• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.783-792
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• 2006

This study investigates developments in a prestressing method using the thermal-expanded cover-plates that increases the load-carrying capacity of structures by installing it on upper or lower flanges in case that huge flexural stiffness according to the increase in span length or load are required of steel structure, such as rolled H-beam or built-up beam. This method applies multi-stepwise contraction forces generated by the contraction of cover plates as prestressing forces after joining the cover plate applied by multi-stepwise thermal expansion that was applied to induce prestressing to structures. To perform a theoretical investigation of the prestressing force applied to a structure due to the thermal expansion and induce a multi-stepwise prestressing method using multi-stepwise thermal distribution, this study proposes a theoretical heat transfer solution for the multi-stepwise thermal distribution of cover plates and analyzes the effect of a multi-stepwise prestressing method using the multi-stepwise thermal expansion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.321-321
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• 2004

본 연구에서는 웨이퍼 단면 연삭기 구조물의 경량화 고강성화 최적설계를 위하여 가변벌점함수 유전 알고리즘을 이용한 다단계 최적설계 방법을 적용하였다. 구조강성 최대화와 중량 최소화라는 상반된 성질의 목적함수를 최적화하기 위하여 강성의 역수 개념인 컴플라이언스(compliance)를 도입하여 목적함수론 최소화시키는 문제로 만들었으며, 가증방법(weighted method)을 이용하여 다목적 함수를 단일 목적함수로 변환시켰다. 부재 단면형상 최적화 단계와 정적설계 최적화 단계, 및 동적 설계 최적화 단계를 순차적으로 수행하는 다단계 최적설계를 방법을 연삭기 구조물의 최적설계에 적용하였다.(중략)

• Journal of the Korea Computer Graphics Society
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• v.4 no.1
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• pp.1-10
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• 1998

The idea of level-of-detail based on multiresolution model is gaining popularity as a natural means of handling the complexity regarding the realtime rendering of virtual environments. To generate an effective multiresolution model, we should capture the prominent visual features in the process of simplifying original complex model. In this paper, we incorporate view dependent features such as silhouette features and backface features, to the generation process of multiresolution model. To capture the view directional parameter, we propose multiresolution view sphere. View sphere maps the directional relationship between object surface and the view. Using the view sphere, coherence in the directional space is mapped into spatial coherence in the view sphere. View sphere is generated in multiresolution fashion to simplify the object. To access multiresolution view sphere efficiently, we devise quad tree for the view sphere. We also devise a mechanism for realtime simplification process using proposed view sphere. Using proposed mechanism, regenerating simplified model in realtime is effectively done in the order of number of rendered vertices.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.11
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• pp.1-7
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• 2004

We propose multistage parallel nulling (MPN) partial parallel interference cancellation (PPIC) receiver for downlink multiple-input multiple-output (MIMO) multicarrier (MC)-code division multiple access (CDMA) systems. Though the V-BLAST is a popular MIMO receiver, it shows error floor for multiuser downlink MIMO MC-CDMA systems. The proposed MPN-PPIC receiver does not produce error floor for multiuser case, and achieves substantial performance gains with multistage processing. For single user case, the proposed method also surpasses the V-BLAST receiver with multistage processing for MIMO MC-CDMA systems with chip level interleaving. The system performance of the proposed MPN-PPIC receiver is evaluated through computer simulations.

• The Transactions of the Korea Information Processing Society
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• v.3 no.3
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• pp.640-654
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• 1996

This paper presents a synthesis method for multi-level Reed-Muller circuits using BDDs(Binary Decision Diagrams). The existing synthesis tool for Reed circuits, FACTOR, is not appropriate to the synthesis of large circuits because it uses matrix (map-type) to represent given logic functions, resulting in the exponential time and space in number of imput to the circuits. For solving this problems, a syntheisis method based on BDD is presented. Using BDDs, logic functions are represented compactly. Therefor storage spaces and computing time for synthesizing logic functions were greatly decreased, and this technique can be easily applied to large circuits. Using BDD representations, the proposed method extract best patterns to minimize multi-level Reed Muller circuits with good performance in area optimization and testability. Experimental results using the proposed method show better performance than those using previous methods〔2〕. For large circuits of considering the best input partition, synthesis results have been improved.

• The Journal of the Korean dental association
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• v.52 no.10
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• pp.602-614
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• 2014

Obstructive sleep apnea syndrom(OSAS) is defined by total or partial collapse of the upper airway during sleep. In the presence of specific anatomic features, OSAS is potentially amenable to surgical treatment. Initially, the only treatment available for these patients was a tracheotomy that bypassed the obstruction and resulted in a 100% cure. However, this was not readily accepted by most patients, and surgical methods other than tracheotomy were developed to successfully maintain adequate upper airway patency during sleep by comparing to postoperative polysomnography(AHI,RDI etc). In this paper, I would like to provide an overview of some of the multilevel surgical techniques available for treating OSAS as well as the necessary preoperative considerations.

• Journal of KIISE:Software and Applications
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• v.27 no.12
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• pp.1219-1226
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• 2000

본 논문에서는 유전자 알고리즘과 피라미드(다단계 또는 다 해상도)를 결합한 새로운 영상분할 방법을 제안하다. 먼저, 영상을 피라미드의 해상도가 낮은 상위 단계로 분할하고 좋은 적합도를 가진 염색체의 개체군을 얻는다. 둘째, 해상도를 높인 다음 단계의 입력으로 앞 단계에서 얻은 염색체들을 사용하며, 더욱 세분화된 분할이 이루어지도록 염색체를 진화시키다. 유전자 알고리즘의 적합함수는 각 영역의 규질성과 peakiness를 이용하여 정의하였다. 교차는 교차점을 중심으로 영상을 2분하여 서로 교환하는 1점 교환법을 사용하였으며, 돌연변이는 병합과 분할이 이루어지도록 설계하였다. 본 논문은 저 해상도에서 가능성(적합성)이 큰 유전자를 신속히 구한 훙 단계적으로고 해상도에서 적합한 유전자로 진화시켜 나가는 방법으로 처음부터 최고 해상도에 유전자 알고리즘을 적용하는 종전의 방법보다 훨씬 더 효율적이며 유전자 알고리즘과 다단계 기법의 이상적인 결합이라 할 수 있다. 분할 결과에서도 타 알고리즘에 비하여 우수하거나 비슷한 결과를 얻었다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.195-197
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• 2000

데이더는 다양한 빈도 형태와 속성을 가지고 있으며 데이터의 연관 규칙 탐사 시 이러한 데이터의 빈도수를 고려할 수 있는 방법이 필요하다. 그러나 기존의 연관 규칙 탐사 알고리즘은 지지도와 신뢰도만을 가지고 데이터의 연관성을 발견하며 데이터들의 발생 빈도는 고려하지 않는다. 본 논문에서는 하위 단계의 데이터나 동일한 단계지만 상대적으로 발생 빈도가 적은 데이터들의 연관 규칙을 탐사할 수 있는 방법을 제안한다. 제안하는 방법은 데이터의 상대 지지도를 이용한 다단계 연관 규칙 탐사 기법을 수행함으로써 데이터의 발생 빈도를 고려한 연관 규칙을 탐사할 수 있다. 그리고 탐사된 연관 규칙은 마케팅 분야 등의 여러 응용에서 유용하게 이용될 수 있다.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.6
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• pp.493-497
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• 2016

Infrared (IR) imaging is capable of detecting targets that are not visible at night, thus it has been widely used for the security and defense system. However, the quality of the IR image is often degraded by low resolution and noise corruption. This paper addresses target segmentation with the IR image. Multiple regions of interest (ROI) are extracted by the multi-level segmentation and targets are segmented from the individual ROI. Each level of the multi-level segmentation is composed of a k-means clustering algorithm an expectation-maximization (EM) algorithm, and a decision process. The k-means clustering algorithm initializes the parameters of the Gaussian mixture model (GMM) and the EM algorithm iteratively estimates those parameters. Each pixel is assigned to one of clusters during the decision. This paper proposes the selection and the merging of the extracted ROIs. ROI regions are selectively merged in order to include the overlapped ROI windows. In the experiments, the proposed method is tested on an IR image capturing two pedestrians at night. The performance is compared with conventional methods showing that the proposed method outperforms others.

• Geotechnical Engineering
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• v.9 no.2
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• pp.27-40
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• 1993

This paper proposes a new procedure carrying out a series of consolidated-undrained triaxial tests with a specimen. In this procedure high confining pressure applied to the specimen keeps constant during the test and each stage of consolidation can be controlled by partial drainage. With this procedure the test time is remarkably reduced by performing a series of triaxial tests with a single specimen. In order to verify the appliesbility of the procedure, standard triaxial compression tests and conventional multi -stage triaxial testy are performed for both undisturbed and disturbed samples and the results are compared with those of the proposed procedure. The comparison shows that strength parameters determined by the proposed procedure are well agreed with those of the other tests and thus it can be said that the procedure is very effective and practical in determining strength parameters.