• Journal of the Korean Society for Nondestructive Testing
• /
• v.31 no.3
• /
• pp.287-293
• /
• 2011

The enamel, the upper layer of a tooth has remarkable capability of bearing severe loading on the tooth. The fracture behavior is important to understand the mechanism of load bearing and it could be very useful for developing new materials. Non-destructive evaluation of such materials will also benefit from this knowledge. The graded microstructures of enamel were modeled by finite element analysis software and the J-integrals and the stress intensity factors were evaluated as the fracture parameters. The results show that these parameters are location dependent. Those values increase when measured in the direction of dentine enamel junction. This finding matched well with experiments and implies many useful understanding of biomaterials and applications to new materials.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.24-27
• /
• 2002

The environmental problems by using coolant demanded the new cooling methods. As one of them, the studies on the finding with compressed cold air and oil mist have been done. The cooling method using compressed cold air was effective through going down the temperature of compressed air supplied below $-25^{\circ}$ and increasing the amount of compressed cold air, but had not enough cooling effect due to the low performance of lubrication. Therefore, the cooling methods using oil mist newly were suggested. This method can satisfy both cooling effect and lubrication with only small amount of coolant, also have the benefit in the point of decreasing the environmental pollution. This paper focused on analyzing the grinding characteristics of the cooling method using oil mist. The grinding test according to compressed cold air, oil mist spray pressure and oil mist supply direction were done.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.1
• /
• pp.122-133
• /
• 1998

This paper presents the static analysis, the modal analysis and the forced vibration analysis on engine structures to find out the structure-borne noise sources by finite element method. The deformation of engine structures under the maximum combu- stion gas force was calculated through the static analysis, and the resonance possibilities were predicted by the modal analysis which ascertains mode shapes and the corresponding frequencies of engine global and its major noise sources in engine surfaces were investigated with the forced vibration analysis by means of finding the transfer mobilities on engine surfaces due to the piston impact and the velocity levels due to the combustion in consideration of oil film stiffness and damping coefficients. Finally, the direction of engine structure-borne noise reduction can be estabilished by the above-mentioned analysis procedure and the reduction effect of cost on proto-type engine build-up is expected.

• Archives of design research
• /
• v.6 no.1
• /
• pp.1-10
• /
• 1993

This paper described design as a purposeful human activity for solving its problems. This means, problem solving is finding a way to get from some initial situation to a desired goal.In order to do this, like a voyage, there should be a compass, and a route map to guide the designer through the design process. Evaluation gives information about the way a design is proceeding and suggests the direction in which change should be made in order that the complex of design concepts should be fulfilled in a satisfactory manner.I think Pugh's total design model discussing in this paper takes a layered approach through a series of sequential actions, part of which is to find the product status. Each layer has the $$\mu$ti-dimensional elements, Product Design Specification (PDS) around the design core. I made a comparative study of several evaluation tools wi th Pugh's model and examined the criteria for evaluation and the rating / weighing methods.It needs, however, more study in order that PDSs may have its values and be fixed from the dynamic design concepts.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.1
• /
• pp.193-200
• /
• 2003

This paper proposes a novel algorithm to recognize the curve of a structured road. The proposed algorithm uses an LCF (Lane Curve Function) obtained by the transformation of a parabolic function defined on world coordinate into image coordinate. Unlike other existing methods, the algorithm needs no transformation between world coordinate and image coordinate owing to the LCF. In order to search for an LCF describing the lane best, the differential comparison between the slope of an assumed LCF and the phase angle of edge pixels in the LROI (Lane Region Of Interest) constructed by the LCF is implemented. As finding the true LCF, the lane curve is determined. The proposed method is proved to be efficient through various kinds of images, providing the reliable curve direction and the valid curvature compared to the real road.

• Journal of KIISE:Databases
• /
• v.27 no.2
• /
• pp.238-246
• /
• 2000

The distance join has been introduced previously, which finds nearest pairs in the order of distance incrementally among two spatial data sets built with multidimensional indexes like R-trees. We propose efficient K-distance joins when the number(K) of pairs to find is preset. Especially, we develop a distance join algorithm with bi-directional expansion and optimized plane sweeping using selection method of sweep axis and direction. The experiments on real spatial data sets show that the proposed algorithm is much better than the former algorithms.

• Proceedings of the KIEE Conference
• /
• 1992.07a
• /
• pp.70-73
• /
• 1992

With regard to the supply of electric power in better quality, the problem of lightning is becoming more and more important in the operation of an electric power system. In this article a description is given of the new lightning position and tracking system which will be installed in KEPCO. The system is based on the principle of time-of-arrival (TOA) rather than the conventional direction-finding (DF) method.

• Journal of Ocean Engineering and Technology
• /
• v.16 no.6
• /
• pp.37-43
• /
• 2002

The calculation of earthwork plays a major role in the plan or design phase of many civil engineering projects, such as seashore reclamation; and thus, it has become very important to improve upon its accuracy. There have been common drawbacks to earlier methods of ground profiling, such as dialing with sharp corners or the grid points of any tow straight lines. In this paper, we prepose an algorithm for finding a terrain surface using the natural boundary conditions and the both direction spline method, which interpolates the given three-dimensional data by using spline. As a result of this study, the algorithm of the proposed two methods to estimate pit excavation volume should provide a better accuracy than Spot height, Chambers, Chen, or Lin method. Also, the mathematical model mentioned offers maximum accuracy in estimating the volume of a pit excavation.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2002.11a
• /
• pp.200-204
• /
• 2002

본 논문에서는 통신대역에서 실용화 단계에 있는 디지털 고해상도 방탐 알고리즘의 장점들과 MW대역 전자전장비의 요구사항을 효과적으로 절충하여 MW대역에서 운용 가능한 디지털 방탐 알고리즘을 도출하고 고해상도 및 무 모호성을 가지는 MW디지털 방탐 장치의 최적 시스템 구조를 제안하였다. 또한, 제안된 방탐 시스템에 MUSIC 기법을 탑재하여 실제와 유사한 상황에서 수행한 컴퓨터 시뮬레이션을 통하여. 제안된 시스템의 유용성을 입증하였다.

• The Mathematical Education
• /
• v.48 no.1
• /
• pp.33-45
• /
• 2009

The purpose of this article is to study characteristics of Soma Cube in combinatorial-geometric point of view, and to present basic substances and direction for efficient Soma cube activities in school mathematics upon systematical analysis of methods of finding solutions using Inclusion-Exclusion Method. We can apply Inclusion-Exclusion Method to find all possible solutions in Soma Cube activities not as trial-and-error method but as analytical method. Because Inclusion-Exclusion Method can reduce the number of problem-solving variables by making high conjunction in the choice of pieces. Soma cube pieces can be sorted as 'flat' ones and 'non-flat' ones, which would be another effective method in the manipulation of Soma Cube pieces.