• 제목/요약/키워드: Variation of Thickness

검색결과 1,688건 처리시간 0.031초

Design of Frequency Selective Surface with Chessboard Patterns (체스판 형태를 갖는 주파수 선택구조 설계)

  • Lee, In-Gon;Hong, Ic-Pyo
    • Journal of IKEEE
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    • 제16권1호
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    • pp.15-19
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    • 2012
  • The frequency selective surfaces(FSSs) with chessboard patterns are proposed and designed for the first time in this paper. We proposed the design parameters like slot and patch size, gap between slots or patches, and dielectric thickness of FSS chessboard unit cell proposed in this paper. Also, we found that the variation of design parameters can be used to control the frequency transmission characteristics like the resonant frequency or bandwidth of FSS. To validate the proposed FSS, we fabricated the proposed FSS with the use of 1.0mm FR4 for the bandpass operation at X-band and measured the transmission characteristics. From the results, the proposed FSS with chessboard type can be widely applied to application of the frequency controllable radome design because we can use the design parameters selectively.

Theoretical approach on the effective heat exchanger design using boundary layer theory (경계층 이론을 이용한 고효율 열교환기 설계를 위한 이론적 접근법)

  • Lee, Dong-Yeon;Lee, Moo-Yeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • 제13권12호
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    • pp.5655-5660
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    • 2012
  • The objective of this study is theoretically to suggest the effective heat exchanger design method using boundary layer analysis. The boundary layer formation and interruption on rectangular plate and round plate fins are explained and the heat transfer coefficients showed with the variation of the velocity and temperature boundary layer. In addition, the flow pattern on one plate fin surface considered as external flow and flow pattern between fins considered as internal flow. As a result, theoretical method for the boundary layer interruption avoidance is suggested and the heat transfer coefficient of the round plate fin was higher than that of the rectangular plate fin because of the less thermal and velocity boundary layer thickness except the centerline.

Anneal Characteristics of LiF:Mg,Cu,Na,Si Teflon TLDs (LiF:Mg,Cu,Na,Si Teflon TLD의 열처리 특성)

  • Nam, Young-Mi;Chung, Woon-Hyuk;Lee, Dae-Won;Kim, Hyun-Ja;Kim, Gi-Dong
    • Journal of Radiation Protection and Research
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    • 제22권3호
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    • pp.135-141
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    • 1997
  • The study of anneal characteristics is important for TL dosimeter to reuse. To obtain the annealing condition of the recently developed, new TL dosimeter, LiF:Mg,Cu,Na,Si Teflon Tills in a disk type (diameter 4.5 mm, thickness about $90mg/cm^2$), we studied for pre-irradiation annealing, readout procedure and post-readout annealing, in order. The gamma irradiations were carried out with a $^{60}Co$, dose of 0.1 Gy. We have used the method that observe the variation of thermoluminescent(TL) intensity of these Teflon TLDs over repeated cycles by changing both anneal temperature and anneal time with the TLD reader and the oven. There is a 5% loss in sensitivity over the ten repeated readouts by the annealing condition:pre-irradiation annealing at $80^{\circ}C$ for one hour, readout to $280^{\circ}C$ and post-readout annealing at $270^{\circ}C$ for 20 seconds.

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Application of Ground Penetrating Radar for Assessing Riverbed Variation Near Bridge Piers (지하투과레이다를 이용한 교각 주변의 하상변화 조사)

  • Park, In-Chan;Cho, Won-Cheol;Lee, Jong-Kook
    • Geophysics and Geophysical Exploration
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    • 제8권2호
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    • pp.119-128
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    • 2005
  • The assessment of erosional and depositional patterns near bridge piers is essential to understand the fluvial scour process. Geophysical surveys are particularly effective in determining the riverbed variations in a river and may also be of value for obtaining the previous scour history below the riverbed profile. In this study, GPR (Ground Penetrating Radar), as a non-destructive geophysical technique, was used to assess the existence and depth of existing and infilled scour thickness, streambed materials, and pre- and post- scour surfaces at the bridge piers in Han River, June 2002 and October 2002. The GPR acquisition system used for obtaining profiles of the shallow subsurface deposits was a portable GSSI SIR 2000 system with 100 and 400 MHz antennas. The GPR data obtained along the 24 bridge piers in the flow direction of the river and in the surroundings of 5 bridge piers were compared and presented in this study. It is concluded that GPR surveys can be effective in determining both the water depth and sub-bottom geological structure near the bridge piers and abutments provided that the appropriate instrumentation and operational procedures are applied.

A Study on the Boil-Off Rate Prediction of LNG Cargo Containment Filled with Insulation Powders (단열 파우더를 채용한 LNGCC의 BOR예측에 관한 연구)

  • Han, Ki-Chul;Hwang, Soon-Wook;Cho, Jin-Rae;Kim, Joon-Soo;Yoon, Jong-Won;Lim, O-Kaung;Lee, Shi-Bok
    • Journal of the Computational Structural Engineering Institute of Korea
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    • 제24권2호
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    • pp.193-200
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    • 2011
  • A BOR(Boil-Off Rate) prediction model for the NO96 membrane-type LNG insulation containment filled with superlite powders during laden voyage is presented in this paper. Finite element model for the unsteady-state heat transfer analysis is constructed by considering the air and water conditions and by employing the homogenization method to simplify the complex insulation material composition. BOR is evaluated in terms of the total amount of heat invaded into LNGCC and its variation to the major variables is investigated by the parametric heat transfer analysis. Based upon the parametric results, a BOR prediction model which is in function of the LNG tank size, the insulation layer thickness and the powder thermal conductivity is derived. Through the verification experiment, the accuracy of the derived prediction model is justified such that the maximum relative difference is less than 1% when compared with the direct numerical estimation using the FEM analysis.

Tension Tests of Copper Thin Films (구리박막 시험편의 인장시험)

  • Park, Kyung Jo;Kim, Chung Youb
    • Transactions of the Korean Society of Mechanical Engineers A
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    • 제41권8호
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    • pp.745-750
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    • 2017
  • Tension tests for copper thin films with thickness of $12{\mu}m$ were performed by using a digital image correlation method based on consecutive digital images. When calculating deformation using digital image correlation, a large deformation causes errors in the calculated result. In this study, the calculation procedure was improved to reduce the error, so that the full field deformation and the strain of the specimen could be accurately and directly measured on its surface. From the calculated result, it can be seen that the strain distribution is not uniform and its variation is severe, unlike the distribution in a common bulk specimen. This might result from the surface roughness introduced in the films during the fabrication process by electro-deposition.

Fruit Yield and Quality Evaluation of Sweet Pepper (Capsicum annuum L.) F1 Hybrids Derived from Inbred Lines

  • Shrestha, Surendra Lal;Luitel, Binod Prasad;Lee, Taek Jong;Kang, Won Hee
    • Korean Journal of Breeding Science
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    • 제42권4호
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    • pp.344-350
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    • 2010
  • Sweet pepper inbred lines (KNU1003, KNU1006, KNU1007, KNU1009, KNU1015, KNU1017 and KNU2006) developed at Kangwon National University (KNU) through conventional means, inbred lines (5AVS1, 5AVS2, 5AVS3, 5AVS5, 5AVS7 and 5AVS8) collected at Rural Development Administration (RDA) and inbred lines (SP12, SP27 and SP14) derived from anther culture were used as female parents and anther culture derived homozygous lines (SP9, SP10, SP14, SP24, SP25, SP27, SP30, SP32, SP34, SP38, SP43, SP45 and SP51) were used as male parents to produce $F_1$ hybrids. A total of 37 $F_1$ hybrids were evaluated for fruit yield and quality characters in summer season, 2007. Variation in fruit number, fruit weight, fruit yield per plant and fruit volume was observed among the $F_1$ hybrids. Superiority on yield over standard/commercial varieties were differed among $F_1$ hybrids. Hybrid $5AVS8{\times}SP45$ exhibited highest heterosis over Special (16.5%) and Fiesta (24.7%). Fruit quality characters (fruit length, fruit width, pericarp thickness, total soluble solid, fruit shape and fruit color) were varied among the $F_1$ hybrids. Fruit number, fruit weight and fruit volume per plant were correlated with fruit yield. Based on the standard heterosis expressed by the hybrids and quality characters evaluation, $KNU1017{\times}SP27$, $5AVS1{\times}SP43$, $5AVS5{\times}SP27$, $5AVS8{\times}SP45$, $SP12{\times}SP38$ and $SP27{\times}SP25$ hybrids were found to be superior over commercial cultivars and are selected. Inbred lines of these hybrid combinations can be used to produce $F_1$ hybrid seed for commercial production.

An Experimental study for the heat flux in liquid rocket thrust chamber (액체로켓 추력실에서 발생하는 Heat Flux에 관한 실험적 연구)

  • An, Won Geun;Park, Hui Ho;Hwang, Su Gwon;Kim, Yu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • 제31권3호
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    • pp.65-71
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    • 2003
  • In this research, we make the thin wall chamber to the measurement of heat flux of using a Kerosene/LOx liquid rocket engine's thrust chamber. The wall thickness is one millimeter. We measured outside wall temperature of thrust chamber by nine thermocouple. We suppose the system to the one-dimension unsteady state, and so the heat flux and heat transfer coefficient of thurst chamber are calculated using one-dimensional the transient energy equation by outside wall temperature. In this case, O/F ratio is 2.0, experimental variation is chamber pressure and we got the heat transfer coefficient of the proportion relation of 0.88 times for the chamber pressure.

Synthesis of Photoresist Using Environmental-benign Supercritical $CO_2$ Processes (환경친화적인 초임계 이산화 탄소 공정을 이용한 포토레지스트의 합성)

  • 허완수;이상원;박혜진;김장엽;홍유석;유기풍
    • Polymer(Korea)
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    • 제28권6호
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    • pp.445-454
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    • 2004
  • The requirement for a much finer line width circuits on semiconductors needs new developers such as supercritical fluid to prevent the collapse of the photoresist micro-patterns. The copolymers contain t-butyl methacrylate having an acid-cleavable t-butyl group and supercritical fluid $CO_2$ soluble perfluorinated decyl methacrylate segments. The supercritical fluid $CO_2$-philic properties of the photoresist changed to supercritical fluid $CO_2$-phobic properties after the deprotection reaction by exposure, which made the exposed resist insoluble in the supercritical fluid $CO_2$ developer. The synthesized copolymers containing more than 30% of perfluorinated decyl methacrylate were found to be soluble in supercritical fluid $CO_2$. The variation of film thickness before and after exposure was largest when the mole ratio of perfluorinated decyl methacrylate in the copolymer was 30%.

Cr Electroplating Technology to prevent Interdiffusion between Metallic Fuel and Clad Material (금속연료-피복재 상호확산 방지를 위한 크롬 도금법 적용 연구)

  • Kim, Jun Hwan;Lee, Kang Soo;Yang, Seong Woo;Lee, Byoung Oon;Lee, Chan Bock
    • Korean Journal of Metals and Materials
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    • 제49권12호
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    • pp.937-944
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    • 2011
  • Studies have been carried out in order to reduce fuel-cladding chemical interaction (FCCI) behavior of metallic fuel in sodium-cooled fast reactors (SFR) using an electroplating technique. A $20{\mu}m$ thick Cr layer has been plated by the electrochemical method in the Sargent bath over the HT9 (12Cr-1Mo) clad material and diffusion couple tests of the U-10Zr metallic fuel as well as the rare earth alloy (70Ce-29La) have been conducted. The results show that the Cr plating can prevent FCCI behavior along the fuel-clad interface. However, cracks developed through the thickness during plating, which resulted in the migration of some fuel constituents. Variation of bath temperature, application of pulse current, and post heat treatment have been conducted to control such cracks. We found out that some conditions like the pulse current and the post heat treatment enhanced the layer property by reducing the internal cracks and improving the diffusion couple test.