• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.1
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• pp.71-80
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• 1994

This study was conducted to evaluate worker exposure to welding fume in automobile body shop and to evaluate metal components by type of welding. The results are summarized as follows: 1. Average concentrations of total welding fume without and with ventilation were $5.2mg/m^3$ and $2.49mg/m^3$, respectively. Thus, the average reduction rate of total fume by ventilation was 52.1 %. 2. The highest fume concentration was indicated at shielded arc welding, followed by $CO_2$ gas welding, argon arc welding, and spot welding in order of decreasing concentration. 3. Average respirable fume concentrations without and with ventilation were $2.97mg/m^3$ and $1.64mg/m^3$, respectively. 4. Further analysis of welding fume indicated that total fume consisted of $Fe_2O_3$, ZnO, Mn, Pb, and CuO, in order of decreasing amount. Combined effect of metals was below the American Conference of Governmental Industrial Hygienists (ACGIH)Threshold Limit Values (TLVs).

• Applied Microscopy
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• v.39 no.1
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• pp.73-77
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• 2009

Contaminative artifacts such as carbonaceous materials on carbon-coated microgrids are unavoidable, which is induced by electron beam exposure inside electron microscopes. This phenomenon raise a source to produce confusing information to the samples investigated by analytical TEM, which should be alleviated as much as possible. As experimental precautions for reducing this unwanted effect, the use of $LN_2$ cooled anti-contaminator and pre-illumination of electron beam at low magnification can be helpful. Nevertheless, we should be cautious to set an illumination condition for microanalysis because the contaminative effect is dependent with the types of irradiation situations, which is well known to be a decisive factor for causing the carbonaceous artifacts. Accordingly, it is necessary that optimal illumination to minimize the contaminative effect should be selected for improving the accuracy of microanalysis. In this paper, we introduce the practical method to determine the optimal illumination condition by evaluating the contaminative effect as a function of instrumental spot size, which is directly linked with electron current density.

• Journal of the Korea Safety Management & Science
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• v.14 no.1
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• pp.53-63
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• 2012

The purpose of this study is to grasp foreign worker's industrial safety and health state, which find out the improvement to secure the basic safety net for foreign workers. We have investigated 2,050 workers through direct interviews during the period from April 12, 2010 to May 31, 2010. And the result of analysis, foreign worker's daily average working time is 10.6 hours(40.8% workers in total work 10~12 hours), the extent of exposure to harmful and dangerous working environment is 'the position which cause pain in neck, waist, hands, shoulders, legs'(69.3%), 'repetitive hands and arms movement'(66.1%). It showed 'experience of accident damage or disease related work'(27.3%), 'never apply for industrial accident compensation' is revealed high at 73%. As a result of completing a safety health education for a year, it showed 'never educated'(40.2%), 'the institute that foreign workers have used for help and advice is the foreign worker's support center'(61.9%) Thus, hiring foreign workers in the company are small in site, the environment is too harmful and dangerous. In addition, no safety and health managers, legally blind spot located in the health and safety, because it is an urgent meet for these measures to improve.

• Transactions of the Society of Information Storage Systems
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• v.6 no.2
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• pp.79-82
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• 2010

In optical imaging systems, such as microscopes, high resolution exposure systems, and optical storage devices, higher optical resolution is a requirement. One of the promising technologies that is able to satisfy this requirement with relatively simple construction and reliable performance are, solid immersion lens (SIL)-based near-field (NF) optical systems. High NA optical systems using annular apertures have been investigated as one solution to achieve higher resolutions and an extended focal depth. By applying an optimized annular aperture to convention SIL optical head resolution can be increased by approximately 20%. This novel SIL-based near-field optics will be verified through experiments such as measuring focused beam spot profiles and observing the topology of a measurement sample. The studied SIL-based near-field optics can be applicable to not only next generation optical storage device but also high resolution microscopy and pattering technologies.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.32 no.2
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• pp.51-55
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• 2021

There are several lasers available for office-based or suspension microlaryngoscopy laser procedures in the treatment of laryngeal diseases. Each has advantages and disadvantages given the depth of penetration per unit of power, absorption in water, spectral absorption characteristics, mode of delivery, safety, and cost. It is important to note that while the proper selection of indication of treatment based on a laser wavelength is critical, of equal importance is selecting the appropriate power setting, focal length (or spot size), and time of exposure. The photoangiolytic lasers precisely target hemoglobin within the microcirculation of the highly vascularized tissue and may have better hemostatic effects and preservation of surrounding normal tissue than the CO₂ laser. Although the choice of laser is purely theoretical and cannot be accurately concluded which parameters of laser (wattage and pulse width) were best to use, photoangiolytic laser surgery is safe and effective for specific laryngeal lesions. In this review, indications for photoangiolytic laser procedures for various laryngeal diseases, laser settings and surgical techniques for specific laryngeal lesions including sulcus vocalis, laryngeal dysplasia, and recurrent respiratory papillomatosis will be introduced. Pros and cons of in-office laser surgery using photoangiolytic laser and flexible CO₂ laser will also be addressed.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.65-76
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• 2006

Scz1, an isolate of Sclerotinia homoeocarpa, was recently reported as a novel pathogen responsible for dollar spot disease in Zoysiagrass, a warm season turfgrass. Scz1 possessed different characteristics on mycelial pigment, mycelial affinity and host pathogenecity compared to those of Scb1, a typical isolate, obtained from creeping bentgrass, a cool season turfgrass. In this study, only three isolates, Scz1, Scz2(another analogous isolate of Sclerotinia homoeocarpa from zoysiagrass), and Scb1, were examined at the molecular level using the internal transcribed spacer(ITS) and random amplified polymorphic DNA(RAPD) assays to verify their identification and genetic variation. As a result of ITS assay, partial ITS sequences of three isolates showed 94-97% similarity with a standardized ITS sequence of S. homoeocarpa registered on BLAST. In the analysis of RAPD, range value through similarity matrix was 0.167 between Scz1 and Scb1, 0.139 between Scz2 and Scb1, and 0.713 between Scz1 and Scz2, respectively. Furthermore, tendegram analysis indicated that Scz1 and Scz2, unlike Scb1, were clustered together as accompanying a high genetic similarity. In in vitro fungicide bioassay, $EC_{50}$ value representing the sensitivity degree to propiconazole, a well-known fungicide for dollar spot disease, was 0.012 ${\mu}g/ml$ for Sczl, 0.003 ${\mu}g/ml$ for Scz2, and 0.030 ${\mu}g/ml$ for Scb1. From all data taken, we concluded that both Scz1 and Scz2 belonged to one group of S. homoeocarpa, since they exhibit the same host range and high level of genetic similarity, whereas their chemical competences to a fungicide were different. This study would provide further approach for assessing genetic diversity of S. homoeocarpa isolates as well as characterizing individual isolate against chemical exposure.

• Journal of Environmental Health Sciences
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• v.33 no.6
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• pp.506-512
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• 2007

This study was conducted to describe the exposure levels of welding fumes by the type of manufacturers, work process, welding type and the size of manufacturers, and to find out the trend of chronological changes of airborne welding fume levels. The subjects of this study were 509 manufacturers, consisting of 11 types of manufacturers, 3 work processes, 7 welding types, in Busan from January, 1997 to December, 2005. Airborne concentration of welding fume was determined by manual of National Institute for Occupational Safety and Health (NIOSH), and the data were analyzed by using SPSS 10.0 for Windows program. The mean concentration of airborne welding fume in all manufacturers was $1.29\;mg/m^3$ (Range: $0.01{\sim}3.00\;mg/m^3)$. The level of welding fume was the highest, as $1.96\;mg/m^3$, for manufactures of motor vehicles, trailers and semi-trailers, which was lower than $5.0\;mg/m^3$ of 8 hr-TWA in Korean permissible exposure limit for welding fume. There was a significant difference in the mean levels of welding fumes by work process, showing the highest in welding workshop ($1.39\;mg/m^3$), followed by pipeline welding workshop ($1.26\;mg/m^3$) and engineering workshop ($1.20\;mg/m^3$). Among welding types, the mean level of welding fume was the highest in the type of $CO_2$ & arc welding, as $1.46\;mg/m^3$, followed by $CO_2$ welding ($1.40\;mg/m^3$), shielded metal arc welding ($1.31\;mg/m^3$), spot welding ($1.27\;mg/m^3$), and so on. The highest mean level of welding fume was $1.58\;mg/m^3$ in work process of pipe line welding workshop for the manufacturers of basic iron and steel, and $2.27\;mg/m^3$ in the type of arc welding for the manufactures building ship and boats. By the size of manufacturers, the mean concentration of welding fume for manufactures in small scale with less than 50 workers was the highest as $1.45\;mg/m^3$ (Range: $0.07{\sim}3.00\;mg/m^3)$. The mean level of welding fume was the highest as $1.39\;mg/m^3$ both in 1997 and in 2005, showing a trend of fluctuating periodically within a range of $1.10{\sim}1.39\;mg/m^3$. The above results suggested that more effective control program for work environment producing welding fumes should be developed and applied since there were significant variations in welding fume levels by the type of manufacturers, work processes, welding types, the size of manufactures, and by year.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.1
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• pp.68-82
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• 2017

Strengthening surveillance, one of the most important factors in the crime prevention environment of cultural heritages, has difficulty in evaluating and diagnosing the site. For this reasons, surveillance enhancement has been assessed by modelling the shape of cultural heritage, topography, and trees digitally. The purpose of this study is to develop the evaluation method of crime prevention environment for cultural heritage by using the 3D visual exposure index (3DVE) which can quantitatively evaluate the surveillance enhancement in three dimensions. For the study, the evaluation factors were divided into natural, organizational, mechanical, and integrated surveillance. To conduct the analysis, the buildings, terrain, walls, and trees of the study site were modeled in three dimensions and the analysis program was developed by using the Unity 3D. Considering the working area of the person, it is possible to analyze the surveillance point by dividing it into the head and the waist position. In order to verify the feasibility of the 3DVE as the analysis program, we assessed the crime prevention environment by digitally modeling the Donam Seowon(Historic Site No. 383) located in Nonsan. As a result of the study, it was possible to figure out the problems of patrol circulation, the blind spot, and the weak point in natural, mechanical, and organizational surveillance of Donam Seowon. The results of the 3DVE were displayed in 3D drawings, so that the position and object could be identified clearly. Surveillance during the daytime is higher in the order of natural, mechanical, and organizational surveillance, while surveillance during the night is higher in the order of organizational, mechanical, and natural surveillance. The more the position of the work area becomes low, the more it is easy to be shielded, so it is necessary to evaluate the waist position. It is possible to find out and display the blind spot by calculating the surveillance range according to the specification, installation location and height of CCTV. Organizational surveillance, which has been found to be complementary to mechanical surveillance, needs to be analyzed at the vulnerable time when crime might happen. Furthermore, it is note that the analysis of integrated surveillance can be effective in examining security light, CCTV, patrol circulation, and other factors. This study was able to diagnose the crime prevention environment by simulating the actual situation. Based on this study, consecutive researches should be conducted to evaluate and compare alternatives to design the crime prevention environment.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.97-107
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• 2017

In the field of automatic door, the infrared rays and microwave sensor are much used as the important components in charge of the motor's operation control of open and close through the incoming signal of object recognition. In case of existing system that the sensor of the infrared rays and microwave are applied to the automatic door, there are many malfunctions by the infrared rays and visible rays of the sun. Because the automatic doors are usually installed outside of building in state of exposure. The environmental change by temperature difference occurs the noise of object recognition detection signal. With this problem, the hardware fault that the detection sensor is unable to follow the object moving rapidly within detection area makes the sensing blind spot. This fault should be improved as soon as possible. Because It influences safety of passengers who use the automatic doors. This paper conducted an experiment to improve the detection area by installing extra ultrasonic sensor besides existing detection sensor. So, this paper realize the computing circuit and detection algorithm which can correctly and rapidly process the access route of objects moving fast and the location area of fixed obstacles by applying detection and advantages of ultrasonic signal to the automatic doors. With this, It is proved that the automatic door applying ultrasonic sensor is improved detection area of blind spot sensing through field test and improvement plan is proposed.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.261-269
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• 1997

Excised immature ovules and calli derived from the stems of cottonwood were bombarded with microprojectiles carrying plasmid DNA containing CaMV-35S promoter and ${\beta}$-glucuronidase(GUS) gene. After bombarded, the expression of GUS gene was detected by the assay of 5-bromo-4-chloro-3-indolyl-${\beta}$-gluconide(X-gluc). Transient gene expression was measured by counting the number of distinct regions of GUS activity per explant. As major parameters, the number of shots and the period of exposure to X-gluc after the bombardment were investigated for detecting GUS gene expression. In this experiment, the percents of GUS gene expression showing spots were 56.8 from immature ovules and 75.9 from micro-calli of cottonwood species. Among the treatments, two consecutive shots and 48 hour exposure produced about $25.75{\pm}2.77$(per ovule), $11.43{\pm}1.22$(per mini petridish) spots, respectively, Microprojectile particle bombardment provides a useful method to assay transient expression in both types of explants. Furthermore, our results represent that the excised ovule and/or the calli might be stably transformed by the biolistics.