• Title/Summary/Keyword: Air-borne

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Micro-shear bond strengths of resin-matrix ceramics subjected to different surface conditioning strategies with or without coupling agent application

  • Gunal-Abduljalil, Burcu;Onoral, Ozay;Ongun, Salim
    • The Journal of Advanced Prosthodontics
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    • v.13 no.3
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    • pp.180-190
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    • 2021
  • Purpose. This study aimed to assess the influence of various micromechanical surface conditioning (MSC) strategies with or without coupling agent (silane) application on the micro-shear bond strength (µSBS) of resin- matrix ceramics (RMCs). Materials and Methods. GC Cerasmart (GC), Lava Ultimate (LU), Vita Enamic (VE), Voco Grandio (VG), and Brilliant Crios (BC) were cut into 1.0-mm-thick slices (n = 32 per RMC) and separated into four groups according to the MSC strategy applied: control-no conditioning (C), air-borne particle abrasion with aluminum oxide particles (APA), 2W- and 3W-Er,Cr:YSGG group coding is missing. The specimens in each group were further separated into silane-applied and silane-free subgroups. Each specimen received two resin cement microtubules (n = 8 per subgroup). A shear force was applied to the adhesive interface through a universal test machine and µSBS values were measured. Data were statistically analyzed by using 3-way ANOVA and Tukey HSD test. Failure patterns were scrutinized under stereomicroscope. Results. RMC material type, MSC strategy, and silanization influenced the µSBS values (P<.05). In comparison to the control group, µSBS values increased after all other MSC strategies (P<.05) while the differences among these strategies were insignificant (P>.05). For control and APA, there were insignificant differences between RMCs (P>.05). The silanization decreased µSBS values of RMCs except for VE. Considerable declines were observed in GC and BC (P<.05). Conclusion. MSC strategies can enhance bond strength values at the RMC - cement interface. However, the choice of MSC strategy is dependent on RMC material type and each RMC can require a dedicated way of conditioning.

A Study on the Noise and Vibration Reduction Effect Depending on Dynamic Property of Slab (바닥판의 동적특성에 따른 소음진동 저감성능에 관한 연구)

  • 황재승;김선우;송진규;서재란
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.04a
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    • pp.259-266
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    • 2004
  • The vibration of slab causes a sudden change of air pressure in the interface between slab and air to create structure home sound. Floor impact noise induced from the vibration of slab became one of the hottest social issues in these day, and it took the biggest parts of the cause of damage in environmental dispute. Because the structure borne sound of slab is different from the dynamic characteristic of slab, it is required more precise vibroacaustic analysis. In this study, we was trying to understand by what mechanism the slab noise is induced from the slab vibration and the relationship between the dynamic propety of slab and the noise is shown by the numerical simulation.

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Design and Performance Evaluation of Low-Volume PM2.5 Inlet (저용량 PM2.5 도입부 개발 및 성능평가)

  • Kim Dae-Seong;Hong Sang-Beom;Lee Jae-Hun;Lee Gyu-Won
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2003.05b
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    • pp.251-252
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    • 2003
  • Most particles capable of reaching the thoracic region of humans are in the size range below 10$\mu$m in diameter. Particles with a diameter smaller than 2.5 $\mu$m are deposited in large amounts in the alveolar region during mouth inhalation. The hazard caused by fine particles depends on their chemical composition and the site within the human respiratory system where they are deposited(Hinds, 1982). Therefore, the concentration of air borne fine particles is an important parameter for the evaluation of the degree of hazard in an atmospheric environment. (omitted)

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The reduction of Tire pattern noise by using pitch sequence (피치배열을 이용한 타이어 패턴노이즈 저감)

  • Hwang S.W.;Bang M.J.;Kim S.J.;Cho C.T.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.611-614
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    • 2005
  • It is well known that tire tread pattern has much influence on the tire pattern noise. The paper describes the method of pattern noise reduction by using the pitch sequence, both on the smooth asphalt roads and on the trenched concrete roads. The noise of tire is classified as either airborne or structure borne noise. Pattern noise through the airborne is considered as a major noise source at high speeds. As block impacting and air pumping by tread patterns are major noise source, tire pattern noise can be greatly influenced by optimal pitch sequence. The goal of this paper is to provide tire engineers with pitch sequence to reduce pattern noise effectively.

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The Effect of Corrosion on the Fatigue Life of Catenary Wire (부식에 의한 가선재 수명특성에 관한 연구)

  • 김용기;장세기;이덕희;정병철
    • Proceedings of the KSR Conference
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    • 2001.10a
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    • pp.139.1-146
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    • 2001
  • Contact lines are necessary to supply electric locomotives with electric power. As most railways are gradually electrified with modernized electric cars, the demand for catenary wires and their facilities are also increased. Catenary wires made by metallic materials are generally used in the open air. They are exposed to the marine area with air-borne salt or severely polluted industrial area with much corrosive emission gases depending on the railway locations. In urban area, acid rain may cause a degradation of catenary wire system. Corrosion of catenary wires can make their actual lifetime shorter than that originally designed. Thus, the messenger wires, a kind of catenary wire system, were investigated with respect to corrosion, which include new and the used one collected at the field. They are also vibrated with some amplitude everytime the train passes through the railway. The frequent cyclic load on the wire any result in a fatigue damage, Surface damage by corrosion can make fatigue crack initiate with ease. In the present study, the fatigue life of the used wire was measured 40 to 50% shorter than that of new one in average.

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섬유질유물의 포화(Degradation)에 영향을 주는 요인들에 대한 연구

  • Bae, Sang-Gyeong
    • 보존과학연구
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    • s.11
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    • pp.1-9
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    • 1990
  • The environmental controls for good conservation of all textile materials are follow as :1) Special RH conditions on textiles keep to the usually advocated 50∼55%.2) The effect of the temperature is too small to worry about in the applicable range, that is $20^{\circ}C$.3) It is important to keep soiling by air borne dirt to a minimum by an air filter or putting textiles in cases.4) Sulphur dioxide must be rekoved by an activated carbon filter or a water spray. And this concentration below $50\muGm^3$ can be regarded assatisfactory.5) Oxygen plays a part of deterioration proceses. The effect of nitrogend andinert gases in sealed show cases should be further studied.6) Ozone is detrimental to textiles. It can be removed by activated carbonfilter.7) The removal of UV radiation and blue light can be expected to increase the lifetime of dyeing and strength of fiber.50 lux is suggested for sensitive textile materials.

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Pb, Cu, Zn Contaminants and Their Correlation of Soil, Leave and Bark of Ginkgo. B and Ambient Air Adjacent to a Heavy Traffic Road Side (교통량 과밀 도로주변의 토양과 가로수, 대기중 Pb, Cu, Zn 중금속 농도와 그 상관성에 관한 연구)

  • 박기학
    • Journal of Environmental Health Sciences
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    • v.18 no.2
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    • pp.19-25
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    • 1992
  • The study was carried out to investigate the correlation between the heavy metals emitted by the motor vehicles with the heavy traffic road side environment (soil, leave, bark, ambient air). The Pb, Cu, Zn contents in road side soil sand leaves, barks from Ginkgo, biloba and ambient air adjacent to the heavy traffic road side from June to August, 1992 Suwon city were analyzed by Atomic absorption spectrometry and Inductively coupled plasma emission spectrophotometry. The results were as follows: 1) The high levels of heavy metals concentration were Pb, at city-terminal in soil (186 $\mu$g/g), Cu, at city-terminal in soil (221 $\mu$g/g), Zn, at city-terminal in ambient air (252 $\mu$g/m$^{3}$). 2) The low leves of heavy metals concentration were Pb, at North-gate in ambient air (1.65$\mu$g/m$^{3}$), Cu, at North-gate in ambient air (4 $\mu$g/m$^{3}$), Zn, at North-gate in ambient air (15.31$\mu$g/m$^{3}$). 3) The regional distribution of Pb, Cu, Zn in road side soils, leaves and barks from Ginkgo, biloba, ambient air show high levels in turn, city4erminal, Guan Sean Dong, South gate, North gate. 4) The concentration of heavy metals (Pb, Cu, Zn) in soils, leaves, barks, ambient air was highly correlated with the traffic volume of the sampling sites (r=0.64~0.96). To conclude that the high levels of Pb, Cu, Zn contaminations were positively related to motor vehicles-borne pollutants and road side soils, trees, ambient air adjacent to a high density building area with low road coverage and heavy traffic volume were reflected strongly by the hazardous pollutants emitted by motor vehicles.

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Helicopter-borne and ground-towed radar surveys of the Fourcade Glacier on King George Island, Antarctica (남극 킹조지섬 포케이드 빙하의 헬리콥터 및 지상 레이다 탐사)

  • Kim, K.Y.;Lee, J.;Hong, M.H.;Hong, J.K.;Shon, H.
    • Geophysics and Geophysical Exploration
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    • v.13 no.1
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    • pp.51-60
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    • 2010
  • To determine subglacial topography and internal features of the Fourcade Glacier on King George Island in Antarctica, helicopter-borne and ground-towed ground-penetrating radar (GPR) data were recorded along four profiles in November 2006. Signature deconvolution, f-k migration velocity analysis, and finite-difference depth migration applied to the mixed-phase, single-channel, ground-towed data, were effective in increasing vertical resolution, obtaining the velocity function, and yielding clear depth images, respectively. For the helicopter-borne GPR, migration velocities were obtained as root-mean-squared velocities in a two-layer model of air and ice. The radar sections show rugged subglacial topography, englacial sliding surfaces, and localised scattering noise. The maximum depth to the basement is over 79m in the subglacial valley adjacent to the south-eastern slope of the divide ridge between Fourcade and Moczydlowski Glaciers. In the ground-towed profile, we interpret a complicated conduit above possible basal water and other isolated cavities, which are a few metres wide. Near the terminus, the GPR profiles image sliding surfaces, fractures, and faults that will contribute to the tidewater calving mechanism forming icebergs in Potter Cove.

Air Pollution Risk Prediction System Utilizing Deep Learning Focused on Cardiovascular Disease

  • Lee, Jisu;Moon, Yoo-Jin
    • Journal of the Korea Society of Computer and Information
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    • v.27 no.12
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    • pp.267-275
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    • 2022
  • This paper proposed a Deep Neural Network Model system utilizing Keras for predicting air pollution risk of the cardiovascular disease through the effect of each component of air on the harmful virus using past air information, with analyzing 18,000 data sets of the Seoul Open Data Plaza. By experiments, the model performed tasks with higher accuracy when using methods of sigmoid, binary_crossentropy, adam, and accuracy through 3 hidden layers with each 8 nodes, resulting in 88.92% accuracy. It is meaningful in that any respiratory disease can utilize the risk prediction system if there are data on the effects of each component of air pollution and fine dust on oil-borne diseases. It can be further developed to provide useful information to companies that produce masks and air purification products.

Evaluation of Radioactive Stack Air Effluents from the Advanced Fuel Science Building at KAERI (한국원자력연구원 새빛연료과학동 굴뚝방출 방사능 평가)

  • Chang, S.Y.;Kim, B.H.
    • Journal of Radiation Protection and Research
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    • v.33 no.3
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    • pp.121-126
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    • 2008
  • Radioactivities of the stack air effluents from the Advance Fuel Science Building (AFSB) at KAERI have been investigated and evaluated. In this AFSB, nuclear fuels for the HANARO research reactor have been fabricated and the advanced nuclear fuels have been studied. A stack air monitoring system has been continuously operating to monitor the stack air effluents from the facility to protect the environment. As the results of the periodical radioactivity measurement and both the gamma and alpha spectrometry for the millipore filters taken from the stack air monitor from January until March 2008, a trace amount of primordial $^{40}K$ and the short-lived decay products of natural borne $^{222}Rn$ and $^{220}Rn$ have been detected. However, the radioactivities have rapidly decayed to the level below the Minimum Detectable Activity (MDA) of the counting system. Therefore, it was evaluated that no uranium isotopes have been released to the atmosphere from the stack of the AFSB at KAERI.