• Journal of the Korean Geotechnical Society
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• v.20 no.4
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• pp.29-38
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• 2004

A finite element nonlinear stress-deformation model with multi-interface element is applied to the stability analysis of waste landfill slope. Strength parameters of waste and geosynthetic materials are obtained from the triaxial test of waste and the direct shear test of geosynthetics, respectively. The landfill models used for the numerical models are fit to regulations of the Korean waste management law. The results of the strength tests showed linear behavior for the waste and nonlinear behavior for the eosynthectic materials. The stability analysis with multi-interface element for the geosynthetic materials in the liner system showed large shear stress and slippage at the boundary of the foundation and the slope of the waste fill. This analysis verified the necessity of multi-interface analysis for waste landfills with composite liners.

• The Korean Journal of Applied Statistics
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• v.35 no.4
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• pp.517-525
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• 2022

In the era of big data, various data mining techniques have been proposed as major analysis methodologies. As complex and diverse data is mass-produced, data mining techniques have attracted attention as a method that forms the foundation of data science. In this paper, we focused on the decision tree, which is frequently used in practice and easy to understand as one of representative data mining methods. Specifically, we analyzed the effect of the splitting method of decision trees on the model performance. We compared the prediction power and structures of decision tree models with different split methods based on various simulated data. The results show that the linear combination split method can improve the prediction accuracy of decision trees in the case of data simulated from nonlinear models with complex structure.

• Journal of the Korean association of regional geographers
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• v.11 no.2
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• pp.291-311
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• 2005

The great estate system of the Old World crossed the Atlantic Ocean in the 1500s along with the Spanish Royal Army, mission, merchants, crops and domestic arrivals, landing at the end of the journey in the Middle and South Americas. The latifundio of Spain's Middle Age combined with the environment of the New World to be regenerated in the name of hacienda which bad became tightly roared in the countryside landscape of New Spain by fin-de-colonial period of 1820s. The haciendas were distributed mainly over the central part of the present-dey Mexico, and the presence of water and towns determined the specific location of the large landed estates. Depending on the activities performed, the hacienda can be divided into several types such as grain hacienda, livestock hacienda, mining hacienda, henequen hacienda, and so forth. Consisting of landlords, estate managers and waged labor called peons, the hacienda as a semi-autarkic settlement played various roles as the home of church, the agrarian center and the hearth of cultural diffusion, as well as dwelling. Toward the end of the colonial period the hacienda experienced internal transformations driven by capitalism.

• Journal of the Korean association of regional geographers
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• v.15 no.2
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• pp.307-315
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• 2009

The purpose of map generalization is a method of map making to transmit the concise cartographic representation and geographic meaning. New generalization algorithm has been developed to be applied in the digital environments by the development of computer cartography. This study aims to look into possibilities of the multiscale mapping by generalization in application with the coordinate transformation and LoD(level of detail) in the web cartography. A method of the coordinate transformation is to improve a transmission of spatial data. Lod is a method which is making web map with selection spatial data by zoom level of users. Layers for test constructed contour line, stream network, the name of a place, a summit of mountain, and administrative office. The generalization was applied to zoom levels by scale for the linear and polygonal features using XML-Based scalable vector graphics(SVG). Resultantly, storage capacity of data was minimized 41% from 9.76mb to 4.08mb in SVG. Generalization of LoD was applied to map elements by stages of the zoom level. In the first stages of zoom level, the main name of places and administrative office, higher order of stream channels, main summit of mountain was represented, and become increase numbers of map elements in the higher levels. Results of this study can help to improve esthetic map and data minimization in web cartography, and also need to make an efforts to research an algorithm on the map generalization over the web.

• Proceedings of the Korean Society of Toxicology Conference
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• 1998.10a
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• pp.8-13
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• 1998

Polyoma Virus Enhancer core Binding Protein (PEBP2)는 유전자의 전사를 조절하는 hetero-dimeric transcription factor로서 $\alpha$와 $\beta$ subunit으로 구성되어 있다. $\alpha$ subunit을 coding 하는 유전자중 하나인 PEBP2aB는 급성백혈병과 관련되어있는 t(8;21) 또는 t(12;21)에 의하여 변형됨으로서 백혈병 발병의 원인이 되고 있다 (Miyoshi et al., 1993; .Romana et al., 1995). $\beta$ subunit을 coding 하는 PEBP2$\beta$도 inv(16)에 의하여 변형됨으로서 백혈병을 유도하는 주요 원인이 되고 있다 (Liu et al., 1993). 이 유전자들의 생물학적 활성을 밝히기 위한 연구가 gene targeting에 의한 knockout mouse 생산 방법으로 수행되었다. 그 결과 PEBP2$\alpha$B와 PEBP2$\beta$ 유전자가 definitive hematopoiesis에 있어서 결정적으로 중요한 역할을 하고 있음이 관찰되었다 (Okuda et al., 1996, Wang et al., 1996a, 1996b), 이는 이들 유전자가 bematopoietic master switch 유전자임을 밝힌 중요한 결과로서 이로부터 혈액학 연구 분야의 새로운 장이 열리게 되었다. 또한 이러한 연구 결과들은 PEBP2 family에 속하는 다른 유전자의 생물학적 활성의 연구를 촉진하는 계기가 되었다. 최근 PEBP2$\alpha$A 유전자가 결손된 마우스가 생산되었는데 이 유전자의 경우에는 모든 종류의 뼈의 생성이 완전히 결손됨이 관찰되었다 (Komori et al., 1997). 이는 PEBP2$\alpha$A 유전자가 뼈의 생성을 지배하는 master switch 유전자임을 보여주는 중요한 관찰로서 bone biologist 들의 큰 관심을 모으고 있다. 본 연구팀은 PEBP2 family 유전자 중 유일하게 아직 생물학적 활성이 규명되지 않은 PEBP2$\alpha$C 유전자의 활성을 knockout 마우스를 생산하는 방법에 의하여 분석하였으며 소화기관의 형성에 중요한 역할을 하고 있음을 확인하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.387-387
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• 2012

결정 Si 및 비정질 Si 태양전지는 환경친화적이며 안정적인 물질로 전력변환 및 에너지 저장 장치에 중요하기 때문에 연구가 활발하게 진행되고 있다. 고효율 Si 태양전지를 제작하여 상용화하기에는 여러 가지 문제점이 있다. 공기와 비교하여 높은 굴절률을 갖고 있기 때문에 발생하는 반사를 줄이기 위해서 필요한 무반사 코팅층(Anti-reflective coating; ARC)은 주로 SiO2 와 SiNx 와 같은 유전체를 이용하여 사용하지만 이들 ARC 증착은 PECVD와 같은 진공장비를 사용하므로 제작 비용이 높아지는 단점이 있다. 나노선 또는 나노 팁과 같은 sub-wavelength 구조를 표면에 만들어 반사율을 줄이는 작업을 통해 ARC 공정비용을 감소하고 효율을 증진하는 연구가 활발히 진행되고 있다. CdS 양자점을 태양전지 표면에 형성함으로 ARC로 해결할 수 없는 단파장영역에 해당하는 부분을 줄이는 연구가 진행되었으며, 비정질의 경우 원기둥 형태의 태양전지 형태와 더불어 지름 방향으로의 PN 접합 나노로드 배열을 만들어 흡수면을 증가하여 효율을 증가한 연구도 진행되었다. 태양전지 표면의 형태를 V-groove 형태로 형성하여 입사하는 태양전지의 광밀도를 증가하는 이론적 결과도 발표되었다. 본 연구에서는 Si 태양전지의 표면변형에 따른 태양전지의 전력변환효율의 변화를 관찰하기 위하여 태양전지 표면의 texture 지름을 $3{\sim}15{\mu}m$, 간격을 $5{\sim}20{\mu}m$로 변화하고, 태양전지 표면의 나노 패턴을 2~10 nm 로 변화하여 반사율과 전력변환효율을 비교하였다. 나노와 마이크로 패턴은 각각 polystyrene nanosphere 와 photo mask를 이용하여 제작하였으며 PN junction Si 태양전지는 spin on dopant 방식으로 제작하여 성능을 조사하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.3
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• pp.204-212
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• 2015

The infrared lock-on range of target aircraft plays a critical role in determining the aircraft survivability. In this investigation, the effects of various UAV engine nozzle configurations on the aircraft lock-on range were theoretically analyzed. A virtual subsonic aircraft was proposed first, based on the mission requirement and the engine performance analysis, and convergent-type nozzles were then designed. After determining thermal flow field and nozzle surface temperature distribution with the CFD code, an additional analysis was conducted to predict the IR signature. Also, atmospheric transmissivity for various latitude and seasons was calculated, using the LOWTRAN code. Finally, the lock-on and lethal envelopes were calculated for different nozzle configurations, assuming the sensor threshold of the given IR guided missile. It was shown that the maximum 55.3% reduction in lock-on range is possible for deformed nozzles with the high aspect ratio.

• The Journal of Engineering Geology
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• v.11 no.2
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• pp.191-203
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• 2001

We investigate mechanical anisotropy dependent of rock fabric and its relationship with microcracks in the Pocheon Granite. Uniaxial compressive strengths range from 177MPa to 212MPa and the elastic constants are 48GPa-62GPa. The tensile strengths are 6.9MPa~8.5MPa and ultrasonic wave velocities range between 3,200m/sec and 3,700m/sec, indicating that mechanical anisotropy is strongly dependent of rock fabric. The minimum anisotropy ratio is 14% and the maximum is 24%, depend on the mechanical properties. The preferred orientations of microcracks are closely related with the directions of rock fabric. The preferred orientations of microcracks in feldspar are governed by the direction of mineralogical axis and are different from the directions of rock fabric. However, microcracks in quartz grains are very long and parallel to the directions of rock fabric, indicating that directions of rock fabric may be governed by the preferred orientations of microcracks in quartz grains. The preferred orientations of microcracks measured by differential strain analysis and microscopic observation are slightly different. That may be caused by different methodology. Lengths and numbers of microcrack are measured by microscopic observation. However, differential strain analysis measures the widths of microcracks.

• Tunnel and Underground Space
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• v.31 no.5
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• pp.309-332
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• 2021

Natural barrier systems surrounding the geological repository for the high-level radioactive waste should guarantee the hydraulic performance for preventing or delaying the leakage of radionuclide. In the case of the behavior of a crystalline rock, the hydraulic performance tends to be decided by the existence of discontinuities, so the coupled hydro-mechanical(HM) processes on the discontinuities should be characterized. The discontinuum modelling can describe the complicated behavior of discontinuities including creation, propagation, deformation and slip, so it is appropriate to model the behavior of a crystalline rock. This paper investigated the coupled HM processes in discontinuum modelling such as UDEC, 3DEC, PFC, DDA, FRACOD and TOUGH-UDEC. Block-based discontinuum methods tend to describe the HM processes based on the fluid flow through the discontinuities, and some methods are combined with another numerical tool specialized in hydraulic analysis. Particle-based discontinuum modelling describes the overall HM processes based on the fluid flow among the particles. The discontinuum methods that are currently available have limitations: exclusive simulations for two-dimension, low hydraulic simulation efficiency, fracture-dominated fluid flow and simplified hydraulic analysis, so it could be improper to the modelling the geological repository. Based on the concepts of various discontinuum modelling compiled in this paper, the advanced numerical tools for describing the accurate coupled HM processes of the deep geological repository should be developed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.17-27
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• 1991

The determination of the stress intensity factors is investigated by means of a surface integral defined around the crack tip of the structure. It has been shown in this work that this integral is derived from the standard path integral J. The use of the surface integral has also been extended to the case where body forces act. Computer program obtaining the stress intensity factors $K_I$ and $K_{II}$ is developed, which prepares input variables from the result of the conventional finite element analysis. This paper provides a parabolic smooth curve function. By the use of the function and conventional element meshes in which the aspect ratio (element length/crack length)is about 25 percent, relatively correct $K_I$ and $K_{II}$ values can be obtained for the exterior radius ranging from 1/3 to 1 of the crack length.