• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.633-642
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• 2004

This study tries to generalize the stream network by constructing rule-based modelling. A study on the map generalization tends to be concentrated on development of algorithms for modification of linear features and evaluations to the limited cartographic elements. Rule-based modelling can help to improve previous algorithms by application of generalization process with the results that analyzing mapping principles and spatial distribution patterns of geographical phenomena. Rule-based modelling can be applied to generalize various cartographic elements, and make an effective on multi-scaling mapping in the digital environments. In this research, nile-based modelling for stream network is composed of generalization rule, algorithm for centerline extraction and linear features. Before generalization, drainage pattern was analyzed by the connectivity with lake to minimize logical errors. As a result, 17 streams with centerline are extracted from 108 double-lined streams. Total length of stream networks is reduced as 17% in 1:25,000 scale, and as 29% in 1:50,000. Simoo algorithm, which is developed to generalize linear features, is compared to Douglas-Peucker(D-P) algorithm. D-P made linear features rough due to the increase of data point distance and widening of external angle. But in Simoo, linear features are smoothed with the decrease of scale.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.198-200
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• 1999

공간 데이터베이스 구축을 효과적으로 하는 방법중의 하나는 대축척 공간 데이터베이스를 이용하여 여러 종류의 다중축척 데이터베이스를 구축하는 것이다. 다중축척 데이터베이스의 구축에는 많은 작업들이 포함된다. 기하학적 변형이나 불필요한 객체의 단순화, 삭제 등의 일반화와 데이터 모델의 변형, 그리고 데이터베이스의 전환 과정에 포함된다. 이 작업은 매우 다양한 처리과정을 요구하기 때문에 자동화된 도구의 도움을 필요로 한다. 본 논문에서는 다중축척 데이터베이스 구축에 이용되는 작업을 지원하는 CASE 도구를 소개한다. 이 도구는 지도 일반화에 의해 발생되는 데이터 모델의 변화에 대한 규칙에 따라 새로운 소축척의 데이터베이스의 데이터 모델을 설계하는 작업을 지원하며, 이 데이터 모델에 따라 대축척의 데이터베이스를 소축척의 데이터베이스로 전환하는 기능을 지원한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.06a
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• pp.95-97
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• 2019

본 논문에서는 비디오 데이터를 이용한 감독 학습 프레임 워크를 제안한다. 최근 Deep Convolutional Neural Networks의 성공으로 많은 분야에서 사용되고 있다. DCNNs 모델 성능의 중요한 요소 중 하나는 Large-cale Dataset을 구축하는 것으로 Small-scale Dataset으로 모델을 학습한다면 과적합 및 일반화 오류를 해결하기 어렵다. 이러한 문제점을 해결하는 방법으로 이미지 왜곡을 통한 데이터 셋을 증가 또는 Dropout 기법 등을 사용하였지만 원본 데이터가 적은 경우에는 모델이 일반화 능력을 갖기 어렵다. 따라서 본 논문에서는 이러한 문제점을 보완하고자 Web으로부터 얻은 비디오에서 해당 Class와 관련된 프레임들을 추출하여 보다 쉽게 데이터 셋을 확장하고, 모델의 성능을 향상 시키는 방법을 제안한다.

• Annual Conference on Human and Language Technology
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• 2019.10a
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• pp.8-11
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• 2019

앙상블 기법은 여러 모델을 종합하여 최종 판단을 산출하는 기계 학습 기법으로서 딥러닝 모델의 성능 향상을 보장한다. 하지만 대부분의 기법은 앙상블만을 위한 추가적인 모델 또는 별도의 연산을 요구한다. 이에 우리는 앙상블 기법을 교차 검증 방법과 결합하여 앙상블 연산을 위한 비용을 줄이며 일반화 성능을 높이는 교차 검증 앙상블 기법을 제안한다. 본 기법의 효과를 입증하기 위해 MRPC, RTE 데이터셋과 BiLSTM, CNN, BERT 모델을 이용하여 기존 앙상블 기법보다 향상된 성능을 보인다. 추가로 교차 검증에서 비롯한 일반화 원리와 교차 검증 변수에 따른 성능 변화에 대하여 논의한다.

• Journal of Convergence for Information Technology
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• v.7 no.3
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• pp.73-81
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• 2017

The generalized Hough transform (GHough) is a useful technique for detecting and locating 2-D model. However, GHough requires a 4-D parameter array and a large amount of time to detect objects of unknown scale and orientation because it enumerates all possible parameter values into a 4-D parameter space. Several n-to-1 mapping algorithms were proposed to reduce the parameter space from 4-D to 2-D. However, these algorithms are very likely to fail due to the random votes cast into the 2-D parameter space. This paper proposes to use internal gradient information in addition to the model boundary points to reduce the number of random votes cast into 2-D parameter space. Experimental result shows that our proposed method can reduce both the number of random votes cast into the parameter space and the execution time effectively.

• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.66-75
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• 2010

In Augmented Reality, it needs restoration and tracking of a real-time scene structure for the augmented 3D model from input video or images. Most of the previous approaches construct accurate 3D models in advance and try to fit them in real-time. However, it is difficult to measure 3D model accurately and requires long pre-processing time to construct exact 3D model specifically. In this research, we suggest a real-time scene structure analysis method for the wide indoor mobile augmented reality, using only generic models without exact pre-constructed models. Our approach reduces cost and time by removing exact modeling process and demonstrates the method for restoration and tracking of the indoor repetitive scene structure such as corridors and stairways in different scales and details.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.315-322
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• 2010

The phase-screen and the split-step Fourier migrations, which are implemented in both the frequency-wavenumber and frequency-space domains by using one-way scalar wave equation, allow imaging in laterally heterogeneous media with less computing time and efficiency. The generalized-screen migration employs the series expansion of the exponential, unlike the phase-screen and the split-step Fourier migrations which assume the vertical propagation in frequency-wavenumber domain. In addition, since the generalized-screen migration generalizes the series expansion of the vertical slowness, it can utilize higher-order terms of that series expansion. As a result, the generalized-screen migration has higher accuracy in computing the propagation with wide angles than the phase-screen and split-step Fourier migrations for media with large and rapid lateral velocity variations. In this study, we developed a 2D prestack generalized-screen migration module for imaging a complex subsurface efficiently, which includes various dips and large lateral variations. We compared the generalized-screen propagator with the phase-screen propagator for a constant perturbation model and the SEG/EAGE salt dome model. The generalized-screen propagator was more accurate than the phase-screen propagator in computing the propagation with wide angles. Furthermore, the more the higher-order terms were added for the generalized-screen propagator, the more the accuracy was increased. Finally, we compared the results of the generalizedscreen migration with those of the phase-screen migration for a model which included various dips and large lateral velocity variations and the synthetic data of the SEG/EAGE salt dome model. In the generalized-screen migration section, reflectors were positioned more accurately than in the phase-screen migration section.

• Annual Conference of KIPS
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• 2015.04a
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• pp.351-353
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• 2015

공공정보 공유 및 개방, 소셜네트워크서비스의 활성화 그리고 사용자 간의 공유 데이터 증가 등의 이유로 인터넷상에 노출되는 사용자의 개인 정보가 증가하고 있다. 인터넷상에 노출된 사용자들의 개인정보들은 연결공격(linkage attack), 배경지식 공격(background attack)으로 프라이버시를 침해할 수 있다. 이를 막기 위해 관계형 데이터베이스에서는 대표적으로 k-익명성(k-anonymity)을 시작으로 l-다양성(l-diversity), t-밀집성(t-closeness)이라는 익명화 모델이 제안되었으며 계속해서 익명화 알고리즘의 성능은 개선되고 있다. 하지만 k-익명성, l-다양성, t-밀집성 모델의 조건을 만족하기 위해서는 준식별자(quasi-identifier)를 일반화(generalization)처리 해주어야 하는데 이 과정에서 준식별자의 가치를 손실된다는 단점이 있다. 본 논문에서 준식별자의 정보 손실을 최소화하기 위해 k-익명성 모델을 만족시키는 과정에서 일반화와 데이터를 삽입을 사용하는 익명화 처리하는 방법을 제안한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.5
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• pp.365-372
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• 2019

We propose a method to estimate unknown parameters(e.g., target amplitude and clutter parameters) in the generalized likelihood ratio test(GLRT) using maximum likelihood estimation and the Newton-Raphson method. When detecting targets in a clutter environ- ment, it is important to establish a modular model of clutter similar to the actual environment. These correlated clutter models can be generated using spherically invariant random vectors. We obtain the GLRT of the generated clutter model and check its detection probability using estimated parameters.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.1 s.19
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• pp.109-123
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• 2002

The purpose of this study construct water-facility Database and to develop its management system using GSIS. We used route system and event table that are data model in GSIS for the construction of water valves on water facility pipe. A water-facility management system using GSIS was developed and was actually applied for the city of Yosu and compared with conventional water-facility management systems in terms of workability, information searching cost, and database management efficiency. The system has also been compared with those of two other local governments in terms of functions, process time, and conveniences. The generalization of the work model for water-facility system was also attempted based on the data collected from three local governments and it was revised by the work model of the wide area water-facility system. The generalized work model in this study was compared with other two local governments' work models. The generalized work model will enable local governments to develop more efficient and economical water-facility management system by GSIS in future.