• Journal of the korean academy of Pediatric Dentistry
• /
• v.23 no.3
• /
• pp.640-658
• /
• 1996

The purpose of this study was to examine the mechanism of improving acid resistance of Nd-YAG laser irradiated tooth enamel and determine the most effective energy density for improving acid resistance. The bovine tooth enamel were lased with a pulsed Nd-YAG laser. The energy densities of exposed laser beam were varied from 10 to $70\;J/cm^2$. To investigate the degree of improving acid resistance by irradiation, all the samples were submerged to demineralize in 0.5 N $HClO_4$ solution for 1 minute. After 1 minute, 0.05 % $LaCl_3$ was added to the solution for interrupting the demineralization reaction. The amounts of dissolved calcium and phosphate in the solution were measured by using an atomic absorption spectrophotometer and the UV/VIS spectrophotometer, respectively. To examine the mechanism of improving acid resistance, X-ray diffraction analysis, infrared spectroscopy, and scanning electron microscopy were taken. The X-ray diffraction pattern of the samples were obtained in the $10^{\circ}{\sim}80^{\circ}2{\theta}$ range with $Cu-K{\alpha}$ radiation using M18HF(Mac Science Co.) with X-ray diffractometer operating at 40 KV and 300 mA. The infra-red spectra of the ground samples in 300 mg KBr pellets 10 mm diameter were obtained in the $4000cm^{-1}\;to\;400cm^{-1}$ range using JASCO 300E spectrophotometer. The scanning electron microscopy was carried out using JSM6400(JEOL Co.) with $500{\sim}2000$ times magnification. The results were as follow 1. The concentration of calcium dissolved from laser irradiated enamel with $50J/cm^2$ was significantly lesser than that of unlased control group (p<0.05) 2. From the result of the X-ray diffraction analysis, $\beta$-TCP, which increases acid solubility, was identified in lased enamel but the diffraction peaks of (002) and (004) became sharp with increasing energy density of laser irradiation. This means that the crystals in lased samples were grown through the c-axis and subsequently, the acid solubility of enamel decreased. 3. The a-axis parameter was slightly increased by laser irradiation, whereas the c-axis parameter was almost constant except for a little decrease at $50J/cm^2$. 4. In the infra-red spectra of lased enamels, phosphate bands ($600{\sim}500cm^{-1}$), B-carbonate bands (870, $1415{\sim}1455cm^{-1}$), and A-carbonate band ($1545cm^{-1}$) were observed. The amounts of phosphate bands and the B-carbonate bands were reduced, on the other hand, the amount of the A-carbonate band was increased by increase the energy density. 5. The SEM experiments reveal that the surface melting and recrystallization were appeared at $30J/cm^2$ and the cracks were observed at $70J/cm^2$. From above results, It may be suggested that the most effective energy density for improving acid resistance of tooth enamel with the irradiation of Nd-YAG laser was $50J/cm^2$. The mechanism of improving acid resistance were reduction of permeability due to surface melting and recrystallization of lased enamel and reduction of acid solubility of enamel due to decrease of carbonate content and growth of crystal.

• Environmental and Resource Economics Review
• /
• v.14 no.1
• /
• pp.167-199
• /
• 2005

The following policy implications can be drawn from this study: 1) The Air Pollution Emission Amount Report published by the Ministry of Environment since 1991 classifies industries into 4 sectors, i. e., heating, manufacturing, transportation and power generation. Currently, the usability of report is very low and extra efforts should be given to refine the current statistics and to improve the industrial classification. 2) Big pollution industries are as follows - s7, s17 and s20. The current air pollution control policy for these sectors compared to other sectors are found to be inefficient. This finding should be noted in the implementation of future air pollution policy. 3) s10 and s17 are found to be a big polluting industrial sector and its pollution reduction effect is also significant. 4) The effect of emission coefficient (${\Delta}f$) has the biggest impact on the reduction of emission amount change and the effect of economic growth coefficient (${\Delta}y$) has the biggest impact on the increase of emission volume. The effect of production technology factor (${\Delta}D$) and the effect of the change of the final demand structure (${\Delta}u$) are insignificant in terms of the change of emission volume. 5) Further studies on emission estimation techniques on each industry sector and the economic analysis are required to promote effective enforcement of the total volume control system of air pollutants, the differential management of pollution causing industrial sectors and the integration of environment and economy. 6) Korea's economic growth in 1990 is not pollution-driven in terms of the Barry Commoner's hypothesis, even though the overall industrial structure and the demand structure are not environmentally friendly. It indicates that environmental policies for the improvement of air quality depend mainly on the government initiatives and systematic national level consideration of industrial structures and the development of green technologies are not fully incorporated.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.28 no.1
• /
• pp.41-57
• /
• 1983

The effect of temperature 'during the reduction division stage on the Indica-Japonica rice varieties were studied in artificial temperature-controlled cabinets (Bioclimatic Laboratory). Varieties used were indica-japonica crosses (Suweon 264, Suweon 258, Milyang 29), indica (IR36, Lengkwang) and japonica rice (Jin-heung). The results obtained from this study are summarized as follows. The most sensitive stage to low temperature, the tetrad stage, was observed in each variety with the following auricle distance: Jinheung, -12cm; IR36, -3cm; Suweon264, -9cm; Suweon258, -3cm; Milyang29, -6cm and Lengkwang, +1cm. The tetrad stage occured when the palea elongation was about 50 to 60% of the final palea length at flowering stage in all varieties. The percentage of degenerated spikelets at tetrad as influenced by low-temperature treatment was very low in Jinheung and Lengkwang, but very high in IR36. In indica-japonica crosses only the 7-days treatments had a very high percentage. Between the 4-day and 7-day treatments as well as among all varieties, clear differences were observed in the low temperature induced sterility of 'special spikelets' (upper position grains at tetrad). In the 7-day treatments except in Lengkwang, all varieties showed very high sterility. It appears that the treatments is over the critical limit for treatment. However in the 4-day treatments, the intervarietal differences in sterility were very clear. In Jinheung, sterility was 46.8%; IR36, 67.6%; Suweon264, 60.9%, Milyang29, 62.2%; Lengkwang, 27.8%. A close relationship was observed between fertility and auricle distance. The lowest fertility of special spikelets was at the tetrad stage and the first contraction phase. Before and after the stage there was an increase in fertility. The palea length elongated nearly in a straight line from the spikelet formation stage to flowering. And there was a high correlation between palea length and auricle distance. distance.

• Journal of Veterinary Clinics
• /
• v.26 no.2
• /
• pp.138-143
• /
• 2009

Ischemia/reperfusion injury(I/RI) is the major cause of acute renal failure and delayed graft function(DGF) unavoidable in renal transplantation. Enormous studies on ischemia damage playing a role in activating graft rejection factors, such as T cells or macrophages, are being reported. Present study was performed to determine whether ischemia time would play an important role in activating rejection-related factors or not in rat models of I/RI. Male Sprague-Dawley rats were submitted to 30, 45, and 60 minutes of warm renal ischemia with nephrectomy or control animals underwent sham operation(unilateral nephrectomy). Renal function and survival rates were evaluated on day 0, 1, 2, 3, 5 and 7. Immunofluorescence staining of dendritic cells(DCs), natural killer(NK) cells, macrophages, B cells, CD4+ and CD8+ T cells were measured on day 1 and 7 after renal I/RI. Survival rates dropped below 50% after day 3 in 45 minutes ischemia. Histologic analysis of ischemic kidneys revealed a significant loss of tubular architecture and infiltration of inflammatory cells. DCs, NK cells, macrophages, CD4+ and CD8+ T cells were infiltrated from a day after I/RI depending on ischemia time. Antigen presenting cells(DCs, NK cells or macrophages) and even T cells were infiltrated 24 hours post-I/RI, which is at the time of acute tubular necrosis. During the regeneration phase, not only these cells increased but B cells also appeared in more than 45 minutes ischemia. The numbers of the innate and the adaptive immune cells increased depending on ischemia as well as reperfusion time. These changes of infiltrating cells resulting from each I/RI model show that ischemic time plays a role in activating rejection related immune factors and have consequences on progression of renal disease in transplanted and native kidneys.

• Journal of Plant Biotechnology
• /
• v.30 no.1
• /
• pp.13-18
• /
• 2003

This study was carried out to investigate the expression patterns of foreign gene that controlled by tuber-specific patatin promoter in transgenic potatoes. Potato leaf disc cultured in vitro were transformed by the Agrobacterium strain LBA4404 containing pBl121 or pATGUS from potato cv. Desiree. In order to select the transgenic lines, gene-specific primers deduced from the NPTII were synthesized and used for polymerase chain reaction. The down part of the putative transgenic potatoes was transplanted weekly onto sucrose-enriched medium to accelerate the microtuber formation. RNA gel blot analysis was performed on the total RNAs obtained from tuber that had been harvested at a week interval. Also, histochemical assay was observed in the explants transformed with either pBI121 or pATGUS. Results showed that the transgenic plant containing pATGUS expressed GUS transcripts mainly at the tuber, not in stem, with the highest expression level in 5 weeks-grown microtubers. In contrast to pATGUS plants, the transformed plants with pBI121 showed an equal expression pattern throughout the whole developing stages. Consistent with RNA gel blot analysis, histochemical GUS staining and enzyme activity exhibited pATGUS transcripts were at the highest level in 5 weeks cultures. From these results, we suggest that the best stage to analyze the foreign gene introduced by patatin promoter into potato plants is at 5 weeks cultures after tuber formation.

• Childhood Kidney Diseases
• /
• v.1 no.2
• /
• pp.170-175
• /
• 1997

Purpose : Hemolytic uremic syndrome(HUS), known as a most common cause of childhood renal failure in western countries, has been a relatively rare disease in Korea. Although the reported cases were not related to any specific cause in Korea, there was an outbreak of HUS with bloody diarrhea in Japan last year. We report here that we experienced the several typical HUS last year. Patients : From Jan.1996 to Dec. 1996, five patients were diagnosed as HUS at Samsung Seoul Medical Center, Dept. Pediatrics. Results : 1) The age of onset was below 3 years in 3 cases and above 9 years in 2 cases. 2) All the cases happened between summer and autumn. Three patients had domestic travel and 4 patients drank well or spring water before the symptoms. 3) The clinical manifestation was generalized edema, oliguria, anuria and hematuria. The bloody diarrhea were present in 5 cases and 1 patient had operation with the impression of appendicitis. 4) There was no bacteria which was isolated from the blood or stool samples. 5) Renal biopsies were performed in 2 cases, because of protracted clinical course. One showed microthrombotic angiopathy and the other cortical necrosis with necrotizing glomeruli. 6) Complete recovery was the outcome in 4 cases and one case progressed to chronic renal failure. Conclusion : In conclusion, typical HUS associated with bloody diarrhea, epidemic and good prognosis can be found in Korea and careful surveillance of the pre-clinical cases will be necessary.

• Korean Journal of Weed Science
• /
• v.30 no.3
• /
• pp.282-290
• /
• 2010

The objective of this research was to discover the best method for weed management in environment-friendly rice paddy fields through the study on the effect of weed control and injury levels of rice plants as affected by size, input time, and input amount of golden apple snail (GAS). The efficacy of weed control as affected by GAS when applied at 5, 10, and 15 days after transplanting (DAT) was 98, 89, and 58%, respectively. The efficacy of weed control had declined as late the input time of GAS. On the other hand, the efficacy of weed control as affected by rice bran followed by GAS treatment was higher than by GAS treatment alone. Weed species such as Persicaria hydropiper, Echinochloa crus-galli, Scirpus juncoides, and Monochoria vaginalis were not completely controlled by GAS when applied late. Input amount and time of adult GAS (70 days after hatching) for effective weed control were 3 kg $10a^{-1}$ at 5 DAT, 6-7 kg $10a^{-1}$ at 10 DAT, and 7 kg $10a^{-1}$ at 15 DAT. Input time and amount of young GAS (35 days after hatching) for effective weed control were 0 day after harrow (DAH) and 1 kg $10a^{-1}$, respectively. The young GAS when applied 0 DAH at 1 kg $10a^{-1}$ provided 100% control of P. hydropiper, E. crus-galli, S. juncoides, M. vaginalis, Ludwigia prostrata, Eleocharis kuroguwai, Sagittaria trifolia and Cyperus difformis. The rice foliar injury caused by adult (3 kg $10a^{-1}$) and young (1 kg $10a^{-1}$) GAS were 5-7% and 1% respectively. There was no significant difference in rice injury by size and input amount of GAS on plant height and number of tiller. These data indicate that the young GAS when applied 1 kg $10a^{-1}$ at 0 day after harrow was the best method for weed management in environment-friendly rice paddy fields.

• Korean Journal of Weed Science
• /
• v.30 no.3
• /
• pp.272-281
• /
• 2010

The objective of this research was to find out the weed management techniques in environment-friendly rice paddy fields through the study on herbicidal effects and problems of various organic materials. This experiment was conducted under different conditions of weed species and weed densities in environment-friendly rice paddy fields. There was no difference in weedy efficacy on golden apple snail (GAS), paper mulching (PM), and machine weeding (MW) between low and high weed densities. However, the effect of weed control in rice bran (RB) and effective microorganism (EM) + molasses was higher in high weed density than in low weed density. In general, the effect of weed control as affected by various organic materials was in the order of GAS (97-100%) > PM (93-98%) > RB (15-80%) > EM (7-31%). GAS provided excellent control of all weed species tested except for Persicaria hydropiper. PM gave acceptable control of the weed species except for Echinochloa crus-galli, Ludwigia prostrata, and Eleocharis kuroguwai. However, MW gave fair control (70% biomass reduction) of all weed species tested. BR followed by MW or EM followed by MW treatments had similar effect on weed control compared to each treatment alone. However, BR followed by GAS or EM followed by GAS provided 100% control of weed species tested. The level of rice foliar injury caused by various organic materials was in the order of GAS and MW (10-20%) > RB (10-15%) > PM and EM (5-7%). Typical symptoms of organic materials are wilting, inhibition of growth, missing hill, and reduction of tiller. Cost for weed control of GAS, RB, EM, and PM were 2.1, 3.1, 2.3, and 13.2 times higher than that of the herbicide. These data indicate that GAS was the best method for weed management in environmentfriendly rice paddy fields. Further study is required to elucidate the mechanisms underlying the rice injury as affected by GAS.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.35 no.1
• /
• pp.57-62
• /
• 2015

"Nokyang" (Hordeum vulgare L.), a new whole-crop silage barley cultivar, was developed by the breeding team at the Department of Rice and Winter Cereal Crop, National Institute of Crop Science, RDA, Korea in 2012. It was derived from combining "Nagyoung" and breeding line "SB77368-B-145". Among the combinations made in 2001, a promising line, "SB01T2017", showed good characteristics in terms of potential forage yield in the yield trial at Iksan from 2007 to 2009. In 2009, the promising line was designated as "Iksan457" and placed in regional yield trials at six locations around Korea for three years from 2010 to 2012, and was released under the name of "Nokyang." It has the growth habit of a group III creeping plant type, with a light-green leaf and common spike. Its average heading and maturing dates were on May 6 and June 4, respectively, which were later than cultivar "Youngyang." "Nokyang" also showed strong winter hardiness, and a resistance to shattering and barley yellow mosaic virus (BaYMV) similar to those of the check cultivar. The best thing among the traits of one is a new good quality with the plant green at the latter growing period. The average forage dry matter (DM) yields in the regional yield trial were about 12.8 and 11.5 MT $ha^{-1}$ in upland and paddy field, respectively, which were higher than those of the check cultivar, by 7% and 2%, respectively. This cultivar would be suitable for an area of the Korean peninsula where the daily minimum temperature in January is above $-8^{\circ}C$.

• Research in Plant Disease
• /
• v.23 no.2
• /
• pp.150-158
• /
• 2017

Pear scab caused by Venturia nashicola has been reported as an important disease of pear resulting in lowering the quality of pear fruits. In this study, it was conducted to investigate the relationship between resistance of V. nashicola and mutation of ${\beta}$-tubulin gene and the fungicide resistance in field isolate group in benzimidazole fungicides. Responce of V. nashicola to carbendazim could be classified into 3 groups as sensitive that does not grow at all on PDA amended with $0.16{\mu}g/ml$ of carbendazim, low resistance that could not grow in $4.0{\mu}g/ml$ medium, and high resistance that can grow even at $100{\mu}g/ml$. Thirty isolates of V. nashicola collected from 3 regions as Wonju, Naju, and Okcheon were highly resistant to carbendazim. Analysis of the nucleotide sequence of ${\beta}$-tubulin gene of V. nashicola showed that there was no difference in the nucleotide sequence between the sensitive and the low-resistant isolate, but GAG at codon 198 (glutamic acid) was replaced with GCG (alanine) in the high-resistant isolate. Among 10 isolates obtained from the Okcheon, 5 isolates showed the substitution of glycine for glutamic acid, which were resistant to carbendazim, but more sensitive to the mixture of carbendazim and diethofencarb than others. Through these results, all isolates of V. nashicola isolated in pear orchard were found to be resistant to benzimidazoles. Also, mutants E198A and E198G at ${\beta}$-tubulin were found to be important mechanisms of V. nashicola resistance against benzimidazole fungicides.