• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.11
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• pp.116-123
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• 1994

A novel opto-digital pattern recognition method which has shift, rotation, and scale invariant properties is proposed for recognizing two dimensional images having straight lines. The algorithm is composed of three stages. In the first stage the line features of the image are extracted. The second stage imposes the shift, rotation, and scale invariant properties on the extracted features through normalizing procedure. The required normalizing equations are analytically explained. In the last stage, the artificial feedforward neural network is trained with the extracted features. In order to evaluated the proposed algorithm, nine different edge enhnaced binary images composed of straight lines are tested. Thus the proposed algorithm can recognize the patterns event though they are shifted, rotated, and scaled.

• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.23-29
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• 2017

A concept of a VSA (Virtual Source Array) is the method for an acoustic spatio-temporal focus at a selected location in the outbound direction with respect to the VSA without the need of a probe source as combines a TRP (Time-Reversal Processing) and time-delay and beam-steering. However, in TRP using the VSA concept, it is limited to the critical angle and the short distances relevant to the VSA. In this paper, the waveguide invariant theory is applied to the VSA concept to refocus the received field at ranges greater other than the critical angle and the short ranges by shifting the focused field. The suggested method is verified via numerical simulation, and the results show that the robust acoustic focusing is achieved on the selected location regardless of the limitation on the conventional VSA concept.

• Journal of the Korea Society of Computer and Information
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• v.27 no.3
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• pp.79-90
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• 2022

'Trust' is 'believing and relying on people or things', and at the same time, it is the foundation and essential condition of existence of a specific community or society. How blockchain technology creates trust can be found in the fact that it is a technology shared by all participants. As a shared technology, blockchain itself shows three characteristics: transparency, immutability, and availability. Because it is shared, it is transparent, and because it is shared, it is immutable, which is difficult to modify or delete. In addition, since it is shared, the entire system operates normally even if some failure occurs. The significance of trust created based on this blockchain technology can be summarized in three aspects as follows. The first is to understand the problem of trust in connection with technology. Second, understanding the relationship between information and trust begins to pay attention. Third, based on the expanded information processing capability, it is possible to establish a large-scale, concrete relationship without central mediation.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.161-164
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• 2007

최근 인터넷과 멀티미디어 기술이 발달함에 따라 이미지 데이터의 양이 급속히 증가하고 있다. 증가하는 이미지를 효과적으로 관리하고 검색하기 위해 내용기반 이미지 검색에 대한 연구가 활발히 진행되고 있다. 대부분의 내용 기반 이미지 검색 시스템은 색상, 모양, 질감 특징을 이용한 유사도-기반검색에 초점을 맞추고 있다. 따라서 본 논문에서는 이미지에 나타나는 주요 색상과 색상의 공간적 특성을 포함하는 픽셀샘플링, 그리고 이미지의 외형적 변경에 강인함을 갖는 불변 모멘트 값을 이용한 내용기반 이미지 검색 시스템을 제안한다. 첫 번째 유사성 검사 단계에서는 이미지의 영역별로 가중치를 부여하여 추출한 대표색상을 사용하여, 유사하지 않은 이미지를 제거하여 검색대상의 수를 줄이며, 두 번째 유사성 검사 단계에서는 첫 번째 단계에서 선별된 후보 이미지에 색상의 공간적 정보를 포함한 픽셀샘플링을 이용하여 색상의 공간적인 위치까지 유사한 이미지만을 선별한다. 두 번째 유사성 검사단계에서 이미지가 외형적으로 변형된 유사이미지의 검출이 어려운 점을 보완하는 방법으로 이미지의 불변 모멘트를 이용하여 검색의 정확성을 높인다. 제안한 이미지 검색 방법은 10000개의 다양한 이미지로 구성된 데이터베이스에서 검색을 효율성을 실험하였다.

• The Journal of the Korea Contents Association
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• v.10 no.10
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• pp.456-463
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• 2010

This study measured the relative efficiency and productivity change of the Korean professional sport teams using DEA model and Malmquist Index for 2006-2009. The main results of this study can be summarized as follows. First, in case of efficiency of CCR for 2006-2009, the number of efficient professional sport teams(CCR value is one) are two(Daejeon Citizen, Incheon United), three(Daejeon Citizen, Incheon United, FC Seoul), two(Daejeon Citizen, Incheon United), three(Kyungnam FC, Incheon United, FC Seoul) respectively. Second, Malmquist Index representing productivity change for 2006-2009 are 1.035, 0.9658, 1.5331 for Kyungnam FC, 1.2514, 0.8948, 0.9056 for Daegu FC, 1.1768, 0.8620, 0.9722 for Daejeon Citizen, 0.9368, 1.2609, 0.7714 for Incheon United, 1.0000, 1.0000, 1.0000 for FC Seoul, respectively. This result will be used by inefficient professional sport teams to improve inefficiency.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.29-32
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• 2011

본 연구에서는 지속적인 증가 및 확대 추세에 있으나 여전히 많은 실패를 겪고 있는 SDO(Software Development Outsourcing) 프로젝트의 성과 향상을 위해 SDO 성과에 영향을 미치는 요인을 탐색하고자 하였다. 연구가설의 검증을 위해 SDO 경험이 있는 고객사의 정보시스템 인력을 대상으로 현장 설문조사를 실시하여 214개의 설문을 수집, 분석에 이용하였다. 분석 결과, SDO의 성과에는 벤더의 힘과 고객사 요구사항의 불변성, 목표의 명확성 그리고 목표의 일치 정도가 영향을 미치는 것으로 나타났다. 본 연구의 결과는 SDO의 실패를 낮추고 성공 가능성을 높이는 데 효과적으로 활용될 수 있을 것이다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.221-224
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• 2001

In this paper we propose a shift-invariant uHMT estimation for wavelet-based image denoising. The proposed estimation have just nine meta-parameter (independent of the size of the image and the number of wavelet scales) and requires no kinds of training. Also it solve visual artifacts resulted in the lack of shift-invariance in the DWT. The experimental results show that the proposed estimation is more effective than the other wavelet-based denoising by 0.5-ldB (PSNR) and allows an Ο(nlog n) in terms of performance speed.

• Communications of the Korean Mathematical Society
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• v.14 no.2
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• pp.233-286
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• 1999

Berkeley의 H. Wu 교수에 의하여 1993년에 제창된 Wu 거리는 다변수 복소함수론의 기하학적 연구에 중심적인 역할을 하는 여러 불변거리 중 가장 최근에 발견되었다. 짧은 역사에도 불구하고 이 개념의 유용성이 두드러지는 점을 감안하여, 이 연구의 내용과 전망 그리고 여러 관련 문제 등을 소개하려는 것이 이 논문의 목표이다.

• Economic and Environmental Geology
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• v.52 no.1
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• pp.81-90
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• 2019

In this study, the effects of fracture tensor component and first invariant on block hydraulic behaviors are evaluated in the 2-D DFN(discrete fracture network) systems. A series of regression analysis is performed between connected fracture tensor components and block hydraulic conductivities estimated at every $30^{\circ}$ hydraulic gradient directions for a total of 36 DFN systems having various joint density and size distribution. The directional block hydraulic conductivity seems to have strong relation with the fracture tensor component estimated in direction perpendicular to it. It is found that an equivalent continuum approach could be acceptable for the 2-D DFN systems under condition that the first invariant of fracture tensor is more than 2.0~2.5. The first invariant of fracture tensor seems highly correlated with average block hydraulic conductivity and can be used to evaluate hydraulic characteristics of the 2-D DFN systems. Also, a possibility of upscaling using the first invariant of fracture tensor for the DFN system is addressed through this study.

• The Korean Journal of Applied Statistics
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• v.34 no.5
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• pp.837-848
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• 2021

Evaluating or predicting the effectiveness of economic policies is an important issue, but it is difficult to find an economic variable which causes a significant result because there are numerous variables that cannot be taken into account. A randomized controlled experiment is the best way to investigate causality, but it is not realistically possible to control through randomization and intervention in time series data such as macroeconomic data. Although some analysis methods have been proposed to find causality, the methods such as Granger causality method and Chow test are insufficient to explain causality. Recently, Pfister et al. (2019) proposed invariant causal prediction methods which can be applicable in time series data. In this paper, we introduce the method of Pfister et al. (2019) and use the method to find macroeconomic variables invariantly affecting the won-dollar exchange rate.