• 대한수학회보
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• 제58권4호
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• pp.837-851
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• 2021

Let R ⊆ L ⊆ S be ring extensions. Two star operations ${\ast}_1{\in}Star(R,S)$, ${\ast}_2{\in}Star(L,S)$ are said to be linked if whenever $A^{{\ast}_1}= R^{{\ast}_1}$ for some finitely generated S-regular R-submodule A of S, then $(AL)^{{\ast}_2}=L^{{\ast}_2}$. We study properties of linked star operations; especially when ${\ast}_1$ and ${\ast}_2$ are strict star operations. We introduce the notion of Prüfer star multiplication extension ($P{\ast}ME$) and we show that under appropriate conditions, if the extension R ⊆ S is $P{\ast}_1ME$ and ${\ast}_1$ is linked to ${\ast}_2$, then L ⊆ S is $P{\ast}_2ME$.

• East Asian mathematical journal
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• 제34권5호
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• pp.571-575
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• 2018

Let D be an integral domain, ${\ast}$ a star-operation on D, and S a (not necessarily saturated) multiplicative subset of D. In this article, we prove the Cohen type theorem for $S-{\ast}_{\omega}$-principal ideal domains, which states that D is an $S-{\ast}_{\omega}$-principal ideal domain if and only if every nonzero prime ideal of D (disjoint from S) is $S-{\ast}_{\omega}$-principal.

• 충청수학회지
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• 제24권2호
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• pp.221-238
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• 2011

We prove the Hyers-Ulam stability of generalized Jensen's equations in Banach modules over a unital $C^{\ast}$-algebra. It is applied to show the stability of generalized Jensen's equations in a Hilbert module over a unital $C^{\ast}$-algebra. Moreover, we prove the stability of linear operators in a Hilbert module over a unital $C^{\ast}$-algebra.

• 대한수학회보
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• 제35권4호
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• pp.641-652
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• 1998

Chung and et al. ([2].1991) introduced a new concept of a manifold, denoted by $^{\ast}g-SEX_n$, in Einstein's n-dimensional $^{\ast}g$-unified field theory. The manifold $^{\ast}g-SEX_n$ is a generalized n-dimensional Riemannian manifold on which the differential geometric structure is imposed by the unified field tensor $^{\ast}g^{\lambda \nu}$ through the SE-connection which is both Einstein and semi-symmetric. In this paper, they proved a necessary and sufficient condition for the unique existence of SE-connection and sufficient condition for the unique existence of SE-connection and presented a beautiful and surveyable tensorial representation of the SE-connection in terms of the tensor $^{\ast}g^{\lambda \nu}$. Recently, Chung and et al.([3],1998) obtained a concise tensorial representation of SE-curvature tensor defined by the SE-connection of $^{\ast}g-SEX_n$ and proved deveral identities involving it. This paper is a direct continuations of [3]. In this paper we derive surveyable tensorial representations of constracted curvature tensors of $^{\ast}g-SEX_n$ and prove several generalized identities involving them. In particular, the first variation of the generalized Bianchi's identity in $^{\ast}g-SEX_n$, proved in theorem (2.10a), has a great deal of useful physical applications.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2290-2295
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• 2018

An acceleration stress test (AST) was performed to evaluate the durability of a polymer membrane in a polymer electrolyte membrane fuel cell (PEMFC) for 500 hours. Previous studies have shown that hydrogen crossover measured by linear sweep voltammetry (LSV) increases when the polymer membrane deteriorates in the AST process. On the other hand, hydrogen crossover of the membrane often decreases in the early stages of the AST test. To investigate the cause of this phenomenon, we analyzed the MEA operated for 50 hours using the AST method (OCV, RH 30% and $90^{\circ}C$). Cyclic voltammetry and transmission electron showed that the electrochemical surface area (ECSA) decreased due to the growth of electrode catalyst particles and that the hydrogen crossover current density measured by LSV could be reduced. Fourier transform infrared spectroscopy and thermogravimetric/differential thermal analysis showed that -S-O-S- crosslinking occurred in the polymer after the 50 hour AST. Gas chromatography showed that the hydrogen permeability was decreased by -S-O-S- crosslinking. The reduction of the hydrogen crossover current density measured by LSV in the early stages of AST could be caused by both reduction of the electrochemical surface area of the electrode catalyst and -S-O-S- crosslinking.

• 한국정보과학회논문지:시스템및이론
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• 제36권6호
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• pp.502-510
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• 2009

Multiprecision Squaring은 공개키 알고리즘을 구성하는 연산 중에서 가장 중요한 연산 중 하나이다. 본 논문에서는 기존의 Multiprecision Squaring 알고리즘을 개선하여 연산 양을 줄임으로 성능을 항상시키는 Squaring 기법들을 제시하고 구현하였다. Scott이[1]에서 제안한 Carry-Catcher Hybrid 곱셈 알고리즘은 Gura가 제안한 Hybrid 곱셈 알고리즘[2]을 계승 발전시킨 것으로 MRACL 라이브러리에 구현되어 있으며, Carry-Catcher Hybrid 방법 사용한 Multiprecision Squaring 알고리즘도 MIRACL에 함께 구현되어 있다. 본 논문에서 이 Carry-Catcher Hybrid Squaring 알고리즘을 발전시켜 보다 효율적인 Squaring 알고리즘인 Lazy Doubling Squaring 알고리즘을 제안하고 구현하였으며, atmega128상에서 성능테스터를 수행하여 Carry-Catcher Hybrid Squaring 알고리즘과 비교하여 더 효율적인 알고리즘임을 보였다. 표준 Squaring 알고리즘이 $S_{ij}\;=\;x_i\;{\ast}\;x_j\;=\;S_{ij}$인 사실을 기반으로 곱셈의 횟수를 절반 가까이 줄인 알고리즘이라면 본 논문에서 제시한 Lazy Doubling Squaring 알고리즘은 $a_0\;{\ast}\;2\;+\;a_1\;{\ast}\;2\;+\;...\;+\;a_{n-1}\;{\ast}\;2\;+\;a_n\;{\ast}\;2\;=\;(a_0\;+\;a_1\;+\;...\;+\;a_{n-1}\;+\;a_n)\;{\ast}\;2$ 라는 사실을 기반으로 하여 doubling 연산 횟수를 획기적으로 줄인 알고리즘으로, MIRACL에 구현되어 있는 Multiprecision Squaring 알고리즘 보다 atmega128상에서 약 25% 정도의 빠른 결과를 얻을 수 있었으며, 저자가 아는 바로는 현재까지 나온 어떤 방법보다 빠르다.

• 대한치과보철학회지
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• 제33권1호
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• pp.24-31
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• 1995

This study was performed to investigate the color stability and shear bond strength of denture repair resins. The denture base resins used in this study were Premium Super-20(Lang Dental Mfg. Co., Inc.,.U.S.A.) as heat curing resin, Triad VLC Denture Base(Dentsply/York Division, U.S.A.), Triad Reline Material(Dentsply/York Division, U.S.A.), Repair Acrylic(Lang Dental Mfg. Co., Inc.,. U.S.A.), Toughron Rebase (MikiChemical Product, Kyoto, Japan), and Tokuso Rebase(Tokuyama Soda Co., Ltd., Japan) as denture repair resin. After fabrication of specimens, they stored for 20 months, then color changes and shear bond strength were measured by colorimeter(Model TC-6FX, Tokyo Denshoku Co.) and Instron Universial Test Machine. The results were as follows : 1. There were changes of $L^{\ast},\;a^{\ast},\;b^{\ast}$ and $DE^{\ast}$ in Triad VLC Denture Base after 20 months. 2. There were changes of $a^{\ast}$ in Toughron Rebase and Tokuso Rebase, and $b^{\ast}$ in Tokuso Rebase after 20 months. 3. The shear bond strength of Repair Acrylic and Toughron Rebase were higher than that of Tokuso Rebase and Triad Reline Material.

• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 2004년도 제34차 추계 국제 학술대회
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• pp.188-191
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• 2004

본 실험은 돈육 후지 부위를 이용하여 육포를 제조하는 과정에서 침지 시간에 따른 육포의 물리적, 이화학적 특성 및 관능적 특성을 조사하여 육포제조 방법을 더욱 표준화 하고자 실시하였다. 침지시간에 따른 돈육 후지의 침지수율은 시간이 경과함에 따라 유의적으로 높아졌고 pH는 침지시간에 따라 차이가 없었으며 보수력은 유의적으로 높았다. 육색은 $L^{\ast}$, $a^{\ast}$, $b^{\ast}-value$ 모두에서 침지시간이 경과함에 따라 유의적으로 낮아졌다. 건조하여 제조된 육포의 건조수율은 침지시간이 경과함에 따라 유의적으로 높아졌으나 수분함량은 차이가 없었으며. 육색은 $L^{\ast}$, $a^{\ast}$, $b^{\ast}-value$ 모두 침지시간이 길어짐에 따라 유의적으로 낮아졌다. 조직감 측정은 12시간 침지한 육포의 hardness가 높았으며 24시간 침지한 육포의 springiness가 높았고 48시간 침지한 육포의 cohesiveness, gumminess, chewiness가 전체적으로 높은 값을 보였다.

• 대한유전성대사질환학회지
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• 제13권1호
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• pp.43-47
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• 2013

Introduction: ALT/AST enzymes are present inside the cells. AST is found in cardiac and skeletal muscle and red blood cells but the ALT is checked mainly in the liver. In general, the rise of these two indicators shows liver damage. The usual measurements of these enzymes are used in liver function tests, but the levels of AST and ALT do not always reflect liver function. Method and Cases: 17 cases of liver dysfunction transiently were evaluated clinically, biochemically, and imaging study of sonogram in pediatric in-patients for 3 years. Result: Most common causes of transient liver dysfunction were infection, especially viral gastroenteritis, and bacterial infection interfering oral food intake. More often occurred in the children who have infant hyperbilirubinemia, positive history of mitochondrial dysfunction or hypoglycemia. Fasting study in one case of hypoglycemia patient showed reversible liver dysfunction during fasting over 20 hours fasting. Discussion: A significant increase in AST and ALT with normal bilirubin can be observed in clinically healthy people during blunt trauma, viral infection, severe pain, metabolic syndrome, fasting or accidental health screening.

• Nutritional Sciences
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• 제5권4호
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• pp.203-210
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• 2002

Aster scaber $T_{HUNB}$ (AST ; Charm-chui), a potent herbal medicinal plant, has a long tradition of use, being harvested as a wild plant, is said to stimulate appetite, and may act as a diuretic, antifebrile agent and painkiller. This study was conducted to investigate the immunomodulative effects of AST In mice, using in vitro and in vivo experiments. The immunomodulative effects were studied in vitro by measuring the proliferation of mice splenocytes and the production of three kinds of cytokines (IL-$\beta$, IL-6, and TNF-$\alpha$) by mice peritoneal macrophages which were cultured with sequential fractions of AST methanol extract (methanol, hexane, chlo-roform, ethylacetate, butanol and water). In an in vivo experiment using mice, different concentrations of AST water extract were orally administrated every other day for two weeks. The production of cytokines (IL-1$\beta$, IL-6, and TNF-$\alpha$) secreted by activated macrophages, and the proliferation of mice splenocytes, were used as indices for immunocompetence. In vitro supplementation using six fractions of AST in the range of 1 to 100$\mu$ g/ml enhanced splenocyte proliferation by 10.5% to 53% compared to the control. IL-1$\beta$production was significantly increased with the supplementation of butanol and water extracts of AST. Higher levels of IL-6 and TNF-$\alpha$production were detected with supplementation of methanol, ethylacetate, butanol or water extracts at the concentration of 100$\mu$ g/ml. In the in vivo study, the highest proliferation of splenocytes was seen in the mice orally administrated with the AST water extract at the concentration of 500mg/kg body weight. In the case of cytokine production, there were no significant differences in the production of IL-1$\beta$and IL-6 among the treated groups and the control. However, TNF-$\alpha$released by activated peritoneal macrophages were augmented by the oral administration of AST water extract. These results indicate that AST may enhance the immune functions by regulating splenocyte proliferation and cytokine production capacity in mice.