• Journal of Environmental Science International
• /
• v.12 no.2
• /
• pp.207-215
• /
• 2003

The purpose of this study is to estimate the air quality of subway stations having underground platforms in Busan Metropolitan City, from September to November 2000, over seven times. The places of the investigation include Yonsan-dong station, Somyon station, Busan station, Nampo-dong station, and Dusil station. Samplings were conducted at three points in each station, i.e. gates, ticket gates, and platforms. CO, NO, $NO_2$, and $O_3$ were the main components of air for this analysis. In order to more fully understand station environments, we also measured an air temperature at each point. The results showed that the $O_3$ average concentration of Yonsan-dong station was higher than others with 38~51 ppb. The average concentration of NO was high at the ticket gate and platform at Somyon station (119 ppb, 122 ppb) and Nampo-dong station (102 ppb, 100 ppb). These results show that the air pollution of stations with underground shopping malls were higher than others. At Somyon station having a junction station, NO and $NO_2$ concentration levels of platform-2 (noncrowded) were higher than platform-1 (crowded). This is most likely due to the accumulation of air pollutants and inadequate ventilation systems. To find the relationship of the indoor (platform) and outdoor (gate), we analyzed the I/O ratio. The averages of CO and $O_3$ were both higher than one: 1.16 and 1.82, respectively. In the correlations between each material and the others, NO vs $NO_2$ was the highest with R=0.63. In the correlations between indoor and outdoor, $O_3$ was the highest with R=0.64.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.10 no.4
• /
• pp.15-24
• /
• 2014

This study conducted a computational fluid dynamics(CFD) analysis to find an appropriate diameter or sectional area of air ducts and fluid pipes which have an electromagnetic pulse(EMP) shied to protect indoor electronic devices in special buildings like military fortifications. The result shows that the optimized outdoor air intake size can be defined with either the ratio of the maximum air velocity in the supply duct to the air intake size, or the shape ratio of indoor supply diffuser to the outdoor air intake. In the case of water channel, the fluid velocity at EMP shield with the identical size of the pipe, decreases by 25% in average due to the resistance of the shield. The enlargement of diameter at the shield, 2 step, improves the fluid flow. It illustrated that the diameter of downstream pipe size is 1step larger than the upstream for providing the design flow rate. The shield increases friction and resistance, in the case of oil pipe, so the average flow velocity at the middle of the shield increase by 50% in average. In consideration of the fluid viscosity, the oil pipe should be enlarged 4 or 5 step from the typical design configuration. Therefore, the fluid channel size for air, water, and oil, should be reconsidered by the engineering approach when EMP shield is placed in the middle of channel.

• Journal of Radiation Protection and Research
• /
• v.42 no.1
• /
• pp.42-47
• /
• 2017

Background: One of the most urgent issues following the accident at the Fukushima Daiichi nuclear power plant (FDNPP) was the remediation of the land, in particular, for residential area contaminated by the radioactive materials discharged. In this study, the effect of decontamination on reduction of ambient dose equivalent outdoors and indoors was evaluated. The latter is essential for residents as most individuals spend a large portion of their time indoors. Materials and Methods: From December 2012 to November 2014, thirty-seven Japanese single-family detached wooden houses were investigated before and after decontamination in evacuation zones. Outdoor and indoor dose measurements (n = 84 and 114, respectively) were collected based on in situ measurements using the NaI (Tl) scintillation surveymeter. Results and Discussion: The outdoor ambient dose equivalents [$H^*(10)_{out}$] ranged from 0.61 to $3.71{\mu}Sv\;h^{-1}$ and from 0.23 to $1.32{\mu}Sv\;h^{-1}$ before and after decontamination, respectively. The indoor ambient dose equivalents [$H^*(10)_{in}$] ranged from 0.29 to $2.53{\mu}Sv\;h^{-1}$ and from 0.16 to $1.22{\mu}Sv\;h^{-1}$ before and after decontamination, respectively. The values of reduction efficiency (RE), defined as the ratio by which the radiation dose has been reduced via decontamination, were evaluated as $0.47{\pm}0.13$, $0.51{\pm}0.13$, and $0.58{\pm}0.08$ ($average{\pm}{\sigma}$) when $H^*(10)_{out}$ < $1.0{\mu}Sv\;h^{-1}$, $1.0{\mu}Sv\;h^{-1}$ < $H^*(10)_{out}$ < $2.0{\mu}Sv\;h^{-1}$, and $2.0{\mu}Sv\;h^{-1}$ < $H^*(10)_{out}$, respectively, indicating the values of RE increased as $H^*(10)_{out}$ increased. It was found that the values of RE were $0.53{\pm}0.12$ outdoors and $0.41{\pm}0.09$ indoors, respectively, indicating RE was larger outdoors than indoors. Conclusion: Indoor dose is essential as most individuals spend a large portion of their time indoors. The difference between outdoors and indoors should be considered carefully in order to estimate residents' exposure dose before their returning home.

• Journal of Environmental Health Sciences
• /
• v.37 no.6
• /
• pp.406-417
• /
• 2011

Objectives: Exposure to bioaerosols in the indoor environment could be associated with a variety adverse health effects, including allergic disease such atopy. The objectives of this study were to assess children's exposure to bioaerosol in home indoor environments and to evaluate the association between atopy and bioaerosol, environmental, and social factors in Ulsan, Korea. Methods: Samples of viable airborne bacteria and fungi were collected by impaction onto agar plates using a Quick Take TM 30 and were counted as colony forming units per cubic meter of air (CFU/$m^3$). Bioaerosols were identified using standard microbial techniques by differential stains and/or microscopy. The environmental factors and possible causes of atopy based on ISAAC (International Study of Allergy and Asthma in Childhood) were collected by questionnaire. Results: The bioaerosol concentrations in indoor environments showed log-normal distribution (p < 0.01). Geometric mean (GM) and geometric standard deviation (GSD) of airborne bacteria and fungi in homes were 189.0 (2.5), 346.1(2.0) CFU/$m^3$, respectively. Indoor fungal levels were significantly higher than those of bacteria (p < 0.001). The concentration of airborne bacteria exceeded the limit recommended by the Korean Ministry of Environment, 800 CFU/$m^3$, in three out of 92 samples (3.3%) from 52 homes. The means of indoor to outdoor ratio (I/O) for airborne bacteria and fungi were 8.15 and 1.13, respectively. The source of airborne bacteria was not outdoors but indoors. GM of airborne bacteria and fungi were 217.6, 291.8 CFU/$m^3$ in the case's home and 162.0, 415.2 CFU/$m^3$ in the control's home respectively. The difference in fungal distributions between case and control were significant (p = 0.004) and the odds ratio was 0.996 (p = 0.027). Atopy was significantly associated with type of house (odds ratio = 1.723, p = 0.047) and income (odds ratio = 1.891, p = 0.041). Some of the potential allergic fungal genera isolated in homes were Cladosporium spp., Botrytis spp., Aspergillus spp., Penicillium spp., and Alternatia spp. Conclusions: These results suggest that there this should be either 'was little' meaning 'basically no significant association was found' or 'was a small negative' mean that an association was found but it was minor. It's a very improtant distinction. Association between airborne fungal concentrations and atopy and certain socioeconomic factors may affect the prevalence of childhood atopy.

• Journal of Environmental Science International
• /
• v.16 no.9
• /
• pp.1019-1026
• /
• 2007

This study was performed in 30 selected apartments in Seoul, Asan and Daegu area which were constructed within 4 years and over 4 years, to measure the concentration of VOCs(benzene, toluene, xylene) from July, 2004 to September. Mean ratios of indoor to outdoor VOCs concentrations in the construction under 4 years were higher in 1 than average, I/O ratio of over 4 years were lower in 1. This was considered that the VOCs density influences indoor pollutant. For the indoor air quality estimation, the deposition constant and the source strength factor of toluene were $1.49{\pm}2.05\;hr^{-1}\;and\;36.95{\pm}52.26\;ppb/h$, respectively.

• Journal of the Korean Solar Energy Society
• /
• v.29 no.6
• /
• pp.81-87
• /
• 2009

The purpose of this study is to evaluate of the outdoor thermal environment by building scale and block type as variable factors. In this study, 18 cases of office in central business district that have different condition are compared about their surface temperature, HIP(Heat Island Potential), and MRT(Mean Radiant Temperature). They are simulated with 3-dimension numerical simulation software named Hoyano-model. The output results contain visualized distribution chart and numerical data. The results of evaluation are as follows. (1)The surface temperature of the building becomes higher as building coverage ratio is higher but floor area ratio is lower. In same conditions, unified block type is maximum $3.2^{\circ}C$ higher than divided block type. (2)HIP shows different daily pattern as block type. During daytime, divided block type is much higher than unified block type but after sunset, it is changed. (3)MRT shows different distribution pattern as sunlight moves expecially at noon. (4)As the results of this study, cases that have high floor area ratio condition show lower surface temperature by tendency to stay low indoor temperature in office building and big rate of windows on building surface.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1613-1617
• /
• 2006

The total light efficiencies of the novel 1.9" transflective tRGB-t/rW and tRGB-rW TFT LCDs are calculated and they are implemented by the traditional 7-mask ${\alpha}$-Si processing. Then, the two vehicles are turned on with the appropriate Sub-Pixel Rendering White (SPRW) algorithms, so they can exhibit the extra luminance without the original visual resolution loss. Their outstanding optical properties are approved by measuring the contrast ratio (C.R.) and the NTSC ratio. Because they utilize the light resource very effectively and efficiently, they are very suitable for the dark indoor and the bright outdoor environments.

• Journal of Digital Convergence
• /
• v.16 no.1
• /
• pp.147-152
• /
• 2018

Recently, as the demand for transmission of ultra-high quality media data such as UHD, AR, and VR increases, various technologies for this have been actively developed and IEEE 802.11ad standard have been commercialized. In this paper, a test bed is constructed to analyze the indoor wireless environment using the IEEE 802.11ad standard based on mmWave, and the experimental results of various indoor wireless environments are introduced and analyzed. We compared the data from the module by data transmission, such as signal to noise ratio(SNR) and throughput. And we measured the beam pattern and width of the module and compared the effects on the indoor environment of the corridor and the office. This shows that the signal reflection of the wall shows higher SNR values and is more suitable to use for indoor than outdoor. It is confirmed that the loss when not in line of sight(LoS) is not enough to compensate the wall reflected signal. As a result, it is judged to be suitable for the indoor use of the mmWave LAN and can be usefully used for further experiments.

• Journal of IKEEE
• /
• v.3 no.2 s.5
• /
• pp.196-203
• /
• 1999

In this paper, the DS(direct sequence)-CDMA and MC(multi-carrier)-CDMA, which are being researched recently as a synchronous IMT-2000 scheme for next-generation mobile multimedia communications, are studied in terms of BER(bit error rate) performance. The BER performance of MC-CDMA with EGB, MRC, and improved MMSEC detection scheme are analyzed and compared to that of conventional DS-CDMA adopting RAKE receiver through the computer simulations under the environments of synchronous IMT-2000 transmission channel. Not only single user case but also multiuser case is considered in the given system. As a result, it is shown that MC-CDMA with MMSEC detection outperforms all other schemes improved the $E_b/N_o$ by about 5 [dB] and 6 [dB] when the BER is $2{\times}10^{-3}$, for the indoor/outdoor fading channel and synchronous IMT-2000 transmission channel, respectively. Also in the multiuser case, MC-CDMA with MMSEC detection scheme exhibits better performance than all the other schemes.

• Analytical Science and Technology
• /
• v.20 no.6
• /
• pp.474-482
• /
• 2007

Daycare centers are an important indoor environment for pre-school children and exposure area with potential harmful health effects for infants and children who spend most of their daily life. Sampling was undertaken at 29 daycare centers located Seoul in Korea from January, 2006 to December 2006. The target compounds were 7 individual volatile organic compounds (benzene, toluene, ethylbenzene, m,p-xylene, styrene, o-xylene, TVOC). The mean concentrations of TVOC, toluene, m ,p-xylene, ethylbenzene, benzene and styrene in daycare centers were $318.7{\mu}g/m^3$, $51.6{\mu}g/m^3$, $11.7{\mu}g/m^3$, $6.5{\mu}g/m^3$, $4.2{\mu}g/m^3$, $3.6{\mu}g/m^3$, respectively. Toluene occupied 17.6 % of the concentration of individual VOCs. The ratio of indoor and outdoor (I/O) of TVOC and toluene were 2.0 and 1.6, respectively. The results of characteristics according to a season of a year, the concentration of TVOC were measured $433.9{\mu}g/m^3$, and these concentrations during third quarter of the year in summer were higher than the other season. In the other four seasons, TVOC were measured 280.5 in winter, 298.3 in spring and $264.6{\mu}g/m^3$ in fall, respectively.