• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.437-441
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• 1995

In this paper, the ultra precision positioning system for servo motor and piezo actuator using dual servo loop control has been developed. For positioning system having long distance with ultra precision, the combination of global stage and micro stage is required. Servo moter and ball screw are used as a master stage and piezo acuator as a fine stage. By using this system, an positional precision witin .+-. 30nm has been achieved at dual servo loop control. When using micro stage, an positional precision within .+-. 10nm has been achieved. This result can be applied to develop semiconductor equipment such as wafer stepper.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.60-68
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• 1998

Parallel link manipulators have an ability of more precise positioning than serial open-loop manipulators. However. general parallel link manipulators have been restricted to the real applications since they have limited workspace due to interference among actuators. In this study, we suggest a closed-loop manipulator with 6 degrees-of-freedom and with enlarged workspace. It consists of two parts for minimizing the interference among actuators. One part is lower structure with planar 3 degrees-of-freedom and the other is upper one with spatial 3 degrees-of-freedom. Forward kinematics and inverse kinematics are solved, research about singularity points are carried out and workspace is evaluated. The comparison of workspace between Stewart platform, which is the typical parallel link manipulator, and the suggested manipulator shows that the workspace of the latter is wider than that of the former. Especially, simulation results also show that the suggested manipulator is more suitable when there needs rotation in the end-effector.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.154-163
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• 1999

In this paper, an ultra precision positioning system has been developed using dual servo loop control. For positioning system having long distance with ultra precision , the combination of global stage and micro stage was required. A servo motor based ball screw is used as a global stage and the piezo actuator as a micro stage. For the improvement of positional precision, the digital Chebyshev filter is implemented in the developed to dual servo system. Therefore, the positional repeatability has been achieved within ${\pm}$ 10 mm, and this technique can be applied to develop precision semiconductor equipments such as lithography steppers and probers.

• Geophysics and Geophysical Exploration
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• v.14 no.2
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• pp.158-163
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• 2011

The small-loop electromagnetic (EM) survey is an effective method to delineate contamination areas and pathways of contaminant plumes from landfill. A multi-frequency small-loop EM survey was applied to find them at landfill area, located in delta region, and checked the results with in-situ surveys including 24 trench excavations and 12 drilling boreholes. The correlation between these two results indicates this survey would be suitable to investigate the contamination area. However, it would be difficult to analyze low resistivity less than 10 ohm-m below 10 m depth in delta area without drilling survey because of a limitation to expand the penetration depth lower than 10 m depth due to the separation of 1.66 m between the two coils of GEM-2.

• Journal of Digital Convergence
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• v.20 no.5
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• pp.211-220
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• 2022

This paper proposes a green closed-loop supply chain network (GCSN) for optimizing closed-loop supply chains. The GCSN focuses on the application of the recycling express box in logistics circulation, accelerates the standardization of logistics operations and the use of express packaging in e-commerce companies, and promotes the reduction and greening of recycling express box in the e-commerce industry. The GCSN is represented as a mathematical formulation and implemented using LINGO. Greening, environmental protection, and wisdom are the general trends for promoting the growth of the e-commerce industry. Meanwhile, the price of raw materials has increased owing to a shortage of resources, which emphasizes the need for e-commerce enterprises to develop green packaging. Therefore, this study considers the shared circular packaging launched by e-commerce enterprises as the research object, and integrates the problem of facility positioning and path planning in the logistics system. The conclusion summarizes the significance of this study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.583-590
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• 2008

In this paper, we present a spatially adaptive post-processing algorithm for H.264 video coding standard to remove blocking artifacts. The loop filter of H.264 increases computational complexity of the encoder. Furthermore it doesn't clearly remove the blocking artifacts, resulting in over-blurring. For overcoming them, we combine the projection method with the Constraint Least Squares(CLS) method to restore the high quality image. To reflect the Human Visual System, we adopt the weight norm CLS method. Particularly pixel location-based local variance and laplacian operator are newly defined for the CLS method. In addition, the fact that correlation among adjoining pixels is high is utilized to constrain the solution space when the projection method is applied. Quantization Index(QP) of H.264 is also used to control the degree of smoothness. The simulation results show that the proposed post-processing filter works better than the loop filter of H.264 and converges more quickly than the CLS method.

• Geophysics and Geophysical Exploration
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• v.6 no.3
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• pp.143-152
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• 2003

Among the various geophysical approaches to identify the leakage of leachate with conductivity variation, conventional electrical resistivity survey has been mainly used at waste landfill. We adopted small-loop electromagnetic (EM) survey using multi-frequencies in parallel with electrical resistivity survey to delineate the leakage of leachate through the shallow soil layer at a waste landfill in Jeju Island, and also with self-potential monitoring to detect the streaming potential produced by the movement of leachate. There were no evidences of leakage from waste landfill according to the results of the electrical resistivity survey and SP monitoring, and it was also true from the results of water quality analysis at stream around waste landfill periodically. On the other hand, the results of one-dimensional inversion of spatially-filtered small-loop EM survey data showed the anomalous zone of low resistivity with depth both around and inner waste landfill.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1765-1766
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• 2008

본 논문에서는, 전동기를 이용하는 위치제어 시스템을 이용하여, 이너루프 제어기 유무에 따라 시간 응답 특성 개선 효과에 대하여 실험을 통해 검증하고자 한다. 실험 플랜트로서, 전동기의 속도에 따라 진자의 위치를 제어하는 다중 안정도를 가지고 비선형 시스템인 아라고 진자 시스템을 이용한다. 이 시스템은 속도 정보를 알 수 있는 측정 장치가 없는데, 칼만필터로 전동기의 속도를 추정하고 속도 제어기를 설계하도록 한다. 또한, 선형 시스템을 고려하기 위하여 안정영역 동작점인 진자의 각도가 지면으로 부터 45$^{\circ}$인 선형화 모델을 이용한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.432-438
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• 2005

In this paper, the high precision position control of AC Servo motor for semiconductor equipment is studied. The control system was implemented using TI DSP TMS320F2812 which has 150 MIPS speed for next generation motor control. The controlled 100W PMSM motor has 2,500 ppr optical incremental encoder. The control system has speed controller and current controller to control the motor position. The encoder pulses are divided into 4 times, which has 10,000 ppr and the motor system has the position accuracy of 1/10,000. If the resolution of the encoder is increased, the resolution of the position control will be increased.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.223-225
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• 2006

본 논문에서는 매입형 영구자석 동기전동기(IPMSM)의 속도추정을 위한 새로운 센서리스 알고리즘을 제안한다. 매입형 영구자석 동기 전동기의 기본 전압 방정식을 이용하여 회전자의 자속을 추정하고, 위상고정루프(PLL)를 사용하여 회전자의 위치와 속도를 추정하는 방법으로 센서리스 알고리즘을 구성하였다. Matlab SIMULINK를 이용한 시뮬레이션과 실험을 통하여 제안된 알고리즘을 검증하였다.