• 농촌계획
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• 제5권2호
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• pp.24-29
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• 1999

The soil from constructed wetland system for sewage treatment was analyzed to examine physical and chemical characteristics. Clogging and lowered permeability were the physical matters of concern, and nutrient and salt accumulation were the chemical matters of concern. However, the soil properties of the constructed wetland system after 3 year operation demonstrated no degradation and still the soil works almost same as the initial stage. Encouragingly, no sludge accumulation was observed inside the system. Therefore, it implies that the wetland sewage treatment system can work continuously as long as it is operated and managed properly not to cause excessive pollutant loading.

• 한국농촌건축학회논문집
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• 제22권1호
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• pp.1-12
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• 2020

The main purpose of the research is to prevent residents who are using underground parking lot from being exposed to pollusion, and to allow them to enjoy clean indoor environment. The study subject for the research are underground parking lots in 20 different apartments, 4 of them were constructed before 2000, 10 were constructed from 2000-2010, and the rest were constructed after 2010. By analyzing the air quality in these underground parking lots, we found out that O3, NO2, CO, PM10, Radon in all parking lots were not excessive compared to the standard limit. TVOC rate was measured with the value in between 312 ~ 2,137㎍/m3, with CO2 value in between 193~1,824 ppm, and HCHO with the value in between 0.01~1.52ppm. The lightning system in underground parking lots in apartments constructed before 2000 were using manual light control system, while automatic light control system was used in all apartments constructed after 2000, and the brightness of parking lots in apartments constructed before 2000 was quite low. The apartments constructed after 2000 are performing cleaning and ventilation due to management agreement, while the apartments constructed before 2000 are not performing regular cleaning and there was no mechanical ventilation system installed. The difference of indoor air quality was significant seasonally, daily, and yearly (year of construction), while illuminance was significantly different yearly.

• Environmental Engineering Research
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• 제18권3호
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• pp.169-176
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• 2013

The present study was designed to examine the concentrations, emission rates, and source characteristics of a variety of volatile organic compounds (VOCs) in 30 newly-constructed apartment buildings by measuring indoor and outdoor VOC concentrations over a 2-year period. For comparison, seven villa-type houses were also surveyed for indoor and outdoor VOC concentrations over a 3-month period. Indoor and outdoor air samples were collected on Tenax-TA adsorbent and analyzed using a gas chromatograph (GC)/mass spectrometer system or a GC/flame ionization detector system coupled to a thermal desorption system. The long-term change in indoor VOC concentrations depended on the type of VOCs. Generally, aromatic (except for naphthalene), aliphatic, and terpene compounds exhibited a gradual deceasing trend over the 2-year follow-up period. However, the indoor concentrations of the six halogenated VOCs did not significantly vary with time changes. Similar to these halogenated VOCs, the indoor naphthalene concentrations did not vary significantly with time changes over the 2-year period. Unlike the halogenated VOCs, the indoor naphthalene concentrations were much higher than the outdoor concentrations. The indoor concentrations of aliphatic and aromatic compounds were higher for the villa-type houses when compared to those of apartment buildings. In addition, four source groups (floor coverings and interior painting, household products, wood paneling and furniture, moth repellents) and three source groups (floor coverings and interior painting, household products, and moth repellents) were considered as potential VOC sources inside apartment buildings for the first- and second-year post-occupancy stages, respectively.

• 상하수도학회지
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• 제29권2호
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• pp.211-222
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• 2015

This study focused on evaluating the efficiency of the removal of non-point source pollution by Daecheong Lake Juwon Stream constructed wetlands. The constructed wetland system is a surface flow type designed in the year 2007 for purifying eutrophic water of Daecheong Lake Juwon Stream. The value of conductivity, suspended solids(SS), chemical oxygen demand using a potassium permanganate($COD_{Mn}$), five-day biochemical oxygen demand($BOD_5$), total nitrogen(T-N), total phosphorous(T-P), and pH in inflow averaged 220.2, 2.46, 3.33, 1.34, 2.00, 0.04 mg/L and 7.24, respectively and in outflow averaged 227.9, 1.12, 3.34, 0.87, 1.16, 0.02 mg/L and 7.45, respectively. The average removal efficiency of constructed wetlands was 30 % for SS, 22 % for $BOD_5$, 45 % for T-N and 31 % for T-P. The removal rates of SS, $BOD_5$ and T-N in the spring, summer and autumn were higher than those in winter. The removal rate of T-P was not significant different in all seasons. The amounts of pollutants removal in the constructed wetlands were higher in the order of $3^{rd}$ < $2^{nd}$ < $1^{st}$ wetland for SS and T-P, $2^{nd}$ < $3^{rd}$ < $1^{st}$ wetland for $BOD_5$ and T-N. Therefore, our findings suggest that the constructed wetlands could well treat the eutrophic Daecheong Lake Juwon Stream waters.

• 한국물환경학회지
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• 제28권1호
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• pp.94-101
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• 2012

The performance data for eight years from a free-surface-flow constructed wetland system receiving agricultural tailwater were used to analyze denitrification rate and nitrogen treatment characteristics according to season and wetland design. Seasonal difference between growing season (March~November) and winter season (December~February) was shown in the concentration of all nitrogen species. Seasonal nitrogen treatment has similar trend with temperature and measured denitrification rate. The highest denitrification rate was measured in July, but treatment efficiency was most higher in May and June. Nitrogen absorption of vegetation could affect to these wetland performances, therefore dense population of wetland vegetation might be helpful. According to design of wetland, at least 25~50 m of wetland length was needed to decrease effluent T-N concentration to background concentration in growing season. In winter season, wetland needed much longer distance to reduce T-N concentration. Mass removal rate was continuously high through whole year because runoff coefficient was low in winter season. Applicability of constructed wetland was observed for the total maximum daily load that control T-N load.

• 한국환경농학회지
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• 제19권5호
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• pp.433-441
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• 2000

A feasibility study was performed to examine the agronomic application of treated sewage on paddy rice culture by field experiment for two consecutive years. The domestic sewage was treated by the constructed wetland system which was in subsurface flow type and consisted of sand and macrophyte. The effluent of the wetland system was used for irrigation water. The effluent was diluted to maintain the total nitrogen concentration below $26mg{\cdot}L^{-1}$ in the first year and used without dilution in the second year experiment. Growth components and yields were compared against the CONTROL plot where conventional method was applied. And also, soil characteristics of the plots before and after reclaimed sewage irrigation were analyzed. Generally, addition of the treated sewage to the irrigation water showed no adverse effects on paddy rice culture, and even enhancement was noticed in both growth and yield. Irrigation of treated sewage after concentration adjusted with conventional fertilization showed the better result, and the yield exceeded that of CONTROL case where clean water was irrigated. Soil characteristics changed after irrigation, and significant EC increasing was observed for the reclaimed sewage irrigation plots. From this study, it appears that reuse of treated sewage, as supplemental irrigation water could be a feasible and practical alternative. For full-scale application, further study is recommended on the specific guideline of major water quality components in treated sewage for irrigation and public health.

• Journal of Astronomy and Space Sciences
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• 제12권1호
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• pp.44-53
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• 1995

충북대학교 천문우주학과의 35cm Schmidt-Cassegrain 망원경으로 접촉쌍성 AW UMa를 1994년 3월부터 4월 사이의 13일 밤 동안 BVRI 광전측광관측 하여 각 필터별로 273점씩 총 1092개의 관측점을 얻었다. 이 관측점들을 이용하여 BVRI 광도곡선을 그렸으며, 이로부터 주극심시각 JD Hel 2449456.1502 와 부극심시각 JD Hel 2449432.2412, JD Hel 2449447.1567을 결정하였다. 수집한 극심시각 자료들을 가지고 그린 O-C도에서, 공전주기 변화량 $-0.^d00000394$를 구하고 그에 해당하는 질량이동량 $-6.4\times10^{-7}M_\odot/year$를 계산하였다. AW UMA의 광도변화를 질량이동과 연관하여 해석할 수 있는 가능성을 제시했다.

• 약학회지
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• 제54권2호
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• pp.126-133
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• 2010

This study was conducted to analyze cost-utility of bosentan versus iloprost indicated for pulmonary arterial hypertension (PAH) in a Korean healthcare setting from a payer's perspective. We constructed a Markov model to estimate total costs and outcomes for 1-year time horizon in a hypothetical cohort of 50-year-old patients with PAH. Base analysis showed that bosentan resulted in KW 5.5 billions saving and 18 quality-adjusted life year (QALY) gains per 100 patients compared to iloprost. Bosentan as a dominant strategy was found to be robust through various sensitivity analyses.

• Journal of Chest Surgery
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• 제51권2호
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• pp.122-129
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• 2018

Background: For hemodialysis patients with end-stage renal disease (ESRD), it is important to construct an efficient vascular access with a superior patency rate. This study investigated the factors influencing the efficiency of arteriovenous fistulas (AVFs) constructed using an autologous vessel and evaluated the necessity of ultrasonography as a preoperative tool for AVF construction. Methods: A retrospective analysis was performed of 250 patients in whom an AVF was constructed using an autologous vessel due to ESRD at our institution from January 2009 to April 2016. Results: The 1-, 3-, and 5-year patency rates for all subjects were 87.6%, 85.6%, and 84.4%, respectively. The patients who underwent a preoperative evaluation of their vessels via ultrasonography had better patency rates than those who did not. Superior patency rates were found in patients under 65 years of age or with an anastomotic vein diameter of 3 mm or more. The 1-year patency rate and the diameter of the anastomotic vein showed a positive relationship. Conclusion: Ultrasonography is strongly recommended for AVF construction, and efforts should be made to increase the patency rate in patients over 65. Superior clinical results can be expected when an AVF is made using an autologous vessel with an anastomotic vein diameter of at least 3 mm.

• Journal of Astronomy and Space Sciences
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• 제30권4호
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• pp.241-246
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• 2013

We have investigated drought periodicities occurred in Seoul to find out any indication of relationship between drought in Korea and solar activities. It is motivated, in view of solar-terrestrial connection, to search for an example of extreme weather condition controlled by solar activity. The periodicity of drought in Seoul has been re-examined using the wavelet transform technique as the consensus is not achieved yet. The reason we have chosen Seoul is because daily precipitation was recorded for longer than 200 years, which meets our requirement that analyses of drought frequency demand long-term historical data to ensure reliable estimates. We have examined three types of time series of the Effective Drought Index (EDI). We have directly analyzed EDI time series in the first place. And we have constructed and analyzed time series of histogram in which the number of days whose EDI is less than -1.5 for a given month of the year is given as a function of time, and one in which the number of occasions where EDI values of three consecutive days are all less than -1.5 is given as a function of time. All the time series data sets we analyzed are periodic. Apart from the annual cycle due to seasonal variations, periodicities shorter than the 11 year sunspot cycle, ~ 3, ~ 4, ~ 6 years, have been confirmed. Periodicities to which theses short periodicities (shorter than Hale period) may be corresponding are not yet known. Longer periodicities possibly related to Gleissberg cycles, ~ 55, ~ 120 years, can be also seen. However, periodicity comparable to the 11 year solar cycle seems absent in both EDI and the constructed data sets.