• Title/Summary/Keyword: 회전율

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A Prediction Study on the Roll Lock-in Phenomena of Freely Spinning Tailfins (자유회전 테일핀의 Roll Lock-in 현상 예측 연구)

  • Yang, Young-Rok;Cho, Tae-Hwan;Myong, Rho-Shin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.9
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    • pp.849-855
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    • 2010
  • This paper investigated the roll lock-in phenomena of a canard-controlled missile with freely spinning tailfins by applying Falanga's roll-rate equation. To confirm and validate the accuracy of the results of the roll-rate and roll lock-in prediction for freely spinning tailfins, the results were compared with Blair's wind tunnel test data. For calculation of the roll-rate of freely spinning tailfins, rolling moment coefficients of the tailfins were obtained from the wind tunnel test data and roll-damping coefficients were calculated by missile DATCOM. The roll-rate and roll lock-in of the freely spinning tailfins were calculated by applying these values to the roll-rate equation for freely spinning tailfins. The calculation results showed good agreement with the wind tunnel test data, and the roll lock-in could be anticipated as well.

Investigating the Relationships Among Inventory Turnover Performance, IT, and Firm and Industry Characteristics (정보기술, 기업 및 산업특성, 재고회전율 간의 관계에 대한 실증분석)

  • Kim, Gilwhan
    • Journal of Korea Society of Industrial Information Systems
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    • v.24 no.3
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    • pp.1-21
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    • 2019
  • The objective of this study is three-fold: to investigate the relationship between information technology (IT) investment and inventory turnover, using 98 U.S. firms spanning eleven years (from 1999 to 2009); to analyze the correlation of inventory turnover with firm and industry characteristics, where vertical integration and growth options are chosen to reflect the features of the firm's internal characteristics, and industry dynamism and industry concentration are selected to represent the industry's competitive environment; and to examine time trends in inventory turnover. The significant findings include the following: (i) both IT investment and growth options have a positive impact on inventory turnover; (ii), but vertical integration and industry concentration have a negative impact on inventory turnover; (iii) the impact of industry dynamism on inventory turnover positive; and (iv) the time trends in inventory turnover and 'adjusted inventory turnover' have been increased during the sample period from 1999 to 2009.

Extraction of Parking Turnover Ratio (주차 회전율의 추출)

  • Shin, Seong-Yoon;Lee, Hyun-Chang;Ahn, Woo-Young
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2016.01a
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    • pp.109-110
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    • 2016
  • 본 논문에서는 효율적으로 주차 공간을 확보와 주차장 성능을 향상을 위한 방법을 조사하였다. 이러한 방법으로는 차량 번호판 조사를 이용하여 주차 회전율을 구하는 방법이 있었다. 본 연구로 효율적으로 주차장을 사용하고 있는지를 판단할 수 있다. 또한 차량의 주차를 하여 잘 소통되는지를 알 수 있었다.

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Average Parking Duration and Parking Turnover (주차 지속 시간과 주차 회전율 파악)

  • Shin, Seong-Yoon;Lee, Hyun-Chang
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2017.01a
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    • pp.205-206
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    • 2017
  • 본 논문에서는 주차 시설 이용 현황 중에서 차량 번호판 조사를 통하여 평균주차시간과 주차 회전율을 구하도록 한다. 관찰하는 사람이 없이 카메라를 활용하고, 조사 시간에 일정한 간격을 주어 조사하도록 한다. 일정한 조사 시간 간격을 주차된 차량에 나눠주어 평균 주차 지속 시간을 구하도록 한다. 그리고 이렇게 하여 주차면 1개당 1시간당 주차 차량 대수인 주차 회전율을 구하도록 한다.

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A Study on Characteristics of Heat Transfer for a Rotating Heat Pipe with a Trigonal Cross Section (삼각 단면을 갖는 회전 열파이프의 열전달 특성에 관한 연구)

  • 이진성;김철주;김윤제;최영준;홍성은
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1997.10a
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    • pp.114-121
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    • 1997
  • 회전 열파이프의 열전달 성능은 액막 두께 및 증발부로 귀환되는 응축 액막 유동율에 의해 결정된다. 그 동안 응축액 유동율을 촉진시키기 위하여 용기 내벽에 groove, 테이퍼 및 나선형 코일을 삽입하여 유동율을 높이는 방법들이 연구되었다. 본 연구도 회전 열파이프의 내부 관벽 구조에 관한 것으로써 삼각 단면을 갖는 회전 열파이프의 열전달 특성을 파악하고자 하였다. 삼각 단면을 갖는 회전 열파이프는 고속 회전 영역에서 모서리 부분으로 액막이 집중되어 관 내벽에 형성되는 액막 두께를 줄일 수 있으나 증발부에서 국부적인 과열이 발생되어 불안정한 작동 상태를 나타내었다. 따라서 본 연구에서는 개선방안으로 증발부에 부분적으로 원형관을 접합하였으며, 그 결과 dry-out의 억제와 함께 삼각 유동 단면에 의한 액막 두께 감소 효과를 볼 수 있었다. 회전체 발열부 냉각에 적용시키기 위해서는 앞으로 최적의 기하학적 형상에 따른 충전율 및 액막에서의 열전달에 대한 정량적인 해석 연구가 필요할 것으로 생각된다.

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Efficient Parking Management through The Investigation of Car License Plate Using Camera (카메라를 이용한 차량 번호판 조사를 통한 효율적 주차 관리)

  • Lee, Kang-Ho;Shin, Seong-Yoon;Choi, Byeong-Seok
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.11
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    • pp.145-151
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    • 2013
  • This research is to suggest a method for investigating car number plates among the information managed in parking facilities. The investigation of car number plate is generally used to know how long vehicles are parked. Also, it can provide the information about the parking turnover rate and the mean parking duration of parked vehicles. This research performs the investigation using cameras at a distance of time. That is, the given distance of time from cameras is assigned to each parked vehicle, and then it can find the mean parking time of parked vehicles. Also, it can check the parking turnover rate of parked vehicles at a space unit of parking lot in an hour. The information such as the mean parked duration and the parking turnover rate of parked vehicles taken from this method is helpful to find and understand the inefficient use of parking facilities. With this suggested method, this research attempted to check the mean parking duration and the parking turnover rate of parked vehicles.

Status of ICT Application in Agricultural Market of China (주차 회전율 파악)

  • Shin, Seong-Yoon;Lee, Hyun-chang;Rhee, Yang-Won
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.10a
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    • pp.1041-1042
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    • 2015
  • This paper studies on securing parking spaces and improving parking performance, by use of vehicle license plate investigation for parking turnover ratio. It is easy to test whether a parking lot is effectively used and its traffic flows smoothly or not.

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Neural Network Pitch Controller of Wind Turbine using Changing Rate of Generator Speed (발전기 속도 변화율을 이용한 신경망피치제어기)

  • Hong, Min-Ho;Kim, Ho-Chan;Huh, Jong-Chul;Kang, Min-Jae
    • Journal of the Korean Institute of Intelligent Systems
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    • v.24 no.4
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    • pp.366-371
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    • 2014
  • The neural network pitch controller using changing rate of generator speed has been suggested in this paper to regulate wind turbine power above the rated wind speed. The changing rate of generator speed is used in the suggested pitch controller as well as the difference between the rated and current generator speed. Matlab/simulink has been used for simulations and it has been shown that the suggested pitch controller regulates generator speed as the rated speed of 122.9[rad/s].

Characteristics of canola biodiesel fuel blended with diesel on the combustion and exhaust gas emissions in a compression ignition diesel engine (압축착화 디젤기관의 연소 및 배기가스에 대한 카롤라 바이오디젤 혼합 연료의 특성)

  • Yoon, Sam Ki;Kim, Min Soo;Choi, Nag Jung
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.9
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    • pp.1081-1086
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    • 2014
  • An experimental study was performed in order to compare with the case of using pure diesel the characteristics of combustion pressure and exhaust emissions when the engine speed was changed in a CRDI 4-cylinder diesel engine using biodiesel( Canola oil) blended and pure diesel fuel. As a results, the combustion pressure was decreased with increasing biodiesel blended rate when engine speed was 1,000, 1,500, 2000(rpm). but the combustion pressure of the engine speed 2,500rpm was increased with increasing biodiesel blended rate. The emission results show, that CO was decreased with increasing biodiesel blended rate and engine speed. The emission of $CO_2$, NOx, were increased with increasing biodiesel blended rate and engine speed.

EFFECTS ON THE ENLARGEMENT RATIOS DUE TO CHANGES OF HEAD POSTURE ON LATERAL HEADFILMS (측두 규격방사선사진 촬영시 두부의 위치변화가 확대율에 미치는 영향)

  • Seo, Young-Hun;Choi, Yeong-Chul
    • Journal of the korean academy of Pediatric Dentistry
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    • v.28 no.1
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    • pp.185-194
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    • 2001
  • This study was designed to evaluate the effects of angulation changes of head posture on the enlargement ratios of a lateral headfilm depending on the vortical or horizontal rotation of the objects. A device was constructed to measure regional changes of enlargement ratios. The device was held within the cephalostat and cephalograms recorded at each measured degrees of the device tilting, vertically and horizontally. The enlargement ratios of the horizontal, vertical, and angular measurements on the films taken at each tilted angulations were obtained and compared with those on the films taken without rotation. In summary, the enlargement ratios of the horizontal linear measurements were decreased during horizontal rotations. The enlargement ratios of vortical measurements of the right side on the film were increased and those of the left side were decreased by the horizontal rotations. Enlargement ratios of horizontal measurements were affected further than those of vertical measurements by the same angular changes of the horizontal rotations. Therefore, a disruption of parallelism between the object's midsagittal plane and the film could result in distortion of the image while vertical rotation around the object's porionic axis would not significantly affect the enlargement ratios on the headfilm.

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