• 한국공작기계학회논문집
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• 제11권5호
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• pp.65-72
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• 2002

In this study, actuator, sensor, guide, power transmission element and control method are considered for ultra-precision positioning apparatus. Through previous process, single plane X-Y stage with ultra-precision positioning is manufactured. Global stage for the purpose of materialization with robust system, is combined by using AC servo motor and ball screw and rolling guide. And ultra-precision positioning system is developed by micro stage with elastic hinge type and piezo element. global servo and micro servo for the purpose of materialization positioning accuracy with nm(nanometer) are controlled simultaneously by using incremental encoder and laser interferometer as displacement measurement sensor. Through previous process, ultra-precision positioning system(100mm stroke and $\pm$ l0nm positioning accuracy) with single plane X-Y stage are materialized.

• 대한기계학회논문집
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• 제18권2호
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• pp.271-277
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• 1994

The fatigue crack opening behavior is analyzed using finite element method. Because extremely fine mesh subdivision is required when using constant stress constant strain triangular element, this study uses conventional two dimensional eight node isoparametric elements. Since plasitc zone size is similar to crack propagating length per each load cycle because of relatively large element size, a new analysis model that a crack propagates every two load cycle is suggested. the opening load and crack opening displacement can be obtained accurately by this method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2824-2826
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• 2002

Immune system is an evolutionary biological system to protect innumerable foreign materials such as virus, germ cell, and etcetera. Immune algorithm is the modeling of this systems response that has adaptation and reliability when disturbance occur. In this paper, immune algorithm is proposed to control four wheels steering AGV(Automated Guided Vehicle) in container yard. The adaptive immune system is applied to the PID controller. For design the PID controller using immune algorithm, we tune PID parameters by off-line manner, in order to avoid the damage from abrupt control force. Repeatedly, the PID parameters are adjusted to be accurate by on-line fine tuner of immune algorithm. And then the computer simulation result from the viewpoint of yaw rate and lateral displacement are analyzed and compared with result of conventional PID controller.

• 산업기술연구
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• 제27권A호
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• pp.121-130
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• 2007

Centrifuge model tests were performed to find appropriate equations proposed previously of estimating the bearing capacity of the composite clayey soil reinforced with sand compaction pile. Model tests were carried out with changing the replacement ratio of SCP (20%, 40%, 70%), contents of fine materials (5%, 10%, 15%) and ratio of treated width to loading width (1B, 2B, 3B). Test results about bearing capacity of the composite ground were obtained by performing the surcharge load tests with measurements of applied loads and vertical displacement. Bearing capacities against bulging and shear failures were estimated by the existing equations. As results of comparing the estimated bearing capacity with experimental values the bearing capacities estimated by Greenwood's equation (1970) for bulging failure mode were similar to the test results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.61-64
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• 2005

Concrete is one of the principal materials for the structure and it is widely used all over the world, but it shows extremely brittle failure under bending and tensile load. Recently to improve such a poor property, Ductile Fiber Reinforced Cementitious Composites (DFRCC) have been developed, and it are defined by an ultimate strength higher than their first cracking strength and the formation of multiple cracking during the inelastic deformation process. This paper is to estimate experimentally the mechanical properties of ductile concrete with the kinds of used fine and coarse aggregate for purpose of development of high ductile concrete mixing coarse aggregate. As the results, ductile concrete mixed coarse aggregate showed the displacement-hardening behavior under bending load similar to DFRCC, and its compressive and bending performance varied according to the kinds of used coarse aggregate.

• Journal of Welding and Joining
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• 제1권2호
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• pp.53-60
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• 1983

COD test based on fracture mechanics concept was used in this study to evaluate the fracture toughness quantitatively. Effects of specimen sizes on critical COD value for ABS EH 36 steel and its submerged arc weldments, and the variation of critical COD value depending on metallurgical/mechanical heterogeneities caused by weld thermal cycles were investigated. Experiment was performed by using specimens made from base metal and submerged arc weldments according to BS 5762. Obtained results are summarized as follows; 1) Critical COD value for base metal decreases with increasing thickness of specimen. On hand, as the reduction ratio of critical COD decreases with increasing specimen thickness, critical COD value becomes constant above a thickness of specimen. 2) Critical COD value for weldment decreases with increasing thickness of specimen and was also affected by metallurgical states of base metal. 3) Size effects for weldment was greater at the hardened region. 4) Critical COD value was affected by microstructural change due to weld thermal cycles in weldments; that is, accicular ferrite formation is favorable for increasing of COD value.

• 자동차안전학회지
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• 제13권3호
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• pp.54-59
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• 2021

Diesel engines emit PM and NOx during combustion. This is the main culprit of fine dust, which seriously affects the atmospheric environment. In particular, large-sized diesel vehicles over 3.5 tons emit a greater amount of pollutants because of their large displacement. The occurrence of vehicle abnormalities in this large-scale diesel vehicle causes even greater problems in the atmospheric environment. It was confirmed that there were many problems caused by natural regeneration DPF among large-sized diesel vehicles. Therefore, the most effective maintenance plan is suggested.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.27-32
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• 2004

Absolute optical angle 센서는 디지털 광학 장치의 핵심적인 부분이라고 말할 수 있으며, 이 장치의 목적은 Pseudorandom-code와 Geometry-code를 이 용하여 코드화된 원판(coded disk)의 상대적/절대적 변위 (Relative/Absolute angle position)를 해결하기 위함이다. 이 기술에서 디스크의 각 위치(Angular position)는 먼저 Pseudorandom-code에 의해 "Coarse" angle이 검출되어 결정되어지며, 그런 다음 Geometry-code의 Pixel 계산에 의해서 얻어지는 "Fine" angular position 데이터는, 7㎛의 Line image 센서를 사용 시, 시스템의 0.006°분해능 결과를 구할 수 있다. 제안된 기술은 비접촉 반사 특성, 시스템의 높은 분해능, 상대적으로 간단한 코트 패턴 그리고 센서의 고유한 디지털 성질을 갖는 등 많은 면에서 새로운 방식이다 더 나아가서 시스템은 두 개의 코드화된 원판에 적용하여 얻어진 절대 자의 변형(Absolute angular displacement)을 관찰하는 방식으로 쉽게 토크 센서로 변경할 수 있다. 제안된 센서의 디지털 광전 특성은 토크와 각을 동시에 측정함으로써 자동 차량 시스템에 사용 시 이상적인 시스템을 만든다. 본문에서는 코드화된 원판의 정확한 각 위치(Angular position)를 결정하기 위하여 Pseudo random-code와 Geometry-code를 활용한 기술을 제안하며, 아이디어의 실행 가능성을 구현하는 실험 결과를 제시하였다.

• The Korean Journal of Physiology
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• 제6권2호
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• pp.49-56
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• 1972

This experiment was designed to explore specific functional relationship between the vestibular canals and the extraocular oblique muscles by observing the isometric tension responeses of the muscles to the selected vestibular canal excitation. The vestibular excitation was simulated by either stimulation of the individual canal nerve or endolymphatic fluid displacement in each canal. Each canal nerve was subjected to square wave pulses with a monopolar wire electrode placed closely to the ampullary nerve endings for electrical stimulation, and a fine stainless cannula was introduced into the each canal toward the ampulla and a minute amount $(0.5{\sim}3.5\;microliter)$ of fluid was injected in or ejected out by means of a microsyringe connected to the cannula to produce ampullopetal or ampullofugal displacement of endolymphatic fluid. The superior oblique muscle was contracted by the excitation of homolateral canals and was relaxed by contralateral canals. On the contrary, the inferior oblique was contracted by the contralateral canals and was relaxed by the homolateral canals. Summation of excitatory and inhibitory canal effects from the bilateral vestibular system was demonstrable on the tension changes of the oblique muscles. Excitation of either dual or triple canals of the unilateral vestibular system also caused summation effect on the tension response of the oblique pair; thus multiple signals from the different ampullary receptors seems to be converged into the relevant ocular motor muclei. Since the superior and inferior obliques are known to receive their motor fibers from the contralateral trochlear nuclei and intermediate nuclei of the homolateral oculomotor complex respectively, the above experimental evidences indicate that the ocular motor nuclei for oblique muscles receive excitatory signals from the contralateral vestibular canals and inhibitory signals from the homolateral canals.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권2호
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• pp.153-160
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• 1999

Dual-stage servo system for super-high density HDD has the chances of being composed of the coarse actuator(VCM) for track-seeking control and the fine actuator(microactuator) for-following control in near future. This paper presents the concept design of dual-stage servo system and the track-following control using an electrostatic microactuator for super-high density HDD. The electrostatic microactuator is designed and fabricated by MEMS(micro-electro-mechanical system) process. Both the nonlinear plant(voltage/displacement-to-electrostatic force) and the linear plant(electrostatic force-to-displacement) of the microactuator are established. Inverse function of the nonlinear plant is employed for a feedforward nonlinear compensator design. And feedforward control effect of this compensator is shown by time-domain experiments. A track-following feedback controller is designed using the feedback nonlinear compensator which is derived from the feedforward nonlinear compensator. The track-following control experiment is done to show the control efficiency of the proposed control system. And, excellent track-following control performance(2.21kHz servo-bandwidth, 7.51dB gain margin, $50.98^{\circ}$phase margin) is achieved by the proposed control system.