• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.207-208
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• 2003

Increasing interest in indoor air quality (IAQ) control has been found because of its serious effect on human health. To evaluate IAQ, thermal comfort in terms of temperature and velocity distributions of indoor air has to be analyzed in detail. Choice of location for installation of air-conditioner in a building will affect the performance of cooling effect and thermal comfort on the occupants, which in turn will affect the indoor air quality (IAQ) of the building. In this paper, we present a discussion on the proper location of the air-conditioner in order to obtain good thermal comfort for occupant of a typical bedroom in Macao. A set of carefully designed numerical experiments is run with the Computational Fluid Dynamics (CFD) software FLOVENT 3.2 [1]. Reynolds averaged Navier-Stokes equations are solved with finite volume technique and turbulence effects upon the mean flow characteristics is modeled with the k - & model. Assumption of steady state environment is made and only convective and conductive heat transfer from the occupant and air-conditioner are being concerned.

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.5
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• pp.39-49
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• 1992

The dynamic design object of rotor system is to optimize the system in stability at the operating speed, unbalance response in the vicinity of the rotor critical speed, bearing weighting and system weighting. In conventional optimization method, designers have to set mathematical modeling, such as objective function, constraints and design parameters, strictly and quantitavely. But in actual design process, they do not treat all of these values strictly and some of them are somehow "fuzziness". So, considering boundary conditions of seal diameter, clearance, and length in a typical double suction centrifugal pump is fuzzy, this paper is considered fuzzy in constraints. Fuzzy method is used .alpha.-level cut method. Then, the optimum dimensions of seal according to values are obtained and vibration characteristics are investigated.estigated.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.420-424
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• 2003

Stacking sequence optimization needs discrete programming techniques because ply angles are limited to a fixed set of angles such as $0^{\circ},\;{\pm}45^{\circ},\;90^{\circ}$. Two typical methods are genetic algorithm and branch and bound method. The goal of this paper is to compare the methods in the light of their efficiency and performance in handling the constraints and finding the global optimum. For numerical examples, maximization of buckling load is used as objective and optimization results from each method are compared.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.90-93
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• 2000

This paper presents job scheduling for non-identical parallel machines using Simulated Annealing (SA). The scheduling problem accounts for allotting work parts of L lots into M parallel machines, where each lot is composed of N homogeneous jobs. Some lots may have different jobs while every job within each lot has common due date. Each machine has its own performance and set up time according to the features of the machine, and also by job types. A meta-heuristic, SA, is applied in this study to determine the job sequences of the scheduling problem so as to minimize total tardiness of due. The SA method is compared with a conventional steepest descent(SD) algorithm that is a typical tool for finding local optimum. The comparison shows the SA is much better than the SD in terms tardiness while SA takes longer , but acceptable time.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.711-712
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• 2002

A numerical study of a hemodynamical model for the tumor angiogenesis is carried out. The tumor angiogenesis process is comprised of a sequence of events; secretion of tumor angiogenesis factor(TAF) from the solid tumor, degradation of the basement membrane of nearby blood vessels, migration and proliferation of the endothelial cells. The model takes into account the effect of TAF concentration and endothelial cell density, and their conservation equations are represented as a set of one-dimensional initial boundary value problems. These equations are discretized by using a finite difference method in which the second order schemes both in time and in space are used. The effects of the parameters contained in the model are Investigated extensively through the numerical simulation of the discretized model. The result for the typical case compares very well with the known result.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.643-652
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• 2006

This paper is concerned with computer simulations of a biped robot walking in static and dynamic gaits. To this end, a three-dimensional robot is considered possessing a torso and two identical legs of a typical design. For such limbs, a set of inverse kinematic solutions is analytically derived between the torso and the feet. Specific walking patterns are off-line generated meeting stability based on the VPCG or ZMP condition. Subsequently, to verify whether the robot can walk as planned in the presence of mass and ground effects, a multi-body dynamics CAE code has been applied to the resulting joint motions determined by inverse kinematics. As a result, the key parameters to successful gaits could be identified including inherent characteristics as well. Upon comparisons between the two types of gaits, dynamic gaits are concluded more desirable for larger humaniods.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1452-1459
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• 2010

Application of long-span bridge, which is affected by parameters such as span length, shoe boundary condition, track property and stiffness of superstructure and substructure etc., can vary. Especially, by CWR aspects of the axial force, that can be less constraints of construction depending on whether the application of rail expansion joint(REJ), which has disadvantaged in terms of maintenance. In this study, it was performed parameter study for multiple variables (shaft length, the upper and lower cross-section characteristics, track characteristics, etc.) in terms of CWR aspects. Structure-rail interaction analysis was applied to the typical simple span PSC Box and 3 span continuous bridge Extradosed Bridge(50m+80m+50m) excluding REJ. If you set the boundary e of variables for long-span railway bridge excluding REJ through the this study, when designing future is expected to be able to useful.

• Journal of Preventive Medicine and Public Health
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• v.20 no.1 s.21
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• pp.40-48
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• 1987

In this paper strategic planning is applied for effective management to improve hospital income. Though community hospital has been set up for improving the health status of community, it must be trying to increase income for continuing with referral hospital in the community. The most useful tool of management to do this purpose is thought of strategic planning. Therefore this paper developed strategic planning a typical community hospital, which for it presenting the strategic planning process and developing the simulation model for evaluation of strategic alternatives. In the result it is represented that admission rate is the most sensitive to hospital operating income among the important variables in the model. And simulation by changing the parameter could estimate the yearly hospital income in the response of alternatives. This strategic planning simulation model has had constraints as number of date but also significance such as evaluating the alternatives by quantitative model and at first applying the hospital in our country.

• Communications for Statistical Applications and Methods
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• v.27 no.3
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• pp.327-347
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• 2020

We consider a credit portfolio with highly skewed exposures. In the portfolio, small number of obligors have very high exposures compared to the others. For the Bernoulli mixture model with highly skewed exposures, we propose a new importance sampling scheme to estimate the tail loss probability over a threshold and the corresponding expected shortfall. We stratify the sample space of the default events into two subsets. One consists of the events that the obligors with heavy exposures default simultaneously. We expect that typical tail loss events belong to the set. In our proposed scheme, the tail loss probability and the expected shortfall corresponding to this type of events are estimated by a conditional Monte Carlo, which results in variance reduction. We analyze the properties of the proposed scheme mathematically. In numerical study, the performance of the proposed scheme is compared with an existing importance sampling method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.2
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• pp.15-22
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• 1980

For efficient coding of graphic image data, the statistical characteristics for both Korean lettered images and English lettered images are measurpd and co mpared. Also, the measured run length distribution is compared with the run length distribution hased on Markov model. It is shown that the measured white run length distribution is more Bike a negative - power distribution than an exponential distribution . This fact is stronger in the Korean lettered images than is the English lettered images, The performances of four typical run length codes are compared for the same set of graphic data files,, and it is shown that the codes perform better in the Korean ]entered images :hart In Eng]isle lettered images.