• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1B
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• pp.15-20
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• 2012

In this paper, an algorithm that enhances the conventional directional CSMA/CA protocol in IEEE 802.15.3c is proposed under saturation environments. For the algorithm, a Markov chain model is presented and analyzed in no-ACK mode. The effects of directional antennas and the features of IEEE 802.15.3c MAC are considered in the model. The optimal sizes of contention window are derived from the numerical results. The numerical results show that the proposed directional CSMA/CA algorithm outperforms conventional one. The overall analysis is verified by simulation. The obtained results provide the criterion for selecting the optimal parameters and developing a MAC protocol that enhances the performance of mmWave WPANs.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.4
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• pp.324-329
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• 2000

본 논문에서는 잡음환경에서의 음질향상(Speed Ehnacement) 시스템 구현을 목적으로 한다. 이를 위한 적응필터로서 LSM(Least Mean square)알고리즘 FIR필터를 적용한다. 또 정밀 필터로서 다충신경망(MLP, Multi-Layer Perceptorn) 필터를 적용한다. 잡음환경에서의 음성신호 복원 및 음질향상 시스템은 잡음에 의해 왜곡된 음성신호에서 잡음성분만을 제거함으로써 음성신호를 복원하는 시스템이다. 신경망 필터는 오차 역전과 학습 알고리즘에 의해 오차를 최소화 하는 방향으로 필터의 피라미터를 수정한다. 제안한 필터로 잡음환경에서의 음성신호복원 시스템을 구서오하고, 실험을 필터의 성능을 확인한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.582-584
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• 2013

본 논문에서는 스마트폰의 급격한 확산과 함께 보급되는 다양한 SWD(Smart Wellness Device)로부터 파생된 데이터를 센싱하여 습득할 때 생기는 문제점을 개선하고 신뢰성을 향상시키기 위하여 관련 정보를 조사 및 분석하였다. 이를 통해 스마트 웰니스 시스템에서 SWD를 통해 수집된 데이터의 신뢰성을 잃는 문제점을 해결하고 신뢰성 향상을 위한 데이터 추출 및 전송 알고리즘을 설계하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.942-949
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• 2004

This paper proposes and analyzes the anti-collision algorithm in Ubiquitous ID system. We mathematically compares the performance of the proposed algorithm with that of binary search algorithm, slotted binary tree algorithm using time slot, and bit-by-bit binary tree algorithm proposed by Auto-ID center. We also validated analytic results using OPNET simulation. Based on the analytic results, comparing the proposed algorithm with bit-by-bit algorithm which is the best of existing algorithms, the performance of proposed algorithm is about 5% higher when the number of tags is 20, and 100% higher when the number of tags is 200.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.3010-3023
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• 1998

GA has a fast convergence speed in searching the one point around optimal value. But it's convergence time increase in searching the region around optimal value because it has no regional searching mechanism. BP has the tendency to converge the local minimum because it has global searching mechanism. To overcome these problems, a method in which a genetic algorithm and a back propagation are applied in turn is proposed in this paper. By using a genetic algorithm, we compute optimal synaptic strength and offset value. And then, these values are fed to the input of the back propagation. This proposed method is superior to each above method in improving the convergence speed.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.01a
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• pp.119-122
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• 2012

정보화시대에 요구하는 인재는 문제를 인식하고 이런 문제를 풀기 위해 다양한 전문가들과 함께 창의적인 사고를 통해 해결책을 제시하는 인물이다. 정보영재교육의 목표 역시 창의적 인재를 기르는 데 있으나, 프로그래밍과 알고리즘 교육은 특정 프로그래밍 언어의 사용법이나 문법 위주의 교육, 정렬 및 탐색과 같은 알고리즘 그 자체에 치중함으로서 이러한 목표에 도달하고 있지 못하다는 지적이 많다. 이에 본 논문에서는 창의적인 알고리즘을 설계하고 개발하는데 필요한 사고력, 즉 사고 과정에 대해 안내하고 생각하는 알고리즘적 사고력을 기르기 위한 방안으로 실생활 주제의 이야기 쓰기를 활용하는 교수 학습 프로그램을 제안하였다. 반성적 사고와 창의성을 기르는 데 효과적인 것으로 알려진 이야기 쓰기 활동에서 출발하여 사건 요소 추출과 시간적 질서 분석하기, 순서도로 알고리즘 표현하기, 동료 학습자와 토의하기 등의 과정을 통해 알고리즘적 사고력을 향상시킬 수 있도록 하였다.

• The KIPS Transactions:PartD
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• v.14D no.1 s.111
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• pp.139-144
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• 2007

In seeking to improve the workload efficiency and inference capability of context-aware systems, we propose a new framework for an advanced teaming mechanism that uses improved bath propagation (BP) algorithm. Even though a learning mechanism is one of the most important parts in a context-aware system, the existing algorithms focused on facilitating systems by elaborating the learning mechanism with user's context information are rare. BP is the most adaptable algorithm for learning mechanism of context-aware systems. By using the improved BP algorithm, the framework we proposed drastically improves the inference capability so that the overall performance is far better than other systems. Also, using the special system cache, the framework manages the workload efficiently. Experiments show that there is an obvious improvement in overall performanre of the context-awareness systems using the proposed framework.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.81-89
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• 2021

Under natural conditions, Apple detection has the problems of occlusion and small object detection difficulties. This paper proposes an improved model based on SSD. The SSD backbone network VGG16 is replaced with the ResNet50 network model, and the receptive field structure RFB structure is introduced. The RFB model amplifies the feature information of small objects and improves the detection accuracy of small objects. Combined with the attention mechanism (SE) to filter out the information that needs to be retained, the semantic information of the detection objectis enhanced. An improved SSD algorithm is trained on the VOC2007 data set. Compared with SSD, the improved algorithm has increased the accuracy of occlusion and small object detection by 3.4% and 3.9%. The algorithm has improved the false detection rate and missed detection rate. The improved algorithm proposed in this paper has higher efficiency.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.4
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• pp.209-215
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• 2020

In this paper, we propose an algorithm for segmenting weld bead images using edge enhancement and active contours. In the proposed method, high-frequency filtering and contrast improvement are performed for edge enhancement, and then, by applying the active contour method, only the weld bead region can be obtained. The proposed algorithm detects an edge through high-frequency filtering and reinforces the detected edge by using contrast enhancement. After the edge information is improved in this way, the weld bead area can be extracted by applying the active contour method. The proposed algorithm shows better performance than the existing methods for segmenting the weld bead in the image. For the objective reliability of the proposed algorithm, it was compared with the existing high pass filtering methods, and it was confirmed that the welding bead segmentation of the proposed method is excellent. The proposed method can be usefully used in evaluating the quality of the weld bead through an additional procedure for the segmented weld bead.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.8 no.12
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• pp.89-95
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• 1985

MRP System에서 시스템 성능을 향상시킬 수 있는 하나의 인자는 우수한 Lot-Sizing rule의 선택과 발견이다. 널리 사용되고 있는 Lot-Sizing rule 들 중 Wagner-Whitin 알고리즘은 생산준비 비용과 재고 유지비용이 가변적일 경우 동적 로트크기 결정에 우수한 forward 알고리즘이다. 본 연구에서는 Wagner-Whitin 알고리즘의 중요 원리들을 응용하여 LDS 알고리즘이라 명명한 backward 알고리즘을 개발한다. 그리고 개발된 알고리즘을 Wagner-Whitin 알고리즘과 비교함으로 그 유효성을 테스트하고 backward 알고리즘이 가지는 계산상의 장점을 고찰한다.