• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.1
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• pp.83-91
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• 1996

The SPICE circuit analysis program has a limited math capability and, in general, cannot be used for RF and microwave simulation because a complex arithmetic is required to compute S-parameters from node voltages. This paper presents two test bench models that can be used to obtain node voltages proportional to incident, reflected, and transmitted signals. From SPICE computed node voltages, S-parameters are computed using the math capability of the PSPICE post processor, PROBE, as an example for a low-pass filter consisting of transmission line sections. The results of this example are compared with another high frequency circuit analysis program, TOUCHSTONE. The difference between the results of these two programs in magnitude was less than 0.003 and in phase was a few tenths of a degree. By using these test benchs to simulate a filter, RF and microwave analysis can be made with the SPICE, which can be a cost-effective and readily available computational tool for educators and practicing engineers.

• Journal of Broadcast Engineering
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• v.19 no.3
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• pp.355-361
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• 2014

In this paper, we propose a complexity reduction method of sample adaptive offset (SAO), which is an in-loop filter in high-efficiency video coding (HEVC). In the conventional SAO, an offset value is calculated for each coding tree block (CTB) to minimize the error between the original and reconstructed images. In order to determine the optimal offset value, all offset candidates are examined and the offset value that leads to the smallest rate-distortion cost is chosen. Thus, SAO occupies a significant amount of the computational complexity in the HEVC encoder. In the proposed method, we determine the least-used band (LUB) by considering the statistical characteristics of offset values and without processing the offset value included in the LUB. Also, in the offset value decision stage, we check only a certain number of candidates rather than all of them. Experimental results show that the proposed method reduces the encoding time by approximately 8.15% without yielding a significant loss in terms of coding efficiency.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.81-87
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• 1998

This paper proposes an efficient face recognition system using phase difference between the face images. We use a Karhunen-Loeve transform for image compression and reconstruction, and obtain the phase difference by using normalized inner product of the two compressed images. The proposed system is rotation and light-invariant due to using the normalized phase difference, and somewhat shift-invariant due to applying the cosine function. The faster recognition than the conventional system and incremental training is possible in the proposed system. Simulations are conducted on the ORL images of 40 persons, in which each person has 10 facial images, and the result shows that the faster recognition than conventional recognizer using convolution network under the same recognition error rate of 8% does.

• Geophysics and Geophysical Exploration
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• v.5 no.3
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• pp.150-156
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• 2002

In this study, a software for crosswell seismic tomography is developed. The software consists of first arrival picking and adjusting module, crosswell traveltime tomography module, and imaging module. This software allows saying the picked first arrival times into the header of seismic data, and using this data directly to the input of crosswell seismic tomography. With an imaging module, velocity structures and ray path can be imaged directly from the output of the tomography module. Because it is developed on the basis of the SU under the Linux and the GUI environment for user, this software can be carried out directly the first arrival picking, inversion and tomogram for crosswell tomography data in the field. Therefore, this software can be improved the applicability of site investigation by tomography method.

• Journal of Sensor Science and Technology
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• v.6 no.2
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• pp.115-122
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• 1997

In this paper, on-chp atomatic tuning circuit, using proposed integration level approximation technique, is designed to tuning of the variation of RC time-constant due to aging or temperature variation, etc. This circuit reduces the error, the difference between code values and real outputs of integrator, which is drawback of presented dual-slope tuning circuit and eliminates modulations of processing signals in integrated circuit due to fixed tuning codes during ordinary operation. This system is made up of simple integrator, A/D converter and digital control circuit and all capacitors are replaced by programed capacitor arrays in this system. This tuning circuit with 4 bit resolution achieves $-9.74{\sim}+9.68%$ of RC time constant error for 50% resistance variation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.662-671
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• 2020

It is crucial to manage and maintain the geodetic reference coordinates of GNSS continuously operating reference stations (CORSs) in consideration of their fundamental roles in geodetic control and positioning navigation infrastructure. Earthquake-induced crustal displacement directly impacts the reference coordinates, so such events should be promptly detected, and appropriate action should be made to maintain the target accuracy, including update of the geodetic coordinates. To this end, this paper deals with online schemes for the detection of persistent shifts in the coordinate time-series produced by an automatic GNSS processing system. Algorithms were implemented to test filtered results, such as hypothesis tests of the innovation sequence of a Kalman filter and a cumulative sum (CUSUM) test. The results were assessed by the time-series of coordinates of 14 CORS for two years, including the 2011 Tohoku earthquake. The results show that the global hypothesis test is practical for detecting abrupt jumps, whereas CUSUM is effective for identifying persistent shifts.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.1
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• pp.119-132
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• 1998

For the purpose of producing of grid D.E.M based on National Digital Map accurately and efficiently, We must carefully consider arrangement and numbers of it's elevation information, supplement interpolation method of control point information for maintaining accuracy. According to each combination, each of them has an effect on estimate elevations. This study, after finishing experimental analysis of several grid distance and interpolation methods, aims at presenting the optimal grid distance and interpolation method in the production of grid D.E.M by using of National Digital Map. The results are as follows: First, The result of experimental analysis shows that the method of Kriging is a very excellent interpolation method in the production of grid D.E. M by using National Digital Map. Second, For the purpose of determining grid distance, this study present that twice of the amount of contour interval to make producing grid D.E.M is optimal distance.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.5
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• pp.437-449
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• 2007

This paper deals with issues of GPS network adjustment for the purpose of determining the $3^{rd}$ order national geodetic control points based on the Korean Geodetic Datum which has newly adopted in the country since early 2003. After examining and arranging all the observations, GPS baseline analyses were performed to estimate baseline vectors between two control points. All the observations were divided into 17 block networks in order to accelerate the adjustment efficiency. After applying a minimally constrained adjustment technique to each of the block networks for the sake of detecting outliers and examining network precision, over constrained adjustments by fixing all of the $2^{nd}$ order control points within the block network were carried out to derive final coordinate sets. The final solutions indicated that the accuracy of the adjusted coordinates was better than 1cm and 2cm in the horizontal and vertical component, respectively.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.04a
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• pp.168-168
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• 2001

제지공정의 지절 현상은 많은 공정 변수들이 복합적으로 작용하여 발생하는 가장 큰 공정 트러블 중의 하나이다. 지절은 생산량 감소 뿐만 아니라 발생 후 공정의 복구 와 정리, 생산재가동 및 공정의 재안정화를 위해 많은 시간과 비용, 그리고 노력이 투 입되어야 하므로 공정의 효율과 생산성을 크게 저하시키는 요인이다. 그러나 지절 현상 의 복잡성 때문에 이에 대해 쉽게 접근하거나 해결하지 못하고 있는 것이 현실이지만 그 필요성은 더욱 더 증대되고 있다. 본 연구에서는 최근 들어 각종 산업분야에서 복잡 한 공정상의 결점 발견 및 진단에 효과적이라고 인정받고 있는 예측 분석기법인 인공 신경망(artificial neural network) 시율레이션과 일반적인 통계기법 중의 하나인 주성분 분석을 이용하여 제지 공정의 지절 현상의 검토 가능성을 타진하였다. 인공신경망이란 인간두뇌에서 일어나는 자극-반응-학습과정을 모사하여 현실세계에 존재하는 다양한 현상들의 업력벡터와 출력상태 간의 비선형 mapping올 컴퓨터 시율 레이션을 통하여 분석하고자 하는 기법으로, 여러 가지 현상들을 학습을 통해서 인식하 는 신경망 내의 신경단위들이 병렬처리에 의해 많은 양의 자료에 대한 추론이나 판단 을 신속하고 정확하게 해주는 특징이 있으며 실시간 패턴인식이나 분류 응용분야에도 매우 매력적으로 이용되고 있는 방법이다. 이러한 인공 신경망 기법 중에서도 본 연구 에서는 퍼셉트론의 한계점을 극복하기 위하여 입력총과 출력층에 한 개 이상의 은닉층 ( (hidden layer)을 사용하여 다층 네트워으로 구성하고, 모든 입력패턴에 대하여 발생하 는 오차함수를 최소화하는 방향으로 연결강도를 조정하는 back propagation 학습 알고 리즘을 사용하였다. 지절의 원인으로 추정 가능한 공정인자들을 변수로 하여 최적의 인 공신경망을 구축하기 위해 학습률과 모멘트 상수의 변화 및 은닉층의 수와 출력층의 뉴런 수를 조절하는 동의 작업을 거쳐 네트워크의 정확도가 높은 인공신경망을 설계하 였다. 또한 이러한 인공신경망과의 비교분석을 위해 동일한 공정 데이터들올 이용하여 보편적으로 사용하는 통계기법 중의 하나인 주성분회귀분석을 실시하였다. 주성분 분석은 여러 개의 반응변수에 대하여 얻어진 다변량 자료의 다차원적인 변 수들을 축소, 요약하는 차원의 단순화와 더불어 서로 상관되어있는 반응변수들 상호간 의 복잡한 구조를 분석하는 기법이다. 본 발표에서는 공정 자료를 활용하여 인공신경망 과 주성분분석을 통해 공정 트러블의 발생에 영향 하는 인자들을 보다 현실적으로 추 정하고, 그 대책을 모색함으로써 이를 최소화할 수 있는 방안을 소개하고자 한다.

• 한국공간정보시스템학회:학술대회논문집
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• 2000.06a
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• pp.67-76
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• 2000

Recently, SAR Interferometry method is actively being studied as a new technic in topographic mapping using satellite imageries. it extract height values using two SAR imageries covering same areas. Unlike when using SPOT imageries, it isn't affected by atmospheric conditions and time. But it is difficult to process radar imageries and the height accuracy is very low where relief displacements are high. In this study, we produced DEM(Digital Elevation Model) using ERS-1, ERS-2 tandem data and analysed the height accuracy over 14 ground control points. The mean error in height was 14.06m. But when using airborne SAR data, it Is expected that we can produce more accurate DEM which will be able to ue used in updating 1/10,000 or 1/25,000 map.