• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.109-115
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• 2004

Polishing process has been applied to get extremely fine surfaces, e.g., mirror surfaces such as optical mirrors, lens, molds and etc. Nowadays not only fine surface quality but also submicron order of dimensional accuracy is required for many applications. To meet the requirements polishing process should be provided with an active control of polishing pressure especially for automation of polishing process. In this paper a study on development of an active polishing pressure control system has been presented. A new type of tool assembly has been developed to facilitate the control. The tool is attached to an axis of a polishing machine with a coil spring and control of the polishing pressure is done by the position control of the axis, which needs no additional actuator. The polishing pressure is successfully measured by the measurement of the spring deformation. Control specifications were quantitatively considered by weighting functions and a controller was designed by using loop-shaping technique based on the no synthesis. Some experiments have been executed on a polishing machine with a PC-NC controller. It is shown that the results were coincident well with the theoretical analyses and satisfied the design specifications.

• Journal of the Korean Solar Energy Society
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• v.24 no.1
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• pp.39-45
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• 2004

The thermal performance of glass evacuated tube solar collectors with finned tubes is numerically modelled with code and investigated to see the effect of toe inner tube diameter and incidence angle. The solar collector consists of a two-layered glass tube and an inner tube. Finned tubes are used as the inner tube of the collector in order to improve the performance of the solar collector. Two strip-type fins are attached on the opposite sides of the inner tube surface. The fin is wide enough to be tightly fatted inside the glass tube. The results show that if the incidence angle is small, the effect of the tube diameters is not significant on the thermal performance and the outlet air temperature. If the incidence angle is large, however, the outlet air temperature and the performance increases as the inner tube diameter increases.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.308-315
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• 2013

Water emulsion technology has the problem of unstable combustion due to the rapid separation of water. To solve the problem, a hybrid mixing device was developed. The device attached on the burner was tested. As a result, the fuel consumption reduced to 12% in the similar condition of exhaust emissions and flame temperature, and 45.5%, 98.5% and 97.2% of NOx, CO, and smoke were reduced at the same inlet air and fuel flow rate.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.2
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• pp.30-38
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• 2003

This paper proposed PID controller for torch slider and PD controller for motor right wheel. to control the motion of two-wheeled welding mobile robot with seam tracking sensor touched on welding line. The motion control is realized in the view of keeping constant welding velocity and precise seam tracking even though the target welding line is on straight line or curved line. The position and direction of the body of the mottle robot are controlled by using signal errors between seam tracking sensor and body positioning sensor attached on the end of torch slider and body side of the mobile robot, respectively. In turning motion, the body and the torch slider are controlled by using the kinematic model related with two motions of body turning and torch sliding. The straight locomotion is controlled according to eleven control patterns obtained from displacements between two sensors of the seam tracking sensor and the body positioning sensor. The effectiveness is proven through the experimental results fur lattice type welding line. Through the experimental results, we can see that the position value of the electrode end point and the welding velocity are controlled almost constantly both in straight and turning locomotion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.446-452
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• 2002

This paper Presents a 3-D design and a Vibration control of a new walking R.G.O.(Robotic Gait Orthosis) and would like to develop a simulation by this walking system. The vibration control and evaluation of the new knee joint mechanism on the biped walking R.G.O.(Robotic Gait Orthosis) was a very unique system and was to obtain by the 3-axis accelerometer with a low frequency vibration for the paraplegia It will be expect that the spinal cord injury patients are able to recover effectively by a biped walking R.G.O.. The new knee joint system of both legs were adopted with a good kinematic characteristics. It was designed attached a DC-srevo motor and controller, with a human wear type. It was able to accomodate itself to a environments of S.C.I. Patients. It will be expect that the spinal cord injury patients are able to recover effectively by a new walking R.G.O. system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.289-294
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• 2002

In this study, performance, flow characteristics and noise of a cross-flow-fan system, used in indoor unit of the split-type air conditioner, were predicted by computational simulation. Triangular elements were used to mesh the calculation domain and quadrilateral elements were attached to the blade surfaces and walls to enhance the simulation quality. The unsteady incompressible Wavier-Stokes equations were solved using a sliding mesh technique on the interface between rotating fan region and the outside. Two stripes of velocity stream inside the cross-flow-fan were shown - the one was due to the eccentric vortex and the other was due to the normal entrance flow. As the flow rate increased, the center of the eccentric vortex moved toward the inner blade tip and rear-guide, and the exiting flow still had velocity variation along the stabilizer, which can increase the noise level. The acoustic pressure was calculated by using Lowson's equation. From the calculated acoustic pressure, it was found that the trailing edge is a dominant of acoustic generation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.7
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• pp.667-672
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• 2009

This paper is concerned with the development of linear magnetic actuator for active vibration control. The newly developed linear magnetic actuator consists of permanent magnets and copper coils. On the contrary to the voice-coil type actuator, the linear magnetic actuator utilizes magnetic flux to generate the shaft movement. In this study, experiments on the prototype linear magnetic actuator were carried out to investigate its dynamic characteristics. Block and inertia forces generated by the actuator were measured. The experimental results show that the actuator can be used as both actuator and active tuned-mass damper. The linear magnetic actuator was attached to a cantilever as the active-tuned mass damper and active vibration control experiment was carried out. The experimental results show that the newly developed linear magnetic actuator can be effectively used for the active vibration control of structures.

• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.61-72
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• 2004

This study investigated the inelastic lateral-torsional buckling of simply supported beams under a central concentrated load and a uniformly distributed load. A line-type finite element, method was incorporated with the "so-called" simplified and polynomial patterns of residual stresses. The effect of the load height was also considered in this study. The polynomial residual stresses assumed in this study was a quartic distribution in the flange and a parabolic distribution in the web. The inelastic lateral-torsional buckling of beam was analyzed with four different I-sections manufactured in Korea. Results obtained in this study were compared with KSDM(design method in the 1995 Korean Steel Designers' Manual). The design method in KSDM was found to be generally conservative with and without a sub-beam attached to the main beam, which acted as an intermediate restraint.

• KSTLE International Journal
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• v.6 no.1
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• pp.28-32
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• 2005

The electrorheoloRical (ER) fluids are composed of a colloidal dispersion of polarizable particles in insulating oil, and it's the rheological property changes by the applied electric field. These changed are reversible and occur fast within a fewmilliseconds. The ER properties of the ER fluid such as increment of viscosity and yield stress come from the particle chain structure induced by electric fleld. When formulating the ER fluid for a speciflc application, some requirement must besatisfled, which are high yield stress under electric field, rapid response, and dispersion stability. While this characteristic makes valuable ER fluids in valious industrial applications, their lung term and quiescent application has been limited because ofproblems with particle sedimentation. In an effort to overcome sedimentation problem of ER fluids, the anhydrous ER materials of monodispersed hollow polyaniline (PANI) and adipate derivative respectively with submicron-sized suspension providing wide operating temperature range and other advantage were synthesized in a four-step procedure. The ER fluidswere characterized by FT-lR, TGA, DLS, SEM, and TEM. Stability of the suspensions was examined by an UV spectroscopy.The rheological and electrical properties of the suspension were investigated Couette-type rheometer with a high voltagegenerator, current density, and conductivity. And the behavior of ER suspensions was observed by a video camera attached toan optical microscope under 3kV/mm. The suspensions showed good ER properties, durability, and particle dispersion.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.6 s.154
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• pp.916-927
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• 2006

The purpose of this study was to identify psychological and behavioral outcomes of commitment to apparel brand community by test structural equation model. Subjects of 317 members for 9 selected apparel communities responded the questionnaire in the home-page or in the attached file. The results were as follows: 1) The suggested structural equation mode was accepted by data from apparel brand communities with hish brand strength(${\chi}^2=97.42$, d.f.=89, p=0.25, GFI=0.92, AGFI=0.88, RMR=0.05, NFI=0.94). However, this model wasn't accepted by data kom apparel brand communities with low brand strength. 2) Three types of commitment to brand community(emotional, continuous and normative commitments) influenced brand identification positively and brand identification positively influenced three types of behavioral outcomes(favorable word-of-mouth, co-production and repurchase of brand). Therefore, managements need to develop marketing programs to promote each type of commitment to their's own brand community.