• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.652-657
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• 2003

A wind-tunnel experiment is carried out to examine the applicability of a new passive device, wake disrupter, to flow over a model vehicle for drag reduction. The wake disrupter is a small-size rectangular body attached to a part of the trailing edge of the model vehicle, designed to perturb an essentially two-dimensional nature of wake. A pair of wake disrupter is mounted on the mid-span at the upper and lower trailing edges. From a parametric study about the size of wake disrupter, it is found that the optimum disrupter increases the base pressure by about 20%. Large eddy simulation is also conducted to confirm the experimental result, and shows that the wake is indeed disrupted by the present device.

• 한국의류산업학회지
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• 제18권4호
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• pp.457-467
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• 2016

This study aimed to develop functional underwear for elderly women in their sixties in terms of good fit, wear comfort and body temperature regulation. To satisfy elderly women's physical and metabolical needs, an automatic temperature control system via PCM treatment was applied. Underwear pattern was produced by producing body surface replica, which was derived from 3D body parametric model. Differential ratios of outline length and area between 3D surface and 2D plane were 1.4% and 0.5%, respectively. The reduction rate was determined as 10% through the expert's evaluation. PCM treated fabric showed higher Q-max, meaning that it can facilitate the thermal transition in hot situation. Moreover, it also showed higher insulation to preserve heat and keep warm microclimate in a cold weather. Heat distribution measurements on various body parts revealed that the temperature after PCM treatment was significantly higher. The clothing pressure after 10% pattern reduction showed higher before reduction, at the same time, even lower than the comfort clothing pressure range of $5{\sim}10gf/cm^2$, implying that experimental garment of this research is acceptable in terms of clothing pressure. Evaluation results on the comfort to move in various motions proved that adequate clothing pressure improved the wear comfort in various motions.

• 한국기계가공학회지
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• 제18권3호
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• pp.26-32
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• 2019

This study was conducted to analyze the stresses by impact loads on front-end loaders attached to tractors using flexible multi-body dynamics. The model was designed and validated by comparing previous experimental data with the simulation data obtained in this study. Nine sets of conditions were designed using three weights (500, 300, and 100 kg) loaded inside a bucket and three heights (1700, 1350, and 1000 mm) of the bucket from ground level. A parametric study was carried out at five locations for two types of parts of a front-end loader. All the safety factors for the five locations under all conditions were calculated and were greater than 1. Thus, the designs of the front-end loaders were structurally safe. Based on this study, front-end loaders attached to tractors can be designed effectively in terms of cost and safety.

• 한국의류산업학회지
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• 제16권6호
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• pp.961-970
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• 2014

Several retailers such as Target and Kohle's and their vendors have piloting the 3D clothing simulation programs to produce garment samples. However, few studies have verified the virtual fit information and 3d visualization process for pants, and no study compared the commercial 3D virtual programs. This study is designed to analyze similarity of fit and appearance between real pants with 3D virtual pants based on three 3D virtual programs (Optitex, CLO 3D, and i-Designer), three lower body types (slim, normal, and thick waist type), and fit status. We selected a representative model for each lower body type, produced their custom pants according to Lee and Nam's method(2007), and took photos of front, side and back view for visual analysis. Then, we virtually tried each model's custom pants on her parametric avatar developed by manually inputting their body measurements using the three 3D virtual program. Thirty fit experts compared the real fit to virtual fit. This study found that 'Optitex' and 'i-Designer' can visualize more effectively than 'CLO 3D' in many fit locations. Regarding the body types, 3D virtual program can visualize pants fit for 'thick waist body type' more preciously than the other body types. With respect to fit status, it does not affect much on the similarity overall.

• 한국음향학회지
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• 제11권4호
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• pp.5-13
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• 1992

엔진의 가진력으로 인해 발생되는 차량의 진동은 승차감에 큰 영향을 미치며, 또한 엔진 마운트 계의 동역학적 특성은 차량의 진동 및 소음에 직접적인 영향을 준다. 본 논문에서는 승용 지이프차의 엔진 key-off시 엔진 가진력으로 인한 차체 흔들림(body shake)을 실험을 통하여 측정함과 동시에 매카니즘해석 전용 프로그램인 DADS를 이용한 컴퓨터 시뮬레이션을 통하여 고찰하였다. 컴퓨터 시뮬레이션 모델은 엔진, 후레임이 포함된 차체, 앞 엑슬 그리고 뒤 엑슬로 구성되며, 각 엑슬은 좌우에 타이어를 고려하였다. 실험에서 얻은 차체 흔들림의 실험 결과와 컴퓨터 시뮬레이션한 결과를 비교 검토하였으며, 검증된 컴퓨터 시뮬레이션 모델을 통하여 엔진 마운트 고무의 강성, 엔진마운트의 설치각도 및 마운트 위치를 변경하여 key-off 시 자체 흔들림을 고찰함으로써 엔진 key-off 시의 차체 흔들림의 감소를 확인하였다.

• International Journal of Automotive Technology
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• 제8권3호
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• pp.327-335
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• 2007

A new optimization scheme and some key techniques are proposed in the development of a vehicle glass drop design software system. The key issues of the design system are how to regenerate the glass surface and make the vehicle glass drop down along the glass channels. To resolve these issues, a parameterized model was created at first, in which the optimizing method and Knowledge Fusion techniques were adopted the optimized process was then written into the glass drop design system by coding with C language and UGS/Open Application Programme Interface functions etc. Therefore, the designer or engineer can simulate the process of glass dropping along the channels to assess the potential interference between glass and door accessory by using this software system. All of the testing results demonstrate the validity of the optimizing scheme, and the parametric design software effectively solves the key issues on development of the door accessory package.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.369-372
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• 2006

Monolithic forging of cask is required continuously. Body-base monolithic forging of cask has advantage of an economical manufacturing process and better reliability for nuclear applications. Through the finite element analysis and parametric study of design variables, those are die angle, groove length and flange thickness, the optimal dimensions of preform and die sets are determined in order to develop a suitable forging process for body-base monolithic forging. To verify the result of finite element analysis, the physical model of 1/30 scale of actual product using plasticine was carried out. The result of this experiment, deformed shapes were very similar to the finite element analysis. As a result of this work, the special piercing method was developed using blank material consisting of a flange, groove and squared part.

• Journal of Ship and Ocean Technology
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• 제4권1호
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• pp.21-27
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• 2000

The slamming force occurring in the free fall impact of cylindrical bodies on the water surface is analyzed in both compressible and incompressible stages. In the compressible phase the hydrodynamic analysis is carried on by the acoustic approximation, obtaining a closed form expression for the maximum impact force. The incompressible analysis is approached through and unsteady boundary element method to compute the free surface evolution and the slamming force on the body. A similar behavior seems to characterize the maximum slamming force versus a dimensionless mass parameter.

• 디지털콘텐츠학회 논문지
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• 제13권2호
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• pp.255-262
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• 2012

사람 움직임 추적 알고리즘은 인간과 컴퓨터 상호작용, 화상회의, 감시 시스템, 게임 및 엔터테인먼트 분야에서 반드시 필요한 기술로 인식되고 있다. 과거 다양한 사람 움직임 추적 알고리즘들이 응용 프로그램의 특성에 따라 구현되고, 실시간성을 고려한 보다 효율적인 영상 처리, 컴퓨터 비전, 인터페이스 기술들을 적용하여 구현되고 있다. 본 논문에서는 타원체 형태의 신체 모델과 깊이값 정보를 갖는 3차원 점들과의 매칭을 통해 실시간으로 적용 가능한 움직임 추적 기술을 소개한다. 움직임 추적을 위한 기반 모델은 사람의 모습과 유사한 형태의 타원체 조합의 18개의 관절을 갖는 형태로 구성되어 지며, 영상으로부터 들어온 사람의 모습을 분석하여 일련의 신체 부위를 나누고, 그 정보를 바탕으로 역기구학 기반의 초기 자세를 추출한다. 초기 자세는 3차원 점 매칭 기법을 활용하여 보다 정확한 자세로 수정된다.

• 접착 및 계면
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• 제13권1호
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• pp.9-16
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• 2012

접착용 테이프 박리거동에 미치는 외부효과를 알아보고, 이를 설명하는 준강체 실린더 체인(semi-rigid body cylinder chain) 모델을 제안하였다. 먼저 평면으로부터 테이프를 떼어낼 때, 테이프의 거동을 정성적으로 파악하고, 이를 토대로 준강체 실린더 체인 모형을 도식화하였다. 그 다음 테이프를 떼어내는 힘에 미치는 여러 요소들(온도, 표면거칠기, 떼어내는 속도, 각도 의존성, 테이프 폭 등)의 효과와 이들의 민감도를 분석하여 동일한 실험 기준조건을 설정하고, 이 조건에서 평면으로부터 테이프를 떼어내는 힘(벡터)의 각도 의존성을 $10^{\circ}$ 간격으로 측정하였다. 실험결과는 본 연구에서 확립한 모형이론과 실험오차범위 내에서 잘 일치하였고, 다른 요소들의 효과는 현상론적 입장에서 정성적으로 잘 설명되었다. 이러한 이유로, 본 결과는 PSA 테이프의 접착력을 시험 평가하는 모델로 활용될 수 있을 것으로 기대된다.