• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.311-314
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• 2006

This paper concerns about total dynamic analysis of integrated mining system. This system consists of vertical steel pipe, intermediate buffer station, flexible pipe and self-propelled miner. The self-propelled miner and buffer are assumed as rigid-body of 6-dof. Discrete models of vertical steel pipe and flexible pipe are adopted, which are obtained by means of lumped-parameter method. The motion of mining vessel is not considered. Instead, the motion of mining vessel is taken into account in form of various boundary conditions (e.g. forced excitation in slow motion and/or fast oscillation and so on). A terramechanics model of extremely soft cohesive soil is applied to the self-propelled miner. The hydrodynamic forces and moments are included in the dynamic models of vehicle and lifting pipe system. Hinged and fixed constraints are used to define the connections between sub-systems (vertical steel pipe, buffer, flexible pipe, miner). Equations of motion of the coupled model are derived with respect to the each local coordinates system. Four Euler parameters are used to express the orientations of the sub-systems. To solve the equations of motion of the total dynamic model, an incremental-iterative formulation is employed. Newmark-b method is used for time-domain integration. The total dynamic responses of integrated mining system are investigated.

• 한국세라믹학회지
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• 제31권5호
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• pp.572-580
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• 1994

With low thermal expansion coefficients, eucryptite (Li2O.Al2O3.2SiO2) and spodumene (Li2O.Al2O3.4SiO2) in LAS ceramic system show good thermal shock resistance. In this study, sillimanite or kaolin group silicate minerals and Li2CO3 were used as starting materials, and if necessary SiO2 or Al2O3 were added for making stoichiometrically formed specimens. By this process, eucryptite powders were synthesized and characterized. The powder mixtures of lithiumcabonate and silicate minerals calcined at 80$0^{\circ}C$ for 2 hrs were made into powder compacts. $\beta$-Eucryptite single phase was formed via intermediate phases of Li2SiO3 and LiAlO2 et al, by heating at 110$0^{\circ}C$ or 120$0^{\circ}C$ for 10 hrs from those powder compacts. When using the sillimanite group minerals, Virginia kyanite or andalusite was reacted to form eucryptite at 120$0^{\circ}C$and CMK International kyanite were completed at 110$0^{\circ}C$. When kaolin group minerals were used, it was found that the synthesizing temperature (100$0^{\circ}C$) of $\beta$-eucryptite from the mixture of New Zealand white kaolin was lower than that from Hadong pink kaolin (110$0^{\circ}C$). The Microstructure of systhesized powder showed the irregular lump shape such as densed crystallines.

• 대한치과기공학회지
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• 제27권1호
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• pp.97-104
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• 2005

The effect of Nb on interfacial bonding characteristics of Ni-Cr alloy for porcelain fused to metal crown (PFM) has been studied in order to investigate oxide layer. A specimens, which is 0.8mm in thickness, were fired at 1,000$^{\circ}C$ with four tests such as air, vacuum, air for 5 minutes and vacuum for 5 minutes in order to examine an oxide behavior of alloy surface generated by the adding of Nb to be controlled at a rate of 0, 1, 3 and 5. It observed oxide film form of the fired specimens with optical microscope and scanning electron microscope (SEM), and chemical formation of them with energy disperse X-ray spectroscopy (EDX). The other specimens, which is 2mm in thickness, were fired at 1,000$^{\circ}C$ with air and vacuum in order to analyze the diffusion behaviors of alloy-porcelain interface by X-ray dot mapping. The results of this study were as follows: 1. The observation of microstructure of specimens by SEM showed that the more Nb content is high, the more much intermediate compound of rich Nb is observed. 2. The surface morphology of oxide film is most dense in 3% Nb. The heat treatment in air constitutes denser oxide film than heat treatment under vacuum. 3. The diffusion behavior of oxide layer by X-ray dot mapping showed that Si, Al of porcelain diffuse toward metal.

• 한국전자파학회논문지
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• 제22권8호
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• pp.797-804
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• 2011

무선 애드 혹(ad hoc) 네트워크에서 전송 효율을 향상시킬 수 있는 방법으로 네트워크 코딩(network coding)이 많은 주목을 받고 있다. 본 논문에서는 IEEE 802.11 무선 랜에 네트워크 코딩을 적용하였을 때, 수율(throughput) 성능을 예측할 수 있는 분석 모델을 제안하고자 한다. 이 모델에서는 모든 무선 노드들이 선형 토폴로지(topology)로 네트워크를 구성하고 있고, 양단에 위치한 두 개의 소스 노드들이 패킷을 발생시키고, 중간 노드들은 네트워크 코딩을 수행하면서 패킷을 전달하는 역할을 하게 된다. 제안하는 분석 모델은 궁극적으로 각 노드별수율의 비선형 방정식 형태로 귀결되며, 이 방정식의 해를 통해서 단대단(end-to-end) 수율을 계산하게 된다. 본 논문에서 제안한 분석 모델의 정확성을 검증하기 위하여, 다양한 모의 실험을 수행하였으며, 분석 모델을 통한 수율 예측치가 시뮬레이션 결과와 상당히 일치함을 확인할 수 있었다.

• 한국수산과학회지
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• 제25권6호
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• pp.501-510
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• 1992

정어리표피 중에 존재하는 지방산화촉진물질의 검색확인 및 그 특성구명을 시도하였다 정어리표피중의 산화촉진물질은 0.05M 인산염 완충액으로 거의 모두 추출되었고, 이 조추출액에 대해 Sephadex G-200, DEAE-Sephadex A-50 및 CM-Sephadex A-50 등으로 연속적인 분리를 행하였다. 정어리표피 중의 주 산화촉진물질은 열에 극히 불안정하고, 지방산화촉진의 최적 작용 pH가 7이며, 특징적인 Sohret흡수를 나타내는 점등으로부터 햄을 가진 효소임을 알 쑤 있었다. 특히 이들은 기질인 유리 및 에스테르화 리놀산에 모두 잘 작용하여 빠른 속도로 공역과산화물을 형성하였다. 이상의 결과로부터 정어리표피 중의 주 지방산화촉진물의 본태는 새로운 형태의 리폭시지네이스유사 효소인 것으로 추정되었다.

• The Korean Journal of Physiology and Pharmacology
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• 제1권3호
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• pp.285-296
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• 1997

Injury to brain transforms resting astrocytes to their reactive form, the hallmark of which is an increase in glial fibrillary acidic protein (GFAP), the major intermediate filament protein of their cell type. The overall glial response after brain injury is referred to as reactive gliosis. Glial-neuronal interaction is important for neuronal migration, neurite outgrowth and axonal guidance during ontogenic development. Although much attention has been given to glial regulation of neuronal development and regeneration, evidences also suggest a neuronal influence on glial cell differentiation, maturation and function. The aim of the present study was to analyze the effects of glial-hippocampal neuronal co-culture on GFAP expression in the co-cultured astrocytes. The following antibodies were used for double immunostaining chemistry; mouse monoclonal antibodies for confirm neuronal cells, rabbit anti GFAP antibodies for confirm astrocytes. Primary cultured astrocytes showed the typical flat polygonal morphology in culture and expressed strong GFAP and vimentin. Co-cultured hippocampal neurons on astrocytes had phase bright cell body and well branched neurites. About half of co-cultured astrocytes expressed negative or weak GFAP and vimentin. After 2 hour glutamate (0.5 mM) exposure of glial-neuronal co-culture, neuronal cells lost their neurites and most of astrocytes expressed strong CFAE and vimentin. In Western blot analysis, total GFAP and vimentin contents in co-cultured astrocytes were lower than those of primary cultured astrocytes. After glutamate exposure of glial-neuronal co-culture, GFAP and vimentin contents in astrocytes were increased to the level of primary cultured astrocytes. These results suggest that neuronal cell decrease GFAP expression in co-cultured astrocytes and hippocampal neuronal-glial co-culture can be used as a reactive gliosis model in vitro for studying GFAP expression of astrocytes.

• 환경생물
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• 제18권3호
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• pp.347-353
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• 2000

금강 수계에서 식물플랑크톤 현존량 변화를 알기 위하여 현도, 마암, 장암, 나포에서 1998년 10월부터 1999년 9월까지 매월 1회 채수하여 식물플랑크톤 현존량을 조사하였다. 식물플랑크톤 현존량은 현도에서 7월에 $39.5{\times}10^3cells ml^{-1}, 마암에서 7월에 112.1{\times}10^3cells ml^{-1}, 장암에서 7월에 125.5{\times}10^3cells ml^{-1}, 나포에서 8월에 288.6{\times}10^3cells ml^{-1}로 최대였으며, 현도와 마암에서는 대부분의 시기에 5.0{\times}10^3Cells ml^{-1}이하였고, 나포에서는 5.0{\times}10^3Cells ml^{-1}$ 이상이었으며, 장암은 그 중간이었다. 각 조사 정점의 현존량은 마암이 현도보다 3배 이상 높았고, 장암이 마암보다 1.3배, 나포는 장암보다 2.1배 높아서, 중류에서 하류로 갈수록 급격하게 증가하였다. 현존량 조사 시점에 따라 차이가 있어서 봄부터 초여름까지는 장암의 현존량이 최대였고, 다른 계절에는 나포에서 가장 높았다. 현존량의 시공 분포 변화는 중심형의 소형 규조류 Cyclotella spp.와 Stephanodiscus spp. 및 사상 규조류 Aulacoseira spp.의 번무에 기인하였다.

• 한국환경복원기술학회지
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• 제16권3호
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• pp.83-95
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• 2013

To understand natural regeneration and stand development after fire in mixed broadleaved-coniferous forests of Sikhote-Alin Mountains, ten sample plots of $50m{\times}50m$ size were established in 1975 and 1983 at the stands burned by wildfires in 1973 and 1982, respectively. And, the number of naturally regenerated seedlings were monitored in two $50m{\times}4m$ subplots in each plot. The most fire-sensitive conifer species is Abies nephrolepis, while Betula costata is the most fire-sensitive broadleaved tree species. The most fire-resistant species were Q. mongolica, T. taquetii and A. mono. The results of 20 and 30 years after the fire showed that pioneer tree species, e.g. Populus, Salix, and Betula, were regenerated immediately at the early stage of stand development and grew where there is a mono canopy layer with high density. On the other hand, the densities of successors, e.g. Pinus koraiensis, Picea jezoensis, Abies nephrolepis, Acer mono and Tilia taquetii, which were present in the study plots before the fire, increased gradually. Naturally regenerated tree species after forest fire by the growth rate were divided into three groups according to their annual height growth. The seral tree species (Betula costata, Betula platyphylla, Padus maackii, Populus tremula and Sarix caprea) belong to the first group and have the highest growth rate (from 40 to 96 cm per year). The late successional broad-leaved trees (Tilia taquetii, Acer mono and Quercus mongolica) belong to the second group and have intermediate annual height growth (from 3.7 to 13.5 cm per year). The late successional coniferous species (Picea jezoensis, Pinus koraiensis and Abies nephrolepis) form the third group and have the least annual height growth (from 1.4 to 3.5 cm per year).

• 공업화학
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• 제3권4호
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• pp.686-693
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• 1992

주성분이 heazlewoodite와 ferronickel로 구성된 니켈 matte로 부터 니켈의 용해를 지배하는 메카니즘을 규명하기 위해서, 염산용액에서 침출실험을 수행하였다. 실험온도 범위는 $50-90^{\circ}C$ 이고, 입자의 크기는 $100-160{\mu}m$와 $400-500{\mu}m$이며, 산농도는 0.5-3.ON 이었다. Heazlewoodite의 용해속도는 ferronickel 보다 휠씬 빨랐으며, 2성분이 각각 다른 반응속도로 동시에 용해하였다. 본 실험범위에서는 중간체인 NiS가 생성되지 않았지만, 반응용액이 $H_2S$로 포화되면 입자표면에 NiS의 얇은 막이 생성될 가능성을 배제할 수 없다. 반응초기의 활성화 에너지는 약 10kca1/g mol 이었고, 용해반응은 입자표면에서 진행되어 시간이 경과함에 따라 입자의 크기가 감소하였으며, 니켈의 용해속도가 1.0N 까지는 염산농도에 비례하였다.

• 한국수의병리학회지
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• 제6권1호
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• pp.41-48
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• 2002

Oval cell is considered as facultative precursor cells for both hepatocytes and biliary cells, as well as origin of hepatocellar and cholangiocellular carcinoma (CCC) during carcinogenesis or toxic liver injury. To clarify the cellular origin or differentiation of cholagiocarcinogensis, the fate of carcinogen-induced oval cells was pathologically and phenotypically chased in Syrian golden hamster liver after Clonorchis sinensis (CS) infection which would give rise to a promoting effect. Two week treatment of hamsters with 0.005% diethylnitrosamine (DEN) followed by 2 week treatment of 1% 2-acetylaminofluorene (AAF) under choline deficient diet resulted in massive proliferation of BrdU labeleed and PCNA positive oval cells showing various distinct morphology, histochemical and immunohistochemical phenotypes for GGT, cytokeratin 19 and OV-6. Oval cells also frequently form ductular-like structures or phenotypically show hepatocyte-like characteristics. After CS infection, the oval cells showed sequential morphological changes to atypicl proliferating bile ductules and all hamsters thereafter developed well differentiated and anaplastic CCC at 16 week after CS infection. In electron microscopy, some bile ductules were constructed by intermediate oval cells and bile ductular cells surrounded by basement membrane. The results of this study strongly suggest that CCC developed in the present study were originated from hepatic stem-like oval cells, supporting the theory of stem cell origin of cancers. In addition, this hamster model would be valuable for the molecular mechanistic study during chemical-triggered cholangiocarcinogenesis.