• Journal of Appropriate Technology
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• v.5 no.2
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• pp.82-90
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• 2019

The Box-Benhken Design (BBD) model of response surface methodology (RSM) was used to optimize fluoride adsorption conditions in water using a 350℃ thermally treated cow bone. Water temperature, pH, contact time, and initial fluoride concentration were selected as variables to be optimized. A second order reaction equation was obtained from a Box-Behnken Design DoE experimental matrix of 29 runs. R² and p-value of the model were 0.9242 and <0.0001, respectively, indicating that the selected variables had a very substantial effect on the adsorption results. The optimized adsorption capacity of the thermally synthesized bone char was estimated to be 6.46 mgF/g at the water temperature of 39.68℃, pH 6.25, contact time of 88.81 minutes and an initial fluorine concentration of 14.64 mgF/L.

• Journal of Microbiology and Biotechnology
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• v.34 no.5
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• pp.1101-1108
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• 2024

Earlier studies have validated the isolation of extended-spectrum beta-lactamase-producing Salmonella (ESBL-Sal) strains from food. While poultry is recognized as a reservoir for Salmonella contamination, pertinent data regarding ESBL-Sal remains limited. Consequently, the Ministry of Food and Drug Safety has isolated Salmonella spp. from retail meat and evaluated their antibiotic susceptibility and genetic characteristics via whole-genome sequencing. To further elucidate these aspects, this study investigates the prevalence, antibiotic resistance profiles, genomic characteristics, and homology of ESBL-Sal spp. obtained from livestock-derived products in South Korean retail outlets. A total of 653 Salmonella spp. were isolated from 1,876 meat samples, including 509 beef, 503 pork, 555 chicken, and 309 duck samples. The prevalence rates of Salmonella were 0.0%, 1.4%, 17.5%, and 28.2% in the beef, pork, chicken, and duck samples, respectively. ESBL-Sal was exclusively identified in poultry meat, with a prevalence of 1.4% in the chicken samples (8/555) and 0.3% in the duck samples (1/309). All ESBL-Sal strains carried the bla_CTX-M-1 gene and exhibited resistance to ampicillin, ceftiofur, ceftazidime, nalidixic acid, and tetracycline. Eight ESBL-Sal isolates were identified as S. Enteritidis with sequence type (ST) 11. The major plasmid replicons of the Enteritidis-ST11 strains were IncFIB(S) and IncFII(S), carrying antimicrobial resistance genes (β-lactam, tetracycline, and aminoglycoside) and 166 virulence factor genes. The results of this study provide valuable insights for the surveillance and monitoring of ESBL-Sal in South Korean food chain.

• Journal of Oral Medicine and Pain
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• v.30 no.2
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• pp.269-276
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• 2005

This in vitro study evaluated the influence of a flowable composite resin on the tensile bond strength of resin to enamel and dentin treated with Er:YAG laser and diamond bur. 96 Buccal enamel and mid-coronal dentin were laser-irradiated using an Er:YAG laser and treated with diamond bur. Each groups(48) were divided two small groups depends on acid-etching procedure. Light-cure flowable resin(Metafil Flo) and self-cure resin(Clearfil FII New Bond) were used in this study. After surface etching with 37% phosphoric acid and the application of an adhesive system, specimens were prepared with a hybrid composite resin. After 24hours storage in distilled water at 37$^{\circ}C$, all samples were submitted to the tensile bond strength evaluation, using a universal testing machine(Z020, Zwick, Germany). The obtained results were as follows: 1. TBS of acid-etching group were higher than those of non-etching group in both enamel and dentin treated with Er:YAG laser and diamond bur. Laser 'conditioning' was clearly less effective than acid-etching. Moreover, acid etching lased enamel and dentin significantly improved the microTBS of M-Flo. 2. In enamel, TBS of laser-irradiated group were lower than those of bur-prepared group. However, in flowable resin subgroup, there were not differed those between two groups in dentin. 3. In laser-treated group, TBS of flowable composite resin were higher than those of self-curing resin in dentin, however, there was no difference in enamel. From this study, we can conclude that the self- and light-cure composite resin bonded significantly less effective to lased than to bur-cut enamel and dentin, and that acid-etch procedure remains mandatory even after laser ablation. We suggest that Er:YAG laser was useful for preparing dentin cavity with flowable resin filling.

• Restorative Dentistry and Endodontics
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• v.21 no.1
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• pp.174-186
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• 1996

The purpose of this study was to evaluate the adaptability to tooth structure of composite resin and glass ionomer cement according to filling methods. In this study. two class V cavities were prepared on the buccal and lingual surface of each tooth of forty extracted human premolars. and they were randomly assigned into 4 groups with 10 teeth. The cavities of each group were filled with the CLEARFIL FII self curing resin(Control Group), Z-100 light curing resin (Group 1). $Vitremer^{TM}$ light curing glass ionomer cement(Group 2) and Z-100 light curing resin over the $Vitremer^{TM}$ liner(Group 3). The specimens underwent temperature changed from $5^{\circ}C$ to $55^{\circ}C$ five hundred times. After thermocycling. specimens were immersed in 2% methylene blue solution and stored in 100% relative humidity at $37^{\circ}C$ for 24 hours. And then. the specimens sectioned buccolingually. Degree of dye penetration at tooth-restoration interfaces were examined by Tool maker's microscope(x 200) and Image analyzer. The results were as follows : 1. On the occlusal margin. among the experimental groups. the group 2 showed the highest dye penetration($2.40{\pm}0.68$) and the group 3 showed the lowest dye penetration($1.15{\pm}0.37$). There was significant difference among the experimental groups(p<0.001). 2. On the gingival margin, among the experimental groups, the group 1 showed the highest dye penetration($3.30{\pm}0.57$) and the group 2 showed the lowest dye penetration($1.65{\pm}0.49$). There was significant difference among the experimental groups(p>0.001). 3. About total degree of dye penetration, the group 1 showed the highest dye penetration($2.25{\pm}1.17$) and the group 3 showed the lowest dye penetration ($1.43{\pm}0.55$). There was significant difference among the experimental groups(p<0.001). 4. The sum of dye penetration at occlusal margin was less than gingival margin. There was significant difference between occlusal margin and gingival margin (p<0.001). The results showed that differences were more pronounced at the gingival margin. Composite restorations inserted over the glass-ionomer liner demonstrated significantly less leakage than single restoration that used composite resin or glass-ionomer cement.

• The Journal of Advanced Prosthodontics
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• v.5 no.4
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• pp.479-484
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• 2013

PURPOSE. The aim of this study was to evaluate the effects of additional acid etching and curing mechanism (light-curing or self-curing) of a composite resin on the dentin bond strength and compatibility of one-step self-etching adhesives. MATERIALS AND METHODS. Sixteen human permanent molars were randomly divided into eight groups according to the adhesives used (All-Bond Universal: ABU, Clearfil S3 Bond: CS3), additional acid etching (additional acid etching performed: EO, no additional acid etching performed: EX), and composite resins (Filtek Z-250: Z250, Clearfil FII New Bond: CFNB). Group 1: ABU-EO-Z250, Group 2: ABU-EO-CFNB, Group 3: ABU-EX-Z250, Group 4: ABU-EX-CFNB, Group 5: CS3-EO-Z250, Group 6: CS3-EO-CFNB, Group 7: CS3-EX-Z250, Group 8: CS3-EX-CFNB. After bonding procedures, composite resins were built up on dentin surfaces. After 24-hour water storage, the teeth were sectioned to make 10 specimens for each group. The microtensile bond strength test was performed using a microtensile testing machine. The failure mode of the fractured specimens was examined by means of an optical microscope at ${\times}20$ magnification. The data was analyzed using a one-way ANOVA and Scheffe's post-hoc test (${\alpha}$=.05). RESULTS. Additional etching groups showed significantly higher values than the no additional etching group when using All-Bond Universal. The light-cured composite resin groups showed significantly higher values than the self-cured composite resin groups in the Clearfil S3 Bond. CONCLUSION. The additional acid etching is beneficial for the dentin bond strength when using low acidic one-step self-etch adhesives, and low acidic one-step self-etch adhesives are compatible with self-cured composite resin. The acidity of the one-step self-etch adhesives is an influencing factor in terms of the dentin bonding strength and incompatibility with a self-cured composite resin.

• The Journal of the Korean Society for Microbiology
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• v.21 no.4
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• pp.461-471
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• 1986

Shigella strains isloated in the Teagu area during the period from 1973 to 1985 were studied for species distribution, drug resistance, and R plasmids. Approximately 1,200 strains were isolated during this period, and most of them were classified into Shigella flexneri, S. sonnei occupied less than 20%, and S. dysenteriae and S. boydii were very rarely isolated. More than 95% of them were resistant to one or more of these drugs; chloramphenicol (Cm), tetracycline (Tc), streptomycin (Sm), sulfisomidine (Su), ampicillin (Ap), and trimethoprim (Tp). Strains resistant to kanamycin, nalidixic acid (Na), and rifampin (Rf) were rare, and no strain was resistant to cephaloridine, gentamicin, and amikacin. Approximately half of the isolates were resistant to drugs in 1973, but the rate of resistant strains increased to more than 95% from 1977. Strains resistant to the four drugs (Cm, Tc, Sm, and Su) occupied the majority of resistant strains until 1977, but the most prevalent multiplicity of drug resistance increased to six drugs (Cm, Tc, Sm, Su, Ap, and Tp) from 1978 with the marked increase of Ap- and Tp-resistant strains. Approximately 75% of them transferred resistance to Escherichia coli by conjugation, and the resistance was considered to be mediated by R plasmids. Almost all of them transferred the complete patterns of resistance to drugs except Na and Rf. However, among some strains of recent isolates, small numbers of segregants of transferred resistance were observed. The R plasmids in Shigella were mostly classified into Inc FII, and only small numbers into Inc B. Segregants were in most cases unclassified.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.652-663
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• 1996

The purpose of this study was to evaluate the tensile bond strength to tooth structure of composite resin and glass ionomer cement according to filling methods and light curing units. In this study, two class V cavities were prepared on the buccal surface of each tooth of 140 extracted human molars, and they were randomly assigned into 3 experimental groups with 40 teeth and control group with 20 teeth. And then, each experimental groups subdivided into 2 groups(A,B) according to light curing units. The cavities of each group were filled with the CLEARFIL FII self curing resin(Control Group), Z-100 light curing resin(Group 1), Vitremer$^{TM}$ light curing glass ionomer cement(Group 2) and Z-100 light curing resin over the Vitrebond$^{TM}$ liner(Group 3). And subdivided A Group used Argon Laser(SPECTRUM$^{TM}$, U.S.A.), B Group used XL 1,000 curing light (3M, U.S.A.). The specimens underwent temperature changed from $5^{\circ}C$ to $55^{\circ}C$ five hundred times. After thermocycling, specimens were stored in 100% relative humidity at $37^{\circ}C$ for 24 hours. And then, the tensile bond strength of specimens were calculated with Universal Testing Machine(AGS-100A, Japan). The results were as follows : 1. Among the experimental groups, the group 2-B showed the highest tensile bond strength ($18.89{\pm}7.80$) and the group 1-A showed the lowest tensile bond strength ($11.68{\pm}2.28$). There was significant difference between group 2-B and group 1-A(p<0.01). 2. Between the light curing units, the XL 1,000 unit showed higher tensile bond strength ($16.63{\pm}3.20$) than that of the Argon Laser unit ($13.73{\pm}2.30$). There was significant difference between XL 1,000 and Argon Laser(p<0.01). 3. About filling methods and materials, the group 2 showed the highest tensile bond strength ($17.56{\pm}1.89$) and the group 1 showed the lowest tensile bond strength($13.03{\pm}1.90$). There was significant difference between group 2 and group 1,3(p<0.01). In conclusion, the results showed that the glass-ionomer cement that cured by XL 1,000 light curing unit demonstrated significantly higher tensile bond strength than other curing unit and filling methods.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.1
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• pp.15-23
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• 1979

In the first paper of the series the five soil fertility factors were evaluated by means of principal component analysis and varimax method. They are interpreted as representing, 1) skeletal available phosporus status, 2) organnic matter status, 3) salt status 4) base status, and 5) free oxide status. In order to resynthesize such fragmented information for the overall soil fertility evaluation, the method of multiple regression analysis was adopted, using the five factor scores and yield data for Korean paddy soils as independent and dependent variables respectively. As test of linear models with different combinations of independent variables the results of t-test of regression coefficient were revealed that the organic matter status (FII) has no relevance to the yield of paddy and that the free oxides and salt supply has by it self only an insignificant contribution to the yield. The multiple correlation coefficient (R) revealed its multiple regression analysis was as low as 0.43. Introduction of quadratic terms to the linear model bettered the result. Thus multiple correlation coefficient (R) was increased as 0.59. Therefore, a coefficient of determination 0.35 was obtained by a quadratic model with interaction terms among the five fertility constituents. Generally we think that the fertility factor has more contribution to raise the rice yield in paddy and that the failure of yield prediction by fertility factor scores was caused by one of follows; 1) the roughness of the yield inspection, and 2) missextraction of fertility constituents. The second step in this study, assuming that the residuals by multiple regression analysis were due to factors other than soil fertility, we can now proceed to predicting the yield from the field characters with the classified fertility groups by means of Hayashi's theory of quantification No. 1. Such variables as fertility groups (FTYG), water availability (WATER), soil drainage (DRNG), climatic zone (CLIZ), surface soil's stickiness (STCKT), surface soil's dry consistence (DCNST), and surface soil's texture (FTEXT) are taken up as the explanatory variables. The quantification appears reasonable; the well to extremely well in soil drainage, very sticky of surface soil, inefficiency in water availability, coarse texture, and very hard to extremely hard dry consistence in soil are detrimental to the rice yield. The R was as high as 0.90 for the set of variables. But the given explanatory variables in this study were not quite effective in explaining rice yield. The method developed seems to be promising only if properly collected data are available. Conditions that should be satisfied in the yield inspection obtained from common cultivator for the purpose of deriving a prediction equation were put forward.

• Journal of the Korean Arthroscopy Society
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• v.8 no.2
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• pp.75-81
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• 2004

Purpose: Recent development and advances in arthroscopic surgical techniques for Anterior Cruciate Ligament(ACL) reconstruction have led to the ideal location for the etric point from 10 o'clock (in right knee) and 13:30 (in left knee) to 10:30 (in right knee) and 14 o'clock (in left knee) in the frontal plane. This study was performed to compare operative methods and the radiologic results of femoral tunnels made through the tibial tunnel(trans-tibial approach) and the anteromedial portal. Material and Methods: From January 2003 to May 2004, one-hundred reconstructions of anterior cruciate ligament were performed. Group I (femoral tunnel through tibial tunnel) was composed of 50 cases and group ll (femoral tunnel through anteromedial portal) was consisted of 50 cases. The study was performed to compare the radiographic results of femoral tunnels made through the tibial tunnel and the anteromedial portal and operative methods. Results: In operative methods at Group II, femoral tunnel was made more easily at isometric point than Group I, a good visual field was achived because 100$^{\circ}$ flxion of knee, they can be reduced risk of posterior cortical breakage and tunnel-graft mismatching and decreased divergence of femoral interference screw in radiology (P<0.05). The angle between femoral tunnel and longitudinal axis of ACL wae increased at Group ll. Conclusion: Aanteromedial portal technique was more useful in ACL reconstruction for femoral tunnel toward 10 o'clock to10:30(in right) or 1:30 to 2 o'clock(in left).