• Title/Summary/Keyword: Low-profile design

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Co-simulation for Dynamic Characteristic Analaysis of Solenoid Valve for Vehicle (자동차용 솔레노이드 밸브의 동특성을 위한 연성해석)

  • Kim, Ki-Chan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.6
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    • pp.3821-3826
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    • 2014
  • This paper proposes a methodology for developing the performance of a solenoid valve for vehicles based on the dynamic analysis model by an electromagnetic field. The high performance solenoid model with a low current and high thrust was induced through the shape optimal design of the yoke and plunger. To perform the dynamic analysis of the solenoid valve, the input current profile was analyzed. The speed and thrust information was analyzed by FEM with this current profile. The co-simulation method of the circuit model of control logic and electromagnetic model of the solenoid valve was also proposed to analyze the performance with several current patterns. Finally, the performance of the original model and optimal one was compared.

Design of the Step-stare Image Gathering System for an Aerial Reconnaissance (항공 정찰용 Step-stare 영상획득 시스템 설계)

  • Baek, Woonhyuk;Park, Jaeyoung;Ahn, Junghun;Lee, Jungsuk
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.9
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    • pp.813-820
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    • 2014
  • This paper presents design and performance validation of a method for motion compensation using fast steering mirror. First of all, the schematics of the Electro Optical/Infra-Red (EO/IR) and step-stare image gathering system for an aerial reconnaissance are introduced. Because of the steering mirror with low inertia so called Back scan mechanism (BSM), the fast step-stare image gathering technique that is required for taking a high-definition still image will be realized. After then, the BSM hardware includes motors and feedback sensors are introduced. Also, the motion profile for BSM will be designed to compensate roll scan motion of the gimbals. At the end of this paper, designed profile and tracking performance of the EO/IR system with BSM will be validated through experiments.

Optical Lens Design of Image Sensor (이미지 센서용 광학렌즈설계)

  • Lee, Chan-Ku;Lee, Su-Dae;Joung, Maeng-Sig
    • Journal of Korean Ophthalmic Optics Society
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    • v.8 no.2
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    • pp.99-103
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    • 2003
  • This paper presents lens optimization of the resolution and the distortion for a four-element lens design. In order to have compact optical system, we used the tele-photo type lens composed of a positive and a negative power elements instead of retro-focus lens. The specifications of optical lens design are the focal length of 7.2 mm, the F/number of 2.8 and the field angle of $54.7^{\circ}C$. The MTF values are higher than 0.5 in the spatial frequency range up to 110 lp/mm for all of the designed object heights. Also, it is expected to fulfill all the requirements of a digital still camera lens and especially suited for building low-cost, compact digital cameras because of the low-profile property of the lens design.

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Filter Media Specifications for Low Impact Development: A Review of Current Guidelines and Applications (LID 시설 여재에 관한 기술지침 및 적용에 관한 고찰)

  • Guerra, Heidi B.;Kim, Lee-Hyung;Kim, Youngchul
    • Journal of Wetlands Research
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    • v.21 no.4
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    • pp.321-333
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    • 2019
  • A primary aspect of low impact development (LID) design that affects performance efficiency, maintenance frequency, and lifespan of the facility is the type of filter media as well as the arrangement or media profile. Several LID guidelines providing media specifications are currently available and numerous studies have been published presenting the effectiveness of these systems. While some results are similar and consistent, some of them still varies and only a few focuses on the effect of filter media type and arrangement on system performance. This creates a certain level of uncertainty when it comes to filter media selection and design. In this review, a synthesis of filter media specifications from several LID design guidelines are presented and relevant results from different laboratory and field studies are highlighted. The LID systems are first classified as infiltration or non-infiltration structures, and vegetated or non-vegetated structures. Typical profiles of the media according to classification are shown including the different layers, materials, and depth. In addition, results from previous studies regarding the effect of filter media characteristics on hydraulic and hydrologic functions as well as pollutant removal are compared. Other considerations such as organic media leaching, clogging, media washing, and handling during construction were also briefly discussed. This review aims to provide a general guideline that can contribute to proper media selection and design for structural LIDs. In addition, it also identifies opportunities for future research.

Design of LSEV Switched Reluctance Motor Considering Drive Condition (주행조건을 고려한 LSEV용 SRM 설계)

  • Khoi, Huynh Khac Minh;Tanujaya, Marully;Lee, Dong-Hee;Ahn, Jin-Woo
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.889_890
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    • 2009
  • Design of high efficiency Switched Reluctance Motor (SRM) for Low Speed Electric Vehicle (LSEV) is presented in this paper. The design is made from point of view to save more used energy for operating LSEV. Focus on saving the energy gives more efficiency can be produced. Based on applying suitable driving cycles and investigates the frequently power used are foundation to design the proposed motor. Meanwhile through Finite Element Analysis (FEA) characteristic of the proposed motor such as inductance and torque profile can be obtained.

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Shape Optimization of Axial Flow Fan Blade Using Surrogate Model (대리모델을 사용한 축류송풍기 블레이드의 형상 최적화)

  • Kim, Jin-Hyuk;Choi, Jae-Ho;Kim, Kwang-Yong
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2440-2443
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    • 2008
  • This paper presents a three dimensional shape optimization procedure for a low-speed axial flow fan blade with a weighted average surrogate model. Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are discretized by finite volume approximations. Six variables from airfoil profile and lean are selected as design variables. 3D RANS solver is used to evaluate the objective functions of total pressure efficiency. Surrogate approximation models for optimization have been employed to find the optimal design of fan blade. A search algorithm is used to find the optimal design in the design space from the constructed surrogate models for the objective function. The total pressure efficiency is increased by 0.31% with the weighted average surrogate model.

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Optimized Sealing Profile Design of Mechanical Face Seals for a Hydro-power Turbine (소수력 터빈용 기계평면시일의 최적형상설계에 관한 연구)

  • Kim, Chung-Kyun;Kim, Jung-Il;Sihn, Ihn-Cheol;Lim, Kwang-Hyeon
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.06a
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    • pp.499-502
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    • 2006
  • This paper presents computed results of FEM analysis on the tribological contact behaviors of a primary sealing components of mechanical face seals for a small hydro-power turbine. The FEM computed results present that the contact area between seal rings and seal seats is very important for a good tribological performance such as low friction heating, low wear, high contact normal stress in a primary seal ing components. Based on the FEM computation, model III in which has a small sealing contact area shows low dilatation of primary sealing components, and high contact stress between a seal ring and a 1)seal seat.

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Numerical Study About the Effect of the Low Reynolds Number on the Performance in an Axial Compressor (저 레이놀즈 수가 압축기 성능에 미치는 영향에 대한 수치적 연구)

  • Choi, Min-Suk;Chung, Hee-Taeg;Oh, Seong-Hwan;Ko, Han-Young;Baek, Je-Hyun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.2
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    • pp.83-91
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    • 2008
  • A three-dimensional computation was conducted to understand effects of the low Reynolds number on the performance in a low-speed axial compressor at the design condition. The low Reynolds number can originates from the change of the air density because it decreases along the altitude in the troposphere. The performance of the axial compressor such as the static pressure rise was diminished by the separation on the suction surface with full span and the boundary layer on the hub, which were caused by the low Reynolds number. The total pressure loss at the low Reynolds number was found to be greater than that at the reference Reynolds number at the region from the hub to 85% span. Total pressure loss was scrutinized through three major loss categories in a subsonic axial compressor such as the profile loss, the tip leakage loss and the endwall loss using Denton#s loss model, and the effects of the low Reynolds number on the performance were analyzed in detail.

EFFECTS OF THE LOW REYNOLDS NUMBER ON THE PERFORMANCE OF AN AXIAL COMPRESSOR (저 레이놀즈 수가 압축기 성능에 미치는 영향)

  • Choi, Min-Suk;Baek, Je-Hyun;Oh, Seong-Hwan;Ko, Han-Young
    • 한국전산유체공학회:학술대회논문집
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    • 2007.04a
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    • pp.138-141
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    • 2007
  • A three-dimensional computation was conducted to understand effects of the low Reynolds number on the performance in a low-speed axial compressor at the design condition. The low Reynolds number can originates from the change of the air density became it decreases along the altitude in the troposphere. The performance of the axial compressor such as the static pressure rise wag diminished by the separation on the suction surface and the boundary layer on the hub, which were caused by the low Reynolds number. The total pressure loss at the low Reynolds number was found to be greater than that at the reference Reynolds number at the region from the hub to 90% span. Total pressure loss was scrutinized through three major loss categories in a subsonic axial compressor such as profile loss, tip leakage loss and endwall loss using Denton's loss model, and effects of the low Reynolds number on the performance were analyzed in detail.

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Primary Tissue Filure of Bioprosthetic Valves (생물학적 보철판막의 조직실패)

  • 김종환
    • Journal of Chest Surgery
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    • v.26 no.9
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    • pp.667-676
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    • 1993
  • Boprosthetic cardiac valves fail from biological and metabolic as well as mechanical reasons, and the limited durability is the main factor of marked withdrawal in their clinical use. Starting the use of bioprosthetic valves in 1976, up to the end of 1992, the consecutive 178 patients have undergone re-replacement of glutaraldehyde-treated xenograft valves for primary tissue failure [PTF]among the patients who had initial valve replacement at Seoul national University Hospital. The explanted valves were 69 porcine aortic [51 Hancock, 12 Angell-Shiley and 6 Carentier-Edwards] and 141 bovine pericardial [129 standard-profile and 12 low-profile ionescu-Shiley] valwes, with an overall incidence of PTF of 15.2%. The operative mortality rate of re-replacement was 5.1%. Calcific degeneration and tissue damage in relation to calcification were the most frequent modes of PTF on gross examinatin of the explanted valves resulting hemodynamically in valvular regurgitation. The number of Hancocg porcine and the standard-profile Ionescu-Shiley valves in valves in mitral position failed more often from tissue damage [tears, holes, and loss or destruction of cuspal tissue] than calcification [68.3% vs. 39.0%, p<0.01] with resultant regurgitation in 61%, the Ionescu-Shiley valves in the same position in 53%. The tendency of more calcification than tissue damage[71.3% vs. 33.3%, p<0.001]with stenosis in 53%. The tendency of more calcification and immobility of cusps in the latter group was partly explainable by the inclusion of patients of pediatric age. Observation made in this study suggest : many of bioprosthetic valves would fail from calcification and tissue damage : some fail prematurely because of mechanical stress probably owing to the valve design in construction ; andeven those valves escaped early damage would be subject to calcify in the prolonged follow-up period. In conclusion, at the present time, the clinical use of bioprostheticxenograft valves seems to be quite limited until further improvement in biocompatibility and refinement in valve design in manufacture are achieved.

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