• Korean Journal of Biological Psychiatry
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• v.8 no.2
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• pp.251-257
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• 2001

Backgrounds : Gamma band oscillatory activity is considered to be related to cognitive functions and illustrates that the concept of event-related oscillations bridges the gap between single neurons and neural assemblies. An event-related gamma oscillation is the time-locked responses of specific frequency, and can be identified by computing the amplitude frequency characteristics of the averaged event-related potentials(ERPs) after stimulation. Objectives : We purposed to present experimental paradigm to investigate ${\gamma}$-band oscillation activities from the recording of ERPs by using auditory oddball paradigm and investigate the difference of ${\gamma}$-band activity between schizophrenia and normal controls. Methods : The ERPs resulting from auditory stimuli with oddball paradigm in a group of schizophrenics(n=11), and also a group of age-, sex-, and handedness matched normal controls, were recorded by 128 channel EEG. The ${\gamma}$-band oscillatory activities were calculated by using time-frequency wavelet decomposition of the signal between 20 and 80Hz. The ${\gamma}$-band oscillatory activities of both groups were compared by t-test. Results : The ${\gamma}$-band oscillatory of the leads Fz, Cz, and Pz of both groups were represented well in the time-frequency maps. Significant increases of the ${\gamma}$-band activity in normal controls compared with schizophrenics were observed around 160 msec, 350 msec, and 800 msec after stimulation. Conclusions : Our results suggested that the increment in ${\gamma}$-band oscillatory activity during cognitive operations and decreased ${\gamma}$-band activity in schizophrenics may be associated with the cognitive dysfunctions and the pathophysiology of the schizophrenia.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.28-28
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• 2011

치수는 고대국가로부터 현재의 국가에 이르기까지 중차대한 국가사업이다. 근대를 지나면서 산업화가 가속화되었고 수자원의 사용과 관리는 더욱 세분화 되었다. 또한 수자원의 사용과 관리에 앞서 기후와 밀접한 관계가 있는 수자원의 물리적 특성을 분석하는 연구가 활발히 이루어지고 있다. 최근 우리나라도 급격한 산업화로 인한 환경파괴와 지구온난화로 인한 강수의 편중이 더욱 심해지고 있다. 즉, 한반도도 전 세계가 직면한 기후변화로 인한 자연재해로 부터 안전하지 않다는 것을 의미한다. 특히 수자원을 관리함에 있어 가뭄의 경우에는 장기적으로 진행되는 경우가 많고 피해 규모와 복구 등도 가뭄의 진행 기간과 밀접한 관계를 가지므로 적극적인 대비가 필요하다. 따라서 가뭄을 연구함에 앞서 과거 한반도의 가뭄의 경향성 및 주기성 같은 특성을 분석할 수 있는 연구가 수반되어야 할 것으로 사료된다. 이에 따라 본 논문에서는 과거 한반도 가뭄 사상의 특성분석을 위해 대표 가뭄지수로 SPI(Standardized Precipitation Index)와 PDSI(Palmer Drought Severity Index)를 선정하여 우리나라 전역에 위치한 총 59개 기상관측소의 1980년~2009년까지의 기상자료를 수집하여 유역별 월평균 가뭄지수를 산정하였다. 또한 이를 이용하여 가뭄발생의 경향성 및 주기성을 중심으로 과거한반도 가뭄의 통계학적 특성분석을 실시하였다. 각 지수의 경향성을 분석한 결과, SPI3와 SPI6는 봄과 겨울에는 가뭄이 심화되는 경향을 보였고 여름철에는 가뭄이 완화되는 경향을 보였다. 반면 SPI12의 경우는 섬진강과 영산강은 유의하지는 않으나 전 기간에 걸쳐 가뭄이 심화되는 경향을 보였고 한강, 낙동강, 금강유역은 가뭄이 완화되는 것으로 나타났다. PDSI의 경우에는 SPI와는 반대로 섬진강과 영산강은 전 기간에 걸쳐 가뭄이 완화되는 경향을 보였고 한강, 낙동강, 금강유역은 유의한 수준에서 가뭄이 심화되는 경향을 보임으로써, SPI와 PDSI에 의한 가뭄평가 경향성이 유역별로 다소 다르게 나타나는 것을 확인할 수 있었다. 한편, 각 유역의 주기성을 분석한 결과로는 모든 유역에서 1년~3년 또는 6년 이하의 주기성을 나타냈으며, SPI의 경우 지속기간이 길어질수록 6년 이상의 저빈도 주기성을 나타냈고, SPI3는 짧게는 1년 미만의 고빈도 주기를 보이는 경우도 있었으며, SPI6와 SPI12는 4년~6년 주기를 나타냈다. 또한 PDSI도 마찬가지로 6년 내외의 장주기를 보였다. 특히 유역별로 분석할 경우 남부지역의 가뭄발생 주기가 중부지역보다 길게 나타나는 성향을 보였다. 그리고 SPI와 PDSI, 두 가뭄지수의 공통주기를 분석한 결과에서는 상관관계가 적은 것으로 확인 되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.433-433
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• 2011

수자원 계획 및 관리를 위한 지표 자료로서 일유량은 매우 유용하기 때문에 정확한 일유량 산정의 문제는 매우 중요하다. 그러나 우리나라의 경우 조석이나 배수 갑문 혹은 보 등에 의한 배수 영향으로 인해 수위-유량관계곡선식만으로 정상적인 유량산정이 어려운 지점이 다수 존재한다. 특히, 한강대교 지점과 같이 조석영향 구간에서 수위-유량관계곡선식에 의해 산정된 일유량은 자료에 대한 곡선식의 적합도 문제로 그 정확도가 매우 낮았다. 최근 자동유량측정에 의해 시간단위 이하의 실시간 유량이 생산되고 있고 이를 이용하여 일유량을 환산하고 있어 과거에 비해 보다 정확한 일유량 산정이 가능해 졌다. 그러나 신뢰도 있는 일유량을 안정적으로 제공하기 위해서는 보다 다양한 조건을 고려한 비교 검증 연구가 요구되는 실정이다. 이러한 배경에서 본 연구에서는 한강대교 지점과 같이 조석영향을 받는 지점의 일유량 산정방법 및 산정개념에 따른 유황의 차이와 적정성을 평가하여 보았다. 각 산정방법 및 산정개념 별로 산정된 일유량을 통해 유황을 산정하여 한강대교 지점의 일유량 산정방법에 대한 적정성을 평가하고 적절한 유황산정을 위한 목적별 대안을 제시하였다. 산정방법 별로는 기존의 수위-유량관계 곡선식으로 변환된 자료, 자동유량측정자료, 그리고 자동유량측정자료에서 조석성분을 제거한 순수 유출성분자료를 이용하여 일유량을 산정하였고, 이를 이용하여 산정된 유황에 대한 비교 분석을 실시하였다. 수위-유량관계곡선식에 의한 일유량은 수문조사연보의 자료를 이용하였고 자동유량자료를 이용한 일유량은 시자료를 평균하여 일유량으로 환산하는 방법을 사용하였다. 자동유량 자료에서 조석성분을 제거한 순수 유출성분의 추출은 웨이블릿 변환(wavelet transform)을 이용하였다. 각 방법별로 산정된 일유량을 비교한 결과 수위-유량관계곡선식에 의해 산정된 일유량이 자동 유량자료로 산정된 일유량에 비해 전반적으로 크게 나타났고, 2009년 한해 동안의 유출용적을 비교해 본 결과 18%정도 더 크게 산정되었다. 산정개념에 따른 비교에서는 조석성분 유량의 유효성 여부에 따른 유황을 비교하였으며, 조석성분 유량도 실효적 유량으로 간주한 경우 이론적 확률 분포형에 적합시켜 산정한 평균 갈수량은 15.7 ��/s(동절기 이상 거동기간인 2009년 11월 17일-12월 12일 기간을 제외하고 산정된 결과이나 불확실성은 잔존)에서 $53.2m^3/s$로 증가하였다. 따라서 유지유량의 목적상 경관용수나 생태용수가 중요한 지점으로 조석성분 유량이 이에 유효하다면, 유황산정을 위한 한강대교 지점의 일유량 산정방법은 다양한 목적에 비추어 추가적인 분석 검토가 필요할 것으로 판단된다.

• The Journal of the Korea Contents Association
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• v.11 no.11
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• pp.10-18
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• 2011

Medical asset protection is important in each medical institution especially because of the law on private medical record protection and face recognition for this protection is one of the most interesting and challenging problems. In recognizing human faces, the distortion of face images can be caused by the change of pose, illumination, expressions and scale. It is difficult to recognize faces due to the locations of lights and the directions of lights. In order to overcome those problems, this paper presents an analysis of coefficients of Gabor wavelets, kernel decision, feature point, size of kernel, for face recognition in CCTV surveillance. The proposed method consists of analyses. The first analysis is to select of the kernel from images, the second is an coefficient analysis for kernel sizes and the last is the measure of changes in garbo kernel sizes according to the change of image sizes. Face recognitions are processed using the coefficients of experiment results and success rate is 97.3%. Ultimately, this paper suggests empirical application to verify the adequacy and the validity with the proposed method. Accordingly, the satisfaction and the quality of services will be improved in the face recognition area.

• Journal of the Korean Society of Radiology
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• v.3 no.1
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• pp.29-39
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• 2009

In this paper has proposed to the recognition of the disease on medical images using neural network. The neural network is constructed as three-layers of the input-layer, the hidden-layer and the output-layer. The training method applied for the recognition of disease region is adaptive error back-propagation. The low-frequency region analyzed by DWT are expressed by matrix. The coefficient-values of the characteristic polynomial applied are n+1. The normalized maximum value +1 and minimum value -1 in the range of tangent-sigmoid transfer function are applied to be use as the input vector of the neural network. To prove the validity of the proposed methods used in the experiment with a simulation experiment, the input medical image recognition rate the evaluation of areas of disease. As a result of the experiment, the characteristic polynomial coefficient of low-frequency area matrix, conversed to 4 level DWT, was proved to be optimum to be applied to the feature parameter. As for the number of training, it was marked fewest in 0.01 of learning coefficient and 0.95 of momentum, when the adaptive error back-propagation was learned by inputting standardized feature parameter into organized neural network. As to the training result when the learning coefficient was 0.01, and momentum was 0.95, it was 100% recognized in fifty-five times of the stomach image, fifty-five times of the chest image, forty-six times of the CT image, fifty-five times of ultrasonogram, and one hundred fifty-seven times of angiogram.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.5
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• pp.379-387
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• 2006

The real world is spatially modelled conceptually either as discrete objects or earth surface. The generated data models are then usually represented as vector and raster respectively. Although there are limited cases where only one data model is sufficient to solve the spatial problem at hand, it is now generally accepted that GIS should be able to handle various types of data model. Recent advances in spatial technology introduced even more variety of heterogeneous data models and the need is ever growing to handle and manage efficiently these large variety of spatial data. The OGC (Open GIS Consortium), an international organization pursuing standardization in the geospatial industry. recently introduced the GMLJP2 (Geographic Mark-Up Language JP2) format which enables store and handle heterogeneous spatial data. The GMLJP2 format, which is based on the JP2 format which is an abbreviation for JPEG2000 wavelet image compression format, takes advantage of the versatility of the GML capabilities to add extra data on top of the compressed image. This study takes a close look into the GMLJP2 format to analyse and exploit its potential to handle and mange hetergeneous spatial data. Aerial image, digital map and LIDAR data were successfully transformed end archived into a single GMLJP2 file. A simple viewing program was made to view the heterogeneous spatial data from this single file.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.122-128
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• 2016

This paper, proposes a new analysis method for the event detection of an OTDR signal. An OTDR signal was passed through the Hamming filter to remove the high frequency noise included in the signal. The signal was then passed consecutively through a differential filter to detect the events of interest. The terminal position was determined using the fact that there is a large gap between the signal and the trailing noise power beyond the terminal. This study examined the local maxima of the signal up to the terminal position and determined the peak regions. The real events were determined from the peak regions using noise information and peak threshold. Finally, the user events were found by inspecting the user peaks beyond the terminal position. The events of the OTDR signal without users are located at less than 17m compared to the optical fiber link setup. The events of the JDSU device are located less than 25m and their users are less than 5m. For the RadianTech device, the events are detected at less than 19m and the users are found in 5m. The results suggest that the proposed method is sufficiently applicable to an optical fiber link monitoring system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.134-141
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• 2011

There have been increased economic and societal demands to continuously monitor the integrity and long-term deterioration of civil infrastructures to ensure their safety and adequate performance throughout their life span. However, it is very difficult to continuously monitor the structural condition of the pipeline structures because those are placed underground and connected each other complexly, although pipeline structures are core underground infrastructures which transport primary sources. Moreover, damage can occur at several scales from micro-cracking to buckling or loose bolts in the pipeline structures. In this study, guided wave measurement can be achieved with a self-sensing circuit using a piezoelectric active sensor. In this self sensing system, a specific frequency-induced structural wavelet response is obtained from the self-sensed guided wave measurement. To classify the multiple types of structural damage, supervised learning-based statistical pattern recognition was implemented using the damage indices extracted from the guided wave features. Different types of structural damage artificially inflicted on a pipeline system were investigated to verify the effectiveness of the proposed SHM approach.

• Journal of Broadcast Engineering
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• v.22 no.3
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• pp.282-294
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• 2017

In this paper, we propose a novel intelligent headlight control (IHC) system which is durable to various road lights and camera movement caused by vehicle driving. For detecting candidate light blobs, the region of interest (ROI) is decided as front ROI (FROI) and back ROI (BROI) by considering the camera geometry based on perspective range estimation model. Then, light blobs such as headlights, taillights of vehicles, reflection light as well as the surrounding road lighting are segmented using two different adaptive thresholding. From the number of segmented blobs, taillights are first detected using the redness checking and random forest classifier based on Haar-like feature. For the headlight and taillight classification, we use the random forest instead of popular support vector machine or convolutional neural networks for supporting fast learning and testing in real-life applications. Pairing is performed by using the predefined geometric rules, such as vertical coordinate similarity and association check between blobs. The proposed algorithm was successfully applied to various driving sequences in night-time, and the results show that the performance of the proposed algorithms is better than that of recent related works.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.344-354
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• 2005

In this paper, we proposed a new lifting architecture for JPEG2000 and implemented to ASIC. We proposed a new cell to execute unit calculation of lifting using the property of lifting which is the repetitious arithmetic with same structure, and then recomposed the whole lifting by expanding it. After the operational sequence of lifting arithmetic was analyzed in detail and the causality was imposed for implementation to hardware, the unit cell was optimized. A new lifting kernel was organized by expanding simply the unit cell, and a lifting processor was implemented for Motion JPEG2000 using it. The implemented lifting kernel can accommodate the tile size of $1024{\times}1024$, and support both lossy compression using the (9,7) filter and lossless compression using (5,3) filter. Also, it has the same output rate as input rate, and can continuously output the wavelet coefficients of 4 types(LL, LH, HL, HH) at the same time. The implemented lifting processor completed a course of ASIC using $0.35{\mu}m$ CMOS library of SAMSUNG. It occupied about 90,000 gates, and stably operated in about 150MHz though difference from the used macro cell for the multiplier. Finally, the improved operated in about 150MHz though difference from the used macro cell for the multiplier. Finally, the performance can be identified in comparison with the previous researches and commercial IPs.