• Title/Summary/Keyword: high speed data transfer

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Development of a Boat Operator Computer Scoring System Based on LiDAR and WAVE (LiDAR 및 WAVE 기반 동력수상레저기구 조종면허 실기시험 전자시스템 개발)

  • Moon, Jung-Hwan;Yun, Jea-Jun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.4
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    • pp.504-510
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    • 2019
  • Practical test items were analyzed to extend the existing scoring method for boat operator licenses to an electronic scoring method. We have attempted to digitize the method within the current practical test system scope and have developed an electronic scoring system using LiDAR sensors and WAVE communication. The results of the study are as follows; the first, the scoring data entered into the LiDAR and examiner score device on the boat were transferred from an integrated processing unit to a land control center through WAVE communication. The system was constructed and verified to store and manage examinee data. Second, when testing the meandering task, accurate distance measurement was achieved by using LiDAR instead of visually observing the stick (3 m), and an accurate distance was displayed through the examiner score device quickly. Finally, we confirmed that it is possible to smoothly transmit and process the WAVE communication used to transfer the score data acquired from the boat to the monitoring center at a high speed without loss.

A Study on the Application of Zero Copy Technology to Improve the Transmission Efficiency and Recording Performance of Massive Data (대용량 데이터의 전송 효율 및 기록 성능 향상을 위한 Zero Copy 기술 적용에 관한 연구)

  • Song, Min-Gyu;Kim, Hyo-Ryoung;Kang, Yong-Woo;Je, Do-Heung;Wi, Seog-Oh;Lee, Sung-Mo;Kim, Seung-Rae
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.6
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    • pp.1133-1144
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    • 2021
  • Zero-copy is a technology that is also called no-memory copy, and through its use, context switching between the user space and the kernel space can be reduced to minimize the load on the CPU. However, this technology is only used to transmit small random files, and has not yet been widely used for large file transfers. This paper intends to discuss the practical application of zero-copy in processing large files via a network. To this end, we first developed a small test bed and program that can transmit and store data based on zero-copy. Afterwards, we intend to verify the usefulness of the applied technology in detail through detailed performance evaluation

Condensation Heat Transfer Characteristics of R-410A as an Alternative R-22 in the Condenser with Small Diameter Tubes (세관을 사용한 응축기에서 R-22의 대체냉매인 R-410A의 응축 열전달 특성)

  • Son, Chang-Hyo
    • Clean Technology
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    • v.13 no.2
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    • pp.151-158
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    • 2007
  • An experimental study to investigate the condensing heat transfer characteristics of small diameter horizontal double pipe heat exchangers with R-22 and R-410A was performed. Experimental facility was constructed to calculate and observe HTC(heat transfer coefficients), flow patterns and pressure drop. The main components include a liquid pump, an evaporator, a condenser(test section), a sight-glass, pressure taps and measurement apparatus. Two pipes of different diameters are tested; One 5.35 mm ID 0.5 mm thick, the other 3.36 mm ID 0.7 mm thick. The mass flow rate ranged from 200 to $500\;ks/m^2{\cdot}s$ and heating capacity were form 1.0 to 2.4 kW. The flow patterns of R-22 and R-410A were observed with a high speed camera through the sight-glass. The tests revealed that HTC of R-410A was higher than that of R-22 by maximum 5%. Annular pattern was observed for the most cases but stratified flow was also detected when x<0.2. The pressure drop in 3.36 mm ID pipe was higher than that of 5.35 mm by $30{\sim}50%$. Comparing with previous correlations such as Shah, Fujii and Soliman's, Fujii' showed the best good agreement with my data with a maximum deviation of 40%.

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A Design & Implementation of Remote Access Function for A Multimedia Database of The Tele-medical System Based on ATM/B-ISDN (ATM/B-ISDN 기반의 원격 의료정보 시스템을 위한 멀티미디어 데이터베이스 원격 접속기능 설계 및 구현)

  • 김호철;김영탁
    • Journal of Korea Multimedia Society
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    • v.1 no.1
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    • pp.98-108
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    • 1998
  • In the multimedia tele-medical system the medical informations are stored and managed in multimedia database. Also, multimedia DBMS is essential in order to manage large scale medical informations, and the remote access function is necessary for the distributed processing at all around the hospital. For the multimedia tele-medical information that is composed of image/picture, data, video, and audio, a high-speed telecommunication network is necessary that can provide separated connections for each medical information type with different QoS. The commercial DBMSs are based on the TCP/IP socket API(Application Programming Interface) that does not provide multiple QoS. Also, each commercial DBMS has its own API that is incompatible with other DBMS. In this paper, we propose a multimedia DBMS agent for the remote access of the multimedia database in the tele-medical system. The proposed multimedia DBMS agent is based on the ATM API that can provide high-speed data transfer capability and multiple QoS connections. Also, the proposed multimedia DBMS agent is independent of the commercial DBMS. We explain the functional architecture of the multimedia DBMS agent, implementation technology on the ATM network environment, and the result of performance analysis.

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Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

Hybrid TCP PEP Scheme, Mixture of Error Recovery Method and the TCP Hybla in Satellite Communications (위성통신에서 에러 복구 방법과 TCP Hybla를 결합한 Hybrid TCP PEP 기법)

  • Lee, Seunglyong;Kim, Jong-Mu;Oh, Ji-Hoon;Kim, Jae-Hyun
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.11
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    • pp.15-22
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    • 2016
  • In satellite communication, transmission performance is degraded due to long propagation delay and relatively high data loss compared to terrestrial network. In this paper, We propose Hybrid TCP PEP scheme with XOR coding and Hybla TCP, which reduces the transmission performance degradation due to the transmission delay time. Experimental results show that the proposed method improves the file transfer rate by more than 10% in the environment with high channel error rate. Therefore, Hybrid TCP, which is a mixture of XOR coding method and TCP Hybla, is considered to contribute to the improvement of transmission speed in satellite communication when applied to connection split PEP.

Resource Management Scheme for Improvement of Reliability and Connectivity in wireless USB System (무선 USB 시스템에서 신뢰성과 연결성 향상을 위한 자원 관리 기법)

  • Kim, Jin-Woo;Jeong, Min-A;Lee, Seong Ro
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39C no.11
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    • pp.1159-1166
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    • 2014
  • In this paper, a resource management scheme for enhancing the network connectivity and reliability in wireless USB system is proposed. Wireless USB protocol is suitable for the application that supports the real-time multimedia service in Ship Area Network since it supports high speed data transfer. However, the device's mobility is caused the dramatic change of link state and network topology, and is occurred the degradation of network performance. Therefore, a resource management scheme for wireless USB system is proposed in this paper. The proposed technique can intelligently treat the change of link state, and solve the degradation of network performance. The simulation results show that proposed protocol can enhance the throughput and delay performance by selecting relay device with better link state.

Performance Analysis of WAP Packet Considering WTP SAR Algorithm and RLP in Wireless CDMA Network (무선 CDMA 망에서 WTP SAR 알고리즘과 RLP를 고려한 WAP 패킷의 성능 분석)

  • Moon, Il-Young;Roh, Jae-Sung;Cho, Sung-Joon
    • Journal of Advanced Navigation Technology
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    • v.6 no.1
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    • pp.69-76
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    • 2002
  • With the growth of data communication service by mobile devices, WAP is proposed to efficiently access the Internet contents by user request through wireless condition that has a high error rate and mobility. But, because a transmission speed of WAP is limited, it takes many times to transmit and to receive the data. This paper has studied the WAP packet transmission time using WTP-SAR algorithm. As a method that is to improve transfer capability of WAP, using SAR function in WTP, total message down from upper layer has been fragmented and packet is transmitted through RLP frame time slot. Then, we have analyzed the transmission time of WAP packet with variable RLP layer size on the wireless CDMA network for next generation systems. From the results, we could obtain the WAP packet transmission time and optimal WTP packet size.

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(Theoretical Performance analysis of 12Mbps, r=1/2, k=7 Viterbi deocder and its implementation using FPGA for the real time performance evaluation) (12Mbps, r=1/2, k=7 비터비 디코더의 이론적 성능분석 및 실시간 성능검증을 위한 FPGA구현)

  • Jeon, Gwang-Ho;Choe, Chang-Ho;Jeong, Hae-Won;Im, Myeong-Seop
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.39 no.1
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    • pp.66-75
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    • 2002
  • For the theoretical performance analysis of Viterbi Decoder for wireless LAN with data rate 12Mbps, code rate 1/2 and constraint length 7 defined in IEEE 802.11a, the transfer function is derived using Cramer's rule and the first-event error probability and bit error probability is derived under the AWGN. In the design process, input symbol is quantized into 16 steps for 4 bit soft decision and register exchange method instead of memory method is proposed for trace back, which enables the majority at the final decision stage. In the implementation, the Viterbi decoder based on parallel architecture with pipelined scheme for processing 12Mbps high speed data rate and AWGN generator are implemented using FPGA chips. And then its performance is verified in real time.

Implementation of a TCP/IP Offload Engine Using Lightweight TCP/IP on an Embedded System (임베디드 시스템상에서 Lightweight TCP/IP를 이용한 TCP/IP Offload Engine의 구현)

  • Yoon In-Su;Chung Sang-Hwa;Choi Bong-Sik;Jun Yong-Tae
    • Journal of KIISE:Computer Systems and Theory
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    • v.33 no.7
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    • pp.413-420
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    • 2006
  • The speed of present-day network technology exceeds a gigabit and is developing rapidly. When using TCP/IP in these high-speed networks, a high load is incurred in processing TCP/IP protocol in a host CPU. To solve this problem, research has been carried out into TCP/IP Offload Engine (TOE). The TOE processes TCP/IP on a network adapter instead of using a host CPU; this reduces the processing burden on the host CPU. In this paper, we developed two software-based TOEs. One is the TOE implementation using an embedded Linux. The other is the TOE implementation using Lightweight TCP/IP (lwIP). The TOE using an embedded Linux did not have the bandwidth more than 62Mbps. To overcome the poor performance of the TOE using an embedded Linux, we ported the lwIP to the embedded system and enhanced the lwIP for the high performance. We eliminated the memory copy overhead of the lwIP. We added a delayed ACK and a TCP Segmentation Offload (TSO) features to the lwIP and modified the default parameters of the lwIP for large data transfer. With the aid of these modifications, the TOE using the modified lwIP shows a bandwidth of 194 Mbps.