• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.252-257
• /
• 2006

Low vibration characteristics of a vehicle are mainly influenced by the local stiffness of the joint structure beam section. The method of substituting equivalent beam element to spring element for the joint is presented. Formation process of the equivalent beam joint modeling is described in terms of key section properties. To get required dynamic characteristics section properties of the equivalent beam element are set to design variables. The study shows that the equivalent beam joint model can be effectively used for low frequency vibration analysis of a vehicle.

• The Journal of Korean Society for Radiation Therapy
• /
• v.2 no.1
• /
• pp.87-92
• /
• 1987

The authors have intended to measure intrinsic dose distribution by Farmer dosimeter in irregularly shaped fields such as L, M, T,-shape model in order to determine dose inhomogeneity in those models. We made 2 off-axis points in each model and measured the depth dose at 1.5,5, and 9cm below surface. The results showed $1-3\%$ dose discrepancy between 2 points. We also measured the depth dose by geometric approximation and computer calculation in those models, and came to the conclusion that computer calculation using Clarkson's principle is simpler and the measurements are to the ideal data obtained by the experiment in those three models of irregularly shaped fields than those of geometric approximation method.

• International Journal of Reliability and Applications
• /
• v.15 no.2
• /
• pp.99-110
• /
• 2014

Based on the kernel function, a new test is presented, testing $H_0:\bar{F}$ is exponential against $H_1:\bar{F}$ is UBACT and not exponential is given in section 2. Monte Carlos null distribution critical points for sample sizes n = 5(5)100 is investigated in section 3. The Pitman asymptotic efficiency for common alternatives is obtained in section 4. In section 5 we propose a test statistic for censored data. Finally, a numerical examples in medical science for complete and censored data using real data is presented in section 6.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.985-988
• /
• 1997

In end milling process, the undeformed chip section area and cutting forces vary periodically with phase change of the tool. However the real undeformed chip section area deviates from the geometrically ideal one owing to cutter runout and tool shape error. In this study ,a method of estimating the real undeformed chip section area which reflects cutter runout and tool shape error was presented in up end milling process using measured cutting forces. Size effect was identified from the analysis of specific cutting resistance obtained by using the modified undeformed chip section area.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.4
• /
• pp.62-72
• /
• 1997

The optical power splitter/couplers based on MMI(multimode interference) in GaAs/AlGaAs are studied. We presetn a design of optical power splitter/couplers, which have deeply etched multimode waveguide. The properties and fabrication tolerance on the etching depth, multimode waveguide width are simulatedusing a FD-BPM (finite difference beam propgation method). Proposed 1*N optical of designed device is 0.7dB smaller than the optical power splitter with a shallowly etched MMI section. For 0.5dB excess loss, the predicted fabrication tolerance is 0.6.mu.m on the multimode waveguide width of the 14 optical power splitter with a deeply etched MMI section. Also excess loss and uniformity of poposed 32*32 optical power coupler are below 0.3dB. The excess loss of proposed 32*32 optical power coupler is 2dB smaller than the optical power coupler with a shallowly etched MMI section. It is shown that the optical power splitters/couplers with a deeply etched mMI section have low loss, good uniformity, and improved fabriction tolerance.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.829-835
• /
• 2007

For constant operation, Electric Railway System has many electrically divided parts of the trolley lines to avoid error spreading. FRP-Section have a role to divide Catenary trolley lines electrically. If one electric train approach to the section at the same time with partial power failure, the pantograph of train can make a short circuit with supplied part to failure part. Electric arc induced with this switching effect, can break FRP-section, and there are such error cases. In this study, we propose one method to prevent FRP-section breakdown from these reason, with detecting sensor at the sectional position.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.479-484
• /
• 2000

In this study, optimal design of reinforced concrete piers under seismic load is numerically investigated. Object function is the area of the concreate-section. Design variables are the total area of reinforcement and concrete-section dimension(Circular section diameter). Constraints of the design strength of the column, longitudinal reinforcement ratio and lower and upper bounds on the design variables are imposed. The reinforcement concrete column is analysed and designed by the Ultimated Strength Design method and load combination involving dead, live, wind and seismic load is used. For numerical optimization, ADS(Garret N, Vanderplaats_ routine is used. From the result of numerical examples, the concrete-section dimension was reduced, but longitudinal reinforcement was not changed. The results show that confinement reinforcement was reduced and confinement reinforcement spacing is increased. The higher strength of reinforcement used, the more concrete-section area was reduced.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.17 no.1
• /
• pp.11-18
• /
• 1980

In the conventional ship's structures, the stiffeners with asymmetric sections have been widely used, in spite of the disadvantage on the point of strength, compared to those with symmetric sections. So far, the stiffened plating was usually analyzed not considering the geometric unsymmetry characteristics of the section, including only the cross sectional area and moment of inertia. In this paper, the stiffened plating is devided into the strips having a thin-walled open cross section by using the concept of the effective width. The geometric characteristics of the sections are also included. The governing equations are derived, which can be applied to the arbitrary cross section beams, and the symmetric and the asymmetric section beams which have the same cross sectional areas are analyzed by using the finite element method. From that result, we obtain the allowable load of the two sections, and compared them.

• Wind and Structures
• /
• v.4 no.4
• /
• pp.315-332
• /
• 2001

Presented herein is a numerical study for evaluating the aerodynamic behaviour of equipped bridge deck sections. In the first part, the method adopted is described, in particular concerning turbulence models, meshing requirements and numerical approach. The validation of the procedure represents the aim of the second part of the paper: the results of the numerical simulation in case of two-dimensional, steady, incompressible, turbulent flow around a realistic bridge deck are compared to the data collected from wind-tunnel tests. In order to demonstrate the influence of the section details and of the partial streamlining of the deck geometry on its aerodynamic behaviour, in the third part of the paper the effect of the fairings and of each item of equipment of the section (such as central barriers, side railings and sidewalks) is evaluated. The study has been applied to the deck section of the Normandy cable-stayed bridge.

• Structural Engineering and Mechanics
• /
• v.34 no.5
• /
• pp.597-609
• /
• 2010

A problem formulation and solution methodology for design optimization of laminated thin-walled composite beams of generic section is presented. Objective functions and constraint equations are given in the form of beam stiffness. For two different problems one for open section and the other for closed section, the objective function considered is bending stiffness about x-axis. Depending upon the case, one can consider bending, torsional and axial stiffnesses. The different search and optimization algorithm, known as Evolution Strategies (ES) has been applied to find the optimal fibre orientation of composite laminates. A multi-level optimization approach is also implemented by narrowing down the size of search space for individual design variables in each successive level of optimization process. The numerical results presented demonstrate the computational advantage of the proposed method "Evolution strategies" which become pronounced to solve optimization of thin-walled composite beams of generic section.