• 소성∙가공
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• 제15권3호
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• pp.220-225
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• 2006

This paper investigates the characteristics of a hydro-mechanical punching process. The hydro-mechanical punching process is divided into two stages: the first stage is the mechanical half piercing in which an upper punch goes down before the initial crack is occurred; the second stage is the hydro punching in which a lower punch goes up until the final fracture is occurred. Ductile fracture criteria such as the Cockcroft, Brozzo and Oyane are adopted to predict the fracture of sheet material. The index values of ductile fracture criteria are calculated with a user material subroutine, VUMAT in the ABAQUS Explicit. The hydrostatic pressure retards the initiation of a crack in the upper region of the blank and induces another crack in the lower region of the blank during the punching process. The final fracture zone is placed at the middle surface of the blank to the thickness direction. The result demonstrates that the hydro-mechanical punching process makes a finer shearing surface than the conventional one as hydrostatic pressure increases.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.425-428
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• 2009

Aerospace engine application needs to stand high temperature and pressure. Because of its mechanical properties such as high strength at high temperature, Alloy 718 is used aerospace engine application about 80%. But alloy 718's mechanical properties cause some problem to manufacturing profile ring like damage of material and mold. In this study, alloy 718's mechanical properties investigated for knowing its formability and using FE-Simulation for designing profile ring roll process and mold shape. Profile ring rolling processing is designed with "Initial material$\rightarrow$Blank$\rightarrow$Linear Ring$\rightarrow$Profilering". Blank's heating temperature is setting $1100^{\circ}C$ for manufacturing a trial profile ring on the basis of FE-Simulation. As a result of manufacturing alloy 718 profile ring, it is possible to make near target profile shape ring with all of the processing condition which gives in this study.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.149-152
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• 2000

By using a three-dimensional finite element program HydroFORM-3D based on a rigid-plastic model, the hydroforming process for automobile subfrmae is analyzed in this study. The goal of this study is to accomplish preform design and determine the level of internal pressure for producing final hydroformed subframe component. Prior to hydroforming, the initial tube blank must be bent to the approximate centerline of the final part to enable the tube to be placed in the die cavity, After then, a preforming operation like stamping is carried out to the prebent tube. Finally, hydroforming process is performed to the preformed tube to get the final production. And through ductile fracture theory, the failure, bursting, is predicted during hydroforming process for tube blank with different diameter.

• 소성∙가공
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• 제9권5호
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• pp.478-485
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• 2000

This study aims to Improve the productivity in forming of flanged thrust engine bearings from two kinds of laminated sheet materials by integrating the forming processes or by reducing the number of the subsequent sizing and machining processes or by modifying the forming tools used. For steel-Al rolled blank, a design scheme for the one-step forming operation and the geometry of the tool set required is suggested and is verified its usefulness by the finite element simulation. And for steel-Cu sintered blank, the results of experiment and finite element analysis show that it is possible to improve the dimensional accuracy of formed products and to reduce the number of sizing processes just by modifying the shape and dimensions of initial blanks and flange forming dies, and by controlling the spring force.

• 소성∙가공
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• 제7권4호
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• pp.382-392
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• 1998

Computer simulations and test trials were carried out to obtain the optimal stamping conditions of the die design of the laser welded automotive body. The stamping process including gravity deflection bead calibration binder wrap, forming and spring back was simulated and compared with the results obtained from test trials. The production variables were determined from a preliminary operation and they were investigated in the simulation and the test trials. The formability was tested under the various conditions, such as the initial position of blank, blank holding force, corner radius and the shape of drawbead. Sound products without fracture, wrinkling and excessive weldline movement were produced by applying results obtained this investigation.

• 대한환경공학회지
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• 제22권12호
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• pp.2163-2173
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• 2000

메탄자화균에 의한 코발트 제거의 최적 pH 영역은 6.0~12.0이었으나 메탄자화균을 넣지 않은 blank는 10.5~11.5이었다. 코발트의 제거능은 pH에 크게 의존하였으나 blank보다는 민감하지 않았다. 초기 pH 6.0에서 1.0 g/L의 메탄자화균을 투입했을 때 170 mg Co/g biomass가 제거되었다. SEM 분석 결과에 의하면 코발트는 메탄자확균의 표면이나 세포의 분비 고분자에 흡착되어 제거된 것으로 사료된다. 초기 pH 6.0, 400 mg Co/L에서 메탄자화균의 최적의 투입량은 1.0 g/L이었다. 2.0 M NaCl과 $NaNO_3$의 높은 이온강도 하에서도 코발트 제거능은 그다지 영향을 받지 않았다.

• International Journal of Advanced Culture Technology
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• 제10권3호
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• pp.174-183
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• 2022

The abstract should summarize the contents of the paper and written below the author information. Use the word "Abstract" as the title, in 12-point Times New Roman, boldface type, italicized, centered relative to the column, initially capitalized, fixed-spacing at 13 pt., 12 pt. spacing before the text and 6 pt. after. The abstract content is to be in 11-point, italicized, single spaced type. Leave one blank line after the abstract, and then begin the keywords. All manuscripts must be in English. When it comes to the issue of "virtual and real" in traditional Chinese painting, the first impression is to describe the problems of painting strokes and ink, layout of pictures, etc., but it runs through the initial conception of the work, creation in the middle and aesthetic appreciation of the work. It exists in the whole process of artistic creation and appreciation. In essence, it is a problem of aesthetic thinking and philosophical thinking. Because the traditional Chinese painting theory is influenced by Taoism, when the concept of "virtual and real" is implemented in the specific picture of Chinese painting, it is contained in the specific shape of "physics", that is, the painting theory research of "blank space" in the picture. Based on the traditional Taoist philosophy of China, this paper takes the "virtual and real" view in Lao Zhuang's thought as the research object, deeply analyzes and compares its relationship with the "virtual and real" in Chinese landscape painting, and finds out their artistic spirit, essential characteristics and how to present them. This paper mainly discusses the internal relationship between Taoist philosophy and "virtual and real" in Chinese landscape painting from the following aspects. The introduction expounds the origin, purpose, significance, innovation and research methods of the topic. This paper analyzes the philosophical thoughts about landscape in the philosophical thoughts represented by Lao Tzu and Zhuangzi. The development of Chinese traditional aesthetics theory is closely related to Taoist philosophy, which has laid the foundation and pointed out the direction for the development of Chinese painting theory since ancient times. It also discusses the influence of the Taoist philosophy of "the combination of the virtual and real" on the emergence and development of the artistic conception of landscape painting. Firstly, through the analysis of the artistic conception of landscape painting and its constituent factors, it is pointed out that the artistic conception is affected by the personality and the painting artistic conception. Secondly, through the Taoist thought of "the combination of the virtual and real" in landscape painting, so as to reflect that it is the source of the artistic conception of Chinese landscape painting. It is the unique spiritual concept of "Yin and Yang" and "virtual and real" that creates the unique "blank space" aesthetic realm of Chinese painting in the composition of the picture. Finally, it focuses on the "nothingness" in Taoist philosophy and the "blank space" in Chinese landscape painting. The connotation of the "blank space" in Chinese painting exceeds its own expressive significance, which makes the picture form the aesthetic principle of emotional blending, virtual and real combination and dynamic and static integration. Through the "blank space", it deepens the artistic characteristics of the picture and sublimates the expression of "form" in Chinese painting.

• 대한기계학회논문집A
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• 제34권8호
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• pp.1097-1103
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• 2010

사출성형에서 사출압력은 제품의 특성을 결정하는 주요인자이므로 성형품의 품질 향상을 위해 사출압력은 최소화 되어야 한다. 또한 휨 변형과 웰드라인은 사출성형에서의 대표적인 불량요인으로 사출성형품의 품질 향상을 위해 방지되어야 한다. 본 논문에서는 사출성형품의 품질 향상을 위해 설계 절차를 2 단계로 나눈다. 첫 번째 설계에서는 공정조건을 제어하여 사출압력과 휨 변형을 최소화 하기 위해 직교배열표를 이용한 전산실험을 수행하고 이를 이용하여 근사모델을 생성한 후 최적설계를 수행한다. 두 번째 설계에서는 유동경로 개선을 통한 웰드라인의 발생을 방지하기 위해 해석모델의 두께를 변경하고 웰드라인 발생 유무를 평가한다. 이러한 설계절차를 통해 사출압력과 휨 변형을 최소화하면서 웰드라인을 방지하여 본 논문에서 제안한 설계방법의 유효성을 보이고자 한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.125-128
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• 2002

The automotive industry have made an effort to reduce the weight of vehicle structures with increased safety, while initial model of the final product does not contain any prehistoric effects in a design stave. It takes lots of time to calculate forming effects that have great influences on the energy absorption of structures. In this paper, finite element inverse analysis is adopted to calculate forming effects, such as thickness variation and effective plastic strain as well as an initial blank shape with small amount of computation time. Crash analysis can be directly performed after inverse analysis of the forming process without remeshing scheme. The direct mesh mapping method is used to calculate an initial guess from the sliding constraint surface that is extracted from the die and punch set. Analysis results show that energy absorption of structures is increased with consideration of forming effects and finite element inverse analysis is usefully applicable to calculate forming erects of vehicle structures for the crash analysis.

• 항공우주기술
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• 제2권2호
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• pp.133-141
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• 2003

초소성 공정을 이용하여 구형 압력용기를 제작하는 경우 두께와 구형의 형상은 일정하지 않고 성형공정이 진행함에 따라 변하게 된다. 본 연구에서는 공정과정 동안 발생하는 초기 블랭크의 두께변화 예측을 이론적으로 해석하였다. 두께변화 예측을 위한 이론적인 모델은 Kuglov 등이 적용한 박막이론을 사용하였으며 요구되는 최종 두께를 얻기 위한 초기 블랭크의 두께, 블랭크의 균일한 변형을 얻기 위한 시간에 따른 압력 프로파일, 각 성형단계에서 위치에 따른 두께분포 및 시간에 따른 두께분포를 결정하였다. 공정 단계 전반에 걸쳐서 적용 모델 및 해석 프로그램의 적합성을 문헌의 시험 결과와 비교하여 검증하였다.