• 대한수학회보
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• 제41권1호
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• pp.125-135
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• 2004

One of the intriguing and fundamental algorithmic graph problems is the computation of the strongly connected components of a directed graph G. In this paper we first introduce a simple procedure for determining the location of the nonzero elements occurring in $B^{-1}$ without fully inverting B, where EB\;{\equiv}\;(b_{ij)\;and\;B^T$ are diagonally dominant matrices with $b_{ii}\;>\;0$ for all i and $b_{ij}\;{\leq}\;0$, for $i\;{\neq}\;j$, and then, as an application, show that all of the strongly connected components of a directed graph G can be recognized by the location of the nonzero elements occurring in the matrix $C(G)\;=\;(D\;-\;A(G))^{-1}$. Here A(G) is an adjacency matrix of G and D is an arbitrary scalar matrix such that (D - A(G)) becomes a diagonally dominant matrix.

• 한국정보처리학회논문지
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• 제6권2호
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• pp.299-306
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• 1999

생성트리와 같은 문제를 해결하는데 필요한 정보가 네트워크상의 프로세서에 분산되어 있는 상황에서 그들 정보를 교환하면서 그 문제를 해결하는 알고리즘을 분산알고리즘(Distributed Algorithm)이라고 한다. 생성트리와 강결합요소가 이미 구성되어 있는 비동기식 네트워크상에서 네트워크 형상이 변할 경우, 이로 인해 구성되어 있던 생성트리와 강결합요소를 갱신해야 해는 경우가 발생한다. 본 논문에서는 이러한 경우 생성트리와 강결합요소를 효율적으로 갱신하는 메시지 복잡도 O(n'log n'+ (n'+s+t)), 이상시간복잡도 O(n'log n')의 분산 알고리즘을 제안한다. 여기서 n'는 토폴로지 변화후의 네트워크의 프로세서수, s는 추가 링크수를 나타낸다. 또 t는 삭제 링크를 포함하는 강결합요소에 포함되어 있는 전체 링크수를 나타낸다.

• International Journal of Contents
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• 제8권1호
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• pp.30-38
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• 2012

Text extraction and binarization are the important pre-processing steps for text recognition. The performance of text binarization strongly related to the accuracy of recognition stage. In our proposed method, the first stage based on line detection and shape feature analysis applied to locate the position of a business card and detect the shape from the complex environment. In the second stage, several local regions contained the possible text components are separated based on the projection histogram. In each local region, the pixels grouped into several connected components based on the connected component labeling and projection histogram. Then, classify each connect component into text region and reject the non-text region based on the feature information analysis such as size of connected component and stroke width estimation.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.641-651
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• 2006

거대한 웹 컨텐츠 안에는 수많은 링크들로 인한 순환들이 존재하게 된다. 그 순환들은 강하게 뭉쳐있는 실타래 처럼, 강하게 결합한 순환들의 덩어리 형태로 존재하게 된다. 웹 컨텐츠는 흔히 방향그래프로 표현되는데, 즉 웹 컨텐츠에서 나타나는 수많은 링크둘을 방향그래프에서 강결합요소를 이용하면 모든 순환을 효율적으로 발견할 수 있다. 본 논문에서는 강결합요소를 이용하여 거대한 그래프에서 보다 효율적으로 모든 순환을 찾아낼 수 있는 방법을 제시하였다.

• 한국압력기기공학회 논문집
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• 제6권1호
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• pp.29-36
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• 2010

Ultrasonic inspection of heavy walled cast austenitic stainless steel(CASS)welds is very difficult due to complex and coarse grained structure of CASS material. The large size of anisotropic grain strongly affects the propagation of ultrasound by severe attenuation, change in velocity, and scattering of ultrasonic energy. therefore, the signal patterns originated from flaws can be difficult to distinguish from scattered signals. To improve detection and sizing capability of ID connected defect for heavy walled CASS piping welds, the low frequency segmented TRL Pulse Echo and Phased Array probe has been developed. The experimental studies have been performed using CASS pipe mock-up block containing artificial reflectors(ID connected EDM notch). The automatic pulse echo and phase array technique is applied the detection and the length sizing of the ID connected artificial reflectors and the results for detection and sizing has been compared respectively. The goal of this study is to assess a newly developed ultrasonic probe to improve the detection ability and the sizing of the crack in coarse-grained CASS components.

• Tribology and Lubricants
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• 제23권5호
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• pp.228-233
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• 2007

This paper presents the case studies on the friction related wears of an automotive tire, which is strongly connected to the safety and comfort of a driver during a running of a car. Wear scars of a tire tread are affected by various causes such as an air pressure, a wheel alignment, a driving speed, road conditions, starting and braking habits of a driver. The data were collected from used tires for a replacement at the car service center. Most of the wear problems came from the improper repair and adjustment of revolving components, which cause an unbalanced wear of a tread part of a tire. Thus, the regular checking of a tire radically reduces the wear scars of a tire and may increase a driving safety and a fuel economy of a car and a wear life of a tire.

• 디지털산업정보학회논문지
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• 제17권2호
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• pp.13-20
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• 2021

Placement is a very important step in the VLSI physical design process. It is the problem of placing circuit modules to optimize the circuit performance and reliability of the circuit. It is used at the layout level to find strongly connected components that can be placed together in order to minimize the layout area and propagation delay. The most popular algorithms for circuit placement include the cluster growth, simulated annealing, integer linear programming and genetic algorithm. In this paper we propose a adapted genetic algorithm searching solution space for the placement problem, and then compare it with simulated annealing and genetic algorithm by analyzing the results of each implementation. As a result, it was found that the adaptive genetic algorithm approaches the optimal solution more effectively than the simulated annealing and genetic algorithm.

• 조명전기설비학회논문지
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• 제26권6호
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• pp.8-15
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• 2012

In this paper, we investigated possible optical parameters causing deviation of experimentally observed output spectra from theoretically predicted results in a high-order fiber comb filter based on a polarization-diversity loop configuration. They include wavelength dependency of half-wave plates (HWPs) inserted in the filter for wavelength switching and the modal birefringence of single-mode fibers (SMFs) with which optical components comprising the filter are connected. In order to consider the effect of the modal birefringence of the SMF on a filter performance, it is modeled as a low birefringence fiber with an arbitrary orientation angle and birefringence. It is found from the simulation results that the modal birefringence of SMFs strongly affects the spectral characteristics of the filter and decreases the extinction ratio of the filter, compared with the wavelength dependency of HWPs. In particular, it is also confirmed that the spectral deviation and asymmetric distortions of side-lobes in narrow band transmission spectra result mainly from the modal birefringence of SMFs.

• 융합신호처리학회논문지
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• 제2권4호
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• pp.97-102
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• 2001

CAD(Computer-Aided Design)에서의 분할(partitioning)은 기능의 최적화를 위해 대상의 그룹화(grouping)로 레이아웃(layout)에 면적과 전파지연 최소화를 위해 함께 위치할 소자를 결정하는 문제 또는 스케쥴링이나 유닛 선택을 위한 HLS(high level synthesis)에서의 변수나 연산에 대한 집단화 (clustering) 문제들을 포함하여 분할 문제에서 해를 얻기 위해 Kernighan-Lin 알고리즘 Fiduccia Mattheyses heuristic, 시뮬레이티드 어닐링(simulated annealing)등의 방식이 이용된다. 본 논문에서는 회로 분할 문제에 대하여 유전 알고리즘(GA; genetic algorithm)을 이용한 해 공간 탐색(soultion space search)방식을 제안하였으며, 제안한 방식을 시뮬레이티드 어닐링 방식과 비교, 분석하였다.

• 한국콘텐츠학회논문지
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• 제21권7호
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• pp.164-170
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• 2021

VLSI 설계에서의 분할(partitioning)은 기능의 최적화를 위하여 설계하고자 하는 회로의 그룹화(grouping)하는 단계로서 레이아웃(layout)에서 면적과 전파지연의 최소화를 위해 함께 배치할 소자를 결정하는 문제이다. 이러한 분할 문제에서 해를 얻기 위해 사용되는 알고리즘은 Kernighan-Lin 알고리즘, Fiduccia Mattheyses heuristic, 시뮬레이티드 어닐링, 유전자 알고리즘 등의 방식이 이용된다. 본 논문에서는 회로 분할 문제에 대하여 유전자 알고리즘과 확률 진화 알고리즘을 결합한 어댑티드 유전자 알고리즘을 이용한 해 공간 탐색(solution space search) 방식을 제안하였으며, 제안한 방식을 유전자 알고리즘 및 시뮬레이티드 어닐링 방식과 비교, 분석하였고, 어댑티드 유전자 알고리즘이 시뮬레이티드 어닐링 및 유전자 알고리즘보다 더 효과적으로 최적해에 근접하는 것을 알 수 있었다.