• Journal of KIISE:Information Networking
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• v.32 no.6
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• pp.705-715
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• 2005

A peer-to-peer web caching has been studied recently as it can reduce the traffic converged on the server side and can support the traditional web caching model. Although the peer-to-peer web caching has the merit of having additional cache space from the local caches of peers without additional infrastructure, several constraints such as dynamic participation and local caching strategy caused by the autonomy of peers in peer-to-peer networks nay limit the performance of the peer-to-peer web caching. To overcome these limitations, we propose an efficient directory-based peer-to-peer web caching system under dynamic participation of peers. In the proposed caching system, we present new peer selection and replica management schemes by introducing the concept of the object lifetime in P2P networks. We evaluate the effectiveness of the proposed system through trace-driven simulations with a web log dataset. Simulation results show that the proposed system has higher accuracy and fewer redirection failures than the conventional directory-based P2P web caching system in feasible peer-to-peer networks.

• Journal of the Korea Computer Graphics Society
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• v.26 no.3
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• pp.9-19
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• 2020

With the recent development of various kinds of virtual reality devices, there has been an active research effort to increase the sense of reality by recognizing the physical behavior of users rather than by classical user input methods. Among such devices, the Leap Motion controller recognizes the user's hand gestures and can realistically trace the user's hand in a virtual reality environment. However, manipulating an object in virtual reality using a recognized user's hand often causes the hand to pass through the object, which should not occur in the real world. This study presents a way to build a visual feedback system for enhancing the user's sense of interaction between hands and objects in virtual reality. In virtual reality, the user's hands are examined precisely by using a ray tracing method to see if the virtual object collides with the user's hand, and when any collision occurs, visual feedback is given through the process of reconstructing the user's hand by moving the position of the end of the user's fingers that enter the object through sign distance field and reverse mechanics. This enables realistic interaction in virtual reality in real time.

• Korean Institute of Interior Design Journal
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• v.23 no.5
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• pp.67-75
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• 2014

Architecture is not only coming out of the making of a building room but also contributing to the making of an urban room. "The inside is not a contradiction of the outside...architecturally opened". (De Carli, 1967) The urban room is felt as a sense of rapport between building and city because architecture makes the building room closed simultaneously open toward the city. Architecture exists between both rooms. There is the possibility of integrating, by the conception of interior, architecture and urbanism and thus, the possibility of giving a theoretical ground to Interior Architecture/Design; "all architecture is interior architecture". (Ottolini, 1996) It is in line with the idea of the "Fusing: Landscape/Urbanism/Architecture". (Holl, 2009) The paper deals with, through literature review, a possibility of the fusing: Interior/Architecture/Landscape/Urbanism. The first site explores the meaning of the urban place as a thing, which gives a possibility of combining the building interior and the urban interior. The second site illustrates the idea of the urban interior for dwelling. The urban interior is definitely a place of dwelling to keep human inhabitancy, which takes place in a united interior of the building interior and the urban interior. The third site clarifies the idea of the urban interior. While the building interior gives human being with the private stage, the urban interior provides him with the public stage of city life. The two different interiors constitute an interior world for his trajectory of dwelling. The last site traces the conceptual development of the urban interior. The trace comes to a conclusion that architecture, landscape, and urbanism can be unified by the conception of interior and the urban interior is an object of "Interior Architecture/Design". This paper is theorized as a twofold singular of the building interior and the urban interior. Ultimately, it is relevant to the theoretical principle of fusing interior/architecture/landscape/urbanism, and aims at offering a departing point to consider the urban interior as an object of "Interior Architecture/Design" and for the future studies of the urban interior.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.27-29
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• 2007

The visual implementation of 3-dimensional national environment is focused by the requirement and importance in the fields such as, national development plan, telecommunication facility deployment plan, railway construction, construction engineering, spatial city development, safety and disaster prevention engineering. The currently used DEM system using contour lines, which embodies national geographic information based on the 2-D digital maps and facility information has limitation in implementation in reproducing the 3-D spatial city. Moreover, this method often neglects the altitude of the rail way infrastructure which has narrow width and long length. There it is needed to apply laser measurement technique in the spatial target object to obtain accuracy. Currently, the LiDAR data which combines the laser measurement skill and GPS has been introduced to obtain high resolution accuracy in the altitude measurement. In this paper, we first investigate the LiDAR based researches in advanced foreign countries, then we propose data a generation scheme and an algorithm for the optimal manage and synthesis of railway facility system in our 3-D spatial terrain information. For this object, LiDAR based height data transformed to DEM, and the realtime unification of the vector via digital image mapping and raster via exactness evaluation is transformed to make it possible to trace the model of generated 3-dimensional railway model with long distance for 3D tract model generation.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.6
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• pp.583-591
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• 2000

Caching mechanisms have been studied extensively to buffer the speed gap of hierarchical storages in the context of cache memory, paging system, and buffer management system. As the wide-area distributed environments such as the WWW extend broadly, caching of remote objects becomes more and more important. In the wide-area distributed environments, the cost and the benefit of caching an object is not uniform due to the location of the object; which should be considered in the cache replacement algorithms. For online operation, the time complexity of the replacement algorithm should not be excessive. To date, most replacement algorithms for the wide-area distributed environments do not meet both the non-uniformity of objects and the time complexity constraint. This paper proposes a replacement algorithm which considers the non-uniformity of objects properly; it also allows for an efficient implementation. Trace-driven simulations show that proposed algorithm outperforms existing replacement algorithms.

• Journal of KIISE:Software and Applications
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• v.29 no.5
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• pp.319-325
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• 2002

Tracking moving objects is one of the most important techniques in motion analysis and understanding, and it has many difficult problems to solve. Especially, estimating and identifying moving objects, when the background and moving objects vary dynamically, are very difficult. It is possible under such a complex environment that targets may disappear totally or partially due to occlusion by other objects. The Kalman filter has been used to estimate motion information and use the information in predicting the appearance of targets in succeeding frames. In this paper, we propose another version of the Kalman filter, to be called structured Kalman filter, which can successfully work its role of estimating motion information under a deteriorating condition such as occlusion. Experimental results show that the suggested approach is very effective in estimating and tracking non-rigid moving objects reliably.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.53.3-53.3
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• 2015

We analyzed both HCN J=1-0 and HNC J=1-0 line profiles to study the inflow motions in different evolutionary stages of massive star formation; infrared dark clouds (IRDCs), high-mass protostellar object (HMPOs), and ultra-compact HII regions (UCHIIs). The infall asymmetry in HCN spectra seems to be prevalent throughout all the three evolutionary phases, with IRDCs showing the largest excess in blue profile. In the case of HNC spectra, the prevalence of blue sources does not appear, excepting for IRDCs. We suggest that this line is not appropriate to trace infall motion in evolved stages of massive star formation because of an astrochemical effect. This result spotlights the importance of considering chemistry in dynamical study in star-forming regions. The fact that the IRDCs show the highest blue excess in both infall tracers indicates that the most active infall occurs in the early phase of star formation, i.e., the IRDC phase rather than in the later phases. However, the UCHIIs is likely still accreting matters. We also found that the absorption dips of the HNC spectra in all blue sources are red--shifted relative to their central velocities. These red-shifted absorption dips may indicate the observational signature of overall collapse although observations with better resolutions are needed to examine this feature more in detail.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.70.2-70.2
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• 2013

We present collections of optical photometry for a pre-main sequence star HBC 722. It showed large amplitude optical outburst (${\Delta}V=4.7$ mag) in 2010 and classified as a FU Orionis type object. We have been observing HBC 722 from 2011 April to 2013 May, using Camera for QUasars in EArly uNiverse (CQUEAN) attached to the 2.1 m Otto Struve telescope at the McDonald Observatory. Time-series monitoring data (minute-scale interval) were obtained in SDSS r, i and z bands to see short-scale behaviors as well as trace the long-term brightness changes after the eruption in 2010. Interestingly, it started to brighten from 2011 early summer and became brighter than the first outburst peak in our 2013 May observation. We expect that the recovering phase would result from re-increase of disk accretion rate, might attribute to distinctive short-scale color features. In this presentation, we report long- and short-timescale optical behaviors of HBC 722 in the post-outburst phase.

• The Transactions of the Korea Information Processing Society
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• v.7 no.7
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• pp.2086-2094
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• 2000

It is not easy to analyze object-oriented programs, including those in Java, Because the control flows of he program is not visible to the users. The users, however, can utilize class files to trace the process of execution, since a lot of information related on control flow are store in the control flows. A Java virtual machine can then execute the bytecods included in classfiles. It means that understanding the execution process of the bytecodes leads users to comprehend and analyze source programs in Java. We design and implement a visual tool for bytecode execution that is an efficient and powerful tool to understand and analyze source programs in Java. It can aid users to thoroughly grasp not only the structure of a program but also the flow of controls among objects.

• Korean Institute of Interior Design Journal
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• no.15
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• pp.79-85
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• 1998

Woods have been the familiar constructional materials because they were well suited to natural environments of Korea in terms of history regionalism and nationality. Since the modernization of Korea the wooden structure have mostly disappeared because of constructional costs regulations and convenience. But wooden constructions will reappear because of a prediction of wood demand and supply various choices for life circumstances and various investigations. There are many such cases. Among them Japan became an interesting object of investigation. New wooden constructional structures with new materials and modern skills may be observed in Japan. The purpose of this study is to trace architects' consciousness and to analyze constructions with the combination of wooden and other materials in Japan. Thus we explore a possibility to construct a new wooden structure which is suitable in modern Korea. The results were as follows: First the consciousness of Japanese architects' mixed wooden construction corresponds to the close relations between society and environment. Second the space of a structure with mixed wooden constructions in present Japan is chosen as the best way to consider functions and environments according to the form of need space scale and quality. Third the structure wooden constructional structure is a part of roof open space. in this case woods are represented and composed of japanese traditional wooden structure with new technique. Forth a mixed wooden construction has been used through a merit of each material by mixed of different materials as well as beauty of form.