• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.838-841
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• 2004

[ $B_2O_3$ ] added $Ba(Mg_{1/3}Nb_{2/3})O_3$ (BBMN) ceramics were not sintered below $900^{\circ}C$. However, when CuO was added to the BBMN ceramic, it was sintered even at $850^{\circ}C$. The amount of the $Ba_2B_2O_5$ second phase decreased with the addition of CuO. Therefore, the CuO additive is considered to react with the $B_2O_3$ inhibiting the reaction between $B_2O_3$ and BaO. Moreover, it is suggested that the solid solution of CuO and $B_2O_3$ might be responsible for the decrease of the sintering temperature of the specimens. A dense microstructure without pores was developed with the addition of a small amount of CuO. However, a porous microstructure with large pores was formed when a large amount of CuO was added. The bulk density the dielectric constant $({\varepsilon}_r)$ and the Q-value increased with the addition of CuO but they decreased when a large amount of CuO was added. The variations of those properties are closely related to the variation of the microstructure. The excellent microwave dielectric properties of Qxf=21500 GHz, ${\varepsilon}_r=31$ and temperature coefficient of resonance frequency$({\tau}_f)=21.3\;ppm/^{\circ}C$ were obtained for the $Ba(Mg_{1/3}Nb_{2/3})O_3+2.0\;mol%B_2O_3+10.0$ mol%CuO ceramic sintered at $875^{\circ}C$ for 2h.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.284-295
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• 2019

In the recent times, a personalized travel path recommendation based on both travelogues and community contributed photos and the heterogeneous meta-data (tags, geographical locations, and date taken) which are associated with photos have been studied. The travellers using social media leave their location history, in the form of paths. These paths can be bridged for acquiring information, required, for future recommendation, for the future travellers, who are new to that location, providing all sort of information. In this paper, we propose a personalized travel path recommendation scheme, based on social life log. By taking advantage, of two kinds of social media, such as travelogue and community contributed photos, the proposed scheme, can not only be personalized to user's travel interest, but also be able to recommend, a travel path rather than individual Points of Interest (POIs). The proposed personalized travel route recommendation method consists of two steps, which are: pruning POI pruning step and creating travel path step. In the POI pruning step, candidate paths are created by the POI derived. In the creating travel path step, the proposed scheme creates the paths considering the user's interest, cost, time, season of the topic for more meaningful recommendation.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.376-383
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• 2011

The CMCs of LA and LA3 nonionic surfactants obtained from the reaction between glycidol and lauryl alcohol were found to be $0.97{\times}10^{-3}mol/L$ and $1.02{\times}10^{-3}mol/L$ respectively and the surface tensions for 1 wt% surfactant were 26.99 and 27.48 mN/m respectively. Dynamic surface tension measurements using a maximum bubble pressure tensiometer showed that the adsorption rate of surfactant molecules at the interface between the air and the surfactant solution was found to be relatively fast in both surfactant systems, presumably due to the high mobility of surfactant molecules. The contact angles of LA and LA3 nonionic surfactants were 27.8 and $20.9^{\circ}$ respectively and the dynamic interfacial tension measurement by a spinning drop tensiometer showed that interfacial tensions at equilibrium condition in both systems were almost the same. Also both surfactant systems reached equilibrium in 2~3 min. Both surfactant solutions showed high stability when evaluated by conductometric method and the LA nonionic surfactant system provided the higher foam stability than the LA3 nonionic surfactant system. The phase behavior experiments showed a lower phase or oil in water (O/W) microemulsion in equilibrium with an excess oil phase at all temperatures studied. No three-phase region was observed including a middle-phase microemulsion or a lamellar liquid crystalline phase.

• Analytical Science and Technology
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• v.35 no.6
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• pp.256-266
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• 2022

It is important to determine the concentration of long-lived radionuclides (e.g., ¹²⁹I) in nuclear waste to ensure safety when handling it. To analyze nuclides in a solid sample (e.g., concrete and soil), it is essential to effectively separate and purify the nuclides of interest in the sample. This study reports the comprehensive efforts made to validate the analytical procedure for ¹²⁹I detection in solid samples, using a high-temperature combustion furnace. ¹²⁹I volatilized from the sample collected in 0.01 M HNO₃ solution with a reducing agent (e.g., NaHSO₃) and was rapidly measured by ICP-MS. Analytical conditions, such as pyrolysis temperature and types of mobile phase gas, catalyst, and trapping solution, were optimized to obtain a high recovery rate of spiked ¹²⁹I. Finally, the optimized method was applied for the simultaneous analysis of other volatile radionuclides, such as ³H and ¹⁴C. The performance test results for the optimized method confirmed that the LSC (for ³H and ¹⁴C) and ICP-MS (for ¹²⁹I) measurements, with the separation of volatile nuclides using a high-temperature combustion furnace, were reliable.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.217-225
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• 2023

2,3-Butanediol (2,3-BDO), which is used in various fields such as cosmetics and fertilizers, is a high value-added substance and the demand for it is gradually increasing. 2,3-BDO produced from the fermentation of microorganisms not only contains by-products of fermentation, but also varies greatly in feed composition depending on fermentation conditions, so it is difficult to efficiently operate the separation process to reach the target purity of the product. Therefore, in this study, through dynamic optimization of the bio-based 2,3-BDO distillation process, the optimal control route was explored to control the 2,3-BDO concentration of the bottom product to 99 wt% or more, when feed concentration changes. Steady and dynamic state process simulation, proportional integral (PI) controller design, and dynamic optimization were sequentially performed. As a result, the error between the 2,3-BDO concentration and the set point of the bottom product was reduced by 75.2%.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.344-351
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• 2023

Purpose: This study aimed to evaluate the effectiveness of a dielectric barrier discharge (DBD) plasma module for sterilizing airborne bacteria in indoor spaces and measure the concentration of ozone generated during plasma discharge. Method: The DBD plasma module was installed in a 76m³ space, and air samples were collected under various discharge times to compare the reduction of airborne bacteria. Result: The results showed a significant decrease in airborne bacteria, ranging from 92.057% to 99.999%, with an average ozone concentration of 0.04 ppm, below the reference value. Conclusion: The study suggests that plasma discharge can be used as a means of preventing the spread of airborne bacteria and viruses, while ensuring safety for human exposure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5D
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• pp.587-595
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• 2009

Since October 11th, 2007, water taxi service in Han River has been operated for commuting and sightseeing. However, it is less popularized than expected because of economical problem and accessibility. Therefore, this paper develops service estimation items for water taxi based upon literature review on public transportation. It also conducts survey questionnaire and IPA (Importance Performance Analysis) Analysis to analyze service characteristics of water taxi users and provide several implications. The results are follows: First, economical problem should be solved out as showed in the 'main improvement' item. Second, accessibility, informativeness and convenience in the 'required improvement' item, and security and punctuality in the 'keep up the good work' item are presented. Third, kindness and soundness are showed in the 'the maintenance of current situation' item. All in all, if municipal considers economical problem, accessibility, informativeness, and convenience as it improves water tax service, it will make it possible to attract more water taxi users.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.52-59
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• 2011

BACKGROUND: This study was performed to investigate pre-harvest residue limit (PHRL) in Chwinamul, to estimate biological half-life for residue of each pesticide. Chwinamul was sprayed with pesticides of standard and double application rate. Chlorfenapyr and fenarimol were sprayed once on Chwinamul at 10 days before harvest, and it was sampled 7 times and analysed the residual change of two pesticides. METHODS AND RESULTS: Chwinamul sample was extracted with acetonitrile and partitioned with dichloromethane, and pesticide residues were determined with GCECD. Method quantitation limit (MQL) of chlorfenapyr was 0.10 mg/kg and that of fenarimol was 0.02 mg/kg. Recoveries of chlorfenapyr at two fortification levels of 1.0 and 5.0 mg/kg were $94.2{\pm}$1.70 and $99.0{\pm}1.61%$, respectively. Recoveries of fenarimol at two fortification levels of 0.2 and 1.0 mg/kg were $92.1{\pm}2.14$ and $83.1{\pm}1.98%$, respectively. CONCLUSION(s): The biological half-lives of chlorfenapyr were about 3.5 days at standard application rate, and 3.4 days at double application rate. The biological half-lives of fenarimol were about 6.0 days at standard application rate, and 5.9 days at double application rate. The PHRLs of chlorfenapyr were recommended as 13.02 and 6.25 mg/kg for 10 and 5 days before harvest, respectively. And the PHRLs of fenarimol were recommended as 2.80 and 1.67 mg/kg for 10 and 5 days before harvest, respectively.

• Journal of Veterinary Clinics
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• v.23 no.2
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• pp.114-118
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• 2006

A study on bioavailability and pharmacokinetics of florfenicol was conducted in broilers following a single intravenous (i.v.) and oral (p.o.) doses of 20 mg/kg body weight (b.w.). Florfenicol concentrations in plasma were determined by a high-performance liquid chromatography/mass spectrometry. Plasma concentration-time data after i.v. administration were analyzed by a non-compartmental analysis. Following i.v. injection, the total body clearance was $0.74{\pm}0.25L/kg/h$ and the volume of distribution at steady-state was $1.16{\pm}0.19L/kg$. Florfenicol was rapidly distributed and eliminated following i.v. injection with $1.15{\pm}1.06h$ of elimination half-life. After oral administration, the calculated $C_{max}$ values ($8.18{\pm}0.97{\mu}g/mL$) were reached at $1.33{\pm}0.29h$ in broilers. The elimination half-life of florfenicol was $1.31{\pm}0.27h$ and the absolute bioavailability (F) was 75.46% after oral administration of florfenicol. Florfenicol amine, a major metabolite of florfenicol, was detected in all broilers after i.v. and p.o. administration of florfenicol. The observed $C_{max}$ values of florfenicol amine ($3.96{\pm}2.60\;and\;2.22{\pm}1.71{\mu}g/mL$) were reached at $0.16{\pm}0.19\;and\;1.61{\pm}1.02h$ after i.v. and p.o. administration of florfenicol, respectively. Florfenicol amine was eliminated with $1.88{\pm}0.39\;and\;2.64{\pm}1.39h$ of the elimination half-life after i.v. and p.o. administration of florfenicol, respectively.

• Journal of Animal Science and Technology
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• v.46 no.1
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• pp.39-48
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• 2004

This experiment was conducted to investigate the effect of continuous feeding of probiotics on growth performance, nutrient digestibility, blood urea nitrogen(BUN) and immune responses in pigs. Treatments were 1) Control(basal diet), 2) P-O.l(basal diet + 0.1% probiotics) and 3) P-0.2(basal diet + 0.2% probiotics). In growth trial, a total of sixty pigs(6.17 $\pm$ 0.45 kg average body weight) weaned at 21 days of age were used. All pigs were assigned according to sex and body weight, and each treatment had 5 replicates of 4 pigs per pen in a randomized complete block(RCB) design. During 0${\sim}$8 weeks, there was no significant difference in average daily gain(ADG), average daily feed intake(ADFI) and gain:feed ratio(GfF) among treatments. During 9 - 20 weeks, ADG was improved significantly in pigs fed P-O.I or P-0.2 diets when compared to the pig fed control diet(P <0.05), but there was no significant difference in ADFI and GfF ratio. During overall period, ADG, ADFI and GfF ratio were not significantly different among treatments. In the first metabolic trial(17.93 $\pm$1.45kg average body weight), apparent digestibility of OM, protein, fat in pigs fed P-O.l and P-0.2 diets were greater than in pigs fed control diet(P <0.05) and ash digestibility in pigs fed P-0.2 diet was significantly higher than in pigs fed control diet(P <0.05). Calcium digestibility in pigs fed P-0.2 diet was significantly higher than in pigs fed control and P-O.I diets(P <0.05). Fecal-N excretion was lower in pigs fed P-O.! and P-0.2 diets than in pigs fed control(P <0.05). In the second metabolic trial(41.80 $\pm$ 2.68kg average body weight), there was no significant difference among treatments in apparent digestibility of nutrients and N-retention. In blood assay for the BUN and immune responses investigations, there was no significant difference among treatments during overall period of experiment. Therefore, this experiment suggested that probiotics supplementation could improve growth performance and nutrient digestibility of pigs.