• 전기학회논문지
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• 제63권6호
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• pp.850-854
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• 2014

Analyzing dynamic performance between pantograph and contact wire depends on mechanical and electrical conditions such as contact force, currents, aerodynamics of pantograph and tension of overhead contact wire. For the characteristic of dynamic performance between pantograph and overhead contact wire, various evaluation systems are used to measuring of the interaction of the contact line and the pantograph. Among the various methods, the contact force and percentage of arcing are intended to prove the safety and the quality of the current collection system on the train. However, these methods are only capable of measuring on the train which are installed measurement systems. Therefore in this paper, a track-side monitoring system was implemented to measure electrical characteristics from active overhead contact wire systems in order to constantly estimate current collection performance of railway operation. In addition, a method to analyze loss of contact phenomena was proposed. According to simulation results, the proposed system was capable of measuring abnormal electrical behavior of pantograph and contact wires on the track-side. The advantage of the proposed system is possible to detect loss of contact or any other electrical abnormalities of all types of trains within sections from sub to sub without the need to install any on-board equipment on trains.

• 한국항해항만학회지
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• 제35권6호
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• pp.463-467
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• 2011

최근 선박의 안전운항에 대한 요구가 증가되면서, 국제해사기구에서는 SOLAS규정에 따라 선박의 다양한 정보를 제공하는 AIS의 의무 장착을 시행하고 있다. AIS장비는 선박의 자선 정보를 주변 선박 및 육상에 자동으로 브로드캐스팅방식으로 발신하고, 또한 주변 선박의 정보를 수신할 수 있는 장비이다. 최근에는 다양한 디스플레이 장치에 서비스를 제공하기 위한 시도가 진행되고 있으며, 특히 웹 응용을 이용하는 사례가 많아지고 있다. 본 논문에서는 이러한 웹 기반 응용에 대한 실현을 실험해보기 위해, 온라인 기반의 상용지도를 이용해 AIS 정보를 확인할 수 있는 디스플레이 시스템을 구현해 보았다. AIS수신 메시지 분석을 통해 주변 선박 정보를 분류하고, 상용지도는 구글 맵을 사용했으며, 디스플레이 처리를 위해서는 차세대 웹 표준인 HTML5 기술을 이용하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2018년도 춘계학술대회
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• pp.318-320
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• 2018

When a ship sails on sea, it may be influenced by the environmental disturbance such as wind, wave, sea surface temperature, etc. These affect on the ship's speed, fuel consumption, safety and operating performance. It is necessary to find the optimal weather route of a ship to avoid adverse weather conditions which can put the crews in serious danger or cause structural damage to the vessel, machinery, and equipment. This study introduced how to apply A* algorithm based on sea trial test data for determining the optimal ship routes. The path cost function was modelled as a function of minimum arrival time or minimum energy depending on the time of various environment conditions. The specially modelled path-cost function and the safety constraints were applied to the A* algorithm in order to find the optimal path of the ship. The comparison of ship performances estimated by real sea trial's path and estimated optimal route during the voyage of the ship was investigated. The result of this study can be used to create a schedule to ensure safe operation of the ship with short passage time or minimum energy. In addition, the result of this study can be integrated into an on-board decision supporting expert system and displayed in Electronic Chart Display and Information System (ECDIS) to provide all the useful information to ship master.

• 한국운동역학회지
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• 제31권3호
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• pp.183-188
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• 2021

Objective: The purpose of this study was to develop a stretchable joint motion sensor that is based on silver nano-particle. Through this sensor, it can be utilized as an equipment for rehabilitation and analyze joint movement. Method: In this study, precursor solution was created, after that, nozel printer (Musashi, Image master 350PC) was used to print on a circuit board. Sourcemeter (Keithley, Keithley-2450) was used in order to evaluate changes of electric resistance as the sensor stretches. In addition, the sensor was attached on center of a knee joint to 2 male adults, and performed knee flexion-extension in order to evaluate accurate analysis; 3 infrared cameras (100 Hz, Motion Master 100, Visol Inc., Korea) were also used to analyze three dimensional movement. Descriptive statistics were suggested for comparing each accuracy of measurement variables of joint motions with the sensor and 3D motions. Results: The change of electric resistance of the sensor indicated multiple of 30 times from initial value in 50% of elongation and the value of electric resistance were distinctively classified by following 10%, 20%, 30%, 40% of elongation respectively. Through using the sensor and 3D camera to analyze movement variable, it showed a resistance of 99% in a knee joint extension, whereas, it indicated about 80% in flexion phase. Conclusion: In this research, the stretchable joint motion sensor was created based on silver nanoparticle that has high conductivity. If the sensor stretches, the distance between nanoparticles recede which lead gradual disconnection of an electric circuit and to have increment of electric resistance. Through evaluating angle of knee joints with observation of sensor's electric resistance, it showed similar a result and propensity from 3D motion analysis. However, unstable electric resistance of the stretchable sensor was observed when it stretches to maximum length, or went through numerous joint movements. Therefore, the sensor need complement that requires stability when it comes to measuring motions in any condition.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.807-817
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• 2019

Airborne Gamma Ray Spectrometry (AGRS) with its important applications such as gathering radiation information of ground surface, geochemistry measuring of the abundance of Potassium, Thorium and Uranium in outer earth layer, environmental and nuclear site surveillance has a key role in the field of nuclear science and human life. The Broyden-Fletcher-Goldfarb-Shanno (BFGS), with its advanced numerical unconstrained nonlinear optimization in collaboration with Artificial Neural Networks (ANNs) provides a noteworthy opportunity for modern AGRS. In this study a new AGRS system empowered by ANN-BFGS has been proposed and evaluated on available empirical AGRS data. To that effect different architectures of adaptive ANN-BFGS were implemented for a sort of published experimental AGRS outputs. The selected approach among of various training methods, with its low iteration cost and nondiagonal scaling allocation is a new powerful algorithm for AGRS data due to its inherent stochastic properties. Experiments were performed by different architectures and trainings, the selected scheme achieved the smallest number of epochs, the minimum Mean Square Error (MSE) and the maximum performance in compare with different types of optimization strategies and algorithms. The proposed method is capable to be implemented on a cost effective and minimum electronic equipment to present its real-time process, which will let it to be used on board a light Unmanned Aerial Vehicle (UAV). The advanced adaptation properties and models of neural network, the training of stochastic process and its implementation on DSP outstands an affordable, reliable and low cost AGRS design. The main outcome of the study shows this method increases the quality of curvature information of AGRS data while cost of the algorithm is reduced in each iteration so the proposed ANN-BFGS is a trustworthy appropriate model for Gamma-ray data reconstruction and analysis based on advanced novel artificial intelligence systems.

• The Journal of Korean Physical Therapy
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• 제2권1호
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• pp.75-83
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• 1990

The purpose of this study was to determine if any differences exist in eye contact before and after vestibulaar stimulation in mentally retarded children. The subjects of this study were 20 mentally retarded children with a mean age of 9 years and 8 months and a mean intelligence quotient of $30.4{\pm}9.1$. Vestibular stimulation was given for 15 minutes, 5 times a week, for 4 weeks from September 1 to September 30, 1989. Equipment used included a rocking-horse, see-saw and scooter board. Two testers used a digital watch calibrated to 1/100 second to measure object-eye contact duration and the Blocks and Shapes test for determining frequency of object-eye contact in the subjects. The results of this study were as follows : 1. There was a significant prolongation in the duration of eye contact after 15 minutes of vestibular stimulation (p<0.005). 2. There was no significant difference in duration of eye-object contact between the first and last vestibular stimulation. 3. There was no significant difference in the length of time of attention paid to objects (frequency of eye-object contact) before and after 15 minutes of vestibular stimulation on the first vestibular stimulation. 4. There was no significant difference in the frequency of eye-object contact between the first and first vestibular stimulation. In conclusion, there was u significant improvement in duration of eye-object contact on intrasession measurement in mentally retarded children. However, there was no significant improvement over time after 4 weeks of vestibular stimulation on intersession measurement. Nor was there any statistically significant improvement in frequency of eye-object contact over time during the study period.

• 대한임베디드공학회논문지
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• 제13권1호
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• pp.17-24
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• 2018

Military camera equipment has a problem that observability is inferior due to various shaking factors. In this paper, we propose an image stabilization algorithm considering performance and execution time to solve this problem and implemented it in Zynq SoC. We stabilized both the simple shaking in the fixed observation position and the sudden shaking in the moving observation position. The feature of the input image is extracted by the Sobel edge algorithm, the subblock with the large edge data is selected, and the motion vector, which is the compensation reference, is calculated through template matching using the 3-step search algorithm of the region of interest. In addition, the proposed algorithm can distinguish the shaking caused by the simple shaking and the movement by using the Kalman filter, and the stabilized image can be obtained by minimizing the loss of image information. To demonstrate the effectiveness of the proposed algorithm, experiments on various images were performed. In comparison, PSNR is improved in the range of 2.6725~3.1629 (dB) and image loss is reduced from 41% to 15%. On the other hand, we implemented the hardware-software integrated design using HLS of Xilinx SDSoC tool and confirmed that it operates at 32 fps on the Zynq board, and realized SoC that operates with real-time processing.

• 한국철도학회논문집
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• 제15권1호
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• pp.37-41
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• 2012

경부고속철도는 운영환경(차량,구배,곡선,시설물 등)에 따라 궤도회로를 여러 개의폐색으로 분할하여 운행하는 고정폐색방식의 열차제어시스템으로 운행된다. 고정폐색방식 열차제어시스템은 선행열차의 점유폐색을 기준으로 진입/진출폐색속도, 목표거리, 감속도와 같은 운행정보를 차상열차제어장치로 전송하여 연속적으로 열차를 제어하는 방식으로, 경부고속철도 열차제어시스템은 열차가 해당 폐색의 진입/진출속도를 초과할 경우, 비상제동명령을 내려 열차의 안전한 운행을 보장한다. 본 논문에서는 안전한 운행을 위해 폐색에 할당되는 속도제어코드의 생성원리를 분석하여, 최고운행속도와 운행차량특성에 따른 속도제어코드를 도출하고, 도출된 속도제어코드에 따른 운행시격 분석을 통해 열차 운행효율을 분석하였다. 이와 같은 연구는 기존 고속철도의 증속 및 신규 고속철도 열차제어시스템 설계 자료로 활용될 수 있다.

• 컴퓨터교육학회논문지
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• 제10권6호
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• pp.11-18
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• 2007

본 논문에서 구현된 논리회로 가상실험실은 원리이해를 위한 개념학습실과 가상 디지털 키트에 의한 가상실험실의 두 단계로 설계하였다. 개념학습실에서 학습자는 디지털 논리회로에 대한 중요한 원리나 의미를 쉽게 이해할 수 있도록 하였다. 가상실험실에서는 가상 브레드보드에서 회로를 결선하여 입력전압을 인가하여 출력신호를 측정한 다음 가상실험데이터와 비교하여 서버로 전송한다. 가상실험실에서 수행된 모든 실험활동은 데이터베이스에 저장되어 개인정보와 함께 예비보고서의 형태로 제공되어 교수자는 학습자가 얼마나 회로동작에 대해 잘 이해하였는가를 점검할 수 있도록 하였다. 마지막으로 제안된 가상실험시스템의 유효성을 입증하기 위해 한 학기 동안 실험 중에 발생한 실제 장비의 파손율과 학생들의 성취도를 5개의 설문을 통해 조사하여 분석하였다.

• 한국항해학회지
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• 제22권2호
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• pp.13-22
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• 1998

선재용 자동식별시스템(AIS)은 21세기에 선박식별, 감시, 통신에 사용하기 위한 중요한 해상장비가 될 것 이며, 현재 여러 선진국에서 개발중에 있다. 본 논문에서는 AIS의 기술적인 방법을 제시하고자 한다. AIS의 주요 부분은 방송트랜스폰더(broadcast transponder)이고 핵심기술은 STDMA(self-organized Time Division Multiple Access)라 불리는 고용량의 VHF 라디오 데이터링크(radio data link)이다. 해상 VHF채널로 자신의 위치와 신분(identities)을 자동적이고 주기적으로 방송하게 될 AIS가 설치된 선박들은 선상이나 VTS 센터에 있는 ECDIC의 서면에 표시가 될 것이다. AIS는 방송서비스뿐만 아니라 일대일(point topoint) 통신 서비스를 지원하게 될 것이다. 본 논문에서는 STDMA의 방안 뿐만 아니라 AIS의 구성과 동작원리 그리고 기능을 설명하고자한다. 이외에 IMO에서의 AIS에 관한 표준화 작업을 본 논문에 소개하고자 한다.