• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.147-156
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• 2008

A new approach based on cone prism intersection method combined with sorting algorithm is proposed for the fast and robust signed distance field computation. In the method, the space bounding the geometric model composed of triangular net is divided into multiple smaller cells. For the efficient calculation of distance fields, valid points among the triangular net which will generate minimum distances with current cell are selected by checking the intersection between current cell and cone prism generated at each point. The method is simple to implement and able to achieve an order of magnitude improvement in the computation time as compared to earlier approaches. Further the method is robust in handling the traditional sign problems. The validity of the suggested method was demonstrated by providing numerous examples including Boolean operation, shape deformation and morphing of complex geometric models.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.973-978
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• 2001

Noise reduction has become a major issue of the manufacturing industry. This paper describes the reduction of noise and vibration of rotary compressors. Empirical design for the present strap of the accumulator has been considered to be sufficient for the constraint of the accumulator resonance modes without thorough study. Recently, however, some researchers found out that the accumulator contributes considerably to the sound propagation. In this paper, the contribution of accumulator to the noise propagation is investigated through sound measuring experiments by checking the directivity of the noise. And, experimental modal analysis results show that frequencies of some resonance modes of the accumulator coincide with the highest peaks on sound spectrum. To demonstrate the reason for those resonance modes, a finite element analysis is conducted. Normal mode analysis of the finite element model of the rotary compressor shows the mechanism of the accumulator resonance modes.

• Structural Engineering and Mechanics
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• v.7 no.1
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• pp.1-18
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• 1999

Seismic evaluation of a 32-story reinforced concrete framed tube building is performed by checking damageability, safety, and toughness limit states. The evaluation is based on Standard 2800 (Iranian seismic code) which recommends equivalent lateral static force, modal superposition, or time history dynamic analysis methods to be applied. A three dimensional linearly elastic model checked by ambient vibration test results is used for the evaluation. Accelerograms of three earthquakes as well as linearly elastic design response spectra are used for dynamic analysis. Damageability is checked by considering story drift ratios. Safety is evaluated by comparing demands and capacities at the story and element force levels. Finally, toughness is studied in terms of curvature ductility of members. The paper explains the methodology selected and various aspects in detail.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.384-387
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• 1995

A helicopter is used in a variety of situations because of its usability. Its operation, needs human skill. The authors are working on automatization of human skill. Helicopter operation is one of such fields of practicing human skill. This is why the present paper deals with helicopter (model helicopter) operation. Full operation of a helicopter needs more complicated system in both aspects of software and hardware, and also requires more training for operation. From the purpose here that helicopter operation is for checking the applicability of the authors' idea for automatization based on experience, attitude regulation in hovering is the target. In the present paper, a human operator's operation is recorded as a time series of operation actions, and the record is reorganized as the correspondence between the helicopter's attitude and the proper operation action required in that particular situation.

• Journal of the Korean Society for Railway
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• v.7 no.2
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• pp.114-119
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• 2004

According to the computerization of railway signalling systems. the communication protocol for interface between these systems are required. Therefore the new communication protocol for railway signaling system is required. Generally, there are two verification method for new designed protocol in the industrial and academic fields. One is the laboratory testing method which is very popular and general technique. In our research the comparison between existing and new designed protocol for signaling is described and the verification test results are also represented. From these laboratory test, we are verified the conformance of new designed protocol. Another method is verified by formal method. The format verification method is widely used at safety-critical system design but this approach is nor popular at verification communication protocol. However it is very important to verify the safety of new designed protocol for railway signaling system because signaling systems are very safety-critical systems. So, the methodology for formal verification of designed protocol is also reviews in this paper.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.412-417
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• 2007

The energy efficiency and environment-friendly aspect of the railway system would be superior to other on-land transportation systems. In a preliminary feasibility study stage, the energy efficiency and problems related with environment are usually not considered. Selection of optimal railway line is taken into consideration include of the purpose of railway, geographical features and facility of management. The railway Alignment which could be reasons of environmental problems are focused and studied in this paper. This study performed opinions of specialists, checking of industrial environment, analysis of bid guideline to select the optimal line and executed AHP method to make quality model and choose weight factors. The investment for railway systems could be encouraged by the considering of main environmental elements evaluated with the modified noise and vibration standard for environment-friendly railway construction.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.579-584
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• 1999

The purpose of the present paper are not to develope machine tools of new concepts and advanced mechanisms but to introduce and apply new methods and concepts in the design procedure by using and changing the previously existing technologies. In this paper 3D modeller was proposed for designing machine tools and the design and the better manufacturability checking than 2D one so that design error was dramatically reduced. As designer may easily understand the real shape of a part and assembly object, it's easy to draw the drawings not only in a conceptual design but also in a detailed design. Also, design automation software enabled designer to consider the real important design parameters by reducing time to spend in estimating and calculating the strength of the model by the computer aided automatic calculation instead of a tedious and complex calculation by manual method and help him to easily make the decision for selecting the stocks and design the structure of part or unit of machine tools.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.439-444
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• 2004

A new efficient intelligent machining strategy named the Steepest Directed Tree method is presented in this study, which makes surface model discrete with triangulation meshes and the cutter paths track along the tree directions. In order to formulate these algorithms practically, it is deduced the multi-stage machining approach of uncut volume caused by cutter gouging in the course of milling using flat end mill. It is systematized the checking process the cutter interference by grouping the 6 kinds of gouging types, which yields the environment of connectivity data lists including CL-data, and then the multi-stage machining strategy, that minimizes uncut area by continuously sequencing the generative subsequent CL-paths, is shamed to determine the second tool path for the next uncut area and to compose the operating multi-stage cutting processes. The completed machining system of curved surfaces is evaluated by testing the practical machining experiments which have various kinds of shape conditions.

• Journal of the Korean Institute of Landscape Architecture
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• v.24 no.3
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• pp.29-41
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• 1996

The purposes of this study were to develope some techniques which can be used in the landscape simulation process using PC based computer grahics. As a result, a couple of utilities were programmed in AutoLISP language. The one(DSLINE.LSP) is to digitize 2-dimensional structuer forms in the interactive mode considering error handling, and the other one (IMPOST.LSP) is for superimposing and visualizing the digitized plan data to 3-dimension solids & surfaces referring to topographic elevations of meshes in digital terrain model. By applying utilities to present site, the followings may be described. 1) The utility DSLINE.LSP for digitizing simplified building structure form were proved to be easy to input data of polygons including orthogonal edges by handling user coordinates system and checking invalid intersection and default colsing. 2) IMPOST.LSP utility for superimposing and visualizing tool were proved to be more complicated and speedy in calculating process compared with a practical application of modeling tool before rendering process in landscape simulation of built environment on topographic relief, on specially mesospace level of assessment.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.258-260
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• 1999

The Single Machine Equivalent(SIME) is a hybrid method resulting from the coupling of a time-domain program with the equal-area criterion. This paper presents the efficient filtering algorithm using improved SIME for Transient Stability Assessment. The main feature of the method is cascading contingency filtering. First contingency filtering is conducted by using the first-swing stability of equivalent One Machine Infinite Bus(OMIB) system. This stability is evaluated by checking its time trajectory. Selected cases through the first step are assessed on the second step using SIME under the detailed model of power systems. The efficiency of the algorithm is tested on PSS/E test system.