• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.667-671
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• 2005

This study was carried out to examine the prediction of ship's manoeuvrability in initial design stage. New parameter representing basic hull form and stem shape were proposed. Captive model test were carried out to investigate the correlation coefficient between hydrodynamic coefficient and hull parameter. The results showed which parameter are positive correlation with hydrodynamic coefficient. Moreover correlation was examined between stem hull shape and ship's manoeuvrability. New empirical formulas for hydrodynamic coefficients were proposed These results can be used to predict a ship's manoeuvrability in initial design stage.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.896-897
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• 2015

본 연구는 3D 이미지 스캔 데이터 기반으로, SWEEPING 형상을 효과적으로 역설계하는 기술에 관한 것이다. 사용자가 미리 정의한 형상 단면 모델 데이터베이스를 이용해, 3차원 SWEEPING 형상을 자동으로 역설계하는 알고리즘을 제안한다. 이를 위해, 3D 이미지 스캔 데이터인 포인트 클라우드에서 자동으로 추출한 단면 포인트들을 처리해, 파라메터 정보를 추출하고, 미리 정의된 형상 단면들과 상호간 유사도를 비교한 후, 가장 유사한 형상 단면을 획득한다. 이러한 기술은 SWEEPING 형상 모델의 역설계 과정을 자동화하는 데 도움을 줄 것이다.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.224-227
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• 2000

본 논문에서는 기준 영상으로부터 면의 반사특성을 검출하고, 구해진 반사특성을 임의의 물체에 적용하여 3매의 명암영상을 얻는다. 이 영상을 측광입체시법(photometric stereo method)에 적용하여 3차원 형상인식하는 방법을 제시한다. 본 연구에서 목적으로 하는 물체의 반사특성은 난반사(diffuse reflection)성분과 전반사(specular reflection)성분이 혼합된 혼합 반사면(hybrid reflectance surface)을 그 대상으로 하며, 이러한 면의 반사특성은 Torrance-sparrow모델로 가정하여 문제를 해결해 나간다. 본 연구에서 목적으로 하는 대상 물체는 동일한 재질로 이루어졌다는 가정 하에서 몇개의 표본점들을 취해 반복수치 계산하기 때문에 계산속도가 빠르며, 각 표본점들로부터 계산된 면특성 파라메터들의 평균값을 취해서 다시 Torrance-sparrow모델에 적용함으로써 측광입체시법의 해석을 가능토록 한다. 즉, 3차원 형상인식 과정시 계산된 면특성 파라메터를 사용해 생성한 참조표와 명암영상과의 비교에 의해 빠른 면방향 복구를 행할 수 있다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.103-107
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• 2005

This study was carried out to examine the prediction of ship's manoeuvrability in initial design stage. New parameter representing basic hull form and stern shape were proposed. Captive model test were carried out to investigate the correlation coefficient between hydrodynamic coefficient and hull parameter. The results showed which parameter are positive correlation with hydrodynamic coefficient. Moreover correlation was examined between sternhull shape and ship's manoeuvrability. These results can be used to predict a ship's manoeuvrability in initial design stage.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.92-92
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• 2017

밭작물 중 마늘 재배를 위한 노동력 투입시간은 2016년 기준 10a 당 126.9시간 이었고, 파종정식의 기계화율은 2015년 기준 15.1%로 조사된다. 이는 마늘 재배에 있어서 파종정식의 기계화가 노동력 절감을 위해 필요하다는 것을 보여준다. 현재의 우리나라 마늘 파종기는 점파식으로 개발, 판매되고 있는데 집개 방식 또는 버킷 방식은 파종 속도를 올리면 파종율이 떨어지기 때문에 파종 속도를 향상시키는데 한계가 있있다. 본 연구에서는 이를 보완하기 위하여 콩, 옥수수 등의 종자에 사용되는 진공식 파종 기술을 마늘에 적용하였다. 마늘의 경우 형상이 비대칭형에다가 종구별 크기, 모양, 무게가 조금씩 다르기 때문에 이론적으로 흡입구를 설계하는 어려움이 있다. 따라서 진공흡입구의 지름과 재질을 파라메터로 하여 변화를 주고 실험을 통하여 배종률 결과의 차이를 확인하였다. 그 결과 경도 $10{\pm}2$의 실리콘 재질에 지름 14mm이상에서 90%이상의 높은 배종률을 보여주었다.

• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.106-114
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• 2010

Mesh parameterization is the process of finding one-to-one mapping between an input mesh and a parametric domain. It has been considered as a fundamental tool for digital geometric processing which is required to develop several applications of digital geometries. In this paper, we propose a novel 3D volume parameterization by means that a harmonic mapping is established between a 3D volume mesh and a unit solid cube. To do that, we firstly partition the boundary of the given 3D volume mesh into the six different rectangular patches whose adjacencies are topologically identical to those of a surface cube. Based on the partitioning result, we compute the boundary condition as a precondition for computing a volume mesh parameterization. Finally, the volume mesh parameterization with a low-distortion can be accomplished by performing a harmonic mapping, which minimizes the harmonic energy, with satisfying the boundary condition. Experimental results show that our method is efficient enough to compute 3D volume mesh parameterization for several models, each of whose topology is identical to a solid sphere.

• Composites Research
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• v.19 no.2
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• pp.13-19
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• 2006

In this paper, parametric study was carried out to design sandwich structures for EDM machines controlling stacking sequence, stacking thickness of composites and rib configuration. Sandwich structures which are dealt with in this paper are composed of fibre reinforced composite for skin material and foam or resin concrete for core materials. The sandwich column has cruciform rib to enhance bending stiffness of the structure and the bed has several vertical ribs to resist the normal forces and vibration. The design parameters such as rib thickness and stacking sequence were controlled to enhance the system robustness. Finite element analysis was also carried out to verify the variation of static and dynamic stiffness of the structures according to the variation of the parameters. Vibration tests were performed to verify the natural frequencies and damping ratios of the manufactured composite structures. The appropriate shape and configuration conditions for micro-EDM machine structures are proposed.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.601-610
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• 2008

This paper deals with a new geometrical surface modeling method of forebody's hull form which is fully defined by form parameters. The complex hull form in the forebody can be modeled by the combination of three parts: bare hull, bulbous bow and blending part which connects a bare hull and a bulbous bow. All these subdomain parts are characterized by each own form parameters and constructed with simple surface model. For this, we need only 2-dimensional hull form data and then the form parameters are calculated automatically from these data. Finally, the smooth hull form surfaces are generated by parametric design and fair-skinning. In the practical point of view, we show that this new method can be useful and efficient modeling tool by applying to the hull form surface modeling of Panamax container's forebody.

• The KIPS Transactions:PartB
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• v.12B no.5 s.101
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• pp.567-576
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• 2005

This paper proposes an image-based modeling method which recovers 3D models using projected line segments in multiple images. Using the method, a user obtains accurate 3D model data via several steps of simple manual works. The embedded nonlinear minimization technique in the model parameter estimation stage is based on the distances between the user provided image line segments and the projected line segments of primitives. We define an error using a finite line segment and thus increase accuracy in the model parameter estimation. The error is defined as the sum of differences between the observed image line segments provided by the user and the predicted image line segments which are computed using the current model parameters and camera parameters. The method is robust in a sense that it recovers 3D structures even from partially occluded objects and it does not be seriously affected by small measurement errors in the reconstruction process. This paper also describesexperimental results from real images and difficulties and tricks that are found while implementing the image-based modeler.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.10a
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• pp.35-38
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• 2003

현재, 세계 여러나라에서 해상물표를 정확하게 탐지 및 검출하기 위한 방안으로 레이더 clutter 신호를 효과적으로 억제 및 제거하기 위한 연구가 활발하게 진행되고 있다. 일반적으로 레이더 반사파에 대한 envelope 신호의 진폭는 Rayleigh 분포에 따라 변동하는 특성을 나타내지만, clutter의 진폭분포의 파라 메터가 변동하여 분포형상이 변화하면, 오경보확률(false alarm probability)에도 변화가 발생하기 때문에 오경보확률을 충분히 낮은 일정치로써 억제시켜 일정오경보확률(constant false alarm rate, CFAR)을 유지하는 처리가 필요하다. (중략)