Noise-Induced Hearing Loss in the Police Force

Kyaw N. Win,Nayake B.P. Balalla,Min Z. Lwin,Alice Lai 한국산업안전보건공단 산업안전보건연구원 2015 Safety and health at work Vol.6 No.2

Background: Noise-induced hearing loss (NIHL) is a major preventable occupational health problem with 250 million people worldwide known to have disabling impairment of moderate to greater severity. The aims of the study are to estimate the prevalence of NIHL in the police force; and study its association with age, sex, duration of service (years), smoking and alcohol habits, use of hearing protective devices, as well as preexisting chronic diseases. Methods: A cross-sectional study was conducted on 543 police personnel who had undergone periodic medical examination over a 12-month period. The diagnostic criteria for NIHL were (1) history of occupational noise exposure, (2) bilateral hearing loss, (3) hearing loss of ? 25 dBA at 4,000 Hz in two consecutive audiograms, and (4) no significant medical history affecting hearing. Severity of NIHL was based on the World Health Organization grading. Results: Males (74.8%) made up the majority of the police force. The mean age for police personnel was 35.55 ? 9.57 years, and the mean duration of service was 14.75 ? 9.39 years. Compliance with the usage of hearing protective devices was seen in 64.4%. The prevalence of NIHL in this study population was 34.2%, with a higher prevalence in males (37.7%) than in females (23.9%). The study also showed strong associations between NIHL and male sex (odds ratio, 1.9; P < 0.05), and hypertension (odds ratio, 3.3; P < 0.001). Overall, 93% were found to have mild NIHL, 3.5% had moderate NIHL, and 3.5% had severe NIHL. No police personnel were found to have profound hearing loss. Conclusion: The prevalence of NIHL in this study is high compared to other similar studies among police personnel. This study shows that increasing age, male, presence of hypertension, diabetes, and longer duration of service are significant associated factors for NIHL. Preventative strategies include health surveillance, implementation of a hearing conservation program, and legislation.

Noise-Induced Hearing Loss in the Police Force

Win, Kyaw N.,Balalla, Nayake B.P.,Lwin, Min Z.,Lai, Alice Occupational Safety and Health Research Institute 2015 Safety and health at work Vol.6 No.2

Background: Noise-induced hearing loss (NIHL) is a major preventable occupational health problem with 250 million people worldwide known to have disabling impairment of moderate to greater severity. The aims of the study are to estimate the prevalence of NIHL in the police force; and study its association with age, sex, duration of service (years), smoking and alcohol habits, use of hearing protective devices, as well as preexisting chronic diseases. Methods: A cross-sectional study was conducted on 543 police personnel who had undergone periodic medical examination over a 12-month period. The diagnostic criteria for NIHL were (1) history of occupational noise exposure, (2) bilateral hearing loss, (3) hearing loss of ${\geq}25dBA$ at 4,000 Hz in two consecutive audiograms, and (4) no significant medical history affecting hearing. Severity of NIHL was based on the World Health Organization grading. Results: Males (74.8%) made up the majority of the police force. The mean age for police personnel was $35.55{\pm}9.57years$, and the mean duration of service was $14.75{\pm}9.39years$. Compliance with the usage of hearing protective devices was seen in 64.4%. The prevalence of NIHL in this study population was 34.2%, with a higher prevalence in males (37.7%) than in females (23.9%). The study also showed strong associations between NIHL and male sex (odds ratio, 1.9; P < 0.05), and hypertension (odds ratio, 3.3; P < 0.001). Overall, 93% were found to have mild NIHL, 3.5% had moderate NIHL, and 3.5% had severe NIHL. No police personnel were found to have profound hearing loss. Conclusion: The prevalence of NIHL in this study is high compared to other similar studies among police personnel. This study shows that increasing age, male, presence of hypertension, diabetes, and longer duration of service are significant associated factors for NIHL. Preventative strategies include health surveillance, implementation of a hearing conservation program, and legislation.

New Method of PD measuring on MV XLPE Cable by Using Prototype Patch Antenna

키아우소 륀(K-S Lwin),신동훈(D-H Shin),임광진(K-J Lim),공태식(T-S Kong),김희동(H-D Kim),박노준(N-J Park),박대희(D-H Park) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.4

We studied the partial discharge detecting by sensing electromagnetic wave emitted from the partial discharge source in the MV XLPE cable with the new type of patch antenna sensor. In this study, we design new kind of patch antenna and make many experiments compare with the existing HFCT sensor on MV XLPE cable in the laboratory. According to our experimental results our new sensor can detect pure PD and wider bandwidth 20㎒ to 70㎒ than HFCT and can easily localized manually on the cable.

PD Diagnosis on High Voltage Rotating by Using New Prototype Patch Antenna Sensor

키아우소륀(K-S Lwin),신동훈(D-H Shin),임광진(K-J Lim),공태식(T-S Kong),김희동(H-D Kim),박노준(N-J Park),박대희(D-H Park) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.4

We studied the partial discharge detecting by sensing electromagnetic wave emitted from the partial discharge source in the HV Rotating Machine with the new prototype patch antenna sensor. In this study, we design new type of patch antenna based on microstrip technology and make many experiments of offline testing compare with the existing HFCT and EM probe on stator winding of HV generator in the laboratory. This paper will mention comparison of experimental results based on the three kinds of sensors.

Sintering properties and low-temperature degradation behaviour of Y-TZP ceramics

C.H. Ting,S. Ramesh,N. Lwin,U. Sutharsini 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.12

Y-TZP ceramics has outstanding mechanical properties and has been used for many engineering applications. However, amajor drawback of this ceramic is the undesirable ageing-induced tetragonal to monoclinic phase transformation resulting inproperties deterioration when exposed to steam environment. In the present work, the effect of sintering temperatures (1200to 1500 oC) on mechanical properties, microstructure and low temperature ageing behaviour of the sintered Y-TZP sampleswere investigated. The sintered bodies were characterized to determine the bulk density, Young’s modulus, Vickers hardnessand fracture toughness. The sintered samples were exposed to superheated steam at 180 oC/10 bar vapor pressure and theextent of monoclinic phase development were measured at selected intervals. It was found that the relative density and Young’smodulus of the sintered samples increased with sintering temperature and attained a maximum value of 99% and 211 MPa,respectively at 1400 oC. On the other hand, maximum Vickers hardness and fracture toughness of 14.4 GPa and 5.07 MPam1/2respectively, was measured at 1350 oC. X-ray diffraction studies indicated that after 24 h of ageing, no traces of monoclinicphase was found in the Y-TZP having an average grain size of below 0.3 µm. The study found that sintering at 1350-1400 oCwas optimum to produce sintered bodies having good ageing resistant without sacrificing the mechanical properties.

Effect of manganese oxide on the densification and properties of ceria-doped scandia stabilized zirconia

C.K. Ng,S. Ramesh,C.Y. Tan,C.Y. Ching,N. Lwin,A. Muchtar 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.5

In the present work, the effect of manganese oxide (MnO2) additions (0, 0.5, 1 and 5 wt%) on the properties of ceria-dopedscandia stabilized zirconia (10Sc1CeSZ) was investigated over the temperature range of 1400 oC to 1550 oC. The results showedthat the addition up to 1 wt% had negligible effect on the mechanical properties of the ceramic. The samples containing upto 1 wt% MnO2 attained above 97.5% relative density, Vickers hardness of 13-14 GPa and fracture toughness of about3 MPam1/2. In addition, it was revealed that the 0.5 wt% MnO2 addition was beneficial in suppressing the cubic zirconia graingrowth i.e. the highest average grain size was measured at 4.9 µm when sintered at 1550 oC as compared to 9.9 µm measuredfor the undoped zirconia when sintered at the same temperature. On the other hand, the addition of 5 wt% MnO2 was foundto be detrimental to the densification and properties of the zirconia, particularly when sintered at higher temperatures. Thiswas attributed to the accelerated grain growth of the doped samples, i.e. the grain size increased by 2 fold, to 18.6 µm whensintered at 1550 oC.