• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.858-863
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• 2003

In the practical engineering fields, the horizontally curved beams are frequently erected as the major/minor structural components. The effects of both variable curvature and variable cross-section on structural behavior are very important and therefore these effects should be included in structural analyses. From this viewpoint, this paper deals with the free vibrations of horizontally curved beams with variable curvature and variable cross-section. In this study, the parabola as the curvilinear shape and stepped beam as the variable cross-section are considered. The ordinary differential equation governing free vibrations of such beams are derived. For calculating the natural frequencies, the governing equations are solved by numerical methods. The Runge-Kutta and Determinant search Methods are used for integrating the differential equations and for calculating the natural frequencies, respectively. With regard to numerical results, the relationships between frequency parameters and various beam parameters are presented in the forms of Table and Figures.

• 전자공학회논문지C
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• 제35C권3호
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• pp.46-58
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• 1998

Multi-disk data allocation problem examined in this paper is to find a method to distribute a Binary Cartesian Product File on multiple disks to maximize parallel disk I/O accesses for partial match retrieval. This problem is known to be NP-hard, and heuristkc approaches have been applied to obtain sub-optimal solutions. Recently, efficient methods have been proposed with a restriction that the number of disks in which files are stored should be power of 2. In this paper, we propose a new disk Allocation method based on Genetic Algorithm(GA) to remove the restriction on the number of disks to be applied. Using the schema theory, we prove that our method can find a near-optimal solutionwith high probability. We compare the quality of solution derived by our method with General Disk Modulo, Binary Disk Modulo, and Error Correcting Code methods through the simulation. The simulation results show that proposed GA is superior to GDM method in all cases and provides comparable performance to the BDM method which has a restriction on the number of disks.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.107-114
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• 2002

This paper deals with the non-linear analysis of cantilever beams with constant volume. Numerical methods are developed for solving the elastica of cantilever ben subjected to a tip Point load and a tip couple. The linear, parabolic and sinusoidal tapers with the regular polygon cross-section are considered, whose material volume and span length are always held constant. The Runge-Kutta and Regula-Falsi methods, respectively, are used to integrate the governing differential equations and to compute the unknown value of the tip deflection. The numerical results obtained herein are shown in tables and figures. Also the shapes of strongest beams are determined by reading the minimum values form the deflection versus section ratio curves.

• 한국정보과학회 언어공학연구회:학술대회논문집(한글 및 한국어 정보처리)
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• 한국정보과학회언어공학연구회 2006년도 제18회 한글 및 한국어 정보처리 학술대회
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• pp.73-80
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• 2006

현재 유니코드에서 한글텍스트의 정규화 기법은 완성형 현대한글 음절과 옛 한글을 표현하는 조합형 한글 그리고 호환 자모등과 같이 사용할 경우 원래의 글자와는 전혀 다른 글자의 조합을 만들어내는 문제점이 있다. 이러한 문제점은 호환 한글 자모 및 기호들의 잘못된 정규화 변환과 유니코드의 한글자모 조합 규칙에서 자모와 완성형 현대한글 음절을 다시 조합하여 한글음절로 사용 할 수 있게 허용한 때문이다. 이는 정규화 형식을 처음 작성할 당시 옛 한글의 사용을 고려하지 않았거나, 한글에 대한 올바른 이해가 부족한 상태에서 작성 된데 따른 결과라 하겠다. 따라서 본 연구에서는 유니코드 환경에서의 한글코드와 특히 최근 들어 Web을 비롯하여 XML과 IDN에서 필연적으로 사용하는 정규화에 따른 문제점을 파악하고 이들을 올바르게 처리하기 위한 정규화의 수정 방안과 조합형 한글의 조합규칙에 대한 수정 방안을 제안한다.

• 한국안전학회지
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• 제11권3호
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• pp.104-111
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• 1996

A system was developed that could predict hazardous states for safe operation of chemical plants. This system aimed to prevent hazards of chemical processes from misoperation before real operation. In this study, a data base was organized which consisted of all hazards in the chemical processes. The structure of process was represented by signed direct graph(SDG) of NODEs and ARCs. Each NODE and ARC have property variables ; connected structure and state of processes etc. The hazards that could be occurred in processes were divided into two classes ; one is by operation of unit and the other is by hazardous materials. Using Hazardous States Transition Network, we could recognize transition progress of process states.

• 한국안전학회지
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• 제18권2호
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• pp.64-72
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• 2003

A new reliability assessment methodology is presented and the new method is compared with fault tree analysis. The system is modeled by directed graph at a new methodology, which is composed of nodes and arcs. The directed graph corresponds to the layout of chemical process and is easy to construct. Therefore, the directed graph analysis is applicable to the chemical process that has complex sequence. The example of fault tree analysis and directed graph analysis is given. The directed graph analysis has proved to be a valuable and useful method for the reliability assessment of chemical process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.63-64
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• 2007

이 논문은 최근 영국기상청에서 올해 엘니뇨현상이 가세하여 세계적으로 가장 무더운 한 해가 될 것이라고 발표하였고, 우리나라 기상청에서도 지구온난화로 지난 100년간 세계는 평균 0.7$^{\circ}C$, 우리나라는 1.5$^{\circ}C$ 상승할 것으로 발표하였다. 이에 따라 전력거래소는 올 여름철 전력수급 전망을 조기에 착수하여 안정적 전력공급을 위한 전력수급 전망 및 대책을 수립하였다.

• 한국정밀공학회지
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• 제15권11호
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• pp.233-243
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• 1998

The demand of high speed machining is increasing due to the high speed cutting and grinding provides high efficiency of process, short process time, improved metal removal capacity and better surface finish. Active magnetic bearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting or grinding. This paper describes a design process of an active magnetic bearing system for a high speed grinding spindle with power 5.5kW and maximum speed 60,000rpm. Magnetic actuators are designed by the magnetic circuit theory considering static load condition, and examined with FEM analysis. Dynamic characteristics are also considered, such as bandwidth, stiffness, natural frequency and static deflection. System characteristics are simulated with a rigid rotor model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.514-517
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• 2005

Microstereolithography(MSL) has evolved from the stereolithography technique, and is also based on a light-induced layer-stacking fabrication. Although integral MSL allows the manufacture of a complete layer by one irradiation only, there is a problem related with shape precision due to the light-intensity distribution of focused image. In this study, we developed the integral MSL apparatus using Digital Micromirror Device ($DMD^{TM})$, Texas Instruments) as dynamic pattern generator. It is composed of Xenon-Mecury lamp, optical devices, pattern generator, precision stage, controllers and the control program. Also, we have studied curing depth and width of photocurable resin according to the change of exposure energy.

• 한국정밀공학회지
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• 제21권9호
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• pp.196-203
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• 2004

SL(Stereolithography) part is made by piling up thin layers which causes the stair stepping effect at the surface of SL parts. The effect brings about excessive surface roughness and cuts down the merits of using SL part. Hence, additional post-machining finishing such as traditional grinding is required. But the traditional post-machining is detrimental to part geometry and time consuming. In this study, therefore, a paraffin coating and grinding post-machining is newly proposed to improve the surface quality of SL fart. The paraffin which has suitable properties for the proposed post-machining is coated all over the part surface. By grinding the only over-coated paraffin based on boundary of the SL part surface, the surface roughness can be improved without any damage on the part. Also, it is verified that SL part finished by the proposed post-machining process can be applied for rapid tooling as pattern through manufacturing silicon rubber molding and casting test.