• 한국의학물리학회지:의학물리
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• 제19권2호
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• pp.113-119
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• 2008

본 연구에서는 6종에 대한 RTP의 실험 결과에 대하여 오차를 평가하고 AAPM Report-62의 평가 항목에 적용하여 RTP 오차의 허용범위 여부를 조사하였다. 이를 위하여 NDR (Normalized dose rate) 개념을 도입하여 RTP 계산값과 측정값을 동일한 기준으로 비교할 수 있도록 하였다. 평가결과 대부분의 RTP들은 차폐조사면과 불균질 물질의 계산에서 허용범위 이내의 오차를 보였으나 표면 불균일성에 대해서는 대부분 허용범위를 초과하는 것으로 나타났다.

• 대한기계학회논문집B
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• 제25권4호
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• pp.583-592
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• 2001

The combustion characteristics of the hybrid catalytic(catalytic+thermal) combustor with a lean methane-air mixture on platinum catalyst were investigated numerically using a 2-D boundary layer model with detailed homogeneous and heterogeneous chemistries. for the more accurate calculations, the actual surface site density of monolith coated with platinum was decided by the comparison with experimental data. It was found that the homogeneous reactions in the monolith had little effect on the change of temperature profile, methane conversion rate and light off location. However, the radicals such as OH and CO were produced rapidly at exit by homogeneous reactions. The effect of operation conditions such as equivalence ratio, temperature, velocity, pressure and diameter of the monolith channel at the entrance were studied. In thermal combustor, the production of N$_2$O was more dominant than that of NO due to the relative importance of the reaction N$_2$+O(+M)→N$_2$O(+M). Finally the productions of CO and NOx by amount of methane addition were studied.

• Mycobiology
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• 제29권1호
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• pp.15-18
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• 2001

Protoplast fusion is a useful technique for establishing fungal hybrids to overcome the natural barriers. The ultrastructure of protoplast and its fusion process were observed using a scanning electron microscopy(SEM) and a transmission electron microscopy(TEM). The protoplasts were variable in size from $0.5{\sim}15{\mu}m$ in diameter, and the mean diameter was about $3{\sim}5{\mu}m$. It was impossible to discriminate protoplasts of Lentinula edodes from protoplasts of Coriolus versicolor by size and surface structure. Big aggregates of the dehydrated protoplasts were observed, after polyethylene glycol 4000 treatment. Nucleus, mitochondria, lipid granules and various vesicles having granules were scattered in the cytoplasm. The vesicles were heterogeneous in size and vary from one protoplast to another. The fused membrane layer of the two protoplasts was observed. Time protoplast membrane contact and reorganization of membrane components were essential condition for protoplast fusion. Transmission electron micrograph showed fused protoplasts and flattening of the cells in the area of the membrane contact. We hope that our electron microscopic observations provide some insights into the understanding of the fusion process of protoplast in fungi.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1989년도 춘계학술대회
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• pp.7-8
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• 1989

The graft copolymer of chitosan with amino acid, L-lysine was synthesized by heterogeneous copolymerization and was evaluated as an artificial skin. The mechanical properties under dry and wet state, water content, water vapor transmittance rate and biodegradability were measured. The tensile strength and elongation under wet state ranged $0.3-0.5\;kg/mm^2$, 10-13%, respectively. Water vapor transmittance rate ranged $450-500\;g/m^2{\cdot}day$ like that of the normal skin. The weight loss of prepared membrane by protease IV was measured for the degree of biodegradation. The degree of biodegradation was around 15% and after 4 days it was slow. Biocompatibility was evaluated by studying the attachment of human fibroblast on the prepared membrane surface.

• Journal of Microbiology
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• 제39권4호
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• pp.293-299
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• 2001

The nucleocapsid(NP) protein of Newcastle disease virus (NDV) and its derivative (NP$\sub$cfus)containing the myc region and six histidine residues fused to its C-terminus were pcpressed aboundantly in Escherichia coli. The proteins were purified by sucrose gradient centrifugation. Both the NP and NP$\sub$cfus/ proteins self-assem- bled into ring-like particles stacked together to from nucleocapsid-like structure which are heterogeneous in length with a diameter of 20${\pm}$2 nm and central holow of 5${\pm}$1 nm. Only a very small amount of the monomers in the particles was linked by inter-molecular disulfide bonds. Fusion of the C-terminal end to 29 amino acids inclusive of the myc epitope and His tag did not impair ring assembly buy inhibited the formation of the long herringbone structures. Immunogold lableing of the particles with the anti-myc antibody showed that the C-terminus of the NP$\sub$cfus/ protein is exposed on the surface of these ring-like particles.

• 한국세라믹학회지
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• 제26권6호
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• pp.737-746
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• 1989

After Ba-ferrite powders synthesized hydrothermally and its heated powders were dissolved partially with HCl treatment time, the BaO/Fe2O3 mole ratio of dissolved solutions and powders were measured by AAS, also, lattice constants, particle morphology and magnetic properties in HCl treated, heated and no-heated Ba-ferrite powders were abtained by means of XRD, SEM and VSM, respectively. From above analysis results, the effect of Ba/Fe mole ration in suspension(as starting material) on the BaO/Fe2O3 composition and particle characteristics of products were investigated, and the effect of heat treatment on magnetic properties of products examined. The composition, lattice constant and crystal phase of products depend on the Ba/Fe mole ratio in suspension. Ba content in surface or outer part of Ba-ferrite powder is higher than inner and heterogeneous, and the excess Ba ions in the inner part of particle move into the outer by heating, so that the mole ratio of BaO/Fe2O3 in the more jinner approaches more to the stoichiometric composition 1 : 6. The crystallinity, coercivity and saturation magnetization of products are increased by heat treatment, and the heat-treated samples synthesized hydrothermally in lower temperature are appreciated to have better powder characteristics.

• Nuclear Engineering and Technology
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• 제24권3호
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• pp.252-262
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• 1992

시간 및 공간 종속형 중성자 수송 방정식으로부터 비균질 원자로 노심해석의 효율적인 방법을 개발하였다. 이를 위해 계산 시간을 단축하고 각 집합체 크기의 소격격자(coarse mesh)에 대한 평균 중성자속을 정확히 예측할 수 있도록 노달방법(nodal method)을 도입하였고, 노드 별 평균 중성자속과 노드 각 경계면의 평균 중성자속 및 유속(flux and current)과의 관계식을 얻기 위하여 조정 인자( correction factor)로서 불연속인자(discontinuity factor)를 사용하였으며, 이 인자는 이전 시간대(previous time step)의 노드 평균 중성자속, 확산계수, 그리고 불연속인자 등에 따라 새로이 계산(updating)된다. 본 논문에서 개발된 방법을 시간에 따라 비교적 단순히 변하는 과도 노심(TWIGL)과 급격한 중성자 거동의 변화를 모사하는 과도 노심(LRA)에 적용한 결과 정확성 및 효율성이 입증되었 다.

• 한국조경학회지
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• 제18권1호
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• pp.41-51
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• 1990

This study was executed to investigate the vegetation structure and to propose the vegetation management proposals of the Sansung Nature Park at Cheonju City and the results were as fellows. 1. A damage of vegetation and soil surface around the Namgosa was taken place up to 100m by picnic 2. Pinus rigida forest covered 36.1% of the total area(152.6ha) and total afforested vegetation covered 43.5%, respectively. P. denstflora comm. covered 28.4% arid Carpinus laxiflora Comm. as a climax vegetation in temerate zone covered 0.3%, respectively. 3. 6, 7 and 8 of the degree of human disturbance of vegetation covered 45.3%, 26.6% and 21.4%, respectively and resulted in low quality of naturalness. 4. Physical and chemical properties of soil were pour at high elevation and were poor severely in and around the Namgosa due to human disturbance. 5. Plant community were under rapid succession and had unvalanced structure and heterogeneous composition of species. Rapid vegetational succession from Pinus densiflora and Pf. rigida to Carpinus laxifora, Quercus spp. and Robinina pseudo-acacia were taken place.6. The speeies of Raunkiaer's frequency class I as of high frequency class were Pinus dunsiflora, Carpinus alxiflora, Quercus mmongolica, Sorbus alnifolia, Prunrs sargintii, Rhododendron yedoense, Stephanandra incisa and Lespedeza maxinowiczii. 7. Vegetational management proposals were made for three vegetation zones ; Historic landscape restoration and preservation zone, Afforested vegetation zone, Native vegetation conservation zone and recommanded native species for landcape planting.

• BMB Reports
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• 제49권1호
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• pp.11-17
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• 2016

The gastrointestinal tract forms the largest surface in our body with constantly being exposed to various antigens, which provides unique microenvironment for the immune system in the intestine. Accordingly, the gut epithelium harbors the most T lymphocytes in the body as intraepithelial lymphocytes (IELs), which are phenotypically and functionally heterogeneous populations, distinct from the conventional mature T cells in the periphery. IELs arise either from pre-committed thymic precursors (natural IELs) or from conventional CD4 or CD8αβ T cells in response to peripheral antigens (induced IELs), both of which commonly express CD8α homodimers (CD8αα). Although lineage commitment to either conventional CD4 T helper (Th) or cytotoxic CD8αβ T cells as well as their respective co-receptor expression are mutually exclusive and irreversible process, CD4 T cells can be redirected to the CD8 IELs with high cytolytic activity upon migration to the gut epithelium. Recent reports show that master transcription factors for CD4 and CD8 T cells, ThPOK (Th-inducing BTB/POZ-Kruppel-like factor) and Runx3 (Runt related transcription factor 3), respectively, are the key regulators for re-programming of CD4 T cells to CD8 lineage in the intestinal epithelium. This review will focus on the unique differentiation process of IELs, particularly lineage re-commitment of CD4 IELs. [BMB Reports 2016; 49(1): 11-17]

• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.4015-4022
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• 2012

Manganese(III) 5-(4-carboxyphenyl)-10,15,20-triphenyl porphyrin chloride (Mn(TCPP)Cl) was grafted through amide bond on silica zeolite Y (HY), zeolite beta ($H{\beta}$) and hexagonal mesoporous silica (HMS). XRD, ICP-AES, $N_2$ physisorption, SEM, TEM, FTIR and thermal analysis were employed to analyse these novel heterogeneous materials. These silica supported catalysts were shown to be used for epoxidation and good shape selectivity was observed. The effect of support structure on catalytic performance was also discussed. The catalytic activity remained when the catalysts were recycled five times. The energy changes about epoxidation of alkenes by $NaIO_4$ and $H_2O_2$ were also computationally calculated to explain the different catalytic efficiency.