• 상하수도학회지
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• 제19권4호
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• pp.421-428
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• 2005

Dissolved air flotation (OAF) is a solid-liquid separation system that uses fine bubbles rising from bottom to remove particles in water. In this study, we investigated the effect of L/W (L; Length, W; Width) on the hydro-dynamic behavior in DAF system using CFD (Computational Fluid Dynamics) and ADV (Acoustic Doppler Velocimetry) technique. The factual full-scale DAF system, L/W ratio of 1:1, was selected and various L/W ratio (2:1, 3:1, 4:1 and 5:1) conditions were simulated with CFD. For modelling, 2-phase (gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. Also, for verification of CFD simulation results, we measured the factual velocity at some points in the full-scale DAF system with ADV technique. Both the simulation and the measurement results were in good accordance with each other. As the results of this study, we concluded that L/W ratio and outlet geometry play important role for flow pattern and fine bubble distribution in the flotation zone. In the ratio of 1:1, the dead zone is less than those in other cases. On the other hands, in the ration of 3:1, the fine bubbles were more evenly distributed.

• 대한세포병리학회지
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• 제12권2호
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• pp.97-103
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• 2001

Carcinoma ex pleomorphic adenoma(CXPA) is a rare malignant tumor of the salivary gland, fine needle aspiration cytology(FNAC) of which are rarely reported. We retrospectively reviewed FNAC of five cases of histologically proven CXPA of the salivary glands diagnosed in Seoul National University Hospital to evaluate their cytologic characteristics. Histologically, the carcinoma components were low-grade in three cases and high-grade in two cases. The cytologic diagnosis were malignancy in two cases(40%), suspicious for malignancy in one(20%), and benign(pleomorphic adenoma) in two(40%). All of the high-grade carcinomas were correctly diagnosed by FNAC, however, 2 cases of low-grade carcinomas were diagnosed as benign by FNAC. The low sensitivity in cytologic diagnosis is due to interpretative difficulties in low-grade tumors. The characteristic cytologic features of CXPA were high cellularity, necrotic, bloody, and inflammatory background, marked nuclear overlapping, coarsely granular chromatin, prominent macronucleoli, and atypical mitosis in epithelial component in addition to the typical biphasic pattern of pleomorphic adenoma consisting of epithelial cells admired with spindle-shaped cells and chondromyxoid stroma. Even though low-grade tumors show mild pleomorphism, the cytologic findings of necrotic background, moderate to high cellularity, and nuclear overlapping could lead to an accurate cytodiagnosis of CXPA.

• 자원환경지질
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• 제19권2호
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• pp.133-146
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• 1986

Primary uraninite and secondary uranium minerals such as torbernite, metatorbernite, tyuyamunite, metatyuyamunite, autunite and metaautunite have been identified from various types of uranium ores. Uranium minerals occur as accessory minerals in both the primary and secondary ores. Low·grade uranium ores consist of various kinds of primary and secondary minerals. Major constituent minerals of primary uranium ores are graphite. quartz. Ba-feldspar and sericite/muscovite, and accessories are calcite, chlorite, fluorapatite, barite, diopside, sphene, rutile, biotite, laumontite, heulandite, pyrite, sphalerite and chalcopyrite, and secondary minerals consist of kaolinite, gypsum and goethite. Uraninite grains occur as microscopic very fine-grained anhedral to euhedral disseminated particles in the graphitic matrix, showing well·stratified or zonal distribution of uranium on auto-radiographs of low-grade uranium ores. Some uraninite grains are closely associated with very fine-grained pyrite aggregates, showing an elliptical form parallel to the schistosity. Some uraninite grains include extremely fine-grained pyrite particle. Sphalerite and pyrite are often associated with uraninite in graphite-fluorapatite nodule. The size of uraninite is $2{\mu}m$ to $20{\mu}m$ in diameter. Low-grade uranium ores are classified into 5 types on the basis of geometrical pattern of mineralization. They are massive, banded, nodular, quartz or sulfide veinlet-rich and cavity filling types. Well-developed alternation of uranium-rich and uranium-poor layers, concentric distribution of uranium in graphite-fluorapatite nodule and geopetal fabrics due to the load cast of the nodule suggest that the uranium was originally deposited syngenetically. Uraninite crystals might have been formed from organo-uranium complex during diagenesis and recrystallized by metamorphism. Secondary uranium minerals such as torbernite, tyuyamunite and autunite have been formed by supergene leaching of primary ores and subsequent crystallization in cavities.

• 대한세포병리학회지
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• 제9권1호
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• pp.45-54
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• 1998

Fine needle aspiration cytology is considered as a useful diagnostic procedure in management of patients with breast lesions. This study was undertaken to evaluate the scoring system of Masood in the interpretation of breast aspirates, to establish the most useful cytologic criteria for the diagnosis of breast lesions, and to subclassify the benign breast diseases. To assess the feasibility of a cytologic grading system, 57 cases of benign breast disease, 61 cases of malignant breast disease were studied, respectively. The aspirates were evaluated for the cellular arrangement, the degree of cellular pleomorphism and anisonucleosis, and the presence of myoepithelial cells and nuceoli. Values ranging from 1 to 4 were assigned to each criterion and the sum of the individual values was made for each case. The presence of stroma, apocrine metaplasia, foamy histiocytes and inflammatory cells, background of the smear, and cellularity were also evaluated. Cut-off value of the scoring system of Masood between benign and malignant lesion was 15. Among the cytologic criteria, cellular arrangement, presence of myoepithelial cells, nucleoli, and stroma, status of chromatin pattern, and background of smear were useful criteria in the differentiation between benign and malignant lesions. Application of the scoring system of Masood does not always make the accurate diagnosis and the subclassification of benign breast disease.

• 대한환경공학회지
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• 제29권8호
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• pp.915-921
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• 2007

본 연구는 매립가스내 siloxanes 측정의 기초 연구로서 국내 매립지를 대상으로 하여 용매흡수법으로서의 최적 용매를 선정하고자 수행하였으며, n-hexane, acetone 및 methanol을 흡수용매로 하여 각 용매의 siloxanes 검출 특성을 비교 분석하였다. 연구결과 표준물질의 GC분석에서 사용된 3가지 흡수용매 중 methanol이 용매와 silane 피크의 겹침현상이 발생하지 않아 분리능이 가장 우수하게 나타났다. 검출되는 siloxanes 농도는 흡수용매에 따라 최대 2.6배의 농도차를 보였으며, 포집유속과 포집 임핀저 단수에 대한 의존성에 대해서도 높은 것으로 나타났다. Methanol은 siloxanes 총 농도가 가장 높을 뿐만 아니라 휘발성이 적어 임핀저 단별 흡수에서도 가장 이상적인 형태를 보여주었으며, 가장 낮은 상대표준편차를 나타내 실험대상 매립지에 가장 적합한 것으로 나타났다. 그러나 용매의 적합성은 매립지의 쓰레기 성상, 매립이력에 따라 다를 수 있다고 판단된다.

• 한국응용과학기술학회지
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• 제26권2호
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• pp.117-123
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• 2009

Caprylic/Capric triglyceride-in-water emulsions stabilized by Nikkol HCO-60 and HCO-10 were prepared using emulsion inversion point method at different HLB values. Emulsions with various droplet sizes were formed, and emulsion inversion point was detected by electrical conductivity. The change in emulsion droplet sizes and long term stability were monitored using laser scattering method and visual method. The droplet sizes and stability of emulsions were affected by HLB of surfactant. At emulsion inversion point, the water volume fraction increased as the HLB of surfactants decreased. According to our analysis, this resulted from a tendency of forming the W/O (water-in-oil) emulsion as the HLB of surfactants was decreased. The emulsion inversion point was clearly detected by the microscope and the electric conductivity meter. Nanometer-sized emulsion was obtained at the optimum HLB by using emulsion inversion point method. The main pattern of instability of emulsions in HLB 12 and 13 systems was Ostwald ripening. However, The patterns of instability of emulsions below 11 of HLB systems were Ostwald ripening and coalescence. All emulsions produced with surfactants in the range of HLB 8-13, creaming caused by density difference between water phase and oil phase.

• 한국세라믹학회지
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• 제11권2호
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• pp.22-30
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• 1974

This study was carried out to investigate the species of iron compounds in kaolin mineral and the bonding relation between the major kaolin and its subordinate iron compound existing as incidental mineral in common clay by means of chemical composition, X-ray diffraction, thermal differential and thermogravimetrie analysis for the application of clays in the field of ceramic raw material. The domestic clay are produced abounduntly in many places, but San-Cheong kaolin, Chu-An clay, and Yeong-Am clay were selected as samples in this experiment because of their frequent utilization in porcelain industry. Two kinds of samples with low and high iron content are picked up respectively from the place of production and elutriated under two micron size to determine the properties and concentration of iron compound very fine particles or colloidal substance of low crystalline grade. Therefore, hydrothermal treatment in autoclave was conducted considering the existence of low crystalline grade of iron compounds known as an amorphoue state in X-ray diffraction pattern furthermore, de-iron treatment of hydrothermal compound was done in order to identify the related iron compound before and after hydrothermal reaction and iron compound which is one of the samples was synthesized for the determination of their compounds state in more detail. The obtained results in this study are as follows: In San-Cheong kaolin, Chu-An clay and Yeong-Am clay 1) It is proved that species accompanying iron compound is $\alpha$-FeOOH form. 2) Iron compound is composed of very fine particles or colloidal substance. 3) The iron substance encircles the fine parts of clay minerals under 2 micron and acts as cementizing agent.

• 대한세포병리학회지
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• 제6권2호
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• pp.193-198
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• 1995

The increased use of thyroid fine needle aspiration(FNA) has re-focused on $H\"{u}rthle$ cell lesions. The cytologic diagnosis of $H\"{u}rthle$ cell tumor is a challenge due to the presence of $H\"{u}rthle$ cells in non-neoplastic lesions and the inability to differentiate between benign and malignant $H\"{u}rthle$ cell tumor. We report a case of $H\"{u}rthle$ cell adenoma(HCA) un a 68-year old woman, with review of the cytopathologic findings. FNA revealed loosely cohesive or sheets of large oval to polygonal $H\"{u}rthle$ cells containing abundant granular cytoplasm. The hustopathologic examination confirmed the diagnosis of HCA with follicular growth pattern. Ultrastructurally, the cytoplasm was packed with variable sized mitochondria.

• 한국수산과학회지
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• 제23권2호
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• pp.145-154
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• 1990

고리 해역 현탁물의 총량은 표층수에서 $3\~4\;mg/\iota$ 정도이고 저층수에서는 $3.5\~5\;mg/\iota$ 정도로 표층보다 높으며 특별한 계절변화는 없는 것으로 나타났다. 표층퇴적물은 주로 실트와 점토가 $90\%$이상인 세립질 퇴적물로 되어 있으며 미약하나마 외양으로 갈수록 세립화되는 경향이 나타난다. 현탁물중 점토광물의 상대비를 보면 illite가 평균 $65\%$ 정도로 가장 많고 kaolinite와 chlorite는 각각 $170\%$ 정도로 거의 비슷하고 smectite는 $1\%$ 내외의 미량이었다. 고리 부근 현생퇴적물의 주 공급원은 낙동강으로 생각되지만 대마해류에 의해 유입된 동지나해와 남지나해 세립질 퇴적물의 영향도 고려해야 할 것으로 사료된다.

• 대한세포병리학회지
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• 제5권1호
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• pp.35-40
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• 1994

저자들은 접할 기회가 흔치 않은 갑상선의 저분화암종인 일명 "도암종"의 세침흡인 세포검사 1예를 경험하고 조직학적으로 확인하였기에 문헌검색과 함께 보고하는 바이다. 흡인 도말된 세포들은 비교적 깨끗한 도말배경에 중등도 이상의 높은 세포밀도를 보였으며, 세포들은 개개로 흩어지는 양상과 판상의 군집을 이루는 양상이 어우러져 관찰되었다. 때로 세포들이 소포배열을 이루는 곳도 관찰되었다. 대부분의 종양세포들은 비교적 비슷한 크기와 모양을 나타내었으나 일부의 세포들은 현저한 다형성을 보였다. 일부의 세포에서 핵에 주름을 보였으나 소수에 불과하여 이는 어떤 갑상선병변에서나 관찰할 수 있는 비특이적 변화로 간주되었다. 세포의 겹침이 별로 없이 높은 세포밀도를 보이는 점, 세포가 개개로 흩어지는 양상과 소수 다형성이 현저한 세포의 혼재 등은 본 종양을 진단하는데 도움이 되는 소견으로 생각되며, 이러한 소견을 염두에 둠으로써 수술전 진단에 도움을 줄 수 있으리라 생각된다.