• 한국주거학회논문집
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• 제8권3호
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• pp.219-230
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• 1997

Lack of technical standards, specification and inadequate execution in masonry wall construction in Korea lead to produce serious flaw problems such as crack, efflorescene, and upset etc.. The purpose of this paper is to present the practical details for Masonry cavity wall construction to prevent rain penetration and to accommodate differential movement between the inner and outer wythes of cavity walls. Considering rain penetration and differential movement of both wythes of cavity walls, provision of an adequate air space, an airtight back-up wall, clean cavity with weepholes and vents, properly positioned flashing, tie and shelf angle etc. depend on the cavity wall types will help ensure good performance. The present details included noncorrosive hot dip galvanized steel or stainless steel for metal components, plastic and ultra violet resistant polypropylene Copolymer for other components was taken into account the construction method and several types of cavity walls in Korea

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1813-1815
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• 1997

In this study, in order to develop outdoor insulating materials, SIN(simultaneous interpenetrating polymer network) was introduced to Epoxy resin and the environment resistance was investigated. Six kinds of specimen were manufacture by filler($SiO_2$) content. SEM was untilized in order to confirm their network structure changes. Also, tracking test, UV test and acid rain test were carried out investigate the environment resistance characteristic. Therefore it was confirmed that simultaneous interpenetrating polymer network specimens were more excellent than single network structure specimens. But, acid rain almost never changed resistance.

• 환경영향평가
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• 제31권1호
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• pp.1-10
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• 2022

본 연구는 비점오염원 저감시설인 차집시설을 대상으로 다양한 강우조건에 따라 초기우수 유출수의 수질특성을 파악하고, 용존성 오염물질의 기원을 파악하기 위하여 수행되었다. 본 연구는 도시지역 내 위치한 G-배수구역의 10개 차집시설 중 비강우시에도 불명수가 유입되는 것으로 조사된 차집시설 #1, #5, #8, #9 및 #10 등 5개 지점에서 수질분석을 통하여 차집시설에서 비점오염물질의 유출특성을 파악하였다. 연구결과로써 강우량에 따라 차집시설에서 우수유출수의 수질특성에 영향을 받는 것으로 판단되었다. 비강우시 EC, BOD, TOC, TN의 평균농도는 강우시에 비하여 높은 것으로 조사되었으며, DO의 평균농도는 강우시에 비하여 낮은 것으로 조사되었다. 또한, 차집시설에서 유출수의 용존성 유기물은 주로 내부에서 생성된 유기물로 구성된 것으로 판단되었다. 우수유출수는 주변 환경에서 유입되는 오염물질의 영향을 많이 받으며, 강우로 인하여 차집시설의 외부로부터 유입되는 난분해성 휴믹계 물질이 많아진 것으로 판단된다.

• 한국광물학회지
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• 제23권2호
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• pp.99-106
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• 2010

금번 연구에서는 2009년 1월 1일부터 12월 31일 사이에 대전광역시 유성구 지역에서 확보한 강수 시료를 대상으로 강수에 의한 오염 희석 규명을 시도하였다. 강수여과물에 대해 등온잔류자화(Isothermal remanent magnetization) 측정과 현미경 분석 및 정성적인 화학 성분 분석을 실시하였다. 비강수일에 포집한 먼지 시료와 황사발생일에 채취한 먼지 시료도 비교를 위해 실험에 사용하였다. 자화특성 실험과 현미경 관찰 결과를 바탕으로 판단하면, 강수에서 여과된 고체 시료에 존재하는 자성 물질은 자철석이다. 관찰된 자성 물질의 특이한 형태(구형/타원체형)와 탄소 함유를 고려하면, 인위적인 연소에 의해 형성된 자철석이라 해석된다. 강수에서 여과된 고체 시료의 등온잔류자화는 일반 먼지보다도 낮고 황사에 비해서는 현저히 낮은데, 이는 강수에 의해 발생하는 상당한 양의 자성물질 희석 효과라 판단된다.

• Wind and Structures
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• 제23권6호
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• pp.615-639
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• 2016

Although the underlying mechanism of rain-wind induced vibrations (RWIVs) of stay cables has not been fully understood, some countermeasures have been successfully applied to mitigating this kind of vibration. Among these, installing dampers near the bridge deck was widely adopted, and several field observations have shown its effectiveness. In this study, the effectiveness of dampers to RWIVs of stay cables is numerically investigated comprehensively by means of finite difference method (FDM). Based on the free vibration analysis of a taut string, it is found that the 3-points triangle scheme, which can be easily implemented in FDM, can offer an excellent approximation of the concentrated damping coefficient (expressed as a Dirac delta function) at the location where the damper is installed. Then, free vibration analysis of a 3-D continuous stay cable attached with two dampers is carried out to study the relationship of modal damping ratio and damping coefficient of the dampers. The effects of orientation of the dampers and cable sag on the modal damping ratio are investigated in detail. Finally, the RWIV response of a 3-D continuous stay cable attached with two dampers is examined. The results indicate that 0.5% of damping ratio is sufficient to reduce the RWIV vibration of the Cable A20 on the No.2 Nanjing Bridge over Yangtze River.

• Journal of Astronomy and Space Sciences
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• 제31권4호
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• pp.325-333
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• 2014

We are motivated by both the accumulating evidence for the connection of solar variability to the chemistry of nitrogen oxide in the atmosphere and recent finding that the Galactic cosmic-ray (GCR) influx is associated with the solar north-south asymmetry. We have analyzed the measured pH in precipitation over the 109 stations distributed in the United States. We have found that data of pH in precipitation as a whole appear to be marginally anti-correlated with the solar asymmetry. That is, rain seems to become less acidic when the southern hemisphere of the Sun is more active. The acidity of rain is also found to be correlated with the atmospheric temperature, while not to be correlated with solar activity itself. We have carried on the analysis with two subsamples in which stations located in the east and in the west. We find that the pH data derived from the eastern stations which are possibly polluted by sulfur oxides and nitrogen oxides are not correlated with the solar asymmetry, but with the temperature. On the contrary, the pH data obtained from the western stations are found to be marginally anti-correlated with the solar asymmetry. In addition, the pH data obtained from the western stations are found to be correlated with the solar UV radiation. We conclude by briefly pointing out that a role of the solar asymmetry in the process of acidification of rain is to be further examined particularly when the level of pollution by sulfur oxides and nitrogen oxides is low.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권5호
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• pp.82-89
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• 2011

Understanding snowmelt movement to the watershed is crucial for both climate change and hydrological studies because the snowmelt is a significant component of groundwater and surface runoff in temperature area. In this work, a new energy balance budget algorithm has been developed for melting snow from a snowpack at the Central Sierra Snow Laboratory (CSSL) in California, US. Using two sets of experiments, artificial rain-on-snow experiments and observations of diel variations, carried out in the winter of 2002 and 2003, we investigate how to calculate the amount of snowmelt from the snowpack using radiation energy and air temperature. To address the effect of air temperature, we calculate the integrated daily solar radiation energy input, and the integrated discharge of snowmelt under the snowpack and the energy required to generate such an amount of meltwater. The difference between the two is the excess (or deficit) energy input and we compare this energy to the average daily temperature. The resulting empirical relationship is used to calculate the instantaneous snowmelt rate in the model used by Lee et al. (2008a; 2010), in addition to the net-short radiation. If for a given 10 minute interval, the energy obtained by the melt calculation is negative, then no melt is generated. The input energy from the sun is considered to be used to increase the temperature of the snowpack. Positive energy is used for melting snow for the 10-minute interval. Using this energy budget algorithm, we optimize the intrinsic permeability of the snowpack for the two sets of experiments using one-dimensional water percolation model, which are $52.5{\times}10^{-10}m^2$ and $75{\times}10^{-10}m^2$ for the artificial rain-on-snow experiments and observations of diel variation, respectively.

• Applied Science and Convergence Technology
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• 제26권6호
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• pp.218-222
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• 2017

This study was conducted to remove $NO_x$, which is the main cause of fine dust and air pollution as well as acid rain. $NO_x$ was tested using 3% NO (diluted in He) as a simulated gas. Experiments were sequentially carried out by oxidizing NO to $NO_2$ and absorbing $NO_2$. Especially, we focused on the changes of NO oxidation according to both oxidant ($NaClO_2$) concentration change (1~10 M) and oxidant pH change (pH = 1~5) by adding HCl. In addition, we tried to suggest a method to improve $NO_2$ absorption by conducting $NO_2$ reduction reaction with reducing agent (NaOH) concentration (40~60%). It was found that NO removal efficiency increased as both concentration of oxidant and flow rate of NO gas increased, and NO decreased more effectively as the pH of hydrochloric acid added to the oxidant was lower. The $NO_2$ adsorption was also better with increasing NaOH concentration, but the NO removal efficiency was ~20% lower than that of the selective NO reduction. Indeed, this experimental method is expected to be a new method that can be applied to the capture and removal of fine dust caused by air pollution because it is a method that can easily remove NO gas by a simple device without expensive giant equipment.

• 생명과학회지
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• 제15권6호
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• pp.889-894
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• 2005

인공산성비를 애기장대 (Arabidopsis thaliana)에 처리하였을 때 나타나는 줄기와 잎의 생장 변화와 내부구조의 형태변화를 광학현미경으로 관찰하였다. pH 3.0의 인공산성비를 애기장대에 15일 동안 직접 처리한 식물의 줄기 생장은 산성비를 처리하지 않은 정상식물의 줄기 생장과 거의 차이가 없었으며, 외형적인 형태변화도 관찰되지 않았다. 인공산성비를 처리한 식물 줄기의 내부구조는 정상식물 줄기에 비하여 표피조직과 피층 조직이 일부분 파괴되어 산성비에 의한 피해가 있었음이 관찰되었다. 인공산성비를 처리한 식물의 잎 생장은 정상식물 및 생장과 비교하여 차이가 거의 나타나지 않았으나, 외형적인 형태에서는 변화가 관찰되었다. 인공산성비를 처리한 식물의 잎 표면에서는 상표피의 많은 부위에서 흰 괴사반점이 뚜렸하게 관찰되었다. 인공산성비에 의하여 괴사반점이 나타난 잎의 내부조직을 광학현미경으로 관찰한 결과, 잎 표피세포는 큐티클층이 파괴되어 압착되었고 엽육 조직의 세포들도 역시 심하게 파괴되어 수축된 반면에 유관속 조직의 구조적 변화는 거의 관찰되지 않았다.

• 한국농공학회논문집
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• 제61권3호
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• pp.101-112
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• 2019

This study developed selection criteria of small-scales reservoirs, having under $300,000m^3$ storage capacity, for the Emergency Action Plan(EAP) establishment in order to reduce the disaster risks of the reservoir's failures. Those reservoirs are out of ranges of Korean EAP establishment standard, but have potential risk of disasters as they have often failed by the recent extreme rainfall events and earthquakes, causing economical and life losses. The problem of reservoir aging is also one of the reasons of them. In this study, the developed selection criteria of small reservoirs for EAP establishment are storage capacity, embankment height, reservoir age, heavy rain factor and earthquake factor. These criteria were selected based on the review of the existing EAP establishment guidelines, analysis of the past dam failure cases, and the previous related studies. The quantification of these criteria were conducted for the practical applications in the fields, and applied to 67 previous failures in order to investigate the relation of each criteria with these failures. The earthquake factor found to be the highest relations followed by heavy rain factors, combination of earthquake and heavy rain factors, and reservoir age. The classification was made as observation and review groups for EAP establishments based on overlapping numbers of each criteria. This classifications applied to 354 reservoirs designated as having the potential disaster risk by MOIS, and showed 38.4% of observation and 11.9% of review groups. Anticipatory monitoring and regular inspection should be made by professional facility managers for the observation group, and necessity of EAP establishment should be assessed for the review group based on the downstream status and financial budget.