• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1443-1459
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• 2019

Polyglycerol fatty acid ester nonionic surfactants have been used for a long time in foods and have been suggested as an alternative to the safety problems of PEG based nonionic surfactants. The polyglycerol fatty acid ester surfactants are synthesized by combining a hydrophilic polyglycerin and a lipophilic fatty acid. The hydrophilic polyglycerin is polymerized using glycerin, glycidol, epichlorohydrin, etc. The main issues of the polyglycerol polymerization reaction are to increase the content of the polyglycerol in the form of linear rather than branched or cyclic forms and to narrow the distribution of the degree of polymerization. The method of binding a lipophilic fatty acid group to a hydrophilic polyglycerin includes chemical synthesis such as esterification reaction and enzyme synthesis using lipase enzyme. The main issues of polyglycerin fatty acid ester synthesis are to increase the yield and to control the degree of esterification while reducing side reactions.

• Journal of the Korea Institute of Building Construction
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• v.12 no.3
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• pp.284-290
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• 2012

Cement Fineness Modulus (CFM) is a method of expressing the distribution of particle sizes of cement in numeric form. If CFM is controlled through crush process of cement without modifying the chemical components or mineral composition of cement, it is judged to be able to produce a cement satisfying various requirements because it is estimated to enable various approaches to cement such as high early strength, moderate heat, low heat cement and so on. Therefore, in this study, as basic research for manufacturing special cement utilizing the controls of CFM, the intention was to review the impacts of CFM on the fundamental properties of concrete. To summarize the result, as mixture characteristics of fresh concrete, ratio of small aggregate and unit quantity were gradually increased, securing greater fluidity, with an increase in CFM, while the amount of AE and SP were reduced gradually. In addition, setting time was delayed as CFM increased. Furthermore, compression strength was relatively high during initial aging as CFM became smaller, but as time passed, compression strength became smaller, and it showed the same level of strength as aging time passed about three years.

• Journal of the korean academy of Pediatric Dentistry
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• v.5 no.1
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• pp.33-38
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• 1978

It has been studied that aminoacetonitrile was associated with the inhibition of collagen fiber, argyrophilic fiber and oxytalan fiber synthesis. This experiment was performed, by the basic knowledge of above mentioned study, to study on the biological effect of aminoacetonitrile to the developing periodontal ligament in Sprague Dawley rat. twenty two of female rats weighing about 200gm were gestated. In 7 days after gestation, the experimental rats were injected aminoacetonitrile 7 times intraperitoneally. After parturition, delivered fJtuses were divided into 4 groups and each group was sacrificed to 1 day, 7 days, 14 days, and 21 days after delivery, schematically. All the fetuses were observed on their periodontal ligament by histological and histo chemical methods. To study on the components of periodontal ligament fiber in these experimental study van Gieson, Masson's trichrom, argyrophilic fiber, oxytalan fiber, methyl green pyronin and periodic acid-Shiff staining were performed. Results were as follows; 1) Retardation of functional orientation in periodontal ligament collagen fiber was observed in 1 day fetuses hut this appearance was diminished gradually and recovered in normal condition in 7 days fetuses. 2) Distribution of argyrophilic fiber in 1 day fetuses was oriented delicately and loosely but volume of this fiber was gradually thickened and distributed densely. 3) Oxytalan fiber was oriented dendritic ally and contradictorily in 14 days fetuses but their orientation was changed into oblique form in middle portion of roof and their numbers were increased gradually. 4) Pyronin-philic stain of fibroblast was gradually deepened in 7 days fetuses and this finding also suggested to the depreciation of collagen synthesis in this specimen. 5) PAS positive line was observed continuousely at the portion of cervical to the middle root surface.

• Journal of Environmental Health Sciences
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• v.17 no.1
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• pp.57-66
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• 1991

This study was carried out for 5 years between 1984 and 1986 and 1989 and 1990. This interviewers visited 292 households to evaluate the perception of the residents using .the. Simple Piped Water Supply (SPWS), and examined the pollution source surrounding 42 SPWS facilities and water quality by the chemical and microbiological method. The purpose of this study was to find out problems linked with SPWS and to investigate more efficient way of improvement in rural water supply. The results of the study are surmnarized as follows: 1) Approximately 55% of the sampled population have been served by simple piped water supply. 2) The drinking water was mostly taken from the springs in 16 sites and valley water in 26 sites. 3) Considering the type of distribution of the SPWS, there are 28 natural gravity systems and 14 pumping systems. 4) Out of the 180 SPWS in Chun Sung Area, 74% of the SPWS facilities were used more than ten years. In addition, 40% of residents expressed the need for repairs of old facilities. 5) 48% of the SPWS facilities are neighbored with pollution source. 6) 50% of the maintenance crews were not committed totheir job but instead, the facilities were operated by some residents or community leaders who were personally concerned about quality of the facilities. 7) About 85% of the residents answered that SPWS was convenient and helpful. 8) About 57% of the residents complaind that the amount of daily water supply is not adequate. 9) About 74% of the residents felt that the water quality is high for dringking water and therefore, 52% of the facilities were not properly chlorinated. But in contrast, the biochemical tests indicated that only 28% of the SPWS met the dringking water quality standards. 10) Maintenance cost per a household ranges form 500 to 2, 000Won (1 $ = 700 Won) a month. Most of the cost was to cover the power electric charge. For the effective maintenance and arrangement of the facilities, gorvermental financial support for the maintenance is strongly recommended.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.393-396
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• 2002

Submerged gas-injected system can be applied to various industrial field such as metallurgical and chemical processes, So this study aims at presenting the relevant relationship between gas phase and liquid phase in a gas-injected bath. In a cylinderical bath, local gas volume fraction and bubble frequency were measured by electroconductivity probe and oscilloscope. The temperature of each phase was measured using thermocouple and data acquisition system. In vertical gas injection system, gas-liquid two phase plume was formed, being symmetry to the axial direction of injection nozzle and in a shape of con. Lacal gas-liquid flow becomes irregular around the injection nozzle due to kinetic energy of gas and the flow variables show radical change at the vicinity of gas(air) injection nozzle As most of the kinetic energy of gas was transferred to liquid in this region, liquid started to circulate. In this reason, this region was defined as 'developing flow region' The Bubble was taking a form of churn flow at the vicinity of nozzle. Sometimes smaller bubbles formed by the collapse of bubbles were observed. The gas injected into liquid bath lost its kinetic energy and then was governed by the effect of buoyancy. In this region the bubbles which lost their kinetic energy move upward with relatively uniform velocity and separate. Near the gas nozzle, gas concentration was the highest. But it started to decrease as the axial distance increased, showing a Gaussian distribution.

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.416-422
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• 2013

In order to incorporate silver ions into the alginate, silver-alginate was prepared with aqueous solutions of silver nitrate. In the study, the silver-alginate was prepared by blending with poly vinylpyrrolidone solutions and the electrospinning was performed by using this blend solution. Antibacterial properties of silver-alginate/PVP solutions were estimated for Escherichia coli and Staphylococcus aureus by the colony counting test. Electrospinning conditions of silver-alginate/PVP solution were the tip-to-collector distance of 22 cm, the flow rate of the solution at 0.01 mL/min, and the voltage at 26 kV. The form and size of silver-alginate/PVP nanofibers were estimated by SEM and Image J. The average diameter of the electrospun SA5P15 fibers was 124 nm and showed a narrow diameter distribution. The reduction of bacteria for SA5P15 exhibited 99.9% after 24 h.

• Fire Science and Engineering
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• v.22 no.2
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• pp.91-96
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• 2008

This research studied about the cause analysis of fire that was occurred in far infrared rays heater to base on the fire examples. Fire of electric heater was apt to commit error that handled an over-heating accident by judged molten mark in heat ray. Molten mark which was attached in heat ray was appeared to the form of layer short circuit by other metal material, but other metal material was not found beside the ingredient of heat wire which was mixed to an alloy of Fe-Cr-Al according to result of ingredient distribution by SEM/EDX. Also, the result of overheating experiment by layer short circuit and overvoltage showed higher febrility than normal, but there was no possibility of fire occurrence. This paper will be contributed to science for cause analysis of electric fire through analyzing physical, chemical and flame features of burnout heater on the basis of diagnosis of fire that was happened in infrared rays heater.

• Journal of Plant Biotechnology
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• v.46 no.4
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• pp.255-273
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• 2019

Orchids are indispensable to the floriculture industry due to their unique floral organization. The flowers have two outer whorls of tepals including a lip (labellum), and two inner whorls, pollinia and gynostemiun (column). The floral organization and development is controlled at the molecular level, mainly by the MADS-box gene family, comprising homeotic genes divided into type I and type II groups. The type I group has four sub-groups, Mα, Mβ, Mγ, and Mδ, playing roles in seed, embryo, and female reproductive organ development; the type II group genes form classes A, B, C, D, and E, which are a part of the MIKC^C subgroup with specific roles in florigenesis and organization. The coordinated functioning of these classes regulates the development of various floral whorls. The availability of genome and transcriptome sequence data for Phalaenopsis equestris offers an opportunity to validate the ABCDE model of flower development. Hence, this study sought to characterize the MADS-box gene family and elucidate of the ABCDE model. A total of 48 identified MADS-box proteins, including 20 type I [Mα (12), Mγ (8)] and 28 type II [MIKC^C (27), MIKC*(1)] members, were characterized for physico-chemical features and domains and motifs organization. The exon-intron distribution and the upstream cis-regulatory elements in the promoter regions of MADS-box genes were also analysed. The discrete pace of duplication events in type I and type II genes suggested differential evolutionary constraints between groups. The correlation of spatio-temporal expression pattern with the presence of specific cis-regulatory elements and putative protein-protein interaction within the different classes of MADS-box gene family endorse the ABCDE model of floral development.

• Journal of the Korean Ceramic Society
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• v.30 no.4
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• pp.325-331
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• 1993

Aqueous solutions of metallic salts, ZrO(NO3)2.2H2O and Y(NO3)3.5H2O were used as raw materials to synthesize crystalline submicron spherical powders of Zr0.94Y0.06O1.97 with tetragonal crystal phase. Each aqueous solution was mixed on the magnetic stirrer to homogenize for 12 hours. The concentration of the mixed solutionwas changed from 0.01mol/$\ell$ to 0.1mol/$\ell$ calculated as the concentration of Zr0.94Y0.06O1.97. Ultrafine droplets of starting mixed solution were sprayed by the ultrasonic vibrator and carried into the furnace kept at 55$0^{\circ}C$, $650^{\circ}C$, 75$0^{\circ}C$ and 85$0^{\circ}C$ using carrier gas of air (10$\ell$/min) and pyrolysed to form Y-TZP fine powders. The results of this exeriment were as follows. 1) Synthesized powders were nonagglomerated and spherical type. 2) Particle size distribution was narrow between 0.1${\mu}{\textrm}{m}$ and 1${\mu}{\textrm}{m}$. 3) Forming reaction Y-TZP was finished above synthetic temperature 75$0^{\circ}C$. 4) As the synthetic temperature rised from 55$0^{\circ}C$ to 85$0^{\circ}C$, the mean particle size decreased from 0.35${\mu}{\textrm}{m}$ to 0.22${\mu}{\textrm}{m}$ in the concentration of starting solution with 0.02mol/$\ell$. 5) At 75$0^{\circ}C$ of synthetic temperature, the concentration changes of starting solution from 0.01mol/$\ell$ to 0.1mol/$\ell$ increased the mean particle size from 0.24${\mu}{\textrm}{m}$ to 0.38${\mu}{\textrm}{m}$. 6) Chemical compositions of each synthesized particle were homogeneous nearly.

• Journal of Powder Materials
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• v.20 no.3
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• pp.180-185
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• 2013

The iron oxides nanoparticles and iron oxide with other compounds are of importance in fields including biomedicine, clinical and bio-sensing applications, corrosion resistance, and magnetic properties of materials, catalyst, and geochemical processes etc. In this work we describe the preparation and investigation of the properties of coated magnetic nanoparticles consisting of the iron oxide core and organic modification of the residue. These fine iron oxide nanoparticles were prepared in air environment by the co-precipitation method using of $Fe^{2+}$: $Fe^{3+}$ where chemical precipitation was achieved by adding ammonia aqueous solution with vigorous stirring. During the synthesis of nanoparticles with a narrow size distribution, the techniques of separation and powdering of nanoparticles into rather monodisperse fractions are observed. This is done using controlled precipitation of particles from surfactant stabilized solutions in the form organic components. It is desirable to maintain the particle size within pH range, temperature, solution ratio wherein the particle growth is held at a minimum. The iron oxide nanoparticles can be well dispersed in an aqueous solution were prepared by the mentioned co-precipitation method. Besides the iron oxide nanowires were prepared by using similar method. These iron oxide nanoparticles and nanowires have controlled average size and the obtained products were investigated by X-ray diffraction, FESEM and other methods.