• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 춘계학술대회 논문집
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• pp.131-136
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• 1997

This paper represent the variable structure adaptive mode control technique which is new approach to implement the robust control of industrial robot manipulator with external disturbances and parameter uncertainties. Sliding mode control is a well-known technique for robust control of uncertain nonlinear systems. The robustness of sliding model controllers can be shown in contiuous time, but digital implementation may not preserve robustness properties because the sampling process limits the existence of a true sliding mode. the sampling process often forces the trajectory to oscillate in the neighborhood of the sliding surface. Adaptive control technique is particularly well-suited to robot manipulators where dynamic model is highly complex and may contain unknown parameters. Adaptive control algorithm is designed by using the principle of the model reference adaptive control method based upon the hyperstability theory. The proposed control scheme has a simple sturcture is computationally fast and does not require knowledge of the complex dynamic model or the parameter values of the manipulator or the payload. Simulation results show that the proposed method not only improves the performance of the system but also reduces the chattering problem of sliding mode control, Consequently, it is expected that the new adaptive sliding mode control algorithm will be suited for various practical applications of industrial robot control system.

• 지능정보연구
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• 제13권3호
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• pp.63-82
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• 2007

본 논문에서는 유연제조시스템(FMS)에서 다단계스케줄링 문제를 효율적으로 해결하기 위한 적응형 혼합유전 알고리즘(ahGA) 접근법을 제안한다. 제안된 ahGA는 FMS의 해를 개선시키기 위하여 이웃탐색기법을 사용하며, 유전탐색과정에서의 수행도를 향상시키기 위해 유전알고리즘(GA)의 파라메터들을 조정하기 위한 적응형 구조를 사용한다. 수치실험에서는 제안된 ahGA와 기존의 알고리즘들 간의 수행도를 비교하기 위하여 두가지형태의 다단계스케줄링문제를 제시한다. 실험결과는 제안된 ahGA가 기존의 알고리즘들 보나 더 뛰어난 수행도를 보여주고 있다.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.535-545
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• 2006

A nonlinear analysis of torsional self-excited vibration in the driveline system for wheeled towing tractors was presented, with a 2-DOF mathematical model. The vibration system was described as a second-order ordinary differential equation. An analytical approach was proposed to the solution of the second-order ODE. The mathematical neighborhood concept was used to construct the interior boundary and the exterior boundary. The ODE was proved to have a limit cycle by using $Poincar\'{e}-Bendixson$ Annulus Theorem when two inequalities were satisfied. Because the two inequalities are easily satisfied, the self-excited vibration is inevitable and even the initial slip rate is little. However, the amplitude will be almost zero when the third inequality is satisfied. Only in a few working modes of the towing tractor the third inequality is not satisfied. It is shown by experiments that the torsional self-excited vibration in the driveline of the vehicle is obvious.

• 한국멀티미디어학회논문지
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• 제18권6호
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• pp.701-709
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• 2015

Image stitching method is a technique for obtaining an high-resolution image by combining two or more images. In X-ray image for clinical diagnosis, the size of the imaging region taken by one shot is limited due to the field-of-view of the equipment. Therefore, in order to obtain a high-resolution image including large regions such as a whole body, the synthesis of multiple X-ray images is required. In this paper, we propose a rapid stitching method of digital X-ray images using template-based registration. The proposed algorithm use principal component analysis(PCA) and k-nearest neighborhood(k-NN) to determine the location of input images before performing a template-based matching. After detecting the overlapping position using template-based matching, we synthesize input images by alpha blending. To improve the computational efficiency, reduced images are used for PCA and k-NN analysis. Experimental results showed that our method was more accurate comparing with the previous method with the improvement of the registration speed. Our stitching method could be usefully applied into the stitching of 2D or 3D multiple images.

• 천문학회지
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• 제40권4호
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• pp.153-155
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• 2007

We have analyzed H and $K_s$-band images of the Arches cluster obtained using the NIRC2 instrument on Keck with the laser guide star adaptive optics (LGS AO) system. With the help of the LGS AO system, we were able to obtain the deepest ever photometry for this cluster and its neighborhood, and derive the background-subtracted present-day mass function (PDMF) down to $1.3M_{\bigodot}$ for the 5"-9" annulus of the cluster. We find that the previously reported turnover at $6M_{\bigodot}$ is simply due to a local bump in the mass function (MF), and that the MF continues to increase down to our 50 % completeness limit ($1.3M_{\bigodot}$) with a power-law exponent of ${\Gamma}$ = -0.91 for the mass range of 1.3 < M/$M_{\bigodot}$ < 50. Our numerical calculations for the evolution of the Arches cluster show that the ${\Gamma}$ values for our annulus increase by 0.1-0.2 during the lifetime of the cluster, and thus suggest that the Arches cluster initially had ${\Gamma}$ of $-1.0{\sim}-1.1$, which is only slightly shallower than the Salpeter value.

• 전자공학회논문지
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• 제50권9호
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• pp.100-106
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• 2013

AMI는 스마트미터를 기반으로 전력소비자와 생산자간에 양방향 정보 교환을 가능하게 함으로서 에너지 효율을 극대화시키는 시스템이다. AMI 시스템을 성공적으로 구축하기 위해서는 안정된 통신망 구축이 필요하다. 본 논문은 다양한 통신방식 중 IEEE 802.11s 무선메쉬 기술을 AMI 시스템에 적용해 봄으로서 원격검침 통신망으로 활용가능성을 검증한다. 실험 결과, 802.11s 무선기술은 메쉬망을 통해 넓은 커버리지 뿐만 아니라 안정된 통신성능을 제공하는 것을 확인할 수 있었다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제16권3호
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• pp.163-172
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• 2016

Electric load forecasting is essential for effective power system planning and operation. Complex and nonlinear relationships exist between the electric loads and their exogenous factors. In addition, time-series load data has non-stationary characteristics, such as trend, seasonality and anomalous day effects, making it difficult to predict the future loads. This paper proposes a locally-weighted polynomial neural network (LWPNN), which is a combination of a polynomial neural network (PNN) and locally-weighted regression (LWR) for daily shortterm peak load forecasting. Model over-fitting problems can be prevented effectively because PNN has an automatic structure identification mechanism for nonlinear system modeling. LWR applied to optimize the regression coefficients of LWPNN only uses the locally-weighted learning data points located in the neighborhood of the current query point instead of using all data points. LWPNN is very effective and suitable for predicting an electric load series with nonlinear and non-stationary characteristics. To confirm the effectiveness, the proposed LWPNN, standard PNN, support vector regression and artificial neural network are applied to a real world daily peak load dataset in Korea. The proposed LWPNN shows significantly good prediction accuracy compared to the other methods.

• 한국콘텐츠학회논문지
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• 제5권2호
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• pp.221-228
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• 2005

본 논문은 인간의 공간 지각 특성을 이용하여 에지를 강조하는 개선된 오차 확산 해프토닝 시스템을 제안한다. 제안방법은 원 화소의 명암값과 $3{\times}3$ 블록의 평균 명암값과의 차이 값에 공간적 위치 값에 따른 가중치를 결합하여 공간 변화량(SV: spatial variation)을 구한다. SV와 국부 평균을 이용하여 계산한 에지 강조 정보량(IEE: information of edge enchancement)을 양자화기 입력에 더하여 해프톤 영상의 에지를 강조한다. 제안방법의 성능은 에지 상관도 평가 함수로 평가했으며 제안방법을 영상에 적용한 결과 이진 영상의 에지가 강조되어 시각적으로 선명한 결과를 보이며 미세한 에지도 잘 보존되었다.

• 한국재난정보학회 논문집
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• 제11권4호
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• pp.515-519
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• 2015

'13년 87건, '14년 104건의 화학사고는 인명과 환경에 막대한 피해를 가져왔다. 또한 산업계는 피해처리와 복구에 많은 비용지출을 하였고 기업이미지에 큰 영향을 받았다. 대기 중으로의 빠른 확산과 독성을 갖는 화학사고는 근로자 뿐만 아니라 주변 거주 주민 등에도 위협적인 존재이다. 이러한, 화학사고의 원인을 철저히 분석하기 위해서는 체계적인 조사절차와 신뢰성 있는 결과가 도출되어야 한다. 본 연구를 통해 사고조사를 담당하는 각 기관의 제도를 비교 분석하여 화학사고 현장조사 체계마련 시 기본 자료로 활용이 가능할 것으로 판단된다.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 1996년도 추계 학술 발표회 발표논문집
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• pp.217-227
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• 1996

The new filed of learning control develops controllers that learn to improve their performance at executing a given task , based on experience performing this specific task. In a previous work[6], authors presented a theory of indirect learning control based on use of indirect adaptive control concepts employing simultaneous identification and control. This paper develops improved indirect learning control algorithms, and studies the use of such controller indecentralized systems. The original motivation of the learning control field was learning in robots doing repetitive tasks such as on an asssembly line. This paper starts with decentralized discrete time systems. and progresses to the robot application, modeling the robot as a time varying linear system in the neighborhood of the nominal trajectory, and using the usual robot controllers that are decentralized, treating each link as if it is independent of any coupling with other links. The resultof the paper is to show that stability of the indirect learning controllers for all subsystems when the coupling between subsystems is turned off, assures convergence to zero tracking error of the decentralized indirect learning control of the coupled system, provided that the sample tie in the digital learning controller is sufficiently short.