• Title/Summary/Keyword: H-section

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Analysis and Test of Dynamic Responses of Rocket Payload Section Induced by Acoustic Excitation (음향 가진에 의한 로켓 탑재부의 동적 응답 해석 및 시험)

  • Park, S.H.;Jeong, H.K.;Seo, S.H.;Jang, Y.S.;Yi, Y.M.;Cho, K.R.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.717-720
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    • 2005
  • Acoustic loads generated by a rocket propulsion system cause severe random vibrations on payloads. In developing a new launch vehicle, a random vibration level must be specified before the detailed design of payloads or electronic equipments. This paper deals with prediction procedures of a random vibration level on payload section of KSLV-I. The prediction is based on statistical energy analysis. In order to verify the prediction methodology, test and analysis on a sub-scale payload section are performed. The predicted results subject to very high level of acoustic loads show a good agreement with the test results performed in the high intensity acoustic chamber. The predicted random vibration level on payload section of KSLV-I is also presented in this paper.

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Test of SRC Column-to-Composite Beam Connection under Gravity Loading (중력하중을 받는 SRC기둥-합성보 접합부 실험)

  • Kim, Young Ju;Bae, Jae Hoon;Ahn, Tae Sang;Jang, Seong Hoon
    • Journal of Korean Society of Steel Construction
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    • v.26 no.5
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    • pp.441-452
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    • 2014
  • In this paper, steel reinforced concrete(SRC) column and composite beam connections were statically tested under gravity loading. The composite beam consists of H-section and U-section members. Five full-scaled specimens were designed to investigate the effect of a number of parameters on behavior of connections such as H-section size, the presence of stud connector, the presence of stiffeners and top bars. In addition, structural performance of welded joint between the H-section and the U-section members is mainly discussed, with an emphasis on initial stiffness, strength, deformation capacity.

Assessment of stress in virtual reality environment using power spectral density ratio and second derivative of photoplethysmography (광 혈류 신호의 주파수 파워 특성과 이차 미분값을 이용한 가상환경의 스트레스 평가)

  • Y.H. Nam;Kim, H.T.;H.D. Ko;Park, K.S.
    • Proceedings of the Korean Society for Emotion and Sensibility Conference
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    • 2001.11a
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    • pp.169-172
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    • 2001
  • There are many people who suffer from simulation sickness when immersing in virtual reality. In this study, we analyzed two photoplethysmogram(PPG) parameters - a second derivative parameter and power spectral density ratios - in order to relate PPG parameters with simulation sickness. 36 young, healthy subjects were participated in the experiment, and each subject was equipped with a PPG electrode during his or her immersion. Simulation sickness section was defined as a 7 - second section which starts from the point where a subject reported simulation sickness, and normal section as a same-length section where no physical stimuli was presented to him or her. We compared the PPG parameters of the simulation sickness sections with the normal sections, - d/a ratio is believed to have lower value during vasodilation and higher value during vasoconstriction, however, we could not find much difference in the parameter between normal and simulation sickness sections. We also compared 1 to 10Hz power spectral density ratios in normal sections with in simulation sickness section, and found that 6 density ratios among them have different value. Therefore, the density ratios might be utilized as parameters to detect simulation sickness of subjects.

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Development of CNC Extruder for Variable Cross-Section Extrusion Process and its Applied Research (가변단면 압출기 개발 및 응용 연구)

  • Choi, H.J.;Lim, S.J.;Shin, H.T.;Choi, S.
    • Transactions of Materials Processing
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    • v.17 no.2
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    • pp.130-134
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    • 2008
  • Resource and energy saving is a very important practice for the future as well as for today. Weight saving of structural parts, which are formed by extrusion, plays a key role in manufacturing field. The cross-sections of extruded parts with industrial aluminum are constant in the axial direction by conventional extrusion method. Especially, these aluminum parts used and manufactured in the car industry need other processes to vary the cross-section in the axial direction. However, applications of these parts are often limited by high cost. If the cross-section of the parts is variable by only extrusion with newly developed method, the application of extruded aluminum parts will actually increase. Therefore, a new CNC extruder that can control the section area of a car part was invented for the first time in the nation. Using the extrusion machine, the experiment was performed to validate its workability during the variable section extrusion process. Also, numerical analysis was carried out to investigate the flow mode with different speeds of main ram and various pocket shapes of a die-set in the variable section extrusion process.

Dynamic Response Analysis of Composite H-Type Cross-Section Beams to Random Loads (랜덤하중이 가해진 복합재료 H-형 보의 동적 응답 해석)

  • Kim, Sung-Kyun;Song, Pong-Gun;Song, Oh-Seop
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.10a
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    • pp.130-135
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    • 2011
  • A study of the bending-extension-transverse shear coupled random response of the composite beams with thin-walled open sections subjected to various types of concentrated and distributed random excitations is dealt with in this paper. First of all, equations of motion of thin-walled composite H-type cross-section beams incorporating a number of nonclassical effects of transverse shear and primary and secondary warping, and anisotropy of constituent materials are derived. On the basis of derived equations of motion, analytical expressions for the displacement response of the composite beams are derived by using normal mode method combined with frequency response function method.

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Binding energy of H2 to MOF-5: A Model Study

  • Lee, Jae-Shin
    • Bulletin of the Korean Chemical Society
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    • v.32 no.12
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    • pp.4199-4204
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    • 2011
  • Using models simulating the environment of two distinct adsorption sites of $H_2$ in metal-organic framework-5 (MOF-5), binding energies of $H_2$ to MOF-5 were evaluated at the MP2 and CCSD(T) level. For organic linker section modeled as dilithium 1,4-benzenedicarboxylate ($C_6H_4(COO)_2Li_2$), the MP2 and CCSD(T) basis set limit binding energies are estimated to be 5.1 and 4.4 kJ/mol, respectively. For metal oxide cluster section modeled as $Zn_4O(CO_2H)_6$, while the MP2 basis set limit binding energy estimate amounts to 5.4 kJ/mol, CCSD(T) correction to the MP2 results is shown to be insignificant with basis sets of small size. Substitution of benzene ring with pyrazine ring in the model for the organic linker section in MOF-5 is shown to decrease the $H_2$ binding energy noticeably at both the MP2 and CCSD(T) level, in contrast to the previous study based on DFT calculation results which manifested substantial increase of $H_2$ binding energies upon substitution of benzene ring with pyrazine ring in the similar model.

The Role of Oxygen in Bunsen Reaction Section of Sulfur-Iodine Hydrogen Production Process (황-요오드 수소 제조 공정의 분젠 반응 부분에서 $O_2$의 역할)

  • Hong, Dong-Woo;Kim, Hyo-Sub;Kim, Young-Ho;Park, Chu-Sik;Bae, Ki-Kwang
    • Transactions of the Korean hydrogen and new energy society
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    • v.21 no.4
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    • pp.278-285
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    • 2010
  • The Sulfur-Iodine (SI) thermochemical hydrogen production process of a closed cycle consists of three sections, which are so called the Bunsen reaction section, the $H_2SO_4$ decomposition section and the HI decomposition section. To identify the role of oxygen that can be supplied to the Bunsen reaction section via the $H_2SO_4$ decomposition section, Bunsen reactions with a $SO_2,\;SO_2-O_2$ mixture and $SO_2-N_2$ mixture as feed gases were carried out using a stirred reactor in the presence of $I_2/H_2O$ mixture. As the results, the amounts of $I_2$ unreacted under the feed of mixture gases were higher than those under the feed of $SO_2$ gas only, and the amount of HI produced was relatively decreased. The results of Bunsen reaction using $SO_2-O_2$ mixture were similar to those using $SO_2-N_2$ mixture. It may be concluded that an oxygen in $SO_2-O_2$ mixture has a role as a carrier gas like a nitrogen in $SO_2-N_2$ mixture. The effects of oxygen were decreased with increasing temperature and decreasing oxygen content in $SO_2-O_2$ mixture.

Development of Automatic Sorting System for Green pepper Using Machine Vision (기계시각에 의한 풋고추 자동 선별시스템 개발)

  • Cho, N.H.;Chang, D.I.;Lee, S.H.;Hwang, H.;Lee, Y.H.;Park, J.R.
    • Journal of Biosystems Engineering
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    • v.31 no.6 s.119
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    • pp.514-523
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    • 2006
  • Production of green pepper has been increased due to customer's preference and a projected ten-year boom in the industry in Korea. This study was carried out to develop an automatic grading and sorting system for green pepper using machine vision. The system consisted of a feeding mechanism, segregation section, an image inspection chamber, image processing section, system control section, grading section, and discharging section. Green peppers were separated and transported using a bowl feeder with a vibrator and a belt conveyor, respectively. Images were taken using color CCD cameras and a color frame grabber. An on-line grading algorithm was developed using Visual C/C++. The green peppers could be graded into four classes by activating air nozzles located at the discharging section. Length and curvature of each green pepper were measured while removing a stem of it. The first derivative of thickness profile was used to remove a stem area of segmented image of the pepper. While pepper is moving at 0.45 m/s, the accuracy of grading sorting for large, medium and small pepper are 86.0%, 81.3% and 90.6% respectively. Sorting performance was 121 kg/hour, and about five times better than manual sorting. The developed system was also economically feasible to grade and sort green peppers showing the cost about 40% lower than that of manual operations.

A Parametrical Study on the flexural strength of Concrete-Filled SHS Columns to Composite H-Beam Connections (충전각형강관 기둥-합성 H형강보 접합부 휨성능 결정요인에 관한 연구)

  • Lee, Jong Seok
    • Journal of Korean Society of Steel Construction
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    • v.11 no.4 s.41
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    • pp.385-395
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    • 1999
  • Square hollow section columns and H-section beams have recently been increasing1y used. Rigid column-beam connections cannot be made for the structural system and thus some measures to improve the rotational stiffness of connections should be developed. For this purpose, several types of connections. such as H-section beams connected to concrete-filled square hollow section columns, have been contrived and put to experiment. Since the experimental works are usually difficult and expensive. Particularly test of all the types of connections with similar behavior may not be feasible. Instead, the numerical analysis will be adopted predict the flexural stiffness of connections. In this work, FEM modeling techniques are examined and parametric analysis study has been carried out. The major parameters considered are concrete strength, thickness of steel column, magnitude and eccentricity of axial forces.

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