HIGH-PRECISION HIGH-FIDELITY REAL-TIME SIMULATION AND BEHAVIOR PREDICTION METHOD AND DEVICE FOR NUCLEAR POWER STATION
20220405446 · 2022-12-22
Assignee
Inventors
Cpc classification
G06F2119/02
PHYSICS
Y02E30/00
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
Abstract
A high-precision high-fidelity real-time simulation and behavior prediction method and device for a nuclear power station is provided. The method comprises the following steps: (1) constructing a nuclear power station simulator and a physical nuclear power station based on the same design parameters; (2) operating the nuclear power station simulator and the physical nuclear power station in parallel, and obtaining predicted parameters output by the nuclear power station simulator and operation parameters of the physical nuclear power station in real time; (3) comparing the predicted parameters and the operation parameters representing the same physical quantity one by one, and correcting prediction models in the nuclear power station simulator and input parameters of the prediction models by adopting a large-scale concurrent-parallel parameter search and correction algorithm and an artificial intelligence-based mode recognition and correction algorithm until the predicted parameters reach specified precision; and (4) operating the nuclear power station simulator according to a set operation condition to obtain the predicted parameters, thereby completing a behavior prediction of a physical nuclear power station system.
Claims
1. A high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station, wherein the method comprises the following steps: (1) constructing a nuclear power station simulator and a physical nuclear power station based on the same design parameters; (2) operating the nuclear power station simulator and the physical nuclear power station in parallel, and obtaining predicted parameters outputted from the nuclear power station simulator and operation parameters of the physical nuclear power station in real time; (3) comparing the predicted parameters and the operation parameters representing the same physical quantity one by one, and correcting prediction models in the nuclear power station simulator and input parameters of the prediction models by adopting a large-scale concurrent-parallel parameter search and correction algorithm and an artificial intelligence-based mode recognition correction algorithm, and the predicted parameters infinitely approach the operation parameters until their difference reach a specified precision, thereby completing the correction of the nuclear power station simulator; (4) inputting an initial operation condition of a given physical nuclear power station system into the corrected nuclear power station simulator, and operating the nuclear power station simulator to obtain the predicted parameters, thereby completing a behavior prediction of the physical nuclear power station system.
2. The high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station according to claim 1, wherein the step (3) comprises two types of correction modes: a first type of correction mode: keeping each of the prediction models used to predict all the predicted parameters in the nuclear power station simulator unchanged, and correcting the input parameters of the prediction models; a second type of correction mode: correcting some of the prediction models in the nuclear power station simulator, and not correcting the remaining prediction models themselves, but correcting the input parameters of the remaining prediction models.
3. The high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station according to claim 2, wherein the specific correction steps in step (3) comprise: (31) in an initial correction cycle, performing simultaneously and concurrently the two types of correction modes, and performing concurrently a plurality of correction schemes in each type of correction mode, and operating in parallel the nuclear power station simulator according to the plurality of correction schemes to obtain the predicted parameters under each correction scheme; (32) when a next correction cycle is reached, selecting respectively k groups of correction schemes with the top k positions in prediction accuracy in a previous correction cycle, and repeating the correction in step (31) for the k groups of correction schemes respectively; (33) repeating step (32) and the predicted parameters infinitely approach the operation parameters until their differences reach the specified accuracy, and selecting an optimal correction scheme, thereby completing the correction of the nuclear power station simulator.
4. The high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station according to claim 3, wherein a specific correction manner of the first type of correction mode is as follows: firstly, obtaining a prediction parameter set X=(x1, x2, . . . , xn) currently outputted by the nuclear power station simulator, wherein xi represents an i-th predicted parameter, i=1, 2, . . . , n, n represents a total number of the predicted parameters, wherein the first p predicted parameters are physical quantities that can be directly obtained by the physical nuclear power station, and the remaining n-p predicted parameters are physical quantities that cannot be directly obtained by the physical nuclear power station, X=f(EX), wherein EX is a set of the input parameters, and f is the prediction model, EX=(ex1, ex2, ext), ext represents a t-th input parameter, t=1, 2, . . . , t, t represents the total number of the predicted parameters; correspondingly, obtaining an operation parameter set R=(r1, r2, . . . , rn) of the physical nuclear power station, wherein the physical quantities represented by all elements in the set R and the set X are in one-to-one correspondence, the first p operation parameters are the directly obtained operation parameters of the physical nuclear power station, and the rest are given values; then, dividing the set X into m subsets S1, S2, Sm, and simultaneously and correspondingly dividing the set R into m subsets RS1, RS2, RSm, and comparing Sj and RSj one by one, wherein j=1, 2, . . . , m, wherein Sj corresponds to some of the input parameters in the input parameter set, said input parameters are recorded as EXSj, the parameter search and correction algorithm is used to correct the input parameter set EX, and all the prediction models are not corrected.
5. The high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station according to claim 4, wherein a correction manner of the input parameter set EX is as follows: determining a correction value set EXSRaj of EXSj according to the error between Sj and RSj; and constituting a total set of input parameter correction values EXSRZ1=(EXSR0, EXSRa1, EXSRa2, . . . , EXSRam), wherein EXSR0 is a set of all input parameters in EX that do not correspond to any Sj; thereby completing the correction of the input parameters.
6. The high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station according to claim 5, wherein the specific manner of performing concurrently a plurality of correction schemes in the first type of correction mode is as follows: taking a total set of input parameters correction values EXSRZ1 as one group of correction scheme, and randomly generating N groups of input parameter correction value expansion sets EXSRZ1′ based on the total set of input parameter correction values EXSRZ1 and the input parameter set EX to form N groups of correction schemes; a constitution manner of EXSRZ1′ is as follows: generating N groups of random number sequences ROMn, wherein each random number sequence contains t random numbers romt, the random variation range of romt is (0, z), z is an over-correction coefficient, and the value of z is 1˜2, letting the input parameter correction values exsrt∈EXSRZ1, selecting a group of random number sequence ROMt, then any correction value in the corresponding input parameter correction value expansion set EXSRZ1′ being exsrz1t=romt*exsrt, generating one expansion set EXSRZ1′; and using N groups of random number sequences to perform the above operations so as to obtain N groups of input parameter correction value expansion sets EXSRZ1′.
7. The high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station according to claim 3, wherein the specific correction mode of the second type of correction mode is as follows: firstly, obtaining a prediction parameter set X=(x1, x2, . . . , xn) currently outputted by the nuclear power station simulator, where xi represents an i-th predicted parameter, i=1, 2, . . . , n, n represents a total number of the predicted parameters, wherein the first p predicted parameters are physical quantities that can be directly obtained by the physical nuclear power station, and the remaining n-p predicted parameters are physical quantities that cannot be directly obtained by the physical nuclear power station, X=f(EX), where EX is a set of the input parameters, and f is the prediction model, EX=(ex1, ex2, ext), ext represents a t-th input parameter, t=1, 2, . . . , t, t represents the total number of the predicted parameters; correspondingly, obtaining an operation parameter set R=(r1, r2, . . . , rn) of the physical nuclear power station, wherein the physical quantities represented by all elements in the set R and the set X are in one-to-one correspondence, the first p operation parameters are the directly obtained operation parameters of the physical nuclear power station, and the rest are given values; then, dividing the set X into m subsets S1, S2, . . . , Sm, and simultaneously and correspondingly dividing the set R into m subsets RS1, RS2, . . . , RSm, and comparing Sj and RSj one by one, j=1, 2, . . . , m, if a subset Sj of which the contrast error of Sj and RSj remains unchanged or continuously increases in time step of continuous multi-steps is denoted as Sj′, and the rest is denoted as Sj″, and Sj′ corresponds to some of the input parameters in the input parameter set, then denoting said some of the input parameters as EXSj′, denoting the input parameters corresponding to Sj″ as EXSj″, denoting the operation parameters corresponding to Sj′ as RSj′, and denoting the operation parameters corresponding to Sj″ as RSj″, and further, correcting the input parameters EXSj′ and the prediction models corresponding to Sj′ by the artificial intelligence-based mode recognition method, and correcting the input parameters EXSj″ corresponding to Sj″ by the parameter search and correction algorithm, while not correcting the prediction models corresponding to Sj″, thereby finally completing the correction of the input parameter set EX and the correction of some of the prediction models.
8. The high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station according to claim 7, wherein, the correction of the input parameter EXSj′ and the prediction models corresponding to Sj′ are specifically as follows: for Sj′, utilizing the artificial intelligence-based mode recognition method, Sj′ infinitely approaching RSj′, as a target, and directly correcting EXSj′ to obtain a set of correction values EXSRbj′, at the same time, replacing the prediction models obtaining Sj′ with an artificial intelligence recognition model which directly obtains a prediction result according to EXSRbj′; the correction of the input parameters EXSj″ corresponding to Sj″ is specifically as follows: for Sj″, determining the set of correction values EXSRaj″ of EXSj″ according to the error between Sj″ and RSj″; finally, constituting the total set of input parameter correction values EXSRZ2=(EXSR0′, EXSRb1′, EXSRb2′, . . . , EXSRbp′, EXSRa1″, EXSRa2″, . . . , EXSRaq″), where EXSR0′ is a set of all input parameters not corresponding to any Sj in EX, p is a total number of input parameter subsets corrected by the artificial intelligence-based mode recognition method, q is a total number of input parameter subsets corrected by the parameter search and correction algorithm, p+q=m.
9. The high-precision high-fidelity real-time simulation and behavior prediction method for a nuclear power station according to claim 8, wherein the specific manner of performing concurrently a plurality of correction schemes in the second type of correction mode is as follows: taking a total set of input parameters correction values EXSRZ2 as one group of correction scheme, and randomly generating N groups of input parameter correction value expansion sets EXSRZ2′ based on the total set of input parameter correction values EXSRZ2 and the input parameter set EX to form N groups of correction schemes; a constitution manner of EXSRZ2′ is as follows: generating N groups of random number sequences ROMn, wherein each random number sequence contains t random numbers romt, the random variation range of romt is (0, z), z is an over-correction coefficient, and the value of z is 1˜2, letting the input parameter correction values exsrt∈EXSRZ2, selecting a group of random number sequence ROMt, then any correction value in the corresponding input parameter correction value expansion set EXSRZ2′ being exsrz2t=romt*exsrt, generating one expansion set EXSRZ2′, and using N groups of random number sequences to perform the above operations so as to obtain N groups of input parameter correction value expansion sets EXSRZ2′.
10. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 1.
11. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 2.
12. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 3.
13. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 4.
14. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 5.
15. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 6.
16. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 7.
17. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 8.
18. A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the method according to claim 9.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0037]
DESCRIPTION OF EMBODIMENTS
[0038] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. Note that the description of the following implementations is merely an example in nature, and the present invention is not intended to limit its application or its use, and the present invention is not limited to the following implementations.
Embodiments
[0039] As shown in
[0040] (1) constructing a nuclear power station simulator and a physical nuclear power station based on the same design parameters;
[0041] (2) operating the nuclear power station simulator and the physical nuclear power station in parallel, and obtaining predicted parameters output by the nuclear power station simulator and operation parameters of the physical nuclear power station in real time;
[0042] (3) comparing the predicted parameters and the operation parameters representing the same physical quantity one by one, and correcting prediction models in the nuclear power station simulator and input parameters of the prediction models by adopting a large-scale concurrent-parallel parameter search and correction algorithm and an artificial intelligence-based mode recognition correction algorithm, and the predicted parameters infinitely approach the operation parameters until their differences reach specified precision, thereby completing the correction of the nuclear power station simulator;
[0043] (4) inputting an initial operation condition of a given physical nuclear power station system into the corrected nuclear power station simulator, and operating the nuclear power station simulator to obtain the predicted parameters, thereby completing a behavior prediction of the physical nuclear power station system.
[0044] The predicted parameters output by the nuclear power station simulator comprise, but are not limited to, thermal hydraulics, nuclear physical parameters and design parameters such as circulation, materials, operation control and safety of the nuclear power station. The thermal hydraulic parameters are such as pressure, flow, inlet and outlet temperatures of primary and secondary circuits. The nuclear physical parameters are such as fuel enrichment, geometric dimensions of fuel rods, components and core components, fuel cycle period and component layout design, core structure materials, control rod materials and geometric structures, design parameters for start-up reactors, temperature and pressure for normal operation, as well as the pressure, temperature and materials of the safety equipment, the relevant threshold conditions of the safety equipment. Among them, some of the parameters can be directly measured by the physical nuclear power station (that is, the operation parameters of the physical nuclear power station described above), and some cannot be measured. The purpose of the correction in the present invention is to enable the predicted parameters output by the nuclear power station simulator and the actual state of the physical nuclear power station (comprising the above-mentioned measurable operation parameters of the physical nuclear power station and some unmeasurable operation parameters) to be kept parallel and consistent.
[0045] Step (3) comprises two types of correction modes:
[0046] a first type of correction mode: remaining each of the prediction models used to predict all the predicted parameters in the nuclear power station simulator unchanged, and correcting the input parameters of the prediction models;
[0047] a second type of correction mode: correcting some of the prediction models in the nuclear power station simulator, and not correcting the remaining prediction models themselves, but correcting the input parameters of the remaining prediction models.
[0048] The specific correction steps in step (3) comprises:
[0049] (31) in an initial correction cycle, performing simultaneously and concurrently the two types of correction modes, and performing concurrently a plurality of correction schemes in each type of correction mode, and operating in parallel the nuclear power station simulator according to the plurality of correction schemes to obtain the predicted parameters under the correction scheme;
[0050] (32) when a next correction cycle is reached, selecting respectively k groups of correction schemes with the top k positions in prediction accuracy in a previous correction cycle, and repeating the correction in step (31) for the k groups of correction schemes respectively;
[0051] (33) repeating step (32) and the predicted parameters infinitely approach the operation parameters until their differences reach the specified accuracy, and selecting an optimal correction scheme, thereby completing the correction of the nuclear power station simulator.
[0052] A specific correction manner of the first type of correction mode is as follows:
[0053] Firstly, obtaining a prediction parameter set X=(x1, x2, . . . , xn) currently output by the nuclear power station simulator, where xi represents an i-th predicted parameter, i=1, 2, . . . , n, n represents a total number of the predicted parameters, wherein the first p predicted parameters are physical quantities that can be directly obtained by the physical nuclear power station, and the remaining n-p predicted parameters are physical quantities that cannot be directly obtained by the physical nuclear power station, X=f(EX), where EX is a set of the input parameters, and f is the prediction model, EX=(ex1, ex2, . . . , ext), ext represents a t-th input parameter, t=1, 2, . . . , t, t represents the total number of the predicted parameters.
[0054] Correspondingly, obtaining an operation parameter set R=(r1, r2, . . . , rn) of the physical nuclear power station, wherein the physical quantities represented by all elements in the set R and the set X are in one-to-one correspondence, the first p operation parameters are the directly obtained operation parameters of the physical nuclear power station, and the rest are given values, wherein the corresponding predicted parameters output by the nuclear power station simulator at the last moment can be selected as the given values. At the initial moment, the given values can be 0;
[0055] Then, dividing the set X into m subsets S1, S2, . . . Sm, and simultaneously and correspondingly dividing the set R into m subsets RS1, RS2, . . . , RSm, and comparing Sj and RSj one by one, wherein j=1, 2, . . . , m, wherein Sj corresponds to some of the input parameters in the input parameter set, said input parameters are recorded as EXSj, the parameter search and correction algorithm is used to correct the input parameter set EX, and all the prediction models are not corrected. Among them, the classification of the set X can be based on the traditional “phenomenon sorting table” method of nuclear engineering, starting from the system-equipment-phenomenon multi-level classification, and under the physical phenomenon, specific categories such as thermal hydraulics, nuclear physics, materials, control, operation, fuel cycle, safety, etc. are collected according to subject category.
[0056] Among them, a correction manner of the input parameter set EX is as follows: determining a correction value set EXSRaj of EXSj according to the error between Sj and RSj; and constituting a total set of input parameter correction values EXSRZ1=(EXSR0, EXSRa1, EXSRa2, . . . , EXSRam), where EXSR0 is a set of all input parameters in EX that do not correspond to any Sj; thereby completing the correction of the input parameters. The specific manner of performing concurrently a plurality of correction schemes in the first type of correction mode is as follows: taking the total set of input parameter correction values EXSRZ1 as one group of correction scheme, and randomly generating N groups of input parameter correction values expansion sets EXSRZ1′ based on the total set of input parameter correction values EXSRZ1 and the set of input parameters EX to form N groups of correction schemes; constitution manner of EXSRZ1′ is as follows: generating N groups of random number sequences ROMn, wherein each random number sequence contains t random numbers romt, the random variation range of romt is (0, z), z is an over-correction coefficient, and the value of z is 1˜2, letting the input parameter correction values exsrt∈EXSRZ1, selecting a group of random number sequence ROMt, then any correction value in the corresponding input parameter correction value expansion set EXSRZ1′ being exsrz1t=romt*exsrt, generating one expansion set of EXSRZ1′; and using N groups of random number sequences to perform the above operations so as to obtain N groups of input parameter correction value expansion sets EXSRZ1′. Therefore, N+1 groups of correction schemes are concurrently performed.
[0057] The specific correction manner of the second type of correction mode is as follows:
[0058] Firstly, obtaining a prediction parameter set X=(x1, x2, . . . , xn) currently output by the nuclear power station simulator, where xi represents an i-th predicted parameter, i=1, 2, . . . , n, n represents a total number of the predicted parameters, wherein the first p predicted parameters are physical quantities that can be directly obtained by the physical nuclear power station, and the remaining n-p predicted parameters are physical quantities that cannot be directly obtained by the physical nuclear power station, X=f(EX), where EX is a set of the input parameters, and f is the prediction model, EX=(ex1, ex2, . . . , ext), ext represents a t-th input parameter, t=1, 2, . . . , t, t represents the total number of the predicted parameters.
[0059] Correspondingly, obtaining an operation parameter set R=(r1, r2, . . . , rn) of the physical nuclear power station, wherein the physical quantities represented by all elements in the set R and the set X are in one-to-one correspondence, the first p operation parameters are the directly obtained operation parameters of the physical nuclear power station, and the rest are given values;
[0060] Then, dividing the set X into m subsets S1, S2, . . . Sm, and simultaneously and correspondingly dividing the set R into m subsets RS1, RS2, . . . , RSm, and comparing Sj and RSj one by one, j=1, 2, . . . , m, if a subset Sj of which the contrast error of Sj and RSj remains unchanged or continuously increases in time step of continuous multi-steps is denoted as Sj′, and the rest is denoted as Sj″, and Sj′ corresponds to some of the input parameters in the input parameter set, then denoting said some of the input parameters as EXSj′, denoting the input parameters corresponding to Sj″ as EXSj″, denoting the operation parameters corresponding to Sj′ as RSj′, and denoting the operation parameters corresponding to Sj″ as RSj″, and further, correcting the input parameters EXSj′ and the prediction models corresponding to Sj′ by the artificial intelligence-based mode recognition method, and correcting the input parameters EXSj″ corresponding to Sj″ by the parameter search and correction algorithm, while not correcting the prediction models corresponding to Sj″, thereby finally completing the correction of the input parameter set EX and the correction of some of the prediction models.
[0061] Sj′ The correction of corresponding input parameters EXSj′ and the prediction models are specifically as follows: for Sj′, utilizing the artificial intelligence-based mode recognition method, with Sj′ infinitely approaching, RSj′ as a target, and directly correcting EXSj′ to obtain a set of correction values EXSRbj′, at the same time, replacing the prediction models obtaining Sj′ with an artificial intelligence recognition model, which directly obtains a prediction result according to EXSRbj′; the correction of the input parameters EXSj″ corresponding to Sj″ is specifically as follows: for Sj″, determining the correction value set EXSRaj″ of EXSj″ according to the error between Sj″ and RSj″; finally, constituting the total set of input parameter correction values EXSRZ2=(EXSR0′, EXSRb1′, EXSRb2′, . . . , EXSRbp′, EXSRa1″, EXSRa2″, . . . , EXSRaq″), where EXSR0′ is a set of all input parameters not corresponding to any Sj in EX, p is the total number of input parameter subsets corrected by the artificial intelligence-based mode recognition method, q is the total number of input parameter subsets corrected by the parameter search and correction algorithm, p+q=m. The specific manner of performing concurrently a plurality of correction schemes in the second type of correction mode is as follows: taking the total set of input parameter correction values EXSRZ2 as one group of correction scheme, and randomly generating N groups of input parameter correction value expansion sets EXSRZ2′ based on the total set of input parameter correction values EXSRZ2 and the set of input parameters EX to form N groups of correction schemes; constitution manner of EXSRZ2′ is as follows: generating N groups of random number sequences ROMn, wherein each random number sequence contains t random numbers romt, the random variation range of romt is (0, z), z is an over-correction coefficient, and the value of z is 1˜2, letting the input parameter correction values exsrt∈EXSRZ2, selecting a group of random number sequence ROMt, then any correction value in the corresponding input parameter correction value expansion set EXSRZ2′ being exsrz2t=romt*exsrt, generating one expansion set EXSRZ2′, and using N groups of random number sequences to perform the above operations so as to obtain N groups of input parameter correction value expansion sets EXSRZ2′. Therefore, N+1 groups of correction schemes are concurrently performed.
[0062] The specific implementation process of step (3) is as follows: referring to
[0063] After completing the correction of the nuclear power station simulator in step (3), it also comprises the cause diagnosis and calculation of the specific behavior results of the nuclear power station, that is, using the combination of specific measurement parameters of the nuclear power station (such as the output parameters at the accident transient) as a target R, through the step in above (3), using the obtained optimized prediction models to determine the prediction parameter combination X that is closest to the target R, and the corresponding input parameter combination EX is the diagnosed power station state (cause of the accident).
[0064] A high-precision high-fidelity real-time simulation and behavior prediction device for a nuclear power station, wherein the device comprises a memory and a processor, the memory is used to store a computer program, and the processor is used to, when the computer program is executed, realize the above methods.
[0065] The foregoing implementations are only examples, and do not limit the scope of the present invention. These implementations can also be implemented in other various ways, and various omissions, substitutions, and changes can be made without departing from the scope of the technical idea of the present invention.