• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.4
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• pp.1-14
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• 2004

In this study, we propose Linktable based on extended TB-Tree(LTB-Tree) which can improve the performance of existing TB (Trajectory-Bundle)-tree proposed for indexing the trajectory of moving objects in GIS Applications. In addition, in order to evaluate proposed indexing scheme, we take into account as follows. At first, we select existing R*-tree, TB-tree, and LTB-tree as the subject of performance evaluation. Secondly, we make use of random data set and real data set as experimental data. Thirdly, we evaluate the performance with respect to the variation of size of memory buffer by considering the restriction of available memory of a given system. Fourth, we test them by using the experimental data set with a variation of data distribution. Finally, we think over insertion and retrieval performance of trajectory query and range query as experimental measures. The experimental results show that the proposed indexing scheme, LTB-tree, gains better performance than traditional other schemes with respect to the insertion and retrieval of trajectory query.

• The Journal of Korean Association of Computer Education
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• v.9 no.2
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• pp.111-124
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• 2006

Multicast services are provided on the Internet in fast increasing. Therefore it is important to keep security for multicast communication. If a member of the group is removed, new group key has to be generated and distributed to all remaining members of group. Minimizing number of messages and operation cost for generation of the composite keys to be used to encrypting group key are important evaluating criteria of multicast key management scheme since generation and distribution of new keys for rekeying require expensive operation. Periodic batch rekeying can reduce these important parameters rather than rekeying sequentially in fashion one after another. In this paper, Hamming distance is calculated between every members to be removed. In batch rekeying the members with Hamming distance less than threshold are selected for rekeying procedure. With running the round assignment algorithm in the case of removing several members simultaneously, our scheme has advantages of reducing messages and operation cost for generation of the composite keys and eliminating possibility of collusion attack for rekeying. We evaluate performance of round assignment algorithm through simulation and show that our scheme is excellent after performance comparison of existent schemes and our scheme.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.3
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• pp.45-54
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• 2002

The purposes of this paper are to review the shifts and changes in urban planning environment, and to grasp how the new 'National and Urban Planning Law' accommodates these changes. In order to accomplish proposed schemes, I suggest that the following three details should be considered for the proper way of Urban Planning Information System(UPIS) from the beginning stage. First, new techniques are required to realize the new concepts in 'National and Urban Planning Law' with GIS and constructed DB by NGIS, as planning support systems. Second, the status of UPIS rises to the highest status among land-related information systems. Third, to adapt the UPIS to the decision support system, the restructuring of urban planning itself should be proceeded under considering the changes of concepts, paradigms and techniques.

• Journal of Korea Water Resources Association
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• v.47 no.11
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• pp.1061-1066
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• 2014

A stable second-order finite volume method was proposed to predict sediment transport under rapidly varied flow conditions such as transcritical flow. For the use under unsteady flow conditions, a sediment transport model was coupled with shallow water equations. HLLC approximate Riemann solver based on a monotone upstream-centered schemes for conservation laws (MUSCL) reconstruction was used for the computation of the flux terms. From the comparisons of dam break flow experiments on erodible beds in one- and two-dimensional channels, good agreements were obtained when proper parameters were provided. Lastly, dam surface erosion problem by overtopped water was simulated. Overall, the numerical solutions showed reasonable results, which demonstrated that the proposed numerical scheme could provide stable and physical results in the cases of subcritical and supercritical flow conditions.

• Journal of the Korean housing association
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• v.24 no.3
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• pp.121-133
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• 2013

The purpose of this study is to analyze the design characteristics of external appearances of Hundertwasser's housing projects through both literature review and field study, and to understand how Hundertwasser's architecture philosophy was embodied in the design of external appearances so such projects. The subjects of the analysis are: Hundertwasser House; In the Meadow Bad Soden; The Forest Spiral Darmstadt; and The Green Citadel Magdeburg. The conclusion of the study is as follows. The fundamental architecture philosophy of Hunderwasser is the close linkage between mankind and nature. He has proven, through his four housing projects mentioned above, that it is possible to build houses without destroying and in harmony with nature. Hundertwasser had identified vitality, irregularity and diversity as being the source of beauty of nature. Using the human creativity, he had embodied such elements into his housing projects, thus suggesting an ideal housing environment whereby humanity is respected. Hundertwasser made use of organic curved line and spiral shapes that exist in nature when designing his housing projects. His creativity was articulated through vitality, diversity, and irregularity in colour schemes and a wide range of form. Indeed, he was an architect pursuing the underlying nature of both human and nature. The current living environment in Korea can be characterized as being standardized and desolate, which is a result of housing projects being focused too much on functionalism. Through its analysis of Hundertwasser's housing projects, one of the objectives of this study is to contribute to a new design paradigm being called for today, including for housing projects to be more ecological and environmental-friendly. By motivating architects and appealing to their clients, this study hopes to motivate those involved in various housing projects to think progressively. Such an attitude change could assist in transforming and thus enhancing the overall living environment in Korea.

• Journal of the Korean association of regional geographers
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• v.12 no.4
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• pp.496-507
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• 2006

A hybrid approach integrating both high-resolution and hyperspectral data sets was used to map vegetation cover of a coastal lowland area in the Hawaii Volcanoes National Park. Three common grass species (broomsedge, natal redtop, and pili) and other non-grass species, primarily shrubs, were focused in the study. A 3-step, hybrid approach, combining an unsupervised and a supervised classification schemes, was applied to the vegetation mapping. First, the IKONOS 1-m high-resolution data were classified to create a binary image (vegetated vs. non--vegetated) and converted to 20-meter resolution percent cover vegetation data to match AVIRIS data pixels. Second, the minimum noise fraction (MNF) transformation was used to extract a coherent dimensionality from the original AVIRIS data. Since the grasses and shubs were sparsely distributed and most image pixels were intermingled with lava surfaces, the reflectance component of lava was filtered out with a binary fractional cover analysis assuming that tile total reflectance of a pixel was a linear combination of the reflectance spectra of vegetation and the lava surface. Finally, a supervised approach was used to classify the plant species based on tile maximum likelihood algorithm.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.28-38
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• 2013

During the past decades, the B+-tree has been most widely used as an index file structure for disk-resident databases. For the disk based B+-tree, a node update can be cheaply performed just by modifying its associated disk page in place. However, in case that the B+-tree is stored on flash memory, the traditional algorithms of the B+-tree come to be useless due to the prohibitive cost of in-place updates on flash memory. For this reason, the earlier schemes for flash memory B+-trees usually take an approach that saves B+-tree changes from real-time updates into extra temporary storage. Although that approach can easily prevent frequent in-place updates in the B+-tree, it can suffer from a waste of storage space and prolonged search times. Particularly, it is not allowable to process range searches on the leaf node level. To resolve such problems, we devise a new scheme in which the leaf nodes and their parent node are stored together in a single flash block, called the p-node block.

• Journal of Korea Water Resources Association
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• v.37 no.10
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• pp.799-812
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• 2004

Conjunctive use of surface and ground water has drawn much attention as a promising means to solve water shortage problems. Characterized by its maximum utilization of regional resources and environmental friendliness, conjunctive use is expected to contribute to the integrated water resources management in the coming era. This paper examines the applicability of the methodology for conjunctive use developed in the companion paper (this issue). The method consists of the entire process of conjunctive use, including site assessment using analytic hierarchy process, management scenario development based on drought analysis, and evaluation of benefits obtained. Sokcho City was chosen as the study area, and the application of derived operation scenarios for surface and subsurface reservoirs revealed that water of 4.9∼7.4 million cubic meters a year can be attainable additionally. The developed methodology enables one to devise management schemes and to quantify their effectiveness, which makes the method useful for water resources planners as well as practitioners.

• Journal of Korea Water Resources Association
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• v.32 no.2
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• pp.99-110
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• 1999

The method of moments, a Lagrangian scheme, considers the zeroth, first, and second moments of the grid cell spatial distributions of the concentration and then advects the concentration by maintaining conservation of the moments. The reasonable inital description of the first and second moments as well as the mean concentration, the zeroth moments, in grid element is important in the method of moments. In this study, the description methods of each initial moment are reviewed, and the method of moments is extended to overcome the restrictions of Courant number. Its performance is compared with those of available Eulerian and Lagrangian schemes. As the results, the method is successfully extended to overcome the stability restriction and is an accurate scheme for the advection simulation of concentration distribution, especially of which the gradient is steep. In addition, the method is very promising scheme in terms of computational efficiency when the mixing is confined in a relatively small region to the entire domain in two-dimensional problem.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.1-11
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• 2003

This paper describes a finite volume, two-dimensional model. It adopts a recently developed essentially non-oscillatory(ENO) schemes based on the Lax-Friedrichs solver, which was modified for a finite volume grid, and employs a modified MUSCL(Monotonic Upstream centered Scheme for Conservation Law) for second-order accuracy in space. To demonstrate the applications of the model, it is applied to solve the 1-D and 2-D dam-break problems. The model in conjunction with the modified MUSCL showed a better agreement with analytical solutions than the minmod function in 1-D dam-break problems and is satisfactorily validated with documented published data in 2-D dam-break problems. The model was applied to tidal wane entering channel at one end, and the results showed a good agreement with analytical solutions. In the channel with reflective boundary conditions specified at the extremities, the model was capable of accurately simulating the wave propagation.