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Acrosswind aeroelastic response of square tall buildings: a semi-analytical approach based of wind tunnel tests on rigid models

  • Venanzi, I.;Materazzi, A.L.
    • Wind and Structures
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    • v.15 no.6
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    • pp.495-508
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    • 2012
  • The present paper is focused on the prediction of the acrosswind aeroelastic response of square tall buildings. In particular, a semi-analytical procedure is proposed based on the assumption that square tall buildings, for reduced velocities corresponding to operational conditions, do not experience vortex shedding resonance or galloping and fall in the range of positive aerodynamic damping. Under these conditions, aeroelastic wind tunnel tests can be unnecessary and the response can be correctly evaluated using wind tunnel tests on rigid models and analytical modeling of the aerodynamic damping. The proposed procedure consists of two phases. First, simultaneous measurements of the pressure time histories are carried out in the wind tunnel on rigid models, in order to obtain the aerodynamic forces. Then, aeroelastic forces are analytically evaluated and the structural response is computed through direct integration of the equations of motion considering the contribution of both the aerodynamic and aeroelastic forces. The procedure, which gives a conservative estimate of the aeroelastic response, has the advantage that aeroelastic tests are avoided, at least in the preliminary design phase.

Adaptive Exponential Smoothing Method Based on Structural Change Statistics (구조변화 통계량을 이용한 적응적 지수평활법)

  • Kim, Jeong-Il;Park, Dae-Geun;Jeon, Deok-Bin;Cha, Gyeong-Cheon
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2006.11a
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    • pp.165-168
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    • 2006
  • Exponential smoothing methods do not adapt well to unexpected changes in underlying process. Over the past few decades a number of adaptive smoothing models have been proposed which allow for the continuous adjustment of the smoothing constant value in order to provide a much earlier detection of unexpected changes. However, most of previous studies presented ad hoc procedure of adaptive forecasting without any theoretical background. In this paper, we propose a detection-adaptation procedure applied to simple and Holt's linear method. We derive level and slope change detection statistics based on Bayesian statistical theory and present distribution of the statistics by simulation method. The proposed procedure is compared with previous adaptive forecasting models using simulated data and economic time series data.

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A performance based strategy for design of steel moment frames under blast loading

  • Ashkezari, Ghasem Dehghani
    • Earthquakes and Structures
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    • v.15 no.2
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    • pp.155-164
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    • 2018
  • Design of structures subjected to blast loads are usually carried out through nonlinear inelastic dynamic analysis followed by imposing acceptance criteria specified in design codes. In addition to comprehensive aspects of inelastic dynamic analyses, particularly in analysis and design of structures subjected to transient loads, they inherently suffer from convergence and computational cost problems. In this research, a strategy is proposed for design of steel moment resisting frames under far range blast loads. This strategy is inspired from performance based seismic design concepts, which is here developed to blast design. For this purpose, an algorithm is presented to calculate the capacity modification factors of frame members in order to simplify design of these structures subjected to blast loading. The present method provides a simplified design procedure in which the linear dynamic analysis is preformed, instead of the time-consuming nonlinear dynamic analysis. Nonlinear and linear analyses are accomplished in order to establish this design procedure, and consequently the final design procedure is proposed as a strategy requiring only linear structural analysis, while acceptance criteria of nonlinear analysis is implicitly satisfied.

A Comparative Analysis of Costs in Arbitration between Korea and ICC (한국과 ICC 간 중재비용에 관한 비교 분석)

  • Ha, Choong Lyong
    • Journal of Arbitration Studies
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    • v.10 no.1
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    • pp.26-46
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    • 2000
  • International arbitration has been recognized as an effective dispute resolution method. Among the arbitration institutions, the ICC(International Chamber of Commerce) international court of arbitration is one of the most well-known and frequently chosen organizations to which international claimants have resorted, when they were confronted with international disputes. In this paper, costs in the ICC arbitration are compared with those in the KCAB(Korean Commercial Arbitration Board) arbitration. seeking efficient ways to reduce the costs while maximizing the quality of arbitral awards. Three main points about costs in the ICC arbitration and the KCAB arbitration are discussed and analysed, First, the cost structures are analysed and decomposed into manageable units. Second, the cost allocation is discussed to clarify its proportional responsibility among the arbitration parties. Third, how advances in arbitration costs are conducted is examined to explore a well established procedure of arbitration. In conclusion, the KCAB arbitration procedure has been found faster and cheaper than the ICC arbitration procedure in terms of time and costs, respectively. However, it can be cautiously suggested that the quality of arbitral awards made by the KCAB is not necessarily higher than that made by the ICC.

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IMPROVED EARTHQUAKE RESISTANT DESIGN OF MULTISTORY BUILDING FRAMES (고층건물 내진설계기법의 개선)

  • Lee, Dong-Guen-;Lee, Seok-Youn-
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1991.04a
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    • pp.72-78
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    • 1991
  • An improved procedure for earthquake resistant design of multistory building structures is proposed in this study. The effect of gravity load on seismic response of structures is evaluated through nonlinear dynamic analyses of a single story example structure. The presence of gravity load tends to initiate plastic hinge formation in earlier stage of a strong earthquake. However, the effect of gravity load seems to disapper as ground motion is getting stronger. And one of shortcomings in current earthquake resistant codes is overestimation of gravity load effects when earthquake load is applied at the same time so that it may leads to less inelastic deformation or structural damage in upper stories, and inelastic deformation is increased in lower stories. Based on these observation, an improved procedure for earthquake resistant design is derived by reducing the factor for gravity load and inceasing that for seismic load. Structures designed by the proposed design procedure turned out to have increased safety and stability against strong earthquakes.

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Quality Characteristics of Brown Rice Flakes Subjected to Various Flaking and Toasting Method (제조조건에 따른 압착형 현미 Flake의 품질특성)

  • 이연리;최영희;강미영
    • Journal of the East Asian Society of Dietary Life
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    • v.11 no.2
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    • pp.131-139
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    • 2001
  • The physicochemical and sensory characteristics of brown rice flakes by different processing conditions such as flaking Process and their heat treatments were investigated to establish the brown rice flake processing procedure. To successfully make the compressed rice grain type flakes, the most appropriate water steeping conditions were 5 hours at 60'C. The brown rice flakes by compressed flaking procedure and heat treatment with microwave toasting showed the best crispiness-texture that tested from textrometer or sensory evaluation, and there was no significant difference between the source of rice varieties. The water absorption index(WAI) of tested flakes were negatively correlated with the water soluble index( WSI) and positively correlated with bowl life. The flakes made by compressed flaking procedure and heat treatment with microwave toasting showed longer bowl life, which is the length of the time that the cereal can retain its crispness after being soaked in milk.

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A Study on Production Scheduling with respect to the possibility of the connection between machines (공작기계간 연결작업을 고려한 일정계획 수립에 관한 연구)

  • 김동희;김봉선
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.17 no.32
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    • pp.105-112
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    • 1994
  • The purpose of this paper is to develope a heuristic algorithm to maximize reduction rate of the processing time by the connection of neighbored machines. A method to calculate the start-lag and stop-lag for the overlapping production is proposed and applied. The heuristic procedure of this paper has 3 steps. In the first and second step, the job oriented procedure is applied. In the final step, the operation oriented procedure is applied. In order to evaluate the performance of this algorithm, three kinds of performance measures are selected and randomly generated problems are tested.

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QRS detection based on maximum a-posteriori estimation (MAP Estimation을 이용한 QRS Detection)

  • 정희교;신건수;이명호
    • 제어로봇시스템학회:학술대회논문집
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    • 1987.10b
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    • pp.709-712
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    • 1987
  • In this paper, a mathematical model for the purpose of QRS detection is considered in the case of the occurrence of nonoverlapping pulse-shaped waveforms corrupted with white noise. The number of waveforms, the arrival times, amplitudes, and widths of QRS complexes are regarded as random variables. The joint MAP estimation of all the unknown quantities consists of linear filtering followed by an optimization procedure. Because of time-consuming, the optimization procedure is modified so that a threshold test is obtained. The model formulation with nonoverlapping waveforms leads to a standard procedure covering a segment before as well as after an accepted event. Adaptivity of the detector is gained by utilizing past signal properties in determining threshold for QRS detection.

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An Order Releasing Algorithm for a Semiconductor Wafer Manufacturer (주문형반도체 제조회사의 작업하달 논리의 개발)

  • Kim, Ki-Young;Kang, Chang-Ho;Kim, Kap-Hwan
    • IE interfaces
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    • v.19 no.2
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    • pp.97-105
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    • 2006
  • In this paper, based on the process analysis of a semiconductor company, a lot order release procedure (input regulation) is developed for a semiconductor company. The major characteristic of the order release procedure in this paper is to consider the workloads of machines which are obtained from a virtual lot flows by the dispatching rule at machines in the shop of the semiconductor company. The objective is to minimize the cycle time and to obtain other good performances. A simulation is performed in order to evaluate the order release procedure in this paper.

DEVELOPMENT OF AN ACCELERATED LIFE TEST PROCEDURE FOR COOLING FAN MOTORS

  • Shin, W.G.;Lee, S.H.;Song, Y.S.
    • International Journal of Automotive Technology
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    • v.7 no.6
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    • pp.757-762
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    • 2006
  • Reliability of automotive parts has been one of the most interesting fields in the automotive industry. Especially, a small DC motor was issued because of the increasing adoption for passengers' safety and convenience. For several years, small DC motors have been studied and some problems of a life test method were found out. The field condition was not considered enough in the old life test method. It also needed a lot of test time. For precise life estimation and accelerated life test, new life test procedure was developed based on measured field condition. The vibration condition on vehicle and latent force on fan motor shaft were measured and correlated with each other. We converted the acceleration data into the load data and calculated the equivalent load from integrated value. We found the relationship which can be used for accelerated life test without changing the severity by using different loading factors.