• 제어로봇시스템학회논문지
• /
• 제14권6호
• /
• pp.554-557
• /
• 2008

We analyze the stability property of a class of nonlinear time-delay systems with time-varying delays. We present a time-delay independent sufficient condition for the global asymptotic stability. In order to prove the sufficient condition, we exploit the inherent property of the considered systems instead of applying the Krasovskii or Razumikhin stability theory that may cause the mathematical difficulty of analysis. We prove the sufficient condition by constructing two sequences that represent the lower and upper bound variations of system state in time, and showing the two sequences converge to an identical point, which is the equilibrium point of the system. The simulation results illustrate the validity of the sufficient condition for the global asymptotic stability.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
• /
• pp.168-172
• /
• 1993

As the worst-case analysis for interval plants, a conjecture whether the supremum of the integral of square error(ISE) is attained at the extreme point such as vertices, Kharitonov vertices, CB segment, and edges is suggested. We present a sufficient condition for which the worst performance index occurs at one ofvertices of uncertain parameter space. Numerical examples are also given.

• 교육시설
• /
• 제17권4호
• /
• pp.3-12
• /
• 2010

In this paper, a current condition analysis of a certified environmentally-friendly school and a school forest demonstration school was made to understand how they have developed effective ecological environments and examine their specific technical methods for ecological planning. After taking into account the differences and current situations of the two types of schools this paper will present an effective method for the suitable implementation ecological environmental projects in domestic schools.

• 한국공작기계학회논문집
• /
• 제17권1호
• /
• pp.77-85
• /
• 2008

The objective of the study is to construct a sensor fusion system for tool-condition monitoring (TCM) that will lead to a more efficient and economical drill usage. Drill-wear monitoring has an important attribute in the automatic machining processes as it can help preventing the damage of tools and workpieces, and optimizing the drill usage. In this study, we present the architectures of a multi-layer feed-forward neural network with Levenberg-Marquardt training algorithm based on sensor fusion for the monitoring of drill-wear condition. The input features to the neural networks were extracted from AE, vibration and current signals using the wavelet packet transform (WPT) analysis. Training and testing were performed at a moderate range of cutting conditions in the dry drilling of steel plates. The results show good performance in drill- wear monitoring by the proposed method of sensor fusion and neural network analysis.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1997년도 추계학술대회논문집
• /
• pp.24-27
• /
• 1997

In the present work, rigid-plastic continuum elements employing the shape change and anisotropic effects are derived for the purpose of applying more realistic blankholding force condition in three-dimensional finite element analysis of sheet metal forming process. In order to incorporate the effect of shape change effectively in the derivation of finite element equation using continuum element for sheet metal forming, the convected coordinate system is introduced, rendering the analysis more rigorous and accurate. The formulation is extended to cover the orthotropic material using Hill's quadratic yield function. For the purpose of applying more realistic blankholding force condition, distributed normal and associated frictional tangent forces are employed in the blankholder, which is pressed normal and associated frictional tangent forces are employed in the blankholder, which is pressed against the flange until the resultant contact force with the blank reaches the prescribed value. As an example of sheet metal forming process coupling the effect of planar anisotropy and that of blankholding boundary condition, circular cup deep drawing has been analyzed considering both effects together.

• 한국농촌건축학회논문집
• /
• 제16권1호
• /
• pp.53-61
• /
• 2014

The purpose of this study is to analyze present condition and users' behavior on waterfront in local city. To analyze the current physical statues and behavioral issues, 3 cities including Jinju city(Nam river), Ulsan city(Taewha river), and Dae-gu city(Gumho river) has chosen as research areas, the questionnaire and field survey were conducted in research areas focusing on post occupancy evaluation. In this study, it was found that main behaviors of waterfront were rest and exercise and overall satisfactions of waterfront were related to the decision-making for revisitation. However, unsatisfactory physical factors of waterfront were the position and number of facilities related to the behaviors such as rest, exercise, and bicycle riding. Especially, most unsatisfactory factor was the inadequate lighting in respect of intensity of illumination and position although much people had been used each waterfronts at nighttime. In conclusion it was thought that it was necessary to reinforce the program related to culture and leisure such as public performance and to establish infrastructure related to life-time sport and various outdoor exercise for waterfront activation.

• 대한기계학회논문집B
• /
• 제33권6호
• /
• pp.403-410
• /
• 2009

This paper proposes a new approach to find the optimum ratios between sizes of the heat exchangers of the heat recovery steam generator (HRSG) system with limited size to maximize the efficiency of the steam turbine (bottom) cycle of combined cycle power plants (CCPP), but without performing the bottom cycle analysis. This could be achieved by minimizing the unavailable exergy (the sum of the destroyed and the lost exergies) resulted from the heat transfer process of the HRSG system. The present approach is relatively simple and straightforward because the process of the trial-and-error method, typical in performing the bottom cycle analysis for the system optimization, could be avoided. To demonstrate the usefulness of the present method, a single-stage HRSG system was chosen and the optimum evaporation temperature was obtained corresponding to the condition of the maximum useful work. The results show that the optimum evaporation temperature based on the present exergy analysis appears similar to that based on the bottom cycle analysis. Also shown is the dependency of size (NTU) ratios between the heat exchangers on the inlet gas temperature, which is another important factor in determining the optimum condition once overall size of the heat recovery steam generator is given. The present approach turned out to be a useful tool for optimization of the singlestage HRSG systems and can easily be extended to multi-stage systems.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2008년도 추계학술대회 논문집
• /
• pp.359-362
• /
• 2008

Middle domestic the occurrence size which stews recently from the Korean Peninsula circumference country is augmenting on a large scale about earthquake about safe countermeasure part from the existing Natural Countermeasure Law 2008. Refers with the Earthquake Disaster Countermeasure Law to be new standard contents establishment by law and strengthened in March. Consequently the research is propelled about electric equipment earthquake-proof plan and countermeasure. The present paper investigated an equipment by domestic facility present condition about the change disappointment electric equipment which can supply all the member in the building an investigation analysis about problem point and improvement fact. Also about overseas electric equipment investigated about earthquake-proof plan relation system and facility present condition. Investigated the electric equipment earthquake-proof plan pertinent data which is advanced from like this existing nation and the equipment and application direction must apply to domestic presented. With character presents following the guide about electric equipment earthquake-proof plan becomes feed with the fact that will be able to use.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2010년 춘계학술대회논문집
• /
• pp.5-9
• /
• 2010

A numerical wind tunnel simulation is performed in order to predict wind loads acting on a building. The aim of the present study is to suggest a guideline for the numerical wind tunnel analysis, which could provide more detail wind load distributions compared to the wind code and expensive wind tunnel experiments. To validate the present numerical simulation, wind-induced loads on a 6 m cube model is predicted. Atmospheric boundary layer is used as a inlet boundary condition. Various effect of numerical methods are investigated such as size of computational domain, grid density, turbulence model and discretization scheme. The appropriate procedure for the numerical wind tunnel analysis is suggested through the present study.

• 연구논문집
• /
• 통권26호
• /
• pp.43-50
• /
• 1996

Present paper describes on/off design performance analysis of an 74KW industrial turboshaft gasturbine engine. Procedures to match between the compressor, combustor and turbine have been incorporated into the developed program satisfying compatibility requirement of flow and work and ratational speed. The validity of the performance results from the developed program are yet to be proved through performance experiments of the resultant engine, but comparison of the present results with those from "GASCAN(Thermoflow:America) under similar mass inlet flow, pressure ratio, and speed condition show good agreement despite present results underpredict 6-10% for power and up to 3% in efficiency, respectively.