• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.27-35
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• 2010

Accurately extracting skin color regions is very important in various areas such as face recognition and tracking, facial expression recognition, adult image identification, health-care, and so forth. In this paper, we evaluate the performances of several skin color detection algorithms in indoor environments by changing the distance between the camera and the object as well as the background colors of the object. The distance is from 60cm to 120cm and the background colors are white, black, orange, pink, and yellow, respectively. The algorithms that we use for the performance evaluation are Peer algorithm, NNYUV, NNHSV, LutYUV, and Kimset algorithm. The experimental results show that NNHSV, NNYUV and LutYUV algorithm are stable, but the other algorithms are somewhat sensitive to the changes of backgrounds. As a result, we expect that the comparative experimental results of this paper will be used very effectively when developing a new skin color extraction algorithm which are very robust to dynamic real environments.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2470-2476
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• 1997

We propose a new real-time search algorithm and provide experimental evaluation and comparison of the new algorithm with mini-min lookahead algorithm. Many other real-time heuristic-search approached often divide the problem space to several sub-problems. In this paper, the proposed algorithm guarantees not only the sub-problem deadline but also total deadline. Several heuristic real-time search algorithms such as $RTA^{\ast}$, SARTS and DYNORA have been proposed. The performance of such algorithms depend on the quality of their heuristic functions, because such algorithms estimate the search time based on the heuristic function. In real-world problem, however, we often fail to get an effective heuristic function beforehand. Therefore, we propose a new real-time algorithm that determines the sub-problem deadline based on the status of search space during sub-problem search process. That uses the cut-off method that is a dynamic stopping-criterion-strategy to search the sub-problem.

• Convergence Security Journal
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• v.20 no.1
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• pp.3-8
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• 2020

Blockchain can enhance data transparency and security through decentralized data management that is out of the centralized system. permissioned blockchain of the blockchain platform, only trust-based authorized nodes can participate in the distributed network. Considering the characteristics of the permissioned blockchain, it is necessary to consider the network communication speed, transaction finality agreement, and stability as a condition for selecting the consensus algorithm. The consensus algorithms of the permissioned blockchain environment are diverse such as PoA, PBFT, Raft, etc., but there are no various evaluation factors for selecting consensus algorithms. In this paper, various performance evaluation factors are proposed to analyze the characteristics of each consensus algorithm of the permissioned blockchain and to select an efficient consensus algorithm considering the characteristics of the user environment that composes the network. The proposed performance evaluation factor can consider the network speed, stability, and consensus of the finality agreement between nodes under the premise of trust. Through this, a more efficient blockchain network environment can be constructed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.27-37
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• 2006

A Metropolis genetic algorithm (MGA) is developed and applied for the structural design optimization. In MGA, favorable features of Metropolis criterion of simulated annealing (SA) are incorporated in the reproduction operations of simple genetic algorithm (SGA). This way, the MGA maintains the wide varieties of individuals and preserves the potential genetic information of early generations. Consequently, the proposed MGA alleviates the disadvantages of premature convergence to a local optimum in SGA and time consuming computation for the precise global optimum in SA. Performances and applicability of MGA are compared with those of conventional algorithms such as Holland's SGA, Krishnakumar's micro GA, and Kirkpatrick's SA. Typical numerical examples are used to evaluate the computational performances, the favorable features and applicability of MGA. The effects of population sizes and maximum generations are also evaluated for the performance reliability and robustness of MGA. From the theoretical evaluation and numerical experience, it is concluded that the proposed MGA Is a reliable and efficient tool for structural design optimization.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.172-174
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• 1998

이동 컴퓨터들은 다른 컴퓨터들과 통신하기 위하여 무선채널을 사용한다. 효율적인채널 할당은 이동 컴퓨터 시스템 설계의 핵심부분이다. 유한개의 채널들은 처리력을 최대로 하고 채널 간섭을 피하기 위하여 효율적으로 할당되어져야 한다. 채널 할당 알고리즘들은 크게 집중형 채널 할당 알로리즘과 분산형 채널 할당 알고리즘으로 나누어지며, 그것들은 상반관계에 있다. 본 논문에는 고정 채널 할당 정책에 기반한 분산 채널 할당 알고리즘에 집중형 채널 할당 알고리즘을 혼합한 하이브리드 채널 할당 알고리즘을 제안하고, 그것의 성능을 평가한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05d
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• pp.896-900
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• 2002

본 논문에서는 기존의 워터마킹 알고리즘보다 채널에 대해서 더욱 강인한 특성을 위해 오류 정정 능력이 뛰어난 터보 부호 및 인간 시각 시스템을 이용한 디지털 워터마킹 방법을 제안하였다. 이 알고리즘에서는 터보 부호를 이용하여 워터마크를 생성하고, 채널에 강인한 특성을 위해 채널의 부가 정보를 이용하여 워터마크를 삽입한다. 제안한 워터마킹 알고리즘의 성능 평가를 위한 모의실험에서 제안한 워터마킹 알고리즘이 기존의 알고리즘보다 견고성면에서 우수함을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.490-492
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• 2001

세선화 알고리즘은 문자 인식에서 인식율을 높이기 위한 전처리과정으로 대상물체에 대하여 1픽셀 두께가 될 때까지 적용시키는 알고리즘으로 그 중요성과 필요성으로 인하여 수많은 논문들이 발표되었다. 본 논문에서는 인터넷 정보검색을 목적으로 하는 회색조(Gray) 영상에 대한 이진화 및 세선화 알고리즘을 제안한다. 제안된 알고리즘은 해당 픽셀과 이웃 화소 간의 픽셀값 차이를 이용하여 일정값을 증감시키는 방법으로, 이미지의 중심으로 픽셀이 응집하게 하는 과정을 통해 이진화 및 세선화를 시켰으며, 병렬 구현이 용이하다. 제안된 알고리즘의 성능평가는 회색조 영상에 대해 기존 알고리즘들을 적용한 결과와 비교, 분석하여 소개하였다.

• The Journal of Korean Association of Computer Education
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• v.17 no.4
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• pp.45-57
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• 2014

Many studies on algorithm judging system which verifies the correctness and the time efficiency of your program have been underway recently, most of which are on an online judging system focused on programming contests. However this study is mainly about development and application of the judging system based on client-server. Especially, we designed to promote metacognition and motivation which are emphasized in CRESST model, and implemented the total system that consists of the problem, data set, validation program, and user service environments. We applied our system to elementary, middle, and high school students, and We noticed a significant difference of average score between the experimental and control group in posttest and concluded that the teaching method using our system gave the bigger positive effects on programming learning.

• Journal of the Korean Society for Railway
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• v.17 no.6
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• pp.433-442
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• 2014

This paper evaluates the performance of transit assignment algorithms for urban rail networks. The accuracy of the algorithms is essential not just for travel forecasting but also for the area of applications such as the assessment of road vulnerability and the fare adjustments between train operating companies. Nonetheless, the suitability and caveats for the series of computational steps have not yet been much discussed. This study thus considers the characteristics that are appropriate for investigating Seoul rail travelers using three representative transit assignment algorithms: the optimal strategy algorithm, route choice algorithms, and the Dial's algorithm. Both the theoretical foundation and the empirical performance are examined. The results demonstrate that the Dial's algorithm is superior in terms of the theoretical soundness and the computational efficiency.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.24-24
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• 2015

최근 원격탐사기법을 이용한 많은 가뭄평가기법들이 개발되었으나 산림과 함께 산악지형이 우세한 우리나라의 경우 지형특성으로 인하여 가뭄평가시 불확실성이 증가하게 된다. 특히, 농업가뭄은 기후와 지표특성에 큰 영향을 받기 때문에 기후특성만을 고려한 가뭄지수는 실제 필요한 농업가뭄의 특성을 반영하는데 있어서 한계가 있다. 따라서 본 연구에서는 기후와 지표특성을 함께 고려할 수 있는 토양수분을 이용한 가뭄평가기법(Drought Assessment Scheme)을 개발하였다. 가뭄평가기법을 위하여 역추적기법(Inverse Modeling-IM) 기반의 자료동화기법(Data Assimilation, DA)을 이용하였다. 자료동화기법은 1-Dimensional (1-D) 기반의 토양의 물리적 특성을 고려하는 SWMI_ST 모형과 최적화 알고리즘(유전자 알고리즘, Genetic Algorithm-GA)을 연계하여 실측 및 위성기반의 토양수분자료로부터 토양의 수리학적 매개변수(${\alpha}$, n, ${\Theta}_{res}$, ${\Theta}_{sat}$, $K_{sat}$)를 추출한다. 본 연구에서는 LANDSAT(30 m X 30 m) 및 MODerate Resolution Imaging Spectroradiometer(MODIS, 500 m X 500 m) 이미지자료를 이용하여 시 공간적으로 분포되어 있는 토양수분을 산정하였으며, 이후 자료동화기법을 이용하여 LANDSAT/MODIS 토양수분자료로 부터 공간적으로 분포되어 있는 토양의 매개변수를 추출하였다. 추출된 매개변수, GIS 기반의 지표피복 및 기상자료를 이용하여 장기간의 토양수분을 산정 및 예측 할 수 있다. 고해상도의 이미지 자료를 사용하는 가뭄평가기법은 필지~시 군 단위까지 실제 우리나라 지형특성을 고려하여 효율적으로 가뭄을 모니터링 및 예측 할 수 있다.