• Journal of the korean Society of Automotive Engineers
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• v.8 no.1
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• pp.62-74
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• 1986

The simulation of power cycle and unsteady gas exchange processes in the inlet and exhaust systems of the single-cylinder 2-stroke cycle compression ignition engine was studied in this paper. In power cycle process, the single-zone model proposed by Whitehouse and Way was used, and the convective and radiative heat transfer from cylinder contents to surroundings was considered. To solve the equations for gas exchange process, the generalized method of characteristics including area change, friction, heat transfer and entropy gradients was used. Also with the path line calculation, the entropy change along the path line and the variation of specific heat due to the change of temperature and the composition of cylinder gas were considered. As a result of the simulation, the change of pressure and temperature in the cylinder against the crank angle, the rate of net heat release, and the change of properties at each point in the inlet and exhaust pipe against the crank angle were obtained. The engine performances under various operating conditions were also calculated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.675-684
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• 1997

The bit rate control algorithm which is capable of handing scene change is proposed. In MPEG-2 TM5, block variance is used to measure block activity. But block variance is not consistent with human visual system and does not differenciate the distribution of pixel values within the block. In target bit allocation process of TM5, global complexity, obtained by results of previous coded pictures, is used. Since I pictures are spaced relatively far apart, their complexity estimate is not very accurate. In the proposed algorithm local variance is used to measure block activity and detect scene change. Local variance, using deviation from the mean of neighboring pixels, well represents the distribution of pixel values within the block. If scene change is detected, the local variance information is used for target bit allocation process. Allocating target bits for I picture, the average local variance difference between previous and current I picture is considered. The experimental results show that the proposed algorithm can detect scene change very precisely and gives better picture quality and higher PSNR values than MPEG-2 TM5.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.78-91
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• 1999

The endless hot rolling has been focused as an innovative process technology for increasing the productivity drastically and reducing the imperfection of quality in hot rolled steel strip. To realize it in actual mill, a lots of new facilities such as bar coiler, movable LASER welder and high speed strip shear should be equipped. And also it is necessary to develop the control technique for changing the roll gap and rolling speed during rolling, which is named as Flying Gap and Speed Change control technology. To prevent a strip rupture caused by excessive tension, it is very important to minimize fluctuations in strip thickness and intension during FGSC control. In this paper, the mathematical model for FGSC control algorithm was suggested and dynamic simulation is performed to accertain the effect of suggested control method on fluctuations in strip thickness and tension. For endless hot rolling simulation, a lots of FGSC control situations, for instance - strip thickness change from strip to strip - strip width change from strip to strip - carbon content change from strip to strip are considered.

• Communications for Statistical Applications and Methods
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• v.16 no.3
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• pp.511-518
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• 2009

We consider the problem of testing for change and estimating the unknown change-point in a sequence of time-ordered observations from the binomial and Poisson distributions. Including the likelihood ratio test, Gombay and Horvath (1990) tests are studied and the proposed change-point estimator is derived from their test statistic. A power study of tests and a comparison study of change-point estimators are done via simulation.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.235-240
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• 2001

This study presents experimental work on phase change heat transfer, in order to increase heat transfer rate, ultrasonic vibrations were introduced. Solid-liquid phase change occurs in a number of situations of practical interest. This study reveal that ultrasonic vibrations accompany the effects like agitation, acoustic streaming, cavitation, and oscillating fluid motion. Such effects are a prime mechanism in the overall melting process when ultrasonic vibrations are applied. Some common examples include the melting of edible oil, metallurgical process such as casting and welding, and materials science applications such as crystal growth. Therefore, this study presented the effective way to enhance phase change heat transfer.

• Journal of Korean Academy of Nursing
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• v.30 no.2
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• pp.354-365
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• 2000

Purpose: This study was performed to identify the factors that change exercise behave. This study will also classify and identify the characteristics of excercise stages to which the elderly belong Also, to identify the processes of change which influence on the changes in exercise performed by the elderly. Methods: Convenient samples of 198 subjects over the age 60 in Seoul Korea(mean age=70) were selected from elderly communities and were all mentally conpetant older adults. The data were collected from April 1,1999 to May 30, 1999. The research instruments were measured the change in exercise (Marcus et al., 1992b), such as Stage of Change measure(Marcus et al,1992a). The data were analyzed by SAS Program. Results: 1. According to the measure of change without missing data, 191 subjects were distributed each stage of change for exercise: 50 subjects (26.1%), 7 subjects (3.6%), 52 subjects (27.2%), 4 subjects (2%), and 78 (40.8%) belonged to the precontemplation stage, the contemplation stage, the preparation stage, the action stage and the maintenace stage. 2. According to the factor analysis, 6 factors of change were identified as appropriate processes of change and were named by the researchers. The names were; 'Supportive helping relationship', 'Self cognitive determination', 'Environmental reinforcement', Consciousness raising', Reinforcement of negative condition and 'Conversion of negative condition'. 3. According to the stage of change, there were significant mean differences in the 'Supportive helping relationship(F=22.04, p=.0001)', 'Self cognitive determination (F=50.87, p=.0001)', 'Reinforcement of negative condition(F=7.84,p=.0006)'. 4. Through the discriminant analysis, it was found that Self cognitive determination is the most influential variable as one of the processes of change which can discrimiate the three stages of change (precontemplation, preparation, and maintenance). Also the next significant variable was Reinforcement of negative condition. Conclusion: The process of the dey change is one of concepts of The transtheoretical model known as strategies and the techniques people use as they go through the different stages of change. Even though this study is cross- sectional not longitudinal study, the finding of this study gives useful information for exercise intervention, by using this strategy of exercise for elderly in different stages of change in exercise.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.1
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• pp.128-136
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• 1992

This study was undertakened to investigate the change of image characteristics on dental films according to the process of using time of processing solution in automatic processor. Base + fog density, film density and subject contrast were measured with the digital densitometer, the pH of developing and fixing solution were measured with Digital pH / ION Meter. The following results were obtained: 1. Base + fog density was increased with the process of using time of the processing solution and was over the maximum permissible base + fog density 0.25 from the 3rd day. 2. Film density was increased with the process of using time of the processing solution. 3. Subject contrast was decreased with the process of using time of the processing solution. 4. The pH of the developing solution was decreased with the process of using time, the pH of the fixing solution was increased.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.70-73
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• 2007

The forming characteristics of cup-rod combined extrusion process were investigated with process parameter change. Simultaneous forward rod extrusion and backward cup extrusion was conducted with magnesium alloy, AZ31B. Process parameters such as forward extrusion ratio, backward extrusion ratio, and working temperature were controlled in a specific region and the effects of the parameter change were examined. Surface crack was developed in a certain state of the process parameters combination. The crack-free forming limit of the alloy in the combined process was disclosed by the parameter study. The microstructures of the initial and extruded workpieces were observed.

• Journal of the Korea Furniture Society
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• v.27 no.4
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• pp.399-411
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• 2016

Korea Furniture design development process is repeated a number of changes by the change of residence and type of market demand derived from the process of industrialization. The modernization process of industrialization advances by large-scale population moves to the city to urbanization proceeds rapidly. Housing problems are concentrated in cities and sparked the furniture industry, furniture design by changes in marketing concepts that appear in the industrialization phase, growth must necessarily accommodate the needs of consumers. Including kitchen furniture, living room furniture and master bedroom furniture has been sensitively adapted changes in the structure of these houses, particularly structural changes Apartments. Starting in the 1990s, jumping over furniture industry has adapted quickly to the market demand, changes in marketing concepts. Furniture industry is growing market share in most of the country, but the entire industry had to undergo a competitive marketing overheating due to excessive supply in excess of market demand since the mid-1990s. Changes in furniture design in this process was the change in furniture design more than the change of the residential structure. The study industrial development and marketing concepts are changing to construct a model to track the changes varied styles and time changes affect whether the main furniture design.

• Journal of Industrial Technology
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• v.18
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• pp.139-148
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• 1998

Traditionally, the problems of manufacturing technology and manufacturing management have been treated independently. In this research, we endeavor to integrate the process planning and scheduling activities as an attempt to integrate the two realms. To draw up a plan of process planning and scheduling in real manufacturing environment is not an easy task because available time to plan could be limited and the shop status could change frequently. So we propose an architecture of integrated process planing and scheduling problem within the allowed time even if sheep situations change rather frequently. We argue that we can obtain a better and practical scheduling solution by dynamically changing the processing machines and operations as the shop condition changes. The proposed system takes the initial information for alternative machines and operations represented by an AND/OR graph as its input. Other informational inputs to the system are part order and shop statues. The system then generates new process plan and schedules during permitted time. Experimental results show that the proposed scheme provides a viable solution for real world scheduling problems.