• Journal of the Korean Data and Information Science Society
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• 제20권5호
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• pp.949-954
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• 2009

The autoregressive process is applied in this paper to kernel regression in order to infer nonlinear models for predicting responses. We propose a kernel method for the autoregressive data which estimates the mean function by kernel machines. We also present the model selection method which employs the cross validation techniques for choosing the hyper-parameters which affect the performance of kernel regression. Artificial and real examples are provided to indicate the usefulness of the proposed method for the estimation of mean function in the presence of autocorrelation between data.

• 한국지리정보학회지
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• 제21권4호
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• pp.81-90
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• 2018

사람과 사물, 장소 등 공간상의 모든 객체가 네트워크로 서로 연결되어 정보를 공유하는 '초연결 시대'가 점차 현실로 다가오고 있다. 이와 같은 정보통신 환경의 변화에 따라 공간정보도 중요한 도전에 직면해 있다. 정부는 자율주행자동차, 드론, 3차원 공간정보 등 '초연결'로 인한 공간정보의 사회적 수요에 부응하기 위해 노력하고 있지만 근본적인 대응책을 마련하지 못하고 있다. 초연결 시대가 필요로 하는 공간정보의 수요에 효과적이고 능동적으로 대응하기 위해서는 근본적인 변화를 이끌어 낼 수 있는 중장기 전략이 필요하다. 본 연구는 '초연결 시대'라는 커다란 패러다임의 변화에 직면한 공간정보의 미래 수요변화와 활용특성을 분석하고, 이를 기반으로 미래 사회의 공간정보 수요에 효과적으로 대응할 수 있는 전략을 모색하는데 목적이 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.442-445
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• 1997

We present a hybrid self-tuning method of fuzzy inference systems with hyper elliptic Gaussian membership functions using genetic algorithm(GA) and back-propagation algorithm. The proposed self-tuning method has two phases : one is the coarse tuning process based on GA and the other is the fine tuning process based on back-propagation. But the parameters which is obtained by a GA are near optimal solutions. In order to solve the problem in GA applications, it uses a back-propagation algorithm, which is one of learning algorithms in neural networks, to finely tune the parameters obtained by a GA. We provide Box-Jenkins time series to evaluate the advantage and effectiveness of the proposed approach and compare with the conventional method.

• International Journal of Internet, Broadcasting and Communication
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• 제12권4호
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• pp.204-211
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• 2020

The era of the 4th industrial revolution is a complex environment in which the cyber world and the physical world are integrated and interacted. In order to successfully implement and be sustainable the 4th industrial revolution of hyper-connectivity, hyper-convergence, and hyper-intelligence, not only the technological aspects that implemented digitalization but also the social aspects must be recognized and dealt with as important. There are socio-technical systems and socio-technical systems theory as concepts that describe systems involving complex interactions between the environmental aspects of human, mechanical and tissue systems. This study confirmed how the Socio-technical System was applied in the research literature for the last 10 years through machine learning-based analysis. Eight clusters were derived by performing co-occurrence keywords network analysis, and 13 research topics were derived and analyzed by performing a structural topic model. This study provides consensus and insight on the social and technological perspectives necessary for the sustainability of the 4th industrial revolution.

• 한국실내디자인학회논문집
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• 제34호
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• pp.3-9
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• 2002

Entering into the 21st century, digital culture and the innovation of media technology have drastically changed our understanding of the concept of space. Increased availability of information made possible by technological advancement has, directly or indirectly, contributed to the development of space design, which, in turn, offers a possibility for a new paradigm in space design. Given these fundamental changes, this study seeks to explore how to understand the expansion of the concept of space. In order to answer this question, this study investigates de-materialization tendency in modern architectural design such as transparency, anti-gravity, complexity and simultaneity of space. It examines the interaction-oriented nature of space among human, information and time. Finally, based on concepts such as new hyper-surface, which transcend the limitations of space and time, it explores new emerging trends in space design.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.124-127
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• 2007

In this study, we focused on investigation of governing parameters affected on the fatigue properties in the hyper-eutectoid steel wires used for TBR tires. Steel wires are fabricated under different drawing strain from 3.36 to 3.80. Their diameters are 0.21 mm and 0.185mm, respectively. The fatigue properties was measured by hunter rotating beam tester, specially designed thin-sized steel wires. The results showed that the fatigue properites of steel wire, marked as A-1, were greater than the others, due to the low value of residual stress. In order to elucidate the variations of fatigue properties, the microstructure, surface defect and residual stress were observed and measured by useful analysis technique, such as TEM, 3D profiler and FIB.

• 한국해양공학회지
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• 제17권4호
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• pp.59-65
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• 2003

In order to achieve the desired lightweight and robust design of a structure, it is preferable to design a structure and its control system, simultaneously, which is termed the combined optimal design. A constant-cross-sectional area cantilever beam was chosen as the optimum design method, An initial load and a time-varying disturbance were applied at the free end of the beam. Sliding mode control was selected, due to its insensitivity to the disturbance, compared with other modes. It is known that the sliding mode control is robust to the disturbance and is uncertain, only if a matching condition is met, after giving a switching hyper plane. In this study, the optimum method was used for the design of the switching hyper plane, and the objective function of the optimum switching hyper plane was assumed to be the objective of the control system. The total weight of the structure was treated as a constraint, and the cross sectional areas of the beam were considered as design variables, the result being a nonlinear programming problem. To solve it, the sequential linear programming method was applied. As a result of the optimum design, the effect of attenuating vibrations has been substantially improved. Moreover, the lightweight design of the structure became possible as a result of the relationship of the weight of the structure to the control objective function.

• 충청수학회지
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• 제27권1호
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• pp.17-27
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• 2014

In order to study the propagation of singularities for solutions to second order quasilinear strictly hyperbolic equations with boundary, we have to consider the regularity of solutions of first order nonlinear equations satisfied by a characteristic hyper-surface. In this paper, we study the regularity compositions of the form v(${\varphi}$(x), x) with v and ${\varphi}$ assumed to have limited Sobolev regularities and we use it to prove the regularity of solutions of the first order nonlinear equations.

• 한국전산구조공학회논문집
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• 제36권6호
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• pp.391-398
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• 2023

본 논문에서는 기저 스크리닝 기반 크리깅 모델(BSKM: Basis Screening based Kriging Model) 생성의 정확도를 높이기 위해 페널티를 적용한 최대 우도 평가 방법(PMLE : Penalized Maximum Likelihood Estimation)에 대해서 소개한다. BSKM에서 사용하는 기저함수의 최대 차수와 종류는 그 중요도에 따라서 결정하게 되며, 이때 중요도의 지표는 기저함수에 대한 교차 검증 오차(CVE : Cross Validation Error)로 택한다. 크리깅 모델(KM : Kriging Model) 구성시 최적의 기저함수 조합은 우선 최대 기저함수 차수를 선택하고 개별 기저함수의 중요도를 평가를 하게 된다. 최적 기저함수 조합은 크리깅 모델의 CVE가 최소가 될 때까지 개별 기저함수의 중요도가 높은 순으로 기저함수를 하나씩 추가하며 찾는다. 이 과정에서 KM은 반복적으로 생성해야 하며, 동시에 데이터 사이의 상관관계를 나타내는 하이퍼 매개변수(Hyper-parameters)도 최대 우도 평가방법을 통해 계산하여야 한다. 하이퍼 매개변수의 값에 따라 선택되는 최적의 기저함수 조합이 달라지기 때문에 KM의 정확도에 막대한 영향을 미치게 된다. 정확한 하이퍼 매개변수를 계산하기 위해서 PMLE 방법을 적용하였으며, Branin-Hoo 함수 문제에 적용하여 BSKM 의 정확성이 개선될 수 있음을 확인하였다.

• 한국통신학회논문지
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• 제22권4호
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• pp.662-674
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• 1997

In order to post process the vector-quantized images employing the theory of projections onto convex sets or the constrained minimization technique, the the projector onto QCS(quantization constraint set) as well as the filter that smoothes the lock boundaries should be investigated theoretically. The basic idea behind the projection onto QCS is to prevent the processed data from diverging from the original quantization region in order to reduce the blurring artifacts caused by a filtering operation. However, since the Voronoi regions in order to reduce the blurring artifacts caused by a filtering operation. However, since the Voronoi regions in the vector quantization are arbitrarilly shaped unless the vector quantization has a structural code book, the implementation of the projection onto QCS is very complicate. This paper mathematically analyzes the projection onto QCS from the viewpoit of minimizing the mean square error. Through the analysis, it has been revealed that the projection onto a subset of the QCS yields lower distortion than the projection onto QCS does. Searching for an optimal constraint set is not easy and the operation of the projector is complicate, since the shape of optimal constraint set is dependent on the statistical characteristics between the filtered and original images. Therefore, we proposed a hyper-cube as a constraint set that enables a simple projection. It sill be also shown that a proper filtering technique followed by the projection onto the hyper-cube can reduce the quantization distortion by theory and experiment.