• 대한본초학회지
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• 제20권2호
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• pp.83-89
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• 2005

Objectives : This study was performed to investigate the effects of Perilla frutescens var. acuta extracts on growth inhibition of Streptococcus pyogenes KCTC 3208. Methods : Measured growth inhibition of Streptococcus pyogenes KCTC 3208 by concentration of the Perilla frutescens var. acuta. extract and collection periods of the Perilla frutescens var. acuta. and picking region of the Perilla frutescens var. acuta. Results : The Perilla frutescens var. acuta. extract is effective on retarding growth of Streptococcus pyogenes KCTC 3208. At 3% the growth of Streptococcus pyogenes KCTC 3208 was suddenly retarded. The stem of Perilla frutescens var. acuta. extract in a sunny place on June is more effective then its leaf. Conclusions : These results suggest that Perilla frutescens var. acuta. extract is effective in growth inhibition of Streptococcus pyogenes KCTC 3208.

• The Korean Journal of Ceramics
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• 제1권4호
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• pp.214-218
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• 1995

Partially stabilized zironia with magnesia (Mg-PSZ) is known as one of the toughest monolithic ceramics. However, the very large grain sizes obtained after sintering at a high solution-heat treatment temperature in the cubic region of the phase diagram limit the strength of this material rather modest. In this study fine-grained Mg-PSZ materials were fabricated by adding TiC particles as a dispersed phase. Samples were hot-pressed at $1750^{\circ}C$ and then annealed at $1420^{\circ}C$ for various times. Grain growth was retarded severely by the TiC particles resulting in grain sizes smaller by more than one order of magnitude than those of PSZ without TiC. The fine-grained microstructure lead to doubly-increased fracture strength while maintaining the same level of high fracture toughness as that of conventional Mg-PSZ without TiC particles.

• Journal of Pharmaceutical Investigation
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• 제30권4호
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• pp.267-271
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• 2000

The effect of cyclodextrins on the solubility and stability of aspalatone (acetylsalicylic acid maltol ester, AM, CAS 147249-33-0), which has been recently found to have an antithrombotic effect, was investigated. The addition of ${\beta}-cyclodextrin\;({\beta}-CD),\;dimethyl-{\beta}-cyclodextrin\;(DMCD)\;or\;2-hydroxypropyl-{\beta}-cyclodextrin\;(HPCD)$ to the aqueous solution increased the solubility of AM concentration-dependently. From the phase solubility diagram, stability constants for $AM-{\beta}-CD$, -DMCD or -HPCD complexes were calculated to be 43.1, 78.3 and $53.0\;M^{-1}$. The addition of ${\beta}-CD$, DMCD or HPCD to AM solution retarded the degradation rate of AM in the acidic region. However, ${\beta}-CD$ and HPCD rather acted as an accelerator of degradation in the neutral and alkaline regions. DMCD had a stabilizing effect at all pHs studied.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.63-66
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• 2006

A long term deactivation study was carried out with commercial MEA provided by Hyundai Motor Co. The deactivation phenomena were observed only at high voltage region where there is no diffusion-limited reaction. A rapid deactivation was observed up to 40h owing to the sintering of Pt particles. This was followed a gradual increase in the activity up to 300 h, which is probably caused by improvement in the electrode properties in the presence of current during the reaction. After 300 h, monotonic decrease in the activity was observed owing to dissolution of Pt particles especially in the cathode. The presence oxygen is the cause of oxidation and dissolution of Pt. The dissolution rate can be somewhat retarded by generation of current, which reduces Pt ion back to Pt in the cathode.

• Bulletin of the Korean Chemical Society
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• 제18권2호
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• pp.185-189
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• 1997

The effect of pH and sodium dodecyl sulfate (SDS) micelle on the quenching of Ru(bpy)32+ luminescence by N-alkyl-4,4'-bipyridinium ions (RBPY+: R=methyl, octyl, dodecyl, benzyl) were investigated. In the absence of SDS, the quenching rate at pH 2 is similar to that of the corresponding methylalkyl viologens and much greater than that in pH 8 solution due to greater reducibility of the protonated form of RBPY+ (HRBPY2+). The quenching rate at pH 2 is strongly enhanced by the presence of SDS, while that at basic pH is greatly retarded. These observations are explained by deep embedment of RBPY+ into the hydrophobic hydrocarbon region of the micelle, whereas Ru(bpy)32+ and HRBPY2+ locate in the Stern layer of the micelle.

• Animal Bioscience
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• 제35권7호
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• pp.989-998
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• 2022

Objective: This study investigated the effects of intrauterine growth restriction (IUGR) during late pregnancy on the cell growth, proliferation, and differentiation in ovine fetal thymuses. Methods: Eighteen time-mated Mongolian ewes with singleton fetuses were allocated to three groups at d 90 of pregnancy: restricted group 1 (RG1, 0.18 MJ ME/body weight [BW]^0.75/d, n = 6), restricted group 2 (RG2, 0.33 MJ ME/BW^0.75/d, n = 6) and control group (CG, ad libitum, 0.67 MJ ME/BW^0.75/d, n = 6). Fetuses were recovered at slaughter on d 140. Results: The G0/G1 phase cell number in fetal thymus of the RG1 group was increased but the proliferation index and the expression of proliferating cell nuclear antigen (PCNA) were reduced compared with the CG group (p<0.05). Fetuses in the RG1 group exhibited decreased growth hormone receptor (GHR), insulin-like growth factor 2 receptor (IGF-2R), and their mRNA expressions (p<0.05). For the RG2 fetuses, there were no differences in the proliferation index and PCNA expression (p>0.05), but growth hormone (GH) and the mRNA expression of GHR were lower than those of the CG group (p<0.05). The thymic mRNA expressions of cyclin-dependent protein kinases (CDKs including CDK1, CDK2, and CDK4), CCNE, E2-factors (E2F1, E2F2, and E2F5) were reduced in the RG1 and RG2 groups (p<0.05), and decreased mRNA expressions of E2F4, CCNA, CCNB, and CCND were occurred in the RG1 fetuses (p<0.05). The decreased E-cadherin (E-cad) as a marker for epithelial-mesenchymal transition (EMT) was found in the RG1 and RG2 groups (p<0.05), but the OB-cadherin which is a marker for activated fibroblasts was increased in fetal thymus of the RG1 group (p<0.05). Conclusion: These results indicate that weakened GH/IGF signaling system repressed the cell cycle progression in G0/G1 phase in IUGR fetal thymus, but the switch from reduced E-cad to increased OB-cadherin suggests that transdifferentiation process of EMT associated with fibrogenesis was strengthened. The impaired cell growth, retarded proliferation and modified differentiation were responsible for impaired maturation of IUGR fetal thymus.

• 미생물학회지
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• 제42권3호
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• pp.165-171
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• 2006

ERM protein 은 23S rRNA의 $A_{2058}$에 dimethylation시킴으로써 $MLS_B$계 항생제의 부착을 저해하여 항생제의 활성을 억제하는 내생인자 단백질이다. ERM 단백질의 하나인 ErmSF의 N-말단부위(N-termimal end region, NTER)에 존재하는 1-25번째 아미노산을 함유하는 펩타이드의 활성에서의 역할을 알아보기 위해 이률 제거한 변이 단백질을 표현하는 유전자를 클로닝하고 대장균에서 수용성 단백질로 12.65 mg/L culture의 수율로 대량생산하였다. 이렇게 대량생산된 단백질의 활성을 in vivo와 in vitro에서 확인하였다. 그 결과 in vitro에서 야생형(wild type)의 단백질에 비해 15%의 활성이 감소한 것을 확인하였고 이는 제거된 펩타이드가 기질과 상호작용하여 효소의 활성에 영향을 미친다는 것을 시사하고 있다. 이렇게 감소된 효소의 활성은 생체 내(in vivo) 활성에도 적용되어 처음에는 변이 단백질을 함유하는 세포가 항생제의 작용에 의하여 성장억제를 받지만 시간의 경과와 함께 내성을 회복하여 밤샘 배양하였을 경우는 야생형 단백질을 함유한 세포와 동일한 내성 즉 항생제에 의한 성장억제지역(inhibition zone)을 전혀 나타내지 않는 것으로 밝혀졌다.

• 한국식품영양과학회지
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• 제25권6호
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• pp.932-936
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• 1996

자숙가리비의 shelf-life를 연장하기 위하여 열처리하여 탈각한 가리비를 진공 및 질소가스 포장하여 $5^{\circ}C에$ 저장하면서 여러가지 화학적 및 미생물적 변화를 분석하였다. pH는 저장기간이 증가할수록 감소하였으며 진공 및 질소가스 포장은 저장 18일 이후의 급격 한 pH 감소를 억제하였다. 진공 및 질소가스 포장은 아미노태질소, TMA, VBN, TBA생성 및 미생물 생육 억제효과를 나타내었으며, 두 포장방법 사이에는 뚜렷한 효과 차이는 없었다. 진공 및 질소가스 포장은 $5^{\circ}C에$ 저장된 자숙가리비의 shelf-life를 대조구 30일에 비교하여 약 6일 정도 연장하였다.

• 한국분무공학회지
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• 제14권3호
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• pp.109-116
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• 2009

The purpose of this study is the experimental and numerical investigation on the DME spray characteristics in the combustion chamber according to the injection timing in a common-rail injection system. The visualization system consisted of the high speed camera with metal halide lamp was used for analyzing the spray characteristics such as spray development processes and the spray tip penetration in the free and in-cylinder spray under various ambient pressure. In order to observe the spray characteristics as a function of injection timing, the piston head shape of re-entrant type was created and the fuel injected into the chamber according to various distance between nozzle tip and piston wall in consideration of injection timing. Also, the spray and evaporation characteristics in the cylinder was calculated by using KlVA-3V code for simulating spray development process and spray tip penetration under real engine conditions. It was revealed that the high ambient pressure of 3 MPa was led to delay the spray development and evaporation of DME spray. In addition, injected sprays after BTDC 20 degrees entered the bowl region and the spray at the BTDC 30 degrees was divided into two regions. In the calculated results, the liquefied spray tip penetration and fuel evaporation were shorter and more increased as the injection timing was retarded, respectively.

• 대한구순구개열학회지
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• 제11권1호
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• pp.23-30
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• 2008

From 2001 year, our department has been participated medical charity for cleft lip and palate patients with Japanese team, on general hospital of Quang Nam Province in Tamky, Vietnam. Also we started medical service with student volunteer in Hue University Hospital, sisterhood relationship with Chonbuk National University, from 2006. The central area of Vietnam is a hard fought-field during the Vietnam war, many chemical weapons (defoliant etc.) were used during war. As the mountain region lose currency, this area was still retarded. We would like to introduce the medical charity service of our department and the classification of operated patients and performed operation.