• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.596-603
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• 2018

The traffic congestion is frequently occurring due to increasing demand for vehicles and development of subcenter in roads of domestic-downtown. The design of a Great depth underground double-deck tunnel planned for construction as a solution however it's mainly for a compact-car. Its low height and small section cause causalities when fire occurs. From this study, the delay system for fire smoke diffusion is developed to minimize the occurrence of casualties when fire occurs in the Great depth underground double-deck tunnel and the CFD(Computational Fluid Dynamics) is used to find the optimal installation interval and the blockage ratio to maximize the system effects. The study analyzed the shorter the installation interval of the system, the higher the smoke delay effect but the efficiency-change tends to be slight above a certain distance and the larger the blockage ratio, the higher the effect but the efficiency-difference is slight according to installation interval.

• Construction Engineering and Management
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• v.2 no.1 s.5
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• pp.8-11
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• 2001

요즘 매스컴에서 건설회사 도산 및 부실 등에 대한 보도가 많아지고 있다. 98년 말부터 우려해 오던 건설산업 구조조정이 한창 진행 중에 있으며, 2000년 7월말 현재 100대 건설사중 37개사가 법정관리, 화의, 워크아웃 상태이며, 이후 대형건설업체의 계속되는 부도 등 부실화로 인한 퇴출이 더욱 가속되고 있는 상황이다. 이렇게 건설 회사들이 부실화가 된 원인을 살펴보면, 공사 발주물량은 97년 대비 70{\%}대에 머물고 있는 반면 건설업체 수는 오히려 $60{\%} 정도 증가해 업체별 평균 수주액이 급감하였고, 이에 따라 업체들의 과당 출혈 경쟁으로 수익성이 악화되고 말았다. 그러나 이러한 건설업의 어려운 환경에서도 고려개발(주)는 2000년 당기순이익 176억원 등 ‘89년 이후 12년 동안 순익을 내고 있으며, IMF가 한창이던 98년부터 2000년까지 약 1조2천억원의 수주고를 달성하였다. 또한 2000년 부채비율 $146{\%}$, 자기자본비율 $41{\%}$, 자기자본순이익율 $14{\%}$로 선진건설업체 수준의 재무비율을 확보하여 경영평가 1위를 차지하고 있다. 이러한 원인을 고려개발(주)는 건설산업의 구조조정에서 살아남을 수 있는 해결책은 정보화라고 판단하여 지난 ’95년부터 꾸준히 사내 정보화 정착에 전력하고 있다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.4
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• pp.249-256
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• 2011

Lagrangian particle transport model coupled with the EFDC have been performed to estimate the residence time and water exchange rate by release time of pollutants over a tidal cycle in Masan Bay. The modelled residence time for the whole bay was about 40 days, ranging from less than 20 days in the southern parts of Budo, to over 100 days in the upper parts of Somodo. The spatial difference of residence time was controlled by tidal residual currents and the distance to the bay channel. The area mean residence time during spring and neap tides was estimated to be about 36 days and 42 days, respectively. The time required for 30% exchange of water was calculated as ranging from 65 to 105 days by release time of pollutants.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3465-3472
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• 2009

The aims of this study is to medical record data warehouse which had been collected from hospital information systems. continuous patient 2,118 60.5%, informally patient 1,385 39.5%. In using survival factors sex, age, area, insurance, admission-course, medical treatment, out-patient lesson, out-patient form, conference diagnosis, operation, cancer, medical reservation. As a result of making a predictive modeling using the logistic regression, the fitness of the predictive modeling of informally patient was 66.0% and neural network, the predictive was 66.72% and CHAID, the predictive was 63.25%, which is a data mining. The expected modeling of the informally patients, the hospital through the continuous patient management and trust of hospital.

• Resources Recycling
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• v.13 no.1
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• pp.39-46
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• 2004

Triboelectrostatic separation process is a technology that different particles charged after contact and rubbing different materials are separated in a high electric field. This technology has an advantage in that it can be used for separating non-conducting materials such as plastics unlike other electrostatic separation processes. There are two objectives in this study. One is to develop an effective continuous tribo-electrostatic separation process. The other is to apply the developed device for the separation of mixed plastics. Results show that almost all tested plastics reaches over 95% in yield and grade after separation.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.84-84
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• 2011

RF magnetron sputtering을 이용하여 산소 유량에 따라 ZnO 박막을 유리기판 위에 제작하고 구조적, 광학적, 전기적 특성을 조사하였다. 박막 증착 조건의 초기 압력은 $1.0{\times}10^{-6}Torr$, RF 파워는 100W, 증착온도는 상온으로 고정하였으며 기판은 Corning 1737 유리 기판을 사용하였다. 공정 변수로 Ar:$O_2$가스 비율을 50:50 sccm, 75:25 sccm, 100:0 sccm으로 변화시켰다. 유리기판 위에 증착된 모든 ZnO 박막에서 (002) 면의 우선배향성이 관찰되었고 85% 이상의 투과율을 나타내었다. 산소유량이 적을수록 ZnO 박막의 결정성은 향상되었고, 광학적 밴드갭은 증가하였다. Hall 측정 결과 산소의 유량이 포함되어 있는 박막에서는 모두 완전한 산화물에 가까운 화학양론적 조성으로 면 저항이 $10^6{\Omega}/{\square}$ 이상인 부도체 특성을 보였으며, 산소가 포함되지 않은 샘플에서는 n타입의 반도체 특성이 확인되었다. 산소가 포함되지 않은 Ar 유량이 100sccm일 때 전기비저항 $3.56{\times}10^{+1}1{\Omega}cm$, 전하의 농도 $2.04{\times}10^{18}cm^{-3}$, 이동도 $8.59cm^2V^{-1}s^{-1}$로 반도체 활성층으로 적합한 전기적 특성을 얻었다. ZnO 박막의 경우 산소가 포함될 경우 결정성이 저하되고, 절연특성을 갖는 것을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.230-230
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• 2011

RF magnetron sputtering을 이용하여 Ar 및 $O_2$유량에 따라 GZO 박막을 유리기판 위에 제작하고 구조적, 광학적, 전기적 특성을 조사하였다. 박막 증착 조건의 초기 압력은 $1.0{\times}10^{-6}$ Torr, RF 파워는 25W, 증착온도는 상온으로 고정하였으며 기판은 Corning 1737 유리 기판을 사용하였다. 공정 변수로 Ar 유량을 40 sccm, 60 sccm, 80 sccm, 100 sccm으로 변화시켰으며, $O_2$ 가스비율을 5~20%으로 변화를 주어 실험을 진행하였다. GZO 타겟은 ZnO,Ga 분말을 각각 97:3 wt.%로 소결된 타겟을 사용하였다. 유리기판 위에 증착된 모든 GZO 박막에서 (002) 면의 우선 배향성이 관찰되었고 평균 85% 이상의 투과율을 나타내었다. 산소유량이 포함되지 않고 Ar 유량이 적은 GZO 박막의 결정성은 향상되었고, 광학적 밴드갭은 증가하였다. Hall 측정 결과 산소의 유량이 포함되어 있는 박막에서는 모두 완전한 산화물에 가까운 화학양론적 조성으로 면저항이 $10^6{\Omega}/{\Box}$ 이상인 부도체 특성을 보였으며, 산소가 포함되지 않은 샘플에서는 투명전도막 특성이 확인되었다. 산소가 포함되지 않은 Ar 유량이 60 sccm일 때 전기비저항 $3.25{\times}10^{-3}{\Omega}cm$, 전하의 농도 $9.41{\times}10^{20}\;cm^{-3}$, 이동도 2.04 $cm^2V^{-1}s^{-1}$로 투명전도막으로 적합한 전기적 특성을 얻었다. GZO 박막의 경우 산소가 포함될 경우 결정성이 저하되고, 절연특성을 갖는 것을 확인할 수 있었다.

• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.464-471
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• 2009

Vegetation types of the native conifer forests in the ridge of the Baekdudaegan, South Korea, were classified using the Braun-Blanquet method and TWINSPAN and its ecological characteristics analyzed with special repect to floristic composition. The vegetation type was classified into two types (Pinus densiflora-Carex humilis and Pinus koraiensis-Dryopteris crassirhizoma types) and seven groups. Mean species richness and total plot cover per unit area ($/100m^2$) were $21.9{\pm}8.9$ spp. and $146.9{\pm}32.3$%, respectively. The plant species composed of 82 families, 217 genera, and 387 species and the three major families, Compositae, Liliaceae, and Rosaceae, made up about 25.6% of the total species. The 7.8% of total families were the families with occurrence of only one species. The highest relative importance value was 19.2, the species belonged to Pinaceae and the pattern was different from species richness pattern of other families.

• Journal of the Korean Data and Information Science Society
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• v.22 no.6
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• pp.1017-1028
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• 2011

When it is not easy to decide the credit scoring for some loan applicants, credit evaluation is postponded and reserve to ask a specialist for further evaluation of undecided applicants. This undecided inference is one of problems that happen to most statistical models including the biostatistics and sportal statistics as well as credit evaluation area. In this work, the undecided inference is regarded as a missing data mechanism under the assumption of MNAR, and use the bivariate probit model which is one of sample selection models. Two undecided inference methods are proposed: one is to make use of characteristic variables to represent the state for decided applicants, and the other is that more accurate and additional informations are collected and apply these new variables. With an illustrated example, misclassification error rates for undecided and overall applicants are obtainded and compared according to various characteristic variables, undecided intervals, and thresholds. It is found that misclassification error rates could be reduced when the undecided interval is increased and more accurate information is put to model, since more accurate situation of decided applications are reflected in the bivariate probit model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1221-1227
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• 2015

Diffusion bonding is the key manufacturing process for the micro-channel type heat exchangers. In this study, austenitic alloys such as Alloy 800HT, Alloy 690, and Alloy 600, were diffusion bonded at various temperatures and the tensile properties were measured up to $650^{\circ}C$. Tensile ductility of diffusion bonded Alloy 800HT was significantly lower than that of base metal at all test temperatures. While, for Alloy 690 and Alloy 600, tensile ductility of diffusion bonded specimens was comparable to that of base metals up to $500^{\circ}C$, above which the ductility became lower. The poor ductility of diffusion bonded specimen could have caused by the incomplete grain boundary migration and precipitates along the bond-line. Application of post-bond heat treatment (PBHT) improved the ductility close to that of base metals up to $550^{\circ}C$. Changes in tensile properties were discussed in view of the microstructure in the diffusion-bonded area.