• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.829-830
• /
• 2008

In modern days, many of the images are captured by using various devices, such as PDA, digital camera, or cell phone camera. Because all these devise have a limited dynamic range, images captured in real world scenes with high dynamic ranges usually exhibit poor visibility and low contrast, which may make important image features lost or hard to tell by human viewers. In this paper, the efficient color image enhancement method is presented. Experimental result show that the proposed method yields better performance of color enhancement over the previous work for test color images.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.9
• /
• pp.1795-1805
• /
• 2002

A position controller which can achieve a specified dynamic performance irrespective of the different operating position of the pneumatic cylinder is proposed. The position controller developed in this paper is composed of a nonlinear compensator and a disturbance observer. The nonlinear compensator which feeds back position, velocity and acceleration is derived from the nonlinear dominating equations of the position control system to compensate for variation of dynamic characteristics of a pneumatic cylinder according to the change of the operating position. The disturbance observer including a simplified linear model is designed to reduce the effect of model discrepancy in the low frequency range which cannot be suppressed by the nonlinear compensator. The results of the experiments show that the position control performance maintains a designed performance regardless of the variations of an operating position of the pneumatic cylinder.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.6
• /
• pp.1446-1454
• /
• 1990

A systematic method of design modification to reduce the influence of impact from multiple clearances in a planar four bar mechanism is developed. For this purpose, an optimization method is used with the objective function which is the linear sum of the Earles and Wu criteria for every joints with clearances. One coil spring is attached to a joint of limited range of revolution to reduce the undesirable dynamic effects due to clearances at joints. The stiffness of the coil spring and its pre-loading angle are chosen as design variables. A numerical example is taken for a four bar mechanism. The initial and modified mechanisms are compared using a clearance mechanism analysis technic to see the difference in dynamic effects due to contact loss. It is found that the modified mechanism produces much more smooth joint contact forces than the original design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.356-361
• /
• 2001

A research to maximize the force transmitted from a vibration motor at the vibration mode, installed in the cellular phone jig, is presented in this study. When the natural frequencies corresponding to the structural vibration modes of the set exist within the range of the driving frequencies acquired by changing the RPM of the vibration motor, the structural vibration resonance is applicable to maximization of the vibration force sensible to the human body such as hands, arms, and hips. The analytical modal analysis using the Finite Elements and the experimental modal testing for the set jig were performed in order to understand the structural modes and the corresponding frequencies. Then the dynamic responses of the set jig to the given driving frequency were measured and the results on maximizing the vibration were confirmed by the FEM dynamic simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11a
• /
• pp.316.2-316
• /
• 2002

There are a lot of roots of errors in the motion of the optical pickup actuator being one of the most significant components in the CD-ROM drive. Most of the studies recently performed have a tendency to seek fur the causes from an actuator itself. We found the fact that the range of the natural frequencies of a feeding deck and an actuator is close each other through an experiment. This paper present the dynamic characteristics of an actuator affected by the motion of a feeding deck. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.744-749
• /
• 2001

As related to rotordynamics, dynamic characteristics of the wear ring seal in high pressure multi-stage pump is calculated in the cases of labyrinth, damper and helically grooved types. The. results show that the labyrinth seal type has superior performance in the view point of leakage. However, in terms of rotordynamics view point, the damper seal type gains acceptable separate margin in critical speed range, while it has slightly inferior leakage performance compared to labyrinth seal type.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.11
• /
• pp.1059-1065
• /
• 2004

In this paper, the dynamic characteristic analysis of carriage structure supported by air bearings were performed. Toward this end, the characteristics of air bearing were numerically analyzed to estimate the stiffness of the air bearing and the clearance between air bearing and guide surface. The modal analysis of the carriage structure was performed by using finite element method, and the experimental modal analysis was also performed to validate the finite element model, where rigid body modes were compared to validate the stiffness of the air bearings. From the results, the air spring stiffness can be estimated within the range of acceptable accuracy under any pressure and clearance condition.

• 한국공간정보시스템학회:학술대회논문집
• /
• 2004.05a
• /
• pp.176-183
• /
• 2004

Deployable structures are space frames consisting of straight bars that are linked together into bundle and can be deployed large, load bearing structures. Deployable structures are easy to set up, to assemble, to disassemble, to transport and to keep for the use. Also, reusability and flexibility are another important advantages for environmental matter. Since deployable structures have various advantages, they offer viable alternatives for a wide range of potential applications in the temporary construction industry as well as in the aerospace industry. The purpose of this thesis is to decide on geometrical parameters of the design through the numerical analysis and create a final configuration of deployable structures using the geometrical parameters. The Multibody Dynamic Analysis that is dealt with mechanics and aeronautics is used for the method of analysis.

• Journal of The Korean Society of Integrative Medicine
• /
• v.4 no.1
• /
• pp.49-56
• /
• 2016

Purpose : The purpose of this study is to examine the effect of different heel heights on gait deviation and balance. Method : Participants were 16 women majoring in physical therapy in Kyungbuk college, located in Yeong-ju, North Kyungsang Province. Balance and gait patterns were measured by Good Balance and GAIT Rite. Result : Statistically significant differences were found in swing right measured by Gait-rite, and also in Analyze End, Ant-post, Med-Lat, and gait ability score(p < .05) regarding dynamic balance ability. Conclusion : There was no statistically significant difference in gait ability between those who walked barefoot and highheeled. However, balance ability was different "between them". This shows that heel height can lead to decrease in gait ability. Further research should include more participants and use a wide range of heel heights.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.2
• /
• pp.122-128
• /
• 2010

This paper presents vibration control performance of active engine mount system installed with the magneto-rheological(MR) mount and the piezostack mount. The performance is evaluated via hardware-in-the-loop-simulation(HILS) method. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three point mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. As a second step, sliding mode controller(SMC) is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds(wide frequency range) using HILS method and presented in time and frequency domain.