• Imaging Science in Dentistry
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• v.44 no.4
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• pp.321-324
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• 2014

Postoperative maxillary cysts are locally aggressive lesions, usually developing as delayed complications many years after radical antral surgery. This report describes a case of bilateral postoperative maxillary cysts following orthognathic surgery performed approximately 21 years previously. The patient complained of stinging pain on her right cheek. Radiographic examination revealed low-attenuation lesions on both maxillary sinuses with discontinuously corticated margins without distinct expansion or bone destruction. The cysts were enucleated with the removal of metal plates and screws for pain relief. Histopathological examination confirmed the diagnosis of postoperative maxillary cysts lined by ciliated, pseudostratified columnar cells. The patient has remained asymptomatic thus far, and there was no evidence of local recurrence at 21 months of postoperative follow-up.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.348-348
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• 2011

신곡수중보와 전류수위표 사이의 한강 하류부는 홍수기에는 침식에 의한 하상저하가 지배적이고, 비홍수기는 조석에 의해 하류로부터 유입된 부유사의 퇴적으로 인한 하상상승이 지배적인 지역이다. 본 연구는 평면 이차원 하상변동 예측모형인 KU-RLMS 모형을 적용하여 한강 하류부의 지형변화를 예측하기 위한 연구의 일환으로 수행하였다. 본 연구에서는 기존의 KU-RLMS 모형에 포함되어 있던 van Rijn 공식, Ackers-White 공식, Engelund-Hansen 공식 이외에 Colby 공식, Ranga Raju 공식, Shen-Hung 공식, Yang(1973) 공식, Yang(1979) 공식을 추가도 도입하고, 각 공식에 의한 하상변동 예측결과를 실측치와 비교하였다. 이 공식들 중에서 Colby 공식, Ranga Raju 공식, Shen-Hung 공식, Yang(1973) 공식, 그리고 Yang(1979) 공식에 의하면 하상변동이 과도하게 발생하였으며, 특히 과도한 퇴적이 유발됨에 따라 흐름모형이 발산되는 결과가 나타났다. 따라서 이들 공식을 한강 하구부에 적용하는 것은 부적당하다고 판단된다. 유사량 공식 적용의 타당성을 검토한 결과, 대상 구간에 대해 van Rijn 공식과 Engelund-Hansen 공식의 사용이 타당한 것으로 나타났다. 실측 결과와 비교할 때 어느 공식이 적합하다고 판단하기는 어려우며, 향후 보다 엄밀하게 비교할 필요가 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.307-307
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• 2011

ARF(Areal Reduction Factor, 면적우량감소계수)는 지점강우량을 면적 평균 강우량으로 변환하는 환산계수로 정의되며, 유역의 지형학적 특성과 강우의 공간적 분포특성을 반영한 유역단위의 ARF의 개발이 요구된다. 하지만 국내의 ARF는 대부분 한강유역을 대상으로 하고 있어 한강유역과 지형학적, 수문 기상학적 특징이 상이한 유역에 대하여 연구 결과를 적용하기는 많은 제약이 따를 것으로 판단된다. 따라서 본 연구에서는 남강댐 유역의 ARF를 산정하기 위해 7개의 강우관측소(산청, 삼가, 신안, 안의, 운봉, 태수, 함양)로부터 시강우자료(1990년~2010년)를 수집한 후 14개의 재현기간, 6개의 지속시간에 대한 지수형 ARF 회귀식을 산정하였다. 그 결과 남강댐 유역의 지수형 ARF 회귀식의 결정계수는 0.80~0.99로 높은 상관성을 나타내었다. 그리고 남강댐 유역의 ARF와 첨두홍수량의 관계를 분석하기 위해 남강댐 유역내의 산청유역을 대상으로 재현기간 100년, 지속시간 24시간에 대한 홍수량을 모의하였다. 그 결과 ARF의 적용 전 후의 첨두홍수량은 10% 이상 감소하는 것으로 나타났다. 따라서 남강댐 유역의 기상학적 특성을 고려한 첨두홍수량 산정을 위해서는 본 연구에서 제안한 ARF 회귀식이 유용할 것으로 판단된다.

• The Korean Journal of Mycology
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• v.8 no.1
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• pp.63-68
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• 1980

${\beta}-Lactamase$ was isolated from the culture filtrate of the penicillin producing strain, Penicillium chrysogenum Q176. When the pH of the medium was adjusted to 5.0 at the start of culture, a rapid increase in pH accompanied by the synthesis of penicillin was observed in the first $2{\sim}4$ days. When the pH of medium was brought to 6.0 or 7.0 the opposite was observed: high yield of the enzyme and little of the antibiotics in the medium. The optimum enzyme activi­ty was at a temperature of $40^{\circ}C$ and around pH 7.0. A partially purified enzyme was assayed on several different substrates including penicillins V and G, 6-aminopenicillanic acid, cephalospo­rin C. The V max values calculated were 24.5, 20.4, 7.6, and 6.1 mmoles/hour, and the $K_m$, values were 16.4, 12.6, 7.5, and 6.9 mM in the order given.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.533-537
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• 1999

ATO(Sb doped $SnO_2$) thin films whose thicknesses were 600, 1100 and $2100\AA$ were prepared by DC magnetron sputtering method. They showed the lowest resistivity at DC sputtering power 0.24kW and had lower resistivity with increasing thickness. The power dependence of resistivity among ATO thin films was also different with thickness. The increase of carrier concentration in ATO thin films was responsible for the decrease of resistivity with thickness increase. ATO thin films which were prepared at 30sccm oxygen flow rate showed a great change of sheet resistance under 1M HCl solution. The investigation of SAM(Scanning Auger Microprobe) revealed that oxygen atomic percentage on the surface of ATO thin films was changed. The decrease of sheet resistance also occurred when ATO thin films, prepared at 30sccm oxygen flow rate, were exposed to air for a long period of time. For this reason, it was considered that the desorption of oxygen on ATO surface was accelerated by HCl.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.513-517
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• 2007

MANET이 유연성 있고, 자유로운 네트워크로서 주목 받아감에 따라 MANET에서의 Routing 알고리즘이 중요한 논점이 되고 있다. 특히 이동 에드혹에서 각 Node에 대한 관리 방법은 향후 차세대 네트워크의 중요한 부분으로 인식되고 있다. 본 논문에서 연구하고 제안하는 오버레이 멀티캐스트 Routing 알고리즘은 Cluster링 Node의 오버레이ID 생성 및 유지에 관한 알고리즘으로 MANET의 여러 가지 제한 조건 및 조건에 따라 유연성 있게 작용하므로, 현재 많은 연구가 이루어지고 있다. 그러나 기존의 오버레이 멀티캐스트는 일반적인 단일 레이어로 이루어진 Cluster에 한하여 그 알고리즘을 적용하고 있으며, Cluster의 구성 및 유지 또한 Node의 속성 구분에 따른 에너지 등을 고려하지 않고 있다. 본 논문에서 제안하는 OMM은 오버레이 멀티캐스트를 Cluster링 기반의 RODMRP에서 사용하는 멀티레이어 구조에 링크코스트에 따른 Node의 잔여 에너지를 고려하여 적용하였으며, 멀티레이어의 장점과 네트워크의 Life Time을 위한 Node의 오버레이 ID 생성 및 유지에 대한 효율적인 알고리즘을 제안하고 있다

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.05a
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• pp.38-40
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• 1988

This paper was a study on dielectic characteristics of polypropylen film which were annealled in air and qunched in nitorgen after aging for 5[Hr]. Dielectric characteristics of specimen were measured in temperature of the range of 15-120[$^{\circ}C$], and in frequency of the range of $30-1{\times}10^6$[Hz.] As the result, for dielectric relaxation $\beta$-peak was observed in 20[$^{\circ}C$], and $\alpha$-peak was observed in 90[$^{\circ}C$]. Also, it was explained that $\alpha$-peak attributed due to armorphous region and $\beta$-peak attributed due to crystalline region and activation energy from dielectric loss spectra was obtained 34.5[kcal/mole] for $\alpha$-peak and 80.5[Kcal/mole] for $\beta$-peak, respectively.

• Journal of Korea Foundry Society
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• v.27 no.4
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• pp.179-183
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• 2007

The TiC layer was formed on Ti and Ti alloys by plasma carburizing method. The main experimental parameters for plasma car boozing were temperature and time. XRD, EDX, hardness test and corrosion test were employed to analyze the evolution and material properties of the layer. The preferred orientation of TiC layers is (220) at treated temperature of $700^{\circ}C\;and\;880^{\circ}C$ However, it is changed to (200) at temperature of $800^{\circ}C$ The thickness of carbide layer increase with increasing carburizing temperature. Highest hardness of hardened layer formed on CP-Ti was obtained at the carburizing condition of processing temperature $880^{\circ}C$ and processing time 1080min. The corrosion potential of carburizing specimen was higher than untreated CP-titanium, and corrosion potential increased as carburizing temperature and time increased. Thus the corrosion resistance of CP-Ti was greatly enhanced after plasma carburizing treatment.

• Fisheries and Aquatic Sciences
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• v.6 no.3
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• pp.160-163
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• 2003

Mortality of several species of fish and shellfish exposed to Harmful Algal Blooms (HABs) caused by Cochlodinium polykrikoides, Heterosigam akashiwo, Alexandrium tamarense, Eutreptiella gymnastica, Heterocapsa triquetra and Prorocentrum micans was studied. When fish were exposed to a cell density of 8,000 cells $mL^{-1}$ in C. polykrikoides, $35\%$ of flatfish and darkbanded rockfish died within 48 hrs. However, jacopever rockfish had mortality of higher than $85\%$. Rock bream, filefish and red sea bream showed $100\%$ mortality within 10 hrs with an exposure cell density of 8,000 cells $mL^{-1}$. The rest of HABs except for C. polykrikoides showed that there was no fish and shellfish death throughout the 48 hrs even in the maximum cell density of 100,000 cells $mL^{-1}$ These results imply that C. polykrikoides can have a serious impact on fish mortality and it is regarded as an ichthyotoxic dinoflagellate. The fish death may be attributed to anoxia caused by a combination of the production of reactive oxygen species (ROS) and polysaccharide from C. polykrikoides during blooms.

• Biomolecules & Therapeutics
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• v.17 no.1
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• pp.62-69
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• 2009

Roots of Astragalus membranaceus (A. membranaceus) (Astragali Radix, AR) has been used as a herbal medicine for gastrointestinal disorders in China, Korea, Japan, and other Asia countries. In this study we investigated the effects of the AR 70% ethanol extract and compounds isolated from AR on gastritis in rats and growth of human gastric cancer cells. AR 70% ethanol extract showed the potent acid-neutralizing capacities and partly cytotoxicity of Helicobacter pylori and human AGS gastric cancers cell. Astragaloside I and daucosterol, which were isolated from AR, significantly inhibited HCl/ethanol-induced gastric lesions. In addition, daucosterol increased the mucus content to almost the same as the positive control. The results of this study suggest that astragaloside I and daucosterol may be good candidates for the development of new drugs or neutraceuticals which can be used for the treatment or prevention of gastritis.