• 한국전기전자재료학회논문지
• /
• 제24권3호
• /
• pp.234-239
• /
• 2011

In this study, the heat transfer capability have been improved by using via-holes in FR4 PCB, when the LED lighting is designed to solve the thermal problem. The thermal resistance and junction temperature were measured by changing the dimension of FR4 PCB and size of via hole. As a result, when the dimension was increased initially, the thermal resistance and junction temperature was decreased rapidly, the ones was stabilized after the dimension of 200 $[mm^2]$. Also, the light output was improved up to maximum 17% by formation of via-hole and expansion of dimension in FR4 PCB. Therefore, the thermal resistance and junction temperature could be improved by expansion of PCB dimension and configuration of via-hole ability.

• 한국전기전자재료학회논문지
• /
• 제27권10호
• /
• pp.673-677
• /
• 2014

In this paper, thermal analysis of HDU (Heat Dissipation Unit) for infrared CCTV is performed by using SolidWorks Simulation (Thermal analysis) package, in order to change the part materials and HDU shape is optimized. Furthermore, HDU disperses the aggregated heat around the LED inside the housing. The junction temperature of infrared LED checked by HDU check was $65.83^{\circ}C$, $42.02^{\circ}C$, respectively. In addition, the Thermoelement by changing the shape of the HDU was possibly designed and equipped with. Comparison with simulation and prototype measurement results, without HDU model was $65.83^{\circ}C$, $61.99^{\circ}C$, respectively. In addition to with HDU model was $42.02^{\circ}C$, $39.01^{\circ}C$, respectively. Only HDU mounted into infrared CCTV is usable in the ordinary house or outdoors. Also HDU with thermal element, fan mounted into infrared CCTV is usable in a blast furnace workplace or high temperature workplace.

• Structural Engineering and Mechanics
• /
• 제82권3호
• /
• pp.401-416
• /
• 2022

The aim of this study is to examine the frictionless double receding contact problem for two functionally graded (FG) layers pressed with a uniformly distributed load and resting on a homogeneous half plane (HP) using analytical and numerical methods. The FG layers are made of a non-homogeneous material with an isotropic stress-strain law with exponentially varying properties. It is assumed that the contact at the FG layers and FG layer-HP interface is frictionless. The body force of the FG layers and homogeneous HP are ignored in the study. Firstly, an analytical solution for the contact problem has been realized using the theory of elasticity and the Fourier integral transform techniques. Then, the problem modeled and two-dimensional analysis was carried out by using the ANSYS package program based on FEM. Numerical results for contact lengths and contact pressures between FG layers and FG layer-HP were provided for various dimensionless quantities including material inhomogeneity, distributed load width, the shear module ratio, and the heights of the FG layers for both methods. The results obtained using FEM were compared with the results found using the analytical formulation. It was found that the results obtained from analytical formulation were in perfect agreement with the FEM study.

• 마이크로전자및패키징학회지
• /
• 제20권4호
• /
• pp.47-52
• /
• 2013

Gold wire has long been used as a proven method of connecting a silicon die to a substrate in wide variety of package types, delivering high yield and productivity. However, with the high price of gold, the semiconductor packaging industry has been implementing an alternate wire material. These materials may include silver (Ag) or copper (Cu) alloys as an alternative to save material cost and maintain electrical performance. This paper will analyze and compare the electrical characteristics of several wire types. For the study, typical 0.6 mil, 0.8 mil and 1.0 mil diameter wires were selected from various alloy types (2N gold, Palladium (Pd) coated/doped copper, 88% and 96% silver) as well as respective pure metallic wires for comparison. Each wire model was validated by comparing it to electromagnetic simulation results and measurement data. Measurements from the implemented test boards were done using a vector network analyzer (VNA) and probe station setup. The test board layout consisted of three parts: 1. Analysis of the diameter, length and material characteristic of each wire; 2. Comparison between a microstrip line and the wire to microstrip line transition; and 3. Analysis of the wire's cross-talk. These areas will be discussed in detail along with all the extracted results from each type the wire.

• 융합신호처리학회논문지
• /
• 제10권2호
• /
• pp.120-126
• /
• 2009

반도체 외관결함에는 발생 요인이 각각 다른 crack, foreign material, chip-out, chip, void 등이 있으며, 검사 시스템에서는 결함 유무 및 결함 분류를 수행하여 효과적인 공정관리가 가능하여야 한다. 본 논문에서는 QFN 패키지 결함의 분류를 위한 알고리즘 및 광학시스템을 제안한다. 제안한 방법에서 분류가 어려운 결함 중 하나인 foreign material 과 chip의 효과적인 분류를 위해 제안한 결함의 위치, 밝기의 특징정보(feature)를 사용한 ML(Maximum Likelihood ratio) 분류방법 및 특징정보 획득에 효과적인 광학계를 제안하였다. 실험 결과에서 분류가 어려운 foreign material과 chip에 대한 신뢰성 높은 분류성능을 보였다.

• 한국건설관리학회논문집
• /
• 제2권2호
• /
• pp.47-58
• /
• 2001

고층건물공사 현장물류계획은 수직이동계획과 수평이동계획으로 구분할 수 있다. 수평이동계획의 내용은 상대적으로 선행 프로세스인 수직이동계획 과정에서 결정되는 양중장비계획 등에 의해서 제약을 받는다. 현재 국내 건설업체들은 마감자재에 대한 이동계획과 관련해서 약산식을 사용한 가설 리프트 대수 산정, 마감자재별 물량을 양중회수로 치환하는 방법의 부재, 유사현장 사례 비교 방법의 문제점, 양중장비계획의 적정성 검토 방법의 부재, 형식적인 수평이동계획, 수직$\cdot$수평이동계획의 단절 등의 문제점을 가지고 있다. 그리고 이러한 문제점들로 인하여 수직$\cdot$수평이동계획자는 양중장비의 대수, 사용기간, 마감자재의 야적 등에 대해서 합리 적으로 의사결정을 내리지 못하고 있다. 본 연구에서는 계획자로 하여금 고층건물공사 마감자재의 수직$\cdot$수평이동계획을 통합하여 합리적으로 계획할 수 있는 의사 결정모델을 제안하고 있으며, 이 모델을 현업의 수직$\cdot$수평이동계획 과정과 비교하고 있다. 그리고 이 모델을 사용하는 계획자는 자신의 사고의 틀을 결과지향적 사고에서 과정지향적 사고로 변화시키는데 활용할 수 있고, 계획 시 직면하게 되는 한정된 자원 및 동태적 상황 등에 적절하게 대응할 수 있으며, 고층건물공사 마감자재의 수직$\cdot$수평이동계획에 대한 시스템 사고 등이 가능하다.

• Preventive Nutrition and Food Science
• /
• 제14권4호
• /
• pp.349-353
• /
• 2009

The effects of packaging materials on preserving the functional component of pine bud beverage stored under UV (ultraviolet) light exposure conditions were studied. The order of UV light blocking properties of the selected packages was: opaque can> opaque PET (polyethylene terepthalate) with green lamination=transparent PET with 10% PEN (polyethylene naphthalate) blending> transparent PET, and did not depend on film thickness in specified range. At 20${^{\circ}C}$, the order of preserving degree of original color and endobornyl acetate, which is quality index of pine bud beverage, was the same as above. Exposure to UV light can cause of deterioration of functional food components, but green color lamination and blending of PEN materials with transparent PET help to preserve the UV sensitive pine bud beverage components. However, the treated PET bottles have poorer preservation capabilities than the opaque cans. Transparent PET with PEN blending, in particular, will be very useful packaging material for colorful functional beverage preservation by helping to protect the ingredients while attracting consumer attention.

• 한국의류산업학회지
• /
• 제9권6호
• /
• pp.637-644
• /
• 2007

The purposes of this study were to classify adolescents by their lifestyles and to investigate the differences in clothing purchase behavior among lifestyle groups. The data were obtained from questionnaire completed 341 adolescents in Daegu area. The SPSS package was used for data analysis which included frequency, factor analysis, cluster analysis, ${\chi}^2$ test, ANOVA, and Scheffe test. Lifestyles of adolescents were categorized into five factors such as clothing hedonic shopping orientation, positive activity, material orientation, frugality, digital orientation. Three clusters (achievement orientation group, ordinary group, economic orientation group) were developed by five factors of lifestyles. While the achievement orientation group had the highest purchase motives and used the most information sources, the economic orientation group had the lowest purchasing motives and used the least information sources. There were significant differences in clothing purchase frequency and average clothing expenditure among three clusters.

• 복합신소재구조학회 논문집
• /
• 제6권1호
• /
• pp.45-50
• /
• 2015

This study performed a finite element crash analysis of support structures made of various composite materials for road facilities. The effects of different material properties of composites for various parameters are studied using the finite element commercial package for this study. In this study, the existing finite element analysis of composite post structures using the LS-DYNA program is further extended to compare dynamic behaviors against car crash of the structures made of various composite materials. The several numerical examples show the comparison of the nonlinear dynamic effects for different materials.

• Journal of Welding and Joining
• /
• 제35권1호
• /
• pp.49-54
• /
• 2017

In this study, the volumetric heat source in electron beam welding (EBW) is modeled through finite element method taking advantage of ABAQUS software package. Since this welding method is being applied in plates with different thicknesses and also considering that residual stresses reduce the strength of these weldments, the effect of thickness in the distribution and magnitude of residual stresses after welding is studied. Regarding the vast application of Inconel 706 super-alloy in aerospace industries, this material was selected in the current research. In order to validate the finite element model, the obtained results were compared to those of other researchers in this area, and good agreement was observed. The simulation results revealed that increase in the plate thickness leads to increase in the residual stresses. In addition heat treatment in the base metal (before welding) increases the residual stresses significantly.