• Title/Summary/Keyword: Simultaneous Model

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System identification of a building structure using wireless MEMS and PZT sensors

  • Kim, Hongjin;Kim, Whajung;Kim, Boung-Yong;Hwang, Jae-Seung
    • Structural Engineering and Mechanics
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    • v.30 no.2
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    • pp.191-209
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    • 2008
  • A structural monitoring system based on cheap and wireless monitoring system is investigated in this paper. Due to low-cost and low power consumption, micro-electro-mechanical system (MEMS) is suitable for wireless monitoring and the use of MEMS and wireless communication can reduce system cost and simplify the installation for structural health monitoring. For system identification using wireless MEMS, a finite element (FE) model updating method through correlation with the initial analytical model of the structure to the measured one is used. The system identification using wireless MEMS is evaluated experimentally using a three storey frame model. Identification results are compared to ones using data measured from traditional accelerometers and results indicate that the system identification using wireless MEMS estimates system parameters with reasonable accuracy. Another smart sensor considered in this paper for structural health monitoring is Lead Zirconate Titanate (PZT) which is a type of piezoelectric material. PZT patches have been applied for the health monitoring of structures owing to their simultaneous sensing/actuating capability. In this paper, the system identification for building structures by using PZT patches functioning as sensor only is presented. The FE model updating method is applied with the experimental data obtained using PZT patches, and the results are compared to ones obtained using wireless MEMS system. Results indicate that sensing by PZT patches yields reliable system identification results even though limited information is available.

Do Long Term Savings Motives Foster Household Participation and Contribution to Savings Mechanisms in Rural Vietnam?

  • HA, Van Dung
    • The Journal of Asian Finance, Economics and Business
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    • v.6 no.2
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    • pp.75-82
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    • 2019
  • The paper aims to investigate the impacts of long-term savings motives on fostering household participation and contribution to savings mechanisms in rural Vietnam. The paper is organized in five parts: introduction, data description, methodology, empirical results, and conclusion. The quantitative methodology is employed and three simultaneous estimation methods, including instrumental variable model, two-step model, and Heckman model are used to test these impacts as well as the robustness of results. In each model, the paper examines the impacts of independent factors on both household participation and household contribution to savings mechanisms. Two sets of independent variables: long-term savings motives (profit-making investment, accumulation for big expenditure, providing for old age, and cost of educations) and control variables (dependency rate, number of people in household, and household wealth) are in each model. A set of dataset of 2,314 households for analysis is obtained from household survey in rural Vietnam. Robust statistical findings indicate that profit-making investment emerged to be the strongest motive fostering household participation to savings mechanisms while other long-term savings motives have little or no impact on fostering household participation to savings mechanisms. In addition, education investment encourages household contribution to savings mechanisms in rural Vietnam.

A study on Stage-Based Flow Graph Model for Expressing Cyber Attack Train Scenarios (사이버 공격 훈련 시나리오 표현을 위한 Stage 기반 플로우 그래프 모델 연구)

  • Kim, Moon-Sun;Lee, Man-Hee
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.31 no.5
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    • pp.1021-1030
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    • 2021
  • This paper proposes S-CAFG(Stage-based Cyber Attack Flow Graph), a model for effectively describing training scenarios that simulate modern complex cyber attacks. On top of existing graph and tree models, we add a stage node to model more complex scenarios. In order to evaluate the proposed model, we create a complicated scenario and compare how the previous models and S-CAFG express the scenario. As a result, we confirm that S-CAFG can effectively describe various attack scenarios such as simultaneous attacks, additional attacks, and bypass path selection.

Comparative Analysis of Import Substitution Relations of Frozen Squid Demand -Focused on The Rotterdam Model and The Almost Ideal Demand System- (냉동 오징어 수요의 수입대체관계 비교 분석 -로테르담모형과 준이상수요체계를 중심으로-)

  • Woo, Kyeong-Won;Shin, Yong-Min
    • The Journal of Fisheries Business Administration
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    • v.53 no.1
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    • pp.55-72
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    • 2022
  • The domestic catch of squid is decreasing every year. Import volume is increasing to replace these domestic products. Import volume is expected to increase in the future, so it is necessary to study import substitution. Therefore, in this study, after selecting frozen squid, which accounts for the majority of imported squid, as the target fish species, China, Chile and Peru, which account for the majority of frozen squid imports, will be selected as the target countries for analysis. Then, the demand function of squid is estimated using the Rotterdam model, the inverse Rotterdam model, AIDS and inverse AIDS, which are the simultaneous equation demand types, and then elasticity is derived. After that, these models are compared in terms of significance, theoretical fit and practical fit.

Impact of economic integration between South and North Korea on the agricultural market

  • Sukho Han;Yongho Choi;Byung Min Soon
    • Korean Journal of Agricultural Science
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    • v.49 no.1
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    • pp.77-91
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    • 2022
  • North-South Korea economic integration is progressing slowly given the sensitive responses to changes in internal and external conditions. Nevertheless, advanced discussions focusing on North-South Korean economic cooperation should continue. Given this background, various studies of the economic effects of economic integration between North and South Korea have been conducted, but research on agricultural issues has been limited. The purpose of this study is to analyze the impact of the economic integration of South and North Korea on the agricultural market. In this study, a simultaneous equation model was constructed using a growth model. Solow's growth accounting approach is used to construct a model for estimating the macroeconomic effect of North-South economic integration. Also, the construction of growth accounting formulas subdivided into South and North Korea as well as agriculture and non-agricultural fields during the construction of the growth model is a major research achievement and differentiates it from previous studies. It is expected that the results of this study will serve as basic information for preparing policy measures to promote integration. However, there are many limitations when estimating the economic effects of North-South agricultural integration and obtaining policy implications given the insufficient available statistical data on agriculture in North Korea and the lack of related studies in the agricultural field. Therefore, it should be noted that there is an inherent problem in that the analysis results vary greatly depending on the assumptions set, as there is inevitably no choice but to rely on many and strong assumptions.

The Analysis of the Road Freight Transportation using the Simultaneous Demand-Supply Model (수요-공급의 동시모형을 통한 공로 화물운송특성분석)

  • 장수은;이용택;지준호
    • Journal of Korean Society of Transportation
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    • v.19 no.4
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    • pp.7-18
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    • 2001
  • This study represents a first attempt in Korea to develop the simultaneous freight supply-demand model which considers the relationship between freight supply and demand. As the existing study was limited in one area, or the supply and the demand was separated and assumed not to affect each other, this study take it into consideration the fact that the demand affects supply and simultaneously vice versa. This approach allows us to diagnose a policy carried on and helps us to make a resonable alternative for the effectiveness of freight transportation system. To find a relationship between them, we use a method of econometrics. a structural equation theory and two stage least-squares(2SLS) estimation technique, to get rid of bias which involves two successive applications of OLS. Based on the domestic freight data, this study consider as explanatory variables a number of population(P), industry(IN), the amount of production of the mining and manufacturing industries(MMI), the rate of the effectiveness of freight capacity(LE) and the distance of an empty carriage operation(VC). This study describes well the simultaneous process of freight supply-demand system in that the increase of VC from the decrease of VC raises the cargo capacity and cargo capacity also augments VC. By the way. it is analyzed that the increment of VC due to the increase of the cargo capacity is larger than the reduction of VC owing to the increase of the quantify of goods. Therefore an alternative policy is needed in a short and long run point of view. That is to say, to promote the effectiveness of the freight transportation system, a short term supply control and a long run logistic infrastructure are urgent based on the restoration of market economy by successive deregulation. So we are able to conclude that gradual deregulation is more desirable to build effective freight market.

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Effect of Bidding Strategies of Hydro Generation on an Electricity Market (수력발전기의 경쟁적 입찰전략이 전력시장에 미치는 영향)

  • Lee Kwang-Ho
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.9
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    • pp.461-466
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    • 2005
  • This paper addresses the bidding strategies of a hydro generator in an electricity market, and their effect on the electricity market in accordance with some parameters: the water volume, the demand elasticity, and the hydro unit performance. The competition of a hydro generator is formulated as a hi-level optimization problem, and the solving scheme for the equilibrium condition is proposed as a set of nonlinear simultaneous equations. The equilibrium of the oligopolistic model is evaluated by comparison with that of a perfect competition model from the viewpoint of a market power. Simulation results show some parameters have an influence on the market power of an electricity market including a hydro generator.

Bayesian Methods for Wavelet Series in Single-Index Models

  • Park, Chun-Gun;Vannucci, Marina;Hart, Jeffrey D.
    • 한국데이터정보과학회:학술대회논문집
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    • 2005.04a
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    • pp.83-126
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    • 2005
  • Single-index models have found applications in econometrics and biometrics, where multidimensional regression models are often encountered. Here we propose a nonparametric estimation approach that combines wavelet methods for non-equispaced designs with Bayesian models. We consider a wavelet series expansion of the unknown regression function and set prior distributions for the wavelet coefficients and the other model parameters. To ensure model identifiability, the direction parameter is represented via its polar coordinates. We employ ad hoc hierarchical mixture priors that perform shrinkage on wavelet coefficients and use Markov chain Monte Carlo methods for a posteriori inference. We investigate an independence-type Metropolis-Hastings algorithm to produce samples for the direction parameter. Our method leads to simultaneous estimates of the link function and of the index parameters. We present results on both simulated and real data, where we look at comparisons with other methods.

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A Study on Ventilation Characteristics of Cargo-oil pump room (화물유 펌프실의 환기특성에 관한 연구)

  • 박찬수;조대환
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.1
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    • pp.134-141
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    • 2000
  • In this study, a scaled model chamber was built to investigate ventilation characteristics of the Under floor Air-conditioning System. Experimental study was performed in model for cargo-oil pump room with inlet and outlet by visualization equipment with laser apparatus. Instant simultaneous velocity vectors at whole field were measured by 2-D PIV system(CACTUS'2000) which adopted two-frame grey-level cross correlation algorithm. The flow pattern reveals the large scale counterclockwise forced-vortex rotation from upside louver to lower scupper toward diagonal corner and also found small eddies at bottom layer

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Kinetic Study of the Lipase-Catalyzed Interesterification of Triolein and Stearic Acid in Nonpolar Media

  • Chi, Young-Min
    • BMB Reports
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    • v.30 no.1
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    • pp.7-12
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    • 1997
  • The kinetics of the interesterification of triolein and stearic acid catalyzed by immobilized Rhizopus delemar lipase were studied in a batch operation. In order to clarify the mechanisms of this reaction, three models are discussed under various conditions in terms of the ratio of triolein and stearic acid. The rate constants involved in the proposed model were determined by combining the numerical Gauss-elemination method, and the trial-and-error method so as to fit the calculated results with the experimental data. The accuracy of the obtained rate constants was confirmed after they were substituted for simultaneous differential equations and the equations simulated using an adaptive step-size Runge-Kutta method. Finally, the model which agrees with the calculated results and the experimental data was selected.

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