• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.358-361
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• 2004

This paper describes the development process of high stiffness body for ride and handling performance. High stiffness and light weight vehicle is a major target in the refinement of passenger cars to meet customers' contradictable requirements between ride and handling performance and fuel economy. This paper describes the analysis approach process for high stiffness body through the data level of body stiffness. According to the frequency band, we can suggest the design guideline about Is cornering static stiffness, torsional and lateral stiffness, body attachment stiffness. The ride and handling characteristic of a vehicle is significantly affected by vibration transferred to the body through the chassis mounting points from front and rear suspension. It is known that body attachment stiffness is an important factor of ride and handling performance improvement. And high stiffness helps to improve the flexibility of bushing rate tuning between Handling and road noise. It makes it possible to design the good handling performance vehicle at initial design stage and save vehicles to be used in tests by using mother car at initial design stage. These improvements can lead to shortening the time needed to develop better vehicles.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.10
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• pp.667-676
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• 2015

Working displacement variation by elastic deformation of active Gurney flap which was operated on high frequency was observed. Flap-wise natural frequency was lower than mode analysis result and hinge boundary condition was identified to be the cause through the simple modal test. Design modification for increasing natural frequency was conducted for minimizing the elastic deformation at maximum 35 Hz operating condition which was design requirement condition. Brass bushing was applied instead of rotating bearing for gap minimization and Gurney flap design modification was conducted to increase of the flap-wise natural frequency. Design modification effect was validated by natural frequency comparison with mode analysis result and modal test result of design modification model.

• Korean Journal of Metals and Materials
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• v.49 no.9
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• pp.708-714
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• 2011

The premature failure of a servovalve used for six months in a thermal power plant has been analyzed. The servovalve was made of stainless steel, containing 16Cr-0.44Mo, along with other elements. An overload of oil-supply pumping and an abnormal increase in the oil flux were observed during operation. A study revealed that erosion and corrosion could be the main causes of the failure. The visual examination of the servovalve did not show any appreciable damage. However, corrosion and erosion of the servovalve were observed using scanning electron microscopy (SEM). Upon examination of the servovalve, the corrosion was found to have occurred throughout the bushing and spool; however, erosion occurred at only the edge-side. In addition, the condition of the electrohydraulic control system (EHC) oil was investigated with respect to its satisfaction of the management standard.

• Journal of the Korea Convergence Society
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• v.12 no.1
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• pp.205-210
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• 2021

In this study, I studied how to generate input values to achieve the same value as the target value. The general procedures are explained to regenerate the excitation input, which is made by using the frequency response function between input-output. In this study, a mount model connected by a bushing was used as a numerical model. The response value for the excitation input was compared with the target value. The excitation input was corrected to obtain the same response as the target value. Through the iterative process, the reconstructed input value was obtained to have the same response as the test.

• Composites Research
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• v.19 no.6
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• pp.32-37
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• 2006

This paper summarizes the processing inorganic continuous fibers from Korean minerals. Continuous filament fibers have been produced from two rocks, basalt and quartz diorite porphyry(QDP), by melting method. The essence of the method is that the vitrified materials was placed into the bushing, platinum/rhodium alloy crucible with a nozzle, and heated electrically to a temperature which allowed fiber spinning. Vitrified basalt without additive was suitable for producing continuous filament fiber. However doping quartz diorite porphyry with boric oxide yielded a material which could be pulled continuously.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.2
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• pp.1-8
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• 2008

Friction pendulum system is developed to prevent the damage of transformer, which is the most important among the electric power facilities, due to the earthquake and its seismic capacity is verified through the shaking table test. The applicability of friction pendulum system is confirmed as test results of compressive capacity test and friction test. Especially, as a result of shaking table test with a large scale transformer model, friction pendulum system gives to the reduction of maximum response acceleration by 30% at anchorage of transformer and 59% at the top of porcelain bushing comparing with the existing anchorage type. In addition to the reduction of maximum response acceleration, natural frequency of transformer is shifted to long period due to the friction pendulum system. In case that friction pendulum system is applied to the transformer, the damage of transformer can be prevented effectively under the earthquake.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.112-118
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• 1990

Catastrophic fracture cannot be avoided after cracks(initiated from pre-existing defects) propagate rapidly with speeds comparable to a sound wave velocity of the materials. Preventing catastropic failure, crack arrest fracture toughness defined from dynamic(or kinetic) fracture mechanics point of view has been introduced in determining accurate and/or proper crack arrest fracture toughness of a material. For the past decades, many studies have been carried out to render proper theoretical and experimental backgrounds on the use of the static plain strain crack arrest fracture toughness, $K_{1a}$ (which seems to be a material property). $K_{1a}$ has been used to predict the performance of thick walled structures and has been considered as a measure of the ability of a material to stop a fast running crack. Determination of such a material property is of prime importance to the nuclear reactor pressure vessel and bridge materials industries. However, standards procedures for measuring toughness associated with fast running cracks are yet to exist. This study intends to give insight on the determination of the crack arrest fracture toughness of materials such as polymethylmethacrylate(PMMA), SM45C-steel, and A1 7075-T6. The effects of crack jump lengths and fast crack initiation stress intensity factor on the determination of $K_{1a}$ have been experimentally observed.erved.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.9-16
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• 2007

Since the liquid phase LPG injection(LPLI) system has an advantage of higher power and lower emission characteristics than the mixer type fuel supply system, many studies and applications have been conducted. However, the heat extraction, due to the evaporation of liquid fuel, causes not only a dropping of LPG fuel but also icing phenomenon that is a frost of moisture in the air around the nozzle tip. Because both lead to a difficulty in the control of accurate air fuel ratio, it can result in poor engine performance and a large amount of HC emissions. The experimental investigation was carried out on the bench test rig in this study. It was found that n-butane, that has a relatively high boiling point($-0.5^{\circ}C$), was a main species of droplet composition and also found that the droplet problem was improved by the use of a large inner to outer bore ratio nozzle whose surface roughness is smooth. The icing phenomena were decreased when the an engine head temperature was increased, although a large amount of icing deposit was still observed in the case of $87^{\circ}C$. Also, it was observed that the icing phenomenon is improved by using anti-icing bushing.

• Clinics in Shoulder and Elbow
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• v.23 no.1
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• pp.20-26
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• 2020

Background: High complication rate after open reduction and internal fixation can lead to use of primary total elbow replacement (TER) in treatment of complex distal humerus fractures in elderly patients. The purpose of this study was to investigate the short-term outcomes and complications after primary TER in patients with complex distal humerus fracture. Methods: Nine patients with acute complex distal humerus fracture were treated by primary TER using the semiconstrained Coonrad-Morrey prosthesis. The mean age of patients was 72.7 years (range, 63-85 years). Clinical and radiographic outcomes were evaluated over a mean follow-up of 29.0 months (range, 12-65 months) using visual analog scale (VAS) score for pain; Mayo elbow performance score (MEPS); Quick Disabilities of the Arm, Shoulder, and Hand (Quick-DASH) score; and serial plain radiographs. Complications were also evaluated. Results: At the final follow-up, mean VAS, MEPS, and Quick-DASH scores were 1.2, 80.5, and 20, respectively. The mean range of motion was 127.7° of flexion, 13.8° of extension, 73.3° of pronation, and 74.4° of supination. There was no evidence of bushing wear or high-grade implant loosening on serial plain radiographs. Three complications (33.3%) comprising two periprosthetic fractures and one ulnar neuropathy were observed. Conclusions: Primary TER for treatment of complex distal humerus fractures in elderly patients yielded satisfactory short-term outcomes. However, surgeons should consider the high complication rate after primary TER.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.122-124
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• 2005

Underground distribution system is a trend due to the successive development of metropolitan area and satellite cities and the environment of the commercial and residential areas. The high quality of electricity, which is related with the minimal outage duration time due to the maintenance work for the underground distribution line, is mandatory. Hence, the construction method and tools for the outage-free maintenance construction have been required for underground distribution system. So far, all the efforts for outage-free maintenance for the underground distribution have been limited only to the survey for foreign countries situation and the theoretical provision; thus, It is required to develop the various construction method and the application tools. Differently from the aerial line, the construction of the underground cable is complicated and the insulation distance between conductor and shield should be maintained in loadmaking/breaking operation, though the apparatus connected with cable is a deadfront type. Also since the apparatus is installed above ground, by-pass of faulted area at busy area needs a variety of high technologies. Therefore, in this these, the authors introduce the development status of the loadbreak connectors, connection facilities, outage-free maintenance system for secondary side, a secondary auxiliary bushing and additional tools so that there can be more progress on this field.