• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.43 no.1
• /
• pp.61-68
• /
• 2017

The key quality attributes of the pressed powder, one of base makeup products, are skin-affinity and spreadability. In general, there was a limit to meet skin-affinity and spreadability simultaneously, which are opposite attributes each other. In this study, air jet mill process was tried to satisfy two main properties. Skin-affinity was improved by a wet coating of sericite with a mixture of lauroyl lysine (LL) and sodium cocoyl glutamate (SCG). The application of mono-dispersed polymethyl methacrylate (PMMA) and diphenyl dimethicone/vinyl diphenyl dimethicone/silsesquioxane crosspolymer (DDVDDSC) improved both qualities. Air jet mill process has been mainly applied in the pharmaceutical and food industries, and is a method used for processing powder materials in cosmetic field. In this study, we were able to complete makeup cosmetics with an optimum particle size $6.8{\mu}m$ by combining the air jet mill process at the manufacturing stage. It was confirmed that the Ti element was uniformly distributed throughout the cosmetics by EDS mapping, and that the corners of the tabular grains were rounded by SEM analysis. It is considered that this can provide an effect of improving the spreadability when the cosmetic is applied to the skin by using a makeup tool. LL with excellent skin compatibility and SCG derived from coconut with little skin irritation were wet coated to further enhance the adhesion of sericite. SEM images were analyzed to evaluate effect of the dispersion and uniformity of PMMA on spreadability. With the spherical shapes of similar size, it was found that the spreading effect was further increased when the distribution was homogeneously mono-dispersed. The dispersion and spreadability of PMMA were confirmed by measuring the kinetic friction and optimal content was determined. The silicone rubber powder, DDVDDSC, was confirmed by evaluating the hardness, spreading value, and drop test. Finally, it was found that the dispersion of PMMA and silicone rubber powder affected spreadability. Such makeup cosmetics have excellent stability in drop test while having appropriate hardness, and good stability over time. Taken together, it is concluded that air jet mill process can be utilized as a method to improve skin-affinity and spreadability of the pressed powder.

• The korean journal of orthodontics
• /
• v.28 no.2 s.67
• /
• pp.329-341
• /
• 1998

Sterilization has received much attention in orthodontic practices over the past several years. The present study was undertaken to investigate the effects of sterilization on the physical properties of orthodontic pliers-AEZ, Unitek, and Dentronix ligature cutters. This study was designed to examine the tips of ligature cutters before and after 200 and 400 sterilization cycles using the Bowmar RHT-1000, the Dentronix DDS-5000, and the Eschmann SES-2000. The tip surface and the fracture surface were observed with a scanning electron microscope. The microstructure was observed with an optical microscope. The hardness test was carried out with the mic개-Vickers hardness tester and the Rockwell C Scale hardness tester. The chemical composition was analyzed by energy dispersive X-ray spectrometer. The results of this study were as follows : 1. The number and the size of corrosion products on the tip surface and the proportion of cleavage planes in fractured specimen increased, but the hardness of the tip decreased in proportion to sterilization cycles. From these observations, it was considered that mechanical properities decreased in proportion to sterilization cycles. 2. The number and the size of chromium carbides increased in proportion to sterilization cycles. Coarse microstructure decreased mechanical properities. 3. The AEZ and Unitek ligature cutters were Fe-Cr stainless steels, but the Dentronix ligature cutter was Co-Cr alloy. There were many differences among manufactures, but the chemical composition was .not changed after sterilization cycles. 4. The tip edge of ligature cutter used in a clinic revealed microcracks with the SEM observation. Clinical experience confirmed that ligature cutters were gradually degraded by sterilization.

• Journal of Korean Society for Quality Management
• /
• v.5 no.2
• /
• pp.59-120
• /
• 1977

An antibiotic 'P', which is one of the products of the Gist Brocades N. V. is being tested by its research department as fungicide on seed-potatoes. For this testing they designed experiments, with two control groups, one competitor's product, eight formulations of the antibiotic to be tested in different concentrations and one mercury treatment which can not be used in practice. The treated potatoes were planted in three different regions, where bifferent conditions prevail. After several months the harvested potatoes are divided in groups according to their diameter, potato illness is analysed and counted. These data were summarised in percentage and given to us for Analysis. We approached and analysed the data by following methods: a. Computation of the mean and standard deviation of the percenage of good results in each size group and treatment. b. Computation of the experimental errors by substraction of each treatment mean from observed data. c. Description of the frequency table, plotting of a histogram and a normal curve on same graph to check normality. d. Test of normality paper and chi-sqeare test to check the goodness of fit to a normal curve. e. Test for homogeneity of variance in each treatment with the Cochran's test and Hartley's test. f. Analysis of Variance for testing the means by one way classifications. g. Drawing of graphs with upper and lower confidence limits to show the effect of different treatments. h. T-test and F-test to two Control mean and variance for making one control of Dunnett's test. i. Dunnett's Test and calculations for numerical comarision of different treatments wth one control. In region R, where the potatoes were planted, it was this year very dry and rather bad conditions to grow potatoes prevailed during the experimental period. The results of this investigation show us that treatment No.2, 3 and 4 are significantly different from other treatments and control groups (none treated, just like natural state). Treatment no.2 is the useless mercury formulation. So only No. 3 and 4, which have high concentrations of antibiotic 'P', gave a good effect to the potatoes. As well as the competitors product, middle and low concentrated formulations are not significantly different from control gro-ups of every size. In region w, where the potatoes got the same treatments as in region R, prevailed better weather conditions and was enough water obtainable from the lake. The results in this region showed that treatment No. 2, 3, 4, and 5 are Significantly different from other treatments and the control groups. Again No.2 is the mercury treatmentin this investigation. Not only high concentrated formulation of antibiotic 'P', but also the competitor's poroduct gave good results. But, the effect of 'P', was better than the competitors porduct. In region G, where the potatoes got the same treatments as in the regions R and w. and the climate conditions were equal to region R, the results showed that most of the treatments are not significantly different from the control groups. Only treatment no. 3 was a little bit different from the others. but not Significantly different. It seems to us that the difference between the results in the three regions was caused by certain conditions like, the nature of the soil the degres of moisture and hours of sunshine, but we are not sure of that. As a conclusion, we can say that antibiotic 'P' has a good effect on potatoes, but in most investigations a rather high concentration of 'P' was required in formulations.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.8
• /
• pp.1165-1170
• /
• 2010

A method for the determination of four pesticide compounds, urea (isoproturon), bis-carbamate (phenmedipham), thiocarbamate (pyridate) and vinyllidenediamine (nitenpyram) were examined and analyzed by HPLC with C-18 column ($250\;mm{\times}4.6\;mm$, $5\;{\mu}m$ diameter particle size). Mobile phase consisted of deionized water, acetonitrile and 50 mM $KH_2PO_4$ (pH 2.5). Isoproturon and phenmedipham analytical condition was isocratic elution of the column with 50% solvent A (acetonitrile) and 50% solvent B (deionized water); pyridate was 85% solvent A (acetonitrile) and 15% solvent B (deionized water) at a flow rate of 1 mL/min; and nitenpyram analytical condition was 90% solvent A (50 mM $KH_2PO_4$, pH 2.5) and 10% solvent B (acetonitrile) at a flow rate of 1 mL/min. In results, retention times were 6.12, 8.63, 9.40 and 12.76 min for isoproturon, phenmedipham, pyridate and nitenpyram, respectively. All injection volumes were $10\;{\mu}L$ and the limit of quantitation was 0.05 mg/kg for four pesticide compounds, respectively. Recovery rate test was performed with three farm products, rice, apple and soybean. Four pesticide compounds were spiked at concentrations of 0.05, 0.1 and 0.5 mg/kg. The recovery rates were ranged from 70.18% to 118.08% and the standard deviations of all experiments were within 10%.

• Journal of the Korean Applied Science and Technology
• /
• v.32 no.1
• /
• pp.148-156
• /
• 2015

In this study the differences in the sample size and sample input changes as characteristics of bio-oil oak(Quercus variabilis), the oak 0.5~2.0 mm of the oak weighing 300~900g was processed into bio-oil via fast pyrolysis for 1.64 seconds. In this study, the physico-chemical properties of biooil using oak were investigated. Fast pyrolysis was adopted to increase the bio-oil yield from raw material. Although the differences in sample size and sample input changes in the yield of pyrolysis products were not significantly noticeable, increases in the yield of bio-oil accounted for approximately 60.3 to 62.1%, in the order of non-condensed gas, and biochar. When the primary bio-oil obtained by the condensation of the cooling tube and the seconary bio-oil obtained from the electric dust collector were measured separately, the yield of primary bio-oil was twice as higher than that of the secondary bio-oil. However, HHV (Higher Heating Value) of the secondary bio-oil was approximately twice as higher than that of the primary bio-oil by up to 5,602 kcal/kg. The water content of the primary bio-oil was more than 20% of the moisture content of the secondary bio-oil, which was 10% or less. In addition, the result of the elemental analysis regarding the secondary bio-oil, its primary carbon content was higher than that of the primary bio-oil, and since the oxygen content is low, the water content as well as elemental composition are believed to have an effect on the calorific value. The higher the storage temperature or the longer the storage period, the degree of the viscosity of the secondary bio-oil was higher than that of the primary bio-oil. This can be the attributed to the chemical bond between the polymeric bio-oil that forms during the storage period.

• Journal of the Korean Magnetics Society
• /
• v.15 no.1
• /
• pp.42-47
• /
• 2005

Nanocrystalline Nd-Fe-B powder was synthesized by a new thermochemical process that combined with past reduction-diffusion process and spray-dry process. In this process, Ca reduction process is vary important due to formation of hard magnetic$Nd_{2}Fe_{14}B$ phase from various oxides by Ca powder. Therefore, the final products are essentially affected a shape, size, and composition etc. of the Ca reduced powders. Ca reduction was performed to way that raw powders just mixed with Ca powder in proper ratio unlike to compress into compact. The powders after mixture-type Ca reduction mainly composited with $Nd_{2}Fe_{14}B$ phase even relativily low reaction temperature ($800^{\circ}C$) and all particle size of powder were distributed less than 1 ${\mu}m$ except for powder after Ca oxides as magnetic properties of powders after cake-type Ca reduction, with the consequence that high magnetic properties has been expected. The magnetic properties of powders prepared by mixture-type Ca ruduction, with the conseqence that high magnatic properties has been expected. The magnetic properties of powders prepared by mixture-type Ca reduction process showed $_iH_c$ = 5.9 kOe, $B_r$ = 5.5 kG, (BH)max = $Nd_{2}Fe_{14}B{\to}Nd_{2}Fe_{17}B$ decomposition by violent exothermic reaction during washing.

• Korean Business Review
• /
• v.17 no.2
• /
• pp.63-87
• /
• 2004

To create and maintain comparative supremacy as a strategic tool of business, many organizations have introduced informational technology and system. By using this system, Some companies got a beneficial value for achieving organizational goals but others could not obtain their effectiveness and efficiency. In particular, a lot of organizations that tried to make strategic supremacy with e-commercial trade are under hard condition because of poor profit. It implies that it is essential to identify and analyse the consumer who uses e-commercial trade. This paper, therefore, focusing on internet shopping malls between business and consumer as one of areas of e-commercial trades, shows the difference between consumer expectation and performance. The results of this study are as follows: First, as for the significant difference of influencing factors to consumer satisfactions according to the types of internet shopping malls, there is a meaningful difference in consumer anxiety and internet usefulness, but not in consumer service. Prior to verify the differences in detail on consumer's anxiety and internet usefulness, we examined that there is any difference between expectation and performance. T-test was used for the variants of consumer anxiety and internet usefulness, and its meaningful probability was 0.000, which means that both showed statistically significant difference. Based on the results, we also found that regardless of the types of internet shopping malls, consumer expectation was greater than performance. although the difference between expectation and performance was not equal according to the internet shopping malls. Second, a regression analysis was performed to understand the relation between consumer service, internet usefulness, consumer anxiety, and consumer satisfaction, it was found that consumer service, internet usefulness, consumer anxiety had significantly effected on consumer satisfaction. Third, To verify the relation between consumer satisfaction and repurchase-intentions, intentions to spread out, Pearson correlation analysis was used. it was found that consumer satisfaction had positive effect on both intentions. This study has some limitations because of the shorts of money and time. since the sample of this study was consumers who have ever bought one or more products via internet shopping mall, this sample was appropriate. but the major parts of sample were college students, and the sample size was so small. therefore this results should carefully be generalized. For further study, it is required to select more precise samples and to include more variables.

• The Journal of Korean Academy of Prosthodontics
• /
• v.46 no.2
• /
• pp.175-184
• /
• 2008

Purpose: This study was designed to investigate the fitness of adjustable dental impression trays on the Chinese and the Japanese. Material and methods: Initial design of the adjustable dental trays was developed from the results of the dental arch size of Korean adults. This design was applied to the CAD-CAM process in order to create tray model samples. Simple silicon-base molds were then replicated based on these sample models. Polyurethane injection into the silicon- base molds completed the process of creating a large number of test products. 60 Chinese dental students (male:30, female:30) from the Shanghai Second Medical University and 60 Japanese alumni from the Kumamoto high school (male:30, female:30) were selected for taking irreversible hydrocolloid impression with these trays. The width and length of the impression body were measured on several measuring points by Vernier caliper. The results were analyzed statistically to evaluate the fitness of the trays. Results: 1. Uniform impression material thickness was achieved on the Chinese and Japanese by controlling the width of the tray using stops and beveled guides. The material thickness was generally within the range of 3 mm to 6 mm. 2. In the maxillary tray of the Chinese, average thickness of the impression material of the labial vestibule of the incisal teeth was 6.2 mm, the canine was 5.9 mm and the midpalatal part 10.5 mm and the posterior palatal part 9.7 mm. These were relatively large values. 3. In the mandibular tray of the Chinese, average length of the impression material of the lingual vestibule of first, second premolar contact point was 8.9 mm, the incisal teeth was 7.8 mm and thickness of the labial part of canine was 6.8 mm and premolars 7.0 mm. These were relatively large values. 4. In the maxillary tray of the Japanese, average thickness of the impression material of the labial vestibule of the incisal teeth was 7.4 mm, the canine was 7.7 mm and the midpalatal part 9.1 mm. These were relatively large values. 5. In the mandibular tray of the Japanese, average thickness of the impression material of the labial vestibule of first, second premolar contact point was 8.4 mm, and thickness of the labial part of canine was 7.4 mm. These were relatively large values. Conclusion: This adjustable dental tray shows good accuracy to Korean because it was designed by the analysis of the dental arch size of Korean adult model. With this result, it can be applied to Chinese and Japanese, we can take more easy and accurate dental impressions.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.5
• /
• pp.399-407
• /
• 2009

Laser induced breakdown spectroscopy(LIBS) is an simple analysis method for directly quantifying many kinds of soil micro-elements on site using a small size of laser without pre-treatment at any property of materials(solid, liquid and gas). The purpose of this study were to find an optimum condition of the LIBS measurement including wavelengths for quantifying soil elements, to relate spectral properties to the concentration of soil elements using LIBS as a simultaneous un-breakdown quantitative analysis technology, which can be applied for the safety assessment of agricultural products and precision agriculture, and to compare the results with a standardized chemical analysis method. Soil samples classified as fine-silty, mixed, thermic Typic Hapludalf(Memphis series) from grassland and uplands in Tennessee, USA were collected, crushed, and prepared for further analysis or LIBS measurement. The samples were measured using LIBS ranged from 200 to 600 nm(0.03 nm interval) with a Nd:YAG laser at 532 nm, with a beam energy of 25 mJ per pulse, a pulse width of 5 ns, and a repetition rate of 10 Hz. The optimum wavelength(${\lambda}nm$) of LIBS for estimating soil and plant elements were 308.2 nm for Al, 428.3 nm for Ca, 247.8 nm for T-C, 438.3 nm for Fe, 766.5 nm for K, 85.2 nm for Mg, 330.2 nm for Na, 213.6 nm for P, 180.7 nm for S, 288.2 nm for Si, and 351.9 nm for Ti, respectively. Coefficients of determination($r^2$) of calibration curve using standard reference soil samples for each element from LIBS measurement were ranged from 0.863 to 0.977. In comparison with ICP-AES(Inductively coupled plasma atomic emission spectroscopy) measurement, measurement error in terms of relative standard error were calculated. Silicon dioxide(SiO2) concentration estimated from two methods showed good agreement with -3.5% of relative standard error. The relative standard errors for the other elements were high. It implies that the prediction accuracy is low which might be caused by matrix effect such as particle size and constituent of soils. It is necessary to enhance the measurement and prediction accuracy of LIBS by improving pretreatment process, standard reference soil samples, and measurement method for a reliable quantification method.

• Journal of Korea Foundry Society
• /
• v.41 no.2
• /
• pp.144-152
• /
• 2021

Based on the analysis of the current state of the world's foundry industry, we looked at the international competitiveness of Korea's foundry industry for the past 20 years. Korea's total foundry production is 2.52 million tons, and the production per company (so-called productivity) is 2,831 tons, which is the eighth largest in the world and down one position for the case of total foundry production, while productivity remains its position compared to three years ago. Korea is the only one of the top 10 foundry to see a decline in production. Similar to the global situation, Korean products consist of 38% of grey csat iron, 31% of ductile cast iron, 15% of aluminum, and 9% of cast steel. In order to obtain statistics on Korea's foundry industry, the survey conducted a service project for approximately nine months from April 2020. Various statistical surveys and sample in-depth surveys by the Korean standard industry class were evaluated for various contents of the domestic casting industry. We also looked at the number of companies, the distribution by region, the number of workers and the percentage of foreigners, and the distribution of each job, as well as the R&D investment status according to the size of the enterprise. Together, sales, exports, sales and various profit ratios were analyzed to measure the earning power of foundry industry. In addition, the classification by grouping the foundry industry according to the process utilized by focusing on each company, and to determine the sales, exports, and yield status for each process was also investigated on the basis. Based on these data, the domestic foundry industry has presented a variety of offers for the following issues for sustainable growth; global ranking, marginal corporate restructuring, training of domestic technical people, differentiated support policies by company size and process.