• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.172-175
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• 2007

The Performance of a PEMFC stack is strongly dependent on the uniform reactants distribution on MEA. The uniform distribution can be achieved by flow-field pattern and manifold design optimized to satisfy operating conditions. This paper investigates uniform reactants distribution in channels by changing manifold shape and inlet mass flow rate. Typical U and Z shape and modified U and Z shape manifolds with buffer zone were designed. To check the uniform reactants distribution, standard deviation of mass flow rate was compared. The numerical results show that the inlet mass flow rate, inlet shape, and manifolds shape are critical factor for uniform distribution.

• Composites Research
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• 제28권4호
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• pp.176-181
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• 2015

본 연구에서는 stuffed Whipple shield의 성능 향상을 목적으로, stuffed Whipple shield의 중간층에 적용되는 직물의 방탄 성능 향상 기법으로서 Z형 직물 디자인을 제안하였다. 직물은 경계조건에 의하여 충격 현상과 방탄 성능이 크게 변화하게 된다. 따라서 기존의 단순 적층식 직물과는 다른 경계조건을 갖는 Z형 직물을 제안하였고, Z형 직물의 방탄 성능을 확인하기 위하여 상용 프로그램 LS-DYNA를 이용한 아라미드 섬유사와 직물에 대한 충격해석을 수행하여 에너지 흡수 특성을 계산하고, 그 결과를 단순 적층식 섬유사와 직물의 경우와 비교하였다. 그 결과 Z형 직물은 단순 적층식 직물과는 다른 충격 거동을 보이고, 고속 영역에서 2 edge fixed, 4 edge fixed보다 높은 에너지 흡수율을 보이는 것을 확인하였다.

• 한국의상디자인학회지
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• 제25권1호
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• pp.33-47
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• 2023

In this study, the difference in human body dimensions between the age groups of Generation M (27 to 39 years old) and Generation Z (20 to 26 years old) was analyzed. This study also analyzed if there was a change in the body shape of the MZ generation, who have different sensibilities from the "young people" of the past. In addition, major changes in human body dimensions were carefully analyzed and presented as basic data for clothing design. Therefore, a t-test was performed to verify the significant differences in the measurements of each age group. To examine the change in human body measurements according to the measurement year, the 7th and 8th size Korea data statistics were analyzed. The main required dimensions of clothing design were analyzed graphically for visual changes according to measurement year and age group. As a result of the analysis, Generation Z was found to have a difference in body shape from Generation M, and is generally smaller and slimmer with broader shoulders. In addition, the body shape change between the 7th and 8th measurement periods was significantly higher than the 8th measurement overall. Height has increased and back length has become shorter, resulting in a larger ratio of lower body length. In addition, the proportion of obesity abnormalities has increased. Therefore, since the dimensional system set from the past data can cause problems for the fitting of clothing for the MZ generation, it is necessary to design the clothing and reset the dimensional system making it suitable for the changed the body shape of the MZ generation.

• Steel and Composite Structures
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• 제21권1호
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• pp.217-247
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• 2016

Five extended cylindrical reticulated shells are proposed by changing distribution rule of diagonal rods based on three fundamental types. Modeling programs for fundamental types and extended types of cylindrical reticulated shell are compiled by using the ANSYS Parametric Design Language (APDL). On this basis, conditional formulas are derived when the grid shape of cylindrical reticulated shells is equilateral triangle. Internal force analysis of cylindrical reticulated shells is carried out. The variation and distribution regularities of maximum displacement and stress are studied. A shape optimization program is proposed by adopting the sequence two-stage algorithm (RDQA) in FORTRAN environment based on the characteristics of cylindrical reticulated shells and the ideas of discrete variable optimization design. Shape optimization is achieved by considering the objective function of the minimum total steel consumption, global and locality constraints. The shape optimization for three fundamental types and five extended types is calculated with the span of 30 m~80 m and rise-span ratio of 1/7~1/3. The variations of the total steel consumption along with the span and rise-span ratio are analyzed with contrast to the results of shape optimization. The optimal combination of main design parameters for five extended cylindrical reticulated shells is investigated. The total steel consumption affected by distribution rule of diagonal rods is discussed. The results show that: (1) Parametric modeling method is simple, efficient and practical, which can quickly generate different types of cylindrical reticulated shells. (2) The mechanical properties of five extended cylindrical reticulated shells are better than their fundamental types. (3) The total steel consumption of cylindrical reticulated shells is optimized to be the least when rise-span ratio is 1/6. (4) The extended type of three-way grid cylindrical reticulated shell should be preferentially adopted in practical engineering. (5) The grid shape of reticulated shells should be designed to equilateral triangle as much as possible because of its reasonable stress and the lowest total steel consumption.

• 한국CDE학회논문집
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• 제8권2호
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• pp.65-74
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• 2003

For virtual reality, virtual manufacturing system, or simulation based design, we need to visualize very large and complex 3D models which are comprising of very large number of polygons. To overcome the limited hardware performance and to attain smooth realtime visualization, there have been many researches about algorithms which reduce the number of polygons to be processed by graphics hardware. One of these algorithms, occlusion culling is a method of rejecting the objects which are not visible because they are occluded by other objects, and then passing only the visible objects to graphics hardware. Existing occlusion culling algorithms have some shortcomings such as the required long preprocessing time, the limitation of occluder shape, or the need for special hardware implementation. In this study, an efficient occlusion culling algorithm is proposed. The proposed algorithm reads and analyzes Z-buffer of graphics hardware using Microsoft DirectX, and then determines each object's visibility. This proposed algorithm can speed up visualization by reading Z-buffer using DirectX which can access hardware directly compared to OpenGL, by reading only the region to which each object is projected instead of reading the whole Z-Buffer, and the proposed algorithm can perform more exact visibility test by using simplified model instead of using bounding box. For evaluation, the proposed algorithm was applied to very large polygonal models. And smooth realtime visualization was attained.

• 한국의상디자인학회지
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• 제24권3호
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• pp.111-125
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• 2022

Recently, the MZ generation has been leading overall fashion trends, and fashion companies focus on design, marketing, and new products targeting the MZ generation. However, it is expected that a fit problem may occur if the M and Z generations are combined when producing clothing. Therefore, this study aims to analyze the differences between the two groups by comparing the body size according to the classification of the M and Z generations. In addition, this study analyzes whether the body shape of the MZ generation is different from the past generations and analyzes major changes in body size for clothing manufacturing through graphical visualization. As for the research method, a t-test was conducted to verify the significant difference between the measurements for each age group. Generation M was defined as those who are 27-39 years old, and Generation Z was defined as those who are 20-26 years old. In order to examine the changes in body measurements according to the measurement year, the 7th Size Korea and 8th Size Korea data were analyzed. In order to examine the visual changes according to the measurement year and age group, major measurements of clothing construction were analyzed. As a result, it was found that Generation M had a significantly higher height item than Generation Z. Also, in terms of circumference, width, and thickness, Generation M was larger than Generation Z. But the size of the bra cup was larger in Generation Z than Generation M. As a result of analyzing the body size changes, in the height item, the 8th Size Korea measurements were found to be significantly higher in shoulder height and navel level waist height. In the length and circumference items, the 8th Size Korea measurements were larger than the 7th. In the width, thickness, and other items, the 8th measurements were larger than the 7th.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.391-396
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• 2000

Today most companies are designing their automobile shapes by using 3 dimensional CAD software, CATIA. And they used to design 2 dimensional press dies to do some elastic work on their products, but they are currently trying to make use of dimensional software, Pro-Engineer. In this case, they have to change the 3 dimensional product design data to the proper format data for the following process. This paper will show the data loss and the deformation during data transfer between CATIA and Pro-Engineer, and then suggest a solution for these problems. Product's surface will be automatically placed by automatic press tipping angle setting in CATIA to prevent the product from being stuck in the press die. The 2 dimensional section view which is based on the tipping angle setting is created by Z-map. And, to remove the data loss and the data deformation in pro-Engineer, the product surface are delivered to the next process after it is changed to the 2 dimensional Z-map curves in CATIA. finally, this paper suggests an algorithm to develop the automatic design program for the press layout which regenerates product shape surface from the previous process.

• 한국공작기계학회논문집
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• 제11권6호
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• pp.38-44
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• 2002

Today most companies are designing their automobile shapes by using 3 dimensional CAD software, CATIA. And they used to design 2 dimensional press dies to do some elastic work on their products, but they are currently trying to make use of 3 dimensional software, Pro-Engineer. In this case, they have to change the 3 dimensional product design data to the proper format data for the following process. This paper will show the data loss and the deformation during data transfer between CATIA and Pro-Engineer, and then suggest a solution for these problems. Product's surface will be automatically placed by automatic press tipping angle setting in CATIA to prevent the product from being stuck m the press die. The 2 dimensional section view which is based on the tipping angle setting is created by Z-map. And, to remove the data loss and the data deformation in Pro-Engineer, the product surface are delivered to the next process after it is changed to the 2 dimensional Z-map curves in CATIA. Finally, this paper suggests an algorithm to develop the automatic design program for the press layout which regenerates product shape surface from the previous process.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권8호
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• pp.463-468
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• 2004

This paper was applied space harmonic method as a characteristic analysis technique for slotless PMLSM. There is advantages of active response to the change of design parameters as well as reduction of the calculation time. The method can be overcome disadvantages of finite element analysis that needs long times calculation, repetitions of pre and post-process. In this paper, 3D-space harmonic method was applied to consider the precise description of end turn coil shape and the changes of characteristic according to changes of length of z-axis direction. The thrust of optimal design was performed using genetic algorithm to enhance the thrust which is the disadvantage of slotless type PMLSM. For design parameters, width of permanent magnet, width of coil, width of coil inner and lengths of z-axis direction were selected. For objective functions. thrust per weight. thrust per volume. multi-objective function was selected.

• 대한토목학회논문집
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• 제33권1호
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• pp.35-46
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• 2013

본 연구에서는 모듈러 강교량 상부모듈 구성파트의 효율적인 3차원 조립설계를 위하여 BIM(Building Information Modeling)의 핵심기술 요소인 파라메트릭 모델링 방법을 연구하였다. 모듈러 강교량 상부모듈 구성파트의 3차원 조립설계를 위하여 모듈의 조립체계를 상세수준(LoD: Level of Details) 3단계로 정의하였다. 모듈을 구성하는 각 파트들의 3차원 형상구성을 위한 요소들을 추출하여 매개변수, 매개변수에 따라 변하는 종속변수, 매개변수에 따라 변하지 않는 고정 값으로 구분하여 정의하였으며, 조립체계 단계에 따라 파트간의 공간적 조립규칙을 정의하였다. 공간적 위치를 구속하기 위하여 3차원 형상구성 요소간의 위치관계를 정의하였으며, X, Y, Z 축에 대한 자유도를 구속하기 위하여 기하학적 관계를 정의하였다. 또한, 정의한 조립규칙을 적용하여 모듈러 강교량 상부모듈의 3차원 조립설계를 위한 표준템플릿을 구축하였으며, 정의한 매개변수의 변화에 따른 강교량 상부모듈의 형상변화 검토를 통하여 파라메트릭 모델링 방법의 적용성을 검증하였다.