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Park Y.,OIC Language Visual Ltd. | Lee R.,Kyungin Womens College
Educational Technology and Society | Year: 2011

This study defines a blog as a contemporary web-based environment that can make a difference in adult informal learning practice. An online survey with 70 adult bloggers in Korea was undertaken to understand the nature of adults' blogging and its meanings in terms of learning. This study investigates (a) adults' blogging experiences related to learning, (b) bloggers' perceptions of the usefulness of blogging in terms of four perspectives on learning processes (i.e., learning as an acquisition process, a reflection process, a practice-based community process, and an embodied co-emergent process), and (c) the link between adult informal learning and blogging. The findings show that the majority of participants became aware of positive changes, including learning experiences, in everyday life after blogging. Among the four perspectives on learning processes, bloggers perceived blogging mainly as acquisition and/or reflection oriented learning process. Also, adult bloggers identified the characteristics of learning through blogging as 'self-directed,' 'practical,' 'situative,' 'unlimited and accessible,' and 'self-regulated,' which are distinguished from those of formal education in schools. This study therefore implies that the blog can be a meaningful learning environment and the blogging can be a significant factor in having the informal learning for adults more enriched and fulfilled. © International Forum of Educational Technology & Society (IFETS).

Jung C.H.,Kyungin Womens College | Kim Y.P.,Ewha Womans University
Particulate Science and Technology | Year: 2013

In this study, the Ångstrom exponent of the polydispersed aerosol size distribution was theoretically studied. The Ångstrom exponent was represented using a harmonic mean type analytic approximation. A log-normal aerosol size distribution was assumed and a sensitive analysis of the Ångstrom exponent was performed. The change in the Ångstrom exponent was estimated for a range of values of the real and imaginary parts of the refractive index. The result of the approximate analytic solution was comparable with that obtained by numerical integration, although there exists some discrepancy, especially for the intermediate range of particle sizes. Subsequently, this study quantitatively shows how the refractive index and particle size distribution are crucial in estimating the Ångstrom exponent, and that an analytic type approximation can be applied for the estimation of the Ångstrom exponent, especially for the limiting ranges of particle size (i.e., for the Rayleigh and geometric mean dominant size ranges). Copyright © 2013 Taylor and Francis Group, LLC.

Bae S.Y.,Ewha Womans University | Jung C.H.,Kyungin Womens College | Kim Y.P.,Ewha Womans University
Journal of Aerosol Science | Year: 2010

An aerosol dynamics equation for the below-cloud scavenging process considering phoretic and electric charging effects in addition to the conventional mechanisms (the Brownian diffusion, interception, and impaction) is developed by using the moment method. Then, the dynamics of particle size distribution by the below-cloud scavenging process is calculated by using the developed equation and verified with the measurement data. The calculated particle size distribution changes are quite small compared to the measured changes. The calculated removal rate is smaller by 10-2-10-3 than the measured data when only the conventional mechanisms are considered. With the extended mechanisms, the scavenging coefficient increases upto 20 times, mainly for the particle size range of 0.1 μm

Choi N.R.,Ewha Womans University | Lee S.P.,Chosun University | Lee J.Y.,Chosun University | Jung C.H.,Kyungin Womens College | Kim Y.P.,Ewha Womans University
Chemosphere | Year: 2016

Seventy three individual organic compounds in the atmospheric particulate matter with an aerodynamic diameter of less than or equal to a nominal 10 μm (PM10) over Seoul were identified and quantified from April 2010 to April 2011 using gas chromatography/mass spectrometry (GC/MS). These organic compounds were classified into five groups, n-alkanes, polycyclic aromatic hydrocarbons (PAHs), mono-carboxylic acids, di-carboxylic acids (DCAs), and sugars based on their chemical structures and properties. The organic compounds showed higher seasonal average concentrations from fall to winter than from spring to summer due to source strength, except some organic compounds among mono-carboxylic acids, DCAs, sugars such as undecanoic acid, methylmalonic acid, and fructose. Through qualitative data analysis using seasonal concentration variations and relevant diagnostic parameters, it was found that (1) anthropogenic sources such as combustion of fossil fuel and biomass burning attributed more to the formation of the organic aerosols than biogenic sources, and (2) the ambient level of n-alkanes, PAHs, and some compounds of DCAs and sugars was elevated in winter due to the increased primary emissions and larger transport from outside of the organic compounds in winter. © 2015 Elsevier Ltd.

Jung C.H.,Kyungin Womens College | Kim Y.P.,Ewha Womans University
Separation and Purification Technology | Year: 2013

The ideal cut of an aerosol separator should remove all particles larger than the cut diameter and allow particles less than the cut diameter to penetrate. However, it is impossible to obtain a true cut because generally, the aerosol separator shows a fractional efficiency curve with a slope, and these differences in efficiency lead to structural errors in aerosol separation [15,11,14]. This study adapts the generalized Lapple equation to describe the fractional efficiency of a cyclone and calculated the penetration efficiency through a PM2.5 collector. Sensitivity analysis for penetration error has been conducted between a real separation collector and an ideal collector. This study also derives an analytical approximated solution and shows that the approximated calculations agree very well with numerical results, especially for low geometric standard deviation and large slope parameter. Based on this measurement error calculation, the mass difference ratio of PM2.5 separator between different collectors with different slope parameter (β) and geometric mean diameter was compared. Subsequently, this study shows that conventional separators have different separation (penetration) efficiency even if their cut diameter is the same depending on the slope parameter and particle size distribution, calculates the bias with polydispersed aerosol size distributions with different slope parameter and shows an easy way to estimate the penetration error using analytical approximated solutions. © 2012 Elsevier B.V. All rights reserved.

Jung C.H.,Kyungin Womens College | Lee S.S.,National Oceanic and Atmospheric Administration | Bae S.Y.,Prediction Institute | Kim Y.P.,Ewha Womans University
Aerosol and Air Quality Research | Year: 2013

This study found that the minimum collection efficiency particle diameter during precipitation is a function of rain intensity. The raindrop size distribution was parameterized with a log normal size distribution as a function of rain intensity, and the minimum collection efficiency and minimum collection efficiency diameter were obtained analytically. The results show that, during precipitation, both the minimum scavenging coefficient diameter and the minimum scavenging coefficient increase along with rain intensity. A comparison of the minimum collection efficiency diameters for various falling velocities reveals that there is not much of a difference in the diameters. Both the numerical and analytical results of this study agree well, without much loss of accuracy. © Taiwan Association for Aerosol Research.

Choi H.-S.,Kyungin Womens College | Kim G.-H.,Duksung Womens University
Food Science and Biotechnology | Year: 2011

The volatile composition of the essential oil from fresh gamguk (Chrysanthemum indicum) flowers was investigated. The volatile constituents were extracted by the hydro distillation method. Volatile compositional changes of gamguk prepared via different drying methods (shade- and freeze-drying methods) were also determined. Total 36, 63, and 55 volatiles constituents were confirmed in the essential oil from fresh and shade-, and freeze-dried flowers. Ketones were predominant in the volatiles of gamguk flowers (%): fresh, 43.8; shade dried, 30.3; and freeze dried, 36.1. Camphor was the most abundant volatile component in all samples, and the content of borneol was also remarkable. The content of camphor was higher in fresh sample than those of dried samples while borneol concentration was significantly increased in the dried samples. © KoSFoST and Springer 2011.

Jung C.H.,Kyungin Womens College | Kim Y.P.,Ewha Womans University
Environmental Engineering Science | Year: 2010

In this study, the analytic type of a simplified model to estimate the Ångstrom exponent was developed. The relation between aerosol size distribution with different refractive indices and the Ångstrom exponent was analytically obtained using an assumption of Junge aerosol size distribution. Polynomial and harmonic mean-type approximations were applied for parameterizations of the extinction coefficient and the Ångstrom exponent. Results obtained from the simplified model were compared with numerical solutions and showed comparable results. Polynomial approximations produced more accurate results than harmonic mean approximations. This study also showed how the Ångstrom exponent changes for a Junge aerosol size distribution with different refractive index using the simplified analytic model. © 2010, Mary Ann Liebert, Inc.

Ha Y.,Kyungin Womens College | Kim B.,Kyungin Womens College
Proceedings - 1st ACIS International Symposium on Software and Network Engineering, SSNE 2011 | Year: 2011

This paper proposes a service which searches goods by images and finds a shopping mall site that offers referral services. In the service, images are obtained in various types. For image management, it will be modeled using UML Diagram. Unlike other existing sites, the service applied sites have special advantages in:1) Using sketch accessories which enable users to draw pictures.2) Support functions that search various types of images by pattern and shape.In addition to features which were mentioned above, we aim to link individuals and shopping mall sites by improved information searching techniques, ultimately providing a space that realizes user's sympathy and trust. Our goal is making a space which offers following services. When a user draws image of goods that the user is looking for, the website proposes similar looking goods and links to a shopping mall site that sells proposed goods, eventually leading user's searching to sales. © 2011 IEEE.

Jung C.H.,Kyungin Womens College | Bae S.Y.,Seoul National University | Kim Y.P.,Ewha Womans University
Atmospheric Research | Year: 2011

Wet deposition refers to both natural and artificial processes where particles are scavenged by atmospheric hydrometeors. Below-cloud atmospheric particles are removed by raindrops via Brownian diffusion, interception, and impaction. The overall scavenging coefficient has a broad and distinctive minimum for aerosol penetration between 0.1 and several micrometers in diameter. In this study, the approximated analytical solution for most penetrating particle size during precipitation was obtained. Brownian diffusion and interception were considered under the assumption of the inertial impaction can be neglected in this study conditions. Both the minimum collection efficiency and minimum scavenging coefficient particle size were estimated using the harmonic mean type approximation, with the solution compared to the numerically calculated results. The approximated results were comparable with the numerical solutions. The results showed that collection efficiency diameter is a function of terminal velocity and the collection mechanisms included. When considering Brownian diffusion and interception, most penetrating particle size increases as drop diameter increases, which shows a contrary to the study of Wang (1978) and this shows that most penetrating particle size depends on collection efficiency mechanism, flow velocity and collector diameter. Consequently, this study analytically approximated general type-solutions for scavenging gap particle size and minimum collection efficiency during precipitation. © 2010 Elsevier B.V.

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