• 대한산업공학회지
• /
• 제28권1호
• /
• pp.1-13
• /
• 2002

We study a multi-component production/inventory system in which individual components are made to meet various demand types. We assume that the demands arrive according to a Poisson process, but there is a fixed probability that a demand requests a particular kit of different components. Each component is produced by a flow line with several stations. The production of each component is operated by the CONWIP control mechanism. To analyse this system, we propose an approximation method based on aggregation method. In application of the aggregation method, a product-form approximation technique as well as a matrix-geometric method is used. Comparisons with simulation show that the approximation method provides fairly good results.

• Structural Engineering and Mechanics
• /
• 제5권5호
• /
• pp.529-539
• /
• 1997

This paper deals with the bending problem of a variable-are-length elastica under moment gradient. The variable are-length arises from the fact that one end of the elastica is hinged while the other end portion is allowed to slide on a frictionless support that is fixed at a given horizontal distance from the hinged end. Based on the elastica theory, exact closed-form solution in the form of elliptic integrals are derived. The bending results show that there exists a maximum or a critical moment for given moment gradient parameters; whereby if the applied moment is less than this critical value, two equilibrium configurations are possible. One of them is stable while the other is unstable because a small disturbance will lead to beam motion.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
• /
• pp.614-617
• /
• 2006

This study investigates the quality control and the finishability improvement properties of durable marine concrete under construct in Geo-je Ka-duk fixed link project. Below $3.5\times10^{-12}m^2/s$ chloride migration coefficient and above 40MPa compressive strength are required for the caisson structure concrete. The quality control was performed from physical-chemical analysis of raw materials to concrete test. Also, the efficiency of vibration type and action interval were tested to remove the entrapped air on the faced to form. And kinds of form and remolding agent were also tested. This paper aim to enhance the practical use of high performance concrete to construction field.

• Journal of Advanced Marine Engineering and Technology
• /
• 제36권7호
• /
• pp.927-934
• /
• 2012

This paper suggests a new fuzzy PID controller with variable parameters which improves the shortage of the fuzzy PID controller with fixed parameters suggested in [9]. The derivation procedure follows the general design procedure of the fuzzy logic controller, while the resultant control law is the form of the conventional PID controller. Therefore, the suggested controller has two advantages. One is that it has only four fuzzy linguistic rules and analytical form of control laws so that the real-time control system can be implemented based on low-price microprocessors. The other is that the PID control action can always be achieved with time-varying PID controller gains only by adjusting the input and output scalers at each sampling time.

• 제어로봇시스템학회논문지
• /
• 제6권4호
• /
• pp.276-284
• /
• 2000

In this paper, the genetic algorithm is used to design a mixed H₂/ H/sub ∞/ controller Two kinds of controller forms, Youla's form and the general form, are considered to design a mixed H₂/ H/sub ∞/ controller. Efficient searching methods are sought to minimize the given H₂cost function under the H∞ constraint. It is verified by an example that the developed algorithm can provide stable results in the region where unstable results are shown by the conventional gradient method.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.401-410
• /
• 2007

Form the application of long rail system the non-ballast steel plate bridges, fatigue strength increase and rail noise reduction can be expected. This is mainly form the reduction of the rail impact at the rail joint locations which already made to behave together from welds. In the high speed rail, application of long rail system is essential because without long rail system, the required serviceability level can not be achieved. But even with this long rail systems, the thermal expansion from the girder can not be absorbed in the normal bearing systems, and these expansion cause between girder and rail. Also unexpected rail buckling and fracture through rail thermal tension may happen. It was found through numerical analysis and field measurement that these problems can be avoided by semi-fixed bearing system. In this study, the benefits of non-ballast plate bridge through long rail system, especially at the point of girder stability, girder stiffness increase and bearing maintenance will be reviewed.

• 조명전기설비학회논문지
• /
• 제23권11호
• /
• pp.28-33
• /
• 2009

Average torque of PMa-SynRM(Permanent Magnet-assisted Synchronous Reluctance Motor) is changed by magnet form inserted to the barrier. Because the magnet structure inserted to the barrier influences to the magnet-torque and reluctance torque. Therefore, this paper present a suitable permanent magnet form design for maximum torque when the magnet quantites are always fixed. And each motor characteristic such as average torque, torque ripple, cogging torque and back-EMF are analyzed by FEM(Finite Element Method) for optimal design.

• Korean Journal of Mathematics
• /
• 제16권4호
• /
• pp.481-494
• /
• 2008

Iteration functions $K_m(z)$ and $U_m(z)$, $m{\geq}2$are defined recursively using the determinant of a matrix. We show that the fixed-iterations of $K_m(z)$ and $U_m(z)$ converge to a simple zero with order of convergence m and give closed form expansions of $K_m(z)$ and $U_m(z)$: To show the convergence, we derive a recursion formula for $L_m$ and then apply the idea of Ford or Pomentale. We also find a Toeplitz matrix whose determinant is $L_m(z)/(f^{\prime})^m$, and then we adapt the well-known results of Gerlach and Kalantari et.al. to give closed form expansions.

• Communications for Statistical Applications and Methods
• /
• 제10권1호
• /
• pp.247-256
• /
• 2003

In this study, we systemize the theoretical validity for applying RRM to three-stage cluster sampling method and derive the estimate and it's variance of sensitive parameter. We derive the minimum variance form under the optimal values of the subsample sizes when the costs are fixed. Under the some given precision, we obtain the optimal values of the subsample sizes and derive the minimum cost form by using them. We apply the three-stage cluster RRM to field survey and suggest some necessary points for practical use.

• 구강회복응용과학지
• /
• 제22권3호
• /
• pp.243-250
• /
• 2006

Due to high esthetic demands from patients, we are driven to fabricate natural-looking(form and color) restorations. In the past decade, the glass-ceramic in dentistry has been used as a material with variable crystals that affects the appearance, characteristics, and mechanical properties of metal-free fixed restoration. The conventional IPS Empress glass-ceramic is a heat-pressed, leucite reinforced material using the "lost wax" principle. This glass-ceramic has been successfully used for esthetic restorations such as all-ceramic crowns, inlays/onlays, and veneers for about 15 years. This article presents that the form and surface texture of clinical crown are duplicated by IPS-Empress system using "lost-wax technique".