• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.829-834
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• 2005

A series of reinforced G109 type specimens was fabricated and pended with a 15 weight percent NaCl solution. Mix design variables included 1) two cement alkalinities (equivalent alkalinities of 0.32 and 1.08), 2) w/c 0.50 and 3) two rebar surface conditions (as-received and wire-brushed). Potential and macro-cell current between top and bottom bars were monitored to determine corrosion initiation time. Once corrosion was initiated, the specimen was ultimately autopsied to perform visual inspection, and the procedure included determination of the number and size of air voids along the top half of the upper steel surface. This size determination was based upon a diameter measurement assuming the air voids to be half spheres or ellipse. The followings were reached based upon the visual inspection of G109 specimens that were autopsied to date. First, voids at the steel-concrete interface facilitated passive film breakdown and onset of localized corrosion. Based upon this, the initiation mechanism probably involved a concentration cell with contiguous concrete coated and bare steel serving as cathodes and anodes, respectively. Second, the corrosion tended to initiate at relatively large voids. Third, specimens with wire-brushed steel had a lower number of voids at the interface for both cement alkalinities, suggesting that air voids preferentially formed on the rough as-received surface compared to the smooth wire brushed one.

• Ocean and Polar Research
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• v.29 no.3
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• pp.233-244
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• 2007

Nine surface sediments from Masan Bay and Gadeog Channel were taken for grain size and geochemical and foraminiferal analyses in August 2002. The sediments consist of mud with 7.29-8.54 $\phi$ in mean grain size. Average concentrations of Al, Fe and Mn are higher in Gadeog Channel than those in Masan Bay. On the other hand, average concentrations of Pb, Cu, Zn, Cd, Cr, Ni and V are higher in Masan Bay than those in the channel. The latter group of elements show the highest concentration at station M4, off the outfall of treated wastewater disposal. Eighty-one foraminiferal species are identified in total assemblages, including 21 species of living populations. The number of individuals, species number, species diversity and equitability in Masan Bay have lower values than those in Gadeog Channel. The foraminiferal fauna off the outfall is relatively poor. Compared to geochemical and foraminiferal data obtained in 1996, heavy metals are more enriched, and the characteristics of foraminifera are little changed. These features indicate that the pollution of Masan Bay has not been reduced.

• Food Science and Preservation
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• v.30 no.4
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• pp.589-601
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• 2023

Malaysian honey is rich in nutrients and bioactive compounds, which can be a healthy alternative to refined sugar in food production. However, liquid honey's viscous and sticky nature makes it unpreferable in industrial handling. This study, an atomization system coupled with vacuum drying to produce honey powders to overcome the problem. Three types of Malaysian honey, namely Acacia, Gelam, and Tualang, were encapsulated in Ca-alginate gel beads using the atomization system. The density viscosity, and surface tension of the honey-alginate solutions were measured, and the concentration of honey and alginate influenced the physical properties of the solutions. Honey-encapsulated gel beads in the size range of 2.16-2.92 mm were produced using the atomization system with the air-liquid mass flow rate ratios of 0.22-0.31, Weber number (We) of 112-545, and Ohnersorges number (Oh) of 0.35-10.46. Gel bead diameter can be predicted using a simple mathematical model. After vacuum drying, the honey gel powder produced was in the size range of 1.50-1.79 mm. Results showed that honey gel powders with good encapsulation efficiency and high honey loading could be produced using the atomization system and vacuum drying.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.11
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• pp.1014-1019
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• 2006

The influence of the number of solution coatings on the densification of the PZT thick films was studied. PZT powder and PZT precursor solution was prepared by a sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The powder and solution of composition were (A) PZT(80/20)/PZT(20/80), (B) PZT(70/30)/PZT(30/70) and (C) PZT(60/40)/PZT(40/60), (D) PZT(52/48)/PT. The coating and drying procedure was repeated 4 times. And then the PZT precursor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5 moth and the number of coating was repeated from 0 to 6. The porosity of the thick films was decreased with increasing the number of coatings and the PZT thick films with 6-times coated showed the dense microstructure and thickness of about $60{\mu}m$. A grain size was increased with increasing the coating number. All PZT thick films showed the typical XRD patterns of a typical perovskite polycrystalline structure. The relative dielectric constant of PZT thick films was improved 30-100% as the number of coatings.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.737-744
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• 2012

A mobile emission laboratory (MEL) was designed to measure the amount of traffic pollutants, with high temporal and spatial resolution under real conditions. Equipment for the gas-phase measurements of CO, NOx, $CO_2$, and THC and for the measurement of the number, concentration, and size distribution of fine and ultra-fine particles by an FMPS and CPC was placed in a minivan. The exhausts of different types of vehicles can be sampled by an MEL. This paper describes the technical details of the MEL and presents data from the experiment in which a car chases passenger vehicles fuelled by diesel and gasoline. The particle number concentration in the exhaust of the diesel vehicle was higher than that of the gasoline vehicle. However, the diesel vehicle with a DPF emitted fewer particles than the vehicle equipped with a gasoline direct injection engine, with particle diameters over 50 nm.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.3
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• pp.237-246
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• 1994

Experimental data are reported for charging and collection of NaCl aerosols in the 0.03- to $0.2{\mu}m$-geometric-mean-diameter range in 2-stage parallel-plate electrostatic precipitators. The NaCl aerosols are generated with geometric standard deviation of about 1.74 and particle generation rate of about 10^9 particles/see by the constant output atomizer and injected into the air flow in the clean wind-tunnel. The 2-stage parallel-plate electrostatic precipitator installed in the test section of the wind-tunnel is operated with a positive corona discharge. The NaCl aerosols in the channel flow are sampled and transported to the aerosol particle number concentration measurement system by using the isoaxial sampling and transport system constructed based on the Okazaki and Willeke design. The aerosol particle number concentration measurement system measures the size distribution of submicrometer aerosols by an electrical mobility detection technique. It is confirmed from comparing the measured collection efficiencies in this study and the predicted ones by our previous theoretical analysis that the predicted collection efficiencies agree well with the experimental ones. It is also found from the comparison that below about $0.02{\mu}m$ all particles are not charged and the uncharged particles are not collected, and consequently 2-stage parallel-plate electrostatic precipitators are not suitable for that particle size range.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.175-180
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• 2015

Worldwide, studies on intelligent vehicles for the convenience of drivers have been actively conducted as the number of cars has increased. However, vehicle convenience enabled by buttons lowers the concentration on driving and hence poses as a huge threat to the safety of the driver. The use of one of the convenient features, impaired driving auxiliary equipment, is limited because of its complex usage, and this device also hinders the front view of the driver. This paper proposes a vehicle-control device for controlling the convenient features as well as changes in speed and direction using gestures and motions of the driver. This device consists of an ultrasonic sensor for recognizing movement, an arduino for accepting signal control functions and servo and DC motors apply to various vehicle parts. Firstly, the vehicle-control device was designed using a 3D CAD program known as Solid-works based on the size of the steering wheel. Then, through simulations, a suitable length for minimizing the absorbent between ultrasonic sensors was confirmed using a program known as COMSOL Multiphysics. Finally, simulation results were verified through experiments, and the optimal size of the device was identified through the number of errors.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.3
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• pp.327-337
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• 2019

The aim of this research is to contribute to enhancing the competitiveness of automotive parts suppliers while departing from the dependent relationship structure, by developing and interpreting factors that affect sale, which are financial achievements, in a practical way. The research data covered 200 companies from 2013-2017. The study hypothesis was verified by dividing the hypothesis into Model1 with control variables only and Model2 with control variables in independent variables. As a result of hypothesis testing, regarding sales, only capital size showed to have an effect in Model1, while in Model2, asset size, number of employees and joint ventures with foreign companies did but the other remaining factors did not. In particular, the results showed that an increase in financial performance required 'Economies of scale', and that companies that concentrated on a small number of items, diversified products into four or more items, or owned two to four suppliers, reaped positive results in financial performance. Therefore, in addition to the selection and concentration of corporate management for production items and account management, applying strategies, like the inter-company M&A, consortiums and co-branded strategies to achieve 'Economy of scale', would highly enhance the financial performance of automotive parts suppliers.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.215-218
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• 2015

Simultaneous laser ignition and spectroscopy is a scheme that enables rapid determination of the local equivalence ratio and condensed fuel concentration during a reaction in a two phase spray flame. We have conducted quantitative analysis of the LIBS signals according to the equivalence ratio, droplet size, droplet number density and droplet concentration as a part of novel feedback control strategy proposed for flame ignition and stabilization with simultaneous in situ combustion flow diagnostics. This is a desirable scheme since such real time information onboard an engine for instance can be constantly monitored and fed back to the control loop to enhance the mixing process and minimize emissions of unwanted species and potential combustion instability.

• Particle and aerosol research
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• v.7 no.4
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• pp.113-121
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• 2011

The aerosol nanoparticles are suspected to be exposed to workers in nanomaterial manufacturing facilities. However, the exposure assessment method has not been established. One of important issues is to characterize background level of nanoparticles in workplaces. In this study, intensive aerosol measurements were made at a $TiO_2$ manufacturing laboratory for five consecutive days in May of 2010. The $TiO_2$ nanoparticles were manufactured by the thermal-condensation process in a heated tube furnace. The particle number size distribution was measured using a scanning mobility particle sizer every 5 min, in order to detect particles ranging from 14.5 to 664 nm in diameter. Total particle number concentration shows a severe diurnal variation irrespective of manufacturing process, which was governed by nanoparticles smaller than 50 nm in diameter. During the background monitoring periods, significant peak concentrations were observed between 2 p.m. and 3 p.m. due to the infiltration of secondary aerosol particles formed by photochemical smog. Although significant increase in nanoparticle concentration was also observed during the manufacturing process twice among three times, these particle peak concentrations were lower than those observed during the background measurement. It is suggested that the investigation of background particle contamination is needed prior to conducting main exposure assessment in nanomaterial manufacturing workplaces or laboratories.