• Proceedings of the Safety Management and Science Conference
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• 2005.05a
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• pp.273-278
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• 2005

Prescribed according to the occupational safety and health low noise measurement method was changed to personal sampling in the method to measure an area noise. Such method had the limit which did not evaluated characteristic of sound of occurrence and the place of origin. This study was performed to establish an engineering remedy of the work-place noise. The subject was a vibration control process of the place of business in Pusan. A simulation program applied for an engineering improvement of the work-place noise. The results were as follows: 1. An noise occurrence level of the work-place before improvement was $88^{\sim}97dB(A)$, We applied an improvement method to be established and were expected to $80^{\sim}119dB(A)$. 2. The level of the noise-distribution to appear in the place of origin of the work-place before improvement was $90^{\sim}93dB(A)$ but, We executed the simulation after applied an engineering remedy and predicted $80^{\sim}85dB(A)$. A result of the simulation blue part was changed mostly into the dark blue color. The results suggest that simulation program establishes an engineering remedy and is useful to the case to apply.

• Journal of the Korea Safety Management & Science
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• v.7 no.2
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• pp.57-64
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• 2005

Prescribed according to the occupational safety and health low noise measurement method was changed to personal sampling in the method to measure an area noise. Such method had the limit which did not evaluated characteristic of sound of occurrence and the place of origin. This study was peformed to establish an engineering remedy of the work-place noise. The subject was a vibration control process of the place of business in Pusan. A simulation program applied for an engineering improvement of the work-place noise. The results were as follows: 1. An noise occurrence level of the work-place before improvement was $88^{\sim}97dB(A)$, We applied an improvement method to be established and were expected to $80^{\sim}l19dB(A)$, 2. The level of the noise-distribution to appear in the place of origin of the work-place before improvement was $90^{\sim}93dB(A)$ but, We executed the simulation after applied an engineering remedy and predicted $80^{\sim}85dB(A)$. A result of the simulation blue part was changed mostly into the dark blue color. The results suggest that simulation program establishes an engineering remedy and is useful to the case to apply.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.620-627
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• 2023

Ship noise is one of the important factors for the living and health of seafarers, and ef orts to reduce ship noise are actively underway. There are two methods of noise reduction: passive noise Control (PNC) and active noise control (ANC). Unlike cars and airplanes, ANC is not widely used for noise reduction on ships. This study aimed to reduce the noise generated in the engine room by using soundproof panels and high-frequency vibration generators, as well as active noise control (ANC). For this purpose, an experimental model was made using an acrylic box, and the noise reduction effect was measured under four conditions. The experimental results are as follows: First, the soundproof panel had a noise reduction effect in all ranges from 55 dB to 85 dB. In the case of using a high-frequency vibration generator, there was no ef ect in the low noise range such as 55 dB(A), but there was a noise reduction effect in the high noise range such as 70.8 dB(A) and 85 dB(A).Second, when the soundproof panel and the high-frequency vibration generator were used simultaneously, the noise reduction ef ect was up to -2.2 dB(A). The results of this experiment were obtained from an experimental model made of acrylic, and they may be different from actual ships made of steel plate. In future studies, we plan to experiment using iron plate (considering the material, thickness, and structure) used in actual ships. We hope that this study will help to improve the living environment and health of seafarers on ships.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2003.04a
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• pp.255-258
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• 2003

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.9
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• pp.841-849
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• 2013

Workers engaged in construction works have been exposed to high levels of noise during their work in tunnels. Noise is one of the major health hazards for employees working in construction sites. The aim of this study is to evaluate the noise levels generating from tunneling equipments such as jumbo drills, backhoes, payloaders, shotcrete machines and service cars. Explosion and turbo fan noises were also monitored. A high precision sound level meter was introduced for measuring LAeq, LAFmax, LAFmin and LCpeak noises in 5 tunneling work sites that were located in Seoul, Kyunggi-do and Kangwon-do areas with NATM and shield methods. The highest noise was recorded by explosion(151.9 dB LCpeak) followed by jumbo drills of higher than 110 dB(A) LAeq. Backhoe normally generated 90~110 dB(A) LAeq while breaking work of rock showed additional around 5~15 dB(A). Noise exposure levels for payloader and shotcrete machine scored more than 90 dB(A) which might be a source of noise-induced hearing loss. Additional research in revealing noise levels from construction equipments operating in tunneling works may enhance the protection of workers who exposed to noise primarily at the sites.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.60-65
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• 2015

This study is to explore floor impact sound and sound insulation of reinforced concrete structure with void-deck slab system which combines polystyrene void foam and T-shaped steel deck plate. A void-deck slab system can effectively reduce the amount of concrete used and hence the mass of a reinforced concrete slab. Also void slab system has dynamically favorable for bending. Three-bay 2-story building was constructed as a mock up test specimen using void-deck slab system and floor impact sound was measured to valuate sound insulation performance. Light weight floor impact and heavy weight floor impact were investigated. Light weight floor impact pressure levels were 32dB, 28dB, and 29db at representative locations which are $1^{st}$ level in the floor impact sound insulation performance grading system. The heavy-weight floor impact pressure levels were 44dB, 45dB, and 43dB at representative locations which are $2^{nd}$ level in the floor impact sound insulation performance grading system. Therefore void-deck slab system can be used in public housing apartment building in terms of not only effectively reduced construction materials but also floor impact sound insulation.

• Molecules and Cells
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• v.42 no.1
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• pp.79-86
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• 2019

Endolysins are bacteriophage-derived enzymes that hydrolyze the peptidoglycan of host bacteria. Endolysins are considered to be promising tools for the control of pathogenic bacteria. LysB4 is an endolysin produced by Bacillus cereus-infecting bacteriophage B4, and consists of an N-terminal enzymatic active domain (EAD) and a C-terminal cell wall binding domain (CBD). LysB4 was discovered for the first time as an L-alanoyl-D-glutamate endopeptidase with the ability to breakdown the peptidoglycan among B. cereus-infecting phages. To understand the activity of LysB4 at the molecular level, this study determined the X-ray crystal structure of the LysB4 EAD, using the full-length LysB4 endolysin. The LysB4 EAD has an active site that is typical of LAS-type enzymes, where $Zn^{2+}$ is tetrahedrally coordinated by three amino acid residues and one water molecule. Mutational studies identified essential residues that are involved in lytic activity. Based on the structural and biochemical information about LysB4, we suggest a ligand-docking model and a putative endopeptidase mechanism for the LysB4 EAD. These suggestions add insight into the molecular mechanism of the endolysin LysB4 in B. cereus-infecting phages.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.62-71
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• 2018

According to own investigation conducted by Korea Gas Safety Corporation Gas Safety Research Institute in 2017, the length of underground pipes in domestic high-pressure gas pipelines is approximately 770km, of which 84% is buried in Ulsan and Yeosu industrial complexes. In particular, 56% of underground pipelines have been in operation for more than 20 years. This suggests urgent management of buried high pressure gas pipelines. PHMSA in US and EGIG in Europe, major causes of accidents in buried gas pipelines are reported as third party damage, external corrosion and loss of pipe wall thickness. Therefore, it is important to evaluate whether the defects affect the remaining life of the pipe when defects occur in the pipe. DNV and ASME have evaluated the residual strength of pipelines through the hydraulic rupture test using pipe specimens with artifact flaws. Once the operating pressure is known through the residual strength of the pipe, the wall thickness at the point at which the pipe ruptures is calculated. If we know the accurate rate of corrosion growth, we can predict the remaining life of pipe. In the study, we carried out experiments with A53 Grade.B and A106 Grade.B, which account for 80% of domestic buried pipes. In order to modify the existing model equation, specimens with a defect depth of 80% to 90% was tested, and a formula expressing the relationship between defect and residual strength was made.

• Journal of Acupuncture Research
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• v.29 no.5
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• pp.97-108
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• 2012

Objectives : To demonstrate the importance of syndrome differentiation in clinical research of herb medication, through the comparative study on efficacy and safety of herb medication according to cold-heat tendency of OA knee patients. Methods : During December 2010 to July 2011, 138 knee OA patients were randomly assigned to WIN-34B 600mg(300mg, b.i.d.), 1,200mg(600mg, b.i.d.) and placebo b.i.d. for 8 weeks. Patient were re-classified into cold-heat tendency group according to cold-heat questionnaires. To investigate efficacy and safety, we assessed the 100mm pain VAS at baseline and 8 weeks later, and we monitored adverse event of patients during treatment period. Results : 1. Efficacy study : In WIN-34B 1,200mg group, VAS mean changes of heat tendency group showed slightly increase than those of cold tendency, but no significant difference within two groups. In heat tendency group, WIN-34B 1,200mg group showed a significant decrease of VAS compared to placebo group. but there were no significant difference in cold tendency group. 2. Safety study; In WIN-34B 600mg group, incidence of adverse events of cold tendency group was higher than those of heat tendency, but not in WIN-34B 1,200mg group. Conclusions : This study suggests that WIN-34B tend to have more efficacy in heat tendency-knee OA patients and WIN-34B is safe drug relatively, regardless of cold-heat tendency. In further clinical research on efficacy and safety of WIN-34B, stratification using syndrome differentiation is required.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.405-406
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• 2007