• Korea-Australia Rheology Journal
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• 제19권3호
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• pp.147-156
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• 2007

The orientation and deformation of polymer chains in a confined channel flow has been investigated. The polymer chain was modeled as a Finitely Extensible Nonlinear Elastic (FENE) dumbbell. The Brownian configuration field method was extended to take the interaction between the flow and local chain dynamics into account. Drag and Brownian forces were treated as anisotropic in order to reflect the influence of the wall in the confined flow. Both Poiseuille flow and 4 : 1 contraction flow were considered. Of particular interest was molecular tumbling of polymer chains near the wall. It was strongly influenced by anisotropic drag and high shear close to the wall. We discussed the mechanism of this particular behavior in terms of the governing forces. The dumbbell configuration was determined not only by the wall interaction but also by the flow type of the geometric origin. The effect of extensional flow on dumbbell configuration was also discussed by comparing with the Poiseuille flow.

• 한국유통학회지:유통연구
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• 제10권2호
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• pp.1-26
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• 2005

본 연구는 증권거래 채널의 선택에 영향을 미치는 소비자 요인을 파악하는데 그 목적을 두고 있다. 본 연구는 오프라인 채널이 관계마케팅이 실현되는 채널이라는 관점과 온라인 채널은 인터넷 거래라는 관점에서 14개의 소비자 요인을 추출하였다. 자료 분석 결과 14개의 가설변수 가운데 8개 변수가 두 집단간에 유의한 차이를 보이는 것으로 나타났다. 즉, 대인 성향, 위험감수 성향, 투자 규모, 가격민감도, 인터넷 사용 시간, 혁신성, 정보 프라이버시 민감도, 내재적 정보 욕구 등의 변수에서 유의한 차이를 보였다. 유의하게 나타난 변수들을 독립변수로 하는 판별분석 결과는 이들 변수들 가운데에서도 특히 위험감수 성향, 인터넷 사용 시간, 정보 프라이버시 민감도 등의 변수들이 두 집단을 구분하는데 유용함을 보여주고 있다.

• Design & Manufacturing
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• 제12권2호
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• pp.27-33
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• 2018

Korea's automobile industry, which has grown rapidly to become the world's fifth-largest automobile producer, To cope with environmental pollution and energy problems in order to prevail competitive edge in global market We are investing a lot of research personnel and costs. Among them, for realizing alternative light weight It is a part of the automobile module system that has achieved the technological development before the breakthrough in the injection molding process in the press process. Door module PNL was the subject of research. The door module PNL is expected to cause warpage before the mold production due to the thin and flat product characteristics and fiber orientation characteristic of the material. In this paper, CAE analysis and reverse correction tool Design. CAE analysis to obtain the results of weld line position, bending position and deformation value Through the correction tool, think3, the original product was modified before the mold production to improve the completeness of the parts. In fiber orientation, the position and size of the cooling channel in the mold, the position and size of the gate, Temperature, pressure, time, and work environment. Compared with the result of CAE analysis, the product that was reverse-corrected by Think3 was manufactured, and injection molding was performed. Injection molding products were tested 24 hours later. 3.5 mm to 7.0 mm, and under the fixed condition, the deviation was from 1.1 mm to 1.5 mm. Unlike the CAE analysis, the deviation of the actual injection pressure and the cooling temperature, the fiber orientation of the material, In order to solve this problem, it is necessary to compare the injection conditions with the database, I knew I had to catch the standard.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.230-230
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• 2012

Graphene have showed promising performance as electrodes of organic devices such as organic transistors, light-emitting diodes, and photovoltaic solar cells. In particular, among various organic materials of graphene-based organic devices, pentacene has been regarded as one of the promising organic material because of its high mobility, chemical stability. In the bottom-contact device configuration generally used as graphene based pentacene devices, the morphology of the organic semiconductors at the interface between a channel and electrode is crucial to efficient charge transport from the electrode to the channel. For the high quality morphology, understanding of initial stages of pentacene growth is essential. In this study, we investigate self-assembly of pentacene molecules on graphene formed on a 6H-SiC (0001) substrate by scanning tunneling microscopy. At sub-monolayer coverage, adsorption of pentacene molecules on epitaxial graphene is affected by $6{\times}6$ pattern originates from the underlying buffer layer. And the orientation of pentacene in the ordered structure is aligned with the zigzag direction of the edge structure of single layer graphene. As coverage increased, intermolecular interactions become stronger than molecule-substrate interaction. As a result, herringbone structures the consequence of higher intermolecular interaction are observed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.163-163
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• 2015

The effect of nematic liquid crystal(5CB-4-Cyano-4'-pentylbiphenyl) on the amorphous indium gallium zinc oxide thin film transistors(a-IGZO TFTs) was investigated. Through dropping the 5CB on the a-IGZO TFT's channel layer which is deposited by RF-magnetron sputtering, properties of a-IGZO TFTs was dramatically improved. When drain bias was induced, 5CB molecules were oriented by Freedericksz transition generating positive charges to one side of dipoles. From increment of the capacitance by orientation of liquid crystals, the drain current was increased, and we analyzed these phenomena mathematically by using MOSFET model. Transfer characteristic showed improvement such as decreasing of subthreshold slope(SS) value 0.4 to 0.2 and 0.45 to 0.25 at linear region and saturation region, respectively. Furthermore, in positive bias system(PBS), prevention effect for electron trapping by 5CB liquid crystal dipoles was observed, which showing decrease of threshold voltage shift [(${\delta}V$]_TH) when induced +20V for 1~1000sec at the gate electrode.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.274.1-274.1
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• 2013

We report the circumferential alignment of human aortic smooth muscle cells (HASMCs) in an orthogonally micropatterned circular microfluidic channel to form an in vivo-like smooth muscle cell layer. To realize a biomimetic smooth muscle cell layer which is aligned perpendicular to the axis of blood vessel, we first fabricated a half-circular polydimethylsiloxane (PDMS) microchannel by soft lithography using a convex PDMS mold. The orthogonally micro wrinkle patterns were generated inside the half-circular microchannel by stretching-releasing operation under UV irradiation. Upon UV treatment with uniaxial 40 % stretch of a PDMS substrate and releasing process, the microwrinkle patterns perpendicular to the axial direction of the circular microchannel were generated, which could guide the circumferential alignment of HASMCs successfully during cultivation. The analysis of orientation angle, shape index, and contractile protein marker expression indicates that the cultured HASMCs revealed the in vivo-like cell phenotype. Finally, we produced circular microchannels by bonding two half-circular microchannels, and cultured the HASMCs circumferentially with high alignment and viability for 5 days. These results are the first demonstration for constructing an in vivo-like 3D smooth muscle cell layer in the circular microfluidic channel which can provide novel bioassay platforms for in-depth study of HASMC biology and vascular function.

• 동력기계공학회지
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• 제18권4호
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• pp.29-35
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• 2014

Plate heat exchanger are being applied in the field of OTEC (ocean thermal energy conversion) and SWAC (seawater air conditioning) system. This study is to analyze numerically the heat transfer and pressure drop characteristics by using solid works flow simulation in order to offer optimum design data of plate heat exchanger. Plater heat exchanger proposed in this study is four types. The geometric design parameters of plate heat exchanger are a channel space, a flow orientation, a plate array, the flowrate of working fluid and so on. The main results for numerical analysis of plate heat exchangers are summarized as follows. Heat transfer performance for the channel space of 2.4 mm shows the highest value compared to other spaces. And, the Type 4 plate heat exchanger in Table 2 is the highest performance. From the pressure drop characteristics of plate heat exchanger, the channel space of 3.2 mm shows the lowest value. And Type 1 plate heat exchanger in Table 2 is the lowest pressure drop.

• 대한금속재료학회지
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• 제50권12호
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• pp.931-937
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• 2012

The microstructure of Cu-15 wt%Ag composites fabricated by equal channel angular pressing (ECAP) with intermediate heat treatment at $320^{\circ}C$ was investigated by transmission electron microscopy (TEM) observations. Ag precipitates with a thickness of 20-40 nm were observed in the eutectic region of the Cu-15 wt%Ag composite solution treated at $700^{\circ}C$ before ECAP. The Cu matrix and Ag precipitates had a cube on cube orientation relationship. ECAPed composites exhibited ultrafine-grained microstructures with the shape and distribution dependent on the processing routes. For route A in which the sample was pressed without rotation between each pass, the Cu and Ag grains were elongated along the shear direction and many micro-twins were observed in elongated Cu grains as well as in Ag filaments. The steps were observed on coherent twin boundaries in Cu grains. For route Bc in which the sample was rotated by 90 degrees after each pass, a subgrain structure with misorientation of 2-4 degree by fragmentation of the large Cu grains were observed. For route C in which the sample was rotated by 180 degrees after each pass, the microstructure was similar to that of the route A sample. However, the thickness of the elongated grains along the shear direction was wider than that of the route A sample and the twin density was lower than the route A sample. It was found that more microtwins were formed in ECAPed Cu-15 wt%Ag than in the drawn sample. Grain boundaries were observed in relatively thick and long Ag filaments in Cu-15 wt%Ag ECAPed by route C, indicating the multi-crystalline nature of Ag filaments.

• 경영과정보연구
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• 제30권4호
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• pp.195-227
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• 2011

본 연구는 '과연 소비자의 중독구매성향은 일반적인 소비에서 예상되는 구매 이후 감정 및 행동패턴에 또다른 영향으로 작용할 것인가' 라는 질문에 관심을 가지고 접근하고자 한다. 구체적인 연구의 목적은 첫째, 우리나라 패션제품 소비자의 쇼핑 중독구매성향에 영향을 미치는 심리적 요인을 살펴보고, 둘째, 중독구매성향이 패션제품 구매 후 감정(긍정적 감정/부정적 감정)에 미치는 영향을 살펴보며, 셋째, 구매후 감정이 구매 후 행동(재구매/반품 및 교환/부정적 구전)에 미치는 영향을 살펴보고, 넷째, 중독구매성향에 영향을 미치는 심리적 요인과 중독구매 성향이 구매 후 감정 및 행동에 미치는 영향은 유통채널(온라인/오프라인) 별로 차이가 있는 지를 살펴보고자 하였다. 연구결과, 개인의 심리적 요인 중 자아 존중감이 낮고, 보상구매성향과 충동성이 높은 사람일수록 중독구매성향이 높아지는 것으로 나타났다. 중독구매성향은 구매후의 양면적(긍정적, 부정적) 감정에 모두 영향을 미치고, 특히 오프라인의 경우 긍정적 감정을 수반하는 것이 밝혀졌다. 구매 후 감정은 일반적인 소비상황과 같이 구매 후 행동에 영향을 미치고 있으나, 부정적 감정의 영향이 긍정적 감정의 영향보다 크고, 또한 긍정적, 부정적 행동에 모두 명확한 영향을 미치는 것을 밝혔다는 점을 찾을 수 있었다. 본 연구는 사회적으로 문제가 되고 있는 중독구매성향에 초점을 맞추고, 중독구매성향이 구매 후 감정 및 행동에 미치는 영향을 최초로 연구하였다는 점에 의의가 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.741-744
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• 2000

In general there occur warpage in one way long part. Warpage is caused by differential shrinkage-Orientation Effect, Volumetric Shrinkage Effect, Differential Cooling Effect -over the part. Deco-Top is located at the top of 29"TV set and it's shape is one way long$(626{\times}130mm)$. Material is used transparency ABS resin. So we can't design ribs in this part. And we use film gate to avoid weld line. In these reasons we must develop no ribs and no warpage product. In this study we use MOLDFLOW's software-MF/FLOW, MF/COOL, MF/WARP. Using MF/FLOW, set the flow balance and gate positioning. And we can set cooling channel layout and the optimum processing condition through MF/COOL and MF/WARP. In result we reduced trials and obtained good product.