• Electric Engineers Magazine
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• s.372
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• pp.36-37
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• 2013

2013. 7. 12(금) 14시 경, 부산시 사상구에 소재한 상가 및 공장 철거공사 현장에서 외국인(러시아) 근로자(24세, 남)가 해머(Rotary Hammer)를 이용하여 철골기둥 하부의 콘크리트를 파쇄하는 작업 중 감전 사망한 재해임.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.131.2-131
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• 2001

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.992-998
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• 2008

The purpose of this study to improve quality control and prevent repeated error.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.298-299
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• 2005

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.159-166
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• 1999

One of the most general methods that can evaluate the rippability is the seismic exploration. However, most field engineers have hardly used the seismic exploration. Instead of using the seismic exploration, they have usually used rock hammer and naked eyes to confirm the degree of rippability for soil, ripping rock and blasting rock. Therefore, to excavate the ground rationally, it is required to establish a quantitative criterion that can be used for distinguishing rippability. In this study, we find out the characteristics of rock strength through laboratory and field tests. The weathering condition of rock exposed to air due to excavation of soil layer and the variation of rock strength caused by weathering were investigated. A relationship between rock strength values that are obtained from uniaxial compression test, slaking durability test, point load test, schmidt hammer test and absorption ratio test is analyzed. The relationship is expressed in a form of equation by which we can evaluate the rock strengths obtained from simple laboratory and field tests. To evaluate rippability in a reasonable manner, a quantitative approach is proposed and a check list of rippability is developed based on the proposed methodology. It is recommended to modify the proposed method for evaluation of rippability in the field.

• Journal of the Korean housing association
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• v.20 no.1
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• pp.83-90
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• 2009

The present study is a preliminary research improving the dwelling quality of apartment house as a kind of multi-family housing. The purpose of the study is to find out the actual state on characteristics of indoor noise including residents' living in apartment units. The method was field survey consisted of field measurements on equivalent noise level, observation on noise type, and interview on residents' responses. Field survey were carried out in 20 occupied apartment units from January to March 2007. The results are as follows. 1) Averages of indoor noise levels including residents' living noise were measured as $43.9{\sim}62.2\;dB(A)_{Leq5min}$, the average of each house except one was higher than the permissible level, 45 dB(A). 2) The noise types observed were mostly residents' living noise and classified into 'water hammer', 'living equipment noise', 'noise by family', 'hood noise', 'kitchen noise' in own unit, 'walking and talking noise in stairs and corridors', 'noise by neighborhood house', 'noise by the upper story' in building, and outdoor noise. 3) The residents showed slightly non-positive responses at 'noise by the upper story', 'noise by neighborhood house', 'water hammer', and 'noise by family'. Therefore, it is required to plan for preventing deterioration of the dwelling quality by residents' living noise in own unit as well as by neighborhood houses.

• Korean journal of applied entomology
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• v.33 no.2
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• pp.107-113
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• 1994

This study is canled for tanonomical investigation of Olibatid mites on landscape plan& As the results, thirteen species of Oribatid mites on the plants are described for the first time from Korea. but the harmfulness caused by the mites is not yet proved The mites are Tuberemoeus singularis Sellnick, Zygoribatulo elongoto Hammer. Scahperemaeus yamashitoi Aoki, Oribatula sakamori Aoki, Camis~a segnis (Hemann), Scheloribates Jatipes (Koch), Oppiella nova (Oudemans), Lauroppia neerlondica (Oudemans), Hemileius sp.. Oripodo sp., Twncopes sp.. and Tectocehpeus sp. etc. Among them, Tuberemaeus singularis and Zygoribotulo elongatn are recorded from Korea for the first time And three lalvae are found out at intestine of one specimen of Tuberemoeus singularrs Sellnick which is collected on Cryptomerio japonica D, in Chep (Seoguipo). Therefore, thls mite seems to be ovoviviparous.

• Journal of Sensor Science and Technology
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• v.28 no.6
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• pp.371-376
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• 2019

We have developed an acoustic resonance inspection system to inspect the welding defects in the mechanical parts fabricated using friction stir welding method. The inspection system was consisted of a DAQ board, a microphone sensor, an impact hammer, and controlled by a PC software. The system was developed to collect and analyze the sound signal generated by hitting the sample with an impact hammer to determine whether it is defective. In this study, 100% welded good samples were compared with 95%, 90%, and 85% welded samples, respectively. The variation of the completeness in welding did not affect the visual appearance in the samples. As a result of analyzing the natural frequencies of the good samples, the five natural frequency peaks were identified. In the case of the defective samples, the frequency change was observed. The welding failure detection time was fast enough to be only 0.7 seconds. Employing our welding defect inspection system to the actual industrial field will maximize the efficiency of quality inspection and thus improve the productivity.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.47-50
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• 2003

Grain size of the $\alpha$ phase is computed during isothermal forging of the TC6 aerofoil blade, by combining FE with the Yada's model of grain size. The present results illustrate the grain size and distribution of the $\alpha$ phase during isothermal forging of the TC6 aerofoil blade' in detail. The computed results show that height reduction, deformation temperature, hammer velocity and friction have significant effect on distribution of the equivalent strain, and that height reduction, deformation temperature and hammer velocity have more significant effect on grain size of the $\alpha$ phase than friction between billet and die.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.313-317
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• 2009

The orifice in the propellent feeding pipe line of a Liquid Rocket Engine(LRE) is used to balance the pressure of the pipe line. When a LRE starts up, pressure at the upstream of the orifice rapidly increases. In this case, pressure waves occuring by resistance of the orifice may induce low frequency instability in the pipe line. For this reason the study of dynamic characteristics of orifices is needed to prevent the instability. A pump is used to build up the pressure, and the pressure is measured upstream and downstream of the orifice when the orifice diameter is changed. With the increase of orifice diameter, water hammer decreases, but the effect of resistance downstream is increases.