• 전기학회논문지
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• 제64권3호
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• pp.473-479
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• 2015

Thermal relays are sometimes used instead of long time overcurrent relays for motor protection. But, it is difficult for any relay design engineer to adequately approximate motor heating curves which represent the average of a difficult-to-define thermal zone. Thermal relays frequently may not provide sufficient protection on heavy overloads. Digital multifunction relays are microprocessor-based devices. These relays offer highly reliable and advanced protection of motors. If a situation can be mathematically described, the microprocessor in a digital relay can be programmed to tackle that problem. Today's motor protection is accomplished with digital protective relays. Digital relays offer additional, highly important features to complement protection. The best way to prevent short in motor is to not overheat and degrade the insulation.

• ETRI Journal
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• 제35권3호
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• pp.378-385
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• 2013

An S-band multifunction chip with a simple interface for an active phased array base station antenna for next-generation mobile communications is designed and fabricated using commercial 0.5-${\mu}m$ GaAs pHEMT technology. To reduce the cost of the module assembly and to reduce the number of chip interfaces for a compact transmit/receive module, a digital serial-to-parallel converter and an active bias circuit are integrated into the designed chip. The chip can be controlled and driven using only five interfaces. With 6-bit phase shifting and 6-bit attenuation, it provides a wideband performance employing a shunt-feedback technique for amplifiers. With a compact size of 16 $mm^2$ ($4mm{\times}4mm$), the proposed chip exhibits a gain of 26 dB, a P1dB of 12 dBm, and a noise figure of 3.5 dB over a wide frequency range of 1.8 GHz to 3.2 GHz.

• 패션비즈니스
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• 제6권4호
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• pp.46-61
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• 2002

The purpose of this study was to analyze critical needs and demands for the multifunctional traveler's jacket and to develop design prototypes based on the findings from the analysis. A self-report questionnaire with the stimuli was applied. Total 163 travelers were purposively sampled for the survey and the data were analyzed quantitatively as well as qualitatively. The results were as follows: 1. The respondents were divided into three groups - "digital-functionality-needs group", "non-digitalfunctionality-needs group", "no-need group", according to their preference and needs for the multifunctional traveler's jacket. 2. The three groups were analyzed (1) to have meaningful differences in experiencing inconvenience in their traveling, (2) to have statistically significant differences in their needs for the multifunctional traveler's jacket, (3) while some imperative consensus in their needs were found in part. 3. Based on the findings of the analysis mentioned above, three design prototypes were developed and visualized with conclusion.

• 공학논문집
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• 제7권1호
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• pp.61-70
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• 2005

일반적인 지질조사에서는 많은 양의 지질구조 측정을 위하여 수동 컴퍼스를 사용하고 있다. 암반사면의 건축과 터널의 증가로 인해 좀 더 정밀한 지질조사 요구 때문에 휴대용 다용도 디지털 컴퍼스가 필요하다. 이 시스템은 마이크로 컨트롤러로서 Intel PXA 255 임베디드 보드가 사용되어 만들어졌으며, 기울기 센서, 방위각 센서, 그리고 위성항법장치로 구성되어져 있다. 우리가 개발한 시스템으로 측정되어진 경사 값과 주향 값, 그리고 위치 값은 PDA나 노트북으로 전송되어 지질구조 분석을 위하여 쓰여질 것이다. 본 논문에서 개발된 값싸며 성능이 향상된 디지털 컴퍼스는 광대한 지질 조사에 있어서 많은 비용과 시간을 절약하는 역할을 하리라 기대된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.444-446
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• 1994

This paper describes the design of a digital multifunction controller for the intelligent high voltage customer switchboard and proposes a relaying algorithm for high impedance faults using back-propagation neural network. The hardware design uses the three microprocessors and global memory architecture to achive real time operation and control 4 feeders. The controller uses a 64-point radix-4 DIF FFT algorithm to measure the harmonic and relay parameters. Synthesized fault current waveforms are used to train and test the back - propagation network.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.465-470
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• 2002

A novel phased array antenna system for space-borne polarimetric SAR is proposed and completed in this paper.The antenna system assures polarimetric and multi-mode capability of SAR. It has broadband, high polarization isolation and high port to port isolation. The antenna system is composed of broadband polarimetric microstrip antenna, T/R modules and multifunction beam controller nit. The polarimetric microstrip antenna has more than 100MHz bandwidth at L-band with -30dB polarization isolation and high port to port isolation. The microstrip element and T/R module's structure and characteristics, the subarray's performances measuring results are presented in detail in this paper. A design scheme on beam controller of the phased array antenna is also proposed and completed, which is based on Digital Signal Processing (DSP) chip -TMS320F206. This beam controller unit has small size and high reliability compared with general beam controller. In addition, the multifunction beam controller unit can acquire and then send the T/R module's working states to detection system in real time.

• 정보보호학회논문지
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• 제20권6호
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• pp.23-32
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• 2010

IT 환경의 발전으로 일상생활에서의 임베디드 기기의 사용빈도가 증가하고 있다. 이러한 임베디드 기기중 대표적인 사무자동화기기인 디지털복합기는 복사기, 스캐너, 팩스, 파일서버 기능 등 다양한 용도로 사용되고 있다. 이러한 디지털복합기내에 스캔 등을 통하여 저장되어 있을 수 있는 데이터의 존재여부와 추출방법, 이를 이용한 증거자료로서의 활용방안에 대하여 논하여 보고자 한다.

• 대한디지털의료영상학회논문지
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• 제13권4호
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• pp.177-183
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• 2011

This study intends to investigate patients' exact exposure doses by comparatively measuring ESD (Entrance Surface Dose) with the DAP meter, which excludes scattered rays, and ESD with the Xi multifunction meter, which includes scattered rays, by posture changes for Esophagography test and UGI test. The materialwere examined through Sonialvision-SafireII SPEC overtube system. ESD was measured by using the DAP meter, and as a tool to measure ESD including scattered rays on the plane of incidence of human phantom, the Xi multifunction meter was used. The average fluoroscopic time of Esophagography test was 4.192 minutes and the average number of images was 47.7, while the average fluoroscopic time of UGI test was 6.881 minutes and the average number of images was 37.8. The ratios of the incident dose of DAP meter and the ESD of Xi meter were calculated bydividing the fluoroscopic time and the number of images by each posture change. As for Esophagography test, the dose increased by 21.6~55.5% in the fluoroscopic test and by 4.8~24.7% in the spot test. In the front spot test, however, the does increased by as little as 5.3%. As for UGI test, the dose increased by 21.1~49.5% in the fluoroscopic test and by 10.1~34.9% in the spot test. It is expected that measuring doses in consideration of scattered rays by posture changes will be an important index in evaluating and managing patients' exact exposure doses for each test above. Furthermore, it is judged that this sort of study is inevitable and desirable to reduce patients' exposure doses after all.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.803-805
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• 1993

This paper describes the development of a digital multifunction controller for the protection, measurement and control of the high voltage customer switchboard. The magnitude of the fundamental component is estimated using a simple filter based on cross-correlation with a heptagonal wave. The characteristics of flexible relay functions such as adjustable pickup and time-dial settings, various time-magnitude curve and directional capability including measurement functions are presented. The controller implementation is carried out on two microprocessors for real time operation.

• 한국진공학회지
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• 제8권4B호
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• pp.536-540
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• 1999

We have developed a refractory WNx self-aligned gate GaAs metal-semiconductor field-effect transistor(MESFET) using $SiO_2$ side-wall process. The MESFET hasa fully ion-implanted, planar, symmetric self-alignment structure, and it is quite suitable for integration. The uniform trans-conductance of 354nS/mm up to Vgs=+0.6V and the saturation current of 171mA/mm were obtained. As high as 43GHz of cut-off frequency hs been realized without any de-embedding of parasitic effects. The refractory WNx self-aligned gate GaAs MESFET technology is one of the most promising candidates for realizing linear power amplifier ICs and multifunction monolithic ICs for use in the digital mobile communication systems such as hand-held phone(HHP), personal communication system (PCS) and wireless local loop(WLL).