• Journal of Hydrogen and New Energy
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• v.24 no.6
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• pp.487-494
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• 2013

In this study, solutions for a liquid pool spreading model with continuous and instantaneous release are discussed based on the model used in the FERC's report. The effects of the release time on the liquid pool volume and radius are investigated for the continuous release. For the continuous release with the frictional resistance force in the liquid pool spreading model, the vaporization time decreases as the release time increases. On the other hand, for the continuous release without the frictional resistance force in the liquid pool spreading model, the vaporization time increases as the release time increases. These phenomena are deeply related to the pool radius. In addition, the effects of the initial pool radius for the instantaneous release in the liquid pool spreading model are discussed. For the case with the frictional resistance force in the liquid pool spreading model, as reducing release time in the model with the frictional resistance force for the continuous release, the solution for a continuous release approaches to that for an instantaneous release. On the contrary to this, the pool volume and radius for the instantaneous release without the frictional resistance force are totally different from those for the continuous release without the frictional resistance force.

• Journal of Hydrogen and New Energy
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• v.32 no.5
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• pp.365-373
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• 2021

In this study, evaporation of LN2 non-spreading pool on concrete plate was dealt with experimentally. The thermophysical properties of concrete, which is a composite material, were obtained by minimizing the difference between the numerical analysis results obtained from the assumed properties and the results from experiments. The thermal energy required for evaporation of the liquid pool is supplied from the concrete plate and the wall of the container. As a result of the measurement, the thermal energy flowing in from the wall was negligible compared to the one supplied from the concrete plate. It was found that the measured evaporation rate of the liquid pool by the heat energy supplied through the concrete plate agrees well with the PTC model except for the initial section of the experiment. The validity of the semi-infinite assumption and the one-dimensional assumption, which are the main conditions of the PTC model, was also verified through experiments. The evaporation rate model in the non-spreading pool discussed in this study can provide a basic frame for the one in the spreading pool, which is a meaningful result considering that the spreading pool is very realistic compared to the non-spreading pool.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.11_12
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• pp.692-704
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• 2005

With the improvement of computer hardware, GPUs(Graphics Processor Units) have tremendous memory bandwidth and computation power. This leads GPUs to use in general purpose computation. Especially, GPU implementation of compute-intensive physics based simulations is actively studied. In the solution of differential equations which are base of physics simulations, tridiagonal matrix systems occur repeatedly by finite-difference approximation. From the point of view of physics based simulations, fast solution of tridiagonal matrix system is important research field. We propose a fast GPU implementation for the solution of tridiagonal matrix systems. In this paper, we implement the cyclic reduction(also known as odd-even reduction) algorithm which is a popular choice for vector processors. We obtained a considerable performance improvement for solving tridiagonal matrix systems over Thomas method and conjugate gradient method. Thomas method is well known as a method for solving tridiagonal matrix systems on CPU and conjugate gradient method has shown good results on GPU. We experimented our proposed method by applying it to heat conduction, advection-diffusion, and shallow water simulations. The results of these simulations have shown a remarkable performance of over 35 frame-per-second on the 1024x1024 grid.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.50-50
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• 2018

본 연구는 국내 생육이 확인된 미기록 외래식물을 보고하고 그 특성을 기술하고자 한다. 가는잎가시상추(Lactuca saligna)는 국화과 다년생 초본이며 높이 10~65cm에 까지 자란다. 줄기에 난 잎은 피침형, 좁은피침형이며, 기부는 이저(耳底), 줄기를 반쯤 감싼다. 유라시아원산으로 지중해, 유럽온대까지 넓은 생육범위를 보인다. 한국에서는 부산, 울산 해안가 주변 공터에서 생육이 확인되었다. 부산, 울산 해안가 저지대를 중심으로 신속한 분포확산이 예상된다. 근연종인 가시상추의 국내 분포확산, 위해성 등을 고려할 때 가는잎가시상추에 대한 주의가 요구된다. 좀전동싸리(Melilotus indicus)는 해안 초지에 생육하는 일년초이며 높이 60cm까지 성장한다. 잎은 우상 3소엽, 소엽은 도란형~좁은도란형, 길이는 1~2.5cm이며 거치가 있다. 좀전동싸리는 국내생육하는 전동싸리와 매우 유사한 형태적 특성을 보인다. 좀전동싸리는 꽃의 길이 2~3mm 개화기는 4~5월이며, 전동싸리는 꽃의 길이 4~7mm 개화기는 7~11월로 차이를 보인다. 지중해, 유럽 남서부 원산으로 전세계적으로 온대 전역에 유입된 것으로 알려져 있다. 국내에서는 제주시 한림읍 옹포리 일대 해안가 저지대 공터 및 초지에서 생육이 확인되었다. 넓은 면적에서 분포하며 제주도에 정착된 것으로 판단된다. 나도뿔이삭풀은(Hainardia cylindrica) 해안 초지에 생육하는 일년초이며 높이 5~35cm까지 성장한다. 수상화서는 25cm에 이르며, 쇠뿔모양으로 단단하다. 소수는 화서 중축에 파인곳을 메우고 있으며, 길이 5~8mm 1개의 소화를 포함한다. 초형은 혁질이며 예두이다. 남아메리카원산으로 북아메리카, 호주 일본 등에 귀화되어 있다. 한국에서는 전라남도 완도군 신지면 신리 해안가 일대 공터 및 초지에 생육이 확인되었다. 나도뿔이삭풀속 Hainardia 은 국내 처음 보고되는 속이며, 뿔이삭풀과 유사한 형태적 특성으로 인해 국명을 신칭하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.607-615
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• 2009

Analysis of chloride penetration into concrete is performed considering the repeated wetting and drying conditions of tidal zone, by means of the developed finite element program which enables the diffusion-convection analysis to be conducted. Heat conduction and moisture diffusion are also included in the finite element analysis program in order that their effects to chloride penetration may be considered. For the efficiency of calculation, the analyses of temperature, relative humidity and free chloride concentration are conducted successively in that order, by treating the convection of chloride due to moisture diffusion as an source or sink term. By comparing the analysis result from finite element analysis, where main variable is a wetting and drying period, with the chloride profiles from ACI Life-365 method, it is shown that the Life-365 method gives an accurate result for the submerged zone but does not consider the differences of wetting and drying period. To obtain an accurate chloride profile in the tidal zone, it is confirmed that the diffusion-convection finite element analysis should be applied.

• Ecology and Resilient Infrastructure
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• v.3 no.3
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• pp.189-200
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• 2016

The species distribution model would be a useful tool for understanding how invasive alien species spread over the country and what environmental variables contribute to their distributions. This study is focused on the potential distribution of two invasive alien species, the common ragweed (Ambrosia artemisiifolia) and knotgrass (Paspalum distichum) in the Korean Peninsula. The maximum entropy (Maxent) model was used for the prediction of their distribution by inferring their climatic environmental requirements from localities where they are currently known to occur. We obtained their presence data from the Global Biodiversity Information Facility and the Korean plant species databases and bioclimatic data from the WorldClim dataset. As a results of the modelling, the potential distribution predicted by global occurrence data was more accurate than that by native occurrence data. The variables determining the common ragweed distribution were precipitation of the driest month and annual mean temperature. Both annual and the coldest quarter mean temperatures were critical factors in determining the knotgrass distribution. The Maxent model could be a useful tool for the prediction of alien species invasion and the management of their expansion.

• Journal of Hydrogen and New Energy
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• v.21 no.6
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• pp.513-518
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• 2010

In the present work the second-order perturbation solutions of the simple physical model for liquid pool spreading is obtained for the case of instantaneous spill. To generalize the solution governing equations are non-dimensionalized, and two dimensionless parameters, dimensionless evaporation rate and aspect ratio of the initial pool, are identified to control the governing equations. The dimensional governing equations have three parameters. The second-order solution improves fairly the first-order solution for the pool volume.

• Review of KIISC
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• v.23 no.3
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• pp.14-18
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• 2013

클라우드 컴퓨팅 서비스는 클라우드 서비스 고객에게 편리하면서도 온디맨드 (on-demand) 방식으로 풀 형태로 준비되어 있는 공유 자원 (네트워크, 서버, 메모리, 어플리케이션, 그리고 서비스) 을 제공한다. 클라우드 컴퓨팅 서비스의 확산을 위해서 가장 우려되는 것은 보안 위협과 클라우드 서비스 고객의 정보 통제권 상실과 개인정보 유출 등의 프라이버시 이슈이다. 클라우드 컴퓨팅 보안을 위한 국제 표준화 활동은 두 개의 공적 표준화 기구인 국제전기통신연합-전기통신표준화부문 연구반 17 (ITU-T SG 17) [1]과 국제표준화기구/국제전기표준화위원회 합동기술위원회 1 연구그룹 27(ISO/IEC JTC 1/SC 27) [3] 에서 주로 수행되고 있다. 본 논문에서는 클라우드 컴퓨팅 보안을 위해 양대 공적 국제 표준화 기구에서 추진 중인 동향을 제시하고, 이를 근거로 향후 표준화 추진 방향을 제시하고자 한다.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.769-777
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• 2023

Globalization has brought about rapid economic, technological, and cultural changes. In order for countries around the world to communicate, recognize and understand globalization, creativity or planning ability can be used to code. In this paper, we would like to present and prove a data analysis that can solve world problems. In the global market, the value of goods or services increases with connectivity. This connection is becoming one of the factors that increase the value of culture. Changes taking this into account promoted cultural spread and innovative growth, and increased productivity and competitiveness in each region of the world. This paper compares the income of the middle class in the United States on the impact of globalization and anti-globalization on cultural spread and innovative growth. Globalization has created an environment in which various elements of K-culture can interact and spread. Through the Internet, social media, and international travel, globalization has had a positive impact on Korea's innovative growth. In areas such as economic activity, technological innovation, and creative industries, globalization has facilitated new tech and approaches, Through this, it changed the existing economic model and contributed to exports K-culture with a new middle class model. However, globalization in the cultural industry can result in the loss of regional characteristics & individuality, which can lead to the middle class cultural unification and alienation(chasm). As a result of the empirical analysis of K-exports for the middle income in the United States, cultural diffusion and innovation must be developed even in anti-globalization. With these industrial changes the soft power value of the Korean Wave proves that it can create value for use for the middle class of major exporting countries.

• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.619-629
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• 2015

The train conflict resolution problem refers to an adjustment of the train operation schedule in order to minimize the delay propagation when a train conflict is predicted or when a train conflict occurs. Previous train studies of train conflict resolutions are limited in terms of the size of the problems to be solved due to exponential increases in the variables. In this paper, we propose a train conflict resolution model using a time-space network to solve the train conflict situation in the operational phase. The proposed model adjusts the size of the problem by giving only the dwell tolerance in the time-space network only for stops at the station after a train conflict. In addition, the proposed model can solve large problems using a path flow variable. The study presents a train delay propagation analysis and experimental results of train conflict resolution assessments as well using the proposed model.