• Communications for Statistical Applications and Methods
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• 제24권2호
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• pp.115-127
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• 2017

This paper proposes a Bayesian test for the equivalence of survival functions in multiple groups. Proposed Bayesian test use the model of Cox's regression with time-varying coefficients. B-spline expansions are used for the time-varying coefficients, and the proposed test use only the partial likelihood, which provides easier computations. Various simulations of the proposed test and typical tests such as log-rank and Fleming and Harrington tests were conducted. This result shows that the proposed test is consistent as data size increase. Specifically, the power of the proposed test is high despite the existence of crossing hazards. The proposed test is based on a Bayesian approach, which is more flexible when used in multiple tests. The proposed test can therefore perform various tests simultaneously. Real data analysis of Larynx Cancer Data was conducted to assess applicability.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1650-1654
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• 2004

This paper presents how it is effective to use many features for improving the speed and the accuracy of the visual servo systems. Some rank conditions which relate the image Jacobian and the control performance are derived. It is also proven that the accuracy is improved by increasing the number of features. Effectiveness of the redundant features is evaluated by the smallest singular value of the image Jacobian which is closely related to the accuracy with respect to the world coordinate system. Usefulness of the redundant features is verified by the real time experiments on a Dual-Arm Robot manipulator made in Samsung Electronic Co. Ltd.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.778-782
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• 2003

This paper presents how it is effective to use many features for improving the speed and the accuracy of the visual servo systems. Some rank conditions which relate the image Jacobian and the control performance are derived. It is also proven that the accuracy is improved by increasing the number of features. Effectiveness of the redundant features is evaluated by the smallest singular value of the image Jacobian which is closely related to the accuracy with respect to the world coordinate system. Usefulness of the redundant features is verified by the real time experiments on a Dual-Arm Robot manipulator made in Samsung Electronic Co. Ltd.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.348-351
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• 1995

This note proposes a robust LQR method for systems with structured real parameter uncertainty based on Riccati equation approach. Emphasis is on the reduction of design conservatism in the sense of quadratic performance by utilizing the uncertainty structure. The class of uncertainty treated includes all the form of additive real parameter uncertainty, which has the multiple rank structure. To handle the structure of uncertainty, the scaling matrix with block diagonal structure is introduced. By changing the scaling matrix, all the possible set of uncertainty structures can be represented. Modified algebraic Riccati equation (MARE) is newly proposed to obtain a robust feedback control law, which makes the quadratic cost finite for an arbitrary scaling matrix. The remaining design freedom, that is, the scaling matrix is used for minimizing the upper bound of the quadratic cost for all possible set of uncertainties within the given bounds. A design example is shown to demonstrate the simplicity and the effectiveness of proposed method.

• Korean Journal of Mathematics
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• 제15권2호
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• pp.135-148
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• 2007

We prove the stability of generalized Jensen's equations in a Hilbert module over a unital $C^*$-algebra. This is applied to show the stability of a projection, a unitary operator, a self-adjoint operator, a normal operator, and an invertible operator in a Hilbert module over a unital $C^*$-algebra.

• 산업경영시스템학회지
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• 제13권21호
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• pp.61-72
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• 1990

In the past, a fundamental technique in inventory control system was to rank the items of a inventory from a distribution by value to draw an ABC curve. Unfortunately the use of ABC categorization technique has created problems and introduced some gross errors into the inventory control system. First, the author considers the possible applications of the technique in the real world and then attempts to discuss ABC fallacies through the literatures. Finally, an inventory categorization algorithm by the principal component analysis is derived and a numerical example is also presented to illustrate the algorithm.

• 대한수학회논문집
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• 제15권3호
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• pp.521-531
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• 2000

Graph C*-algebras C*(E) are the universal C*-algebras generated by partial isometries satisfying the Cuntz-Krieger relations determined by directed graphs E, and it is known that a simple graph C*-algebra is extremally rich in sense that it contains enough extreme consider a sufficient condition on a graph for which the associated graph algebra(possibly nonsimple) is extremally rich. We also present examples of nonextremally rich prime graph C*-algebras with finitely many ideals and with real rank zero.

• Korean Journal of Mathematics
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• 제29권4호
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• pp.741-747
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• 2021

The Cayley-Bacharach theorem says that every cubic curve on an algebraically closed field that passes through a given 8 points must contain a fixed ninth point, counting multiplicities. Ren et al. introduced a concrete formula for the ninth point in terms of the 8 points [4]. We would like to consider a different approach to find the ninth point via the theory of truncated moment problems. Various connections between algebraic geometry and truncated moment problems have been discussed recently; thus, the main result of this note aims to observe an interplay between linear algebra, operator theory, and real algebraic geometry.

• 한국항만경제학회지
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• 제24권4호
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• pp.313-327
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• 2008

한국과 일본은 가장 가까운 이웃 나라이면서 한국은 일본의 식민지를 거친 경험을 갖고 있는 논문에서는 Liu(2008)의 슬랙변수모형을 도입하여 이론적으로 설명하고 1994년 및 1995년의 국내 20개 항만의 3개의 산출물(수출입물량, 선박입출항척수, 항만재정수입)과 2개의 투입물(접안능력, 하역능력)을 이용하여 국내항만들의 효율성을 측정한 후에, 양년도간에 모두 효율적인 항만으로 판명된 항만을 제외한 나머지 16개 항만들의 효율성 순위를 이용하여 월콕슨의 부호순위검정을 통해서 슬랙변수모형이 갖고 있는 항만효율성측면의 예측력을 측정하는 방법을 보여 주었다. 또한 동일한 방법으로 다년도(1995년-2003년)분석을 실시하여 항만효율성의 예측력은 어느 정도 되는지를 검정하였다. 다년도(1995-2003년)의 실증분석의 주요한 결과를 요약한다면 "가설검정의 모든 결과는 귀무가설을 기각할 수 없는 것"으로 나타났다. 즉, 예측자료와 실제자료의 차이가 있다고 할 수 없기 때문에, 예측자료가 실제자료를 반영하고 있는 것으로 나타났다. 특히 2000-2001년, 2003-2004년의 유의수준은 60%에 가까운 수준으로 나타나서 예측력이 있는 것으로 나타났으나 1995-1996년, 2002-2003년의 예측력은 낮은 것으로 나타났다. 본 연구의 정책적인 함의는 국내항만들도 슬랙변수모형과 월콕슨부호순위검정방법을 이용하여 차년도의 효율성, 또는 경영성과를 예측하여 제시하는 것도 항만의 효율성을 높일 수 있는 한 가지 방법이 될 수 있다는 점이다.

• 방송공학회논문지
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• 제17권3호
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• pp.437-446
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• 2012

흑백 혹은 컬러 영상과 같은 2차원 정보를 사용한 얼굴 검출 알고리즘에 관한 연구가 수십 년 동안 이루어져 왔다. 최근에는 저가 range 센서가 개발되어, 이를 통해 3차원 정보 (깊이 정보: 카메라와 물체사이의 거리를 나타냄)를 손쉽게 이용함으로써 얼굴의 특징을 높은 신뢰도로 추출하는 것이 가능해졌다. 대부분 사람 얼굴에는 3차원적인 얼굴의 구조적인 특징이 있다. 본 논문에서는 흑백 영상과 깊이 영상을 사용하여 얼굴을 검출하는 알고리즘을 제안한다. 처음에는 흑백 영상에 adaboost를 적용하여 얼굴 후보 영역을 검출한다. 얼굴 후보 영역의 위치에 대응되는 깊이 영상에서의 얼굴 후보 영역을 추출한다. 추출된 영역의 크기를 $5{\times}5$ 영역으로 분할하여 깊이 값의 평균값을 구한다. 깊이 값들의 평균값들 간에 순위를 매김으로써 블록 순위 패턴이 생성된다. 얼굴 후보 영역의 블록 순위 패턴과 학습 데이터를 사용하여 미리 학습된 템플릿 패턴을 매칭함으로써 최종 얼굴 영역인지 아닌지를 판단할 수 있다. 제안하는 방법의 성능을 Kinect sensor로 취득한 실제 영상으로 실험하였다. 실험 결과 true positive를 잘 보존하면서 많은 false positive들을 효과적으로 제거하는 것을 보여준다.