• Title/Summary/Keyword: Seperation distance

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Development of the Near/Far Absolute Gain Measurement System Using an Extrapolation Technique (외삽기법을 이용한 안테나의 원 ${\cdot}$ 근역장 절대이득 측정시스템 개발)

  • Shin, Joon;Kang, Chan-Koo;Kim, Jeong-Hwan;Chung, Nak-Sam
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.2
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    • pp.31-38
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    • 1990
  • An antenna gain measurement system using an extrapolation technique is described. The technique is similar to the usual two-antenna method for absolute gain measurement system, but involves the measurement of the received signal as a function of seperation in short distances, and the signal-versus-seperation data is processed in a way that allows an extrapolation of the signal to "infinite" seperation. In this technique it is possible to obtain the near field gain as function of distance by combining the far field gain and a proximity correction factor. The results of gain measurements of standard gain horn antennas and OEG (open ended waveguide) antennas are also presented.

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A Study on the PN Junction Breakdown Characteristics with Design and Process Parameters of FLR in Power Device Design (전력 반도체 소자의 설계에 있어서 FLR의 Design 및 Process Parameter에 따른 PN접합의 항복특성에 관한 고찰)

  • Song, Dae-Sik;Kang, Ey-Goo;Hwang, Sang-Joon;Sung, Man-Young;Lee, Cheol-Jin
    • Proceedings of the KIEE Conference
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    • 1995.07c
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    • pp.1146-1148
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    • 1995
  • To improve the breakdown characteristics of vertical power devices, field limiting ring(FLR) is popularly used. In this paper, at vertical power device having $300{\sim}600V$ breakdown voltage, FLR thecnique is considered, by two dimensional computer simulator, with the various of parameters; number of FLR, seperation distance of first FLR from the main juncton and second FLR from the first FLR, doping concentration and thickness of epi-layer, etc.. Below $40{\mu}m$ epi thickness, and for the case of one FLR, the maximum breakdown voltage, 580V is obtained.

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Characteristics of Interacting Lifted Flames (상호작용하는 부상화염의 특성에 관한 연구)

  • Lee, Seung;Lee, Byeong-Jun
    • 한국연소학회:학술대회논문집
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    • 2000.05a
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    • pp.1-8
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    • 2000
  • The effects of nozzle arrangements, nozzle distances and fuel flowrates on the flame stabilities such as flame length, liftoff height and blowout characteristics are investigated experimentally. Three nozzle arrangements - diamond 4 nozzle, linear 5 nozzle, cross 5 nozzle- are used. Flame interactions result in the increase of the blowout flowrates and constant turbulent liftoff heights. The flames separated about 10 nozzle diameters are sustained as nozzle attached flames to the higher fuel flowrates than the other separation cases. Normally flames are extinguished at the lifted states. Blowout flowrates are affected by the nozzle configuration, nozzle seperation distance. Blowout flowrates for the diamond- or cross- shaped nozzle arrangements are parabolic function of nozzle distances. Maximum blowout flowrates for the 5 nozzle configuration case except linear one is about 2.9 times that of single equivalent nozzle case. Turbulent liftoff heights are not function of flowrates for the interacting flames.

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Characteristics of Interacting Lifted Flames (상호작용하는 부상화염의 특성에 관한 연구)

  • Lee, Seung;Lee, Byeong-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.4
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    • pp.461-466
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    • 2001
  • The characteristics of nonpremixed interacting flames are investigated in the parameter of nozzle configuration and nozzle separation distane, s. Three nozzle arrangements - diamond 4 nozzle, linear 5 nozzle and cross 5 nozzle- are used. When s is about 10 nozzle diameter, flames lift from the nozzle at the highest fuel flowrate compared with the other s cases. Normally flames are extinguished at the lifted states. Flowrates when blowout occurs are affected by the nozzle configuration, nozzle seperation distance. Blowout flowrates for the diamond- or cross-shaped nozzle cases are parabolic function of s. For 5 cross nozzle case, flames extinguished at 3.3 times higher flowrate than that of single equivalent area nozzle. Turbulent liftoff heights are not function of flowrates for these cases.

Dissecting Aneurysm of Aorta: report of a case (해리성 대동맥류 1례 보고)

  • 이종태
    • Journal of Chest Surgery
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    • v.14 no.3
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    • pp.291-296
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    • 1981
  • Dissecting aortic aneurysm is a disease which is characterized by hemorrhagic intramural seperation of aortic wall and extension for varlng distances proximally, distally, or both from the site of the intimal tear. Most aortas show some type of medial degeneration most commonly described as cystic medial necrosis. DeBackey classified this disease according to involved aorta and site of intimal tear to 3 basic types, such as type I, II and III. Type III is defined that dissecting process arrises in the descending thoracic aorta just distal to origin of the left subclavian artery and extends distally for a varing distance. We expirienced a case of dissecting aneurysm, type III of DeBackey's classification which dissecting process is limited to the descending thoracic aorta in the Department of Thoracic and Cardiovascular Surgery, Kyungpook National University Hospital. This patient was 40 year old woman and she had suffered from intermittent sharp back pain for 3 years .before admission. Excision of the aneurysm and Dacron graft were placed successfully under the left atrio-femoral bypass with artificial pump. The hospital course was uneventful.

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Computation of Temperature Rising by Absorbed Power Radiated from a Portable Phone (휴대폰 전파인 인제 흡수전력량과 온도 상승량 산출)

  • 이승학;김채영;강승진
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.3
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    • pp.409-426
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    • 2001
  • Absorbed power of the human head radiated from a 900 MHz portable phone and temperature rise are computed using FDTD(Finite-Difference Time-Domain) method. For this computation the 5 layered media for the human head modeling and the monopole antenna attached to metallic box for the portable phone are used. To reflect the real circumstances typical sizes of human heads and portable phones are considered in the calculation. The length of monopole antenna is 8.15 cm, and the output power of a phone is 600 mW. Under the predetermined model the distribution of 1 g, 10 g averaged SAR and temperature rise rate over the human head are calculated, from which it was found that the position of maximum SAR is near at the head skin surface, not deep places far into the head. The position of the highest temperature is located far from the head skin more than that of the maximum SAR occured. The averaged SAR and temperature along the distance between the head and phone are calculated according to seperation distance between the head and phone.

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Study on the Proper Separation Distance from Intersection to Bus Stop for Reducing Traffic Accidents (교통사고 감소를 위한 교차로에서 버스정류장간 적정 이격거리 산정 연구)

  • Eom, Daelyoung;Chae, HeeChul;Park, Wonil;Yun, llsoo
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.21 no.2
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    • pp.1-16
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    • 2022
  • The location of the bus stop on urban roads should be installed at a point where it is convenient for users and the impact of bus stops on the traffic flow is minimized. However, the location of the bus stops is determined indiscriminately due to the lack of related research. Therefore, this study developed a traffic accident prediction model and calculated the proper separation distance for the bus stops through an optimization technique. The result of the study indicates that the bus stop can be installed in the form of a mid-block approximately 87 to 166 m away from the intersection in the road section. This result is valid if the number of main road lanes in the road section is 2 to 4 with a level of traffic from 1,000 to 3,000 v/h. In the section with 5 to 6 lanes, it is desirable to install a bus stop close to the intersection by about 42 to 97 m.

A Study on Construction of Express Lane Applied by Bus Only Lane as Seperation Facility: Focused on Pangyo-Hannam Section of Gyeongbu Expressway (버스전용차로를 분리시설로 활용한 Express Lane 구축에 관한 연구: 경부고속도로 판교-한남 구간을 중심으로)

  • Kim, Min Kyoung;Kim, Ju Hyun;Shin, Eon Kyo
    • Journal of Korean Society of Transportation
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    • v.31 no.4
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    • pp.32-46
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    • 2013
  • Because of short length between interchanges, traffic congestion has been caused by a lot of short trip traffic in the urban section of interregional expressway. Also, in case of expressway with Bus Only Lane, bus causes dangerous situation by conflicting between vehicles and buses in order to access from Bus Only Lane to IC. Therefore, this study aims to propose Express Lane applied by Bus Only Lane as a new lane operation in order to efficiently operate and to analyze the effectiveness on constructing Express Lane to the Pangyo-Hannam section in Gyeongbu Expressway. The study analyzes effectiveness by scenario using the micro traffic simulation tool, VISSIM 5.4. For this, the indicators which evaluate construction effect of Express Lane, are used by average delay time, average speed and total travel time. The results of the study showed the best effectiveness when Express Lane installed one, and it represented an ideal traffic condition when long distance trip traffic of the whole traffic is 25% in the study section. Therefore, the construction of Express Lane using Bus Only Lane achieves positive effectiveness on safety and expense aspect as well as uncongested flow.