• Journal of KIISE:Databases
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• v.30 no.3
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• pp.296-309
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• 2003

One of commercial applications of mobile computing is ATIS(Advanced Traveler Information Systems) in ITS(Intelligent Transport Systems). In ATIS, a primary mobile computing task is to compute the shortest path from the current location to the destination. In this paper, we have studied the shortest path re-computation problem that arises in the DRGS(Dynamic Route Guidance System) in ATIS where the cost of topological digital road map is frequently updated as traffic condition changes dynamically. Previously suggested methods either re-compute the shortest path from scratch or re-compute the shortest path just between the two end nodes of the edge where the cost change occurs. However, these methods we trivial in that they do not intelligently utilize the previously computed shortest path information. In this paper, we propose an efficient approximate shortest path re-computation method based on the dynamic window scheme. The proposed method re-computes an approximate shortest path very quickly by utilizing the previously computed shortest path information. We first show the theoretical analysis of our methods and then present an in-depth experimental performance analysis by implementing it on grid graphs as well as a real digital road map.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.400-409
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• 2016

The geospatial information industry has the advantage of being able to converge with other industries to create new value. Therefore, efforts are underway to promote the growth of this dwindling national industry by endorsing policies and initiatives to promote its convergence with other industries. In this study, feedback was collected from experts in various fields through three rounds of polls using the Delphi method. The poll results were used to investigate the causes of hindrance to the growth of the geospatial information industry and to build a comprehensive solution to this problem. As a result, 27 strategies were constructed based on the users' requirements related to policy, data and service, including the demands for establishing public polling methods, enhancing data quality and advertisement. Since the coefficient of variance fell between 0.11 and 0.20 in the importance evaluation, an amicable consensus was reached between the experts. Considering that the convergence of industries is achieved through the integration of various types of technology and information, it is important to consider the requirements of users in different industries. In this respect, the results of this study will serve as a useful base for constructing mid-to-long term road maps to promote the development of the geospatial information industry.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.585-591
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• 2003

Recently, South korea is driving forward the strategy concerning of the logistics center of northeast asia aggressively on the purpose of promoting Busan port & Gwangyang port to the hub-port of northeast asia, In that situation, it is significant that the meaning, construction connecting between south and north railway. Namely, That is the reason why Busan port is satisfied with the combined transport system of not only marine transportation but also railway transportation completely, However, the research and policy is only focused on the connection of north-south railway so far. The ability of Buans railway equipment as the actual role of origin-destination point of TKR(Trans Korean Railway), was not reviewed. Therefore, this research is shown the problem and reality of the railway transport concerning the centralization of Busan port, and the capacity of Busan port railway facility regarding the increase of future container quantity is reviewed and analyzed Moreover, the object, shown the importance of facility expansion such as Gungbu Trans Express between Daegu and Busan and the improvement scheme for railway transportation activation through the analysis of society cost and the logistics cost of the ability of railway facility, is set up.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2627-2640
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• 1998

In this paper, we analyze the performance of the virtual cell system[1] for the transmission of IP datagrams in mobile computer communications. A virtual cell consistsof a group of physical cells shose base stationsl are implemented b recote bridges and interconnected via high speed datagram packet switched networks. Host mobility is supported at the data link layer using the distributed hierachical location information of mobile hosts. Given mobility and communication ptems among physical cells, the problem of deploying virtual cells is equivalent to the optimization cost for the entire system where interclster communication is more expesive than intracluster communication[2]. Once an iptimal partitionof disjoint clusters is obtained, we deploy the virtual cell system according to the topology of the optimal partition such that each virtual cell correspods to a cluser. To analyze the performance of the virtual cell system, we adopt a BCMP open multipel class queueing network model. In addition to mobility and communication patterns, among physical cells, the topology of the virtual cell system is used to determine service transition probabilities of the queueing network model. With various system parameters, we conduct interesting sensitivity analyses to determine network design tradeoffs. The first application of the proposed model is to determine an adequate network bandwidth for base station networking such that the networks would not become an bottleneck. We also evaluate the network vlilization and system response time due to various types of messages. For instance, when the mobile hosts begin moving fast, the migration rate will be increased. This results of the performance analysis provide a good evidence in demonsratc the sysem effciency under different assumptions of mobility and communication patterns.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.339-344
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• 2016

Since transmissions of large amounts of data are frequent, users require more bandwidth, and the need for communications networks having greater bandwidth is increasing. One communications network satisfying this need is an optical communications network. Therefore, studies to increase the transmission capacity of optical communications systems have been carried out. However, in a general optical communications system, a signal transmitted through optical fiber (a transmission medium) is detected through direct detection in the receiving system. This method has a disadvantage in that the entire bandwidth of the optical signal cannot be utilized. Also, when transmitting an optical signal, there is a problem where the signal-to-noise ratio is affected by neighboring channels. To overcome this situation, various studies are being conducted to minimize the influence of external interference and noise. This paper overcomes the situation by transmitting spectrum-sliced signals using the digital transmission system, FSK. Analyzing the characteristics of the signals detected in the receiver of the optical communications system, Gaussian distribution is used for the PDF of the spectrum-sliced signal, and the signal at the receiving end of the optical communications system is assumed to have a k-square distribution. The results of the analysis confirmed it is better to transmit the spectrally divided signal rather than transmit the laser source.

• Journal of KIISE:Databases
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• v.37 no.2
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• pp.71-81
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• 2010

The problem of finding clusters is widely used in numerous applications, such as pattern recognition, image analysis, market analysis. The important factors that decide cluster quality are the similarity measure and the number of attributes. Similarity measures should be defined with respect to the data types. Existing similarity measures are well applicable to numerical attribute values. However, those measures do not work well when the data is described by categorical attributes, that is, when no inherent similarity measure between values. In high dimensional spaces, conventional clustering algorithms tend to break down because of sparsity of data points. To overcome this difficulty, a subspace clustering approach has been proposed. It is based on the observation that different clusters may exist in different subspaces. In this paper, we propose a new similarity measure for clustering of high dimensional categorical data. The measure is defined based on the fact that a good clustering is one where each cluster should have certain information that can distinguish it with other clusters. We also try to capture on the attribute dependencies. This study is meaningful because there has been no method to use both of them. Experimental results on real datasets show clusters obtained by our proposed similarity measure are good enough with respect to clustering accuracy.

• The KIPS Transactions:PartB
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• v.16B no.5
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• pp.385-394
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• 2009

Face tracking and recognition are difficult problems because the face is a non-rigid object. The main reasons for the failure to track and recognize the faces are the changes of a face pose and environmental illumination. To solve these problems, we propose a nonlinear manifold framework for the face pose and the face illumination normalization processing. Specifically, to track and recognize a face on the video that has various pose variations, we approximate a face pose density to single Gaussian density by PCA(Principle Component Analysis) using images sampled from training video sequences and then construct the GMM(Gaussian Mixture Model) for each person. To solve the illumination problem for the face tracking and recognition, we decompose the face images into the reflectance and the illuminance using the SSR(Single Scale Retinex) model. To obtain the normalized reflectance, the reflectance is rescaled by histogram equalization on the defined range. We newly approximate the illuminance by the trained manifold since the illuminance has almost variations by illumination. By combining these two features into our manifold framework, we derived the efficient face tracking and recognition results on indoor and outdoor video. To improve the video based tracking results, we update the weights of each face pose density at each frame by the tracking result at the previous frame using EM algorithm. Our experimental results show that our method is more efficient than other methods.

• Water for future
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• v.16 no.4
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• pp.245-252
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• 1983

Recently river water pollution in Korea is given rise to serious problem in aspect of crop production, drinking well, water contamination and etc. Under these urgent situations, it is prime importance to protect water resources from pollutants. An environmental isotope survey of the groundwater form the shallow alluvial and the underlying crystalline rock aquifer of the Han River Basin has been undertaken, Analysis of the data has I) confirmed the hypothesis that the groundwater from the metropolitan area is recharged from the river whereas that form the non-urbanized region of the Basin is replenished by the infiltrating precipitation; ii) shown that crystalline rock aquifers are recharged by the ground water form the overlying alluvium. Old groundwater is a group of wells with tritium values in the range of 0 to 2 TU. These low values indicate that the water sampled was recharged much ealier, at least a few decades, than the other groundwater samples of higher tritium content. The low values in this region may, in fact, reflect the effect of the impermeable clay layers which impede infilteration from the surface. Stable isotope evidence confirmed that a recharge in the karst area occurs at a significantly greater elevation than that to the alluvial aquifer. An analysis of the tritium level collected over an annual cycle suggests that the residence time of groundwater is probably not more than a few months. There does not appear to be any correlation between the trace level of Zn, Mn and Pb in the groundwater and the mechanism of the recharge.

• The Journal of Korean Society for School & Community Health Education
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• v.2 no.2
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• pp.89-99
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• 2001

This paper is based on the assumption that the sexual awareness and sexual behaviour of high school students would show the difference between an academic high school and a vocational high school. The main purpose of this paper is to provide basic information on establishing the direction of a realistic and efficient education, which leads to the desirable sex ethics eventually. To do this, a comparative study was carried out to figure out the difference between academic high school students and vocational high school students in terms of their actual awareness and behaviour of sex. I put the following two questions in order to achieve the goal of this study. First, what is the difference in sexual awareness between academic high school students and vocational high school students? Second, what is the difference in sexual behaviour between academic high school students and vocational high school students? The subjects of the survey conducted were 595 high school students in Kyunggi Province and I made the questionnaires referencing pre-studies. The SPSS program was used to get a frequency and a percentage from the results of the survey and then, by applying t-text, $x^2$ verification and interrelation, the following results were obtained. First, regarding sexual awareness, there wasn't much difference in their idea of keeping virginity before marriage between academic high school students and vocational high school students. From the results obtained by analyzing the interrelation between students and their parents and friends in terms of a will to keep virginity, it is found that there was a relevance in both academic high school and vocational high school. When they have a sex problem, it was friends that they are looking for consulting and both groups showed thesame result. But pertaining to an experience of a sex education, the comparative analysis indicated an meaningful difference. Second, as for sex behaviour, it was shown that there was a difference in the experience of going out with the other sex between academic high school students and vocational high school students as well as in the degree of physical touch. However, not much difference was shown in controlling a sex desire between the two groups. As a results of the comparative analysis of the sex experience between the two groups, there was a meaningful difference. In terms of the object of their sex experience, the majority of students in the two groups chose a friend as their first answer and there was little difference. From these results I can draw some conclusions that most of the students in both groups have a link with friends and parents in keeping their virginity. Furthermore, a meaningful difference in experiencing a sex education is presented between the two groups. With regard to the sex behaviour of high school students, a meaningful difference is shown in dating the other sex, a physical touch and a sex experience between the two groups. Consequently, we realize that there is a meaningful difference in some variants on the sexual awareness and sexual behaviour of high school students between academic high school and vocational high school.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.7-18
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• 2003

Due to the changes of shipping and logistic environment, Asian ports today face severe competition. To be a mega-hub port, Asian ports have achieved a big scale development. For these reasons, it has been widely recognized as an important study to analyze and evaluate characteristics of Asian ports, from the standpoint of Korea where Busan Port is located. Although some previous studies have been reported, most of them have been beyond the scope of Asian ports and analyzed the world's major ports; moreover, the studied ports have been about the ports which are well known from the previous research and reports. So, most studies is unlikely to be used as substantial indicators from the perspective of Busan Port. In addition. most of the existing studies have used hierarchical evaluation algorithm for port ranking, such as AHP (analytical hierarchy process) and clustering analysis. However, these two methods have fundamental weaknesses from the algorithm perspective. The aim of this study is to classify major Asian ports based on competitiveness level. Especially. in order to overcome serious problem of the existing studies, major Asian ports were analyzed by using objective indicators. and Fuzzy C-Means algorithm, which alleviates the weakness of the clustering method. It was found that 10 ports of 16 major Asian ports have their own phases and were classified into 4 port groups. This result implies that some ports have higher potential as ports to lead some zones in Asia. Based on those results. present status and future direction of Busan port were discussed as well.