• Transactions on Control, Automation and Systems Engineering
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• 제3권4호
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• pp.289-292
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• 2001

This paper concerns with a receding horizon estimator (RHE) for discrete-time linear systems subject to constraints on the estimate. In solving the optimization for every horizons, the past all measurement data outside the horizon is discarded and thus the arrival cost is not considered. The RHE in the current work is a finite impulse response (FIR) structure which has some good inherent properties. The proposed RHE can be represented in the simple matrix form for the unconstrained case. Various numerical examples demonstrate how including constraints in the RHE can improve estimation performance. Especially, in the application to the unknown input estimation, it will be shown how the FIR structure in the RHE can improve the estimation speed.

• Journal of Information Technology Applications and Management
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• 제9권1호
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• pp.27-44
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• 2002

Performance evaluations of database algorithms are usually conducted on a set of queries for a given test database. For more detailed evaluation results, it is often necessary to use different query workloads several times. Each query workload should reflect the querying patterns of the application domain in real world, which are non-uniform in the usage frequencies of attributes in queries of the workload for a given database. It is not trivial to generate many different query workloads manually, while considering non-uniform distributions of attributes'usage frequencies. In this paper we propose a technique to generate non-uniform distributions, which will help construct query workloads more efficiently. The proposed algorithm generates a query-attribute usage distribution based on given constraints on usage frequencies of attributes and qreries. The algorithm first allocates as many attributes to queries as Possible. Then it corrects the distribution by considering attributes and queries which are not within the given frequency constraints. We have implemented and tested the performance of the proposed algorithm, and found that the algorithm works well for various input constraints. The result of this work could be extended to help automatically generate SQL queries for various database performance benchmarking.

• 대한기계학회논문집
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• 제17권10호
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• pp.2437-2445
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• 1993

In this work, a new method is presented for generating the manipulator path which significantly reduces residual vibration under the torque constraints. The desired path is optimally designed so that the required movement can be achieved with minimum residual vibration. From the previous research works, the dynamic model had been established including both the link and the joint flexibilities. The performance index is selected to minimize the maximum amplitude of residual vibration. The path to be designed is developed by a combined Fourier series and polynomial function to satisfy both the convergence and boundary condition matching problems. The concept of correlation coefficients is used to select the minimum number of design variables, i.e. Fourier coefficients, the only ones which have a considerable effect on the reduction of residual vibration. A two-link Manipulator is used to evaluate this method. Results show that residual vibration can be drastically reduced by selecting an appropriate manipulator path to both of unlimited and torque-limited cases.

• 대한안전경영과학회지
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• 제7권1호
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• pp.159-166
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• 2005

It is not difficult to see the road repairing. There are many and various machines which crush road surface. The efficiency and power of the machine depend on crushing head-shape, crushing interval, crushing load, crushing stress, machine's dropping height and roller's kind. The objective of this study is to select the optimal model among ten models of crushing machine with constraints such as crushing depth, variation, and crushed particle size. And then this paper provides the valid theoretical base on selected model. The data for this study are chosen from the site of construction in Kangnung during three months (2004. 6. 1${\~}$2004. 8. 31). The provided methodology in this paper will be fruitful not only for the selection of crushing machine but also for the aspects of construction period, cost, work efficacy according to the condition from the various sites of construction.

• 천문학회보
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• 제36권1호
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• pp.39.1-39.1
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• 2011

Coronal mass ejection (CME) plasmas have been observed in EUV and X-ray passbands as well as in white light. Mass of CME has been determined using polarized brightness observed by the Large Angle and Spectrometric Coronagraph Experiment (LASCO) on board Solar and Heliospheric Observatory (SOHO). Therefore, this mass obtained from the LASCO observation indicates the total CME mass. However, the mass of CME plasma in different temperatures can be determined in EUV and X-ray passbands using observations by SOHO/EIT, STEREO/EUVI, and Hinode/XRT. Prominence/CME plasmas have been observed as absorption or emission features in EUV and X-ray passbands. The absorption features provide a lower limit to cold mass. In addition, the emission features provide an upper limit to the mass of plasmas in temperature ranges of EUV and X-ray. We determine the mass constraints using the emission measure obtained by assuming the prominence/CME structures. This work will address the mass constraints of hot and cold plasmas in CMEs, comparing to total CME mass.

• 한국소음진동공학회논문집
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• 제15권11호
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• pp.1255-1261
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• 2005

The dynamic contact model of a beam that contacts to a rigid wall in a reactor core was studied. The gap between the beam and contact wall results in dynamic contact accompanying inequality constraints. The inequality constraints can be relieved to an equality constraint problem by introducing a convex Penalty function. In this work, a beam with contact condition is formulated using quasi-convex penalty function and numerically solved. General coordinate solution is adopted to raise computational efficiency. Also nonlinearity is examined In the beam contacting to a rigid wall.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.34.1-34
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• 2001

We deal with robust control problem for singularly perturbed linear systems with norm-bounded structured uncertainty under state constraints. We assume that the norm-bounded uncertainty is composed of repeated scalar-block and full-block forms. In the structured uncertainty, repeated scalar block forms account for uncertain physical parameter value and full-block forms may be some unknown nonlinear dynamics. In order deal with uncertainty and state constraints, we use LMI(Linear Matrix Inequality). The original problem is decomposed into two well behaved reduced order problems. Shinc two LMI problems are completely independent, each solution can be computed simultaneously and work in parallel.

• 한국경제지리학회지
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• 제12권4호
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• pp.319-343
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• 2009

이 논문은 이주노동자의 일터와 생활공간에 초점을 두고, 이들이 겪는 다양한 유형의 (시)공간적 제약과 이를 극복하기 위한 방안의 모색에 대해 설문 조사 및 심층 면접 자료에 기초하여 고찰하였다. 이들은 일터에 대해 가시적으로 긍정적 태도를 보이고 있지만, 이는 실질적인 것이라기보다는 가식적(허구적)인 것으로 해석된다. 즉 이들은 타자의 '영역'으로 만들어진 일터 속에서 장시간 노동과 엄격한 통제 하에서 일하도록 강제되고 있다. 또한 주거, 소비, 여가 등을 위한 생활공간에서도 생존을 위한 기본적 이동성은 어느 정도 확보되는 것처럼 보이지만, 중층적 제약들로 인해 뿌리내리기 어려운 장소에서 매우 어렵게 살아간다. 일터와 생활공간에서 겪게 되는 제약들을 벗어나기 위하여, 이주노동자들은 주로 본국 출신의 이주자들과 국지적 및 탈지역적 네트워크, 그리고 본국 가족 및 친지들과의 초국가적 네트워크를 구성하고, 이를 통해 주어진 제약들에 대응하거나 해소할 수 있는 방안들을 모색하게 된다. 이러한 노력은 이주노동자들의 삶의 시공간적 제약들을 벗어나도록 하기에는 한계를 가진다. 특히 이러한 한계는 이주노동자들에게 포괄적 의미의 지리적 지식(장소감과 지리적 상상력 포함)의 부족으로 심화된다. 이들은 결국 본국과 한국에 대한 혼종적 국가정체성뿐만 아니라 새롭고 낯선 삶의 현장에서 교란된 지역정체성으로 살아간다.

• Safety and Health at Work
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• 제7권2호
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• pp.171-174
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• 2016

Effective and sustainable prevention of work-related musculoskeletal disorders (WR-MSDs) remains a challenge for preventers and policy makers. Coordination of stakeholders involved in the prevention of WR-MSDs is a key factor that requires greater reflection on common knowledge and shared representation of workers' activities among stakeholders. Information on workers' strategies and operational leeway should be the core of common representations, because it places workers at the center of the "work situation system" considered by the intervention models. Participatory ergonomics permitting debates among stakeholders about workers' activity and strategies to cope with the work constraints in practice could help them to share representations of the "work situation system" and cooperate. Sharing representation therefore represents a useful tool for prevention, and preventers should provide sufficient space and time for dialogue and discussion of workers' activities among stakeholders during the conception, implementation, and management of integrated prevention programs.

• 산학경영연구
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• 제22권2호
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• pp.139-156
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• 2009

산악관광은 관광의 한 분야로서 지속적인 관광수요 창출과 함께 대표적인 관광개발의 대상이 되고 있다. 특히 최근에는 산악관광에 대한 관심과 투자가 급속한 증가 추세에 있고 그 가치와 중요성이 구체적으로 가시화되고 있다. 하지만 산악관광에 대한 선행 연구나 자료가 매우 빈약하고 그 내용 또한 제한적이다. 특히 고산지대 산악관광에 대한 단순한 여행 행태과 동기만이 제한적으로 연구되었다. 본 연구는 고산지대 산악관광의 동기와 제약요인을 규명하고 그 관계성을 검증하는 것을 주된 목적으로 한다. 본 연구를 위한 설문은 인구분포와 산악관광의 주목적지를 고려하여 한국과 인도(시킴), 그리고 네팔(카트만두)에서 조사되었다. 관광객의 산악관광 동기와 제약요인에 관련된 설문지가 제시되었다. 본 연구에서는 산악관광에 대한 한국인의 제약요인이 여타 관광객들에 비해 현저하게 높다는 분석결과와 함께 구조적인 제약요인이 가장 큰 요인임을 입증하였다. 또한 이 연구를 통해 한국인의 산악관광 동기는 건강과 즐거움 추구에 있는데 반해 인도인들을 비롯한 다른 국가의 사람들은 지식추구와 모험심에 기인한다는 결론은 도출하였다. 그리고 환경보존의 중요성은 모든 나라 사람들에게 가장 중요한 산악관광의 과제였음을 확인하였다.