• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.216-219
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• 2003

In this paper, we present performance analysis of an IEEE P802.15.3a high rate wireless personal area network transceiver. This physical layer standard uses QOSK as its sub-channel modulation scheme and orthogonal frequency domain modulation (OFDM) for sub-bands. OFDM is used for each sub-band so that multi-path effects are absorbed by equalizer and guard, and fading can be approximately modeled as additive white Gaussian noise. In multi-band ultra-wideband system, DAC quantization error is important noise source since high resolution conversion cannot be used due to high power consumption. Simulation result shows that, to get 640-Mbps throughput, at least 5-bits precision is necessary to maintain bit-error rate under 10$\^$-2/, which can be lowered, with channel coding, to 10$\^$-6/ that is the bit-error rate required by IEEE 802.15 upper protocol layer, in 4-meter LOS fading channel.

• 전기전자학회논문지
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• 제22권4호
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• pp.933-940
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• 2018

본 논문에서는 얼굴 인식률 향상을 위한 멀티 블록 방식의 딥러닝 구조를 제안한다. 제안하는 딥러닝의 인식 구조는 입력된 이미지의 멀티 블록화, 특징 수치 분석을 통한 멀티 블록 선정, 선정된 멀티 블록의 딥러닝 수행 등의 3가지 과정으로 구성된다. 첫 번째로 입력된 이미지의 멀티 블록화는 입력된 이미지를 4등분하여 멀티 블록화 시킨다. 두 번째로 특징 수치분석을 통한 멀티 블록 선정에서는 4등분된 멀티 블록들의 특징 수치를 확인하고 특징이 많이 부각되는 블록만을 선정하여 얼굴 인식에 방해가 되는 요소를 사전에 제거한 블록들을 선정한다. 세 번째로 선정된 멀티 블록으로 딥러닝 수행은 선정된 멀티 블록 부위가 학습되어진 딥러닝 모델에 인식을 수행하여 특징 수치가 높은 효율적인 블록으로 얼굴 인식의 결과를 도출한다. 제안된 딥러닝 구조의 성능을 평가하기 위하여 CAS-PEAL 얼굴 데이터베이스를 사용하여 실험 하였다. 실험 결과, 제안하는 멀티 블록 방식의 딥러닝 구조가 기존의 딥러닝 구조보다 평균 약 2.3% 향상된 얼굴 인식률을 나타내어 그 효용성이 입증됨을 확인하였다.

• 전자공학회논문지A
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• 제29A권3호
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• pp.8-14
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• 1992

In this paper, the differential detection technique of multi-h CPM is introduced and described. We derived the sets of modulation index of multi-h phase codes adequate to the differential detection. The power spectra of multi-h signals with various sets of modulation index are presented and compared to those of MSK and QPSK. Error rate performances of the conventional detector and Viterbi algorithm detector of 2-h and 3-h CPM are evaluated and compared.

• 한국전자파학회논문지
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• 제12권3호
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• pp.378-390
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• 2001

본 논문은 다중경로 라이시안 페이딩과 다중접속간섭이 함께 존재하는 단일 셀 내의 Multi-Carrier DS-CDMA 시스템은 오율 성능을 분석하고, 이를 Single-Carrier Ds-CDMA 시스템의 오율 성능과 비교하였다. 또한, 다중경로 페이딩과 다중접속간섭에 의하여 열화된 Multi-Carrier DS-CDMA 시스템의 성능 개선을 위해 부호화율이 1/2, 1/3 그리고 1/4인 콘볼루션 부호화 기법을 채용하여, 이로부터 얻어지는 Multi-Carrier DS-CDMA 시스템의 성능 특성을 알아 보았다. 분석 결과, 다중경로 페이딩과 다중접속간섭이 존재하는 채널에서 Single-Carrier DS-CDMA 시스템의 RAKE 수신기의 가지를 증가시키거나 Multi-Carrier DS-CDMA 시스템의 반송파의 수를 적정하게 선택함으로써 시스템의 사용자의 수를 결정할 수 있음을 알 수 있었다. 또한, 콘볼루션 부호가 적용된 Multi-Carrier CS-CCMA 시스템은 부호이득과 전력제한의 사이의 trade off를 고려하여 부호화율을 선택하여야 함을 알 수 있었다. 결과적으로 Multi-Carrier DS-CDMA 시스템은 반송파의 수가 증가할수록 처리이득은 감소하나 주파수 다이버시티 효과로 인하여 오율 성능이 개선되었으며, 낮은 칩율을 사용한 시스템의 구성이 가능함을 알 수 있었다.

• 한국초전도ㆍ저온공학회논문지
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• 제3권1호
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• pp.35-39
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• 2001

The optimum cross-sectional area profile of gas-cooled high-temperature superconductor(HTS) current lead is analyzed to have minimum helium boil-off rate. The conventional constant area HTS lead has much higher helium consumption than the optimum HTS lead considered in this study. The optimum HTS lead has variable cross-sectional area to have constant satiety factor. An analytical formula of optimum shape of lead and temperature profile are obtained. For multi-stacking HTS current leads, the optimum tape lengths and minimum heat dissipation rate are also formulated. The developed formulations are applied to the Bi-2223 material, and the differences between constant area, constant safety-factor, and multi-stacking current leads are discussed.

• 대한임베디드공학회논문지
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• 제8권6호
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• pp.339-345
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• 2013

This paper addresses the system lifetime maximization algorithm in multi-hop sensor network system. A multi-hop sensor network consists of many battery-driven sensor nodes that collaborate with each other to gather, process, and communicate information using wireless communications. As sensor-driven applications become increasingly integrated into our lives, we propose a energy-aware scheme where each sensor node transmits informative data with adaptive data rate to minimize system energy consumption. We show the optimal data rate to maximize the system lifetime in terms of remaining system energy. Furthermore, the proposed algorithm experimentally shows longer system lifetime in comparison with greedy algorithm.

• 한국멀티미디어학회논문지
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• 제18권8호
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• pp.909-914
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• 2015

In wireless sensor networks, sensor nodes have a short transmission range and data is transferred from source to destination node using the multi-hop transmission. Sensor nodes are powered by battery and the link qualities are different, and the routing protocol in the wireless sensor network is one of the important technical issues. Multipath routing was proposed to reduce the data congestion and increase data throughput. In the multipath routing, however, each path can be interfered by the other path, and it can aggravate network performance. In this paper, we propose the multipath routing scheme for multi-rate wireless sensor networks. The multipath routing selects transmission paths to minimize transmission delay and path interference.

• 설비공학논문집
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• 제12권5호
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• pp.446-475
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• 2000

Performance of a water-to-water multi-type heat pump system using R22 has been experimentally investigated. Total refrigerant flow rate was adjusted with a variable speed compressor and the refrigerant flow rate for two indoor units were controlled by electronic expansion valves. Evaporator outlet pressure of refrigerant and indoor unit outlet temperatures of secondary fluid were selected as controlled variables. Experiments were carried out for both cooling and heating modes using PID control method. Results show that the multi-type heat pump system can be adequately controlled by keeping control gains at certain levels for various operating conditions.

• 전기학회논문지
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• 제65권11호
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• pp.1925-1930
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• 2016

Fuel cell power generation system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. This paper presents the control of interleaved multi-phase boost converter as the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. PSIM simulation program is to be used to implement the modeling of the electrical fuelcell as well as traction motor control with interleaved multi-phase boost converter. Comparing the input current ripple rate, two-phase interleaved boost converter is less than the boost converter. But the more multi-phase not less proportional to the ripple factor. we confirmed that the amplitude of the input current ripple rate of converter depend on duty ratio.

• 한국안전학회지
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• 제32권4호
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• pp.114-121
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• 2017

In order to overcome the limitations of the mobile speed system for 1 lane, this study is used a multi-laser beam to develop a mobile speed measuring system, using a multi-phase beam. By using multi-laser beam, least squares algorithms and speed error processing algorithms were developed to improve speed accordancy and speed error rates compared to conventional mobile speed meters using a single laser beam. A field test showed that 80.0 percent of 3 lane and 87.0 percent of 4 lane were appropriate for the mobile speed system. With the development of the mobile speed measuring system, it is expected to dramatically reduce the accidents caused by the speed of traffic. It is also expected to effectively operate equipment and manage the cost by improving manpower and providing improved enforcement accuracy, by contributing positively to public institution and public affairs.