Earticle

현대의 초고층 및 대규모 복합건축물은 복잡한 내부 기하구조를 가진다. 이러한 구조는 화재 발생 시 열과 연기가 빠르게 확산되도록 한다. 계단실은 뚜렷한 굴뚝효과로 인해 특히 취약한 공간이다. 굴뚝효과 는 연기의 상향 이동을 가속화하여 수직 피난 경로의 안전성을 저해한다. 다수의 화재 사례에서 계단실 연기 침투는 피난 실패의 주요 원인으로 지적되고 있다. 화재 및 연기 위험을 분석하기 위해 Fire Dynamics Simulator(FDS)가 널리 활용되고 있다. FDS는 대와류모사(LES) 기법을 적용하여 열과 연기 거동을 정밀 하게 모사한다. 그러나 텍스트 기반 입력 구조로 인해 좌표와 구성요소를 수작업으로 정의해야 한다. 이로 인해 입력 오류가 빈번히 발생하며 모델링 신뢰성과 효율성이 저하된다. 본 연구는 FDS를 위한 GUI 기반 자동 입력 생성 시스템을 제안한다. 검증 결과, 주요 변수의 편차는 ±3% 이내였으며 입력 준비 시간은 약 72% 감소하였다.

Modern high-rise and large-scale mixed-use buildings have complex internal geometries. These geometries enable rapid spread of heat and smoke during fire events. Stairwells are particularly vulnerable due to the pronounced stack effect. This effect accelerates upward smoke movement and compromises vertical evacuation routes. Numerous fire incidents identify stairwell smoke infiltration as a major cause of evacuation failure. Fire Dynamics Simulator (FDS) is widely used to analyze these fire and smoke risks. FDS applies a LES-based approach to model heat and smoke transport accurately. However, its text-based input structure requires manual coordinate and component definition. This often leads to input errors and reduced modeling reliability and efficiency. This study proposes a GUI-based automatic input generation system for FDS. Validation showed deviations within ±3% and a 72% reduction in input preparation time.

In semiconductor manufacturing, the design of devices and the selection of optimal materials are traditionally time-consuming and costly process. To address these challenges, machine learning techniques are being explored to improve simulation speed and efficiency without compromising accuracy. This study aims to optimize semiconductor manufacturing by identifying the optimal material based on slit design structure and transmittance. Traditionally, inverse design methods focused on developing slit designs from transmittance, requiring significant time and financial resources for material validation through simulations. We propose a multi-modal algorithm that combines slit design images and transmittance to predict optimal material. Additionally, we introduce a convolutional neural network that predicts transmittance from slit design image and materials. Our approach introduces a model that identifies optimal materials directly from transmittance and design structure, enhancing efficiency. This advancement allows for effective prediction and analysis of material properties in semiconductor devices through domain transformation.

Advanced Air Mobility (AAM) systems require efficient ground infrastructures to support high-frequency operations, where battery swapping stations play a critical role. In such environments, energy supply stability significantly affects system performance, particularly under time-varying demand. This study analyzes the impact of different energy supply configurations on battery swapping station performance using a simulation-based approach. Three configurations are considered: external power grid, distributed energy resources (DER), and integrated DER with energy storage systems (ESS). Key performance metrics include average waiting time, system staying time, task completion rate, and battery availability. The results show that grid-based systems experience increased delays under peak demand, while DER-only configurations improve some performance indicators, but their effectiveness remains limited under highly time varying demand due to supply variability. In contrast, the integration of DER and ESS achieves the most stable performance by mitigating energy fluctuations. These findings indicate that the temporal adaptability of energy supply is a critical factor in determining operational performance, highlighting the importance of integrating energy storage systems in AAM infrastructure design.

본 연구에서는 RUSLE기법을 이용하여 경사지 밭 우회수로 저감효과 분석을 위한 모의기법을 제시하고, 태풍 매미가 영향을 주었던 2003년간 임하호 유역을 대상으로 토양유실 유발 경사지 밭에서의 우회수로 설치시 저감효과를 분석하였으며 적용모델은 SATEEC로 하였다. 우회수로는 상류지역으로부터의 유출수를 우회시켜 토양유실량을 저감시키는 기법으로 우회수로를 모의하기 위해서 우회수로 설치 대상 경사지 밭만 DEM을 클리핑하여 상류지역의 흐름누적면적을 제거한 후 지형 인자(LS-factor)를 새롭게 산정하여 토양유실량을 산정하는 방법을 제안하였다. 2003년간 임하호 유역에서의 토양유실량은 2,070,580 ton인 것으로 모의되었다. 우회수로의 효과를 모의한 결과 경사지 밭에서의 누적 흐름면적이 감소하였으며 이에 따라 토양유실량의 저감효과가 잘 모의되는 것으로 나타났다. 임하호 유역전체유역을 대상으로 토양유실 주요유발 경사지 밭을 선택하여 우회수로를 설치하여 모의한 결과 우회수로에 의한 토양유실저감효과는 26%인 것으로 모의되었다.

The method for simulating the diversion ditch for reducing soil erosion from cropland by RUSLE technology was proposed and the analysis of reduction efficiency of soil erosion from cropland within Imha Dam watershed for 2003 using SATEEC model based on RUSLE technology. The major mechanism of diversion ditch for controling soil erosion is to divert surface runoff, which can generate rill and gully erosion, from upper area into cropland. To simulate diversion ditch under RUSLE technology, DEM covered only cropland was clipped and LS-factor for clipped DEM was re-generated by SATEEC model. As a result of example application, flow accumulated area within cropland with diversion ditch was significantly reduced compared to that without diversion ditch and the effect of diversion ditch was well simulated by the proposed method. The 2,070,580 ton of soil was eroded from Imha Dam watershed for 2003. The reduction efficiency of diversion ditch was simulated about 26% of soil erosion from the selected cropland as a hot spot.

본 연구에서는 비용효율적인 인공습지의 설계를 위하여 초기 침강지 내 다양한 도류벽형태에 따른 인공습지의 사수역 및 입자상 물질의 제거효율을 전산유체역학(Computational Fluid Dynamics, CFD)을 통해 연구하였다. 그 결과, 초기 침강지에서 도류벽의 형태는 유입 유속에 영향을 미치며, 침전률에도 큰 영향을 미치는 것으로 분석되었다. 2 ㎛ 와 5 ㎛ 와 같은 미세한 입자에서는 수평으로 설치한 도류벽에서 침전률이 높았으며, 10 ㎛ 와 20 ㎛ 크기의 큰 입자는 수직형 도류벽에서도 높은 침전률을 나타내었다. 또한, 수직형 도류벽의 경우 좁은 면적에 침전이 집중적으로 이루어지기에 다른 형태에 비해 유지관리가 효율적일 것으로 판단되었다. 이에 인공습지의 설계 목적에 따라 가장 적절한 도류벽의 형태를 선정하여 설계해야 할 것으로 보여진다.

In this study, the removal efficiency of the wetland in terms of particulate matter and dead water zone through the application of baffles in the sedimentation were simulated with the use of Computational Fluid Dynamics (CFD) to determine the design of a cost-effective constructed wetland. As a result, it was analyzed that the application of the baffle in the sedimentation tank affect the flow and sedimentation rate. Fine particles such as 2 ㎛ and 5 ㎛ showed high sedimentation rate when the baffles are installed horizontally. large particles such as 10 ㎛ and 20 ㎛ showed also high deposition rate when the baffles are installed vertically. In addition, the vertical baffles is considered to be more efficient than other baffle types in terms of maintenance since the particulate matter are concentrated in narrow areas. Therefore, it is considered that the selection of the most applicable type of baffle depends on the design purpose of the wetland to be constructed.

EPCIS(EPC Information Services) system is a core component of EPCglobal Architecture Framework offering information of the freights, the time of awareness and the location of awareness on the EPCglobal Network. The role of EPCIS is to exchange information based on EPC. There are four kinds of event data which are object event data, aggregation event data, quantity event data, and transaction event data. These EPCIS events data are stored and managed in EPCIS repository. This paper deals with the method which diversifies the data flow load of intensive EPCIS events and effectively manages EPCIS repository for exchanging data smoothly. In order to verify a effectiveness, we measure the performance of the system using a simulation by comparing the existing method with the suggested method.

This study was successfully achieved out the optimized system for dispersing and mixing condition of resin liquid. The flow analysis was simulated according to the shape of the impeller and the stirring tank using ANSYS software and optimized in advanced design. As a result, it was confirmed that the shape and double number of the impeller on the flow field are influenced better effects in a range of mixing and diffusion areas comparing to single number of impeller. It was considered that stirring was performed more quickly and efficiently under the condition of double numbers and saw tooth type impeller. This result can be applied practically for the mixing tank in the industrial application and avaliable used to make a new system for painting equipment.

In order to solve the problem about the brush and slip ring in drive motor of renewable energy vehicle, high frequency power magnetic field produced by a novel separable magnetic pot transformer could achieve contactless excitation energy transfer. For contactless energy transfer (CET) system, its research about energy and efficiency quality still remains a low level because application and research of CET are not integrated, especially how to improve transmission power and efficiency is still not enough. First of all in this paper, the topology of magnetic pot transformer is built to design resonant compensation circuit. Secondly, mutual inductance parameter is proposed by optimum efficiency analysis through calculation. Thirdly, circuit simulation model of Matlab and 3D simulation model of Ansoft Maxwell which can complete finite element transient analysis are built to verify the accuracy of optimum efficiency analysis. Lastly, the experiment platform about CET in synchronous generator prototype is performed. Although the output power had little increase, experiment and Matlab, Ansoft 3D simulation research proved that system efficiency had a quite increase based on optimum efficiency analysis.

We focus on a way of combining the Monte Calro methods of antithetic variates and control variates to reduce the variance of the estimator of the mean response in a simulation experiment. Combined Method applies antithetic variates (partially) for driving approiate stochastic model components to reduce the vaiance of estimator and utilizes the correlations between the response and control variates. We obtain the variance of the estimator for the response analytically and compare Combined Method with control variates method. We explore the efficiency of this method in reducing the variance of the estimator through the port operations model. Combined Method shows a better performance in reducing the variance of estimator than methods of antithetic variates and control variates in the range from 6% to 8%. The marginal efficiency gain of this method is modest for the example considered. When the effective set of control variates is small, the marginal efficiency gain may increase. Though these results are from the limited experiments, Combined Method could profitably be applied to large-scale simulation models.

시뮬레이션 실험에서 시스템 성과에 대한 추정치의 정확도를 개선하기 위한 분산감소기법(Variance Reduction Technique)은 입력영역과 출력영역에 대한 것으로 나누어 볼 수 있다. 본 연구에서는 시스템 성과 추정량이 단일 변량인 경우에, 분산감소기법으로 많이 사용되는 Antithetic Variates방법과 Control Variates방법을 결합하여 응용가능한 시뮬레이션 실험설계기법을 제시하고 이 기법을 선택된 모형에 적용하여 시뮬레이션의 효율성을 분석하였다. 실험결과, 제안된 기법은 기존 방법들보다 추정치의 분산을 5%-8% 더 감소시켰다. 비록 제한된 실험결과이지만 이러한 효과는 대형 시뮬레이션의 경우에 적지 않으리라 기대된다. 특히 효과적인 Control Variates의 수가 적은 경우, 제안된 기법은 매우 효율적이다.

Through a simulation experiment, often an experimenter is concerned with estimating the system parameters of the linear model consisting of m design points from the outputs oft the simulation model. To improve the estimation of the system parameters and reliability of these estimators, appropriate simulation techniques have been developed. For the first order linear model, Schruben and Margolin (1978) exploited the random number assignment rules which uses a combination of common random numbers and antithetic streams in a simulation experiment designed to estimate the system parameters when the design matrix of simulation model admits orthogonal blocking into two blocks. Nozari, Arnold and Pegden (1984) developed a method for appliying the method of control variates to the situation of the linear model having multiple design points. This talk deals with a different way of utilizing controls under the correlation induction strategy of Schruben and Margolin's to improve the simulation efficiency, and presents a procedure for obtaining the estimators of the system parameters analytically. Simulation results on a selected simulation model indicate a promising evidence that a proposed method may yield better results than Schruben and Margolin's method.

In the present paper, we focus on the flow computation of a low head Propeller turbine at a wide range of design and off-design operating conditions. First, we will present the results on the efficiency hill chart prediction of the Propeller turbine and discuss the consequences of using non-homologous blade geometries for the CFD simulation. The flow characteristics of the entire turbine will be also investigated and compared with experimental data at different measurement planes. Two operating conditions are selected, the first one at the best efficiency point and the second one at part load condition. At the same time, for the same selected operating points, the numerical results for the entire turbine simulation will be compared with flow simulation with our standard stage calculation approach which includes only guide vane, runner and draft tube geometries.

Hybrid electric vehicles have attracted much attention of late, emphasizing the necessity of developing traction motors with a high input current and a wide speed range. Among such traction motors, various researches have been conducted on interior permanent-magnet synchronous motors (IPMSMs) with high power density and mechanical solidity. Due to the complexity of its parameters, however, with nonlinear motor characteristics and current vector control, it is actually difficult to accurately estimate the base speed within an actual operating speed range or a voltage limit. Moreover, it is impossible to construct an efficiency map as the efficiency differs according to the control mode. In this study, a simulation method for operation performance considering the nonlinearity of IPMSM was proposed. For this, datasets of various nonlinear parameters were made via the finite-element method and interpolation. Maximum torque-per-ampere and flux-weakening control were accurately simulated using the datasets, and an IPMSM efficiency map was accurately constructed based on the simulation. Lastly, the validity of the simulation was verified through tests.

In this work, a numerical analysis of a CIGS ($CuIn_{1-x}Ga_xSe_2$) solar cell with a rectangular grating on the electrode is presented. The effects of the grating on the energy conversion efficiency are calculated using the RCWA (rigorous coupled wave analysis) method. In conventional CIGS solar cells, the thickness of the light absorption layer (CIGS) is $2\;{\mu}m$, at which the incident light is almost absorbed. By adopting a grating on the electrode and using a less than $1\;{\mu}m$ CIGS layer, we obtained a higher efficiency compared to the conventional solar cells.

An optical model based on the optical thin-film theory is derived to calculate the output radiance of small molecules organic light-emitting diodes (OLEDs). We have designed the high efficiency OLEDs using the reflectance phase control of dielectric layers. It is found that OLED with a single $TiO_2$ dielectric layer is a good candidate to enhance the outcoupling efficiency and increase the color purity.

We performed computer simulations to improve transmission efficiencies of a dual ion funnel system implemented on an FT-ICR MS. We found that the low m/z range from 50 to 150 could be significantly improved by operating the two ion funnels at different RF amplitudes. These new operational conditions could be applied to analyze metabolome samples, which require high sensitivity in the m/z range from 50 to 1,000.

The design of the LEDs lighting in general household illumination was proposed and compared with the fluorescent lighting in this study. Using the LED as a light source would promote energy saving lighting for household illumination purposes. We used the LightTools and DIALux software to design and simulate different standards of illuminance, different correlated color temperatures and different color rendering indices for household environments. The power consumption and efficiency of traditional illuminated light sources and an LED light source with the same standard of illuminance for lighting the household environment were analyzed and compared with each other. Finally, our results show the advantages of using white-light LEDs for lighting and household illumination.