• 대한기계학회논문집A
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• 제29권6호
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• pp.852-859
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• 2005

Molecular dynamics simulations of nanoimprint lithography in which a stamp with patterns is pressed onto amorphous poly-(methylmethacrylate) (PMMA) surface are performed to study the deformation of polymer. Force fields including bond, angle, torsion, inversion, van der Waals and electrostatic potential are used to describe the intermolecular and intramolecular force of PMMA molecules and stamp. Periodic boundary condition is used in horizontal direction and Nose-Hoover thermostat is used to control the system temperature. As the simulation results, the adhesion forces between stamp and polymer are calculated and the mechanism of deformation are investigated. The effects of the adhesion and friction forces on the polymer deformation are also studied to analyze the pattern transfer in nanoimprint lithography. The mechanism of polymer deformation is investigated by means of inspecting the indentation process, molecular configurational properties, and molecular configurational energies.

• 암석학회지
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• 제3권1호
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• pp.20-33
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• 1994

Some of the seven types of subgrain boundaries (Means and Ree, 1988) in octachloropropane samples show distinctive deformation patterns during their development. Type II subgrain boundaries migrate to accommodate the deformation difference between adjacent grains. The formation of Type III requires a rigid-body roation of grains to reduce misorientation of adjacent grains. Type I, IV, V and VI develop either in static or dynamic condition. Type VII form only in static environments after deformation. Ribbon grains can develop via Type III or Type IV process. The orientation pattern and density of subgrain boundaries are more or less stable through a post-deformation heating. Subgrain boundary orientations are symmetric with respect to the grain-shape foliation in pure shear. In simple shear, their maximum inclines toward the direction of shear.

• 대한기계학회논문집A
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• 제30권7호
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• pp.849-856
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• 2006

In this paper, fabric composite draping on hemisphere moulds were studied to find out the deformation behaviour of micro-tow structures of fabrics during draping and thermoforming. Aluminium and PVC foams were used to fabricate the hemisphere moulds for draping tests. In order to observe the local tow deformation pattern during the draping several specimens for microscopic observation were sectioned from the draped hemisphere structures. The effect of forming condition and mould properties on tow deformation was investigated by the microscopic observation of the tow parameters such as crimp angle. Normalization scheme was performed to compare tow parameter variations with different forming conditions. Stress-strain .elations of two different PVC foams (HT70 and HT110) were tested to investigate the effect of foam property on the micro-tow deformation during forming.

• Korea-Australia Rheology Journal
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• 제15권2호
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• pp.75-82
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• 2003

In this study, with the finite element method we numerically investigate the deformation of liquid drops surrounded by Newtonian or non-Newtonian viscous medium in the axisymmetric contraction flow. 1, 2 or 4 Newtonian or non-Newtonian drops are considered and the truncated power-law model is applied In order to describe non-Newtonian viscous behavior for both fluids. In this type of flow the drop exhibits considerably large deformation, and thus techniques of unstructured mesh generation and auto-remeshing are employed to accurately express the fluid mechanical behavior. We examine the deformation pattern of liquid drops with viscosity dependence different from that of the surrounding medium and also explain their interactions by comparing relative position or speed of drop front.

• 한국가시화정보학회지
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• 제19권3호
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• pp.77-83
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• 2021

Solid oxide fuel cell (SOFC) operates at high temperatures in range of 600-800℃. Since layers of SOFC are composed of different substances, different thermal expansion in SOFC can result in defects under high temperature conditions. For understanding relation between temperature field and the thermal deformation in SOFC, temperature and strain field were simultaneously estimated using thermographic phosphors by optical measurement. Temperature fields were obtained by the life-time method, and the temperature differences of one specimen was checked with thermocouple. The thermal deformation was estimated by digital image correlation (DIC) method with extracted phosphorescence images. To investigate the deformation accuracy of DIC measurement, thermographic phosphors were coated with and without grid pattern on aluminum surface. Simultaneous measurement of temperature fields and thermal deformation were carried out for YSZ. This study will be helpful to multi-sensing of temperature field and thermal deformation on SOFC cells.

• 한국광학회:학술대회논문집
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• 한국광학회 1996년도 Advance Program of 13th optics andquantum Electronics conference, 1996제13 회 광학 및 양자전자 학술 발표회 논문 요약집
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• pp.21-21
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• 1996

• 한국디지털건축인테리어학회논문집
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• 제13권4호
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• pp.5-12
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• 2013

Conceptual and technical design designated as digital architecture has been discussed with disorderly meaning as a conception only. Thus, this study aims at verification of development possibility for the digital architecture by analyzing how works of Frank Gehry have effect on nonlinearity of the digital architecture. Nonlinear characteristics appeared on works of Frank Gehry analyzed on the basis of expression techniques and modeling principle are as follows: 1) Initial works show a trend to gradually change and develop from horizontal and vertical linear structure to nonlinear pattern. 2) From a nonlinear modeling principle, initial works appear the primary deformation elements only, while afterwards, they are gradually developing to a pattern to mix the primary and secondary deformation elements as introduction of digital architecture. 3) Through specific cases, Frank Gehry has conducted attempts with various method for nonlinear pattern expression. 4) From the initial works to the latest works, continuity becomes higher and changed to nonlinear pattern. This study is significant from a viewpoint that it has verified development possibility of digital architecture by analyzing nonlinear trend of digital architecture for Frank Gehry and it is required to conduct multilateral researches related to the digital architecture.

• 화약ㆍ발파
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• 제37권2호
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• pp.1-13
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• 2019

본 연구에서는 도심지 발파에서 형성되는 분할 단면의 변형을 확인하기 위해 Visual FEA 유한요소 프로그램으로 발파 단면을 모델링하여 발파 기폭 패턴에 따른 최대주변형률을 분석하였고, Visual FEA 유한요소 프로그램으로 분석된 분할 단면과 현장 발파로 형성된 분할 단면을 비교하였다. 결과적으로, 발파 기폭 패턴에 따라 분할 단면에서 최대주변형률의 차이를 나타냈고, 전산해석과 현장 발파에서 분할 단면이 유사한 파형 형태를 보이는 것으로 확인되었다.

• 한국의류산업학회지
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• 제21권4호
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• pp.468-479
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• 2019

This study used a three-dimensional-analysis method to quantitatively analyze the change of clothing appearance according to a gusset added to bodice and sleeve patterns for men in their twenties. Comparing six different patterns, the study found that patterns P1 and P2 with little gusset did not have a large difference in the strain map, and pattern P6 had no gusset in the motion of raising the arm $28^{\circ}$ to the side (M1). When the arm was raised $45^{\circ}$ to the side (M2), the P1 pattern had the smallest deformation, and only the P5 pattern had a large deformation from the neck to the armhole area. In contrast, except for in the P3 pattern, large wrinkles formed in the front and back when the arm was raised above $158^{\circ}$ (M3) from the side of the waist to the armpit. In addition, P3 had the smallest change in the hem of the bodice and sleeves. However, the appearance of P2, P3, and P5 was excellent when the arm was moved forward (M4), and the P2 and P5 patterns were the smallest at the bodice and sleeve hem. The P6 pattern showed the least fitness in terms of function. In the case of raising the arm, there was a strong correlation between gusset size and motion function, but when the motion of the arm changed, the motion function did not improved just by changing the ease size.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.332-337
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• 2009

Recently, boss and rib test based on backward extrusion process was proposed to quantitative evaluate the interfacial friction condition in bulk forming process. In this test, the tube-shaped punch with hole pressurizes the workpiece so that the boss and rib are formed along the hole and outer surface of the punch. It was experimentally and numerically revealed that the height of boss is higher than that of the rib under the severe friction condition. This work is focused on the effect of the punch design and friction condition on deformation pattern in boss and rib test. From the boss and rib test simulations, it was found that there is slight variation in both the heights of boss and rib according to the length of punch land, nose radius, and face angle. However the hole diameter of the punch and the clearance between the punch and die have a significant influence on the heights of the boss and rib. In addition, the effect of flow stress was also investigated on the deformation patterns through FE simulations.