• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.35-40
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• 2012

In this study, the ultraviolet (UV) intensity of polymer insulator was measured using the Anti-Reflective (AR) coating lens on the occurrence of corona discharge. The UV intensity was compared before and after the AR coating. Under the 200-260[nm] of UV lens, the reflection rate before AR coating was 7.5~5.5[%] with 85-89[%] of transmission rate. After AR coating, however, the reflection rate decreased to 1.3~1.22[%] with improved transmission (97.4~97.6[%]). Then, the UV intensity by distance was measured in the polymer insulator. According to the measurement, the UV intensity increased 6.5 times at 37.5[%] of Vm/Vbd with 5[m] of distance. As distance increased, the growth rate declined. As high voltage increased, in addition, AR coating was less effective due to the count error caused by the UV sensor pulse signal overlap. Therefore, it appears that it would be more effective to detect corona discharge with 5[m] or less of distance at diagnosis of power facilities by AR coating and UV sensor sensitivity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.254-257
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• 2005

Locations and emission characteristics of noise source of rapier loom are important factors greatly. So, noise characteristics of rapier loom were investigated by the noise source identification as a part of experimental methods in this study. To identify the noise sources of the rapier loom sound intensity was measured under machine operation. In addition, frequency spectra of the sound at operator position was measured along with sound intensity to help identify the noise characteristics of the rapier loom. The results indicate that the sound power level occurs along the rapier loom.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.43-46
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• 2000

Optical triangulation displacement sensors(0TDSs) are widely used for their simple struchlre, high resolution, and long operating range. However, there are several factors that must be taken into account in order to obtain high accuracy and reliability Measurement errors from inclinations a？ an object surface, prohe signal fluctuations generated by speckle effects. power vanation of a light source, electronic noises, and so on. Previous models of OTDSs can not show reasonable behavior as change of surface inclination and shape of light intensity distribution on the detector. In this paper, we propose a new and reasonable modeling for diffise-type OTDSs based on a geometrical optics. To verify propriety of new modeling, we take basic experiments. Shape of light intensity distribution is asymmetric in both simulation result and experimental result. Both simulation result and experimental result show same tendency of light intensity distribution movement as changing surface inclination

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.10a
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• pp.407-411
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• 2004

Ohmic heating occurs when an electric current is passes through food, resulting in a temperature rise in the product due to the conversion of the electric energy into heat. The time spent in the thawing is critical for product sterility and quality. The objective of this study is to conduct numerical modelling between the effect of ohmic thawing intensity on PTT(phase transition time) at constant concentration and the effect of matrix concentrations on PTT at constant voltage condition. the stronger ohmic thawing intensity resulted in decreasing the PTT. High ohmic intensity causes short PTT. And the higher gelatin concentration, the faster increment of PTT. A numerical modeling was executed to predict the PTT influenced by the power intensity using exponential regression and the PTT influenced by gelatin concentration using logarithmic regression. Therefore, from this numerical model of gelatin matrix, it is possible to estimate exact values extensively.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.1
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• pp.63-71
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• 1987

The measuring of acoustic intensity has been investigated by many researchers and practicians during the last several decades. But due to the lack of measurement accuracy, they have had no practical use. In recent years, the two microphone acoustic intensity method has been developed by the advancement of FFT analysis technique and the digital data processing equipment. This new method of using two microphones gives informations on the noise source survey and the acoustic power of sound radiation source without the anechoic room. In this paper, theoretical formulae for the two microphone acoustic intensity method and the sound transmission loss are checked. The obtained results for the acoustical enclosure of gas heat pump were compared with the classical field incidence mass law. The surface vibration modes for a panel of enclosure were also estimated.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1402-1406
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• 2004

As a method of confirming light flickering, we tried to confirm the flicker index measured by Flickermeter and the application possibility by using digital intensity of illumination meter. Also, after simulating the quality deterioration of electric power and generating a various voltage change, we studied on the function between the flicker index measured by Flickermeter and the flicker index for the intensity of illumination by using digital intensity of illumination meter.

• Journal of Mechanical Science and Technology
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• v.17 no.8
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• pp.1120-1132
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• 2003

A problem of a circular elastic inhomogeneity interacting with a crack under uniform loadings (mechanical tension and heat flux at infinity) is solved. The singular. integral equations for edge and temperature dislocation distribution functions are constructed and solved numeric-ally, to obtain the stress intensity factors. The effects of the material property ratio on the stress intensity factor (SIF) are investigated. The computed SIFs are used to predict the kink angle of the crack when the crack grows.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.8
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• pp.777-783
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• 2012

Vibration intensity has been used to identify the location of a vibration source in a vibrating system. By using vectors representation, the source of the power flow and the vibration energy transmission paths can be revealed. However, due to the large surface area of a plate-like structure, clear transmission paths cannot be achieved using the vectors representation. Experimentally, for a large surface object, the number of measured points will also be increased. This requires a lot of time for measurement. In this study, streamlines representation is used to clearly indicate the power flow transmission paths at all surface plate for FEM and experiment. To clearly improve the vibration intensity transmission paths, streamlines representation from experimental works and FEM computations are compared. Improved transmission paths visualization for both FEM and experiment are shown in comparison to conventional vectors representation. These streamlines visualization is useful to clearly identify vibration source and detail energy transmission paths especially for large surface plate-like structures. Not only that, this visualization does not need many measured point either for experiment or FEM analysis.

• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.644-664
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• 2021

Objective : Since the enactment of the Special Act on Korean Medical Residents, neurosurgeons working at training hospitals have been performing the duties of residents, in addition to their existing patient care responsibilities, which include surgery, education, and research. This study explores the relationships between work intensity, work-life balance, and burnout experienced by Korean neurosurgeons. Methods : The participants (n=451) were neurosurgeons working at training hospitals throughout Republic of Korea. Data on socio-demographic characteristics (including objective and subjective work environment), work intensity, work-life balance, and burnout were gathered using self-report questionnaires completed between March 1 and December 20, 2019. The data were analyzed using descriptive statistics, independent samples t-tests, one-way analysis of variance, Pearson's correlations, and multiple regression analysis. IBM SPSS Statistics for Windows, version 25 (IBM Corp., Armonk, NY, USA) was used for the analyses. Results : The work intensity, work-life balance, and burnout levels of neurosurgeons were 3.95, 3.57 (on a scale from 1 to 5) and 4.60 (on a scale from 1 to 7); and 280 (62.1%) of 451 neurosurgeons were found to be experiencing burnout. By controlling for the socio-demographic characteristics, the effects of work intensity and work-life balance on burnout were analyzed. Work intensity (B=0.314), work-life balance-family and leisure (B=0.216), work-life balance-growth (B=0.147), job stress (B=0.133), and satisfaction with human relationships (B=-0.069) were shown to be significant (all p<0.05), and they were found to affect burnout in the abovementioned order. The overall explanatory power was 58.3% (p<0.05), and the explanatory power with the addition of independent variables such as work intensity and work-life balance was 14.5% (p<0.05). Conclusion : This study showed that Korean neurosurgeons working at training hospitals experienced a high level of work intensity and job stress, and low work-life balance. Additionally, nearly half of the neurosurgeons were found to experience burnout related to factors such as work intensity, work-life balance, job stress, and satisfaction with human relationships. In particular, these factors seem to have deteriorated further after the implementation of the Special Act on Korean Medical Residents. These very high levels of burnout among Korean neurosurgeons who care for patients with both brain and spinal diseases may have a very important impact on patients' health. Therefore, it is recommended that the Korean Neurosurgical Society and the Korean government make efforts to improve the factors that affect burnout among Korean neurosurgeons.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.192-205
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• 2020

Seismic design practices and seismic response analyses of civil structures and nuclear power plants (NPPs) have conventionally used the peak ground acceleration (PGA) or spectral acceleration (S_a) as an intensity measure (IM) of an earthquake. However, there are many other earthquake IMs that were proposed by various researchers. The aim of this study is to investigate the correlation between seismic responses of NPP components and 23 earthquake IMs and identify the best IMs for correlating with damage of NPP structures. Particularly, low- and high-frequency ground motion records are separately accounted in correlation analyses. An advanced power reactor NPP in Korea, APR1400, is selected for numerical analyses where containment and auxiliary buildings are modeled using SAP2000. Floor displacements and accelerations are monitored for the non- and base-isolated NPP structures while shear deformations of the base isolator are additionally monitored for the base-isolated NPP. A series of Pearson's correlation coefficients are calculated to recognize the correlation between each of the 23 earthquake IMs and responses of NPP structures. The numerical results demonstrate that there is a significant difference in the correlation between earthquake IMs and seismic responses of non-isolated NPP structures considering low- and high-frequency ground motion groups. Meanwhile, a trivial discrepancy of the correlation is observed in the case of the base-isolated NPP subjected to the two groups of ground motions. Moreover, a selection of PGA or S_a for seismic response analyses of NPP structures in the high-frequency seismic regions may not be the best option. Additionally, a set of fragility curves are thereafter developed for the base-isolated NPP based on the shear deformation of lead rubber bearing (LRB) with respect to the strongly correlated IMs. The results reveal that the probability of damage to the structure is higher for low-frequency earthquakes compared with that of high-frequency ground motions.