• Journal of the Microelectronics and Packaging Society
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• v.8 no.4
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• pp.35-41
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• 2001

In this paper, several methods to predict the solder joint shape are studied. Although there are various methods to predict the solder joint shape, such as truncated sphere method. force-balanced analytical solution, and energy-based methods like surface evolver developed by Ken Brakke, we calculate solder joint shape of $\mu$BGA by two solder joint shape prediction methods(truncated sphere method and surfaceevolver) and then compare results of each method. The results indicate that two methods can accurately predict the solder Joint shape in an accurate range. After that, we calculate reliability solder joint shape under thermal cycle test by FEA program ANSYS(version 5.62). As a result, it could be found that optimal solder joint shape calculated by solder joint prediction method has best reliability in thermal cycle test.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.259-268
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• 1988

Clay deposits in the vicinity of the Gwangpo Bay, southern coast of Korea, occur restrictively in anorthositic masses. Laumontite and meta-halloysite are the predominant clay minerals with iron oxides at the uppermost surface. Chlorite and halloysite occur in deeper zone. Beneath the main clay horizon, but not above, some anorthositic rocks are pervasively altered to quartz, sericite, chlorite, pyrite and montmorillonite along the hydrothermal channels. The hypotheses of hydrothermal and weathering origins of the clay minerals are tested by multi-component equilibrium calculations of the reactions of modified hydrothermal water and rain water with anorthositic rocks at $100^{\circ}C\;and\;25^{\circ}C$, respectively. The calculated mineralogy from the reaction with rain water resembles natural mineral assemblage except for abundance in laumontite. The result implies that the weathering process is the main machanism of the formation of clay deposits in the area.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.42.2-42.2
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• 2018

신도시 및 대규모 도시 개발이 진행됨에 따라 안정적이고 효율적인 전력 공급을 위해 다수의 지상 배전함이 설치되고 있으며, 이에 따라 불법 광고물 및 스티커의 부착으로 인한 문제가 발생하고 있다. 이를 해결하기 위하여 여러 기관 및 산업체에서는 부착 방지용 코팅 도료 및 시트에 대하여 다양한 연구개발을 진행하고 있으며, 현장에 적용 된 다수의 제품이 존재한다. 하지만 현재 대부분의 제품들은 약 1년 정도의 시간이 지나면 부착 방지 기능을 상실하며, 도료와 기판 또는 시트와 기판 사이의 박리가 일어나 도시의 미관을 더욱 해치는 결과를 초래하고 있다. 이러한 원인으로는 부착력(Peel resistance, N/cm)을 측정하는 기존의 제시된 방법(KS T 1028, Peel test)으로는 정확한 측정이 어렵기 때문에 제품 선별에 어려움이 있다. 일반 기판의 경우 규격에서 요구하는 각도($90^{\circ}$, $180^{\circ}$)가 잘 유지되어 정밀한 부착력 측정이 가능하지만, 저점착 기능성 코팅소재(Anti-adhesion coating)의 경우 부착 자체가 어렵기 때문에 요구 각도를 유지하기 어려워 정밀한 측정을 할 수 없다. 이러한 문제점들을 해결하고자 압입자(Probe)를 이용한 새로운 평가 장치와 방법(Tack test)을 개발 및 제시하였다. 평가 지표로는 최대 점착력(Adhesive force, N), 최대 점착력일 때 점착제가 늘어난 총 길이(Extension of adhesive, mm), 탈착 에너지(Energy, J)가 있으며, 인가하는 힘(N)이 커질수록, 탈착 속도(Velocity)가 빨라질수록 평가 지표 모두 값이 상승하는 경향성을 보인다. 각 시험방법(Peel test, Tack test)에 대한 테이프류 점착제와 기판과의 결합이 끊어지는(Debonding, 탈착) 메커니즘(Mechanism)은 점착제 기공(Cavity)의 형성, 결합이 끊어지는 힘(Debonding force, N), 힘의 평형(Force balance)로 설명 가능하며, 상호간의 관계성을 도출한다. 이와 같은 평가 지표를 활용하여 저점착 기능성 코팅소재에 대해 정밀한 평가를 하는 것으로, 향후 개발될 다양한 제품에 대한 성능 분별력을 높이고, 현장에 적용 될 제품들의 성능을 끌어 올려 기존에 발생한 다양한 문제점들을 해결 할 수 있다.

• Journal of the Korean Chemical Society
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• v.61 no.6
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• pp.339-345
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• 2017

Carbonaceous adsorbent (CA-WTP) was prepared by heat treatment at $400^{\circ}C$ for 2 h in N2 atmosphere using waste tire powder (WTP). WTP and CA-WTP were first characterized by thermo-gravimetric analysis (TGA), energy dispersive X-ray spectrometer (EDS), scanning electron microscopy (SEM), specific surface area analysis (BET) and FT-IR spectroscopy. Then, they were tested as adsorbents for removal of Cd in water. CA-WTP exhibited much higher specific surface area and total pore volume than WTP itself and showed higher adsorption capacity for Cd. Equilibrium data of adsorption were analyzed using Freundlich and Langmuir isotherm models. It was seen that both Freundlich and Langmuir isotherms have correlation coefficient $R^2$ value larger than 0.95. The results of studies indicate that CA-WTP developed from WTP by heat treatment could be used as efficient adsorbent for the removal Cd from water.

• Journal of Animal Science and Technology
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• v.45 no.1
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• pp.113-122
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• 2003

Net and metabolizable energy requirements for maintenance of Hanwoo (Korean native cattle) bulls were estimated in twenty-eight fasting metabolism trials using seven different feeds at four stages of body weight(100, 200, 300 and 400kg). Three cattle for each of twenty-eight trials fed at a level of maintenance energy requirement were housed in metabolic stalls during the 5 days of collection period. Thereafter, during the 2 days of respiration period the heat production was measured by indirect calorimetry using respiratory chamber. After finishing the respiratory metabolism trials under the maintenance level, experimental animals were fasted for 5 days and were measured heat production by indirect calorimetry using respiratory chamber. Seven different feeds were: 1) mixed ration of concentrate and rice straw, 2) mixed ration of concentrate and mixed grass hay, 3) mixed ration of concentrate and corn silage, 4) rice straw alone, 5) mixed grass hay alone, 6) corn silage alone, 7) concentrate alone. Fasting heat production were 66.05/$W^{0.75}$ at 100kg of body weight and 60~63kcal/$W^{0.75}$ at 200~400kg of body weight. When subtracting heat loss by muscular work from the fasting heat production, basal metabolic rate was 55.92kcal/$W^{0.75}$. The average values of NEm requirements were obtained by adding urinary energy excretion to the basal metabolic rates were 69.1, 62.1, 65.8 and 64.4kcal/$W^{0.75}$ for the four stages of body weight, respectively. The ME requirement for maintenance could be calculated using retained energy and the efficiency of utilization of ME for net energy. The ME requirement for maintenance thus obtained was 102.69kcal/$W^{0.75}$.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.395-405
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• 1994

The various functional groups, such as hydroxyl(-OH), carboxyl(-COOH) and quinonic oxygen(OC<) on the carbon black(abbreviated to CB) surface were activated with n-butyl lithium solution in n-hexane and then acrylate and methacrylate monomers were graft polymerized onto these activated anionic sites and CB-grafted polymers were obtained. To separate homopolymers from reaction mixture, non-solvent precipitation method or centrifugal separating method were applied. Subsequently, conversion, grafting ratio and efficiency were determined at various reaction temperatures and times. In case of acrylates, the grafting ratio showed 20~30% but methacrylates showed 150~200%. Also the anion polymerizations between CB and monomers were nearly reached to equilibrium state within one or two hours under each reaction temperatures but conversion and grafting ratio were increased a little with reaction temperature increase. In colloidal dispersion stability test, before heat-drying, the all CB-grafted polymers showed good dispersed stability in good solvents for acrylic and methacrylic homopolymers. Futhermore, CB-polymethacrylates were found to show excellent collidal properties for good solvents of methacrylic homopolymer even after heat-drying. Identification of the grafted polyacrylates and polymethacrylates onto the CB surface was performed by FT-IR spectroscopy. In addition, electric resistance values of CB-grafted polymers were measured by Four-probe method, and the increase of the grafting ratio showed the increase of the surface resistance.

• Applied Biological Chemistry
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• v.47 no.3
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• pp.344-350
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• 2004

This study was conducted to develop and assess the applicability of mixed-bed ion exchange resin capsules for water quality monitoring in small agricultural watershed. Recoveries of resin capsules for inorganic N and P ranged from 96 to 102%. The net activation energies and pseudo-thermodynamic parameters, such as ${\Delta}G^{o\ddag},\;{\Delta}H^{o\ddag},\;and\;{\Delta}S^{o\ddag}$ for ion adsorption by resin capsules, exhibited relatively low values, indicating the process might be governed by chemical reactions such as diffusion. However, those values increased with temperature coinciding with the theory. The reaction reached pseudo-equilibrium within 24 hours for $NH_4-N\;and\;NO_3-N$, and only 8 hours for $PO_4-P$, respectively. The selectivity of resin capsules were in the order of $NO_3\;^-\;>\;NH_4\;^+\;>\;PO_4\;^{3-}$, coinciding with that of encapsulated Amberlite IRN-150 resin. At the initial state of equilibrium, the resin adsorption quantity was linearly proportional to the mass of ions in the streams, but the rate of movement leveled off, following Langmuir-type sorption isotherm. The overall results demonstrated that the resin capsule system was suitable for water quality monitoring in small agricultural watershed, judging from the reaction mechanism(s) of the resin capsule and the significance of model in field calibration.