• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.152-159
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• 1999

YBa$_2Cu_3O_{7-{\delta}}$ (YBCO) films grown on CeO$_2$-buffered r-cut sapphire substrates (CbS's) were prepared and their structural and electrical properties were measured. Post-annealed CeO$_2$ films were used as buffer layers for the experiments. It turned out that the YBCO films grown on post-annealed CbS's had the rms roughness of less than 20 ${\AA}$ and peak-to-peak roughness of about 30 ${\AA}$ when the YBCO film thickness was 3000 ${\AA}$. Meanwhile, YBCO films on in-situ grown CeO$_2$ buffer layers on r-cut sapphire substrates appeared to have the peak-to-peak roughness of more than 450 ${\AA}$. X-ray diffraction data revealed that the YBCO flms were epitaxially grown along the c-axis with the typical FWHM of(005) ${\theta}$ -2 ${\theta}$ peak about 0. 16 $^{\circ}$ and ${\Delta}$ ${\omega}$ of the (005) peak about 0.5 $^{\circ}$. T$_c$ > 87 K, ${\Delta}$T < 1 K and R(look)/R(100K) ${\ge}$3 were observed from the YBCO films. Applicability of the YBCO films for high-frequency applications was described.

• KSTLE International Journal
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• 제1권2호
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• pp.113-117
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• 2000

The rotary-vane compressor has become one of the most successful types of compressors because of its mechanical reliability, compactness, and adaptability to moderately high-speed operation in virtually an unlimited range of sizes. However recently, the depletion of the ozone layer due to the current refrigerant(R22) has been getting worse, and it is one of the world's pressing issues. In this paper, we will discuss the use of R410a in the compressor of a room air-conditioner as an alternative refrigerant and air-conditioning system to R22, since R410a has greater refrigerant characteristics than R22. Miniaturization of the rotary compressor for the new refrigerant and air-conditioning system is also possible, which reduces the prime cost of production, hence R410a is naturally a better refrigerant. But to apply the new HFC refrigerant system in refrigeration and air-conditioning systems, a significant redesign of the current refrigerant system is also required, because as the refrigeration changes, lubrication characteristics vary. Close attention must be paid to friction force and energy loss due to friction and wear at many sliding areas.

• Investigative Magnetic Resonance Imaging
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• 제17권1호
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• pp.19-25
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• 2013

목적: 신장 혈중산소치의존 자기공명영상은 신장 산소공급의 평가로 사용되고 있다. 3T 자기공명영상에서 신장의 정상 $R2^*$ 값을 재고, 성별과 위치에 따른 $R2^*$ 값의 차이를 평가하고자 하였다. 대상과 방법: 24명의 건강한 자원자를 대상으로 3.0T 에서 혈중산소치의존 자기공명영상을 시행하였다. $T2^*$ 맵을 생성한 다음에 $R2^*$ 값을 계산하였고, 신피질과 신수질, 남녀 그리고 좌우 신장에 대한 $R2^*$값의 통계적 차이를 평가하였다. 양측 신장 내에서도 위치에 따른 $R2^*$값의 차이도 평가하였다. 결과: 모든 대상에서 혈중산소치의존 자기공명영상은 성공적이었으며, $R2^*$의 측정에 방해되는 인공물은 없었다. 3.0T에서의 평균 $R2^*$는 피질에서 $17.1{\pm}2.60s^{-1}$ 였으며 수질에서는 $27.7{\pm}4.83s^{-1}$ 였다 (p < 0.001). 남자의 수질의 $R2^*$ 값이 여자보다 통계적으로 유의하게 높았으나 (p=0.025), 좌우신이나 신장 내에서의 $R2^*$값의 통계적 차이는 없었다 (p=0.197). 결론: 3.0T에서 신장 혈중산소치의존 자기공명영상은 효과적으로 시행될 수 있었다. 정상인에서 상대적인 신수질의 저산소증이 존재하였고, 이 결과는 병리적인 환경에서 신장 평가에서의 기준치로 사용될 수 있을 것으로 생각된다.

• Molecules and Cells
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• 제37권6호
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• pp.441-448
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• 2014

Inflammasomes are specialized signaling platforms critical for the regulation of innate immune and inflammatory responses. Various NLR family members (i.e., NLRP1, NLRP3, and IPAF) as well as the PYHIN family member AIM2 can form inflammasome complexes. These multiprotein complexes activate inflammatory caspases (i.e., caspase-1) which in turn catalyze the maturation of select pro-inflammatory cytokines, including interleukin (IL)-$1{\beta}$ and IL-18. Activation of the NLRP3 inflammasome typically requires two initiating signals. Toll-like receptor (TLR) and NOD-like receptor (NLR) agonists activate the transcription of pro-inflammatory cytokine genes through an NF-${\kappa}B$-dependent priming signal. Following exposure to extracellular ATP, stimulation of the P2X purinoreceptor-7 ($P2X_7R$), which results in $K^+$ efflux, is required as a second signal for NLRP3 inflammasome formation. Alternative models for NLRP3 activation involve lysosomal destabilization and phagocytic NADPH oxidase and /or mitochondria-dependent reactive oxygen species (ROS) production. In this review we examine regulatory mechanisms that activate the NLRP3 inflammasome pathway. Furthermore, we discuss the potential roles of NLRP3 in metabolic and cognitive diseases, including obesity, type 2 diabetes mellitus, Alzheimer's disease, and major depressive disorder. Novel therapeutics involving inflammasome activation may result in possible clinical applications in the near future.

• 생명과학회지
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• 제20권6호
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• pp.853-860
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• 2010

DevSR two-component system은 Mycobacterium smegmatis의 redox sensing에 관련된 주요한 regulatory system이다. DevSR system은 DevS histidine kinase와 DevR response regulator로 구성되어 있다. 저산소 조건에서 DevS histidine kinase는 활성화되어 DevR response regulator를 인산화 시키고, 인산화된 DevR response regulator는 DevR regulon의 transcriptional activator로 작용한다. DevS의 kinase activity는 DevS의 N-terminal에 위치한 GAF domain에 존재하는 heme의 ligand-binding state에 의해 결정된다. 본 연구에서는 C-terminal kinase domain의 redox-responsive cysteine (C547)이 DevS kinase activity의 redox-dependent control과 연관이 있음을 밝혔다. 산소가 존재할 때, C547 residue 사이의 disulfide bond의 형성은 DevS kinase activity를 불활성화 시킨다. $\beta$-mercaptoethanol과 dithiothreitol과 같은 환원제를 이용하여 산화된 DevS를 환원시켰을 때, DevS kinase activity가 복원된 것이 관찰되었다. 또한, C547을 alanine으로 치환했을 때, M. smegmatis의 DevS의 sensory 기능을 부분적으로 손상되는 것이 complementation 실험을 통해 in vivo 상에서 증명되었다.

• 동의생리병리학회지
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• 제20권6호
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• pp.1507-1515
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• 2006

Angelica gigantis (AG), Rehamaninae Radix(RR), Paenia japonica (PJ), and Polygoni multiflori Radix (PM) have been used as medicinal plants to tonify the blood. General function of the drugs have been known to nourish blood and control the heart and liver meridians. Recently, several studies have proposed mechanisms by which some oriental medicinal herbs work on the immune system. However, it is uncertain whether aqueous-extract of these drugs has immunomodulatory effect yet. In this study, I investigated the immune promotive effects of the water-extracted AG, RR, PJ and PM. The water-extracted AG, RR, PJ and PM inhibited NO production and iNOS expression in LPS stimulated RAW 264.7 macrophage cell line. Among these extracts, AG and PM induced expression of IL-2 and IFN${\gamma}$ in mouse spleen cells. In the flow cytometry analysis, PM-stimulated mouse spleen cells showed an increase in B-cell phenotype (CD45R/B220). The oral administration of Polygoni multiflori water-extracts to mice having S-180 abdominal dropsy cancer prolonged life-span more than control mice. These data suggest that among these extracts, PM has cellular and humoral immune-enhancement effect through IL-2 and IFN${\gamma}$ cytokine production, the regulation of NO production in macrophage cells and the B cell production in spleen cells.

• 한국해양공학회지
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• 제28권5호
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• pp.474-483
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• 2014

The majority of existing WECs (wave energy converters) are designed to achieve maximum power at a resonance condition. In the case of a single WEC, its size must be large enough for tuning, and it has high efficiency only within a limited frequency band. Recently, wave power extraction by deploying many small buoys in a compact array has been studied under the assumption that the buoy's size and separation distance are much smaller than the water depth, wave length, and size of the array. A boundary value problem involving the macro-scale boundary condition on the mean surface covered by an infinite strip of buoys is solved using the eigenfunction expansion method. The energy extraction efficiency (${\varepsilon}=1-R^2_f-T^2_r$), where $R_f$ and $T_r$ are the reflection and transmission coefficients for a strip array of buoys, is assessed for various combinations of packing ratio, strip width, and PTO damping coefficient.

• 대한기계학회논문집B
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• 제27권3호
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• pp.381-388
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• 2003

An experimental study was carried out to measure the heat transfer coefficient in flow boiling to mixtures of HFC-l34a and HCFC-123 in a uniformly heated horizontal tube. Tests were run at a pressure of 0.6 MPa and in the ranges of heat flux 1-50 kw/$m^2$, vapor quality 0-100 % and mass velocity 150-600 kg/$m^2$s. Heat transfer coefficients of mixture were less than the interpolated values between pure fluids both in the low quality region where the nucleate boiling is dominant and in the high quality region where the convective evaporation is dominant. Measured data of heat transfer are compared to a few available correlations proposed for mixtures. The correlation of Jung et. al. satisfactorily predicted the present data, but the data in lower quality was overpredicted and underpredicted the high quality data. The correlation of Kandlikar considerably underpredicted most of the data. and showed the mean deviation of 35.1%.

• 한국강구조학회 논문집
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• 제25권5호
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• pp.579-585
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• 2013

본 연구에서는 매개변수해석을 통하여 횡력에 의한 강관의 전달좌굴응력에 대해 분석을 하였다. 비선형좌굴에 의한 전단좌굴응력을 산정하기 위해 ABAQUS의 상세 쉘 모델을 적용한 유한요소해석을 수행하였으며, 매개변수로는 강종, 두께, 반지름 그리고 길이를 선택하였다. 해석대상 강종은 STK400, STK490, SM570이며, 강재의 두께는 2mm, 40mm로 하였고 반지름과 부께의 비(R/t)는 20~200, 길이와 반지름의 비(L/R)는 1~3이 되도록 하였다. 모든 강종에서 R/t이 20에서 200으로 변화하였을 때 전단좌굴응력은 감소하였고, 저강도 강재보다 고강도 강재일수록 R/t의 변화에 민감하며, 전단좌굴응력에 미치는 영향도 커지는 것으로 나타났다. 또한 L/R이 증가할수록 전단좌굴강도가 작아지는 것으로 보아 강관의 길이가 길수록 전단좌굴에 취약하다는 것을 알 수 있다.

• 대한화장품학회지
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• 제40권3호
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• pp.297-305
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• 2014

홍삼(Red Ginseng; RG)은 인삼보다 더 높은 생체 흡수율과 다양한 약리효과를 갖는 특이한 진세노사이드(Rg2, Rg3)를 함유하고 있다. 따라서 오랫동안 많은 사람들의 건강을 위해 이용되어 왔다. 또한 발효는 유효한 생리활성을 갖는 저분자의 물질들을 생성하기 때문에 많은 연구자들이 생물학적 활성에 대해 오랫동안 연구해오고 있다. 본 연구에서는 홍삼을 붉은덕다리버섯 균사체로 7일 동안 발효하였다. HPLC 분석 결과 진세노사이드 Rg1, Re 및 Rb2가 각각 0.24, 0.25, 0.16 mg/g에서 0.12, 0.1, 0.03 mg/g으로 함량 감소를 확인하였고, 홍삼 붉은덕다리 균사체배양액(Fermented Red Ginseng; FRG)의 항염, 세포 이동, 항산화, 콜라겐 타입 I 합성과 MMP-1 억제효능에 대한 생물학적 효능을 확인하였다. 그 결과, FRG는 RG보다 항염 및 cell migration 촉진효과가 더 우수하였다. FRG는 LPS로 유도된 RAW 264.7 대식세포의 NO 생성을 억제하였으며, iNOS와 IL-6의 발현을 mRNA 수준에서 억제하였다. 이 결과로 FRG는 새로운 항염소재로서 제안이 가능하다고 사료된다.