• Tunnel and Underground Space
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• v.16 no.4 s.63
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• pp.281-287
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• 2006

Intake of groundwater by tunneling in a mountainous area mostly results from groundwater flow through fractured parts of total rock mass. For reasonable analysis of this phenomenon the representative joint groups 1, 2, and 3 have been selected by previous investigations, geological/geophysical field tests and boring works. Three dimensional fractures were generated by the FracMan and MAFIC which is a three dimensional finite element model has been used to analyse a groundwater flow through fractured media. Monte Carlo simulation was applied to reduce the uncertainty of this study. The numerical results showed that the average and deviation of amounts of groundwater intaked into tunnel per unit length were $5.40{\times}10^{-1}$ and $3.04{\times}10^{-1}m^3/min/km$. It is concluded that tunnel would be stable on impact of groundwater environment by tunneling because of the lower value than $2.00{\sim}3.00m^3/min/km$ as previous and present standard on the application of tunnel construction.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.677-692
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• 2009

In recent years, lots of studies on the planetary rover systems have been performed around space advanced agencies such as NASA, ESA, JAXA, etc. Among the various technologies for the planetary rover system, the mobility system, navigation algorithm, and scientific payload have been focused particularly. In this paper, the conceptual design for a ground-based model of planetary rover's mobility system to evaluate mobility and moving stability on ground is presented. The status of overseas research and development of the planetary rover systems is also addressed in terms of technical issues. And then, the requirements of the planetary rover's mobility system are derived by means of considering mobility and stability. The designed rover's mobility system has an active suspension with 6 legs that controls 6 joints on the each leg in order to achieve high stability and mobility. This kind of mobility system has already applied to the ATHELE of NASA for various purposes such as transportation and habitation for human lunar exploration activities in the near future (i.e., Constellation program). However, the proposed system has been designed by focusing on the small-sized unmanned explorations, which may be applied for the future Korea Lunar exploration missions. Therefore, we expect that this study will be an useful reference and experience in order to develop the planetary exploration rover system in Korea.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.608-611
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• 2003

선진국입을 목전에 둔 한국경제의 발전을 위해서 지식과 기술을 기반으로 한 벤처기업의 생성과 발전은 매우 중요한 요소라 할 수 있다. 민과 관의 적절한 벤처 투자는 미래의 기업가들에게 신지식 창조의 동기를 부여하고 성장, 발전단계에 있는 기업들에게 자본을 공급함으로써 미래의 산업을 창조하는 매우 중요한 활동이다. 국내외적으로 벤처 투자자본에 대한 연구가 활발히 진행되어 왔으나 재무론을 바탕으로 한 벤처투자에 관한 연구와 다양한 벤처투자자본들의 유형과 투자행태 등을 설문지를 통해 밝혀내는 탐색적 연구들에 국한되어 연구, 발표되고 있는 실정이다. 본 연구에서는 벤처자본시장의 대표적 투자자본인 사적 창업투자회사와 정부 벤처정책투자 간의 전략적 상호작용을 가격모델을 통해 고찰하였다. Bertrand paradox의 가정에서 기술한 바와 같이 정부 벤처정책투자간 민간 창업투자회사들과 같은 투자전략을 구사하면 민간 창업투자회사들은 시장에서 살아남기 어렵고 결과적으로 정부는 벤처기업의 생성 및 발전지원이라는 목적에 부합되지 않은 투자를 한 것이 된다. Hotelling(1929)의 위치차별모델이 역설하는 바와 같이 정부 벤처정책투자는 사적 창업투자회사가 지향하는 투자와는 다른 투자정책을 구사할 때만 벤처기업 육성이라는 목표를 효율적으로 수행할 수가 있을 것이다. 이 연구 논문에서는 다양한 투자변수에 대한 Nash Equibrium이 존재함을 증명함으로써 사적 창업투자회사와 정부의 벤처정책투자가 벤처기업의 육성이라는 목적에 맞는 효율적 투자를 하기 위해 취해야 할 투자 전략들을 밝혀내었다.가 있는 것 같다. 따라서 본 연구에서는 웹기반 쇼핑시스템의 확산에 관련된 균형된 분석을 수행하기 위하여 경영(management)과 기술 (technology)을 조화롭게 고려한 관점에서 연구를 수행하고자 한다. 즉, 본 논문에서는 기술적 측면(technical aspect)과 경영적 측면(management aspect)을 동시에 고려하여 웹기반 쇼핑시스템의 주요만 특성을 살펴보고, 향후 정보통신 기술(ICT)의 확산에 관한 연구에서 두 가지 관점의 통합적 중요성에 대하여 강조하고자 한다. 그에 덧붙여 웹기반 쇼핑시스템과 다른 정보시스템을 비교하여 전자상거래 환경에서 웹기반 쇼핑시스템의 주요만 특성들이 두가지 연구관점에서 어떻게 개념화 될 수 있는지를 고찰하고자 한다. 이러만 분석에 기반하여 본 연구에서는 기술적 측면과 경영적인 측면을 동시에 고려한 웹기반 쇼핑시스템의 특성을 제시하고자 한다. 결론적으로 본 연구의 목적은 본 논문에서 적용한 기술(technical)과 경영(management)의 조화로운 연구관점이 향후 정보통신 기술이나 시스템, 그리고 전자상거래에 관련된 일련의 연구에 적응되어 보다 균형잡힌 논의와 분석이 이루어 질 수 있는 시발점이 되길 기대한다.생된 $CH_{4}$를 회수하여 이용하면 대체에너지원으로 활용 가치가 높은 것으로 판단된다./207), $99.2\%$(238/240), $98.5\%$(133/135) 및 $100\%$ (313)였다. 각각 두 개의 요골동맥과 우내흉동맥에서 부

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.3
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• pp.147-154
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• 2014

In the context of an increasing need for safety in concrete structures under blast and impact loading condition, the behavior of concrete under high strain rate condition has been an important issue. Since concrete subjected to impact loading associated with high strain rate shows quite different material behavior from that in the static state, several material models are proposed and used to describe the high strain rate behavior under blast and impact loading. In the process of modelling high strain rate conditions with these material models, mesh dependency in the used finite element(FE) is the key problem because simulation results under high strain-rate condition are quite sensitive to applied FE mesh size. This paper introduces an criterion which can minimize the mesh-dependency of simulation results on the basis of the fracture energy concept, and HJC(Holmquist Johnson Cook) model is examined to trace sensitivity to the used FE mesh size. To coincide with the purpose of the perforation simulation with a concrete plate under a projectile(bullet), the residual velocities of projectile after perforation are compared. The analytical results show that the variation of residual velocity with the used FE mesh size is quite reduced and accuracy of simulation results are improved by applying a unique failure strain value determined according to the proposed criterion.

• Proceedings of the Korea Database Society Conference
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• 1998.09a
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• pp.293-312
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• 1998

$\square$ 정보화 혁명의 대국민 인식수단과 초고속정보통신망의 주요 응용 서비스로서 부각 $\square$ 전통적인 정보이용방법에 대한 이용자들의 인식의 변화로 도서관 활성화 방안으로써 정보통신기술의 도입 $\square$ 선진 각국의 전자도서관 구축의 국가적 추진 $\square$ 국내 초고속정보통신망의 구축과 보급 확대 $\square$ 모든 국민이 지역, 시간의 제약없이 도서관에 접근하여 필요한 자료를 획득 $\square$ 정보획득시간 단축으로 국내연구자들의 연구력 증진 $\square$ 정보화의 지역격차 해소 $\square$ 국내 도서관의 전자도서관 사업 촉진 $\square$ 주요 전자도서관의 통합연동체제를 마련 $\square$ 주요 도서관별 대상분야 조정으로 중복투자 방지 $\square$ 초고속정보통신망의 주요한 응용서비스로 가시화 - 초고속정보통신망의 선도적 대국민 가시화 - 이에 따른 민간부문의 참여 및 투자 촉진 $\square$ 국가, 산업, 국민생활 정보화의 주요한 기반 구축 $\square$ 지역적 정보불균형 해소 - 일부지역에 편중되어 있는 정보를 인터넷을 이용하여 시.공간 제약없이 제공함으로써 정보의 불균형 해소 $\square$ 전자도서관의 기본모델 제시 -전자도서관의 주요기능인 타기관간 자료연동 및 검색시스템을 구현함으로써 향후 구축되는 전자도서관의 기본모델 제시 $\square$ 전자도서관간 자료공유체제 구축 -시범사업 참여도서관간 분산 관리하고 있는 정보의 공유를 위한 표준체제 구축(중략) 것으로 나타났다.까지 증가율을 보여 주었다. 것으로 나타났다.대표하는 압밀계수의 추정이 가능할 것으로 사료된다. $O_3$/라는 결정학적 관계를 가지며 에피탁샬 성장했음을 알 수 있었다.있었다.다(p<0.05)..8800-0.6800로 각각 표시되었다.~$\pm$10 V의 측정범위에서 memory window가 계속 증가하는 것을 보여주었다./$^{\circ}C$의 고주파 유전특성을 얻었다. 얻었다.끼쳤다.보였다.다. 싸이클링 성능을 보였다.다.보였다.다.고 입력 반사손실을 그림 I, 2, 3에 각각 나타내었다. 대책을 요구하고 있다.하는 경향을 보였다. 생존율은 48시간째부터 폐사하기 시작하여 144시간째에는 전량폐사하였다. 삼투압 조절 능력을 위한 여러가지 파라메타에서 15 $\textperthousand$구는 이상이 없는 것으로 추측되나, 0 $\textperthousand$구에서는 코티졸, Na$^{+}$, K$^{+}$, Cl￣, 총단백질 및 AST에서 시간경과에 따른 삼투압 조절 능력에 문제가 있는 것으로 보여진다.c}C$에서 5시간 가열조리 후 잔존율은 각각 84.7% 및 73.3%였고, 질소가스 통기하에서는 잔존율이 88.9% 및 81.8%로 더욱 안정하였다.8% 및 12.44%, 201일 이상의 경우 13.17% 및 11.30%로 201일 이상의 유기의 경우에만 대조구와 삭제 구간에 유의적인(p<0.05) 차이를 나타내었다.는 담수(淡水)에서 10%o의 해수(海水)로 이주된지 14일(日) 이후에 신장(腎臟)에서 수축된 것으로 나타났다. 30%o의 해수(海水)에 적응(適應)된 틸라피아의 평균 신사구체(腎絲球體)의 면적은 담수(淡水)에 적응된 개체의 면적보다 유의성

• Journal of Korea Water Resources Association
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• v.51 no.7
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• pp.617-627
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• 2018

In this study, CMIP5 GCMs rainfall data (2011~2099) based on RCP scenarios were used to analyze the extreme drought evaluation for the future period. For prospective drought assessment, historical observations were used based on the Automated Surface Observing System (ASOS) data (1976~2010) of the Korea Meteorological Administration. Through the analysis of various indicators, such as average annual rainfall, rainy days, drought spell, and average drought severity was carried out for the drought evaluation of the five major river basins (Han river, Nakdong river, Geum river, Sumjin river, and Youngsan river) over the Korean peninsula. The GCMs that predicted the most severe future droughts are CMCC-CMS, IPSL-CM5A-LR and IPSL-CM5A-MR. Moderate future droughts were predicted from HadGEM2-CC, CMCC-CM and HadGEM2-ES. GCMs with relatively weak future drought forecasts were selected as CESM1-CAM5, MIROC-ESM-CHEM and CanESM2. The results of this study might be used as a fundamental data to choose a reasonable climate change scenario in future extreme drought evaluation.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.993-999
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• 2008

A girder height limitation is the critical parameter for rapid construction of bridge deck and construction space limitation especially in urban area such as high population area and high density habitats. A standard post-tensioned I-shaped concrete girder usually demands relatively higher girder height in order to retain sufficient moment arm between compression force and tensile force. To elaborate this issue, a small U-shaped section with wide flanges can be used as a possible replacement of I-shaped standard girder. This prestressed concrete box girder allows more flexible girder height adjustment rather than standard I-shaped post-tensioned girder plus additional torsion resistance benefits of closed section. A 30m-long, 1.7m-high and 3.63m-wide actual small prestressed concrete box girder is designed and a laboratory test for its static behaviors by applying 6,200kN amount of load in the form of 4-point bending test was performed. The load-deflection curve and crack patterns at different loading stage are recorded. In addition, to extracting the dynamic characteristics such as natural frequency and damping ratio of this girder, several excitation tests with artificial mechanical exciter with un-symmetric mass are carried out using operational frequency sweep-up. Nonlinear finite element analysis of this 4 point bending test under monotonic static load is investigated and discussed with aids of concrete damaged plasticity formulation using ABAQUS program.

• Journal of Korea Water Resources Association
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• v.52 no.8
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• pp.545-554
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• 2019

The most drought assessments are based on a drought index, which depends on univariate variables such as precipitation and soil moisture. However, there is a limitation in representing the drought conditions with single variables due to their complexity. It has been acknowledged that a multivariate drought index can more effectively describe the complex drought state. In this context, this study propose a Copula-based drought index that can jointly consider precipitation and soil moisture. Unlike precipitation data, long-term soil moisture data is not readily available so that this study utilized a Gaussian Mixture Non-Homogeneous Hidden Markov chain Model (GM-NHMM) model to simulate the soil moisture using the observed precipitation and temperature ranging from 1973 to 2014. The GM-NHMM model showed a better performance in terms of reproducing key statistics of soil moisture, compared to a multiple regression model. Finally, a bivariate frequency analysis was performed for the drought duration and severity, and it was confirmed that the recent droughts over Jeollabuk-do in 2015 have a 20-year return period.

• Smart Media Journal
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• v.9 no.4
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• pp.26-35
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• 2020

Attempts to predict future stock prices have been studied steadily since the past. However, unlike general time-series data, financial time-series data has various obstacles to making predictions such as non-stationarity, long-term dependence, and non-linearity. In addition, variables of a wide range of data have limitations in the selection by humans, and the model should be able to automatically extract variables well. In this paper, we propose a 'sliding time step normalization' method that can normalize non-stationary data and LSTM autoencoder to compress variables from all variables. and 'moving transfer learning', which divides periods and performs transfer learning. In addition, the experiment shows that the performance is superior when using as many variables as possible through the neural network rather than using only 100 major financial variables and by using 'sliding time step normalization' to normalize the non-stationarity of data in all sections, it is shown to be effective in improving performance. 'moving transfer learning' shows that it is effective in improving the performance in long test intervals by evaluating the performance of the model and performing transfer learning in the test interval for each step.

• Korean Journal of Remote Sensing
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• v.38 no.5_3
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• pp.873-885
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• 2022

The particulate matter (PM) has emerged as a hot topic around the world as it has been reported that PM is related to an increase in mortality and prevalence rates. In South Korea, the importance of PM has been recognized since the late 1990s, and various studies on PM have been conducted. This study investigated the PM research topics and trends for papers (D=2,764) published in Research Information Sharing Service (RISS) using topic modeling based on Latent Dirichlet Allocation (LDA). As a result, a total of 10 topics were identified in the whole papers, and the PM research topics were classified as 'PM reduction (Topic 1)', 'Government policy and management (Topic 2)', 'Characteristics of PM (Topic 3)', 'PM model (Topic 4)', 'Environmental education (Topic 5)', 'Bio (Topic 6)', 'Traffic (Topic 7)', 'Asian dust (Topic 8)', 'Indoor PM (Topic 9)', 'Human risk (Topic 10)'. In particular, the proportion of papers on topics 'Government policy and management (Topic 2)', 'PM model (Topic 4)', 'Environmental education (Topic 5)', and 'Bio (Topic 6)' to the toal number of papers increased over time (linear slope > 0). The results of this study provide the new literature review methodology related to particulate matter and the history and insight.