• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.12
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• pp.685-692
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• 2013

In this study, the control characteristics and effects of heating control methods on the heating performance and energy consumption of a hot-water heating control system of a residential apartment were researched by simulation and experiment. The purpose of this study is to evaluate operational strategies for improving an indoor thermal environment and reducing f energy consumption in the radiant floor heating system of a residential apartment.

• Journal of the Korean Chemical Society
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• v.50 no.1
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• pp.60-64
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• 2006

has been synthesized using the layered organic-inorganic hybrids, Cu2(OH)3(CH3COO)·H2O as a precursor. Cubic Cu2O is synthesized by reducing Cu2(OH)3(CH3COO)·H2O with glucose in water at 75oC. The effects of precursor and glucose are investigated. The structure of Cu2(OH)3(CH3COO)·H2O plays an important role in preparing the uniform size of Cu2O.

• Journal of Environmental Science International
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• v.11 no.4
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• pp.333-338
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• 2002

In this work, the characterization of adsorption of Cu, Zn and Cd on granular activated carbon in water has been studied. The factors that affect adsorption in boundary between activated carbon and wastewater are concentration, temperature, contact time, pH and so on. As the result of this study, the maximum adsorption amount of Cu occurred near pH 7, while that of Zn and Cd was near pH 9.6 and 10, respectively. As contact time and temperature are transformed, such factors as optimum contact time and temperature are taken into consideration in an adsorptive process of heavy metal because an adsorption and a reducing process occur. In isotherm of Freundlich, 1/n values of Cu, Cd capacity were between 0.16 and 0.5.

• Carbon letters
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• v.21
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• pp.74-80
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• 2017

A highly facile and eco-friendly green synthesis of Annona squamosa (custard apple) leaf extract reduced graphene oxide (CRG) nanosheets was achieved by the reduction of graphene oxide (GO). The as-prepared CRG was characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopic techniques. Removal of oxygen containing moieties from the GO was confirmed by UV-Vis, FT-IR and XPS spectroscopic data. The XRD and Raman data further confirmed the formation of the CRG. TEM images showed the sheet structure of the synthesized CRG. These results show that the phytochemicals present in custard apple leaf extract act as excellent reducing agents. The CRG showed good dispersion in water.

• Journal of the Korean Society of Safety
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• v.7 no.2
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• pp.42-46
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• 1992

The submersible motor pump could have much more merits than the general pump such as higher exhaustion head, narrower installahon place, lower noise due to operating in the water and so on. But, so far, hydraulic mechanism of the axial thrust at impeller was not analysed quantitatively and so it is very difficult to solve the occuring problems. Therefore, in this study, we aimed to minimize the axial thrust acting on thrust bearing of submersible motor pump through the analysis of hydraulic mechanism of thrust and design rivision of impeller. Test carried out on the pump with an impeller 92mm in diameter, 6 balacing holes 10mm in diameter, showed the thrust is reduced by about 86％ at the normal operating point.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.201-202
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• 2019

The high performace water reducing agent with three-hours-fluidity-retention performance is developed for the purpose of entering into the global market belonging to extreme environment such as Southeast Asia and the Middle East. In this study, the fresh and mechanical properties of the high strength concrete with three-hours-fluidity-retention performance are evaluated by making mock-up members in Vietnam.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.133-134
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• 2014

As a previous research, improved durability of concrete by filling capillary pores with waste cooking oil was suggested as a method of controlling carbonation of the concrete replaced high volume of SCMs. on the other hand, the emulsified refined waste cooking oil for better mixing performance had a drawback of reducing air content related with decreasing freeze-thawing resistance. As a solution of this problem, surface applying method was suggested instead of adding in mixing process, and in this research, the performance regarding concrete durability are evaluated comparing emulsified refined cooking oil with water-repelling agent.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1120-1125
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• 2004

Welding characteristics of STS304 stainless steel and Inconel 600 using a continuous wave Nd:YAG laser are experimentally investigated. Alloy 600 being used in steam generator tubing of pressurized water reactor(PWR) exposed to some corrosion environment, stress corrosion cracking can occur on this material. Presented here are the results from a series of experiments in which dissimilar metal welds were made using the gas tungsten arc welding process with pure argon shielding gas. But It is well known that solidification cracking susceptibility of austenitic alloys depends on the solidification temperature range and amount/distribution of solute rich liquid that exists at the terminal stages of solidification. An experimental study was conducted to determine effects of welding parameters and to optimize those parameters that have the most influence on eliminating or reducing the extent welding zone formation at dissimilar metal welds.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.7
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• pp.366-372
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• 2017

The objective of this study was to characterize Waveguide-Blow-Cutoff (WBC) array for Electromagnetic Pulse (EMP) shield in air duct or water pipe, the typical pathway of pulse in indoor space with critical electronic device. A numerical investigation with three different WBC designs (circular, rectangular, and hexagonal or honeycomb) was conducted to satisfy recommended shielding effectiveness (SE) levels from 80 dB to 140 dB. Pressure drop between upstream and downstream of EMP shields based on WBC arrays was also investigated to understand air flow feature in air duct of HVAC system. Results showed that honeycomb geometry outperformed other shapes in terms of reducing the depth of EMP shield, thus providing better air flow in duct path with lower local loss coefficient in HVAC system under SE requirements.

• Journal of Ginseng Research
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• v.4 no.1
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• pp.88-95
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• 1980

Red ginseng was extracted with water and analyzed for yield, saponin, pectin and other chemical composition. It was found that: (1) The total solid content in extract after 6 times of extraction was 46.8%,: including 13.6% of centrifugal residue; (2) 83.7% of total extractable solids and 86% total saponin was extracted after the initial three runs of extraction. (3) No significant changes were observed in HPLC pattern of extracted saponins over a range of extractions; (4) The ratio of centrifugal residue to total solids increased as the number of extractions increased; (5) The ratios of fat, protein, reducing sugar and pectin contents decreased with repeating extraction while those of crude fiber, total sugar and 35% alcohol insoluble residue increased when they were compared with total solids.