• Tunnel and Underground Space
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• v.28 no.4
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• pp.372-386
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• 2018

The air quality near the backfilled site area is significantly deteriorated during and even after the curing period of the backfill materials. Hazardous gases such as NH3 and CO2 may leak out prolongedly from the mined-out sites backfilled with the composite carbonate-based material; leakage can be observed at the underground working sites as well as on the surface. At operating mines, underground gas leakage will severely aggravate the workplace environment. The ventilation schemes should supply sufficient air to dilute the contaminated air, and control the toxic gas leakage and dispersion. This study shows the applicability of pressurization ventilation system to control gas leakage and dispersion at the backfilled underground mine site.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.2
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• pp.156-165
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• 2015

Objectives: The purpose of this study was to investigate the possible effects of a gasoline vapor recovery system on personal exposure levels of gasoline vapor constituents including benzene, toluene, ethyl benzene, xylene(BTEX), and methyl tert-butyl ether(MTBE) among gas station workers in a metropolitan area. Methods: Thirty-one gas station workers at ten gas stations in a metropolitan area were selected as subjects for this study. Test method PV2028 as recommended in the OSHA process was used for sampling and analysis. Results: The personal exposure levels of benzene, toluene, ethyl benzene, xylene, MTBE and gasoline vapor in the gas station workers were $0.0018{\pm}0.0069ppm$, $0.0077{\pm}0.0137ppm$, $0.0002{\pm}0.0008ppm$, $0.0016{\pm}0.0084ppm$, $0.2619{\pm}0.3340ppm$, and $1.4940{\pm}1.7984ppm$, respectively. After adjustment for refueling frequency and volume, personal exposure levelswere higher in the gas stations where gasoline vapor recovery systems(Stage II) were not installed, but the results were not statistically significant. Gasoline vapor concentrations showed a positive correlation to the level of MTBE, a gasoline additive. Conclusions: Vapor recovery systems(Stage II) were effective not only in reducing emissions of air pollutants, but also in reducing exposure to hazardous substances among gas station workers. In addition, acorrelation between gasoline vapors and MTBE concentration was confirmed.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.335-343
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• 1996

The dipole-dipol electrical resistivity survey was conducted to investigate the probable contamination of the Han river by leachate from the near-by Nanjido Landfill. The survey line of 3 km was set along the unpaved road toward the Han river. For the convenience of the field work, the survey line was divided into four segments. The complete two-dimensional resistivity section was constructed by connecting the inversion result of each segment. Gravity survey was also carried out along the profile parallel to the resistivity line. Near surface resistivity generally appeared to be of very low value in most part of the survey area and the boundary between the alluvium layer and underlying basement rocks is well discriminated on the resistivity section. These results agree well with those of the preceding Schlumberger depth sounding made at adjacent area by Lee and fun (1995). The variation of thickness of the alluvium layer delineated by gravity anomaly profile also correlates well with the result of the resistivity survey on the qualitative basis. The problem of contamination by leachate from the Nanjido Landfill, where various waste materials have been dumped without any proper treatment facilities, has been remains unsolved yet. Therefore, we present the most probable passages of leachate flow based on the survey results and have briefly discussed about measure for contamination control. Considering the thickness of alluvium and the possible existence of fractured zone, the middle point between 1st and 2nd landfill and the midst of 1st landfill are the most hazardous regions to make leachates flow into the Han river. Since large amounts of leachates are observed from the test wells located on the lines extending from the border between the 1st and 2nd landfill and the middle of the lst landfill, contamination protection barriers are strongly recommended near these regions.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.1
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• pp.11-22
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• 2000

Polycyclic aromatic hydrocarbons(PAHs) have known as potentially hazardous air pollutants(HAPs0 to human health because of its carcinogenic and mutagenic behaviors. The purpose of this study was to determine the level of 6 PAHs(Fluoranthene, Pyrene, Benzo[a]anthracene, Chrysene, Benzo[b]fluoranthene, and Benzo[a]pyrene) as well as 10 inorganic elements(Cr, Na, K, Zn, Pb, Fe, Cu, Ti, Al and Cd) in the ambient PM-10. The total of 115 samples had been collected from February, 1996 to June, 1996 on quartz fiber by a PM-10 high volume air sampler near the Yong-Tong Apartment complexes. A statistical analysis was performed for the PAHs and inorganic elements data set using a principal component analysis in order to identify qualitatively the potential sources of PM-10. A total of 6 principal components were separated by intensive data pretrement and transformation processes, such as soil, refuse incineration, oil burning, coal burning, field burning, vehicle emission sources. The results showed that PAHs were associated with various burning activities like refuse and field burning, coal burning, and oil burning emissions in the study area. These derived sources were well matched with the previously known source profiles in terms of compositonal order and level of measured species. The combination data set consisted of both organic and inorganic species might provide more powerful source signature and might increase the number of potentially derived sources than PAHs or inorganic data alone.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.37-43
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• 2005

Recently, many ships such as fishing boats, cargo ships, high speed ferry boats are visiting Mokpo harbor. In particular, many marine accidents rave been occurred at this area because of the narrow channel, a thick fog, the existing of the shallow waters etc. However there is no suitable ships' routeing system which takes account of today's traffic situations in this area. This study aims at the settling of hazardous factors to mitigate the danger to vessels in mokpo harbor and to secure the safety qf maritime environment.

• Journal of the Korean institute of surface engineering
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• v.42 no.4
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• pp.157-160
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• 2009

Many fundamental studies have been carried out regarding waste water and hazardous gas treatments technologies using the photolysis effect of $TiO_2$. However, a permanent use of $TiO_2$ particles immobilized using organic or organic-inorganic binders is impossible. In this study, Ni-$TiO_2$ composite coating was produced by electroless plating to trap $TiO_2$ particles in the Ni coating layer. The electroless plating was performed in the bath solutions with three different concentrations of $TiO_2$ particles : 10 g/l, 20 g/l, and 40 g/l. The surface and photolytic characteristics of the coating layer was investigated by the use of SEM, a scratch tester, and an UV-Visible spectrophotometer. The results showed that the amounts of immobilized $TiO_2$ particles and the photolytic rate of the coating increased with the initial content of $TiO_2$ particles in the electroless bath. In addition, the photolytic rate of the Ni-$TiO_2$ composite coating was remarkably promoted by etching process in 10% HCl solution.

• Journal of Food Hygiene and Safety
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• v.1 no.2
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• pp.121-131
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• 1986

Four types of restaurants in Seoul city area were aSsessed in terms of the sanitary conditions and practices, and the microbiological quality. Sanitary check-lists were developed to evaluate the sanitary condition of sampled restaurants. Subjective samples were randomly selected based on the distribution factors of areas, types, and sizes. Microbiological tests on foods, equipments, and utensils were done according to standard procedures and included total plate count and coli forms. Singnificant differences among types or sizes were determined by using one-way analysis of variance. Correlation coefficients were calculated to determine significant relationships between sanitary scores and microbiological counts. The results of the study are summarized as follows: 1) Sanitary condition of kitchen and dining areas as well as the sanitary practices of employees were evaluated as the unsatisfactory state with potentially hazardous practices observed. 2) The microbiological quality of food items with high cooking temperature was in good condition, but most food items showed high levels of microbiological counts mainly due to the improper food handling practices of employees. 3) The sanitary conditions of equipment and utensils which were used at preparation and cooking phases, and food containers which were used at the serving phase, were crucial. Serveal guidelines were suggested for the improvement of the working environment as well as the food Quality.

• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.98-104
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• 2004

When a straight-in landing from an instrument approach using ILS or VOR/DME is not possible or desirable because of topographical reason or bad weather, a circling approach maneuver is initiated by the pilot to align the aircraft with a runway for landing. Visual contact with the runway is necessary while conducting a circle to land maneuver. This research is to develop a new warning system based on a convention marker system which alerts pilots to watch out for exceeding the circling approach area. The airborne system also uses the same receiver unit without any new installations. The objective of this research is to design and develop a Yagi antenna in a special form. The research includes computer simulations to determine the size of antenna radiation pattern and to compute an expected flight path in case of alarm to validate effectiveness of the system.

• Journal of Convergence for Information Technology
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• v.8 no.4
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• pp.121-126
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• 2018

We are developing a hazard map creation support system for historical local towns. Our system aims at collecting the unique information received from residents and raising resident's consciousness to disasters by recording hazardous locations where residents feel danger in case of disasters. In this paper, we examine the hazard information of the area collected by the residents themselves in using the system. While exchanging opinions, the residents review the validity and completeness of the information gathered by walking around the area. We also consider how to integrate and share it throughout the region. We found that it was possible to gather regional hazard information from the viewpoint of residents in addition to high coverage for each district. Also, by sharing information at the review meeting, the residents were able to newly know the hazard information of other districts that they did not know before. This shows the usefulness of residents to share the dangerous information while examining each cause across the different districts.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.269-281
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• 2021

Land creeping is the imperceptibly slow, steady, downward movement o f slope-forming soil or rock. Because creep-related failures occur frequently on a large scale without notice, they can be hazardous to both property and human life. Korea Forest Service has operated the prevention and response system from land creeping which has been on the rise since 2018. We categorized and proposed three survey steps (e.g., preliminary, regional, detailed) for investigation of creeping susceptibility site with a focus on geophysical mapping of a selected test site, Yongheung-dong, Pohang, Korea. The combination of geophysical (dipole-dipole electrical resistivity tomography and reciprocal seismic refraction technique, well-logging), geotechnical studies (standard penetrating test, laboratory tests), field mapping (tension cracks, uplift, fault), and comprehensive interpretation of their results provided the reliable information of the subsurface structures including the failure surface. To further investigate the subsurface structure including the sliding zone, we performed high-resolution geophysical mapping in addition to the regional survey. High-resolution seismic velocity structures are employed for stability analysis because they provided more simplified layers of weathering rock, soft rock, and hard rock. Curved slip plane of the land creeping is effectively delineated with a shape of downslope sliding and upward pushing at the apex of high resistive bedrock in high-resolution electrical resistivity model with clay-mineral contents taken into account. Proposed survey steps and comprehensive interpretation schemes of the results from geological, geophysical, and geotechnical data should be effective for data sets collected in a similar environment to land-creeping susceptibility area.