• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.1
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• pp.22-29
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• 2001

In Korean high yielding varieties developed by crosses between indica and japonica rice, the most limiting factor for yield may be attributed to the less number of the tillers in the unit area. The goals of this study is to find out the effect of the temperature factors as well as cultural practices on the development and increase of tillers of Dasanbyeo, the high yielding indica crossed japonica cultivar. The effect of temperature was examined under controlled phytotron condition with 6 levels of temperature, 15, 17, 19, 22, 24 and 26$^{\circ}C$, respectively, For the experiment, the leading japonica variety in Korea, Hwaseongbyeo, was used for the check cultivar for the comparison with Dasanbyeo. The high temperature also accelerated the initiation and termination of tiller development. The cultivar difference in the speed of tiller development was observed, for example, more rapid development of tiller in Dasanbyeo than in Hwaseongbyeo was observed at the high temperature range of 24-26$^{\circ}C$, while the vice versa phenomena was observed at lower temperature range of 17-22$^{\circ}C$. The first secondary tiller of Dasanbyeo was observed on the 16, 17, 23, 27 and 38 days after transplanting (DAT) at 26$^{\circ}C$, 24$^{\circ}C$, 22$^{\circ}C$, 19$^{\circ}C$, and 17$^{\circ}C$, respectively. Those of Hwaseongbyeo was 19-22, and 26 DAT at 19-26$^{\circ}C$ and 17$^{\circ}C$, respectively. The last effective tiller of Dasanbyeo was observed on 27-33 DAT for the primary tiller, 20-41 DAT for the secondary tiller. Those of Hwaseongbyeo were 23-40 DAT for primary tiller, and 24-40 DAT for the secondary tiller, and 24-40 DAT for the secondary tiller.

• Parasites, Hosts and Diseases
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• v.23 no.2
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• pp.253-259
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• 1985

In order to correlate the number of eggs In female Enterobius vermicularis with their body length and to re-evaluate the number of eggs liberated by gravid females, a total of 203 worms were examined. Those females were removed from naturally infected orphans with mebendazole (100mg) and had been fixed in 10% formalin(Cho et al., 1981). The decent ones which were selected under dissecting microscope were unbroken, neatly fixed females without contaminated eggs on their surface. The worms were measured by their body length, softened in 0.1N NaOH solution overnight, and teased by dissecting needles. And their number of shelled eggs was measured in a counting chamber made as described by Denham et at. (1971). The results were summarized as follows: 1. The observed females, 4.10~9.90mm long, began to have shelled eggs in uterus when body length was 5.50mm or longer. 2. The percentage of females with eggs in uterus was as follows by range of body length: 25% in 5.50~5.99mm long, 53.3% in 6.00~6.49mm long, 86.7% in 6.50~6.99mm long, 95.2% in 7.00~7.49mm long and 100% in 7.50mm or longer. 3. The mean and standard deviation of egg number were as follows by the length of females: $19{\pm}50$ in 5.50~5.99mm long, $734{\pm}1,597$ in 6.00~6.49mm long, $1,473{pm}1,606$ in 6.50~6.99mm long, $1,530{\pm}2,055$ in 7.00~7.49mm long, $2,567{\pm}2,046$ in 7.50~7.99mm long, $5,598{\pm}2,470$ in 8.00~8.49mm long, $9,318{\pm}2,651$ in 8.50~8.99mm long, $10,678{\pm}2,892$ in 9.00~9.49mm long and $13,323{\pm}1,778$ in 9.50~9.90mm long. 4. The numbers of uterine eggs showed greater individual variation when the female lengths were in range of 5.5~8.0mm. When the female length was longer than 9.0mm, the egg numbers were over 10,000 in majority, and showed lesser individual variations. Above results su99ested that the e99 Production in female 5. vermicularis began in 28~32 days after infection and that in early stapes, the egg Production varied by individual worms, but in gravid females longer than 9. Qmm at last deposited 10,000 to 16,000 eggs in their uterus with the least individual variations.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.260-266
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• 2000

Water quality parameters were surveyed in Lake Andong. Turbidity, temperature, secchi disc transparency (SD), phosphorus, nitrogen and chlorophyll a concentration were measured at dam site from July 1993 to December 1998. Minimum transparency in summer was only about 2 meters in 1993 and 1994, but it decreased to about 1 meter in 1997 and 1988. Total phosphorus concentration of the epilimnion increased slightly from $11{\sim}30\;mgP/m^3$ in 1993 to $18{\sim}42\;mgP/m^3$ in 1998. Total nitrogen concentration of the epilimnion decreased slightly from $1.81{\sim}2.96\;mgN/L$ in 1993 to $1.48{\sim}2.57\;mgN/L^3$ in 1998. TN/TP weight ratio decreased from $82{\sim}281$ in 1993 to $21{\sim}143$ in 1998 due to the increase of phosphorus concentration and the decrease of nitrogen concentration. Dissolved inorganic phosphorus concentration and the decrease of nitrogen concentration. Dissolved inorganic phosphorus and nitrate nitrogen concen tration of the epilimnion were in the range of $0.9{\sim}5.3\;mgP/m^3$ and $1.36{\sim}1.68\;mgN/L$, respectively. Chlorophyll a concentration in summer was in the range of $11.0{\sim}19.1\;mg/m^3$ in 1994, 1996 and 1997, but it decreased to $2.3{\sim}6.5\;mg/m^3$ in 1998. Trophic state of Lake Andong can be classified as mesotrophic to eutrophic from TP, TN and chlorophyll a concentration.

• Journal of the Korean earth science society
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• v.43 no.2
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• pp.283-302
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• 2022

Despite the nationwide COVID-19 lockdown in China since January 23, 2020, haze days with high PM₁₀ levels of 88-98 ㎍ m^-3 occurred on February 1 and 2, 2020. During these haze days, the East Asian region was affected by a warm and stagnant air mass with positive air temperature anomalies and negative zonal wind anomalies at 850 hPa. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) was used to analyze the variation of regional PM₁₀ aerosol transport in Korea due to decreased anthropogenic emissions in East Asia. The base experiment (BASE), which applies the basic anthropogenic emissions in the WRF-Chem model, and the control experiment (CTL) applied by reducing the anthropogenic emission to 50%, were used to assess uncertainty with ground-based PM₁₀ measurements in Korea. The index of agreement (IOA) for the CTL simulation was 0.71, which was higher than that of BASE (0.67). A statistical analysis of the results suggests that anthropogenic emissions were reduced during the COVID-19 lockdown period in China. Furthermore, BASE and CTL applied to zero-out anthropogenic emissions outside Korea (BASE_ZEOK and CTL_ZEOK) were used to analyze the variations of regional PM₁₀ aerosol transport in Korea. Regional PM₁₀ transport in CTL was reduced by only 10-20% compared to BASE. Synthetic weather variables may be another reason for the non-linear response to changes in the contribution of regional transport to PM₁₀ in Korea with the reduction of anthropogenic emissions in East Asia. Although the regional transport contribution of other inorganic aerosols was high in CTL (80-90%), sulfate-nitrate-ammonium (SNA) aerosols showed lower contributions of 0-20%, 30-60%, and 30-60%, respectively. The SNA secondary aerosols, particularly nitrates, presumably declined as the Chinese lockdown induced traffic.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.65-76
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• 2006

Scz1, an isolate of Sclerotinia homoeocarpa, was recently reported as a novel pathogen responsible for dollar spot disease in Zoysiagrass, a warm season turfgrass. Scz1 possessed different characteristics on mycelial pigment, mycelial affinity and host pathogenecity compared to those of Scb1, a typical isolate, obtained from creeping bentgrass, a cool season turfgrass. In this study, only three isolates, Scz1, Scz2(another analogous isolate of Sclerotinia homoeocarpa from zoysiagrass), and Scb1, were examined at the molecular level using the internal transcribed spacer(ITS) and random amplified polymorphic DNA(RAPD) assays to verify their identification and genetic variation. As a result of ITS assay, partial ITS sequences of three isolates showed 94-97% similarity with a standardized ITS sequence of S. homoeocarpa registered on BLAST. In the analysis of RAPD, range value through similarity matrix was 0.167 between Scz1 and Scb1, 0.139 between Scz2 and Scb1, and 0.713 between Scz1 and Scz2, respectively. Furthermore, tendegram analysis indicated that Scz1 and Scz2, unlike Scb1, were clustered together as accompanying a high genetic similarity. In in vitro fungicide bioassay, $EC_{50}$ value representing the sensitivity degree to propiconazole, a well-known fungicide for dollar spot disease, was 0.012 ${\mu}g/ml$ for Sczl, 0.003 ${\mu}g/ml$ for Scz2, and 0.030 ${\mu}g/ml$ for Scb1. From all data taken, we concluded that both Scz1 and Scz2 belonged to one group of S. homoeocarpa, since they exhibit the same host range and high level of genetic similarity, whereas their chemical competences to a fungicide were different. This study would provide further approach for assessing genetic diversity of S. homoeocarpa isolates as well as characterizing individual isolate against chemical exposure.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.5
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• pp.720-726
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• 1995

Chemical components relevant to the characteristic taste of the Korean native persimmon(Diospyros kaki, Thumb) leaf tea were analyzed. Samples were processed by using three different methods ; SHT(steamed and then hot-air dried), DHT(dried in the shade, steamed and then hot-air dried) and RHT(roasted and then hot-air dried). The components analyzed were general compositions of dried perisimmon leaves and extracted solution. The composition of moisture, ash, crude lipid and total nitrogen did not show significant variation among different processing methods of the persimmonleaf tea. The contents of caffeine, tannin and vitamin C in persimmon leaf tea were in the range of $178.4~209.8{\mu}mol/g$, 29.1~38.5mg% and 325.3~2084.7mg%, respectively. The vitamin C content was significantly higher in the RHT than other treatments. The contents of caffeine, tannin and vitamin C in the tea extracted solution were in the range of $101.5~130.1{\mu}mol/g$, 15.4~25.9mg% and 111.0~1274.3mg%, respectively. The vitamine C in the tea solution was the highest in the RHT treatment and 61.1% of vitamin C in the leaf tea was extracted out in these processing methods. The major amino acids contained in the leaf tea were in decreasing order glutamic acid, aspartic acid, leucine and phenylalanine, these four amino acids consisting 38.9~39.8% of the total amino acid contained in the persimmon leaf tea. The major amino acids contained in the tea solution were glutamic acid, proline, histidine and arginine. Six kinds of 5'-nucleotides, CMP, AMP, UMP, IMP, GMP and hypoxanthine were detected and CMP was the most abundant component in fresh leaf, leaf tea and tea solution. The second highest 5'-nucleotides in both leaf tea and tea solutions were GMP, AMP and UMP in all processing method. The highest free sugar contained in the fresh leaf tea and tea solution was sucrose.

• Journal of Food Hygiene and Safety
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• v.26 no.4
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• pp.308-314
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• 2011

This study surveyed and compared the temperatures established in display stands and food surfaces for cold and frozen foods in large discount stores in Korea. The temperatures established in display stands for cold food ranged with $3.5{\pm}1.8^{\circ}C$ as mean, minimum and maximum were $0^{\circ}C$ and $7^{\circ}C$. However, the surface temperatures of cold food on sale ranged with $10.7{\pm}2.9^{\circ}C$ as a mean, minimum $4.6^{\circ}C$ and maximum $18.4^{\circ}C$. Totally, the surface temperature of cold food on sale was $7.2^{\circ}C$, as a mean, higher than established in display stands for cold food in large discount stores in Korea. 53% of the surveyed cold foods were more than $10^{\circ}C$ in surface temperature and only 47% was less than $10^{\circ}C$. The differences between temperatures were lowest in fruits, salads and vegetables, but highest in milk products. On the other hand, the temperatures established in display stands for frozen food showed a range with $-20.7{\pm}1^{\circ}C$ as a mean. However, the surface temperatures of frozen food on sale showed a range with $-15.4{\pm}5^{\circ}C$ as a mean, minimum $-28^{\circ}C$ and maximum $-4.6^{\circ}C$ (included defrosting). The surface temperatures of frozen food, frozen meats, frozen processed foods and ice creams were $-13.8^{\circ}C$, $-15.9^{\circ}C$, and $-16.8^{\circ}C$, respectively. Only 32.3% of surveyed frozen foods showed less than $-18^{\circ}C$ in surface temperature. In conclusion, the temperatures established on cold and frozen food display stands were less than those of cold and frozen food surfaces on sale. There was also much variation in food surface temperatures during cold and frozen food storage and sales. Therefore, a temperature management system technology use at the distribution level for cold and frozen foods will be developed.

• Journal of Food Hygiene and Safety
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• v.19 no.1
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• pp.12-18
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• 2004

Ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin in chicken muscle were seperated by liquid extraction and determined with high performance liquid chromatography (HPLC) with fluorescence detector. Analysis was carried out using following conditions; Cl8 column (250${\times}$4.6 mm i.d. 5 ${\mu}{\textrm}{m}$ particle size), mobile phase composed of D.W. (containing 0.4% triethylamine and phospholic acid): methanol : acetonitrile (800:100:100, v/v/v), isocratic pump at a flow rate of 1.0 $m\ell$/min and 50 ${mu}ell$ of injection volume, fluorescence detector with EX278 nm/EM.456 nm. The calibration curves of four fluoroquinolones showed linearity (${\gamma}$$^2$$\geq$0.999) at concenration range of 0.025-0.6 $\mu\textrm{g}$/ml. The recoveries in fortified chicken muscle represented more than 80% with low coefficient of variation (〈10%) for concentration range of four fluoroquinolones. The detection limits for ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin were 23.5, 3.4, 3.0 and 2.5 ng/g in chicken muscle, respectively. We also monitored fluoroquinolones residue in muscle of chickens (broiler 1:227, Korean native chicken 219, laying chicken 77) using EEC-4-plate screening and HPLC conformation methods. Ten(broiler 5, Korean native chicken 5) out of the fifteen samples which were positively detected by EEC-plate screening method from 1,523 chicken meat were confirmed with ciprofloxacin and enrofloxacin by HPLC. The ranges of residual concentration were 0-0.12 ppm for ciprofloxacin and 0.01-6.79 ppm for enrofloxacin. In conclusion, our method could be applied effectively to determine four fluoroquinolones residues in chicken meat, and further survey for fluoroquinolones residue in chicken meat are needed for more effective control of fluoroquinolones used in livestock.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.498-507
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• 2006

The main objective of present study was to evaluate how seasonal rainfall influenced natural habitat conditions of 10 metric habitat variables along with ionic conditions and suspended solids in the Woopo Wetland during August 2002-July 2003. Largest spatial variabilities in total suspended solids (TSS) occurred during the summer monsoon and the inorganic suspended solids (ISS), expressed as a inorganic proportion of total solids, showed linearly increasing trend from the upstream to downstream. This phenomenon was mainly attributed to counter flow of turbid water from the main Nakdong-River. During the flooding, ISS : TSS ratio showed large increases (92%) in the downstream than the upstream (43%). For this reason, transparency declined (mean=0.13 m, range=0.08-0.21 m) largely in the downstream reach and thus, chlorophyll-a concentration showed low values (range: $4.2-8.6\;{\mu}g\;L^{-1}$), indicating a direct influence on primary productivity or algal growth by inorganic turbidity. In the 2nd survey, ISS averaged 4.0 mg $L^{-1}$ (3.3-4.8 mg $L^{-1}$), thus the ISS decreased by 14 fold, compared to the ISS in the 1st survey during the flooding, while organic suspended solids (OSS) values were greater than those of ISS, indicating a dominance of organic solids. This condition was similar to solid contents in the 3rd survey, but showed a large difference compared to the 4th survey during the growing season. Habitat health assessments, based on 10 metric habitat variables, showed that QHEI values were greatest in the growing season (May) than any other seasons and largest spatial variations occurred in the 2nd survey. Overall, dataset suggest that seasonal episodic flooding during the monsoon may largely contribute nutrient cycling and sediment contents in the Woopo Wetland and Topyung Stream.

• Economic and Environmental Geology
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• v.38 no.4 s.173
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• pp.481-492
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• 2005

The purpose of this study is to determine geochemical characteristics for stream sediments in the Gwangju area. We collect the stream sediments samples by wet sieving along the primary channels and dry these samples slowly in the laboratory and grind to under 200mesh using an alumina mortar fur chemical analysis. Major elements, trace and rare earth elements are determined by XRF, ICP-AES and NAA analysis methods. For geochemical characteristics on geological groups of stream sediments, we separate geologic groups which are derived from Precambrian granite gneiss area, Jurassic granite area and Cretaceous Hwasun andesite area. Contents range of major elements for stream sediments in the Gwangju area are $SiO_2\;51.89\~70.63\;wt.\%,\;Al_2O-3\;12.91\~21.95\;wt.\%,\;Fe_2O_3\;3.22\~9.89\;wt.\%,\;K_2O\;1.85\~4.49\;wt.\%,\;MgO\;0.68\~2.90\;wt.\%,\;Na_2O\;0.48\~2.34\;wt.\%,\;CaO\;0.42\~6.72\;wt.\%,\;TiO_2\;0.53\~l.32\;wt.\%,\;P_2O_5\;0.06\~0.51\;wt.\%\;and\;MnO\;0.05\~0.69\;wt.\%.$ According to the AMF diagram for stream sediments and rocks, the stream sediments are plotted on boundary of tholeiitic series and calk alkaline series, which shows that contents of $Fe_2O_3$ are higher in stream sediments than rocks. According to variation diagram of $SiO_2$ versus $(K_2O+Na_2O),$ stream sediments are plotted on subalkaline series. Contents range of trace and rare earth elements for stream sediments in the Gwangiu area are Ba$590\~2170$ppm, Be1\~2.4$ppm, Cu$13\~79$ppm, Nb$20\~34$ppm, Ni$10\~50$ppm, Pb$17\~30$ppm, Sr$70\~1025$ ppm, V$42\~135$ppm, Zr$45\~171$ppm, Li$19\~77$ppm, Co$4.3\~19.3$ppm, Cr$28\~131$ppm, Cs$3.1\~17.6$ppm, Hf$5\~27.6$ppm, Rb$388\~202$ppm, Sb$0.2\~l.2$ ppm, Sc$6.4\~17$ppm, Zn$47\~389$ppm, Pa$8.8\~68.8$ppm, Ce$62\~272$ppm, Eu$1\~2.7$ppm and Yb$0.9\~6$ppm.