• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.219-225
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• 1998

A voltage controlled oscillator for the local oscillator in 380 MHz TRS handset is designed and fabricated. To improve the phase noise characteristics, the NEC's 2SC4226 transistor with NF=1.2 at 1 GHz and Toshiba's 1SV229 varactor diode with Q=70 are used. And an inductor of VCO is realized by microstrip line. At the bias condition of 5 V and 10 mA, the output power and phase noise in the operating frequency range of 357∼387 MHz are above 3.7 dBm and 111 dBc/Hz at 12.5KHz offset from the carrier, respectively. And FM sensitivity deviation are within ±0.4 KHz. This VCO is well suited for TRS handset.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1877-1879
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• 1997

차량용 안테나 시스템을 설계하기 위해서는 안테나를 포함한 차량 전체를 하나의 안테나계로 모델링해야 한다. 본 논문에서는 안테나계를 wire-grid법을 적용하여 FM 라디오 대역에서 모델링 하였다. 시뮬레이션은 NEC(Numerical Electromagnetic Code)-2 모멘트법 코드를 이용하여, wire의 반경을 $0.005{\lambda}$일 때와 twice surface arearule의 경우를 각각 적용하여 해석하였다. 이 해석의 타당성 검증을 위하여 복사 패턴의 수치 해석치를 구한 후 실제 차량의 실험 결과와 비교하였다.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.95-102
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• 1999

Because a driver is located in the front end of KHST, he is most likely to be insured at collision accidents. So, it is very important to design some survival space for the driver. To evaluate the driver's safety of KHST (Korean High Speed Train), the front structure of power car is analysed using PAMCRASH under the SNCF accident scenario(collision against a movable rigid mass 15 ton at 110㎞/h). Because the driver's cab of KHST is a modified version of TGV-K, which is not so strong as to protect him, it turns out to be inadequate to guarantee his survival space. Therefore it is recommended to redesign the driver's cab in a crashworthy point of view like the case of TGV-Duplex or NEC.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.4
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• pp.226-239
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• 2013

A number of systems have several on-chip memories with cache memory being one of them. Conventional cache memory consists of SRAM but the ratio of static energy to the total energy of the memory architecture becomes larger as the leakage power of traditional SRAM increases. Spin-Torque Transfer RAM (STT-RAM), which is a variety of Non-Volatile Memory (NVM), has many advantages over SRAM, such as high density, low leakage power, and non-volatility, but it consumes too much writing energy. This study evaluated a wide range of energy consumptions of a two-level cache using NVM partially on a mobile processor. Through a number of experimental evaluations, it was confirmed that the use of NVM partially in the two-level cache effectively reduces energy consumption significantly.

• Journal of Communications and Networks
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• v.13 no.2
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• pp.95-101
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• 2011

Extended life expectancy and a decrease in fertility rates are dramatically increasing the number of seniors who will eventually need professional care assistance. Although there is no clear technical solution to this problem, recent advances in ubiquitous computing offer opportunities to assist elders in their residence, thus reducing the need for professional assistance in special facilities. There have been several studies, but current solutions tend to address specific issues and cannot be easily extended, updated, and customized to meet the complex and evolving requirements of eldercare assistance. This study aims to bridge this gap, and this paper presents a context-management framework, called awareness for pervasive environments (APE), that provides easily customizable support for the development of ubiquitous eldercare services and applications.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.5
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• pp.28-35
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• 1980

The ever unsatisfied demand for more channel and bandwidth to the limited installalion of existing communication facilities, and explosively increasing expanses for the cable installation fee force us to revive once patented but unused idea of multlplexign in time, that is, PCM in telephony. The authors designed, artworked and prototyped PCM 24 since 1972 and tested the first PCM chaulel Hank between Noryang Jin and yang see stations to prove that the resust of their PCM 24 Channel Bank implementation is viable and promissing.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.339-344
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• 2005

A person's body resistance in the waterpark, public bath and similar places is lower than any other places due to effect of water. So low voltage may create a shock hazard for the human body in case of leakage or fault currents from lighting unit etc. We researched the related regulations these are internal standards, NEC, IEC and investigated the actual conditions for the prevention of electrical shock due to lighting units in the waterpark, public bath and similar places. So we could present actual facilities's problems and solutions

• International Journal of Contents
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• v.9 no.2
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• pp.22-26
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• 2013

Comparing online and paper-based environment for report submission and correction, the former supersedes to the latter, since (1) the turn-around time becomes shorter, (2) teaching opportunity increases, and (3) as a consequence, the student's achievement level becomes higher in the online environment. In this paper, we propose an annotation tool GABA for PDF document in order to reduce correction time by the teachers and to facilitate instruction to students. In a usual class, the same or similar assignments are given to the students. Then it is often the case that many students make similar mistakes. A teacher can register and classify common correction comments to GABA. Report correction time becomes significantly shorter by reusing the registered comments. GABA also provides various support functions in order to assist efficient checking of numerous report files such as (1) sorting of frequently-used comments, (2) similarity-based file sorting, and (3) cross tabulation of comments using category and weight.

• Journal of Power Electronics
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• v.6 no.2
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• pp.114-120
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• 2006

This paper compares two types of direct torque controllers for permanent magnet synchronous motors(PMSMs). These controllers both use a single-chip FPGA(Field Programmable Gate Array) but have differing hardware configurations. One of the controllers was constructed by programming a soft-core CPU and hardware logic circuits written in VHDL(Very high speed IC Hardware Description Language), while the other was constructed of only hardware logic circuits. The characteristics of these two controllers were compared in this paper. The results show the controller constructed of only hardware logic circuits was able to shorten the control period and it was able to suppress the low torque ripple.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.169-176
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• 1998

이동통신용 기지국안테나는 현재 약 -20dB의 후방부엽이 존재한다. 이는 인접한 안테나에 전파감쇠 및 장애를 일으키고 있어 후방부엽을 -50dB이하까지 개선시킬 필요가 있다. 본 논문에서는 기존의 Back Plate 구조를 새롭게 변형하여 후방부엽의 레벨을 낮추고자 한다. 새로운 구조의 Back Plate는 리플렉터안테나의 원리를 이용하여 ㄷ자 형태로 만들었다. 본 연구 수행의 구체적 방법으로는 범용소프트웨어툴인 NEC2를 사용하였고 각 파라메터에 대해 파라메터스터디를 하여 최적의 파라메터를 도출하였으며 -49.58dB의 후방부엽을 갖는 기지국안테나를 설계하였다.