유사장치의 건전성데이터 분석을 통한 수소충전소 기능안전 추론방안

오봉식(Bong S. Oh),박상철(Sang C. Park),장중순(Joong S. Jang) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.4

Purpose: There has been a substantive expansion of FCEV in the hydrogen economy. According to the government’s policy, the installation and operation of HRSs (Hydrogen Refueling Station) are expected to be carried out rapidly. However, the types of failures among the major devices of HRS such as compressors, coolers, and dispensers, and technologies related to the safety and reliability of data are not well disclosed. In the case of foreign (Germany, France, etc.) products of HRS in Korea, it is not easy to access technology, and to reduce risks in operating HRS, it is necessary to solve the problem in this area. Methods: HRSs are required to have the highest level of safety and reliability, but due to certain terms and conditions among suppliers, the main characteristics of the technology are not openly available. Based on the analysis done, in this paper we suggest improvement plans to curb the problems mentioned above. Results: PHM(Prognostics and Health Management) through failure type analysis of similar devices and safety-based real-time risk severity rating of HRS through technology that collects, analyzes, and evaluates and judges functional safety real-time safety risk data based on operational data are extremely important. A monitoring technique was presented to collect results through the methods mentioned above. Conclusion: In order to secure safety for safety-based risk reduction for an HRS’s operation, site selection for an HRS that meets functional safety and construction requirements is needed. It is also important that the required technology selected for this purpose, presented by the HRS standard, be applied to design. In addition, post-maintenance technology that can sustain risk reduction is also required.

레이저프린터 스캐닝지터의 자동검사

장중순(Joong Soon Jang),엄윤섭(Y . S . Um),최경희(K . H . Choi),이정태(J . T . Lee) 대한설비관리학회 1996 대한설비관리학회지 Vol.1 No.1

N/A An automatic measuring system for scanning jitters of laser beam printers is developed. Scanning jitters are critical defects for high resolution printing. Two types of scanning jitters are possible' horizontal and vertical. Horizontal jitters are mainly

실시간 감시를 통한 교통신호제어기의 열화 감지

김은영,장중순,오봉식,박상철,Kim, Eun Y.,Jang, Joong S.,Oh, Bong S.,Park, Sang C. 한국신뢰성학회 2018 신뢰성응용연구 Vol.18 No.2

Purpose: A traffic signal controller needs to control and coordinate to ensure that traffic and pedestrians move as smoothly as possible. Since a traffic signal controller has a significant impact on the safety of vehicles and pedestrians, it is important to monitor the failure and deterioration of the traffic signal controller. The purpose of this paper is to propose an IoT (Internet of Things)-based monitoring system for a traffic signal controller. Methods: Every traffic signal controller has a nominal system trajectory specified when it is deployed. The proposed IoT-based monitoring system collects the system trajectory information through real-time monitoring. By comparing the nominal system trajectory and the monitored system trajectory, we are able to detect the failure and deterioration of the traffic signal controller. Conclusion: The proposed IoT-based monitoring system can contribute to the safety of vehicles and pedestrians by maximizing the availability of a traffic signal controller.

수소충전소 설비운영 안전관리 상용화를 위한 CBM+활용 방안 연구

오봉식(Bong S. Oh),신덕식(Duck S. Shin),이용훈(Yong H. Lee),장중순(Joong S. Jang) 한국신뢰성학회 2023 신뢰성응용연구 Vol.23 No.1

Purpose: This study aims to meet the functional safety requirements using condition-based maintenance plus (CBM+) to ensure the safe operation of equipment, such as chillers, compressors, and dispensers, used in hydrogen refueling facilities. Methods: For the commercialization of the safety management of hydrogen refueling stations, we demonstrate an approach for detecting equipment abnormalities during operation by measuring sound, vibration, and current. CBM+ is used for fault diagnosis; the results are compared with those of the traditional fault diagnosis methods. Results: At hydrogen refueling stations in South Korea, 90.48% of accidents occurred due to hydrogen leakage from 2005 to 2014. During the same period, 7 (31.82%) out of 22 such accidents were caused by human errors in the United States. Through structural analysis of vertical axis, lateral sides, and height of the hydrogen charging stations, we propose a method that uses sensor nodes, sensor systems, and communication systems for CBM+. Conclusion: Only a few empirical studies have reported the use of CBM+ for hydrogen refueling stations in South Korea. Effective strategies for CBM+ have also not been presented. Through technical research and institutional improvement, including this study, it is necessary to secure functional safety and PHM technology for CBM for the safe operation of hydrogen refueling stations in South Korea. In addition, data based on several factors, including the equipment component type, failure, and safety risk level, must be acquired in a standard format. However, to eliminate the safety risks of hydrogen refueling stations, hydrogen leakage accidents must be primarily avoided.

수소충전소 압축기의 CBM+ 데이터수집을 위한 기술개발

오봉식(Bong S. Oh),신덕식(Duck S. Shin),이용훈(Yong H. Lee),장중순(Joong S. Jang) 한국신뢰성학회 2023 신뢰성응용연구 Vol.23 No.1

Purpose: This paper demonstrates Functional Safety Requirements by collecting and analyzing the condition-based maintenance (CBM+) data of the compressors such as chillers, compressors, and dispensers of a hydrogen refueling station (HRS) installation as well as HRS operation using power quality monitoring (PQM) instrumentation at the HRS input stage. Methods: Demonstrate fault measurement items and fault diagnosis such as sound, vibration, and current with CBM+. The feature extraction of the collected data in this process was analyzed using an LSTM AutoEncoder to demonstrate the occurrence of failures. Results: There were a total of 21 HRS accidents from 2005 to 2014 in Japan and 22 accidents in the US from 2004 to 2012. In particular, approximately 90% of the hydrogen gas leakage accidents in Japan and approximately 91% in the US were due to human error. The CBM+ of a hydrogen compressor was demonstrated by connecting a PQM instrument to the HRS input. Conclusion: A technically developed PQM measuring device was installed at the Gwangju HRS input power source and data was collected for approximately 3 months. After analyzing and evaluating the collected data through the LSTM AutoEncorder, it was demonstrated that HRS failure occurred after approximately 7 days. Therefore, we propose a failure detection and failure diagnosis model through the CBM+ of domestic HRSs.

교통신호제어기 신뢰성 규격 비교와 예측

오봉식(Bong S. OH),박상철(Sang C. Park),장중순(Joong S. Jang) 한국신뢰성학회 2019 한국신뢰성학회 학술대회논문집 Vol.2019 No.10

Purpose: Maintenance data for Korean traffic signal controller (TSC) shows that the replacement life is shorter than 10 years required. To investigate the causes, Korean and international TSC reliability standards are compared and MTBF of TSC is evaluated. Methods: Reliability test items of Korean, US, European, and Japanese TSC standards are compared as well as their test conditions. In addition, failures rates of main control unit CPU boards of 2 main control unit are evaluated based on MIL-HDBK-217F. Conclusion: Korean TSC standard requires less test items than EU, US and Japan. Some important tests like solar test, salt spray test, gas test and storage test are not specified. MTBFs of 2 CPU boards are evaluated to be less than 10 years.

기능안전 기반 스마트팩토리 MQTT통신시스템 개발

오봉식(Bong S. Oh),박상철(Sang C. Park),장중순(Joong S. Jang),이정준(Jung J. Lee) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.3

Purpose: Reliability and safety-based message queuing telemetry transport (MQTT) communication applications and artificial intelligence (AI)-smart sensor development are considered in the smart factory to ensure competitiveness by minimizing risks in manufacturing, pre-failure diagnosis, and failure prediction prognostics and health management (PHM) technology. Methods: The algorithm was implemented to ensure that the MQTT Publisher software technology application conforms to the standard by applying it as a process design method in the smart factory. In the functional safety standard and reliability prediction methods, safety risk data were collected, analyzed, and verified as an evaluation procedure in the smart factory. Results: The performance of MQTT communication as well as the safety data collection and database (DB) storage functions were confirmed in the smart factory. The contents of the literature search were confirmed in relation to the evaluation of the reliability feature extraction factors and functional safety-related failure prognosis parameters of the AI-smart sensor, center control server, monitoring-related design, and development products to be used as the basis for reliability and safety in smart factories. Conclusion: The process of sensor input using Arduino, the transmission of measured values, and storage of collected data into a DB using the resistive temperature device was developed as a software algorithm and demonstrated in the smart factory using MQTT communication. According to a literature search related to priority-based MQTT, this partial application can be effectively used in small and medium-sized smart factories that require a real-time priority algorithm. It can be used as a price-competitive communication method.

스마트센서시스템의 기능안전을 위한 Lora 통신 필드 적합성 테스트 연구

오봉식(Bong S. Oh),박상철(Sang C. Park),장중순(Joong S. Jang),이정준(Jung J. Lee) 한국신뢰성학회 2022 신뢰성응용연구 Vol.22 No.2

Purpose: Three types of LPWA LoRa module were investigated as candidate smart sensor systems in a smart factory. A long-distance communication success test was conducted to determine which module type best satisfied functional safety requirements. Methods: The three types of LoRa communication module considered in this paper were 1. sLory, 2. RYLR890 using UART interface and 3. P2P UART communication module RAK811. A communication success field demonstration test was performed at 3.24 km in the city center and in a flat area (Ansan-si). Results: The RYLR890 module type achieved communication success up to 3 km. However, the communication success rate from departure to arrival was unstable. The RAK811 achieved communication up to 2 km and the field test demonstrated that the transmission/reception performance was stable from departure to arrival. Conclusion: Three types of LoRa module were selected for LPWA and the worlds first field verification test was conducted. It was verified that the RAK811 model’s field communication success rate meets functional safety requirements. However, it is still necessary to ensure the functional safety of sensor-node, communication system and PHM technology by examining structural aspects such as longitudinal axis, lateral side and height.

원샷 시스템의 저장 신뢰성 추정 정확성에 대한 샘플링 시점의 영향 분석

정용호(Yong H. Chung),오봉식(Bong S. Oh),이홍철(Hong C. Lee),박희남(Hee N. Park),장중순(Joong S. Jang),박상철(Sang C. Park) 한국신뢰성학회 2016 신뢰성응용연구 Vol.16 No.1

Purpose: The purpose of this study is to analyze the effect of sampling points on accuracy of storage reliability estimation for one-shot systems by assuming a weibull distribution as a storage reliability distribution. Also propose method for determining of sampling points for increase the accuracy of reliability estimation. Methods: Weibull distribution was divided into three sections for confirming the possible to estimate the parameters of the weibull distribution only some section’s sample. Generate quantal response data for failure data. And performed parameter estimation with quantal response data. Results: If reduce sample point interval of 1 section, increase the accuracy of reliability estimation although sampling only section 1. Even reduce total number of sampling point, reducing sampling time interval of the 1 zone improve the accuracy of reliability estimation. Conclusion: Method to increase the accuracy of reliability estimation is increasing number of sampling and the sampling points. But apply this method to One-shot system is difficult because test cost of one-shot system is expensive. So propose method of accuracy of storage reliability estimation of one-shot system by adjustment of the sampling point. And by dividing the section it could reduce the total sampling point.

의약품 사용기간 평가 기법을 활용한 원샷시스템의 최초시험 연수 결정

박지명(Ji M. Park),이홍철(Hong C. Lee),장중순(Joong S. Jang),박상철(Sang C. Park) 한국신뢰성학회 2017 신뢰성응용연구 Vol.17 No.1

Purpose: This study aims at omitting the initial testing of the ASRP by determining the initial test year. Methods: This study is to determine of the initial test year for one-shot system using validity assessment of drugs. Results: Procedures for determining the initial test duration of the one shot system and examples of omitting the tests are presented. Conclusion: Using this method, the time and labor required for testing can be saved by omitting the initial testing of ASRP.