• 경영과학
• /
• 제12권1호
• /
• pp.111-124
• /
• 1995

With the increasing interest of reducing process variation, statistical process control has served the pivotal tool in most industrial quality programs. In this study, system analyses have been performed associated with a cost incorporated version of a process control, a quadratic loss-based X over bar control chart model. Specifically, two issues, the capital/research investments for improvement of a system and the precision of a parameter estimation, have been addressed and discussed. Through the analysis of experimental results, we show that process variability is seen to be one of the most important sources of loss and quality improvement efforts should be directed to reduce this variability. We further derive the results that, even if the optimal designs may be sensitive, the model appears to be robust with regard to misspecification of parameters. The approach and discussion taken in this study provide a meaningful guide for proper process control. We conclude this study with providing general comments.

• Structural Engineering and Mechanics
• /
• 제4권4호
• /
• pp.365-381
• /
• 1996

Stability equations that evaluate the elastic critical axial load of columns in any type of construction with sidesway uninhibited, partially inhibited, and totally inhibited are derived in a classical manner. These equations can be applied to the stability of frames (unbraced, partially braced, and totally braced) with rigid, semirigid, and simple connections. The complete column classification and the corresponding three stability equations overcome the limitations and paradoxes of the well known alignment charts for braced and unbraced columns and frames. Simple criteria are presented that define the concept of partially braced columns and frames, as well as the minimum lateral bracing required by columns and frames to achieve non-sway buckling mode. Various examples are presented in detail that demonstrate the effectiveness and accuracy of the complete set of stability equations.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2004년도 춘계학술발표회
• /
• pp.765-774
• /
• 2004

This paper presents a damage assesment method for buried pipelines subjected to Deep Excavation-induced ground movements. Ground deformation characteristics resulting from 3D finite element analysis was represented mathematically by a hyperbolic tangential function. A parametric study was performed on excavation depth and burial position of pipeline. The result of the parametric study indicate that length of hyperbolic tangential function affects the results of damage assessment. Using numerical studies for buried pipeline response to ground movements by relative flexibility of the pipe-soil system. The result of numerical studies are presented in forms of design charts which can be readily used for various condition encountered in practices.

• 산업경영시스템학회지
• /
• 제25권4호
• /
• pp.1-7
• /
• 2002

Statistical process control is used widely as an effective tool to solve the quality problems in practice fields. All the control charts used in statistical process control are parametric methods, suppose that the process distributes normal and observations are independent. But these assumptions, practically, are often violated if the test of normality of the observations is rejected and/or the serial correlation is existed within observed data. Thus, in this study, to screening process, the Combined Shewhart - CUSUM quality control chart is described and evaluated that used bootstrap method. In this scheme the CUSUM chart will quickly detect small shifts form the goal while the addition of Shewhart limits increases the speed of detecting large shifts. Therefor, the CSC control chart is detected both small and large shifts in process, and the simulation results for its performance are exhibited. The bootstrap CSC control chart proposed in this paper is superior to the standard method for both normal and skewed distribution, and brings in terms of ARL to the same result.

• 한국국방경영분석학회지
• /
• 제22권2호
• /
• pp.126-138
• /
• 1996

The statistical control chart has been proven to be the effective tool most widely used in the manufacturing industry for monitoring and controlling the manufacturing processes. However, the Shewhart chart sometimes gives us false information when the distribution of quality characteristics is skewed. Therefore, it cannot serve as the universal quality control chart if there exist odd events in the manufacturing process. The objective of this study is thus to develop the new technique for constructing the limits of quality control chart based on a sample median and range when the distribution of the underlying population is skewed. This new control chart can effectively solve and manage the processes which have the non-normally distributed quality characteristics frequently occurring in the practical situation.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 1999년도 가을 학술발표논문집 Vol.26 No.2 (3)
• /
• pp.54-56
• /
• 1999

현재 많은 내장형 시스템을 구현하기 위한 방법론으로 가상 프로토타입(VP)을 이용하고 있다. 본 논문에서는 가상 프로토타입을 이용하여 내장형 시스템의 설계 및 구현을 위해 사용되는 시스템 명세 언어인 SpecCharts로 명세된 시스템을 동기적 의미론에 만족하는 SpecCharts의 Subset을 규명하여 동기화 형태로 해당명세를 변환시키고 이로부터 synchronous VHDL 코드로 생성할 수 있는 방법을 설계하였다. 동기적 의미론을 만족시키기 위하여 비결정적인 추상적인 모델(NDAM)을 이용하여 SpecCharts로부터 VHDL ？로 변환하는 방법을 제시하고, 변환된 VHDL 코드를 동기적 VHDL 코드로 변환하기 위하여 W. Baker에 의해 규명된 동기적 VHDL subset 적용하여 synchronous VHDL 코드를 생성하는 방법을 제안한다.

• International Journal of Quality Innovation
• /
• 제2권2호
• /
• pp.136-144
• /
• 2001

The Markov Chain approach is used to develop an economic adjustment model of a process whose quality can be affected by a single special cause, resulting in changes of the process mean by incorrect adjustment of the process when it is operating according to its capability. The $\bar{X}$ control chart is thus used to signal the special cause. It is demonstrated that the expressions for the expected cycle time and the expected cycle cost are easier to obtain by the proposed approach than by adopting that in Collani, Saniga and Weigang (1994). Furthermore, this approach would be easily extended to derive the expected cycle cost and the expected cycle time for the case of multiple special causes or multiple control charts. A numerical example illustrates the proposed method and its application.

• 산업경영시스템학회지
• /
• 제21권47호
• /
• pp.211-218
• /
• 1998

In start-up process control applications it may be necessary to limit the sample size to one measurement. A control chart for individual measurements is used whenever it is desirable to examine each individual value from the process immediately. A possible option would be to use an exponential weighted moving(EWM), using modifying statistics with individual measurement, chart for monitoring the process center, and using a moving range (MR) chart for monitoring process variability. In this paper it is shown that there is scheme in using the EWM procedure based on average run length. An expression for the ARL is given in terms of an integral equation, approximated using numerical quadrature. In this case, where it is reasonable to assume normality and negligible autocorrelation in the observations, provide graphs that simplify the design of EWM-MR chart and taking method of exponential smoothing constant(λ) and constant(K) are suggested. The charts suggested above evaluate using the conditional probability.

• 한국정보처리학회논문지
• /
• 제7권11호
• /
• pp.3556-3565
• /
• 2000

가상 프로토타입(Virtual Prototyping: VP) 방법론을 이용하면 내장형 시스템을 설계하고 구현할 때에 비용을 절감하면서 제품의 개발기간을 단축할 수 있다. VP는 S/W component, H/W component 그리고 S/W 와 H/W를 연결하는 Interface component로 구성되어 진다. VP의 구성 요소중 H/W component를 구현하는 방법은 여러 가지가 있었으나 시스템 명세 언어로부터는 하드웨어 컴포넌트로 구현하는 방법을 고려하고자한다. 그러나 시스템 명세 언어로부터 생성된 H/W component 용 VHDL 코드는 항상 합성 가능한 코드라고 할 수 없다. 본 논문에선 시스템 명세 언어로부터 검증을 용이하게 하는 하드웨어 구현을 위하여 명세언어로써 SpecCharts를 이용하고 이로부터 동기적 의미론을 만족하는 합성 가능한 VHDL 코드를 생성하는 방법론을 제시한다.

• 소음진동
• /
• 제4권2호
• /
• pp.221-230
• /
• 1994

This paper deals with the dynamic stability and the nonlinear behavior of a check valve system. The nonlinear equations of motion of fluid-valve interation model are derived, which are composed of the unsteady Bernoulli's equation included the jet flow mechanism and equation of motion of a check valve formulated by one degree of freedom. Also, the derived equations of motion are nondimensionalized. According to the change of the nondimensional parameters, the stabilities of the system are analyzed, and the nonlinear interaction responses of the check valve and the passing flow rate are obtained. As the results, the stability charts are constructed for the variation of nondimensional parameters. It is shown that self-excited vibrations exist in a check valve system. And also the Hopf bifurcation and the periodic doubling are found. The presented theoretical model of a check valve system can be utilized to the design and operation of a piping system with the check valve.