• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.401-408
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• 2003

A CAD program for metal bellows diaphragm was developed in this study. This program was written in AutoLISP on the AutoCAD system with a personal computer. Basic design concept used in this program is composition of a convolution that is tangent to two lines and 5 circles from given design parameters(initial radius, inner and outer diameter, thickness, pitch, etc.). The effects of altering some design parameters on stress distribution and fatigue life of bellows were estimated using commercial FEM code, NISAII. As a result, the metal bellows diaphragm was successfully designed by the CAD program. It is used to model a bellows geometry in pre-processor of FEM code. The FEM result shows that stress is dependent on straight line length, bellows diameter with same span, and fatigue life is also affected by design parameters.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.288-295
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• 2003

An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the recovery technique. In case of the recovery technique, the SPR(superconvergent patch recovery) approach has been modified for p-adaptive mesh refinement. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly. To verify the proposed algorithm, the limit value approach is proposed which utilizes the exact strain energy computed from the extrapolation equation. A new pre-processor is developed for the p-version finite element program in which the vector graphic editor is used for the automatic generation of node connection and coordinate by halfedge solid data structure according to uniform or nonuniform p-distribution. The general 2-D algorithm is also developed to generate face modes and internal modes in accordance with different mesh types. The quality of the error estimator is investigated with the help of two mumerical examples. The results show that the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.142-147
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• 2009

In the present study, a numerical simulation of passenger evacuation in a subway station was performed. Algorithm for passenger flow analysis based on DEM(Discrete Element Method) has been improved to simulate passenger flow in detailed geometry. The effect of grid density was assessed in the present study to show the advantage of using finer grid in the simulation. The method of coupling passenger flow and fire simulation has also been investigated to analyze passenger evacuation flow under fire. In this method the CO distributions in the subway station was used to assess fire hazards of passenger by means of FED(Fractional Effective Dose) model. Using the coupled algorithm a simulation for passenger evacuation flow and fire analysis were performed simultaneously in the simplified subway station. This algorithm could be used in the design of subway station for the purpose of passengers' safety in case of fire.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.488-493
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• 2011

The object of this study is to develope the program for analyzing the fluid flow and heat transfer of PMSM electric motor. The program will be mainly used for inexperienced users of CFD analysis. So it has to be performed using the geometry data and the heat source of each part only. Interface program for converting the given data to the instruction of pre-processor is developed. The conjugate heat transfer between a flow passage of the motor and inner parts consisting of rotor and stator is regarded. In order to reduce the computational time and memory storage, cyclic boundary condition is applied. For the numerical simulation, MRF(Multi-Reference Frame) method is used to consider rotating operation of the rotor and heat source is applied to the copper, wire, and magnetic parts in the motor. On the screen of computer, the users can show the velocity distributions and the contours such as pressure, turbulent kinetic energy, turbulent dissipation rate and temperature.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.871-876
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• 2006

In this thesis, to accurately measure 3D face information using the spatial encoding patterns, the new algorithm to segment the pattern images from initial face pattern image is proposed. If the obtained images is non-homogeneous texture and ambiguous boundary pattern, the pattern segmentation is very difficult. Furthermore. the non-encoded areas by accumulated error are occurred. In this thesis, the FCM(fuzzy c-means) clustering method is proposed to enhance the robust encoding and segmentation rate under non-homogeneous texture and ambiguous boundary pattern. The initial parameters for experiment such as clustering class number, maximum repetition number, and error tolerance are set with 2, 100, 0.0001 respectively. The proposed pattern segmentation method increased 8-20% segmentation rate with conventional binary segmentation methods.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.14-17
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• 2016

This paper describes the implementation of automatic number-braille converter based on image processing for the blind people. The algorithm is consists of four main steps. First step is binary image conversion of the input image obtained by the camera. the second step is segmentation operation by means of dilation and labelling of the character. Next step is calculation of cross-correlation between segmented text image and pre-defined text-pattern image. The final step is generation of brail output which is relevant to input image. The computer simulation result was showing 91.8% correct conversion rate for arabian numbers which is printed in A4-sheet and practical possibility was also confirmed by using implemented automatic number-braille converter based on DSP image processing board.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.258-262
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• 2007

분포형 수문모형인 WEP(Water and Energy transfer Processes)는 일본토목연구소의 물순환 해석 모형으로써, 짧은 구동시간에도 불구하고 물과 열에너지의 순환을 파악하는 데 효과적인 것으로 알려져 있다, 그러나 모의에 필요한 자료입력 과정이 매우 복잡하고 불편할 뿐 아니라 획득된 결과를 효율적으로 표현하지 못한다는 약점을 가지고 있어 활용도가 높지 않았다, WEP 사용성 향상에 관한 요구가 높아짐에 따라, WEP 전 후처리 프로그램인 WEP+가 개발되었다. WEP+의 개발은 WEP 모형에 대한 방대한 양의 입력 자료를 효과적으로 구축하고, 다양한 기능을 통해 모의 결과에 대한 분석을 용이하게 할 수 있도록 하여 사용자가 직관적으로 모형을 적용할 수 있도록 하는데 그 목적을 두고 있다. WEP+는 기존 WEP의 복잡한 입력과정을 체계화 하여, 사용자가 쉽게 접근할 수 있도록 설계되었으며, 입력 자료의 편집기능을 도입하였다. 또한 복잡하게 연관된 매개변수들의 적합성 여부를 사전에 점검 할 수 있는 기능을 부여하여 모의 도중 오류가 발생하거나 잘못된 모의 결과를 생산할 가능성을 최소화 하고자 하였다. 모의 결과에 대해서는 하천 유출, 지표면 유출, 지하수 유출, 토양수분, 지하수위, 증발산 등 세부 수문요소에 대한 모의 결과를 지점별 시계열과 전체 유역에대한 분포형 자료로 확인할 수 있다. 본 연구에서는 새로 개발된 WEP+ 각 모듈의 기능과 인터페이스를 살펴보고 적용사례를 중심으로 결과분석과 활용방법에 대해 고찰해 보도록 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.509-514
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• 2010

A numerical simulation of passenger evacuation in a subway station was performed by coupling the passenger flow analysis and the fire simulation. The algorithm of the passenger flow analysis was based on a DEM (Discrete Element Method) using the potential map of the direction vector for each passenger. This algorithm was improved in the present study as to use finer grid smaller than a passenger in order to resolve detailed geometry of the station and to resolve the behavior of passengers in the bottleneck at the ticket gate considering the collision of passengers to a wall or with other passengers. In the fire simulation, the CO distribution predicted by using CFD was used to take into account the effect of toxic gases on the passengers' mobility. The methodology proposed in the present study could be used in designing safer subway station in case of fire occurrence.

• The Transactions of the Korea Information Processing Society
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• v.6 no.3
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• pp.804-811
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• 1999

The object-oriented methods are being rapidly accepted as the solution for the software crisis. Object-oriented systems are composed of the integration of independent object modules; their merits are such that it is possible to reuse objects already developed, and that, when changes are required, modifications are restricted to some independent objects such that their affects to other objects are so little. In this paper, we deal with the macro assembler for next-generation microprocessors which has the merits of object methods. Whenever a microprocessor is newly developed, new assembler should be developed or the existing assembler be modified. In the former, it leads to the loss of time and money by the repeated developments, and, in the latter, it causes the problem of inefficient productivity since other modules are to be analyzed for the affections followed by modifications of one module, especially in the existing assemblers. To resolve these problems, the object-oriented macro assembler suggested in this paper consists of independent objects separable such that it shows reusability and reduces the inefficient productivity by minimizing the affects to other objects. Moreover, the object-oriented macro assembler integrates a macro pre-processor into an assembler, and uses automata for analyzing input streams to reduce the compile time.

• The KIPS Transactions:PartA
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• v.9A no.1
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• pp.129-136
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• 2002

JNI is a linkage method to other languages such as C/C++ which enables the Java to do the platform-dependent specific tasks and also, it can be used to reuse the existing libraries and programs. However, the complex and difficult steps are required to use JNI and it is Inconvenient to manipulate Java source and C/C++ source separately. We design and implement the JPP (Java Preprocessor) that enables the Java source and C/C++ source to handle in a same source file and reduces the required steps so as to use JNI easily.