• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1212-1215
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• 2009

The theoretical equations for J-V characteristics in an OLED was derived according to the internal carrier emission equation based on a diffusion model at Schottky barrier contact and the mobility equation based on the Pool-Frenkel model. The J-V characteristics of OLED are presented using a behavioral model for analog systems (Verilog-A language), and the accuracy of this model was verified by comparing with the device simulation results.

• Journal of the Korea Society for Simulation
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• v.7 no.2
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• pp.17-32
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• 1998

The flow fields in Gas Bubble Driven Circulation Systems were numerically analyzed. In various gas flow rate and bubble size, the flow characteristics were predicted. Eulerian-Eulerian approach was used for the formulation of both the continuous and dispersed phases. The modification of the general purpose computer program PHOENICS code was employed to predict the mean flow fields, turbulent characteristics, gas dispersion, volume fraction. The predicted shows very satisfactory agreement with experimental results for all regions of ladle. The results are of interest in the design and operation of wide variety of material processing.

• The Journal of the Acoustical Society of Korea
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• v.19 no.2
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• pp.73-82
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• 2000

This paper presents a significant improvement achieved in the acoustic characteristics of a conference room of I-company originally designed and built without consideration for room acoustic characteristics. The reverberation time of the room was excessive, which resulted in poor 'Definition' for speech. Thus the improvement of room acoustic characteristics was required. In this study, experiments and simulations using the principles of geometrical acoustics were executed to improve the acoustic characteristics in the room. By performing a series of simulation, it has become possible to predict acoustic parameters for an improvement plan. And the improvement plan of room acoustic characteristics was established. And for the verification of the simulation results, the experimental data were compared and evaluated against those from the simulation. Additionally, the proposed method in this paper demonstrated its effectiveness by successfully improving the room acoustic characteristics resulted from repair construction.

• The KSFM Journal of Fluid Machinery
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• v.12 no.3
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• pp.13-18
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• 2009

This paper describes flow characteristics in a piping system having various duct shapes on refuse collecting system. A simulator for the refuse collecting system is designed to analyze the flow characteristics in the piping system. The simulator consists of an air intake, a waste chute, circular duct having various shapes, cyclone and turbo blower. The simulator has four different duct shapes: straight, curved, inclined and Y-shaped ducts. Three-dimensional Navier-Stokes analysis is introduced to analyze the pressure loss in the piping system. Throughout the numerical simulation, pressure loss obtained by numerical simulation has a good agreement with the results of experimental measurements. The selected length of curved and Y-ducts for the pressure loss is determined using pressure distributions on the duct. Flow and pressure characteristics in the piping system of the simulator are evaluated by numerical simulation and discussed in detail.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.172-181
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• 1997

The dynamic characteristics during gear ratio change including the disturbance of output torque has been one of the most important issues in the study of automatic transmissions of passenger cars. In this paper, to investigate the dynamic characteristics of a passenger car automatic transmission during gear ratio change, a dynamic model of the driveline of a passenger car focused on the automatic transmission is proposed and the dynamic simulation program is developed. The results of the simulation show good agreements with the experimental data, which process the use fullness of the dynamic model and the simulation of the driveline.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.120-126
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• 2006

Vehicle dynamic simulation has been carried out using the coherence of road roughness between left and right wheels. The generated twin tracks with the coherence of road roughness between left and right wheels are in good agreements with the measured coherence relation of left and right wheels. And these tracks reflect well on the roughness characteristics of real roads. Using the generated roads and multibody dynamic simulation program, vehicle dynamic simulation is performed. The vertical and roll motion analysis of a vehicle are carried out using the realistic road profiles with the coherence between left and right wheels and the results are in good agreements with the dynamic characteristics of a vehicle.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.91-105
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• 1999

Dynamic simulation techniques are developed to analyze the shift characteristics of vehicle powertraisn with automatic transmission. In this study, the mathematical modeling of powertrain components such as engine , clutch system, planetary gear system and road load , is presented for the simulation. The clutch engagement condition, which determines the degree of freedom for the system, is also proposed .By using a detailed nonlinear model of torque converter, it is possibile to accurately analyze the extremely transient state such as the shift. Dynamo-based experiments are carried out to prove the validity of the proposed simulation techniques. Using the developed simulation program, the effects of the dynamic design variables and the control conditions , focused on the shift, are evaluated to improve the driving comforability.

• Journal of Biosystems Engineering
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• v.25 no.2
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• pp.89-96
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• 2000

In this study, experiments were performed for various drying air temperatures, air flow rates tray distance to analyze drying characteristics of batch type tunnel dryer. In comparison of tunnel drying with cabinet drying which is currently used in the farm, the results of drying simulation model of cabinet dryer was used and then the possibility of applying the drying simulation model of cabinet dryer to batch type tunnel dryer was investigated. The results showed that as the drying temperature increased, the drying rte and moisture difference in the direction of air flow increased and as the air flow rate increased, the drying rate increased and moisture differences decreased. In tunnel dryer, drying through bottom of the tray had large effect on drying rate and the effect was more significant when the drying temperature increased. As air flow rate increased, the difference of drying rates between tunnel and cabinet drying increased and drying rate of tunnel of drying was higher. The drying simulation model could estimate moisture content in tunnel more precisely by using modified effective moisture diffusion coefficient for air flow rate.

• Progress in Superconductivity and Cryogenics
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• v.23 no.1
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• pp.1-6
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• 2021

Thermoacoustic oscillations (TAOs) could be often observed in liquid helium cryogenic system especially in half-open tubes. These tubes have closed warm end (300K) and open cold end (usually 4.4K). This phenomenon significantly induces additional heat load to cryogenic system and other undesirable effects. This work focuses on using computational fluid dynamics (CFD) method to study TAOs in liquid helium. The calculated physical model, numerical scheme and algorithm, and wall boundary conditions were introduced. The simulation results of onset process of thermoacoustic oscillations were presented and analyzed. In addition, other important characteristics including phase relation and frequency were studied. Moreover, comparisons between experiments and the CFD simulations were made, which demonstrated thevalidity of CFD simulation. CFD simulation can give us a better understanding of onset mechanism of TAOs and nonlinear characteristics in liquid helium cryogenic system.

• Journal of the Korea Society for Simulation
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• v.3 no.1
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• pp.1-16
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• 1994

In this paper, the modeling capabilities of an object-oriented simulator, AgvTalk is demonstrated by designing and simulating a conceptually configuration of AGV systems, known as the tandem configuration. The characteristics and design methodology in AgvTalk are described between the tandem configuration for AGV systems and conventional AGV systems. Also, simulation between the conventional AGV system and its corresponding tandem AGV system are compared with AgvTalk in the job shop environment. From the simulation results, the characteristics of each system observed are discussed.