집계자료를 이용한 미시적 시뮬레이션 모형의 자동정산체계 개발 (도시고속도로사례)

이호상,이태경,마국준,김영찬,원제무 대한교통학회 2011 大韓交通學會誌 Vol.29 No.1

미시적 시뮬레이션 모형은 컴퓨터 성능이 향상되고 정교한 모형이 개발되면서 광역적인 범위까지 적용분야가 점차 확대되고 있다. 현장 교통상황을 정확하게 묘사하기 위해서는 시뮬레이션 모형의 정확한 정산이 매우 중요하다. 국내에서는 거시적 모형에 대한 정산연구는 많이 진행된 반면에 미시적 모형에 대한 정산연구는 매우 부족한 실정이다. 본 연구에서는 유전자알고리즘 이용하여 미시적 시뮬레이션 모형의 파라미터를 자동으로 최적화하는 자동정산체계를 제시하였다. 내부순환로 지점검지기에서 수집되는 관측교통량과 미시적 시뮬레이션모형(VISSIM)의 교통량간의 제곱오차(RMSE)를 성능지표로 하고, 최적화 목적함수는 제곱오차를 최소화 하는 것으로 설정하였다. 내부순환로에 적용한 결과, 기본 파라미터에 비해 자동정산체계의 RMSE가 60.4%(19.3→7.6)나 감소하여 매우 효과적인 것으로 나타났다. The application of micro-simulation model has been extended farther with improvement of computer performance and development of complicated model. To make a micro-simulation model accurately replicate field traffic conditions, model calibration is very crucial. Studies on calibration of micro-simulation model have not been enough while lots of studies on calibration of macro-simulation model have been continued in our country. This paper presents an auto-calibration of parameter values in micro-simulation model(VISSIM) using genetic algorithm. RMSE(Root Mean Square Error) of collected volume on the urban expressway versus simulated volume is set as MOP(measure of performance) and objective function of optimization is set as to minimize the RMSE. Applying to urban expressway(Nae-bu circular) as a case study, it shows that RMSE of optimized parameter values decrease 60.4%(19.3→7.6) compared to default parameter values and the proposed auto-calibration system is very effective.

Stata를 활용한 Sick-Sicker 모형 시뮬레이션: 고혈압과 당뇨를 중심으로

이성호,민인식 경희대학교 경영연구원 2023 의료경영학연구 Vol.17 No.3

This study develops a micro-simulation model in Stata, showcasing the potential of constructing such models using Korea Health Panel (KHP) data. Specifically, we reinterpret the micro-simulation model originally developed using R code based on the Sick-Sicker model by Krijkamp et al.(2018) in the Stata environment. Using data from the KHP, simulation results for cohorts aged 60 to 69 focused on diabetes and hypertension were derived. The findings suggest: First, the proportion of individuals without chronic diseases (specifically, diabetes and hypertension) diminishes over time, with 38% of the cohort projected to succumb within 30 years. Second, utility was observed to be higher in an extended model incorporating the treatment process than in a baseline model excluding it. Third, effective governmental health and medical policies could amplify patient utility while concurrently decreasing the medical service burden. This research is pivotal in demonstrating the feasibility of creating and employing micro-simulation models using Stata. Furthermore, the study provides specific Stata codes for such models, which can serve as a foundation for future research and policy development. It is hoped that the findings will spur broader discussions, facilitating the creation of intricate micro-simulations tailored for devising impactful healthcare policies.

A novel transient thermohydraulic model of micro-channel heat sink

Jung, Eui Guk,Boo, Joon Hong Pergamon Press 2019 International journal of heat and mass transfer Vol. No.

<P><B>Abstract</B></P> <P>The purpose of this work is to develop an analytical model for prediction of the thermal fluid performance of a micro-channel heat sink by applying liquid thin-film theory. For this purpose, a one-dimensional transient model has been developed for a single channel of micro-channel heat sink and a series of numerical simulation was performed for various operating conditions. Mass, momentum and energy equations were applied separately for the vapor and liquid phases to predict more effective physical performance of the transient behavior. As a result, the axial distributions of mass flow, pressure, and temperature for the working fluid were obtained for vapor and liquid in the micro-channel. In particular, the phase change interface profile with the liquid thin-film was obtained using an augmented Young Laplace equation. Consequently, the interface areas of heat and mass transfer occupied by the liquid and vapor were predicted and incorporated into the governing equations of each phase. The analytical model was validated by comparison of its numerical solutions with experimental results. The discrepancy between the experimental and numerical results for the axial wall temperature was less than 4 °C, and that for the transient time to reach a steady-state wall temperature was within 1 sec. Through a series of performance simulations for a micro-channel model with pure water as the working fluid, transient response of the wall temperature, liquid film thickness, mass flow rate, liquid pressure, and vapor and liquid temperatures were investigated. The model developed in this study might be utilized for more refined performance prediction of a micro-channel heat sink.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel transient thermal numerical model is presented for a single micro-channel heat sink. </LI> <LI> Governing equations for the transient were derived under liquid thin-film evaporation. </LI> <LI> Predicted performance variables were analyzed during the whole transient process. </LI> <LI> The model was validate by experimental results in the literature. </LI> <LI> Influence of the input variables on the transient simulation was investigated. </LI> </UL> </P>

미시모의실험모형을 이용한 장래 건강보험 진료비 추정

황인욱,이윤경,임유나,이태진 한국보건경제정책학회 2023 보건경제와 정책연구 Vol.29 No.2

In Korea, the National Health Insurance (NHI) expenditure is expected to rapidly increase due to population ageing and the government’s policy of expanding the health insurance coverage, as estimated in previous studies using component-based or macro models. Compared to such models, the micro-simulation model has advantages in reflecting dynamic changes in individual-level determinants of medical care cost, population structure, and policy effect on individual behaviors. In this study, we designed a micro-simulation model for estimating the National Health Insurance medical care cost between 2019 and 2065 and produced detailed projection results using the Korean Health Panel Survey data. Our results suggested that total NHI medical care cost increased to 150 trillion Korean Won (KRW) in 2065, of which 2/3 was cost incurred by older adults aged 65 and over. Once we incorporated effect of the health insurance coverage expansion policy, the total NHI medical cost in 2065 increased to 206 trillion KRW. Additionally, projected medical care cost in 2060 approximately corresponded to 6% of projected GDP in Korea. We also showed that our results are subject to the key components of the model, including the period for parameter estimation, population projection scenarios, the presumed relationship between changes in health insurance coverage and changes in individual medical cost, by suggesting that the NHI medical care cost increased to 16% of the projected GDP if we change the parameter estimation period and the assumption on insurance coverage-medical care cost relationship.

Comparison of Micro- and Macro-Characteristics of Vehicular Mobility Models

Dan Shao,Guangmin Liang,Shaoqiang Wang 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.6

Simulation methodology is preferred approach to test vehicular networking protocols and to perform overhead analysis compared to high affordability and inconvenience of the real testbed. The confidence of simulation results is greatly dependent on the adoptive mobility model, i.e. whether or not the vehicular mobility modeling could reproduce the real vehicle moving pattern and could capture the intrinsic spatial as well as temporal relationships among vehicles. From the perspective of macro- and micro-scale, this paper proposes a series of statistical characteristics to assess whether the existing mobility models reflect a regular pattern. Micro-characteristics cover individual statistics, including driving duration time, driving distance, parking duration time, and link holding time. Simulations show that diverse mobility models share similar micro-characteristics in the complementary cumulative distribution function, but still display innegligible differences in distribution curves. Macro-characteristics refer to overall correlations, such as average velocity, total driving distance, total driving time, average neighbors' degree, and average accelerating time. Results show that the investigated mobility models behave with similar phase transition, but with different critical transition points. Marco-statistics follow Poisson distribution, but with completely different average values. The work is expected to help researchers better understand simulations and design context-aware vehicular algorithms.

소형 공작기계의 이송계 시뮬레이션을 이용한 마이크로 엔드밀링의 절삭 공정 시뮬레이션

이한울(H.U.Lee),정영훈(Y.H.Jeong),조동우(D.W.Cho),박종권(J.K.Park) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-

In order to predict the cutting forces in general micro-end-milling operated by NC code, a cutting process simulation model was conducted. This model computes the cutting configurations using a geometric simulation based on ME Z-map and predict the cutting force using a mechanistic cutting force model that can precisely predict the cutting force in micro-end-milling under various cutting conditions. In order to eliminate a serious difference between an actual machine tool behavior and an ideal behavior commanded by NC code, a feed drive simulation was introduced. The comparison of the predicted and measured cutting forces in micro-packet-milling showed that the proposed method provides very accurate results.

소형 공작기계의 이송계 시뮬레이션을 이용한 마이크로 엔드밀링의 절삭 공정 시뮬레이션

이한울,정영훈,조동우,박종권 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-

In order to predict the cutting forces in general micro-end-milling operated by NC code, a cutting process simulation model was conducted. This model computes the cutting configurations using a geometric simulation based on ME Z-map and predict the cutting force using a mechanistic cutting force model that can precisely predict the cutting force in micro-end-milling under various cutting conditions. In order to eliminate a serious difference between an actual machine tool behavior and an ideal behavior commanded by NC code, a feed drive simulation was introduced. The comparison of the predicted and measured cutting forces in micro-packet-milling showed that the proposed method provides very accurate results.

Simulation of non-steady state oxygen transfer caused by microbubble supply

Jaiyeop Lee,Ilho Kim 대한상하수도학회 2018 상하수도학회지 Vol.32 No.5

Microbubbles oxygen transfer to water was simulated based on experimental results obtained from the bubbles generation operated under varying liquid supply velocity to the multi-step orifices of the generator. It had been known that liquid supply velocity and bubble size are inversely related. In the oxygen transfer, a non-steady state was assumed and the pseudo stagnation caused the slow movement of bubbles from the bottom to the water surface. Two parameters were considered for the simulation: They represent a factor to correct the pseudo stagnation state and a scale which represented the amount of bubbles in supply versus time. The sum of absolute error determined by fitting regression to the experimental results was comparable to that of the American Society of Civil Engineers (ASCE) model, which is based on concentration differential as the driving force. Hence, considering the bubbles formation factors, the simulation process has the potential to be easily used for applications by introducing two parameters in the assumptions. Compared with the ASCE model, the simulation method reproduced the experimental results well by detailed conditions.

Effects of Battery Model on the Accuracy of Battery SOC Estimation Using Extended Kalman Filter under Practical Vehicle Conditions Including Parasitic Current Leakage and Diffusion Of Voltage

오현종,전지환,박성진 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.5

Accurate estimation of battery State of Charge (SOC) is a crucial factor for the safe and efficient usage of the batteries in hybrid electric vehicles. The combined method of Coulomb counting and Open circuit Voltage (OCV) is already under practical usage for the estimation of battery SOC, but the methods have significant error when there is parasitic current leakage (dark current) or short rest period. Thus, Extended Kalman Filter (EKF) is one of the battery SOC estimation methods used to overcome such drawbacks. And, most importantly, due to structural dependency of EKF upon battery model, the battery model used for the EKF contributes significantly to the accuracy of EKF. Thus, in this paper, 3 types of battery Equivalent Circuit Models (ECMs) including second order RC model, first order RC model, and R model are compared under practical vehicle driving conditions. To simulate the vehicle driving condition, a micro Hybrid Electric Vehicle (micro-HEV) is modeled and simulation is conducted under NEDC condition.

2007년 공적 연금 개혁의 적정성 전망과 평가 -Dynamic Micro-Simulation을 통한 장기 분석-

권혁진 ( Hyuk Jin Kwon ),신우진 ( Woo Jin Shin ),한재명 ( Jae Myung Han ),정동진 ( Dong Jin Jung ),류재린 ( Jae Rin Ryu ),박충렬 ( Chung Ryeol Park ),김균 ( Kyun Kim ) 한국사회보장학회 2013 사회보장연구 Vol.29 No.4

본 연구에서는 한국의 경제·사회에 대한 미시 모의실험 모형인 MMESP(Micro-simulation Model for Economic and Social Policy in Korea, version 1.0)를 개발하고, 이를 이용하여 2007년 연금 개혁의 핵심 내용인 소득대체율의 점진적 인하에 따른 정책 효과를 분석하였다. 그 결과, 일차적으로 소득대체율의 인하가 연금의 지속가능성은 향상시키지만, 적정성을 축소시키는 것을 구체적으로 확인하였다. 동시에 그 영향이 세대와 소득수준에 따라 어떻게 나타나는지를 검토한 결과, 소득대체율은 저소득계층일수록 상대적으로 더 크게 하락할 것으로 전망되었다. 또한 공적 연금이 노인 빈곤에 미치는 영향은 지속적으로 커질 것이며, 동 개혁으로 인해 세대 간 재분배 효과는 축소될 것으로 보인다. 마지막으로 저소득계층 일수록, 그리고 후세대일수록 2007년 개혁에 따른 부담은 상대적으로 더 큰것으로 평가된다. This study developed a micro-simulation model, MMESP (Micro-simulation Model for Economic and Social Policy in Korea, ver. 1.0) to project long term policy effects of the gradual reduction of income replacement rates which was a core measure of the 2007 National Pension System reform. As it was expected, we found that although the income replacement rate reduction improves the sustainability of the public pension fund, it also deteriorates the adequacy of the pension. We also found that this reform has relatively bad effects to low income classes, i.e, making them worse off; that elder generation`s poverty problem becomes worse than before; that redistribution effects of public pension in/between generations become worse, compared to the without-reform case; and that burdens both of low income classes and late-comer generations are expected to be heavier than before.