• 한국초전도ㆍ저온공학회논문지
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• 제14권1호
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• pp.14-19
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• 2012

Shimming, active and/or passive, is indispensable for most MR (magnetic resonance) magnets where homogeneous magnetic fields are required within target spaces. Generally, shimming consists of two steps, field mapping and correcting of fields, and they are recursively repeated until the target field homogeneity is reached. Thus, accuracy of the field mapping is crucial for fast and efficient shimming of MR magnets. For an accurate shimming, a "magnetic" center, which is a mathematical origin for harmonic analysis, must be carefully defined, Although the magnetic center is in general identical to the physical center of a magnet, it is not rare that both centers are different particularly in HTS (high temperature superconducting) magnets of which harmonic field errors, especially high orders, are significantly dependent on a location of the magnetic center. This paper presents a new algorithm, based on a field mapping theory with harmonic analysis, to define the best magnetic center of an MR magnet in terms of minimization of pre-shimming field errors. And the proposed algorithm is tested with simulation under gaussian noise environment.

• 한국작물학회지
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• 제45권5호
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• pp.316-321
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• 2000

Blast severity data of 39 rice varieties at 11 sites in Korea from 1997 to 1999 were analyzed using AMMI model and pattern analysis. Genotype x Environment (G$\times$E) interaction sum of squares (SS) accounted for 12 % of the total SS. Eight genotype groups and seven location groups were identified based on blast reaction pattern. The data obtained from over 21 sites with 44 test varieties from 1981 to 1996 were also considered. These were compared with the 1997-1999 data using the G$\times$E analysis results. Majority of the variability in the Korean Rice Blast Nursery (KRBN) were attributable to variations due to genotypes. Variations of G$\times$E interaction were maintained though test sites were reduced from 21 to 11 sites. Broadly compatible biological discriminative varieties identified were Nagdongbyeo and Akibare while broadly incompatible biological discriminative varieties identified were Hangangchalbyeo and Seogwangbyeo. Key sites for future evaluation work could be selected from location groups. Each location group should be represented by the site with the strongest interaction pattern. Blast responses in Cheolwon, Gyehwa, Suwon, Iksan, and Icheon showed different patterns from other locations.

• 한국정보통신학회논문지
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• 제15권11호
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• pp.2488-2492
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• 2011

현재 무선 통신기술의 발전으로 위치기반 서비스 및 위치 인식의 중요성이 증가하는 추세이다. 여러 위치 인식 기법 중에서 삼변측량 기법이 대표적이다. 그러나 삼변측량 기법에서는 장애물이나 실내 주변 환경의 변화로 인하여 거리 오차가 발생하면 정확한 위치 인식을 할 수 없다. 위치 인식을 향상시키는 기존 삼변 측량 인식 기법에 대한 연구가 많이 있었지만, 삼변측량 위치인식 기법에 대한 체계적인 분석을 하지 않았다. 본 논문에서는 기존의 삼변측량 위치인식 기법들을 분석하고, 거리오차로 인해 위치 인식의 오차를 줄이는 기법들을 평가하였다.

• Korean Journal of Acupuncture
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• 제25권2호
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• pp.107-114
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• 2008

Objectives : Accurate location of acupoints is a prerequisite for both practice and research into acupoint specificity. Given that accurate location of acupoints is one of the most important issues in meridianology education, this study aimed at evaluating if the elastic ruler method for locating acupoints is suitable for meridianology practice class. Methods : Fifty-six students who took meridianology practice class participated in the experiment. Firstly, they were asked to locate PC6, CV12 and ST36 without any assisting tools and the distance between standard acupoint and their acupoint location was measured. Secondly, they were again asked to locate the same points this time with an elastic ruler. Then the first and second measurements were compared using a paired t-test. Results : Analysis of the results found using an elastic ruler significantly improved the difference between the student's acupoint location and the standard acupoint: there was a significant difference between 1st and 2nd measurements for PC6 (1.87${\pm}$0.29mm vs. 1.28${\pm}$0.19mm, P=0.037) and for ST36 (2.70${\pm}$0.22mm vs. 1.38${\pm}$0.15mm, P<0.0001). Conclusions : Using an elastic ruler as an assisting tool for locating acupoints in meridianology practice class should be considered for improving accuracy in acupoint location.

• 전기학회논문지
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• 제65권9호
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• pp.1583-1589
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• 2016

This paper proposes an improved spread spectrum time domain reflectometry (ISSTDR) using time-frequency correlation and reference signal elimination method in order to have more accurate fault determination and location detection than conventional (SSTDR) despite increased signal attenuation due to the long distance to cable fault location. The proposed method has a two-step process: the first step is to detect a peak location of the reference signal using time-frequency correlation analysis, and the second step is to detect a peak location of the correlation coefficient of the reflected signal by removing the reference signal. The proposed method was validated through comparison with existing SSTDR methods in open-and short-circuit fault detection experiments of low voltage power cables. The experimental results showed that the proposed method can detect correlation coefficients at fault locations accurately despite reflected signal attenuation so that cable faults can be detected more accurately and clearly in comparison to existing methods.

• 한국공작기계학회논문집
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• 제14권3호
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• pp.96-102
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• 2005

Acoustic Emission(AE) technique has been applied to not only material characterization evaluation but also on-line monitoring of the structural integrity. The AE source location technique is very important to identify the source, such as crack, leak detection. Since the AE waveforms obtained from sensors are very difficult to distinguish the defect signals, therefore, it is necessary to consider the signal analysis of the transient wave-form. In this study, we have divided the region of interest into a set finite elements, and calculated the arrival time differences between sensors by using the velocities at every degree from 0 to 90. A new technique for the source location of acoustic emission in fiberboard plates has been studied by introducing Wavelet Transform(WT) do-noising technique. WT is a powerful tool for processing transient signals with temporally varying spectra. If the WT de-noising was employed, we could successfully filter out the errors of source location in fiberboard plates by arrival time difference method. The accuracy of source location appeared to be significantly improved.

• 한국산학기술학회논문지
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• 제13권3호
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• pp.1412-1417
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• 2012

본 논문은 판교 신도시내의 새로운 추모시설을 도입함으로써, 차후의 신도시의 계획컨셉과 복지정책의 전환을 가능케할 수 있다는 전제하에 추진되었다. 이 연구에서는 판교신도시내의 근린공원 10개 중, 최종 1개의 최적부지를 선정하기 위해 추모공원 입지가 가능한 근린공원들을 분석하여 선정하는 연구를 진행하였다. 추모공원의 혐오시설로서의 특성들을 고려하고, 자연적 요소 및 기술적 요소 등에 대한 기준들을 검토하였으며, 전문가의견 설문을 통해 가중치분석의 틀을 객관화하였으며, 신도시내의 공원화 가능성에 대해 검토하였다. 이를 위해 판교라는 신도시의 특징 등 제반 여건이 종합적으로 검토되었으나, 본 연구에서는 추모공원의 입지선정과정을 보여줌으로써, 다른 여타의 추모공원의 입지분석에 기초정보를 제공할 수 있을 것으로 사료된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.411-413
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• 2006

This paper presents a novel fault location scheme on Korean AC electric railway systems. On AC railway system, because there is a long distance, 40 km or longer, between two railway substations, a fault location technique is very important. Since the fault current flows through the catenary system, the catenary system must be modeled exactly to analyze fault current magnitude and fault location. In this paper, before suggestion for the novel scheme of fault location, a 9-conductor modeling technique that includes boost wires and impedance bonds is introduced, based on the characteristics of Korean AC electric railway. After obtaining a 9-conductor modeling, the railway system is constructed for computer simulation by using PSCAD/EMTDC. By case studies, we can verify superiority of a new fault location scheme and suggest a powerful model for fault analysis on electric railway systems.

• 전자공학회논문지
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• 제51권6호
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• pp.143-151
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• 2014

최근 스마트폰이 널리 보급됨에 따라 이용자의 다양한 정보들이 스마트폰에 저장되고 있다. 그 중 위치정보는 특정 시간의 이용자의 위치나 이용자의 관심지역, 경로 등을 나타낼 수 있으므로 범죄수사 시 유용한 자료로 활용될 수 있다. 그러나 위치 정보에 대한 기존의 포렌식 연구는 단순히 사용흔적이나 위치정보에 대해 확인하는데 그치고 있다. 따라서 본 논문은 안드로이드 스마트폰에 저장되는 위치정보를 로그, 이미지, 각종 애플리케이션 등 다각적으로 접근하여 분석하고, 계층적 군집화를 이용한 통합적인 위치정보 분석모델을 제안한다. 본 논문에서 제안한 모델은 위치정보 분석의 효율성을 높이고 사건에 대한 정보를 제공함으로써 범죄수사과정에 도움이 될 것으로 기대된다.

• 전기학회논문지
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• 제63권12호
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• pp.1683-1689
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• 2014

In this paper, we propose an image processing based time-frequency domain reflectometry(TFDR) in order to estimate the fault location of a cable. The Wigner-Ville distribution is used for analysis in both the time domain and the frequency domain when the conventional TFDR estimates the fault location in a cable. However, the Winger-Ville distribution is a bi-linear function, and hence the cross-term is occurred. The conventional TFDR cannot estimate the accurate fault location due to the cross-term in case the fault location is close to the position where the reference signal is applied to the cable. The proposed method can reduce the cross-term effectively using binarization and morphological image processing, and can estimate the fault location more accurately using the template matching based cross correlation compared to the conventional TFDR. To prove the performance of the proposed method, the actual experiments are carried out in some cases.