• 대한전자공학회논문지SD
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• 제41권8호
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• pp.93-98
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• 2004

SRAM에서 쓰기 전력을 줄이기 위하여 소스 전압을 높인 메모리 셀을 이용한 저전력 SRAM을 제안하였다. 메모리 셀의 소스 전압을 GND에서 V/sub T/로 올리고 비트라인과 데이터버스의 프리차지 전압을 V/sub DD/에서 V/sub DD/-V/sub T/로 낮춤으로써 비트라인과 데이터버스의 스윙 전압을 줄였다. 이것은 면적의 증가와 속도 감소 없이 SRAM의 쓰기 전력을 크게 줄여준다. 8K×32비트의 SRAM이 0.25um CMOS 공정으로 제작되었다. 제작된 SRAM은 2.5V 전원과 300MHz 동작 주파수에서 쓰기 동작의 소모전력을 45% 줄였고, 최대 동작 주파수는 330MHz였다.

• Journal of Power Electronics
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• 제17권3호
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• pp.811-820
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• 2017

The reliability issue of IGBT is a concern for researchers given the critical role the device plays in the safety of operations of the converter system. The reliability of power devices can be estimated from the intermittent life test, which aims to simulate typical applications in power electronics in an accelerated manner to obtain lifetime data. However, the test is time-consuming, as testing conditions are not well considered and only rough provisions have been made in the current standards. Acceleration of the test by changing critical test conditions is controversial due to the activation of unexpected failure mechanisms. Therefore, full investigations were conducted on critical test conditions of intermittent life test. A design optimization process for IGBT intermittent life testing program was developed to save on test times without imposing additional failure mechanisms. The applicability of the process has been supported by a number of tests and failure analysis of the test results. The process proposed in this paper can guide the test process for other power semiconductors.

• Journal of Biosystems Engineering
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• 제37권6호
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• pp.352-358
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• 2012

Purpose: The inexpensive black box system was developed to acquire and save driving information, to give the slope information, and to transmit SOS and theft signal. Method: The device consists of a main micro controller to acquire and save data, a GPS sensor module, a CDMA module, a touch LCD module, a RF (Radio Frequency) ID module, a SD (Secure Digital) card module, an emergency electric power source, a theftproof circuit, and a sensing device. The sensing device consists of a 8 bit micro controller, a accelerometer to detect impulse, two slope sensors to detect roll and pitch angle and a circuit to detect operation of 6 lighting devices. Results: Test results are as follows: 1) a tractor can be start up only with an electronic key (password or RFID card), 2) theft signal was transmitted when a tractor moved without an electronic key, 3) SOS was transmitted at conditions that rollover or crash happened. 4) 5 more than per 1s data are recorded at 5 minute intervals as new file name in SD card. Conclusions: This system can be used to save travelling record, reduce accident, prevent theft and rescue life in the accidents.

• 정보처리학회논문지A
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• 제10A권6호
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• pp.685-690
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• 2003

새로운 무선인터넷 디바이스로써 주목받고 있는 PDA는 기능 개선을 위해서 다양한 애플리케이션 개발이 이루어지고 있으며 수시로 응용프로그램이 설치되어지고 있다. 또한 PDA는 전원이 방전 될 경우에 RAM(Random Access Memory)에 저장되어 있는 데이터가 모두 삭제되는 단점이 있어서 그때마다 프로그램을 다시 복원해야 한다. 본 논문에서는 PDA의 응용 프로그램을 설치할 경우에 사용자가 직접 애플리케이션을 설치해야 하는 기존의 문제점을 해결하기 위하여 자동으로 PDA 응용프로그램이 설치되는 시스템(PAIS : PDA Automatic Installation System)을 제안하였다. 이 시스템을 적용한 경우 사용자에게는 설치에 소요되는 시간과 노력을 감소시켜 편의를 제공하고, 기업에게는 프로그램 설치관련 홍보물 제작에 소요되던 비용을 절감 할 수 있는 효과가 있다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
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• pp.160-163
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• 2000

Due to the complexities of the real-world system, a water resource management program has to deal with various types of data. It appears that management personnel who has to use the program usually suffers from the technical burdens of handling large amount of data and understanding the optimization theory when they try to interpret the results. By combining the capabilities of database technology and modeling technique with optimization procedure we can develop a reliable decision supporting tool for multi-reservoir operation planning, which yields operating schedule for each dam in a river basin. We introduce two special data handling methodology for the real world application. First, by treating dams, hydro-electric power generating facilities and demand sites as separate database tables, the proposed data handling scheme can be applied to general water resource system in Korea. Second, by assigning variable names using predetermined key words, we can save searching time for identifying the moaning of the variables, so that we can quickly save the results of the optimization run to the database.

• 경영과학
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• 제24권2호
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• pp.127-142
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• 2007

This study deals with the optimal design of mobile access network connecting base stations(BSs) and mobile switching centers(MSCs). Generally mobile operators constitute their access networks by leasing communication lines. Using the characteristic of leased line rate based on administration region, we build an optimization model for mobile access network design which has much smaller number of variables than the existing researches. And we develop a GUI based optimization tool integrating the well-known softwares such as MS EXCEL. MS VisualBasic, MS PowerPoint and Ip_solve, a freeware optimization software. Employing the current access network configuration of a Korean mobile carrier, this study using the optimization tool obtain an optimal solution for both single MSC access network and nation-wide access network. Each optimal access network achieves 7.45% and 9.49% save of lease rate, respectively. Considering the monthly charge and total amount of lease line rate, our optimization tool provides big amount of save in network operation cost. Besides the graphical representation of access networks makes the operator easily understand and compare current and optimal access networks.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.547-550
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• 2005

본 논문에서는 기존의 하드디스크가 가지고 있는 단점을 개선하기 위하여 반도체 소자인 Flash Memory를 이용한 ATA 버스 방식의 Flash Memory Drive를 설계 및 구현하고 성능을 평가하였다. 일반적인 하드디스크의 경우, 외부의 충격에 비교적 민감하며 이로 인해 데이터의 손상이나 디스크의 오류가 발생되게 된다. 또한 내부적인 구조로 인하여 구동 시 많은 전류를 필요로 하며 경량화에 어려움이 있다. 그러나 반도체 소자인 Flash Memory를 이용하여 하드디스크를 제작하게 되면 소전류로도 구동이 가능하며 경량화가 가능할 뿐만 아니라 특히 외부의 충격에 강하므로 자동차, 선박, 산업용과 더불어 군사용으로의 활용이 가능할 것으로 기대된다.

• 한국체육학회지인문사회과학편
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• 제57권4호
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• pp.387-394
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• 2018

본 연구의 목적은 국제아이스하키연맹(IIHF)이 개최하는 대회에서 승리 팀을 결정하는 주요 변인들을 파악하여 전략 및 전술 수립에 필요한 정보를 제공하는 것이다. 2017 IIHF World Championship 1부 리그 14개 팀의 예선 및 본선을 포함한 64개 경기의 기록지를 분석대상으로 하였다. 분석변인은 save, shot on goal, penalty in minute, time on power play, power play goal, face off win의 비율, 승패 간 로지스틱 회귀분석, 중다회귀분석, 주성분분석을 수행하였다. 로지스틱 회귀분석 결과 승리와 관련이 있는 변인은 shot on goal(p<.001)와 face off win(p<.001)이고 penalty in minute(p<.01)과 time on power play(p<.01)는 부정적인 영향을 미친다. 중다회귀분석에 의하여 산출한 승패 비율과 각 변인과의 상관분석에서는 save(p<.01), face off win(p<.001)가 정적인 상관관계이고 penalty in minute(p<.001)이 부정적인 상관관계이다. 주성분분석 결과에서는 승리한 팀의 경우 페널티 요인, 공격 요인, 수비 요인으로 구성되는 반면 패배한 팀에서는 페널티 요인을 제외하고 공격과 수비 요인이 혼합되어 구성되었다. 따라서 최상위 팀이 참가하는 아이스하키 경기에서 승리하기 위해서는 페널티를 받지 않는 내에서 거친 플레이가 이루어져야 하고 face off win 비율을 높일 수 있는 방안이 마련되어야 할 것이다.

• 신재생에너지
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• 제5권3호
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• pp.40-48
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• 2009

Recovered heat has been considered as a renewable energy in Europe since 2008 because its great effect on energy saving and carbon decreasing in plant process. Energy saving and decreasing green gas are critical issue today, so various technologies to save energy and decrease carbon dioxide in plant process have been applied to many industrial area. In this paper, the feasibility of condenser heat recovery by heat pump in power plant for district heating and fuel line preheating were reviewed by verifying energy (heat) balance and mass balance of power plant model. Some ways to compose proper system to recover heat of condenser are suggested and their possibilities are also reviewed. Limitations on heat recovery in power plant are also reviewed. The results are verified by calculating input/output energy based on actual performance test data of Taean Thermal Power Plant in Korea. There is noticeable improvement of plant performance in some cases which demand low temperature (<100 C) heat like distrcit heating, fuel line heating, and so forth.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1483-1488
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• 2005

As the development of microprocessor technology, electric power steering(EPS) system which uses an electric motor came to use a few years ago. It can solve the problems associated with hydraulic power steering. The motor only operates when steering assistance is needed, so it can save fuel and can reduce weight and cost by eliminating hydraulic pump and piping. As one of performance criteria of EPS systems, the transmissibility from road wheel load to steering wheel torque is considered in this paper. The transmissibility can be studied by fixing the steering wheel and calculating the torque needed to hold the steering wheel from road wheel load. A proportion-plus-derivative control is needed for EPS systems to generate desired static torque boost and avoid transmissibility of fluctuation. A pure proportion control can' satisfy both requirements.