• The Journal of Korean Society for Radiation Therapy
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• v.10 no.1
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• pp.69-77
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• 1998

When a high energy photon beam is used to treat lesions located in the upper respiratory air passages or in maxillary sinus, the beams often must traverse an air cavity before it reaches the lesion. Because of this traversal of air, it is not clear that the surface layers of the lesion forming the air-tumor tissue interface will be in a state of near electronic equilibrium; if they are not, underdosing of these layers could result. Although dose corrections at large distances beyond an air cavity are accountable by attenuation differences, perturbations at air-tissue interfaces are complex to measure or calculate. This problem has been investigated for 4MV and 10MV X-ray beams which are becoming widely available for radiotherapy with linear accelerator. Markus chamber was used for measurement with variouse air cavity geometries in X-ray beams. Underdosing effects occur at both the distal and proximal air cavity interface. The magnitude depended on geometry, energy, field sizes and distance from the air-tissue interfaces. As the cavity thickness increased, the central axis dose at the distal interface decreased. Increasing field size remedied the underdosing, as did the introduction of lateral walls. Fellowing a $20{\times}2{\times}2\;cm^3$\;air\;cavity,\;4{\times}4\;cm\;field\;there\;was\;an\;11.5\%\;and\;13\%\;underdose\;at\;the\;distal\;interface,\;while\;a\;20{\times}20{\times}2\;cm^3\;air\;cavity\;yielded\;a\;24\%\;and\;29\%$ loss for the 4MV and 10MV beams, respectively. The losses were slightly larger for the 10MV beams. The measurements reported here can be used to guide the development of new calculation models under non-equilibrium conditions. This situation is of clinical concern when lesions such as larynx and maxillary carcinoma beyond air cavities are irradiated.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.279-290
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• 2010

In this paper, a VOF method called RHRIC (refined high resolution intertace capturing) is introduced for solving the motion of the free surface and applied to the simulation of the advection of rigid interiaces of different shapes and a 20 dam-break problem, which are typical benchmark test cases. The numerical results for the interface advection cases are compared to the analytic solutions, while the available experimental data and other numerical results of various free surface methods for the dam-break problem are provided for the validation of the proposed VOF method. The same simulations were also carried out using the original HRIC scheme and a modified HRIC scheme called MHRIC for comparison. Although the RHRIC uses a simple order scheme, a basis of the original HRIC scheme, lower than the third-order ULTIMATE-QUICKEST used by the MHRIC, it provides an improved accuracy over the two previous HRIC methods.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.97-100
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• 2000

As network resources have become faster and demands for multimedia service through network have increased, the demand for Media server system has increased. These kinds of media server solve their bottle neck problem of internal storage device by using parallel system which takes advantage of fast network resource. Many vendors have suggested each of their media server system to solve these problem radically, but most of them require major modification of infra component and additional drawback has added. For example, storage mechanism for specific media requires new file system which is totally different from traditional one, and algorithm for enhancing performance may not suit for traditional operating system environment. In this paper, we designed a parallel media server based on web interface of traditional system and implemented a program for media server. Implemented server system performs parallel processing through web interface without any modification of traditional system, and controls which is related to merging load by distributed data is charged only to client and control server and consequently load of storage server can be minimized. And also, data transfer protocol for streaming media includes Retransfer algorithm and client Admission control policy relevant to performance of whole system.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.557-564
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• 2001

Many people use Linux and FreeBSD because it is freeware and excellent performance. The open source code is very important feature but it also has some problem which may be attacked by hackers frequently. This paper describes the SecuROS of secure operating system that is best solution to this problem and introduces user and programmer interface for active use of secure operating system. Developed secure operating system is composed of the access control method MAC and ACL and conforms to the POSIX which is universally used.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.61-65
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• 2002

These days, in order to satisfy the complex and various demands of the customers, the telecommunication networks must provide rapid and flexible services, with the support of efficient service and network management systems. To satisfy these requirements, many objects for management have been released to manage network services and elements. But there are no efficient ways to manage these newly managed objects in object-oriented software. Therefore, we study several problems, when a subsystem using object-oriented technique is implemented. The first problem is that interface works between realized application programs using its technique. The second problem is that reusability of internal managed objects is difficult. In this paper, we will point out some problems and to solve these problems, we have proposed the Object Management System (OMS) architecture, which supports a transparent interface between object-oriented applications and the distributed data repositories. Also in order to manage efficient business objects stored in the different repositories, we suggest a method for integrating dynamic information resources in heterogeneous and distributed network environments. Finally, we applied OMS to TINA(Telecommunication Information Network Architecture) domain, implemented OMS, and verified it with SMV(Symbolic Model Verifier) which is model checking technology.

• Journal of the Korean GEO-environmental Society
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• v.3 no.2
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• pp.15-21
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• 2002

Because of the environmental problem during the pile driving, the use of low noise-vibration auger-drilled pilling is increasing to solve noise and vibration problem in pilling. In Korea, SIP (Soil-Cement Injected Precast Pile) method is mainly used as auger-drilled pilling. But, a proper bearing capacity evaluation formula has not been suggested, yet. To improve and supplement this situation, direct shear tests between SIP pile skin interface and soil were executed under various conditions. Through the analysis of test results, skin resistance characteristics of SIP were investigated thoroughly. Also, the maximum unit skin resistance capacity evaluation formulae on SM, SC soil was suggested.

• Journal of Korea Game Society
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• v.11 no.2
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• pp.93-104
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• 2011

For development of physical interactive game recognized as next generation game, this study examines the present situation of physical interactive games and analyzes the problem that game contents lack development compared to the hardware. This paper firstly divides the problem of physical interactive game contents into three parts: demand of the contents and biased game genre, low level of game difficulty, and limited use and/or misuse of the motion controller. Then, the possible solutions for each part are suggested afterward. As the discussion on the development methods in physical interactive game will also develop and therefore, as the next generation game, physical interactive game will play a positive role in th growth of game industry as well as game culture.

• Journal of the Korean GEO-environmental Society
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• v.4 no.1
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• pp.59-66
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• 2003

The environmental problem due to the pile driving, the use of low noise-vibration auger-drilled pilling is increasing to solve noise and vibration problem in pilling. Therefore, in Korea, SIP (Soil-Cement Injected Precast Pile) method is mainly used as auger-drilled pilling. However, a proper bearing capacity evaluation formula has not been suggested, yet. In order to improve and supplement this situation, direct shear tests between SIP pile skin interface and soil were executed under various conditions. Through the analysis of test results, skin resistance characteristics of SIP were investigated thoroughly. Also, the nonlinear unit skin resistance capacity model and relative parameters evaluation formula with SM, SC soil were suggested.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.439-446
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• 2012

This paper presents an implicit moving least squares(MLS) difference method for improving the solution accuracy of 1-D free boundary problems, which implicitly updates the topology change of moving interface. The conventional MLS difference method explicitly updates the moving interface; it requires no iterative solution procedure but results in the loss of accuracy. However, the newly developed implicit scheme makes the total system nonlinear involving iterative solution procedure, but numerical verification show that it dramatically elevates the solution accuracy with moderate computation increase. Through numerical experiments for melting problems having moving singularity, it is verified that the proposed method can achieve the second order accuracy.

• Structural Engineering and Mechanics
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• v.67 no.2
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• pp.185-206
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• 2018

This paper studies the non-axisymmetric 3D problem on the dynamics of the moving load acting in the interior of the hollow cylinder surrounded with elastic medium and this study is made by utilizing the exact equations of elastodynamics. It is assumed that in the interior of the cylinder the point located with respect to the cylinder axis moving forces act and the distribution of these forces is non-axisymmetric and is located within a certain central angle. The solution to the problem is based on employing the moving coordinate method, on the Fourier transform with respect to the spatial coordinate indicated by the distance of the point on the cylinder axis from the point at which the moving load acts, and on the Fourier series presentation of the Fourier transforms of the sought values. Numerical results on the critical moving velocity and on the distribution of the interface normal and shear stresses are presented and discussed. In particular, it is established that the non-axisymmetricity of the moving load can decrease significantly the values of the critical velocity.