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  • Title/Summary/Keyword: 구조계산

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Flexible Body Dynamics Analysis of Agricultural Tractor Using 4-Post Road Simulator (4-Post Road Simulator 를 이용한 농용 트랙터의 유연 다물체 동역학 해석)

  • Park, Ji Soo;Lee, Kang Wook;Cho, Chong Youn;Yoon, Ji Won;Shin, Jai Yoon
    • Transactions of the KSME C: Technology and Education
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    • v.3 no.2
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    • pp.83-88
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    • 2015
  • Agricultural tractors are utilized on rough road such as rice paddy field. Therefore, static and dynamic load should be considered when simulating structural analysis with finite element analysis (FEA). But it consumes a lot of time and effort to measure dynamic load because of difficulty and complexity in modeling various field working load conditions and kinematics of machinery. In this paper, to reduce the efforts, 4-post road simulator is developed for agricultural tractor like modeling commercial vehicle. In proving ground test in our facility, I measured acceleration of front/rare axle and strain of body frame to validate input loads. The acceleration is used for defining input loads. And strain is validated with dynamics analysis including mode superposition method. As a result, I was able to calculate 4-post input road profiles, which represent similar proving ground profile with good reliability.

Performance Characteristics of p-i-n type Organic Thin-film Photovoltaic Cell with Rubrene:CuPc Hole Transport Layer (Rubrene:CuPc 정공 수송층이 도입된 p-i-n형 유기 박막 태양전지의 성능 특성 연구)

  • Kang, Hak-su;Hwang, Jongwon;Kang, Yongsu;Lee, Hyehyun;Choe, Youngson
    • Korean Chemical Engineering Research
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    • v.48 no.5
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    • pp.654-659
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    • 2010
  • We have investigated the effect of rubrene-doped CuPc hole transport layer on the performance of p-i-n type bulk hetero-junction photovoltaic device with a structure of ITO/PEDOT:PSS/CuPc: rubrene/CuPc:C60(blending ratio 1:1)/C60/BCP/Al and have evaluated the current density-voltage(J-V) characteristics, short-circuit current(Jsc), open-circuit voltage(Voc), fill factor(FF), and energy conversion efficiency(ηe) of the device. By rubrene doping into CuPc hole transport layer, absorption intensity in absorption spectra decreased. However, the performance of p-i-n organic type bulk hetero-junction photovoltaic device fabricated with crystalline rubrene-doped CuPc was improved since rubrene shows higher bandgap and hole mobility compared to CuPc. Increased injection currents have effected on the performance improvement of the present device with energy conversion efficiency(ηe) of 1.41%, which is still lower value compared to silicone solar cell and many efforts should be made to improve organic photovoltaic devices.

Application of Vision-based Measurement System for Estimation of Dynamic Characteristics on Hanger Cables (행어케이블의 동특성 추정을 위한 영상계측시스템 적용)

  • Kim, Sung-Wan;Kim, Nam-Sik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.1A
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    • pp.1-10
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    • 2012
  • Along with the development of coasts, islands and mountains, the demand of long-span bridges increases which, in turn, brings forth the construction of cable-supported bridges like suspension and cable-stayed bridges. There are various types of statically indeterminate structures widely applied that supported the main girder with stay cables, main cables, hanger cables with aesthetic structural appearance. As to the cable-supported bridges, the health monitoring of a bridge can be identified by measuring tension force on cable repeatedly. The tension force on cable is measured either by direct measurement of stress of cable using load cell or hydraulic jack, or by vibration method estimating tension force using cable shape and measured dynamic characteristics. In this study, a method to estimate dynamic characteristics of hanger cables by using a digital image processing is suggested. Digital images are acquired by a portable digital camcorder, which is the sensor to remotely measure dynamic responses considering convenient and economical aspects for use. A digital image correlation(DIC) technique is applied for digital image processing, and an image transform function(ITF) to correct the geometric distortion induced from the deformed images is used to estimate subpixel. And, the correction of motion of vision-based measurement system using a fixed object in an image without installing additional sensor can be enhanced the resolution of dynamic responses and modal frequencies of hanger cables.

The Analysis and Field Measurement of Longitudinal Track Forces for Long Railroad Bridges (교량상 궤도축력의 해석 및 실측결과 비교)

  • Kang, Kee Dong;Park, Jong Bang;Kim, In Jae;Park, Dae Geun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.4
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    • pp.907-913
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    • 1994
  • The design of railroad bridges differs from road bridges because of the interface between track structure and bridge structure. The track generally consists of Continuous Welded Rail(CWR) which is fixed by fasteners to the sleepers embedded in the ballast. The ballast provides the interface between the track structure and the bridge structure. Large longitudinal forces can develop from the temperature variation in rail and bridge structure. These longitudinal forces are specially important for long bridges because the bridge layout for span length, pier dimensions and arrangement and type of bearings can be governed by these forces. This report provides a comparison of longitudinal track forces determined by analysis and actual measured track forces. In recent practice the longitudinal track force for European railways is analyzed using a finite element analysis method. This method is very time-consuming and requires the detail design of the bridge to be complete. Redesign is required if the design criteria for longitudinal track forces are not satisfied. There is a need to develop a simple analysis method considering the large number of bridge structures and a relatively short design time on the Korean High Speed Rail Project. The analysis results presented herein, based on a simplified analysis, show good agreement with those obtained by finite element analysis, as well as with those measured on an actual track. The proposed analysis method is particularly useful for the preliminary design of bridge structures.

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Development of a compact fuel processor for building fuel cells (건물용 연료전지를 위한 컴팩트 연료개질기 개발)

  • Jung, Un Ho;Koo, Kee Young;Yoon, Wang Lai
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.224.2-224.2
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    • 2010
  • 연료개질기는 연료전지 시스템의 핵심 구성요소 중의 하나로 도시가스로부터 수소를 생산하는 역할을 담당한다. 연료개질기는 주로 탈황, 수증기 개질, 수성가스 전이, 선택적 산화 반응의 4단계로 구성되어 있으며 이 중 상온 탈황부분을 제외한 나머지 부분은 일체화 설계를 통해 제작된다. 탈황의 경우 도시가스에 포함된 부취제인 황화합물를 제거하여 후단에 위치한 촉매층이 황에 의해 피독되는 것을 막는 역할을 하며 주로 상온흡착식 탈황제를 사용한다. 황이 제거된 도시가스는 물과 함께 연료개질기로 도입되어 수증기 개질반응을 통하여 수소, 일산화탄소, 이산화탄소 및 소량의 메탄과 미반응 수증기로 구성된 개질가스로 전환된다. 이후의 수성가스 전이반응에서는 일산화탄소가 물과 반응하여 수소 생산량을 늘리며 동시에 일산화탄소의 농도를 낮추게 된다. 또한 고분자 전해질 연료전지에 공급되는 개질가스는 선택적 산화반응을 통하여 일산화탄소의 농도를 10ppm이하로 유지하게 된다. 이러한 기능의 연료개질기 개발의 주요 이슈로는 컴팩트화 및 고효율화이며 이 두가지 요소를 고려하여 연료개질기를 설계하여야 한다. 연료전지 시스템의 전체부피를 줄이기 위한 노력의 일환으로 연료개질기의 컴팩트화가 요구되는데 가정용 연료전지 기술 선진국인 일본 제품의 경우 1Nm3/h급 연료개질기의 부피는 20L정도로 알려져 있다. 또한 연료전지 시스템의 효율은 연료개질기의 개질효율과 연료전지 스택의 발전효율의 곱으로 계산되기 때문에 연료개질기의 연료개질 효율은 전체 시스템의 효율에 직접적으로 영향을 미치게 된다. 한국에너지기술연구원에서는 수소생산량 기준 1Nm3/h급 연료개질기의 개발을 완료하였으며 크기 및 효율면에서 선진국 제품과 비교하여 동등 또는 우위의 수준을 달성하였다. 연료개질기 내부의 혼합 및 분배 구조를 개선하고 각 촉매층의 최적 배치를 통해 연료개질기의 부피를 최소화 하였으며 연료개질기 내부에서 고온부위와 저온부위 사이의 최적 열교환을 통해 열효율을 극대화 시켰다. 현재 개발된 1Nm3/h급 개질기의 단열 후 부피는 13.5L 그리고 단독운전 시 열효율은 80%(LHV)로 측정되었다. 또한 1Nm3/h급의 연료개질기의 스케일-업 설계를 통하여 수소생산량 3, 5Nm3/h 규모의 연료개질기를 개발하였으며 성능평가가 진행 중이다.

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A Fast Motion Estimation Algorithm Based on Multi-Resolution Frame Structure (다 해상도 프레임 구조에 기반한 고속 움직임 추정 기법)

  • Song, Byung-Cheol;Ra, Jong-Beom
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.37 no.5
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    • pp.54-63
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    • 2000
  • We present a multi-resolution block matching algorithm (BMA) for fast motion estimation At the coarsest level, a motion vector (MV) having minimum matching error is chosen via a full search, and a MV with minimum matching error is concurrently found among the MVs of the spatially adjacent blocks Here, to examine the spatial MVs accurately, we propose an efficient method for searching full resolution MV s without MV quantization even at the coarsest level The chosen two MV s are used as the initial search centers at the middle level At the middle level, the local search is performed within much smaller search area around each search center If the method used at the coarsest level is adopted here, the local searches can be done at integer-pel accuracy A MV having minimum matching error is selected within the local search areas, and then the final level search is performed around this initial search center Since the local searches are performed at integer-pel accuracy at the middle level, the local search at the finest level does not take an effect on the overall performance So we can skip the final level search without performance degradation, thereby the search speed increases Simulation results show that in comparison with full search BMA, the proposed BMA without the final level search achieves a speed-up factor over 200 with minor PSNR degradation of 02dB at most, under a normal MPEG2 coding environment Furthermore, our scheme IS also suitable for hardware implementation due to regular data-flow.

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Electrochemical and Optical Studies on the Passivation of Nickel (니켈의 부동화에 관한 전기화학적 및 광학적 연구)

  • Dong Jin Kim;Woon-Kie Paik
    • Journal of the Korean Chemical Society
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    • v.26 no.6
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    • pp.369-377
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    • 1982
  • The technique of combined-measurement of reflectance and ellipsometric parameters was used for studying the anodic film formed on nickel surface in basic solutions. An ellipsometer was automated for transient measurements by way of modulating the plane-polarized light with the Faraday effect. Surface film was formed electrochemically by applying a potential step from the reduction potential range to the passivation range on a polished, high-purity, polycrystalline nickel specimen. From that instant, the changes in the reflectance(r) and the ellipsometric parameters(Δ,Ψ) of the surface film were recorded by the automatic ellipsometer. Three exact simultaneous equations including these optical signals, Δ,Ψ and r were solved numerically with a computer in order to determine the optical properties, n, k, and the thickness, τ, of the surface film. From the computed results which showed dependence on pH and time, it was found that passivation of nickel can be effectively attained by surface film thinner than 15\AA and this passivation film has a small optical absorption coefficient. It seemed that a high pH environment enhances the rate of passivation and is favorable for a denser structure of the surface film. The experimental evidence is in accordance with the hypothesis that the composition of the passive film can be approximated by Ni(OH)2 in the early stage of passivation and that as time passes the composition changes partially toward that of NiO through dehydration.

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Analysis of Traffic Delays at Scramble Crosswalks Considering Signal Phase Sequence and Traffic Volume (신호현시 순서와 통행량을 고려한 대각선 횡단보도 지체도 분석)

  • Kim, Suji;Lee, Jooyoung;Kwon, Yeongmin
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.19 no.3
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    • pp.116-128
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    • 2020
  • This study compared the delays of scramble crosswalks and general crosswalks, considering the pedestrian and vehicle traffic at intersections. Based on the signal theory, this study used traffic delays as a measure of feasibility of installing scramble crosswalks. The road structure and length of signal lights were assumed to be specific numbers to calculate the delays in vehicles and pedestrians. With the computed delays, this study compared general crosswalks and scramble crosswalks, and evaluated the feasibility sections on the installation of scramble crosswalks using circular and non-circular signal phases, respectively. The analysis confirmed that the introduction of scramble crosswalks might be more appropriate when the traffic ratio on the main roads is high. In addition, the application of non-circular signal phases is more proper for the operation of scramble crosswalks than circular signal phases. In the non-circular signaling system, however, it was shown that diagonal crosswalks might not be practical if the demand for diagonal crossing is too low. These results are expected to contribute to the development of basic guidelines for assessing the installment feasibility of scramble crosswalks in terms of traffic operation and efficiency.

A Study of Evacuation Route Guidance System using Location-based Information (위치기반 정보를 활용한 비상대피경로 안내 지원시스템 개발)

  • Kim, Ho-Kyeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.9
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    • pp.18-23
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    • 2017
  • The shipyard quay process struggles to control workers and maintain a secure working environment because of the presence of at least 1,000 people. Therefore, safety accidents such as an explosion or a fire are likely to occur. With the recent increase in safety accidents at shipyards, the requirements for safety and process monitoring have been strengthened. Major shipyards are conducting researchto monitor the process in real time and to detect the work environment for safety. In this paper, we propose a safe and accurate evacuation route based on the information of the dangerous area and the user's location based on a mobile application to reduce the casualty accidents in the presence of many personnel in a concentrated area. To do this, we analyze the trend of the fire escape system on the ground building, compare various algorithms for escape route calculation, select appropriate algorithms for this study, and perform programming. A basic experiment was conducted to confirm the results. The proposed method is expected to be used in large ship construction sites, passenger ships and large public facilities to reduce accidents in the case of a safety accident.

Kinetic Characterization of an Iron-sulfur Containing Enzyme, L-serine Dehydratase from Mycobacterium tuberculosis H37Rv (Mycobacterium tuberculosis H37Rv로부터 유래된 철-황 함유 효소인 L-세린 탈수화효소의 동력학적 특성)

  • Han, Yu Jeong;Lee, Ki Seog
    • Journal of Life Science
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    • v.28 no.3
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    • pp.351-356
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    • 2018
  • L-Serine dehydratase (LSD) is an iron-sulfur containing enzyme that catalyzes the conversion of L-serine to pyruvate and ammonia. Among the bacterial amino acid dehydratases, it appears that only the L-serine specific enzymes utilize an iron-sulfur cluster at their catalytic site. Moreover, bacterial LSDs are classified into four types based on structural characteristics and domain arrangement. To date, only the LSD enzymes from a few bacterial strains have been studied, but more detailed investigations are required to understand the catalytic mechanism of various bacterial LSDs. In this study, LSD type II from Mycobacterium tuberculosis (MtLSD) H37Rv was expressed and purified to elucidate the biochemical and catalytic properties using the enzyme kinetic method. The L-serine saturation curve of MtLSD exhibited a typically sigmoid character, indicating an allosteric cooperativity. The values of Km and kcat were estimated to be 59.35±1.23mM and 18.12±0.20s1, respectively. Moreover, the plot of initial velocity versus D-serine concentration at fixed L-serine concentrations showed a non-linear hyperbola decay shape and exhibited a competitive inhibition for D-serine with an apparent Ki value of 30.46±5.93mM and with no change in the kcat value. These results provide insightful biochemical information regarding the catalytic properties and the substrate specificity of MtLSD.