• Title/Summary/Keyword: Line array

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Effects of Fin Pitch and Array on the Frost Layer Growth on the Extended Surface of a Heat Exchanger (열교환기 표면에서의 서리층 성장에 대한 휜 피치와 배열의 영향)

  • 양동근;이관수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.9
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    • pp.711-717
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    • 2003
  • This paper presents the effects of the fin array and pitch on the frost layer growth of a heat exchanger. The numerical results are compared with experimental data of a cold plate to validate the present model, and agree well with experimental data within a maximum error of 8%. The frost behaviors of the staggered fin array are somewhat different from those of in-line array. The frost layer formed on the first fin of the in-line array grows rapidly, compared to second fin, whereas the difference of the frost layer growth between the fins of the staggered array is small. For fin pitch below 10 m, the frost layer growth of second fin in the staggered array is affected by that of first fin. The thickness of the frost layer and heat transfer of single fin are reduced with decreasing fin pitch regardless of fin array. However, the thermal performance of a heat exchanger is enhanced due to the increase of heat transfer surface area.

An Application of CMOS Gate Array Integrated Circuits to Switching Network and Digital Line Concentrator (스위칭 네트워크와 디지털 접선 장치에서의 CMOS 게이트 어레이 IC 적용)

  • 박항구;박권철;조용현
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.24 no.4
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    • pp.652-657
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    • 1987
  • This paper describes an application of CMOS Gate Array Integrated Cricuits to the implementation of three functional units: A Multiplexer, Time Switch, and Demultiplexer in the Switching Network and Digital Line Concentrator of TDX-1 system, which is a fully digital time division electronic switching system in Korea. The application of CMOS Gate Array Integrated Circuits significantly improves the overall system performance in terms of power consumption, cost, size, reliability, and timing margin, etc.

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Crosstalk analysis of laser-diode array modules for wavelength division multiplexing (파장 분할 다중화 방식을 위한 고속 레이저 다이오드 배열 모듈의 혼신해석)

  • 김성일;이해영
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.7
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    • pp.71-78
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    • 1997
  • In this paper, we analyzed the crosstalk characteristics of LD array modules for WDM and improved the crosstalk levels using a screening line between access lines. From the calculation resutls, we have found that inductive crosstalk of access lines is dominant for the low impedance LD arrays with short bondwire interconnections. The proposed array interconnecton with the screening line and ouble bondwires, rduces the crosstalk level about 10dB compared to conventional interconnections using simple access lines and a single bondwire. This proposed structure also can be easily imlemented with transmission reliability.

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Experimental Studies on the Performance of the Active Phased-Array. Antenna Coupled by Transmission Line (전송선로로 결합된 능동 위상차배열 안테나의 동작특성에 관한 실험적 연구)

  • 최영규
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.53 no.3
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    • pp.175-181
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    • 2004
  • In order to increase the coupling efficiency of the Power and Phase of the active Phase way antenna, we have fabricated the active phased-array antenna which is coupled by the transmission line, and investigated the relationship between the length of the coupling transmission line and coupling power and phase. The following three types of driving method -(1) giving the frequency difference between the two active antenna, (2) applying the input signal to the one side of the two antennas, and changing the eigen frequency of the other side antenna, (3) appling the different phase inputs to the active antennas was investigated. The experimental results showed that the interval of the antenna elements has not affected the power and the phase of the antenna.

Design of Asymmetric Parallel Coupled-line Array using Finite Element Analysis (유한요소해석을 이용한 배열구조의 평면형 비대칭 결합선로 설계)

  • 윤재호;박준석;김형석
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.6
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    • pp.521-527
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    • 2002
  • In this paper, we introduce a procedure to find design parameter for array coupled lines using 2-D finite element analysis. To extract design parameters using FE calculation, we set up several design conditions. In order to show the validity of our approach, we designed, simulated and fabricated a comb-line bandpass filter.

X, K-Band Patch Array Antenna Having One Port Feeding for Radar Detector (단일 급전부를 갖는 레이다 디텍터용 X, K 밴드 배열 안테나)

  • Joo, Hyun-Mo;Park, Byung-Chul;Kay, Young-Chul;Lee, Jeong-Hae
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.5
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    • pp.559-569
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    • 2012
  • In this paper, the X($1{\times}2$, 10.525 GHz) and K($3{\times}6$, 24.15 GHz) bands patch array antenna having single feed line for radar detector applications is proposed. The left side of the proposed array antenna is X band array antenna and the right is K band array antenna. Two array antennas with two stubs located in the front of antennas are fed through one transmission line. If the array antennas which have the different resonance frequency are fed by one transmission line using general T-junction, it interferes each other and the array antenna lost its character. Therefore, to prevent these interferences, two stubs using open and short property of stub are designed. First of all, the performances of array antenna weren't changed when each array antennas were connected with the stub and in the end, it is found out that it was the same when the two array antennas were combined and feed through the one transmission line. The measured gain at X band is 6.47 dBi and measured gain at K band is 13.07 dBi. The experimental results agree well with the simulated ones.

Optimizing the design factors of the head-fed type combine(I) -Estimation of the threshing drum torque curve- (자탈형 콤바인 탈곡부 설계요인(設計要因)의 적정화(適正化)를 위한 연구(I) -급동축(扱胴軸) 토오크 파형의 추정(推定)-)

  • Nam, S.I.;Chung, C.J.;Hosokawa, A.
    • Journal of Biosystems Engineering
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    • v.12 no.3
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    • pp.42-49
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    • 1987
  • The threshing action of the head-fed type threshing unit occurs mainly by the impact between threshing tooth and grains. It may be therefore the most fundamental step to calculate the time and order of the occurrance of impact by the tooth for predicting the performance of threshing unit. The threshing teeth arrangement was defined by length and diameter of threshing dram, number of spiral arrays, number of threshing teeth by kind per one spiral array, number of windings of spiral array around the threshing drum, delay angle of impact line. The linear equations for locus of left and right margin of paddy bundle, spiral array, impact line on the development figure of the threshing drum were expressed by fastors of the threshing teeth arrangement. In the computer program, the teeth which inflict impact were searched successively along the impact line. Searching range and impact condition were defined by the relation between four linear equations. If the impacting tooth was found, time and the kind of threshing tooth was derived from the coordinate of the threshing tooth. At this time the unit torque curve was accumulated on the array of computer memory. At last the completed torque curve of threshing drum shaft was described on the computer screen. Remarkably the peack valae and fluctuation of torque curve was decreased by adopting the delay angle of impact line.

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A Study on the Application of Phased Array Ultrasonic Testing to Main Steam Line in Nuclear Power Plants (원전 주증기배관 웰더렛 용접부 위상배열초음파검사 적용연구)

  • Lee, Seung-Pyo;Kim, Jin-Hoi
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.3
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    • pp.40-47
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    • 2011
  • KSNPs(Korea Standard Nuclear Power Plant) have been applied the break exclusion criteria to the high energy lines passing through containment penetration area to ensure that piping failures would not cause the loss of containment isolation function, and to reduce the resulting dynamic effects. Systems with the criteria are the Main Steam system, Feed Water system, Steam Generator Blowdown system, and Chemical & Volume Control system. In accordance with FSAR(Final Safety Analysis Report), a 100% volumetric examination by augmented in-service inspection of all pipe welds appled the break exclusion criteria is required for the break exclusion application piping. However, it is difficult to fully satisfy the requirements of inspection because 12", 8" and 6" weldolet weldments of Main Steam pipe line have complex structural shapes. To resolve the difficulty on the application of conventional UT(Ultrasonic Testing) technique, realistic mock-ups and UT calibration blocks were made. Simulations of conventional UT were performed utilizing CIVA, a commercial NDE(Nondestructive Examination) simulation software. Phased array UT experiments were performed through mock-up including artificial notch type flaws. A phased array UT technique is finally developed to improve the reliability of ultrasonic test at main steam line pipe to 12", 8" and 6" branch connection weld.

A study on the active phased array antennas with slotline coupling (슬롯라인 결합을 이용한 능동 위상배열안테나에 관한 연구)

  • Mun, Cheol;Kim, Seon-Taek;Yoon, Young-Joong;Park, Han-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.5
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    • pp.981-989
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    • 1997
  • In this paper, the 5-element active phased array antennas coupled through slotline between elements are designed and fabricated. A recent studies on the active phased array antennas using the transmission line coupling which can be designed to provide strong coupling and the appropriate coupling phase. But this sturucture has limitation of expanding in two dimensions for planar active phased array antennas and distortion of the radiation pattern caused by coupling network. Thus our work proposes the slotline coupling structure asthe broadband coupling network for the active phased array antenna. In experiment, 5-elements active phased array antenas have steering range from -30.deg. to 20.deg. off broadside as the free-running frequencies of end elements are controlled. The overall results show that the proposed slotline coupling structure is suited for the coupling network in the actie phased array antenna system. And the proposed coupling structire solves the expansion problem and eliminates the distortion of the radiation pattern caused by the spurious radiation of the transmission line coupling network. Thus thiscan be expanded to two dimensional coupling network for the planar active phased array antenna system.

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Design of Rotman Lens for Curved Array Antenna with Minimal Phase Error (최소 위상 오차를 갖는 곡선 배열안테나용 Rotman 렌즈의 설계)

  • Park, Joo-Rae;Park, Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.10
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    • pp.1077-1086
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    • 2014
  • We propose a design method of a Rotman lens for curved array antenna applicable to conformal array. In this paper, design equations are derived to obtain an array curve, transmission line lengths of a Rotman lens in conjunction with a curved array antenna, and the phase error of a Rotman lens based on these design equations is minimized through the beam curve optimization procedure and the refocusing procedure. Rotman lenses designed by the proposed design equations and design procedures still maintain 3 focal points, can feed a convex or concave array antenna with circular curve, parabolic curve, V-shaped curve, etc as well as a straight line array antenna, and have minimal phase error.