• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.3
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• pp.213-232
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• 2009

This document was prepared to review and summarize the analytical methods for airborne and bulk asbestos. Basic principles, shortcomings and advantages for asbestos analytical instruments using phase contrast microscopy(PCM), polarized light microscopy(PLM), X-ray diffractometer (XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM) were reviewed. Both PCM and PLM are principal instrument for airborne and bulk asbestos analysis, respectively. If needed, analytical electron microscopy is employed to confirm asbestos identification. PCM is used originally for workplace airborne asbestos fiber and its application has been expanded to measure airborne fiber. Shortcoming of PCM is that it cannot differentiate true asbestos from non asbestos fiber form and its low resolution limit ($0.2{\sim}0.25{\mu}m$). The measurement of airborne asbestos fiber can be performed by EPA's Asbestos Hazard Emergency Response Act (AHERA) method, World Health Organization (WHO) method, International Standard Organization (ISO) 10312 method, Japan's Environmental Asbestos Monitoring method, and Standard method of Indoor Air Quality of Korea. The measurement of airborne asbestos fiber in workplace can be performed by National Institute for Occupational Safety and Health (NIOSH) 7400 method, NIOSH 7402 method, Occupational Safety and Health Administration (OSHA) ID-160 method, UK's Health and Safety Executive(HSE) Methods for the determination of hazardous substances (MDHS) 39/4 method and Korea Occupational Safety and Health Agency (KOSHA) CODE-A-1-2004 method of Korea. To analyze the bulk asbestos, stereo microscope (SM) and PLM is required by EPA -600/R-93/116 method. Most bulk asbestos can be identified by SM and PLM but one limitation of PLM is that it can not see very thin fiber (i.e., < $0.25{\mu}m$). Bulk asbestos analytical methods, including EPA-600/M4-82-020, EPA-600/R-93/116, OSHA ID-191, Laboratory approval program of New York were reviewed. Also, analytical methods for asbestos in soil, dust, water were briefly discussed. Analytical electron microscope, a transmission electron microscope equipped with selected area electron diffraction (SAED) and energy dispersive X-ray analyser(EDXA), has been known to be better to identify asbestiform than scanning electron microscope(SEM). Though there is no standard SEM procedures, SEM is known to be more suitable to analyze long, thin fiber and more cost-effective. Field emission scanning electron microscope (FE-SEM) imaging protocol was developed to identify asbestos fiber. Although many asbestos analytical methods are available, there is no method that can be applied to all type of samples. In order to detect asbestos with confidence, all advantages and disadvantages of each instrument and method for given sample should be considered.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.1
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• pp.64-74
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• 2016

Objectives: The purpose of this study was to investigate whether chemical exposure among workers has relevance to dyspnea using data from the $3^{rd}$ Korea Working Conditions Survey. Methods: The research subjects were 29,711 wage workers. Chemical exposures consist of four factors, (1) breathing in vapors, fumes, dust and dirt, (2) breathing in organic solvent vapors, (3) handling or touching chemicals, and (4) secondhand smoke. Multiple logistic regression analysis was performed to examine the association between chemical exposure and dyspnea in the last 12months using proc surveylogistic in SAS 9.3 statistical software excluding people who had received a diagnosis of hypertension or obesity that can affect the respiratory distress symptoms(n=27,842). Results: Chemical exposure among workers was associated with dyspnea after adjustment for demographics and job characteristics. Prevalence of dyspnea was 4.9 per 1,000 among men and 5.8 per 1,000. Compared to a total score of 0 points of chemical exposure among workers, a total score of 1, 2-3, and 4 points tended to have increased risk of dyspnea in a dose-response manner for both men (OR=1.43, 1.93, and 4.26; P-for trend=0.002) and women(OR=1.10, 2.81, and 7.70; P-for trend=0.002). Stratified analysis by duration of current job showed that the association between chemical exposure and dyspnea tended to get stronger until 15 years and then disappeared afterwards, which reflects healthy worker survivor effect. Conclusions: We observed significant association between chemical exposure and dyspnea using the data of the $3^{rd}$ Korea Working Conditions Survey. Our results warrants providing knowledge related to chemical exposure, performing prevention activities, and creating various health policies to protect workers.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.567-573
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• 2012

Compared with the natural marble, the artificial marble has the advantages of excellent appearance, high degree of finish, even color, fine pressure and wear resistance, bear erosion and weathering, etc. It can be widely used in kitchen countertops, bath vanity tops, table tops, furniture, reception desks, etc. However, large amounts of artificial marble waste such as scraps or dust have been generated from sawing and polishing processes in artificial marble industry. Waste from artificial marble industry is increasing according to demand magnification of luxurious interior material. Artificial marble wastes can be recycled as aluminum oxide used as raw materials in electronic materials, ceramics production, etc., and methyl methacrylate(MMA) which become a raw material of artificial marble by pulverization, pyrolysis and distillation processes. The characteristics of artificial marble wastes was analyzed by using TGA/DSC and element analysis. Crude aluminum oxide was obtained from artificial marble waste by pulverization and thermal decomposition under nitrogen atmosphere. In this work, Box-Behnken design was used to optimize the pyrolysis process. The characteristics of crude aluminum oxide was evaluated by chromaticity analysis, element analysis, and surface area.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.2
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• pp.71-78
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• 2012

Eupatilin, one of representative medical components of mugwort, can be efficiently extracted from the 'Gangwha Sajabalssuk'. The Eupatilin content may depend on environmental factors such as soil and regional climate in addition to a genetic factor and Gangwha region has a profitable environmental condition for the mugwort growth. In this study, the climatological characteristics of Gangwha was analyzed in order to find the environmental condition of mugwort containing high Eupatilin in term of atmospheric, oceanographic and land variables. The climate of Gangwha is characterized by the relatively low daily temperature and large diurnal variation with plenty of solar radiation, long sunshine duration and less cloudiness. According to our correlation analysis, the long sunshine duration and the large diurnal temperature variation are highly correlated with the Eupatilin contents. The result implies that Gangwha has the favorable conditions for the cultivation and the habitat of the high-Eupatilin concentrated mugwort. Because of the sea surrounding Gangwha Island with low salinity and moderate wind, the salt contained in sea breeze is relatively low compared to other regions. Furthermore, Gangwha has clean atmospheric environment compared to other regions because the concentrations of toxic gases harmful to crop growth such as nitrogen dioxide ($NO_2$), sulfite gas ($SO_2$) and fine dust (PM-10) are lower in the air. The ozone ($O_3$) concentration is moderate and within the level of natural production. It is also found that moderately coarse texture or fine loamy soils known as good for water drainage and for the growth and cultivation of the 'Gangwha-mugwort' are distributed throughout the areas around mountainous districts in Gangwha, coinciding with those of mugwort habitat.

• Korean Journal of Construction Engineering and Management
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• v.20 no.6
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• pp.126-131
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• 2019

The estimation of available solar energy at particular locations is critical to find and assess suitable locations of PV sites. The amount of PV power generation is however affected by various geographical factors (e.g., weather), which may make it difficult to identify the complex relationship between affecting factors and power outputs and to apply findings from one study to another in different locations. This study thus undertakes a regression analysis using data collected from 172 PV plants spatially distributed in Korea to identify critical weather conditions and estimate the potential power generation of PV systems. Such data also include solar radiation, precipitation, fine dust, humidity, temperature, cloud amount, sunshine duration, and wind speed. The estimated PV power generation is then compared to the actual PV power generation to evaluate prediction performance. As a result, the proposed model achieves a MAPE of 11.696(%) and an R-squred of 0.979. It is also found that the variables, excluding humidity, are all statistically significant in predicting the efficiency of PV power generation. According, this study may facilitate the understanding of what weather conditions can be considered and the estimation of PV power generation for evaluating and determining suitable locations of PV facilities.

• Explosives and Blasting
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• v.39 no.3
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• pp.15-23
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• 2021

Ventilation shafts are pathways in mines and tunnels for the removal of dust or smoke during underground space construction and operation. In mines, blasting with long blast holes is preferred for the excavation of a ventilation shaft in the 10~20m long crown pillar section. In this case, the bottom part of the blast hole is completely drilled in order to determine the drilling error, and this causes a problem of lowering the explosive charge and blasting efficiency. It is possible to solve the problem of explosive loading and to increase the blast efficiency by covering the curb of the blasthole by using stemming material. In this study, simulations for the blasting of a ventilation shaft were performed with various stemming lengths and the blasthole diameters(45, 76mm) using AUTODYN 2D SPH(Smooth particle hydrodynamics) analysis technique. Also the optimal bottom stemming column was derived by checking the size of the boulder and burden line according to blasting. Analysis result, blasting efficiency is lessened in case of stemming length less than 30cm and the optimal length of the stemming material should be 30cm or higher to achieve high efficiency of blasting.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1191-1205
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• 2022

Particulate matter(PM) among air pollutants with complex and widespread causes is classified according to particle size. Among them, PM_2.5 is very small in size and can cause diseases in the human respiratory tract or cardiovascular system if inhaled by humans. In order to prepare for these risks, state-centered management and preventable monitoring and forecasting are important. This study tried to predict PM_2.5 in Seoul, where high concentrations of fine dust occur frequently, using two ensemble models, random forest (RF) and extreme gradient boosting (XGB) using 15 local data assimilation and prediction system (LDAPS) weather-related factors, aerosol optical depth (AOD) and 4 chemical factors as independent variables. Performance evaluation and factor importance evaluation of the two models used for prediction were performed, and seasonal model analysis was also performed. As a result of prediction accuracy, RF showed high prediction accuracy of R² = 0.85 and XGB R² = 0.91, and it was confirmed that XGB was a more suitable model for PM_2.5 prediction than RF. As a result of the seasonal model analysis, it can be said that the prediction performance was good compared to the observed values with high concentrations in spring. In this study, PM_2.5 of Seoul was predicted using various factors, and an ensemble-based PM_2.5 prediction model showing good performance was constructed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.5
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• pp.405-412
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• 2022

This paper studies the method of estimating power loss and classifying the factors for improving the power generation efficiency through O&M. It is installed under various climatic conditions worldwide, operational and maintenance technologies suitable for the characteristics of the installation location are required. Existing studies related to solar power generation efficiency have been actively quantifying the impact on short-term losses by environmental factors such as high temperature, dust accumulation, precipitation, humidity, and wind speed, but analysis of the overall impact from a long-term operation perspective is limited. In this study, the potential for efficiency improvement was analyzed by re-establishing a loss classification system according to the power flow of solar power to derive a comprehensive efficiency model for long-term operation and estimating power loss through a case study for each region where climate conditions are classified. As a result of the analysis, the average annual potential for improving soiling loss was 26.9%, Death Valley 7.2%, and Seoul 3.8%. Aging losses was 6.6% in the 20th year as a cumulative. The average annual potential due to temperature loss was 2.9 % for Doha, 1.9% for Death Valley, and 0.2% for Seoul.

• Journal of Korea Port Economic Association
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• v.40 no.2
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• pp.39-52
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• 2024

As the 'Eco-friendly conversion project for Port's CHE(Cargo handling Equipment) ' which has started in 2014 ends in 2024, in addition to the existing 'Low pollution' paradigm to respond to fine dust problems, a full-fledged 'Zero-emission' conversion is to be required to implement 2050 carbon neutrality at the port level. Accordingly, this study calculated the future replacement demand for container handling equipments at the four major domestic ports(Busan, Incheon, Yeosu Gwangyang, and Ulsan), and assumed a scenario where every CHE supposed to eb replaced is electrified inturn every year. And then the resulting future emission reduction effect accordingly was calculated and analyzed. In particular, compared and analyzed the emission outlook applying the life-cycle concept(LCA), which is being adopted as a new emission calculation standard in most industrial fields, and the existing emission calculation concept that only considers direct emissions within the port, to provide more effective implications for the promotion of follow-up conversion projects. According to the analysis results, if the CHE is replaced according to the proposed schedule, it is expected that the existing emissions can be reduced by 79% compared to BAU in 2025 and 97.4% in 2030. However, if the LCA is applied, it is expected to be reduced by only 27.6% by 2030. This suggests that port's CHE must be converted to zero emissions and at the same time establish an Ports' self-sufficient energy grid based on renewable energy.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.2
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• pp.269-280
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• 2018

This paper reports the results of field evaluation to determine the levels of heavy metals in major industrial complexes in Korea over a seven year period (2007~2013). The measurement of heavy metal was conducted using quartz fiber filter sampling and ICP-AES analysis. In order to validate the analytical performance of these methods, studies were also carried out to investigate data quality control(QC) parameters, such as the method detection limit (MDL), repeatability, and recovery efficiencies. The average concentrations of total suspended particulates (TSP) for the nine industrial complexes in Korea were $104{\sim}169{\mu}g/m^3$, which was higher than other industrial complexes and urban areas. The Sihwa and Banwol industrial complexes were shown to be the biggest contributing sources to high TSP emission ($159{\mu}g/m^3$ and $169{\mu}g/m^3$, respectively). The concentrations of heavy metals in TSP were higher in the order of Fe>Cu>Zn, Pb, Mn>Cr, Ni, As and Cd. It was observed that Fe was the highest in the Gwangyang and Pohang steel industrial complexes. The concentrations of Zn and Pb were high in Onsan, Sihwa and Banwol industrial complexes, and this was attributed to the emission from the nonferrous industry. Additionally, Cr and Ni concentrations were high in the Sihwa and Banwol industrial complexes due to plating industry. On the other hand, Ulsan and Onsan industrial complexes showed high Cr and Ni concentrations as a response to the emission of metal industry related to automobile. The correlation analysis revealed the high correlation between Cr and Ni in plating industry from Sihwa and Banwol industrial complexes. Adding to this, components related to coal combustion and road dust showed high correlation in Pohang and Gwangyang industrial complexes. Then Onsan and Ulsan industrial complexes showed high correlation among components related to the nonferrous metals.