• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.130-142
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• 2009

In this paper, we propose a self-adaptation framework that selects a TCP variant adapted to current end-to-end path among available TCP variants. There is no single version of TCP that is suitable to all network environments since the causes for performance degradation are different one another according to characteristics of network environments. Thus, determining that which TCP variants should be selected in order to get best performance is very important. To enable adaptation through such determination, we integrate the existing network estimation schemes and some TCP variants into our framework then make light-weight performance knowledge database for TCP selection. Through implementing and evaluating the proposed framework we show that our solution can help TCP get high and stable performance on the various types of network environments by pure end-to-end.

• Journal of the Korea Society of Computer and Information
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• v.13 no.2
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• pp.1-9
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• 2008

As the size of software becomes larger and the features of it become complex. it is really hard to successfully complete the project without following development guidelines. Software process is the best practices and procedures that organizations of high maturity and capability of software development carry out in common, and it is a set of progressive ideas of management. However, complicated and unfamiliar concepts can interrupt the introduction and improvement of software process of the organizations. Even though many kinds of frameworks such as standard of process and maturity measurement models are introduced, it is still difficult to follow software process without fully understanding their relations. The purpose of this study is to support successful internalization of organizations that introduce and use software process. It also suggests the design of standard ontology, standard relationship domain ontology, and the lifestyle of software process and the relations between them.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3A
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• pp.267-277
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• 2011

Like other wireless network protocols, IEEE 802.15.4 adopts CA (Collision Avoidance)algorithm to avoid the early collision of a new packet by randomizing its first transmission time rather than its immediate delivery. The traditional CA scheme of IEEE 802.15.4, however, selects the random access time from the predetermined range without considering the degree of current congestion. It probably causes either a long delay to settle in the suitable range for the current network load or frequent clashes especially during the long lasting heavy traffic period. This paper proposes an ACA(Adaptive Collision Avoidance) algorithm adapting the initial backoff range to the undergoing collision variations. It also introduces a mathematical model to predict the performance of ACA algorithm added to IEEE 802.15.4. With only small deviations from corresponding simulations, our analytical model shows that ACA technique can improve the throughput of IEEE 802.15.4 by up-to 41% maximally in addition to shortening the packet delays.

• Journal of the Korea Society of Computer and Information
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• v.15 no.9
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• pp.165-172
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• 2010

Communication problems have been regarded as one of the biggest causes in trouble in many industries. This led to extensive research on communication as a part of human error analysis. The results of existing researches have revealed that maintaining a good quality of communication is essential to secure the safety of a large and complex process system. In this paper, we suggested a method to measure the quality of communication during off-normal situation in main control room of nuclear power plants. It evaluates the cosine similarity that is a measure of sentence similarity between two operators by finding the cosine of the angle between them. To check the applicability of the method to evaluate communication quality, we compared the result of communication quality analysis with the result of operation performance that was performed by operators under simulated environment.

• Journal of Digital Convergence
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• v.17 no.2
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• pp.155-161
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• 2019

Electroencephalography (EEG), a representative method of identifying temporal and spatial changes in brain activity, is a voluntary electrical activity measurable in the human scalp. Various interface technologies have been provided to control EEG activity, and it is possible to operate a machine such as a wheelchair or a robot through brainwaves. The characteristics of EEG data are collected in various types of channels in real time, and a server system for analyzing them is required to have an independent and lightweight system for the platform. In these days, the Spring platform is used as a large business server as an independent, lightweight server system. In this paper, we propose an EEG analysis system using the Spring server system. Using the proposed system, the reliability of EEG control can be enhanced, and analysis and control interface expansion can be provided in various aspects such as game and medical areas.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.886-895
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• 2005

As the networked media technology have been grown in recent, there have been many research works to deliver high-quality video such as HDV and HDTV over the Internet. To realize high-quality media service over the Internet, however, the network adaptive streaming scheme is required to adopt to the dynamic fluctuation of underlying networks. In this paper, we design and implement the network-adaptive HD(high definition) MPEG-2 streaming system employing the frame-based prioritized packetization. Delivered video is inputted from the JVC HDV camera to the streaming sewer in real-time. It has a bit-rate of 19.2 Mbps and is multiplexed to the MPEG-2 TS (MPEG-2 MP@HL). For the monitoring of network status, the packet loss rate and the average jitter are measured by using parsing of RTP packet header in the streaming client and they are sent to the streaming server periodically The network adaptation manager in the streaming server estimates the current network status from feedback packets and adaptively adjusts the sending rate by frame dropping. For this, we propose the real-time parsing and the frame-based prioritized packetization of the TS packet. The proposed system is implemented in software and evaluated over the LAN testbed. The experimental results show that the proposed system can enhance the end-to-end QoS of HD video streaming over the best-effort network.

• Journal of the Korea Computer Graphics Society
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• v.23 no.3
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• pp.95-103
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• 2017

Horizon correction is a crucial stage for image composition enhancement. In this paper, we propose a deep learning based method for estimating the slanted angle of a photograph and correcting it. To estimate and correct the horizon direction, existing methods use hand-crafted low-level features such as lines, planes, and gradient distributions. However, these methods may not work well on the images that contain no lines or planes. To tackle this limitation and robustly estimate the slanted angle, we propose a convolutional neural network (CNN) based method to estimate the slanted angle by learning more generic features using a huge dataset. In addition, we utilize multiple adaptive spatial pooling layers to extract multi-scale image features for better performance. In the experimental results, we show our CNN-based approach robustly and accurately estimates the slanted angle of an image regardless of the image content, even if the image contains no lines or planes at all.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.183-186
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• 2009

인터넷의 발전과 비디오 압축 코덱의 발전으로 인해 실시간 영상 스트리밍 (Streaming) 서비스가 가능해졌다. 하지만, 패킷 손실로 인한 비디오 화질 열화는 여전히 문제가 되고 있다. 이 때문에 부호화기 에서는 에러에 강한 내성을 가지는 부호화방법으로 압축하며, 복호화기 에서는 에러 은닉기법을 통하여 패킷 손실에 의한 화질열화를 최소화한다. 이런 기법들을 활용하기 위해서는 패킷손실을 보정한 정확한 화질 열화를 측정 할 수 있는 방법이 필요하다. 영상의 화질을 평가하는 방법은 어떤 정보를 기준으로 평가하느냐에 따라서 전체 기준법 (Full Reference), 부분기준법 (Reduced Reference) 그리고 무기준법 (No Reference)으로 나눌 수 있다. 이중에서 무기준법은 수신 영상만을 가지고 측정하기 때문에, 다른 방법보다 활용범위가 넓다. 본 논문에서는 패킷 비디오 네트워크 환경에서의 발생할 수 있는 다양한 패턴의 패킷 손실에 따른 비디오의 화질 열화를 무기준법에 의해 측정하는 방법을 제안한다. 제안한 방법은 수신된 영상의 움직임 정보를 이용하여 패킷 손실에 따른 각 프레임당 초기 에러 값을 예측 한다. 실험 결과를 통하여 제안한 방법이 상당히 높은 피어슨 상관도 (Pearson Correlation)를 보여준다.

• Journal of Internet Computing and Services
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• v.7 no.3
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• pp.169-178
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• 2006

In this paper, we define the large word sets which are noble variations the large item sets in mining association rules, and improve the accuracy for NaiveBayes based on the defined large word sets. In order to use them, a document is divided into the several paragraphs, and then each paragraph can be transformed as the transaction by extracting words in it. The proposed method was implemented by using Al:Categorizer framework and its accuracies were measured by the experiments for reuter-21578 data set. The results of the experiments show that the proposed method improves the accuracy of the conventional NaiveBayes.

• Journal of Digital Contents Society
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• v.13 no.3
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• pp.353-358
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• 2012

Wireless sensor networks consist of resource constraint devices which typically send data measured by sensors attached to the end devices towards a coordinator. The most often used medium access control protocol used in wireless sensor networks is the standard IEEE 802.15.4, where it is wireless standard introduced for low power, low cost wireless communication with moderate data rates. In this paper, we present implementation of both the IEEE 802.15.4 protocol stack and UART interface on the TI CC2530. We show that data via UART of our implemented IEEE 802.15.4 board are transmitted correctly in terms of captured frames.