• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2113_2114
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• 2009

Chalcopyrite based sollar cells have received much attention because of their tunable electronic and optical properties. As a typical ternary chalcopyrite material, $CuInS_2$ has been considered as one of the most popular and promising candidates as absorber materials for photovoltaic applications because of its high absorption coefficient and environmental consideration. In this study, $CuInS_2$ powders have been synthesized using polyol process of a mixture of copper nitrate, indium nitrate, and thiourea with various stoichiometric molar ratios in ethylene glycol at $196^{\circ}C$. As boiling time goes by, the color of metal ion mixed solutions were changed transparent green to dark green and finally turned to black by reduction of OH- radicals. The prepared powders were fully characterized using SEM, XRD. The particle shape of black colored powders showed sphere with about 50 nm in particle size compared to those with dark green colored powders showed irregular shape with about $1{\mu}m$ in particle size. The XRD results showed highly crystallized $CuInS_2$.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.199-205
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• 2016

A thin sheet of metal with corrugated structures has been utilized in various devices: heat exchangers, separators in fuel cells, and many others. However, it is not easy to fabricate thin corrugated structures using a single-step stamping process due to their geometrical complexity. To solve this problem, firstly, a plate type heat exchanger was redesigned to attain the optimal value of aspect ratio and the optimal shape of corrugated structures for the actual loading conditions. A forming analysis of the corrugated plate was then carried out to determine the process parameters. From this work, the optimal value of aspect ratio was found to be 4.6. In addition, the process parameters of heat exchanger forming were optimized using the optimal value of aspect ratio, and the analytical results were evaluated through experiments. The results obtained indicated good agreements between them.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.263-266
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• 1998

Several constraints in machine duplication cost, machining capability, cell space capacity, intercell moves and exceptional elements(EEs) are main problems that prevent achieving the goal of ideal Cellular Manufacturin System (CMS) environment. Minimizing intercell part traffics and EEs are the main objective of the cell formation problem as it's a critical point that improving production efficiency. Because the intercell moves could be changed according to the sequence of operation, it should be considered in assigning parts and machines to machine cells. This paper presents a method that eliminates EEs under the constraints of machine duplication cost and cell space capacity attaining two goals of minimizing machine duplications and minimizing intercell moves simultaneously. Developing an algorithm that calculates the machine duplications by cell-machine incidence matrix and part-machine incidence matrix, and calculates the exact intercell moves considering the sequence of operation. Based on the number of machine duplications and exact intercell moves, the goal programming model which satisfying minimum machine duplications and minimum intercell moves is developed. A linear programming model is suggested that could calculates more effectively without damaging optimal solution. A numerical example is provided to illustrate these methods.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1319-1321
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• 2001

The purpose of this study is to manufacture and test a thermoelectric generator which converts unused energy from close-at-hand sources, such as garbage incineration heat and industrial exhaust, to electricity. A manufacturing process and the properties of a thermoelectric generator are discussed before simulation the thermal stress and thermal properties of a thermoelectric module located between an aluminum tube and alumina plate. We can design the thermoelectric modules having the good properties of thermoelectric generation. Resistivity of thermoelectric module for thermoelectric generation consisting of 62 cells was $0.15{\sim}0.4{\Omega}$. The maximum power of thermoelectric generator using thermoelectric generation modules can be defined as temperature function, and in this case. It can be analogized the lineal relation between current and voltage characteristics as function of temperature. The thermoelectric generator using 32 thermoelectric modules was assembled with 32 directly connected modules that they constrained for two kinds of heat transfer tube with key joints.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.2
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• pp.139-144
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• 2006

A fabrication condition of the cathode electrode was optimized in a lithium secondary battery. The $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ powders were used as a cathode material. The $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$/Li cells were prepared with a certain formulation and their cycleability and rate-capability were evaluated. Optimum electrode composition simulated from the evaluated value was 86.3: 5.6: 8.1 in mass $\%$ of active material: binder: conducting material. Discharge capacity decreased markedly as the press ratio exceeded $30\%$ during preparation of the electrode. Discharge performance at a high current rate deteriorated abruptly as the electrode thickness was over $120{\mu}m$.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.258-267
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• 2003

Recently inside nano liposome particles or nano-emulsions which contain tough-melting physiology activity materials or the coefficient of low organism utilization promote the coefficient of organism utilization, so this part has been studied a lot because they can absorb selectly cosmetics, specially physiology activity materials, into the skin. Also, in particle size, cells interstitial lipid interval are 30~50nm, so nano-emulsions that the size is similar to 30~50 nm are made to study for absorbing quickly into the skin. And transparent skin which contains oils in common skin lotion dosage form has become the center of public interest. The used nano-emulsions in this study were unsaturated lecithin/co-surfactant! ethanol/ oil / water. And polysorbate 20/ polysorbate 80/ Dicetyl phosphate/hydrogenated .caster oil/ isoceteth-20/SLS were used in co-surfactant. The used oils were cyclomethicone and caprylic/capric triglyceride. The manufacturing process was that microfluidizer was fixed in 1000bar and transit times were changed from 1 to 10 times. From transparency and particle size, the transparency sequence was SLS> polysorbate 20= polysorbate 80> isoceteth-20> dicetyl phosphate >hydrogenated caster oil and the particle size was small. Specially cyclomethicone nano-emulsions, when we made unsaturated lecithin /SLS /ethanol/water/cyclomethicone, cyclomethicone 5％ was good for transparency. And 20％ of this was used for making transparent skin toner in common skin dosage form.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.30-32
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• 2009

In this study, $CuInS_2$ powders have been synthesized using polyol process of a mixture of copper nitrate, indium nitrate, and thiourea with various stoichiometric molar ratios in ethylene glycol at 196$^{\circ}C$. As boiling time goes by, the color of metal ion mixed solutions were changed transparent green to dark green and finally fumed to black by reduction of $OH^-$ radicals. The prepared powders were fully characterized by SEM, XRD and UV-Vis. The particle shape of black colored powders showed sphere with about 30 nm in particle size compared to those with dark green colored powders showed irregular shape with about 1 ${\mu}m$ in particle size. The XRD results showed highly crystallized $CuInS_2$. The UV-Vis spectra showed broad shoulder at 430 and 780 nm corresponding to 2.78 and 1.58 eV for the dark green colored one and black colored one, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.589-594
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• 1991

Group Technology (GT) is a technique for identifying and bringing together related or similar components in a production process in order to take advantage of their similarities by making use of, for example, the inherent economies of flow production methods. The process of identification, from large variety and total of components, of the part families requiring similar manufacturing operations and forming the associated groups of machines is referred as 'machine-component grouping'. First part of this paper is devoted to describing a hierarchical divisive algorithm based on graph theory to find the natural part families. The objective is to form components into part families such that the degree of inter-relations is high among components within the same part family and low between components of different part families. Second part of this paper focuses on establishing cell design procedures. The aim is to create cells in which the most expensive and important machines-called key machine - have a reasonably high utilization and the machines should be allocated to minimize the intercell movement of machine loads. To fulfil the above objectives, 0-1 integer programming model is developed and the solution procedures are found. Next an attempt is made to test the feasibility of the proposed method. Several different problems appearing in the literature are chosen and the results air briefly showed.

• The Korean Journal of Food And Nutrition
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• v.21 no.3
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• pp.288-292
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• 2008

To save cost and time in Kimchi manufacture, the use of raw red-pepper paste and device-mashed vice materials, in place of dried red-pepper powder, was examined. Two kinds of Kimchi were prepared: One with dried red pepper powder and device-not mashed vice materials and the other with raw red pepper paste and device-mashed vice materials. Then pH, total acidity, total viable cell counts, total lactic acid bacteria and sensory characteristics were evaluated. Comparisons of the two Kimchis, indicated that changes in pH, total acidity, the total number of viable cells and total lactic acid bacteria were similar between the two groups. The acceptability score of the Kimchi made using the raw red pepper paste and device-mashed vice materials was slightly lower than that of Kimchi made using the dried red-pepper powder. This color was indistinctly changed since the vice materials were mashed and mixed. In conclusion, the results indicate that when manufacturing Kimchi using device-mashed vice materials, Kimchi of better quality can be made by adding dried red-pepper powder.

• Journal of Korean Society on Water Environment
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• v.30 no.6
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• pp.683-690
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• 2014

Nanomaterials are used in a range of fields, including industry, medicine, aerospace, and manufacturing, due to their unique and useful properties. In recent years, nanotechnology has developed rapidly, and the amount of nanomaterials used in various fields has increased consistently. As a result, nanomaterials are released into the aquatic and soil ecosystem, posing potential risks to organisms and environment. These materials can enter the cells and may cause serious damage to organisms. Furthermore, they can be transferred through trophic levels and food web, thereby leading to bioconcentration and biomagnification. In this study, we analyzed the trends in research on food chain transfer of nanomaterials and investigated the techniques used in the research. Although many studies have been underway, there is a need for further advanced studies on higher trophic levels and complex microcosm and mesocosm. Furthermore, study topics should be expanded to include various types of nanomaterials and varied species and trophic levels.