• Journal of Korean Association for Spatial Structures
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• 제5권3호
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• pp.65-74
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• 2005

An analytical model was developed to investigate the flexural behavior of a pultruded fiber-reinforced plastic deck of rectangular unit module. The model is based on first-order shea. deformable plate theory (FSDT), and capable of predicting deflection of the deck of arbitrary laminate stacking sequences. To formulate tile problem, two-dimensional plate finite element method is employed. Numerical results are obtained for FRP decks under uniformly-distributed loading, addressing the effects of fiber angle and span-to-height ratio. It is found that the present analytical model is accurate and efficient for solving flexural behavior of FRP decks. Also, as the height of FRP deck plate is higher, the necessity of higher order Shear deformable plate theory(HSDT) is announced, not the FSDT in the plate analysis theory.

• The KIPS Transactions:PartD
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• 제16D권2호
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• pp.161-168
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• 2009

Recently, use of various position base servicesthat collect position information for moving object and utilize in real life is increasing by the development of wireless network technology. Accordingly, new index structures are required to efficiently retrieve the consecutive positions of moving objects. This paper addresses an improved trajectory split algorithm for the purpose of efficiently supporting spatio-temporal range queries using index structures that use Minimum Bounding Rectangles(MBR) as trajectory approximations. We consider volume of Extended Minimum Bounding Rectangles (EMBR) to be determined by average size of range queries. Also, Use a priority queue to speed up our process. This algorithm gives in general sub-optimal solutions with respect to search space. Our improved trajectory split algorithm is going to derive minimizing volume of EMBRs better than previously proposed split algorithm.

• Journal of KIISE:Databases
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• 제28권4호
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• pp.665-676
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• 2001

The most expensive spatial operation in patial database in a spatial join which computes a combined table of which tuple consists of two tuples of the two tables satisgying a spatial predicate. Although the execution time of sequential processing of a spatial join has been so far considerably improved the response time is not tolerable because of not meeting the requiremetns of interactive users. It is usually appropriate to use parallel processing to improve the performance of spatial join processing. in spatial database the fixed grids which consist of the regularly partitioned cells can be employed the previous works on the spatial joins have not studied the parallel processing of spatial joins using fixed grids. This paper has presented an analytical cost model that estimates the comparative performance of a parallel spatial join algorithm based on the fixed grids in terms of the number of MBR comparisons. disk accesses, and message passing, Several experiments on the synthetic and real datasets show that the proposed analytical model is very accurate. This most model is also expected to used for implementing a very important DBMS component, Called the query processing optimizer.

• The Transactions of the Korea Information Processing Society
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• 제4권12호
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• pp.2931-2946
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• 1997

In multimedia information retrieval applications, content-based image retrieval is essential for retrieving relevant multimedia documents. The purpose of our paper is to provide effective representation and efficient retrieval of images when a pixel-level original image is automatically or manually transformaed into its iconic image containing meaningful graphic descriptions, called icon objects. For this, we first propose new spatial match representationschemes to describe spatial relationships between icon objects accurately by expressing them as rectangles, rather than as points. In order to accelerate image searching, we also design an efficient retrieval method using a two-dimensional signature file organization. Finally, we show from our experiment that the proposed representation schemes achieve better retrieval effectiveness than the 9-DLT (Direction Lower Triangular) scheme.

• Journal of the Institute of Electronics Engineers of Korea CI
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• 제38권1호
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• pp.19-25
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• 2001

A novel approach for the feature extraction of handwritten characters is proposed by using spatial filtering neural networks with 4 layers. The proposed system first removes rough pixels which are easy to occur in handwritten characters. The system then extracts and removes the boundary information which have no influence on characters recognition. Finally, The system extracts feature information and removes the noises from feature information. The spatial filters adapted in the system correspond to the receptive fields of ganglion cells in retina and simple cells in visual cortex. With PE2 Hangul database, we perform experiments extracting features of handwritten characters recognition. It will be shown that the network can extract feature informations from handwritten characters successfully.

• Journal of Korean Association for Spatial Structures
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• 제3권4호
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• pp.69-76
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• 2003

In case of rectangular latticed pattern which shearing rigidity is very small, it has a concern to drop Buckling-strength considerably by external force. So, by means of system to increase buckling-strength, there is a method of construction that lattice of dome is reinforced by braced member. In a case like this, shearing rigidity of braced member increase buckling-strength of the whole of structure and can be designed economically from the viewpoint of practice. Therefore, this paper is aimed at investigating how much does rigidity of braced member united with latticed member bearing principal stress of dome increase buckling-strength of the whole of structure. the subject of study is rectangular latticed domes that are a set of 2-way lattice dome which grid is simple and number of member gathering at junction is small. Analysis method is based on FEM dealing with the geometrically nonlinear deflection problems.

• Proceedings of the Acoustical Society of Korea Conference
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• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
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• pp.323-326
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• 2004

에어컨 실외기의 구조 방사 소음을 줄이기 위해 제진재를 적용함에 있어 구조 인텐서티(structural intensity)법을 사용할 수 있다. 에어컨 실외기 각 패널의 법선 방향의 속도는 레이져 스케닝 바이브로미터(laser scanning vibrometer)에 의해 측정되며, 측정된 데이터는 공간 주파수 영역(k-domain)으로 변환하여 구조 인텐서티 계산에 필요한 공간 미분값이 구해진다. 이러한 과정을 통하여 계산된 구조 인텐서티 중 반동 전단 구조인텐서티(reactive shearing structural intensity)값이 가장 높은 부분에 사각형 형상의 제진재를 적용한다. 본 논문은 패널에 비해 그 크기가 작은 제진재의 적용으로 에어컨 실외기의 구조 방사 소음을 줄일 수 있음을 보여준다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제12권1호
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• pp.33-39
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• 2000

There are many under going researchs for the natural convection and fluid flow in rectangular enclosure. In this paper, the optimal model that is the most frequently used for the analysis of a turbulent natural convection in rectangular enclosure is suggested by comparing with the result of Cheesewright's experiment. As We can see the distribution of the velocity, temperature, and turbulent kinitic energy, ST model tends to exaggerate the result of the experiment. The LS model generates better experimental result than the ST and DA's. Therefore, it is resonable to adopt the LS model that contains explicit physical meanings of each term in eouation of turbulent kinitic energy.

• Proceedings of the Korea Information Processing Society Conference
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• 한국정보처리학회 2021년도 춘계학술발표대회
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• pp.560-563
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• 2021

본 논문에서는 사각형 실내 공간에서 점군 데이터를 기반으로 빠르고 정확하게 바닥, 천장, 벽면에 대한 평면 정보를 획득할 수 있는 시스템을 제안한다. 기존의 방법은 관측되지 않은 공간에 대한 평면을 예측할 수 없으며, 노이즈에 취약하고, 모든 점에 대한 기저 정보를 알아야하기 때문에 많은 연산량을 요구한다. 제안 방법은 기존의 평면 검출 방식에서 벗어나 Bounding Box 형상을 예측하는 기술을 활용한다. 또한, 제안 시스템은 구면 파노라마 비디오를 기반으로 적은 수의 프레임으로도 빠르게 실시간 점군 데이터를 확장해나간다. 제안 방법은 실험을 통해 기존의 방법보다 월등히 빠르고, 노이즈 등 환경 제약 요소에 강건함을 보인다.

• Spatial Information Research
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• 제10권1호
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• pp.61-76
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• 2002

Mobile map services using PDA are prevailing because of the rapid developments of techniques of the internet and handhold devices recently. While the volume of spatial data is tremendous and the spatial operations are time-intensive, the PDA has small size memory and a low performance processor. Therefore, the spatial index for PDA should be small size and efficiently filter out the candidate objects of spatial operation as well. This paper proposes a spatial index far PDA called MHF(Multilevel Hashing File). The MHF has simple structure for storage efficiency and uses a hashing technique, which is direct search method, for search efficiency. This paper also designs a compression technique for MBR. which occupies almost 80% of index data in the two dimensional case. We call it HMBR. Although the HMBR technique reduces the MB\ulcorner size to almost a third, it shows good filtering efficiency because of no information loss by quantization in case of small objects that occupy a major portion. Our experimental tests show that the proposed MHF index using HMBR technique is appropriate for PDA in terms of the size of index, the Number of MBR comparisons, the filtering efficiency and the execution time of spatial operations.