• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.896-902
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• 2019

In this paper, we proposed two methods to automatically generate color images similar to existing images using genetic algorithms. Experiments were performed on two different sizes($256{\times}256$, $512{\times}512$) of gray and color images using each of the proposed methods. Experimental results show that there are significant differences in the evolutionary performance of each technique in genetic modeling for image generation. In the results, evolving the whole image into sub-images evolves much more effective than modeling and evolving it into a single gene, and the generated images are much more sophisticated. Therefore, we could find that gene modeling, selection method, crossover method and mutation rate, should be carefully decided in order to generate an image similar to the existing image in the future, or to learn quickly and naturally to generate an image synthesized from different images.

• Journal of Aerospace System Engineering
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• v.12 no.4
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• pp.49-56
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• 2018

In this paper, the performance analysis and the experiment of the brake system using the small piezoelectric-hydraulic pump were performed. Initially, the 3-D modeling of the brake load components was performed for the construction of the brake system. Subsequently, modeling using the commercial program AMESim was performed. A floating caliper model was used as a load for modeling the brake system. Through the AMESim simulation, load pressure, check valve displacement and flow rate under no load state were calculated, and performance analysis and changes in dynamic characteristics were confirmed by adding brake load. A jig for use in fixing the brake load during performance test was manufactured. The flow rate was assessed under no load condition and load pressure formation experiments were performed and compared with simulation results. Experimental results revealed the maximum load pressure as about 73bar at 130Hz and the maximum flow rate as about 203cc/min at 145Hz, which satisfied the requirement of small- and medium-sized UAV braking system. In addition, simulation results revealed that the load pressure and discharge flow rate were within 6% and 5%, respectively. Apparently, the modeling is expected to be effective for brake performance analysis.

• Composites Research
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• v.16 no.5
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• pp.7-14
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• 2003

Modeling of thick composite structures for finite element analysis is relatively complicated. 2-D plane elements may cause inaccurate result since the plane stress condition cannot be applicable in these structures. Therefore a 3-D modeling should be used. However, the difficulty to model all the layers with different material properties and ply orientation arise in this case. In this paper, an equivalent modeling is proposed and numerically tested for analysis of thick composite structures. By grouping layers with same material and ply orientation, number of elements through the thickness is remarkably reduced and still the result is close enough to the one from a detail finite element model. MSC/NASTRAN and PATRAN are used for the analysis. The proposed modeling technique has been applied for analysis of composite rotor hub system designed by Korea Aerospace Research Institute(KARI). Using the proposed equivalent modeling technique, we could conduct stress analysis for the hub system and check the safety factor of each part.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.21-30
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• 2016

Recently manufacturing companies have used PLC control programs popularly for their automated production systems. Since the life cycle of production process is not so long, the change of the production lines occur frequently. Most of changes happen with modification of the position information and control process of the equipment. PLC control program is also modified based on the fundamental process. Therefore, to verify new PLC program by configuring virtual space according to real environment is needed. In this paper we show a logical modeling method, based on Timed-FSA useful for sequence control and dead-lock prevention. There is a problem wasting user's labor and time when defining a variety of states in a device. To overcome this problem, we propose an extended I-O model based on existing methods by adding a token concept of Petri Nets. Also we will show the usability of the extended I-O modeling through user study.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.242-248
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• 2007

For an optimal design of automotive electric system, it is important to have a reliable modeling tool to predict the charge-discharge behaviors of the automotive battery. In this work, a two-dimensional modeling was carried out to predict the charge-discharge behaviors of a 12-V automotive lead-acid battery. The model accounted for electrochemical kinetics and ionic mass transfer in a battery cell. In order to validate the modeling, modeling results were compared with the experimental data of the charge-discharge behaviors of a lead-acid battery. The discharge behaviors were measured with three different discharge rates of C/5, C/10, and C/20 at operating temperature of $25^{\circ}C$. The batteries were charged with constant current of 30A until the charging voltage reached to a predetermined value of 14.24 V and then the charging voltage was kept constant. The discharge and charge curves from the measurements and modeling were in good agreement. Based on the modeling, the distributions of the electrical potentials of the solid and solution phases, the porosity of the electrodes, and the current density within the electrodes as well as the acid concentration can be predicted as a function of charge and discharge time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.107-114
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• 2011

In this study, a correlation between the roughness of nanoscale lapping surface and its laser scattering pattern has been identified experimentally. The characteristics of laser scattering on a reflected surface are investigated, and a laser scattering mechanism is newly designed by adopting the dark-field method. Laser scattering patterns resulting from nanoscale lapping shape are in the shape of crossed irregular lattice. In addition, optimum laser scattering images are obtained by the design of experiment, and the roughness of nanoscale lapping surface is estimated using regression analysis certain useful features of the laser scattering patterns. The results of fifty experiments on three types of nanoscale lapping surfaces show that the roughness of nanoscale lapping surfaces can be accurately estimated by the proposed mathematical modeling method.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.520-527
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• 2006

A realistic surface model is presented for prediction of various surface phenomena such as polymer deposition, suppression and sputtering as a function of incidence ion energy in high density fluorocarbon plasmas. This model followed ion enhanced etching model using the "well-mixed" or continuous stirred tank reactor (CSTR) assumption to the surface reaction zone. In this work, we suggested ion enhanced polymer formation and decomposition mechanisms that can capture $SiO_2$ etching through a steady-state polymer film on $SiO_2$ under the suppression regime. These mechanisms were derived based on experimental data and molecular dynamic simulation results from literatures. The model coefficients are obtained from fits to available beam and plasma experimental data. In order to show validity of our model, we compared the model results to high density fluorocarbon plasma etching data.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.850-852
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• 2005

마이크로 프로세서 구조의 성능을 분서할 때, 트레이스 구동형 모의실험이 광범위하게 수행되고 있으나, 시간과 공간을 많이 차지하기 때문에 비실용적이다. 본 논문에서는 통계적 프로화일링 기법을 이용하여 다양한 하드웨어 사양을 갖는 수퍼스칼라 마이크로 프로세서의 성능간 통계적 모의실험에 의하여 측정하는 기법에 대하여 연구하였다. 이것을 위하여 SPEC 2000 벤치마크 프로그램의 특성을 통계적 프로화일링 기법으로 모델링하고 여기서 얻은 통계적 프로화일을 바탕으로 벤치마크 트레이스를 합성하여 모의실험을 수행하였다. 그 결과, 다양한 하드웨어 구성에 대하여 비교적 높은 정확도를 얻을 수 있었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.42-47
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• 1992

본 연구에서는 공극관의 실험인자에 대한 특성을 알아보기 위하여 공극관에 입사되는 음파의 파수 k와 공극분포부분들 사이의 거리인 a의 곱으로 나타나는 무차원변수 ka와, 공극관의 단면적에 대한 전체 공극면적의 비로 정의한 공극률을 실험인자로 하여 연구를 진행하였다. 또한 sulivan의 모델을 이용하여 공극관을 모델링하고 이를 컴퓨터를 사용하여 모의 실험을 한 후 실험결과와 비교하였다.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.22-30
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• 2015

So far, most of research activities on modeling of membrane separation processes have been focused on binary feed mixture. But, in actual separation operations, binary feed is hard to find and most separation processes involve multicomponent feed mixture. In this work models for membrane separation processes treating multicomponent feed mixture are developed. Various model types are investigated and validity of proposed models are analysed based on experimental data obtained using hollowfiber membranes. The proposed separation models show quick convergence and exhibit good tracking performance.