• Title/Summary/Keyword: Assembly Simulation

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Three Dimensional Thermal-Elastic Plastic Analysis of GMAW Considering the Melting of Weld Bead (비드의 용용상태를 고려한 가스메탈 아크용접의 3차원 열탄소성 변형 해석)

  • Jang-Hyun Lee;Jong-Gye Shin;Ji-Hoon Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.39 no.1
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    • pp.49-60
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    • 2002
  • Welding is essential in ship production since welding is very popular method for joining two or more metals. However, welding causes residual stress and distortion and these give a bad influence to the structure strength and assembly of ship blocks. Therefore, prediction and treatment of residual stress and distortion is a key to accuracy control in shipyard. In this paper, a computational procedure, based on thermal-elastic-plastic 3-dimensional FEA, has been suggested to simulate butt and fillet welding process. In the simulation process, temperature distribution at each time step is obtained by heat transfer analysis and then thermal deformation analysis is done with obtained temperature distributions to find the residual stress and distortion. In heat transfer analysis, enthalpy method is used to realize phase change at melting temperature. Also element birth and death method is used to simulate adding of weld metal in both heat transfer analysis and thermal elastic plastic analysis. The proposed procedure is verified by related researches and the results show good agreement with those of related researches.

Design of $GF(3^m)$ Current-mode CMOS Multiplier ($GF(3^m)$상의 전류모드 CMOS 승산기 설계)

  • Na, Gi-Soo;Byun, Gi-Young;Kim, Heung-Soo
    • Journal of IKEEE
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    • v.8 no.1 s.14
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    • pp.54-62
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    • 2004
  • In this paper, we discuss on the design of a current mode CMOS multiplier circuit over $GF(3^m)$. Using the standard basis, we show the variation of vector representation of multiplicand by multiplying primitive element α, which completes the multiplicative process. For the $GF(3^m)$ multiplicative circuit design, we design GF(3) adder and multiplier circuit using current mode CMOS technology and get the simulation results. Using the basic gates - GF(3) adder and multiplier, we build the $GF(3^m)$ multiplier circuit and show the examples for the case m=3. We also propose the assembly of the operation blocks for a complete $GF(3^m)$ multiplier. Therefore, the proposed circuit is easily extensible to other p and m values over $GF(p^m)$ and has advantages for VLSI implementation. We verify the validity of the proposed circuit by functional simulations and the results are provided.

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Design review of fuel vent-relief valve (연료 벤트/릴리프 밸브의 설계 분석)

  • Jang, JeSun;Kil, GyoungSub;Han, SangYeop;Park, Jong-Ho
    • Aerospace Engineering and Technology
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    • v.11 no.2
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    • pp.109-116
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    • 2012
  • A vent-relief valve performs as a safety-valve assembly for liquid propellant feeding system of space launch vehicle, which relives pressurant propellant tanks during the filling and the flight. At vent mode, valve is opened and closed by driving pneumatic pressure, and at relief mode, valve is automatically operated to set relief pressure. In this study, we have analyzed a basic layout of vent-relief valve which is designed using foreign LVs(Saturn) to satisfy requirements of Korean Space Launch Vehicle. The simulation model of vent-relief valve is designed by using the AMESim code to verify design parameters and evaluate pneumatic behaviors of valve. In this study, we performed dynamic characteristic simulations on design parameters. And we could predict opening/closing time and pressures, operating performances on design parameters. Using this results, we could suggest detail design and boundary conditions of design.

A Hyper Suprime-Cam View of the Interacting Galaxies of the M81 Group - Structures and Stellar Populations

  • Arimoto, Nobuo;Okamoto, Sakurako
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.2
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    • pp.39.2-39.2
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    • 2017
  • Over the last decade, deep studies of nearby galaxies have led to the discovery of vast stellar envelopes that are often rich in substructure. These components are naturally predicted in models of hierarchical galaxy assembly, and their observed properties place important constraints on the amount, nature, and history of satellite accretion. One of the most effective ways of mapping the peripheral regions of galaxies is through resolved star studies. Using wide-field cameras equipped to 8 m class telescopes, it has recently become possible to extend these studies to systems beyond the Local Group. Located at a distance of 3.6 Mpc, M81 is a prime target for wide-field mapping of its resolved stellar content. In this talk, we present the detailed results from our deep wide-field imaging survey of the M81 group with the Hyper Suprime-Cam (HSC), on the Subaru Telescope. We report on the analysis of the structures, stellar populations, and metallicities of old dwarf galaxies such as NGC3077, IKN, KDG061, as well as young stellar systems such as Arp's Loop and Holmberg IX. Several candidates for yet-undiscovered faint dwarf galaxies and young stellar clumps in the M81 group will also be introduced. The peculiar galaxy NGC3077 has been classified as the irregular galaxy. Okamoto et al. (2015, ApJ 809, L1) discovered an extended halo structure with S-shape elongated tails, obvious feature of tidal interaction. With a help of numerical simulation by Penarrubia et al. (2009, ApJ 698, 222), we will demonstrate that this tidal feature was formed during the latest close encounters between M81, M82, and NGC 3077, which induced star formation in tidally stripped gas far from the main bodies of galaxies. It is not clear whether the latest tidal interaction was the first close encounters of three galaxies. If NGC3077 is still surrounded by the dark matter halo, it implies that NGC3077 has undergone the first tidal stripping by larger companions. Kinematic studies of inter galactic globular clusters and planetary nebulae would tell us the past history of tidal interaction in this group of galaxies.

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Double Side SMT and Molding Process Development for mPossum Package

  • Kim, ByongJin;Cho, EunNaRa;Kim, ChoongHoe;Lee, YoungWoo;Lee, JaeUng;Ryu, DongSu;Jung, GyuIck;Kang, DaeByoung;Khim, JinYoung;Yoon, JuHoon;Kim, Sun-Joong
    • Journal of the Microelectronics and Packaging Society
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    • v.23 no.4
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    • pp.43-48
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    • 2016
  • 3-Dimensional System in Package (3-D SiP) structure (Amkor calls it mPossum-molded Possum) using double side Surface Mount Technology (SMT) and double side molding was evaluated in order to achieve small/thin form factor as well as good functionality by integration and double side layout. As the new platform on laminate substrate basis, molding process was challenge in mold flow balance at top and bottom side and package warpage control over the overall assembly process. There were two types of different molding process evaluated with 1) 1-step molding which was done at both side at the same time and 2) 2-step molding which was done at the conventional molding process twice. Mold simulation helped to narrow down the material selections and parameters available before actual sample build. There were many challenges for this first trial in design/ parameter and material types but optimized them to enable this structure.

Electron Accelerator Shielding Design of KIPT Neutron Source Facility

  • Zhong, Zhaopeng;Gohar, Yousry
    • Nuclear Engineering and Technology
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    • v.48 no.3
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    • pp.785-794
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    • 2016
  • The Argonne National Laboratory of the United States and the Kharkov Institute of Physics and Technology of the Ukraine have been collaborating on the design, development and construction of a neutron source facility at Kharkov Institute of Physics and Technology utilizing an electron-accelerator-driven subcritical assembly. The electron beam power is 100 kW using 100-MeV electrons. The facility was designed to perform basic and applied nuclear research, produce medical isotopes, and train nuclear specialists. The biological shield of the accelerator building was designed to reduce the biological dose to less than 5.0e-03 mSv/h during operation. The main source of the biological dose for the accelerator building is the photons and neutrons generated from different interactions of leaked electrons from the electron gun and the accelerator sections with the surrounding components and materials. The Monte Carlo N-particle extended code (MCNPX) was used for the shielding calculations because of its capability to perform electron-, photon-, and neutron-coupled transport simulations. The photon dose was tallied using the MCNPX calculation, starting with the leaked electrons. However, it is difficult to accurately tally the neutron dose directly from the leaked electrons. The neutron yield per electron from the interactions with the surrounding components is very small, ~0.01 neutron for 100-MeV electron and even smaller for lower-energy electrons. This causes difficulties for the Monte Carlo analyses and consumes tremendous computation resources for tallying the neutron dose outside the shield boundary with an acceptable accuracy. To avoid these difficulties, the SOURCE and TALLYX user subroutines of MCNPX were utilized for this study. The generated neutrons were banked, together with all related parameters, for a subsequent MCNPX calculation to obtain the neutron dose. The weight windows variance reduction technique was also utilized for both neutron and photon dose calculations. Two shielding materials, heavy concrete and ordinary concrete, were considered for the shield design. The main goal is to maintain the total dose outside the shield boundary less than 5.0e-03 mSv/h during operation. The shield configuration and parameters of the accelerator building were determined and are presented in this paper.

A pilot study on the formation and evolution of the Intracluster light: Preliminary results of the Coma cluster

  • Yoo, Jaewon;Ko, Jongwan
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.1
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    • pp.52.1-52.1
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    • 2017
  • Galaxy clusters are the most massive gravitationally bound systems and thus probably the most recent objects to form. One of promising routes to understand the assembly history of galaxy clusters is to measure observable quantities of components in clusters that are sensitive to the evolutionary state of the cluster. Recent deep observations on the nearby clusters show distinct diffuse intracluster light (ICL), that the light from stars are not bound any individual cluster galaxy, however until now this component has not been well studied due to its faint nature, with typical brightness of ~100 times fainter than the sky background. As shown in galaxy cluster simulation studies, the ICL abundance increases during various dynamical exchanges of galaxies such as the disruption of dwarf galaxies, major mergers between galaxies and the tidal stripping of galaxies. Thus, the ICL is an effective tool to measure the evolutionary stage of galaxy clusters. Moreover, the investigation of the ICL evolution mechanism will allow us understand the galaxy evolution process therein. In this pilot study, we target the Coma cluster, where the existing ICL studies are limited only in the central region. With large and uniform deep optical images from the Subaru telescope, available only recently (Okabe et al. 2014), we are developing a robust ICL measurement technique, extracting the ICL surface brightness and color profiles, which will allow us to study the origin of the ICL and its connection to the evolutionary history of the Coma cluster. For the next phase, we plan to utilize the plenty of spectroscopy data from the MMT telescope to compare ICL properties with the star formation history of the brightest cluster galaxies (BCG), and discuss the ICL formation mechanism of the Coma cluster by comparing the distribution of cluster galaxies with the distribution of diffuse light inside the Coma cluster.

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The Development Process of Vehicle Roof Carrier using One Side Release System (측면 단동 릴리즈 시스템을 이용한 자동차용 루프 캐리어 개발 프로세스)

  • Jang, Dong-Hwan;Ko, Byung-Doo;Lee, In-Chul
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.5
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    • pp.56-62
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    • 2010
  • This paper presents the development process of roof carrier assembly using a one side release system for a vehicle. An RV(Recreational Vehicle) or SUV(Sports Utility Vehicle) has a roof carrier system on an upper surface of a roof panel for loading large or long size baggage. Such a roof carrier system is comprised of a roof rack longitudinally mounted on a roof panel and cross bar perpendicularly installed in the horizontal direction. Several locking mechanisms used in most vehicle roof carrier systems are composed with both side releasable locking ones. The obvious drawback to this arrangement is that when the user desires to reposition the cross bar, first one of the locking members must be unlocked and then the user must walk around to the opposite side of the vehicle to unlock the other member. In this paper, we proposed a newly locking mechanism, which allows a user simultaneously place both locking members of the roof carrier in locked and unlocked positions. In order to estimate design compatibility, structural and modal analysis is performed. Furthermore, a prototype based on the proposed design has been made, and then durability test carried out. From the simulation and experimental results, the proposed roof carrier system is proved effective and safe.

A Study of Home-furnishing Products Strategy through the Consumption Tendency Analysis of Single Household (1인 가구의 소비성향 분석을 통한 홈퍼니싱 제품전략 연구)

  • Kim, Taesun
    • Journal of the Korea Furniture Society
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    • v.27 no.3
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    • pp.237-245
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    • 2016
  • Single households currently account for 26.5% of all households and their number is expected to continue to rise, reaching 34.5% by 2035. An analysis of the consumption trends and needs of single households shows that they are rising as a new consumer group with a focus on investment on the individual and favouring: small but high-tech products: efficient use of limited resources: safety and peace of mind: self-improvement and leisure. Products which meet such demands are having an impact on the growth of home-furnishing market. An analysis of companies in Korea's home-furnishing market, with examples like the lifestyle company IKEA, shows a variety of brands such as SPA brand, furniture specialist, distributor and character products. And yet most are OEM products which lack differentiated product lines and compete with similar display and distribution structure. We needs the Single household consumption tendency of home-furnishing market and differentiation strategy through product analysis. In order to increase the value of companies in the home-furnishing market, in addition to differentiated design, product competitiveness must aspire to higher customer satisfaction with easy assembly, innovation in logistics, innovative sales methods such as virtual-reality simulation for products and space, individually-tailored furniture for the needs of single household and products which combine smart technology. For home-grown home-furnishing brands to have competitiveness, they must leverage on the strengths of the industry, offering differentiated and competitive products in a wider range of areas with convergence functions as well as differentiation in consumer interface and application of advancing technology; in-depth product research is called for.

Improvement and Application of Total Maximum Daily Load Management System of Korea: 2. Determination of Margin of Safety and Allocation of Pollutant Loads (우리나라 오염총량관리제도의 적용 및 개선: 2. 안전율 산정 및 삭감부하량 할당)

  • Kim, Kyung-Tae;Chung, Eun-Sung;Kim, Sang-Ug;Lee, Kil Seong
    • Journal of Korean Society on Water Environment
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    • v.26 no.1
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    • pp.168-176
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    • 2010
  • This study proposes the improvement of the present Total Maximum Daily Load (TMDL) management system of MOE (Ministry of Environment). The margin of safety (MOS) is calculated by a method using standard error and a method using variability and uncertainty. The allocation of pollutant loads are calculated using three methods, equal load reduction method, equal percent removal method and method using equity standards. This study applied the improved TMDL management system to the Anyangcheon watershed. Since MOS varies from 12% to 44% due to the high variability of measured and simulated data, it must not be ignored in the TMDL. The method using equity standards is the most proper in this application since the others produced unrealistic allocations. Area, runoff, water use quantity, population and budget are considered for equity standards. This study shows that this allocation method can be also applicable for the administrative units as well as the sub-watersheds. Finally, Hydrologic Simulation Program-FORTRAN (HSPF) with the allocated pollutant load was used to confirm whether it satisfy the water quality standard or not. This study will be helpful to improve the MOS and allocation system TMDL in the future.