• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.34-34
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• 2014

Filamentous fungi of the genus Colletotrichum (teleomorph, Glomerella) are considered major plant pathogens worldwide. Cereals, legumes, vegetables, and fruit trees may be seriously affected by this pathogen (1). Colletotrichum species cause typical disease symptoms known as anthracnoses, characterized by sunken necrotic tissue, where orange conidial masses are produced. Anthracnose appears in both developing and mature plant tissues (2). We investigated disease occurrence in apple orchards from 2013 to 2014 in northern Gyeongbuk province, Korea. Typical anthracnose with advanced symptoms was observed in all apple orchards studied. Of late, static fruit spot symptoms are being observed in apple orchards. A small lesion, which does not expand further and remains static until the harvesting season, is observed at the beginning of fruit growth period. In our study, static symptoms, together with the typical symptoms, were observed on apples. The isolated fungus was tested for pathogenicity on cv. 'Fuji apple' (fully ripe fruits, unripe fruits, and cross-section of fruits) by inoculating the fruits with a conidial suspension ($10^5$ conidia/ml). In apple inoculated with typical anthracnose fungus, the anthracnose symptoms progressed, and dark lesions with salmon-colored masses of conidia were observed on fruit, which were also soft and sunken. However, in apple inoculated with fungi causing static symptoms, the size of the spots did not increase. Interestingly, the shape and size of the conidia and the shape of the appressoria of both types of fungi were found to be similar. The conidia of the two types of fungi were straight and cylindrical, with an obtuse apex. The culture and morphological characteristics of the conidia were similar to those of C. gloeosporioides (5). The conidia of C. gloeosporioides germinate and form appressoria in response to chemical signals such as host surface wax and the fruitripening hormone ethylene (3). In this study, the spores started to germinate 4 h after incubation with an ethephon suspension. Then, the germ tubes began to swell, and subsequently, differentiation into appressoria with dark thick walls was completed by 8 h. In advanced symptoms, fungal spores of virtually all the appressoria formed primary hyphae within 16 h. However, in the static-symptom fungus spores, no primary hyphae formed by 16 h. The two types of isolates exhibited different growth rates on medium containing apple pectin, Na polypectate, or glucose as the sole carbon. Static-symptom fungi had a >10% reduction in growth (apple pectin, 14.9%; Na polypectate, 27.7%; glucose, 10.4%). The fungal isolates were also genetically characterized by sequencing. ITS regions of rDNA, chitin synthase 1 (CHS1), actin (ACT), and ${\beta}$-tubulin (${\beta}t$) were amplified from isolates using primer pairs ITS 1 and ITS 4 (4), CHS-79F and CHS-354R, ACT-512F and ACT-783R, and T1 and ${\beta}t2$ (5), respectively. The resulting sequences showed 100% identity with sequences of C. gloeosporioides at KC493156, and the sequence of the ${\beta}$t gene showed 100% identity with C. gloeosporioides at JX009557.1. Therefore, sequence data from the four loci studied proves that the isolated pathogen is C. gloeosporioides. We also performed random amplified polymorphic DNA-PCR, which showed clearly differentiated subgroups of C. gloeosporioides genotypes. The clustering of these groups was highly related to the symptom types of the individual strains.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.3
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• pp.170-176
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• 2004

This study was carried out to establish a spatial decision support system for evaluating climatic aspects of a given geographic location in complex terrains with respect to the quality apple production. Monthly climate data from S6 synoptic stations across South Korea were collected for 1971-2000. A digital elevation model (DEM) with a 10-m cell spacing was used to spatially interpolate daily maximum and minimum temperatures based on relevant topoclimatological models applied to Jangsoo county in Korea. For daily minimum temperature, a spatial interpolation scheme accommodating the potential influences of cold air accumulation and the temperature inversion was used. For daily maximum temperature estimation, a spatial interpolation model loaded with the overheating index was used. Freezing risk in January was estimated under the recurrence intervals of 30 years. Frost risk at bud-burst and blossom was also estimated. Fruit quality was evaluated for soluble solids, anthocyanin content, Hunter L and A values, and LID ratio, which were expressed as empirical functions of temperature based on long-term field observations. AU themes were prepared as ArcGlS Grids with a 10-m cell spacing. Analysis showed that 11 percent of the whole land area of Jangsoo county might be suitable for quality 'Fuji' apple production. A computer program (MAPLE) was written to help utilize the results in decision-making for site-selection of new orchards in this region.

• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.60-73
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• 1991

The purpose of this study is to evaluate the effects of etching time, environmental temperature and humidity on the adhesion of composite resin to glass-ionomer cement. Two chemical cure composite resins (Clearfil F II and Microrest AP) and two glass-ionomer cements (Fuji ionomer Type I and KET AC-CEM) were used as the experimental materials. The experiment is performed in 3 stages: The first stage is to bond composite resins to glass-ionomer cements, and the surface was not etched, and etched for 20 seconds, 40 seconds, and 60 seconds. Then specimens are stored in distilled water at $37^{\circ}C$ for 24 hours to measure tensile strength. The second stage is to choose the one group that had the highest tensile strength from the first stage and prepare two experimental groups: One group with composite resin bonded to glass-ionomer cement without etching and bonding agent application and the other with composite resin bonded to glass-ionomer cement with etching but without any bonding agent application. The specimens are stored in distilled water at $37^{\circ}C$ for 24 hours and tensile strength is measured. The third stage is to choose group that had the highest tensile strength from the first stage experiment, and bond composite resin to glass-ionomer cement at $24^{\circ}C$ 44%, $30^{\circ}C$ 44%, $30^{\circ}C$ 80%, and $32^{\circ}C$ 92%. The storage time of specimens is to bond immediately after storage, then changed to 30 sec., 60 sec., and 120 sec.. Specimens are stored in distilled water at $37^{\circ}C$ for 24 hours and their tensile strength are measured again. The following results were obtained: 1. As the etching time increases, the tensile bond strength between glass-ionomer cement and composite resin increase, and the tensile bond strength is the highest when acid etched for 60 minutes (P < 0.05). 2. After acid etching for 60 minutes, the tensile strength of the group with bonding agent was stronger than that without bonding agent application (P < 0.05). 3. The tensile strength of Clearfil F II was stronger than that of Microrest AP. 4. It was observed that the tensile bond strength is not affected by different storage time with different temperature and humidity. 5. As the humidity was increased, the tensile bond strength between glass-ionomer cement and composite resin decreased (P < 0.05).

• Restorative Dentistry and Endodontics
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• v.12 no.1
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• pp.119-129
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• 1986

The purpose of this study was to evaluate the marginal leakage of glass ionomer cement with different cavosurface margins. 192 class V cavities were prepared on freshly extracted non-carious teeth and glass ionomer cement were inserted according to the manufacturer's instructions. Cavity preparations for this investigation were performed in four groups. The experimental specimens were made by packing the glass ionomer cement (Fuji Ionomer Type II G-C Co. Japan) into the prepared 192 cavities of four groups with different modes: Group I. - The 48 cavities with $90^{\circ}$ butt-joint cavosurface preparation and restored with glass ionomer cement. Group II. - The 48 cavities with butt-joint preparation modified by $135^{\circ}$ beveling the cavosurface in the dentin and restored with glass ionomer cement. Group III. - The 48 cavities with butt-joint preparation modified by cutting a chamfer in the dentin and restored with glass ionomer cement. Group IV. - The same 48 cavities as group I, and overfilled with glass ionomer cement beyond the cavosurface angle. And four groups above described divided into three subgroups by means of conditioning the cavity walls: Control group. - Glass ionomer cement filled in the prepared 64 cavities after being cleaned with a stream of tap water. Phosphoric acid treatment group. - Glass ionomer cement filled in the prepared 64 cavities after being conditioned with a 50% phosphoric acid. Citric acid treatment group. - Glass ionomer cement filled in the prepared 64 cavities after being conditioned with a 50% citric acid. All 192 specimens were immersed in the 2.0% basic fuchsin solution and subjected to thermal stress at one-minute intervals ($4{\pm}2^{\circ}C$ to $60{\pm}2^{\circ}C$) for 70 minutes before exposure to the dye. The specimens were sectioned ecclesiologically through the center of the restorations for different periods of immersion time, 24 hours, 7 days, 14 days 30 days. The sections were examined under a stereoscopic microscope. The results were as follows: 1. The degree of marginal leakage in group II and III was greater than that in group I and IV. 2. The degree of marginal leakage in phosphoric acid treatment group was similar with that in control group. 3. The degree of marginal leakage in citric acid treatment group was less than that in control group. 4. In all groups, the degree of marginal leakage in phosphoric acid treatment group was greater than that in citric acid treatment group. 5. There is no statistical difference of the degree of marginal leakage according to the immersion time in the dye solution.

• The korean journal of orthodontics
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• v.40 no.3
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• pp.176-183
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• 2010

Objective: This study was performed to evaluate functional changes of occlusion after orthodontic treatment by measuring the occlusal force (OcFr) and occlusal contact area (OcAr), and to compare OcFr and OcAr change according to premolar extractions. Methods: Data were obtained from 74 patients who had finished orthodontic treatment using fixed appliance aged between 18 and 40 years. Subjects were divided into groups who had four premolars extractions or non-extraction (Male extraction-16, Male nonextraction-18, Female extraction-19, Female nonextraction-21). All subjects were asked to bite pressure-sensitive sheets into maximum intercuspation with maximum bite force, and OcFr and OcAr were evaluated by measuring the sheet with a CCD camera. Records were taken right after debonding, 1 week, 1 month, 3 months, 6 months and 1 year after debonding. Results: OcFr and OcAr increased gradually in all groups during the 1 year retention period (p < 0.05). Male groups showed higher OcFr and OcAr than female groups throughout the retention periods (p < 0.05). There were no statistically significant differences of OcFr and OcAr between extraction and non-extraction groups in both males and females (p > 0.05). Conclusions: Occlusion was improved functionally throughout the 1 year retention, and premolar extraction did not induce a decline in the functional aspect of occlusion.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.184-192
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• 2016

This study was carried out to investigate the effect of temperature ($15{\sim}40^{\circ}C$) and the spraying plant growth regulators ($GA_{4+7}+BA$ and prohexadione-calcium) during full blooming on pollen germination and pollen tube growth of the commercial apple cultivars ('Fuji' and 'Tsugaru') and apple cultivars bred in Korea ('Chukwang', 'Gamhong', 'Hongan', 'Honggeum', 'Hongro', 'Hwahong', 'Hongso', 'Summer dream' and 'Sunhong'). Pollen germination and pollen tube growth were increased with increasing temperature from 15 to $25^{\circ}C$, but high temperature over $30^{\circ}C$ inhibit those. The apple cultivar bred in Korea that shows the highest value on pollen germination and pollen tube growth at over $30^{\circ}C$ was 'Sunhong'. The spraying $GA_{4+7}+BA$ increased pollen germination and pollen tube growth than control, but that effect was not show at $40^{\circ}C$. The spraying prohexadione-calcium was not affect to pollen germination and pollen tube growth. In conclusion, if the air temperature during full bloom of apple tree rises about $30{\sim}35^{\circ}C$, the spraying $GA_{4+7}+BA$ after artificial pollination will be good to increasing fruit set.

• Journal of Korean Dental Science
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• v.5 no.1
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• pp.7-12
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• 2012

Purpose: To examine the antibacterial effectiveness of silver nanoparticles (SNP) mixed with commercial orthodontic adhesives. Materials and Methods: SNP was prepared by dissolving silver perchlorate in an organic solvent and reducing it with ultraviolet radiation. SNP was then mixed with four commercial orthodontic adhesives (Light Bond, Blugloo, Transbond XT, and Fuji Ortho LC) (0.05 wt %), which were then formed into disc-shape specimens ($8.0mm{\times}3.0mm$). Commercial orthodontic adhesives containing no SNP were used as the control groups. Specimens of the four experimental and four control groups were incubated with streptococcus mutans and the medium turbidity was assessed at 3, 6, 9, 12, and 24 hours after incubation. The agar diffusion test was also performed to examine the growth inhibition zone of these groups. The data were statistically analyzed using a Wilcoxon rank sum test and t-test with a Bonferroni's correction (P<0.05). Result: The SNP containing groups had a superior antibacterial effect compared to the control groups. In the agar diffusion test, the control groups without SNP did not produce an inhibition zone, whereas the SNP containing groups showed inhibition zone of 10~13 mm. Conclusion: The incorporation of SNP into orthodontic adhesives can inhibit cariogenic bacterial growth.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.1
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• pp.103-111
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• 2006

Statement of problem: The previous unilateral bite force recorder has several limitations for taking long time for measuring and causing discomfort to subjects. Because of these reasons, it could not use widely for epidemiological researches. However, 'Dental Prescale System' which is new equipment for measuring bite force, is more convenient for measuring bite force than previous unilateral recorder. Purpose: The purpose of this study was to compare a new technique(Dental Prescale System) using pressure sensitive foils for recording of maximal jaw closing force with conventional measurement using unilateral bite force recorder Material and method: This studies included 22 healthy dental students in college of dentistry Yonsei university in Rep of Korea. Mean age was 23.9 years. All subjects had continuous dental arches and no significant malocclusion or signs from the teeth and craniomandibular system. The Dental Prescale System (Fuji Film, Tokyo, Japan) consists of a horseshoe-shaped pressure sensitive sheet (50H, R type) and a computerized scanning system.(FPD705) We also used unilateral bite force recorder(Denbotics Co. Seoul, Rep.Korea) for comparing with Dental Prescale. Results and conclusion: The total bite force recorded with Dental Prescale System (1423 N) was systematically higher than that recorded by unilateral bite force recorder. (256 N) However, the maximum bite force values measured in the two ways were significantly correlated (r=0.46, p<0.05). The Dental Prescale bite force calculated for first molar (208 N) was lower than that recorded by unilateral bite force recorder. (256 N) The two values were also very significantly correlated. (r=0.66. p<0.001) There were significantly different in bite force between two measurement methods. The reasons were first, unilateral bite force recorder measured only the bite force of a part of teeth, and Dental Prescale measured the total teeth force. Second, in measurement, a difference in muscle contraction appeared by an extent of mouth-opening. Third, unilateral bite force recorder has the reducing effect of the bite force by protective tape. Fourth, Dental Prescale has limitations during the computer scanning procedure. Therefore, Dental Prescale System is considered to be a very promising alternative to be conventional bite force recording methods.

• Restorative Dentistry and Endodontics
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• v.25 no.1
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• pp.123-132
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• 2000

To overcome problems of conventional glass ionomers, resin components have been added to glass ionomers. On a continuum between glass ionomers and composites are a variety of blends, employing different proportions of acid-base and free radical reactions to bring about cure. Popular groups defined between the ends are resin-modified glass-ionomers(RMGIs), polyacid-modified composite resins(Compomers) and ionomer modified resins. These groups show different clinical properties, and in selecting these materials for a restoration, one should sufficiently understand these different setting properties. In this study, some difference in the setting characteristics of different groups of hybrid ionomers were examined. Two RMGIs (Fuji2 LC,GC / Vitremer, 3M), three Compomers (Dyract AP, Dentsply / F2000, 3M / Elan, Kerr) were involved in this study. The identification of the setting characteristics of different groups was achieved by a two-stage study. First, thermal analysis was performed by a differential scanning calorimeter, and then the hardness of each group at different depth and time were measured by a micro-hardness tester. Thermal analysis was performed to identify the inorganic filler content and to record the heat change during setting process. The setting process was progressed for each material by chemical set mode and light-cured mode. In the hardness test, samples of materials were prepared with a 6mm-diameter metal ring, and the hardness was measured at the top, and 1mm, 2.5mm, 4mm below at just after a 40 second-cure, and after 10 minutes, 24 hours, and 7 days. Statistical analysis was performed by Mann-Whitney rank sum test to assess significant differences between set modes and types of materials, and by ANOVA and T-test to evaluate the statistical meanings of data at different times and depths of each materials. Followings are findings and conclusions derived from this study. Thermal analysis; 1. Compomers show no evidence of chemical setting while RMGIs exhibit heat output during the process of chemical setting. 2. Heat of cure of RMGIs exceed Compomers. 3. The net heat output of RMGIs through light-cured mode is higher than through chemically set mode. Hardness test; 1. Initial hardness of RMGIs immediately after light cure is relatively low, but the hardness increases as time goes by. On the contrary, Comomers do not show evident increase of the hardness following time. 2. Compomers show a marked decrease of setting degree as the depth of the material increases. In RMGIs, the setting degree at different depths does not significantly differ.

• Research in Plant Disease
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• v.14 no.1
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• pp.57-60
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• 2008

A rhizopus soft rot caused by Rhizopus stolonifer occurred sporadically on apple fruits (Malus pumila var. dulcissima Koidz.) at a wholesale market of agricultural products in Jinju, Korea in 2006 and 2007. Infected fruits were rapidly water-soaked, softened and rotted. The symptoms were initiated mainly from wounds or cracks occurred at harvest time. Sporangiophores were $950{\sim}1,900\;{\mu}m$ in length and $12{\sim}22\;{\mu}m$ in width. Sporangia were globose or hemispheric and $82{\sim}185\;{\mu}m$ in size. The color of sporangia was white and cottony at first and gradually turned to brownish black, bearing abundant spores when matured. Columella were hemispheric and $70{\sim}85\;{\mu}m$ in size. Sporangiospores were irregular round or oval, brownish-black streaked and $8{\sim}18{\times}7{\sim}8\;{\mu}m$ in size. Optimum temperature for mycelial growth of the fungus on PDA was $25^{\circ}C$. On the basis of mycological characteristics and pathogenicity to apple the causal fungus was identified as Rhizopus stolonifer (Ehrenb.) Vuill. This is the first report of Rhizopus soft rot by R. stolonifer on Fuji apple in Korea.