• Computers and Concrete
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• v.25 no.6
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• pp.485-495
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• 2020

This paper, presents the dynamic and stability analysis of the simply supported single walled Carbon Nanotubes (SWCNT) reinforced concrete beam on elastic-foundation using an integral first-order shear deformation beam theory. The condition of the zero shear-stress on the free surfaces of the beam is ensured by the introduction of the shear correction factors. The SWCNT reinforcement is considered to be uniform and variable according to the X, O and V forms through the thickness of the concrete beam. The effective properties of the reinforced concrete beam are calculated by employing the rule of mixture. The analytical solutions of the buckling and free vibrational behaviors are derived via Hamilton's principle and Navier method. The analytical results of the critical buckling loads and frequency parameters of the SWCNT-RC beam are presented in the form of explicit tables and graphs. Also the diverse parameters influencing the dynamic and stability behaviors of the reinforced concrete beam are discussed in detail.

• Journal of Environmental Science International
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• v.15 no.7
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• pp.669-676
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• 2006

PAHs are major pollutants that are widely distributed in soil and groundwater environment, so that may be regarded as carcinogens. We investigated the degradation kinetics of PAH in aqueous solution when low pressure UV energy and ultrasonic irradiation were applied. Phenanthrene and pyrene were used as model compounds. The degrees of degradation of these compounds with time were analyzed with a GC/MSD (SIM-mode). UV photolysis experiments showed that phenanthrene was reduced by 90 -67% at initial concentrations of 1 ppm to 8ppm whilst it decreased to 50% at 10 ppm. Under the same conditions pyrene was degraded up to about 75% at lower initial concentrations but the reduction efficiency dropped to a level of 34 to 29% at the higher concentrations above 8 ppm. The reaction orders for phenanthrene and pyrene were found to be zero-th and ca. -0.4th order, respectively, thus implying that the reported assumption of pseudo 1st order reaction for some PAHs would be no longer valid. PAH degradation was roughly proportional to the intensity of UV (number of lamps), exhibiting maximum 92.5% of the degradation efficiency. The solution pH was lowered to 4.4 from 6.4 during the experiments partially because the carbons decomposed by the energy reacted with oxygen radicals to produce carbon dioxides. Ultrasonic irradiation on phenanthrene solutions gave relatively poor results which matched to 50 to 70% of degradation efficiency even at 2 ppm of initial concentration. Phenanthrene was found to be degraded more efficiently than pyrene for the two energy sources. Ultrasound also followed the same reaction kinetics as UV energy on PAH degradation.

• Journal of the Korean Vacuum Society
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• v.13 no.2
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• pp.79-85
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• 2004

Secondary ion mass spectrometry(SIMS) and glow discharge mass spectrometry(GDMS) were used to determine the impurity concentrations of hydrogen, carbon, and oxygen elements in the Cu and Ta films, and the results of SIMS and GDMS analysis were carefully considered. The Cu and Ta films were deposited on Si (100) substrates at zero substrate bias voltage and a substrate bias voltage of -50 V(Cu films) or -125 V(Ta films) using a non-mass separated ion beam deposition method. As a result of SIMS with Cs+ ion beam, in the case of the Cu and Ta films deposited without the substrate bias voltage, many strong peaks were observed, which is considered to be detected as a the cluster state such as CxHx, OxHx, CxOxHx. All the peaks of SIMS results could be interpreted by the combination of these dominant impurities. Moreover, it was confirmed that the quantitative results of GDMS analysis were accordant to the SIMS results.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.133-138
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• 2009

The continued rise in the number of automobiles on the roads is prompting air pollution to emerge as a serious problem due to the harmful exhaust gas emissions throughout the world. Specifically, based on the exhaust gas regulation in North America represented by PZEV, the regulation on evaporative emission, which originates from the intake manifold system when the engine is stopped, is substantially being intensified. And the technology that can meet and satisfy these regulations has been needed. This study aimed to analyze and evaluate the butane working capacity (BWC) of HC adsorption filter according to the shape of it, which was developed to reduce evaporative emission, and the effect of HC adsorption filter on the engine performance. As a results, HC adsorption filter of the plate type, which was improved compared to that of the corrugated type and also became thinner, indicates higher absorption performance compared to the corrugated one. The absorption performance of the honeycomb type, derived from improving the shape of plate type, is 33.5% higher than that of the corrugated type. However, there was no significant difference in engine performance in all shapes.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.214-217
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• 2001

자연계에서는 오염물질이 단일물질로 존재하기보다는 혼합물로 존재하는 것이 대부분이다. 본 연구에서는 지하수 오염물질 chlorinated aliphatic hydrocarbon(CAH)들 중 trichloroethylene(TCE), vinyl chloride(VC)에 대해서 Fe$^{\circ}$와 함께 미생물, 활성탄을 이용하여 단일물질 및 혼합물질상태에서 그 분해특성을 살펴보았다. 실험은 120$m\ell$ serum bottle을 이용하여 단일물질 및 혼합물질상태에서 그 분해특성을 살펴보았다. 실험은 120$m\ell$ serum bottle을 이용하였고 headspace 50${\mu}\ell$를 GC에 주입하여 각 오염물질 농도를 분석하였으며, Fe$^{\circ}$, Fe$^{\circ}$+ cell, Fe$^{\circ}$+ 활성탄 3가지 조건에서 TCE (25${\mu}\ell$)가 단일화합물 또는 VC(10$\mu\textrm{m}$)와 혼합화학물로 존재시 분해특성을 조사하였다. 단일화합물로 존재시 2시간후 TCE농도 측정 결과 Fe$^{\circ}$만을 이용하였을 때보다 활성탄, Cell을 함께 이용하였을 경우 그 분해율이 각각 1.6배, 1.8배 높게 나타났다. 그러나, VC와 혼화합물로 존재시 TCE 분해율은 단일 화합물로 존재시와 비교 Fe$^{\circ}$, Fe$^{\circ}$+ 활성탄, Fe$^{\circ}$+ cell 조건에서 각각 63%, 28%, 5%로 나타났다. VC는 Fe$^{\circ}$만으로는 분해가 되지 않았지만 cell에 의해 완전분해 되었으며, 함께 존재시 TC는 Fe$^{\circ}$만으로는 분해가 되지 않았지만 cell에 의해 완전분해 되었으며, 함께 존재시 TCE분해에 저해작용을 미치는 것으로 나타났다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.228-231
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• 2015

In power system research fields, one of current key issues is the construction and commercialization of micro grid site which is called green island, carbon zero island, energy independent island, building micro grid, etc. and various affiliated technologies have been being vigorously developed to realize. In addition, various researches about electric vehicles (EVs) are in progress and it is expected to penetrate rapidly with the next a few years. Some new load models should be developed integrating with electric vehicle loads because the EVs' deployment could cause the change of load composition rate on power system planning and operations. EVs are also resources for micro grid as well as distributed generation and demand response so that various supply and demand side resources should be considered for micro grid researches. In this paper, the load composition rate of residential sectors is prospected considering the deployment of EVs and the resource configuration of micro grid is optimized based on net present cost. In the optimization, the load patten of case studies includes EV's charging characteristics and various cases are simulated comparing micro grid environment and normal condition. HOMER is used to compare various cases and economic effects.

• Safety and Health at Work
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• v.8 no.2
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• pp.220-225
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• 2017

Background: Benzene is a known occupational and environmental pollutant. Its urinary metabolite trans, trans-muconic acid (tt-MA) has been introduced by some environmental and occupational health regulatory associations as a biological index for the assessment of benzene exposure; however, recently, doubts have been raised about the specificity of tt-MA for low-level benzene exposures. In the present study, we investigated the association between urinary levels of tt-MA and inhalational exposure to benzene in different exposure groups. Methods: Benzene exposure was assessed by personal air sampling. Collected benzene on charcoal tube was extracted by carbon disulfide and determined by a gas chromatograph (gas chromatography with a flame ionization detector). Urinary tt-MA was extracted by a strong anion-exchange column and determined with high-performance liquid chromatography-UV. Results: Urinary levels of tt-MA in intensive benzene exposure groups (chemical workers and police officers) were significantly higher than other groups (urban and rural residents), but its levels in the last two groups with significant different exposure levels (mean = 0.081 ppm and 0.019 ppm, respectively) showed no significant difference (mean = $388{\mu}g/g$ creatinine and $282{\mu}g/g$, respectively; p < 0.05). Before work shift, urine samples of workers and police officers showed a high amount of tt-MA and its levels in rural residents' samples were not zero. Conclusion: Our results suggest that tt-MA may not be a reliable biomarker for monitoring low-level (below 0.5 ppm) benzene exposures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1514-1519
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• 2001

This paper is concerned with design, manufacturing and performance test of LIPCA ( Lightweight Piezo- composite Curved Actuator) using a top carbon fiber composite layer with near -zero CTE(coefficient of thermal expansion), a middle PZT ceramic wafer and a bottom glass/epoxy layer with high CTE. The main point of this design is to replace the heavy metal layers of THUNDER by thigh tweight fiber reinforced plastic layers without losing capabilities to generate high force and large displacement. It is possible to save weight up to about 30% if we replace the metallic backing material by the light fiber composite layer. We can also have design flexibility by selecting the fiber direction and the size of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use epoxy resin prepreg system. Glass/epoxy prepregs, a ceramic wafer with electrode surfaces, and a graphite/epoxy prepreg were simply stacked and cured at an elevated temperature (177 $^{circ}C$ after following an autoclave bagging process. It was found that the manufactured composite laminate device had a sufficient curvature after detached from a flat mold. The analysis method of the cure curvature of LIPCA using the classical lamination theory is presented. The predicted curvatures are fairly in agreement with the experimental ones. In order to investigate the merits of LIPCA, a performance test of both LIPCA and THUNDE$^{TM}$ were conducted under the same boundary conditions. From the experimental actuation tests, it was observed that the developed actuator could generate larger actuation displacement than THUNDERT$^{TM}$.

• Journal of Environmental Policy
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• v.8 no.3
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• pp.181-206
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• 2009

The purpose of this paper is to analyze economic adequacy by estimating the benefit-cost for bird eco-park, eco-center, eco-river, and eco-waterway, which will be built in the new town of Kimpoo, Yangchon. This paper attempts an economic analysis for the development of an eco-friendly new town. The rates of B/C (benefit-cost) in all scenarios are over one. Especially, the B/C rate of the eco-center is the most efficient of the four eco-facilities by 5.02 - 3.75. In addition, the construction costs of the five eco-facilities are assumed to be 50 percent higher, though their economic soundness is maintained. This paper implies that providing ecological variety is one of the core components in constructing housing complexes and suggests that the construction of housing be harmonized with zero-carbon and energy efficient methods.

• Korean Institute of Interior Design Journal
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• v.21 no.6
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• pp.212-223
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• 2012

The "Eco-friendly", "Green" concepts was began around 1992 after the Rio Environmental Summit, and the need for sustainable development globally widespread. The green building certification system was began around 2000 and the concept of green building was started in the late 1990s. The green building, which welcomes a period of radical change, is for the survival of the Earth "climate change" and reducing energy consumption in building sector. In this architecture of eco-friendly concept, the green building is rapidly expanding and existing as a ecological environment preservation. Moreover, the realization of zero energy house is to mandate for new buildings in 2025. The aim of further eco-friendly is through the prior ecosystems to restore and product energy for the 9 Green Building model houses in this paper. Building in the concept of ecology is to show about change into 7R's from the 3R's. The "Reduce", "Reuse", "Recycle" consisting of "3R's" is correlated with the traditional to the present Green Building Design. U.S. NCARB (National Council of Architectural Registration Boards) change into the concept of 7R's as "Receive", "Restore", "Respect" and "Remember", added to "3R's". In this paper, the 9 Green Building model houses do not meet the criteria of 7R's. But, the Green Tomorrow of Samsung C & T Corporation meet the 6 criteria for 7R's. This company is most comfortable at low carbon Green Building model houses. Conclusionally, introduction of eco-friendly technologies and amenities for the health of human and natural community life is to advance eco-friendly construction and enhance brand value of housing. By the way, The problem of eco-friendly architecture is initial investment and maintenance. Therefore, eco-friendly architecture and government has to try solving of this difficulty.