• Journal of Advanced Marine Engineering and Technology
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• v.29 no.4
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• pp.417-425
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• 2005

An experimental study is performed on the turbulent swirling flow behind a crcular cylinder using 2-D PIV technique. The Reynolds numbers investigated are 10.000, 15,000. 20.000 and 25.000. The mean velocity vector, time mean axial velocity, turbulence intensity, kinetic energy and Reynolds shear stress behind the cylinder are measured before and behind the cylinder along the test tube. A comparison is included without swirling flow behind a circular and square cylinder. The recirculation zones are shown unsymmetric profiles.

• Journal of Korean Society of Forest Science
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• v.50 no.1
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• pp.25-28
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• 1980

The purpose of the this study was to compare the torlent tree to drought among the Pinus koraiensis, Abies holophylla, and Ginkgo biloba. The water relations parameters of leafy shoots were measured by the Pressure chamber technique from August 10 to September 4 in 1980. On the water relations parameters such as original osmotic pressure(${\pi}_0$), osmotic pressure(${\pi}_p$) and relative water content (RWC) at incipient plasmolysis, and Vp/Vo ratio of the volume of osmotic water (Vp) at incipient plasmolysis to total symplasmic water (Vo) basis, the Abies holophylla shoots showed ontogenetically a superior osmoregulation which are closely associated with drought resistance compared with Pinus koraiensis, and the Ginkgo biloba shoots showed the heighest among these three species.

• Korean Journal Plant Pathology
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• v.2 no.3
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• pp.185-192
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• 1986

Upon germination, a conidium was septated in accordance with number of germ tubes. The percentages of ppressorial formation were not different between the resistant cultivars (Kumchang NO. 2 and Hongilpum) and the susceptible cultivars (Haneulcho and Saegochu). Appressorial form was various such as round, elliptic or star-shapped. The maximum number of appressoria was shown at 12 hours after inoculation. By 24 hours fter inoculation, hypersensitive tiny brown lesions were observed on the leaves and fruits of the resistant cultivars. Epidermal cells under cuticle layer of the resistant Kumchang NO. 2 fruit showed severe plasmolysis, while on the susceptible cultivars, the lession was largely extended to following incubation. Subcuticular infection hyphae were profusely colonized in the disintegrated tissues. Acervuli and setae on the stromatic structure ere formed at 96 hours. The infected seed coat was not only severely collapsed, but also infection hyphae were observed on the disintegrated seed coat, resulting severe plasmolysis of nucellus and embryo.

• Applied Microscopy
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• v.31 no.4
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• pp.367-374
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• 2001

Leaves of two developmental stages of Salsola species, young and mature, were examined to reveal the structural and functional relationships in the photosynthetic tissue using anatomical and ultrastructural criteria. Both young and mature leaves had Kranz anatomy of the Salsolid type with two layers of chlorenchyma on the leaf periphery: an outer layer of palisade mesophyll cells and an inner layer of compact bundle sheath cells with centripetally arranged organelles. The chlorenchyma was continuous in young leaves , while it was discontinuous in mature leaves. The main vascular bundle occupied the central position in the leaf. but the small peripheral vascular bundles were in contact with the chlorenchyma. Structural dimorphism of chloroplasts was obvious in bundle sheath cells of mature leaves exhibiting noticeable grana reduction, whereas mesophyll cell chloroplasts had well developed grana in all cases. Plasmodesmata were less numerous and rather simple in young leaves relative to well-developed secondary plasmodesmata of the later stage. According to the current data, features of two stages of Salsola leaves corresponded to NADP-ME bio-chemical subtype on the basis of photosynthetic cell ultrastructure. Implications of developing such anatomical and ultrastructural data of Sulsola species and biochemical characteristics reported in other C-4 species have been discussed.

• Journal of Korean Society of Steel Construction
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• v.13 no.1
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• pp.71-79
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• 2001

The concrete filled tubular(CFT) columns have many excellent structural properites. such as high compressive strength high ductility and high absorption capacity However the confinement effect and limiting width-thickness ratio of CFT column have not yet been clarified. Therefore. this paper aims to clarify the confinement effect of steel tubes and strength of concrete filled steel tubular columns. And this paper presents results of a probabilistic analysis based on statistical data for strength of concrete filled steel tubular columns which has been tested in Korea for recent 10 years(1991.1~2000.6).

• Journal of Conservation Science
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• v.29 no.1
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• pp.15-24
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• 2013

Chil-sa head-wear excavated in Buksandong of Ulsan is precious relic with historical, cultural, social and artistic values because it shows head-wear shape at the period of Goryeo dynasty with the invaluable worth in the field of Korean traditional costumes. Also, this excavated head-wear provides the empirical information about Goryeo dynasty which has relatively insufficient remains. The purposes of this study are to recover and maintain the original states of the artifacts from various environmental factors and then to preserve the materials from rapid decomposition. As a result, the original shape of the head-wear from Goryeo dynasty can be conserved and through the material and structure analysis it is found out that the head-wear's surface structure is composed of silk(紗) and the ground structure is made by bamboo(竹絲).

• Korean Journal of Veterinary Research
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• v.26 no.2
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• pp.301-305
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• 1986

Enterovirus 감염증시(感染症時) dexamethasone이 미치는 영향(影響)을 알아보기 위하여 초유(初乳)를 먹지 않은 1일령(日齡) 자돈(仔豚) enterovirus를 경구감염(經口感染)시키고 dexamethasone을 근육주사(筋肉注射)한 후 임상(臨床) 및 병리조직학적(病理組織學的)으로 관찰(觀察)하였던 바 다음과 같은 결과(結果)를 얻었다. 임상적(臨床的)으로는 dexamethasone을 투여(投與)한 자돈(仔豚)에서 감염후(感染後) 3일(日)째 체온(體溫)의 상승(上昇), 4일(日)째 보행실조(步行失調) 그리고 8일(日)째 횡와(橫臥)한 반면(反面) enterovirus만을 감염(感染)시킨 대조군(對照群)은 감염후(感染後) 7일(日)째 체온(體溫)의 상승(上昇), 14일(日)째 보행실조(步行失調)가 확인(認定)되었다. 병리조직학적(病理組織學的) 소견(所見)으로는 중추신경계(中樞神經系) 전반(全般)에 걸쳐 수막하(髓膜下) 원형세포(圓形細胞)의 침윤(侵潤), 혈관주위(血管周圍) 원형세포(圓形細胞)의 침윤(侵潤), 미만성(彌漫性) 또는 한국성(限局性) gliosis, 신경세포(神經細胞)의 퇴행성(退行性) 변화(變化)가 관찰(觀察)되었고, 특히 대뇌(大腦) 제(第)3뇌실부(腦室部)와 중뇌수도(中腦水道), 제(第)4뇌실(腦室) 및 척수(脊髓)의 중심관(中心管) 주변부(周邊部)에서 glia 세포(細胞)의 침윤(侵潤)이 현저(顯著)하였으며, 병변(病變)의 정도(程度)는 enterovirus만을 감염(感染)시킨 대조군(對照群)에 비해 dexamethasone을 투여(投與)한 자돈(仔豚)에서 훨씬 심하게 나타난 점으로 보아 dexamethasone 투여(投與)는 자돈(仔豚)의 enterovirus 감염증(感染症)을 촉진(促進)시킬 수 있는 한 유인(誘因)으로 간주(看做)된다.

• Journal of Convergence for Information Technology
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• v.9 no.8
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• pp.155-163
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• 2019

Laminar mixed convection of a nanofluid consists of water and $Al_2O_3$ in a horizontal circular tube has been studied numerically. Two-phase mixture model has been used to investigate hydrodynamic and thermal behaviors of the nanofluid with variables physical properties. Three dimensional Navier-Stokes, energy and volume fraction equations have been discretized using the finite volume method. The Brownian motions of nanoparticles have been considered to determine the thermal conductivity and dynamic viscosity of $Al_2O_3$-Water nanofluid, which depend on temperature. The calculated results show good agreement with the previous numerical data. Results show that in a given Reynolds number (Re), increasing solid nanoparticles volume fraction and Richardson number (Ri) increases the convective heat transfer coefficient and wall shear stress.

• Journal of Convergence for Information Technology
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• v.12 no.3
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• pp.141-150
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• 2022

Fluid flow and thermal characteristics of laminar nanofluid(water/Al2O3) flow in a circular U-bend tube have been studied numerically. In this study, the effect of Reynolds number and the solid volume fraction and the impact of the U-bend on the flow field, the heat transfer and pressure drop was investigated. Comparisons with previously published experimental works on horizontal curved tubes show good agreements between the results. Heat transfer coefficient increases by increasing the solid volume fraction of nanoparticles as well as Reynolds number. Also, the presence of the secondary flow in the curve plays a key role in increasing the average heat transfer coefficient. However, the pressure drop curve increases significantly in the tubes with the increase in nanoparticles volume fraction.

• Applied Microscopy
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• v.30 no.1
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• pp.89-100
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• 2000

We observed the salivary ducts of two species of snails, Achatina fulica and Incilaria fruhstoferi with an electron microscope, and obtained the following results. The intralobular and interlobular ducts of Achatina fulica assume the forms of round or ellipsoidal doughnuts. The boundaries between the endothelial cells are not clear. It is also found that the cytoplasm of the endothelial cells consists of the membrane infolded in interdigital form, and there are well -developed microvilli at the apical portion of the cytoplasm. On the other hand, the intralobular and interlobular ducts of Incilaria fruhtoferi consist of the irregular simple columnar epithelia. The high electron dense cytoplasm is filled with the irregular round granules. The microvilli at the apical portion of the cytoplasm are not so well-developed as those in Achatina fulica. In the salivary duct of Achatina fulica, the lumen has narrow and long tubular structure. The boundaries between the endothelial cells are not clear. The cytoplasm is full of many vacuoles and electron lucent granules. At the apical portion of the cytoplasm, lots of short and thin microvilli are found. The salivary duct of Incilaria fruhstorferi is wider ($65\times250{\mu}m$ in diameter) than that of Achatina fulica, and consists of endothelial cells of the same structures. At the apical portion of those endothelial cells, a lot of junction apparatus such as desmosomes are observed. The vessels in the salivary ducts of Achatina fulica and Incilaria fruhstoferi are observed mainly in the connective tissues between the salivary glands. The endothelial cell of the vessel has the irregular structure and looks dark due to the high electron density. These cells protrude their filopodia and phagocytosize foreign bodies.