• Restorative Dentistry and Endodontics
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• v.18 no.1
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• pp.73-83
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• 1993

The purpose of this study was to evaluate the effect of various acid treatments on dentin bonding. Freshly extracted human teeth were uprightly embedded in self curing acrylic resin, and their occlusal surfaces were grinded to expose flat dentin surfaces. The specimens were divided into 4 groups. Specimens of one group were not treated so as to be a control and those of the other three groups were threated with 10% polyacrylic acid, 10% phosphoric acid, and 10-3 solution(10% citric acid/3% ferric chloride) respectively. Primer, bonding resin and composite resin were applied over the treated dentin surfaces sequentially. All specimens were stored in $37^{\circ}C$ distilled water for 24 hours, then the tensile bond strength was measured and the treated dentin surfaces and fracured dentin surfaces were examined under a scanning electron microscope. The results were as follows: Bond strengths of acid-treated groups were higher than those of the untreated group. In the acid-treated groups, bond strength was found to be the highest in the 10-3 solution group followed by the 10% phosphoric acid group and the 10% polyacrylic acid group(P<0.01). On SEM examination of dentin surfaces, the untreated dentin surface showed a remaining smear layer and closed dentinal tubules. Dentin surfaces treated with 10 % polyacrylic acid showed a clean dentin surface without the smear layer, but showed remaining smear plugs in dentinal tubules. A dentin surface treated with 10% phosphoric acid or 10-3 solution showed open dentinal tubules without the smear layer or smear plugs. On SEM observation of the fractured dentin-resin interface, the untreated group showed that failure occurred in the smear layer. The group treated with 10% polyacrylic acid showed no resin tag remained in the dentinal tubules, but resin tags in the dentinal tubules were observed in the group treated with the 10% phosphoric acid or the 10-3 solution. On the failure mode examination, the higher the bond strength of the group, the higher the frequency of cohesive failure. The coefficient between bond strength and cohesive failure rate was 0.71.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.1
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• pp.1-7
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• 2006

To designate rural landscape spatially, land use and topographic features for 383 of "Ri"s or "Dong", which is a basic administrative unit in Korea, were analyzed using GIS application. We have categorized rural landscape into three types such as agricultural, natural and urban landscape by land use. On the basis of spatial landscape pattern, rural area could be classified into 6 groups of Mountainous area (MA), Mountainous village area (MV), Developing mountainous village area (DM), Plain agricultural area (PA), Developing plain village area (DP) and Urbanized area (UA) according to the ratios of land for agricultural and urban use as the criteria. In MA, the ratio of upland area including orchard was slightly larger than that of paddy, while that of paddy was about 1.5 times larger than upland in other groups. Forested area was distributed more than two-thirds among natural landscape area in MA, MV and DM. In plain types (PA and DP), the ratio of irrigated paddy was extremely larger than partially irrigated paddy and the ratio of water body area among the natural landscape area was two times as large as that of forested area. The ratio of land for industrial and livestock facilities among urban landscape area were 20% or more in MV, DM and DP, and it means that these facilities are mainly distributed in the developing ru ral area where residents and industry are closely related each other. According to the relative ratio of sloped land of 6 categorized areas, the MA area have lots of land with E and F slopes and MV and DM have all grades of sloped land evenly distributed in relative to other types of rural landscape. It has been showed that PA, DP and UA occupied more than two-thirds of land with A or B slope. In case of the analysis of topological distribution in 6 types of rural landscape, there were overwhelmingly lager highland areas in MA. Conclusively, we have confirmed that 6 types of rural landscape classified by land use pattern in 3 categorized areas such as agricultural, natural and urban landscape area would be useful for the management of rural area. For development of sustainable agriculture and the preservation of rural amenity, proper management ways should be properly applied according to rural landscape patterns.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.88-89
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• 2013

A variety of influenza A viruses from animal hosts are continuously prevalent throughout the world which cause human epidemics resulting millions of human infections and enormous industrial and economic damages. Thus, early diagnosis of such pathogen is of paramount importance for biomedical examination and public healthcare screening. To approach this issue, here we propose a fully integrated Rotary genetic analysis system, called Rotary Genetic Analyzer, for on-site detection of influenza A viruses with high speed. The Rotary Genetic Analyzer is made up of four parts including a disposable microchip, a servo motor for precise and high rate spinning of the chip, thermal blocks for temperature control, and a miniaturized optical fluorescence detector as shown Fig. 1. A thermal block made from duralumin is integrated with a film heater at the bottom and a resistance temperature detector (RTD) in the middle. For the efficient performance of RT-PCR, three thermal blocks are placed on the Rotary stage and the temperature of each block is corresponded to the thermal cycling, namely $95^{\circ}C$ (denature), $58^{\circ}C$ (annealing), and $72^{\circ}C$ (extension). Rotary RT-PCR was performed to amplify the target gene which was monitored by an optical fluorescent detector above the extension block. A disposable microdevice (10 cm diameter) consists of a solid-phase extraction based sample pretreatment unit, bead chamber, and 4 ${\mu}L$ of the PCR chamber as shown Fig. 2. The microchip is fabricated using a patterned polycarbonate (PC) sheet with 1 mm thickness and a PC film with 130 ${\mu}m$ thickness, which layers are thermally bonded at $138^{\circ}C$ using acetone vapour. Silicatreated microglass beads with 150~212 ${\mu}L$ diameter are introduced into the sample pretreatment chambers and held in place by weir structure for construction of solid-phase extraction system. Fig. 3 shows strobed images of sequential loading of three samples. Three samples were loaded into the reservoir simultaneously (Fig. 3A), then the influenza A H3N2 viral RNA sample was loaded at 5000 RPM for 10 sec (Fig. 3B). Washing buffer was followed at 5000 RPM for 5 min (Fig. 3C), and angular frequency was decreased to 100 RPM for siphon priming of PCR cocktail to the channel as shown in Figure 3D. Finally the PCR cocktail was loaded to the bead chamber at 2000 RPM for 10 sec, and then RPM was increased up to 5000 RPM for 1 min to obtain the as much as PCR cocktail containing the RNA template (Fig. 3E). In this system, the wastes from RNA samples and washing buffer were transported to the waste chamber, which is fully filled to the chamber with precise optimization. Then, the PCR cocktail was able to transport to the PCR chamber. Fig. 3F shows the final image of the sample pretreatment. PCR cocktail containing RNA template is successfully isolated from waste. To detect the influenza A H3N2 virus, the purified RNA with PCR cocktail in the PCR chamber was amplified by using performed the RNA capture on the proposed microdevice. The fluorescence images were described in Figure 4A at the 0, 40 cycles. The fluorescence signal (40 cycle) was drastically increased confirming the influenza A H3N2 virus. The real-time profiles were successfully obtained using the optical fluorescence detector as shown in Figure 4B. The Rotary PCR and off-chip PCR were compared with same amount of influenza A H3N2 virus. The Ct value of Rotary PCR was smaller than the off-chip PCR without contamination. The whole process of the sample pretreatment and RT-PCR could be accomplished in 30 min on the fully integrated Rotary Genetic Analyzer system. We have demonstrated a fully integrated and portable Rotary Genetic Analyzer for detection of the gene expression of influenza A virus, which has 'Sample-in-answer-out' capability including sample pretreatment, rotary amplification, and optical detection. Target gene amplification was real-time monitored using the integrated Rotary Genetic Analyzer system.

• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.147-152
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• 2015

Nitrogen (N) loading from domestic, agricultural and industrial sources can lead to excessive growth of macrophytes or phytoplankton in aquatic environment. Many studies have used nitrogen stable isotope ratios to identify anthropogenic nitrogen in aquatic systems as a useful method for studying nitrogen cycle. In this study to evaluate the precision and accuracy of Kjeldahl processes, two reference materials (IAEA-NO-3, N-1) were analyzed repeatedly. Measured the ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values of IAEA-NO-3 and IAEA-N-1 were $4.7{\pm}0.2$‰ and $0.4{\pm}0.3$‰, respectively, which are within recommended values of analytical uncertainties. Also, we investigated spatial patterns of ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ in effluent plumes from a waste water treatment plant in Han River, Korea. ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values are enriched at downstream areas of water treatment plant suggesting that dissolved nitrogen in effluent plumes should be one of the main N sources in those areas. The current study clarifies the reliability of Kjeldahl analytical method and the usefulness of stable isotopic techniques to trace the contamination source of dissolved nitrogen such as nitrate and ammonia.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.60-66
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• 2014

This test was performed to evaluate the bactericidal efficacy of a fumigation disinfectant containing 20% ortho-phenylphenol against Pseudomonas aeruginosa (P. aeruginosa) and Enterococcus hirae (E. hirae). In preliminary tests, P. aeruginosa and E. hirae working culture suspension number (N value) were $2.8{\times}10^8$ and $4.0{\times}10^8CFU/mL$, respectively. And all the colony numbers on the carriers exposed to the fumigant (n1, n2, n3) were higher than 0.5N1 (the number of bacterial test suspentions by pour plate method), 0.5N2 (the number of bacterial test suspentions by filter membrane method) and 0.5N1, respectively. In addition, the mean number of P. aeruginosa and E. hirae recovered on the control-carriers (T value) was $2.8{\times}10^8$ and $3.4{\times}10^6CFU/mL$, respectively. In the bactericidal effect of the fumigant, the reduction number of $2.8{\times}10^8$ (d value) was 6.46 and 5.19 logCFU/mL, respectively. According to the French standard for the fumigant, the d value for the effective bactericidal fumigant should be over than 5 logCFU/mL. With the results from this study, the fumigation disinfectant containing 20% ortho-phenylphenol has an effective bactericidal activity, then the fumigant can be applied to disinfect food materials and kitchen appliances contaminated with the pathogenic bacteria.

• Korean journal of food and cookery science
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• v.28 no.4
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• pp.391-397
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• 2012

This study was carried out to investigate commercialization of Kimchi made of cabbage (Brassica oleracea var. capitata L.) using pre-fermentation conditions. The pre-fermentation conditions were 0, 18, 24, and 28 h at $20^{\circ}C$, and then the samples were stored at $10^{\circ}C$ to assess changes in quality characteristics. A comparison of the quality characteristics during storage showed that PF24 (pre-fermented cabbage Kimchi during 24 h at $20^{\circ}C$) and PF28 (pre-fermented cabbage Kimchi during 28 h at $20^{\circ}C$) had pH 4.47 and pH 4.23 on the second day of storage, respectively. It was possible to shorten the fermentation time to less than that of PF0 (not pre-fermented cabbage Kimchi at $20^{\circ}C$), by approximately 3 days. Total acidity was 0.26 to 0.29% immediately after making the Kimchi. However, PF0, PF18 (pre-fermented cabbage Kimchi during 18 h at $20^{\circ}C$), PF24 and PF28 became well-fermented when they were stored for 8~14 days, 3~10 days or 2~3 days. The number of lactic acid bacteria increased with the passage of time in all treatment groups regardless of fermentation conditions. However, the longer pre-fermentation time became, the faster the number of lactic acid bacteria increased. Most samples showed similar results late in the storage period; 7.2~7.4 log CFU/mL. PF0 had the greatest volume change 2.1 times increase late in the storage period. The sensory evaluation showed significant differences for flavor, taste, and overall acceptability after a partial storage period. PF28 stored for 2~3 days showed excellent flavor, and PF24 and PF28 stored for 2~3 days showed the highest scores of 6.27 to 6.67. The PF24 and PF28 treated samples were appropriate for commercializing small packed cabbage Kimchi and for alleviating the expansion problem of the packing material. However, because mass commercial production requires a large number of samples to be used at once, the results should be assessed for industrial product development in the future.

• Food Engineering Progress
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• v.13 no.3
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• pp.203-210
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• 2009

In this study, antioxidant activity and quality characteristics of egg yolk mayonnaise and soy milk mayonnaise containing soybean paste powder were assessed. The mayonnaise with egg yolk as an emulsifier is E group according to the amount of soybean paste powder addition of 0% (E1), 3% (E2), 6% (E3) and mayonnaise with soy milk as an emulsifier is S group with soybean paste powder addition of 0% (S1), 3% (S2), 6% (S3). Total phenol content and electron donating ability of mayonnaise were increased as the amount of the soybean paste powder increased. L value of Hunter's color was decreased, but a value and b value were increased as the amount of the soybean paste powder increased. Soy milk mayonnaise showed very low cholesterol content than egg yolk mayonnaise. In sensory evaluation, S2 received the highest scores for flavor, overall taste and preference. Base on these results, soybean paste powder showed significant antioxidant activity in mayonnaise and cholesterol content was successfully decreased in soy milk mayonnaise compared to egg yolk mayonnaise. The soy milk mayonnaise with soybean paste powder will be a possible model to introduce our traditional food to the worldwide food item, such as mayonnaise.

• Food Engineering Progress
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• v.13 no.2
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• pp.117-121
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• 2009

Detection of spoilage odors from beef during storage was investigated using sensory evaluation with R-index, and microbial assay for Pseudomonas. Beef samples were tested to measure the flavor changes, which were converted to R-index, and the Pseudomonas levels during storage. There was a steep rise in R-index until 36 hr after storage at 25$^{\circ}C$, and then a gentle rise from 48 hr, whereas, there was a steady rise in R-index in the whole range of storage at 5$^{\circ}C$. Detection time of spoilage odors according to R-index was statistically analyzed at $\alpha$=5% to be at 30.92${\pm}$3.47 hr and 169.80${\pm}$11.27 hr for 25 and 5$^{\circ}C$ storage, respectively, and analyzed at $\alpha$=1% to be 34.80${\pm}$4.01 and 176.41${\pm}$9.89 hr for 25 and 5$^{\circ}C$ storage, respectively. At the detection times of spoilage odors, the Pseudomonas levels were found to be almost the same, but less than 6-7 log CFU/g generally known as a standard level at occurrence of spoilage odors in beef. This indicated that some other factors than the Pseudomonas reactions could be associated with generation of spoilage odors.

• Journal of agriculture & life science
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• v.45 no.6
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• pp.41-46
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• 2011

In this study, in addition to the green tea-wood fiber hybrid composite boards of previous researches, to make effective use of saw dust of domestic cypress tree with functionalities and application as interior materials, eco-friendly hybrid composite boards were manufactured from wood fiber, green tea and saw dust of cypress tree. We investigated the effect of the component ratio of saw dust and green tea on static bending strength performances. Static bending MOE (modulus of elasticity) was within 0.956~1.18GPa, and showed the highest value in wood fiber : green tea : saw dust = 50 : 40 : 10 of the component ratio, and had the lowest value in 50 : 30 : 20 of component ratio. These values were 2.0~3.1times lower than those of green tea-wood fiber hybrid composite boards reported in the previous researches. The bending MOR (modulus of rupture) showed 8.99~11.5MPa, the change of the bending MOR with component ratio of the factors was the same as that of bending MOE. These values had 1.9~3.5 times lower value than those of green tea-wood fiber hybrid composite boards, and showed the slightly lower values than the MOR of particle boards (PB) and medium density fiberboards (MDF) prescribed in Korean Industrial Standard. Therefore, it is considered that these hybrid composite boards need to improve strength performances by component ratio change, hybrid composite with other materials and adhesive change etc. in order to industrialize the hybrid composite boards.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.852-857
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• 2010

This study was performed to explore the effect of the clay mineral illite on the improvement of bed soil and plant growth. Red pepper (Capsicum annuum L.) was used as a model vegetable crop. The experiment was performed during the whole six weeks in the glass house of the Chungbuk National University. Its seedlings were cultivated in the bed soil normally used for horticultural purpose. Of the seedlings cultured, the healthy and regular size of seed were selected and cultivated in the pots. They were treated with two forms of illite, particulate (PA) and powder (PW), at the following application rates: standard application[P1 (PA1, PW1), 1:20 (w/w)], two times[P2 (PA2, PW2), 1:10 (w/w)], and four times[P4 (PA4, PW4), 1:5 (w/w)] of standard application. Untreatment (P0) was used as a control pot. At six weeks of cultivation, their growth lengths were correspondingly increased as the application rate was increased ranging from P0, P1, P2, and to P4. Their growth length was a little greater on the application of powder illite (PW) than on the particulate illite (PA). Based on the plant analysis for the root, leaf, stem of red pepper, the uptake amounts of K, Ca, and Mg, were correspondingly increased, as the application rate was increased ranging from P0, P1, P2, and to P4, respectively. At the same application rate, their amounts taken up in the respective parts were higher on the application of PW illite than on the PA one. Especially the amounts of Ca and Mg were higher in the stem, leaf than root. Consequently, it appears that the illite treatment, especially, PW form of illite, enhance the growth of red pepper in the glass house during the whole six weeks of experiment.