• Asian Journal of Atmospheric Environment
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• 제11권3호
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• pp.202-216
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• 2017

Nitrogen (N) is an essential macronutrient. Thus, evaluating its flows and stocks in rice paddy ecosystems provides important insights into the sustainability and environmental loads of rice production. Among the N sources of paddy fields, atmospheric deposition and irrigation inputs remain poorly understood. In particular, insufficient information is available for atmosphere-rice paddy exchange of gaseous and particulate reactive N (Nr, all N species other than molecular N) which represents the net input or output through dry deposition and emission. In this study, we assessed the N inputs via atmospheric deposition and irrigation to a Japanese rice paddy area by weekly monitoring for 2 years with special emphasis on gas and particle exchange. The rice paddy during the cropping season acted as a net emitter of ammonia ($NH_3$) to the atmosphere regardless of the N fertilizer applications, which reduced the effects of dry deposition to the N input. Dry N deposition was quantitatively similar to wet N deposition, when subtracting the rice paddy $NH_3$ emissions from N exchange. The annual N inputs to the rice paddy were 3.2 to $3.6\;kg\;N\;ha^{-1}\;yr^{-1}$ for exchange, 8.1 to $9.8\;kg\;N\;ha^{-1}\;yr^{-1}$ for wet deposition, and 11.1 to $14.5\;kg\;N\;ha^{-1}\;yr^{-1}$ for irrigation. The total N input, 22.8 to $27.5\;kg\;N\;ha^{-1}\;yr^{-1}$, corresponded to 38% to 55% of the N fertilizer application rate and 53% to 67% of the brown rice N uptake. Monitoring of atmospheric deposition and irrigation as N sources for rice paddies will therefore be necessary for adequate N management.

• International Journal of Concrete Structures and Materials
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• 제8권3호
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• pp.185-199
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• 2014

As the national transportation infrastructure ages and deteriorates, many existing bridges require frequent and costly maintenance and repairs. The objective of this work was to synthesize new and existing types of beam end coatings and treatments that have been proven to extend the life of new and existing concrete and steel bridge beams. A comprehensive literature review, along with online surveys and phone interviews of State department of transportations (DOTs) and coating manufacturers was conducted to gather information about existing and recently developed technologies. The study revealed that while many promising coatings and treatments are offered on the market, there is a lack of readily available laboratory results that would enable direct comparison of the available methods. This finding applies in terms of the coatings' durability and the potential for extending the service life of existing bridges. Most of the interviewed State DOTs' personnel assessed the products listed in respective DOT's Qualified Products Lists as performing 'well'. However, there was significant variability between states in the type of the products used. Among the agencies contacted, none was able to suggest the most promising or advanced products, either for concrete or steel bridge beam end treatments. This suggests that comprehensive laboratory evaluation would be necessary for selecting the best available beam end treatments and coatings.

• Computers and Concrete
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• 제25권1호
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• pp.1-14
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• 2020

This study presents applications of the multivariate adaptive regression splines (MARS) method for predicting the ultimate loading carrying capacity (N_u) of rectangular concrete-filled steel tubular (CFST) columns subjected to eccentric loading. A database containing 141 experimental data was collected from available literature to develop the MARS model with a total of seven variables that covered various geometrical and material properties including the width of rectangular steel tube (B), the depth of rectangular steel tube (H), the wall thickness of steel tube (t), the length of column (L), cylinder compressive strength of concrete (f'_c), yield strength of steel (f_y), and the load eccentricity (e). The proposed model is a combination of the MARS algorithm and the grid search cross-validation technique (abbreviated here as GS-MARS) in order to determine MARS' parameters. A new explicit formulation was derived from MARS for the mentioned input variables. The GS-MARS estimation accuracy was compared with four available mathematical methods presented in the current design codes, including AISC, ACI-318, AS, and Eurocode 4. The results in terms of criteria indices indicated that the MARS model was much better than the available formulae.

• Journal of Ecology and Environment
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• 제37권1호
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• pp.13-19
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• 2014

The effect of different turnover time of water on the decomposition of emergent macrophyte litter (Zizania latifolia Griseb.) was investigated using a microcosm experiment. Microcosm treatment represented different turnover time of water; 1, 2, 4 and 8 weeks. The litterbags from each treatment were retrieved every 2 weeks until the 8th week and the water simultaneously sampled with the litterbag. The dry weight and the content of major cations in the litter, and the content of available N, P, and major cations in the water were analyzed. Dry weight loss after 8 weeks indicated the lower decay rates under the condition of short turnover time of water. Major cations from the litter and the water showed that the leached amounts of K and Mg from the litter were highest in the 2nd week and dramatically decreased from the 4th week. The dynamics of available nitrogen and phosphorus in the water showed that as the water turnover time was getting longer, the amounts of available nitrogen and phosphorus remained higher. These results suggest that wetlands with longer turnover time of water could maintain the increased nitrogen and phosphorus and no outflow of the nutrients could cause eutrophication problem.

• Geomechanics and Engineering
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• 제21권6호
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• pp.583-598
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• 2020

This study is attempted to propose a new hybrid artificial intelligence model called integrative genetic algorithm with multivariate adaptive regression splines (GA-MARS) for settlement prediction of shallow foundations on sandy soils. In this hybrid model, the evolution algorithm - Genetic Algorithm (GA) was used to search and optimize the hyperparameters of multivariate adaptive regression splines (MARS). For this purpose, a total of 180 experimental data were collected and analyzed from available researches with five-input variables including the bread of foundation (B), length to width (L/B), embedment ratio (D_f/B), foundation net applied pressure (q_net), and average SPT blow count (N_SPT). In further analysis, a new explicit formulation was derived from MARS and its accuracy was compared with four available formulae. The attained results indicated that the proposed GA-MARS model exhibited a more robust and better performance than the available methods.

• Wind and Structures
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• 제28권5호
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• pp.271-284
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• 2019

This paper describes the application of a novel virtual prototyping methodology to wind turbine blade design. Numeric modelling data and experimental data about turbine blade geometry and structural/dynamical behaviour are combined to obtain an affordable digital twin model useful in reducing the undesirable uncertainties during the entire turbine lifecycle. Moreover, this model can be used to track and predict blade structural changes, due for example to structural damage, and to assess its remaining life. A new interactive and recursive process is proposed. It includes CAD geometry generation and finite element analyses, combined with experimental data gathered from the structural testing of a new generation wind turbine blade. The goal of the research is to show how the unique features of a complex wind turbine blade are considered in the virtual model updating process, fully exploiting the computational capabilities available to the designer in modern engineering. A composite Sandia National Laboratories Blade System Design Study (BSDS) turbine blade is used to exemplify the proposed process. Static, modal and fatigue experimental testing are conducted at Clarkson University Blade Test Facility. A digital model was created and updated to conform to all the information available from experimental testing. When an updated virtual digital model is available the performance of the blade during operation can be assessed with higher confidence.

• 한국토양비료학회지
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• 제14권4호
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• pp.242-249
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• 1982

카드뮴의 해독(害毒)을 경감(輕減)하는데 필요(必要)한 기초지식(基礎知識)을 얻기 위(爲)하여 카드뮴이 처리(處理)된 토양(土壤)에 석회물질(石灰物質)과 개량제(改良劑)를 사용(使用)한 것과 이미 석회(石灰)가 사용(使用)된 토양(土壤)에 Cd를 처리(處理)한 것을 분(盆)에 담아서 1981년(年) 여름 또는 가을에 자연토양수분조건하(自然土壤水分條件下)에 묻고 처리후(處理后) 40일(日)~70일(日)사이에 토양시료(土壤試料)를 채취분석(採取分析)한 결과(結果)는 다음과 같다. 1. 카드뮴은 토양(土壤)을 0.1N-HCl나 2%구연산으로 침출(浸出)했을 때에 많고, $N-AcNH_4$로 침출(浸出)했을때 적었으며 물로 침출(浸出)했을 때는 나오지 않았다. 침출(浸出)된 카드뮴의 처리간(處理間) 차이(差異)는 $N-NH_4A$ 침출(浸出)에서 가장 뚜렷하여 이것을 유효카드뮴으로 할 수 있을 것 같다. 2) 치환성(置換性)카드뮴을 줄이는데 가장 유효한 것은 수산화(水酸化)카드뮴이며 탄산(炭酸)카드뮴, 규산(珪酸)카드뮴의 순서(順序)로 효과가 적어졌다. 3. 과석(過石)도 치환성(置換性)카드뮴을 줄였는데 인산(燐酸)카드뮴을 침전(沈澱)시키기 때문으로 판단(判斷)되었다. 4. 치환성(置換性)카드뮴은 토양(土壤)의 pH 6.0~6.5에서 많고 그 이하(以下)나 이상(以上)에서 적었다. pH 5.0이하(以下)에서는 $Mn^{+{+}}$으로 인(因)한 $Cd^{+{+}}$의 침전(沈澱)때문이고, pH 6.0이상(以上)에서는 수산화(水酸化)카드뮴의 침전(沈澱)때문으로 판단(判斷)되었다.

• 청정기술
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• 제22권4호
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• pp.274-280
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• 2016

본 연구에서는 태양광용 웨이퍼를 제조하는 과정에서 발생하는 실리콘 폐슬러지의 함유물질 중 공정원가의 25% 가량을 차지하고 있는 절삭유를 화학적으로 재생하기 위한 방법을 개발하고자 하였다. 이를 위해 아세톤, HCl, NaOH, KOH, $Na_2CO_3$, 불산, 염화메틸렌 등 7종류의 시약이 이용되었으며 다양한 농도로 폐슬러지와 반응을 실시하고 3000 rpm의 속도로 60분간 원심분리를 수행하였다. 그 결과, 실리콘분말 및 금속분말과 같은 고형물과 액상의 절삭유를 분리하기 위한 최적 시약 및 조건이 0.3 N NaOH로 확인되었다. 시판되는 절삭유의 약산성 특성에 맞게 pH 조절이 요구되어 금속분말 제거에 효과적인 0.1 N HCl과 폐슬러지를 먼저 반응시킨 후 0.3 N NaOH로 후처리 한 재생 절삭유의 pH가 6.05로 나타났으며 0.3 N NaOH 단독으로 폐슬러지에 적용하였을 때 보다 우수한 탁도를 나타내었다. 시판용 절삭유와의 특성을 비교하고자 FT-IR 분석을 실시한 결과, 재생유로서의 가능성이 확인되었으며 실험을 통하여 얻어진 절삭유 회수율은 86.9%로 나타났다.

• 한국토양비료학회지
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• 제34권2호
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• pp.110-116
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• 2001

벼 2모작 재배시 보릿짚시용후 질소시용량별 토양의 이화학적 변화와 수도체의 양분흡수량, 질소이용효율을 조사하기 위하여 2년간('97~'98) 전북통에서 시험한 결과는 다음과 같다. 보릿짚시용으로 경도, 용적밀도, 고상율이 낮아졌고 공극율과 기상율이 증가하여 토양의 물리성이 개선되었다. 보릿짚시용으로 벼 재배후 토양의 pH, OM, T-C, $SiO_2$, K, CEC가 증가한 반면 $P_2O_5$이 감소되었다. 보릿짚시용후 벼 재배시 토양중 $Fe^{+{+}}$함량은 분얼기~유수형성기까지 높은 함량을 보였으나 출수기에는 낮아졌고 $Mn^{+{+}}$함량은 증가되었다. 보릿짚시용시 수도체로의 시비질소 흡수량은 질소시용량 $126kg\;ha^{-1}$ 시용구까지는 증가하였으나 질소 $144kg\;ha^{-1}$ 시용구에서는 감소되었다. 또 질소시용량이 적을수록 보릿짚시용구에서 무시용구보다 시비질소 흡수기간이 길었다. 수도체로의 질소이용율은 분얼기에는 1% 전후였지만 최고분얼기부터 크게 증가하였고 보릿짚시용구에서 낮았다. 수도체로의 인산흡수량은 보릿짚시용구에서 질소시용량에 관계없이 모두 높았으나 칼리함량은 낮았다.

• Preventive Nutrition and Food Science
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• 제3권3호
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• pp.260-266
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• 1998

Selenium contents of infant formulas that were commerically available in Japan and Korean were determined by the method of atomic absorption spectrometry with hydrode generation. Total means of selenium contents were 45.2$\pm$22.1ng/g(n=34) in all the Japaneses formulas and 58.3$\pm$18.9ng/g(n=22) in all the Korean formulas. selecnium contents of milk-based formulas (54.7$\pm$23.2ng/g in Japan, n=20 and 64.8$\pm$12.6ng/g in Korean , n=18) were significantly higher than those of soy-based formulas (36.8$\pm$11.0ng/g in Japanes brands, n=11 and 36.4ng/g in Korean one , N=1). Based on selenium data of these formulas the selenium intakes of infants have been estimated to be about 6.6$\mu\textrm{g}$/day and 8.1$\mu\textrm{g}$/day in Korean by milk-based formula feeding.