• 한국방재안전학회논문집
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• 제15권2호
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• pp.37-44
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• 2022

기후변화로 인해 집중호우와 태풍의 빈도가 늘어면서 토석류의 발생 빈도가 늘어나고 있다. 특히 강원도의 경우 산지와 해안이 접하는 지형적 특성을 가지고있어 산지재해에 의한 피해발생이 늘어나고 있다. 본 연구에서는 태풍 미탁으로 인해 발생한 강원도 삼척시를 대상으로 토석류 피해지역 분석을 위해 모델링을 수행하였다. 토석류 퇴적부분에서의 유동특성을 분석하기 위해 수치지도와 현장자료를 통해 입력자료를 구축하고 2차원 모델인 FLO-2D를 모의하였다. 피해지역을 토석류 유입부, 마을 중심부, 항구 인접부로 나누어서 토석류의 유동심과 유속을 모의하여 현장 조사한 자료와 비교분석하였다. 그 결과 최대유동심의 경우 토석류 유입부에서는 2.4m 마을 중심부에서는 2.7m, 항구 인접부에서는 1.4m로 나왔으며 현장조사와 비교분석 하였을 때 유사하게 나타났다. 그리고 최대 유속의 경우 토석류 유입부에서는 3.6m/s 마을 중심부에서는 4.9m/s, 항구 인접부에서는 1.2m/s로 산정되었으며 최대유속이 나타난 구간에서 최대유동심이 발생하는 것을 확인하였다.

• 한국대기환경학회지
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• 제32권3호
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• pp.289-304
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• 2016

The $PM_{10}$ and $PM_{2.5}$ aerosols were collected at the Gosan site of Jeju Island in 2013 and analyzed, in order to examine the variation characteristics of the chemical compositions in relation to the haze, Asian dust, and mixed haze-Asian dust episodes. Volume concentrations obtained from the Aerodynamic Particle Sizer (APS) were high in the range of $0.6{\sim}1.0{\mu}m$ particles for haze event, and in the range of $2.0{\sim}10.0{\mu}m$ particles for Asian dust event. For the haze event, nitrate concentrations increased highly as 8.8 and 25.1 times for $PM_{10}$ and $PM_{2.5}$, respectively, possibly caused by the inflow of air mass stagnated in eastern parts of China into Jeju area. For the Asian dust event, the concentrations of nss-$Ca^{2+}$, $NO_3{^-}$ and nss-$SO_4{^{2-}}$ increased 6.0, 1.5, 1.8 times for $PM_{10}$, and 2.3, 1.3, 1.6 times for $PM_{2.5}$, respectively. Meanwhile, for the mixed haze-Asian dust event, the concentrations of nss-$Ca^{2+}$ and $NO_3{^-}$ increased 13.4 and 3.2 times for $PM_{10}$, and 1.8 and 3.4 times for $PM_{2.5}$, respectively. The $NH_4NO_3$ content was higher than that of $(NH_4)_2SO_4$ during the haze event, however it was relatively low during the mixed haze-Asian dust event. The aerosols were acidified mostly by inorganic acids, and especially the nitric acid contributed highly to the acidification during both the haze and the mixed haze-Asian dust events. Meanwhile, the neutralization by ammonia was noticeably high during haze event when the stagnated air mass moved from China.

• 한국대기환경학회지
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• 제32권1호
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• pp.67-81
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• 2016

In order to examine the variation characteristics of chemical compositions in accordance with the different meteorological conditions, $PM_{10}$ and $PM_{2.5}$ were collected at Gosan site of Jeju Island in 2014, and then their ionic and elemental species were analyzed. The concentrations of nss-$SO{_4}^{2-}$ and $NH_4{^+}$ were respectively 4.3 and 3.3 times higher in fine particle mode ($PM_{2.5}$) compared to coarse particle mode ($PM_{10-2.5}$), however $NO_3{^-}$ concentration was 1.6 times higher in coarse mode compared to fine particle mode. During Asian dust days, the concentrations of nss-$Ca^{2+}$ and $NO_3{^-}$ increased highly as 7.7 and 4.5 times in coarse particle mode, and 3.0 and 4.9 times higher in fine particles, respectively. Especially, the concentrations of the crustal species (Al, Fe, Ca, K, Mn, Ba, Sr, etc.) indicated a noticeable increase during the Asian dust days. For the haze days, the concentrations of secondary pollutants increased 2.2~2.7 and 2.9~6.0 times in coarse and fine particles, respectively, and they were 0.8~1.1 and 1.8~2.4 times, respectively, during the mist days. The aerosols were acidified largely by sulfuric and nitric acids, and neutralized mainly by ammonia in fine particle mode during the haze days, but neutralized by calcium carbonate in coarse particle mode during the Asian dust days. The clustered back trajectory analysis showed that the concentrations of nss-$SO{_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$ were relatively high when the inflow pathway of air mass was from the southern part of China.

• 대기
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• 제20권2호
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• pp.173-186
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• 2010

The impact of the precipitation has been focused on losses in social and economical sectors. However, as growing the concerns of the future water shortage caused by the climate change, the precipitation should be consider in various views for an effective planning in the water resource management. A precipitation case occurred from 20 to 21 April 2009 was recorded as a welcome rain because it reduced the severe drought continued in Korea from winter season of 2008. In this study, economic values of the event was calculated with positive aspects in various sectors. The estimation is based on four major parts such as a secure of water resources, the improvement of air quality, the decrease of forest fires, and the reduction of the drought impact. The water resources only considered inflow waters into dams and the reservoirs managed by Korean public institutions and their economic values accounts for 5.92 billion won. Decreases of four air pollutants($PM_{10}$, $NO_2$, CO, and $SO_2$) were considered as the positive effects of the rainfall and estimated 175.4 billion won. The preventive effect of the forest fire after the rainfall results in 0.48 billion won. Finally, the rainfall during the drought period is effective to reduce the social costs of 108.65 billion won. Although the economic values estimated in this study explain parts of the positive effects of the precipitation, it can help to develop a comprehensive and systematic valuation system for the whole process of the precipitation. For doing this, various rainfall types should be analyzed in social-economic terms including economics, environments and hydrology.

• 한국태양에너지학회 논문집
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• 제25권4호
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• pp.111-118
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• 2005

The purpose of this study is to address the progress of the heat island phenomenon and the scheme to decrease in heat island phenomenon through analysis of micro-climates according to land use and make a plan to construct wind ways. The result is: 1) Analysis of temperature and humidity at 6 spots for 24 hours showed that heat island phenomenon was considerably intense around center road of Gwangju and can be mild through making lakes and green zones. 2) Analysis of the direction and velocity of the wind at 2 spots for 24 hours showed that the direction of the wind at the center of Gwangju was SSW(South-South-West) and average velocity of the it was $1.2{\sim}1.5\;m/s$. To make the inflow of the low-temperature air current from Mt. Mudeung into the city through Gwangju river, efficient management of Gwangju riverside parks should be considered for Gwangju river itself to be wind way. 3) Analysis of mobile temperature measurement on 3 courses for 24 hours showed that the low-temperature air current of Mt. Mudeung and a micro-climate of Gwangju river can lighten thermal storage phenomena of the city in that the temperature was lowest at Gwangju riverside. These outcome is from a day term measurement. So, to figure out accurate condition of heat island phenomenon in Gwangju City, it is needed to have long term measurements and accumulation of those information.

• 한국습지학회지
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• 제23권2호
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• pp.116-121
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• 2021

이 연구는 현재까지 국내 야생에서 확인되지 않았던 외래종 견목거북과(Podocnemididae) 아마존노란점거북(Yellow-spotted Amazon River Turtle, Podocnemis unifilis)을 처음으로 관찰한 사실을 학술적으로 보고하고자 한다. 2020년 7월 24일 제주특별자치도 제주시 조천읍 와흘리 33°30'20.08"N 126°38'0.23"E 지점에서 아마존노란점거북 2개체가 바위에서 일광욕하고 있는 것이 관찰되었다. 1개체는 머리에 노란색 반점이 있었고, 다른 1개체는 흑화되어 검은색을 띠었다. 관찰된 장소는 도로와 인접해 있고, 사람들의 출입이 잦은 곳으로, 애완용으로 사육되던 개체가 연못으로 방사된 것으로 추측된다. 최근 호수, 저수지 등 국내 야생에서 확인되는 외래거북이 증가하고 있으며, 외래거북 유입으로 인한 수생태계의 피해가 예상되는 만큼, 외래생물에 대한 시민과학 프로젝트와 환경교육을 통한 대중들의 인식 개선이 필요하다. 향후 발견된 개체에 대하여 지속적인 모니터링을 통한 야생 적응 여부, 번식과 관련된 추가 연구가 수행되어야 할 것이다.

• Ocean and Polar Research
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• 제44권1호
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• pp.1-11
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• 2022

Hypoxia can affect water-atmosphere methane flux by controlling the production and consumption processes of methane in coastal areas. Seasonal methane concentration and fluxes were quantified to evaluate the effects of seasonal hypoxia in Dangdong Bay (Gyeongsangnamdo, Jinhae Bay, South Korea). Sediment-water methane flux increased more than 300 times during hypoxia (normoxia and hypoxia each 6, 1900 µmol m^-2 d^-1), and water-atmospheric methane flux and bottom methane concentration increased about 2, 10 times (normoxia and hypoxia each 190, 420 µmol m^-2 d^-1; normoxia and hypoxia each 22, 230 nM). Shoaling of anaerobic decomposition of organic matter in the sediments during the hypoxia (August) was confirmed by the change of the depth at which the maximum hydrogen sulfide concentration was detected. Shoaling shortens the distance between the water column and methanogenesis section to facilitate the inflow of organic matter, which can lead to an increase in methane production. In addition, since the transport distance of the generated methane to the water column is shortened, consumption of methane will be reduced. The combination of increased production and reduced consumption could increase sediment-aqueous methane flux and dissolved methane, which is thought to result in an increase in water-atmospheric methane flux. We could not observe the emission of methane accumulated during the hypoxia due to stratification, so it is possible that the estimated methane flux to the atmosphere was underestimated. In this study, the increase in methane flux in the coastal area due to hypoxia was confirmed, and the necessity of future methane production studies according to oxygen conditions in various coastal areas was demonstratedshown in the future.

• 한국방재안전학회논문집
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• 제12권4호
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• pp.1-13
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• 2019

최근 기후변화로 인해 강우강도 및 빈도의 증가에 따른 국지성 집중호우의 피해가 증가함에 따라 초기 우수에 대응할 수 있는 시설물 설치가 필요한 실정이다. 이를 위해, 빗물을 직접 유출하지 않고 저류 시키는 저영향 개발(Low Impact Development)기법을 적용한 시설물 설계 및 수치모형을 이용한 유출저감효과 검토에 관한 연구가 많이 진행되어 왔다. 그러나 대부분의 연구는 유출저감효과에 대한 검토만 수행된 반면, 시설물에 유입되는 유량에 의한 흐름특성 변화 검토 및 안정성 검토에 관한 연구는 미비한 실정이다. 이에 본 연구에서는 LID 기법이 많이 적용되고 있는 회전교차로를 대상으로 하여, 회전교차로 내의 우수저류조의 관망시스템의 안정성 검토를 3차원 수치모형인 FLOW-3D를 사용하여 검토하였다. 또한 우수저류조의 최적의 설계방안 도출을 위하여 우수저류조의 수를 증가하여 용량증가에 따른 유속과 동압의 변화를 검토하고 설계기준과 비교하였다. 우수저류조의 제원 및 유입유량은 선행연구에서 제시된 값을 적용하여 수치모의를 수행한 결과, 유속은 저류조 설치개소 수가 증가할수록 빨라지는 것을 확인하였고, 대부분 설계기준 범위 안에 유속이 형성되는 것을 확인하였다. 다만 추가 저류조가 3개 이상일 경우는 추가저류조관에서 유속이 3.44 m/s가 발생하여 설계유속의 허용범위를 초과하였고, 유속의 증가율도 일정해지는 것으로 나타났다. 난류강도 및 바닥전단력 비교의 경우, 저류조 설치 개소수가 증가함에 따라 바닥전단력이 한계소류력보다 크게 나타나 유입토사의 침전은 발생하지 않을 것으로 예상되나 난류강도의 크기가 작아져 플록(Floc)형성으로 인한 토사 침전이 발생할 수 있음을 고려해야한다. 최종적으로 유속을 이용한 동압 산정 결과를 우수관 설계에 일반적으로 사용되는 압력관의 허용내압과 비교하였을 경우, 동압이 허용내압보다 작게 나타났다. 이를 통하여 본 연구에서 제안한 우수저류조 제원으로 설계할 경우 추가 저류조를 2개까지 설치하는 것이 가장 적합한 것으로 나타났다. 이는 저류조를 계속하여 설치하게 되면 배수가 원활해져 관내 유속이 빨라지고, 유속증가로 인하여 관의 마모손상 등의 문제가 일어날 수 있기 때문이다. 그러나 본 연구는 저류조의 제원 및 우수의 유입량을 가정하였고, 단순히 저류조를 추가하여 저류조 설계방안을 도출한 한계점이 있어 향후에는 다양한 저류조 형태 및 우수유입 시나리오를 적용하여 검토한다면 보다 효율적인 설계방안 도출이 가능할 것으로 기대된다.

• 한국농공학회지
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• 제14권3호
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• pp.2703-2715
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• 1972

본 실험 연구는 흙수로내에서의 용수손실에 관한 연구로서 물을 필요로 하는 논과 밭까지 필요한 시기에 필요한 양만큼을 보급해 주어야 하는 관개계획을 수립함에 있어 매년 높아져 가는 사수위에 늘어가는 필요 수량과의 함수관계를 해결하는 지표를 주는데 목표을 두었다. 시험은 용수계통인 간선, 지선, 분선수로로 구분하여 간선수로에서는 1,000m 구간을 잡아 유속계측정 방법으로 지선수로에서는 500m 구간을 잡아 상 하류에 파야샬후륨을 설치하여 측정하였으며 분선수로에서는 200m 구간을 상 하류에 사각예언웨어를 설치하여 손실을 측정하였으며 기타손실에 영향을 주는 제요인들도 조사하여 다음 결과를 얻었다. (1) 1,000m 구간의 간선수로에서는 9.64%의 통수손실을 보였으며, 500m 구간의 지선수로에서는 15.55%. 200m 구간의 분선수로에서는 12.34%의 통수손실율을 보였다. (2) 삼투량조사는 지선수로를 40m 간격으로 3번 반복조사에서 2.08cm/day 또 200m 간격의 지선수로에서는 1일 평균 3.37cm/day의 삼투량을 얻었다. (3) 단 1회의 결과치를 객관성 있게 취급은 곤난하며 종래에 사용해 온 결과치보다는 손실과 삼투가 공히 상당히 큰 값을 보여주고 있어 좀 더 자세한 연구가 필요하다.

• 한국대기환경학회지
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• 제19권6호
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• pp.689-699
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• 2003

This study was to examine characteristics of treating toluene vapor, which gets to be problematic due to its harmful carcinogenicity and mass generation from various sources, through a biological treatment facility which is environment-friendly and adopts a high-efficient and low-cost clean technology. In order to identify whether Alnus Firma Fruit (AFF) can be used as a media for a bioreactor, its utility and basic operating factors, a study was conducted on pressure drop, supply of nutrient substances and retention time which are operating factors of a biofilter, and eliminating characteristics were compared between AFF and the conventional biological activatedcarbon (BAC) widely used as filter media. In the case of AFF, the initial microbial deposits was 2.3${\times}$10$^{7}$ CFU/g dry AFF, which represents the initial microbial density higher than the case of BAC showing 5.5${\times}$10$^{6}$ CFU/g dry BAC And it took about 2 weeks to acclimate until its eliminating rate got to be increased over 90%. As a result of comparing pressure loss taking place with the lapse of time between BAC and AFF, after 130 days passed at SV 25h$^{-1}$ , BAC showed that its eliminating efficiency had a tendency to drop greatly due to a great pressure loss (0.53\longrightarrow54.7 mm$H_2O$/m) caused by an excess of biomass as accumulated. On the other hand. AFF showed that the pressure drop was 0.53 mm$H_2O$/m, about 2 times as much as the initial pressure loss of 0.4 mm$H_2O$/m, which represents no great change in the pressure loss, and its eliminating efficiency was also shown to be continuously high. Therefore, when AFF was used as a filler for a biological treatment facility, a biological filter enabling improvement of the purifying efficiency to be promoted could be provided, and moreover, the pressure loss was so small that the filler replacement cycle or the back flushing cycle could be extended. So, even in terms of the operating cost, it was identified to be an economical filler When an inorganic material was used as a filler, the biofilters performance acted sensitively on whether nutrient substances were supplied or not. In the case of AFF with low adsorptivity, addition of ethyl-alcohol increased the solubility of toluene, and consequently, biodegradation got to be actively made by microbes, and thus, its eliminating rate could be increased. As the flow velocity and the inflow concentration got to be more increased, its eliminating rate got to be lower, and particularly, an increase in the flow velocity made its eliminating rate drop more greatly than an increase in the concentration.