• 한국통신학회논문지
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• 제13권1호
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• pp.63-73
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• 1988

본 논문에서는 확률적 방향성 그래프에서 시점(source node)과 종점(terminal node) 간의 통신할 수 있는 확률인 단점간 신뢰도를 계정하는 알고리즘을 제시하였다. Satyanarayana의 factoring $theorem^{(7)}$을 이용하여 확률적 방향성 그래프에서 시점에 연결되어 있는 에지(edge)를 개방(open)과 단락(short)상태로 감축하여 원래의 그래프를 2개의 감축된 그래프로 분리한 후, 본 논문이 제시한 에지제거법과 일반적인 직, 병렬 감축법을 분리된 그래프에 적용한다. 이 에지 감축(edge reduction)을 source node와 terminal node가 단일 에지로 연결될때까지 반복한다. 또한 복잡하고 규모가 큰 망에 대한 단점간 신뢰도를 계정하기 위해서 전산기 프로그램을 제시하였다.

• 방사선산업학회지
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• 제6권3호
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• pp.231-237
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• 2012

This paper introduces a gamma-ray measurement system for a transportable tomography which is applicable for an industrial process diagnosis. The gamma-ray measurement system consists of pulse mode operating 72 channel CsI detectors, main AMP-pulse shaper, single channel analyzer, counter and control PC. The CsI crystal is coupled with a PIN diode which is connected to an amplifier and pulse shaper. For a compact design, the amplifier and pulse shaping circuit are included in a single package. 36 sets of CsI detectors are connected to a multi-channel counter through single channel analyzers. A computer controls and collects data from two multi-channel counters. This configuration results in 72 channel counting system in total. The CT rotator and radiation measurement system are controlled by a PC with LabVIEW program. Tomographic data were measured for a phantom by the measurement system and transportable gamma-ray CT. From the experimental data image reconstructions were performed by ML-EM algorithm. The result showed that the CsI detector system can be a suitable component for transportable gamma-ray CT system.

• Structural Engineering and Mechanics
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• 제37권1호
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• pp.17-37
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• 2011

This paper presents a new Internet-based computational framework for the realistic simulation of multi-scale response of structural systems. Two levels of parallel processing are involved in this frame work: multiple local distributed computing environments connected by the Internet to form a cluster-to-cluster distributed computing environment. To utilize such a computing environment for a realistic simulation, the simulation task of a structural system has been separated into a simulation of a simplified global model in association with several detailed component models using various scales. These related multi-scale simulation tasks are distributed amongst clusters and connected to form a multi-level hierarchy. The Internet is used to coordinate geographically distributed simulation tasks. This paper also presents the development of a software framework that can support the multi-level hierarchical simulation approach, in a cluster-to-cluster distributed computing environment. The architectural design of the program also allows the integration of several multi-scale models to be clients and servers under a single platform. Such integration can combine geographically distributed computing resources to produce realistic simulations of structural systems.

• 한국초전도ㆍ저온공학회논문지
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• 제12권2호
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• pp.29-33
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• 2010

The experimental results of the 2 stage Gifford-McMahon(GM) type pulse tube refrigerator (PTR) or cryopump are presented in this paper. The objectives of his study are to develop design technology of the integral type 2 stage PTR which rotary valve is directly connected to he hot end of the regenerator and acquire its improved performance. Design of the 2 stage PTR is conducted by FZKPTR(Forschungs Zentrum Karlsruhe Pulse Tube Refrigerator) program for the design of pulse tube refrigerators. The fabricated PTR has U-type configuration and incorporates orifice valve, double-inlet valve and reservoir as phase control mechanism. Rotary valve is used to make pulsating pressure and is directly connected to inlet of $1^{st}$ stage regenerator. From experiments, cooling performance map and pressure waveform at each point were measured for different operating frequencies. Experimental results show the best cooling performance with 2 Hz operation in spite of small pressure amplitude. The lowest temperatures of the 2 stage PTR were 16.9 K at the second stage and 58.0 K at the first stage. The cooling capacities achieved were 14.4 W at 79 K, the first stage and 3.6 W at 29 K, the second stage.

• 한국정보통신학회논문지
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• 제20권3호
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• pp.590-598
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• 2016

자동차와 이동통신기술이 융합된 커넥티드 카 산업이 새로운 블루오션으로 주목받고 있고, 휴대용 전자기기(스마트폰, 태블릿 PC, MP3 플레이어 등)와 자동차를 연결한 각종 인포테인먼트(infotainment) 서비스들도 빠르게 성장하고 있다. 커낵티드 카란 자동차가 주변과 실시간으로 소통하며 운전자에게 안전과 편의를 제공한다는 개념으로 차량 연결성(Connectivity)을 강조하고 자동차에 사물인터넷(IoT)을 채용하여 플랫폼으로 활용, 현재는 실시간 내비게이션, 주차 보조기능, 원격 차량제어 및 관리 서비스뿐만 아니라 이메일, 멀티미디어 스트리밍, SNS 등 엔터테인먼트 서비스를 지원하고 있다. 지능형 자동차 네트워크는 MANET(Mobile Ad Hoc Network)의 한 종류로 도로 상의 자동차들의 안전한 운행 및 운행 효율성 제고 등을 위해 연구되고 있다.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.452-460
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• 2014

Due to increased concerns for rising oil prices and environmental problems, various solutions have been proposed for solving energy problems through tightening environmental regulations such as those regarding $CO_2$ reduction. Among them, Electrical Vehicles (EVs) are evaluated to be the most realistic and effective approach. Accordingly, research and development on EVs and charging infrastructures are mainly proceeding in developed countries. Since EVs operate using electric energy form a battery, they must be connected to the power system to charge the battery. If many EVs are connected during a short time, power quality problems can occur such as voltage sag, voltage unbalance and harmonics which are generated from power electronics devices. Therefore, when EVs are charged, it is necessary to analyze the effect of power quality on the distribution system, because EVs will gradually replace gasoline vehicles, and the number of EVs will be increased. In this paper, a battery for EVs and a PWM converter are modeled using an ElectroMagnetic Transient Program (EMTP). The voltage sag and unbalance are evaluated when EVs are connected to the distribution system of the Korea Electric Power Corporation (KEPCO). The simulation results are compared with IEEE standards.

• 한국전자통신학회논문지
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• 제18권6호
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• pp.1103-1108
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• 2023

본 논문에서는 음향신호의 배경잡음을 감쇠하기 위한 새로운 알고리즘을 제안한다. 이 알고리즘은 이산 웨이블릿 변환(DWT: Discrete Wavelet Transform) 후 기존의 적응필터를 대신 FNN(: Full-connected Neural Network) 심층학습 알고리즘을 이용하여 잡음감쇠 성능을 개선하였다. 입력신호를 단시간 구간별로 웨이블릿 변환한 다음 1024-1024-512-neuron FNN 딥러닝 모델을 이용하여 잡음이 포함된 단일입력 음성신호로부터 잡음을 제거한다. 이는 시간영역 음성신호를 잡음특성이 잘 표현되도록 시간-주파수영역으로 변환하고 변환 파라미터에 대해 순수 음성신호의 변환 파라미터를 이용한 지도학습을 통하여 잡음환경에서 효과적으로 음성을 예측한다. 본 연구에서 제안한 잡음감쇠시스템의 성능을 검증하기 위하여 Tensorflow와 Keras 라이브러리를 사용한 시뮬레이션 프로그램을 작성하고 모의실험을 수행하였다. 실험 결과, 제안한 심층학습 알고리즘을 사용하면 기존의 적응필터를 사용하는 경우보다 30%, STFT(: Short-Time Fourier Transform) 변환을 사용하는 경우보다는 20%의 평균자승오차(MSE: Mean Square Error) 개선효과를 얻을 수 있었다.

• 초등상담연구
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• 제9권1호
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• pp.95-110
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• 2010

본 연구는 또래 칭찬활동 프로그램이 초등학생의 교우관계와 학급응집성에 미치는 영향을 알아보기 위하여 실시되었다. 서울특별시에 소재한 J초등학교 5학년 2개 학급을 실험집단과 통제집단으로 나누어 실험집단에 프로그램을 처치하고 사후검사와 추후검사를 실시하여 프로그램의 효과를 검증하였다. 프로그램의 타당도를 검증하기 위하여 예비 실시를 통해 미비점과 문제점을 보완하였다. 연구 결과 또래 칭찬활동프로그램을 처치한 실험집단은 교우관계와 학급응집성에서 모두 유의미한 효과가 나타났으며, 아동 소감과 연구자의 관찰에서도 이 프로그램을 통해 아동의 교우관계가 개선되고, 학급응집성이 증가한 것을 알 수 있었다. 그러나 통제집단에서도 학기 초 아동의 학급생활 적응으로 인해 교우관계의 일부 하위변인에서 유의미한 효과가 나타났으며, 추후검사에서 실험집단 아동의 교우관계 하위변인 중 일부에서 효과가 감소한 것이 드러나기도 하였다. 학급응집성은 사후검사보다 추후검사에서 더욱 유의미하게 증가한 점으로 보아 본 연구에서 실시한 또래 칭찬활동 프로그램은 학급응집성의 증가와 유지에 긍정적인 영향을 미친다는 것을 알 수 있었다. 앞으로의 연구에서는 교우관계를 지속적으로 높이기 위한 프로그램의 내용 수정이나 추후지도에 관한 연구가 필요하다고 본다.

• 대한간호학회지
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• 제30권4호
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• pp.1035-1044
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• 2000

The purpose of this study was to develop and evaluate an internet based program for nursing informatics. The course subject, Nursing Informatics, was made by a computerized instructional module using the internet. The program was developed after taking into consideration the level of competence and knowledge in the subjects. It was based on 10 steps of the CAI module developed by Alessi and Trollip. The subjects consisted of 76 junior nursing students taking a Nursing Informatics course. Two sets of questionnaires were used for this study. First, a questionnaire was administered to 76 students to collect general information on their experience while using computers and the internet. Secondly, another questionnaire was administrated to 76 students after they took the course. They were asked to evaluate the program in terms of easiness of use, precision of contents, freshness of contents, motivation in learning, effectiveness of learning, enhancement of communication, precision of screen, and interest in the contents. IDs and passwords were given to the students. The students were asked to write their IDs and passwords when they connected to Nursing Informatics (http://hallym.ac.kr/~yhyom/ inform.html). They were led the menu page which was categorized into 8 icons (i. e., syllabus, lecture notes, quick test, Q & A board, assignment, on-line test, related web sites and mailing lists) after confirming their IDs and passwords. The students' responses were very positive. This program was a very useful in increasing the effectiveness of learning and motivation in the students. Suggest to be use for other nursing courses.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권2호
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• pp.125-131
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• 2001

When the program voltage is applied to a word line, a part of the boosted channel charge in inhibited bit lines is lost due to the coupling between the string select line (SSL) and the adjacent word line. This phenomenon causes the program disturbance in the cells connected to the inhibited bit lines. This program disturbance becomes more serious, as the word line pitch is decreased. To reduce the word line coupling, the rising edge of the word-line voltage waveform was changed from a pulse step into a ramp waveform with a controlled slope. The word-line ramping circuit was composed of a timer, a decoder, a 8 b D/A converter, a comparator, and a high voltage switch pump (HVSP). The ramping voltage was generated by using a stepping waveform. The rising time and the stepping number of the word-line voltage for programming were set to $\mutextrm{m}-$ and 8, respectively,. The ramping circuit was used in a 512Mb NAND flash memory fabricated with a $0.15-\mutextrm{m}$ CMOS technology, reducing the SSL coupling voltage from 1.4V into a value below 0.4V.