• 자원환경지질
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• 제28권2호
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• pp.139-145
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• 1995

Tungsten skarn mineralization of the Sangdong mine is localized in the interbedded limestone layers of the Myobong Slate Formation and in the limestone of the Pungchon Limestone Formation of Cambrian age. Fluid inclusion, gas composition and Nd-Sr isotope for granites and skarns have been investigated. Gas compositions show $CO_2$ rich in the Sangdong granite and CH, rich in the Nonggeori and Eopyeong granites. The initial $^{87}Sr/^{86}Sr$ and $^{143}Nd/^{144}Nd$ ratios of the Sangdong granites have 0.714~0.716(${\varepsilon}_{Sr}$=138~162) and 0.51173~0.51178(${\varepsilon}_{Nd}$=-14.4~15.5), respectively. And their two stage model ages range from 1687 to 1764 Ma. The granite characterized by high strontium initial ratios and negative eNd value could have originated from the old continental crust source. Low homogenization temperature of the Sangdong granite having $203{\sim}296^{\circ}C$ with 1.9~9.2 NaCl equiv. wt% indicates the post-magmatic hydrothermal alteration temperature. Skarn ore fluid responsible for tungsten mineralization has been evolved from CH, rich fluid of early pyroxene garnet skarn to $CO_2$ rich later quartz-mica skarn.

• 혜화의학회지
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• 제8권2호
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• pp.93-106
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• 2000

To evaluate the antitumor activity and antimetastatic effects of Kamicheungyeolhaedog tang(KCHT), studies were done experimentally. The results were obtained as follows: 1. KCHT extracts exhibited a significant cytotoxicity against A549, SK-MEL-2, SK-OV-3, and B16-BL6 cell lines. 2. KCHT extracts showed significant inhibitoty effect on DNA topoisomerase I 3. The T/C% was 145.8% in KCHT treated group in S-180 bearing ICR mice. 4. KCHT extracts exhibited efficient affect adhesive effect of A549, B16-BL6 cell to complex extracellular matrix. 5. In vitro neovascularization assays, angiogenesis was insignificantly inhibited in KCHT treated group as compared with control group. These results suggested that KCHT extracts might be usefully applied for prevention and treatement of cancer.

• 한국과학교육학회지
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• 제11권2호
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• pp.119-131
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• 1991

A taxonomy which can be used conveniently for analyzing the vertical articulation of mathematics and science textbooks has been developed. It includes two types sanalysis criterion: one is based on the detail of description and the other is based on the depth of contents in terms of their sequence. These two criterion elements are combined to form groups of 'overlap', 'development' and 'gap' to represent the extent of articulation. Examples of applying the taxonomy are illustrated for the concepts of gemetrical area in mathematics and potential energy in science.

• Journal of the Korean Data and Information Science Society
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• 제26권1호
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• pp.151-159
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• 2015

이 논문에서는 텍스트마이닝 (text mining) 기법을 이용하여 한국데이터정보과학회지에 게재된 논문의 영어초록을 분석하였다. 먼저 다양한 방법을 통해 단어-문서 행렬 (term-document matrix)을 생성하고 이를 사회연결망 분석 (social network analysis)을 통해 시각화하였다. 또한 토픽을 추출하기 위한 방법으로 LDA (latent Dirichlet allocation)와 CTM (correlated topic model)을 사용하였다. 토픽의 수, 단어-문서 행렬의 생성방법에 따라 엔트로피 (entropy)를 통해 토픽 추출 모형들의 성능을 비교하였다.

• 한국농촌건축학회논문집
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• 제16권2호
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• pp.45-54
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• 2014

This study aims to examine factor of tourism attraction and tourism satisfaction in order to product plan of tourism policies related to architecture and urban design focused on Marado, Jeju Island. For that, a questionnaire is conducted by tourists who visit to Marado. The results are as follows. 30s and 40s tourists evaluate that Marado is more attractive in natural environment rather than 60s. Tourists who visit more than four times to Marado evaluated low in satisfaction for landscape of Marado but tourists who reside in other area not Jeju evaluate higher in satisfaction for landscape. The difference of residence areas shows same result in tourism attraction factors. Tourists participating in tour activities show higher in satisfaction rather than no-participants but the difference between participants and no-participants is not showed in tourism attraction factors. Tourism attraction is extracted four factors; natural environment, architectural environment, economic efficiency and psychological factor. The factors of natural environment and architectural environment have the relation with satisfaction but the factors of economic efficiency and psychology do not show no relation with satisfaction.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.535-542
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• 2000

The investigated cut-slope is located in Odong-Ri, Hoebuk-Myun, Boeun-Gun and composed of quartzite and phyllitic rocks (approximately 80 meters in length and 25 meters in height). During the investigation, the groundwater which was inferred to the natural pipe of slope was continuously flowing in the upper part of slope. The investigation for discontinuity properties in this area was carried out to decide the rock mass rating and strength parameters. To analyze the stability of cut-slope, lower equal-area hemisphere projection method was used. And laboratory test was done to evaluate engineering properties of soil which was sampled in the non-failure and failure area The inferred causes of cut-slope failure are the geometric relationship between the orientation of cut-slope and geological structures such as joints, faults which is distributed in the slope. And direct cause of failure is the increase of water content due to the heavy rainfall.

• 대기
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• 제24권1호
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• pp.69-76
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• 2014

Urbanization affects the local thermal environment due to the large scale land use changes. To investigate the weather environment change of large scale urban redevelopment, 9 surface temperature and humidity observations were accomplished at Eunpyeong new town area. The observation period is from March 2007 to February 2010. In the center of development area, the air temperature has increased and relative humidity has decreased, by the changes of the land cover and building construction. In the area where the green zone is maintained, air temperature and relative humidity were not changed significantly. The air temperature and relative humidity for the other development observation stations is decreased and increased, respectively. The relative temperature difference between study area and a neighboring rural location was increased during observation periods. The difference is the highest during winter. The urban-rural minimum temperature difference was increased at development area, which means that urbanization affects increasing of minimum temperature in study area.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.934-937
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• 2003

In this paper, authors use a stereo vision system based on the visual model of human and establish inexpensive method that recognizes moving distance using characteristic points around the robot. With the stereovision. the changes of the coordinate values of the characteristic points that are fixed around the robot are measured. Self-displacement and self-localization recognition system is proposed from coordination reconstruction with those changes. To evaluate the proposed system, several characteristic points that is made with a LED around the robot and two cheap USB PC cameras are used. The mobile robot measures the coordinate value of each characteristic point at its initial position. After moving, the robot measures the coordinate values of the characteristic points those are set at the initial position. The mobile robot compares the changes of these several coordinate values and converts transformation matrix from these coordinate changes. As a matrix of the amount and the direction of moving displacement of the mobile robot, the obtained transformation matrix represents self-displacement and self-localization by the environment.

• 한국정밀공학회지
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• 제30권7호
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• pp.754-761
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• 2013

Thermal displacement is an important issue in machine tool systems. During the last several decades, thermal error compensation technology has significantly reduced thermal distortion error; this success has been attributed to the development of a precise, robust thermal error model. A major advantage of using the thermal error model is instant compensation for the control variables during the modeling process. However, successful application of thermal error modeling requires correct determination of the temperature sensor placement. In this paper, a procedure for predicting thermal-mode-based thermal error is introduced. Based on this thermal analysis, temperature sensors were positioned for multiple heat-source models. The performance of the sensors based on thermal-mode error analysis, was compared with conventional methods through simulation and experiments, for the case of a slide table in a transient state. Our results show that for predicting thermal error the proposed thermal model is more accurate than the conventional model.

• 한국분무공학회지
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• 제19권1호
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• pp.19-24
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• 2014

In this study, the cooling performance of a liquid CPU cooler using the water/propylene glycol(PG)-based $Al_2O_3$ nanofluids is experimentally investigated. Water/PG-based $Al_2O_3$ nanofluids are manufactured by two-step method with ultrasonic energy for 10 hours. The volume fractions of the nanofluids are 0.25% and 0.35%. Thermal conductivity and viscosity of the nanofluids are measured to theoretically predict the thermal performance of the liquid CPU cooler using performance factor. Performance factor results indicate that the cooling performance of the liquid CPU cooler can be improved using the manufactured nanofluids. To evaluate the cooling performance of the liquid CPU cooler experimentally, temperature differences between ambient air and heater are measured for base fluid and nanofluids respectively. Based on the results, it is shown that performance of the liquid CPU cooler using $Al_2O_3$ nanofluids is improved maximum up to 8.6% at 0.25 Vol.%.