• Proceedings of the KSME Conference
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• 2002.08a
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• pp.139-142
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• 2002

An experimental model and a conceptual model are investigated in this paper with both shock tube experiment and numerical technique. The shock-vortex interaction generated by this model is visualized with various methods: holographic interferometry, shodowgraphy, and numerical computation. In terms of shock dynamics, there are two meaningful physics in the present problem. They are reflective wave from the slip layer at the vortex edge and transmitted shock penetrating the vortex core. The discussion in this study is mainly focused on the two kinds of waves contributing to the quadrupolar pressure distribution around the vortex center during the interaction.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.226-230
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• 1997

A plasticity theory applicable to powdered metal compaction is briefly summarized and its variational form for the finite element analysis is described. The compaction processes of axisymmetric solid cylinder are simulated. For the analysis of the friction effect of solid cylinder, the investigations were performed for different compact geometries. Highlights of the results for given geometries are reported in terms of transmitted pressure on the lower punch from the upper punch through the compact and maximum density variation within the compacts. General conclusions from these simulation results are : (1) the friction coefficient could be selected from the transmitted force data during the single acting compaction test with the simulated results ; and (2) density variatioins within the compacts are very much dependent of the compact geometry such as the height to diameter ratio and the frictional condition between compact and dies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.792-796
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• 2013

A practical process to optimize engine mounts on construction equipment is presented in this research. Transmitted force from the engine is estimated by using stiffness of the mount rubber which varies with frequency, amplitude and pre-load, and by the engine excitation force that comes from piston mass and gas pressure and so on. The transmitted force is measured through TPA(Transfer Path Analysis) and is then compared with the estimated force. The optimum mount position and stiffness are solved using MATLAB. The result shows the improvement on engine mount vibration.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.988-995
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• 2005

Vibration has been severly increased at the branch pipe of main steam header since the commercial operation of nuclear power plant. Intense broad band disturbance flow at the discontinuous region such as elbow, valve, and header generates the acoustical pulsation which is propagated through the piping system. The pulsation becomes the source of low frequency vibration at piping system. If it coincide with natural frequency of the pipe system, excessive vibration is made. High level vibration due to the pressure pulsation related to high dynamic stress, and ultimately, to failure probability affects fatally the reliability and confidence of plant piping system. This paper discusses vibration effect for the branch pipe system due to acoustical pulsations by broad band disturbance flow at the large main steam header in 700 MW nuclear power plant. The exciting sources and response of the piping system are investigated by using on-site measurements and analytical approaches. It is identified that excessive vibration is caused by acoustical pulsations of 1.3 Hz, 4.4 Hz and 6.6 Hz transmitted from main steam balance header, which are coincided with fundamental natural frequencies of the piping structure. The energy absorbing restraints with additional stiffness and damping factor were installed to reduce excessive vibration.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.1
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• pp.11-23
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• 2010

A sacrificial member with aluminum foam of excellent energy absorption capacity was proposed for the protection of significant structures. Parametric studies of explicit finite element analyses were performed to investigate the pressure mitigation of close-range air-blasts. The scaled distance of the blast had a range of Z=0.48~0.95 and an empirical blast load function was utilized. The analytical parameters of the aluminum foam were density, thickness and the existence of a cover sheet. Analytical results showed that the transmitted pressure can be controlled to have a similar level of yield values of the foam by using a foam with low density and higher thickness. As the blast load increased, the sacrificial member needed to have higher density and thickness. A cover sheet of the foam clearly showed its effect on the wider distribution of blast pressure. It is necessary to determine the design parameters of sacrificial foams considering different energy dissipation capacities according to the scaled distance.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.952-957
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• 2001

The objectives of this investigation were to obtain an excellent spray by cavitation under the low injection pressure. When cavitation occurs in the nozzle hole, the atomization of the liquid jet enhanced considerably. In this experiments, a acrylic nozzle made the gap and installed the bypass in the nozzle hole was used to enhance the atomization of the liquid jet at the low injection pressure. The liquid flow in the nozzle hole was photographed by a transmitted light using a micro flash. The spray angle was measured macroscope images of PMAS and the Sauter mean diameter was measured PDA system. To measure the pressure of the nozzle hole, pressure transducer was used. The results of this study indicated that enhanced atomization of the liquid jet at the low injection pressure was obtained by making the gap and installing the bypass at the single hole nozzle.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.81-84
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• 1998

In this paper, we implemented this failure detecting and monitoring system for high-pressure natrium lamps and ballasts. The hall CTs of the local detecting system measure the current flowing into natrium lamps via ballasts and acertain whether the natrium lamps or ballasts are out of order or not. These test data are transmitted to the main monitoring system. So, we can see the status of the natrium lamps or ballasts promptly.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.100-107
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• 1999

The purpose of the study is to investigate the effect of H$_2$ pressure on partial discharge (PD) activity and aging rate in turbine generator winding insulations. A series of field tests and laboratory tests were peformed to investigate the effect of $H_2$ pressure on PD activity. Field tests were conducted at two unit turbine generators in two conditions, in $H_2$ pressure and in air atmosphere. Obtained results are as follows ; 1) ${\Delta}tan{\delta}$ and maximum partial discharge are reduced with increase of $H_2$ pressure and partial discharge inception voltage. 2) The reduction ratio of ${\Delta}tan{\delta}$ due to $H_2$ pressure is higher than one of PD magnitude. 3) Partial discharge pulses suffer from attenuation and distortion when transmitted along windings, because of the complex L-C network between windings. From the result, partial discharge pulses are subjected to resonance phenomena in a generator winding.

• Journal of ILASS-Korea
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• v.7 no.1
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• pp.36-42
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• 2002

The objective of this investigation was to obtain an excellent spray at the low injection pressure. When cavitation occurred in the nozzle hole the atomization of the liquid jet enhanced considerably. In this experiments, a acrylic nozzle which was installed the gap and installed the bypass in the nozzle hole was used to enhance the atomization of the liquid jet at the few injection pressure. The liquid flow in the nozzle hole was photographed by a transmitted light using a micro flash. The spray angle was measured by macroscope images of PMAS and the Sauter mean diameter was measured by PDA system. The pressure of the notate hole was measured by pressure transducer. It was found that enhanced atomization of the liquid jet at the low injection pressure was obtained by installing the gap and the bypass at the single hole nozzle.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.13 no.1
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• pp.237-252
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• 2000

Pressure sore is an area of ulceration and necrosis of the skin and underlying tissues usually occuring over the bony prominences of the body after prolonged or often repeated pressure. We reviewed and summarized the published articles and treatise on the treatment of pressure sore. The results were as follows : 1. Pressure sore occur due to prolonged or often repeated pressure. So it is better than decubitus ulcer that is called pressure sore. 2. The most common lesions of pressure sore are sacrum, ischial tuberosity, greater trochanter. 3. The cause of pressure sore are change of comprehension. urine, moisture, change of the ability of activity and exercise, shearing force. 4. The elements to influence on wound healing are collagen accumulation velocity, nutrition condition, Vitamine C, copper, iron. oxygen pressure, steroids, cell-toxic drug, radiation. 5. Non-operative treatments are managements of skin such as avoiding consistant pressure, dressing, preventing moisture, understanding patient and protecter, preventing spasm, improvement of systemic nutrition condition. 6. Operative treatements are debridement, suture, skin transplantation, muscle flap and musculaocutaneous flap surgery. Recently V-${\Gammer}$ advancement surgery in use of muscle and musculocutaneous flap is generally maded. 7. Complications of post-operation are wound rupture, infection, disappearance of transmitted skin, necrosis of flaps.