• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.198-212
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• 2002

A numerical variation and abnormalities were studied on egg bags and embryos of Korean salamander, Hynobius leechii from agricultural habitat. The teratogenic and toxic effects of fungicide benomyl were also investigated with early embryos from non-agricultural habitat. We collected 144 egg bags from agricultural region, and 3418 of early embryos were contained. The lengths of egg bags were varied from 10 to 23 cm and the most frequent length was 19 cm. The number of embryos was varied from 7 to 43, and the most frequent range was 22 to 26. Spontaneous abnormalities were occurred in 406 embryos among 116 egg bags, and 24 kinds of external abnormalities were found. Individuals showing severe external defect were histologically studied and they showed optic dyspalsia, thyroid carcinoma, somatic muscular dysplasia, partial biaxial structure, decrease of red blood cells in the heart, cephalic degeneration and intestinal dysplasia. 385 embryos from non-agricultural region were exposed to 200 nM${\sim}$ 1 ${\mu}$M of benomyl at blastula or gastrula for 12 days. All embryo were dead in the concentration of 1 ${\mu}$M (LD$_{100}$) and 75% of embryos were dead in 800nM of benomyl. Speciflc effect due to benomyl was acrania or cephalic dysplasia and this restult suggests that the benomyl inhibit stongly to the development of neural tissue. These abnormal developments may be caused by antimitotic action, inhibition of tubulin complex, destruction of microtubule, inhibitions of neurulation and closing of neural fold, and by the inhibition of the movement of neural crest cells.

• Korean Journal of Ecology and Environment
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• v.48 no.2
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• pp.108-114
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• 2015

Single - and combined effects of a domestic freshwater bivalve Unio douglasiae (7.6~8.6 cm in shell length) and zooplankton Daphnia magna (1~2 mm in body size) were examined to understand whether they inhibit the growth of harmful cyanobacterial bloom (i.e. Microcystis aeruginosa) in a eutrophic lake. The experiments were triplicated with twelve glass aquaria (40 L in volume); three aquaria without mussel and zooplankton, served as a control, three zooplankton aquaria (Z, density=40 indiv. $L^{-1}$), three mussel aquaria (M, density=0.5 indiv. $L^{-1}$), and three mussel plus zooplankton aquarium (ZM, density=40 indiv.Z $L^{-1}$ plus 0.5 indiv.M/L), respectively. Algal growth inhibition (%) calculated as a difference in the concentration of chlorophyll-a (Chl-a) before and after treatment. Chl-a in all aquaria decreased with the time, while a greatest algal inhibition was seen in the ZM aquaria. After 24 hrs of incubation, Chl-a concentration at the mid-depth (ca. 15 cm) in ZM aquaria reduced by 90.8% of the control, while 63.2% and 79.8% in Z and M aquaria, respectively. Interestingly, during the same period, the surface Chl-a was diminished by 51.9% and 65.4% relative to the control in Z and ZM aquaria, while 27.4% of initial concentration decreased in M aquarium, respectively. These results suggest that 1) this domestic freshwater filter-feeding bivalve plays a significant role in the control of cyanobacterial bloom (M. aeruginosa), and 2) the combination with zooplankton and mussel has a synergistic effect to diminish them, compared to the single treatment of zooplankton and mussel.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.260-269
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• 2009

Hwabuk Dam has been under construction to reduce flood damage in Nakdong River watershed and to supply stable water for middle area of Gyeongbuk Province. Therefore, fish investigation in up and downstream of the dam was conducted from 2004 to 2008 in order to determine any negative effect on fish community due to dam construction and to use as fundamental data for conserving species diversity and maintaining stream health. According to data analysis on water quality, temperature, dissolved oxygen, pH, suspended solids, and total E-coli had seasonal variation, but they did not significantly differ in sites. However, biological and chemical oxygen demand, chlorophyll-a, nitrogen, and phosphorus representing organic matter and nutrient concentration were higher in upper site and decreased to lower site so that they differed by site. Concentration of arsenic among the heavy metals was less than 0.05 mg $L^{-1}$, which is regulated for protection of human health in water quality standard, except for 0.092 mg $L^{-1}$ in June 2005. During the study period, the total number of fish caught from the 6 sites was 10,263 representing 7 families 19 species. Among them, dominant and subdominant species were Korean chub (Zacco koreanus, 62.5%) and Chinese minnow (Rhynchocypris oxycephalus, 10.6%) which inhabit mostly in mid and upper streams, Korea. Among the 19 species, Korean endemic species were 9 species (47.4%) including Korean slender gudgeon (Squalidus gracilis majimae), Korean dark sleeper (Odontobutis platycephala), and Korean shiner (Coreoleuciscus splendidus). There was several individuals of the $1^{st}$-class endangered species, Naktong nose loach (Koreocobitis nahtongensis), caught in 2005${\sim}$2007, and no introduced species of fish was found in entire sampling period. According to result of community analysis, dominance index decreased toward lower site, but diversity and richness indices increased toward lower site. The equation of length-weight relationship on the dominant species was TW=0.000003$(TL)^{3.2603}$. The parameter b in the equation was greater than 3.0 indicating good nutritional condition in the populations. Compared to populations of Korean chub in other streams, the population in Hwabuk Dam watershed had higher mean of condition factor by size indicating better growth rate. With fish fauna and multi-metric health assessment model in each sampling attempt, index of biotic integrity (IBI) was evaluated and it resulted mostly in good (26${\sim}$35) and excellent (36${\sim}$40) condition in all sites, and the mean of IBI was the highest in site 5. The results indicate that it is very important to study not only environmental impact assessment with fish composition but also stream health assessment in order to conserve healthy aquatic ecosystem.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.2
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• pp.132-139
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• 1995

This experiment was canied out to select the soybean of high productivity suited for soiling. and growth characterisitcs, palatability, dry matter and crude protein yield of 10 cultivars of soybean have been evaluated at the experimental forage field. College of Natural Science of Kon-Kuk University in Chungju over three years (1 989-1 09 1 ). The results obtained are summarized as follows: JangBaek showed the tallest plant length from the 70th day to 80th day during cultivation period. and BaekUn showed the tallest at 90th day. PalDal among all cultivars showed the fastest growth rate and the strongest resistant lodging during cultivation period. The stem diameter of 70th day showed highly in order of PalDal and HwangKeum > BaekUn > KwangKyo and JangYeob, the 80th day showed highly in the order of TogYu > BaekCheon > JangBaek and 90th day showed highly in order of BangSa > BaekCheon > JangYeob. Stem hardness was highly increased with increasing of cultivation period, but no significant difference were found among the soybean cultivan. Especially, BaekUn and TogYu of 90th day showed very high as 17.9 and 17.6 kg/cm2, respectively. In the number of branch, PalDal was the lowest during cultivation period(70, 80 and 90th day), and 90th day showed lower two and three times than other soybeans(P<0.05). In the leaf rate, BaekCheon showed the highest according to cultivation period and the lowest in JangBaek. The fresh yield was tended to increase by increasing cultivation period at all cultivars except KwangKyo, but no significant differences were found among cultivars. Dry matter yield of JangYeob was the highest as 5, 861 kg/ ha at 70th day, and that of KwangKyo and TogYu was the highest as 7, 471 and 10, 603 kgha at 80th and 90th day, respectively. Relative palatability of 70th days showed very high at all soybean cultivars(81-100%), and that of 80th and 90th day showed the highest at TogYu, while showed the lowest at PalDal. In crude protein content of the 70th, 80th and 90th day, DanYeob, JangYeob and HwangKeum were the highest as 20.1, 17.9 and 20.4 percentage, respectively. Crude protein yield during cultivation period showed the highest at JangYeob(7Oth : 1, 068, 80th : 1, 211, 90th : 1, 882 kglha), but showed the lowest at BangSa(70th : 61 1, 80th : 814, 90th : 1, 078 kg/ha).

• Fire Science and Engineering
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• v.18 no.1
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• pp.54-66
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• 2004

In this article, we are to suggest the hazard-assessing method for the underground pipelines, and find out the pipeline-maintenance schemes of high efficiency in cost. Three kinds of methods are applied in order to refer to the approaching methods of listing the hazards for the underground pipelines: the first is RBI(Risk Based Inspection), which firstly assess the effect of the neighboring population, the dimension, thickness of pipe, and working time. It enables us to estimate quantitatively the risk exposure. The second is the scoring system which is based on the environmental factors of the buried pipelines. Last we quantify the frequency of the releases using the present THOMAS' theory. In this work, as a result of assessing the hazard of it using SPC scheme, the hazard score related to how the gas pipelines erodes indicate the numbers from 30 to 70, which means that the assessing criteria define well the relative hazards of actual pipelines. Therefore. even if one pipeline region is relatively low score, it can have the high frequency of leakage due to its longer length. The acceptable limit of the release frequency of pipeline shows 2.50E-2 to 1.00E-l/yr, from which we must take the appropriate actions to have the consequence to be less than the acceptable region. The prediction of total frequency using regression analysis shows the limit operating time of pipeline is the range of 11 to 13 years, which is well consistent with that of the actual pipeline. Concludingly, the hazard-listing scheme suggested in this research will be very effectively applied to maintaining the underground pipelines.

• Journal of Bio-Environment Control
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• v.13 no.1
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• pp.44-50
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• 2004

This experiment was conducted to investigate the effects of different levels of light intensity (100, 200, 400 ${\mu}mol\;{\codt}\;m^{-2}\;{\cdot}\;s^{-1}$, and natural light) on the growth and the fruit quality of cucumber(Cucumis sativus cv. Hyakunari-3). The results of this experiment indicated that plant height and length of lateral shoots were decreased under low light condition, but it was not significantly different among treatments. Leaf area and root weight were lowest under low light intensity(100 ${\mu}mol\;{\codt}\;m^{-2}\;{\cdot}\;s^{-1}$), but no significant differences were noted between 200 and 400 ${\mu}mol\;{\codt}\;m^{-2}\;{\cdot}\;s^{-1}$. Photosynthesis rate was decreased with reduced light intensity and total chlorophyll contents, root activity and xylem sap were also decreased under low light intensity, but there was no significant difference between 200 and 400 ${\mu}mol\;{\codt}\;m^{-2}\;{\cdot}\;s^{-1}$. From the SEM observation the erosion of the guard cells and closed stomata in low light treatment were shown and the size of stoma were small also the stomatal aperture were decreased with reducing the light intensity. Chlorosis in leaves and aborted-liked fruits were appeared under low light condition and Ca and Mg uptake in leaves were decreased by shading in proportion to the decrease of light intensity. Fruit yields were decreased by 65% under 400 ${\mu}mol\;{\codt}\;m^{-2}\;{\cdot}\;s^{-1}$, and by 80${\sim}$90% under 200 and 100 ${\mu}mol\;{\codt}\;m^{-2}\;{\cdot}\;s^{-1}$, compared to those under the natural light. This low intensity of light caused the sharp decrease in the early harvested yields within two weeks and the fruit yields of lateral shoots were greatly decreased.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.6
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• pp.921-927
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• 2015

The aim of this study was to investigate the effect of die temperature and repeated extrusion on physical properties of extruded white ginseng (EWG). The die temperature was adjusted to 100, 120, and $140^{\circ}C$, and extrusion was repeated under the same conditions with their corresponding samples. Specific mechanical energy input decreased as die temperature increased during extrusions. The secondary extruded white ginseng (SEWG) at a die temperature of $120^{\circ}C$ showed a higher expansion index than other extrudates. Elevation of both die temperature and repeated extrusion increased the specific length of extrudates. The highest apparent elastic modulus, breaking strength, and water solubility index obtained from SEWG at a die temperature of $100^{\circ}C$ were $7.53{\times}10^8N/m^2$, $7.49{\times}10^5N/m^2$, and 39.02%, respectively. When die temperature increased, water absorption index (WAI) decreased. The WAI of SEWG was higher than that of EWG. In conclusion, repeated extrusion affected physical properties of white ginseng and could be applied to produce improved quality of ginseng products.

• Journal of Korean Society of Forest Science
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• v.90 no.1
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• pp.113-123
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• 2001

The main purpose of this study was to provide information on attenuation effects in forest tree belt of pine stand and oak stand. The relationships between DBH, tree height, clear length, crown area and number of trees and also between distance from noise origin, landslope etc. were analysed by correlation and multiple regression. The results obtained were as follows : 1. There was no difference between pine stand and oak stand in effecting noise attenuation. 2. The noise pressure was highly correlated with all of seven elements tested and both DBH and distance from noise origin have higher r-values than the others. For the pine stand, it was 0.9133 in DBH and 0.9630 in the distance and for the oak stand, 0.9296 in DBH and 0.9565 in the distance. 3. The optimum regression equation for pine stand and oak stand were made by combination of two variables (DBH and distance). The table of noise attenuation was made by optimum regression equation. In the case of pine stand, the attenuation ratio was 29% at 5m, 31.6~32.6% at 10m, 38.3~39.8% at 20m and 45.2~46.6% at 30m. And case of oak stand, the attenuation ratio was 29% at 5m, 31.6~34.2% at 10m, 38.6~41.4% at 20m and 45~47.2% at 30m. 4. As the noise pressure limit at the Urban housing area according to environmental laws is under 55dB, it is suggested by the table of noise attenuation that the distance, and DBH for the pine and oak stand are over 20m, 400cm and 30-35 trees, respectively.

• Journal of Yeungnam Medical Science
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• v.22 no.2
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• pp.211-220
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• 2005

Background: The purpose of this study was to determine the effectiveness of a percutaneously placed self-expanding metallic stent for the relief of biliary obstruction in patients with hilar cholangiocarcinoma. Materials and Methods: From November 2001 to December 2004, 48 patients with hilar cholangiocarcinoma were prospectively studied. After percutaneous placement of bilateral selfexpanding, uncovered metallic stents, follow-up evaluation was carried out until July 2005. Results: There were 4 cases of Bismuth type II, 21 cases of Bismuth type IIIa, 8 cases of Bismuth type IIIb and 15 cases of Bismuth type IV. Stent placement was technically successful in all patients. All patients had satisfactory biliary drainage, resulting in one week drainage rate of 72.8% and final drainage rate of 91.1%. There were 12 cases (21.3%) of abdominal pain requiring analgesics and 1 case (7.1%) of cholangitis; both were successfully managed with conservative treatments. Late complications occurred in four patient (8.3%), including two patients with cholangitis, one patient with liver abscess, and one patient with biloma; all were appropriately managed by percutaneous drainage. The average length and median durations of stent patency and median survival time were 303 days (range, 60~815) and 338 days (range, 60~1175), respectively. Conclusion: Placement of a percutaneous metallic stent is an effective and safe method for palliation of patients with hilar cholangiocarcinoma.

• FLOWER RESEARCH JOURNAL
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• v.17 no.4
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• pp.251-255
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• 2009

This study was conducted to investigate effect of ionic strength and feeding times of a nutrient solution on reduction of stem cavity size and improvement of flower quality in chrysanthemum 'Baekma'. A nutrient solution was applied with different strengths at three stages, namely, transplanting, budding, and flowering. The solution EC was adjusted as 1.61.82.0, 1.81.81.8, 1.82.01.8, and $2.02.02.0dS{\cdot}m^{-1}$ in four treatments. Feeding frequency per a day were 4 times for 12 min., 8 times for 6 min., 12 times for 4 min., and 18 times for 2.7 min. each. Cut flower length as affected by different strengths of a nutrient solution was the greatest in the plot of EC $2.02.02.0dS{\cdot}m^{-1}$. However number of leaves, stem diameter, and leaf size were greater in EC $1.82.01.8dS{\cdot}m^{-1}$ than in other treatments. Also, petal number of petals was the greatest and stem cavity size was the smallest in the plot of EC $1.81.81.8dS{\cdot}m^{-1}$. Plant height, number of leaves, stem diameter, leaf size were greater in the plot with 12 times feed ing per a day. number of petal was most in the plot with 8 times feeding per day, while stem cavity size was the smallest in the plot with 12 times feed ing per a day. Therefore, the better plant growth, the smaller stem cavity size.