• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.655-662
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• 2016

This study proposes that a diving supervisor, who can perform the role of both a field manager and a supervisor, be introduced in the national qualification system. The goal was achieved by surveying the general status of the commercial diving sector, including the statistics of an underwater construction company, commercial diving equipment operation condition, diver working hours, diver supply and demand status, and underwater construction market size. The national qualification and national competency standard (NCS) systems were also analyzed to deduce the role definition and work scope of the diving supervisor. Consequently, the following proposition is made: the diving supervisor should be an "on-site manager with the highest job skill in the commercial diving field, who can perform the on-site process management as well as guide, supervise, and educate project participants and serve as an intermediary between the contractor and the workers." The responsibilities of the diving supervisor are proposed to include "diving planning and operation of the diving team," "diving with surface-supplied air and mixed-gas diving system," "chamber operation," "underwater construction," and "ship salvage." The persistent issues in commercial diving sectors, such as diver career development, management, and worker supervision, are expected to be largely resolved with the introduction of this qualification.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.105-108
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• 2011

The increased concern for the security of the oil supply and the negative impact of fossil fuels on the environment, particularly greenhouse gas emissions, has put pressure on society to find renewable fuel alternatives. Compared to the traditional biofuel, ethanol, higher alcohols offer advantage as gasoline substitutes because of their higher energy density and lower hygroscopicity. For this reason, microbial fermentation is known as potential producers for sustainable energy carriers. In this study, bacterial responses including cellular and molecular toxicity were studied in three different microorganisms, such as Escherichia coli, Clostridium acetobutylicum, and Saccharomyces cerevisiae. In this study, it was analyzed specific stress responses caused by ethanol and buthanol using four different stress responsive genes, i.e. fabA, grpE, katG and recA. The expression levels of these genes were quantified by semi-quantitative reverse transcription-PCR. It was found that four genes have shown different responsive patterns when E. coli cultures were under stressful conditions caused by ethanol and buthanol, respectively. Therefore, in this study, the stress responsive effects caused by these alcohols and the extent of each stress response can be analyzed using the expression levels and patterns of different stress responsive genes.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.2
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• pp.147-158
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• 2016

Objectives: The objective of this study was to evaluate the assessment of exposure to welding fume and heavy metals among construction welders. Methods: Activity-specific personal air samplings(n=206) were carried out at construction sites of three apartment, two office buildings, and two plant buildings using PVC(poly vinyl chloride) filters with personal air samplers. The concentration of fumes and heavy metals were evaluated for five different types of construction welding jobs: general building pipefitter, chemical plant pipefitter, boiler maker, ironworker, metal finishing welder. Results: The concentration of welding fumes was highest among general building pipefitters($4.753mg/m^3$) followed by ironworkers($3.765mg/m^3$), boilermakers($1.384mg/m^3$), metal finishing welders($0.783mg/m^3$), chemical pipefitters($0.710mg/m^3$). Among the different types of welding methods, the concentration of welding fumes was highest with the $CO_2$ welding method($2.08mg/m^3$) followed by SMAW(shield metal arc welding, $1.54mg/m^3$) and TIG(tungsten inert gas, $0.70mg/m^3$). Among the different types of workplace, the concentration of welding fumes was highest in underground workplaces($1.97mg/m^3$) followed by outdoor($0.93mg/m^3$) and indoor(wall opening as $0.87mg/m^3$). Specifically comparing the workplaces of general building welders, the concentration of welding fumes was highest in underground workplaces($7.75mg/m^3$) followed by indoor(wall opening as $2.15mg/m^3$). Conclusions: It was found that construction welders experience a risk of expose to welding hazards at a level exceeding the exposure limits. In particular, for high-risk welding jobs such as general building pipefitters and ironworkers, underground welding work and $CO_2$ welding operations require special occupational health management regarding the use of air supply and exhaust equipment and special safety and health education and fume mask are necessary. In addition, there is a need to establish construction work monitoring systems, health planning and management practices.

• Korean Journal of Ecology and Environment
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• v.46 no.3
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• pp.409-418
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• 2013

Global warming due to climate change is a problem facing the entire world. Several factors, such as $CO_2O$ concentration, level of warming, soil temperature, precipitation, water content of soil and denitrification by denitrifying bacteria influence the emission of nitrous oxide ($N_2O$) from soil. In this study, we investigated nitrous oxide emissions from the soil of two wetlands, Jilmoineup in Mt. Odae and Moojechineup in Mt. Jungjok, according to temperature change. Soil collected in Jilmoineup in July showed increasing $N_2O$ emissions as temperature increases, but did not show any significant differences at $10^{\circ}C$ (p<0.05). Soil of $15^{\circ}C$ and $20^{\circ}C$ showed increasing pattern of $N_2O$ emissions until 24 h. After that, however, there was no difference in temperature. Overall, $N_2O$ emissions showed significant differences according to temperature (p<0.05). Soil collected from Moojechineup in July showed increasing $N_2O$ emissions according to temperature increase, but did not show any significant differences at $10^{\circ}C$ (p<0.05) as was the case for Jilmoineup soil. On the other hand, two wetland soils showed a slight increase of $N_2O$ emissions by additional nitrogen supply, but did not show any significant differences in the presence of nitrogen or between nitrogen sources. In conclusion, increasing temperature the wetland soil increased the emission of $N_2O$, which is a known greenhouse gas. In order to more clearly identify $N_2O$ emissions, various subsequent studies such as the influence and correlation of several factors are required.

• Fire Science and Engineering
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• v.31 no.2
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• pp.61-73
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• 2017

The Fukushima Nuclear Disaster in 2011 and California Power Failure in 2001 are examples of the importance of the power plant safety management that caused huge national loss with a power-related mass casualty incident. In a situation where humans cannot live without electricity, efforts to strengthen the systematic firefighting safety management in power plants that produce electricity with large amounts of hazardous materials as fuel, such as nuclear energy, coal and gas, are essential to protect life and prevent property loss and stable economic growth from fire explosion accident or radiation leak due to the negligence of safety management and natural disasters such as earthquakes, which has recently become an issue. This study examined the operating situation of firefighting safety management in power plants with firefighting officials employed by five power generation companies including Korea Southern Power Co., Ltd. and Korea Hydro & Nuclear Power Co. Ltd., which are in charge of the domestic power supply. As a result, for the systematic firefighting safety management of power plants, improvement plans were drawn, including the development of an effective business manual and a comprehensive management system, the substantiality of firefighting safety education, and the strengthening of seismic designs to prepare for earthquakes.

• Journal of the Korean Home Economics Association
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• v.28 no.4
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• pp.65-86
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• 1990

Living conditions of the rural elderly were assessed in terms of clothing behavior, health and nutritional status, housing and envioronmental condition, and psychological adjustment. The subjects were eighty individuals over sixty residing in the rural community of Iksan-kun, Chollabukdo. The interview method using questionnaires, direct measurement, and observation was used for this study. Data were compared with those obtained from a previous study of the elderly residing in an urban area. Clothing behavior showed that the elderly residing in the rural community were more concerned about plain and conservative design of clothes than their urban counterparts. Special protective clothes for cropdusting with agricultural chemicals had not been prepared. The following urgent needs were pointed out: development and supply of agricultural chemical protective clothing and development and education of appropriate washing and clothing care methods. The health status of the elderly was generally good, but poor eating habits were found more frequently in the rural elderly than among the urban dwellers. Several dietary nutrient intakes were insufficient. Contrasting the urban elderly with the rural group, it was found that the urban group lacked sufficient vitamin A and vitamin C and the urban women had insufficient calorie whereas the rural group was deficient in protein, vitamin A, calorie, and fat. A significant relationship was found between dietary nutrient intake and health index, food habit points, self recognized health status, meal satisfaction, and economic status. Urgent needs of the development of a nutrition education program for the elderly were pointed out. Most of elderly residing in the surveyed rural communities were living alone or with their spouse only, therefore only one room was used among the three or four available rooms. Most of the rural elderly were living either in a traditional Korean house built with differing floor levels or in a modified Korean style house. Minimal modernization had been made for kitchen facilities such as sink and gas range or for heating facilities with the briquette boiler. However, sanitary space such as lavatory and bathroom had not been remodeled. A housing welfare program for rural communities should be implemented at the national level. The comparison of psychological characteristics of the rural elderly with their city counterparts revealed that the rural elderly have a more stable psychological status and optimistic attitude than those living in a city. However, it was found that most of the elderly did not have any future plan. Community programs for the elderly including hobbies or leisure activities or education programs to generate close interpersonal relationships with their children should be developed and provided.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.967-972
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• 2003

The inner-diameter 5 cm cold hollow cathode ion source was designed for the high current density and the homogeneous beam profile of ion beam. The ion source consisted of a cylindrical cathode, a generation part of magnetic field, a plasma chamber, convex type ion optic system with two grid electrode, and DC power supply system. The cold hollow cathode ion sources were classified into standard type (I), electron output electrode modified type (II). The operation of the ion source was done with discharge current, ion beam potential and argon gas flow rate. The modification of electron output electrode resulted in uniform plasma generation and uniform area of ion beam was extended from 5 cm to 20 cm. Improved ion source was evaluated with beam uniformity, ion current, team extraction efficiency, and ionization efficiency.

• Journal of the Economic Geographical Society of Korea
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• v.15 no.1
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• pp.77-94
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• 2012

The purpose of this study is to analyze the process of vertical fragmentation of regional industries in Korea using Revealed Comparative Advantage index (RCA) and Average Propagation Length (APL). First of all, the competitiveness in regional export and substitution of regional imports were strong in the Electricity, Gas, and Water supply sector in Gyeongnam, and consumer-oriented Manufacturing sector in Incheon, Gyeongnam, and Gwangju. The high values of the APL were also found in the regions with common similarity with respect to the industrial structure and the sectors with indirect effects. In addition, the industrial sectors with high quality of infrastructure, and endowed services tended to be located in the beginning of the production chain. FInally, since manufacturing and service sectors in Seoul has higher APL, they could lead the growth of other related industries as key sectors, in the production fragmentation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.900-905
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• 2016

The field of power system harmonics has been receiving a great deal of attention recently. This is primarily due to the fact that non-linear (or harmonic-producing) loads comprise an ever-increasing portion of what is handled at a typical industrial plant. The incidence rate of harmonic-related problems is low, but awareness of harmonic issues can still help increase offshore power plant system reliability. On the rare occasion that harmonics become a problem, this is either due to the magnitude of harmonics produced or power system resonance. This harmonic study used an electrical configuration for the offloading scenario of a Floating LNG (FLNG) unit, considering power load. This electrical network configuration is visible in the electrical network load flow study part of the project. This study has been carried out to evaluate the performance of an electric power system, focusing on the harmonic efficiency of an electrically driven motor system to ensure offshore plant safety. In addition, the design part of this study analyzed the electric power system of an FLNG unit to improve the safety of operation and maintenance.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.203-209
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• 2017

Research on condition monitoring and diagnosis of power facilities has been conducted to improve the safety and reliability of electric power supply. Although insulation diagnostic techniques for unit equipment such as gas-insulated switchgears and transformers have been developed rapidly, studies on monitoring of cables have only included aspects such as whether defects exist and partial discharge (PD) detection; other characteristics and features have not been discussed. Therefore, this paper dealt with PD characteristics against void sizes and positions, and with defect localization in XLPE cable. Four types of defects with different sizes and positions were simulated and PD pulses were detected using a high frequency current transformer (HFCT) with a frequency range of 150kHz~30MHz. The results showed that the apparent charge increased when the defect was adjacent to the conductor; the pulse count in the negative half of the applied voltage was about 20% higher than that in the positive half. In addition, the defect location was calculated by time-domain reflectometry (TDR) method, it was revealed that the defect could be localized with an error of less than1m in a 50m cable.