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Multibody models with flexible components for inflatable space structures

  • Petrolo, Marco;Governale, Giorgio;Catelani, Daniele;Carrera, Erasmo
    • Advances in aircraft and spacecraft science
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    • v.5 no.6
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    • pp.653-669
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    • 2018
  • This work has the objective to analyze multibody mechanisms of inflatable structures for manned space applications. The focus is on the evaluation of the main characteristics of MaxFlex, a new module of MSC Adams including the effect of nonlinear flexible bodies. MaxFlex integrates the nonlinear Finite Element Analysis (FEA) of Nastran-SOL400-and the Adams multibody capabilities in one unique solver, providing an improvement concerning the concept and technology based on the co-simulation among solvers. MaxFlex converts the equations of motion of the nonlinear FEA into phase-space form and discretizes them according to the multibody system integrator framework. The numerical results deal with an inflatable manned space module having rigid components and a flexible coating made of Kevlar. This paper is a preliminary assessment of the computational capabilities of the software and does not provide realistic guidelines for the actual design of the structure. The analysis leads to some recommendations related to the main issues to consider in a nonlinear simulation including both rigid and flexible components. The results underline the importance of realistic deployment times and applied forces. Also, a proper structural modeling is necessary, but can lead to excessive computational overheads.

Electrical Characteristics of Nano-Structural Monolayer (나노구조 단분자막의 전기적 특성)

  • Choi, Yong-Sung;Cho, Jang-Hoon;Song, Jin-Won;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.166-167
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    • 2006
  • Dendrimers represent a new class of synthetic macromolecules characterized by a regularly branched treelike structure. Multiple branching yields a large number of chain ends that distinguish dendrimers from conventional star-like polymers and microgels. The azobenzene dendrimer is one of the dendrimeric macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. Functional photoisometrization organic molecular the photo-stimulus to organic monomolecular L-films and LB films of dendrimer and 8A5H were performed. The 8A5H organic monolayer in case of pressure stimulus occurred that positive course but in case of the photo-stimulus compared positive and negative. It is assumed that generation forms of displacement current were measured when photo-stimulus for Impression.

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Operational Report of the Mission Analysis and Planning System for the KOMPSAT-I

  • Lee, Byoung-Sun;Lee, Jeong-Sook;Kim, Jae-Hoon;Lee, Seong-Pal;Kim, Hae-Dong;Kim, Eun-Kyou;Choi, Hae-Jin
    • ETRI Journal
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    • v.25 no.5
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    • pp.387-400
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    • 2003
  • Since its launching on 21 December 1999, the Korea Multi-Purpose Satellite-I (KOMPSAT-I) has been successfully operated by the Mission Control Element (MCE), which was developed by the ETRI. Most of the major functions of the MCE have been successfully demonstrated and verified during the three years of the mission life of the satellite. This paper presents the operational performances of the various functions in MAPS. We show the performance and analysis of orbit determinations using ground-based tracking data and GPS navigation solutions. We present four instances of the orbit maneuvers that guided the spacecraft form injection orbit into the nominal on-orbit. We include the ground-based attitude determination using telemetry data and the attitude maneuvers for imaging mission. The event prediction, mission scheduling, and command planning functions in MAPS subsequently generate the spacecraft mission operations and command plan. The fuel accounting and the realtime ground track display also support the spacecraft mission operations.

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Anodic Dissolution of Electrodeposited Iron Group Elements in Phthalate Buffer Solution (Phthalate 완충용액에서 전해 석출한 철족 원소의 산화 용해 반응)

  • Chon, Jung-Kyoon;Kim, Youn-Kyoo
    • Journal of the Korean Chemical Society
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    • v.51 no.1
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    • pp.14-20
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    • 2007
  • The anodic dissolution of electrodeposited iron group elements (Fe, Co, Ni) were studied in phthalate buffer solution. The pH dependence of the corrosion potential, the corrosion current and Tafel slope was measured for each element. Based on the electrochemical parameters including Tafel slopes, we proposed the redox mechanism of the corrosion and the passivation. The adsorption of various phthalate species on the electrodeposited iron group elements seemed to be affected the corrosion mechanisms.

A Specific Character of Fashion-Presentation in the Korean Music stars since 1990s (1990년대 이후 국내 대중음악 스타의 패션연출 특성에 관한 고찰)

  • 유송옥;한자영
    • Journal of the Korean Society of Costume
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    • v.51 no.5
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    • pp.61-75
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    • 2001
  • This study was intended to observe strategic fashion-presentation in Music stars according to the change of the star system in the Korean popular musics. The Korean Music stars since 1990s have been made, fabricated and have excessively depended on the demand of the teenagers. Therefore their distinctive fashion-presentation is considered as more important element than those of the past. Consequently. the characteristics of the fashion-presentation in the Korean Music star these days are as follows : First. Music stars shows fashion-presentation that has a consistent fashion theme. That is one of the key success factor to raise the recognition of star singer. Second. Music star produces fashion images which reflects identity and of subculture. Those appearance have won wild popularity of the Peeps 1990's new generation. Third. although there is no change music genre and emotion. through merely renovation of their fashion image, Music star got diversity and originality of the characteristics of contemporary cultural goods. Fourth. In case of famous dance groups, in the past they maintained a singular atmosphere as a group, but in 1990'Music star group each members of the group have individually fashion-presentation. So, they can get more fans. Fifth, Music singers borrow or duplicate fashion-presentation from each others. Such as similar fashion-presentation guarantees support of the same fans.

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Validation of Efficiency Analysis for Independent Multi-Phase BLDC Motor Using Hysteresis PWM Current Control Method (Hysteresis PWM 전류 제어 기법을 사용한 독립 다상 BLDC 전동기의 효율 해석 유효성 검증)

  • Lee, Junewon;Kong, Yeongkyung;Park, Sunjung;Choi, Hoyong;Hong, Sungyoung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.17 no.5
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    • pp.604-610
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    • 2014
  • In this paper, the analysis and the experiment of independent multi-phase BLDC motor are performed. The back-emf, iron loss analysis are performed by the finite element method and compared with experimental results. The independent multi-phase BLDC motor is manufactured and to measure the efficiency of the motor, evaluation system is also manufactured including the load generator. By comparing the analytic and the experimental results, the effectiveness of the analysis model is verified when calculating the efficiency of the motor.

Nutritional Assessment of the Older Population: Practical Application and Limitation

  • Yoon, Jin-Sook
    • Journal of Community Nutrition
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    • v.2 no.1
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    • pp.36-49
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    • 2000
  • Evaluation of nutritional status is an essential element in providing appropriate intervention strategies to achieve the highest level of health, Nutritional assessment of the older population is complicated by many factors which do not significantly affect the nutritional status in young adults, therefore, it should be considered in two ways; community-dwelling elders group and hospitalized or institutionalized elderly group. To sort out the individuals with nutritional problems in a community efficiently, nutrition screening tools must be simple, relatively inexpensive, and applicable to a large number of subjects. Combination of tools and indicators such as 24-hour food recall, body weight and height, and questionnaires on eating practices, and the presence of chronic diseases is practically applicable as basic tools of nutritional screening of older age group. However, the lack of validated screening techniques remains a barrier in improving nutrition. Validation is only limited to energy, BMI, protein intake of the older populations living in western countries. Further refinement of nutritional assessment tools is demanded to figure out whether those are practically applicable to community-living older adults in Asian Society. A careful and systematic evaluation of nutritional assessment tools should be carried out prior to implementation of stepwise nutrition service to the heterogeneous older population. For an in-depth nutritional assessment at the individual level, we need to extend research efforts to clarify the requirements of nutrients due to aging and diseases. More cost-effective method that will allow rapid analysis of survey results are needed so that information can be readily available to policymakers.

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Development of Real Time Multibody Vehicle Dynamics Software Part I : Real Time Vehicle Model based on Subsystem Synthesis Method (실시간 다물체 차량 동역학 소프트웨어 개발 Part Ⅰ: 부분시스템 합성방법에 의한 실시간 차량 모델)

  • Kim, Sung-Soo;Jeong, Wan-Hee;Lee, Chang-Ho;Jung, Do-Hyun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.1
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    • pp.162-168
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    • 2009
  • The real-time multibody vehicle model based on the subsystem synthesis method has been developed. Suspension, anti roll bar, steering, and tire subsystem models have been developed for vehicle dynamics. The compliance effect from bush element has been considered using a quasi-static method to achieve the real time requirement. To validate the developed vehicle model, a quarter car and a full vehicle simulations have been carried out comparing simulation results with those from the ADAMS vehicle model. Real time capability has been also validated by measuring CPU time of the simulation results.

The Method of Estimating Group Effect with Small Pull-out Tests of Screw Anchors (나선형 앵커의 실내인발시험을 이용한 무리효과 평가기법)

  • Park Si-Sam;Lee Hyung-Kyu
    • Journal of the Korean Geotechnical Society
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    • v.21 no.10
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    • pp.123-131
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    • 2005
  • In the present study, laboratory pull-out tests with screw anchors are carried out to investigate behavior characteristics of the anchors used in foundation system of underground structures which are applied to uplifting seepage forces. Small scaled pull-out tests in sand under saturated condition and dry condition were carried out. For estimating the group effects of the anchors, the upward displacement and the pullout load varied with spacing of the anchor were observed. The test results were compared with theoretical equation for the ultimate pull-out force. Also, the result of tests can be used to the finite element analysis program, $PENTAGON^{2D}$.

A Time-multiplexed 3d Display Using Steered Exit Pupils

  • Brar, Rajwinder Singh;Surman, Phil;Sexton, Ian;Hopf, Klaus
    • Journal of Information Display
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    • v.11 no.2
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    • pp.76-83
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    • 2010
  • This paper presents the multi-user autostereoscopic 3D display system constructed and operated by the authors using the time-multiplexing approach. This prototype has three main advantages over the previous versions developed by the authors: its hardware was simplified as only one optical array is used to create viewing regions in space, a lenticular multiplexing screen is not necessary as images can be produced sequentially on a fast 120Hz LCD with full resolution, and the holographic projector was replaced with a high-frame-rate digital micromirror device (DMD) projector. The whole system in this prototype consists of four major parts: a 120Hz high-frame-rate DMD projector, a 49-element optical array, a 120Hz screen assembly, and a multi-user head tracker. The display images for the left/right eyes are produced alternatively on a 120Hz direct-view LCD and are synchronized with the output of the projector, which acts as a backlight of the LCD. The novel steering optics controlled by the multiuser head tracker system directs the projector output to regions referred to as exit pupils, which are located in the viewers’eyes. The display can be developed in the "hang-on-the-wall"form.