• Journal of the Korean Society of Safety
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• v.21 no.5 s.77
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• pp.12-16
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• 2006

This paper deals with the noise evaluation and noise reduction of a reciprocating air-compressor. The reciprocating air-compressor is widely used in the small and medium sized industrial firms, many employees exposed and irritated by their noise in the workplace. Thus, appropriate noise control actions should be taken to prevent hearing loss due to the its noise exposure. Lead-wrapping techniques are employed to identify the contribution of principal noise sources which are generally known to be motor, belts, suction valves, discharge valves, moving parts, and flow-induced noise caused by edges or discontinuities along the flow path including expansions, contractions, junctions and bends. As a result, the main noise sources of the air-compressor are categorized by the suction and discharge noise, valve noise, and compressed air tank noise. Based on the investigations, mufflers are designed to reduce both the suction and discharge noise and the compressed-air tank noise. Instead of the conventional valve plate, polyethylene resin is used the reduction of valve impact noise. In addition, attempts are made to reduce the valve noise propagation to the cylinder head and the compressor tank by using the insulation casings. As a result of the countermeasure plans, a noise reduction up to 10dB(A) could be achieved for the air-compressor.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.20-26
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• 2011

This paper is to investigate noise source for reciprocating type air compressors. The reciprocating type air compressors are widely used in the small and medium sized enterprise and many employees are affected and irritated by their noise during working. The investigation and analysis of the noise source were made according to the ISO 1680/1 and MIL-STD 7410-1 and noise evaluation of each part of compressors was made. Noise emitted from the intake and exhaust valve and the air receiver tank were dominant compared with those from other parts of compressor. Noise from the motor and the revolution of crank mechanism was negligible relatively with the noise sources as mentioned above.

• Journal of Korean Neurosurgical Society
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• v.49 no.1
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• pp.49-52
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• 2011

Traumatic intracranial aneurysms are rare, comprising 1% or less of all cerebral aneurysms. The majority of these aneurysms arise at the skull base or in the distal anterior and middle cerebral arteries or their branches following direct mural injury or acceleration-induced shearing force. We present a 50-year-old patient in whom subarachnoid hemorrhage (SAH) was developed as a result of traumatic aneurysm rupture after a closed craniofacial injury. Through careful evaluation of the three-dimensional computed tomography and conventional angiographies, the possible mechanism of the traumatic internal carotid artery trunk aneurysm is correlated with a hit injury by the bony protuberances on the anterior and posterior clinoid processes. This traumatic aneurysm was successfully obliterated with clipping and wrapping technique. The possibility of a traumatic intracranial aneurysm should be considered when patient with SAH demonstrates bony protuberances on the clinoid process as a traumatic aneurysm may result from mechanical injury by the sharp bony edges.

• International Journal of Safety
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• v.3 no.1
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• pp.6-9
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• 2004

This paper deals with the noise evaluation technique of a reciprocating air-compressor and its noise reduction. The reciprocating air-compressors are widely used in the small, medium sized industrial firms, and lots of their employees are affected and irritated by their noise in the workplace. Thus, noise control actions should be taken appropriately by considering the hearing loss due to the occupational noise exposure. Lead-wrapping techniques are employed to identify the contribution of principal noise sources which are generally known as motor, belts, suction/discharge valves, moving pistons, and flow-induced noise caused by edges or discontinuities along the flow path e.g. expansions, contractions, junctions and bends etc .. As a result, main noise sources of the air-compressor can be categorized by the suction/discharge noise, valve noise, and compressed-air tank noise. Based on the investigations, mufflers are designed to reduce both the suction/discharge noise and the compressed-air tank noise. Instead of the conventional valve plate, polyethylene resin is used as a new one for the reduction of valve impact noise. In addition, attempts are made to reduce the valve noise propagation to the cylinder head and the compressor tank by using the insulation casings. As a result of the countermeasure plans, it can be achieved that the noise reduction of the air-compress is up to 10dB.