• Asian-Australasian Journal of Animal Sciences
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• v.28 no.8
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• pp.1155-1162
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• 2015

This study aimed to evaluate the nutrient digestibility of growing rabbits fed diets with different levels of either Leucaena leucocephala (LLM) or Moringa oleifera (MOLM) leaf meals and also to compare total collection and $TiO_2$ marker methods for estimating digestibility. A total of 30 California growing rabbits ($1.81{\pm}0.19kg$ live weight on average) were randomly distributed into five experimental groups of six rabbits each and were housed in individual cages. The groups were control, 30% LLM, 40% LLM, 30% MOLM, and 40% MOLM. All groups received pelleted diets for two weeks; diets also contained 4 g/kg titanium dioxide as dietary marker. Daily feed intake was recorded during the whole experimental period and total feces were collected daily and weighed individually during four days. The results showed that there were no difference (p>0.05) in feed, dry matter (DM), organic matter (OM), crude protein (CP), digestible energy, and crude fiber (CF) intake between the control group and the other experimental groups. The apparent digestibility values of DM, OM, CP, CF, acid detergent fiber, and gross energy were the highest for control group (p = 0.001), meanwhile MOLM diets had generally higher nutrient digestibility coefficients than LLM diets. Increasing the inclusion level of leaf meal in the diet from 30% to 40% improved the digestibility of CF from 45.02% to 51.69% for LLM and from 48.11% to 55.89% for MOLM. Similar results for apparent nutrient digestibility coefficients were obtained when either total collection or indigestible marker method was used. In conclusion, the digestibility of MOLM containing diets were better than LLM diets, furthermore $TiO_2$ as an external marker could be used as a simple, practical and reliable method to estimate nutrients digestibility in rabbit diets.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.1
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• pp.34-44
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• 2015

This study was initiated to remove free cyanide from wastewater using the process of photocatalytic oxidation. UV lamp has been extensively used as a light source in conventional photocatalytic oxidation, but numerous drawbacks of UV lamp have been raised so far. Thus, this study focused on evaluating the applicability of UV LED as an alternative light source to overcome the drawbacks of UV lamp. Furthermore, the effects of diverse operational parameters on the performance of process were investigated. The results demonstrated the applicability of UV LED as a substitute of UV lamp. Also, the results show that the performance of process was improved by the increase in the number of UV LEDs used. To acquire economic feasibility as well as high efficacy, however, it is required to determine the optimum number of UV LED prior to practical implementation of the process. Among the three types of photocatalysts (anatase, rutile, and Degussa P25) tested, the Degussa P25 showed the greatest performance, and it was proven that the process was not improved as much as the Degussa P25 through simple mixing of anatase and rutile without any pretreatment. In addition, the removal efficiency of free cyanide appeared to be increased with the decrease in the particle size of $TiO_2$ photocatalyst. Besides, the process was enhanced with injection of oxygen which is considered as a major electron acceptor in the photocatalytic oxidation.

• Environmental Engineering Research
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• v.24 no.4
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• pp.711-717
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• 2019

The application of advanced oxidation for the treatment of oil refinery wastewater under UV radiation by using nanoparticles of titanium dioxide was investigated. Synthetic wastewater prepared from phenol crystals; Power Glide SAE40 motor vehicle oil and water was used. Response surface methodology (RSM) based on the Box-Behnken design was employed to design the experimental runs, optimize and study the interaction effects of the operating parameters including catalyst concentration, run time and airflow rate to maximize the degradation of oil (SOG) and phenol. The analysis of variance and the response models developed were used to evaluate the data obtained at a 95% confidence level. The use of the RSM demonstrated the graphical relationship that exists between individual factors and their interactive effects on the response, as compared to the one factor at time approach. The obtained optimum conditions of photocatalytic degradation are the catalyst concentration of 2 g/L, the run time of 30 min and the airflow rate of 1.04 L/min. Under the optimum conditions, a 68% desirability performance was obtained, representing 81% and 66% of SOG and phenol degradability, respectively. Thus, the hydrocarbon oils were readily degradable, while the phenols were more resistant to photocatalytic degradation.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.165-170
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• 2005

A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxide nanoparticle content. Their water uptake, methanol permeability and proton conductivity as a function of temperature were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and water swelling. It is also found that increase in inorganic oxide content leads to decrease of methanol permeability. In terms of the morphology, membranes are homogeneous and exhibit good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with the standard nafion membrane.

• Conservation Science in Museum
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• v.27
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• pp.67-90
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• 2022

A C-46 transport aircraft, which can be thought of as a large cultural heritage item from the modern period, was subjected to paint analysis and conservation treatment in preparation for its exhibition. The C-46 is the first aircraft ever dispatched to overseas combat zones by the Korean Air Force and carried out missions during the Vietnam War. The aircraft is mainly made of aluminum and shows signs of corrosion on its surface, including pitting and etching, as well as gray and white powdery attachments. In the analysis of the paint, diatomite(SiO₂·nH₂O) was confirmed in the red paint, titanium dioxide(TiO₂) was identified in the white paint, black iron oxide(Fe₃O₄) was detected in the black paint, and colcothar(Fe₃O₄) mixed with putty was confirmed in the blue paint. Infrared spectroscopy revealed the use of alkyd resin in the paint on the main body and nitrocellulose in the Taegeuk pattern. During the conservation treatment, mechanical cleaning, such as sanding, was conducted to remove paint and varnish from the surface. Corrosion was removed by sanding and cleaning with chemical solvents, and new paints and varnishes were applied. Through the paint analysis and conservation treatment, the aircraft was made available for exhibition in a stable condition.

• Computers and Concrete
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• v.19 no.2
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• pp.153-159
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• 2017

In this study, the strength properties of alkali-activated silica fume (SF) mortars were investigated. The crushed limestone sand with maximum size of 0-5 mm and the sodium meta silicate ($Na_2SiO_3$) used to activate the binders were kept constant in the mortar mixtures. The mortar specimens using the replacement ratios of 0, 25, 50, 75 and 100% SF by weight of cement together with $Na_2SiO_3$ at a constant rate were produced in addition to the control mortar produced by only cement. Moreover, the mortar specimens using the replacement ratio of 4% titanium dioxide ($TiO_2$) by weight of cement in the same mixture proportions were produced. The prismatic specimens produced from eleven different mixtures were de-moulded after a day, and the wet or dry cure was applied on the produced specimens at laboratory condition until the specimens were used for flexural strength ($f_{fs}$) and compressive strength ($f_c$) measurement at the ages of 7, 28 and 56 days. The $f_{fs}$ and $f_c$ values of mortars applied the wet or dry cure were compared with the results of control mortar. The findings revealed that the $f_c$ results of the alkali activated 50% SF mortars were higher than that of mortar produced with Portland cement only. It was found that the $f_{fs}$ and $f_c$ of alkali-activated SF mortars cured in dry condition was averagely 4% lower than that of alkali-activated SF mortars cured in wet condition.

• Conservation Science in Museum
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• v.30
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• pp.23-46
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• 2023

The Jija Chongtong Gun, owned by Seokdang Museum of Dong-A University, is a tubedstyle heavy weapon of the battlefield in the mid-Joseon Dynasty and is the second largest firearm after Cheonja Chongtong. The original surface color of the Jija Chongtong Gun was obscured by foreign substances and therefore it was judged that its condition requires the conservation treatment. For stable conservation treatment, gamma ray and X-ray non-destructive transmission surveys was conducted to determine the internal structure and conservation condition. And the component analysis on the material components and surface contaminants of Jija Chongtong Gun was conducted by utilizing the p-XRF component analysis, SEM-EDS component analysis, and XRD analysis. As a result of the gamma-ray and X-ray non-destructive transmission investigation, a large amount of air bubbles was observed inside Jija Chongtong Gun, and the part that appeared to be a chaplet by visual observation was not identified. As a result of gamma-ray and p-XRF component analysis, it was confirmed that Jija Chongtong Gun was bronze made of copper (Cu), tin (Sn), and lead (Pb) alloy. As a result of surface analysis of foreign substances using SEM-EDS, it was confirmed that the main components of white foreign substances were calcium (Ca), sulfur (S), and titanium (Ti). Titanium was presumed to be titanium dioxide (TiO₂), the main component of white correction fluid. The red foreign substance was confirmed to contain barium (Ba) as its main ingredient, and was presumed to be barium sulfate (BaSO₄), an extender pigment in paint. White and red contaminants, mainly composed of titanium and barium, are presumed to have been deposited on the surface in recent years. The yellow foreign substances were confirmed to be aluminum (Al) and silicon (Si), and were presumed to have originated from soil components. As a result of SEM-EDS and XRD component analysis, the white foreign substance was confirmed to be gypsum (CaS). Based on the results of component analysis, surface impurities were removed, stabilization treatment, and strengthening treatment were performed. During the conservation process, unknown inscriptions Woo (右), Byeong (兵), Sang (上), and Yi (二) were discovered through a portable microscope and precise 3D scanning. In addition, the carving method, depth, and width of the inscription were measured. Woo Byeong Sang is located above Happo Fortress in Changwon, and Yi can be identified as the second hill.

• Journal of the Mineralogical Society of Korea
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• v.28 no.1
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• pp.29-38
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• 2015

Cyanide can be leached out from the cyanidation method which has been used to extract high-purity gold and silver from ores, and it becomes a variety of cyanide complexes associated with heavy metals contained in ores. Such cyanide complexes are considered as persistent and non-degradable pollutants which cause adverse effects on humans and surrounding environments. Based on binding force between heavy metals and cyanide, cyanide complexes can be categorized weak acid dissociable (WAD) and strong acid dissociable (SAD). This study comparatively evaluated the performance of photo-catalytic process with regard to forms of cyanide complexes. In particular, both effects of UV LED wavelength and surface modification of photo-catalyst on the removal efficiency of cyanide complexes were investigated in detail. The results indicate that the performance of photo-catalytic oxidation is significantly affected by the form of cyanide complexes. In addition, the effect of UV LED wavelength on the removal efficiency was quite different between free cyanide and cyanide complexes associated with heavy metals. The results support that the surface modification of photo-catalyst, such as doping can improve overall performance of photo-catalytic oxidation of cyanide complexes.

• Journal of Conservation Science
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• v.36 no.5
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• pp.383-392
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• 2020

This study aimed to examine the characteristics of paint used for modern art works by conducting sectional observations, inorganic component analysis, and infrared spectroscopic analysis on the painted layers of 3 painted sculpture works exhibited in the Yongdam Dam Environmental Sculpture Park and Naejangsan Sculpture Park in the Jeollabuk-do area. The observations indicate that the cross section is composed of various layers of 2-3 folds, the thickness of the layers was uneven at approximately 23-150 ㎛, and putty was used for plate treatment prior to painting. Inorganic component analysis results show that putty containing calcium carbonate, iron oxide, diatomite, and titanium dioxide was used for the putty layer. It is also assumed that paint mixed with green (Cr₂O₃), blue(sodaliteblue), red(chromered), andwhite(TiO₂) colors were used for the painted layers. As a result of infrared spectroscopic analysis to confirm the types of paint, it is estimated that the paint was mixed with polyester resin and an extender.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.251-264
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• 2000

Organic removal from synthetic wastewater by electrochemical methods was investigated with various operating parameters, such as current density, retention time, electrode gap and $Cl^-/COD_{Cr}$ ratio. In electrolysis, dioxide iridium coated titanium ($IrO_2/Ti$) and stainless steel plate were used for anode and cathode respectively. The $COD_{Cr}$ removal efficiencies between plate type anode and net type anode were about same effect, but electrolytic power using net type anode is low than plate type anode. The $Cl^-/COD_{Cr}$ ratio was about $1.3kgCl^-/kgCOD_{Cr}$ when organic removal obtained 70 %, $Cl^-/COD_{Cr}$ ratio needs $2.2kgCl^-/kgCOD_{Cr}$ so as to organic completely remove. The removal efficiency of organics increased with current density, retention time and $Cl^-/COD_{Cr}$ ratio, but decreased with increasing electrode gap. The relationship of operating conditions and $COD_{Cr}$ removal efficiencies are as follows. $$COD_{Cr}(%)=80.0360(Current\;density)^{0.4451}{\times}(HRT)^{0.8102}{\times}(Gap)^{-0.4915}{\times}(Cl^-/COD_{Cr})^{0.5805}$$ There existed a competition between the removals for $COD_{Cr}$ and ammonium during electrolysis, the removal of ammonium was shown to be dominant and $COD_{Cr}$ removal was low. But $COD_{Cr}$ removal was raised as addition of alkalinity.