• The Korean Journal of Ceramics
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• 제6권1호
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• pp.27-31
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• 2000

A series experiments were performed to evaluate mechanical behavior of non-oxide boride type ceramics formed on the AISI 1040 plain carbon steel. Boronizing was performed in a slurry salt bath consisting of borax, boric acid, and ferro-silicon at $950^{\circ}C$ for 2-6h. The AISI 1040 steel used as substrate material was containing 0.4%C, 0.13%Si, 0.65%Mn, 0.02%P, 0.014%S. The presence of non-oxide boride type ceramics $Fe_2B $ and FeB formed on the surface of steel was confirmed by metallographic technique and X-ray diffraction (XRD) analysis. The hardness of borides measured via Vickers indenter with a load of 2N reached a microhardness of up to 1800 DPN. The hardness of unborided steel was 185 DPN. The fracture toughness of borides measured by means of Vickers indenter with a load of 10N was about 2.30 MPa.$m^{1/2}$. The thickness of boride layers ranged from 72$\mu\textrm{m}$ to 145$\mu\textrm{m}$. Boride layers have a columnar morphology.

• 한국재료학회지
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• 제26권4호
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• pp.207-211
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• 2016

Ti films were deposited on glass substrates under various preparation conditions in a chamber of two-facing-target type dc sputtering; after deposition, the electric resistivity values were measured using a conventional four-probe method. Crystallographic orientations and microstructures, including the texture and columnar structure, were also investigated for the Ti films. The morphological features, including the columnar structures and surface roughness, are well explained on the basis of Thornton's zone model. The electric resistivity and the thermal coefficient of the resistivity vary with the sputtering gas pressure. The minimum value of resistivity was around 0.4 Pa for both the $0.5{\mu}m$ and $3.0{\mu}m$ thick films; the apparent tendencies are almost the same for the two films, with a small difference in resistivity because of the different film thicknesses. The films deposited at high gas pressures show higher resistivities. The maximum of TCR is also around 0.4 Pa, which is the same as that obtained from the relationship between the resistivity and the gas pressure. The lattice spacing also decreases with increasing sputtering gas pressure for both the $0.5{\mu}m$ and $3.0{\mu}m$ thick films. Because they are strongly related to the sputtering gas pressures for Ti films that have a crystallographic anisotropy that is different from cubic symmetry, these changes are well explained on the basis of the film microstructures. It is shown that resistivity measurement can serve as a promising monitor for microstructures in sputtered Ti films.

• 접착 및 계면
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• 제15권4호
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• pp.161-168
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• 2014

페놀과 피리딘 간의 단일 수소결합을 이용하여 새로운 형태의 자기 집합된 원반형 액정을 제조하고 그 액정 특성을 조사하였다. 원반형 구조 설계를 위해 phloroglucinol을 중심부 분자로, 체계적으로 알킬사슬 길이를 변화시킨 trans-4-alkoxy-4'-stilbazole을 주변 물질로 사용하였다. 적외선 분광 분석을 통해 중심부 분자와 주변 물질 사이의 분자간 수소결합이 성공적으로 형성됨을 확인하였고, 또한 수소결합의 안정성이 분자 정렬에 의해 크게 영향을 받음을 확인하였다. 자기 집합된 원반형 액정 복합체는 원반형 메소겐 주위의 알킬 사슬 길이에 따라 다른 액정상들을 나타내었다. 긴 알킬사슬을 함유하는 액정 복합체의 경우 육방형 컬럼상이 나타났으며, 상대적으로 짧은 사슬을 갖는 다른 액정 복합체에서는 네마틱 컬럼상이 형성되었다. 이는 자기 집합된 원반형 액정 복합체의 액정상 구조가 원반형 핵 단위 주변의 알킬사슬 길이에 의해 크게 영향을 받음을 의미하였다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제31권4호
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• pp.316-321
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• 2005

Ameloblastoma is the most common odontogenic tumor of the jawbones, but the origin of this tumor has been remained to be unproven. Cytokeratins (CKs) are specific intermediate filament of epithelial cells, and vimentin is expressed in mesenchymal cells. The immunohistochemical detection of different CKs and vimentin has made it easier to know the origin of tumor. Paraffin-embedded tissue sections from 15 ameloblastomas and 1 ameloblastic carcinoma were used for immunohistochemical evaluation of CK 7, 8, 13, 14, 19 and vimentin. Their expression is evaluated in different tumor cells, which are observed in different type of tumors. In the follicular and reticular subtype, central stellate cells of tumor nests expressed CK 8, 14, 19 and peripheral columnar cells expressed CK 14. CK 7, and 13 were not expressed. Vimentin was detected in fibrous stroma around tumor nest, not in tumor cells. The tumor cells of ameloblastic carcinoma expressed CK 7, 14 and 19, but CK 8 was more weakly stained than that in ameloblastoma. Central stellate cells and peripheral columnar cells of acanthomatous subtype showed same expression pattern with others. Meta plastic squamous cells expressed CK 8, 14, 19 and keratinizing squamous cells expressed CK 13, 19. CK 7 and vimentin were not detected in tumor cells and vimentin was expressed in fibrous stroma. Most of the tumor cells of ameloblastoma showed CK 14 and CK 19 and did not express CK 7 and vimentin. These findings were similar to the immunophenotype of dental lamina. And these results will be beneficial to differential diagnosis of odontogenic tumors and other kind of tumors arising at the oral cavity.

• Applied Biological Chemistry
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• 제40권4호
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• pp.329-333
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• 1997

PDA-calcium phosphate 평판배지를 이용하여 경남북 일대의 토양으로부터 인산가용화능이 우수한 1,000여종의 세균과 200여종의 사상균을 분리하였다. 이중에서 인산가용화능이 가장 우수한 사상균 GL-101 균주를 선발하여 MEA와 PDA 배지에서 배양하면서 분생자병과 분생자의 형태적 특성을 조사한 결과 플라스크형의 phialide, 분생자병의 branching type이 simple type이며, conidial head가 columnar shape 등의 특징을 갖는 Penicillium sp. GL-101로 동정되었다. 이 균주의 인광석 분해능이 최대가 되는 최적 배양온도와 초발 pH는 각각 $25^{\circ}C$와 pH 7.5이었다. 이와같은 배양조건에서 tricalcium-phosphate, aluminium phosphate, hydroxyapatite, 인광석 등의 난용성 인산염에 대한 이 균주의 인산가용화능을 살펴보면 배양 8일째에 최대값을 보였으며, tricalcium-phosphate에 대해서는 1,152 ppm, 인광석에 대해서는 565 ppm, aluminium phosphate에 대해서는 292 ppm, hydroxyapatite에 대해서는 217 ppm의 유리인산을 생성하였다.

• Applied Microscopy
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• 제26권3호
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• pp.305-313
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• 1996

Acinous gland cells (A, B, C, D and E-type cells) and duct cell (G-type cell) are observed in acinus and in duct of salivary gland of Korean Slug respectively by electron microscope. The type-A gland cells are numerous and are packed with medium electron dense granules (diameter, $3{\mu}m$) in cytoplasm. The circular shaped nucleolus and evenly developed chromatins are observed in the nucleus of type-B cell, and cytoplasm includes medium electron dense granules (diameter, $2.5X3.7{\mu}m$). The type-C gland cell has a round nucleus, and thin elongated-shaped heterochromatins are evenly distributed in the nucleoplasm and many net shaped endoplasmic reticulums and oval serous granules of middle electron density (diameter, $3.5X5{\mu}m$) fill the cytoplasm. The type-D gland cell is the largest and the most numerous of the gland cells consisting the salivary gland and heterochromatins in nucleus are well developed in the nucleoplasm. Most of granules (diameter, $0.8X2.5{\mu}m$) in cytoplasm are round, and look dark for the high electron density, and cytoplasm is filled with net-shaped endoplasmic reticulums. The type-E gland cells are rarely existent around the salivary gland, and the granules of those cells are irregular in shape and size and are vacuolized in cytoplasm. Intralobular salivary duct is composed of the high electron dense squamus endotheliums, while the other interlobular salivary duct is filled with irregular columnar epitheliums. The interlobular duct cell contains the high electron dense granules (size, $0.3{\sim}1.5{\mu}m$) in cytoplasm and those granules are secreted into cilia of salivary lumen.

• 한국패류학회지
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• 제12권1호
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• pp.1-17
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• 1996

Morphological and histochemical characteristics of the cells in posterior tentacle antenna of Korean slug, Incilaria fruhstorferi were observed with light microscope. The epithelium of the posterior tentacle antenna was composed of supporting cells, sensory neurons and type-a clear cell. The columnar supporting epithelium was widely distributed in the posterior tentacle antenna, and the upper end of the cell was covered with acidic mucopolysaccharide. Nerve endings of the sensory neuron were distributed between type-a clear cells. It was usually located in tentacular knob, and the number of them gradually decrdased as close as tentacular stalk. Several cilia were observed on the nerve ending. Type-a clear cells were very brightly stained with all staining used, and the neutral mucous guanules distributed in the cytoplasm. Collar cells, type-b clear cell and various types of secrdtory cells distributed in the connective tissue. The collar cells were clustering in connective tissue, and the cytoplasm were filled with neutral mucous guanules. The cells and granules were stained with dark brown by silver nitrate stain. Type-b clear cells were irregular in shape and their cytoplasms were brightly stained wth many stains used. Ten types of secretory cells evenly distributed in the connective tissue and muscle layers of the posterior tentacle antenna. The five types of the secretory cells(A, B, E, J and L)seemed to secrete acidic mucopolysaccharide, and the other five type of the cell(C, D, F, H, and L)seemed to secrete neutral mucopolysaccharide. Muscular tissue composed of well-developed thick longitudinal muscle layers and thin circular muscle layers. Type-L secretory cells clustered only in muscular layers and they contained acidic mucopolysaccharides.

• 비파괴검사학회지
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• 제9권1호
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• pp.8-21
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• 1989

This paper presents the ultrasonic characteristics of weldment and detectability of defects of weldment in Austenitic Stainless Steel Type 304 that is composed of mostly coolant piping system in nuclear power plants. The results of this experient show as follows: 1. When the ultrasonic beam detects the defects on the side of base metal and on the opposite side of weldment, the indications which was detected on the screen show different amplitude and different metal path each. 2. The ultrasonically estimated notch depth is generally oversized than actual notch depth. 3. It is easy for the false indication to show up on the screen because of columnar structure of weldment in austenitic stainless steel. 4. The higher frequencies of transducer have more difficulties to detect the defects of the opposite side of weldment because of ultrasonic attenuation in weldment and the longitudinal transmitter-receiver transducer is the most effective in detecting the opposite side defects of weldment.

• KSBB Journal
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• 제13권5호
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• pp.497-501
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• 1998

A fungus with high phosphate solubilizing activites was isolated from soil using potato dextrose agar-calcium phosphate medium and identified to Penicillium sp. PS-113, based on the morphological characteristics of conidiophore and conidia; flask shape of phialide, simple branching type of conidiophore, and columnar shape of conidial head, in malt extract agar and potato dextrose agar media. The optimum temperature ad initial pH to solubilize rock phosphate in potato dextrose broth-rock phosphate medium were 30$^{\circ}C$ and pH 8.0, respectively. In these conditions phosphate solubilizing activities of Penicillium sp. PS-113 against four types of insoluble phosphate like tricalcium-phosphate, aluminium phosphate, hydroxyapatite and rock phosphate were quantitatively determined. As results, this fungus highly produced free phosphates to the culture broth with the concentrations of 1,283 ppm against tricalcium-phosphate, 585 ppm against rock phosphate, 528 ppm against aluminium phosphate, and 242 ppm against hydroxyapatite, respectively.

• Nuclear Engineering and Technology
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• 제5권2호
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• pp.94-102
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• 1973

원주상 재결합 영역에 있어서 전리함의 포화특성을 이론적으로 검토하고, 보론 피복 원통형 전리한을 설계, 제작하여 내부에 질소 또는 헬륨을 760mmHg와 380mmHg로 충전시켜서 실험적임 측정을 하였다. 해석적임 방법으로 도출한 collection efficiency의 식은 실험결과와 잘 일치하였다. 이 결과를 이용하면 보론을 피복한 전리함의 포화특성을 실험적인 측정 업이 설계치에 의한 이론적인 계산만으로 예측할 수 있다.