• Radiation Oncology Journal
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• 제9권2호
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• pp.343-350
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• 1991

종양모양에 거의 일치하는 선량분포를 얻기위해 다층부정형필터를 이용하는 방법을 보였으며, 필터의 재질은 Lipowitz (일명 cerrobend alloy) 금속체를 이용하였다. 선속내 필터의 놓임은 일차선의 감쇄와 함께 조직내 산란선 기여율의 변화가 예상되므로 필터의 두께에 따른 SMR의 변화가 계산에 이용되어야 된다. 이에 본 연구의 계산선량은 실측치의 $3\%$이내에서 잘 일치됨을 알 수 있었다. 다층부정형필터를 이용한 펜톰의 원호조사의 선량평 가는 동일 필터에 의한 고정조사의 선량분포가 적용되었으며, 가상종양에 거의 일치하는 선량분포를 얻을수 있었다. 한편, 컴퓨터모의계산된 선량과 열발광산량계(teflon-embedded TLD)의 실측선량은 비교적${\pm}5\%$ 범위내에서 잘 일치됨을 알 수 있었으며, 이 치료방법은 현재 차폐체로 많이 이용되고 있는 Lipowitz 금속체를 사용함으로써 보다 쉽게 응용되어질 것으로 생각된다.

• 한국해양공학회지
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• 제34권6호
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• pp.406-418
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• 2020

In this study, a nonlinear wave simulation code is developed using a higher-order spectral (HOS) method. The HOS method is very efficient because it can determine the solution of the boundary value problem using fast Fourier transform (FFT) without matrix operation. Based on the HOS order, the vertical velocity of the free surface boundary was estimated and applied to the nonlinear free surface boundary condition. Time integration was carried out using the fourth order Runge-Kutta method, which is known to be stable for nonlinear free-surface problems. Numerical stability against the aliasing effect was guaranteed by using the zero-padding method. In addition to simulating the initial wave field distribution, a nonlinear adjusted region for wave generation and a damping region for wave absorption were introduced for wave generation simulation. To validate the developed simulation code, the adjusted simulation was carried out and its results were compared to the eighth order Stokes theory. Long-time simulations were carried out on the irregular wave field distribution, and nonlinear wave propagation characteristics were observed from the results of the simulations. Nonlinear adjusted and damping regions were introduced to implement a numerical wave tank that successfully generated nonlinear regular waves. According to the variation in the mean wave steepness, irregular wave simulations were carried out in the numerical wave tank. The simulation results indicated an increase in the nonlinear interaction between the wave components, which was numerically verified as the mean wave steepness. The results of this study demonstrate that the HOS method is an accurate and efficient method for predicting the nonlinear interaction between waves, which increases with wave steepness.

• 한국CDE학회논문집
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• 제19권2호
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• pp.91-102
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• 2014

The outer surface of an irregular structure contains panels with two-directional curvature called NURBS. To construct these forms of exterior materials, complex geometric surface should be divided into forms and sizes that can be manufactured and constructed. Because the bigger the curvatures of these divided exterior panel, the more expensive the construction costs, these complex two-directional curvatures should go through optimal process of reinterpretation to minimize the curved surfaces with complex two-directional curvatures. Yet, to gain higher ground in technological competition in the field of irregular structure construction, companies do not share know-how that they obtained. Accordingly, small construction and design companies have trouble calculating even rough estimate and cannot adjust expected construction cost based on comparison of design alternatives. Given this situation, this study conducted the research that can support decision-making in the design stage of the construction and provide basic material for optimal range to reduce manufacturing cost by the minimizing the distorted plane of the irregular structure.

• 한국해양공학회지
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• 제22권6호
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• pp.7-12
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• 2008

The present study numerically investigates the effect of the shape of absorbing revetment on wave overtopping rate under regular and irregular incident waves. At first, the numerical model developed by Hur and Choi(2008), which considers the flow through a porous medium with inertial, laminar and turbulent resistance terms, directly simulates Wave-Structure-Sandy seabed interaction and can determine the eddy viscosity with LES turbulent model in 2-Dimensional wave field (LES-WASS-2D), is validated when compared to experimental data. Numerical simulations are then performed to examine the effect of the shape of absorbing revetment and incident wave conditions on wave overtopping rate. The numerical result shows that the wave overtopping rate decreases with the slope gradient of absorbing revetment under both regular and irregular waves. In addition, the effects of mean grain size and porosity of absorbing revetment, incident wave period and crest height on wave overtopping rate are discussed.

• 지질공학
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• 제33권3호
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• pp.439-459
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• 2023

Numerical analysis has been adopted in nearly all modern scientific and engineering fields due to the rapid and ongoing evolution of computational technology, with the number of grid or mesh points in a given data field also increasing. Some values must be extracted from large data fields to evaluate and supplement numerical analysis results and observational data, thereby highlighting the need for a fast and effective interpolation approach. The quadrilateral irregular network (QIN) proposed in this study is a fast and reliable interpolation method that is capable of sufficiently satisfying these demands. A comparative sensitivity analysis is first performed using known test functions to assess the accuracy and computational requirements of QIN relative to conventional interpolation methods. These same interpolation methods are then employed to produce simple numerical model results for a real-world comparison. Unlike conventional interpolation methods, QIN can obtain reliable results with a guaranteed degree of accuracy since there is no need to determine the optimal parameter values. Furthermore, QIN is a computationally efficient method compared with conventional interpolation methods that require the entire data space to be evaluated during interpolation, even if only a subset of the data space requires interpolation.

• 대한안전경영과학회지
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• 제17권1호
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• pp.125-130
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• 2015

Techniques, using physical wedge filter and using dynamic wedge filter and FIF(Field in Field) and ISCT(Irregular Surface Compensating Technique), have been developed according to progress of radiation therapy of breast cancer. Measurement of dose was done to judge the usefulness of technique using three cases, non tissue loss after breast conserving operating and tissue loss after breast conserving operating and mastectomy. Dose indexes of breast tissue, CI (Conformity Index), HI (Homogeneity Index) and QOC (Quality of Coverage), dose index of skin, or dose indexes of lung, volume of 50 percent dose and 20 percent dose were estimated and compared. Using dynamic wedge filter is useful plan at non tissue loss allowing for high dose of lung. FIF and ISCT are useful plan at tissue loss. ISCT is useful plan at mastectomy. Henceforth, we need to apply to valid plan and body type and thorax size.

• 한국정밀공학회지
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• 제15권8호
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• pp.174-182
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• 1998

This paper describes a research work of developing a computer-aided design and machining of irregular shaped-sheet metal product for blanking or piercing operation. An approach to the CAD/CAM system is based on the knowledge-based rules. Knowledge for the CAD/CAM system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD and in customer tool kit on the SmartCAM with a personal computer and is composed of nine modules, which are input and shape treatment, flat pattern-layout, production feasibility check, blank-layout, strip-layout, die-layout, data conversion, modelling, and post-processor module. Based on knowledge-based rules, the system is designed by considering several factors, such as material and thickness of product, complexities of blank geometry and punch profile, diameter and material of a wire, and availability of press. This system is capable of generating NC data automatically according to drawings of die-layout module. Results which are carried out in each module will provide efficiencies to the designer and the manufacturer of blanking or piercing die in this field.

• 대한조선학회논문집
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• 제48권6호
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• pp.539-543
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• 2011

Recently, to reduce the noise and vibration levels of ships, high skewed marine propellers with thinner thickness are adopted widely, however, such propeller design trend causes to reduce the strength of blades. Propeller blades are rotating continuously in irregular wake field of ships. So, it is necessary to examine the strength of them precisely including from a viewpoint of fatigue strength. In present paper, the fatigue strength of propeller blades was investigated. Firstly, fatigue tests for Al Bronze, the representative propeller material, were carried out. The S-N curve was obtained for the assessment of the fatigue crack initiation life. And the material properties C, m for the fatigue crack propagation analysis based on the Paris' equation were derived. For the 2nd stage, the structural responses of propeller blades in irregular ship wake field was carried out using the finite element analysis code. And the fatigue strength of propeller blades were considered based on the calculated stress levels and material characteristics for fatigue strength.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.292-292
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• 2004

There are many difficulties to get the scattered field generated by obstacle which has arbitrary shape or irregular surface impedance by using analytic solution or numerical methods. In this study, we propose experimental method of acoustic scattering holography that can predict the far-field scattered field based on nearfield measurements. First of all, we express scattered field using K-H integral equation and compare the differences of which green's function we use. Also we consider analytic solution of scattered field by infinite cylinder to analysis for the errors due to apply cylinderical holography. So the errors which caused by holography due to frequency (ka) and microphone spacing are also analyzed by numerical simulation.

• 교육시설 논문지
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• 제19권1호
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• pp.37-44
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• 2012

This study developed an algorithm to predict the most efficient evacuation protocol in an elementary school that has an irregular type of architectural planning. The assumption of this study takes a stand point that today's elementary schools are designed in unusual and irregular floor type and, therefore, past architect's knowledge regarding efficient evacuation will no longer effective to save lives. In this regard, this study applied an algorithm that is especially designed to find appropriate locations in general in the field of industrial engineering, which has been proven for many decades. Furthermore, this study not only adapted an engineering model but also conversed to examine spatial relationship and added the concept of group evacuation, which will delay the whole evacuation process, in the tested algorithm to make it more architectural. Consequently, this study compared its outcome with an existing elementary school and questioned its effectiveness in evacuation process based on the algorithm.