• Journal of Korea Water Resources Association
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• v.39 no.10 s.171
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• pp.833-844
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• 2006

The objective of this study is to evaluate the snowmelt effects on the hydrological components, especially on the runoff, by using the soil water assessment tool(SWAT) which is a continuous semi-distributed long term rainfall-runoff model. The model was applied to the basin located in the upstream of the Chungju Dam. Some parameters in the snowmelt algorithm were estimated for the Chungju basin in order to reflect the snowmelt effects. The snowmelt effects were assessed by comparing the simulated runoff with the observed runoff data at the outlet of the basin. It was found out that the simulated runoff with considering the snowmelt component matches more satisfactorily to the observed one than without considering snowmelt effect. The simulation results revealed that the snowmelt effects were noticeable on March and April. Similar results were obtained at other two upstream gauging points. The effect of the elevation bands which distribute temperature and precipitation with elevation was analyzed. This study also showed that the snowmelt effect significantly affects the temporal distribution as well as quantity of the hydrological components. The simulated runoff was very sensitive to the change of temperature near the threshold temperature which the snowmelt can occur. However, the reason was not accounted for this paper, Therefore, further analyses related to this feature are needed.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.4
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• pp.57-66
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• 2009

수학적 모델은 수량과 수질의 예측을 위해 현장 조사의 대안으로 사용되어지며 이러한 모델의 사용과 실측에 불확실성이 존재하게 된다. 불확실성에 대한 많은 연구들이 진행되어 왔으나 시나리오에 의한 모델링 과정에서 발생하는 불확실성에 대한 연구는 미흡한 실정이다. 본 연구에서는 산림이 농경지와 목초지로의 변화에 따른 시나리오를 설계한 후 시나리오 적용에 따른 SWAT (Soil and Water Assessment Tool) 매개변수의 불확실성을 분석하고자 하였다. 몬테카를로 기법 (Monte Carlo simulation)을 이용하여 각 매개변수별 1,000개의 난수를 발생하였으며 앙상블 유량모의 기법을 이용하여 미국 Alabama주 카하바강 상류 (50,967ha)를 대상으로 각 난수별 100개의 유량을 통해 불확실성을 분석하였다. 분석 결과 산림지역이 농경지와 목초지로 변화 되었을 때 유출량이 증가하는 것으로 분석되었으며, 임야가 목초지 보다 농경지로 변화되었을 때 유출량은 더욱 증가하는 것으로 나타났다. 각 시나리오별 SWAT 매개변수의 불확실성은 AWC (Available water capacity), CN (Curve number), GWREVAP (groundwater re-evaporation coeffeicient), REVAPMN (minimum depth of water in shallow aquifer for re-evaporation to occur)순으로 크게 나타났으며, Ksat (Saturated hydraulic conductivity)와 ESCO(Soil evaporation compensation factor)는 유출량의 변화에 큰 영향을 미치지 못하는 것으로 분석되었다. 토지피복별 산림 면적이 클 경우 불확실성이 크게 나타나 산림이 목초지와 농경지로 변함에 따라 불확실성은 감소하는 것으로 나타났다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.1234-1249
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• 2017

One of the difficulties developers encounter in maintaining tasks of a large-scale software system is the updating of suitable libraries on time. Developers tend to miss or make mistakes when searching for and choosing libraries during the development process, or there may not be a stable library for the developers to use. We present a novel approach for helping developers modify software easily and on time and avoid software failures. Using a tool previously built by us called GPES, we collected information of projects, such as abstract syntax trees, tokens, software metrics, relations, and evolutions, for our experiments. We analyzed the contexts of source codes in existing projects to predict changes automatically and to recommend suitable libraries for the projects. The collected data show that researchers can reduce the overall cost of data analysis by transforming the extracted data into the required input formats with a simple query-based implementation. Also, we manually evaluated how the extracted contexts are similar to the description and we found that a sufficient number of the words in the contexts is similar and it might help developers grasp the domain of the source codes easily.

• The Journal of the Korea Contents Association
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• v.13 no.10
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• pp.92-102
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• 2013

The definition of mobile phone was a device that can make and receive telephone calls or messages for communication but it has rapidly developed from communication tool into multi-function device. Especially since release of smart phone, Korea is one of the highest country in the world and the statistics can be interpreted into people positively accept new technology. Therefore it's time to study on usage behavior according to different generation of mobile phone. Based on media richness theory and elaboration likelihood model, we analyzed factors affecting usage behavior of mobile phone. Case study methodology were constructed a survey to female university students from 20-24 years of age.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.752-759
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• 2012

This paper presents a mission orbit design method for spacecraft which use the sun-synchronous and ground repeat orbits. In this work, we have proposed a new design procedure, "Nonlinear simulation-based numerical optimization technique" using the commercial S/W's such as STK (Satellite Tool kit) and Matlab, which are widely adopted S/W's in the area of orbital mechanics and engineering analysis. Inclusion of all the perturbation effects on the spacecraft not only can more precisely satisfy the mission requirements for sun-synchronicity and repeated ground track, and also operational requirements such as minimum change in the S/C local time, maximization of the contact time with a specified ground station, etc. can be appropriately considered. Design examples for LEO sun-synchronous mission are presented to demonstrate the usefulness of the proposed method in this paper.

• Journal of Energy Engineering
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• v.29 no.1
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• pp.25-33
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• 2020

Recently, as the mandatory policy of zero energy building is promoted, policies / systems for transition to Zero Energy School are being promoted, but there is no method to systematically analyze and verify the results of energy saving activities for school buildings. For the study of energy performance verification methodology, the current status of related standards was referred to, and the case study of other methodologies was conducted to examine the tools that can analyze the performance in the field. In addition, this study analyzed the current status and characteristics of energy management through domestic school visits. In this paper, we presented various energy saving projects such as air conditioning and heating facilities, lighting, insulation, change operation behavior, and improve operation methods in new and existing school buildings, and M & V methods for verifying energy savings before and after implementation of energy conservation projects.

• The Mathematical Education
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• v.45 no.2 s.113
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• pp.191-204
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• 2006

Computer technology has a potential to change the contents of school mathematics and the way of teaching mathematics. But in our country, the problem whether computer technology should be introduced into mathematics classroom or not was not resolved yet. As a tool, computer technology can be used by teachers who are confident of the effectiveness and who can use it skillfully and can help students to understand mathematics. The purpose of this study was to investigate the effective way to introduce and utilize computer technology based on the status quo of mathematics classroom setting. One possible way to utilize computer technology in mathematics classroom in spite of the lack of computer and the inaccessibility of useful software is using domain specific simulation software like 'Polyhedron'. 'Polyhedron', as we can guess from the name, can be used to explore regular and semi regular polyhedra and the relationship between them. Its functions are limited but it can visualize regular polyhedra, transform regular polyhedra into other polyhedra. So it is easier to operate than other dynamic geometry software like GSP. To investigate the effect of using this software in mathematics class, three classes(one in 6th grade from science education institute for the gifted, two in 7th grade) were chosen. Activities focused on the relationship between regular and semi regular polyhedra. After the class, several conclusions were drawn from the observation. First, 'Polyhedron' can be used effectively to explore the relationship between regular and semi regular polyhedra. Second, 'Polyhedron' can motivate students. Third, Students can understand the duality of polyhedra. Fourth, Students can visualize various polyhedra by reasoning. To help teachers in using technology, web sites like NCTM's illuminations and NLVM of Utah university need to be developed.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.4
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• pp.97-104
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• 2012

Recent climate change has increased the occurrence of flood disaster. There are two approaches to prevent flooding damage. One is a structural method and the other is a non-structural method. The production and usage of a flood risk map are the example of non-structural way. The flood risk map displays several kinds of information to minimize casualties and property damage caused from flooding. In order to increase the usage of current flood risk maps and improve intuitive recognition of flood information, this paper produced flood risk maps based on geo-spatial information system using three dimensional virtual reality techniques and investigated the applicability of the maps. Because flood information is easily accessed through online, flood risk maps suggested in this paper are regarded as an efficient tool.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.4
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• pp.55-65
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• 2012

The purpose of this study is to construct the System Dynamics Model that can analyze urban spatial and temporal change and suggest the policy directions applicable to U-City Planning in Busan based on the SD model. It reviews previous literatures to elicit U-City issues and performs the case study to simulate urban spatial and temporal changes in Busan. The elicited results are connected into the policy directions of U-City planning. It emphasizes the necessity of business model suggestion based on U-City technology and industry not a tool, the U-City model construction that linkages and integrates the existing cities and new cities, and the excavation of U-City service model reflecting social and demographic changes.

• Journal of Families and Better Life
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• v.31 no.6
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• pp.97-112
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• 2013

This study was conducted to investigate the effect of sandplay therapy for couples on the self-differentiation, and heterosexual relationship satisfaction, of couples who are college students'. The subjects were four couples who are college students living in Seoul with low self-differentiation and heterosexual relationship satisfaction. I carried out sandplay therapy on four couples for once a week for 10 weeks, and each session was 70 minutes long. In this study, the self-differentiation scale was modified for Korea on the basis of Bowen's family systems theory (1976), and it was used as a research tool. Yu (2000) and Lee (2000) made a scale to measure heterosexual relationship satisfaction after they adjusted the Korea Marital Satisfaction Inventory (K-MSI). The scale was also used in order to compare pre-therapy and post-therapy traits and identify any changes. In addition, the group's behavior and interactions were observed and recorded in each session throughout the process of sandplay therapy with the couples, and the behanior and interactions were analyzed along with the change flow in the sand trays. The study's outcomes are summed up as follows. First, sandplay therapy with couples advances the level of self-differentiation in college students. Second, sandplay therapy with couples improves the heterosexual relationship satisfaction on college students. Third, the trays used in sandplay therapy with couples showed positive changes as the therapy progressed. As the sessions continued, negative factors in the trays decreased and the trays converged into one. As the sessions proceeded, it was observed that the couples became closer, felt more comfortable with each other, compromised and reflected on their relationship. The study's results show that sandplay therapy with couples increased the level of self-differentiation in college students and heterosexual relationship satisfaction, thus proving the therapy's effectiveness.