• Food Science and Biotechnology
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• 제18권2호
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• pp.336-342
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• 2009

To confirm the antimicobial mechanism of Torilis japonica, antimicrobial profile was observed on various spore conditions by combining 0.1% (3 mM) torilin with antimicrobial activity and 0.27% water fraction with germinants. A 75% ethanol extract of T. japonica fruit reduced Bacillus subtilis ATCC 6633 spore counts by 3 log cycles and reduced the vegetative cells to undetectable level (by about 6 log cycles) (both in terms of CFU/mL). Further fractionating the ethanol extract into n-hexane and water fractions revealed that the former reduced the spore count by 1 log cycle whereas the latter had no effect. The antimicrobial active compound was isolated and purified from the hexane layer, and identified as torilin ($C_{22}H_{32}O_5$). The water fraction of the ethanol layer did not show antimicrobial activity, whereas the antimicrobial effect of 0.1% (3 mM) torilin was significantly enhanced in the presence of the water fraction (0.27%). This result can be explained by synergistic effects of the water fraction containing considerable amounts of germinants such as L-alanine and K+ ions that triggered germination.

• Smart Structures and Systems
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• 제22권6호
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• pp.675-687
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• 2018

In the previous studies on the porous rock strength the effect of pore number and its diameter is not explicitly defined. In this paper crack initiation, propagation and coalescence in Brazilian model disc containing a single cylindrical hole and or multiple holes have been studied numerically using PFC3D. In model with internal hole, the ratio of hole diameter to model diameter was varied between 0.03, 0.17, 0.25, 0.33, and 0.42. In model with multiple hole number of holes was different in various model, i.e., one hole, two holes, three holes, four holes, five holes, six holes, seven holes, eight holes and nine holes. Diameter of these holes was 5 mm, 10 mm and 12 mm. The pre-holed Brazilian discs are numerically tested under Brazilian test. The breakage load in the ring type disc specimens containing an internal hole with varying diameters is measured. The mechanism of cracks propagation in the wall of the ring type specimens is also studied. In the case of multi-hole Brazilian disc, the cracks propagation and b cracks coalescence are also investigated. The results shows that breaking of the pre-holed disc specimens is due to the propagation of radially induced tensile cracks initiated from the surface of the central hole and propagating toward the direction of diametrical loading. In the case of disc specimens with multiple holes, the cracks propagation and cracks coalescence may occur simultaneously in the breaking process of model under diametrical compressive loading. Finally the results shows that the failure stress and crack initiation stress decreases by increasing the hole diameter. Also, the failure stress decreases by increasing the number of hole which mobilized in failure. The results of these simulations were comprised with other experimental and numerical test results. It has been shown that the numerical and experimental results are in good agreement with each other.

• 한국지능시스템학회논문지
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• 제13권2호
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• pp.137-147
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• 2003

새로운 3차원 도립진자 시스템의 구현 및 퍼지제어에 관하여 논한다. 기존의 1차원 또는 2차원 도립진자 시스템과 달리, 3차원 도립진자 시스템은 상하 운동을 포함하는 인간의 도립진자 제어행위를 적절히 모사할 수 있는 새로운 시스템이다. 3차원 도립진자 시스템의 특성 분석과 퍼지제어기 설계를 위하여 3축 직교로봇과 도립진자를 포함하는 기구부의 동력학식을 유도한다. 로봇의 여유자유도와 제한된 작업영역을 고려하면서 도립진자의 요오(yaw) 및 피치(pitch)각을 제어하기 위한 퍼지제어기 설계 방법을 제안한다. 개발된 PC 기반의 다축제어보드를 이용한 실험 결과를 통하여 제안된 시스템의 성능을 검증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.321-324
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• 1991

In this study, $(Sr{\cdot}Pb)TiO_3$ series ceramics which is used in high voltage were fabricated by the mixed oxide method, and the electrical conduction mechanism and D.C. breakdown voltage characteristics of the specimens in accordance with the contents of $Bi_2O_3{\cdot}3TiO_2$ were investigated. As a result, the leakage current was increased with the contents of $Bi_2O_3{\cdot}3TiO_2$ and the measuring temperature. At room temperature, the leakeage current was showed a tendency of saturating when D.C. electrical field of $l5{\sim}30$[kV/cm] was applied to the specimen. As a result of breakdown voltage characteristics. breakdown strength was decreased when the contents of $Bi_2O_3{\cdot}3TiO_2$ were increased. On the other hand, in the temperature region below $60[^{\circ}C]$, the electronic breakdown was occured, and in the temperature region from 60 to $200[^{\circ}C]$, the thermal breakdown was occured by the Joule heat and the dissipation factor.

• 대한화학회지
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• 제24권1호
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• pp.8-14
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• 1980

메틸클로로휘메이트, $CH_3O$(CO)Cl와 메틸티오노클로로휘메이트, $CH_3O$(CS)Cl 및 메틸티올클로로휘메이트, $CH_3S$(CO)Cl의 가용매분해반응속도상수를 아세톤-물 및 아세토니트릴-물혼합용매중에서 전기전도도법으로 측정했으며 활성화파라미터, ${\Delta}H^{\neq}$ 와 ${\Delta}S^{\neq}$를 구하였다. 그 결과로 물함량이 큰 영역에서는 속도순위가 $$CH_3O(CO)Cl 이며, 한편 dipolar aprotic solvent가 큰 부분에서는 속도의 순위가 거꾸로 임을 알았다. log k대 solvent parameter인 Y, $\frac{D-1}{2D+1}$ 와 log($H_2$) 의 plots는 물함량이 큰 부분에서 $S_N1$ 성격이 증가함을 보여준다. 물함량이 큰 영역에서 $CH_3O$(CO)Cl은 $S_N2$로 $CH_3O$(CS)Cl은 중간정도의 메카니즘으로 반응하나 $CH_3S$(CO)Cl은 $S_N1$ 메카니즘으로 반응함을 알았다.

• Nutrition Research and Practice
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• 제16권6호
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• pp.745-754
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• 2022

BACKGROUND/OBJECTIVES: The incidence of cardiovascular diseases (CVDs) has increased worldwide. Although a low serum vitamin D level is known to be associated with the risk of CVD, the mechanism is not well understood yet. The aim of this study was to determine the relationship of serum 25-hydroxyvitamin D₃ (25[OH]D) with homocysteine and apolipoprotein B (ApoB). SUBJECTS/METHODS: Of 777 subjects recruited from one health promotion center for routine heath exam from January 2010 to December 2016, 518 subjects were included in this study. Serum 25(OH)D, serum homocysteine, and other metabolic parameters including ApoB were analyzed. Simple and partial correlations were carried out after adjustments. Simple linear regression analysis was used for precise correlation of parameters. Multivariate regression analysis was done to know which factor (serum homocysteine or ApoB) was more related to serum 25(OH)D after adjustments. Finally, logarithms of homocysteine concentrations according to tertiles of serum 25(OH)D were compared. RESULTS: After sex and age adjustments, serum 25(OH)D showed negative correlations with serum homocysteine (r' = -0.114) and ApoB (r' = -0.098). In simple linear regression analysis, serum 25(OH)D showed a significant negative correlation with ApoB (P = 0.035). However, in multivariate regression analysis, serum 25(OH)D was significantly associated with serum homocysteine after adjustments (P = 0.022). In addition, serum homocysteine concentration was significantly high in the lowest 25(OH)D group (P = 0.046). CONCLUSION: Serum 25(OH)D concentration showed a stronger negative association with serum homocysteine than with ApoB.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.1037-1041
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• 2012

The nucleophilic substitution reactions of (2R,4R,5S)-(+)-2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide (3) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $5.0^{\circ}C$. The anilinolysis rate of 3 involving a cyclic five-membered ring is considerably fast because of small negative value of the entropy of activation (${\Delta}S^\neq=-2cal\;mol^{-1}\;K^{-1}$) over considerably unfavorable enthalpy of activation (${\Delta}H^\neq=18.0\;kcal\;mol^{-1}$). Great enthalpy and small negative entropy of activation are ascribed to sterically congested transition state (TS) and bulk solvent structure breaking in the TS. A concerted $S_N2$ mechanism with a backside nucleophilic attack is proposed on the basis of the secondary inverse deuterium kinetic isotope effects, $k_H/k_D$ < 1.

• 한국통신학회논문지
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• 제36권9C호
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• pp.573-580
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• 2011

무선 센서 네트워크는 다양한 분야에서 광범위하게 사용되고 있으며, 무선측위는 센서 네트워크의 응용을 위한 필수적이고 핵심적인 기술로 집중을 받고 있다. 하지만 무선 센서 네트워크의 환경이 3차원으로 이루어져 있는 반면에 대부분의 무선측위 기법은 2차원으로 구현되어 있어 새로운 기법이 요구되고 있는 상황이다. 이에 본 논문에서는 3차원 공간에서 동작하는 무선 센서 네트워크를 위한 저복잡도 무선측위 메커니즘을 제안한다. 기본 개념은 2개의 앵커 노드를 한쌍으로 탑재한 비행체를 이용하는 것으로, 이 앵커 노드들은 그들의 현재 위치를 담고있는 비컨 신호를 주기적으로 전파하며 임의 노드들은 앵커 노드들의 통신 범위에 들어가자마자 이 비컨 신호를 수신한다. 제안된 기법은 3차원 무선측위의 복잡도를 줄이기 위하여 3차원 문제를 2차원의 계산으로 변형하여 임의 노드의 위치를 추정한다. 모의실험 결과를 통해 무선 센서 네트워크에서 제안된 기법이 3차원 무선측위에 효과적임을 확인하였다.

• Journal of Ginseng Research
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• 제44권2호
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• pp.274-281
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• 2020

Background: Ultraviolet (UV) goes through the epidermis and promotes release of inflammatory cytokines in keratinocytes. Granulocyte-macrophage colony-stimulating factor (GM-CSF), one of the keratinocyte-derived cytokines, regulates proliferation and differentiation of melanocytes. Extracellular signal-regulated kinase (ERK1/2) and protein kinase C (PKC) signaling pathways regulate expression of GM-CSF. Based on these results, we found that ginsenoside Rh3 prevented GM-CSF production and release in UV-B-exposed SP-1 keratinocytes and that this inhibitory effect resulted from the reduction of PKCδ and ERK phosphorylation. Methods: We investigated the mechanism by which ginsenoside Rh3 from Panax ginseng inhibited GM-CSF release from UV-B-irradiated keratinocytes. Results: Treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) or UV-B induced release of GM-CSF in the SP-1 keratinocytes. To elucidate whether the change in GM-CSF expression could be related to PKC signaling, the cells were pretreated with H7, an inhibitor of PKC, and irradiated with UV-B. GM-CSF was decreased by H7 in a dose-dependent manner. When we analyzed which ginsenosides repressed GM-CSF expression among 15 ginsenosides, ginsenoside Rh3 showed the largest decline to 40% of GM-CSF expression in enzyme-linked immunosorbent assay. Western blot analysis showed that TPA enhanced the phosphorylation of PKCδ and ERK in the keratinocytes. When we examined the effect of ginsenoside Rh3, we identified that ginsenoside Rh3 inhibited the TPA-induced phosphorylation levels of PKCδ and ERK. Conclusion: In summary, we found that ginsenoside Rh3 impeded UV-B-induced GM-CSF production through repression of PKCδ and ERK phosphorylation in SP-1 keratinocytes.

• 대한화학회지
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• 제47권3호
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• pp.199-205
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• 2003

우라닐 이온, $UO^+_2$와 Schiff-base 와의 착화합물이 글리실글라이신과 살리실알데히드, 2-히드록시-1-나프트알데히드, 2,3-디히드록시 벤즈알데히드 그리고 2,4-디히드록시 벤즈알데히드와의 축합에 의해 합성되었으며 이들 착화합물의 특성을 원소분석, 전도도 측정, 자기화율 측정, UV, IR, NMR 스펙트라와 DTA, TG, DSC 결과를 이용하여 조사하였다. 구조와 열분해 메카니즘이 제안되었다.