• Journal of the Korean Solar Energy Society
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• v.30 no.2
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• pp.87-95
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• 2010

This study analyzed the performance of solar chimney system for natural ventilation in underground space. A mathematical model of the solar chimney was proposed in order to predict its performance under varying parameters and Korea climatic condition. Steady state heat transfer equations were set up using a energy balanced equations and solved using a inverse matrix method. Numerical simulation program to analyze system was developed by using MATLAB. As the results, the ventilation performance of the solar chimney was determined by the temperature difference of air channel and inlet, and the temperature difference was influenced by insolation, stack height and distance of air gab. Also the solar chimney system can provide $262.9m^3/h$ of annual average ventilation rate. Because seasonal differences of ventilation rate was calculated within 25%, the solar chimney system can be used for every season in Korea climatic condition. Through this study, performance of solar chimney system for natural ventilation was verified by numerical method. Consequently, the solar chimney system is proved to be effective device for natural ventilation utilizing at all times, and the additional studies should be made through the experimental method for imagineering and commercialization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.536-564
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• 2019

Soft faults are inherent in wireless sensor networks (WSNs) due to external and internal errors. The failure of processes in a protocol stack are caused by errors on various layers. In this work, impact of errors and channel misbehavior on process execution is investigated to provide an error classification mechanism. Considering implementation of WSN protocol stack, inter-process correlations of stacked and peer layer processes are modeled. The proposed model is realized through local and global decision trees for fault diagnosis. A hybrid framework is proposed to implement local decision tree on sensor nodes and global decision tree on diagnostic cluster head. Local decision tree is employed to diagnose critical failures due to errors in stacked processes at node level. Global decision tree, diagnoses critical failures due to errors in peer layer processes at network level. The proposed model has been analyzed using fault tree analysis. The framework implementation has been done in Castalia. Simulation results validate the inter-process correlation model-based fault diagnosis. The hybrid framework distributes processing load on sensor nodes and diagnostic cluster head in a decentralized way, reducing communication overhead.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.11-17
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• 2009

This paper deals with the estimation performance DoA (Direction of Arrival) using the 3D adaptive array antenna in W-CDMA signal. For this, we proposed the 5 types of 3D array antenna, and appied for the MUSIC in order to the estimation of DoA algorithm for that antenna, commonly, then the DoA estimation error was used for the estimation performance. In the mobile communication and radio positioning service, performing the spatial filtering after the DoA estimation in array antenna, the quality of receiving signal can improve by the nulling or minimization of interfering signal which is from the undesired direction and the forming of beam which is from the desired direction. The result of DoA estimation and the DoA estimation error by varying the signal to noise ration and the number of interfering signal and power of each type antenna was calculated by computer simulation. As a result of simulation, the other propose antenna has good performance excluding the stack 3D antenna in DoA estimation and the Curved-B type antenna has more superior performance when increasing the number of interfering signal and power in the DoA estimation error.

• Journal of ILASS-Korea
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• v.17 no.2
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• pp.57-63
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• 2012

For reduction of CO, NOx and soot emission emitted by diesel diffusion combustion, the authors focused on injection actuator to improve fuel availability inside combustion chamber. In this study, it was investigated the internal dynamic characteristics of two-stage injection with diesel injectors with different driving type for the common rail direct injection by using the AMESim simulation code. The analysis parameter defined such as fuel pressure, injection hole's diameter and driven voltage. As the results, it was shown that the piezo-driven injector had a faster response and had better control capability than the solenoid-driven injector. It was found the piezo-driven injector can be utilized effectively as multiple injector than solenoid-driven injector.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.31-34
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• 1995

The automated chemical analysis shop floor are developed for the environmental pollution problems in our chemical analysis center. This shop floor have the several equipments include weight, pour, dry, heater, boiler, mixture, spectroscopy etc. And the material handling components are made up by the stored stack, conveyore, turntables, robot etc. Computer simulation has been an important tool for these complete design problem. We have designed the arangement of chemical equipments and material flow systems by using the simulator "AutoModII". "AutoMoII" is one of the advanced simulator, CAD-like drawing tools with a powerful, engineering oriented language to model control logic and material flow. The result is the modeling of the chemical analysis system in accurate, three dimensional detail. We could designed the set able layout and scheduling system by using the AutoMoII simulator. AutoMoII simulator.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.3
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• pp.223-233
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• 1999

The wind-flow characteristics over a two-dimensional triangular prism with a porous windbreak are numerically investigated. The geometry is a simplified model of large outdoor stack with a frontal wall-type windbreak which is used to prevent particle dispersion by reducing wind speed over stak surface. In the present numerical model, the RNG k-$\varepsilon$ model, the orthogonal grid system and the QUICK scheme are employed for the successful simulation of separated flow. The predicted results are compared and validated with the associated wind-tunnel experiments. In addition, the trajectories of dispersed particles and their sedimentation characteristics are quantitatively investingated using a Lagrangian turbulent-dispersion model.

• Journal of KIISE:Software and Applications
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• v.29 no.5
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• pp.326-335
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• 2002

Recently there have been a number of researches to provide code mobility to lazy functional language (LFL) programs by translating LFL programs to Java programs. These approaches are basically baled on architectural similarities between abstract machines of LFLs and Java. The abstract machines of LFLs and Java programming language, Spineless Tagless G-Machine(STGM) and Java Virtual Machine(JVM) respectively, share important common features such as built- in garbage collector and stack machine architecture. Thus, we can provide code mobility to LFLs by translating LFLs to Java utilizing these common features. In this paper, we propose a new translation scheme which fully utilizes architectural common features between STGM and JVM. By redefining STGM as an eval-apply evaluation model, we have defined a new translation scheme which utilizes Java Virtual Machine Stack for function evaluation and totally eliminates stack simulation which causes array manipulation overhead in Java. Benchmark program translated to Java programs by our translation scheme run faster on JDK 1.3 than those translated by the previous schemes.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.109-112
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• 2007

In this paper, a mathematical modeling was developed to simulate 1kW class air cooled Polymer Electrolyte Membrane Fuel Cell(PEMFC) system. The proposed modeling was conducted under SIMULINK based environment. The model ing was developed based on the thermodynamic and chemical equilibrium. The objective is to design and implement the entire fuel cell system model ing including the system controller modeling. The fuel cell process and the control system modeling should have to be connected with each other simultaneously， therefore the two types of modeling influences each other when the system simulator run. The fuel cell modeling libraries are simulated using the SIMULINK under the thermodynamic and chemical equilibrium base. The PID controller application was designed and developed to test the process modeling and verify it. This the prototype development of the fuel cell system to design and test more complicate fuel cell systems, like the residential power generation system. The simulation results was compared to the real PEMFC system performance. We have achieved the reasonable accordance with the Lab test and the simulation results.

• Journal of Hydrogen and New Energy
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• v.18 no.1
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• pp.60-66
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• 2007

In terms of the vehicle efficiency, a fuel cell hybrid system has advantages compared to a conventional internal combustion engine and a fuel cell alone-powered system. The efficiency of the fuel cell hybrid vehicle mainly depends on the maximum power of the fuel cell and therefore it is important to decide the design value of the fuel cell maximum power. In this paper, to estimate the performance of the fuel cell hybrid mini-bus in the design phase the simulator based on the models for the fuel cell stack, the electric battery, the fuel cell balance of plant, the controller, and the vehicle itself is proposed. Additionally, the hybrid mini-bus efficiencies with several different fuel cell powers are simulated for a city driving schedule and are compared on another. Consequently, the proposed simulation scheme is useful to determine the best design value of the fuel cell hybrid vehicles.

• Industrial Engineering and Management Systems
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• v.11 no.3
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• pp.276-287
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• 2012

Determining storage locations of containers is an important issue for efficient operation of container terminals. This study assumes a storage yard with a horizontal layout in which blocks are laid out in parallel to the quay and trucks enter at the side of a block to deliver (receive) a container to (from) the yard crane. Various storage rules for determining storage locations of containers are introduced. Simulation studies are conducted for evaluating various rules. The following guidelines are derived from the result of our simulation study: when designing a block, consider a block configuration in which the longest gantry and the longest trolley travel times of rail-mounted gantry cranes (RMGCs) are similar; do not restrict the types of containers that can be stored in a storage area; if different roles are to be assigned to different storage areas, one possible way is to divide a bay into two areas so that some rows in the bay are allocated to inbound containers while the other rows in the same bay are allocated to outbound containers; reserve the space in bay unit for a high productivity of RMGCs but reserve the space in stack unit when the storage space is not enough; when the storage space is not sufficient, allocate storage location in a way of starting from the end and ending at the middle of a block; for reducing the travel distance of internal trucks, provide a higher priority to a block nearer to the berthing position of the corresponding vessel.