• 한국항행학회논문지
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• 제26권4호
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• pp.226-234
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• 2022

자율주행체와 네트워크기반 제어 기술의 발달에 따라서, 하나의 에이전트를 제어하는 것을 넘어서 다수의 이동체를 분산 제어하는데 사용 가능한 다중 에이전트의 컨센서스 제어에 대한 관심과 연구가 증가하고 있다. 컨센서스 제어는 분산형 제어이기 때문에, 정보 교환은 실제 시스템에서 지연을 가지게 된다. 또한, 시스템에 대한 모델을 정확히 수식적으로 표현하는데 있어서 한계를 갖는다. 이런 한계를 극복하는 방법 중에 하나로서 강화 학습 기반 컨센서스 알고리즘이 개발되었지만, 불확실성이 큰 환경에서 느린 수렴을 갖는 경우가 자주 발생하는 특징을 보이고 있다. 따라서, 이 논문에서는 불확실성에 강인한 특성을 갖는 슬라이딩 모드제어를 강화학습과 결합한 슬라이딩 강화학습 알고리즘을 제안한다. 제안 알고리즘은 기존의 강화학습 기반 컨센서스 알고리즘의 제어 신호에 슬라이딩 모드 제어 구조를 추가하고, 시스템의 상태 정보를 슬라이딩 변수를 추가하여 확장한다. 모의실험 결과 다양한 시변 지연과 왜란에 대한 정보가 주어지지 않았을 때에 슬라이딩 강화학습 알고리즘은 모델기반의 알고리즘과 유사한 성능을 보이면서, 기존의 강화학습에 비해서 안정적이면서 우수한 성능을 보여준다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1615-1620
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• 2003

Kinematic calibration is a process whereby the actual values of geometric parameters are estimated so as to minimize the error in absolute positioning. Measuring all components of Cartesian posture, particularly the orientation, can be difficult. With partial pose measurements, all parameters may not be identifiable. This paper proposes a new device that can identify all kinematic parameters with partial pose measurements. Study is performed for a six degree-of-freedom fully parallel Hexa Slide manipulator. The device, however, is general and can be used for other parallel manipulators. The proposed device consists of a link with U joints on both sides and is equipped with a rotary sensor and a biaxial inclinometer. When attached between the base and the mobile platform, the device restricts the end-effector's motion to five degree-of-freedom and can measure position of the end-effector and one of its rotations. Numerical analyses of the identification Jacobian reveal that all parameters are identifiable. Computer simulations show that the identification is robust for the errors in the initial guess and the measurement noise. Intrinsic inaccuracies of the device can significantly deteriorate the calibration results. A measurement procedure is proposed and formulations of cost functions are discussed to prevent propagation of the inaccuracies to the calibration results.

• 한국동물위생학회지
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• 제29권2호
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• pp.103-110
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• 2006

Ticks cause economic losses to the deer industry by decreasing the growth and production of the farmed animals. The mediation of ticks affects humans and animals by causing contagious disease both directly and indirectly. Blood from farmed deer from the areas near Jangsu branch was collected for screening of infectious protozoa and rickettsial disease. Seventy deer blood samples were collected from 30 different deer farms located in Jinan, Jangsu and Muju. This blood samples were used for blood slide smear examination and hematological analysis. DNA from these samples was extracted and was used for PCR analysis for detection of gene fragments of Theileria spp, Babesia spp, Anaplasma spp and Ehrlichia spp. In the blood slide smear examination and PCR analysis all samples did not show presence of protozoal and rickettsial diseases. Eight blood samples showed anemia, 1 sample showed iron deficiency and 7 samples showed regenerative anemia. Results for PCR analysis showed 2 samples were positive for T orientalis. All DNA samples were negative for Babesia spp, Anaplasma spp, and Ehrlichia spp.

• 한국정밀공학회지
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• 제15권5호
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• pp.93-99
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• 1998

Although laser interferometer measurement system has advantages of measurement range and accuracy, it has some disadvantages when measurement of multi degrees of freedom of motion are required. Because the traditional error measurement methods for geometric errors (two straightness and three angular errors) of a slide of machine tools measures error components one at a time. It may also create an optical path difference and affect the measurement accuracy. In order to identify and compensate for geometric errors of a moving rigid body in real time processes, an on-line error measurement system for simultaneous detection of the five error components of a moving object is required. Using laser alignment technique and some optoelectronic components, an on-line measurement system with 5 degrees of freedom was developed for the geometric error detection in this study Performance verification of the system has been performed on an error generating mechanism. Experimental results show the feasibility of this system for identifying geometric errors of a slide of machine tools.

• 한국정밀공학회지
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• 제30권7호
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• pp.754-761
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• 2013

Thermal displacement is an important issue in machine tool systems. During the last several decades, thermal error compensation technology has significantly reduced thermal distortion error; this success has been attributed to the development of a precise, robust thermal error model. A major advantage of using the thermal error model is instant compensation for the control variables during the modeling process. However, successful application of thermal error modeling requires correct determination of the temperature sensor placement. In this paper, a procedure for predicting thermal-mode-based thermal error is introduced. Based on this thermal analysis, temperature sensors were positioned for multiple heat-source models. The performance of the sensors based on thermal-mode error analysis, was compared with conventional methods through simulation and experiments, for the case of a slide table in a transient state. Our results show that for predicting thermal error the proposed thermal model is more accurate than the conventional model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1494-1499
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• 2003

Kinematic calibration is a process whereby the actual values of geometric parameters are estimated so as to minimize the error in absolute positioning. Measuring all components of Cartesian posture, particularly the orientation, can be difficult. With partial pose measurements, all parameters may not be identifiable. This paper proposes a new device that can be used to identify all kinematic parameters with partial pose measurements. Study is performed for a six degree-of-freedom fully parallel Hexa Slide manipulator. The device, however, is general and can be used for other parallel manipulators. The proposed device consists of a link with U joints on both sides and is equipped with a rotary sensor and a biaxial inclinometer. When attached between the base and the mobile platform, the device restricts the end-effector's motion to five degree-of-freedom and can measure position of the end-effector and one of its rotations. Numerical analyses of the identification Jacobian reveal that all parameters are identifiable. Computer simulations show that the identification is robust for the errors in the initial guess and the measurement noise.

• 전기전자학회논문지
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• 제28권2호
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• pp.180-186
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• 2024

본 논문에서는 CNN을 이용한 3상 유도모터 ITSC(Inter-Turn Short Circuit) 고장진단에 있어서, 전류 데이터를 이용한 고장 진단 및 효율적인 이미지 encoding 방법을 제안하도록 한다. 진동, 소음센서를 이용한 방법과 달리 전류를 이용하는 방법은 데이터의 손실이 낮을 수 있다는 장점은 있지만, 3상 신호로 인해 CNN의 채널 수 증가의 부담이있다. 이에 D-Q 동기좌표계의 D축 성분만의 데이터를 활용하여 채널 부담을 줄이고, 효율적인 입력 이미지 구성 방법을 알아보고자 SWM(Slide Window Method)과 GAF(Gramian Angular Field)방식을 비교하도록 하였다. 데이터는 무부하부터 전부하까지 전체 변화를 고려하였으며, 그 결과, GAF방식은 약 74%, SWM방식은 약 65%로, GAF방식이 약 9%의 높은 정확도를 보임을 알 수 있었다. 또한, 학습된 속도에 있어서 약 14.74[s]로 전체 학습 시간대비 차이가 없었으며, 100 epoch 이하에서는 빠른 속도로 학습이 가능함을 알 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.423-426
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• 2002

A custom micro-PIV optics assembly has been used to measure the flow field inside a T-shaped microchannel. The micro-PIV system consists of microscope objectives of various magnifications, a dichroic cube, and an 8-bit CCD camera. Fluorescent particles of diameters 620nm have been used with a Nd:YAG laser and color filters. A programmable syringe pump with Teflon tubings were used to inject particle-seeded distilled water into the channel at flow rates of $420,\;40,\;60{\mu}L/hr$. The microchannels are fabricated with PDMS with a silicon mold, then $O_2-ion$ bonded onto a slide glass. Results show differences in flow characteristics and resolution according to fluid injection rates, and magnifications, respectively. The results show PIV results with vector-to-vector distances of $2{\mu}m$ with 32 pixel-square interrogation windows at $50{\%}$ overlap.

• 한국조경학회지
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• 제13권1호
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• pp.123-130
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• 1985

In this study, the distribution of players on a soccer field was investigated with slide -photos in order to suggest a basic data for the athletic turf maintenance and construction. The results of this investigation may be summarized as follows. 1) There's a tendency that trampling frequency per grid (32.23m$^2$)of a soccer field gradually increases from the corner area to the center. Especially the area around goal and center-circle get the highest frequency. 2) Trampling numbers per grid show the similar tendency to trampling fequency. And the grid around the goal get the highest trampling number per grid.(6.52 times/32.23m$^2$). 3) The extent of the damage to the athletic turf per grid also show the similar tendency to the foregoing results. Under such extent of the damage to the athletic turf as these, the method of the turf maintenance and construction will be made.

• 한국광학회지
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• 제34권6호
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• pp.283-288
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• 2023

본 연구에서는 quartz, sapphire, slide glass와 같이 투명한 기판 위에 (3-mercaptopropyl) trimethoxysilane (MPTMS)를 처리하고 나노미터 두께로 은을 증착하여 형성된 은 나노 박막의 광학적, 전기적 특성을 탐구한다. 기판의 MPTMS 증착에 따라 각각 5, 7, 9, 13 nm 두께를 갖는 은 나노 박막의 표면 형태 변화를 전자현미경을 통해 확인하고, UV-visible 전자기파 영역의 투과 측정 실험을 통해 금속 나노 박막에서 나타나는 국소 표면 플라즈몬에 의한 흡수 효과가 줄어드는 것을 확인하였다. 이는 MPTMS에 의해 나노미터 두께의 금속 박막이 균일하게 형성된 것을 의미한다. 또한 MPTMS 증착 시간을 30분부터 77시간까지 조절함으로써 UV-visible 투과율과 전기전도도 변화를 측정하여 균일한 금속 나노 박막 형성을 위한 MPTMS의 증착 조건에 대해 탐구한다. 본 연구 결과는 투명 기판 위 균일한 금속 나노 박막 형성에 대한 연구 및 고성능 나노 박막 전극 개발 등과 같은 응용 분야에 도움이 될 것이다.