• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.312-319
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• 1997

The magnetometer is one of the most important payloads for scientific satellite to monitor the near-earth space environment. The electromagnetic variations of the space environment can be observed with the electric and magnetic field measurements. In practice, it is well known that the measurement of magnetic fields needs less technical complexities than that of electric fields in space. Therefore the magnetometer has long been recognized as one of the basic payloads for the scientific satellites. In this paper, we discuss the scientific fluxgate magnetometer which will be on board the KITSAT-3. The main circuit design of the present magnetometer is based on that of KITSAT-1 and -2 but its facilities have been re-designed to improve the resolution to about 5nT for scientific purpose. The calibration and noise level test of this circuit have been performed at the laboratory of the Tierra Tecnica company in Japan.

• International Journal of Highway Engineering
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• v.20 no.1
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• pp.69-76
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• 2018

PURPOSES : This study determined the optimal usage rate of RAP (reclaimed asphalt pavement) using cold central-plant recycling (CCPR) on a road-surface layer. In addition, a mixture-aggregate gradation design and a curing method based on the proposed rate for the surface-layer mix design were proposed. METHODS : First, current research trends were investigated by analyzing the optimum moisture content, mix design, and quality standards for surface layers in Korea and abroad. To analyze the aggregate characteristics of the RAP, its aggregate-size characteristics were analyzed through the combustion asphalt content test and the aggregate sieve analysis test. Moreover, aggregate-segregation experiments were performed to examine the possibility of RAP aggregate segregation from field compaction and vehicle traffic. After confirming the RAP quality standards, coarse aggregate and fine aggregate, aggregate-gradation design and quality tests were conducted for mixtures with 40% and 50% RAP usage. The optimum moisture content of the surface-layer mixture containing RAP was tested, as was the evapotranspiration effect on the surface-layer mixture of the optimum moisture content. RESULTS : After analyzing the RAP recycled aggregate size and extraction aggregate size, 13-8mm aggregate was found to be mostly 8mm aggregate after combustion. After using surface-chipping and mixing methods to examine the possibility of RAP aggregate segregation, it was found that the mixing method contributed very little for 3.32%, and because the surface-chipping method applied compaction energy directly as the maximum assumption the separation ratio was 15.46%. However, the composite aggregate gradation did not change. Using a 40% RAP aggregate rate on the surface-layer mixture for cold central-plant recycling satisfied the Abroad quality standard. The optimum moisture content of the surface-layer mixture was found to be 7.9% using the modified Marshall compaction test. It was found that the mixture was over 90% cured after curing at $60^{\circ}C$ for two days. CONCLUSIONS : To use the cold central-plant recycling mixture on a road-surface layer, a mixture-aggregate gradation design was proposed as the RAP recycled aggregate size without considering aggregate segregation, and the RAP optimal usage rate was 40%. In addition, the modified Marshall compaction test was used to determine the optimum moisture content as a mix-design parameter, and the curing method was adapted using the method recommended by Asphalt Recycling & Reclaiming Association (ARRA).

• Journal of Korea Water Resources Association
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• v.39 no.10 s.171
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• pp.823-832
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• 2006

Precipitation is the most important component to the study of water and energy cycle in hydrology. In this study we investigate rainfall retrieval uncertainty from different sources of remotely sensed precipitation field and then probable error propagation in the simulation of hydrologic variables especially, runoff on different vegetation cover. Two remotely sensed rainfall retrievals (space-borne IR-only and ground radar rainfall) are explored and compared visually and statistically. Then, an offline Community Land Model (CLM) is forced with in situ meteorological data to simulate the amount of runoff and determine their impact on model predictions. A fundamental assumption made in this study is that CLM can adequately represent the physical land surface processes. Results show there are big differences between different sources of precipitation fields in terms of the magnitude and temporal variability. The study provides some intuitions on the uncertainty of hydrologic prediction via the interaction between the land surface and near atmosphere fluxes in the modelling approach. Eventually it will contribute to the understanding of water resources redistribution to the climate change in Korean Peninsula.

• Korean Journal of Food Science and Technology
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• v.41 no.2
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• pp.131-135
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• 2009

The identification characteristics of irradiated commercial Ramen soup were investigated depending on radiation sources and doses by electron spin resonance (ESR) spectroscopy. Two commercial powder soups (RS-1, RS-2) were irradiated at 0 to 20 kGy under ambient conditions by both a Co-60 gamma irradiator and an electron beam (EB) accelerator, respectively. Crystalline sugar-induced multi-component signals with g-values of 2.010/2.011, 2.006, 2.002 and 1.999 were detected in the irradiated Ramen soup (RS-1, RS-2), whereas $Mn^{2+}$ signals were observed in non-irradiated samples, thereby distinguishing each other. Under the same analytical conditions, the intensity of ESR signals was higher in EB-irradiated samples than the gamma-irradiated ones. Determination coefficients ($R^2$) between irradiation doses and corresponding ESR responses were above 0.9665 in all the samples, and the magnetic field of specified g-value remained constant. The predominant ESR signals of $g_2$ (2.010-2.011) and $g_3$ (2.002) increased with corresponding doses of irradiation ($R^2$= 0.9750-0.9981).

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.502-507
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• 2016

This study was conducted to develop novel antimicrobial nano-composites, with the aim of fully utilizing antimicrobial properties of multi-walled carbon nanotubes (MWCNTs), nickel (Ni) and zinc oxide (ZnO). Ni coated-MWCNTs (Ni-CNT) were prepared and evaluated for their potential application as an antimicrobial material for inactivating bacteria. Field emission scanning electron microscopy (FE-SEM), and X-ray energy dispersive spectroscopy (EDS) were used to characterize the Ni coating and morphology of Ni-CNT. Staphylococcus aureus (S. aureus) and Escherichia coil (E. coil) were employed as the target bacterium on antimicrobial activities. Comparing with the nitric acid treated MWCNTs and Ni-CNT which have been previously reported to possess antimicrobial activity towards S. aureus and E. coil, Ni-CNT/ZnO exhibited a stronger antimicrobial ability. The nickel coating was confirmed to play an important role in the bactericidal action of Ni-CNTs/ZnO composites. Also, the addition of ZnO to the developed nanocomposite is suggested to improve the antimicrobial property.

• Korean Journal of Environmental Agriculture
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• v.26 no.2
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• pp.124-130
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• 2007

Excess application of paper mill sludge (PMS) in field can limit phosphorus uptake by crops because aluminum presented in the sludge can fix or adsorb available phosphorus which is necessary for crop growth. To investigate phosphorus (P) adsorption characteristics of PMS, we examined P adsorption maximum $(X_m)$ using Langmuir isotherm and P adsorption energy constant $(K_f)$ using Freundlich isotherm for PMS without alum, PMS with alum, and composted PMS with alum through a laboratory incubation test. The maximum P adsorption capacities were 800 ${\mu}g\;g^{-1}$ in soil, 47 $mg\;g^{-1}$ in PMS without alum and 61 $mg\;g^{-1}$ in PMS with alum. P adsorption capacity with alum treatment for PMS increased by 30%. That of PMS compost was 68 $mg\;g^{-1}$ and showed that composting increases 11% of P adsorption. Freundlich constant $K_f$ was 22 in check soil, while $K_f$ values in PMS without alum and in PMS with alum were 398 and 426, respectively. After composting, $K_f$ value of PMS compost significantly increased as 1,819. In conclusions, p adsorption capacity for PMS were increased by alum treatment or composting and therefore excess or continuous land application of alum-amended or composted PMS can limit P uptake for crops by reducing available P in sell.

• Radiation Oncology Journal
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• v.22 no.1
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• pp.69-75
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• 2004

Purpose : A new fiduciary plate and orientation marker have been devised to assist the quality assurance (QA) procedures for port films in radiation therapy department. The plate is used in conjunction with the film/cassette combination during weekly QA procedures, at Seoul National University Hospital (SNUH), in order to verify treatment fields in high radiation therapy. Materials and Methods : A new fiduciary plate was fabricated using an acrylic plate, cerrobend, standard blocking tray and mercury. The acrylic plate had the dimension of $1{\times}25{\times}25$ cm, with two fiduciary markers. The plate was rigidly attached onto the standard blocking tray, thus making it easier to set the fiduciary plate to the center on the radiation field on the linear accelerator. The plate had two 2-mm vertical and horizontal lines, with the minor scales in 2-cm steps. The orientation marker was a small mercury filled disk, which was inserted into the plate. Results : The geometrical structure of the lines in the plate makes it easier to correlate two different images between the simulation and port films. The marker clearly indicated the orientation of the film, for example, the anterior, posterior, left, right and various oblique orientations, without the placement of a conventional orientation marker. Also, the new orientation marker could easily be applied to the simulator by placing the small orientation marker onto the image intensifier or in front of the film/cassette holder. Conclusions : The new fiduciary plate appears to be useful in verifying the treatment fields, and the new orientation marker makes the film orientation simple, which is expected to lower the block fabrication errors.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.931-937
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• 2008

Rigorous multiscale modelling and simulation of the MTR for WGSR was carried out to accurately predict the behavior of process variables and the reactor performance. The MTR consists of 4 fixed bed tube reactors packed with heterogeneous catalysts, as well as surrounding shell part for the cooling purpose. Considering that fluid flow field and reaction kinetics give a great influence on the reactor performance, employing multiscale methodology encompassing Computational Fluid Dynamics (CFD) and process modeling was natural and, in a sense, inevitable conclusion. Inlet and outlet temperature of the reactant fluid at the tube side was $345^{\circ}C$ and $390^{\circ}C$, respectively and the CO conversion at the exit of the tube side with these conditions approached to about 0.89. At the shell side, the inlet and outlet temperature of the cooling fluid, which flows counter-currently to tube flow, was $190^{\circ}C$ and $240^{\circ}C$. From this heat exchange, the energy saving was achieved for the flow at shell side and temperature of the tube side was properly controlled to obtain high CO conversion. The simulation results from this research were accurately comparable to the experimental data from various papers.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.6
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• pp.383-390
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• 2020

Since the dynamic behaviors of liquid storage tanks on flexible soil are significantly influenced by the fluid-structure-soil interaction (FSSI), its effects must be rigorously considered for accurate earthquake analysis and seismic design of the storage system. In this study, dynamic analysis is performed for a rectangular liquid storage tank on flexible soil, and its dynamic characteristics are examined by rigorously considering the effects of FSSI. The hydrodynamic force and the interaction force between the structure and soil are evaluated using the finite-element approach. In the evaluations, mid-point integrated finite elements and viscous dampers are considered for energy radiation into the infinite soil. The effective earthquake force is then obtained from free-field analysis. It is thus demonstrated that the earthquake responses of the rectangular liquid storage tank on flexible soil are significantly influenced by the FSSI.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.7-13
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• 2022

This study compared the aortic root image by using the ECG gating and non-ECG gating methods. We observed the presence or absence of progression of the aortic root image in the images examined by the high pitch (flash) chest pain protocol method and in the patients tested without ECG gating by the conventional method. The AAPM phantom was scanned by using high pitch (flash) chest pain protocol and general chest pain protocol. CTDI values were compared. By ECG gating, the blurring of ascending aorta was significantly reduced compared to the existing non-ECG gating test method, and the image quality of the aortic root was improved. Within the parametar range that did not show differences in noise, uniformity, and high contrast resolution, CTDI values were lower when tested with the high-pitch chest pain protocol. It was found that there is an advantage in dose reduction, and if it is applied and applied to diagnostic fields such as dissection using the dose reduction mode in the cardiac field, it is a very important test for patients who need rapid diagnosis and prompt treatment as well as a dramatic reduction in exposure dose. It is presumed to be a method.