• Title/Summary/Keyword: Looping

Search Result 131, Processing Time 0.022 seconds

Triangular Mesh Generation on Places or Surfaces by a New Looping Method (새로운 분할법에 의한 평면 및 곡면의 삼각형 요소망 자동생성)

  • 이민철;전만수;임우섭
    • Korean Journal of Computational Design and Engineering
    • /
    • v.4 no.2
    • /
    • pp.79-86
    • /
    • 1999
  • A general approach to automatic generation of triangular meshes on three-dimensional surfaces is presented in this paper. The approach, developed with emphasis on program generality and interface with CAD/CAM systems, is based on the double mapping method and the looping method. The double mapping method is introduced and anew splitting scheme is proposed for the looping method employed for triangular mesh generation on the parametric domain. Several application examples are given.

  • PDF

A Method For Preventing Data Looping in Multi Tactical Datalink Operation (다중 전술데이터링크 운용에 따른 데이터 루핑 방지 방안)

  • Woo, Soon;Lim, Jae-Sung
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.16 no.3
    • /
    • pp.314-321
    • /
    • 2013
  • In this paper, we have proposed a method which can prevent data looping in multi tactical data-link operating situation. Because the situation of multi tactical data-link in Korea would be more complex than ever before, data looping is more likely to be happened. To prevent data looping, forwarder has to manage TQ(Track Quality) in forwarded track message by degrading it to enlarge correlation gate. Forwarder also has to discard useless track message which can be determined by minimum TQ value. To decide optimal formula for forwarder to degrade TQ and to determine minimum TQ, a research about track motion, correlation, TQ managing, etc in real system is necessary.

The Low Height Looping Technology for Multi-chip Package in Wire Bonder (와이어 본더에서의 초저 루프 기술)

  • Kwak, Byung-Kil;Park, Young-Min;Kook, Sung-June
    • Journal of the Semiconductor & Display Technology
    • /
    • v.6 no.1 s.18
    • /
    • pp.17-22
    • /
    • 2007
  • Recent new packages such as MCP(Multi-Chip Package), QDP(Quadratic Die Package) and DDP(Dual Die Package) have stack type configuration. This kind of multi-layer package is thicker than single layer package. So there is need for the low height looping technology in wirebonder to make these packages thinner. There is stiff zone above ball in wirebonder wire which is called HAZ(Heat Affect Zone). When making low height loop (below $80\;{\mu}m$) with traditional forward loop, stiff wire in HAZ(Heat Affected Zone) above ball is bended and weakened. So the traditional forward looping method cannot be applied to low height loop. SSB(stand-off stitch) wire bonding method was applied to many packages which require very low loops. The drawback of SSB method is making frequent errors at making ball, neck damage above ball on lead and the weakness of ball bonding on lead. The alternative looping method is BNL(ball neckless) looping technology which is already applied to some package(DDP, QDP). The advantage of this method is faster in bonding process and making little errors in wire bonding compared with SSB method. This paper presents the result of BNL looping technology applied in assembly house and several issues related to low loop height consistence and BNL zone weakness.

  • PDF

Conceptual Design and Feasibility Study on 0.5 MWth Pressurized Chemical Looping Combustor (0.5 MWth 가압 케미컬루핑 연소기 개념설계 및 구현 가능성 조사)

  • RYU, HOJUNG;LEE, DONGHO;JANG, MYOUNGSOO;KIM, JUNGHWAN;BAEK, JEOM-IN
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.27 no.2
    • /
    • pp.201-210
    • /
    • 2016
  • To develop a pressurized chemical looping combustor, conceptual design of 0.5 MWth chemical looping combustor was performed by means of mass and energy balance calculations. Based on the conceptual design, reactivity of oxygen carrier and solid circulation rate were selected as key parameters. Sensitivity analysis of those key parameters were conducted with the change of oxygen carrier utilization percent from 5 to 50% and proper solid circulation rate and solid conversion rate to meet 98% of $CO_2$ selectivity were confirmed. Feasibility of 0.5 MWth pressurized chemical looping combustor was confirmed by experimental studies to find real solid circulation rate and $CO_2$ selectivity within the operating conditions based on the conceptual design. We could varied very wide range of solid circulation rate in two interconnected fluidized bed system. We also got enough $CO_2$ selectivity more than 98% in semi-continuous chemical looping combustor using OCN717 oxygen carrier. Consequently, feasibility of 0.5 MWth pressurized chemical looping combustor was confirmed.

Continuous Operation of $CO_2$/NOx-free 50kW Checmial-Looping Combustor ($CO_2$/NOx-free 50kW 매체순환식 가스연소기 산화-환원 연속반응 실증)

  • Ryu, Ho-Jung;Jin, Gyoung-Tae;Yi, Chang-Keun
    • 한국연소학회:학술대회논문집
    • /
    • 2004.06a
    • /
    • pp.227-234
    • /
    • 2004
  • For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion(CLC) may yield great advantages of savings of energy to $CO_2$ separation and suppressing the effect on environment. In chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. The purpose of this study is to demonstrate inherent $CO_2$ separation and no NOx emission and to confirm high $CO_2$ selectivity, no side reaction (i.e., carbon deposition, hydrogen generation) by continuous reduction and oxidation experiment in a 50kWtb chemical-looping combustor. NiO/bentonite particle was used as a bed material and $CH_4$ and air were used as reacting gases for reduction and oxidation respectively.

  • PDF

Performance Estimation and Process Selection for Chemical-Looping Hydrogen Generation System (금속매체 순환식 수소생산 시스템의 성능예측 및 공정선정)

  • Ryu, Ho-Jung;Jin, Gyoung-Tae
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.16 no.3
    • /
    • pp.209-218
    • /
    • 2005
  • To find a suitable metal component in oxygen carrier particles for chemical-looping hydrogen generation system(CLH), oxygen transfer capacities of metal components were compared and Ni has been selected as the best metal component. The proper operating conditions to achieve high hydrogen generation rate have been investigated based on the chemical-equilibrium composition analysis for water splitting reactor. Moreover, suitable compositions of syngas from gasifier of heavy residue to achieve high energy efficiency have been investigated by calculation of heat of reaction. Based on the selected operating conditions, the best configuration of two interconnected fluidized beds system for the chemical-looping hydrogen generator has been investigated as well.

A descriptive study of the impact of the causal looping method to the small group decision-making process of the Korean managers (인과 고리기법이 집단의사결정 과정에 미치는 행태적 연구)

  • 전기정
    • Korean System Dynamics Review
    • /
    • v.3 no.2
    • /
    • pp.69-91
    • /
    • 2002
  • This paper presents an analysis of the impact of the causal looping method to the Korean middle managers' decision-making processes. The sample included the observations of decisions made by 70 groups with 5 to 7 members each. The results showed that the causal looping method was a strong device to help Korean managers followed value-focused decision processes, as opposite to alternative-focuses ones. The lessons from this study suggest a direction for the development of the education method to improve group decision-making processes.

  • PDF

Packed Bed Methane Chemical-Looping Reforming System Modeling for the Application to the Hydrogen Production (수소 생성을 위한 고정상 메탄 매체 순환 개질 시스템 모델링)

  • HA, JONGJU;SONG, SOONHO
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.28 no.5
    • /
    • pp.453-458
    • /
    • 2017
  • A study on the modeling of the methane Chemical Looping Reforming system was carried out. It is aimed to predict the temperature and concentration behavior of the product through modeling of oxygen carrier fixed bed reactors composed of multiple stacks. In order to design the reaction system, first of all, the flow rate of the hydrogen to be produced was calculated. The flow rate ratio of the oxidation/reduction reactor was calculated considering the heat of reaction between adjacent reactors. Finally, in this paper, kinetic model including empirical coefficients was suggested.

A Looping Population Learning Algorithm for the Makespan/Resource Trade-offs Project Scheduling

  • Fang, Ying-Chieh;Chyu, Chiuh-Cheng
    • Industrial Engineering and Management Systems
    • /
    • v.8 no.3
    • /
    • pp.171-180
    • /
    • 2009
  • Population learning algorithm (PLA) is a population-based method that was inspired by the similarities to the phenomenon of social education process in which a diminishing number of individuals enter an increasing number of learning stages. The study aims to develop a framework that repeatedly applying the PLA to solve the discrete resource constrained project scheduling problem with two objectives: minimizing project makespan and renewable resource availability, which are two most common concerns of management when a project is being executed. The PLA looping framework will provide a number of near Pareto optimal schedules for the management to make a choice. Different improvement schemes and learning procedures are applied at different stages of the process. The process gradually becomes more and more sophisticated and time consuming as there are less and less individuals to be taught. An experiment with ProGen generated instances was conducted, and the results demonstrated that the looping framework using PLA outperforms those using genetic local search, particle swarm optimization with local search, scatter search, as well as biased sampling multi-pass algorithm, in terms of several performance measures of proximity. However, the diversity using spread metric does not reveal any significant difference between these five looping algorithms.

Natural Gas Combustion Characteristics of Mass Produced Oxygen Carrier Particles for Chemical-looping Combustor in a Batch Type Fluidized Bed Reactor (회분식 유동층 반응기에서 매체순환식 가스연소기용 대량생산 산소공여입자들의 천연가스 연소특성)

  • Ryu, Ho-Jung;Kim, Kyung-Su;Park, Yeong-Seong;Park, Moon-Hee
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.20 no.2
    • /
    • pp.151-160
    • /
    • 2009
  • Natural gas combustion characteristics of mass produced oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor. Five particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN703-950, OCN703-1100 were used as oxygen carrier particles. Natural gas and air were used as reactants for reduction and oxidation, respectively. During reduction reaction, high fuel conversion and high $CO_2$ selectivity were achieved for most of oxygen carriers. During oxidation, NO emission was very low. These results indicate that inherent $CO_2$ separation and low NOx combustion are feasible for the natural gas fueled chemical-looping combustion system. Among the five oxygen carriers, OCN703-1100 particle was selected as the best candidate for demonstration of long-term operation in large-scale chemical-looping combustor from the viewpoints of fuel conversion, $CO_2$ selectivity, $CH_4$ concentration, and CO concentration.