• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.226-235
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• 1998

This study proposes the analysis and evaluation of method of time series of ultrasonic signal using the chaotic feature extraction for ultrasonic pattern recognition. The features are extracted from time series data for analysis of weld defects quantitatively. For this purpose, analysis objectives in this study are fractal dimension, Lyapunov exponent, and strange attractor on hyperspace. The Lyapunov exponent is a measure of rate in which phase space diverges nearby trajectories. Chaotic trajectories have at least one positive Lyapunov exponent, and the fractal dimension appears as a metric space such as the phase space trajectory of a dynamical system. In experiment, fractal(correlation) dimensions and Lyapunov exponents show the mean value of 4.663, and 0.093 relatively in case of learning, while the mean value of 4.926, and 0.090 in case of testing in slag inclusion(weld defects) are shown. Therefore, the proposed chaotic feature extraction can be enhancement of precision rate for ultrasonic pattern recognition in defecting signals of weld zone, such as slag inclusion.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.193-198
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• 2005

Changes in visuospatial cognitive performance, blood oxygen saturation and heart rate due to the highly concentrated oxygen administration were observed in this study. Six male ($25.8 \pm$1.0) and six female (($23.8 \pm$ 1.9) adults were asked to perform 20 visuospatial tasks with the same level of difficulties by supplying two different oxygen levels (21%, 30%). Experiment consisted of Rest1 (1 min.), Control (1 min.), Task (4 min.), and Rest2 (4 min.) and physiological signals such as blood oxygen saturation and heart rate were measured through each stage. The result showed the accuracy of task performance increased significantly at 30% oxygen concentration compared with 21%, which means oxygen supply has positive effects on visuospatial cognitive performance. When 30% oxygen was supplied, blood oxygen saturation during control and task phases was increased and heart rate was decreased compared with 21%. It means that 30% oxygen can stimulate brain activities by directly increasing the actual level of blood oxygen concentration during cognitive performance, and enough oxygen supply during cognitive performance make heart rate decrease.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.14 no.2
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• pp.159-166
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• 1996

It has the imfortant significance to study of 3 dimensional precision surveying and analysis system for conservation of culutral properties. This study is about to efficient precision surveying methods and analysis of digital information data for conservation of cultral properties. We acquire the photos and construct the 3 dimensional digital information in 1 n accuracy, and carry the spatial analysis to five story pagoda at Chongrimsa temple site of National Treasure No. 9 of Korea. In result, we carry the 3 dimensional modelling accurately and the efficient geometrical analysis of sections, calculation of the aera, volumn, and position and slope of con-trial axis. So, we expect efficient use of as well study of art history as safety diagonise for the preservation of cultural properties.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.387-388
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• 2006

This article provides a dynamic analysis model for huge marine engine that examined analytically variation effects of frequency response by fitting of transverse stays such as hydraulic type. First, vibration analysis using the three dimensional finite element models for the huge marine engine has performed in order to find out the dynamic characteristics. Second, three dimensional finite elements model for the huge marine engine was modifued so that generate forcing nodes in crosshead part and top bracing nodes in cylinder frame part. Third, a system matrix and output matrix was derived for the general siso(single input single out) state space model. Finally, developed state space model for the three dimensional finite elements model for the huge marine engine without the additional modifying process.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.4
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• pp.61-66
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• 2009

This Paper describes a new program called DEM Generator need to process DEM from LiDAR data or digital map data. It is difficult to generate raster DEM from LiDAR mass point data sets and digital maps too large to fit into memory. The DEM Generator was designed to process DEM and shaded relief image of GeoTiff format in order of streaming meshes; I/O minimize tag, delaunay triangle, natural neighborhood or TIN, temporary files and grid. It is expected that we can be improved the precision of DEM and solved the time consuming problem of DEM generating of a wider area.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.1
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• pp.58-64
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• 2001

정밀을 요하는 자동차 부품의 측정 시스템은 온도에 따라 보상이 필수적이다. 부품의 측정값의 신뢰도를 유지하기 위해서 단순히 제품의 합격 영역을 상온에서 51.786~51.819mm로 했을 때, 온도가 상온에서 따러져 있는 경우 그 부품의 측정영역을 신뢰하기가 어려워진다. 본 논문에서는 이 문제를 해결하기 위해서 2개의 카메라를 사용하여 한쪽은 표준 제품을 두고, 다른 쪽은 실제 제품을 둠으로서 온도에 따라 달라지는 표준 제품의 측정값의 Offset를 실제 제품에 반영함으로써 측정값을 보상하려고 하였다. 자동차의 부품은 여러 가지가 있으나, 이 중에서 현재 공장에서 측정에 어려움을 겪고 있는 에어콘 스윗치인 마그네트 코일 하우징을 대상으로 하였다. 특히 측정 대상이 크고, 카메라의 화소수가 40만 이하일 경우, 측정의 중요한 포인트는 화소수와 배경과 대상의 구별이다. 이를 정확히 알아내는데, FCM (Fuzzy C-means) 알고리듬이 좋은 결과를 주지만 속성 공간에서 유사성만을 고려하고, 공간영역에서 유사성은 고려되지 않기 때문에 FCM은 \"equal evidence\"와 \"ignorance\"를 구분하지 못한다. 이를 개선하기 위해서 FCM를 수정하여 먼저 FCM로 처리하고 이를 바탕으로 PCM (Possibilistic C-means)를 사용하였다. 결과를 모니터에 보여주고, RSC-232 포트를 통하여 신호를 마이크로 프로세서에 전달하여 제품의 양호(good), 불량(bad)을 판별하는 신호를 발생하게 하였다.을 판별하는 신호를 발생하게 하였다.

• Communications for Statistical Applications and Methods
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• v.17 no.2
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• pp.263-273
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• 2010

Missing values in time series can be treated as unknown parameters and estimated by maximum likelihood or as random variables and predicted by the conditional expectation of the unknown values given the data. The purpose of this study is to impute missing values which are regarded as the maximum likelihood estimator and random variable in incomplete data and to compare with two methods using ARMA and STAR model. For illustration, the Mumps data reported from the national capital region monthly over the years 2001~2009 are used, and estimate precision of missing values and forecast precision of future data are compared with two methods.

• Journal of Cadastre & Land InformatiX
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• v.51 no.1
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• pp.23-38
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• 2021

In this paper, we analyzed the possibility of utilizing LX-PPS GNSS permanent stations whose antennas are installed on the building rooftop for the purpose of high-precision GNSS positioning services. We picked 15 pairs of adjacent GNSS permanent stations operated by LX-PPS and NGII, and then produced 3-year-long time series using the high-precision data processing software called GIPSY. Patterns and trends of position estimates were compared and analyzed. Horizontal and vertical deviations including the linear velocities coincide with the well-known crustal deformation rates of the Korean peninsula. We also observed almost the same annual or seasonal patterns from those nearby sites. After detrending the linear velocity, the amplitude and phase of annual signals almost perfectly match each other within the baseline length of 2 km. By subtracting seasonal signals, the RMS and standard deviations in LX-PPS PPGR with respect to NGII KANR are about 1, 2, and 5 mm in the north-south, east-west, and vertical directions, respectively. From this analysis it can be concluded that the rooftop-installed LX-PPS sites show similar level of stability and positioning performance comparable to those ground-mounted NGII stations.

• Journal of Korean Society for Geospatial Information Science
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• v.3 no.2 s.6
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• pp.173-181
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• 1995

Geospatial analysis method was applied for classification of suitable site for farmstead. Typical urban suburb and rural area was selected and analyzed, that is Cheongwon County in Chungbuk Province, South Korea. In this study, suitable site for the farmstead was classified by five grade in the other site except suitable area for paddy field, upland, settlement and Green Belt, regulated area for development around the city. Digital Elevation Model(DEM), detailed soil map, administration boundary map, stream map and Green Belt map where digitized and scoring tables were composed with scoring standard. In site verification, Geospatial Information System(GSIS) was quite good tools for suitable site classifying for farmstead causing farm household income increasing, environmental impact decreasing and scientific site selection.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.3 s.37
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• pp.13-22
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• 2006

Realistic 3D building construction in urban area has become an important issue because of increasing demand of 3D geo-spatial information in many application. Contrary to the conventional 3D building model construction approach using aerial images and high-resolution satellite imagery, it has been researched widely in building reconstruction using high-accuracy aerial LIDAR data in the latest. This paper presents a method for 3D building construction through building outlines extraction by LoG operator's Zero-crossing and line generation and refinement by Douglas-Peucker algorithm.