• The Journal of Korean Academy of Prosthodontics
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• v.41 no.2
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• pp.232-242
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• 2003

Statement of problem : Fiber-reinforced posts have lower modulus of elasticity than titanium post or cast post-core. With this similar elasticity to that of dentin, fiber-reinforced posts have been known to have a tendency to reduce the risk of root fracture. However, there were few studies on the teeth restored with fiber-reinforced posts under the condition of reduced periodontal support. Purpose : The purpose of this study was to evaluate the fracture strength and failure mode of endodontically treated teeth restored with fiber-reinforced posts and titanium posts under the condition of reduced periodontal support. Material and method : Extracted human maxillary incisor roots were divided into 3 groups (group 1 carbon fiber post, group 2 : glass fiber post, and group 3 : titanium alloy post). After coronectomy and endodontic treatment, teeth were restored with each post systems and resin core according to the manufacturer's recommendation. Then, teeth with simulated periodontal ligament were embedded in the acrylic resin blocks at the level of 4 mm below the cemento-enamel junction. Each specimen was exposed to $10^5$ load cycles with average 30 N force in $36.5^{\circ}C$ water using a computer-controlled chewing simulator. Loads were applied at $45^{\circ}$ angle to the long axis of the teeth. After cyclic loading, teeth were subjected a compressive load until failure at a crosshead speed of 0.5 mm/min. Fracture strength (N) and failure mode were examined. The fracture strength was analyzed with one-way ANOVA and the Scheffe adjustment at the 95% significance level. Results and conclusion : The results were as follows. 1. There was no statistically significant difference in the mean fracture strength among the groups (P<.05). 2. Carbon fiber post and glass fiber post group showed less root fracture tendency than control group. 3. All specimens with root fractures showed fracture lines above the level of acrylic resin block, except for only one specimen in group 3.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.237-242
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• 2003

These studies were carried out to establish an effective in vitro embryo transfer methods by analyzing several factors. The base media were TCM-199 solution for in vitro maturation(IVM) of bovine follicular oocytes and Fer-TALP solution for in vitro fertilization(IVF) and CRlaa medium for in vitro culture(IVC). IVC used the fertilized oocytes of 24-hr culture (day 1)after IVF. Embryos were cultured in drop-culture that contained 25 embryos per 10${mu}ell$. Blastocysts cultured for 7 to 9 in vitro were transferred to recipients. The results obtained were as follows: 1. The pregnancy rate according to different region of embryo transfer were 33.8％, 48.1％, 45.0％ and 35.3％ respectively. 2. The pregnancy rate according to the parity of recipient when embryos were transferred to nulliparous (42.9％) was higher than that of 1∼3nd parlous(36.9％), however there were not show significant difference each other. 3. According to the stage of blastocyst, the pregnancy rate when middle blastocysts (MB) (45.5％) were transferred to recipients were higher than that of late blastocysts (LB) (41.0％). 4. When IVF-derived blastocysts cultured for 7 to 9 day were transferred to recipients, the pregnancy rate was higher 7 day of blastocyst than that of 8 day or 9 day of blastocyst. The results of embryo transfer according to the regions, the parity of recipient and the development stage showed that blastocyst formed for 7day transferred to nulliparou were higher pregnancy rate than others.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.295-304
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• 2015

To develop a technique for efficient management of fertility for cucumber in greenhouse, a quick test method to quantify nitrate ($NO_3{^-}$) content in soil solution and leaf petiole juice using a simple instrument that are easy to use for farmers was investigated. N fertilizer (urea) was applied at 0, 50, 100 and 200% levels of the recommended application rate from 30 days after transplanting to harvest by soil fertigation treatments. Stable results were obtained from analysis of nitrate ($NO_3{^-}$) using top $10^{th}$ or $11^{th}$ leaf petioles collected between 10 to 11 am in the morning. Under the semiforcing culture, $NO_3{^-}$ content of leaf petiole juice was highest at 60 days after transplanting (DAT) at all fertigation treatments. Appropriate $NO_3{^-}$content of leaf petiole juice was $2,418{\pm}78{\sim}2,668{\pm}118$ at 45 DAT, $3,032{\pm}90{\sim}3,332{\pm}63$ at 60 DAT, $2,709{\pm}50{\sim}3,158{\pm}155$ at 75 DAT, $2,535{\pm}49{\sim}2,907{\pm}83$ at 90 DAT, and $2,242{\pm}48mg\;L^{-1}$ at 105 DAT. In addition, appropriate $NO_3{^-}$ content of soil solution was $167{\pm}9{\sim}212{\pm}15$ at 45 DAT, $83{\pm}10{\sim}112{\pm}12$ at 60 DAT, $49{\pm}3{\sim}92{\pm}6$ at 75 DAT, $71{\pm}9{\sim}103{\pm}9$ at 90 DAT, and $73{\pm}9mg\;L^{-1}$ at 105 DAT. The cucumber yield at 100% N level of fertigation was $7,770kg\;10a^{-1}$ and no difference in yield was found at 200% N level of fertigation. However, there was 12% decrease in yield at 50% N fertigation and, 17% decrease at 0% N fertigation. Under retarding culture, $NO_3{^-}$ concentration of leaf petiole juice was highest at 55 days after transplanting (DAT) at all fertigation treatments. Appropriate $NO_3{^-}$ content of leaf petiole juice was $2,464{\pm}102{\sim}2,651{\pm}33$ at 45 DAT, $3,025{\pm}71{\sim}3,314{\pm}84$ at 55 DAT and $2,488{\pm}92mg\;L^{-1}$ at 65 DAT, respectively. Appropriate $NO_3{^-}$ content of soil solution was $111{\pm}10{\sim}155{\pm}14$ at 45 DAT, $93{\pm}7{\sim}147{\pm}14$ at 55 DAT, $67{\pm}4mg\;L^{-1}$at 65 DAT, respectively. The cucumber yield at 50% N fertigation was not different from $1,697kg\;10a^{-1}$ of 100% N fertigation level and even with that of the 200% N fertigation. However, there was 21% decrease in yield at 0% N fertigation.

• Korean Journal of Poultry Science
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• v.16 no.2
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• pp.61-71
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• 1989

The purposes of this study were to investigate the genetic variations by backcrossing in commercial chickens. Backcrossing was carried out successively back to parent stock (P.S). Heritabilities and genetic correlation coefficients were estimated to verify the genetic variations. The data obtained from a breeding programme with commercial chickens (I strain) were collected from 1955 to 1987 at Poultry Breeding Farm, Seoul National University. Data came from a total of 1230 female offspring. The results obtained are summarized as follows： 1. The general performance ($Mean\pmStandard deviation$) of each trait was $663.94\pm87.11$g for 8 weeks body weight, $1579.1\pm155.43$g for 20 weeks body weight, $2124.1\pm215.3$g for 40 weeks body weight, $2269.1\pm242.94$g for 60 weeks body weight, $168.43\pm12.94$ day for a9e at sexual maturity (SM), $214.52\pm29.82$ eggs , for total egg number to 60 weeks of age (TEN), $61.45\pm3.48$ g for average weight (AEW), $13180.7\pm1823.22$ g for total egg mass to 60 weeks of age(TEM). All traits, except 10 weeks body weight and AEW, were significant for the degrees of backcross (p＜0.01). 2. The pooled estimates of heritabilities derived from the sire, dam and combined variance components were 0.47~0.52 for age at sexual maturity (SM), 0.07~0.37 for total egg number (TEN), 0.40~0.54 for average egg weight (AEW), 0.18~0.27 for total egg mass (TEM). High heritability estimates were found for SM and AEW. TEN and TEM were estimated to be a lowly heritable traits. Heritability estimates from dam components were higher than those from sire components. These differences might be due to non-additive genetic effect and maternal effect. 3. The estimates of heritabilities and standard errors derived from combined variance components for different degrees of backcross were $0.47\pm0.11$ (BCO), $0.42\pm0.16$ (BC1), $0.51\pm0.29$ (BC2) for TEN, $0.59\pm0.20$ (BCO), $0.43\pm0.17$ (BC1), $0.35\pm0.18$ (BC2) for AEW, $0.28\pm0.12$(BC0), $0.20\pm0.11$(BC1), $0.18\pm0.14$ (BC2) for TEM. Heritability estimates for AEW and TEM were decreased by backcrossing while those for SM and TEN remained constant. Since backcrossing contributes to increased homozygosity, the genetic variation of the traits (AEW and TEM) decreased . 4. The pooled estimates of genetic correlation coefficients were -0.55 between SM and TEN, 0.20 between SM and AEW, -0.29 between TEN and AEW, 0.82 between TEM and TEN, 0.31 between TEM and AEW, -0.42 between TEM and SM. The genetic correlation between TEM and TEN was higher than that between TEM and AEW, and it was suggested that egg mass was strongly affected by egg number. Also, age at sexual maturity(SM) contributes to egg mass(TEM). 5. When backcrossing was carried out successively, the genetic correlation between TEM and TEN increased (BC0：0.79, BC1：0.82, BC2：0.91) but those between TEM and SM decreased (BC0：-0.54, BC1：-0.36, BC2：-0.09) with successive backcrosses.

• Tuberculosis and Respiratory Diseases
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• v.63 no.3
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• pp.242-250
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• 2007

Background: Abnormal angiogenesis can induce hypoxia within a highly proliferating tumor mass, and these hypoxic conditions can in turn create clinical problems, such as resistance to chemotherapy. However, the mechanism by which hypoxia induces these changes has not yet been determined. Therefore, this study was conducted to determine how hypoxia induces changes in cell viability and extracellular microenvironments in an in vitro culture system using non-small cell lung cancer cells. Methods: The non-small cell lung cancer cell line, A549 was cultured in DMEM or RPMI-1640 media that contained fetal bovine serum. A decrease in the oxygen tension of the media that contained the culture was then induced in a hypoxia microchamber using a $CO_2-N_2$ gas mixture. A gas analysis and an MTT assay were then conducted. Results: (1) The decrease in oxygen tension was checked the anaerobic gas mixture for 30 min and then reoxygenation was induced by adding a 5% $CO_2-room$ air gas mixture to the chamber. (2) Purging with the anaerobic gas mixture was found to decrease the further oxygen tension of cell culture media. (3) The low oxygen tension resulted in a low pH, lactic acidosis and a decreased glucose concentration in the media. (4) The decrease in glucose concentration that was observed as a result of hypoxia was markedly different when different types of media were evaluated. (5) The decrease in oxygen tension inhibited proliferation of A549 cells. Conclusion: These data suggests that tumor hypoxia is associated with acidosis and hypoglycemia, which have been implicated in the development of resistance to chemotherapy and radiotherapy.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.4
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• pp.242-248
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• 2007

To find a feasibility of utilization of food waste slurry (FWS) generated during composting, FWS was combined with pig manure slurry (PMS) in various ratios and the change of nutrient contents and offensive odor of the combined slurries before and after fermentation were studied. The initial pH was 7.67 for PMS and 8.45 for FWS. However, during the fermentation, pH increased in the combined slurries with the higher FWS rate among the treatments while decreased in thosewith higher PMS rate. EC of each slurry sample showed that the difference among combined slurry samples has been reduced during fermentation and became stabilized in $21{\sim}23dS\;m^{-1}$ after 180 days. After 180 days fermentation, total nitrogen (T-N) decreased. T-N of mixture with a half and more FWS decreased up to 0.1%, less than the critical level (0.3%). The contents of O.M., T-N, phosphorus, calcium and magnesium decreased with fermentation while those of potash and salinity increased. From initial fermentation until 30 days, a lot of $NH_3$, as an offensive odor, was produced. However, it decreased steadily, except in higher PMS rate. In terms of producing $50{\mu}g\;ml^{-1}$ of $NH_3$, the top layer took 30 days after fertilization with FWS only, 45 days for utilized treatment with F75 (25 % of PMS), 75 days for utilized with F50 (50%) and F25 (75%) and 90 days for PMS only, respectively. $RNH_2$ also had similar trend with $NH_3$ but it was produced continuously as long fermentation proceeded. In terms of $RNH_2$, the decrease in concentration up to $50{\mu}g\;ml^{-1}$ were; 45 days for FWS only(F100), 105 days for F75 utilization, 120 daysfor F50, 165 days for F25, respectively. ethyl mercaptan was produced in PMS until 180 days after fertilization but it was not produced in FWS. Sensory tests as an integrated test of offensive odor were also done. FWS showed lower than 1 after 30 days from initial fermentation, while PMS had still offensive odor even up to 180 days from initial fermentation. It is probably affected by the continuous production of ethyl mercaptan and amines. However, considering in decrease T-N content caused by volatilization while offensive odor intensity according to official standard of fertilizer is lower than 2. Further study on controlling offensive odor needs to be done.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.3
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• pp.235-242
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• 2016

Purpose: This study was to investigate whether the application of different diagnostic criteria affected the frequency of convergence insufficiency (CI). Methods: Eighty one subjects with mean age of 22.54 years (20 to 27 years) were evaluated. Binocularity tests after refraction were performed as the following tests: near point of convergence (NPC) with an accommodative target, phoria using von Graefe method, positive fusional vergence (PFV) with a phoropter. Subjects with CI were diagnosed when exophoria (exo) was greater at near than at distance ($exo{\geq}4{\Delta}$, or >$6{\Delta}$), fusional vergence was $PFV{\leq}11{\Delta}$ for blur, $PFV{\leq}15{\Delta}$ for break, Sheard's or Percival's criterion, and NPC was $NPC{\geq}6cm$, ${\geq}7.5cm$ or >10 cm. Results: Frequency of CI with one diagnostic criterion was ranged from 6.2% to 77.8%, and was overestimated or underestimated according to criteria. It was reduced to the range of 6.2% to 43.2% with diagnostic criteria more than two, especially to the range of 24.7% to 28.4% with lower variability in diagnostic criteria including phoria and Sheard's criterion. There were high relationship between total score of signs and phoria score (r = 0.772, p<0.001), and measured phoria and Sheard's criterion (r = -0.654, p<0.001), but NPC had a high variability and a weak or no significant relationship with other diagnostic criteria. Results suggested $exo{\geq}4{\Delta}$, Sheard's criterion and $NPC{\geq}7.5cm$ for diagnostic criteria of signs and sequence for CI. Conclusions: Frequency of CI is likely to be over- and underestimated with diagnostic criteria. Cutoff values and procedures for phoria, Sheard's criterion and NPC as clinical signs should be suggested definitely in diagnosis associated with CI.

• Food Science and Preservation
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• v.19 no.2
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• pp.235-242
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• 2012

The excellence of pigmented rice with respect to its nutritional composition was proven and the physicochemical properties of five kinds of rice (Jindo black rice, Jindo jeongmi, Boseong black rice, red rice, and green rice) were compared. The crude protein content of black rice harvested in Boseong (10.15%) were higher than that of the other varieties. The crude fat contents of pigmented rice (black, red, and green) were higher than those of polished rice (Jindo-jeongmi and black rice). Boseong black rice had the highest crude fat content. The major free sugar types in the rice varieties were maltose and glucose. The major mineral contents of the unpolished rice (pigmented rice) varieties were as follows: of P, 361.32~570.11 mg%; K, 196.63~210.04 mg%; Mg, 104.11~128.02 mg%; Na, 2.49~8.14 mg%; and Ca, 12.10~16.82 mg%. The major fatty acids in the five kinds of rice were linoleic acid, oleic acid and palmitic acid. The fatty acid contents of the rice varieties did not differ significantly. The black rice (Boseong) had a higher amino acid content than the other varieties. The hunter color values of rice varieties were affected by the colors of tha samples. The L (lightness) value of black rice (Jindo, Boseong) was lower than that of the other samples. The thiamine and riboflavin contents of the red rice (0.48 mg/100 g and 0.14 mg/100 g, respectively) were higher than those of the other varieties (thiamine: 0.36~0.24 mg/100 g and riboflavin: 0.09~0.06 mg/100 g). The hardness of the rice varieties differed significantly (10.75~14.64 kg).

• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.835-852
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• 2000

The ultimate goal of periodontal therapy is the regeneration of periodontal tissue and repair of function. For more than a decade there have been many efforts to develop materials and methods of treatment to promote periodontal wound healing. Recently many efforts are concentrated on the regeneration potential of material used in oriental medicine. In some in vitro and in vivo experiments, there have been many evidences that these materials have an effect on bone regeneration. The purpose of this study was to evaluate histologically and radiologically in Sprague-Dawley rats the effects of safflower seed extracts on the regeneration of the calvarial defects surgically produced. So in this study, the critical size defects were surgically produced in the calvarial bone of 30 Sprague-Dawley rats using the 8mm trephine bur. The safflower seed extract was applied into the defect of each rat in experimental group, whereas nothing was applied into the defect of each rat in control group. Rats were sacrificed at 2, 4, 8 weeks following operation and histomorphometric and radiodensitometric analysis were performed. 1. The newly formed bone length was $102.91{\pm}22.05$, $178.29{\pm}24.40$ at 2 week in the each control, experimental group, $130.95{\pm}39.24$, $242.62{\pm}50.33$ at 4 week and $181.53{\pm}76.35$, $240.36{\pm}22.00$ at 8 week($unit,{\mu}m$). In the 2, 4 week, there were statistically significant difference between control and experimental group(P<0.05). 2. The newly formed bone area was $2962.06{\pm}1284.48$, $10648.35{\pm}1284.48$ at 2 week, $5103.25{\pm}1375.88$, $9706.78{\pm}1481.81$ at 4 week, $8046.02{\pm}818.99$, $12057.06{\pm}740.47$ at 8 week($unit,{\mu}m^2$). In every week, there were statistically significant difference between control and experimental group(P<0.05). 3. The radiopacity was $14.26{\pm}.33$, $25.47{\pm}4.33$ at 2 week, $20.06{\pm}9.07$, $26.61{\pm}2.78$ at 4 week, $22.99{\pm}3.76$, $27.29{\pm}1.54$ at 8 week(unit, %). In the 2 week, there was statistically significant difference between control and experimental group(P<0.05). In conclusion, the results of the present study suggest that safflower seed extract initially has an effect on the newly formed bone area, length and radiopacity when it is applied to the calvarial defect of Sprague - Dawley rat. Then. the material has an effect on newly formed bone area and length.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.235-242
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• 2012

Purpose: The purpose of this study was to compare the fracture behavior of Zironia, glass infiltrated Alumina and PFM full crown system. Materials and methods: Fifteen crowns for each of 3 experimental groups (Zironia, glass infiltrated Alumina and PFM full crown) were made by the conventional method. The crowns mounted on the testing jig were inclined in 30 degrees to the long axis of the tooth and the universal testing machine was used to measure the fracture strength. Results: 1. The mean fracture strengths were $588.3{\pm}49.6MPa$ for zirconia system, $569.1{\pm}61.8MPa$ for PFM system and $551.0{\pm}76.5MPa$ for glass-infiltrated alumina system (P>.05). 2. The mean shear bond strengths were $25.5{\pm}5.6MPa$ for zirconia system, $38.9{\pm}5.0MPa$ for Ni-Cr alloy system and $39.4{\pm}5.1MPa$ for glass-infiltrated alumina system. 3. The chemical bonding was observed at interfaces between PFM or glass-infiltrated alumina and veneering porcelain, however, no chemical bonding was observed at interface between zirconia and veneering porcelain. Conclusion: With the study, the fracture strengths of PFM crown system had a higher fracture strength than conventional zirconia system crown and glass-infiltrated alumina crowns. and than the shear bond strengths glass-infiltrated alumina system had a higher shear bond strength than conventional PFM system and zirconia system.