• YAKHAK HOEJI
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• v.51 no.2
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• pp.145-149
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• 2007

Saussurea Radix, the dried roots of Saussurea lappa Clark (Compositae), has been used in oriental traditional medicine for aromatic stomachic. Present study was carried out for the anticancer effect of Saussurea Radix. Bioassay-directed fractionation of Saussurea Radix led to the isolation of two sesquiterpenes, dehydrocostuslactone (1) and costunolide (2). The structures of 1 and 2 were elucidated by spectral methods (MS, IR, $^1$H and $^{13}$C NMR). These compounds showed a potent cell proliferation activity against human breast cancer cell MCF-7 and MDA-MB-453.

• International Journal of Knowledge Content Development & Technology
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• v.6 no.2
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• pp.67-92
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• 2016

Employing a newly developed conceptual framework of the tasks and activities that comprise today's digital scholarly undertaking and their potentially reputation building, maintaining and enhancing components, the efforts of ResearchGate in supporting scholars' reputation building endeavours were put under the microscope. Not unexpectedly, RG performs well in regard to basic research activities. Clearly, too, with ten metrics at its disposal, RG is in a league of its own when it comes to monitoring individual research reputation. Where RG falls down is regarding scholarly activities that do not concern pure research and so especially teaching. Its claim to have created a new way of measuring reputation is only partially true because if it wants to do so genuinely then it needs to extend the range of scholarly activities covered. RG also falls short in informing members as to the nature and changes to its service and of embracing new actors, such as citizen scientists and amateur experts.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.533-541
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• 2014

The streams in Jeju Island have very distinctive hydrological and geological properties and there are a lot of limits in applying the general flood estimation method. This study presented parameters dominant in the Hancheon stream of Jeju Island by analyzing the sensitivity of parameters of HEC-HMS model regarding rainfall events in the target basin, and extracted the optimal parameter(Time of Concentration of Clark Unit Hydrograph: Kraven II method, Storage Coefficient: Sabol method) by analyzing and comparing it with the flood runoff data observed in the site and Jeju Island's observation data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.223-226
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• 2005

본 논문에서는 지능형 교통망 시스템 서비스에 사용하는 5.8GHz 대역에서 OFDM을 이용한 단거리 전용 통신 시스템의 성능을 분석하였다. 현재의 DSRC 시스템은 1Mbps 이상의 데이터 서비스가 어려울 것으로 예상되므로 개선도니 변복조방식이 요구된다. OFDM(orthogonal frequency division multiplexing) 방식은 보호구간의 삽입을 통하여 ISI를 방지할 수 있으므로 고속 데이터 전송에 적합하다. 따라서, 본 논문에서는 데이터 변조 방식으로는 IEEE 802.11a에 근거한 부 반송파의 수가 64개인 QPSK변조 방식을 사용하는 OFDM 시스템을 모델링 하고, 도플러 천이 효과를 고려한 Clark & Gans 페이딩 환경에서 성능을 분석하였다. 또한 페이딩 환경에서는 성능의 열화 정도가 크기 때문에 이를 극복하기 위해 채널 예측기를 사용하여 채널 응답을 근사적으로 예측${\cdot}$보상하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.233-236
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• 2005

국내외적으로 M/W 중계용 주파수 대역은 3${\sim}$30GHz 대역이다. 그러나 갈수록 늘어나는 서비스와 전송용량의 증대로 인해 주파수 부족현상이 일어나는 추세이다. 이에 대한 방안으로 주파수 재배치에 관한 문제가 대두되고 있다. 이동방송 중계용 링크인 FPU 링크는 차후 다른 주파수 대역으로 이전시 이전의 링크에서 사용되었던 시스템 제원을 토대로 필요한 대역에 대해 다양한 변조방식으로 시뮬레이션 평가 후 이용채널 개수 및 이전 가능 여부등과 같은 조치가 수행되어져야 한다. 본 논문에서는 M/W 대역 휴대용 디지털 무선전송 시스템으로써 디지털 FPU 링크 시스템을 모델링하고 이동환경에서 발생하는 도플러 천이 효과를 고려한 Clark & Gans 페이딩 채널 모델을 고려하여 페이딩의 영향에 따른 시스템 성능을 분석하였다.

• Applied Microscopy
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• v.46 no.4
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• pp.227-237
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• 2016

This investigation deals with the process of field electron emission from composite microemitters. Tested emitters consisted of a tungsten or carbon-fiber core, coated with a dielectric material. Two coating materials were used: (1) Clark Electromedical Instruments Epoxylite resin and (2) Epidian 6 Epoxy resin (based on bisphenol A). Various properties of these emitters were measured, including the current-voltage characteristics, which are presented as Fowler-Nordheim plots, and the corresponding electron emission images. A field electron microscope with a tip (cathode) to screen (anode) distance of 10 mm was used to electrically characterize the emitters. Measurements were carried out under ultra-high vacuum conditions with a base pressure of $10^{-6}$ Pascal ($10^{-8}$ mbar).

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.232-236
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• 2012

본 연구에서는 산간계곡의 경보발령기준의 고도화를 위하여 Clark 유출모형에 의한 단위도를 산정하고 연구대상유역의 강우패턴을 분석하여 강우분포를 적용하였다. 강우량적용에 있어서 유효우량을 산정해야 하며 유효우량 산정시 유출곡선지수(CN)를 산정하여 적용해야 하는데 발령기준우량을 산정하는데 CN값 등의 관계매개변수에 민감하게 반응하는 것으로 분석되었다. 따라서 본 연구에서는 유역특성에 따른 경보발령기준우량과 CN값의 민감도를 분석하여 자동우량경보시설 경보발령기준우량을 결정하는 신뢰도를 향상시켜 소음에 대한 피해를 줄이고 인명피해를 예방하는데 도움을 주고자 한다. 또한 경보발령기준우량을 산정하기 위한 정량적인 방법을 제시하므로서 지역특성에 맞는 경보발령기준우량을 결정하는데 수문학적 매개변수를 제시하였다.

• Animal Systematics, Evolution and Diversity
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• v.19 no.1
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• pp.103-109
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• 2003

Presynaptiphilus poraminutus is described as a new species in association with the ophiuroid Ampioplus ancistrotus (H. L. Clark) collected from an intertidal sand beach in the Yellow Sea. The new species is closely related to P. minutus in having the identical leg structure, but may be differentiated from the latter by the larger body, the longer genital double-somite and caudal rami, and the shorter pre-anal semite.

• Water Engineering Research
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• v.4 no.1
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• pp.1-17
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• 2003

A mathematical model was developed to simulate the performance of a prototype wind-powered reverse osmosis desalination system. The model consists of two sub-models operated in a series. The first sub-model is the wind-energy conversion sub-model, which has wind energy and feed water as its input and pressurized feed water as its output. The second sub-model is a reverse osmosis (RO) process sub-model, with pressurized feed water as its input and the flow and salinity of the product water or permeate as its output. Model coefficients were determined based on field experiments of a prototype wind powered RO desalination system of the University of Hawaii, from June to December 2001. The mathematical model developed by this study predicts the performance of wind-powered RO desalination systems under different design conditions. The system optimization is achieved using a linear programming approach. Based on the results of system optimization, a design guide is prepared, which can be used by both manufacturer and end-user of the wind-driven reverse osmosis system.

• Animal Systematics, Evolution and Diversity
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• v.36 no.3
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• pp.264-267
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• 2020

Thaumatometra tenuis (A. H. Clark, 1907), an unstalked crinoid that lives on the muddy bottoms of the deep sea, is re-described with images in this study. This species distributes in the cold water zone of the northwestern Pacific and had been reported at the end of 1800s from South Korea but had not been found thereafter. So we thought that this species was no longer living in Korea. In March 2019, a large number of T. tenuis were found near the Sokcho-si, Gangwon-do, Korea. So the presence of T. tenuis in Korea is reconfirmed. This species, markedly fragile overall, is characterized by long segments of cirri and pinnules, and P₁ composed of 35 segments.