• 한국자기학회지
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• 제5권5호
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• pp.710-715
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• 1995

Magnetic domains were observed using an image lock-in technique for backscattered electron contrast (Type II) with a 200 kV scanning electron microscope. Backscattered electrons indicate a difference in magnetic domain structures at the upper and lower parts of the upper pole in thin-film heads, changing the acceleration voltage. With this method, it is also possible to observe the domain structure of the thin-film head pole through a 10 to $20\;\mu\textrm{m}$ protective layer, and the upper shield of the MR head through the coil in the resist, alumina overcoat, and upper pole.

• 스마트미디어저널
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• 제6권1호
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• pp.61-67
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• 2017

현 시대에 사는 사람들 중에 다수는 자의적이거나 타의적인 이유로 결혼을 하지 않거나 독립하여 혼자 생활하는 것을 선호하고 있고 그 이유로는 크게 타인에게 간섭받기 싫어서 또는 경제적 사정 등이 있으며, 특히 자신만의 편안한 생활을 추구하는 직장여성들이 일인 생활을 선호하는 추세이다. 하지만 이러한 점을 타겟으로 하여 악용하는 범죄의 표적이 되기도 한다. 그로인하여 현관문 등에 안전고리 등과 같은 보안장치를 추가 장착하여 사용하기도 한다. 현관문의 안전고리를 잠그는 행위는 그렇게 어려운 일은 아니지만 쉽게 잊어버릴 수 있고, 취침 전 잠자리에 위치하여 있을 때 안전고리의 잠금 여부를 확인하거나 잠가야할 때 다시 일어나서 현관으로 이동해 안전고리를 확인하고 잠가야 한다. 하지만 그 번거로움과 불편함으로 괜찮겠지 하는 마음에 안전고리를 채우지 않을 때가 많다. 본 논문에서는 이러한 번거로움을 해결하고 보다 안전한 생활을 유지하기위한 방법으로 스마트 폰을 이용하여 원격에서 안전고리를 조정할 수 있는 장치를 설계 및 구현하여 보다 편하게 안전고리를 사용하여 불법주거 침입 등의 범죄로 부터 안전을 도모 하고자 한다.

• Wind and Structures
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• 제2권4호
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• pp.285-303
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• 1999

A discrete vortex method (DVM) has been developed at the Department of Aerospace Engineering, University of Glasgow, to predict unsteady, incompressible, separated flows around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow. This paper gives a brief description of the method and presents the results of calculations on static and transversely oscillating square section cylinders. The results demonstrate that the method successfully predicts the character of the flow field at different angles of incidence for the static case. Vortex lock-in around the resonance point is successfully captured in the oscillatory cases. It is concluded that the vortex method results show good agreement, both qualitatively and quantitatively, with results from various experimental data.

• 제어로봇시스템학회논문지
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• 제4권4호
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• pp.525-533
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• 1998

A conventional contact type brake system which uses a hydraulic system has mny Problems such as time delay response due to pressure build-up, brake pad wear due to contact movement, bulky size, and low braking performance in high speed region. As vehicle speed increases, a more powerful brake system is required to ensure vehicle safety and reliability. In this work, a contactless brake system of an eddy current type is proposed to overcome problems. Optimal torque control which minimizes a braking distance is investigated with a scaled-down model of an eddy current type brake. It is possible to realize optimal torque control when a maximum friction coefficient (or desired slip ratio) corresponding to road condition is maintained. Braking force analysis for a scaled-down model is done theoretically and experimentally compensated. To accomplish optimal torque control of an eddy current type brake system, a sliding mode control technique which is, one of the robust nonlinear control technique is developed. Robustness of the sliding mode controller is verified by investigating the braking performance when friction coefficient is varied. Simulation and experimental results will be presented to show that it has superior performance compared to the conventional method.

• 드라이브 ㆍ 컨트롤
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• 제21권1호
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• pp.1-7
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• 2024

The locking performance of a multi-plate clutch with a mechanical lock-up system is governed by the engagement algorithm. In this paper, a control algorithm to improve the locking performance of the clutch was studied. A 1D dynamic model was constructed and simulated according to the developed algorithm. The developed algorithm was composed of a method in which the locking device is engaged while generating artificial slip on the friction plate by controlling the piston pressure of the clutch. Furthermore, a case study of the parameters within the developed algorithm was conducted to explore combinations that maximize locking performance and analyze trends according to these parameters.

• 한국진공학회지
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• 제5권2호
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• pp.156-160
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• 1996

The purity dependence of the Curie point and the critical exponent of heat capaicty has been studied by measuring the resistvity of nickel samples with several different purities. The resistivity was measured by the 4-point ac method with a lock-in amplifier. The Curie points determined from in-phase and out-of-phase signals were found to be consisten twith each other . We found that the Curie point and the critical exponent of heat capacity did not depend on the purity of samples.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제37권
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• pp.17.1-17.5
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• 2015

Arthroscopy is useful to detect early changes in the temporomandibular joint (TMJ). Despite great advances in arthroscopy, many arthroscopic surgeries have now been replaced by arthrocentesis. We propose a simple diagnostic and therapeutic method having operative rigid ultra-thin arthroscopy with 16 gauge needle size combined with arthrocentesis.

• 한국자동차공학회논문집
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• 제12권3호
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• pp.101-108
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• 2004

A FEM-based efficient method is developed for the shape optimization of 2-D structures. The combined SLP and Simplex method are coupled with finite element analysis. Selected set of master nodes on the design boundaries are employed as design variables and assigned to move towards their normal directions. The other nodes along the design boundaries are grouped into the master node. By interpolating the repositioned master nodes, the B-spline curves are formed so that the rest mid-nodes efficiently settle down on the B-spline curves. Mesh smoothing scheme is also applied for the nodes on the design boundary to maintain most finite elements in good quality. Finally, a numerical implementation of optimum design of an automobile torque converter piston subjected to pressure and centrifugal loads is presented. The results shows additional weight up to 13% may be saved after the shape optimization.

• 한국전자통신학회논문지
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• 제7권2호
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• pp.333-339
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• 2012

통신의 세계적 흐름은 고속화와 디지털화 그리고 대용량화의 추세로 흐르고 있다. 또한 한정된 자원인 주파수를 효율적으로 이용하기 위하여 대역확산 방식이 대표하여 그 주를 이루고 있다. 주파수 합성기로서 통신시스템에 많이 이용되고 있는 PLL(Phase Lock Loop)은 위상잡음 등 여러 가지 문제점을 가지고 있기 때문에, 이러한 문제점을 최소화 할 수 있는 디지털 소자인 직접디지털 합성기(DDS : Direct Digital Synthesis)를 이용하여 고속주파수도약 시스템을 설계하기위한 성능평가에 대하여 연구하여, 오율 개선의 해석과 고속 주파수 도약이 가능한 시스템을 설계하고 그 성능을 평가 하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권2호
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• pp.206-218
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• 2014

The wave attenuation by floating breakwaters in high amplitude waves, which can lead to wave overtopping and breaking, is examined by numerical simulations. The governing equations, the Navier-Stokes equations and the continuity equation, are calculated in a fixed Cartesian grid system. The body boundaries are defined by the line segment connecting the points where the grid line and body surface meet. No-slip and divergence free conditions are satisfied at the body boundary cell. The nonlinear waves near the moving body is defined using the modified marker-density method. To verify the present numerical method, vortex induced vibration on an elastically mounted cylinder and free roll decay are numerically simulated and the results are compared with those reported in the literature. Using the present numerical method, the wave attenuations by three kinds of floating breakwaters are simulated numerically in a regular wave to compare the performance.