• 전자공학회논문지 IE
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• v.43 no.4
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• pp.76-82
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• 2006

Wheels' Direction Indicator, an electronic direction displaying system, provides a driver with information of wheels' direction in real time. The purpose of this study is to develop the system showing on LCD and LED with measuring steering wheel's movement. This system that applies a steering wheel's movement to the data process part will reduce inconvenience that confirms wheels' direction before throughout the open window before driving a car in parking lot.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.31-33
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• 2006

전력수요의 증가에 대하여 전력을 공급하는 발전기의 대용량화, 고전압화 소형경량화 됨에 따라 발전기 고장 예방을 위한 진단이 더욱더 중요시되고 있다. 이들 발전기의 전기적 고장의 대부분은 고정자 및 회전자 권선에서 발생하며 이의 고장을 복구하는데 장시간이 요구되므로, 발전기의 예측진단에 따른 정비와 더불어 고장을 미연에 발견하고 불시정지에 따른 파급을 막기 위해서는 상시감시가 요구된다. 본 연구에서는 소용량 동기발전기를 이용하여 발전기 회전자권선의 단락 고장진단을 위한 공극에서의 자속패턴을 상용 전자장해석 전문프로그램을 이용하여 수치적으로 계산하여 도출하였으며, 또한 실제 회전자 권선 단락 실험을 통하여 실제 공극에서의 자속패턴과 전자장 해석결과와 비교를 하여 전자장 해석결과의 신뢰성을 확보 하였다.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.28-30
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• 2006

본 논문에서는 대용량 동기발전기 회전자 권선의 다양한 단락사고 유형에 따라 발생하는 공극자속 파형의 변형정도에 대한 민감도해석을 수행하였다. 우선 정밀 전자장 수치해석도구를 이용하여 발전기 회전자 권선의 단락사고 유형에 대한 과도상태 해석을 수행하여 공극자속 파형에 대한 기본 데이터를 수집하였다. 이를 바탕으로 정상상태의 공극자속 파형을 기준으로 각 단락사고 유형별로 발생하는 공극자속 파형에 대한 최대 전압차에 다구찌법을 적용하여 Signal to Nose(SN) ratio 및 Percentage Contribution(PC) 등을 분석함으로써 단락사고 유형에 따른 공극자속 파형의 변형정도를 정량화하였다. 따라서 본 연구결과는 향후 대용량 발전기 회전자 단락사고 진단 및 감시 시스템 구축에 관련한 분야에 중요한 기초데이터로 활용될 것으로 사료된다.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.265-266
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• 2011

본 연구에서는 유한요소 해석 방법을 이용하여 척추 퇴행성 질환을 가진 환자의 관절 불안정 모델을 개발 및 검증하였다. 관절 불안정 모델은 정상요추 유한요소 모델의 인대 및 협부를 결손시켜 개발하였으며, 요추 유한요소 모델의 제 5 요추체를 완전히 고정시키고 추적 경로 방향의 400 N의 압축력을 가한 상태에서 10 Nm의 굴곡과 신전 모멘트를 가하였다. 굽힘 및 신전 시 관절 불안정 모델들의 회전량이 정상의 요추 모델의 회전량에 비하여 크게 나타났다. 또한 굽힘 시 관절 불안정 모델들의 전위거리가 정상에 비하여 크게 나타났다. 본 연구의 결과는 척추 불안정성의 원인 및 기전의 이해뿐만 아니라 다양한 인체정보 콘텐츠 분야에 널리 활용될 수 있을 것으로 생각된다.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.267-268
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• 2011

본 연구에서는 유한요소 해석 방법을 이용하여 경추 유한요소 모델을 개발하고, 척추 인공디스크 수술 후 경추 분절의 생체역학적 특성을 평가하였다. 반구속 및 비구속 개념의 인공디스크가 삽입된 경추 유한요소 모델의 제 7 경추체를 완전히 고정시키고 추적 경로 방향의 50 N의 압축력을 가한 상태에서 1 Nm의 굴곡과 신전, 측면 굴곡, 비틀림 모멘트를 가하였다. 모든 방향의 하중 조건에서 인공디스크가 삽입된 경추 모델들의 회전량이 정상 경추 모델의 회전량에 비하여 크게 나타났다. 또한 인공디스크를 삽입한 운동 분절에서 정상에 비하여 후관절의 접촉력과 여섯 가지 주요 인대에 걸리는 응력이 높게 나타났다. 본 연구의 결과는 척추 인공디스크 수술 시 수술 방법의 선택뿐만 아니라 새로운 경추 수술용 임플란트 개발을 위한 인체정보 콘텐츠를 구축하는데 유용하게 활용될 수 있을 것으로 기대된다.

• Journal of the Korean Geotechnical Society
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• v.23 no.7
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• pp.57-64
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• 2007

This study proposes a method to estimate drilling torque during ground boring with an aid of electrical energy required for rotating a boring-auger. Ground boring is commonly used in geotechnical engineering such as preboring precast pile installation, soil-cement grouting, ground exploration and so forth. In order to understand the correlation between required electrical energy to rotate the boring auger and the drilling torque, a small laboratory apparatus was designed and a pilot study was performed. The apparatus rotates common drill bits of $D=5{\sim}25mm$ in CBR specimens. The velocity of a bit is 19 RPM and predefined using a reduction gear which connects a main rotation axis to a 25 Watts AC electrical motor shaft. In the middle of drilling the motor current increments and the drilling torque were measured and the correlation between the current and the torque was obtained through linear square fits. Based on the correlation the acquired motor current during drilling was applied to predict the drilling torque in consequent testing and the prediction results were compared to the measured torque. The comparison leads a conclusion that the motor current during drilling using electrical power may be a good indicator to estimate/determine strength characteristics of the ground.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1139-1148
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• 2000

To treat and recycle a large quantity of converter slag. the milling properties of -14/ +24 mesh-sized slag has been considered. The optimal conditions in milling process were investigated for producing powder-type slag and the required consumption was derived for the economical grinding. The characteristics of milling processes were studied in the variation of the rotational speed, milling time, filling ratio of ball, and size and amount of feed. The grinding efficiency was also examined. The optimal rotational speed in this experimental condition was observed to be the value of 79% of critical speed. The extent of grinding was increased with increasing the grinding time. but the efficiency of milling was decreased with the time. 50% ball filling was shown to have the optimal grinding effect, and less amount and small-sized feed made the milling efficiency high. As the result, using Bond's equation, power required for efficient milling was considered and the highest value was observed in the condition of high grinding time and optimal rotational speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.267-273
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• 2020

Suction anchors are used for floating structures because they have advantages in installation and stability. Recently, the demand for floating structures requiring low allowable displacement has increased. Thus, it is strongly suggested that the displacement of the suction anchor be evaluated. However, conventional studies regarding suction anchors have concentrated on the capacity of the anchor, and research on the displacement of the anchor is limited. In particular, rotation is the primary behavior of a suction anchor subjected to an inclined load, and related information has been insufficient. Therefore, the main objective of this paper is to investigate the rotation behavior of a suction anchor via centrifuge model tests. The experimental parameters are the inclination of the pull-out load, anchor dimensions, and aspect ratio. The rotation values of suction anchors were compared using a series of load-rotation curves. The results show that the inclination of the load has a dominant influence on the rotation behavior of the suction anchor.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.77-83
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• 2011

This study deals with the effectiveness of roundabout. The goal is to comparatively analyze the operational effectiveness related to the conversion of rotary to roundabout in Korea. In pursuing the above, this study gives particular attentions to investigating the existing 20 rotaries and developing the networks of before-and-after improvement using VISSIM, and comparatively analyzing the effectiveness. The domestic rotaries were analyzed to need many improvements of geometric structure for the effective operation of roundabout. The main results are as follow. First, when the present condition of traffic volume were applied, the operational effect of rotary were evaluated to be better than roundabout, but the difference analyzed to be small. Second, the average delay per vehicle in the rotaries of urban area were analyzed to rapidly increase according to the growth of traffic volume. Finally, the average speed of roundabout were evaluated to be less (about 10km/h) than that of rotary, because the traffic volume of rural area were less than that of urban area.

• Journal of Korean Society of Transportation
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• v.27 no.1
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• pp.157-167
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• 2009

This study deals with the turn penalty functions in the urban transportation demand forecasting. The objectives are to develop the penalty functions of left-turn traffic in the case of signalized intersections, and to analyze the applicability of the functions to the traffic assignment models. This is based on the background that the existing models can not effectively account for the delays of left-turn traffic which is bigger than that of through traffic. In pursuing the above, this study gives particular attention to developing the penalty functions based on the degrees of saturation by simulation results of Transyt-7F, and analyzing the applicability of the functions by the case study of Cheongju. The major findings are the followings. First, two penalty functions developed according to the degrees of saturation, are evaluated to be all statistically significant. Second, the results that the above functions apply to the Cheongju network, are analyzed to be converging, though the iteration numbers increase. Third, the link volumes forecasted by turn penalty functions are evaluated to be better fitted to the observed data than those by the existing models. Finally, the differences of traffic volumes assigned by two functions, which are exponential and divided forms, are analyzed to be very small.