해상 광대역 통신시스템 개발

김지성,윤정인,정경국,김성윤,강희욱,이종률,손원일,김경남,이두용 한국마린엔지니어링학회 2018 한국마린엔지니어링학회지 Vol.42 No.4

This study aims to develop bridge equipment for terrestrial and maritime terminal stations and automatic tracking antenna systems for low-cost base stations. The tests were performed considering the bridging speed, hardware recovery, distance range and communication speed. The bridging speed test was conducted by installing a bridging device and an antenna, and it was confirmed that the existing antenna could be connected to the new antenna within 10 s if the connection was cut off because of signal interruption. The hardware recovery test method was used to install the bridge device, and it was confirmed that the time to reach the login screen by pressing the power button of the breeze device was within 60 s. The test method of the distance range test verified the communication status of the land base station and the repeater, and it was confirmed through the GPS equipped in the repeater that the distance between the land base station and the repeater was over 30 km. The test method of the communication speed test aimed to check the communication status by connecting to the site for the transmission test using the installed repeater. This test confirmed that the communication speed between the terrestrial base station and the repeater was over 1 Mbps at a 30 km distance. The experiment showed that in all tests, the bridging processing speed was 3.16 s; the hardware recovery time was 52.21 s; the communication distance was 32.26 km; and the communication speed for downloading was 6.35 Mbps, whereas that for uploading was 4.05 Mbps. The results of this study are expected to contribute to the development of a remote monitoring system 본 논문의 목적은 육상 및 해상 단말기지국용 브릿지 장비, 저가 보급형 기지국 자동추적 안테나 시스템을 개발하는 것이다. 시험은 브리징 처리속도, 하드웨어 복구, 통달거리 및 통신속도로 총 4가지를 기본적으로 실시하였다. 브리징처리속도 시험의 실험방법은 브리지 장비와 안테나를 설치하고 기존의 안테나가 신호단절로 인하여 연결이 끊어졌을 경우 10 초 이내에 새로운 안테나에 연결이 가능한지 확인하였다. 하드웨어 복구 시험의 실험방법은 브리지 장비를 설치하고 브리장비의 전원을 눌러 로그인 화면이 나올 때까지의 시간이 60 초 이내인지 확인하였다. 통달거리 시험의 실험방법은 육상 기지국과 중계기의 통신상태를 확인하고 중계기가 장착된 GPS를 통해 육상 기지국과 중계기의 거리가 30 km이상인지 확인하였다. 통신속도 시험의 실험방법은 설치된 중계기를 이용하여 전송시험을 위한 사이트에 접속하여 통신상태를 확인한 뒤 30 km거리에서 육상 기지국과 중계기의 통신속도가 1 Mbps이상인지 확인하였다. 실험 측정결과 브리징처리 속도 3.16 초, 하드웨어 복구시간 52.21 초, 통달거리 32.26 km, 통신속도 다운로드 6.35 Mbps, 업로드 4.05 Mbps로 4 가지 실험 모두 요구기준에 충족하여 적합 판정을 받았다. 본 연구에서 실험한 통신시스템의 4가지 성능이 목표치 이상을 충족하며 개발완료된 상태로 본 연구결과는 원격 모니터링 시스템(NMS) 개발에 기여할 수 있을 것으로 기대된다.

Motor Function in the Late Phase After Stroke: Stroke Survivors’ Perspective

Lina Bunketorp-Käll,Marcela Pekna,Milos Pekny,Hans Samuelsson,Christian Blomstrand,Michael Nilsson 대한재활의학회 2020 Annals of Rehabilitation Medicine Vol.44 No.5

Objective To examine the association between observer-assessed functional status and perceived recovery in the late phase after stroke. The study also aimed to determine whether observer-assessed functional improvements as a result of horse-riding therapy (H-RT) are related to enhanced perception of stroke recovery. Methods This is a descriptive correlational study using data derived from a three-armed randomized controlled trial in which 123 individuals were enrolled, among whom 43 received H-RT for 12 weeks. The measures included the Modified Motor Assessment Scale, Berg Balance Scale, Timed Up and Go, timed 10-m walk, and perceived recovery from stroke indicated by item #9 in the Stroke Impact Scale (version 2.0). Spearman rank order correlation (rs) was used in the analyses. Results There were moderate to strong positive or negative correlations between all four observer-assessed motor variables and participants’ ratings of perceived late-phase stroke recovery at trial entrance, ranging from rs=-0.49 to rs=0.54 (p<0.001). The results of the correlational analyses of variable changes showed that, after the end of the H-RT intervention, both self-selected and fast gait speed improvement were significantly correlated with increments in self-rated stroke recovery (rs=-0.41, p=0.01 and rs=-0.38, p=0.02, respectively). Conclusion This study provided data supporting the association between individual ratings of self-perceived recovery after stroke and observer-assessed individual motor function. The results further demonstrate that enhancement in perceived stroke recovery after completing the intervention was associated with objectively measured gains in both self-selected and fast gait speed.

Effect of a pre-bias on the adsorption and desorption of oxidizing gases in FET-type sensor

Wu, Meile,Kim, Chang-Hee,Shin, Jongmin,Hong, Yoonki,Jin, Xiaoshi,Lee, Jong-Ho Elsevier 2017 Sensors and actuators. B Chemical Vol.245 No.-

<P><B>Abstract</B></P> <P>An efficient pre-bias method is proposed in the reading operation of a Field-Effect-Transistor(FET)-type gas sensor which utilizes flatband voltage change of the sensing material formed between the control-gate (CG) and floating-gate (FG) of the FET. The proposed method improves greatly recovery speed and shortens recovery time by more than 10 times at 180°C, which can reduce the power consumed by heater. Since the polarity of the pre-bias affects response, sensing and recovery speeds, it is possible to identify the redox characteristics of the detected gas. To verify experimentally the pre-bias effect, we apply pulses for the pre-biasing and reading to the sensor with a sensing material of 200-nm-thick SnO<SUB>x</SUB> layer to detect NO<SUB>2</SUB> gas as an example. The mechanism is explained theoretically by energy band theory. The pre-biasing method is expected to open a new biasing scheme which improves significantly sensing characteristics, gas identification, and power dissipation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pulse measurement method including pre-bias before reading operation was proposed. </LI> <LI> The polarity of the pre-bias affects response, sensing and recovery speeds. </LI> <LI> Principle responsible for the effect was explained by using energy band diagrams. </LI> <LI> A pulse cycle to enhance both response and recovery properties was provided. </LI> </UL> </P>

The Role of NiO Doping in Reducing the Impact of Humidity on the Performance of SnO₂‐Based Gas Sensors: Synthesis Strategies, and Phenomenological and Spectroscopic Studies

Kim, Hae‐,Ryong,Haensch, Alexander,Kim, Il‐,Doo,Barsan, Nicolae,Weimar, Udo,Lee, Jong‐,Heun WILEY‐VCH Verlag 2011 Advanced Functional Materials Vol.21 No.23

<P><B>Abstract</B></P><P>The humidity dependence of the gas‐sensing characteristics in SnO<SUB>2</SUB>‐based sensors, one of the greatest obstacles in gas‐sensor applications, is reduced to a negligible level by NiO doping. In a dry atmosphere, undoped hierarchical SnO<SUB>2</SUB> nanostructures prepared by the self‐assembly of crystalline nanosheets show a high CO response and a rapid response speed. However, the gas response, response/recovery speeds, and resistance in air are deteriorated or changed significantly in a humid atmosphere. When hierarchical SnO<SUB>2</SUB> nanostructures are doped with 0.64–1.27 wt% NiO, all of the gas‐sensing characteristics remain similar, even after changing the atmosphere from a dry to wet one. According to diffuse‐reflectance Fourier transform IR measurements, it is found that the most of the water‐driven species are predominantly absorbed not by the SnO<SUB>2</SUB> but by the NiO, and thus the electrochemical interaction between the humidity and the SnO<SUB>2</SUB> sensor surface is totally blocked. NiO‐doped hierarchical SnO<SUB>2</SUB> sensors exhibit an exceptionally fast response speed (1.6 s), a fast recovery speed (2.8 s) and a superior gas response (<I>R</I><SUB>a</SUB>/<I>R</I><SUB>g</SUB> = 2.8 at 50 ppm CO (<I>R</I><SUB>a</SUB>: resistance in air, <I>R</I><SUB>g</SUB>: resistance in gas)) even in a 25% r.h. atmosphere. The doping of hierarchical SnO<SUB>2</SUB> nanostructures with NiO is a very‐promising approach to reduce the dependence of the gas‐sensing characteristics on humidity without sacrificing the high gas response, the ultrafast response and the ultrafast recovery.</P>

성별차이에 따른 스피드 스케이트 최대하 운동시 심박수 반응 비교

김기현(Kim Kee Hyun),서민근(Seo Min Geun),정지영(Jung Jiyoung),차광석(Cha Kwang Suk),소위영(So Wi-Young) 한국웰니스학회 2016 한국웰니스학회지 Vol.11 No.3

이 연구는 남녀 엘리트 스피드 스케이트 선수를 대상으로 안정시 심박수, 그리고 최대강도의 70%의 훈련 중 심박수와 회복기 심박수를 비교하는데 목적이 있다. 이 연구에서 남자 7명, 그리고 여자 6명의 엘리트 스피드 스케이트 선수가 참여하였으며, 안정시 심박수는 1회를 측정하였으며, 훈련 중 총 10 구간, 그리고 회복기 총 6 구간의 심박수를 10초 단위로 측정하여 다음과 같은 결과를 획득하였다. 안정시 심박수는 성별에 따라 유의한 차이가 없었다. 또한 각 시기별 훈련 중 심박수와 심박수증가율도 유의한 차이가 없었으며, 회복시 심박수와 심박수 감소율도 유의한 차이가 없었다. 이와 같은 결과는 남녀 엘리트 스피드 스케이트선수에서의 안정시, 운동시 그리고 회복시 심박수 반응이 유사하다는 것을 의미한다. The aim of the present study was to compared heart rate at resting, during exercise and recovery in male and female elite speed skaters. Seven male and six female athletes were participated in this study. Resting heart rate was measured by 1 time. Heart rate during exercise and heart rate recovery was divided into 10 seconds and was measured 10 times and 6 times, respectively. Results of this study were as follows. In resting heart rate was no significant difference in male and female speed skaters. Both the heart rate and the increasing rate during exercise at each periods were also no significant differences in male and female speed skaters. There was no significant differences in both heart rate recovery and recovery rate from exercise between male and female speed skaters. These results indicate that heart rate responses were similar between male and females elite speed skaters at rest, during exercise and recovery from exercise.

골프장 그린의 볼마크 수리방법에 따른 벤트그래스의 회복속도 비교

박종하,주영규,이재필,김두환 한국잔디학회 2010 Weed & Turfgrass Science Vol.24 No.2

This study was conducted to investigate a proper method of ball mark repair by comparing the creeping bentgrass recovery speed on golf course green treated by various methods of ball mark repair. Nine general repairing methods were tested and compared; control (no repair, A type), two common methods of USGA (B type) and GCSAA (C type), three methods with fork shaped hand set performing at Korean golf courses (Ansung Benest, D; Sky72, E; Lakeside,F type), and three methods using the repair machine with 6, 8, or 14 teeth (G, H, I type, respectively). Three creeping bentgrass cultivar of ‘Penncross’, ‘T-1’, and ‘CY-2’ were tested in this field experiment. This test was carried out from September to November in 2009 at the nursery on the Seoul Lakeside Golf Course. The average speed of turfgrass recovery after various ball mark repairing methods have been ranked as in the order of E, D, C, B, F, I, H, G, and A. The methods of hand practise showed more effective results than repair method using machines. The ball mark recovery speeds of ‘Penncross’ were in the order of E, D ,B, C, F, I, H, and A. In the case of ‘T1’ and ‘CY-2’, similar orders were showed as D, E, B, F, C, H, I, A, G and the order of D, E, C, F, B, H, G, I, A, respectively. The ball mark recovery speed among creeping bentgrass cultivar resulted in the order of ‘CY-2’, ‘Penncross’, and ‘T-1’. The most proper method of ball mark repair was repair method using a hand set tool especially the method of the Sky72 Golf course (E type). At the first, remove a damaged grass area with fork and tap. And then gather the side grasses into the center area with pulling the grasses with fork. After that, make harden and flat on the turf surface by pounding and rolling with the round wooden stick. The final step, water the repaired grass surface. This ball mark repairing practise showed a most rapid and proper recovery method on creeping bentgrass green.

Seasonal effectiveness of a Korean traditional deciduous windbreak in reducing wind speed

Koh, Insu,Park, Chan-Ryul,Kang, Wanmo,Lee, Dowon The Ecological Society of Korea 2014 Journal of Ecology and Environment Vol.37 No.2

Little is known about how the increased porosity of a deciduous windbreak, which results from loss of leaves, influences wind speed reduction. We hypothesized that, with loss of foliage, the wind speed reduction effectiveness of a deciduous windbreak decreases on near leeward side but not on further leeward side and that wind speed recovers faster in the full foliage season than in other seasons. During summer, autumn, and winter (full, medium, and non-foliage season, respectively), we observed wind speed and direction around a deciduous windbreak in a traditional Korean village on windward and near and further leeward sides (at -8H, 2H, and 6H; H = 20 m, a windbreak height). We used a linear mixed effects model to determine that the relative wind speed reduction at 2H significantly decreased from 83% to 48% ($F_{2,111.97}=73.6$, P < 0.0001) with the loss of foliage. However, the relative wind speed reduction at 6H significantly increased from 26% to 43% ($F_{2,98.54}=18.5$, P < 0.0001). Consequently, wind speed recovery rate between 2H and 6H in summer was two times higher than in autumn and ten times higher than in winter ($F_{2,102.93}=223.1$, P < 0.0001). These results indicate that deciduous windbreaks with full foliage seem to induce large turbulence and increase wind speed recovery rate on leeward side. Our study suggests that further research is needed to find the optimal foliage density of a deciduous windbreak for maximizing windbreak effectiveness regardless of seasonal foliage changes.

Seasonal effectiveness of a Korean traditional deciduous windbreak in reducing wind speed

Insu Koh,이도원,박찬열,강완모 한국생태학회 2014 Journal of Ecology and Environment Vol.37 No.2

Little is known about how the increased porosity of a deciduous windbreak, which results from loss of leaves, influences wind speed reduction. We hypothesized that, with loss of foliage, the wind speed reduction effectiveness of a deciduous windbreak decreases on near leeward side but not on further leeward side and that wind speed recovers faster in the full foliage season than in other seasons. During summer, autumn, and winter (full, medium, and non- foliage season, respectively), we observed wind speed and direction around a deciduous windbreak in a traditional Korean village on windward and near and further leeward sides (at –8H, 2H, and 6H; H = 20 m, a windbreak height). We used a linear mixed effects model to determine that the relative wind speed reduction at 2H significantly decreased from 83% to 48% (F2,111.97 = 73.6, P < 0.0001) with the loss of foliage. However, the relative wind speed reduction at 6H significantly increased from 26% to 43% (F2,98.54 = 18.5, P < 0.0001). Consequently, wind speed recovery rate between 2H and 6H in summer was two times higher than in autumn and ten times higher than in winter (F2,102.93 = 223.1, P < 0.0001). These results indicate that deciduous windbreaks with full foliage seem to induce large turbulence and increase wind speed recovery rate on leeward side. Our study suggests that further research is needed to find the optimal foliage density of a deciduous windbreak for maximizing windbreak effectiveness regardless of seasonal foliage changes.

고속 무선 전송을 위한 QPSK 복조기 FPGA 설계

정지원 한국전자파학회 2003 한국전자파학회논문지 Vol.14 No.12

본 논문에서는 QPSK 방식을 채용하는 고속 무선 전송 시스템에 적용될 수 있는 Zero-Crossing IF-level QPSK 복조기에 대해서, 복조기에 소요되는 알고리즘들을 고찰하고 이를 구현하기 위한 H/W구조에 대해서 언급한다. Zero-Crossing IF-level QPSK 복조기를 구현하기 위해서, 비트 동기를 포착하는 심볼 동기부와 반송파 동기를 포착하는 반송파 동기부가 구현되어야 하는데, 심볼 동기부로는 Gardner 알고리즘을, 반송파 동기부로는 빠른 반송파 포착을 위한 Decision-Directed 동기화 알고리즘을 적용하여 설계, 구현하였다. 설계한 QPSK복조기를 Altera 사의 Design Compiler를 이용하여 CPLD-FLEX10K 칩에 합성해 본 결과 약 2.6 Mbps의 전송속도까지 복조 가능하였다. 설계된 Zero-Crossing IF-level QPSK 복조기를 ASIC으로 구현할 경우 CPLD속도의 5∼6 이상 고속화가 가능하므로 약 10 Mbps급 Zero-Crossing IF-level QPSK 복조가 가능하다. High-speed QPSK demodulator has been one important design objective of any wireless communication systems, especially those offering broadband multimedia service. This paper describes Zero-Crossing IF-level(ZCIF) QPSK demodulator for high-speed wireless communications, and its hardware structures are discussed. ZCIF QPSK demodulator is mainly composed of symbol time circuit and carrier recovery circuit to estimate timing and phase-offsets. There are various schemes. Among them, we use Gardner algorithm and Decision-Directed carrier recovery algorithm which is most efficient scheme to warrant the fast acquisition and tracking to fabricate FPGA chip. The testing results of the implemented onto CPLD-FLEX10K chip show demodulation speed is reached up to 2.6[Mbps]. Actually in case of designing by ASIC, its speed may be faster than CPLD by 5 times. Therefore, it is possible to fabricate the ZCIF QPSK demodulator with speed of 10 Mbps.

Flexible and stable heat energy recovery from municipal wastewater treatment plants using a fixed-inverter hybrid heat pump system

Chae, Kyu-Jung,Ren, Xianghao ELSEVIER 2016 APPLIED ENERGY -BARKING THEN OXFORD- Vol.179 No.-

<P>Among many options to improve energy self-sufficiency in sewage treatment plants, heat extraction using a heat pump holds great promise, since wastewater contains considerable amounts of thermal energy. The actual heat energy demand at municipal wastewater treatment plants (WWTPs) varies widely with time; however, the heat pumps typically installed in WWTPs are of the on/off controlled fixed-speed type, thus mostly run intermittently at severe part-load conditions with poor efficiency. To solve this mismatch, a specially designed, fixed-inverter hybrid heat pump system incorporating a fixed-speed compressor and an inverter-driven, variable-speed compressor was developed and tested in a real WWTP. In this hybrid configuration, to improve load response and energy efficiency, the base-heat load was covered by the fixed-speed compressor consuming relatively less energy than the variable-speed type at nominal power, and the remaining varying load was handled by the inverter compressor which exhibits a high load-match function while consuming relatively greater energy. The heat pump system developed reliably extracted heat from the treated effluent as a heat source for heating and cooling purposes throughout the year, and actively responded to the load changes with a high measured coefficient of performance (COP) of 4.06 for heating and 3.64 for cooling. Moreover, this hybrid operation yielded a performance up to 15.04% better on part loads than the single inverter operation, suggesting its effectiveness for improving annual energy saving when applied to highly load-fluctuating real WWTPs. To improve the overall efficiency of the heat recovery system, although the heat pump is the largest energy-consuming component, taking up 56.0-68.5% of the total energy, new efforts to develop a novel design are also needed to make the heat exchanger more energy-efficient. (C) 2016 Elsevier Ltd. All rights reserved.</P>