• 한국대기환경학회지
• /
• 제25권5호
• /
• pp.382-391
• /
• 2009

The aim of the study was to assess the levels in typical central borough of phthalate exposure by monitoring children's facilities (19 kindergartens and 21 elementary schools) and households (17 old apartments and 22 new apartments) via sampling indoor floor dust. A vacuum cleaner specifically prepared for sampling dust was attached to a filter of a vacuum cleaner dust collecting container. During the sample preparation process, containers made of glass were used and analysis was performed using GC-MSD. The mean concentration of DEHP was $412{\mu}g/g$, DnBP was $24{\mu}g/g$, and BBzP was $10{\mu}g/g$ dust. The indoor characteristics including floor, wall materials, years after construction, water leakage history for the past three years, and ventilation were also examined to categorize phthalate esters from the dust samples. From the flooring and wallpaper materials of kindergartens and elementary schools, DEHP in the dust sample appeared at a statistically significant level (p<0.05) when PVC materials were present. DEHP in the indoor dust also increased significantly (p<0.01) during the construction period. The daily intake of DEHP measured from indoor dust was 0.08~$19.7{\mu}g/kg/day$ for children and 0.02~$1.1{\mu}g/kg/day$ for adults (women). The results clearly revealed that phthalate exposure is greater in children than in adults (women) due to the indoor dust.

• 한국위험물학회지
• /
• 제6권2호
• /
• pp.7-12
• /
• 2018

Hydrochloric acid is a highly corrosive toxic substance and requires proper safety to minimize damage in case of leakage. Among the various risk-reduction facilities, the dike is a typical safety facility installed to protect the surrounding buildings and facilities by preventing the external spread of hazardous materials from the storage tank. In this study, the KORA program was used to assume leakage accident of hydrochloric acid storage tank. At this time, the extent of the damage effects of ERPG-2 were assessed for each of the three separation distance between the storage tank and the dike. The study found that the smaller the separation distance between the dike and the storage tank, the smaller the extent of damage caused by hydrochloric acid leakage, and the greater the impact of indoor conditions under the same conditions. Through this process, we are going to assist in selecting locations and installing facilities for new and existing businesses.

• 실내환경 및 냄새 학회지
• /
• 제17권4호
• /
• pp.355-361
• /
• 2018

Mold grows more easily when humidity is higher in indoor spaces, and as such is found more often on wetted areas in housing such as walls, toilets, kitchens, and poorly managed spaces. However, there have been few studies that have specifically assessed the level of mold in the indoor spaces of water-damaged housing in the Republic of Korea. We investigated the levels of airborne mold according to the characteristics of water damage types and explored the correlation between the distribution of mold genera and the characteristics of households. Samplings were performed from January 2016 to June 2018 in 97 housing units with water leakage or condensation, or a history of flooding, and in 61 general housing units in the metropolitan and Busan area, respectively. Airborne mold was collected on MEA (Malt extract agar) at flow rate of 100 L/min for 1 min. After collection, the samples were incubated at $25^{\circ}C$ for 120 hours. The cultured samples were counted and corrected using a positive hole conversion table. The samples were then analyzed by single colony culture, DNA extraction, gene amplification, and sequencing. By type of housing, concentrations of airborne mold were highest in flooded housing, followed by water-leaked or highly condensed housings, and then general housing. In more than 50% of water-damaged housing, the level of airborne mold exceeded the guideline of Korea's Ministry of Environment ($500CFU/m^3$). Of particular concern was the fact that the I/O ratio of water-damaged housing was greater than 1, which could indicate that mold damage may occur indoors. The distribution patterns of the fungal species were as follows: Penicillium spp., Cladosporium spp. (14%), Aspergillus spp. (13%) and Alternaria spp. (3%), but significant differences of their levels in indoor spaces were not found. Our findings indicate that high levels of mold damage were found in housing with water damage, and Aspergillus flavus and Penicillium brevicompactum were more dominant in housing with high water activity. Comprehensive management of flooded or water-damaged housing is necessary to reduce fungal exposure.

• 한국가스학회지
• /
• 제7권4호
• /
• pp.24-29
• /
• 2003

실내에서 가스 폭발시 피해를 예측하기 위해서 폭발 화염면의 전파를 수치해석을 통해 해석했다. 확산방정식에 의해 가스누출에 의한 실내의 가스확산분포를 구했으며, 문헌에서 선택한 누출의 초기조건을 사용했다. 화염온도를 계산하기 위해 각 가스 혼합비에 따른 엔탈피와 화학식에 대한 reduced mechanism을 사용했으며 문헌에서 찾은 각 가스의 농도 별 층류 연소속도를 혼합가스의 층류연소속도에 적용시켰다. k-$\epsilon$ 모델에서 난류 에너지를 층류연소속도와 결합시켜 난류화염 전파속도를 모델링 했다. 화염면의 전파를 분석하기 위해 실내의 위치에는 직각, 화염면의 전파에는 원통좌표계를 사용했다. 유리창의 파손에 의한 화염전파면의 변화에 따른 압력상승 요인을 해석하였으며, 창문의 크기에 따라서 점화위치에 따른 실내 압력상승의 영향이 서로 다르게 나타나는 결과를 얻었다.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2021년도 춘계학술대회
• /
• pp.397-399
• /
• 2021

사회적으로 1인 가구의 증가와 Home IoT 기술의 발전에 따라 주거 환경의 편의성 개선이 중요시된다. 또한 'COVID-19'에 의한 실내 활동 증가에 따라 1인 가구의 주거 편리성을 위한 제품 개발이 요구되고 있다. 이러한 추세로 그 전보다 현재 주거 환경과 상호작용이 수월해졌으며, 이에 따라 Home IoT 기술 발전의 필요성이 대두되고 있다. 따라서 본 논문은 온도, 습도, 미세먼지와 같이 실내 환경 유지에 필요한 정보를 모니터링하여 사용자와 상호작용 할 수 있도록 하였으며, 가스 누출 및 화재와 같은 안전사고 예방에 필요한 IoT 센서를 탑재하여 증가하는 실내 활동에 안전성을 향상하는 시스템을 제안하였다.

• 한국산업보건학회지
• /
• 제28권4호
• /
• pp.382-392
• /
• 2018

Objective: Allergic diseases such as asthma due to fungal exposure in houses have increased, and proper management is urgent. Mold can grow in the air, floor, walls, and other areas according to environmental conditions, and there are many limitations to the conventional methodology for examining fungal exposure. For this reason, the degree of fungal contamination is being evaluated by ERMI (Environmental Relative Moldiness Index), a quantitative analysis method proposed by the EPA. In this study, we compared ERMI values between water-damaged dwellings and non-damaged ones to evaluate the effectiveness of Korean ERMI values. We also explored the association of ERMI values with the level of airborne mold and characteristics of dwellings. Methods: Floor dust was collected after installing a Dustream collector on the suction port of a vacuum cleaner. The collected samples were filtered to remove only 5 mg of dust, and DNA was extracted using the FastDNA SPIN KIT protocol. Results: The ERMI values were found to be 19.6 (-6.9-58.8) for flooded houses, 7.5 (-29.2-48.3) for leaks/condensation, and 0.8 (-29.2-37.9) for non-damaged dwellings. The airborne concentration of mold for flooded, leakage or condensed, and non-damaged houses were $684CFU/m^3$, $566CFU/m^3$, and $378CFU/m^3$, respectively. The correlation between ERMI values and the levels of airborne mold was low (R = 0.038), but a weakly significant association of the ERMI values with the concentration of particulate matter ($PM_{10}$) was observed as well(R=0.231,P<0.05). Conclusions: Our findings show that the reference value using ERMI can be used to distinguish water-damaged and non-damaged dwellings. It is believed that ERMI values could be a promising tool for assessing long-term fungal exposure in dwellings.

• Journal of Radiation Protection and Research
• /
• 제46권3호
• /
• pp.127-133
• /
• 2021

Background: Phosphogypsum is material produced as a byproduct in fertilizer industry and is generally used for building materials. This material may contain enhanced radium-226 (²²⁶Ra) activity concentration compared to its natural concentration that may lead to indoor radon accumulation. Therefore, an accurate measurement method is proposed in this study to determine ²²⁶Ra activity concentration in phosphogypsum sample, considering the potential radon leakage from the sample container. Materials and Methods: The International Atomic Energy Agency (IAEA) phosphogypsum reference material was used as a sample in this study. High-purity germanium (HPGe) gamma spectrometry was used to measure the activity concentration of the ²²⁶Ra decay products, i.e., ²¹⁴Bi and ²¹⁴Pb. Marinelli beakers sealed with three different sealing methods were used as sample containers. Due to the potential leakage of radon from the Marinelli beaker (MB), correction to the activity concentration resulted in gamma spectrometry is needed. Therefore, the leaked fraction of radon escaped from the sample container was calculated and added to the gamma spectrometry measured values. Results and Discussion: Total activity concentration of ²²⁶Ra was determined by summing up the activity concentration from gamma spectrometry measurement and calculated concentration from radon leakage correction method. The results obtained from ²¹⁴Bi peak were 723.4 ± 4.0 Bq·kg^-1 in MB1 and 719.2 ± 3.5 Bq·kg^-1 in MB2 that showed about 5% discrepancy compared to the certified activity. Besides, results obtained from ²¹⁴Pb peak were 741.9 ± 3.6 Bq·kg^-1 in MB1 and 740.1 ± 3.4 Bq·kg^-1 in MB2 that showed about 2% difference compared to the certified activity measurement of ²²⁶Ra concentration activity. Conclusion: The results show that radon leakage correction was calculated with insignificant discrepancy to the certified values and provided improvement to the gamma spectrometry. Therefore, measuring ²²⁶Ra activity concentration in TENORM (technologically enhanced naturally occurring radioactive material) sample using radon leakage correction can be concluded as a convenient and accurate method that can be easily conducted with simple calculation.

• 한국생산제조학회지
• /
• 제23권3호
• /
• pp.299-309
• /
• 2014

When using an automotive heating, ventilation, and air conditioning (HVAC) system, we can obtain fresh outside air while maintaining the interior vehicle temperature. In this study, a correction equation considering experimental data for automotive indoor air leakage is defined to simulate the ratio of fresh air to recirculated air in the automobile cabin. With this correction equation, numerical results are compared with experimental data and validated. The $CO_2$ concentration in the automotive cabin is evaluated by considering various boarding conditions and mass flow rates of the HVAC system. The $CO_2$ concentration model derived in this study is expected to be used to control the effective air conditioning and become a basic research tool for automotive air quality control system development.

• Journal of Korean Society for Atmospheric Environment
• /
• 제23권E2호
• /
• pp.66-73
• /
• 2007

The introduction of tracer gas techniques to ventilation studies in indoor environments provides valuable information that used to be unattainable from conventional testing environments. Data acquisition systems (DASs) containing analogue-to-digital (A/D) converters are usually used to function the key role that records signals to storage in digital format. In the testing process, there exist a number of components in the measuring equipment which may produce system-based inference to the monitored results. These unwanted fluctuations may cause significant error in data analysis, especially when non-linear algorithms are involved. In this study, a pre-processor is developed and applied to separate the unwanted fluctuations (noise or interference) in raw measurements and to reduce the uncertainty in the measurement. Moving average, notch filter, FIR (Finite Impulse Response) filters, and IIR (Infinite Impulse Response) filters are designed and applied to collect the desired information from the raw measurements. Tracer gas concentrations are monitored during leakage and ventilation tests in the model test room. The signal analysis functions are introduced to carry out the digital signal processing (DSP) work. Overall the FIR filters process the $CO_2$ measurement properly for ventilation rate and mean age of air calculations. It is found that, the Kaiser filter was the most applicable digital filter for pre-processing the tracer gas measurements. Although the IIR filters help to reduce the random noise in the data, they cause considerable changes to the filtered data, which is not desirable.

• 한국산업융합학회 논문집
• /
• 제14권1호
• /
• pp.37-43
• /
• 2011

Study of stack effects in the early design stage is the most appropriate moment to draw any problems and provide the right solutions. However, In a real process, The pre-design planning stage review is not thoroughgoing enough to high-rise construction site. Therefore, this study has reviewed by selecting one of inappropriate project [D] to find the possible stack effect alternatives in an early design documentation stage and provide countermeasures to be a foundations of stack effect in the construction stages.