• Journal of Environmental Science International
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• v.25 no.4
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• pp.505-516
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• 2016

With the development of nanotechnology, nanomaterials are used in various fields. Therefore, the interest regarding the safety of nanomaterial use is increasing and much effort is diverted toward establishment of exposure assessment and management methods. Occupational exposure limits (OELs) are effectively used to protect the health of workers in various industrial workplaces. This study aimed to propose an OEL for domestic multi-walled carbon nanotubes (MWCNTs) based on animal inhalation toxicity test. Basic procedure for development of OELs was examined. For OEL estimation, epidemiological study and quantitative risk assessment are generally performed based on toxicity data. In addition, inhalation toxicity data-based no observed adverse effect level (NOAEL) and benchmark dose (BMD) are estimated to obtain the OEL. Three different estimation processes (NEDO in Japan, NIOSH in USA, and Baytubes in Germany) of OELs for carbon nanotubes (CNTs) were intensively reviewed. From the rat inhalation toxicity test for MWCNTs manufactured in Korea, a NOAEL of $0.98mg/m^3$ was derived. Using the simple equation for estimation of OEL suggested by NEDO, the OEL of $142{\mu}g/m^3$ was estimated for the MWCNT manufacturing workplace. Here, we used test rat and Korean human data and adopted 36 as an uncertainty factor. The OEL for MWCNT estimated in this work is higher than those ($2-80{\mu}g/m^3$) suggested by previous investigators. It may be greatly caused by different physicochemical properties of MWCNT and their dispersion method and test rat data. For setting of regulatory OELs in CNT workplaces, further epidemiological studies in addition to animal studies are needed. More advanced technical methods such as CNT dispersion in air and liquid should be also developed.

• Korean Journal of Occupational Health Nursing
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• v.9 no.1
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• pp.5-17
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• 2000

The occupational health nursing guideline for primary care was developed by the Korean Academic Society of occupational health nursing and the organization for occupational health nurses (currently known as the Korean Association of Occupational Health Nurses) in 1993. Since then, there have been many changes in the health care environment and job performance of occupational health nurses. Appropriate revisions are necessary of the guidelinea based on this background. The purpose of this study was to describe the use of the occupational health nursing guideline for primary care and to analyze the characteristics of primary care activities by occupational health nurses. The questionnaire was mailed to 150 occupational health nurses(OHNs) with the response rate of 64%. The results can be summarized as follows; 1. 65.6% of OHNs have been using the guideline for primary care and 75.9% of them agreed that the guideline was be helpful for their job. 2. Common symptom care, emergency care and chronic illness care were more frequently implemented than occupational disease care by OHNs. In manufacturing industries, emergency care was more frequently implemented than chronic illness care in contrast to the service industries. 3. Most frequent common symptoms treated by OHNs were indigestion, diarrhea, abdominal pain, headache, and coughing. In the case of chronic illness, OHNs more frequently treated diseases of the gastro-intestinal system, skin and sensory organs, and the respiratory system. Emergency care for bruises, burn, and abrasions was more frequently provided. VDT syndrome was the most common occupational disease cared by OHNs in manufacturing and service industries. 4. OHNs prescribed the medicine for external application more frequently than internal medicine. Remedy for colds, analgesics, vitamins, and digestives were more frequently used. From these results, we suggest that the guideline should be revised to emphasize the activities consisting problem finding such as health assessment, physical examinations, monitoring and screening, and to renew the drug list in the range of over- the counter medication (OTC). In the future, the guideline will include the strategies for the role as the case manager.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.449-455
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• 2009

The increase of industrial carbonic dioxide emissions has accelerated the carbonation of reinforced concrete structures, which drops off their durability. Although advanced countries have already taken safety control measures against the carbonation of RC structures, it is still difficult now to accurately predict the actual carbonation depth. Additionally, it requires much time and efforts. Recently, it is possible to get the data more rapidly through accelerated carbonation test with the $CO_2$ concentration of 100%. In this paper, the carbonation test results obtained by two test methods such as the normal carbonation test method and the accelerated carbonation test method, were compared to investigate the carbonation characteristics of fly ash concrete. The accelerated carbonation test on concrete specimens with the pre-curing age of 180 days was also carried out to examine the carbonation characteristics of fly ash concrete at long-term age. Consequently, fly ash concrete at early age was vulnerable to carbonation and however, its carbonation resistance at long-term ages was improved compared with OPC concrete.

• Journal of the Korean GEO-environmental Society
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• v.21 no.6
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• pp.13-17
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• 2020

In the era of the fourth industrial revolution, drones are being used in various civil engineering fields. Currently, the construction and maintenance of slopes are generally managed by manpower. This method has a risk of safety accidents, and it is difficult to accurately evaluate the slope because it is difficult to secure the vision. In this paper, the effects of RTK and GCP on the 3D model of the slope were studied by using digital images taken by the drone. GNSS coordinates were measured for nine points to compare the quality of the slope 3D model, three points of which were used as the check points and the remaining points were used as GCPs. When making the 3D model of the slope using high-accuracy geotagging images using RTK, it was found that the error at the check point decreases as the number of GCP increases. Even if GNSS was used, it was found that the error at the check points of the 3D slope model was not significant when the GCPs were applied. However, it was found that even if high-accuracy geotagging images are used using the RTK module, a significant error occur when the 3D slope model is created without applying GCPs. Therefore, it can be stated that GCP must be applied to create the 3D slope model in which information about the height as well as plane information is important.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1056-1063
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• 2012

Recent rapidly growth in nanotechnolgies is promised novel benefits through the exploitation of their unique industrial and biomedical applications. With increasing utilization of nanomaterials in consumer products, the potential release of nanomaterials into the environment and their impacts on the ecosystem and human health have been the issues of concern. Nanomaterials that was exposed unintentionally in environment might be accumulated in various environmental media, and finally it will be influenced to human and ecosystems. Therefore, it is important to understand the fate and behavior of nanoparticles for understanding effects on environmental media (air, water, and soil phase). Therefore, in this work, we investigated the several cases for environmental exposure of nanomaterials and suggested the direction of further research. In workplace, exposure to air media is dominant, but finally waste and wastewater was moved to the water and soil phase. In addition, we found the existing sewage treatment plant was not suitable to remove completely nanomaterials in wastewater flow. To deeper study, environmental monitoring tool must be developed additionally and we suggested the several analyzing method for aged and pristine physicochemical properties of nanomaterials exposed into environmental media. This review for nanomaterials' exposure to environmental media will be helpful to investigate the environmental fate of nanomaterials and define the suitable treatment method for nano-waste.

• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.139-146
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• 2004

Recently, interest on the performance of the construction temporary equipment have been greatly increased. Since the application of the 'Performance Test Code' for the equipment in 1992 according to the Industrial Safety and Health Act, a basic study of Steel Pipe Supports have been carried out for the last 2 years based on the Performance Test Results. The present code specification for the Steel Pipe Supports and research status are introduced. So far, total 849 specimen have been examined on their outer and inner pipe's length, thickness, their overlapping length, and their load carrying capacities. The test was conducted separately into two groups - used and new equipment, and it was found that the used ones revealed a decrease on their load carrying capacity, almost $10\%$ compared to the new ones. Considering this fact, it is strongly recommended to ensure the quality of the equipment before use at the jobsite. First of all, based on this basic investigation, the statistical values on the Steel Pipe Supports are suggested and further analysis on the effect of each component is in progress. It is, however, expected that this report can be used as a basic information on the Steel Pipe Supports.

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.777-783
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• 2006

This study has focused on the possibility for recycling of tailings from the Sangdong tungsten mine as powder(TA) of self-compacting concrete(SCC). The experimental tests for slump-flow, time required to reach 500 mm of slump flow(sec), time required to flow through V-funnel(sec) and filling height of U-box test(mm) were carried out in accordance with the specified by the Japanese Society of Civil Engineering(JSCE). The results of this study, slump-flow of SCC was satisfied a prescribed range. And time required to reach 500 mm of slump flow(sec) and time required to flow through V-funnel(sec) decreased with increasing replacement of TA. But filling height of U-box test(mm), replacement of TA up to 30% were satisfied a prescribed range. The mechanical properties including compressive strength, splitting tensile strength and elastic modulus were checked with the requirements specified by Korean Industrial Standards(KS). The compressive strength of SCC decreased with increasing replacement of TA, splitting tensile strength and elastic modulus were similar to those of normal concrete. The fundamental durability was reviewed through the dry shrinkage rate and accelerated carbonation tests. As the result dry shrinkage rate and accelerated carbonation depth increased with increasing replacement of TA.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.299-306
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• 2016

In this study, new hydroxyapatite powder surface composites were investigated for protective effects against ultraviolet rays. Hydroxyapatite (HAp) is biocompatible and does not cause nebula phenomenon on skin. We investigated the surface modification of hydroxyapatite to improve UV block and skin usage. Dimethicone, lauroyl lysine, triethoxycaprylylsilane and silica were used as coating agents for the surface modification of HAp. To prepare the composite complex of the modified surface, the dimethicone, lauroyl lysine and triethoxycaprylylsilane were prepared by a dry process, and silica by a hydrothermal synthesis method. The HAp-silica was chosen as the best composite powder when measuring its sun protection levels. We investigated the characteristics of the surface of HAp-silica by SEM, particle size analyzer and energy dispersive spectrometry (EDS). Additionally, the stability in the formulation, UV block effect, and safety in BB creams were investigated. In conclusion, HAp-silica prepared by the modification of HAp complex surface improved the skin usage and UV block effect by enhancing the white cloudy phenomenon. These results indicate that HAp-silica may be used for UV block cosmetics.

• Proceedings of KOSOMES biannual meeting
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• 2004.11a
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• pp.109-115
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• 2004

Hydrocyclone has been widely used for the solid-liquid separation in many industrial sites because of its comparatively preferable applications that can be applied to wide-range particle sizes. If seawater with impurities flows through pumps or heat exchanger, it might cause an decrease in efficiency of cooling system. In this paper, we have suggested some methods of separating impurities from seawater in the cooling system by using a Hydrocyclone. The effects of design factors as solid concentration, cyclone inlet pressure, flow rate and diameter of underflow on the separating performance of the Hydrocyclone were investigated The results from this study are summarized as follows: 1) In proportion to the decrease of solid concentration, the efficiency of solid-liquid separation is improved 2) According as the cyclone inlet pressure increases the efficiency of separation is improved Conclusively, this research suggested that the Hydrocyclone will be used as a pre-treatment system of cooling water in machines, and eventually prevent unexpected accidents in engine systems.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.46 no.3
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• pp.219-229
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• 2020

Recently, since atopic dermatitis is sensitive to skin irritation, it has been suggested that the development of a patch that can effectively exhibit adhesion and absorption to a specific local area while minimizing skin irritation, and capable of appropriate drug release should be given priority. In this study, we tried to develop a hydrogel patch that minimizes skin irritation, adheres effectively to a specific area, and promotes absorption. The atopic patch was formulated into a super-absorbent hydrogel sheet using a freeze drying method. Cell viability assay was carried out using keratinocytes (HaCaT cell) and fibroblasts (L929 cells). In order to investigate the physical properties, FT-IR, FE-SEM, porosity analysis and swelling behavior were investigated. As a result, the newly prepared HA-Dex hydrogel patch was verified by biocompatibility and physical evaluation. In addition, the manufactured hydrogel patch has sufficient moisture absorption capacity and can relieve itching of atopic skin, and is expected to be applied to various drug delivery products for the treatment of atopic dermatitis in the future.