• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.304-307
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• 2021

ML(machine learning) 기술을 활용하여 실용적인 측면에서 일반 사용자들이 바라보고 사용할 수 있도록 다양한 연구 개발이 이루어지고 있다. 특히 최근 개인 사용자의 personal computer와 mobile device의 processing unit의 연산 처리 속도가 두드러지게 빨라지고 있어 ML이 더 생활에 밀접해지고 있는 추세라고 볼 수 있다. 현재 ML시장에서 다양한 솔루션 및 어플리케이션을 제공하는 툴이나 라이브러리가 대거 공개되고 있는데 그 중에서도 Google에서 개발하여 배포한 'Mediapipe'를 사용하였다. Mediapipe는 현재 'android', 'IOS', 'C++', 'Python', 'JS', 'Coral' 등의 환경에서 개발을 지원하고 있으며 더욱 다양한 환경을 지원할 예정이다. 이에 본 팀은 앞서 설명한 Mediapipe 프레임워크를 기반으로 Machine Learning을 사용한 image processing를 통해 일반 사용자들에게 편의성을 제공할 수 있는 알람 프로그램을 연구 및 개발하였다. Mediapipe에서 신체를 landmark로 검출하게 되는데 이를 scikit-learn 머신러닝 라이브러리를 사용하여 특정 자세를 학습시키고 모델화하여 알람 프로그램에 특정 기능에 조건으로 사용될 수 있게 하였다. scikit-learn은 아나콘다 등과 같은 개발환경 패키지에서 간단하게 이용 가능한데 이 아나콘다는 데이터 분석이나 그래프 그리기 등, 파이썬에 자주 사용되는 라이브러리를 포함한 개발환경이라고 할 수 있다. 하여 본 팀은 ML기반의 영상처리 알람 프로그램을 제작하는데에 있어 이러한 사항들을 파이썬 환경에서 기본적으로 포함되어 제공하는 tkinter GUI툴을 사용하고 추가적으로 인텔에서 개발한 실시간 컴퓨터 비전을 목적으로 한 프로그래밍 라이브러리 OpenCV와 여러 항목을 사용하여 환경을 구축할 수 있도록 연구·개발하였다.

• Journal of Digital Contents Society
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• v.15 no.2
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• pp.197-207
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• 2014

Many people are now enjoying mobile games using various smartphone platforms. However, we have to develop games separately for each smart device platforms so far. Cocos2d-x, a game development framework is released to solve this problem. As a multiplatform version of the existing Cocos2d, Cocos2d-x can make one source code run on various platforms. It is an open software that is able to be used by everyone, and when using it, mobile games can be developed easily based on C++ and OpenGL. In this paper, we implemented a PC laboratory decorating game application, named ILove501, using Cocos2d-x. The 501 is a room number of our PC lab. ILove501 includes an educational feature of solving quizzes in order to highlight positive effects of game. For implementation of a multiplatform game, ILove501 was developed in Windows and iOS environment at the same time, and we verified the results of the execution by porting on a variety of devices such as Android, iPhone, iPad and Galaxy Tab.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2105-2112
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• 2013

In this paper we implemented a web-based performance monitoring system for web mail server. For this system we derived performance monitoring items and fixed its threshold values for each measuring items. We used the SCOM 2007 server monitoring tool for collecting the performance data of web mail server and Exchange server management pack and server monitoring rules of SCOM 2007 to set the performance analysis parameters. We implemented this performance monitoring system using C# programming based on the ASP.NET framework. This system supports web-based performance report, failure report and resource availability report from the performance analysis results. Therefore the manager can easily detect the failures of web mail server in advance and decrease the number of failure over 60%. Also this system helps manager to minimize the recovery time when the failure occurs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.515-520
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• 2014

In this paper, the protograph-based block low density parity check (LDPC) code, which improves the performance and reduces the encoder/decoder complexity than the conventional Digital Video Broadcasting Satellite Second Generation (DVB-S2) LDPC code used for the marine satellite communication, is proposed. The computer simulation results verify that the proposed protograph-based LDPC code has the better performance in both the bit error rate (BER) and the frame error rate (FER) than the conventional DVB-S2 LDPC code. Furthermore, by analyzing the encoding and decoding computational complexity, we show that the protograph-based block LDPC code has the efficient encoder/decoder structure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.8
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• pp.663-673
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• 2013

The drastic growth of mobile communication and spreading of smart phone make the significant attention on Location Based Service. The one of most important things for vitalization of LBS is the accurate estimating position for mobile object. Focusing on IMU deployed in smart phone, we develop a hybrid positioning estimation framework with a combination of WPS. The developed approaches can strengthen the advantages of independent indoor applicability of IMU. The estimation of IMU is efficiently compensated by radio fingerprint based Wi-Fi Positioning System. We put a focus especially on the hybrid algorithmic framework. Compared on the existing approaches of WPS or IMU, we achieve the comparable higher performance on both of average error of estimation and deviation of errors. Furthermore test-bed based on smart phone platform is practically developed and all data have been harvested from the actual measurement of test indoor area. This can approve the practical usefulness of proposed framework.

• Journal of the Korean Society for Heat Treatment
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• v.19 no.1
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• pp.30-36
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• 2006

Fretting fatigue behavior of SCM420 steel commonly used in the automotive industry for structural applications was investigated in this study. In addition, the effect of bridge pad on the fretting fatigue test was evaluated from different pad materials and following conclusions were drawn. Simple fatigue limit of SCM 420 steel was determined to be 350 MPa while this value was 225 MPa and 285.5 MPa with SCM420H and with SM45C pad, respectively. Reduction in fatigue limit was, thus found to be 35.7% and 17.9% with SCM 420H pad and SM45C pad, respectively. Results of fracture surface observation revealed that typical striation pattern of fatigue failure existed as well as dimpled and cleavage frature appearance was found in final fractured region. From the EDS compositional analysis, test sample and pad part all had high signals for oxygen and iron, suggesting that worn particles might be iron oxide, although exact chemical composition has to be confirmed. Considerable reduction in fatigue life was apparent in SCM 420 steel under fretting fatigue against simple fatigue. Such reduced fatigue life by fretting damage should be considered as an important factor not only in the viewpoint of repairing but also inevitably in the design stage of structural components.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1338-1345
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• 2014

Recently, wireless technology gains attention for industrial networks due to low cost, flexibility, relatively easy installation and most importantly, solving the rouring issue. ISA100.11a is one of promising standard for wireless industrial networks (WINs). Data traffic in industrial networks are known to be periodic and must satisfy the real-time property namely deadline. Therefore, in this paper, we proposed to apply deadline monotonic scheduling to periodic tasks in ISA100.11a networks and to evaluate the performance of ISA100.11a by checking the schedulability and beacon frame overhead. Simulation results showns, that our proposed scheme can reduces the network overhead while maintaining schedulability as compared to the previous algorithm. In addition, by reducing the network overhead, our proposed scheme can send more data without degrading the overall performance of WINs.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.96-101
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• 2012

An experimental study was conducted to investigate the performance of a concentrating photovoltaic cell (CPV) against temperature. It is know that a high efficiency of a CPV can be achieved only with proper cell temperature as well as high concentration ratio (CR). This study is concerned with appropriate cooling condition for a liquid-convection cooler for the best performance of a specific CPV. A series of experiments was conducted in a range of cell temperatures as a result of varying cooling conditions, while the concentration ratio was 390 and the solar irradiation flux was higher than 900 $W/m^2$ in outdoor environment. The CPV had a planar dimension of 10 by 10 mm. A Fresnel lens was used as a concentrator, of which the dimension was 221 mm(W) ${\times}$ 221 mm(L) ${\times}$ 3 mm(t) and the transmissivity was known to be 0.8. The cooler was attached to the bottom side of the CPV and had a contact area of 21 mm(W) ${\times}$ 26 mm(L), which was identical to the size of the base plate of the CPV. The coolant temperature was controlled by an isothermal bath and the flow rate was controlled and measured by a flowmeter. The experimental results showed that the average of power efficiency of the CPV decreased from 28.6 % to 24.7 % as the cell temperature increased from $36^{\circ}C$ to $97^{\circ}C$. An appropriate cooling method of a CPV might increase the power conversion efficiency by about 4% for the same concentration ratio. Discussion is included from the viewpoint of the combined efficiency in addition to the power efficiency.

• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.293-304
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• 2011

In this paper, we proposed a new hardware architecture for motion estimation (ME) which is the most time-consuming unit among H.264 algorithms and designed to the type of intellectual property (IP). The proposed ME hardware consists of buffer, processing unit (PU) array, SAD (sum of absolute difference) selector, and motion vector (MVgenerator). PU array is composed of 16 PUs and each PU consists of 16 processing elements (PUs). The main characteristics of the proposed hardware are that current and reference frames are re-used to reduce the number of access to the external memory and that there is no clock loss during SAD operation. The implemented ME hardware occupies 3% hardware resources of StatixIII EP3SE80F1152C2 which is a FPGA of Altera Inc. and can operate at up to 446.43MHz. Therefore it can process up to 50 frames of 1080p in a second.

• The Transactions of the Korea Information Processing Society
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• v.6 no.8
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• pp.2188-2195
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• 1999

This paper proposes a new call admission control scheme utilizing an inverse fuzzy vector quantizer(IFVQ) and neuralnet, which combines benefits of IFVQ and flexibilities of FCM(Fuzzy-C-Means) arithmetics, to decide whether a requested call not to be trained in learning phase to be connected or not. The system generates the estimated traffic pattern for the cell stream of a new call, using feasible/infeasible patterns in codebook, fuzzy membership values that represent the degree to which each pattern of codebook matches input pattern, and FCM arithmetics. The input to the NN is the vector consisted of traffic parameters which are the means and variances of the number of cells arriving in decision as to whether to accept or reject a new call depends on whether the NN is used for decision threshold(+0.5). This method is a new technique for call admission control using the membership values as traffic parameter which declared to CAC at the call set up stage, and this is valid for a very general traffic model in which the calls of a stream can belong to an unlimited number of traffic classes. Through the simulations, it is founded the performance of the suggested method outperforms compared to the conventional NN method.