• International Journal of Control, Automation, and Systems
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• 제4권4호
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• pp.524-528
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• 2006

A controller built with the gyro effect for a balance-beam can freely control the attitude of an unstructured object by changing the position of an inner gimbal. In this paper, we propose a new balance-beam controller that can detect the inertia of the load to limit the velocity of the load commanded by a user. We found that when there was smaller load inertia, a larger restoration displacement occurred. Therefore, the load can be identified by issuing a predefined command to measure the restoration displacement, which enables us to construct a controller that can limit the angular velocity of the load by planning the motion. Experimental results show the performance of the controller with different loads.

• 한국건축시공학회지
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• 제23권2호
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• pp.175-185
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• 2023

OECD 국가를 대상으로 건설업의 노동생산성을 분석한 결과, 한국 건설업의 2019년 취업자당 노동생산성은 PPP 적용시 주요 선진국보다 낮은 수준이다. PPP 적용시 상대국을 100 기준으로 했을 때, 미국의 76.9, 일본의 88.4, OECD 평균의 85.1로 미흡한 수준이다. 특히 OECD 국가의 2019년도 건설업 취업자당 노동생산성을 분석한 결과, 한국은 25위 수준으로 OECD 35개 국가에서 차지하는 순위는 낮은 수준이다. OECD 국가의 건설시장규모와 건설업 노동생산성을 비교·분석한 결과, 건설시장규모가 큰 국가가 건설업 노동생산성이 높다고는 볼 수 없다. 따라서 본 연구는 건설업의 노동생산성을 향상 시키기 위해서 첫째, 스마트 건설기술을 건설현장에 접목하여 적극 활용하는 방안, 둘째, 건설현장 작업보다는 OSC 기술로 공장작업을 통한 현장 설치작업의 활성화 방안을 제안하였다. 마지막으로 모듈러 공법, 기술개발을 확대할 필요가 있다고 제안하였다. 향후에는 첨단 로봇과 공장자동화를 통한 탈현장 생산방식 및 모듈 개발을 확대하면, 건설산업도 제조업과 같은 생산방식의 개편으로 노동생산성이 높아질 것으로 기대된다.

• International Journal of Control, Automation, and Systems
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• 제2권1호
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• pp.107-117
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• 2004

A new algorithm for planning a collision-free path based on an algebraic curve as well as the concept of path space is developed. Robot path planning has so far been concerned with generating a single collision-free path connecting two specified points in a given robot workspace with appropriate constraints. In this paper, a novel concept of path space (PS) is introduced. A PS is a set of points that represent a connection between two points in Euclidean metric space. A geometry mapping (GM) for the systematic construction of path space is also developed. A GM based on the 2$^{nd}$ order base curve, specifically Bezier curve of order two is investigated for the construction of PS and for collision-free path planning. The Bezier curve of order two consists of three vertices that are the start, S, the goal, G, and the middle vertex. The middle vertex is used to control the shape of the curve, and the origin of the local coordinate (p, $\theta$) is set at the centre of S and G. The extreme locus of the base curve should cover the entire area of actual workspace (AWS). The area defined by the extreme locus of the path is defined as quadratic workspace (QWS). The interference of the path with obstacles creates images in the PS. The clear areas of the PS that are not mapped by obstacle images identify collision-free paths. Hence, the PS approach converts path planning in Euclidean space into a point selection problem in path space. This also makes it possible to impose additional constraints such as determining the shortest path or the safest path in the search of the collision-free path. The QWS GM algorithm is implemented on various computer systems. Simulations are carried out to measure performance of the algorithm and show the execution time in the range of 0.0008 ~ 0.0014 sec.

• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.24-34
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• 2007

Closed-loop active twist control of integral helicopter rotor blades is investigated in this paper for reducing hub vibration induced in forward flight. A four-bladed fully articulated integral twist-actuated rotor system has been designed and tested successfully in wind tunnel in open-loop actuation. The integral twist deformation of the blades is generated using active fiber composite actuators embedded in the composite blade construction. An analytical framework is developed to examine integrally twisted helicopter blades and their aeroelastic behavior during different flight conditions. This aeroelastic model stems from a three-dimensional electroelastic beam formulation with geometrical-exactness, and is coupled with finite-state dynamic inflow aerodynamics. A system identification methodology that assumes a linear periodic system is adopted to estimate the harmonic transfer function of the rotor system. A vibration minimizing controller is designed based on this result, which implements a classical disturbance rejection algorithm with some modifications. Using the established analytical framework, the closed-loop controller is numerically simulated and the hub vibratory load reduction capability is demonstrated.

• International Journal of Control, Automation, and Systems
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• 제6권3호
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• pp.364-377
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• 2008

Due to the difficulty in solving the Hamilton-Jacobi-Isaacs equation, the nonlinear optimal control approach is not very practical in general. To overcome this problem, Ezal et al. (2000) first solved a linear optimal control problem for the linearized model of a nonlinear system given in the strict-feedback form. Then, using the backstepping procedure, a nonlinear feedback controller was designed where the linear part is same as the linear feedback obtained from the linear optimal control design. However, their construction is based on the cancellation of the high order nonlinearity, which limits the application to the smooth ($C^{\infty}$) vector fields. In this paper, we develop an alternative method for backstepping procedure, so that the vector field can be just $C^1$, which allows this approach to be applicable to much larger class of nonlinear systems.

• International Journal of Control, Automation, and Systems
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• 제6권6호
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• pp.809-817
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• 2008

Program plagiarism is widespread due to intelligent software and the global Internet environment. Consequently the detection of plagiarized source code and software is becoming important especially in academic field. Though numerous studies have been reported for detecting plagiarized pairs of codes, we cannot find any profound work on understanding the underlying mechanisms of plagiarism. In this paper, we study the evolutionary process of source codes regarding that the plagiarism procedure can be considered as evolutionary steps of source codes. The final goal of our paper is to reconstruct a tree depicting the evolution process in the source code. To this end, we extend the well-known bioinformatics approach, a local alignment approach, to detect a region of similar code with an adaptive scoring matrix. The asymmetric code similarity based on the local alignment can be considered as one of the main contribution of this paper. The phylogenetic tree or evolution tree of source codes can be reconstructed using this asymmetric measure. To show the effectiveness and efficiency of the phylogeny construction algorithm, we conducted experiments with more than 100 real source codes which were obtained from East-Asia ICPC(International Collegiate Programming Contest). Our experiments showed that the proposed algorithm is quite successful in reconstructing the evolutionary direction, which enables us to identify plagiarized codes more accurately and reliably. Also, the phylogeny construction algorithm is successfully implemented on top of the plagiarism detection system of an automatic program evaluation system.

• International Journal of Control, Automation, and Systems
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• 제3권2호
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• pp.183-194
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• 2005

In this study, we introduce an advanced architecture of genetically optimized Hybrid Fuzzy Neural Networks (gHFNN) and develop a comprehensive design methodology supporting their construction. A series of numeric experiments is included to illustrate the performance of the networks. The construction of gHFNN exploits fundamental technologies of Computational Intelligence (CI), namely fuzzy sets, neural networks, and genetic algorithms (GAs). The architecture of the gHFNNs results from a synergistic usage of the genetic optimization-driven hybrid system generated by combining Fuzzy Neural Networks (FNN) with Polynomial Neural Networks (PNN). In this tandem, a FNN supports the formation of the premise part of the rule-based structure of the gHFNN. The consequence part of the gHFNN is designed using PNNs. We distinguish between two types of the linear fuzzy inference rule-based FNN structures showing how this taxonomy depends upon the type of a fuzzy partition of input variables. As to the consequence part of the gHFNN, the development of the PNN dwells on two general optimization mechanisms: the structural optimization is realized via GAs whereas in case of the parametric optimization we proceed with a standard least square method-based learning. To evaluate the performance of the gHFNN, the models are experimented with a representative numerical example. A comparative analysis demonstrates that the proposed gHFNN come with higher accuracy as well as superb predictive capabilities when comparing with other neurofuzzy models.

• International Journal of Control, Automation, and Systems
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• 제2권4호
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• pp.423-434
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• 2004

In this paper, we introduce a new topology of Self-Organizing Polynomial Neural Networks (SOPNN) based on genetically optimized Multi-Layer Perceptron (MLP) and discuss its comprehensive design methodology involving mechanisms of genetic optimization. Let us recall that the design of the 'conventional' SOPNN uses the extended Group Method of Data Handling (GMDH) technique to exploit polynomials as well as to consider a fixed number of input nodes at polynomial neurons (or nodes) located in each layer. However, this design process does not guarantee that the conventional SOPNN generated through learning results in optimal network architecture. The design procedure applied in the construction of each layer of the SOPNN deals with its structural optimization involving the selection of preferred nodes (or PNs) with specific local characteristics (such as the number of input variables, the order of the polynomials, and input variables) and addresses specific aspects of parametric optimization. An aggregate performance index with a weighting factor is proposed in order to achieve a sound balance between the approximation and generalization (predictive) abilities of the model. To evaluate the performance of the GA-based SOPNN, the model is experimented using pH neutralization process data as well as sewage treatment process data. A comparative analysis indicates that the proposed SOPNN is the model having higher accuracy as well as more superb predictive capability than other intelligent models presented previously.reviously.

• 대한토목학회논문집
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• 제26권6D호
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• pp.969-974
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• 2006

국내 건설현장 기능 인력 부족 문제가 심각하다. 현재 국내 건설현장은 신규 인력 진입 저조에 따른 공급 부족과 기능 인력의 고령화에 따른 생산성 저하 등 양적, 질적인 문제를 동시에 겪고 있다. 여기에 현재 계획되고 있는 대규모 국가사업으로 향후 건설현장 기능 인력의 부족은 더욱 심각해질 전망이다. 건설현장 기능인력 수급 불균형 문제에 대한 해결방안으로서의 공급 확보 정책은 시대의 흐름과 기술 발전에 따른 미래 전망을 고려해볼 때, 어느 정도 한계가 있다고 판단되며, 기술적 접근을 통해 기능 인력에 대한 수요를 줄이는 노력이 병행되어야 한다고 판단된다. 기술 발전을 통한 기능인력 수요 감소를 위해서는 현장에서 수행되는 작업 프로세스의 생산성과 효율성을 향상시킬 수 있는 분야에 연구의 초점이 맞춰져야 하며, 기능인력 수요 저감의 핵심이 되며 연구개발 노력이 필요한 분야로서 1) 건설 자동화 및 기계화 확대를 통한 기능 인력의 대체, 2) 고성능 건설 자재 개발 및 활용으로 현장 작업량 저감, 3) 정보화 기술 도입으로 현장 작업대기 시간 감축에 의한 생산성 향상, 4) 모듈화, 선조립, 공장제작 등 선작업 방식의 적용을 통한 현장 기능 인력 수요 저감 및 생산성 향상, 5) 재설계/재시공 예방으로 추가 작업 발생 방지, 6) 기능 및 직종 통합에 의한 다기능 인력 양성, 7) 시공 프로세스 개선에 의한 작업 생산성 향상 등의 7가지 주제를 제시하였다.