• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.658-665
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• 2013

In this study, we measured particulate matter(PM) which emerged as the hot issue from the International Maritime Organization(IMO) and the exhaust emission using HANBADA, the training ship of Korea Maritime University. In particular, the PM was obtained with TEM grid. PM structure was observed by electron microscopy. And exhaust gases such as NOx, $CO_2$, and CO were measured using the combustion gas analyzer(PG-250A, HORIBA). The results of this study are as follows. 1) When the ship departed from the port, the maximum difference in PM emissions were up to 30 % due to the Bunker Change. 2) Under the steady navigation, emission of PM was $1.34mg/m^3$ when Bunker-A is changing L.R.F.O(3 %). And, at the fixed L.R.F.O (3 %), emission of PM was $1.19mg/m^3$. When the main engine RPM increased up to 20 % with fixed L.R.F.O(3 %), emission of PM was $1.40mg/m^3$. When we changed to low quality oil(L.R.F.O(3 %)), CO concentration from main engine increased about 16 %. On the other hand, when the main engine RPM is rising up to 20 %, CO concentration is increased more than 152 percent. These results imply that the changes of RPM is a dominant factor in exhaust emission although fuel oil type is an important factor. 3) The diameter of PM obtained with TEM grid is about $4{\sim}10{\mu}m$ and its structure shows porous aggregate.

• Journal of the Korean GEO-environmental Society
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• v.14 no.9
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• pp.13-19
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• 2013

The Chongok karst cave which is located in Donghae-city, has high tourist and educational value due to existence of many doline(sink hole). Whereas this cave is easy to approach for the tourists, because this cave is located near the downtown, a high environmental riskiness such as sewage flowing has been also involved. In study, we observed the variation of water quality with long-term monitoring and investigated the possibility of existence of impact factor to water eco-system and determined the proper long-term monitoring factor among many monitoring criteria. The groundwater quality was maintained in the range of about $14^{\circ}C$ in temperature, over 10mg/l in dissolved oxygen and 7-8 in pH, so the impact factor in water eco-system was not observed. The guide line to make sure of tourist safety was determined to 60mm/d as daily rainfall. The conductivity was suggested to main factor for long-term monitoring main factor and pH/turbidity was suitable for the supplementary factor. For the seasonal variation monitoring, ORP was recommended.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.59-70
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• 2022

Water distribution systems (WDSs) are a representative infrastructure injecting chlorine to disinfect the pathogenic microorganisms and supplying water from sources to consumers. Also, WDSs prescribe to maintain the usual standard (0.1-4.0 mg/L) of residual chlorine. However, the user's usage pattern, water age, network shape, and type affect the hydraulic features (i.e. nodal pressure, pipe velocity) and water quality features (i.e., the residual chlorine concentration). Therefore, this study developed an optimization approach for optimizing WDSs considering water quality-hydraulic factors using Multi-objective Harmony Search (MOHS). The design cost and the system resilience were applied as the design objective functions, and the nodal pressure and the concentration of residual chlorine are used as constraints. The derived optimal designs through this approach were analyzed according to network characteristics such as the network shapes and type. These optimal designs can meet the safety of economic and water quality aspects to increase user acceptance.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.4
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• pp.25-31
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• 2021

In this research, in order to effectively utilize the petroleum residue pitch, it was used as an adsorbent for removal of cesium ion. In this experiment, acid modification (hydrochloric acid, sulfuric acid) treatment was performed on the adsorbent to improve the ability to remove low-concentration cesium ions dissolved in water. As a result, when the reaction was performed with 9 M sulfuric acid at 25 ℃ and for 240 min, the removal efficiencies of 1.0 and 2.5 mg/L cesium ions were 66 and 51%, respectively. In addition, as the adsorption time increased in the batch experiment, the removal capacity of 1.0 and 2.5 mg/L cesium ions was improved, and when the adsorption reached for 32 hr, the removal efficiencies were 72 and 68%, respectively. Also, in order to increase the ability to remove the remaining cesium ions, an experiment was performed by temperature change (25, 37, 49 ℃), and 1.0 and 2.5 mg/L cesium ions contained in water under the operating conditions of 49 ℃ and 32 hr showed removal efficiencies of 90 and 81%, respectively. Consequently, these experimental results were intended to be used as an adsorption technology that can economically treat low-concentration cesium ions contained in water.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.53-61
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• 2006

When routine behavior control is impossible, midazolam is often used for sedation, because it has wide margin of safety, relatively few side-effects and multiple route of administration. Although intramuscular administration of all administration route is frequently used, it is a major source of anxiety, discomfort, and trauma in children. To the contrary, oral administration of midazolam is easily administered and accepted by children. But, it's therapeutic drug concentration has not been established. The purpose of this study was to compare sedation effect and physiologic parameter of oral midazolam which palliate demerits of intramuscular administration in sedating young pediatric patients with intramuscular midazolam Twelve negative children, mean age 62.5 months, who needed at least two separate restorative visits, requiring local anesthesia participated in this study On every visit, one of the following 2 different sedative regimen was given : (1) 0.30mg/kg midazolam by intramuscular administration (2) 0.75mg/kg by oral administration. Physiologic parameter(oxygen saturation, heart rate) was recorded by ten procedure and behavior was videotaped and rated using Ohio State University Behavior Rating Scale and Automated Counting System by one investigator, blind to administration route The analyzed sedative effect of oral midazolam resulted in good sedative effect, comparing to intramuscular route, And there is no statistically difference between oral and intramuscular administration of midazolam (p>0.05).

• Toxicological Research
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• v.20 no.4
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• pp.365-374
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• 2004

Inhalation toxicity, mutagenicity, and immunotoxicity tests were performed using a smoke generation system to investigate the safety of Herbrette, a tobacco substitute made with the leaves of Perilla frutescens. ICR mice were exposed to nicotine-free Herbrette smoke with concentrations of 0 (control), 4.08 $\pm$ 1.32 mg/$m^3$ (low dose), 7.72 $\pm$ 2.14 mg/$m^3$ (medium dose) and 12.83 $\pm$ 1.69 mg/$m^3$ (high dose) total particulate matters (TPM) for 4 weeks. When compared to the control group, the body weights, organ weights in the exposed groups did not show any significant differences. However, certain change of several serum chemical data and biochemical parameters were observed, however, the changes were within normal physiological ranges. Moreover, no changes in organ weight, and no gross/microscopic changes were observed between the exposed and control groups. Salmonella typhimurium reverse mutation, in vivo chromosomal aberration and micronucleus assays revealed that Herbrette did not induce mutagenicity. Upon evaluation of peripheral cellular immunity of mice through in vitro lymphocyte proliferation assay, no significant difference was observed in mean stimulation index between the exposed and control groups. Taken together, our results strongly suggest that Herbrette may not cause toxicity on mice under current condition.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.327-332
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• 2001

In recent years, experimental evidence have been suggested that melatonin has either contractive or relaxing effects on the vascular smooth muscle in vitro. But the effect of melatonin on the cardiovascular system in vivo had been emphasized about the hypotensive effect. In this work, we found not only hypotensive effect but also hypertensive effect of melatonin in rats and attempted to determine the mechanism of these effects elicited by melatonin. Regadless of concentration, melatonin(0.002~5 mg/kg) produced increase in mean blood pressure (MBP) in 36% (54/150 cases) and decrease in mean blood pressure in 64%(96/150 cases). As a whole melatonin caused an increase or a decrease in MBP without compensatory decrease or increase in heart rate. The melatonin-induced hypertension was abolished by the pretreatment of phenoxybenzamine, a ${\alpha}$-adrenoceptor antagoninst. The melatonin-induced hypotension was abolished by the pretreatment of propranolol, a ${\beta}$-adrenoceptor antagonist, ODQ, a NO-sensitive guanylate cyclase inhibitor, or nifedipine, a L-type $Ca^{2+}$ channel blocker, but not by bilateral cervical vagotomy. The results indicate that melatonin-induced hypertension may be related to ${\alpha}$-adrenoceptor stimulation and melatonin-indued hypotension may be related to ${\beta}$-adrenoceptor stimulation, inhibition of $Ca^{2+}$ channel and/or activation of guanylate cyclase.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.4
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• pp.295-303
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• 2021

Objective: Paint manufacturing industry workers are exposed to various lung cancer carcinogenic substances including hexavalent chromium and crystalline silica. Studies have been conducted on lung cancer in Paint manufacturing industry workers and the concentration of hexavalent chromium in paint industry; however, the concentration of crystalline silica and hexavalent chromium and cases of lung cancer in a single Paint factory has never been reported in Korea. Methods: To determine whether the cancer was related to his work environment, we assessed the level of exposure to carcinogens during pouring and mixing talc and pigment. In addition, a mask fit test was performed for the worker. Results: Analysis of talc and silica bulk powder materials showed that crystalline silica (quartz) was 5% in talc and 100% in silica. The green and yellow pigments contained 87% and 92% of lead chromate, respectively. Our quantitative analysis of pigment powder samples showed that the hexavalent chromium contents quantified in the green and yellow pigment samples were 87% and 92%, respectively. In order to estimate his exposure level of hexavalent chromium, we measured a personal exposure level of hexavalent chromium for a worker in accordance with the National Institute for Occupational Safety and Health #7605 method. The results showed that the worker was exposed to the high level of hexavalent chromium (0.033 mg m-3). In addition, the talc powder also contained 5% quartz, and the worker's exposure level to respirable quartz exceeded OEL. As a result of the respiratory protection fit test for workers, the overall Fit Factor was '15' when wearing a second-grade mask and '25' when wearing a first-grade mask, significantly lower than the US Occupational Safety and Health Agency (OSHA) pass value of "100". Conclusion: Workers who pouring and mixing powder materials such as talc or colored pigments in paint manufacturing company may be exposed to high concentrations of carcinogenic substances. These findings indicate that it is necessary to local ventilation system inspection, safety and health education for employers and workers, and periodically monitoring and manage the working environment.

• Safety and Health at Work
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• v.13 no.1
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• pp.9-16
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• 2022

Background: The global shift toward greener societies demands new technologies and work operations in the waste-management sector. However, progressive industrial methods do not necessarily consider workers' health. This study characterized workers' exposure to bioaerosols and investigated the bioaerosols' potential to engage the immune system in vitro. Methods: Full shift personal aerosol sampling was conducted over three consecutive days. Dust load was analyzed by gravimetry, fungal and actinobacterial spores were analyzed by scanning electron microscopy, and endotoxin by limulus amebocyte lysate (LAL) assay. In vitro exposure of HEK cells to airborne dust samples was used to investigate the potential of inducing an inflammatory reaction. Results: The total dust exposure level exceeded the recommended occupational exposure limit (OEL) of 5.0 mg/m³ in 3 out of 15 samples. The inhalable endotoxin level exceeded the recommended exposure level by a 7-fold, whereas the fungal spore level exceeded the recommended exposure level by an 11-fold. Actinobacterial spores were identified in 8 out of 14 samples. In vitro experiments revealed significant TLR2 activation in 9 out of 14 samples vs. significant TLR4 activation in all samples. Conclusion: The present study showed that the dust samples contained potentially health-impairing endotoxin, fungi, and actinobacterial levels. Furthermore, the sampled dust contained microbial components capable of inducing TLR activation and thus have the potential to evoke an inflammatory response in exposed individuals.

• Safety and Health at Work
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• v.14 no.1
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• pp.118-123
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• 2023

Background: Chronic exposure to silica is related with the provocation of an inflammatory response and oxidative stress mechanism. Vitamin D has multiple benefits in biological activities particularly respiratory system disease. Method: In this research, 20 male Wistar rats were randomly allocated into four groups (5 rats /group) as follow: Group1 received saline as (negative control) group. The group 2 received a single IT instillation of silica (positive control) group; the group 3 was co-administrated with single IT silica and Vitamin D (20 mg/kg/day) daily for a period of 90 days. The rats of group 4 received Vitamin D daily for a period of 90 days. Results: Silica significantly increased serum and lung total Oxidant Status (TOS). Meanwhile, silica reduced serum and lung total antioxidant capacity (TAC), GSH and tumor necrosis factor-α (TNF-a). Vitamin D treatment meaningfully reversed oxidative stress, antioxidants status and inflammatory response. Also, Vitamin D improved histopathological changes caused by silica. Conclusion: These findings indicate that Vitamin D exerts protective effects against silica-induced lung injury. It seems that Vitamin D has potential use as a therapeutic object for silica induced lung injure.