• Interaction and multiscale mechanics
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• 제4권3호
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• pp.187-206
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• 2011

Accurate estimations of pre-failure deformations and post-failure responses of geostructures require that the simulation tool possesses at least three main ingredients: 1) a constitutive model that is able to describe the macroscopic stress-strain-strength behavior of soils subjected to complex stress/strain paths over a wide range of confining pressures and densities, 2) an embedded length scale that accounts for the intricate physical phenomena that occur at the grain size scale in the soil, and 3) a computational platform that allows the analysis to be carried out beyond the development of an initially "contained" failure zone in the soil. In this paper, a two-scale micropolar plasticity model will be used to incorporate all these ingredients. The model is implemented in a finite element platform that is based on the mechanics of micropolar continua. Appropriate finite elements are developed to couple displacement, micro-rotations, and pore-water pressure in form of $u_n-{\phi}_m$ and $u_n-p_m-{\phi}_m$ (n > m) elements for analysis of dry and saturated soils. Performance of the model is assessed in a biaxial compression test on a slightly heterogeneous specimen of sand. The role of micropolar component of the model on capturing the post-failure response of the soil is demonstrated.

• Steel and Composite Structures
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• 제18권5호
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• pp.1215-1237
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• 2015

The majority of connections in moment resisting frames are considered as being fully-rigid. Consequently, the real behavior of the connection, which has some level of flexibility, is ignored. This may result in inaccurate predictions of structural response. This study investigates the influence of flexibility of the extended end-plate connections in the steel moment frames. This is done at two levels. First, the actual micro-behavior of extended end-plate moment connections is explored with respect to joint flexibility. Then, the macro-behavior of frames with end-plate moment connections is investigated using modal, nonlinear static pushover and incremental dynamic analyses. In all models, the P-Delta effects along with material and geometrical nonlinearities were included in the analyses. Results revealed considerable differences between the behavior of the structural frame with connections modeled as fully-rigid versus those when flexibility was incorporated, specifically difference occurred in the natural periods, strength, and maximum inter-story drift angle.

• Architectural research
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• 제9권2호
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• pp.37-45
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• 2007

The proliferation of the House Dust Mite(HDM) is affected by temperature, humidity, ventilation, etc. Measuring temperature and humidity was performed at the very location where dust samplings take place and where they live in reality together with temperature and humidity of the ambient of the room. There has been discussion over the key environment factor of HDM survival; absolute humidity or relative humidity. It seems that relative humidity is the more important determinant for the mite's survival through the analysis of previous studies. Temperature, humidity, ventilation rate and Der P1 were measured in 4 flats in London. Mite allergen was detected in every house. Levels of Der P1 varied between <100ng/g and 22,778ng/g. Flats with high relative humidity(>50%) and poor ventilation(<0.5ach) showed higher levels of mite allergen than flats with lower humidity and adequate air change rate. Questionnaire survey was conducted and the result helped to confirm the findings from monitoring of environmental factors and the dust sampling.

• Transactions on Electrical and Electronic Materials
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• 제18권1호
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• pp.25-29
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• 2017

This paper presents a unique pressure sensor design for environmental applications. The design uses a new geometry for a multi bossed beam-membrane structure with a SOI (silicon-on-insulator) substrate and a mechanical transducer. The Intellisuite MEMS CAD design tool was used to build and analyze the structure with FEM (finite element modeling). The working principle of the multi bossed beam structure is explained. FEM calculations show that a sensing diaphragm with Mises stress can provide superior linear response compared to a stress-free diaphragm. These simulation results are validated by comparing the estimated deflection response. The results show that, the sensitivity is enhanced by using both the novel geometry and the SOI substrate.

• 자원환경지질
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• 제55권6호
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• pp.597-616
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• 2022

The Chungnam basin is a crucial area for studying the Mesozoic crustal evolutionary history of the Korean Peninsula. This study reports the revised geology and new isotopic ages from the northeastern Chungnam Basin based on detailed geological mapping and LA-ICP-MS zircon U-Pb analysis. Our renewed geologic map defines intra-basin, basin-bounding, and basement fault systems closely related to hydrothermal gold-bearing quartz vein injections. Here, we propose the directions of (micro)structural and geochronological future work to address issues on the relationship between the tectonic process, basin evolution, and hydrothermal fluid migration in the southwestern Korean Peninsula.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권1호
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• pp.9-18
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• 2010

In this study, Solid-phase micro-extraction (SPME) with Gas Chromatograph using Flame Ionization Detector (GC/FID) was studied as a possible alternative to liquid-liquid extraction for the analysis of Methyl tert-butyl ether (MTBE) and Tertiary-butyl ether (TBA) in water and an optimization condition of trace analysis of MTBE and TBA using the design of experiment (DOE) was described. The aim of our research was to apply experimental design methodology in the optimization condition of trace analysis of fuel oxygenated compounds in soil-phase microextraction with GC/FID. The reactions of SPME were mathematically described as a function of parameters of Temp ($X_1$), Volume ($X_2$), Time ($X_3$) and Salt ($X_4$) being modeled by the use of the partial factorial designs, which was used for fitting 2nd order response surface models and was alternative to central composite designs. The model predicted agreed with the experimentally observed result ($Y_1$(MTBE, $R^2$ = 0.96, $Y_2$ (TBA, $R^2$ = 0.98)). The estimated ridge of the expected maximum responses and optimal conditions for MTBE and TBA were 278.13 and (Temp ($X_1$) = $48.40^{\circ}C$, Volume ($X_2$) = 73.04 mL, Time ($X_3$) = 11.51 min and Salt ($X_4$) = 12,50 mg/L), and 127.89 and (Temp ($X_1$) = $52.12^{\circ}C$, Volume ($X_2$) = 88.88mL, Time ($X_3$) = 65.40 min and Salt ($X_4$) = 12,50 mg/L), respectively.

• The Journal of Asian Finance, Economics and Business
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• 제7권12호
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• pp.1215-1224
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• 2020

Micro, Small and Medium Enterprises in Denpasar City still face low mastery of technology and financial management, one of which is the application of technology-based accounting information systems (e-commerce) for small and medium enterprises. The research objective was to determine the relationship between environmental uncertainty, trust and ease of information technology moderating behavior in accounting information systems. Research with a quantitative approach, the method used is multiple linear regression with moderated regression analysis. The study population was 816 small and medium enterprises. The sampling method technique was the incidental sampling approach and the Slovin formula so that a sampling of 100 small and medium enterprises that had used e-commerce was determined in the city of Denpasar. The results of research that have been conducted determine the relationship between user behavior in accounting information systems that affect individual performance, the relationship between environmental uncertainty affects accounting information systems mediated by individual performance, while the ease of information technology and its ability to be mediated by individual performance has an effect on the behavior of using accounting information systems. The application of accounting information systems in small and medium enterprises is expected to improve individual performance so as to increase income.

• 한국환경과학회지
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• 제14권1호
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• pp.71-80
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• 2005

Soil is one of the most fundamental elements as well as with water and air in studies associated with the environment, in addition, it is one of the important environmental mediums that constructs a basis of the bio­logical system and performs various roles of matter circulation. This study was carried out in Seoul, in May 2000 to evaluate variation in the concentration levels and distribution characteristics for PAH compounds in soil. Soil samples were collected from 33 sites covering traffic, factory, incineration and mountain groups and the PAHs were analyzed. The results show a wide dis­tribution range of PAHs concentrations between 14.66 ng/g and 1,219.35 ng/g. The highest concentration levels exist at Sungsu-2 of the factory group (FS-2). Daemo-3 of the Mountain group (MD-3) presents the lowest levels as compared with the other sites. PAH compounds including mutagenic and carcinogenic materials show high concentrations in the traffic and factory groups and a high ratio in the mountain group. Besides, these compounds absorbed with micro particles might be spread out over a wide region associated with particles' movement and diffusion. After principal component analysis of the soil samples, the results indicated that the sources of PAHs in the soil were divided into two groups, pesticides and vehicles.

• 한국지반환경공학회 논문집
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• 제22권12호
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• pp.59-63
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• 2021

본 연구는 대심도 조건의 고효율 그라우팅 기술개발을 위한 그라우트재 배합비를 제시한 것으로써 연구에 사용된 1종 보통 포틀랜드 시멘트(OPC)와 마이크로 시멘트(S8000-E)의 배합별 특성과 첨가제 효과를 점도 실험, 입경분석 실험, Gel-Time 실험, 일축압축강도 실험을 통해 확인하였다. 점도실험 결과 점도적인 측면에서 고려하였을 때 OPC가 유리하지만 입경 분석을 통한 암반 절리 간격 통과 고려 시 S8000-E가 적합하다는 것을 확인할 수 있었다. Gel-Time 실험 결과 OPC보다 S8000-E에서 효율적인 값을 나타내었으며 실리카퓸(SF) 적용 시에도 그라우트재로서 주입에는 문제가 없음을 확인하였다. 일축압축강도 시험결과 실리카퓸(SF) 함유량 증가에 따른 강도 증진 효과 및 양생시간에 따른 압축강도 변화를 확인하였으며 여러 가지 실험을 통해 산정된 최적의 배합비는 S8000-E, w/c=70%, 실리카퓸(SF)=6%, 7일 양생으로 대심도 조건의 고효율 그라우트재로서 주입에 가장 효과적인 것으로 판단된다.

• 대한환경공학회지
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• 제39권4호
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• pp.180-185
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• 2017

안료 페인트 생산 업체 7개를 방문하여 제품 21개(안료 17개, 페인트 4개)를 시료채취 하였으며, 대형 온라인 판매상을 통하여 50개 제품을 구매하였다. 총 71개 제품에 대하여 EPA 7473 방법으로 수은 함량분석을 하였고, 물질흐름 분석을 위한 폐기물 내 수은함량은 타 연구(2010)의 안료 페인트 제조 업체에서 발생되는 분진 슬러지 폐페인트 38건의 수은 함량 자료를 사용하였다. 물질흐름분석은 제품 또는 특정 화학물질을 대상으로 하는 Micro 수준의 물질흐름 추적방식을 이용하여 흐름도를 작성하였다. 수은분석 결과, 71개 제품에서 0~0.25 mg-Hg/kg, 38개 폐기물에서 0.23~0.69 mg-Hg/kg으로 나타났다. 물질흐름을 살펴보면 유통단계의 수은흐름량이 연간 10.06 kg인데 반해 폐기되는 수은의 양은 25.27 kg으로 유통량 보다 폐기량이 더 높게 나타났다. 이는 제품과 폐기물의 시료채취 시기가 달라 발생된 현상으로 제품은 2014년도 제품, 폐기물은 2010년 분석된 자료를 사용하여 RoHS 등과 같은 규제의 영향으로 수은 함유 페인트 제품이 감소됨에 따른 것으로 판단된다. 현재 생산되는 제품 중 수은의 농도는 매우 낮고 페인트에 의한 수은의 유출은 미미한 것으로 판단된다.