• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.263-268
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• 2006

Recently, self-etching adhesive system has been introduced to simplify the clinical bonding proce- dures. It is less acidic compared to the phosphoric acid, thus there is doubt whether this system has enough bond strength to enamel. The purpose of this study was to investigate the influence of additional etching on the adhesion of resin composite to enamel. Ninety extracted bovine permanent anterior teeth were used. The labial surfaces of the crown were ground with 600-grit abrasive paper under wet condition. The teeth were randomly divided into six groups of 15 teeth each. Clearfil SE $Bond^{\circledR},\;Adper^{TM}$ Prompt L-Pop and Tyrian $SPE^{TM}$ were used as self-etching primers. Each self-etching primers were applied in both enamel specimens with and without additional etching. For additional etching groups, enamel surface was pretreated with 32% phosphoric acid (UNI-ETCH, Bisco, Inc., Schaumburg, IL. USA). Hybrid resin composite Clearfil AP-X, (Kuraray Co., Ltd., Osaka, Japan) was packed into the mold and light-cured for 40 seconds. Twenty-four hours after storage, the specimens were tested in shear bond strength. The data for each group were subjected to independent t - test at p < 0.01 to make comparisons among the groups. In Clearfil SE $Bond^{\circledR}$, shear bond strength of additional etching group was higher than no additional etching group (p < 0.01). In $Adper^{TM}$ Prompt L-Pop and Tyrian SPE, there were no significant difference between additional etching and non-etching groups (p > 0.01). In conclusion, self-etching adhesive system with weak acid seems to have higher bond strength to enamel with additional etching, while self-etching adhesive system with strong acid seems not.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.308-313
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• 2008

"Jeokjoong", a white winter wheat (Triticum aestivum L.) variety was developed from the cross "Keumkang"/"Tapdong". "Jeokjoong" is an awned, semi-dwarf and soft white winter wheat, similar to "Keumkang" (check variety). The heading and maturing date of "Jeokjoong" were similar to "Keumkang". Culm and spike length of "Jeokjoong" were 78 cm and 7.5 cm, similar to "Keumkang". "Jeokjoong" had lower test weight (800 g) and lower 1,000-grain weight (40.1 g) than "Keumkang" (811 g and 44.0 g, respectively). It had resistance to winter hardiness, wet-soil tolerance and lodging tolerance. "Jeokjoong" showed moderate to scab in test of specific character although "Keumkang" is susceptible to scab. "Jeokjoong" had lower flour yield (69.2%) and ash content (0.36%) than "Keumkang" (72.0% and 0.41%, respectively) and similar flour color to "Keumkang". It showed lower protein content (8.9%) and SDS-sedimentation volume (36.8 ml) and shorter mixograph mixing time (3.5 min) than "Keumkang" (11.0%, 59.7 ml and 4.5 min, respectively). Amylose content and pasting properties of "Jeokjoong" were similar to "Keumkang". "Jeokjoong" had softer and more elastic texture of cooked noodles than "Keumkang". Average yield of "Jeokjoong" in the regional adaptation yield trial was 6.19 MT ha-1 in upland and 5.33 MT/ha in paddy field, which was 19% and 16% higher than those of "Keumkang" (5.21 MT/ha and 4.58 MT/ha, respectively). "Jeokjoong" would be suitable for the area above the daily minimum temperature of $-10^{\circ}C$ in January in Korean peninsula.

• Korean Journal of Agricultural Science
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• v.2 no.2
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• pp.341-356
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• 1975

This study was carried out to evaluate three winter active synthetic varieties in a succeeding generations of improvement and polycross progenies of seven genotypes selected at the cool and wet climate of the Western Oregon, in their performance of the polycross progeny test comparing with a control variety, high yielding 'Fawn', at Daejon, Korea. Various plant and leaf characteristics, especially related to photosynthesis, and forage production during the first summer after the establishment were examined. The important conclusions of this study are summarized as follows: 1. The differences of leaf fresh weight among groups and control exhibit genetic differences. The a verage of leaf fresh weight of polycross progeny group was the heaviest and those of winter active synthetic varieties in the succeeding generations of improvement was heavier than variety 'fawn'. Within polycross progeny group the genotypes exhibit genetic differences for leaf dry weight. 2. The leaf area exhibited genetic differences among groups and control. The average of winter active synthetic varieties in a succeeding generation was larger than variety 'Fawn'. Those oi the polycross progeny group was the largest among groups and control. 3. Differences of specific leaf weight(S. L. W.) among and within varieties, genotypes and control were not significant. Further investigation in this respect is necessary through the study of the diurnal change in S. L. W. 4. Differences of leaf width among groups and control exhibited genetic differences. The average leaf width of winter active varieties was larger than those of 'Fawn' variety. And those of polycross progenies of genotypes was the largest. 5. Plant height of 'fawn' variety in the first measurement was higher than those of winter active tall fescue varieties and genotypes. The deviation in plant height among polyeross progenies of seven genotypes gave a great deviation. The regrowth ability of plant height was not different suggesting that this characteristics was about the same among and within groups and control. 6. Plant width, spreading ability, improved through the succeeding generations of the improvement of the winter active synthetic varieties for the first measurement. Differences of plant width at the second measurement among genotypes within polycross progeny group were big enough to show the genetic difference. 7. Tiller number of the winter active synthetic varieties and the average of genotypes in polycross progeny was more than those of the control 'Fawn' in the first measurement. On the second measurement, the differences of tiller number appeared among three synthetic varieties indicating improvement, and there were genetic differences among seven genotypes in polycross progeny test. 8. Forage yield on the first cutting showed a considerble improvement of forage yield in the more advanced generation of synthetic varieties and genetic differences among seven genotypes in the polycross progeny test. The average of polycross progeny group was higher than those of the control or three winter active varieties. It was suggested that we could make a further improvement for the forage yield. 9. The regrowth ability of these winter active varieties and genotypes was about the same capacity at least on the measurement of the regrowth in forage yield and plant height during summer. 10. On the whole, the averages of the polycross progeny group was in the highest value and those of synthetic varieties were higher than the control variety, 'Fawn', for the most characteristics except S. L. W. and the plant height on the first measurement even though the differences were not always significant. And there were genetic differences among seven gentypes in their performance of the polycross progeny. 11. Although it was not always sgnificant, the most advanced winter active variety, '1002', had in the highest value for all plant characteristics and forage yield measurements than the other two varieties, '1001'. 12. The results of the association study among various characteristics were quite agreeable and would be useful in the selection of desirable genotypes for the development of a better variety.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.4
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• pp.276-283
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• 2013

Purpose: The purpose of this study was to investigate the fit and screw joint stability between Ready-made abutment and CAD-CAM custom-made abutment. Materials and methods: Osstem implant system was used. Ready-made abutment (Transfer abutment, Osstem Implant Co. Ltd, Busan, Korea), CAD-CAM custom-made abutment (CustomFit abutment, Osstem Implant Co. Ltd, Busan, Korea) and domestically manufactured CAD-CAM custom-made abutment (Myplant, Raphabio Co., Seoul, Korea) were fabricated five each and screws were provided by each company. Fixture and abutments were tightening with 30Ncm according to the manufacturer's instruction and then preloding reverse torque values were measured 3 times repeatedly. Kruskal-Wallis test was used for statistical analysis of the preloading reverse torque values (${\alpha}=.05$). After specimens were embedded into epoxy resin, wet cutting and polishing was performed and FE-SEM imaging was performed, on the contact interface. Results: The pre-loading reverse torque values were $26.0{\pm}0.30Ncm$ (ready-made abutment; Transfer abutment) and $26.3{\pm}0.32Ncm$ (CAD-CAM custom-made abutment; CustomFit abutment) and $24.7{\pm}0.67Ncm$ (CAD-CAM custom-made abutment; Myplant). The domestically manufactured CAD-CAM custom-made abutment (Myplant abutment) presented lower pre-loading reverse torque value with statistically significant difference than that of the ready-made abutment (Transfer abutment) and CAD-CAM custom-made abutment (CustomFit abutment) manufactured from the same company (P=.027) and showed marginal gap in the fixture-abutment interface. Conclusion: Within the limitation of the present in-vitro study, in domestically manufactured CAD-CAM custom-made abutment (Myplant abutment) showed lower screw joint stability and fitness between fixture and abutment.

• Development and Reproduction
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• v.10 no.1
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• pp.55-61
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• 2006

There is growing concern that dietary soy intake is associated with protection of breast cancer. However, questions persist on the potential adverse effects of the main soy constituent genistein(GS) on female reproductive physiology. In this study, we examined whether prepubertal exposure to GS affected on the onset of puberty and the associated reproductive parameters such as hormone receptor expressions in female rats. GS(100mg/kg/day) was administrated daily from postnatal day 25(PND 25) to the day when the first vaginal opening(VO) was observed, and the animals were sacrificed on the day after VO occurred. Gross anatomy and tissue weight were compared to test the GS's effect on the cell proliferation. Furthermore, histological studies were performed to assess the structural alterations in tissues. Specific radioimmunoassay(RIA) were carried out to measure serum LH levels. To determine the transcriptional changes in progesterone receptors(PR), total RNAs were extracted from ovary and uterus and were applied to semi-quantitative reverse transcription polymerase chain reaction(RT-PCR). As a results, advanced VO was shown in the GS group(PND $31.2{\pm}0.6$) compared to the vehicle group (PND $35.3{\pm}0.7$). GS treatment significantly increased wet weight of ovaries and uteri compared to the vehicle group. Increased serum LH levels were also shown in the GS group. Graafian follicles and corpora lutea(CL) were observed only in the ovaries from GS treated animals. Similarly, hypertrophy of luminal and glandular uterine epithelium were found only in the GS group. Collectively, these effects were probably due to the estrogenic effects of GS. In the semi-quantitative RT-PCR studies, the transcriptional activities of PR in both ovary and uterus from GS-treated group were significantly higher than those from the vehicle group. The present studies demonstrated that acute exposure to GS, at levels comparable to the ranges of human exposure, during the critical period of prepubertal stage activates the reproductive system resulting precocious puberty in immature female rats.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.559-571
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• 2017

This study was conducted to determine the adhesive performances of plywoods affected by layering direction and the amounts of thermoplastic films. The face and back layers of veneer were hardwood species (Mixed light hardwood) and core layer veneer was radiata pine (Pinus radiata D. Don). Thermoplastic film used as adhesive were polypropylene (PP) film and polyethylene (PE) film. Thermal analysis and tensile strength were investigated on each films. As a result, the melting temperature of PP and PE films were $163.4^{\circ}C$ and $109.7^{\circ}C$, respectively, and the crystallization temperature were $98.9^{\circ}C$ and $93.6^{\circ}C$, respectively. Tensile strength and elongation of each films appeared higher on the width direction than length direction. Considering the characteristics of the thermoplastic films, the test for the amount of film used was carried out by layering film to the target thickness on veneer. The effecting of layering direction of film on plywood manufacturing was conducted by laminating in the length and width directions of the film according to the grain direction of veneer. Tensile-shear strength of plywood in wet condition was satisfied with the quality standard (0.7 MPa) of KS F 3101 when the film was used over 0.05 mm of PP film and over 0.10 mm of PE film. Tensile-shear strength of plywood after cyclic boiling exceeded the KS standard when PP film was used 0.20 mm thickness. Furthermore, higher bonding strength was observed on a plywood made with width direction of film according to grain direction of veneer than that of length direction of film. Based on microscopic analysis of the surface and bonding line of plywood, interlocking between veneers by penetration of a thermoplastic film into inner and cracks were observed.

• Journal of the Korean Society of Costume
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• v.36
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• pp.219-238
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• 1998

For the purpose of this Study, the situation of Korean costume properties in the collection of overseas museums was investigated through correspondence, interviews with their curators and persons in charge and survey. As results were made about the situation of museum science (conservation) and practical utilization of costume properties. So, the study result were drawn as follows : Krean costume properties unexplaind of 'Korean cultural Properties' could be found in the Metropolitan Museum of Art of New York(135 pieces), the Brooklyn Museum of New York(20 pieces), the Newark Museum of New Jersey(15 pieces), and the Victoria Albert Museum of London(100 pieces). Korean costume properties in the collection of over-seas museums mostly fall under the rang of period between the 19th century and the early 20th century and are classified into everyday clothing, wedding costume and armors for the most part. In 1900s, museum in several countries began to collected Korean cultural properties through foreign missionaries or diplomats as well as merchants or travellers in who bought Korean objects. Recently, scholars, traditional Korean costume designerss and diplomatic and consular offices in overseas have donated our Korean costume to many foreign museums. Korean costume properties were largely on display in the dependent display of folklore museums or in a part of exhibition gallery for Asian culture and there were the separate exhibition rooms in museums in the United Kingdom, Germany, Denmark, Austria, Japan and the United States America. But the size and level of display room for Korean cultural properties is one third as large as that for chinese or Japanese cultual properties. It was found in this study that the traditional Korean costume in the collection of overseas museums was largely recorded only as general items rather than given their proper names. The typical example of misnaming included bridal's Kimono for Wonsam(원삼) in the Metropolitan Museum of Art, Yeonroksaek-bumunsajeokori for Dangeui(당의) and Jissan-gryongwonmunsadurumagi for Kongdali(동달이) in the Okura collection of the Tokyo National Museum, and so on. And the Victoria Albert Museum modified the way of wearing Daenim(대님) and the National Museum of Ethnology in Osaka seemed to misplace the ornament of Keanggi(댕기) on Mubok(무복) and Josunjuk(조선족: Chinese-Korean) Museum also misplace hansam(한삼). On the one hand, the Newark museum of New Jersey mixed Chinese armor with the Korean one and the Photohraph of King Kojong(고종) with Chinese one. It is corrected to publish and disseminate the book concering Korean costume in order to inform foreign museums of thed proper names and wearing method of our traditional costumed. The repair of costume before cleaning in the process of conservation treatment can prevent damage likely to occur as the properties of fiber itself are weakened in liquid. It is recommended that western 8-figure stitch and tacking stitch is added to Korean traditional stitching method. Museums in the U.S.A and the U.K are concerned about the aftermath of cleaning it-self, specially conservation treatment may exert on remains and predominantly use the vacuuming method to remove dust or bits of straw before the exhibition beings. But in case of Korea, the dry cleaning and wet cleaning method are used according to the nature and state of a sample costume. This comprehensive cleaning method is gradually developing scientifically but it is expected that those concerned will make a chemical analysis of the solvent to be used and also the more precise test of costume properties will be conducted before cleaning them. A partial study was made here because the scope of study was too broad and vast. It is expected that more studies will be conducted concerning our costume culture under the long-term plan and active support at the government level.

• Development and Reproduction
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• v.10 no.2
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• pp.147-154
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• 2006

Phthalates such as di(2-ethyl hexyl)phthalate(DEHP) are industrial chemicals with wide-ranging human exposures because of their use in plastics and other common consumer products. Consequently, their adverse effects as endocrine disruptor in the reproductive physiology of both laboratory rodents and human have been studied extensively. The present study was undertaken to examine whether prepubertal exposure to DEHP affects on the onset of puberty and the associated reproductive parameters such as hormone receptor expressions in female rats. DEHP(100mg/kg/day) was administered daily from postnatal day 25(PND 25) through the day when the first vaginal opening(VO) was observed, and the animals were sacrificed on the next day. Gross anatomy and weight of reproductive tissues were compared to test the DEHP's effects on the cell proliferation. Furthermore, histological studies were performed to assess the structural alterations in the tissues. Specific radioimmunoassay was carried out to measure serum LH levels. To determine the transcriptional changes in progesterone receptor(PR), total RNAs were extracted and applied to the semi-quantitative reverse transcription polymerase chain reaction(RT-PCR). As a result, delayed VO was shown in the DEHP group(PND $37.3{\pm}0.7$) compared to the control group(PND $35.3{\pm}0.7$; p<0.05). DEHP treatment significantly decreased the wet weight of ovaries and uteri compared to the control group(p<0.05). Interestingly, elevation of serum LH levels was shown in the DEHP group(p<0.05). Graafian follicles and corpora lutea were observed only in the ovaries from the control animals. Numerous primary, secondary follicles and small atretic follicles were observed in the ovaries from DEHP-treated animals. Similarly, hypotrophy of luminal and glandular uterine epithelium was found in the DEHP-treated group. These effects were probably due to the inhibitory effects of DEHP on the synthesis and secretion of estrogen from granulosa cells. In the semiquantitative RT-PCR studies, the transcriptional activities of PR in both ovary(p<0.05) and uterus(p<0.01) from DEHP-treated animals were significantly lower than those from the control animals. The present studies demonstrated that the acute exposure to DEHP during the critical period of prepubertal stage could inactivate the reproductive system resulting delayed puberty in female rats.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.353-360
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• 2016

Effect of heavy metals(Cd, Cu, Zn) on the survival and population growth rates(PGR) of marine rotifer, Brachionus plicatilis were examined. B. plicatilis were exposed to Cd, Cu and Zn for 24 h to determine their survival and 72 h to determine their PGR. Survival rates in the control groups were greater than 90%. They were decreased with increasing concentrations of Cd, Cu and Zn. Survival rates were reduced in a concentration-dependent manner. Significant reduction in survival rates after exposure to Cd, Cu and Zn at concentration greater than 40.00, 0.13 and $10.00mg\;L^{-1}$, respectively. PGR in the control groups were greater than 0.50. They were decreased with increasing concentrations of heavy metals. PGR were reduced in a concentration-dependent manner. Significant reduction in PGR after exposure to Cd, Cu and Zn occurred at concentration greater than 12.5, 0.06 and $1.00mg\;L^{-1}$, respectively. The order of heavy metal toxicity based on PGR was Cu>Zn>Cd, with $EC_{50}$ (50% Effective Concentration) values of 0.12, 6.15 and $21.41mg\;L^{-1}$, respectively. The lowest-observed-effective-concentrations(LOEC) of PGR after exposure to Cd, Cu and Zn were 12.50, 0.06 and $1.00mg\;L^{-1}$, respectively. The No-observed-effective-concentrations(NOEC) of PGR after exposure to Cd, Cu and Zn were 6.25, 0.03 and $0.01mg\;L^{-1}$, respectively, in marine ecosystems have toxic effects on PGR of B. plicatilis. These results suggest that the PGR of B. plicatilis are useful tool to assess the effect of heavy metals on primary consumers in marine natural ecosystems.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.5
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• pp.643-650
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• 2007

It has been known that Samultang has positive effects on blood circulation and erythrocyte formation. Samultang was composed of four ingredients, Angelica gigas Nikai, Rahmanniae Radix Preparata, Paeonia lactiflora Pallas, and Cnidium officinale Makino. Five types of bread were prepared by replacing water with Samultang for dough proportionally. Control (C) did not have Samultang and the other four experimental bread contained Samultang: S-I (25% of water was substituted by Samultang), S-II (50% substituted), S-III (75% substituted), and S-IV (100% substituted). Moisture, protein, and ash contents of Samultang were $97.34{\pm}0.11%,\;0.42{\pm}0.04%,\;and\;1.40{\pm}0.16%$, respectively. Replacing water with Samultang decreased pH and increased significantly wet gluten content of the dough. Substitution of Samultang for water incremented redness and yellowness of the dough and bread and increased hardness. It also raised the contents of ash and protein. Although it was not significant, in addition, moisture loss of the bread during storage seemed to be lessened by replacing water with Samultang. However, total volume and specific loaf volume of the bread, baking loss rate, and the other textural characteristics except hardness were not affected by substituting water with Samultang. Due to the above results, sensory evaluation of volume and gumminess of the bread were improved significantly by substituting Samultang for water. The bread replaced 25% of the water with Samultang was ranked as the best by the test of sensory evaluation. These results imply that adding Samultang instead of water to dough for bread might bring positive effects on quality characteristics of the bread without any adverse influences. Therefore, it might be worth developing functional bread using Samultang.