• Polymer(Korea)
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• v.37 no.6
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• pp.702-710
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• 2013

Zaltoprofen loaded polyoxalate (POX) microspheres were prepared by an emulsion solvent-evaporation/extraction method like oil-in-water (O/W) for sustained release of zaltoprofen. The influence of several preparation parameters such as fabrication temperature, stirring speed, intensity of the sonication, initial drug ratio, molecular weight ($M_w$) of POX, concentration of POX and concentration of emulsifier has been investigated on the zaltoprofen release profiles. Physicochemical properties and morphology of zaltoprofen loaded POX microspheres were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and Fourier transform infrared (FTIR). Through the analyzed results, it was demonstrated that the characteristics of the microspheres greatly affected by the prepared condition. The releases behavior of zaltoprofen was investigated for 10 days in vitro. It was confirmed that the release behavior of zaltoprofen can be controlled by the manufacturing factor of solvent-evaporation/extraction method.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.217-221
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• 2012

Blending films having enhanced water-resistance and barrier properties were prepared using the mixtures of poly(vinyl alcohol) (PVA) aqueous solution and poly(ethylene-co-acrylic acid) (EAA) dispersed in water. Thermal-mechanical properties, contact angles, water-vapor transmission rates (WVTR) and oxygen transmission rates $(O_2TR)$ were measured with the content of EAA of blending films, and their water-resistance was evaluated. The tensile strength of the films was found to be $9.16{\sim}11.75\;kg/mm^2$ which showed no significant difference compared with that of PVA, and the hardness increased with the content of EAA. The glass transition temperature and melting temperature of the blending films were slightly improved. The film prepared with PVA/EAA (= 90/10), of which the swelling and solubility were measured to be 109 and 0%, respectively, showed improved water-resistance. The WVTR and $O_2TR$ for the PET film (thickness $50\;{\mu}m$) coated with PVA/EAA (= 90/10) film (thickness $2.5\;{\mu}m$) were measured to be $9.1\;g/m^2/day$ and $2.0\;cc/m^2/day$, respectively.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.59-67
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• 1987

The pot experiment was conducted using soils with varying contents of available phosphorus to select the reasonable method for determination of the available phosphorus content in soils for Nak-Dong rice cultivation. On a basis of the responses to the phosphorus tertilizer applied, the linear correlation coefficients by Bray No.1, Bray No.2, Lancaster, North Carolina and Olsen methods were 0.887, 0.868, 0.879, 0.952 and 0.911 for Nak-Dong rice yield, respectively. Of the methods tested, North Carolina method was the most suitable for determining, the phosphorus content in soils for Nak-Dong rice. The phosphorus application promoted the growth of Nak-Dong rice in pots for culm, tiller number, available stem and grain number per ear. Based on this experiment it could be presumed that the recommanded quantity of phosphorus fertilizer should attain to 5kg per 10a to promote the growth of Nak-Dong rice in A-soil and 10kg per 10a in B -, C - and D-soil. The results from the pot experiment will be somewhat different from those from the field experiment. Therefore, field experiment should be carried out for further information.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.59-65
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• 1998

Morphology and thermal properties of polyurethane synthesized from 4,4'-diphenylmethane diisocyanate (MDI), polyester polyol, and 1,4-butane diol are investigated using fourier transform infrared spectroscopy (FT-IR), differential scanning calorimeter (DSC), and dynamic mechanical thermal analysis (DMTA). From the FT-IR study, it is found that the stretching peaks of hydrogen bonded N-H and C=O are shifted to the low frequencies with the increase of hard segment content of the polyurethanes. The shift of the stretching peaks of hydrogen bonded N-H and C=O indicates that the degree of hydrogen bonding is increased. From the DSC study, it appears that the glass transition temperature ($T_g$) of the polyurethanes is increased with the increase of the hard segment content. Also, it is found that the polyurethanes investigated in this study have the homogeneous network structure due to the high functionality of the MDI. From the DMTA study, transition of the soft segment was not found. Therefore it is concluded that the polyurethanes investigated in this study have the one-phase morphology which is consistent with the DSC results.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.268-275
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• 2021

The three factors that determine the strength of concrete are the strength of cement paste, aggregate and ITZ(Interfacial Transition Zone) between aggregate and cement paste. Out of these, the strength of ITZ is the most vulnerable. ITZ is formed in 10~50㎛, the ratio of calcium hydroxide is high, and CSH appears low ratio. A high calcium hydroxide ratio causes a decrease in the bond strength of ITZ. ITZ is due to further weak area. The problem of ITZ appears as a more disadvantageous factor when it used lightweight aggregate. The previous study of ITZ properties have measured interfacial toughness, identified influencing factors ITZ, and it progressed SEM and XRD analysis on cement matrix without using coarse aggregates. also it was identified microstructure using EMPA-BSE equipment. However, in previous studies, it is difficult to understand the microstructure and mechanical properties. Therefore, in this study, a method of measuring electrical resistance using EIS(Electrochemical Impedance Spectroscopy) measuring equipment was adopted to identify the ITZ between natural aggregate and lightweight aggregate, and it was tested the change of ITZ by surface coating of lightweight aggregate with ground granulated blast furnace slag. As a result, the compressive strength of natural aggregate and lightweight aggregate appear high strength of natural aggregate with high density, surface coating lightweight aggregate appear strength higher than natural aggregate. The electrical resistivity of ITZ according to the aggregate appeared difference.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.247-253
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• 2019

In this study, compounds with azo-mesogenic groups at 4-, 3,5-, or 3,4,5-positions of one phenyl ring were synthesized, and their liquid crystallinity and photochemistry were investigated. The compounds in the Azo1 and Azo2 series had linear and planar geometries, respectively, while those in the Azo3 series had relatively bulky structures. Compounds of BA-Azo2 and BA-Azo3 did not show any liquid crystallinity. Compounds of BE-Azo1 and BE-Azo2 exhibited a monotropic liquid crystallinity, while the other compounds showed an enantiotropic liquid crystallinity. The liquid crystalline behavior was imparted by the azo-mesogenic groups, and most of the liquid crystalline compounds formed a smectic phase. All the RM-AzoX compounds exhibited photoisomerism because of the presence of the azo groups in the molecule. The rate of photoisomerization followed the order of RM-Azo3 < RM-Azo1 < RM-Azo2 and was considered to depend on the steric hindrance around the azobenzene groups in the molecule. These results suggest that the liquid crystallinity and photochemical property of the compounds are affected by the position or the number of azo-mesogenic groups phenyl ring of the molecule.

• Clean Technology
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• v.27 no.2
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• pp.146-151
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• 2021

Pure and Sm ion doped BiVO₄ catalysts were synthesized using a conventional hydrothermal method and characterized by XRD, DRS, SEM, and PL. We also examined the activity of these materials on the photocatalytic decomposition of rhodamine B under visible light irradiation. The doping of Sm ion into BiVO₄ catalyst changed the ms-BiVO₄ crystal structure into the tz-BiVO₄ crystal structure in the low synthesis temperature. Light absorption analysis using DRS showed that all the catalysts displayed strong absorption in the visible range of the electromagnetic spectrum regardless of Sm ion doping. In addition, an amorphous morphology was shown in the pure BiVO₄ catalyst, but the morphology of the BiVO₄ catalyst doped with Sm ion was changed into an ellipse shape and also the particle size decreased. In the photocatalytic decomposition of rhodamine B, Sm ion doped BiVO₄ catalyst showed higher photocatalytic activity than the pure BiVO₄ catalyst. In addition, the Sm3-BVO catalyst doped with 3% Sm ion showed the highest photocatalytic activity, as well as the highest formation rate of OH radicals (•OH) and the highest PL peak. This result suggests that the formation rate of OH radicals produced in the interface between the photocatalyst and water is well correlated with the photocatalytic activity.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.7-11
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• 1968

A high and low productive paddy soils were waterlogged at $30{\pm}2^{\circ}C$ for 35 days in the laboratory. The relation of pH and Eh changes, ferrous iron and ammonium nitrogen of these soils was studied. The results obtained are summarized as follows: 1. pH value has been increased for 13 days of incubation and after 13 th day, they maintain their pH value without marked change, and pH value of high productive soil is higher than that of low productive soil by 0.25-0.30. 2. Eh value has been decreased for 10 days of incubation and then they also maintain their Eh value without marked change. Eh value of high productive soil is lower than that of low productive soil by 50-70 mv. 3. In both soils ferrous iron formed under submerged condition increased steeply within 4-5 days of incubation and after that they maintain their content without marked change. The $Fe^{+{+}}$ content of high productive soil is higher than low productive soil by 1.0 mg/1 gr soil. 4. $NH_4{^{-N}}$ formed under submerged condition rapidly increased in the early period of incubation and after that decreased to a certain level and maintain their content, but its content of high productive soil is higher than that of low productive soil by $20-25{\gamma}/1\;gr$ at the early stage and lower at the latter period by $10-15{\gamma}/1\;gr$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.275-282
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• 2009

PAHs(Polycyclic Aromatic Hydrocarbons) compounds may enter into the marine environment in a number of ways, and PAHs in coastal area and estuary adjacent to urban area and industrial activities region are mainly introduced into marine environment via atmosphere or river. The field surveys to evaluate the pollution of PAHs in rivers of Jinhae bay were carried out in August, 2008. The water samples collected from seven main rivers and Deokdong WWTP(Waste water Treatment Plant) which lead to Jinhae bay. 16 PAHs which had been selected as priority pollutants by EPA were analyzed. The range and mean of dissolved Total PAHs concentrations in the rivers and Duckdong WWTP that lead to Jinhae bay were shown to be 9.79~128.25(mean 36.94)ng/L, while the range and mean of Total PAHs concentrations in SPM(Suspended Particulate Matter) were shown to be 1,81434~8,893.37(mean 4,657.73)${\mu}g$/kg dry wt. The dissolved Total PAHs and Total PAHs in SPM were shown to be high concentrations in the Semhocheon which leads to Masan bay that is the most polluted area of Jinhae bay, while those were shown to be low concentrations at rivers which lead to the west area of the bay. The ranges and means of the loading fluxes from rivers and Duckdong WWTP were calculated at 0.06~12.05(mean 1.86)g/day for dissolved Total PAHs and at 0.12~16.00(mean 2.41)g/day tor Total PAH in SPM. The loading flux of Total PAHs from Duckdong WWTP was shown to be the greatest, occupying more than 80% of Total loading flux from all rivers and WWTP to Jinhae bay. The composition patterns of PAHs compound by the number of benzene ring between dissolved PAHs and PAHs of SPM were different each other. Low molecuar weight PAHs of dissoloved compounds were in high concentration, while high molecular weight PAHs of SPM were in high concentration. These results were due to physical and chemical characteristics of PAHs and were similar to those of other studies. The total PAHs concentrations of dissolved and SPM in this study are lower than those of other studies. The extent of PAHs pollution appeared to be not serious in reverine waters of Jinhae bay.

• Journal of Korean Society of Forest Science
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• v.76 no.2
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• pp.99-108
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• 1987

Half-sib seeds and one-year-old seedlings of Ginkgo biloba were treated with various simulated acid rains (pH 2.0, pH 3.0, pH 4.0 and pH 5.0) to examine the effects of acid rain on seed germination and seedling growth. The seeds were sown in a pot ($4500cm^3$) containing one of three different soils (nursery soil, mixed soil and sandy soil) and the seedlings were grown in the same pots as the seeds. Simulated acid rain was made by diluting sulfuric and nitric acid solution ($H_2SO_4$: $HNO_3$ = 3:1, V/V) with tap water and tap water (pH6.4), and treated by 5mm each time for three minutes during the growing seasons (April to October 1985 and April to August 1986). Acid rain treatments were done three times per week to potted seeds and seedlings by spraying the solutions. The seed germination, seedling growth and physiological characteristics of potted seedlings were compared among three soil types as well as among the various pH levels. The results obtained in this study were as follows: 1. Seed germination of Ginkgo biloba decreased significantly at pH 2.0 level in the field test, and also at the levels of both pH 2.0 and pH 3.0 in the laboratory test, compared to that at control. 2. For two-year-old seedlings, total, top and root dry weights per seedling were significantly different among the three soil types and among the levels of pH, and shoot growth was different only among the levels of pH. 3. For one-year-old seedlings, height and total and stem-branch dry weights per seedling were significantly different among the levels of pH.