• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.158-163
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• 2014

In this study, two commercial PCR and ELISA test kits were examined for identification of eight animal species (beef, pork, chicken, duck, turkey, goat, lamb, and horse) from raw meat and meat products in Korea. The detection limit in RAW meat ELISA kit$^{(R)}$ on three types of meat samples blended with beef, pork and chicken, demonstrated that all meat species were differentiable down to 0.2%. RAW meat ELISA kit$^{(R)}$ on animal species resulted in differentiation rate of 94.5% for beef, 93.3% for pork, 90% for lamb, and 100% for chicken, duck, turkey, goat, and horse. In contrast, Powercheck Animal Species ID PCR kit$^{TM}$ resulted in 100% specificity at 0.05% limit of detection for all meat species. The detection limit of Cooked Meat ELISA kit$^{(R)}$ on mixed meat samples heat-treated with different temperatures and times, resulted in 0.1% for all heat-treated mixed meat except for chicken at 1.0%. Additionally, ELISA kit on sixty meat products resulted in specificity of 31.8% for ham, 13.6% for sausages, and 12.5% for ground processed products, and relatively low rate for more than 2 types of mixed meats. On the contrary, meat species differentiation using PCR kit showed higher percentage than that using ELISA kit$^{(R)}$: 50.0% for ham, 41.7% for sausages, and 28.6% for ground processed meat. Futhermore, PCR kit on 54 dried beef meats detected pork genes in 13 products whereas ELISA kit showed negative results for all products. Hence, the possibility of cross-contamination during manufacturing process was investigated, and it was found that identical tumblers, straining trays, cutters and dryers were used in both beef and pork jerky production line, suggesting the inclusion of pork genes in beef products due to cross-contamination. In this study, PCR and ELISA test kits were found to be excellent methods for meat species differentiation in raw meat and heat-processed mixed meat. However, lower differentiation rate demonstrated in case of meat processed products raised the possibility of inclusion of other species due to cross-contamination during manufacturing process.

• Restorative Dentistry and Endodontics
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• v.31 no.3
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• pp.192-202
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• 2006

The purpose of this study was to examine the viability of PDL cells in rat molars by using in vivo MTT assay, which was used to compare fast cryopreservation group by liquid nitrogen $(-196^{\circ}C)\;with\;4^{\circ}C$ cold preservation group. A total of 74 Sprague-Dawley white female rats of 4 week-old with a body weight of 100 grams were used. The maxillary left and right, first and second molars were extracted as atraumatically as possible under ketamine anesthesia. Ten teeth of each group were divided as six experimental groups depending upon the preservation. Cryopreservation groups were Group 1 (5% DMSO 6% HES in F medium) Group 2 (10% DMSO in F medium), Group 3 (5% DMSO 6% HES in $Viaspan^(R)$). Group 4 (10% DMSO in $Viaspan^(R)$) which were cryopreserved for 1 week and cold preservation groups were Group 5 (F medium) , Group 6 ($Viaspan^(R)$) at $4^{\circ}C$ for 1 week. Immediate extraction group was used as a control. After preservation and thawing, the in vivo MTT assay was processed. Two way ANOVA and Duncan's Multiple Range Test was performed at the 95 % level of confidence, Another 2 teeth of each group were treated as the same manner and frozen sections $10{\mu}m$ thick for microscopic observation. The value of optical density obtained after in vivo MTT analysis was divided by the value of eosin staining for tissue volume standardization. Group 1, 2 had significantly higher optical density than Group 3 and 4 which had the lowest OD value. Group 6 had higher OD value than in Group 5 (P<0.05). Histological findings of periodontal ligament cell, after being stained with MTT solution were consistent with the in vivo MTT assay results. In this study, the groups which were frozen with DMSO as a cryoprotectant and the groups with F medium showed the best results.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.1-8
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• 2007

This study compared the microshear bond strength (${\mu}SBS$) of light-cured and dual-cured composites to enamel bonded with three self-etching adhesives. Crown segments of extracted human molars were cut mesiodistally, and 1 mm thickness of specimen was made. They were assigned to three groups by used adhesives: Xeno group (Xeno III), Adper group (Adper Prompt L-Pop), and AQ group (AQ Bond). Each adhesive was applied to cut enamel surface as per manufacturer's instruction. Light-cured (Filtek Z 250) or dual-cured composite (Luxacore) was bonded to enamel of each specimen using Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to ${\mu}SBS$ testing with a crosshead speed of 1 mm/minute. The mean ${\mu}SBS$ (n = 20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at the 0.05 probability level, The results of this study were as follows ; 1. The ${\mu}SBS$ of light-cured composite was significantly higher than that of dual-cured composite when same adhesive was applied to enamel. 2. For Z 250, the ${\mu}SBS$ of AQ group ($9.95{\pm}2.51 MPa$) to enamel was significantly higher than that of Adper soup ($6.74{\pm}1.80 MPa$), but not significantly different with Xeno group ($7.73{\pm}2.01 MPa$). 3. For Luxacore, the ${\mu}SBS$ of Xeno group ($5.19{\pm}1.32\;MPa$) to enamel was significantly higher than that of Adper group ($3.41{\pm}1.19\;MPa$), but not significantly different with AQ group ($4.50{\pm}0.96\;MPa$).

• Asia Marketing Journal
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• v.13 no.3
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• pp.25-53
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• 2011

This study probes the effect of loyalty program on the customer retention based on the real transaction data(n=2,892) acquired from education service industry. We try to figure out the outcomes of reward program through more than 1 year-long data gathered and analyzed according to quasi-experimental design(i.e., before and after design). We adopt this kinds of research scheme in regard that previous studies measured the effect of loyalty program by dividing the customers into two group(i.e., members vs. non-members) after the firms or stores had started the program. We believe that it might not avoid the self-selection bias. The research questions of this study could be explained such as: First, most research said that the loyalty programs could increase the customer loyalty and contribute to the sustainable growth of company. But there are little confirmation that this promotional tool could be justified in terms of financial perspective. Thus, we are interested in both the retention rate and financial outcomes caused by the introduction of loyalty programs. Second, reward programs target mainly current customer. Especially CRM(customer relationship management) said that it is more profitable for company to build positive relationship with current customer instead of pursuing new customer. And it claims that reward program is excellent means to achieve this goal. For this purpose, we check in this study whether there is a interaction effect between loyalty program and customer type in retaining customer. Third, it is said that dis-satisfied customers are more likely to leave the company than satisfied customers. While, Bolton, Kannan and Bramlett(2000) claimed that reward program could contribute to minimize the effect of negative service by building emotional link with customer, it is not empirically confirmed. This point of view explained that the loyalty programs might work as exit barrier to current customer. Thus, this study tries to identify whether there is a interaction effect between loyalty program and service experience in keeping customer. To achieve this purpose, this study adopt both Kaplan-Meier survival analysis and Cox proportional hazard model. The research outcomes show that the average retention period is 179 days before introducing loyalty program but it is increased to 227 days after reward is given to the customers. Since this difference is statistically significant, it could be said that H1 is supported. In addition, the contribution margin coming from increased transaction period is bigger than the cost for administering loyalty programs. To address other research questions, we probe the interaction effect between loyalty program and other factors(i.e., customer type and service experience) affecting it. The analysis of Cox proportional hazard model said that the current customer is more likely to engage in building relationship with company compared to new customer. In addition, retention rate of satisfied customer is significantly increased in relation to dis-satisfied customer. Interestingly, the transaction period of dis-satisfied customer is notably increased after introducing loyalty programs. Thus, it could be said that H2, H3, and H4 are also supported. In summary, we found that the loyalty programs have values as a promotional tool in forming positive relationship with customer and building exit barrier.

• Restorative Dentistry and Endodontics
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• v.27 no.2
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• pp.158-174
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• 2002

The aim of this study was to investigate the effect of light irradiation modes on polymerization shrinkage, degree of cure and microleakage of a composite resin. VIP$^{TM}$ (Bisco Dental Products, Schaumburg, IL, USA) and Optilux 501$^{TM}$ (Demetron/Kerr, Danbury, CT, USA) were used for curing Filtek$^{TM}$ Z-250 (3M Dental Products, St. Paul., MN, USA) composite resin using following irradiation modes: VIP$^{TM}$ (Bisco) 200mW/$\textrm{cm}^2$ (V2), 400mW/$\textrm{cm}^2$ (V4), 600mW/$\textrm{cm}^2$ (V6), Pulse-delay (200 mW/$\textrm{cm}^2$ 3 seconds, 5 minutes wait, 600mW/$\textrm{cm}^2$ 30seconds, VPD) and Optilux 501$^{TM}$ (Demetron/Kerr) C-mode (OC), R-mode (OR). Linear polymerization shrinkage of the composite specimens were measured using Linometer (R&B, Daejeon, Korea) for 90 seconds for V2, V4, V6, OC, OR groups and for up to 363 seconds for VPD group (n=10, each). Degree of conversion was measured using FTIR spectrometer (IFS 120 HR, Bruker Karlsruhe, Germany) at the bottom surface of 2 mm thick composite specimens V2, Y4, V6, OC groups were measured separately at five irradiation times (5, 10, 20, 40, 60 seconds) and OR, VPD groups were measured in the above mentioned irradiation modes (n=5 each). Microhardness was measured using Digital microhardness tester (FM7, Future-Tech Co., Tokyo, Japan) at the top and bottom surfaces of 2mm thick composite specimens after exposure to the same irradiation modes as the test of degree of conversion(n=3, each). For the microleakage test, class V cavities were prepared on the distal surface of the ninety extracted human third molars. The cavities were restored with one of the following irradiation modes : V2/60 seconds, V4/40 seconds, V6/30 seconds, VPD , OC and OR. Microleakage was assessed by dye penetration along enamel and dentin margins of cavities. Mean polymerization shrinkage, mean degree of conversion and mean microhardness values for all groups at each time were analyzed using one-way ANOVA and Duncan's multiple range test, and using chi-square test far microleakage values. The results were as follows : . Polymerization shrinkage was increased with higher light intensity in groups using VIP$^{TM}$ (Bisco) : the highest with 600mW/$\textrm{cm}^2$, followed by Pulse-delay, 400mW/$\textrm{cm}^2$ and 200mW/$\textrm{cm}^2$ groups, The degree of polymerization shrinkage was higher with Continuous mode than with Ramp mode in groups using Optilux 501$^{TM}$ (Demetron/Kerr). . Degree of conversion and microhardness values were higher with higher light intensity. The final degree of conversion was in the range of 44.7 to 54.98% and the final microhardness value in the range of 34.10 to 56.30. . Microleakage was greater in dentin margin than in enamel margin. Higher light intensity showed more microleakage in dentin margin in groups using VIP$^{TM}$ (Bisco). The microleakage was the lowest with Continuous mode in enamel margin and with Ramp mode in dentin margin when Optilux 501$^{TM}$ (Demetron/Kerr) was used.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.5
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• pp.353-360
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• 1984

As an effort to expand the utilization of mackerel which has been thought disadvantageous to processors due to the defects in bloody dark color of meat, high content of lipid, and low stability of protein, and to develope a new type of product, so called, preservative fish meat paste, the processing method was studied in which dielectric heating was applied by means of cooking, pasteurization, dehydration, and control of water activity. The principle of this method is based on that dielectric heating can initiate a rapid dispersion or displacement of moisture in the meat tissue so that the level of water acivity can be controlled by dehydration with hot air meanwhile the product is cooked, pasteurized, and texturized. And the product is finally heated with electric heaters and vacuum sealed to stabilize water activity and storage stability. In present paper, a formula for preparing the fish meat-stach paste, the conditions of dielectric heating and dehydration, shape and size of the product, and other parameters were tested to optimize the process operation. A formula of the fish meat-starch paste to provide proper textural properties and water activity was $10\%$ starch, $1.5\%$ salt, $3\%$ soybean, $0.6\%$ MSG, $2\%$ sucrose, and $3\%$ sorbitol against the weight of fish meat. A proper shape and size of the product to avoid foaming and case hardening during heating was sliced disc of 8 cm $diameter{\times}0.8$ cm thickness or $10{\times}10$ cm square plate with 1.0 cm thickness. The disc shape was recommended because it resulted more uniform heating, minimum foaming and case hardening. And it was also advantageous that disc was simply provided when the fish meat disc was stuffed in the same, solidified in boiling water for 2 to 3 minutes, and sliced. Condition of dielectric heating was critical to decide the levels of sterility, water activity, and textural property of the product. The temperature at the center of the meat disc slices was raised up to $95^{\circ}C$ in 1.5 minutes so that continuous exposure to microwave caused expanded tissue and hardening ending up with a higher water content. Heating for 5 to 6 minutes was adequate to yield the final water activity of 0.86 to 0.83(35 to $40\%$ moisture). It is important, however, that heating had to be done periodically, for instance, in the manner of 2.0, 1.5, 1.5, and 1.0 minute to give enough time to displace or evaporate moisture from the meat tissue. The product was dehydrated for 2 to 3 minutes by hot air of $60^{\circ}C$, 3 to 5m/sec and finally exposed to electric heaters for 5 to 6 minutes until the surface was roasted deep brown. These conditions of heating and dehydration resulted in a complete reduction of total plate count from an initial count of $5.3{\times}10^6/g$ to less than $3{\times}10^2/g$. General composition of the product was $40.1\%$ moisture, $20.8\%$ protein, $17.4\%$ lipid, $16.2\%$ carbohydrate, and $5.5\%$ ash. Textural properties revealed folding test AA, hardness 42, cohesiveness 0.53, toughness 4.6, and elasticity 0.8.