• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.1
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• pp.87-98
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• 1999

The objectives of this study were to evaluate exposures to airborne methylene chloride and postshift carboxyhemoglobin (COHb) in blood of workers engaged in processes using blowing or cleaning agents, and to investigate correlation between methylene chloride concentrations and the blood COHb levels of workers. The geometric mean (GM) of workers' exposures (8 hour-time weighted averages, TWA) to airborne methylene chloride during cleaning molds using rags wetted with the solvent in the manufacture of flexible polyurethane foam (GM = 61.4 ppm), during operating the dip tank for cleaning molds in the manufacture of lens (GM = 61.0 ppm), and during cleaning the blowing nozzles by spraying the solvent in the manufacture of shoes (GM = 117.2 ppm) were exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value ($TLV^{(R)}$)-Time Weighted Average (TWA) (50 ppm). The COHb levels were significantly different among groups (p<0.05). The average COHh levels in blood of non-smoking workers were 2.0% in. low-level (<50 ppm) exposure group, and 3.9 % in high-level (>50ppm) exposure group. The average COHb levels in smoking workers were 3.1% in low-level exposure group, and 4.8% in high-level exposure group. The blood COHb levels of no-exposed workers to methylene chloride were 1.8% in non-smoking group, and 2.8% in smoking group. It was found that the COHb level dependeds on the methylene chloride concentration and smoking habit, and was highly correlated with methylene chloride concentration in air. The correlation coefficient was 0.81 among non-smoking workers. The estimated COHb level (3.6%) and 95% upper confidence limit (4.0%) corresponding to TLV-TWA of methylene chloride exceeded the current ACGIH Biological Exposure Index (COHb 3.5%) for carbon monoxide. The estimated COHb level (5.4%) at 100 ppm exceeded the standard (5%) recommended by National Institute for Occupational Safety and Health (NIOSH) for preventing adverse cardiovascular effect. The estimated COHb value and 95% upper confidence limit at 25 ppm of the Occupational Safety and Health. Adminstration (OSHA) Permissible Exposure Limit-TWA (PEL-TWA) were 2.6% and 3.0%, respectively. It is suggested that COHb in blood be kept below 3.0% to comply with OSHA PEL-TWA.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.46-51
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• 2004

The film coated snap bean (Phaseolus vulgaris) seeds with five different coating materials treated with 3% increase in seed weight were planted at sandy loam soil controlled moisture content of 18, 19, 20 and 21 %. The oxygen diffusion rate (ODR) was calculated from the different moisture content soil. The number of normal seedlings, seedling vigor, and seedling capability in field (seed vigor x dry matter weight) were observed at 9 days after planting and compared to the changes of ODR. The germination rate and ODR were sharply decreased simultaneously in the seeds planted at 21 % soil moisture content. Seedling emergence did not occur at all as the soil moisture content increased above 22 %. Hence this value should be considered as the threshold of soil moisture content for seedling emergence. An ODR value under 20% did not influence the percent emergence significantly. The certain difference observing in the emergence at the same ODR was not related clearly to the condition of soil. So it can be assumed that the limit of soil moisture content for the emergence of snap bean was approximately 20%. The value of 18% soil moisture content may be considered as the optimum for snap bean emergence. There was close relationship between the mean value of ODR in different soil moisture contents and the emergence. The germination rates of the seeds coated with the different materials were quite different when the seeds were planted at 21 % soil moisture. Dry weight of the seedlings from film coated seeds was decreased slightly, but the germination rates were not much different from the non-treated control under relatively higher soil moisture content (21 %). Major factor lowering emergence rate was oxygen stress while film coating act as a minor constraint for snap bean sown in excess soil moisture condition.

• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.1101-1108
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• 2012

In this paper, we proposed an algorithm for real-time lane detecting against luminance variation using morphological image processing and edge-based region segmentation. In order to apply the most appropriate threshold value, the adaptive threshold was used in every frame, and perspective transform was applied to correct image distortion. After that, we designated ROI for detecting the only lane and established standard to limit region of ROI. We compared performance about the accuracy and speed when we used morphological method and do not used. Experimental result showed that the proposed algorithm improved the accuracy to 98.8% of detection rate and speed of 36.72ms per frame with the morphological method.

• Atmosphere
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• v.24 no.3
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• pp.445-456
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• 2014

A real-time quality control system for meteorological data (air temperature, air pressure, relative humidity, wind speed, wind direction, and precipitation) measured by an integrated meteorological sensor has been developed based on comparison of quality control procedures for meteorological data that were developed by the World Meteorological Organization and the Korea Meteorological Administration (KMA), using time series and statistical analysis of a 12-year meteorological data set observed from 2000 to 2011 at the Incheon site in Korea. The quality control system includes missing value, physical limit, step, internal consistency, persistence, and climate range tests. Flags indicating good, doubtful, erroneous, not checked, or missing values were added to the raw data after the quality control procedure. The climate range test was applied to the monthly data for air temperature and pressure, and its threshold values were modified from ${\pm}2{\sigma}$ and ${\pm}3{\sigma}$ to ${\pm}3{\sigma}$ and ${\pm}6{\sigma}$, respectively, in order to consider extreme phenomena such as heat waves and typhoons. In addition, the threshold values of the step test for air temperature, air pressure, relative humidity, and wind speed were modified to $0.7^{\circ}C$, 0.4 hPa, 5.9%, and $4.6m\;s^{-1}$, respectively, through standard deviation analysis of step difference according to their averaging period. The modified quality control system was applied to the meteorological data observed by the Weather Information Service Engine in March 2014 and exhibited improved performance compared to the KMA procedures.

• Environmental and Resource Economics Review
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• v.28 no.4
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• pp.617-643
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• 2019

The Demilitarized Zone(DMZ) is a buffer zone set between the southern and northern limit lines established after the 1953 Armistice Agreement. It is an important natural environment conservation area where wild species of animals and plants live. On the other hand, the development pressure on the DMZ will increase when the inter-Korean economic cooperation is activated in the future. As a result, DMZ development should consider not only the economic cost-benefit aspects, but also how to assess and conserve the biodiversity of the DMZ, as well as the recovery costs and budget. This paper develope a sustainable DMZ management model under biodiversity uncertainly by using real option approach. The model is also designed to reflect the political risk and regional specificity of the DMZ. Through empirical analysis, I derive the biodiversity threshold (b^*) that can secure the DMZ investment economy under uncertainty. In addition, through the sensitivity analysis, I derive the factors influencing the biodiversity threshold, and suggest the policy implications for sustainable management of DMZ.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.2
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• pp.113-127
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• 2007

In this study, a model to calculate the expected total construction cost is developed that simultaneously considers the rehabilitation cost related to the sliding of the caisson, the economic damage cost due to harbor shutdown in the event of excessive caisson sliding, and the economic damage cost due to temporal operational stoppage by excessive wave overtopping. A discount rate is used to convert the damage costs occurred at different times to the present value. The optimal cross-section of a caisson is defined as the cross-section that requires a minimum expected total construction cost within the allowable limit for the expected sliding distance of the caisson during the lifetime of the breakwater. Two values are used for the allowable limit: 0.3 and 0.1 m. It was found that the economic damage cost due to harbor shutdown by excessive caisson sliding is more critical than the rehabilitation cost of the caisson or the economic damage cost by excessive wave overtopping in the decision of the optimal cross-section. In addition, the optimal cross-section of the caisson was shown to be determined by the allowable limit for the expected sliding distance rather than the minimum expected total construction cost as a larger value is used for the threshold sliding distance of the caisson for harbor shutdown.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.1-10
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• 2001

This study was performed to evaluate chromium in air and chromium concentrations in whole blood and urine of workers at chrome plating factories, and to determine the correlation between environmental and biological chromium levels. This study involved 29 workers as study group and 24 undergraduate students as control group. The geometric means(GM) of airborne hexavalent chromium and total chromium concentrations in the plating factories were 3.4 $\mu\textrm{g}$/㎥ and 10.8 $\mu\textrm{g}$/㎥, respectively. Hexavalent chromium levels in two of total 29 measurements exceeded the korean occupational exposure limit and the American Conference of Governmental Industrial Hygienists Threshold Limit Value(ACGIH-TLV) of 50$\mu\textrm{g}$/㎥. Only one sample for total chromium exceeded the Korea occupational exposure limits, the ACGIH-TLV, and the National Institute for Occupational Safety and Health Recommended Exposure Limits(NIOSH-REL) of 500 $\mu\textrm{g}$/㎥. The GM of chromium concentrations in blood and urine of workers exposed to chromium were 8.4 $\mu\textrm{g}$/L and 11.9 $\mu\textrm{g}$/L. The GM of chromium concentrations in blood and urine of workers exposed to chromium were 8.4 $\mu\textrm{g}$/L and 11.9 $\mu\textrm{g}$/L, respectively, whereas the chromium concentrations in blood and urine of the controls were 1.6 $\mu\textrm{g}$/L and 3.8 $\mu\textrm{g}$/L, respectively. There were statistically significant differences of blood and urine concentrations between study group and control group (p<0.01). The chromium concentrations in urine were most highly related to hexavalent chromium, concentration in air(r=0.642, p<0.01). Also, there was a relatively high correlation between the hexavalent chromium concentrations in air and chromium concentrations in whole blood(r=0.557, p<0.05). These results indicate that whole-blood chromium with urinary chromium could be an indicator of chromium body burden caused by exposure to chromic acid mist in plating operation.

• Toxicological Research
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• v.27 no.3
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• pp.137-141
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• 2011

This study was conducted to assess the exposure risk through inhalation to baby powder for babies and adults under simulated conditions. Baby powder was applied to a baby doll and the amount of baby powder consumed per application was estimated. The airborne exposure to baby powder during application was then evaluated by sampling the airborne baby powder near the breathing zones of both the baby doll and the person applying the powder (the applicator). The average amount of baby powder consumed was 100 mg/application, and the average exposure concentration of airborne baby powder for the applicator and baby doll was 0.00527 mg/$m^3$ (range 0.00157~0.01579 mg/$m^3$) and 0.02207 mg/$m^3$ (range 0.00780~0.04173 mg/$m^3$), respectively. When compared with the Occupational Exposure Limit of 2 mg/$m^3$ set by the Korean Ministry of Labor and the Threshold Limit Value (TLV) of 2 mg/$m^3$ set by the ACGIH (American Conference of Governmental Industrial Hygienists), the exposure concentrations were much lower. Next, the exposure to asbestos-containing baby powder was estimated and the exposure risk was assessed based on the lung asbestos contents in normal humans. As a result, the estimated lung asbestos content resulting from exposure to asbestos-containing baby powder was found to be much lower than that of a normal Korean with no asbestos-related occupational history.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.3
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• pp.193-201
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• 2006

This study was performed to investigate employee exposures to waste anesthetic gases, such as enflurane and sevoflurane in operating rooms of general surgical, children's and dental clinics of a large hospital located in Seoul and to analyze factors affecting the concentrations of waste anesthetic gases. The results of the study are summarized below. 1. Based on results of personal and area samples for airborne enflurane, all of the employees investigated in this study were exposed to airborne enflurane concentrations below the ACGIH-threshold limit value (TLV) of 75 ppm. 2. However, based on results of personal samples for sevoflurane, employees of two (2) out of eleven (11) operating rooms were exposed to sevoflurane concentrations in excess of the NIOSH recommended exposure limit (REL) of 2 ppm. A similar trend was found in the area samples. 3. To investigate the source of sevoflurane emissions, airborne sevoflurane concentrations were measured on an anesthesia machine, a drug cabinet and a desk. It was indicated that the geometric means were 0.93 ppm, 0.83 ppm and 0.72 ppm, respectively. 4. Factors affecting waste anesthetic gas concentrations were the age of anesthesia machine, the volume of operating room and the extent of ventilation (p<0.05). 5. It is recommended that the use of anesthesia equipments be properly controlled, the operating room be well ventilated, and the airborne concentrations of anesthetic gases be continuously monitored.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.1
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• pp.32-40
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• 2008

Methyl bromide has been used as a representative fumigant for quarantine, and several poisoning cases have occurred recently by this chemical in Korea. The purpose of this study is to evaluate workers' exposures to airborne methyl bromide in the importing and exporting plant products quarantine companies. Air samples were collected 400/200 mg Anasorb 747TM and were analyzed by gas chromatograph /flame ionization detector according to the Occupational Safety and Health Agency (OSHA) Method PV2040. Geometric mean (GM) and arithmetic mean (AM) of total 27 workers' exposure concentrations to airborne methyl bromide were 1.12 ppm and 0.24 ppm, respectively. Two exposures(12.1 ppm and 12 ppm as 8hr-TWA) of total 27 workers' exposures exceeded the Korean standard (5 ppm) of Ministry Labor, while 4 exposures (15%) exceeded the Threshold Limit Value (TLV) (1 ppm) of American Conference of Governmental Industrial Hygienists (ACGIH). Seven samples (11%) of total 63 short-term air samples exceeded the OSHA Permissible Exposure Limit (PEL) 20 ppm (Ceiling). The opening (management) task in wood fumigation by tent showed the highest short-term exposure concentrations (AM: 18.6 ppm, GM: 0.58 ppm, maximum: 340.7 ppm). The maximum level in treatment task of the same process was 2.01 ppm. Methyl bromide concentrations in opening operation was significantly higher than that in treatment operation (p<0.05). In conclusion, the GM of workers' 8hr-TWA exposures to airborne methyl chloride in the importing/exporting plant quarantine industry was estimated below the ACGIH TLV (1 ppm). However, opening task in the fumigation of wood being covered with tent or fumigation of pant products in container showed the levels exceeding ACGIH TLV (1 ppm), and opening task in the fumigation of wood being covered with tent showed the level exceeding the Korean standard of Ministry of Labor (5 ppm).