• Journal of the Korea Society of Computer and Information
• /
• v.25 no.5
• /
• pp.65-72
• /
• 2020

To improve the performance of D2D power control algorithm proposed in the previous work, three modified D2D power control algorithms are proposed to compensate the channel estimation error. Then, we evaluate the performance of three modified D2D power control algorithms in the channel estimation error environment. In real channel environment, the channel estimation is not perfect. To that end, the impact of imperfect channel estimation on the D2D power control algorithm, which was developed with the assumption of perfect channel estimation, has been analyzed in the previous work. Three modified D2D power control algorithms are based on 1) Retransmission, 2) SIR Margin, and 3) Retransmission and SIR Margin. Simulation results show that the Retransmission and SIR Margin approach shows best performance in the sense of the transmit power consumption and the latency.

• Proceedings of the IEEK Conference
• /
• 2003.11a
• /
• pp.141-144
• /
• 2003

가장 최근의 동영상 압축 표준인 H.264는 매크로블록의 최적 모드를 결정하기 위하여 총 7가지 모드를 사용하여 움직임 예측을 수행하기 때문에 부호화 효율과 수행 성능 면에서 기존의 방식에 비해 좋은 결과를 보이지만, 움직임 예측 과정에서 많은 계산 시간을 필요로 한다는 것이 커다란 단점으로 지적되고 있다. 따라서, 본 논문에서는 H.264에서 가변 블륵 단위의 움직임 예측 시 인접한 블록과의 상관성을 분석하여 다음 움직임 예측 모드의 사용 여부를 결정하는 블록 병합 알고리즘을 HEXBS(Hexagon-based Search) 고속 움직임 탐색 알고리즘에 적용하여 움직임 예측 시간을 효율적으로 절약하는 방법을 제안한다.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.42 no.6
• /
• pp.33-42
• /
• 2005

In this paper, we propose an efficient segmentation algerian using morphological grayscale reconstruction for region-based coding. Each segmentation stage consists of simplification, marker extraction and decision. The simplification removes unnecessary components to make an easier segmentation. The marker extraction finds the flat zones which are the seed points from the simplified image. The decision is to locate the contours of regions detected by the marker extraction. For the simplification, we use a new connected operator based on the size and contrast. In the marker extraction stage, the regions reconstructed to original values we excluded from the candidate marker. For the other regions, the regions which are larger than structuring elements or have higher contrast than a threshold value are selected as markers. For the initial segmentation, the conventional hierarchical watershed algorithm and the extracted markers are used. Finally in the region merging stage, we propose an efficient region merging algorithm which preserves a high quality in terms of the number of regions. At the same time, the pairs which have higher contrast than a threshold are excluded from the region merging stage. Experimental results show that the proposed marker extraction method produces a small number of markers, while maintaining high quality and that the proposed region merging algorithm achieves a good performance in terms of the image quality and the number of regions.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1782-1787
• /
• 1997

A combined algorithm called APEXS(Alarm Processing and Diagnosis Expert System) for power plants has been developed on the time-based alarm processing with a proper alarm prioritization and a diagnosis with a qualitative model(QM), qualitative interpreter(QI), and a state-transition trees(STT).

• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06a
• /
• pp.341-342
• /
• 2008

• Journal of KIISE:Software and Applications
• /
• v.27 no.12
• /
• pp.1219-1226
• /
• 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
• /
• 2000.04b
• /
• pp.307-309
• /
• 2000

진화 알고리즘은 현재까지 다양한 최적화 문제들에 사용되어 왔고, 또한 이러한 최적화 문제들은 효율적으로 해결하기 위하여 많은 진화 알고리즘이 개발되어 왔다. 그러나 이러한 진화 알고리즘들의 공통적인 문제점은 탐색공간의 확대에 대하여 전반적으로 탐색시간이 오래 걸린다는 것이다. 실제로 최적화 해야 할 변수의 증가에 따라 탐색 차원이 증가하므로 탐색 시간도 기하급수적으로 늘어난다. 따라서 최근의 진화 알고리즘에 대한 연구는 탐색공간의 축소나, 진화 속도의 향상에 초점이 맞추어져 있었고, 이러한 경향에 따라 많은 연구성과가 있었다. Potter와 Dejong의 협력 공진화와, Weicker의 적응적 공진화가 바로 그것이다. 그러나 이 방법들도 최적화 해야 할 변수들이 서로 강한 의존성을 가지고 있는 경우나, 대부분의 변수가 서로 의존성을 가지고 있는 경우에는 그다지 좋은 결과를 보이지 못하는 문제점을 가지고 있다. 본 논문에서는 이러한 연구들을 기반으로 하여 각 방법의 단점들을 보완함으로써 효율을 향상시킨 새로운 진화 알고리즘을 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.2
• /
• pp.872-877
• /
• 2012

We proposes the method to detect the Hangul character region from natural image using topological structural feature of Hangul grapheme. First, we transform a natural image to a gray-scale image. Second, feature extraction performed with edge and connected component based method, Edge-based method use a Canny-edge detector and connected component based method applied the local range filtering. Next, if features are not corresponding to the heuristic rule of Hangul character, extracted features filtered out and select candidates of character region. Next, candidates of Hangul character region are merged into one Hangul character using Hangul character merging algorithm. Finally, we detect the final character region by Hangul character class decision algorithm. Experimental result, proposed method could detect a character region effectively in images that contains a complex background and various environments. As a result of the performance evaluation, A proposed method showed advanced results about detection of Hangul character region from mobile image.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.1A
• /
• pp.34-42
• /
• 2012

Low density parity check (LDPC) code is widely used, since it shows superior performance close to Shannon limit and its decoding complexity is lower than turbo code. Recently, it is used as a channel code to decode Wyner-Ziv frames in distributed video coding (DVC) system. In this paper, we propose an efficient method to design the parity check matrix H of LDPC codes. In order to apply LDPC code to DVC system, the LDPC code should have rate compatibility. Thus, we also propose a method to merge check nodes of LDPC code to attain the rate compatibility. LDPC code is designed using ACE algorithm and check nodes are merged for a given code rate to maximize the error correction capability. The performance of the designed LDPC code is analyzed extensively by computer simulations.

• Journal of KIISE:Computing Practices and Letters
• /
• v.7 no.6
• /
• pp.684-695
• /
• 2001

Recent recommender system uses a method of combining collaborative filtering system and content based filtering system in order to solve sparsity and first rater problem in collaborative filtering system. Collaborative filtering systems use a database about user preferences to predict additional topics. Content based filtering systems provide recommendations by matching user interests with topic attributes. In this paper, we describe a method for discovery of user preference through combining two techniques for recommendation that allows the application of machine learning algorithm. The proposed collaborative filtering method clusters user using genetic algorithm based on items categorized by Naive Bayes classifier and the content based filtering method builds user profile through extracting user interest using relevance feedback. We evaluate our method on a large database of user ratings for web document and it significantly outperforms previously proposed methods.