• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.57-68
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• 2018

The main objective of this study is to prepare the bionanocomposite films using mungbean starch (MBS), PVA, ZnS, and plasticizers, and to evaluate the physical properties, thermal stability, and photocatalytic activity. The bionanocomposite films were cross-linked by heat-curing process. The ZnS and bionanocomposite films were characterized by FT-IR, XRD, and SEM. The results indicated that the mechanical properties and water resistance enhanced up to 1.2-1.5 times by the addition of nano-ZnS particles, and the thermal stability was improved by the addition of nano-ZnS particles. The photocatalytic activity of the bionanocomposite films added nano-ZnS particles was examined using bisphenol A (BPA) and methyl orange (MO). In addition, the photodegradation efficiency of BPA and MO was evaluated using the pseudo-first order kinetic model (PFOK).

• 한국지반공학회논문집
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• 제18권2호
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• pp.97-105
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• 2002

불연속면의 확률특성은 불연속면의 생성이 자연적인 현상에 의해 이루어 졌으며 불연속면의 특성을 파악하기 위한 시험이나 자료 획득의 기술적인 제약, 획득 가능한 자료 양의 제약에 기인한다. 따라서 다른 지반공학분야와 마찬가지로 암반사면해석에서도 불확실성이 필연적으로 개입되며 이러한 불확실성을 효과적으로 다루기 위한 방법으로 확률론적 해석방법이 제안되었다. 그러나 현재까지 제안된 암반사면의 확률론적 해석기 법은 대개 운동학적인 분석이 제외된 상태에서 동역학적인 분석 즉, 불연속면의 방향성이 가지는 분산을 고려하지 않고 전단강도의 분산 상태만 고려한 분석이 수행되어왔다. 따라서, 본 연구에서는 이러한 문제점을 보완할 수 있도록 불연속면의 기하학적인 특성과 전단 강도 특성 모두의 확률특성을 고려하여 운동학적인 파괴 가능성과 동역학적인 파괴 가능성으로 구분하여 파괴 확률을 산정하였다. 확률론적 해석 방법과의 비교를 위해 획득한 결정론적인 해석에 의한 결과는 일부 확률론적인 해석결과 와 차이를 보이고 있으며 이는 결정론적인 해석을 위해 선택된 자료의 대표값들이 자료들의 분산에 의해 대표성을 보이지 못하고 있기 때문인 것으로 보인다. 따라서 결정론적 해석 기법을 이용하여 사면의 안정성을 분석하기 위하여서는 자료의 대표값 선정에 신중을 기해야 하며 확률론적 해석기법을 보완적으로 사용하는 것이 오류를 줄일 수 있는 방법 중의 하나로 판단된다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.29.2-29.2
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• 2011

Earth's bow shock is a transition layer across which properties of plasmas change irreversibly. Although some features of the bow shock are well described by continuities of fluxes of various macroscopic quantities, particle dynamics across the transition layer is very complicated. Observed phase space distributions show multiple ion beams and partially thermalized ions around the transition layer. In some cases, both hot magnetosheath ions and cold solar wind ions simultaneously exist in the magnetosheath. Electrons around the transition layer usually have flat-top distributions with temperature anisotropy. From the observed properties of the phase space distributions we will discuss thermalization processes that occur across the shock transition.

• 한국포장학회지
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• 제21권3호
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• pp.107-113
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• 2015

This work focused on the study of thermal properties and kinetic behavior of LDPE-nanoclay composite films. The effect of nanoclay content (0.5, 1, 3, and 5 wt%) on thermal stability and crystallization characteristics of the nanocomposites were investigated by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results from endothermic curve showed that the nanoclay played an important role in the crystallization of nanocomposites by acting as nucleating agent. From exothermic curve, there was a crystallization temperature shift which was attributed to crystallization process induced by nanoclay. The TGA results showed that the addition of nanoclay significantly increased the thermal stability of LDPE matrix, which was likely due to the characteristic of layered silicates/clays dispersed in LDPE matrix as well as the formation of multilayered carbonaceous-silicate char. A well-known Coats-Redfern method was used to evaluate the decomposition activation energy of nanocomposite. It was demonstrated that introducing of nanoclay to LDPE matrix escalated the activation energy of nanocomposite decomposition resulting in thermal stability improvement.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1612-1618
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• 2018

In this work, the ground-state properties of an interacting electron gas confined in a two-dimensional quantum dot system with the Gaussian potential ${\upsilon}(r)=V_0(1-{\exp}(-r^2/p))$, where $V_0$ and p are confinement parameters, are determined numerically by using the Thomas-Fermi approximation. The shape of the potential is modified by changing the $V_0$ and the p values, and the influence of the confining potential on the system's properties, such as the chemical energy, the density profile, the kinetic energy, the confining energy, etc., is analyzed for both the non-interacting and the interacting cases. The results are compared with those calculated for a harmonic potential, and excellent agreement is obtained in the limit of high p values for both the non-interacting and the interacting cases.

• The Korean Journal of Physiology
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• 제20권2호
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• pp.257-270
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• 1986

It has been reported that the luteal function may be regulated by the intracellular calcium in luteal cells (Higuchi et al, 1976; Dorflinger et at, 1984; Gore and Behrman, 1984) which is adjusted partially by $Ca^{++}-ATPase$ activities in luteal cell membranes (Verma and Pennistion, 1981). However, the physicochemical and kinetic properties of $Ca^{++}-ATPase$ in luteal membranes were not fully characterized. This study was, therefore, undertaken to partially characterize the physicochemical and kinetic properties of $Ca^{++}-ATPase$ system in luteal membranes and microsomal fractions, known as an one of the major $Ca^{++}$ storge sites (Moore and Pastan, 1978), from the highly luteinized ovary Highly luteinized ovaries were obtained from PMSG-hCG injected immautre female rats. Light membrane and heavy membrane fractions and microsomal fractions were prepared by the differential and discontinuous sucrose density gradient centrifugation method desribed by Bramley and Ryan (1980). Light membrane and heavy membrane fractions and microsomal fractions from highly luteinized ovaries are composed of the two different kinds of $Ca^{++}-ATPase$ system. One is the high affinity $Ca^{++}-ATPase$ which is activated in low $Ca^{++}$ concentration (Km, 10-30 nM), the other is low affinity $Ca^{++}-ATPase$ activated in higher $Ca^{++}$ concentration $(K_{1/2},\;40\;{\mu}M)$. At certain $Ca^{++}$ concentrations, activities of high and low affinity $Ca^{++}-ATPase$ are the highest in light membrane fractions and are the lowest in microsomal fractions. It appeares that high affinity $Ca^{++}-ATPase$ system have 2 binding sites for ATP (Hill's coefficient; around 2 in all membrane fractions measured) and the positive cooperativity of ATP bindings obviously existed in each membrane fractions. The optimum pH for high affinity $Ca^{++}-ATPase$ activation is around S in all membrane fractions measured. The lipid phase transition temperature measured by Arrhenius plots of high affinity $Ca^{++}-ATPase$ activity is around $25^{\circ}C$. The activation energies of high affinity $Ca^{++}-ATPase$ below the transition temperature are similar in each membrane fractions, but at the above transition temperature, it is the hightest in heavy membrane fractions and the lowest in microsomal fractions. According to the above results, it is suggested that intracellular $Ca^{++}$ level, which may regulate the luteal function, may be adjusted primarily by the high affinity $Ca^{++}-ATPase$ system activated in intracellular $Ca^{++}$ concentration range $(below\;0.1\;{\mu}M)$.

• Composites Research
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• 제18권6호
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• pp.34-39
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• 2005

본 연구에서는 방탄재료로 활용 가능할 것으로 예상되는 여러 구조용 세라믹스의 물리기계적 물성과 방탄물성과의 상호연관성을 분석하였다. 물리기계적 물성을 측정한 후 30mm 고체추진포에서 10.7의 L/D비를 갖는 텅스텐 긴 관통자를 비행시켜 운동에너지(KE)탄에 대한 방탄물성을 측정하였으며, K215 자탄을 기폭시켜 성형작약(HEAT)탄에 대한 방탄물성을 측정하였다. 영률/밀도비, 경도/밀도비 및 꺽임강도/밀도비가 증가할수록 방탄물성이 대체적으로 증가하는 경향을 보였으며, 특히 HEL(Hugoniot Elastic Limit)/밀도비가 증가함에 따라 KE탄에 대한 방탄물성이 선형적으로 증가하는 현상을 나타내었다.

• The Korean Journal of Ceramics
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• 제2권4호
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• pp.226-230
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• 1996

A small amount of fine particle graphite was added to $\alpha$-SiC and $\beta$-SiC having certain particle distributions, and they were mixed clay and frit. After forming, they were sintered at 140$0^{\circ}C$ for 3 hours. Tribological properties of sintered $\alpha$-SiC-$\beta$-SiC-graphite-clay (frit) system showed that kinetic friction coefficient was 0.108, specific wear rate was 1.3${\times}10^-8\;mm^2$.$kgf^1$, and torque was 0.01kgf.cm at the wrench torque of 100 kgf.cm.

• 대한수학회논문집
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• 제10권1호
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• pp.123-131
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• 1995

The notion of our non-associative algebra is obtained from the Lotka-Volterra system of differential equation describing competitiion between animals or vegetals species and also in the kinetic theory of gasses. For the structure of an algebra, the existence of idempotents is of particular interest. But also from the biological aspect the existence of such elements is of interest because the equilibria of a population which can be described by an algebra correspond to idempotents of this algebra. Thus we present some properties of the general natures for a Lotka-Volterra algebra associated to a weight function and idempotents elements.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 1986년도 Priceedings Of The Third Korea-Japan Seminar On New Ceramics
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• pp.211-225
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• 1986

Silicon carbide coating has been studied using a graphite substrate, a mixture of tetramethylsilane and hydrogen or argon at deposition temperature (T) of 950 to $1200^{\circ}C$ total pressure of 20 to 50 torr and carrier gas flow rate of 0 to 901/h. Deposition kinetic study has shown that a transition, from a surface reaction limited process to a diffusion limited one, takes place near $1100^{\circ}C$. Deposition rate depends directly upon the experimental parameters. The influence of the main process parameters is also discussed to relate the physiochemical properties of the coating to the deposition conditions.