• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.2
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• pp.212-219
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• 2019

This study was conducted to investigate marine algal community characteristics and the status of barren ground in the summer at study sites on Jeju Island, Korea. Sampling was carried out from July to September 2017 using a qualitative and quantitative survey (including coverage of non-geniculated coralline algae and density of grazer) by scuba diving. A total of 121 species were identified, including 11 (9.1 %) green algae, 24 (19.8 %) brown algae, and 86 (71.1 %) red algae. Hyeongjeseom had the greatest diversity, with 60 species, and Harye the least, with 18 species. The mean biomass at the study sites was $1,503.0g{\cdot}m^{-2}$, while the mean for the neighboring islets ($3,268.7g{\cdot}m^{-2}$) was higher than that of the main island ($914.7g{\cdot}m^{-2}$). Also, dominant species was identified: Sargassum macrocarpum at the neighboring islets, and Ecklonia cava at the main island, with differences showing not only in biomass but also species composition. In conclusion, the marine algal community status in summer at the study sites was evaluated based on the algal community characteristics (species composition, biomass, biomass ratio of kelp species), coverage of non-geniculated coralline algae, and density of grazer. As a result, both Hyeongjeseom and Marado require preservation and management to maintain their excellent marine algal communities, and other sites on the main island require the creation and/or restoration of marine algal communities. In addition, as the generation of barren ground accelerates, it is urgent not only to grasp existing monitoring research but also to identify the status of the marine algal community where it is not known at present.

• Safety and Health at Work
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• v.11 no.4
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• pp.509-516
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• 2020

Background: Meta-analyses have shown firefighters to be at an increased risk of several cancer types. Occupational carcinogen exposure may explain these increased risks. This study aims to describe Norwegian fire departments' work conditions from 1950 until today, focusing on factors relevant for potential occupational carcinogen exposure. Methods: With the help of a reference group, we developed a questionnaire on topics related to occupational exposure to carcinogens for the period 1950-2018. Selected Norwegian fire departments provided department-specific responses. Results: Sixteen departments, providing fire services for 48% of the Norwegian population as of 2019 and mainly consisting of professional firefighters, responded to our questionnaire. The introduction of synthetic firefighting foams, more regular live fire training, the introduction of chemical diving, and a higher number of diesel-driven fire service vehicles were identified as changes thought to increase exposure to occupational carcinogens. Changes thought to decrease exposure included the switch from negative to positive pressure self-contained breathing apparatuses, the use of self-contained breathing apparatuses during all phases of firefighting, the use of ventilating fans during firefighting, increased attention to flammable materials used during live fire training, increased attention to handling and cleaning of turnout gear and other equipment, and installment of exhaust removal systems in apparatus bays. Conclusion: Norwegian fire departments' work conditions have seen several changes since 1950, and this could influence firefighters' occupational carcinogen exposure. A peak of carcinogen exposure may have occurred in the 1970s and 1980s before recent changes have reduced exposure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4403-4410
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• 2011

The purpose of this study was to investigate on the safety knowledge level, and to identify the factors that affect the safety knowledge according to general characteristics of scuba divers. This research design was a descriptive study. Data of 179 scuba divers were collected from October 17, 2010 to June 17, 2011. Data were analyzed by SPSS PASW statistics 18.0 program. The mean score of safety knowledge related to diving was 2.07(${\pm}0.54$)(score range was 1~4). The highest score was safety knowledge to cope with the cold($2.42{\pm}0.64$점). The lowest score was safety knowledge for hyperexpansion of lungs. In the results of multivariate regression analysis after variable selection, Adjusted $R^2$ value was 0.567. The model fit was 56.7%. The factors that affect the safety knowledge were age(${\leqq}29$ years), equipment(all purchase, some lease), motivation(job), participation period(${\leqq}11$ months) and frequency(once a month)(p<.05, p<.001). It is necessary to develop and conduct the educational program for scuba divers safety at country level.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.4
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• pp.179-187
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• 2001

In recent years, the switching source devices have the advantage of small, light and high reliability with the high-frequency. But, high-frequency switching has disclosed disadvantage of result from stress and turn-on and turn-off peak losses at the switching instant. Accordingly, in this paper propose ZVS-HB type high-frequency resonant DC/DC converter using soft switching technique (Zero-Voltage-Switching, Zero-Current-Switching) with safety operating of circuit at diving on inductive zone, through the circuit design example using the capacitor $C_3,\;C_4$ with soft switching function and division characteristic of resonant Capacitor C, $C_1,\;C_2$, and, the characteristic analysis of circuit is generally described using normalized parameters. Also, this paper certified a rightfulness of characteristic analysis in comparison with a theoretical values and a experimental values obtain from experiment using MOSFET.

• The Korean Journal of Emergency Medical Services
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• v.18 no.2
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• pp.45-58
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• 2014

Purpose: This study aimed to investigate the level of knowledge and education regarding basic life support (BLS) among scuba divers. Methods: Data collected from 125 scuba divers in Jeju-do were subjected to frequency, t-test, ANOVA, and Chi-square analyses using the SPSS 18.0 program. Results: 42.1% of the subjects was trained BLS for more than an hour less than 4 hours, and 52.6% of the subjects was trained BLS for less than 3 months in scuba diving institutions. Statistically significant difference was observed in the competence for performing cardiopulmonary resuscitation during BLS education according to gender and age further regarding the necessity of BLS education, significant difference was observed with respect to age, job, academic background, monthly income, and participation period of scuba divers. The divers wished to learn cardiopulmonary resuscitation (72.8%), medical first aid (8.0%), and measures to be taken in cases of trauma (8.0%). The knowledge score for BLS among scuba divers was significantly different depending on the gender, age, marital status and frequency of participation. Conclusion: It is necessary to develop and implement a safety education program for scuba divers.

• Safety and Health at Work
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• v.8 no.4
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• pp.386-392
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• 2017

Background: Fire service workers often implement multiple duties in the emergency conditions, with such duties being mostly conducted in various ambient temperatures. Methods: The aim of the current study was to assess the firefighters' physiological responses, information processing, and working memory prior to and following simulated firefighting activities in three different hot environments. Seventeen healthy male firefighters performed simulated firefighting tasks in three separate conditions, namely (1) low heat (LH; $29-31^{\circ}C$, 55-60% relative humidity), (2) moderate heat (MH; $32-34^{\circ}C$, 55-60% relative humidity), and (3) severe heat (SH; $35-37^{\circ}C$, 55-60% relative humidity). It took about 45-50 minutes for each firefighter to finish all defined firefighting activities and the paced auditory serial addition test (PASAT). Results: At the end of all the three experimental conditions, heart rate (HR) and tympanic temperature (TT) increased, while PASAT scores as a measure of information processing performance decreased relative to baseline. HR and TT were significantly higher at the end of the experiment in the SH ($159.41{\pm}4.25beats/min$; $38.22{\pm}0.10^{\circ}C$) compared with the MH ($156.59{\pm}3.77beats/min$; $38.20{\pm}0.10^{\circ}C$) and LH ($154.24{\pm}4.67beats/min$; $38.17{\pm}0.10^{\circ}C$) conditions (p < 0.05). There was no significant difference in PASAT scores between LH and MH (p > 0.05). Nonetheless, there was a measurable difference in PASAT scores between LH and SH (p < 0.05). Conclusion: These consequences demonstrate that ambient temperature is effective in raising the physiological responses following firefighting activities. It is therefore argued that further increase of ambient temperature can impact firefighters' information processing and working memory during firefighting activity.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.2
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• pp.141-152
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• 2022

As a method to understand the ecological habits around the artificial reef, various reports such as fishing gear survey, diving, sound survey, underwater CCTV and camera, etc. are reported. Among them, the sound survey method is carried out by installing an acoustic system on the ship and can be investigated regardless of the marine environment such as time constraints and turbidity. Such method, however, takes a lot of manpower and time as the ship travels at a constant speed. Investigations around artificial reefs are being conducted in an artificial way, and a lot of time and labor are consumed as such. Maritime buoys have been operated for various purposes such as route signs, weather observation, marine environment monitoring and defense monitoring for navigation safety in the past, but studies on monitoring systems for ecological habits and distribution of fish using marine buoys are remarkably insufficient. Therefore, this study aims to develop a system that allows users to directly monitor fish group detector data by estimating the distribution of fish groups around artificial reefs and using wireless communication at sea. In order to confirm the suitability of the maritime buoy used in this study, it was operated to compare data using LTE-equipped buoys capable of wireless communication and a data logger-type system buoy. Data transmission of buoys capable of LTE communication was carried out in a 10-minute ON, 10-minute OFF method due to the limitation of the power supply capacity, and data of the data logger-type buoy received full data. We compared and analyzed the data received from the two fish detectors. It is expected that real-time monitoring of the wireless buoy detection device using LTE will be possible through future research.

• Korean Journal of Culture and Social Issue
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• v.13 no.4
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• pp.101-112
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• 2007

We investigated the influences of 'Circumstance Insensibility', 'Unsafe Driving', 'Incautious Driving', and 'Self-efficacy of Driving', consisting of driving confidence level, on traffic accidents. 1055 drivers conducted Driving Confidence Level Questionnaire, items about their dangerous driving experience and traffic accidents. Among them, after checking the missing items, we analyzed data of 998 drivers. As a result, we found the relation between driving confidence levels and traffic accidents. Specially, 'Circumstance Insensibility' and 'Unsafe Driving' influenced traffic accidents. However 'Circumstance Insensibility' had negative effects, the other side 'Unsafe Driving' had positive effects on traffic accidents. This result means each factor of driving confidence levels have different relation with traffic accidents. 'Incautious Driving' and 'Self-efficacy of Driving' didn't have any effects on traffic accidents in this research. In future, it should be investigated 'Incautious Driving' and 'Self-efficacy of Driving'.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.175-185
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• 2020

Quantitative and qualitative surveys were conducted during scuba diving activity between May 2017 and June 2017 in order to analyze spring marine algal community structure at Gijang-gun, Busan. A total of 121 species including 13 (10.7 %) Chlorophyta, 18 (14.9 %) Phaeophyta, and 90 (74.4 %) Rhodophyta were identified. The species count in the subtidal zone (110 species) was twice as high as in the intertidal zone (56 species). In terms of regions, 88,76, and 75 species were found in Mundong, Gongsu, and Daebyeon, respectively. Mean biomass for the whole study area was 1,501.5 g·m^-2, higher for the subtidal zone (1,869.4 g·m^-2) than for the intertidal zone (1,133.5 g·m^-2). Mean biomass by region values were 2,234.0 g·m^-2, 1,228.1 g·m^-2, and 1,044.4 g·m^-2 for Mundong, Gongsu, and Daebyeon, respectively. Ulva australis, Sargassum thunbergii, and Corallina pilulifera had high biomass in the intertidal zone, while Sargassum macrocarpum, Undaria pinnatifida, and Phycodrys fimbriata had high biomass in the subtidal zone. The composition ratio of marine algal functional forms suggests that the entire study area had 'Low' status, and all sites fell within 'Low' to 'Moderate' status. Results indicate that opportunistic species are widely distributed throughout the Gijang-gun coast, hence potential effects of disturbance and environmental pollution should be considered. Seaweed farming in particular - a major activity along the Gijang-gun coast -, together with effects of other anthropogenic activities such as national fishing port development and the coastal improvement project, could have long-term effects on marine algal communities. Therefore, long-term monitoring and management plans for marine algal communities will be required.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.2
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• pp.159-168
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• 2019

This study was designed to investigate the physiological response of humans to alcohol during underwater activity and to complete related risk analysis. After comparing human responses to alcohol during underwater activity, we analyzed physiological changes and risk level using a new risk analysis method developed in this study, 'Risk Assessment and Analysis (RAA)'. RAA is a modified method based on an internal control frame work. It has 3 steps, the first of which is to analyze risk correlation. The second step is to quantify risk and build a risk database. The last step is to analyze the diagramed risk map. Using RAA, the risk levels of alcohol use underwater were calculated and diagramed. The diagramed risk map was then used to analyze the difference between risk levels underwater before and after alcohol use. As a result, it was found that risk level underwater increased after alcohol use. This study shows alcohol use increases the ratio of high risk groups during underwater activity. It also indicates that risk levels can be quantified according to the likelihood and impairment scale, which can potentially help in identifying high risk groups for intensive management underwater.