• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.480-486
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• 2013

In this study, tubular SOFC unit cell with advanced anode current collector was fabricated to improve the cell performance. First, we prepared two types of single cells having the same manufacture processes such as the same electrolyte, electrode coating condition and sintering processes. And then to compare the developed single cell performance with conventional cells, we changed the anode current collecting methods. From the impedance analysis and I-V curve analysis, the cell performance of advanced cell is much higher than that of conventional cell.

• 공학교육연구
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• 제14권3호
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• pp.45-54
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• 2011

The purpose of this study is to analyze performance problems in establishing and improving program educational objectives (PEO) and to set up action strategies for the civil engineering program at the A university. To fulfill the purpose, according to the typical needs analysis model, research problems were defined, current conditions and desired conditions were identified, discrepancies and their reasons were examined, and action strategies were derived. Current conditions and desired conditions were identified by analyzing the A civil engineering program's self study report, conducting surveys and interviews with constituents. After the discrepancies and the reasons were examined, performance problems and field force analysis were conducted to draw short term and long term action strategies to improve PEO. Short term action strategies were to announce PEO to current students, to hold faculty seminars to establish and to improve PEO, to renew the list of constituents regularly, to composite an annual milestone, to define roles of the committees, and to enforce educational opportunity toward industrial advisory board members. For the long term strategies, improvement and documentation of PEO assessment system, collection and analysis of constituents' suggestions, establishment of effective accreditation support system, and arrangement of compensation system for the faculties who are in charge of engineering education accreditation responsibility.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.502-502
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• 2007

전차선로는 각 경간마다 양단으로 지지점을 갖게 되므로 지지점에서의 탄성도와 경간중앙에서의 탄성도가 같을 수 없다. 이 두 지점의 탄성도의 차이를 나타내는 계수로 불균일율이라는 지수가 정의되어 널리 사용되어왔다. 이 불균일율은 전차선 장력과 경간 길이에 크게 영향 받는다. 그러나 드로퍼의 배치 간격에 따라서도 달라진다. 이 불균일율은 전차선로의 동적인 특성을 예측하는 하나의 변수로 활용되고 결국 집전 성능을 상대 비교하여 판단하는데 활용되며, 직접적으로는 드로퍼 간격을 설계하는데 있어서 중요한 파라미터로 사용되고 있다. 그러나 이 불균일율은 전차선로의 동적 성능을 적절히 반영하는 지수가 되지 못하고 있다고 판단하고 있다. 불균일율의 정의인 경간 중앙에서의 탄성율과 경간 끝 지정의 탄성율과의 단순한 차이 값의 크기만으로는 드로퍼의 수와 배치 간격에 따른 특성을 반영하지 못한다고 판단된다. 이를 여러 가지 다양한 케이스를 가정하여 탄성도 해석 프로그램을 이용하여 평가해본다. 평가 결과를 토대로 드로퍼 수에 따른 보정계수를 갖는 새로운 불균일율 평가 지수를 제시하고자 하며 이 새로운 지수가 기존의 지수보다 보다 집전 성능을 판단하는데 유용한 데이터가 됨을 증명한다. 또한 아울러 불균일율이 다른 가선 구조에 대하여 팬터그래프의 1단과 2단의 스프링 계수의 크기와의 조합과 상환 관계에 따른 집전 성능의 차이를 전차선로-팬터그래프 동역학 시뮬레이션 프로그램을 사용하여 평가한다. 이를 통하여 불균일율에 따른 보다 적절한 팬터그래프 동역학 모델을 제시한다.

• 한국산학기술학회논문지
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• 제21권4호
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• pp.268-275
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• 2020

국내 산악 지역 자연공원에서는 자연 환경과 주변 조망을 보존하기 위해 전차선의 설치가 불가하다. 따라서 산악 트램은 무가선으로 운행되어야 한다. 이를 위해 본 연구에서는 차량의 추진 배터리에 전기를 공급할 수 있는 지상 집중식 급전장치를 개발하고 동작 및 기능 시험을 실시하여 성능을 검증하였다. 개발한 지상 집중식 급전장치는 검수고 또는 정거장의 한 지점에 고정 설치되어 있으며, 차량의 대차가 진입하여 정차하면 스프링 장력으로 암과 집전 슈를 올려 대차 하부에 있는 차량측 집전 바와 접촉하고, 전기를 흘려 배터리에 전력을 공급한다. 지상 집중식이므로 차량 지붕 위의 집전장치와 전차선이 필요 없게 되고, 산악트램은 무가선 상태로 운행을 할 수 있다. 정거장이나 검수고에서 움직이지 않고 정지한 상태에서 집전하므로, 이선이나 아크 발생이 없다. 집전 슈의 마모나 손상을 초래할 수 있는 가동 접촉면이 사라지게 되므로 집전장치 수명이 연장되는 장점이 있다. 시험 결과에 따르면, 절연저항은 기준치인 10㏁ 이상이었고, 전류 335A를 1시간 동안 일정하게 공급하여도 이상 발열이 없음을 확인하였다.

• 한국인공지능학회지
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• 제11권4호
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• pp.21-27
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• 2023

This paper discusses a deep learning-based road surface analysis system that collects data by installing vibration sensors on the 4-axis wheel bearings of a vehicle, analyzes the data, and appropriately classifies the characteristics of the current driving road surface for use in the vehicle's control system. The data used for road surface analysis is real-time large-capacity data, with 48K samples per second, and the A2B protocol, which is used for large-capacity real-time data communication in modern vehicles, was used to collect the data. CAN and CAN-FD commonly used in vehicle communication, are unable to perform real-time road surface analysis due to bandwidth limitations. By using A2B communication, data was collected at a maximum bandwidth for real-time analysis, requiring a minimum of 24K samples/sec for evaluation. Based on the data collected for real-time analysis, performance was assessed using deep learning models such as LSTM, GRU, and RNN. The results showed similar road surface classification performance across all models. It was also observed that the quality of data used during the training process had an impact on the performance of each model.

• 한국세라믹학회지
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• 제52권5호
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• pp.356-360
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• 2015

The specific role of current collectors was investigated at the electrolyte/electrode interface of solid oxide fuel cells (SOFCs). Ag grids were fabricated as current collectors using electrohydrodynamic (EHD) jet printing for precise control of the grid geometry. The Ag grids reduced both the ohmic and polarization resistances as the pitch of the Ag grids decreased from $400{\mu}m$ to $100{\mu}m$. The effective electron distribution along the Ag grids improved the charge transport and transfer at the interface, extending the active reaction sites. Our results demonstrate the applicability of EHD jet printing to the fabrication of efficient current collectors for performance enhancement of SOFCs.

• 한국의료질향상학회지
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• 제5권2호
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• pp.224-237
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• 1998

Background : This is an investigative study to analyse the importance of works perceived by Quality Improvement(QI) Coordinators and to evaluate their current work performances using the questionnaires developed by the investigator. Methods : The data were collected from 37 subjects over two weeks period from Oct. 1 to Oct. 17, 1998 and analysed by the descriptive statistics of SPSS program. The items of questionnaire are consisted of 13 work domains including 73 activities based on Quality Management(QM) Coordinator's job description of National Association for Healthcare Quality:data collection & analysis, communication, monitoring, evaluation, accreditation, tool development, policy development, program development, self development, education & trainning, system design, planning, and consultation & support. Results : 1) Of the performances in 13 work domains, the frequencies of the work performed were accreditation(89%), planning(88%), communication(83%), data collection & analysis(82%), monitoring(76%), policy development(72%), consultation & support (71%), education & trainning(70%), self development(68%), evaluation(63%), tool development(61%), program development(44%) and system design(43%) in order. 2) For the importances (1=not important, 5=very important), the policy development(4.46) scored highest then monitoring(4.42), planning(4.41), education & trainning(4.38), communication(4.35), evaluation(4.34) tool development (4.30), data collection & analysis(4.29), program development(4.22), consultation & support(4.22), accreditation(4.15), self development(4.05) and system design(3.98) in order. 3) There was a difference between the work performance and the perceived importance. The results showed the low performances in policy development, monitoring, education & trainning and evaluation which ranked high by the perceived importance and the high performances in accreditation, data collection & analysis, self development, communication and consultation & support which ranked middle to low by the perceived importance. 4) The reasons for low performances of QI Coordinators were the lack of clear assignment for the responsibility and allowed authority for work to QI Coordinators(30.8%), insufficient member of QI Coordinators(13.9%), lack of hospital director's interest(11.5%), low motivation of QI Coordinators (10.6%) and insufficient knowledge & experience of QI Coordinators (8.8%). Conclusion : Most works were perceived important by QI Coordinators, but there was a difference in the work performance. The works performed over 70% were related with accreditation, data collection & analysis, communication, planning and monitoring, on the other hand under 50% in performances were related with system design, program development, tool development and evaluation.

• 전기학회논문지
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• 제63권6호
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• pp.850-854
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• 2014

Analyzing dynamic performance between pantograph and contact wire depends on mechanical and electrical conditions such as contact force, currents, aerodynamics of pantograph and tension of overhead contact wire. For the characteristic of dynamic performance between pantograph and overhead contact wire, various evaluation systems are used to measuring of the interaction of the contact line and the pantograph. Among the various methods, the contact force and percentage of arcing are intended to prove the safety and the quality of the current collection system on the train. However, these methods are only capable of measuring on the train which are installed measurement systems. Therefore in this paper, a track-side monitoring system was implemented to measure electrical characteristics from active overhead contact wire systems in order to constantly estimate current collection performance of railway operation. In addition, a method to analyze loss of contact phenomena was proposed. According to simulation results, the proposed system was capable of measuring abnormal electrical behavior of pantograph and contact wires on the track-side. The advantage of the proposed system is possible to detect loss of contact or any other electrical abnormalities of all types of trains within sections from sub to sub without the need to install any on-board equipment on trains.

• 전기학회논문지
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• 제60권11호
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• pp.2171-2175
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• 2011

The objective of this paper is to discuss technologies on assessing reliability of arc detectors by composing a system that generates and simulates occurrence of arc caused by loss of contact between pantographs and contact wires in a laboratory condition. In order to establish the arc simulator, a device that generates light having the bandwidth of arcs that occur between carbon-metal. The simulator was designed under conditions of EN 50317 and simulations were conducted using the developed device. According to the results, it was possible to conduct certification tests following regulations of international standards and the precision of the simulator was satisfactory. The proposed arc detector assessment system is expected to enhance precision of current collection quality performance assessment methods at high-speed lines and conventional lines while being referred as fundamental technologies for development of detectors suiting international conditions.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.251-260
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• 2000

Seismic performance evaluation systems require rational classification of structure systems, proper evaluation criteria, and their scoring index for synthesis. Current seismic performance systems need expert judgments based on collection of available data, approximate analysis of important items, and various scoring system. This study presents a three-step seismic performance evaluation system for building structures in Korea. Each evaluation step determines the seismic performance and the method depends on the degree of refinement of analysis. The preliminary step evaluation involves the global attributes of structures such as vertical irregularity, asymmetric plan, redundancy, and age of structures. The second step requires an elastic analysis for estimation of forces acting on critical sections and checks the strength and ductility. The final step requires inelastic capacity of structures. Each stephas own evaluation scheme with proper weighing factor dependent on the importance and consequence. This study applies the fuzzy theory to a scoring method that synthesizes the individual quantity to a representative value.