• Journal of Environmental Health Sciences
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• v.33 no.4
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• pp.283-292
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• 2007

Atmospheric concentrations of radon had been continuously observed in Seoul, Korea since December 1999, as a tracer for long-range transport of air pollutants from China continent to Korea. In order to study radon as a tracer of long-range transport, it is important to know information about the atmospheric distribution and variation of radon concentration and its time variation. Atmospheric radon concentration are measured with electrostatic radon monitor(ERM) at Hanyang University located in Eastern area of Seoul. Air sample is taken into a vessel of ERM, and alpha particles emitted by radon daughters $Po^{218}$ are detected with ZnS(Ag) scintillation counter. Hourly mean concentrations and hourly alpha counts are recorded automatically. The major results obtained from time series observation of atmospheric radon were as follows : (1) The mean of airborne radon concentration in Seoul was found to be $7.62{\pm}4.11\;Bq/m^3$ during December $1999{\sim}January$ 2002. (2) The hourly variation of radon concentrations showed the highest in 8:00AM ($8.66{\pm}4.22\;Bq/m^3$) and the lowest in 3:00AM ($6.62{\pm}3.70\;Bq/m^3$) and 5:00AM ($6.62{\pm}3.39\;Bq/m^3$). (3) the seasonal variation of radon concentrations showed higher during winter-to-fall and lower during summer-to-spring. (4) Correlation between airborne radon concentration and the meteorological factors were -0.21 for temperature, 0.09 for humidity, -0.20 for wind speed, and 0.04 for pressure. (5) The mean difference of airborne radon concentration between Asian dust ($5.36{\pm}1.28\;Bq/m^3$) and non-Asian dust ($4.95{\pm}1.49\;Bq/m^3$) phenomenon was significant (p=0.08). We could identify time series distribution of radon concentration related meteorological factors. In addition, radon can be considered a good natural tracer of vertical dispersion and long-range transport.

• Journal of Radiation Protection and Research
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• v.24 no.4
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• pp.187-193
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• 1999

The specific radioactivity concentrations in the coal fly ash obtained from heat producing stations in Korea were analyzed and its radiological hazard for reuse in construction purpose was evaluated. The concentrations of uranium isotopes in the real fly ash measured by TBP solvent extraction method and $\alpha$-spectrometer were found to be about 116.1 Bq $kg^{-1}$ for $^{238}U$, 5.01 Bq $kg^{-1}$ for $^{235}U$, and 121.2 Bq $kg^{-1}$ for $^{234}U$, respectively. The activity ratio of $^{234}U/^{238}U$, in the coal fly ash was in $1.04\;{\pm}\;0.03$, which is similar to that of uncontaminated Korean soil in natural conditions (1.14). The specific radioactivities of $^{226}Ra,\;^{232}Th,\;and\;^{40}K$ in the coal fly ash were also determined using $\gamma$-spectrometer with a HPGe detector The results showed that $^{226}Ra,\;^{232}Th,\;and\;^{40}K$ in the coal fly ash were in concentrations of $101.7{\sim}113.9$, $39.5{\sim}54.2\;and\;315.0{\sim}990.6$ Bq $kg^{-1}$, respectively. With the specific radioactivities obtained from $\gamma$-spectrometric measurements of the coal fly ash, its radiological hazard for reuse was evaluated. The result showed that the radioactivity of the coal fly ash was in permissible level.

• Geomechanics and Engineering
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• v.34 no.1
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• pp.69-86
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• 2023

To overcome the dilemma of the [BQ] method's inability to predict mountain tunnel support loads, this study is based on the Hoek-Brown criterion and previous results to obtain the connection equations from GSI scores to each parameter of the Hoek-Brown criterion and the link between the [BQ] scores and the GSI system. The equations were embedded in the Hoek-Brown criterion of FLAC6.0 software to obtain tunnel construction forecasts without destroying the in-situ stratigraphy. The feasibility of the secondary development of the Hoek-Brown criterion was verified through comparative analysis with field engineering measurements. If GSI > 45 with a confining pressure of less than 10 MPa, GSI has little effect on the critical softening factor while we should pay attention to the parameter of confining pressure when GSI < 45. The design values for each parameter are closer to the FLAC3D simulation results and the secondary development of the Hoek-Brown criterion meets the design objectives. If the Class V surrounding rock is thinned with shotcrete or the secondary lining is installed earlier, the secondary lining may act as the main load-bearing structure. The study may provide ideas for rapid prediction of mountainous tunnels in China.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.3
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• pp.334-341
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• 2016

Objectives: This study is aimed at examining radon exposure in offices and the factors that can influence the concentrations. Methods: Indoor radon concentrations in a total of 30 places were measured from January 18 to 21, 2016, targeting six buildings in Seoul with different completion years. The measurement was conducted according to the radon measurement guidelines for indoor air suggested by the Ministry of Environment. Results: As a result of comparing each average concentration, underground area concentration was $42.850{\pm}22.501Bq/m^3$, and that of the ground floors was $27.850{\pm}12.232Bq/m^3$, which was lower than the concentration in the underground areas and statistically significant (p=0.045). As a result of comparing the concentration according to whether or not outside air entered, the average concentration for ventilated areas was $24.876{\pm}11.833Bq/m^3$, and the average concentration for enclosed areas was $47.892{\pm}19.375Bq/m^3$. The concentration in ventilated areas was lower at a statistically significant level (p=0.001). Finally, as a result of the multiple regression analysis for evaluating the factors influencing radon concentration, only ventilation was significant (p=0.007). Conclusions: As a result of measuring radon in office buildings, there was no place that exceeding the recommended standard of the US EPA, but the concentration in poorly ventilated areas was measured to be high. An effort to manage radon concentration and reduce it through the improvement of ventilation systems, repeated measurement is necessary in the future.

• Journal of the Korean Geographical Society
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• v.42 no.4
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• pp.526-539
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• 2007

The purpose of this study is to investigate the influence of the Korean Wave on Chinese tourism to South Korea through a behavioral analysis of Chinese tourists in the general group package tours. China suppressed the needs of the Chinese people's geographical movement and imposed restrictions on information about the outside world with the use of a policy of "closure" for a long time. But since reforms and open-door policies were introduced in China, especially in the context of relaxation of control policies over Chinese outbound tourism after the mid-1990's, more and more Chinese make trips abroad including visits to South Korea. In this situation, the recent Korean Wave(especially, drama/film) describes the Korean national image by forming a bridge between fiction and reality and plays a pivotal role in broadening or reconstructing the geographical imagination of the Chinese people who have been historically isolated from the outside world. Although Chinese have imagined the Korean nationscape on the basis of geopolitical or economic factors in the past, they have currently broadened or reconstructed their geographical imagination to include socio-cultural factors related closely to the Korean way of life due to the recent Korean Wave. This newly constructed geographical imagination led by the Korean Wave functions as an important pulling factor in Chinese destination choices, affecting Chinese tourists' motivation formation and the recommendation of main attractions. The more influential the Korean Wave is on their destination choice, the more the respondents select the cultural factors in both their motivation for tourism to South Korea and their recommendations of tourism attractions to other people. Through the analysis results of both satisfaction and intention to revisit, the more influential the Korean Wave is on their destination choice, the higher is the degree of both satisfaction and intention to revisit. In other words, although Chinese tourism to South Korea is chiefly in the general group package tours, Chinese tourists who are influenced by Korean Wave on their destination choice have more attachment to(or affection for) Korea as a tourism destination. This result suggests that the Korean Wave affects qualitative change - that is, change of attitude - as well as quantitative change in Chinese demand for tourism to South Korea.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.52-57
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• 2004

In order to analyze key parameters of important radionuclides in dose evaluation model of decommissioning site, a sensitivity analysis was performed. This analysis assumed a resident farmer for an exposure scenario and 0.037Bq/g for the concentration of radionuclides. As a result of sensitivity analysis, the key parameters of radionuclides considered were the area of contaminated zone, external gamma shielding factor and indoor time fraction for Cs-137 and Co-60. The key parameters for C-14 were the environmental parameters and hydrological parameters of unsaturated zone. Also, the key parameter for Sr-90 was the density of contaminated zone.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3760-3768
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• 2015

This study was to examine the correlation of Personality and EEG. Personality test and EEG of the 40 team leader of a business enterprise were carried out at the same time and the correlation of test results were analyzed. Personality test was done by Big 5 and brain waves were measured by 2-Channel EEG System at Fp1 and Fp2. The analysis showed a positive correlation between the Big 5 agreeableness and SRQ(Self Regulation Quotient) relaxation status which is related with alpha rhythm, and showed a negative correlation between the Big 5 openness and SRQ concentration status which is related with low_beta rhythm. It means that the personality is closely correlated with human brain cortex activation and can be checked by brainwave analysis.

• Analytical Science and Technology
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• v.12 no.5
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• pp.428-435
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• 1999

A method for measuring Rn-222 and Ra-226 in aqueous sample using liquid scintillation counting technique has been studied. The Rn-222 was extracted easily from the water sample (10 mL) by 12 mL of xylene based organic scintillant. After radioactive equilibrium between Rn-222 and its alpha emitting decay products for three hours, the alpha activity from Rn-222 and its decay products were measured in a scintillation vial using the Wallae $1220^{TM}$ Quantulus liquid scintillation counter. Ra-226 concentration in aqueous sample was determined, after isolation of Ra-226 from the sample matrix, by extraction the ingrowth of the Rn-222 and its alpha emitting decay products with xylene based organic scintillant. The optimum pulse-shape analysis (PSA) value was evaluated by the figure of merit (FM) criterion. Minimum detectable activity (MDA) is about 0.14 Bq/L (3.78 pCi) for the region of Rn-222 and its alpha emitting decay products and 0.06 Bq/L (1.63 pCi) for the region of Po-214 respectively, with 200 min, counting time at PSA level 100 in the low-diffusion polyethylene vial and xylene based cocktail solution. Experiment on the optimum sample-cocktail volume ratio, the influence of agitation and the diffusion of radon from vial were carried out.

• Journal of Radiation Protection and Research
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• v.31 no.3
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• pp.141-148
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• 2006

Surveys of radioactive contamination were performed for imported foodstuffs in 2003. The following samples among imported foodstuffs were selected from markets and Korea Food and Drug Administration(KFDA); the imported samples from country associated with the Chernobyl nuclear accident, the samples produced around the nuclear power plants or nuclear tests, the foodstuffs reported as radioacitive contamination materials in foreign country. After pretreatments such as drying and homogenization, samples were analyzed. The $^{137}Cs$ radionuclide was only measured among the regulation radionuclides($^{137}Cs,\;^{134}Cs,\;^{131}I$) of food code. All foodstuffs except Inonotus Obliquus(Chaga mushooms) are less than 17.0 Bq/kg or below the minimum detectable activity(MDA). The activity concentrations of Chaga mushrooms from Russia ranged up to 131.25 Bq/ltg which is almost 35 % of the maximum permitted level of food code. The fraction of imported foodstuffs having meaningful radioactivity is small, however, the radioactive contamination survey of imported foodstuffs is still needed.

• The Journal of the Acoustical Society of Korea
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• v.29 no.4
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• pp.237-242
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• 2010

To do an experimental analysis in this paper, we divided two non-equivalent control groups, such as pre and post test groups for difference listening types by serious game contents. From these test groups, we can achieve the most ability of its activity quotient (ACQ) effect is a phonic type and the next one is an aural type. The purpose of this paper is focused on the quantitative analysis of the human's brain quotient (BQ) derived from serious educational game contents.