• Radiation Oncology Journal
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• 제30권1호
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• pp.27-35
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• 2012

Purpose: To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients. Materials and Methods: Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose. Results: Regardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The $V_{20Gy}$ of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%. Conclusion: In this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

• 한국음향학회지
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• 제14권5호
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• pp.58-62
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• 1995

무한배플에 고정된 사각형 진동체에 대한 자기방사 임피던스를 극좌표를 이용한 적분식으로 표시하고 이를 방사저항과 방사 리액턴스로 분리하여 수치해석 하였다. 해석의 결과를 접근방법이 다른 이론식의 결과와 비교하였다. 수치해석의 결과 다른 방법들은 저주파 영역에서 근사식을 사용하여 보정을 해준 반면 본 논문에서 사용된 적분식은 전 주파수 영역에서 제한조건 없이 잘 맞음을 보였다.

• The Journal of the Acoustical Society of Korea
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• 제28권2E호
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• pp.51-59
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• 2009

Mutual radiation impedance becomes more important in the design and analysis of acoustic transducers for higher power, better beam pattern, and wider bandwidth at low frequency sonar systems. This review paper focused on literature survey about the researches of mutual radiation impedance in the acoustic transducer arrays over 60 years. The papers of mutual radiation impedance were summarized in terms of transducer array structures on various baffle geometries such as planar, cylindrical, spherical, conformal, spheroidal, and elliptic cylindrical arrays. Then the computation schemes of solving conventional quadruple integral in the definition of mutual radiation impedance were surveyed including spatial convolution method, which reduces the quadruple integral to a double integral for efficient computation.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제3권1호
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• pp.14-22
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• 2000

The improved Green integral equation for the calculation of time-harmonic potentials in the radiation diffraction problem about a freely floating body in the presence of moderate or weak current is presented. The forward-speed Green function presented by Brard is used. The correct free surface boundary conditions on the physical free surface are employed as well as an appropriate boundary conditions on the non-physical inner free surface. The default in the existing Green integral equation as well as in the source integral equation is discussed in detail.

• Journal of Ship and Ocean Technology
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• 제3권4호
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• pp.1-14
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• 1999

The improved Green integral equation using the Kelvin-type Green function in known free of irregular frequencies where the integral over the inner free surface integral is removed from the integral equation, resulting in an overdetermined integral equation. The solution of the overdetermined Green integral equation is shown identical with the solution of the improved Green integral equation Using the B-spline higher order panel method, the overdetermined equation is discretized in two different ways; one of the resulting linear system is square and the other is redundant. Numerical experiments show that the solutions of both are identical. Using the present methods, the exact values and higher derivatives of the potential at any place over the wetted surface of the body can be found with much fewer panels than low order panel method.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 춘계학술대회 논문집
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• pp.23-28
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• 2000

The Green integral equation for the calculation of the forward-speed time-harmonic radiation-diffraction potentials IS derived. The forward-speed Green function presented by Brard is used and the correct free surface boundary condition for the Green function is imposed. The cause of the mistakes in the existing Green integral equation is also pointed out.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.184-188
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• 2000

The improved Green integral equation of overdetermined type applied to the radiation problem for an oscillating cylinder in the presence of weak current is presented. A two-dimensional Green function for the weak current is also presented. The present numerical solution of the Improved Green integral equation by the B-spline higher order Kelvin panel method is shown to be free of irregular frequencies which are present in the usual Green integral equation.

• Journal of Ship and Ocean Technology
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• 제6권1호
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• pp.34-53
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• 2002

Numerical solution of the forward-speed radiation problem for a half-immersed cylinder advancing in regular waves is presented by making use of the improved Green integral equation in the frequency domain. The B-spline higher order panel method is employed stance the potential and its derivative are unknown at the same time. The present numerical solution of the improved Green integral equation by the B-spline higher order Kelvin panel method is shown to be free of irregular frequencies which are present in the Green integral equation using the forward-speed Kelvin-type Green function.

• 한국소음진동공학회논문집
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• 제20권6호
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• pp.521-527
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• 2010

This article presents a method to calculate the sound radiation of transmission gearbox housing by using Helmholtz integral. Rayleigh integral is used to verify the method. Half-space radiation is considered because the actual gearbox housing is on hard place like concrete. For optimization, orthogonal array is used as a fractional factorial design method. Sound Radiation is calculated with simple source like plate and sphere shape, then actual gearbox BEM model is applied to the method.

• 한국음향학회지
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• 제27권8호
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• pp.411-417
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• 2008

본 논문에서는 헬름홀쯔 적분 방정식에서 유도된 식을 이용하여 구조물의 표면 압력을 구조진동 성분에 대한 단순한 적분형태로 표현하여 음향방사 및 구조/음향 연성 문제를 수치적으로 푸는 방법에 대하여 다룬다. 이 식은 임의의 형상에 대하여 유도된 식으로 Rayleigh 식과 유사한 형태를 갖는다. 이 식을 이용하면 표면 압력을 구조물의 속도에 대한 단순 적분 형태로 나타낼 수 있기 때문에 경계요소법과 같이 연립방정식에 대한 행렬식을 풀 필요가 없다. 또한 헬름홀쯔 적분 방정식에 기반을 둔 다른 방법 들이 가지는 해의 유일성 문제도 갖지 않는 장점이 있다. 본 논문에서는 구형 셀에 대하여 수치해와 정해를 비교하여 제안한 방법의 타당성을 검증하였다.