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MTS를 이용한 가압기 압력 제어 계통의 조기 고장 감지에 대한 연구
차재민,김준영,신중욱,염충섭,강성기,Cha, Jae-Min,Kim, Joon-Young,Shin, Junguk,Yeom, Choongseob,Kang, Seong-Ki 한국통계학회 2016 응용통계연구 Vol.29 No.7
원자력 발전소의 가압기는 1차 계통의 냉각재가 고온에서도 기화되지 않도록 압력을 가해주는 장치이다. 즉, 가압기의 고장은 원자력 발전소에 큰 영향을 미칠 수 있으며, 따라서, 가압기의 조기 고장 감지는 원자력 발전소의 안전에 매우 중요하다. 이를 위해, 본 연구에서는 마할라노비스 거리 개념과 다구찌 품질 공학 이론에 기반한 패턴 분류 인식 알고리즘 중 하나인 마할라노비스 다구찌 시스템(MTS)을 가압기 압력 제어 계통의 조기 고장 감지에 적용하였다. MTS의 고장 감지 성능을 검증하기 위해, 실제 원자력 발전소에서 발생하고 있는 가압기 압력전송기 고장 시나리오를 대상으로 하여, Full Scope 시뮬레이터를 통해 모사된 데이터에 적용하였다. 실험 결과, MTS는 단일 센서모니터링 기반의 전통적인 고장 감지에 비하여 매우 빠르게 고장을 감지할 수 있었다. A pressurizer is a major equipment system in a nuclear power plant (NPP) and controls the reactor cooling system pressure within the allowable range. Faults in the pressurizer can be critical to the NPP; therefore, early fault detection in the pressurizer is significant for NPP safety. This study applies Mahalanobis Taguchi system (MTS), which is one of the promising pattern classification methods, based on the Mahalanobis distance concept and Taguchi quality engineering theory to the early fault detection problem of the pressurizer pressure control system. We conducted experiments using data from full scope NPP simulator based on a pressurizer pressure transmitter faults scenario to validate the faults detection performance of MTS. As a result, MTS can rapidly detect the faults compared to conventional faults detection based on single sensor monitoring.
원전 상태 감시 및 조기 경보용 빅데이터 시범 플랫폼의 설계를 위한 시스템 엔지니어링 방법론 적용 연구
차재민,손충연,황동식,신중욱,염충섭,Cha, Jae-Min,Shin, Junguk,Son, Choong-Yeon,Hwang, Dong-Sik,Yeom, Choong Sub 한국시스템엔지니어링학회 2015 시스템엔지니어링학술지 Vol.11 No.2
With the era of big data, the big data has been expected to have a large impact in the NPP safety areas. Although high interests of the big data for the NPP safety, only a limited researches concerning this issue are revealed. Especially, researches on the logical/physical structure and systematic design methods for the big data platform for the NPP safety were not dealt with. In this research, we design a new big data pilot platform for the NPP safety especially focusing on health monitoring and early warning services. For this, we propose a tailored design process based on SE approaches to manage inherent high complexities of the platform design. The proposed design process is consist of several steps from elicitate stakeholders to integration test via define operational concept and scenarios, and system requirements, design a conceptual functional architecture, select alternative physical modules for the derived functions and assess the applicability of the alternative modules, design a conceptual physical architecture, implement and integrate the physical modules. From the design process, this paper covers until the conceptual physical architecture design. In the following paper, the rest of the design process and results of the field test will be shown.
Femto Second Laser Pulse에 의한 유리의 결정화 및 기계적 특성
차재민,문필용,김동현,박성제,조성학,류봉기,Cha, Jae-Min,Moon, Pil-Yong,Kim, Dong-Hyun,Park, Sung-Je,Cho, Sung-Rak,Ryu, Bong-Ki 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.6
Generally, the strength achieved of glass-ceramics is higher as is the fracture toughness, as compared with the original glass. This improvement is due to the microstructure consisting of very small crystals. In this study, Ag-doped $45SiO_2-24CaO-24Na_2O-4P_2O_5$ glasses were irradiated to strengthen by the crystallization using Femto second laser Pulses. Through the UV/VIS spectroscope, XRD, Nano-indenter and SEM etc., heat-treated and irradiation of laser pulses without heat-treated samples were analyzed. Two kinds of samples, heat-treated and laser irradiated without heat-treated samples, showed the peaks in the same wavelength near 360 nm. Especially, samples irradiated by 140 mW laser with XYZ stage having at the rate of 100$\~$l000 $\mu$m/s had the largest absorption peak among them, and heat-treated samples was shown lower absorption range than over 90 mW laser irradiated samples. Moreover, samples irradiated by laser had higher values ($4.4\~4.56{\times}10^{-3}(Pa)$) of elastic modulus which related with strength of glass than values of heat-treated samples and these are 1.2$\~$1 .5 times higher values than them of mother glass.
A New Text Entry Method for Smartwatches having Small Screen
Jae-Min Cha(차재민),Eunjung Choi(최은정) (사)한국CDE학회 2015 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2015 No.하계
With the development of IT technology, smartwatches has been one of the important wearable devices which can complement or replace functions of smartphones. However, a smaller screen of smartwatches compare to smartphones is one of the main factors that makes users to input texts difficult. For this, several studies have proposed novel text entry methods for smartwatches but they only proposed a concept for entering texts for smartwatches without usability tests while other studies showed low text input performance. In this study, we proposed a new text entry method called Virtual Sliding QWERTY (VSQ) utilizes a virtual qwerty-layout keyboard and a ‘Tap-N-Drag’ method to move the keyboard to the desired position. In addition, to verify VSQ we conducted a usability test with 20 participants for a combination of 5 key sizes and 4 CD-gains. As a result, VSQ achieved an average of 11.9 Words per Minute which was higher than previous studies.
마할라노비스 다구찌 시스템의 다중 클래스 분류 성능 향상을 위한 새로운 방법
차재민(Jae-Min Cha),김준영(Joon-Young Kim),신중욱(Junguk Shin),염충섭(Choongsub Yeom) 한국IT서비스학회 2016 한국IT서비스학회 학술대회 논문집 Vol.2016 No.추계
Classification between normal and abnormal status of system is one of the important problems in all the industry. Mahalanobis Taguchi System(MTS) that is one of the pattern classification techniques based on mahalanobis distance concept and taguchi quality engineering theory is very efficient for singleclass classification problems; however, it has limitation of accuracy in multiclass classification problems. To overcome this limitation, this study proposes Simultaneous MTS(S-MTS) expanding the concept of the MTS. In the MTS, a single mahalanobis space of normal group is established; however, several mahalanobis spaces per reference group are established in the S-MTS. To validate the performance of the S-MTS, we applied the MTS and the S-MTS to the iris classification problem that is one of the most commonly used pattern classification problems. As a result, the MTS and S-MTS show 96% and 100% of classification accuracy respectively.
Jae-Min Cha(차재민),Choongsub Yeom(염충섭) (사)한국CDE학회 2015 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2015 No.하계
After the era of big data has arrived, the big data technology has been applied to diverse industries including communication, distribution, banking, and so on. With the increasing importanace of the big data in conventional industries, it has also been applied to plant industry recently. This paper reviews the current status of the big data in plant industry, including its concept, cases, applied technologies, analytic methods, and effects. To do this, this paper reviews the existing literatures from oil and gas plant, nuclear power plant. This research is expected to contribute to identify the opportunities of the big data in plant industry.