• Korean Journal of Materials Research
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• v.11 no.8
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• pp.363-363
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• 2001

In order to improve the optical Performance of green emitting phosphor for plasma display panel (PDP) application, the wet chemical method for preparing $Zn_{2-x}$ $SiO_4$:xMn (xi=0.02. 0.08) phosphor was designed. The spherical phosphor particles were obtained and the size can be between 0.5$\mu\textrm{m}$ and 2$\mu\textrm{m}$. The formation of phosphor, which had the willemite structure, was completed at relatively low temperature of 108$0^{\circ}C$. Also, photoluminescence Properties of the phosphors prepared were investigated under vacuum ultraviolet excitation. In particular, the emission intensity of Zn$_2$SiO$_4$:0.08Mn phosphor having the 1$\mu\textrm{m}$ of particle size was higher than that of commercial phosphor by 40%. The decay time of zinc silicate powder prepared as containing 8 mole% of manganese has been measured as 7.8ms.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.5
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• pp.533-545
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• 2013

A type of Korean traditional cookies, yackwa is composed of ingredients which serve as good medicine to people. Further, it has a priceless value and possibility to be a healthy functional dessert. For this study, we developed variable yackwa, containing red-ginseng powder and green tea powder, in order to target the foreign market as well as to investigate the perception and preference of yackwa. The test sample for the control group, yackwa is made of flour, sugar, baking powder, sesame oil and alcohol. For the experimental group, yackwa contains red-ginseng and green tea powder (3, 6, 9, 12%). The investigation period was May 14th, 2013 and the total number of participants was 100. The investigation applied a consumer survey method by filling out a questionnaire while tasting 9 kinds of yackwa samples. They were used for frequency, one-way ANOVA and Pearson's correlation analysis with SPSS 19.0. In the yackwa perception survey, the result indicated that 52.0% of the customers replied 'Do not know well' and 'Do not know at all' which conveys that the perception of yackwa is very low. In contrast, the perception of the red-ginseng and green tea which are functional ingredients is high and the customers tend to prefer the taste and flavor of green tea than red-ginseng. And they prefer the yackwa containing 3% of red-ginseng and green tea powder compared to other ratio contents in the overall preference, color, taste, flavor, odor, degree of greasiness and texture. When people who have a higher perception of yackwa, they tended to prefer the color of red-ginseng yackwa and dislike the color of green tea yackwa. And the more people prefer the taste of green tea, the higher in overall preference, color, taste, flavor, and odor preference.

• Corrosion Science and Technology
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• v.12 no.6
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• pp.280-287
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• 2013

Flow accelerated corrosion(FAC) of the carbon steel piping in pressurized water reactors(PWRs) has been major issue in nuclear industry. Severe accident at Surry Unit 2 in 1986 initiated the worldwide interest in this area. Major parameters influencing FAC are material composition, microstructure, water chemistry, and hydrodynamics. Qualitative behaviors of FAC have been well understood but quantitative data about FAC have not been published for proprietary reason. In order to minimize the FAC in PWRs, the optimal method is to control water chemistry factors. Chemistry factors influencing FAC such as pH, corrosion potential, and hydrazine contents were reviewed in this paper. FAC rate decreased with pH up to 10 because magnetite solubility decreased with pH. Corrosion potential is generally controlled dissolved oxygen (DO) and hydrazine in secondary water. DO increased corrosion potential. FAC rate decreased with DO by stabilizing magnetite at low DO concentration or by formation of hematite at high DO concentration. Even though hydrazine is generally used to remove DO, hydrazine itself thermally decomposed to ammonia, nitrogen, and hydrogen raising pH. Hydrazine could react with iron and increased FAC rate. Effect of hydrazine on FAC is rather complex and should be careful in FAC analysis. FAC could be managed by adequate combination of pH, corrosion potential, and hydrazine.

• Journal of Environmental Health Sciences
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• v.39 no.6
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• pp.522-531
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• 2013

Objectives: A field survey was conducted in a hog-raising industry in order to help develop personal protective equipment for workers which would secure the safety and the health of these workers. The attempt by this study will help enhance safety in the livestock industry and contribute to the advancement of the industry. Method: The study first selected a total of 111 workers from the hog-raising industry as research participants and designed a survey with questions on general characteristics, indoor and outdoor working environments, how the workers would in practice wear or purchase the working clothes, what needs to be improved in these new working clothes, how much the workers would be likely to accept the working clothes and protective equipment, and lastly, conditions of the communicable disease control overgarment. The collected data underwent frequency analysis and cross analysis with SPSS 21.0. Result: The research targets' average age was 50 years. Work efficiency by environmental factor was normal, but all age groups had experience of accidents (79.3%). Major wounded parts were under elbow and under knee. Protective equipment most commonly worn was helmet (83.4%), gloves (98.2%) and boots (99.1%), and satisfaction with them was normal at 3.41. Working clothing most commonly worn was old clothing (31.8%) and everyday wear (17.6%) and satisfaction with it was low. Considering the improvement of working clothing, they required attached pouches, elasticity and deodorization. The acceptability of improved working clothing was high at 69.2%. Conclusion: After problems have been addressed in relevant future research, what has been learned from the concerned study will be referred to as a useful basic reference when the relevant field works to develop high-quality working clothing and protective equipment for workers in the hog-raising industry.

• Culinary science and hospitality research
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• v.15 no.3
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• pp.128-138
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• 2009

This study analyzed the qualitative characteristics and antioxidant effect of Artemisia by experimenting its medicinal effect and functionality. Moisture content increased in proportion to heating time and decreased in reverse proportion to temperature and time. In the contents of mineral compounds, P was shown in the order of roasting temperature $230^{\circ}C$ > $80^{\circ}C$ > $110^{\circ}C$, and blanching condition was 0.50% in one and two minute treatment and 0.38% in five minute treatment. The contents of Ca didn't have significant differences according to the types of treatment. The contents of Fe were higher than general vegetables with 0.54~1.02 mg/100 g. The contents of phenolic compounds were highest in the control plot, followed by one minute blanching and roasting at $110^{\circ}C$ was the lowest. The intensity of electron donating ability was decreased in 14 minute blanching at $230^{\circ}C$. Based on the result of the study, roasting at low temperature and blanching which is Korean traditional method are desirable when cooking with Artemisia.

• Journal of Ocean Engineering and Technology
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• v.28 no.2
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• pp.160-166
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• 2014

Because of industrial development, industrial facilities are becoming more complex and diversified. Plant industries are focused on productivity improvement, cost reduction, and product uniformity by simplifying production processes using automated control. Furthermore, plant industries require higher pressures and temperatures to improve energy efficiency. For this reason, the valves used in plants are operated under harsh conditions. Globe valves and gate valves are mainly used for high pressure these days. However, these valves have various problems, including low maintainability and high cost, due to structural problems. Therefore, butterfly and ball valve applications are increasing in industrial plants. This paper suggests a quadruple-offset butterfly valve that is applicable to bi-direction use, and the principle design parameters are suggested. The selected design parameters are an eccentric flange center line and shaft centerline(Offset 1), an eccentric seat centerline and disc shaft centerline(Offset 2), the angle between the flange centerline and seat wedge angle(Offset 3), the angle between the vertical direction of the disc shaft centerline and seat centerline(Offset 4), and the seat engagement angle. To analyze the interaction effect of the design parameters, ANOM and ANOVA were performed with an orthogonal array. The parameters were found to have effects in the following order: Offset 2, Offset 1, engagement angle, Offset 3, and Offset 4. The interaction between the parameters was insignificant.

• KSBB Journal
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• v.32 no.2
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• pp.117-123
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• 2017

Maple tree is a useful medical plant for obtaining bioactive materials such as pharmaceutics, cosmetics, food additive, etc., and there are 16 species of native maple trees in Korea. In this study, we evaluated the antioxidant activity of sap and crude extracts of Acer mono Max, a representative maple species. The crude extracts were obtained by solvent extraction (water, ethanol, and ethyl acetate) from its branches (bark and xylem). The phenolic contents and radical scavenging capacities of the extracts and the sap were evaluated in terms of half maximal effective concentration ($EC_{50}$) and kinetics by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The ethanol extracts showed the highest extraction yield, phenolic contents and antioxidant activity, and bark extracts showed better antioxidant activity than xylem extracts. The antioxidant activity of the sap was very low, but the $EC_{50}$ of ethanol and ethyl acetate extracts ranged from 68 to $79{\mu}g/mL$, similar to that ($60{\mu}g/mL$) of the control, butylated hydroxytoluene (BHT). The DPPH radical scavenging rate ($220{\sim}760{\mu}M/min$) and the second-order reaction rate constant ($6.48{\sim}7.04L/g{\cdot}min$) of these extracts were better than those of BHT ($55{\sim}370{\mu}M/min$ and $3.60L/g{\cdot}min$). These results suggest that A. mono Max. is one of the useful bioresources for obtaining antioxidant biologically active substances, and it is possible to obtain physiologically active substances from by-product of its pruning while minimizing the effect on the growth of the tree.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.506-511
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• 2009

In order to improve the bacterial cellulose(BC) production yield, centrifugal and inclined centrifugal impellers were developed. A 6 flat-blade turbine impeller was used as a control system. The flow pattern in the fermenter and volumetric oxygen transfer coefficient($k_La$) of these fermentation systems were studied. Fermentations were carried out for the production of BC by G. hansenii PJK in a 2-L jar fermenter equipped with new impellers. Liquid medium was circulated from the bottom, through the cylinder of the impeller and to the wall. The volumetric oxygen transfer coefficients, $k_La$, of inclined centrifugal and centrifugal impeller systems at 100 rpm were 23 and 15% of the conventional turbine impeller system, respectively. However, the conversion of microbial cells to cellulose non-producing mutant decreased and this results in the increase in BC production at low rotating speed of impellers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.259-265
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• 2012

Recently, many research works are focusing on DVC (Distributed Video Coding) system for low complexity encoder. Most DVC systems need feedback channel for parity bit control to achieve the good RD performances, however, this causes the system to have high decoding latency and is considered as one of the most critical problems for real implementation. In order to overcome this problem, this paper proposes an effective distributed video decoding method using adaptive LDPCA frame-based parity bit request estimation. The proposed method applies for the pixel-domain Wyner-Ziv system and exploits the statistical characteristics between adjacent LDPCA frames to estimate adaptively the parity bit request. Through computer simulations, it is shown that the proposed method achieves about 80% of latency reduction compared to the conventional no-estimation DVC system.

• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.51-60
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• 2003

As piling works in urban area are increasing, SIP which has low noise & vibration piling method takes the place of driven pile which has good bearing charateristics and is economical. Although SIP has been used far more than 15 years and it's use is increasing year by year, accurate analysis of bearing mechanism of SIP is not enough. So the design of SIP is much more conservative than driven pile. This paper is aimed at analysing the bearing charateristics of 103 SIPs constructed in Korea to give rational design criteria. Research result shows that bearing capacity of SIP is 40% lower than that of driven pile and conservative Meyerhof(20$\bar{N}_b'A_b$) method produced closer result to load test results than any other design method. And this result shows that in order to use optimised design criteria for the economical SIP design, quality control criteria must be settled down to produce high bearing capacity.