• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.458-467
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• 2002

There has been proposed many simplification algorithms for effectively decreasing large-volumed polygonal surface data. These algorithms apply their own cost function for collapse to one of fundamental simplification unit, such as vertex, edge and triangle, and minimize the simplification error occurred in each simplification steps. Most of cost functions adopted in existing works use the error estimation method based on distance optimization. Unfortunately, it is hard to define the local characteristics of surface data using distance factor alone, which is basically scalar component. Therefore, the algorithms cannot preserve the characteristic features in surface areas with high curvature and, consequently, loss the detailed shape of original mesh in high simplification ratio. In this paper, we consider the vector component, such as surface orientation, as one of factors for cost function. The surface orientation is independent upon scalar component, distance value. This means that we can reconsider whether or not to preserve them as the amount of vector component, although they are elements with low scalar values. In addition, we develop a simplification algorithm based on half-edge collapse manner, which use the proposed cost function as the criterion for removing elements. In half-edge collapse, using one of endpoints in the edge represents a new vertex after collapse operation. The approach is memory efficient and effectively applicable to the rendering system requiring real-time transmission of large-volumed surface data.

• Journal of Korea Multimedia Society
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• v.9 no.5
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• pp.671-680
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• 2006

As a mathematical technique with which we can find the minimum duration time needed to fire all the transitions at least once and coming back to the initial marking in a timed net, the minimum cycle time method has been widely used in computer system analysis. A timed net is a modified version of a Petri net where a transition is associated with a delay time. A delay time used in a timed net is a constant even though the duration time associated with an event in the world is a stochastic number in general. In the consequence, the result of minimum cycle time analysis is not realistic. Therefore, we propose ‘Stochastic Timed Net' where a transition can be associated with a stochastic number and introduce a minimum cycle time analysis method for ‘Stochastic Timed Net’ As an example of the application of ‘Stochastic Timed Net’, we introduce a ‘Stochastic Timed Net' model of a Location Based Service Providing Multimedia System and the result of minimum cycle time analysis of it. Whereas the typical form of the result of the existing minimum cycle time analysis is 'It takes at least 10 time units', the typical form of the result of minimum cycle time analysis of a ‘Stochastic Timed Net' is in the probability form such as "The probability of the events in which it finishes its job within 10 time units is 85%."

• Journal of Korea Multimedia Society
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• v.10 no.2
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• pp.269-277
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• 2007

Network clustering has been proposed to provide that sensor nodes minimize energy and maximize a network lifetime by configuring clusters, Although dynamic clustering brings extra overhead like as head changing, head advertisement, it may diminish the gain in energy consumption to report attribute tasks by using cluster heads. Therefore, this paper proposes a new routing algorithm which configures cluster to reduce the number of messages when establishing paths and reports to the sink by way of cluster heads when responding sens ing tasks. All sensor nodes only broadcast bitmap once and maintain a bitmap table expressed by bits, allowing them to reduce node energy and to prolong the network lifetime. After broadcasting, each node only updates the bitmap without propagation when the adjacent nodes broad cast same query messages, This mechanism makes nodes to have abundant paths. By modifying the query which requests sensing tasks, the size of cluster is designed dynamically, We try to divide cluster by considering the number of nodes. Then, all nodes in a certain cluster must report to the sub- sink node, The proposed routing protocol finds easily an appropriate path to report tasks and reduces the number of required messages for the routing establishment, which sensor nodes minimize energy and maximize a network lifetime.

• Journal of Information Management
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• v.35 no.4
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• pp.1-16
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• 2004

In this paper, we outline the user interface problems that the text messaging users face to provide empirical basis for developing better improved mobile text messaging system. Our initial hypothesis was that the majority of the problems that the text messaging users face, namely, 1) difficulty in correctly understanding the intent of the incoming messages and 2) problem with frequently mis-addressing the recipient of the outgoing messages, can be accounted for by the poor usability of the text messaging user interface. Our analysis is based on the text message-based communication diaries, which were recorded for one week by each and every one of 75 college students, and survey taken from the same subjects. The data was collected in 2004. The students listed various difficulties including the limited message length, obscure input method, lack of mean to express emotional content, lack of receipt confirmation, lack of auto save feature when preparing messages to send, and lack of means to permanently save messages. Some of these problems were also identified in the previous studies. However, we were able to gather additional problems that the users face and also elicit potential solutions to remedy the problems. From these findings and analysis, we attempted to provide ways to improve the text messaging user interface.

• Restorative Dentistry and Endodontics
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• v.30 no.1
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• pp.31-37
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• 2005

The aim of this study was to evaluate the effectiveness of sealer placement in simulated root canal extensions. Forty resin blocks were attained from the Endo-training Bloc. In each block. The simulated root canal was made with $\#20$, 80taper GT file. After each block was longitudinally split into two halves, a standardized groove was prepared on one canal wall of two halves to simulate the canal extensions with various irregularities. The two halves of each block were assembled and all simulated root canals were obturated by single cone method with AH26 sealer. Four different methods of sealer placement were used: group A, $\#20$ K-file; group B, ultrasonic file; group C, lentulo spiral; group D, EZ-Fill bi-directional spiral. All obturated blocks were stored in $100\%$ humidity at $37^{\circ}C$ for 1 week, Using a low speed saw, each block was sectioned horizontally. Images of the sections were taken using a stereomicroscope at $\times$ 30 magnification and a digital camera. The amount of the sealer in the groove was evaluated using a scoring system, a higher score indicated better sealing effectiveness. The data was statistically analysed by Fisher's Exact Test. The sealing score was the lowest, specially at the middle area of canal extensions in group A, and that was statistically significant difference from other groups. In conclusion, the ultrasonic file, lentulo spiral and EZ-Fill bi-directional spiral were effective methods of sealer placement in simulated canal extensions. The K file was the least effective method, specially at the middle area of canal extensions.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.9
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• pp.415-423
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• 2001

Recently, there are many attempts to reproduce real world fine art pieces in digital forms. The digital representations are convenient to store and/or transmit. In contrast, mobiles, or moving sculptures, such as those designed by Alexander Calder cannot to reproduced realistically by usual reproduction techniques. Since mobiles are originally designed to generate motions in response to external forces applied to it, people could not fully enjoy them through photographs or static images. We present a virtual mobile system where use can easily control the mobile and can feel the impressions that the artist originally intended to provide. A real-world mobile is reconstructed in a three-dimensional physically-based model. and then virtual wind is generated to give motions to it. The motions of the mobile are generated by constraint dynamics and impulse dynamics techniques, which are modified to fully utilize the characteristics of the mobile, and finally give interactive displays on the PC platforms. The techniques presented can easily be extended to simulate other interactive dynamics systems.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.3
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• pp.57-67
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• 2012

This study draws the following conclusions about the nature garden culture with crane that is a dynamic landscaping factor introduced into nature garden by analyzing the literatures on cranes written and landscapes painted in Chosun Dynasty. First, crane symbolizes such Buddhist, Taoist and Confucius media as appearance of Buddha, desire for Taoist hermit world and long life, and a solitary's life of proud loneliness. It has been recorded that crane was raised from the Three Nations Era till the Japanese occupation and Confucius scholars in Chosun Dynasty opened shows concerning crane or formed literature groups enjoying poems of it, and often using crane as their denial of going into government service. Second, in order to introduce crane to nature garden, people caught wild crane and made a fence and some kind of pond for their growth. In addition, crane was strictly managed by appointed slaves and they trained crane for dancing and then tended to allow a crane to play on the yard in terms of abstract meaning or got two cranes free in consideration of their ecology. Third, for more appreciation of crane and the expression of some symbolism matching for it, both plum and pine, which mean a solitary's life and long life respectively, were planted in nature garden. And, Confucius scholars in Chosun Dynasty also enjoyed their refined tastes with appreciation, napping, reading and playing the harp, accompanied by crane. As aforementioned, Confucius scholars in Chosun Dynasty did not only draw the meaning symbolized by cranes and write poems about such symbolic meaning, but also positively introduce crane into nature garden as a dynamic landscaping factor, so that they enjoyed synesthetic senses including looks, motions and sounds of cranes for their refined tastes.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.2
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• pp.45-56
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• 2010

This study is dealing with Deoksugung around the founding of the Daehan Empire Era. It will looks closely into how locational contexts and sense of place have been changed according to the subject's view point and the interpretation of text community until Deoksugung is changed into citizen-oriented public place vested with the meaning of public park. In conclusion, Deoksugung was a place for suffering and sorrows, but also it was a place for ceaseless attempt to pursue of the recovery of past without loosing hope. As in the case of uprising war like Japanese invasion of Korea (Imjin Yeran) or Cheong Japan War, Deoksugung was an importantly historical place where autocrat temporarily stayed to stand up for the war and moreover, it was an imperial palace where the ambivalent sensibility between suffering and hope are intermingled in the very first Korean Empire in history. Unlike Kyeongbokgung and Changdeokgung, the current Deoksugung has changed its boundary from time to time since Japanese invasion of Korea up to the present. Deoksugung has evolved the present situation as endlessly changing its boundary by interacting with the neighbor of Kyungungung. The more complicated sense of place is coexisted in the features of the Deoksugung. Therefore, current hot topics concerning restoration project of Deoksugung is much more difficult than of other palaces. This issues should be carefully dealt with beyond the political interests.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.34 no.4
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• pp.26-36
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• 2016

This study aims to identify the place and location of Gasan around Cheonggyecheon in the Joseon Dynasty, and also to examine the current status of their changes or disappearance in the process of modernization. On top of literature research on old document and maps related to dredging of Cheonggyecheon, the field survey to understand the actual status and location of Gasan was conducted. The study contents are like below. First, through old document and maps related to Cheonggyecheon in the Joseon Dynasty, the contents and records related to Gasan around Cheonggyecheon were selected. Such Gasan were mainly built up by dredging work of branch/streamlet in the era of King Sejong, and also the large-scale dredging during the period of King Yeongjo. Second, the location of Gasan and forest around Cheonggyecheon shown in old maps was understood. With Ogansumun(Five-arched Floodgates) as the center, they were constructed on both hills of Cheonggyecheon inside/outside of the capital city, and its surrounding branches. Third, based on the measures to create a scale map based on Susunjeondo, the location of Gasan on old maps was found on the current map, and then the current status of places expressed as Gasan was surveyed. In the results of the study, even though most of the Gasan built up around Cheonggyecheon in the Joseon Dynasty have disappeared by the urban development performed since the end of 19th century, still, there are some remains left.

• Journal of KIISE:Software and Applications
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• v.32 no.7
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• pp.663-673
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• 2005

An analysis model for the dynamics information of two-dimensional time-series patterns is described. In the proposed model, two novel transforms that visualize the dynamic characteristics are proposed. The first transform, referred to as speed equalization, reproduces a time-series pattern assuming a constant linear velocity to effectively model the temporal characteristics of the signing process. The second transform, referred to as velocity transform, maps the signal onto a horizontal vs. vertical velocity plane where the variation oi the velocities over time is represented as a visible shape. With the transforms, the dynamic characteristics in the original signing process are reflected in the shape of the transformed patterns. An analysis in the context of these shapes then naturally results in an effective analysis of the dynamic characteristics. The proposed transform technique is applied to an online signature verification problem for evaluation. Experimenting on a large signature database, the performance evaluated in EER(Equal Error Rate) was improved to 1.17$\%$ compared to 1.93$\%$ of the traditional signature verification algorithm in which no transformed patterns are utilized. In the case of skilled forgery experiments, the improvement was more outstanding; it was demonstrated that the parameter set extracted from the transformed patterns was more discriminative in rejecting forgeries