• Applied Chemistry for Engineering
• /
• v.30 no.5
• /
• pp.597-605
• /
• 2019

In order to improve the adhesion of water-based adhesive, gemini type nonionic reactive surfactants were synthesized and applied to water-based adhesives. The surfactants were synthesized by using maleic acid and polyoxyethylene cetyl ether having different length of ethylene oxide and confirmed by FT-IR and $^1H-NMR$. Their appearance was light yellow wax. The cloud point of the compound was more than $78^{\circ}C$. The measured critical micelle concentration (c.m.c) was $1.0{\times}10^{-4}{\sim}7.0{\times}10^{-4}mol/L$ and surface tension at c.m.c was 25.9~32.0 mN/m. As the number of ethylene oxide increased, the emulsifying power was improved. The foaming height of each compound by Ross-Miles method was 1.4~4.5 cm. The synthesized surfactants was then used as an emulsifier in emulsion polymerization of water-based adhesives and its physical properties were evaluated. The solid contents of prepared adhesives was 59%. The average particle size and initial tackiness of the prepared adhesives were 164~297 nm and ball no. of 20~32, respectively. The peel strength was $1.8{\sim}2.1kg_f/mm$. The retention rate of adhesives viscosity was evaluated to 99% during 30 days. Therefore, synthesized gemini type nonionic reactive surfactants are expected to be applied as an emulsifier for the high adhesive force.

• Journal of Adhesion and Interface
• /
• v.4 no.1
• /
• pp.1-8
• /
• 2003

In this work, the effect of PMR-15 content on the variation of surface free energy of the DGEBA/PMR-15 blend system was investigated in terms of contact angles and mechanical interfacial tests. Based on FT-IR result of the blend system. C=O (1,772, $1,778cm^{-1}$) and C-N ($1,372cm^{-1}$) peaks appeared with imidization of PMR-15 and -OH ($3,500cm^{-1}$) peak showed broadly at 10 phr of PMR-15 by ring-opening of epoxy. Contact angle measurements were performed by using deionized water and diiodomethane as testing liquids. As a result, the surface free energy of the blends gave a maximum value at 10 phr of PMR-15, due to the significant increasing of specific component. The mechanical interfacial properties measured from the critical stress intensity factor ($K_{IC}$) and the critical strain energy release rate ($G_{IC}$) showed a similar behavior with the results of surface energetics. This behavior was probably attributed to The improving of the interfacial adhesion between intermolecules, resulting from increasing the hydrogen bondings of the blends.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.6
• /
• pp.898-904
• /
• 2021

This experimental study aims to investigate the use of a wet electrostatic precipitator as a post-treatment device to satisfy the strict emission regulations for sulfur oxides and particulate matter (PM). The inlet/outlet of a wet electrostatic precipitator was installed in a funnel using a marine four-stroke diesel engine (STX-MAN B&W) consuming marine heavy fuel oil (HFO) with a sulfur content of about 2.1%. Measurements were then obtained at the outlet of the wet electrostatic precipitator; an optical measuring instrument (OPA-102), and the weight concentration measurement method (Method 5 Isokinetic Train) were used for the PM measurements and the Fourier transform infrared (FT-IR; DX-4000) approach was used for the sulfur oxide measurements. The experimenst were conducted by varying the engine load from 50%, to 75% and 100%; it was noted that the PM reduction efficiency was a high at about 94 to 98% under all load conditions. Additionally, during the process of lowering the exhaust gas temperature in the quenching zone of the wet electrostatic precipitator, the sulfur dioxide (SO₂) values reduced because of the cleaning water, and the reduction rate was confirmed to be 55% to 81% depending on the engine load.

• Journal of Advanced Navigation Technology
• /
• v.25 no.3
• /
• pp.248-255
• /
• 2021

The main causes of the July 2013 OZ 214 accident were poorly performed approach and the failure to recognize the autothrottle in the HOLD position which the automated speed control was not provided. The pilots late decision for go-around was also a critical factor leading to the accident. The B777 POM restricts the use of FLCH mode beyond the FAF. This research utilized the QAR data of an airline's B777 fleet in the period of two years where 44 cases were found. In many cases, the FLCH mode was used for rapid descent from an higher than normal situation. In addition, in the base turn, continuous use of FLCH mode even when the path was below the glide path were observed. Airports with elevation above 500 ft MSL had a higher rate of occurrence. In this research, the proper descent planning and vertical path monitoring, and the adherence to the limitation set in the manuals and the stabilized approach criteria were re-emphasized as mitigation to reduce event occurences.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.48 no.1
• /
• pp.77-85
• /
• 2022

Retinaldehyde (RA), vitamin A derivative, is an intermediate between retinol and retinoic acid and has an excellent wrinkle improving effect. In this study, Drug-in-cyclodextrin-in-liposome (DCL) was used to enhance the stability and skin penetration of RA. The complex of RA and hydroxypropyl-beta-cyclodextrin (HP-β-CD) was prepared by the freeze-drying method, and the presence or absence of inclusion of retinal was confirmed by UV-Vis spectrometer, FT-IR and SEM images. RA was captured in HP-β-CD about 95.6% on 1 : 15 (w/w). The retinal-HP-β-CD complex was encapsulated in liposomes using a homomixer and microfluidizer, with an average particle size of 215 ± 4.2 nm and a zeta potential of -31.2 ± 0.5 mv. In the evaluation of the degradation stability of RA, degradation rate of RA-HP-β-CD-liposomes in water was 1.8% higher than RA-liposome (5.8%), RA-HP-β-CD complex (9.7%) and RA alone (37.6%). RA cream (0.05% RA) including RA-HP-β-CD-liposomes was prepared for clinical test with wrinkle-improving efficacy and skin dermis denseness evaluated for 2 or 4 weeks. RA cream showed a significant wrinkle improving effect without skin irritation. In conclusion, it was confirmed that the double stabilization technology using the DCL system contribu tes to the effect of improving skin wrinkles by increasing the stabilization of retinal.

• Applied Chemistry for Engineering
• /
• v.34 no.2
• /
• pp.161-169
• /
• 2023

In this study, we prepared naproxen (NP) imprinted biodegradable polymer based multi-layer biomaterials using allbanggae starch (ABS), polyvinyl alcohol (PVA), and alginic acid (SA), and investigated their physicochemical properties and the controlled drug release effects. In addition, the prepared multi-layer biomaterials were characterized by FE-SEM and FT-IR. In order to confirm the controlled drug release effect for the transdermal drug delivery system (TDDS), the NP release properties of NP imprinted multi-layer biomaterials were investigated using various pH buffer solutions and artificial skin at 36.5 ℃. The results of NP release in various pH buffer solutions indicated that the NP release at high pH was about 1.3 times faster than that at low pH. In addition, NP release in multi-layer biomaterials was about 4.0 times slower than that in single-layer biomaterials. It was confirmed that the NP release rate in triple-layer biomaterials was 4.0 times slower than that in single-layer biomaterials while using artificial skin. Also, it could be found that NP in double-layer biomaterials and triple-layer biomaterials was released sustainably for 12 h. The NP release mechanism in pH buffer solutions followed the Fickian diffusion mechanism, but followed the non-Fickian diffusion mechanism with artificial skin.

• Polymer(Korea)
• /
• v.27 no.5
• /
• pp.464-469
• /
• 2003

In this work, the fragrant oil release behavior of poly($\varepsilon$-caprolactone) (PCL) microcapsules containing SiO$_2$ was investigated. The SiO$_2$ was chemically treated in 10, 20, and 30 wt% hydrochloric acid and sodium hydroxide. The acid and base values were determined by Boehm's titration technique and $N_2$/77 K adsorption isotherm characteristics, the specific surface area and total pore volume were studied by BET. The PCL microcapsules containing SiO$_2$ and fragrant oil were prepared by oil-in-water (o/w) emulsion solvent evaporation method. The shape and surface of PCL microcapsules were observed using image analyzer and scanning electron microscope (SEM). The fragrant oil release behavior of PCL microcapsules was characterized using UV/vis. spectra. The average diameters of PCL microcapsules were decreased from 35 to 21 $\mu$m with increasing stirring rate. It was found that in the case of acidic treatment the fragrant oil adsorption capacity and release rate were increased due to the increase of specific surface area and acid value. In the case of basic treatment, the fragrant oil adsorption capacity and release rate were decreased due to the decrease of sp ecific surface area and the increase of acid-base interactions between SiO$_2$-NaOH and fragrant oil with increasing base value of SiO$_2$.

• Journal of dental hygiene science
• /
• v.6 no.2
• /
• pp.113-117
• /
• 2006

The purpose of this study was to evaluate caries preventive effects of a school-based weekly mouthrinsing program with a 0.2% sodium fluoride solution for five years at elementary school in Yangsan city, which were conducted for 330 children of elementary school from 2000 to 2005. The surveyed data was analyzed with SPSS statistical package. The obtained results were as follows; 1. DMF rate was 58.4% before the mouthrinsing program in 2000 and 48.3% after the program in 2005. DMF rate in 2005 decreased by 10.1% compared to DMF rate in 2000. 2. DT index was 2.46 before the mouthrinsing program and 1.70 after the program. DT index in 2004 decreased by 0.76 compared to DT index in 2000. 3. FT index was 0.55 before the mouthrinsing program and 0.37 after the program. Filled teeth due to decay after the program decreased by 0.18 compared to filled teeth before the program. 4. DMFT score was 2.61 before the mouthrinsing program and 1.64 after the program. DMFT score in 2004 decreased by 0.97 compared to DMFT score in 2000. 5. PHP index was 12.12 before the mouthrinsing program and 5.95 after the program. PHP index in 2005 decreased by 6.17 compared to PHP index in 2000.

• 한국생물공학회:학술대회논문집
• /
• 2003.04a
• /
• pp.40-44
• /
• 2003

Soil-borne infectious disease including Pythium aphanidermatum and Rhizoctonia solani causes severe damage to plants, such as cucumber. This soil-borne infectious disease was not controlled effectively by chemical pesticide. Since these diseases spread through the soil, chemical agents are usually ineffective. Instead, biological control, including antagonistic microbe can be used as a preferred control method. An efficient method was developed to select an antagonistic strain to be used as a biological control agent strain. In this new method, surface tension reduction potential of an isolate was included in the ‘decision factor’ in addition to the other factors, such as growth rate, and pathogen inhibition rate. Considering these 3 decision factors by a statistical method, an isolate from soil was selected and was identified as Bacillus sp. GB16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth was observed when Bacillus sp. GB16 was used. Therefore this strain was considered as plant growth promoting rhizobacteria (PGPR). The action of surface tension reducing component was deduced as the enhancement of wetting, spreading, and residing of antagonistic strain in the rhizosphere. This result showed that new selection method was significantly effective in selecting the best antagonistic strain for biological control of soil-borne infectious plant pathogen. The antifungal substances against P. aphanidermatum and R. solani were partially purified from the culture filtrates of Bacillus sp. GB16. In this study, lipopeptide possessing antifungal activity was isolated from Bacillus sp. GB16 cultures by various purification procedures and was identified as a surfactin-like lipopeptide based on the Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), high performance liquid chromatography mass spectroscopy (HPLC-MS), and quadrupole time-of-flight (Q-TOF) ESI-MS/MS data. The lipopeptide, named GB16-BS, completely inhibited the growth of Pythium aphanidermatum, Rhizoctonia solani, Penicillium sp., and Botrytis cineria at concentrations of 10 and 50 mg/L, respectively. A novel method to prevent the foaming and to provide oxygen was developed. During the production of surface active agent, such as lipopeptide (surfactin), large amount of foam was produced by aeration. This resulted in the carryover of cells to the outside of the fermentor, which leads to the significant loss of cells. Instead of using cell-toxic antifoaming agents, low amount of hydrogen peroxide was added. Catalase produced by cells converted hydrogen peroxide into oxygen and water. Also addition of corn oil as an oxygen vector as well as antifoaming agent was attempted. In addition, Ca-stearate, a metal soap, was added to enhance the antifoam activity of com oil. These methods could prevent the foaming significantly and maintained high dissolved oxygen in spite of lower aeration and agitation. Using these methods, high cell density, could be achieved with increased lipopeptide productivity. In conclusion to produce an effective biological control agent for soil-borne infectious disease, following strategies were attempted i) effective screening of antagonist by including surface tension as an important decision factor ii) identification of antifungal compound produced from the isolated strain iii) novel oxygenation by $H_2O_2-catalase$ with vegetable oil for antifungal lipopeptide production.

• Fire Science and Engineering
• /
• v.32 no.2
• /
• pp.30-37
• /
• 2018

This study is an analysis of combustion characteristics of synthetic insulation materials such as houses and warehouses. Using combustion cone calorimeter and SEM, the researching has experimented combustion characteristics of four kinds of materials such as flame retardant styrofoam, general styrofoam, urethane and gypsum board. And analyzed. As a result of the test, the ignition time (TTI) for the thermal insulation material was found at 27 s~43 s, and the flame retardant styrofoam was ignited at the lowest TTI at 27 s and disappears at 28 s. In addition, the maximum heat release rate (peak HRR) and average heat release rate (mean HRR) of each material were expressed in the following order: urethane> flame retardant styrofoam> styrofoam> gypsum board. Also, the total smoke release ($m^2/m^2$) was the largest at $30.798m^2/m^2$ in flame-retardant styrofoam. The general CO concentration of styrofoam was 0.275 kg/kg and the emission concentration was 12.807 kg/kg. The residues showed the highest 0.029 g in the gypsum board among the above materials.