• Journal of dental hygiene science
• /
• v.11 no.5
• /
• pp.445-453
• /
• 2011

Objectives : The purpose of this study was to determine of fluoride-releasing of orthodontic resin cements containing fluoride and compare decalcification of tooth attached fluoride and non-fluoride resin cements. Methods : Total eighty premolar tooth were used in this study. Forty tooth were used for fluoride releasing measurement and forty tooth were used for decalcification measurement. Each forty tooth were randomly divided into four groups, and brackets were attached on tooth surface with Blugloo, Light Bond, Orthofolw(experimental groups) and Transbond cement(control group). After brackets were attached on tooth surface, forty tooth were immersed in artificial salival and then the quantity of fluoride releasing was measured ever day for 8days and then three-days intervals for 3 weeks. Forty tooth were immersed in decalcification solution for 48hours and then degree of decalcification was measured as lesion area, ${\Delta}F$, and ${\Delta}Q$ using QLF. The data were analysed by one-way ANOVA and Pearson's correlation coefficient using SPSS 12.0 program. Results : Fluoride release of experimental groups was higher than control group(p<0.05). Cumulative fluoride release of experimental groups was also higher than control group(p<0.05). There were the highest release during first day. ${\Delta}F$, and ${\Delta}Q$ was high TB > BG > OF > LB (p<0.05). Change of ${\Delta}F$, and ${\Delta}Q$ was also high TB > BG > OF > LB (p<0.05). As for correlation between fluoride release and lesion area, ${\Delta}F$, and ${\Delta}Q$ showed negative correlation but there was no significant difference. Conclusions : This study shows that orthodontic reins cements containing fluoride release fluoride and prevent initial enamel decalcification caused by orthodontic treatment.

• Korean Journal of Plant Resources
• /
• v.30 no.5
• /
• pp.556-564
• /
• 2017

Appropriate soil temperature and early planting of potato is very important for the successful potato-soybean cropping system in central region of South Korea. This experiment was carried out to determine the effect of mulching materials on the growth and yield of potato (Solanum tuberosum L.). Five different mulch treatments were had been applied on an upland soil as follows ; no mulch (NM), transparent film (TF), transparent film + additional transparent film (TF + ATF), black film (BF), and black film + additional transparent film (ATF). In the period of sowing time to removing additional films, mean soil temperature of the treatments was in the order of TF+ATF > TF > BR+ATF > BF as $20.3^{\circ}C$ > $18.5^{\circ}C$ > $16.1^{\circ}C$ > $15.4^{\circ}C$, respectively and that of NM was $13.8^{\circ}C$. The accumulated soil temperature was TF > NM > BF during the removing additional films to earthing at inter-tillage. On the changes in the soil temperature during a whole day, the temperature in the BF was lower than NM during around 18:00 PM to 12:00 NM, while NM was higher than BF in the time period of 10:00AM to 21:00PM. The sequence of potato sprout emergence was 15 > 18 > 20 > 22 days of TF+ATF, TF, BF+ATF, and BF, respectively and that of NM was 24 days. Comparing to the NM, potato sprout emergence was observed on the TF+ATF treated plot as early as 9 days. At 10 days before harvest, the significant difference in the tuber dry weight had been observed and the sequence tuber weight was in the order of TF > TF+ATF > BF+ATF > BF > NM. The potato yields of TF, TF+ATF, and BF+ATF were increased of 40.7, 37.3, and 22% as compared to NM ($2,805kg\;10a^{-1}$), but almost same yield in the BF. The differences of tuber dry weight and potato yields was co-related with the temperature rise of soil by the application of mulching materials on soil. Based on these results, application of mulching film had been very effective to increase the tuber size and the yield of potato by the temperature rise during seedling stage of potato. Transparent mulching was better than black mulching especially for the emergence of sprout of potato in relation to minimizing cooling injury.

• Korea journal of population studies
• /
• v.25 no.2
• /
• pp.5-40
• /
• 2002

Using detailed data of women's work history, this study analyses the transition process between employment and non-employment over the life history in order to identity individual and structural determinants in the processes. Korean women comprise very heterogeneous groups in terms of work continuity: one group having a continuous work history and another having an interrupted work experience. While 4.0% of total women have stayed in the labor market since leaving school, 17.3% have not worked outside at all and remaining 87.9% have experienced into and out of the labor market at least once. On the average, the cumulated time of employment per woman is 8.2 years and the cumulated time of unemployment is 13.1 years. Thus Korean women work a total of only 38.5% of their whole lifetime after leaving school. We can conclude that the increase of the employment rate of married women in Korea since the 1970s has been due to the increase of the new entrants with short or little working careers into the labor market, not to the increase of women's work continuity on the whole. A women's educational achievement does not seem to be positively related to employment duration, contrary to the suggestion of the human capital theory, Rather, family variables, especially the existence of the child under 6 yens old, is a more significant determining factor for an individual's exit from employment. And there is little difference among different age cohorts which implies little improvement in the employment continuity of younger women. This study also documents the importance of structural variables, such as the type of occupation, as significant determining factors for the hazard rate. Specially women with professional jobs tend to stay longer in the labor market. Therefore, women's entry into more professional occupations is expected to contribute to the continuity of employment. Our results also show that duration-dependence is not spurious. When unobserved heterogeneity is controlled, the negative relation between the rate from employment and the duration of employment does not disappear.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.40 no.6
• /
• pp.747-756
• /
• 1995

To find out the optimum application method of slow-releasing fertilizer(SRF) and conventional fertilizer(CF) with different fertilization rate under two culture methods[l0-day old seedling machine transplanting(MT) and direct-sowing on dry paddy(DS)] in the south-western region(clay loam soil) of Korea, used were Chosun slow-releasing fertilizer(silicate latex coated fertilizer: N-P$_2$O$_{5}$-K$_2$O =18-12-13) and conventional fertilizer. Plant height and number of tillers with different two culture methods were higher at MT than DS in early growth. The ratio of dry weight in heading stage was higher at CF than SRF in MT than DS and especially, SRF 80% + CF 20% than SRF 100% or CF 100%. Leaf area index (LAI) in heading stage was higher at CF in MT but higher at SRF in DS than their counterparts. Chlorophyll content was higher at SRF than in CF expect for heading stage(HS), especially in DS. It was highest at HS in CF without its difference during maximum tillering stage(MTS) and panicle formation stage(PFS), while highest at PFS in SRF with tendency of gradual increase and decrease before and after PFS, respectively. Heading was delayed 2~3 days at SRF in two cultrue methods and 4~5 days at SRF in DS in comparison with CF in MT with delay of 2 days at DS compared with MT. Culm length was longer at CF in MT and at SRF in DS than their counterparts. Panicle number per m was more at SRF and in DS. Filled grain ratio was higher at CF and in MT. Yield was obtained 101 and 100% at 100% and 80% level of SRF in DS respectively, and 96% at 80% level of CF in MT, compared with conventional application method (516kg /l0a), and increased 2~4% at DS and 0~3% at MT in SRF. Yield was high in order of 100%(SRF) =80%(SRF) + 20%(CF) > 100%(SRF) + 20%(CF) > 80%(SRF) at MT and 80%(SRF) + 20%(CF) =100%(SRF) > 80%(SRF) =100%(SRF) + 20%(CF) at DS.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.40 no.6
• /
• pp.684-696
• /
• 1995

A mutant for chalky endosperm and genetic male sterility (GMS) was newly developed in rice. The two characters were found to be controlled by single recessive gene which has pleiotropic effect, indicating that chalky seeds should be GMS seeds in segregating populations. Chalky seeds showed the same shape and size as normal seeds. However, starch composition of central part of endosperm was looser and shape of starch granules was rounder compared with normal endosperm, resulting in significantly lower grain weight, absolute density and grain hardness in chalky grains than in normal ones. Amylose content and gel consistency of chalky grains were much lower and harder, respectively. Male sterile plants showed much shorter plant height, poorer panicle exsertion and lesser panicle number compared with normal plants. Microspore abortion stage in pollen developmental process was observed as before meiosis. Male sterility of the mutant was stable regadless of temperature and day length. A system breeding hybrid rice using this mutant was discussed, comp ring with other systems utilizing cytoplasmic-genic male sterility(CGMS) and environment sensitive GMS(EGMS). Separation of GMS seeds in mixed seed bulks by specific gravity (1.14∼1.16g / cm3) was successful about 85∼90%. But some mixed normal plants were seemed to be easily removed by the apparent difference in growth characters at seedling stage. The highest natural outcrossing rate of this GMS line was as 17.3 % in a plot treated with 2-row pollinator, I-row GMS, and GA3 + cutting of flag leaf + pollen-scattering by rope.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.32 no.3
• /
• pp.486-493
• /
• 2008

Safflower red colorants extracted by two solvents including the traditional ash solution and $K_{2}CO_{3}$ solution was used for dyeing cotton, ramie, viscose rayon, silk, wool, and nylon fabrics. The effects of extraction solvents on the reflectance, K/S value, and color properties of the dyed fabrics were investigated. Wash/dry cleaning and light colorfastness were evaluated. Reflectance curves of cotton, ramie, viscose rayon, and silk fabrics dyed with red colorants extracted by $K_{2}CO_{3}$ solution were similar, showing the maximum absorption at 520nm, to that of the dyed fabrics with red colorants extracted by ash solution. The reflectance curves of wool and nylon fabrics were different, showing the maximum absorption at 400nm. K/S values of dyed fabrics with red colorants extracted by $K_{2}CO_{3}$ solution were higher than that by ash solution with the exception of nylon. $L^{*},\;a^{*},\;b^{*}$, and $C^{*}$ of the dyed fabrics with red colorants extracted by $K_{2}CO_{3}$ solution were higher than that by ash solution except for $L^{*}$ of nylon and $b^{*}$ of viscose rayon. Color difference(${{\Delta}E}^*$) of the dyed fabrics between ash solution and $K_{2}CO_{3}$ solution increased in the order named as cotton, silk, ramie, viscose rayon, wool, and nylon. Regardless of extraction solvents, safflower red colorants produced RP color on cotton, ramie, and nylon, R color on viscose rayon and silk, and YR color on wool. Wash/dry cleaning fastness of the dyed fabrics was high above 3/4 rating but light fastness was very poor. It is considered that the use of $K_{2}CO_{3}$ solution instead of the traditional ash solution would be more effective in terms of color reproducibility and extraction process.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.63 no.3
• /
• pp.229-238
• /
• 2018

The purpose of this study was to evaluate the effects of nitrogen fertilization amount and timing of application on protein content, dough properties, change in protein fraction, and bread loaf volume for Korean wheat cultivars, Baekkang, Joongmo2008, and Saekeumkang, for bread with a superior gluten composition during the grain filling stage. Protein content increased with an increase in the amount of N and timing of application. The SDS segmentation volume (SDSS) increased with an increase in N, but there was no effect of the timing of N application on SDSS. An increase in N amount and timing of application caused a difference in dough properties, such as water absorption, mixing time, and tolerance, among the cultivars. Soluble and insoluble polymeric and monomeric protein contents increased with an increase in N amount and timing of application the three Korean wheat cultivars. The effects of N amount and application timing on bread loaf volume (BLV) varied among the cultivars. The BLV of Saekeumkang increased regardless of the N amount and timing of application, but that of Baekkang and Joongmo2008 cultivars was reduced. However, there was a positive correlation between protein content with the addition of N fertilization and BLV. In addition, SDSS, mixing time, and protein fractions were positively correlated with BLV. Since the response of fertilizer conditions was different for each wheat cultivar, it is necessary to build a suitable fertilizing system for each of them. Additionally, since the environment is changing, such as abnormal climate during the maturing period, research is needed to establish appropriate fertilizer conditions for varieties of bread wheat.

• Horticultural Science & Technology
• /
• v.30 no.5
• /
• pp.484-492
• /
• 2012

The present study aimed to investigate the effect of static magnetic field (SMF) on the growth and physiological characteristics of common indoor plant species. Five foliage plant species, Spathiphyllum spp., Ardisia pusilla DC., Syngonium podophyllum, Peperomia pereskiifolia, and Pilea cadierei were potted into plastic pot equipped with round type anisotropic sintered NdFeB permanent magnet inside the pot. The surface magnetic flux density of each magnet was 3,500 G. After 6 months of growth period, the biomass accumulations of Spathiphyllum, A. pusilla, and P. cadierei under SMF were statistically higher than those of controls. Tissue water content also increased under the influence of SMF in most species. The photosynthetic rate of Spathiphyllum under SMF significantly increased but other species showed no significant difference compared with control. Although there was no significant increase in the photosynthetic rates of A. pusilla, and P. cadierei, they showed remarkable increase in total fresh weight under SMF. This suggests that the demand of assimilates for normal metabolism could be decreased under magnetic influence and thereby biomass accumulation could be more favored. But this is not always true for all plant species because P. pereskiifolia in this experiment, showed no changes in both photosynthetic rate and biomass accumulation. Leaf nitrogen and chlorophyll contents were enhanced significantly in most plant species under influence of SMF. Chlorophyll a/b ratio also increased by SMF. Although there might be a limitation depending on plant species, these results suggest that long-term exposure to SMF might allow plant to have an enhanced acclimation capacity against environmental fluctuations and optimal application of SMF could increase the practical use of indoor plants such as an attempt to improve indoor air quality.

• Korean Journal of Poultry Science
• /
• v.30 no.1
• /
• pp.17-28
• /
• 2003

A feeding trial was carried out to evaluate the effects of feeding Lactobacillus reuteri culture(LRC) on the performance, nutrients digestibility, intestinal microflora, serum metabolites, ammonia generation and litter dampness in broiler chicks. Four hundred eighty, one day old male chicks were fed into none, 0.1, 0.2 and 0.4% of LRC supplementation fer seven weeks. Basal diets excluded antibiotics contained ME 3,100, 3,100 kcal/kg, and CP 22.0, 20.0% for starter and grower, respectively. Weight gain of chicks fed LRC was significantly higher than no supplemental group in overall period(P<0.05). Feed intake was the highest in the 0.1% LRC, but not statistically different from other treatments. Feed conversion showed no significance among treatments. Viable Lactobacillus spp. number of chicks fed 0.2 and 0.4% LRC was significantly higher in cecum at seven weeks of age compared to the none(P<0.05). The tendency of anaerobes number was similar to Lactobacillus spp in ileum and cecum. Total number of E. coli and Salmonella were no difference in all treatments. In serum metabolites, feeding LRC increased triglyceride, and inorganic phosphorus, but no different total protein, albumin, total cholesterol, glucose, blood urea nitrogen and Ca. Nutrients digestibility improved significantly in 0.4% LRC compared to that of none(P<0.05). Fecal NH$_3$, gas generation was greatly decreased in the LRC supplemental groups(P<0.05). Moisture contents of bedding was also significantly decreased in LRC feeding group. It was concluded from the present study that feeding Lactobacillus reuteri culture improved the growth performance and nutrients digestibility of broiler chicks and minimize the fecal noxious gas emission.

• Korean Journal of Poultry Science
• /
• v.37 no.2
• /
• pp.145-150
• /
• 2010

This study was conducted to evaluate effects of dietary Agariemycetes on egg quality and fecal noxious gas concentration in laying hens. A total of two hundred forty laying hens were randomly allocated to four treatments with five replicates of twelve chicks per pen. The experiment lasted 42 days with a 7-day adjustment period. Dietary treatments were as follows: 1) CON (basal diet), 2) A1 (basal diet + Agariemycetes 0.1%), 3) A3 (basal diet + Agariemycetes 0.3%) and 4) A5 (basal diet + Agariemycetes 0.5%). There was no significant difference in egg production and egg weight between CON and Agariemycetes treatments. During the second week of the experiment, eggshell breaking strength was higher in A3 and A5 treatments than that in CON treatment (P<0.05). Besides, eggshell breaking strength in P5 treatment was higher when compared with that in CON treatment (P<0.05) in the sixth week. During the second week of the experiment, eggshell thickness was higher in Agariemycetes treatments than CON treatment (P<0.05). Also, A5 treatment was higher than other treatments in the fourth week of the experiment (P<0.05). At the end of the second week, yolk color unit in A5 treatment was lower compared with CON treatment (P<0.05). During the fourth week of the experiment, CON treatment was higher than A3 treatment (P<0.05). During the second week of the experiment, Haugh unit in A3 treatment was greater than that in CON treatment (P<0.05). At the end of six weeks, Haugh unit in CON treatment was lower than other treatments (P<0.05). Fecal ammonia and hydrogen sulfide were increased in Agariemycetes treatments when compared with CON treatment (P<0.05). Compared with CON and A5 treatments, fecal mercaptans was higher than in other treatments in first of the experiment (P<0.05). In conclusion, this study indicated that the addition of Agariemycetes in the diet improved the egg quality and decreased the feacal noxious gas concentration in laying hens.