• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.150-152
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• 2007

LCD Backlight 구동 응용을 위한 새로운 인버터 회로 Topology인 Modified Half Bridge Inverter를 제안한다. 제안된 회로는 LCD의 광원 역할을 하는 냉음극 형광램프(Cold Cathode Fluorescent Lamp, CCFL) 구동을 위한 회로로서, 제안된 회로는 주 스위치의 동작 시비율이 낮을 때도 보조 스위치를 이용하여 환류 구간을 형성함으로써 주스위치의 영 전압 스위칭 동작을 보장할 수 있다. 제안된 회로의 동작원리를 설명하고, 타당성을 Simulation 및 실험을 통하여 검증한다.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.166-168
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• 2007

본 논문은 LCD backlight 인버터의 Cold Cathode Fluorescent Lamp(CCFL)를 구동하기 위해 승압 기능과 전류 평형 효과를 동시에 갖는 트랜스포머에서 부피 및 원가 저감 효과를 갖는 새로운 구조의 트랜스포머를 제안하였다. 제안된 트랜스포머의 타당성을 검증하기 위해 실제 40인치 LCD backlight 인버터에 적용하여 실험을 수행하였다.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.190-192
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• 2007

LCD TV의 대형화에 따라 하나의 백라이트용 냉음극 방전램프(Cold Cathode Fluorescent Lamp ; CCFL)를 이용한 백라이트는 휘도의 한계가 있어 대형 디스플레이에서는 여러 개의 램프를 사용하여 필요한 휘도를 만들고 있다. 본 논문에서는 냉음극 방전램프 16개를 사용하는 42인치 LCD TV용 대형 백라이트 구동을 위한 인버터의 트랜스포머를 각기 다른 램프의 특성에 대해 동일한 관 전류 출력을 갖도록 설계하였다.

• ETRI Journal
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• v.31 no.5
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• pp.601-603
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• 2009

This letter presents a high performance 2.4 GHz two-stage power amplifier (PA) operating in the temperature range from $-30^{\circ}C$ to $+85^{\circ}C$ for IEEE 802.11g, wireless local area network application. It is implemented in InGaP/GaAs hetero-junction bipolar transistor technology and has a bias circuit employing a temperature compensation technique for error vector magnitude (EVM) performance. The technique uses a resistor made with a base layer of HBT. The design improves EVM performance in cold temperatures by increasing current. The implemented PA has a dynamic EVM of less than 4%, a gain of over 26 dB, and a current less than 130 mA below the output power of 19 dBm across the temperature range from $-30^{\circ}C$ to $+85^{\circ}C$.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.569-572
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• 1998

In this paper, we devised pulse rate diagnosis for provide basic index of cold-hot diagnosis. The system consist of database part and pulse rate detection part for detection pulse wave, respiration and ECG. The database is constructed windwos95 platform using DAO(data access object). Search algorithm used ISAM algorithm. The database consist of one's information and medical report for a subject and detected pulse wave.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.2
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• pp.96-102
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• 2008

In a large screen sized LCD-TV, a backlight system with only one cold cathode fluorescent lamp(CCFL) can not meet brightness specification. Thus, considerable numbers of CCFLs are used to meet brightness specification. In this paper, the design guide for the inverter transformer which can drive 4 CCFLs instantaneously is presented. With the presented design, the inverter transformer that guarantee identical lamp currents under the nonidentical lamp characteristic condition, can be implemented easily. The developed inverter transformer is adopted in a 42" LCD-TV backlight. The experimental results are presented to show the validity of the presented design guide.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.3
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• pp.19-27
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• 2010

KSLV(Korea Space Launch Vehicle)-I is designed as a launch vehicle to enter a 100 kg-class satellite to the LEO(Low-Earth Orbit). Attitude angles of the upper-stage, including roll, pitch and yaw are controlled by cold gas thruster system using nitrogen gas. The thruster for the KSLV-I is the main pneumatic valve in the RCS(Reaction Control System). In this paper, the design, function tests, and environment tests of the thruster for KSLV-I are described. The developed thrusters are experimentally evaluated and successfully passed the required qualification and acceptance tests.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.46-50
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• 2004

The Experimental results of the in-line type inertance tube pulse tube cryocooler for cooling superconductor RF filter are presented in this paper. The pulse tube refrigerator, which has no moving parts at its cold section, is attractive in obtaining higher reliability, simpler construction, and lower vibration than any other small refrigerators. The purpose of this study is to analyze the characteristics of in-line type inertance tube pulse tube refrigerator (IPTR), and to get main factor to improve the performance of the in-line type IPTR. Firstly, design parameters of the in-line IPTR are discussed by ARCOPTR program, and then to find optimal conditions of in-line type IPTR, cool down characteristics according to the variations of the charging pressure, inertance tube volume, regenerator volume and pulse tube volume are measured by the experiment. The lowest temperature of the cold end was about 50 K. Cooling capacity was the highest in the charging pressure of 32 atm. and 5W at 72K. On the other hand, COP of the in-line type IPTR was the highest in the charging pressure of 21 atm. and 0.018 at 77K.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.428-435
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• 2016

In this paper, high-performance and low-noise centrifugal fan used to circulate cold air inside a household refrigerator is developed by reducing the vortex flow observed near the tip of fan hub. First, the performance of the existing centrifugal fan is investigated through the experiment using a fan tester and the characteristics of detailed flow field obtained from the CFD simulation are closely examined. The strong vortex flow is observed in the vicinity of the tip of fan hub. Based on this result, new design is devised to reduce this vortex flow. As a result, it is numerically and experimentaly found that the volume flow rate of the new fan increases and the radiated noise decreases in comparison with the existing fan at the same rotation speed.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.55-60
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• 2011

Recently, the application of electronics in vehicle is increasing, in order to assess the reliability of the electronics, highly accelerated life test is used, highly accelerated life test can assess the reliability of the electronics in the short time. In this study, optimized HALT technique can be applied to the electronics is proposed. The main results are as follows; i) HALT is proceed to the 8-step process. ii) The test mode of HALT is composed of the cold step stress, hot step stress, vibration step stress and combined environments stress. iii) The time dwell is set to at least 20 minutes.