• International journal of advanced smart convergence
• /
• v.5 no.2
• /
• pp.1-7
• /
• 2016

Recently, with the development of advanced thin film devices comes the need for constant high quality vacuum as the deposition pressure is more demanding. It is for this reason our research seeks to understand how the variable design factors are employed in such vacuum systems. In this study, the effects of design factor applications on the vacuum characteristics were simulated to obtain the optimum design modeling of variable models on an ultra high vacuum system. The commercial vacuum system simulator, $VacSim^{(multi)}$, was used in our investigation. The reliability of the employed simulator was verified by the simulation of the commercially available models of ultra high vacuum system. Simulated vacuum characteristics of the proposed modeling aligned with the observed experimental behavior of real systems. Simulated behaviors showed the optimum design models for the ideal conditions to achieve optimal pressure, pumping speed, and compression ratio in these systems.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.1
• /
• pp.69-75
• /
• 2004

This paper presents the thermal characteristics analysis of a high-speed motor-separated spindle system consisted of angular contact ball bearings and built-in motor with oil-jet lubrication. The spindle system is composed of the main spindle and sub-spindle which are mechanically connected by a flexible coupling. The spindles are supported by two front and rear bearings, and the built-in motor is located between the front and rear bearings of the sub-spindle. The thermal analysis model of spindle system is constructed by the finite element method, and the thermal characteristics in the design stage are estimated based on temperature distribution and heat flow under the various testing conditions related to material of bearing ball, spindle speed and coolant temperature.

• Solar Energy
• /
• v.19 no.3
• /
• pp.75-83
• /
• 1999

The optimum drive control method have to be developed to exhibit the use object contributed trust, accuracy, amenity and energy save of product. To develop the optimum drive control method is, first, grasped the static characteristics for the entire system combined each element which consists the machine and performed the dynamic characteristics explanation based on the satisfied result which acquires at the static characteristics explanation. According to this explanation, the response of the system shows same characteristics tendency and the increasing same quantify comparing to response change of each element. So the dynamic response of the entire system shows different. Therefore this study performs the static and the dynamic characteristic explanation of entire system and each element for using air-conditioning system of solar energy based on the performed result from now on, so for application of this result.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.1530-1535
• /
• 2009

The cable bolt is useful underground space support system such as mining in Europe. In spite of favorable strength characteristics, past record of the cable bolt is rarely in Korea. In this study, to evaluate the mechanically characteristics the cable bolt on tunnel support system. To conduct the laboratory strength test in order to enquire material properties as reinforcement material and numerical analysis was performed considering laboratory test results. To estimate the behavior characteristics on tunnel system in which supported by the cable bolt system and compared the behavior characteristics with the rebar rock bolt system result.

• Journal of Biomedical Engineering Research
• /
• v.15 no.1
• /
• pp.57-62
• /
• 1994

The demand of image compression is increasing now for the integration of medical images into the hospital information system. Even though the quantitative distortion can be measured from the difference between original and reconstructed images, it doesn't include the nonlinear characteristics of human visual system. In this study, we have evaluated the nonlinear characteristics of human visual system and applied them to the compression of medical images. The distortion measures which reflect the characteristics of human visual system has been considered. This image compression procedure consists of coding scheme using JND (Just Noticeable Difference) curve, polynomial approximation and BTC (Block Truncation Coding). Results show that this method can be applied to CT images, scanned film images and other kinds of medical images with the compression ratio of 5-10:1 without any noticeable distortion.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.6
• /
• pp.449-457
• /
• 2011

Effect of pump combinations on the vacuum characteristics of vacuum system was simulated for optimum design of system. In this investigation, the feasibility of modelling mechanism for VacSimMulti simulator was proposed. Simulation results of various pumping combinations showed the possibilities and reliabilities of simulation for the performance of vacuum system in specific semiconductor processing. Simulation of roughing pump presented the expected pumping behaviors based on commercial specifications of employed pumps. Application of booster pump exhibited the high pumping efficiency for middle vacuum range. Combinations of optimum backing pump for diffusion and turbo vacuum system were obtained. And, the predictable characteristics of process application of both simulated systems were also acquired.

• Journal of Power System Engineering
• /
• v.10 no.1
• /
• pp.90-95
• /
• 2006

Pneumatic control systems have been mainly used as a high speed operating system. Therefore, state change of air in a control volume was assumed to be adiabatic change and, pneumatic control systems have been analyzed by using this assumption. Especially, when absolute value of pressure change in the control volume is small, there is a tendency to neglect effect of temperature change on pneumatic control system because temperature change owing to pressure change is small. In this study, an effect of temperature change of air on the decompression control process was analyzed by considering change of mass flow rate, and heat transfer characteristics between air in the chamber and the chamber wall. As a result, this study could confirm that a slight temperature change of the air in the pneumatic pressure control system can influence on the dynamic characteristics of pressure response, and pressure control performance.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.11 no.1
• /
• pp.40-49
• /
• 2003

Dynamic characteristics of water hammer arresters installed in a building water supply system have been investigated numerically by utilizing a commercial code that employs the method of characteristics. Some preliminary results with those arrester models produced in this study agree well with the previously reported. Then, the arrester models have been incorporated into a water supply pipe system of a 59 $m^2$apartment unit constructed by a leading construction company, and their dynamic characteristics have been investigated, especially on the reduction in the water hammer pressure. It is found that the setting of the arresters in the pipe system, which is recommended by the company, may not be proper for reducing the pressure down below 1,082.0 kPa (10.0 kg$g_f$/$cm^2$) when quick-closure valves in the pipe system are closed within 30 ms at the static pressure of 542.6 kPa (4.5 kg$g_f$/$cm^2$). More arresters in the system may be required to meet pressure criteria stated on the related standards and codes.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.20 no.4
• /
• pp.191-204
• /
• 2009

It is essential to estimate and evaluate for user satisfaction and quality management of database system, understanding of user needs and quality characteristics. Based on ISO 25000 series, it was suggested, the first research, that 5 main quality characteristics, 21 sub quality characteristics and 48 internal quality characteristics. There are comparative significance methods of main quality characteristics, sub quality characteristics and internal quality characteristics but it is not easy to use directly quality model in database system industry field. Also, Considering time and cost in quality evaluation, it is impossible to evaluate 48 internal quality characteristics and its level of quality evaluation is not equal in accordance with integrity level of database system. By using AHP, this study presents selection method of quality characteristics in weight and possibility of application quality model.

• Asia pacific journal of information systems
• /
• v.4 no.2
• /
• pp.35-61
• /
• 1994

Accounting information system is the most important and formal subsystem of the total information system of an organization which produces and delivers financial information. An organization has its own contigent characteristics. It is the key to a successful development of accounting information system to select the development mode and information characteristics appropriate for the contigent characteristics. The main purpose of this study is to analyze the relationship between the contigent factors and the development mode of accounting information system. In addition, this study will examine the relationship between the contigent variables and the information characteristics of accounting information system. The research method adopted in this study is the survey. The results show that the environmental uncertainty, organization size, task diversity, task interrelatedness, and management commitment are positively related with the involvement and role of user in the system development process. The aggregate information regarding various departments tends to be produced by an organization under the uncertain environment. The information is reported periodically by a centralized organization. The aggregate information is preferred when tha task for implementation is diversified. The output information is more aggregate and provided more frequently when there exists a high interrelatioship between tasks. The output information is more external and reported more frequently in an organization with the high management commitment.