• Proceedings of the Korean Information Science Society Conference
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• 2010.06a
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• pp.287-292
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• 2010

컴퓨터의 성능을 향상하기 위해 주로 프로세서의 성능을 놓여 왔으나 발열 및 집적도 등의 문제로 인하여 한계를 가지게 되었고, 이를 해결하기 위하여 멀티 판로세서와 멀티 코어 시스템이 등장하였다. 이러한 시스템은 두 개 이상의 처리기를 사용하여 단일 처리기 시스템보다 놓은 성능을 갖으며 비교적 낮은 전력을 소모하기 때문에 점차 사용이 증가하고 있다. 운영체제도 이러한 다중 처리기 시스템을 위한 기능이 추가 되어 효율적으로 사용하여 성능을 놓이기 위해 변화하고 있다. 부하 분산 알고리즘 역시 예전의 스케줄러에는 들어있지 않는 기법이었으나 멀티 프로세서가 등장한 이후로 추가 되었다. 본 논문에서는 이 전 방식의 부하 분산 알고리즘에 유동적인 기준점을 추가하여 성능을 개선하고자 한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05d
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• pp.1012-1016
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• 2002

분산시스템에서 부하균형을 유지하기 위해서는 네트워크상의 각 노드는 다른 노드들의 부하상태정보를 가져야만 한다. 네트워크상에 ν개의 노드가 존재할 때 모든 노드간에 부하상태정보를 교환하기 위해서는 Ο(ν²)의 트래픽 오버헤드가 필요하게 된다. 이 논문에서는 분산된 노드간에 동기적으로 동작하는 부하균형 알고리즘을 제시한다. 이를 위해 먼저 SBIBD(symmetric balanced incomplete block design)에 근거하여 (ν,k,1)-configuration에 의해 ν=k²-k＋1개의 노드를 갖는 네트워크 토폴로지를 구성하였다. 이 망에서 동작하도록 고안된 부하상태정보 전파 알고리즘은 (equation omitted)의 메시지 오버헤드를 가지면서 각각의 노드가 ν개의 모든 노드에 대한 부하상태정보를 가지도록 한다. 또한 이 부하균형 알고리즘은 모든 링크가 부하상태정보 전송을 위해 동일한 트래픽을 갖도록 설계되었다.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.223-226
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• 1999

This paper presents the theoretical analysis method to determine the stress concentrations around the circular cutouts with various geometrical parameters. The purposes of this study are to investigate on the stress distribution around the circular cutouts due to interaction between two circular cutouts and to develop the design method in composite plates. The composite laminated plate with 2 equal collinear circular cutouts under inplane loads is treated as an quasi-isotropic, symmetric, finite, square, multiply connected and thin plate. The effects of cutout sizes, distances between two circular cutouts and inplane load conditions on stress distribution are studied in detail.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1619-1625
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• 1997

This paper concerns a 2-axis PR type pneumatic manipulator system translating in vertical and rotating in horizontal directions. A simplified linear model is mathematically formulated similar to the pneumatic acturators in dynamic responses in order to devise an appropriate position control scheme. A PD controller preceding the on/off solenoid valve turns out not only economical but also effective in reducing rise time and amplitude of limit cycles, if its control gains are determined on the basis of frequency response. And, additional implementation of symmetric or asymmetric deadband at the PD controller output greatly helps minimize valve opening numbers, positional error, and undesirable direction-dependent property due to the gravitational load. Such a control concept is synthesized through numerical simulations and next applied to the experimental set-up, featuring enhanced positional servo characteristics.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.6
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• pp.102-106
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• 2004

The purpose of the study is to perform structual analysis of 9 type bellows for automotive. The bellows joint which was used as a absorber or safety equipment to prevent the deformation or fracture of a structure, has been analyzed by the FEM modeling using axi-symmetric conical frustum element. Using FEM the general behavior of bellows analysis can be investigate easily, as well as the stability of the analysis can be guarantee. The results of finite element structual analysis and actual result gave a good agreement.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.214-220
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• 1998

The determination of sound pressure radiated from periodic plate structures is fundamental in the estimation of noise levels in aircraft fuselages and ship hull structures. As a robust approach to this problem, here a very general and comprehensive analytical model for prediction the sound radiated by a vibration plate stiffened by periodically spaced orthogonal symmetric beams subjected to a sinusoidally time varying point load is developed. The plate is assumed to be infinite in extent, and the beams are considered to exert both line force and moment reactions on it. Structural damping is included in both plate and beam materials. From this theoretical model, the sound pressure levels on axis in a semi-infinite fluid(water) bounded by the plate with the variation in the loactions of an external using three numerical tools such as the Gauss-Jordan method, the LU decomposition method and the IMSL numerical package.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.189-194
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• 2001

This paper presents a mew design of an inductive position sensing system with high sensitivity. The designed system consists of the driving coils, position-detecting coils, and closed loop formed magnetic blocks. To obtain high sensitivity we design a symmetric and closed loop type measuring system with small air-gaps. The elements that affect the system characteristics are turn ratio, excitation frequency, air-gap size, capacitance effect, and load resistance. By experimental investigation, the influences of these elements are examined and the system parameters are selected. The sensitivity of the newly designed system is greater than 2800mV/(V mm) and the linearity error is below${\pm}0.01%; in; the; range; of; {\pm}200{\mu}m$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.230-231
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• 2011

There is a merit a planetary gear set disperses a delivery load, and to decrease loss of friction and noise. But, in addition to meshing this internal and external gear simultaneously and phase difference by the tooth contact point and the time difference occurs asymmetric and symmetric sideband noise and vibration caused by the modulation in the vehicle. Existing planetary gear set research have progressed to reduce the cause of the sideband as run-out, pitch error and imbalance. In this paper presents a method for the design of the carrier phase difference by developing various theorys and experiments for gear noise.

• Journal of electromagnetic engineering and science
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• v.9 no.1
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• pp.32-37
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• 2009

Various Class-E CMOS power amplifiers for GSM applications are presented. A stage-convertible transformer for a dual mode power amplifier is proposed to increase efficiency in the low-output power region. An integrated passive device(IPD) process is used to reduce combiner losses. A split secondary 1:2 transformer with IPD process is designed to obtain efficient and symmetric power combining. A quasi-four-pair structure of CMOS PA is also proposed to overcome the complexities of power combining.

• Structural Engineering and Mechanics
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• v.37 no.3
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• pp.285-296
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• 2011

The plane crack-contact problem for an infinite elastic layer with two symmetric rectangular rigid stamps on its upper and lower surfaces is considered. The elastic layer having an internal crack parallel to its surfaces is subjected to two concentrated loads p on its upper and lower surfaces trough the rigid rectangular stamps and a pair of uniform compressive stress $p_0$ along the crack surface. It is assumed that the contact between the elastic layer and the rigid stamps is frictionless and the effect of the gravity force is neglected. The problem is reduced to a system of singular integral equations in which the derivative of the crack surface displacement and the contact pressures are unknown functions. The system of singular integral equations is solved numerically by making use of an appropriate Gauss-Chebyshev integration formula. Numerical results for stress-intensity factor, critical load factor, $\mathcal{Q}_c$, causing initial closure of the crack tip, the crack surface displacements and the contact stress distribution are presented and shown graphically for various dimensionless quantities.