• International Journal of Concrete Structures and Materials
• /
• 제9권4호
• /
• pp.487-498
• /
• 2015

A proper initial curing is a very simple and inexpensive alternative to improve concrete cover quality and accordingly extend the service life of reinforced concrete structures exposed to aggressive species. A current study investigates the effect of wet curing duration on chloride penetration in plain and blended cement concretes which subjected to tidal exposure condition in south of Iran for 5 years. The results show that wet curing extension preserves concrete against high rate of chloride penetration at early ages and decreases the difference between initial and long-term diffusion coefficients due to improvement of concrete cover quality. But, as the length of exposure period to marine environment increased the effects of initial wet curing became less pronounced. Furthermore, a relationship is developed between wet curing time and diffusion coefficient at early ages and the effect of curing length on time-to-corrosion initiation of concrete is addressed.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
• /
• pp.307-311
• /
• 2006

Chemical analyses were conducted for Nakdong River water and riverbank filtrate in Daesan-Myeon area, Changwon City in 2005. Chemical components show different trends in wet season (June, July, August and September) and dry season (the other months). The patterns of chemical variation are classified into four types. Chemical components belonging Type I, as Na and $HCO_3$, show decrease in concentration during wet season and increase in concentration during dry season for both Nakdong River water and the riverbank filtrate. Chemical components belonging Type II, as Mg and $SO_4$, show decrease in concentration during wet season and increase in concentration during dry season for Nakdong River water while show the opposite trend for the riverbank filtrate. Chemical components belonging Type III, as Cl and $NO_3$, show increase in concentration from the start of wet season and high concentration during dry season for both Nakdong River water and the riverbank filtrate. Chemical components belonging Type IV, as Fe, show increase in concentration during wet season and decrease in concentration during dry season for both Nakdong River water and the riverbank filtrate.

• 한국대기환경학회지
• /
• 제19권2호
• /
• pp.217-229
• /
• 2003

The amounts of nitrogen and sulfur deposited in the region of the Yellow Sea in both dry and wet forms were estimated by using the measurement data published in tile literature during tile past 10 years. In the estimation of dry deposition, concentrations at ground stations including those at a station on the Chinese side and concentrations from shipboard and aircraft measurements were used as well as deposition velocities. Wet deposition flux was determined at ground stations on the Korean side either by taking the flux data themselves or by calculating them from precipitation data in the literature. The dry deposition flux over the Yellow Sea was much greater than those China was confirmed from the fact that the total amount summing wet and dry depositions exceeded the emission amount from Korea. Dry deposition was principally made in the gaseous form due to a larger deposition velocity. Nevertheless, since the deposition velocity over water was smaller than that over the ground, dry deposition of oxidized nitrogen was smaller than wet deposition. As a whole, wet depositions of nitrogen and sulfur were 2.3 and 1.9 times 1arger than corresponding dry depositions, respectively.

• 한국식품위생안전성학회지
• /
• 제33권1호
• /
• pp.83-88
• /
• 2018

시중에 유통 중인 물휴지 62 품목을 선정하여 살균보존제 성분 및 유해물질 함유 여부 등의 안전성을 조사하였다. 일반적으로 화장품 및 식품에 가장 많이 사용하는 살균 보존제인 안식향산나트륨은 46 품목에서 200~3500 ppm 검출되었고 파라벤류는 1 품목에서 파라옥시안식향산메칠이 9 ppm 검출되었다. 사용할 수 없는 살균보존제인 메칠클로로이소치아졸리논과 메칠이소치아졸리논(3:1)혼합물이 1 품목에서 검출되어 부적합 판정되었으며, 메칠클로로이소치아졸리논 5 ppm, 메칠이소치아졸리논 140 ppm 검출되었다. 염화세틸피리디늄은 5 품목에서 7~13 ppm 검출되었으며, 모두 허용기준 이내로 나타났다. 잔류유해물질인 포름알데히드 검사결과는 $0.069{\sim}1.796{\mu}g/g$로 허용기준인 $20{\mu}g/g$ 이하였다. 메탄올은 5~51 ppm 검출되었으며, 이 중 4 품목에서 허용기준인 20 ppm보다 2배 이상의 농도가 나타났다. 안전한 제품이 유통될 수 있도록 메탄올의 잔류경로에 대한 지속적인 조사 및 모니터링이 필요하다고 판단된다. 물휴지의 pH를 측정한 결과 4.0~8.2로 나타나 유통화장품의 pH 3.0~9.0 기준에 적합하였으나, 물휴지에는 pH 기준이 설정되어 있지 않으므로 안전관리를 위해서는 pH 기준을 설정하는 고시개정이 필요할 것이다.

• 농촌지도와개발
• /
• 제24권2호
• /
• pp.99-115
• /
• 2017

The purpose of this study is to analyze potential adoption rates and reusing patterns of the new rice direct seeding technology. The model constructed and employed in this study is a system dynamics model of farmer adoption and reusing patterns for this new technology over time. The model incorporates a causal loop diagram that explains interactions among rice cultivation subsystems with feedback loops and further attempts to build a causal loop model with stock-flow diagram for computer simulation. As one example of how the model can be used to provide insight to rice farmers, simulations are run over varying levels on the cultivation process of rice. The major finding is to demonstrate the utility of system dynamics simulation methodology in aiding the rice wet direct seeding farmers' decision making.

• 한국대기환경학회:학술대회논문집
• /
• 한국대기환경학회 2004년도 춘계학술대회 논문집
• /
• pp.135-136
• /
• 2004

• Journal of Korean Society for Atmospheric Environment
• /
• 제21권E3호
• /
• pp.87-94
• /
• 2005

Wet scavenging by rain drops is a most important removal process of air pollutants. In order to study the scavenging mechanisms of aerosol particles, the characteristics of chemical components in the rain water were examined as a function of the amount of rainfall. Rain water were collected continuously and separated into the soluble and insoluble components. The elemental concentrations in both components were determined by a PIXE analysis. The physical and chemical characteristics of atmospheric aerosols during the rainfall events were measured simultaneously. The elemental concentrations in rain water decreased substantially just after rain started and then gradually declined in subsequential rain fall exceeding 1.0 mm. The large particles were scavenged more easily than the fine particles. Fe, Ti and Si in rain water were in high insoluble state. Contrarily, almost whole of S was dissolved in rain water.

• Asian Journal of Atmospheric Environment
• /
• 제8권2호
• /
• pp.69-80
• /
• 2014

It is often assumed that atmospheric observations at remote sites represent long-range transport of airborne material, and local influences are overlooked. We evaluated the impact of local input on the rainwater composition at Gosan Station, a strategic site for monitoring the continental outflow from Asia. We analyzed a 14-year record of rainwater chemical composition archived by the Korea Meteorological Administration and detected local terrestrial contribution for nitrate, sulfate and ammonium. We also measured the chemical composition of rainwater sampled simultaneously at multiple locations within the premises of the Gosan Station, from which local influence with meter-scale spatial heterogeneity could be discerned. We estimate that the local input accounted for at least ~10% of the wet deposition of nitrogen and ~12% of the wet deposition of sulfur during the 14 years. This highlights the significance of the local influence, which should be carefully assessed when interpreting atmospheric observations at this site.

• Computers and Concrete
• /
• 제3권2_3호
• /
• pp.145-161
• /
• 2006

This article involves architecting prototype-fuzzy expert system for designing the nominal cover thickness by means of fuzzy inference for quantitatively representing the environment affecting factor to reinforced concrete in chloride-induced corrosion environment. In this work, nominal cover thickness to reinforcement in concrete was determined by the sum of minimum cover thickness and tolerance to that defined from skill level, constructability and the significance of member. Several variables defining the quality of concrete and environment affecting factor (EAF) including relative humidity, temperature, cyclic wet and dry, and the distance from coast were treated as fuzzy variables. To qualify EAF the environment conditions of cycle degree of wet-dry, relative humidity, distance from coast and temperature were used as input variables. To determine the nominal cover thickness a qualified EAF, concrete grade, and watercement ratio were used. The membership functions of each fuzzy variable were generated from the engineering knowledge and intuition based on some references as well as some international codes of practice.

• 한국염색가공학회지
• /
• 제18권6호
• /
• pp.57-62
• /
• 2006

The functional non-woven fabrics have been applied in various industry fields, such as clothing, hygiene, environment, medical and so forth. The functional non-woven fabrics for wet tissue were manufactured by meltblown and wet tissue finishing processes. The wet tissue was contained the various composition substances such as Benzalkonium Chloride(0.2292g), lodo-2-propynyl Butyl carbamate(0.0069g) and 5-Chloro-2-Methyl-Isothiazolin -3-one, 2-Methyl-Isothiazolin-3-one (0.0034g) with purified water (999.76g). In this study, the functional wet tissue based on meltblown nonwovens has been applied in dairy cattle for prevention on cow mastitis. Mastitis is the most costly disease results in lost milk production, decreased milk quality, milk discard, early culling of cows, drug costs and labor costs in dairy cattle. Therefore, this study was investigated to evaluate clinical effect of the functional wet tissue in mastitis control. The results, after experiment the functional wet tissue used group, demonstrated that the infection rate, cure rate and mean somatic cell count(SCC) were significantly decreased as compared to the control group.