• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.2
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• pp.43-50
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• 2008

ICAO(International Civil Aviation Organization) Doc 9803의 국제규정에 의거하여 SMS(Safety Management System-안전관리시스템)의 대표적인 비행안전 모니터링 프로그램으로 인정된 신개념의 운항감사제도인 LOSA(Line Operations Safety Audit-항공운항 안전감사)를 항공사에서 실시하여 정상 운항시의 운항승무원을 관찰하여 실제의 안전취약 및 위협요소, Error를 포착하여 텍사스대학 인적요인 연구소에서 작성한 최종보고서의 분석을 통해 제도와 방안을 개선한다. 본 논문에서는 LOSA실행을 통한 승무원들의 위협 및 error의 유형과 발생율, 관리율 및 관리여부를 분석하여 설명하고 항공사내 개선인 SCP(Safety Change Process)를 소개하는데 있다.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.417-420
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• 2007

A 12k-bit SRAM has been developed for line memory of system-on-glass (SoG) with lowtemperature poly-silicon (LTPS) thin film transistor (TFT). For accurate sensing even with the large variation and mismatches in the characteristics of LTPS TFT, mismatch immune sense amplifier is developed. The SRAM shows 30ns read access time with 7V supply voltage while dissipating 4.05mW and 1.75mW for write and read operation, respectively

• Journal of the Korea Society for Simulation
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• v.12 no.1
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• pp.21-34
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• 2003

This paper deals with a case study of workload analysis of an operator in an automatic line for machining the race of ball bearing. Eleven machines and three hoppers are installed in the line which is operated by an operator. The elements of operation are separated into machine controlled elements, operator controlled elements and machine/operator controlled elements. In order to analyze the system, time and motion studies are used for gathering input data for the simulation model. The first objective of this study is to evaluate whether the workload of operator is reasonable or not. The second objective is to increase throughput by reducing tact time and the last one is to increase frequencies of inspection by reducing interval. Thus we suggest some ideas for improvement, and as a result, the throughput is improved about 9%. In spite of the increasing of throughput, the allowance of operator is also increased about 4%.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1375-1384
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• 2014

Flashover of power transmission line insulators is a major threat to the reliable operation of power system. This paper deals with the flashover prediction of polymeric insulators used in power transmission line applications using the novel condition monitoring technique developed by PD signal time-frequency map and neural network technique. Laboratory experiments on polymeric insulators were carried out as per IEC 60507 under AC voltage, at different humidity and contamination levels using NaCl as a contaminant. Partial discharge signals were acquired using advanced ultra wide band detection system. Salient features from the Time-Frequency map and PRPD pattern at different pollution levels were extracted. The flashover prediction of polymeric insulators was automated using artificial neural network (ANN) with back propagation algorithm (BPA). From the results, it can be speculated that PD signal feature extraction along with back propagation classification is a well suited technique to predict flashover of polymeric insulators.

• Journal of Power Electronics
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• v.14 no.3
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• pp.572-579
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• 2014

As a non-linear time variant system, the four-quadrant line converter of an electric multiple unit (EMU) was expressed by linear time periodic functions near an operating point and modeled by a steady-state harmonic domain matrix. The components were then combined according to the circuit connection and relations of the feedback control loops to form a complete converter model. The proposed modeling method allows the study of the amplitude of harmonic impedances to explore harmonic coupling. Moreover, the proposed method helps provide a better design for the converter controllers, as well as solves the problem in coordination operation between the EMUs and the AC supply. On-site data from an actual $CRH_2$ high-speed train were used to validate the modeling principles presented in the paper.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.305-307
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• 2005

In the cold and temperate regions of Korea the icing and ice coats on 25[kV] electric car line during winter is a very serious problem. This generates shocks at the mechanical interface of the collecting strips of the pantograph and the contact wire and extra electrical resistance, which may affect quality of current collection at the contact wire / collecting strips of pantograph interface. De-icing operations should be performed just before train operation to avoid the formation of another ice layer. This paper presents temperature analysis of the de-icing system which could be applied to the electric car line of railways.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.60-62
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• 2004

Transmission line outage is influenced by several weather factors: wind, rain snow, temperature, cloud and humidity. And most power system reliability studies assume a failure rate. It can be calculated by transmission line outage data and weather data. Also weather is divided into normal weather and adverse weather by failure rate analysis. The effect of failure rate is discussed with both normal weather and adverse weather. It can be used in effective information about system operation and planing.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.156-159
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• 1991

At LCCSI system, output capacitor of inverter and inductor of load motor raise mutuality operation. This parallel resonant increase equivalent impedance of inverter load and give wrong effect at LCCSI system. This paper carried out resonant analysis of LCCSI system. The result of analysis, particular resonant point of two was discovered that a resonant of S=0 vicinity and $\beta$ resonant of S=1 vicinity. In addition to, the case of harmonics resonant not come from $\alpha$ resonant but come from $\beta$ resonant. A moment of working of LCCSI system, resonant line must not suddenly variation. Accordingly, resonant line is a necessity for doing $f{\alpha}$ vicinity by properly capacitor value selection.

• IE interfaces
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• v.12 no.3
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• pp.374-381
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• 1999

In this paper, we propose an architecture of the DNC system for Shop Floor Control/Point of Production(SFC/POP). The DNC system to be presented this paper retrieves line-up sheets which include the drawing information, making a index database for line-up sheets, NC programs and tool adjustment data. And it is interface with a raw material, jig and tool information. Also, the DNC system transmits operation information to real workers rapidly, and supports realtime monitoring by collecting the state information of machines directly. In the analysis and design phases, this paper models realtime events using the state transition diagrams. In the implementation phase, we use the ORACLE DBMS(Database Management System) as the DBMS and Developer 2000 and Microsoft Visual C++ 5.0 as the programming tools.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.95-96
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• 2008

We constructed an on-line PD monitoring system for the 380kV U/G Cable project at the Riyad 9012 substation in Saudi-arabia. The system will be monitoring the termination of the two 380kV XLPE Cables to prevent unexpected failure of the cable insulation. The system had been tested in the laboratory and on-site for detection of various PD signals and reliability of operation. The system distinguish the existence and nonexistence of the partial discharge and then judge the source of partial discharge using automatic PD pattern recognition software.