• Journal of Auto-vehicle Safety Association
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• v.6 no.2
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• pp.43-48
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• 2014

The flexible pedestrian legform impactor(Flex-PLI) consisting of a flexible femur and tibia will be tested for pedestrian protection by global technical regulation(GTR) within the next couple of years as a replacement for the existing transport research laboratory(TRL) legform impactor. In this study, a computer aided engineering(CAE) model was used to perform the effect analysis of each injury with regard to the changes in tolerance factors with the baseline results without tolerance. The tolerance factors were the height of impactor from ground reference line, initial velocity of impactor and rotation of impactor.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.5
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• pp.685-695
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• 2004

Size-segregated measurements of aerosol composition are used to estimate the transport of natural and anthropogenic aerosols at Gosan site during May 2002. The results of measurement show that not only soil dust but also anthropogenic aerosols, including sulfur and enriched trace metals such as Pb, Zn, Cu, are transported to Gosan. This study combines the size- and time-resolved aerosol composition measurements with factor analysis in order to identify some source materials. As a result, coarse particles (2.5${\mu}m$~12${\mu}m$) are influenced by soil, sea-salt, coal, coal combustion, and nonferrous sources. But fine particles have different sources. The fine particles, which the diameter is from 0.56${\mu}m$ to 2.5${\mu}m$, are more affected by road dust, oil combustion, industry. municipal incineration, and ferrous metal sources. The very fine particles, from 0.09${\mu}m$ to 0.56${\mu}m$, mainly supplied by biomass burning, oil combustion, nonferrous and ferrous metal sources.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.148-153
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• 2024

In this study, a methodology for evaluating impact strength in rollable devices was developed, focusing on measuring impact strength and evaluating rolling and unrolling durability simultaneously, with findings reported from tests on a real demonstration unit. The study utilized a flexible and rollable polyimide (PI) substrate for the evaluations. The chosen parameters for this methodology were a flat-type impactor, weights of 300 g, 500 g, and 1000 g, a rolling shaft ranging from 30 R to 5 R, and the positioning of the impactor. The results revealed that the difference in defect rates when comparing the 300 g and 500 g weights was minimal. However, the adoption of a 1000 g weight markedly increased the defect count due to damage to the PI film's surface. Furthermore, an uptick in rolling and unrolling cycles led to more pronounced surface scratches on the PI film. These methods and findings are poised to make a substantial contribution towards refining reliability testing for a wide array of rollable device applications, including smartphones, watches, pads, and wearable technology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1782-1786
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• 2008

To investigate the characteristics of elemental components of atmospheric particles in Cheonan, atmospheric particles were sampled using a high volume air sampler equipped with a 5-stage cascade impactor during 2006. 16 elemental concentrations in fine and coarse particles were determined using ICP-AES and ICP-MS. The total mass concentrations of fine and coarse particles were 33.23 and $20.66{\mu}g/m3$, respectively, and the total elemental concentrations were 1.27, $1.71{\mu}g/m3$, occupying 3.8 and 8.3% of the total mass. Fe, Al, Ti were the most abundant elements in both fine and coarse particles, and the total Pb concentration was 84.55ng/m3, below the National standard. Enrichment factor for Sc, Cr, Cu, Zn, As, Se, Sn, Pb in fine particles were above 1,000. This indicates that the elements in fine particles are mainly from the anthropogenic sources including automobiles.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.1
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• pp.44-50
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• 1993

The suspended particulate matters had been collected by a cascade impactor having 9 size fragnated stages for 2 years (Dec. 1989 to Nov. 1991) in Kyung Hee University-Suwon Campus. The particulate matters were then collected on each stage by membrane filters. The weight concentration on each stage was estimated by a microbalance and further chemical element concentrations were determined by an XRF system. The study focused on developing of a receptor model using the TTFA (target transformation factor analysis) to apportion aerosol mass with the 30 ambient data sets. Each data set consists of the 8 size-ranged subdata sets characterized by 13 element variables. Even though a couple of sources could not be identified, three to five sources were extracted from each aerosol size-range, and then 9 statistical source profiles were generated. Finally, source contribution of particulate matters on each size-range could be estimated in Suwon area.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.11-19
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• 2015

Objective : The purpose of this study was to analyze the correlation between physical factors (X-factor, X-factor stretch) and club factors (club speed, ball speed, club path, smash factor, vertical launch angle, spin rate, flight time, total length) during impact and it affect on the total distance of the ball during a golf driver swing. Background : There were not enough studies that analyzed the correlation between physical factors(X-factor, X-factor stretch) and club factors(club speed, ball speed, club path, smash factor, launch angle, spin rate, flight time, total length) during a purpose swing to increase total distance. Method : For this study, 9 right handed professional male golfers (KPGA) were chosen. The test subject group used their own drivers and each took a total of 10 swings. These swings consisted of 5 purpose swings to increase total distance and 5 normal swings. Results : The purpose swing to increase total distance showed larger physical factors(X-factor, X-factor stretch) compared to a normal swing however the results were not statistically significant. Total distance increased during a purpose swing as a result of ball and club speed. Conclusion : The results showed that club factors, ball speed and club speed contributed the most in affecting the total distance of the ball during a purpose swing.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E4
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• pp.203-213
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• 2002

Receptor modeling is one of statistical methods to achieve reasonable air pollution strategies. In order to maintain and manage ambient air quality, it is necessary to identify sources and to apportion its sources for ambient particulate matters. The main purpose of the study was to survey seasonal trends of inorganic elements in the coarse and fine particles. Second, this study has attempted emission sources qualitatively by a receptor method, the PMF mo-del. After that. both PMF (positive matrix factorization) model and TTFA (target transformation factor analysis) model were applied to compare and to estimate mass contribution of coarse and fine particle sources at the receptor. A total of 138 sets of samples was collected from 1989 to 1996 by a low volume cascade impactor with 9 size fraction stages at Kyung Hee University in Korea. Sixteen chemical species (Si, Ca, Fe, K, Pb, Na, Zn, Mg, Ba, Ni, V, Mn, Cr, Br, Cu. Co) were characterized by XRF. The study result showed that the weighted arithmetic mean of coarse and fine particles were 51.3 and 54.4 $\mu\textrm{g}$/㎥, respectively. Contribution of both particle fractions were esti-mated using TTFA and PMF models. The number of estimated sources was seven according to TTFA model and 8 according to PMF model. Comparison of TTFA and PMF revealed that both methodologies exhibited similar trends in their contribution pattern. However, large differences between contributions were observed in some sour-ces. The results of this study may help to suggest control strategies in local countries where known source profiles do not exist.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.1
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• pp.30-37
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• 2016

Objectives: This study was performed to measure and evaluate the concentration, size distribution and fugitive emission of particulate matter from process operations at foundries. Methods: Particle matter was collected from three foundries, and samples were also collected from a background site for calculating the fugitive emission concentration of the foundries. For the collection of the samples, a Nanosampler cascade impactor was used. Results: The concentration of TSP in the samples collected from the three foundries was $0.675{\sim}1.222mg/m^3$, $PM_{10}$ was $0.525{\sim}1.018mg/m^3$ and $PM_{2.5}$ was $0.192{\sim}0.615mg/m^3$. The mass size distribution was bimodal or monomodal with maximum peak at two stage(size $2.5{\sim}10{\mu}m$). The mass median aerodynamic diameter(MMAD) was $1.80{\sim}3.98{\mu}m$. The fugitive emission concentration of TSP varies in the range of 0.65 to $1.21mg/m^3$, which exceeds the emission standard of fugitive dust($0.5mg/m^3$). Conclusions: Particle concentration and size is an important industrial hygiene factor to protect foundry workers. Furthermore, the presence of high emission of particulate pollutants has a significant negative impact on the ambient air of the study area. Therefore, it is important to improve both the process and prevention facility in oder to reduce particulate pollutants in foundries.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.3
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• pp.291-298
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• 1995

An intensive field study was carried out during Aug. 1993 in Seoul to study the characteristics of summertime visibility and diurnal trend of ionic composition of ambient particles. A transmissometer, nephelometer with heated and unheated inlets, PM3 fine particle sampler, and cascade impactor were used to measure optical and particle properties of ambient air. During this study period, a weak smog episode has occurred. Light scattering by particles is the most dominant factor on total light extinction. The effect of light absorption by particles in Seoul is much higher than other major cities in U.S.A. throughout the summer and fall with relatively constant values. The effect of water on $b_{sp}$ was small during the period. The particle size distribution shows a typical bimodal one. Sulfate, ammonium, chloride, and nitrate are the major chemical species in fine fraction aerosols, about 30% of toral mass concentration. Concentraion of sulfate is higher during the daytime while those of nitrate and chloride are higher during the nighttime. Ammonium concentration is constant through the daytime.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.1
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• pp.11-23
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• 1998

The purpose of this study was to survey chemical distribution of inorganic elements and ions in the submicron particles, to characterize qualitatively emitting sources by factor analysis, and finally to reveal existing patterns in terms of chemical compounds by a stepwise multiple regression analysis. Total of 141 samples were collected by a cascade impactor from 1989 to1996. Fifteen chemical species (Al, Ba, Cd, K, Pb, Cu, Fe, Ni, $Cl^-, NO_3^-, SO_4^{2-}, K^+, Mg^{2+}, Ca^{2+}, and Na^+$) were characterized by AAS and IC. The study showed that average seasonal levels of submicron particulate matters $(d_p<0.43 \mum)$ were 18.7 $\mug/m^3$ in spring, 15.5 $\mug/m^3$ in summer, 15.7 $\mug/m^3$ in fall, and 24.5 $\mug/m^3$ in winter, respectively. All of the anion concentrations in the particle were highest in the winter season. By applying a factor analysis, 5 source patterns were qualitatively obtained, such as sulfate related source, nitrate related source, oil burning source, calcium related source, and coal combustion source. Finally, when applying a stepwise multiple regression analysis, the results clearly showed that $Na^+ and Ca^{2+}, K^+ and Ca^{2+}, NO_3^-$ and relative humidity, $Cl^-$ and ambient temperature, $Ca^{2+} and Cl^-, Mg^{2+} and SO_4^{2-}, Na^+ and NO_3^-, and Ca^{2+} and NO_3^-$, respectively, are negatively contributed to each other. As a result of those statistical analysis, we could suggest that some chemical compounds in the submicron particles such as$NaNO_3, MgSO_4, Ca(NO_3)_2, and CaCl_2$ may not exist on the filter as final composing products; however, other compounds may possibly exist in the form of $Mg(NO_3)_2, CaSO_4, Na_2SO_4, K_2SO_4, MgCl_2, NaCl, and KCl$. Thus, it must be necessary to identify differences between the results of above statistical analysis and of the real world by laboratory experiments.