• 전력전자학회논문지
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• 제19권6호
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• pp.538-548
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• 2014

This study provides a robust control of a grid-connected three-phase two-level photo voltaic inverter. The introduced control method uses the cascade control strategy to regulate AC-side current and DC-link voltage. A robust controller with integration action is used for the inner-loop AC-side current control, which maximizes the convergence rate using a linear matrix inequality-based optimization design method and eliminates the offset error. The robust controller design method considers the parameter uncertainty set to accommodate parameter mismatch and un-modeled components in the inverter model. An outer-loop proportional-integral controller is used to regulate DC-link voltage with linearization of DC/AC relation. The proposed control strategy is applied to a grid-connected 100 kW photo voltaic inverter.

• 한국분말재료학회지
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• 제10권6호
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• pp.443-447
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• 2003

Nano-sized $TiB_2$ was in situ synthesized in copper matrix through self-propagating high temperature synthesis (SHS) with high-energy ball milled Ti-B-Cu elemental mixtures as powder precursors. The size of $TiB_2$ particles in the product of SHS reaction decreases with time of preliminary mechanical treatment ranging from 1 in untreated mixture to 0.1 in mixtures milled for 3 min. Subsequent mechanical treatment of the product of SHS reaction allowed the $TiB_2$ particles to be reduced down to 30-50 nm. Microstructural change of $TiB_2$-Cu nanocomposite during spark plasma sintering (SPS) was also investigated. Under simultaneous action of pressure, temperature and electric current, titanium diboride nanoparticles distributed in copper matrix move, agglomerate and form a interpenetrating phase composite with a fine-grained skeleton.

• 소성∙가공
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• 제8권3호
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• pp.295-295
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• 1999

In the present study, the corrosion behavior of AZ91D as-cast alloy was investigated form the viewpoint of the distribution aspect of precipitate ($Mg_{17}Al_{12}$) and the variation of Al concentration in the Mg-rich matrix. The dendrite arm spacing (DAS) of an as-cast specimen was measured as a function of degree which describes the distribution aspect of the precipitate, and the salt spray test was conducted for various grain-sired specimens fur 20 days. The dendrite arm spacing increased as the grain size increased to about 150㎛, but a constant value is indicated when the grain size exceeds that range. Although the relationship between the corrosion rate and grain size is of a nonlinear type, the linear trend between the corrosion rate and the dendrite arm spacing is maintained for the overall range of dendrite arm spacing. Since the precipitate in the as-cast alloy is discontinuously distributed, this linear relationship means that the variation of Al-solute concentration in the Mg-rich matrix has a more potent effect than the protective action of the precipitate on the corrosion behavior of an as-cast alloy.

• Journal of Pharmaceutical Investigation
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• 제5권1호
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• pp.41-48
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• 1975

Extrusion-Spheronization Processing (ESP) was applied to preparate sustained release spherical particles as a form of matrix spherical particle (MSP). dl-methylephedrine HCI (ME) was the drug chosen and several dissolution retardants and binders were selected to estimate a relatively good formulation on this purpose. The effect of physicochemical nature, concentration, and solvents of these dissolution retardants and binders on regularity in shape of MSP and in vitro release rate was investigated. The effect of Particle size of matrix particles was also evaluated. It is, therefore, concluded that this ESP would be a relatively good preparation method of sustained release MSP of ME which has the sustained action of about 5 and 8 hours by formulating of ethylcellulose and ethylcellulose-paraffin as a dissolution retardant, respectively, and then ethylcellulose solution of 80% EtOH is recommended as a binder.

• 식품과학과 산업
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• 제51권2호
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• pp.127-135
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• 2018

지방산화는 기본적으로 불포화지방과 산소의 결합이나 이 현상을 제대로 알고 실제 식품에 적용하기 위해서는 지방산화에 미치는 모든 인자들의 화학적 관점(one-electron reduction potential, bond dissociation enthalpy) 뿐만 아니라 물리적 현상(interface, antioxidant polar paradox)을 포괄적으로 이해해야 한다. Invitro실험법에 의해 도출된 산화방지제는 가능성을 보여주는 것이나 실제 식품과 bulk oil, 유화형태, 오르가노젤과 같은고체 상태의 다양한 매트릭스에서는 다른 활성을 나타낸다. 또한 산화방지제의 농도와 다른 물질의 존재에 따라 예상과 다른 활성을 나타내기도 한다. 산화방지제를 활용하여 최종제품의 유통기한을 증가시키기 위해서는 실제 활용될 제품의 매질로 사용해야 한다.

• International Journal of Oral Biology
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• 제46권1호
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• pp.51-59
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• 2021

Periodontal disease is an inflammatory disease that affects the destruction of the bone supporting the tooth and connective tissues surrounding it. Periodontal ligament fibroblasts (PDLFs) induce overexpression of matrix metalloproteinase (MMP) involved in periodontal disease's inflammatory destruction. Osteoclasts take part in physiological bone remodeling, but they are also involved in bone destruction in many kinds of bone diseases, including osteoporosis and periodontal disease. This study examined the effect of baicalin on proteolytic enzymes' production and secretion of inflammatory cytokines in PDLFs and RAW 264.7 cells under the lipopolysaccharide (LPS)-induced inflammatory conditions. Baicalin inhibited the expression of the protein, MMP-1 and MMP-2, without affecting PDLFs' cell viability, suggesting its possibility because of the inhibition of phosphorylation activation of mitogen-activated protein kinase's p38, and the signal transduction process of nuclear factor κB (NFκB)-related protein. Also, baicalin reduced the expression of MMP-8 and MMP-9 in RAW 264.7 cells. This reduction is thought to be due to the inhibition of the signal transduction process of NFκB-related proteins affected by inhibiting p65RelA phosphorylation. Also, baicalin inhibited the secretion of nitric oxide and interleukin-6 induced by LPS in RAW 264.7 cells. These results suggest that baicalin inhibits connective tissue destruction in periodontal disease. The inhibition of periodontal tissue destruction may be a therapeutic strategy for treating inflammatory periodontal-diseased patients.

• Journal of Pharmaceutical Investigation
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• 제30권3호
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• pp.179-189
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• 2000

Clebopride malate(Cm) is a new benzamide drug which has a potent central antidopaminergic activity possessing antiemetic and anxiolytic properties. A purpose of this study was to assess the feasibility of formulating sustained release preparation by dispersing a drug in hydrophilic polymeric matrices and double layered tablets(DLT), using HPMC, carbopol, PEO, PVP/VA and other polymers as a rate controlling barrier. The matrix and DLT showed optimum dissolution pattern up to 8 hours and the contents of polymer were optimized at 30% level in this preparation. After an oral administration in beagle dog, Cm concentration was determined by use of GC-ECD and pharmacokinetic parameters were calculated by Vallner's method. The AUC of DLT showed similar results and the duration of action was increased 55% compared to that of regular release dosage form. The calculated absorption rate effectiveness(ARE) and controlled release effectiveness(CRE) for DLT increased 50% compared to that of matrix, the overall effectiveness(E) of this product appears to be about 70%. in vivo effectiveness test, DLT showed significant differences from control on antiemetic action of Cm. In consequence, it was possible to conclude that double layered tablet might be a good candidate for the sustained release dosage forms.

• 한국식품영양과학회지
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• 제33권5호
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• pp.797-802
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• 2004

L-Ascorbic acid (AsA), commonly known as vitamin C, which is one of the antioxidant vitamins, plays a role in cellular oxidant quenching. Some of the biochemical reactions in which it takes part have been traced through organ culture technique. But in cell cultured system, views on stimulatory and inhibitory action of AsA on cell growth are conflicting. Therefore, this study aimed to clarify the inhibitory action of high concentration AsA on the cell growth in Primary chondrocyte isolated from rat ribs. Cells were exposed to ascorbate at various concentrations. Supplement of AsA induced stimulation of cell growth in primary cultured cells of chondrocytes. Most remarkable stimulation of cell growth by AsA was found in primary cultured chondrocytes. However, it showed that they were dead in the medium which contained AsA at the concentration higher than 1.0 mM. This lethal effect of AsA causing the cell death was inhibited by the addition of catalase in the medium. This supposed that hydroxyl radical (ㆍOH) induced from $H_2O$$_2$ was actively cytotoxic agent. Based on the results, when AsA was added in medium at normal concentrations, the cell growth was stimulated by inducing the formation of extracellular matrix. On the contrary, if added in medium at excess concentrations, the cell growth was inhibited because $H_2O$$_2$ were generated from AsA in medium. Therefore, addition of AsA at the normal concentrations stimulates cell growth, but excess concentrations of AsA induces cell death.

• 디자인융복합연구
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• 제16권6호
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• pp.137-152
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• 2017

본 연구는 실버세대를 위한 컴패니언 로봇의 인터랙션 경험 디자인을 위해 사용자 태스크- 로봇 기능 적합도 매핑에 기반한 로봇 유형 분석과 멀티모달 대화 인터랙션에서의 로봇 감정표현 연구를 수행하였다. 노인의 니즈 분석을 위해 노인과 자원 봉사자를 대상으로 FGI, 에스노그래피를 진행하였으며 로봇 지원 기능과 엑추에이터 매칭을 통해 로봇 기능 조합 유형에 대한 분석을 하였다. 도출된 4가지 유형의 로봇 중 표정 기반 대화형 로봇 유형으로 프로토타이핑을 하였으며 에크만의 얼굴 움직임 부호화 시스템(Facial Action Coding System: FACS)을 기반으로 6가지 기본 감정에 대한 표정을 시각화하였다. 사용자 실험에서는 로봇이 전달하는 정보의 정서코드에 맞게 로봇의 표정이 변화할 때와 로봇이 인터랙션 사이클을 자발적으로 시작할 때 사용자의 인지와 정서에 미치는 영향을 이야기 회상 검사(Story Recall Test: STR)와 표정 감정 분석 소프트웨어 Emotion API로 검증하였다. 실험 결과, 정보의 정서코드에 맞는 로봇의 표정 변화 그룹이 회상 검사에서 상대적으로 높은 기억 회상률을 보였다. 한편 피험자의 표정 분석에서는 로봇의 감정 표현과 자발적인 인터랙션 시작이 피험자들에게 정서적으로 긍정적 영향을 주고 선호되는 것을 확인하였다.

• Translational and Clinical Pharmacology
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• 제25권2호
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• pp.67-73
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• 2017

Glimepiride, a third generation sulfonylurea, is an antihyperglycemic agent widely used to treat type 2 diabetes mellitus. In this study, an untargeted urinary metabolomic analysis was performed to identify endogenous metabolites affected by glimepiride administration. Urine samples of twelve healthy male volunteers were collected before and after administration of 2 mg glimepiride. These samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and then subjected to multivariate data analysis including principal component analysis and orthogonal partial least squares discriminant analysis. Through this metabolomic profiling, we identified several endogenous metabolites such as adenosine 3', 5'-cyclic monophosphate (cAMP), quercetin, tyramine, and urocanic acid, which exhibit significant metabolomic changes between pre- and posturine samples. Among these, cAMP, which is known to be related to insulin secretion, was the most significantly altered metabolite following glimepiride administration. In addition, the pathway analysis showed that purine, tyrosine, and histidine metabolism was affected by pharmacological responses to glimepiride. Together, the results suggest that the pharmacometabolomic approach, based on LC-MS/MS, is useful in understanding the alterations in biochemical pathways associated with glimepiride action.