• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.1053-1061
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• 2009

The goal of this paper is to investigate the generation characteristics of the main impulsive noise sources generated by the supersonic flow discharging from a muzzle. For this, this paper investigates two fundamental mechanisms to sound generation in shocked flows: shock motion and shock deformation. Shock motion is modeled numerically by examining the interaction of a sound wave with a shock. The numerical approach is validated by comparison with results obtained by linear theory for a small disturbance case. Shock deformations are modeled numerically by examining the interaction of a vortex ring with a blast wave. A numerical approach of a dispersion-relation-preserving(DRP) scheme is used to investigate the sound generation and propagation by their interactions in near-field.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.105-112
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• 2013

This paper presents the structural design and finite element analysis of precision stage based on a double triangular parallel mechanism for precision positioning and large force generation. Recently, with the acceleration of miniaturization in mobile appliances, the demand for precision aligning and bonding has been increasing. Such processes require both high precision and large force generation, which are difficult to obtain simultaneously. This study aimed at constructing a precision stage that has high precision, long stroke, and large force generation. Actuators were tactically placed and flexure hinges were carefully designed by optimization process to constitute a parallel mechanism with a double triangular configuration. The three actuators in the inner triangle function as an in-plane positioner, whereas the three actuators in the outer triangle as an out-of-plane positioner. Finite element analysis is performed to validate load carrying performances of the developed precision stage.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.11a
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• pp.77-81
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• 2007

본 논문은 휴머노이드 로봇의 넘어짐 자세 시 충격량 최소화를 위한 GA 기반의 자세 자동 생성 방법을 제안한다. 관절 공간에서 관절각의 최적 조합으로 충격량을 최소화 할 수 있는 자세의 자동 생성 기법을 구현하였다. 제안된 기법의 검증을 위하여 Sony QRIO 로봇에 대해서 ODE 기반 물리적 특성의 시뮬레이션이 가능한 Webots를 이용하여 실험을 수행하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.213-214
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• 2012

• Structural Engineering and Mechanics
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• v.10 no.1
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• pp.17-26
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• 2000

This paper presents a case study with a multi-degree-of-freedom (MDOF) system where the Floor Response Spectra (FRS) have been derived from a large ensemble of ground motion accelerograms. The FRS are evaluated by the frequency response function which is calculated numerically. The advantage of this scheme over a repetitive time-history analysis of the entire structure for each accelerogram of the set has been highlighted. The present procedure permits generation of FRS with a specified probability of exceedence.

• Proceedings of the KIEE Conference
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• summer
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• pp.117-119
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• 2004

An optimal flight motion simulator path generation method is proposed for hardware in the loop simulation of high maneuverable missile. The proposed method consists of open loop and closed loop path calculation algorithm based on the energy optimal control strategies. The optimal angle command is able to protect the simulator from high acceleration shock at initial control phase.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.94.2-94
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• 2002

$\textbullet$ The method to have real-time response at the motion control. $\textbullet$ The trajectory generation method guarantees the continuous acceleration in changing the velocity during the actuator is moving. $\textbullet$ We propose the velocity profile generation algorithm in order to change object position or object velocity with continuous acceleration using blending method.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.263-267
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• 2006

The path of a flapping airfoil during upstroke and down-stroke is optimized for maximum thrust and propulsive efficiency. The periodic flapping motion in combined pitch and plunge is described using Non-Uniform B-Splines(NURBS). A gradient based algorithm is employed for optimization of the NURBS parameters. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver in a parallel computing environment based on domain decomposition. It is shown that the thrust generation is significantly improved in comparison to the sinusoidal flapping motion. For a high thrust generation, the airfoil stays at a high effective angle of attack for short durations.

• Journal of Broadcast Engineering
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• v.22 no.4
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• pp.429-437
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• 2017

2D-to-3D conversion technology has been studied over past decades and integrated to commercial 3D displays and 3DTVs. Generally, depth cues extracted from a static image is used for generating a depth map followed by DIBR (Depth Image Based Rendering) for producing a stereoscopic image. Further, motion is also an important cue for depth estimation and is estimated by block-based motion estimation, optical flow and so forth. This papers proposes a new method for motion depth generation using Motion History Image (MHI) and evaluates the feasiblity of the MHI utilization. In the experiments, the proposed method was performed on eight video clips with a variety of motion classes. From a qualitative test on motion depth maps as well as the comparison of the processing time, we validated the feasibility of the proposed method.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.32-44
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• 2015

In general, a series of ship steering motion is represented by the combination of translational motion and rotational motion of the ship. Especially, special-functioned ships such as large-scale cruises, ships for installing underwater optical cable, and diver ships must be able to reveal only a translational motion without the change of orientation. In this paper, a method to comprise an integrated control system based on the joystick as a command instrument for translational motion control is suggested. In order to realize the translational motion control system, several algorithms are suggested including the velocity command generation, the selection of motional variables, and the generation and tracking of reference inputs for the selected motional variables. A simulation bench is composed to execute simulations for several translational motion commands. At last, the effectiveness of the proposed method is verified by analyzing the simulation results.