• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.3
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• pp.205-211
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• 2003

Acoustic emission (AE) technique has been applied to not only mechanical property testing but also on-line monitoring of the el)tire structure or a limit zone only. Although several AE devices have already been developed for the on-line monitoring, the price of these systems is very high and it is difficult for the field to apply yet. In this study, wc developed a specially designed PC-based source location system using the A/D board. The source location technique is very important to identify the source, such as crack, leak detection. However, since the AE waveforms obtained from transducers are very difficult to distinguish the defect signals, therefore, it is necessary to consider the signal analyses of the transient waveform. Wavelet Transform (WT) is a powerful tool for processing transient signals with temporally varying spectra that helps to resolve high and low frequency transients components effectively In this study, the analyses of the AE signals are presented by employing the WT analyses. AE results are compared the PC-based source location system using A/D board with the commercial AE system.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.2
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• pp.63-69
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• 2019

In this study, bispectrum analysis method introduced to reduce variability of SEF(spectral edge frequency) and MF(median frequency), which are the anesthetic depth indexes extracted by EEG spectral analysis. Bispectrum analysis is an analytical method that can confirm the nonlinearity of EEG. Signal measurement and analysis in the surgical environment should take into consideration various external artifact factors. Bispectrum analysis can confirm the presence of externally introduced artifacts, thereby effectively eliminating artifacts that affect the EEG signal. By applying bispectrum parameters, real-time variability of the anesthetic depth parameters SEF, MF could be reduced. Elimination of variability makes it possible to use SEF, MF as a real-time index during surgery.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.398-403
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• 2008

The propulsion for locomotive application has changed from the DC motor system to the induction motor system. Although the induction motor system has almost reached the stage of maturity, this system also needs to be changed to the PM motor system for the direct drive without using reduction gear. Thus, the IPMSM (Interior buried Permanent Magnet Synchronous Motor) has been adopted to meet the locomotive driving specification. Where the wheel is directly dirven by the traction motor. In this paper, the investigation on IPMSM satisfying driving specifications for the direct drive has been performed using the advanced FEM.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11c
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• pp.1871-1874
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• 2002

최근 인터넷 환경에서 지리 정보 서비스를 제공받으려는 사용자들의 지속적인 증가로 인해 저비용의 여러 개의 단일 노드를 고속의 네트워크로 연결하여 고성능을 제공하는 클러스터 기반의 공간 데이터베이스에 대한 연구가 활발하게 진행되고 있다. 이러한 공간 데이터베이스 클러스터에서 사용자가 요구한 공간 질의를 빠르게 처리하기 위해서는 고비용의 공간 조인 연산을 효율적으로 처리하기 위한 기법이 요구된다. 본 논문에서는 비공유 공간 데이터베이스 클러스터 환경하에서 공간 조인 연산 수행 시 효율적인 병렬 처리를 위한 영역 분할 기법 및 병렬 공간 조인 기법을 제안한다. 기존의 병렬 공간 데이터베이스 시스템에서의 분할 기반 병렬 공간 조인 기법들은 병렬로 수행할 작업 분배 및 할당과 분할 경계선 상에 존재하는 공간 객체들에 대한 중복 조인 연산 및 중복 결과 제거 등의 추가적인 연산을 해야 한다는 문제점들이 있다. 제안된 기법은 공간 릴레이션들을 일정 영역들로 분할하여 비공유 공간 데이터베이스 클러스터의 각 노드에서 중복없이 저장, 관리하도록 하며 분할 영역의 경계선 상에 위치하는 공간 데이터에 대해서만 중복 저장을 허용하여 병렬 공간 조인 연산 시 누락되는 공간 데이터가 없도록 한다. 본 기법은 공간 조인 연산 시 병렬 처리를 위한 별도의 작업 할당 과정을 거치지 않고 각 노드에서 병렬적으로 공간 조인 연산을 수행하며, 분할 경계선 상에 존재하는 공간 객체들은 여과 과정을 거쳐 한번만 공간 조인이 수행되므로 중복 결과들을 제거하기 위한 별도의 연산이 필요없는 특징을 갖는다. Ad Hoc망의 위상변화에 대한 적응성을 높일 수 있도록 한다. SQL Server 2000 그리고 LSF를 이용하였다. 그리고 구현 환경과 구성요소에 대한 수행 화면을 보였다.ool)을 사용하더라도 단순 다중 쓰레드 모델보다 더 많은 수의 클라이언트를 수용할 수 있는 장점이 있다. 이러한 결과를 바탕으로 본 연구팀에서 수행중인 MoIM-Messge서버의 네트워크 모듈로 다중 쓰레드 소켓폴링 모델을 적용하였다.n rate compared with conventional face recognition algorithms. 아니라 실내에서도 발생하고 있었다. 정량한 8개 화합물 각각과 총 휘발성 유기화합물의 스피어만 상관계수는 벤젠을 제외하고는 모두 유의하였다. 이중 톨루엔과 크실렌은 총 휘발성 유기화합물과 좋은 상관성 (톨루엔 0.76, 크실렌, 0.87)을 나타내었다. 이 연구는 톨루엔과 크실렌이 총 휘발성 유기화합물의 좋은 지표를 사용될 있고, 톨루엔, 에틸벤젠, 크실렌 등 많은 휘발성 유기화합물의 발생원은 실외뿐 아니라 실내에도 있음을 나타내고 있다.>10)의 $[^{18}F]F_2$를 얻었다. 결론: $^{18}O(p,n)^{18}F$ 핵반응을 이용하여 친전자성 방사성동위원소 $[^{18}F]F_2$를 생산하였다. 표적 챔버는 알루미늄으로 제작하였으며 본 연구에서 연구된 $[^{18}F]F_2$가스는 친핵성 치환반응으로 방사성동위원소를 도입하기 어려운 다양한 방사성의 약품개발에 유용하게 이

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.5
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• pp.18-24
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• 2011

In multibit Sigma-Delta Modulator, one of the DEM(Dynamic Element Matching) techniques which is DWA(Data Weighted Averaging) is widely used to get rid of non-linearity caused by mismatching of capacitor that is unit element of feedback DAC. In this paper, by adjusting clock timing used in existing DWA architecture, 2n Register block used for output was replaced with 2n S-R latch block. As a result of this, MOS Tr. can be reduced and extra clock can also be removed. Moreover, two n-bit Register block used to delay n-bit data code is decreased to one n-bit Register. After designing the 3rd 3-bit SC(Switched Capacitor) Sigma-Delta Modulator by using the proposed DWA architecture, 0.1% of mismatching into unit element in input frequency 20 kHz and sampling frequency 2.56 MHz. As a consequence of the simulation, It was able to get the same resolution as the existing architecture and was able to reduce the number of MOS Tr. by 222.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.410-417
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• 2013

Long-term behavior analysis considering construction sequence should be performed in the design and the actual construction of reinforced tall buildings. Most of the analytical studies on this subject, however, has not been applied directly to the structural design and the construction caused by the simple approach. As the axial force redistribution of shores and columns is time-dependent, the actual construction sequence with the placement of concrete, form removal, reshoring, shore removal, and the additional load application is very important. Object-oriented analysis program considering construction sequence, especially time-dependent deformation in early days, is developed. This system is composed of input module, database module, database store module, analysis module, and result generation module. Linkage interface between the central database and each of the related module is implemented by the visual c# concept. Graphic user interface and the relational database table are supported for user's convenience.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.471-478
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• 2000

For many decades, the railway was constructed using tracks with jointed rails of relatively short lengths. The joints cause many drawbacks in the track and lead to signeficant maintenance cost. so, railroad engineers became interested in eliminating joints. Continuous welded rail(CWR) track has many advantages over the conventional jointed-rail track. but, in the case of the elimination of rail joints, it may cause the track to be suddenly buckled laterally by thermal loads. In this paper, firstly, 3-D CWR track model and CWRB program exactly considering the influence of tie are developed far linear static and buckling analysis using finite element method. Characteristics of CWR track model are using 7-dofs beam element as rail, Offset technic exactly considering centroid axies difference of track components(rail, rail-pad-fastener, tie), and Thermal gradient considering thermal difference of top flange and bottom flange in rail section.. second,, Through the static and linear buckling analysis by CWRB, Influences of various track components (rail, ballast, fastener, tie and so on..) on CWR track behavior and stability was characterized.

• Journal of Korea Spatial Information System Society
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• v.11 no.1
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• pp.137-144
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• 2009

Understanding lane markings in a live video captured from a moving vehicle is essential to build services for intelligent vehicles such as LDWS(Lane Departure Warning Systems), unmanned vehicles, video-based car navigation systems. In this paper, we present a novel approach to recognize the color of lane markings and the lane number that he/she is driving on. More specifically, we present a background-color removal approach to understand the color of lane markings for various illumination conditions, such as backlight, sunset, and so on. In addition, we present a probabilistic network approach to decide the lane number. According to our experimental results, the proposed idea shows promising results to detect lane number in a various illumination conditions and road environments.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.4
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• pp.253-258
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• 2016

This paper proposes a method that utilizes optimization approach for localization of an indoor mobile robot. Bayesian filters which have been widely used for localization of a mobile robot use many control parameters to take the uncertainties in measurement and environment into account. The estimation performance depends on the selection of these parameter values. Also, the performance of the Bayesian filters deteriorate as the non-linearity of the motion and measurement increases. On the other hand, the optimization approach uses fewer control parameters and is less influenced by the non-linearity than the Bayesian methods. This paper compares the localization performance of the proposed method with the performance of the extended Kalman filter to verify the feasibility of the proposed method. Measurements of ranges from beacons of ultrasonic satellite to the robot are used for localization. Mahalanobis distance is used for detection and rejection of outlier in the measurements. The optimization method sets performance index as a function of the measured range values, and finds the optimized estimation of the location through iteration. The method can improve the localization performance and reduce the computation time in corporation with Bayesian filter which provides proper initial location for the iteration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1317-1325
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• 2014

The study focused on analyzing spatial sampling by minimizing autocorrelation of spatial based on spatial and geographical data. The study concluded two different ways of minimizing autocorrelation. First, it was important to use suitable spatial sampling method to alienate spatial autocorrelation from spatial or geographical data. The shear distribution rate of public transportation in Seoul resulted in high rate of autocorrelation. However, the study showed samples eliminated autocorrelation when samples were extracted with reasonable distance(above 400m) apart. Without spatial sampling the distortion of spatial data leads to false results; therefore, spatial sampling is indispensable. Second, factors which fluctuates shear distribution of public transportation spatial sampling changed before and after spatial sampling. This was caused by incapable of controling inherent spatial autocorrelation of the data.