• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권7호
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• pp.437-443
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• 2004

In this work the AC loss measurement setup based on an iron core background magnet, not used in a conventional one, has been successfully developed. To prove its validity, a round-robin test for the same Bi-2223 tape sample among three institutes has been done. The results show that the self-field and magnetization losses from the developed setup well agree with the losses measured at two other institutes of Korea Basic Science Institute and Yokohama National University. The measured magnetization losses for parallel or perpendicular fields can be well predicted from the slab model or the strip model for a filamentary region. However the magnetization losses for longitudinal fields can be rather predicted by the slab model for a decoupled filament. The self-field losses are well explained by the Norris ellipse model.

• 한국통신학회논문지
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• 제31권11C호
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• pp.1071-1076
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• 2006

본 논문에서는 수화 인식을 위한 얼굴 및 손 추적시스템을 제안한다. 제안된 시스템은 검출 및 추적 단계로 구분된다. 검출 단계에서는 신호의 주체인 얼굴과 손에 위치한 피부 특징을 이용하였다. CbCr 공간에서의 타원 모델을 구성하여 피부 색상을 검출하고 피부 영역을 분할한다. 그리고 크기와 얼굴 특징을 이용하여 얼굴과 손 영역을 정의한다. 추적 단계에서는 동작 추정을 위하여 첫 번째 손 영역으로 예측된 다음의 손위치를 연산함으로써 두 번째 손의 영역을 유도해낸다. 그러나 갑작스런 움직임의 속도 변화가 있을 경우 연속된 프레임에서 추적된 위치는 부정확하였다. 이러한 점을 해결하고자 손 영역에 대하여 반복적인 재연산을 수행하여 적응적으로 영역을 찾음으로써 오차를 보정하도록 하였다. 실험 결과 제안된 방법은 기존의 방법보다 4%의 처리 시간이 증가된 반면, 예측 오차는 96.87%까지 감소시킬 수 있었다.

• Nuclear Engineering and Technology
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• 제43권2호
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• pp.133-140
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• 2011

In this paper, a deformation measurement technology for nuclear fuel rods is proposed. The deformation measurement system includes a high-definition CMOS image sensor, a lens, a semiconductor laser line beam marker, and optical and mechanical accessories. The basic idea of the proposed deformation measurement system is to illuminate the outer surface of a fuel rod with a collimated laser line beam at an angle of 45 degrees or higher. For this method, it is assumed that a nuclear fuel rod and the optical axis of the image sensor for observing the rod are vertically composed. The relative motion of the fuel rod in the horizontal direction causes the illuminated laser line beam to move vertically along the surface of the fuel rod. The resulting change of the laser line beam position on the surface of the fuel rod is imaged as a parabolic beam in the high-definition CMOS image sensor. An ellipse model is then extracted from the parabolic beam pattern. The center coordinates of the ellipse model are taken as the feature of the deformed fuel rod. The vertical offset of the feature point of the nuclear fuel rod is derived based on the displacement of the offset in the horizontal direction. Based on the experimental results for a nuclear fuel rod sample with a formation of surface crud, an inspection resolution of 50 ${\mu}m$ is achieved using the proposed method. In terms of the degree of precision, this inspection resolution is an improvement of more than 300% from a 150 ${\mu}m$ resolution, which is the conventional measurement criteria required for the deformation of neutron irradiated fuel rods.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.61-64
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• 2001

This paper proposes an automatic method for generating and 3D draping the skirt 3D models. The method constructs a 3D basic model of the skirts using elliptic cylinder and generates the various skirt 3D models by controlling the ellipses of the basic model. B-Spline approximates the wrinkles around the ellipse for the various 3D draping changing according to designs and textiles. We make some real skirts and investigate appearances for their drapes. This paper simulates their appearances and obtains good results. Furthermore, adaptation of the skirt 3D model to a personal character implements realistic coordination of the various skirts.

• 한국유체기계학회 논문집
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• 제14권5호
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• pp.55-62
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• 2011

Shape optimization of a Printed circuit heat exchanger (PCHE) has been performed by using three-dimensional Reynolds-Averaged Navier-Stokes (3-D RANS) analysis and surrogate modeling techniques. The objective function is defined as a linear combination of effectiveness of the PCHE term and pressure drop in the cold channels of the PCHE. The cold channel angle and the ellipse aspect ratio of the cold channel are used as design variables for the optimization. Design points are selected through Latin-hypercube sampling. The optimal point is determined through surrogate-based optimization method which uses 3-D RANS analyses at design points. The results of three types of surrogate model are compared each other. The results of the optimizations indicate improved performance in friction loss but low performance in effectiveness than the reference shape.

• 한국농공학회지
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• 제45권2호
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• pp.86-95
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• 2003

During this study, constant stress ratio tests with previous compression anisotropic stress history are performed on compacted decomposed granite soil sampled at Iksan, Jeonbuk. Yielding points are determined from stress-strain curves. The shape and characteristics of compression anisotropic yield curves is examined. In addition, the measured value of yielding curve and stress-strain behavior is predicted by Yasufuku's anisotropic constitutive model based on non-associated flow rule. The main results are summarized as follows : 1) Shape of yielding curves shows almost ellipse but asymmetry with respect to stress path during previous consolidation stress. 2) Yasufuku's anisotropic constitutive model is suitable in evaluation of yielding curves on anisotropic consolidated decomposed granite soil. 3) The predicted stress-strain curve shows reasonable agreement to measured behaviours.

• 수도
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• 통권30호
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• pp.57-62
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• 1984

본 연구는 급속여과지에 있어서 현탁물 부착모델에 관한 연구이다. 금회의 연구를 통하여 수정타원형 부착모델을 제안하여 실측치와 잘 일치하는 여과 저항식을 유도했다. 유도된 이 여과저항식은 금후 급속여과지 설계에 있어서 최적 높이 결정에 기여함으로써 경제적인 급속여과지를 설계하는데 중점을 두고 본 연구를 시행하였다.

• 한국생산제조학회지
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• 제21권6호
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• pp.938-945
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• 2012

This research proposes FEM analysis for Tandem welding process used in wind tower and predicts optimal welding process to improve the stability of welded structures. Three dimensional elasto-plastic analyses are employed to evaluate thermo-mechanical behavior of residual stress and deformation during Tandem welding for different distance between two touches. To confirm the thermal distribution, Goldak's ellipse heat source model and the real size wind tower pipe model are utilized. Four different analyses are being performed, where in each case the distance between two electrode torches is being changed and residual stress and welding deformation are predicted. Depending on base material state, each case is divided into: Liquid (100mm), Austenite+Liquid (200mm), Austenite+Cementite (400mm), Pearlite+Cementite (800mm).

• 대한조선학회논문집
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• 제32권1호
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• pp.58-69
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• 1995

본 논문에서는 이상유체모델에서의 비선형 자유표면파의 발생, 전파 및 상호간섭에 대한 비정상 문제의 수치해법을 개발하였다. 본 수치해법은 매 시간 스텝에서 비선형 축차해법을 이용한 음함수적(implicit)방법이다. 속도장함수를 구하기 위하여 경계접합좌표계를 도입한 유한차분법을 이용하였다. 본 수치해법의 유효성과 효율성의 검증을 위하여 타원형 유체의 변형과 바닥의 일부분이 올라옴으로서 발생하는 자유표면파의 생성에 대한 두 가지 계산결과를 보여준다.

• Fisheries and Aquatic Sciences
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• 제3권2호
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• pp.156-162
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• 2000

Model experiments for a purse seine were carried out in order to measure the geometry of net shape and to estimate an enclosed volume by using 1177 scale model purse seine of 12.62m float line from an offshore mackerel purse seine. A model purse seine was set from a net box of shooting equipments and then pursing and hauling net by hauling equipment. The 3- D geometry shape of the purse seine net during hauling operation was measured by video image processing and tension of purse line by load cell. The 3-D geometry of the model purse seine during hauling operation could be represented with variables such as a ratio of shooting diameter or maximum net depth and a ratio of hauling operation time. Horizontal shapes of float line and lead line were varied from a circle after shooting to an ellipse with pursing and hauling. Projected lateral shape of purse line was observed and formulated as a shape of a water drop. The cross sectional shapes of curved net from two directions were varied such as sine function or polynomial curves. Therefore, enclosed volume of a purse seine in relation to fish school behaviour can be approximated using two main variables from relevant equations.