• Journal of Korean Society of Forest Science
• /
• v.95 no.6
• /
• pp.735-742
• /
• 2006

The objective of this study was to elucidate the tolerance of woody plants to simulated acid rain in relation to mycorrhizal inoculation. Germinating seedlings of Robinia pseudoacacia were planted in 1I pots with autoclaved soil mixture of vermiculite, sand and nursery soil at 1:1:1 ratio. Each pot was inoculated with both crushed root nodules from a wild tree of the same species and commercial arbuscular mycorrhizal inoculum of Glomus intraradices at the time of planting the seedlings. Simulated acid rains at pH 2.6, 3.6, 4.6, and 5.6 were made by mixing sulfuric acid and nitric acid at 3: 1 ratio. Each pot received nutrient solution without N and P, and was also supplied with 180 ml of the one pH level of the acid rains once a week for 50 days. The plants were grown in the green house. At the end of experimental period, plants were harvested to determine contents of chlorophyll, mineral nutrients and net photosynthesis in the tissues, dry weight of the plants, and mycorrhizal infection in the roots. Mycorrhizal infection rate was significantly reduced only at pH 2.6, which meant vitality of G intraradices was inhibited at extremely low pH. Height growth, dry weight production, nodule production and chlorophyll content were increased by mycorrhizal infection in all the pH levels except pH 3.6. Particularly, mycorrhizal inoculation increased root nodule production by 85% in pH 5.6 and 45% in 4.6 treatments. But the stimulatory effect of mycorrhizal inoculation on nodule production was reduced at pH 3.6 and 2.6. Net photosynthesis was increased by mycorrhizal infection in all the pH levels. The phosphorus(P) content in the tissues was increased by 43% in average by mycorrhizal inoculation, which was statistically significant except in pH 2.6. It was concluded that mycorrhizal inoculation of Robinia pseudoacacia would enhance growth and resistance of the plants to acid rain by improving the photosynthesis, phosphorus nutrition, and more nodule production.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.8
• /
• pp.1141-1149
• /
• 2011

The objective of this study was to analyze quality changes during storage of fresh-cut produce (leafy vegetables and condiment vegetables) as a function of packaging and storage temperature. Fresh-cut produce was washed using a three step cleaning process and was packed in vacuum packaging (green onion, hot pepper, onion, baechu) and perforated film packaging (buchu and perilla leaf). The effects of packaging method and storage temperature on quality of fresh-cut produce were determined by analyzing total plate counts, E. coli, coliform groups, moisture content, pH, Aw, surface color, and exterior quality during storage at 4 and 10$^{\circ}C$. According to the results, surface color change and microbial growth were delayed during storage at 4$^{\circ}C$. Additionally, E. coli was not detected during storage. Generally, moisture content decreased in the perforated film packaging. Changes in surface quality such as skin browning, softening of tissue and chlorosis at 4$^{\circ}C$ were inhibited, whereas rapid vacuum annealing and changes in color and flavor were observed in the sample stored at 10$^{\circ}C$. The result indicated that overall quality of the fresh-cut produce at 4$^{\circ}C$ was well maintained. The perforation in packing materials did not significantly increase the number of microorganisms on buchu and perilla leaf. The proper packaging methods and temperature may beneficial effect on microbial safety, quality and thus result in longer shelf-life fresh-cut vegetables during distribution.

• Tuberculosis and Respiratory Diseases
• /
• v.63 no.5
• /
• pp.405-411
• /
• 2007

Background: The objective of this study was to evaluate the clinical applicability of the repeatability criteria recommended by the American Thoracic Society/European Respiratory Society (ATS/ERS) spirometry guidelines and to determine which factors affect the repeatability of spirometry in Korean adults. Methods: We reviewed the spirometry data of 4,663 Korean adults from the Korean National Health and Nutritional Examination Survey (KNHANES) Chronic Obstructive Pulmonary Disease Cohort (COPD cohort) and the Community-based Cohort Study VI-Fishing village/Islands (community cohort). We measured the anthropometric factors and differences between the highest and second-highest FVC (dFVC) and $FEV_1$ ($dFEV_1$) from prebronchodilator spirometry. Analyses included the distribution of dFVC and $dFEV_1$, comparison of the values meeting the 1994 ATS repeatability criteria with the values meeting the 2005 ATS/ERS repeatability criteria, and the performance of linear regression for evaluating the influence of subject characteristics and the change of criteria on the spiro-metric variability. Results: About 95% of subjects were able to reproduce FVC and $FEV_1$ within 150 ml. The KNHANES based on the 1994 ATS guidelines showed poorer repeatability than the COPD cohort and community cohort based on the 2005 ATS/ERS guidelines. Demographic and anthropometric factors had little effect on repeatability, explaining only 0.5 to 3%. Conclusion: We conclude that the new spirometry repeatability criteria recommended by the 2005 ATS/ERS guidelines is also applicable to Korean adults. The repeatability of spirometry depends little on individual characteristics when an experienced technician performs testing. Therefore, we suggest that sustained efforts for public awareness of new repeatability criteria, quality control of spirograms, and education of personnel are needed for reliable spirometric results.

• KDI Journal of Economic Policy
• /
• v.14 no.2
• /
• pp.55-75
• /
• 1992

At the outset of import liberalization, most economists expected a significant drop in the prices of domestic goods that faced foreign competition. However, it is now generally acknowledge that a significant drop in prices of those goods has not occurred. A common claim is that the prices did not drop significantly because the major importers of many imported goods were also the domestic producers of competing goods. The objective of this paper is to analyze the welfare effect of importation by domestic firms that produce competing goods, to identify the factors that facilitate such business practices, and to formulate a policy that could improve the welfare. We proved that importation by competing domestic firms definitely raises the prices of both imported and domestic goods compared to the situation where foreign goods are imported by non-producers, ceteris paribus. The intuition behind this result is that since a producer-importer is essentially a cartel, its overall profit maximization requires reduced competition between the products that it sells. On the other hand, if a producer-importer is more efficient at distrinbution than a simple importer, the comparison between the two cases is a priori indeterminate. We also find that the industries in which domestic producers are actively involved in importing competing goods are the ones in which the distribution channels are tightly controlled by importer-producers. This finding suggests that exclusive dealing contracts, which work as an entry barrier, may be the source of importing by domestic producers. We argue that in a country such as Korea, where financial market is highly incomplete, tight control of the distribution channels by oligopolistic manufacturers is likely to be an effective entry barrier that leads to importing by domestic producers of similar goods. We further argue that seemingly superior distribution costs of importer-producers is likely to be a result of market foreclosure which would disappear once the entry barrier of exclusive dealing contracts is removed. Above findings suggest that market imperfections are the source of importation by domestic competitors, which in turn constitutes a market imperfection in itself and reduces consumer welfare. As potential remedies, we considered three alternatives; direct price control by the government over the imported goods sold by major domestic producers, regulation of trade itself between major producers, and regulation of exclusive dealing contracts. For reasons both theoretical and pratical, we find that the last alternative is the most attrative. Prohibiting exclusive contracts between manufacturers and dealers in industries where exclusive dealing contracts are a significant entry barrier is expected to break up the importer-producer cartel and improve the welfare.

• Clean Technology
• /
• v.13 no.2
• /
• pp.143-150
• /
• 2007

The objective of this study is to develop hydrocarbon-based cleaning agents by blending paraffins, glycol ethers and siloxanes in oder to effectively clean contaminants such as flux, solder and grease. And the effect of cleaning ability by wetting index, aniline points and solubility parameter of the formulated hydrocarbon-based cleaning agents were studied in this work. The formulated hydrocarbon-based cleaning agents were prepared on the base of physical properties of their individual components. Wetting indexes and aniline points of their were measured through experiments and solubility parameters of their were calculated based on the Hansen's equation. In this study, evaluation of cleaning ability by cleaning agents were carried out using contaminants such as flux, solder, and grease. The experimental results showed that the cleaning ability of the formulated cleaning agents was excellent in cleaning contaminants such as flux, solder and grease and that the influencing parameters on their cleaning efficiency were found to be different according to contaminant types. MC($20.3MPa^{1/2}$), DF-1 ($24.2MPa^{1/2}$) and DF-2($21.5MPa^{1/2}$) with similar solubility parameter as flux ($21.3MPa^{1/2}$) showed 100% cleaning efficiency within 3 minutes in flux cleaning. And CFC-113, MC and 1,1,1-TCE with low aniline point less than $-20^{\circ}C$ showed excellent cleaning efficiency in solder cleaning. DG-1($16.2\;MPa^{1/2}$) and DG-2($15.5\;MPa^{1/2}$) with similar solubility parameter as grease($15.0{\sim}17.0\;MPa^{1/2}$) showed relatively low cleaning efficiency of grease, but CFC-113 and MC with high wetting index and low aniline point showed good cleaning efficiency in grease cleaning. As a result of this study, the hydrocarbon-based cleaning agents alternative to regulated cleaning agents such as CFC-113, 1,1,1-TCE and MC were able to be developed through properly blending paraffins, glycol ethers and siloxanes for cleaning flux, solder and grease. And it can be shown that various influencing parameters of cleaning efficiency such as wetting index, aniline point, solubility parameter and etc. of the non-aqueous cleaning agent should be reviewed for prediction of their cleaning ability and can be applied to formulation of cleaning agents.

• Journal of Bio-Environment Control
• /
• v.27 no.4
• /
• pp.332-340
• /
• 2018

Supplemental lighting with artificial light sources is a practical method that enables normal growth and enhances the yield and quality of fruit vegetable in greenhouses. The objective of this study was to investigate the effect of sulfur plasma lamp (SP) and high-pressure sodium lamp (HPS) as supplemental lighting sources on the growth and yield of paprika. For investigating the effectiveness of SP and HPS lamps on paprika, the effects of primary lighting on plant growth were compared in growth chambers and those of supplemental lighting were also compared in greenhouses. In the growth chamber, plant height, leaf area, stem diameter, number of leaves, fresh weight, and dry weight were measured weekly at SP and HPS from 2 weeks after transplanting. In the greenhouse, no supplemental lighting (only sunlight) was considered as the control. The supplemental lights were turned on when outside radiation became below $100W{\cdot}m^{-2}$ from 07:00 to 21:00. From 3 weeks after supplemental lighting, the growth was measured weekly, while the number and weight of paprika fruits measured every two weeks. In the growth chamber, the growth of paprika at SP was better than at HPS due to the higher photosynthetic rate. In the greenhouse, the yield was higher under sunlight with either HPS or SP than sunlight only (control). No significant differences were observed in plant height, number of node, leaf length, and fresh and dry weights between SP and HPS. However, at harvest, the number of fruits rather than the weight of fruits were higher at SP due to the enhancement of fruiting numbers and photosynthesis. SP showed a light spectrum similar to sunlight, but higher PAR and photon flux sum of red and far-red wavelengths than HPS, which increased the photosynthesis and yield of paprika.

• Journal of Bio-Environment Control
• /
• v.29 no.2
• /
• pp.120-129
• /
• 2020

In Yesan-gun, Korea's main apple-producing region, the area of apple cultivation and yield are declining. In particular, the worsening quality of fruits due to unusually high temperatures amid recent climate change has also become a major challenge for apple orchards located on flatlands. The objective of this research is to investigate quality changes of apples according to different growing environments, depending on the shade of the sun, by covering the trees with different colors of wind nets. A white and blue wind nets with a hole size of 2 × 2 mm is installed on two experimental trees, 17-year-old 'Fuji' and 'Hongro', which are planted 1.5 m × 3.5 m in the north-south direction. Treatment of wind nets effectively lowered fruit surface temperature regardless of apple variety. When measuring the temperature of the fruit surface at 2 pm, the temperature of the air was 34.8℃, but the 'Fuji' of the untreated blocks was the highest at 40.0℃, while the blue wind net and the white wind net were significantly lower at 34.9℃ and 36.6℃, respectively. In 'Hongro', the results showed that the surface temperature was effectively lowered by recording 38.3℃ for the blue wind net and 38.5℃ for the white wind net treatment when the untreated one was 44.2℃. According to the color difference in 'Fuji', the skin redness (a^⁎) was the lowest with untreated control at 16.5, but the blue and white wind net treatment higher at 18.0 and 19.3, respectively. In 'Hongro', the white wind net treated fruit also showed a much higher skin redness than the untreated control of 28.1, showing much higher a^⁎ of 34.9. Sunburn damage in 'Fuji' apples amounted to 9.4% in untreated control. However, the blue and white wind net treatment revealed to 3.8% and 4.2%, respectively. In 'Hongro', those damage in the fruits treated with blue or white wind net, accounted for only 8.8% and 12.4%, respectively, significantly lower than 28.8% occurrence of untreated one. And, these results were understood to be the result of low UV radiation being blocked by the treatment of wind nets.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.6
• /
• pp.1059-1075
• /
• 2017

The objective of this study was to evaluate the freezing and thawing resistance of the existing drainage system for leakage treatment of underground concrete structures operating in cold regions. The freezing and thawing test was conducted on 4 types of drainage system specimens to evaluate the freezing and thawing resistance of the drainage system. The freezing and thawing resistance was evaluated on 4 types of Hotty-gel, as a waterproofing material, connection methods and on two methods to fix the drainage board with Hotty-gel on the surface of cement concrete specimen. One cycle of the freeze-thaw testing was 48 hours (24 hours of freezing and 24 hours of thawing), and the temperatures of freezing and thawing were at $-18^{\circ}C$ and $10^{\circ}C$, respectively. Among the 4 types of Hotty-gel connection methods, leakage occurred after 28 cycles (8 weeks) of freeze-thawing only in the Hotty-gel connection method with the 'V' groove applied to the corner of the drainage board. No leakage occurred in the 3 types of Hotty-gel connection methods. In two fixing methods, leakage occurred in the method of fixing the drainage board on the cement concrete specimen using the washer, screw and plastic wall plug. Leakage occurred at one point after 10 cycles (3 weeks) of freezing and thawing. After 28 cycles (8 weeks) of freezing and thawing, leakage point increased to 5 points. As time passed, the leak point was not increased, but the amount of leakage was increased at each leak point. The Hotty-gel connection method with cross-sectional diagonal shape was evaluated to be the highest in the production efficiency considering the production time and manufacturing method of the Hotty-gel connection shape. In the construction efficiency considering the construction time and construction method, the fixing method of air nailer, fixed nail and washer was superior to that of the washer, screw and plastic wall plug.

• Clinical and Experimental Reproductive Medicine
• /
• v.35 no.2
• /
• pp.143-153
• /
• 2008

Objective: To investigate the effects of aromatase inhibitor on reproductive hormone profiles and evaluate it's ovulation inducing capability in anovulatory infertile women. Methods: We quantified the blood levels of reproductive hormones from 30 healthy normal cycling women in natural cycle (control) and letrozole medicated cycle (study). LH, FSH, estradiol, testosterone, DHEA-S were quantified on third, 11th, 21th day in both cycles, and on 21th day, progesterone was added. Sixth anovulatory infertile women received either letrozole or clomiphene citrate for ovulation induction (n=30 in each groups). We compared the clinical parameters such as ovulation rate, pregnancy rate, the day of LH surge, number of follicles and endometrial thickness, cervical mucus amount, spinnbarkeit, mean diameter of follicles on the day of LH surge. Results: Letrozole had no effect on the LH, FSH, estradiol, DHEA-S secretion but there were significant increase in testosterone level on day 11 and progesterone level on day 21 in letrozole medicated cycle compared than control cycle ($0.40{\pm}0.16$ vs $0.28{\pm}0.11\;ng/ml$, p=0.002, $18.18{\pm}13.07$ vs $8.38{\pm}7.64\;ng/ml$, p=0.001, respectively). In comparison between letrozole and clomiphene groups, there were no significant difference in ovulation rate, pregnancy rate, number of mature follicle, mean diameter of follicles, but showed earlier LH surge, thicker endometrium, more cervical mucus, and higher spinnbarkeit in letrozole group ($12.12{\pm}2.46$ vs $14.52{\pm}3.18$ days, p=0.006, $10.48{\pm}1.23$ vs $8.52{\pm}0.93\;mm$, p=0.000, $2.04{\pm}0.61$ vs $1.57{\pm}0.59$, p=0.012, $6.00{\pm}1.12$ vs $4.95{\pm}1.61\;cm$, p=0.003, respectively). Conclusion: Letrozole may augment folliculogenesis and improve the endometrial condition for implantation in normal cycling women. Ovulation efficacy of letrozole in anovulatory women was comparable to clomiphene citrate and letrozole may be more physiological in ovulation induction.

• Journal of Acupuncture Research
• /
• v.19 no.1
• /
• pp.135-146
• /
• 2002

Background and Purpose : This study shows the clinical effects on treatment with Rheumatoid arthritis using Aqua-acupuncture such as Ursi Fel Bovis Calculus and Cathami Flos that are known for which have anti-inflammatory and analgesic effects. Objective and Methods : This study has been carried out Aqua-acupuncture treatment such as Cathami Flos and Ursi Fel Bovis Calculus twice or three times a week with patients diagnosed as rheumatoid arthritis on 7 criteria of US Rheumatism Academy. Results : 1. If you see the sexual distribution, it shows the rates of male and female 1: 1.83. Age distribution shows as age ascend it shows high. 2. If you see the duration distribution, it shows chronic tendency in order of more than 6 months(63.3%), 2 to 5 months, and I month. 3. If you see the invaded distribution, it shows chronic tendency in order of hand(37 cases), wrist joint(34 cases), knee joint(32 cases), ankle joint(21 cases), elbow joint(16 cases), shoulder joint(14 cases), feet(14 cases), hip joint(9 cases), low back(6 cases), neck(4 cases). 4. Seeing the mean post-therapeutic index among groups on RA factor level distinction, it shows that 0-18(normal range) scored 89.0, 19-50 scored 94.8, 51-80 scored 101.2, 81-100 scored 97.3, 101-140 scored 102.4, above 141 scored 97.5. 5. Seeing the mean post-therapeutic index among groups on CRP level distinction, it shows that 0-0.4(normal range) scored 100, 0.5-1.0 scored 48.6, 1.1-2.0 scored 34.9, 2.1-3.0 scored 35.7, 3.1-4.0 scored 37.1, 4.1-5.0 scored 53.8, above 5.0 scored 70.4. 6. Seeing the mean post-therapeutic index among groups on ESR level distinction, it shows that 0-20(normal range) scored 48.6, 21-40 scored 57.5, 41-60 scored 59.2, 61-80 scored 59.2, above 81 scored 66.0. 7. If you see the satisfactory assesment after Aqua-acupuncture treatment such as Cathami Flos and Ursi Fel Bovis Calculus, Excellent is 11 cases, Good is 14 cases, and Moderate 5 cases. Conclusion : It will be better effects, if herbal medicine, moxibustion, and acupuncture are used together with Cathami Flos and Ursi Fel Bovis Calculus on rheumatoid arthritis as chronic inflammatory disease.