• Journal of the Korea Society of Computer and Information
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• v.20 no.5
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• pp.31-39
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• 2015

The degree-constrained minimum spanning tree (d-MST) problem is considered NP-complete for no exact solution-yielding polynomial algorithm has been proposed to. One thus has to resort to an heuristic approximate algorithm to obtain an optimal solution to this problem. This paper therefore presents a polynomial time algorithm which obtains an intial solution to the d-MST with the help of Kruskal's algorithm and performs k-opt on the initial solution obtained so as to derive the final optimal solution. When tested on 4 graphs, the algorithm has successfully obtained the optimal solutions.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.139-145
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• 2009

An analytical solution of groundwater flow is applied to design soil vacuum extraction for removing volatile organic compounds from the unsaturation zone. The governing equation of gas or vapor flow in porous media is nonlinear in that gas density depends on gas pressure. A linear equation suggested by researcher is similar to that of groundwater flow. The pressure drawdowns of confined and leaky aqufiers are calculated using Massmann's field data, and the pressure drawdowns are compared. A solution of Theis equation calculated by Massmann is modified using GASSOLVE9 program in this paper. The pressure drawdown using Hantush's analytical solution for leaky aquifer also compared to that of Massmann. Hantush's analytical solution gives good approximations to pressure drawdown.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.590-590
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• 2016

최근 기후변화로 인하여 풍수해의 발생빈도가 높아짐에 따라 자연재해 예측에 대한 연구가 활발히 진행되는 추세이다. 또한 풍수해와 관련하여 정부 및 지자체에서 재해지도를 작성하고 있으나 각 기관의 특성에 따라 개별적으로 재해지도를 시스템으로 제공하고 있다. 결국 호우, 산사태, 바람 등 각각의 재해에 대해 여러 시스템에서 자료를 제공하고 있기 때문에 필요자료, 지역 등에 따라 사용자가 시스템을 찾아 이용해야하는 불편이 존재하며 전국이 아닌 일부 지역만 제한적으로 제공되고 있다. 또한, 각 기관에서 제공되는 자료의 종류와 제공형태가 시스템별로 다르기 때문에 사용자가 추가적인 작업을 해야하는 단점이 존재한다. 국민안전처에서 추진하는 '풍수해저감 종합계획'의 활성화를 위해서 통합적인 재해지도 제공 시스템이 필요하다. 따라서 본 연구에서는 재해관련기관에서 현재 제공되고 있는 시스템에 대한 활용자료, 구성도 등의 조사, 분석을 통한 연계 전략 수립을 위한 연구를 진행하였다. 또한 풍수해 피해예측지도의 공동활용을 위한 표준연계모듈 적용방안을 제시하여 추후 풍수해 피해예측지도 구축 및 피해예측지도 작성에 활용 가능할 것으로 기대된다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.189-195
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• 2021

This paper discusses choice of loans problem(CLP) that is to minimize annual payment from which bank's borrows in multi-banks multi-nations with distinct interests. For the CLP, there is impossible to obtain the optimal solution actually without the help of mathematical software package as linear programming(LP). This paper applies the method used in transportation problem(TP) that finds initial feasible solution with selects minimum interest first, least cost method(LCM), to CLP. Result of experiment, the proposed algorithm can be obtains the optimal solution with at most two exchange optimization for LCM's initial feasible solution.

• Journal of the Korean earth science society
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• v.34 no.3
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• pp.224-234
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• 2013

This study examined a strong positive correlation between the North Atlantic Oscillation (NAO) index during June and the total tropical cyclone (TC) genesis frequency in the western North Pacific during July and August. To investigate a possible cause for this relationship, the mean difference between the highest positive NAO years and the lowest negative NAO years was analyzed by dividing into when the El Ni$\tilde{n}$o and La Ni$\tilde{n}$a years were included and when the El Ni$\tilde{n}$o and La Ni$\tilde{n}$a years were not included. When the El Ni$\tilde{n}$o and La Ni$\tilde{n}$a years were included, for the positive NAO years, the TCs mostly occurred in the northwestern region of tropical and subtropical western Pacific, and showed a pattern that migrate from the sea northeast of the Philippines, pass the East China Sea, and move toward the mid-latitudes of East Asia. In contrast, for the negative NAO years, the TCs mostly occurred in the southeastern region of tropical and subtropical western Pacific, and showed a pattern that migrate westward from the sea southeast of the Philippines, pass the South China Sea, and move toward the southern coast of China and Indochinese peninsula. These two different TC migration patterns affect the recurving location of TC, and for the positive NAO years, the recurving of TC was averagely found to take place in the further northeast. In addition, the migration patterns also affect the TC intensity, and the TCs of positive NAO years had stronger intensity than the TCs of negative NAO years as sufficient energy can be absorbed from the ocean while moving north in the mid-latitudes of East Asia. The TCs of negative NAO years showed weak intensity as they get weaken or disappear shortly while landing on the southern coast of China and the Indochinese peninsula. On the other hand, the above result of analysis is also similarly observed when the El Ni$\tilde{n}$o and La Ni$\tilde{n}$a years were not included.

• Journal of Korea Water Resources Association
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• v.33 no.3
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• pp.307-314
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• 2000

This study is to investigate the recurrence characteristics of wet and dry years using over 200 year records of annual rainfall depth including Chosun Age in Korea. As well as analyzing the correlation structure of the raw data, recurrence trends of wet and dry year has been investigated based on several truncation levels (mean, $mean{\pm}0.25stdv.,\;mean{\pm}O.5stdv.,\;mean{\pm}O.75stdv.,\;mean{\pm}stdv.$). Also the transition probability among wet, dry and normal years has been derived for the same truncation levels. and finally the average return periods based on the steady-state probabilities were obtained. This analysis has been applied to not only the entire data but also partial data set of before- and after-the long dry period around 1900 in order to compare and detect the possible difference between the Chukwooki (an old raingauge invented in Chosun age) and the modem flip-bucket style. As a result, Similar pattern of dry and wet year recurrence has been found, but the return period of extremely dry years after the dry period shown longer than that before the dry period. Assuming that the dry and wet years can be defined as $mean{\pm}$ standard deviations, respectively, the return period of the wet years is shown to be about 5~6 years and that of the dry years about 6~7 years.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.223-230
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• 2015

As the Transportation Simplex Method of the general transportation problem are inapplicable to the large-scale unbalanced transportation problem, a commercialized linear programming package remains as the only viable means. There is, however, no method made available to verify the optimality of solutions attained by the package. This paper therefore proposes a simple heuristic algorithm to the large-scale unbalanced transportation problem. From a given problem of $31{\times}15$supply and demand areas, the proposed algorithm determines the number of demands areas for each supply area and executes on the latter in the ascending order of each of their corresponding demand areas. Next, given a single corresponding demand area, it supplies the full demand volume and else, it supplies first to an area of minimum associated costs and subsequently to the rest so as to meet the demand to the fullest extent. This initial optimal value is then optimized through an adjustment process whereby costs are minimized as much as possible. When tested on the $31{\times}15$cost matrix, the proposed algorithm has obtained an optimal result improved from the commercial linear programming package by 8.9%.

• Journal of Cadastre & Land InformatiX
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• v.45 no.2
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• pp.87-100
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• 2015

Currently, Korea government has strongly recommended the storm and flood insurance system to reduce the damage caused by natural disasters. The storm and flood insurance operated by private insurance company is the type of policy insurance. and is supervised by Minister of Public Safety and Security. It is the advanced disaster management system which is able to protect the public interests through unexpected natural disaster by assisting some part of the insurance premium from a central or local government. The main purpose of the present investigation is to build the insurance object GIS DB which should be necessary to calculate the premium rate in the map for storm and flood insurance, and also, to perform GIS analysis. The service model in this study is aimed to general single house, apartment and green house. The service management plan targeting the whole country has been investigated in terms of building DB and service operation.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.429-433
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• 2003

We try to analyse the localization phenomenon of a lightwave in random media by means of considering the solution of the propagation equation on a transmission line in which the propagation constants are randomly distributed. Lightwave localization is generated at the turning point where the solution is changed suddenly from an increase to a decrease. First, in order to investigate the changing process of the solution, we have derived the approximated one-dimensional Schrodinger equation from the two-dimensional wave equation by using the Brags condition. Considering the many types of solutions of the wave equation, we have investigated the conditions that allow the solutions to exist. Also, we have investigated the relationships between the localization of the solution and the variation of the propagation constant. In case of the exponential solution, we know that the permittivity $\varepsilon$=(0,0$\varepsilon$$_{0}$) is a very important parameter to influence the phase of the lightwave and to generate the localization.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.308-320
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• 2006

An analytic solution to the mild-slope equation is derived for waves propagating over an axi-symmetric pit. The water depth inside the pit varies in proportion to a power of radial distance from the pit center. The governing equation is transformed into ordinary differential equations by using separation of variables, and the coefficients of the equations are transformed into explicit forms by using Hunt's (1979) approximate solution. Finally, by using the Frobenius series, the analytic solution is derived. Due to the feature of Hunt's equation, the present analytic solution is accurate in shallow and deep waters, while it is less accurate in intermediate depth water. The validity of the analytic solution is demonstrated by comparison with numerical solutions. The analytic solution is also used to examine the effects of pit geometry and relative depth on wave transformation.