• 한국안전학회지
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• 제20권1호
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• pp.75-80
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• 2005

In this paper, when CF/EPOXY laminates for high efficiency space structure are subjected to FOD(Foreign Object Damage), the effects of temperature change on the impact damages(inter laminar separation and transverse crack) of CF/EPOXY laminates and the relationship between residual life and impact damages ale experimentally investigated. Composite laminates used in this experiment are CF/EPOXY orthotropic laminated plates, which have two-interfaces $[0^{\circ}_6/90^{\circ}_6]S$ and four-interfaces $[0^{\circ}_3/90^{\circ}_6/0^{\circ}_3]S$. CF/EPOXY specimens with impact damages caused by a steel ball launched from the air gun were observed by the scanning acoustic microscope under room and high temperatures. In this experimental results, various relations were experimentally observed including the delamination area vs. temperature change, the bending strength vs. impact energy and the residual bending strength vs. impact damage of CF/EPOXY laminates. And as the temperature of CF/PEEK laminates increases, the delaminaion areas of impact-induced damages decrease linearly. A linear relationship between the impact energy and the delamination areas were observed. As the temperature of CF/PEEK laminates increases, the delamination areas decrease because of higher initial delaminatin damage energy.

• 대한금속재료학회지
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• 제48권4호
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• pp.353-356
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• 2010

InSb thin films with a thickness of approximately 300 nm were prepared using single- and double-source vacuum evaporation methods and their structures and properties were investigated in terms of a heat treatment procedure. The double-source InSb films, prepared by the alternate stacking of In and Sb, were polycrystalline in structure and included small amounts of unreacted In and Sb phases. After annealing at elevated temperatures below the melting point of InSb (525$^{\circ}C$), the films changed into the InSb phase and were found to contain small amounts of unreacted In. The formation capability of the InSb compound was slightly lower for multilayer films than for single-layer films. The electrical and galvanomagnetic properties were found to be strongly related to the microstructures of the films. The maximum value of the Hall mobility and the magnetoresistance were determined to be $4.3{\times}10^3cm^2$/Vs and 70%, respectively, for the single-layer films, while these values for the alternately stacked films were respectively $2.9{\times}10^3cm^2$/Vs and 29% for the $[Sb(2.5)/In(2.5)]_{60}$ films, and $3.1{\times}10^3cm^2$/Vs and 10% for the $[Sb(150)/In(150)]_1$ films.

• Journal of Microbiology
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• 제34권1호
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• pp.40-48
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• 1996

We have examined the chromatin structure of the HMRE/HSP82 and HMRa/HSP82 allels using three complementary approaches : DNase I chromating footprinting, micrococcal nuclease (MNase) nucleosome-protected ladder assay, and an in vivo E. coli dam methylase accessibility assay. The footprinting results indicate that the promoter and silencer sequences are assembled into nucleoprotein complexes which exhibit no detectable change in structure, despite a 70-fold range in expression levels. In addition, the promoter region of the HMRa/HSP82 allele is cleaved randomly by MNase in all cases, indicating the absence of anonical nucleosomes over this region irrespective of SIR4 or heat-shock. Finally, no discernible difference in the accessibility of the HMRE/HSP82 locus to dam methylase in SIR4 vs. sir4 cells was seenm which again suggests that the chromatin structure of HMRE/HSP82 allele is identical regardless of SIR4. Altogether, our results indicate that in contrast to other observations of the silent mating-type loci, no discernible structural alteration is detected at either HMR/HSP82 allele regardless of SIR genetic background or transcriptional state of the gene.

• 전기화학회지
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• 제6권1호
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• pp.1-5
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• 2003

[ $LiNi_{1-x}Co_xO_2\;(x=0.0,\;0.3,\;05,\;0.7,\;1.0)$ ]을 구연산법을 이용하여 합성하고, Co 치환량에 따른 결정구조와 리튬 이차전지 양극특성을 조사하였다 X-선 회절분석 결과로부터 Co치환량에 무관하게 모든 조성에서 단일상의 고용체를 형성함을 알 수 있었다. 또한 Rietveld 구조정산을 통하여 고용체의 결정구조가 Co 치환량에 따라 크게 변화함을 확인하였다. 즉, Co치환량이 적은 경우는 (x=0-0.5)는 격자상수의 비가 작은(c/a<4.98) 입방구조에 가까웠으며, Co치환량이 큰 경우(x^gt;0.7)는 격자상수의 비가 큰$(c/a\geq4.98)$ 층상구조를 보였다. 이와 같은 차이는 electrochemical voltage spectroscopy를 통하여 확인할 수 있었는데, 고용체를 형성하고 있는 Co성분은 Co치환량이 적을 경우는 $3.7V\;(vs.\;Li/Li^+)$, 그리고 치환량이 클 경우는 $3.92V\;(vs.\;Li/Li^+)$에서 충전되는 현상을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.125-127
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• 2003

The single phase switched reluctance motor(SRM) is more simpler and robust in the structure than poly phase SRM. It has the merits that it reduces the switching elements and the energy density per volume is very high. Recently, it has been researched and developed in various types and starting method due to the technique of power electronics and the computer added design. The single phase SRM is tried to apply to many industrial appliance field to substitutethe the induction motor by the single phase SRM. On the previous studies, we decided the design parameters of the single phase SRM for the blower driver to adapt the design method of the conventional machine and the poly phase SRM. In this studies, it is proposed the conditions to decide the optimal pole arcs because the stator and rotor pole arcs is very important in the characteristics of the single phase SRM. For this reason, it is analysed the characteristics of current on/off angle vs. pole arc, pole arcs vs. average torque.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.115-115
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• 2003

Silica nanostructures have been attached considerable attention because of theirs potential application in mesoscopic research and the potential use of large surface area structure of catalysts. SiO2 nannowire and nanorods was synthesized various methods including thermal evaporation, chemical vapor deposition (CVD), and laser ablation methods. In this experiments, SiO2 nanowire were grown using thermal evaporation method followed by VS (Vapor-Solid) growth mechanisms. Grown SiO2 nanowires were amorphous phases because of its low growth temperatures. Grown nanowires diameters were about 20-40nm at all growth conditions, but its microstructres were different by that used substrate because of it's oxygen contents.

• The Korean Journal of Ceramics
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• 제4권2호
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• pp.136-140
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• 1998

This work demonstrates a method for modeling of electrical conductivity in high-temperature proton-conducting oxides. Total conductivity was calculated assuming that it comprises partial conductivities contributed by protons, oxygen ions and electron holes. From the polt $\sigma_{tot}$ vs. $po_2\;{1/4}$ in wet atmosphere, thermodynamic and kinetic parameters were obtained representing transport properties such as concentration and mobility of the charge-carrying defects. The formulas for the calculation of partial conduction were derived based on the defect structure of HTPCs. Illustrative calculation were made for $SrCe_{0.95}Yb_{0.05}O_{2.975}$ system.

• 경영과학
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• 제26권1호
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• pp.21-35
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• 2009

There is a controversy on Internet pricing, flat-rate vs. usage-based. This study gives a comparative analysis between flat-rate and two-part tariff which is realistic alternative of usage-based pricing. In a basic economic model, two-part tariff based on ISP's cost structure satisfies allocative efficiency and relatively expand the number of subscribers. But the characteristics of Internet service like consumers' uncertainty on cost, measurement cost of traffic and network externality induce increase of cost or decrease of marginal utility. The analysis shows that small impact of these can make flat-rate more efficient.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.149-154
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• 2007

The zinc prosphate film treatments used to lubricating treatment of mostly cold forging processes. But there are several problems happened to lubricating treatment process such as happening harmful environment on person, complex lubrication processing occurring in energy and time consumption, eco-destructive and chemical by-product generation, the needs of waste disposal etc. As a result, a water-soluble lubricant was developed to replace the perfect or some of the zinc prosphate film in the world. In order to solve these problems, this study evaluated the performance of the typical water-soluble. In this study, for these requirement inquiry of two part. First, about possibility of replace zinc phosphate lubricant, quantitatively evaluation developed of water-soluble lubricant for cold forging vs zinc phosphate lubricant. Second, About optimization of coating Process use to equipment with practicable automatic coating Process. The performance evaluation of these lubricants was conducted using the double cup extrusion test and spike forging test. With the use of the commercial FE code DEFORM, friction factor calibration curves, i.e. cup height ratio vs. punch stroke and spike height vs. punch stroke, were established for different friction factor values. By matching the cup height ratio and the punch stroke and spike height vs. punch stroke from experiment to that obtained from FE simulations, the friction factor of the lubricants was determined. Survey of comparative analysis use to SEM that sprayed lubricant surface structure of grain shape and characteristic of lubricant performance based on grain shape and deformed lubricant surface expansion. As a result, developed lubricant were found to perform comparable to or better than zinc phosphate. And thought this result, innovatively cope with generated problem of existing lubrication process.

• 한국주거학회논문집
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• 제13권5호
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• pp.31-42
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• 2002

This comparative study between Korean and German housings aims at understanding different structural systems in the indoor and outdoor spaces, depending upon the user′s perception of the socio-cultural attributes. The analysis starts with four alternative contrary assumptions, that appear in morphological forms of dwelling; 1) linear distribution vs. areal distribution of residential districts, 2) mirror system vs. comb system in the layout of plot plans 3) organization of front vs. back outdoor spaces and 4) opening vs. closing in the indoor spaces. A clear difference is found between Korean and German samples in view of public and private relationships between indoor and outdoor spaces as well as the intermediate space. In the korean housing there always exists a symbolic and psychological territory of a certain sphere. On the other hand, outdoor space passes through various phases only to form a certain hierarchy even in a private space and, thereby, sets a boundary between private and public areas. In the case of Germany, the building itself draws a clear line between private and public outdoor spaces, and therefore the outdoor space has a "front" and "back". Thus, Germany′s private space may face a genuine public space and street, which is rare in the Korean housing. Although the layout of indoor space in the korean housing tends to be open, such an openness may be outstanding in living and dining spaces, kitchen and various accesses to rooms. In the case of Germany, such indoor spaces are usually closed to each other. Thus corridors act to separate these spaces. Such differences are analysed to be due to the different perceptions of interpersonal and socio-cultural attributes as intra-family and inter-neighbor relationships or communications.