• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.4
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• pp.359-364
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• 2022

The change detection in remote sensing results in errors due to the camera's optical factors, seasonal factors, and land cover characteristics. The inclination of the building in the image was simulated according to the camera angle using the Cycle Generative Adversarial Network method, and the simulated image was used to contribute to the improvement of change detection accuracy. Based on CycleGAN, the inclination of the building was similarly simulated to the building in the other image based on the image of one of the two periods, and the error of the original image and the inclination of the building was compared and analyzed. The experimental data were taken at different times at different angles, and Kompsat-3A high-resolution satellite images including urban areas with dense buildings were used. As a result of the experiment, the number of incorrect detection pixels per building in the two images for the building area in the image was shown to be reduced by approximately 7 times from 12,632 in the original image and 1,730 in the CycleGAN-based simulation image. Therefore, it was confirmed that the proposed method can reduce detection errors due to the inclination of the building.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.545-552
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• 2015

Process modeling and simulation is a powerful methodology to quantitatively predict the change of process variables when operating and design conditions are changed. In this study, considering drawbacks of currently used process simulator for combined cycle plants, we developed process modeling system equipped with an ease of use and flexibility for model development. For this purpose, the analysis of combined cycle processes was carried out and consequently, mathematical models and libraries were developed. Furthermore, in view of the fact that the level of the abstraction of process models depends on the purpose of simulation as well as the available data, simple and rigorous models were also developed for some important units. In use of reference combined plant, we executed process simulation using the developed modeling system and the comparison was made between the results of simulation and the reference data. Less than 1% marginal error was identified and we concluded that the modeling system can be applied for commercial combined cycle processes.

• Journal of IKEEE
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• v.23 no.1
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• pp.1-8
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• 2019

In this paper, the electrical characteristics with various C-rates are tested with a high power series battery pack comprised of 18650 cylindrical nickel cobalt aluminum(NCA) lithium-ion battery. The electrical characteristics of discharge capacity test with 14S1P battery pack and electric vehicle (EV) cycle test with 4S1P battery pack are compared and analyzed by the various of C-rates. Multiple linear regression is used to estimate voltage imbalance of 14S1P and 4S1P battery packs with various C-rates based on experimental data. The estimation accuracy is evaluated by root mean square error(RMSE) to validate multiple linear regression. The result of this paper is contributed that to use for estimating the voltage imbalance of discharge capacity test with 14S1P battery pack using multiple linear regression better than to use the voltage imbalance of EV cycle with 4S1P battery pack.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.21-33
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• 2020

In this study, the program for system analysis of an expander cycle rocket engine using liquid hydrogen as a fuel was developed. The properties of hydrogen were considered by the ratio of isomers with temperature. The analysis procedure was established with the open and closed types of the expander cycle engine and the simulation methods were suggested for each component. To validation of the analysis program, we compared the performance of the engine operating point and the analysis results performed overseas for Vinci and SE-21D, which are expander cycle engines. As a result of the analysis, the main performance factors of the system, such as the mass flow of the propellant, specific thrust, and power, except for some of the inaccurate input information, showed high accuracy with an error of around 1-2%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1117-1125
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• 2000

A current mode PWM method applied one cycle response to averaging circuit model Buck converters is presented. The controller nonlinear PWM implement is based on the error between the switched variable and the response reference to zero each cycle. As the result, the system transfer function is derived as a function of the desired close loop poles, simplifying the design procedure and bringing forward all the important characteristics of the close loop system. The proposed controller has significant advantages over conventional current mode control methods in noise susceptibility, dynamic response and without inductor current sensing, Finally, the simulation and experiment results confirm the proposed PWM control techniques.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.278-280
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• 1999

This paper proposes controlling of temperature in an oven by using 4 bits Integral - Cycle Binary Rate Modulation (IBRM) method and ac line with frequency 50 Hz. Microcontroller MCS-51 controls IBRM according to Proportional Integral controller (PI) function. Discrete signals are used in the system modeled by using Ziegler Nichols principle for analyzing the stability before designing the system. This procedure makes it easy to investigate system response. The system is implemented by 4 bits digital circuit which gives 320 patterns of ac signal fur controlling the generation of energy for 3,000 watts thermal coil every 20 ms of each cycle. We divide scan time (Ts$\sub$n/) in to 20 intervals, 1 ms interval is selected to generate 16 patterns IBRM. Because of this method gives the ripple lower than 2% it generates less noise fur system. Moreover, we can consider whole system from the time model of control procedure and IBRM algorithm at 40-200$^{\circ}C$ with ${\pm}$ 1$^{\circ}C$ error in the 1 cubic meter oven.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.10
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• pp.9-15
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• 2009

In this paper, we invented a new structure of fast ATC(Automatic Threshold Control) circuit. Using the structure we made a new burst-mode limiting amplifier with fast ATC function using commercial $0.8{\mu}m$ BiCMOS technology. It's ATC function worked so fast that even the first bit of burst-data could be detected, which confirmed that the new structure was useful for fast ATC. However, in the beginning of a burst, distortions in duty-cycle occurred and increased up to 59% of duty-cycle as amplitude of input signal increased. But we confirmed that after 10 cycles passed, duty-cycles was staying below 52% of duty-cycle for any magnitude of input signal.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.573-578
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• 2010

Topological matrix which reflects characteristics of network connectivity has been widely used in efficient solving for complicated flow network. Using topological matrix, one can easily define continuity at each node of flow network and make algorithm to automatically generate continuity equation of matrix form. In order to analyze flow network completely it is required to satisfy energy conservation in closed loops of flow network. Fundamental cycle retrieving algorithm based on graph theory automatically constructs energy conservation equation in closed loops. However, it is often accompanied by NP-complete problem. In addition, it always needs fundamental cycle retrieving procedure for every structural change of flow network. This paper proposes alternative mathematical method to analyze flow network without fundamental cycle retrieving algorithm. Consequently, the new mathematical method is expected to reduce solving time and prevent error occurrence by means of simplifying flow network analysis procedure.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.93-97
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• 2010

The analysis of specific impulse of the liquid rocket engine employing gas generator cycle with LOx/kerosene as propellant has been performed. The relative error of performance of 300 ton level engine is 0.1%s for specific impulse and 12% for optimal combustion pressure comparing with the published data. The difference of the performance model and the material property models of gas generator product gas are the presumed major reason of discrepancy. The optimal condition of 30 ton level engine is combustion pressure of 68 bar and mixture ratio of 2.2 for maximum specific impulse. This optimal condition can be changed by performance models.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.70-76
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• 2014

Surely fuel economy(F.E.) label is needed to meet consumer's right to know. Korea has developed and adopted F.E. correction equation similar to the feeling, because consumer complain about F.E. label higher than they feel. Recently, through continuous research and development high-efficiency & performance green car like HEV, PHEV and EV are being sold. In this situation, it is needed to know whether the current equation can reflect a part of their improved technic or not. In this paper, to review current equation through test using hybrid vehicles on 5-cycle SOC, correction equation and F.E were discussed. The result show HEV didn't meet the SOC error standard on US06. Also, HEV has bigger F.E. difference between FTP-75 and 5-cycle than conventional vehicles. However, the correction equation that include HEV almost same with current one.