• Proceedings of the Korean Society for Cognitive Science Conference
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• 2005.05a
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• pp.171-176
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• 2005

본 논문에서는 진단시스템의 추론성능을 향상시키기 위한 방법으로서, 사례 기반 추론을 통해서 규칙 기반 추론의 단점을 보완하여 성능을 향상시키는 혼합형 추론 모델을 제안한다. 본 모델의 특징은 규칙 기반 추론의 확장성 문제와 규칙화 할 수 없는 예외적인 상황에 대한 문제점을 사례 기반 추론에서 사례로 저장하여 규칙 기반 추론의 단점을 보완하는데 있다. 이런 두 모델의 문제점을 해결하는 과정은 첫째로, 문제에 따라 규칙기반추론 모듈의 베이스를 통해서 적절한 규칙을 적용 후 추론을 적용하여 근접한 해를 얻어낸다. 두 번째로, 규칙베이스에 저장되어 있지 않은 문제에 대해서는 사례 라이브러리를 검색하고 유사성 검사를 통해서 저장된 사례를 찾아 입력된 사례에 적용하여 문제를 해결한다. 셋째로, 해결된 문제에 대해서 수정작업을 통해 사례 라이브러리를 확장한다. 이와 같이 세 과정을 통해 본 논문에서 제안하는 방법론의 성과를 측정하기 위하여 정비 메뉴얼을 규칙화하여 규칙베이스를 구축하였고 전문가들의 경험적인 지식에 대해서는 사례라이브러리로 구축하였다. 또한 지식베이스를 통해서 진단을 수행하고 해결된 문제에 대해서 정확도 검사를 통해 진단의 정확성을 측정하여 혼합형추론엔진의 성능을 검증하였다.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.240-245
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• 2006

오늘날 도시인구집중화 현상에 따른 대규모 도시개발과 도시역의 확대로 지표면의 피복 변화가 극심하게 이루어지고 있는 한편 이러한 현상으로 인해 도시의 내 외적 경관변화 뿐만 아니라 지형 및 기온상승, 바람장의 변화 등 복합적인 국지기후 변화를 초래하게 되었다. 본 연구에서는 이러한 도시의 기후 변화에 따라 청계천 복원 전의 도시 지표 열 환경 특성을 분석을 수행하고자 한다 도시지역의 열환경 분석을 위하여 기존에는 주로 Landsat TM/ETM+ 위성영상 자료를 사용하였으나 2003년 5월 위성 센서의 고장으로 위성영상 자료의 사용이 불가피하게 되었다. 이에 대체 방안으로 ASTER 영상 열적외 센서에서 취득한 지표온도 값과 현장에서 취득한 AWS자료와의 상관성 분석을 실시하였으며, 이를 기반으로 청계천 주변의 근접성 분석 및 토지이용별 지표온도 분포 패턴 등 도시 열 환경 변화 탐지 및 분석을 위하여 GIS 및 RS 분석을 실시하였다.

• Journal of Digital Contents Society
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• v.16 no.2
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• pp.257-262
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• 2015

Recently, the interests of mobile GIS technology is increasing with the spread of wireless network, the improvement of mobile device's performances, and the growth of demands about mobile services. Providing services in a wireless environment with existing wired-based GIS solutions have many limitations such as slow communication, processing rates and screen size. In this paper, we propose a cache algorithm on client side to solve the above problems. The proposed algorithm demonstrates the performance improvement over known studies by utilizing unit time and spatial proximity. In addition, this paper conducts a performance evaluation to measure the improvement in algorithm efficiency and analyzes the results of the performance evaluation. When spatial data queries are conducted, according to our performance evaluation, hit rate has been improved over the existing algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.932-939
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• 2008

Recently lattice-reduction (LR) has been used in signal detection for multiple-input multiple-output (MIMO) systems. The conventional LR aided detection schemes are combinations of LR and signal detection methods such as zero-forcing (ZF) and minimum mean square error (MMSE) detection. In this paper, we propose the Lattice-Reduction-aided scheme based on extended noise variance matrix to search good candidate symbol set in quantization step. Then this scheme estimates transmitted symbol with Semidefinite Relaxation by candidate symbol set. Simulation results in a random MIMO system show that the proposed scheme exhibits improved performance and a slight increase in complexity.

• Korean Journal of Optics and Photonics
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• v.30 no.3
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• pp.94-100
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• 2019

The near-field subwavelength squint-less focusing system of a phased array antenna is designed and demonstrated by numerical simulation. The Huygens-Fresnel principle is applied to numerical simulation for calculation of the phased array antenna at microwave frequency. It was shown that beam squinting can be eliminated, utilizing true-time optical delay lines based on a chirped fiber grating in the proposed system. Furthermore, subwavelength focusing with high numerical aperture can be achieved by considering the fact that the array elements of the phased-array antenna can be treated as diffractive elements in an optical lens system. Also, side lobes can be suppressed by decreasing the distance between element antennas to less than half of the wavelength.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.44.3-45
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• 2021

일반화된 excursion set 이론과 자기 유사 구형 유입(Self-similar spherical infall) 모형에 기반하여 Splashback 질량함수에 대한 해석적 단일 매개변수 모델을 착안하였다. Planck/WMAP7 관측결과를 토대로 구축된 EREBOS N-Body 시뮬레이션의 수치적 결과의 해석적 모델을 이용한 회귀분석을 통해 단일 매개변수이자 Splashback 경계의 확산적 특성을 수치화하는 확산계수(Diffusion Coefficient)의 추정치를 계산하였다. 계산된 확산계수를 적용한 해석적 모델과 수치적 결과가 5 ≤ M/(10¹²h^-1 M_⊙) < 10³의 질량범위에서 매우 근접히 일치하는 것을 보였으며 Baysian and Akaike Information Criterion 검정을 통해 0.3 ≤ z ≤ 3의 범위에서 기존의 모델들보다 본 모델이 선호 돼야함을 확인하였다. 또한 확산계수가 적색편이에 대하여 선형진화에 근접한 변화를 보임을 발견하였으며, 특정 임계 적색편이(z_c)를 기준으로 확산계수가 0에 수렴함을 발견하였다. 더 나아가 두 Planck모델과 WMAP7모델에서 도출된 확산계수는 서로 상당한 차이를 보였다. 이 결과는 암흑물질 헤일로의 splashback 질량함수가 z ≥ z_c에서 매개변수가 없는 온전한 해석적 모델로 설명되고 z_c가 독립적으로 우주의 초기조건을 독립적으로 특정지을 수 있는 가능성을 지님을 시사한다. 이 초록은 The Astrophysical Journal의 Ryu & Lee 2021, ApJ, 917, 98 (arxiv:2103.00730) 논문을 바탕으로 작성되었다.

• Explosives and Blasting
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• v.41 no.3
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• pp.1-12
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• 2023

A basic assessment of techniques to mitigate the risk of blast shock waves from proximity explosions was conducted. Common existing techniques include using mitigant materials to form barriers around the explosive or in the direction of propagation of the shock wave. Various explosive energy dissipation mechanisms have been proposed, and research on blast shock wave mitigation utilizing impedance differences has drawn considerable interest. In this study, shear thickening fluid (STF) was applied as a blast mitigation material to evaluate the effectiveness of STF mitigation material on explosion shock wave mitigation through explosion experiments and numerical analysis. As a result, the effectiveness of the STF mitigant material in reducing the explosion shock pressure was verified.

• Journal of Advanced Navigation Technology
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• v.24 no.3
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• pp.192-197
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• 2020

Recently, the technologies related to autonomous drive has studying the goal for safe operation and prevent accidents of vehicles. There is radar and camera technologies has used to detect obstacles in these autonomous vehicle research. Now a day, the method for using LiDAR sensor has considering to detect nearby objects and accurately measure the separation distance in the autonomous navigation. It is calculates the distance by recognizing the time differences between the reflected beams and it allows precise distance measurements. But it also has the disadvantage that the recognition rate of object in the atmospheric environment can be reduced. In this paper, point cloud data by triangular functions and Line Regression model are used to implement measurement algorithm, that has improved detecting objects in real time and reduce the error of measuring separation distances based on improved reliability of raw data from LiDAR sensor. It has verified that the range of object detection errors can be improved by using the Python imaging library.

• Journal of Digital Contents Society
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• v.16 no.4
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• pp.545-553
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• 2015

While all of the data has a value in itself, most of the data that is collected in the real world is a random and unstructured. In order to extract useful information from the data, it is need to use the data transform and analysis algorithms. Data mining is used for this purpose. Today, there is not only need for a variety of data mining techniques to analyze the data but also need for a computational requirements and rapid analysis time for huge volume of data. The method commonly used to store huge volume of data is to use the hadoop. A method for analyzing data in hadoop is to use the MapReduce framework. In this paper, we developed a tournament-based MapReduce method for high efficiency in developing an algorithm on a single machine to the MapReduce framework. This proposed method can apply many analysis algorithms and we showed the usefulness of proposed tournament based method to apply frequently used data mining algorithms k-means and k-nearest neighbor classification.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.10
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• pp.319-326
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• 2016

Abnormal situation caused by aggressive behavior of pigs adversely affects the growth of pigs, and comes with an economic loss in intensive pigsties. Therefore, IT-based video surveillance system is needed to monitor the abnormal situations in pigsty continuously in order to minimize the economic demage. In this paper, we propose a new Kinect camera-based monitoring system for the detection of the individual pigs. The proposed system is characterized as follows. 1) The background subtraction method and depth-threshold are used to detect only standing-pigs in the Kinect-depth image. 2) The moving-pigs are labeled as regions of interest. 3) A contour method is proposed and applied to solve the touching-pigs problem in the Kinect-depth image. The experimental results with the depth videos obtained from a pig farm located in Sejong illustrate the efficiency of the proposed method.