• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.71-72
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• 2006

This paper introduces the results of the development of a new mobile Digital DC-arc Welding Machine (DDWM). A simple PI controller is applied to the DDWM to control the output welding current tracking the constant setting current. Furthermore, a hot-start function, an anti-stuck function, a standby mode and an intelligential circuit breaker (ICB) are included in the DDWM. The DDWM increases welding quality and saves more power energy than a conventional welding machine. Because the DDWM is changed from ready mode into the standby mode automatically after 2 minutes interval from this unload start. Then the DDWM is changed into ready mode automatically since it is reused to weld. Mover, the DDWM increases welding qualify, productivity and reduces costs of welding. So, the DDWM can have a great of contribution to the mobile welding industries. The effectiveness of the DDWM was proven by the experimental results and durable test.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권11호
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• pp.572-576
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• 2003

For quite a long time various researches and developments of superconducting magnetic energy storage(SMES) device have been done for enhancement of power qualify control of sensitive electric load. This paper describes the design. fabrication and experimental results for the 3MJ SMES magnet made by using the design code of a SMES device that we developed. A computer code was developed to find the parameters of the SMES magnet which has minimum amount of superconductor for the same stored energy, and the 3MJ SMES magnet was designed based upon that. And the 3MJ SMES magnet designed based upon those. In addition, 3MJ SMES magnet was made based on several research results which were ramp up to 1㎄ without quench.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.573-576
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• 2004

KARI is achieving the KSLV program according to National Space Technology Development Program. In this paper, the authors are intended to introduce the Integrated Power Plant (abb. IPP) test facility which will be constructed for the variety of tests on KSLV program. IPP test facility refers to comprehensive testing equipment for liquid rocket launch vehicle. Using this facility, KARl can verify the adaptiveness of parts and subsystems for launch vehicle and finally can qualify the system characteristics of launch vehicle doing kinds of test including hot firing test. Using this facility, KARI can simulate the vehicle launching circumstances and it make to predict the performance of launch vehicle when its flight test.

• 전력전자학회논문지
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• 제12권4호
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• pp.300-309
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• 2007

본 논문에서는 전력품질개선기능을 갖는 계통연계형 태양광 발전시스템을 제안한다. 제안된 시스템은 전류제어형 전압원인버터 하나만을 사용하여 단위역률, 고조파저감 그리고 무효전력보상을 동시에 수행한다. 제안된 시스템의 동작모드는 2개의 모드로 구분할 수 있다. 야간모드에서는 PQC를 통해 부하에서 발생하는 무효전력을 보상한다. 주간모드에서는 고조파 저감 및 역률개선을 위한 PQC를 수행하면서 동시에 태양광의 최대전력을 발전하는 MPPT를 수행한다. 본 연구에서 제안한 시스템의 유용성을 확인하기 위해 시뮬레이션과 실험을 수행하였다.

• 한국정보과학회논문지:정보통신
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• 제34권5호
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• pp.379-388
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• 2007

최근 컴퓨터 기술과 네트워크 기술의 급속한 발전과 보급으로 유선환경에서뿐만 아니라 무선환경에서도 이동단말기를 이용하여 네트워크에 접속하여 다양한 작업을 수행할 수 있게 되었다. 사용자들이 네트워크를 통해 이용하는 다양한 어플리케이션들 중에 스트리밍 미디어를 이용하는 어플리케이션의 비중이 높아지고 있으며 이는 유선환경뿐만 아니라 무선환경에서도 마찬가지이다. 스트리밍 미디어는 다른 데이타들에 비해 크기가 매우 크고 높은 네트워크 대역폭과 많은 컴퓨팅 자원을 필요로 한다. 스트리밍 미디어 서비스를 낮은 대역폭과 적은 컴퓨팅 자원을 가지는 이동단말기를 통해 이용할 경우 사용자 환경에 맞게 특화된 서비스가 아니라면 안정적인 서비스를 제공받지 못할 것이다. 특히 이동단말기에서는 배터리를 통한 제한된 에너지 환경을 가지고 있으므로 스트리밍 미디어의 재생을 끝까지 보장하기 위해서는 실시간으로 변화되는 에너지에 대하여 적응적으로 스트리밍을 조절하여야 한다. 본 논문에서는 이동단말기를 위하여 스트리밍 미디어 서비스시에 이동단말기의 에너지 상태에 따라 전송되는 프레임의 수를 동적으로 조절하는 DFRC기법을 연구하였다. 제안하는 기법은 적은 컴퓨팅 자원을 사용하면서 동적으로 스트리밍을 조절하므로 사용자들에게 완전한 재생시간을 보장한다.

• 한국음향학회지
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• 제24권8호
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• pp.431-440
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• 2005

초음파 파워의 정확한 측정은 초음파 의료 장비의 품질 보증과 안전성에 중요하다. 본 논문에서는 초음파 조사가 on/off를 반복하는 동안의 표적에 작용하는 방사 힘과 부력과 같은 다른 원인에서 기인하는 저울 지시 값의 시간에 따른 변화로부터 초음파 파워를 결정하는 간단한 이론을 제시하였다. 아울러 개발된 초음파 파워 측정 시스템에 대해 정밀 기계적 정렬장치, 전기신호 발생부 구성, 제어 및 측정부 구성 및 적절한 절차와 함께 상세히 기술하였다. 본 시스템으로 1 MHz, 5 MHz, 10 MHz, 15 MHz에서 10 mW에서 10 W범위에 걸쳐 측정된 결과를 다른 나라에서 교정된 기준 데이터와 상호 비교한 결과 상대 편차가 $5\%$ 이내로 확인되었다.

• 한국산업경영시스템학회:학술대회논문집
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• 한국산업경영시스템학회 2002년도 춘계학술대회
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• pp.439-444
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• 2002

Competitive power in manufacturing industries mainly depends on production time and qualify of products. The main issue for achieving this goal is to build high speed and super accuracy machine. The machine has been developed in the aspect of hardware. However, applications in high speed machining is not sufficient to give solutions to industries in machining. This research presents a method to improve surface roughness adopting experimental design. This research finds experimental factors which have great impact on surface roughness. From the experiments cutting conditions are found for better quality of machining.

• 산업경영시스템학회지
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• 제19권40호
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• pp.351-360
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• 1996

Korean construction companies are now in very difficult situation due to the recent construction accident, opening of domestic market, the advent of boundless competition period in WTO, etc .Introduction of quality management system is quite urgent in order to strengthen our international competitiveness through the superiority of quality and foster the long term growth of organization. Substantially, many companies are proceeding with or completed the introduction of quality management system but small and medium sized construction companies have difficulties due to lack of money and man power. In this paper, five stage procedures, which can be efficiently applied to introduction and operation of qualify management system, have been suggested to help the minor construction companies which want to adopt the quality management system. This study is considered to be helpful for the companies which will introduce quality management system.

• 전기학회논문지
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• 제56권3호
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• pp.491-497
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• 2007

As dispersed generators was driven in condition interconnecting with utility, it could cause a variety of new effects to the original distribution system that was running as considered only the one-way power flow. Therefore, the protection devices that is builted in distribution system should be designed to be able to operate with disposing of not only a fault of the generator, but also utility condition. Especially, the fault of the feeder interconnected with Dispersed Generator can cause the islanding phenomenon of open DG(Dispersed Generators). This phenomenon has many problems such as a machinery damage, electricity qualify degradation and a difficulty of the system recovery. In the fault therefore, we must separate Dispersed Generator from the system quickly. In this paper, for the fault classification of the interconnected DG and the outside feeder we judge the fault of the interconnected DG and the outside feeder in HMI through data provided by IED(Intelligent Electronic Device) on the network and decide whether it operates or not by sending the result to each relay.

• 품질경영학회지
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• 제30권3호
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• pp.111-119
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• 2002

Gears are essential elements for mechanical power transmission. Geometric precision is the main factor for characterizing gear grade and qualify. Gear pitch is one of the crucial measurements, which is defined as a distance between two adjacent gear teeth. It is well-known that variability in gear pitches may causes wear-out and vibration noise. Therefore maintaining pitch errors at a low level plays a key role in assuring the gear quality to customers. This paper is concerned with a case study, which presents a computerized system for Inspecting pitch errors in a gear machining process. This system consists of a PC and window-based programs. Although the start and stop is manually accomplished, the process of measuring and analyzing pitch data is automatically conducted in this system. Our purpose lies in reducing inspection cost and time as well as Increasing test reliability. Its operation is briefly illustrated by example. Sometimes a strong autocorrelation is observed from pitch data. We also discuss a process monitoring scheme taking account of autocorrelations.