• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1200-1205
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• 2006

In this paper, it is presented to the designed and implemented care system fur health diagnosis. The designed handhold care system is implemented by embedded Visual C++4.0 and Pocket PC2003 software development kit (SDK) in an 802.11 wireless network, and we were conducted that the research provide sufficiently the usefulness of the U health system for the collection of care management information. The proposed system is consists of care management module for health diagnosis, personal record module, data transport module, image information management module for clinic. Also, fur emergency status, transmission function of clinic information is implemented by wireless LAN protocol and serial communication.

• The KIPS Transactions:PartB
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• v.10B no.1
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• pp.103-110
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• 2003

SMIL is a declarative markup language based on XML, which enables users to make effective multimedia presentations on the web by synchronizing media objects. In this paper, we design and implement a SMIL authoring tool which support Intuitive creation of web multimedia documents and diverse practical use of created information. Besides, creation, management and authoring module of SMIL document, it offers template interface depending on network bandwidth selection for general users to create multimedia presentation a convenient way. In addition, we implement SMIL document management facility for a large number of users, by connecting SMIL contents database sever.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.6
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• pp.333-351
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• 2008

Transmission control protocols have to overcome common problems in wireless networks. TCP employing both packet loss discrimination mechanism and available bandwidth estimation algorithm, known as the good existing solution, shows significant performance enhancement in wireless networks. For instance, TCP New Jersey which exhibits high throughput in wireless networks intends to improve TCP performance by using available bandwidth estimation and congestion warning. Even though it achieves 17% and 85% improvements in terms of goodput over TCP Westwood and TCP Reno, respectively, we further improve it by exploring maximized available bandwidth estimation, handling bit-error-rate error recovery, and effective adjustment of sending rate for retransmission timeout. Hence, we propose TCP NJ+, showing that for up to 5% packet loss rate, it outperforms other TCP variants by 19% to 104% in terms of goodput when the network is in bi-directional background traffic.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.277-279
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• 2003

본 논문에서는 편재 컴퓨팅(ubiquitous and pervasive computing) 환경에 입력 시스템으로 사용하는 센서 네트워크에서 측정한 데이터의 품질 (sampling rate and quantization depth) 을 보증하며 네트워크 트래픽 또는 소모전력과 같은 비용을 최소화하기 위한 방법으로, 휴리스틱 알고리즘에 의한 비주기적 샘플링과 신뢰성 있는 전송규약을 사용하는 비주기적 전송방식을 제안한다. 그리고 제안한 비주기적 전송방식에 핵심기술인 신뢰성 있는 전송 규약의 비용을 최적화하기 위한 방법으로 ACK방식과 NACK방식을 패킷 에러율과 동일한 라우터를 사용하는 이웃 노드의 수와 같은 네트워크 상황에 따라 상보적으로 사용하는 상보적 방식(alternative method)을 제안하고, 전체 통신규약을 설계하며, 해석을 통해 성능을 분석하고, 네트워크 상태에 따라 두 방식의 성능상의 우열이 전환되는 전환점을 유도한다. 제안하는 상보형 신뢰성 있는 전송규약은 전체 센서 네트워크에서 처리되는 패킷의 비트 수를 최소화해, 각 노드의 총 전력 소모의 20-60%를 차지하는 통신모듈의 소비 전력을 줄일 수 있어 전력소모를 크게 개선 할 수 있다. 나아가서 다양한 센서 네트워크에서 설계한 전송규약을 바탕으로 하는 제안하는 비주기적 전송방식을 활용한다면 최적의 비용으로 측정하는 데이터의 품질을 보증할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.577-580
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• 2001

최근 정보통신 기술 발전 및 초고속 통신망의 발달로 인한 인터넷 망(network)상에서의 방송과 통신이 융합되는 추세가 가속화되고 있다. 이에 스트리밍(Streaming) 기술을 기반으로 한 멀티미디어 데이터의 서비스와 데이터 정보의 푸시(push) 기술을 결합하여 인터넷과 고속망상에서의 원활한 실시간 전송 서비스를 위하여 다중 서버를 지원하는 3-tier 방식의 스트리밍 시스템을 구현하였다. 구현된 시스템은 실시간 전송 프로토콜인 RTP(Real-time Transport Protocol)를 이용하여 송신자에게 멀티미디어 스트리밍 서비스를 제공하며, VOD(Video on Demand) 및 실시간 방송 서비스를 제공하는 분산 멀티미디어 스트리밍 전송 시스템이다. 전체 시스템은 인터넷 방송 서비스 제공을 위한 VOD 서버, 실시간 방송 서버 및 푸시 서버와 멀티미디어의 실시간 재생을 위한 클라이언트 인터페이스 등으로 구성되어 있으며, 안정적인 서비스를 위한 미들웨어에서의 부하분배 및 채널 정보의 관리를 가능하게 하였다.

• Structural Engineering and Mechanics
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• v.71 no.2
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• pp.175-183
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• 2019

This paper deals with damage detection in a girder bridge using transmissibility functions as input data to Artificial Neural Networks (ANNs). The original contribution in this work is that these two novel methods are combined to detect damage in a bridge. The damage was simulated in a real bridge in Vietnam, i.e. Ca-Non Bridge. Finite Element Method (FEM) of this bridge was used to show the reliability of the proposed technique. The vibration responses at some points of the bridge under a moving truck are simulated and used to calculate the transmissibility functions. These functions are then used as input data to train the ANNs, in which the target is the location and the severity of the damage in the bridge. After training successfully, the network can be used to assess the damage. Although simulated responses data are used in this paper, the practical application of the technique to real bridge data is potentially high.

• Journal of Internet Computing and Services
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• v.20 no.1
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• pp.47-55
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• 2019

Free-viewpoint video (FVV) service provides multi viewpoints of contents and synthesizes intermediate video files which are not captured on some view angles so that enables users to watch as they choose wherever they want. Synthesizing video is necessary technique to provide FVV video service, because every video of the FVV contents for different view angles cannot be stored to the content server physically. For the reason, fast view synthesis can improve the quality of video service and increase user's satisfaction. One of the studies for FVV service, a method was proposed to transmit FVV service based on DASH (Dynamic Adaptive Streaming over HTTP). There is big advantage on using DASH that it is commonly used to transport video service. However, the method was only a conceptual proposal, so it is difficult to implement the system using the proposal. In this paper, we propose an implementation method to provide real-time FVV service smoothly. We suggest a system structure and operation method on the server and client side in detail, which is to be applicable to synthesize video quickly. Also, we suggest generating FVV service map additionally which controls a FVV service overall. We manage real-time information of the whole service through the service map. The service can be controlled by reducing the possible delay from network situation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.257-264
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• 2019

Recently, ITU-T recommends that FlexE, which allows the flexible configuration of Ethernet signals, be received by OTN for transparent transmission through OTN. To compensate for the difference in bit rate that can occur when mapping FlexE signals to OTN payload, an idle codeword is removed or inserted. However, the detailed functional blocks required to implement this method are not yet available. In this paper, based on the recent ITU-T requirements, a detailed functional block for OTN mapping of FlexE signals is proposed based on 400G class. In addition, based on the detailed functional blocks, mathematical analysis was performed to obtain the characteristics of removing and inserting idle code words, and the simulation results are shown.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.448-450
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• 2019

Multipath TCP (MPTCP) is a standardized transport layer protocol for maximizing the use of finite network resources by using multiple interfaces simultaneously. If the characteristics of each path are the same, there is an advantage in terms of stability and bandwidth utilization compared to the existing single TCP. However, if the path characteristics are different, the performance is lower than that of a single TCP. There are many complex reasons for this, but one of the biggest impacts is the bufferbloat, which dramatically increases the latency. In this paper, we implemented an algorithm that improved MPTCP performance degradation due to bufferbloat in Linux - based testbed and compared performance with existing MPTCP scheduler.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.279-286
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• 2022

In this paper, we designed a software library that produces integrated Global Navigation Satellite System (GNSS) / Inertial Navigation System (INS) navigation information using the raw measurements provided by the GNSS chipset, gyroscope, accelerometer and magnetometer embedded in android smartphone. Loosely coupled integration method was used to derive information of GNSS /INS integrated navigation. An application built in the designed library was developed and installed on the android smartphone. And we conducted field experiments. GNSS navigation messages were collected in the Radio Technical Commission for Maritime Service (RTCM 3.0) format by the Network Transport of RTCM via Internet Protocol (NTRIP). As a result of experiments, it was confirmed that design requirements were satisfied by deriving navigation such as three-dimensional position and speed, course over ground (COG), speed over ground (SOG), heading and protection level (PL) using the designed library. In addition, the results of this experiment are expected to be applicable to maritime navigation applications using smart device.