• Journal of Environmental Science International
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• v.22 no.10
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• pp.1327-1335
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• 2013

Na-A zeolite (Z-Cl) was synthesized from coal fly ash, which is a byproduct of coal combustion for the generation of electricity. The adsorption of $Cu^{2+}$ and $Zn^{2+}ions$ onto Z-C1 was investigated via batch tests over a range of temperatures (303.15 to 323.15 K). The resultant experimental equilibrium data were compared to theoretical values calculated using model equations. With these results, the kinetics and equilibrium parameters of adsorption were calculated using Lagergren and Langmuir-Freundlich models. The adsorption kinetics revealed that the pseudo second-order kinetic mechanism is predominant. The maximum adsorption capacity ($q_{max}$) values were 139.0-197.9 mg $Zn^{2+}$/g and 75.0-105.1 mg $Cu^{2+}/g$. Calculation of the thermodynamic properties revealed that the absorption reactions for both $Cu^{2+}$ and $Zn^{2+}$ were spontaneous and endothermic. Collectively, these results suggest that the synthesized zeolite, Z-C1, can potentially be used as an adsorbent for metal ion recovery during the treatment of industrial wastewater at high temperatures.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.694-697
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• 2005

The objectives of this study were to compare the quality changes of cheese slices individually packed in four kinds of edible pouches in order to select the most suitable variety for individual packaging. The edible Z2 pouch (zein with oleic acid) was selected as maintaining the best cheese qualities based on the physical and microbiological changes undergone by the samples over 4-week storage at $5^{\circ}C$. The cheese sample individually packed in Z2 inner edible pouch and repacked in a plastic (OPP/LLDPE) outer pouch was not significantly different in physical and microbiological changes from that individually packed in a plastic (OPP/LLDPE) inner pouch and repacked in a plastic (OPP/LLDPE) outer pouch. Therefore, it may be concluded on the basis of the physical and microbiological evidence that the Z2 edible pouch can be used as an inner package for cheese slices when it is inside a plastic outer pouch.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.446-458
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• 2000

In this study, compressive strengths of three condensable composite resins(ALERT, SureFil, Solitaire), conventional hybrid composite resin(Z-100) and amalgam(HI-Aristaloy 21) according to the 6 types of cavity design(cylinder, trapezoidal, butt-joint, round bevel, long bevel and short bevel) were measured and appearance of fracture surfaces were observed with SEM, thus evaluated clinical applications of condensable composite resins according to the cavity designs. The results were as follows; 1. Compressive strengths according to experimental materials were the highest in SureFil, and Z-100, ALERT, Solitaire, HI-Aristaloy 21 in order. 2. SureFil showed the highest compressive strength(p<0.05). compressive strengths of ALERT and Solitaire were lower than that of Z-100, hybrid composite(p<0.05). 3. Compressive strengths according to specimen design were the highest in trapezoidal shape(p<0.05) and no significant difference was detected between other specimen designs. 4. The appearance of condensable composite resin under SEM was of a diverse configuration according to component of resin matrix, shapes of filler and surface treatments between resin and filler.

• Journal of The Korean Astronomical Society
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• v.45 no.1
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• pp.7-17
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• 2012

Y-band is a broad passband that is centered at ~1 ${\mu}m$. It is becoming a new, popular window for extragalactic study especially for observations of red objects thanks to recent CCD technology developments. In order to better understand the general characteristics of objects in Y-band, and to investigate the promise of Y-band observations with small telescopes, we carried out imaging observations of several extragalactic fields, brown dwarfs, and high redshift quasars with Y-band filter at the Mt. Lemmon Optical Astronomy Observatory and the Maidanak observatory. From our observations, we constrain the bright end of the galaxy and the stellar number counts in Y-band. We also test the usefulness of high redshift quasar (z >6) selection via i - z - Y color-color diagram, to demonstrate that the i - z - Y color-color diagram is effective for the selection of high redshift quasars even with a conventional optical CCD camera installed at a 1-m class telescope.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.286-292
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• 1995

Proximate composition, dimension, water uptake and volume increase rates of three cultivars of Korean kidney beans, Pink(PKB), Red(RKB) and White(WKB) were compared. Significant differences in the proximate composition and calorie were not observed among samples. Hull removed samples showed the lowest ash content and the highest calorie. The rates of water uptake increased as the soaking temperature increased from 10~4$0^{\circ}C$. The moisture gain of the kidney beans during soaking showed a similar pattern to volume increase. Water uptake and volume increase rates were in the decreasing order of PKB, RKB and WKB. Moisture and volume gains held a linear relation with the square root of soaking time regardless soaking temperatures. The activation energies of water uptake and volume increase were 3033~3087 and 3077~ 3161 kcal/mole, respectively. The log time to reach a fixed moisture content showed a linear relation with soaking temperature regardless soaking temperatures. The z-values calculated from weight and volume changes decreased in proportions to the increase of hydration. The z-values of weight and volume to reach 50% hydration were 50.5~56.6$^{\circ}C$ and 48.4~61.2$^{\circ}C$, respectively.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.359-360
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• 2012

This paper proposes a scheme of auto-tuning fuzzy PI controller and input voltage feed forward to control the output voltage of a three-phase Z-source inverter (ZSI). The proposed scheme adjusts the ts (Kp and Ki) in real time in order to find the most suitable Kp and Ki for PI controller and to simplify the controller design. The proposed scheme is verified the validity by experiment and co-simulation in PSIM and MATLAB/SIMULINK both load step change and input DC voltage variation in Z-source inverter, and has compared with the conventional PID control scheme. The experiment results involve of three-phase output voltage, Z-network capacitor voltage and dc-link peak voltage value. By those analysis and comparison, the availability of the proposed method in output voltage transient response quality improving has been verified. Compared with conventional PID method, the proposed method showed a more effective and robust control performance for coping with the severe disturbance conditions.

• The Korean Journal of Emergency Medical Services
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• v.27 no.2
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• pp.51-63
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• 2023

Purpose: The study aimed to analyze the occurrence and transfer status of emergency patients at Incheon International Airport in Korea. Methods: This study design included 810 patients for eight years, from July 1, 2014 to June 31, 2022. The collected data were analyzed with SPSS statistics version 25.0. Results: For the demographics, 531 (65.6%) were males, 151 (19.5%) were in the highest age group (in their 50s), and 289 (35.9%) were foreigners. The most common place of occurrence was in protected areas in the passenger terminal, with 341 (42.1%) of cases occurring here. The time of arrival at the site (z=-3.444, p=.001), stay duration at the site (z=-8.145, p=. 001), and transfer time (z=-3.623, p=.000) were all significantly longer. Conclusion: It is necessary to consider a rapid emergency transportation plan, such as developing a system that simplifies immigration procedures when emergency patients move from protected areas to general areas. Moreover, in order to quickly respond to foreign emergency patients, detailed characteristics will need to be identified. Lastly, considering the long transfer time, an instructing doctor should accompany an ambulance and actively perform advanced resuscitation.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.53.2-53.2
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• 2021

Quasar luminosity function (QLF) shows the active galactic nucleus (AGN) demography as a result of the combination of the growth and the evolution of black holes, galaxies, and dark matter halos along the cosmic time. The recent wide and deep surveys have improved the census of high-redshift quasars, making it possible to construct reliable ultraviolet (UV) QLFs at 2 < z < 6 down to M1450 = -23 mag. By parameterizing these up-to-date observed UV QLFs that are the most extensive in both luminosity and survey area coverage at a given redshift, we show that the UV QLF has a universal shape, and their evolution can be approximated by a pure density evolution (PDE). In order to explain the observed QLF, we construct a model QLF employing the halo mass function, a number of empirical scaling relations, and the Eddington ratio distribution. We also include the outshining of AGN over its host galaxy, which made it possible to reproduce a moderately flat shape of the faint end of the observed QLF (slope of ~ -1.1). This model successfully explains the observed PDE behavior of UV QLF at z > 2, meaning that the QLF evolution at high redshift can be understood under the framework of halo mass function evolution. The importance of the outshining effect in our model also implies that there could be a hidden population of faint AGNs (M1450 > -24 mag), which are buried under their host galaxy light.

• Steel and Composite Structures
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• v.49 no.1
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• pp.1-17
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• 2023

Based on Ahmadzadeh-Varvani hardening rule (A-V model), multiaxial ratcheting effect of Z2CND18.12N austenitic stainless steel is simulated by ABAQUS with user subroutine UMAT. The results show that the predicted results of the origin multiaxial A-V model are lower than the experimental data, and it is difficult to control ratcheting strain rate. In order to improve the predicted capability of A-V model, the A-V model is modified. In this study. Moreover, under the assumption of the von Mises yield criterion and normal plasticity flow rule, we develop a numerical algorithm of plastic strain with the improved model to implement the finite element calculation of the model. Internal iteration in the numerical algorithm was implemented with the Euler backward method, which calculated the trial strain for each equilibrium iteration using the consistent tangent matrix. With a user subroutine, the proposed model is programmed into ABAQUS for a user - executable version. By simulating the uniaxial ratcheting of a round bar made of Z2CND18.12N austenitic stainless steel, we observe that the predicted results simulated by ABAQUS with UMAT are compared with the experimental data. The predicted results of the improved multiaxial A-V model are consistent well with the experimental data.

• Geomechanics and Engineering
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• v.35 no.4
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• pp.367-383
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• 2023

The present paper examines the natural frequency responses of the bi-directional (n_x-n_y, n_y-n_z and n_z-n_x) and multidirectional (n_x-n_y-n_z) functionally graded (FG) plate and curved structures with and without porosity. The even and uneven kind of porosity pattern are considered to observe the influence of porosity type and porosity index. The numerical findings have been obtained using a higher order shear deformation theory (HSDT) based isometric finite element (FE) approach generated in a MATLAB platform. According to the convergence and validation investigation, the proposed HSDT based FE model is adequate to predict free vibrational responses of multidirectional porous FG plates and curved structures. Further a parametric analysis is carried out by taking various design parameters into account. The free vibrational behavior of bidirectional (2D) and multidirectional (3D) perfect-imperfect FGM structure is examined against various power law index, support conditions, aspect, and thickness ratio, and for the curvature of curved structures. The results indicate that the maximum non-dimensional fundamental frequency (NFF) value is observed in perfect FGM plates and curved structures compared to porous FGM plates and curved structures and it is maximum for FGM plates and curved structures with uneven kind of porosity than even porosity.