• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.23-30
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• 2007

The ultimate objective of this study is to develop oxygen-enriched combustion techniques applicable to the system of practical industrial boiler. To this end the combustion characteristics of lab-scale LNG combustor were investigated as a first step using the method of numerical simulation by analyzing the flame characteristics and pollutant emission behaviour as a function of oxygen enrichment level. Several useful conclusions could be drawn based on this study. First of all, the increase of oxygen enrichment level instead of air caused long and thin flame called laminar flame feature. This was in good agreement with experimental results appeared in open literature and explained by the effect of the decrease of turbulent mixing due to the decrease of absolute amount of oxidizer flow rate by the absence of the nitrogen species. Further, as expected, oxygen enrichment increased the flame temperatures to a significant level together with concentrations of $CO_2$ and $H_2O$ species because of the elimination of the heat sink and dilution effects by the presence of $N_2$ inert gas. However, the increased flame temperature with $O_2$ enriched air showed the high possibility of the generation of thermal $NO_x$ if nitrogen species were present. In order to remedy the problem caused by the oxygen-enriched combustion, the appropriate amount of recirculation $CO_2$ gas was desirable to enhance the turbulent mixing and thereby flame stability and further optimum determination of operational conditions were necessary. For example, the adjustment of burner with swirl angle of $30\sim45^{\circ}$ increased the combustion efficiency of LNG fuel and simultaneously dropped the $NO_x$ formation.

• Korean Journal of Microbiology
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• v.54 no.1
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• pp.9-17
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• 2018

To investigate the role of bkdR, sigL, yplP, and des genes which were known to be involved in fatty acid synthesis and sensitive at low temperature, deletion mutants of Bacillus subtilis CU1065 and JH642 were constructed. To determine the low temperature sensitivity of these genes, we compared the growth curves of cells at $37^{\circ}C$ and $15^{\circ}C$. At $37^{\circ}C$, wild type and deletion mutants showed almost similar growth but only bkdR deletion strain at $15^{\circ}C$ showed very slow growing compared with wild type. At $15^{\circ}C$ sigL and yplP deletions were somewhat slower or similar to those of wild type strain. Double and triple mutants for bkdR, sigL, yplP deletions were constructed and grown at $20^{\circ}C$ in LB agar to investigate cold sensitive growth. Double or triple deletions including bkdR deletion showed cold sensitive growing. In order to identify more clearly cold sensitive growth, the experiments were carried out under cold shock conditions in which the temperature was lowered from $37^{\circ}C$ to $15^{\circ}C$ at the point of 0.4 optical densities at 600 nm. In these cold shock experiments, only bkdR deletion showed significantly lower growing and additional des deletion increases cold sensitivity. The bkdR activates the bkd operon, which catabolized isoleucine, valine and leucine, amino acids and produce precursors for the synthesis of branched fatty acids. At cold shock growing of bkdR deletion strain, isoleucine recovered cold sensitivity of bkdR deletion but valine did not restore cold sensitivity. Isoleucine is used as a precursor for the synthesis of anteiso-branched fatty acids. On the other hand, valine is used as a precursor for the synthesis of iso-branched fatty acids. This indicates that anteiso-branched fatty acid plays an important role at the cold shock condition.

• Journal of Chest Surgery
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• v.38 no.7 s.252
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• pp.489-495
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• 2005

In the surgical treatment of aortic dissection, aortic arch replacement under total circulatory arrest is often performed after careful inspection to determine the severity of disease progression. Under circulatory arrest, antegrade or retrograde cerebral perfusion is required for brain protection. Recently, antegrade cerebral perfusion has been used more, because of the limitation of retrograde cerebral perfusion. This study is to compare these two methods especially in the respect to neurological complications. Material and Method: Forty patients with aortic dissection involving aortic arch from May 2000 to May 2004 were enrolled in this study, and the methods of operation, clinical recovery, and neurological complications were retrospectively reviewed. Result: In the ACP (antegrade cerebral perfusion) group, axillary artery cannulation was performed in 10 out of 15 cases. In the RCP (retrograde cerebral perfusion) group, femoral artery Cannulation was performed in 24 out of 25 cases. The average esophageal and rectal temperature under total circulatory arrest was $17.2^{\circ}C\;and\;22.8^{\circ}C$ in the group A, and $16.0^{\circ}C\;and\;19.7^{\circ}C$ in the group B, respectively. Higher temperature in the ACP group may have brought the shorter operation and cardiopulmonary bypass time. However, the length of period for postoperative clinical recovery and admission duration did not show any statistically significant differences. Eleven out of the total 15 cases in the ACP group and thirteen out of the total 25 cases in the RCP group showed neurological complication but did not show statistically significant difference. In each group, there were 5 cases with permanent neurological complications. All 5 cases in the ACP group showed some improvements that enabled routine exercise. However all 5 cases in RCP group did not show significant improvements. Conclusion: The Antegrade, cerebral perfusion, which maintains orthordromic circulation, brings moderate degree of hypothermia and, therefore, shortens the operation time and cardiopulmonary bypass time. We concluded that Antegrade cerebral perfusion is safe and can be used widely under total circulatory arrest.

• Journal of Ginseng Research
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• v.27 no.3
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• pp.103-109
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• 2003

We investigated the effect of ginseng total saponin (GTS) on the regeneration process of experimentally crush injured rat sciatic nerves. The bilateral sciatic nerves of fifty adult male Sprague-Dawley rats were compressed surgically with a straight hemostat for 30 seconds with 1 mm width. Twenty rats were divided into four groups to test the dose-dependent effect of GTS (0, 50, 100, or 150 mg/kg, i.p.). Saline for vehicle control group or GTS dissolved in saline was administerd for three weeks. After that period of time, the numbers of total myelinated axon and degenerated myelin in the sciatic nerves of bilateral legs were examined and analyzed using image analysis system to confirm a morphological effect of GTS. We found that the most effective concentration of GTS for the regeneration of damaged sciatic nerve was 150 mg/kg. In another set of experiment, thirty rats were divided into two groups as saline-treated vehicle group and GTS-treated group (150 mg/kg, i.p.) for three weeks. Every week we examined the numbers of total myelinated axon and degenerated myelin in the sciatic nerves of bilateral legs using image analysis system to evaluate the effect of GTS on injured nerves. We found that the regeneration of damaged sciatic nerves was facilitated in GTS-treated group compared to saline-treated group until two weeks. However, after that period of time we could not observe the significant difference between saline-treated group and GTS-treated group. These results suggest that GTS is a useful adjuvant therapy for the regeneration of the peripheral nerve injury in short period of treatment.

• Journal of Sericultural and Entomological Science
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• v.32 no.2
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• pp.113-117
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• 1990

The recovery of mulberry from a late frost (April 24 to 27) was investigated for four varieties : Kaeryangppong, Cheongilppong, and Jamsang 21 in Cheongju area, Chungbuk Province. 1. Unfavourable meteorlogical conditions for recovery of mulberry followed the early late frost : lower than normal temperatures in mid-April, less sunshine in early and mid-Jay, lower temperatures and early and less precipitation in late-May, and less precipitation than normal in early June. 2. Jamsang 21 grew to the 2-3 leaf stage first, at which time Kaeryangppong and Jamsang 22 were at the 1-2 leaf stage, and Cheongilppong was at the swallow-bill shape-1 leaf stage. 3. The first leaf stage occurred on May 12, 15 days after the frost and, 19 days later in an average year. The difference lasted until the harvesting season, the 6 leaf stage. 4. Young shoot length was 50-58% of that in 1989. Kaeryangppong was the shortest at 50% and the Jamsang 21 highest at 58% of 1989 values. 5. Leaf number was 52-67% that in 1989. Kaeryangppong was the lowest at 52% and the Jamsang 21 highest at 67% of 1989 values. 6. Young shoot and leaf weight was 44-63%, and leaf weight 39-61%, compared to 1989. Kaeryangppong and Cheongilppong were the lowest, Jamsang 21 and Jamsang 22 were the highest, compared to 1989 data. 7. Young shoot length was 50-58% compared with 1989. Kaeryangppong was the lowest as 50%, the highest Jamsang 21 as 58%. 8. Number of leaf was 52-67% compared with 1989. Kearyangppong was the lowest as 52%, the highest Jamsang 21 as 67%. 9. Young shoot and leaf wight was 44-63%, and leaf weight was 39-61% compared with 1989. Kaeryangppong was the lowest, lowest, Jamsang 21 was the highest, Cheongilppong was similar with Kaeryangppong and Jamsang 22 was similar with Jamsang 21. 10. Rate of young shoot and leaf weight to total weight decreased from 75% in 1989 to 55-61% in 1990. Rate of laef weight to young shoot decreased from 72-82% to 67-71%, showed 5-10% decrease. 11. Leaf yield decreased highly in Jamsang 22 as 57% compared with 1989. Kearyangppong 61%, Jamsang 21 64%, Cheonglppong 72%. Leaf yield was 827kg/10g in Kaeryangppong, 1, 000-1, 050kg/10a in the other varieties.

• Journal of Animal Science and Technology
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• v.50 no.5
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• pp.705-712
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• 2008

Sixteen multiparous lactating Holstein cows were used to compare effects of supplementing 1)no additive(Control), 2)1.2% sodium bicarbonate(NaHCO3); 3)niacin(80g/d), 4)vitamin A+E (140,000IU+1000IU) on feed intake, milk production, milk composition and somatic cell counts during the summer months. Insofar as possible, treatment groups were balanced for lactation number and days in milk. Cows were fed a diet of 9.1kg DM of concentrate and 10.2kg DM of corn silage. Daily maximum air temperature in free stall barn was 35℃ for 3 days of the pretreatment periods and decreased gradually up to 27℃ during the treatment periods of 15days. Dry matter intake of corn silage was higher(p<0.05) for cows consuming NaHCO3 than those not consuming NaHCO3. Daily milk production for niacin and vitamin A+E supplementations resulted in significant(p<0.001) increase in milk production from 3 day of trials than control and NaHCO3. Milk fat percentage tended(p=0.09) to increase and milk lactose percentage was increased significantly(p<0.001) for cows supplemented with NaHCO3, niacin and vitamin A+E. Milk protein percentages was higher significantly(p<0.05) with supplemental niacin and somatic cell counts was higher significantly(p<0.001) with supplemental vitamin A+E. These data strongly suggest that supplementation of NaHCO3, niacin or vitamin A+E should be increased for improving milk production and mammary gland health of dairy cows under heat stress.

• Culinary science and hospitality research
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• v.8 no.3
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• pp.309-321
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• 2002

In this study, the characteristics of Jeung-pyun hatter were investigated by wine yeast. The processing conditions were optimized by physicochemical characterization including pH, volume, reduced sugar. The effect of yeast concentration, moisture content on the fermentation time and temperature were investigated in view of improving productivity. It was found that the volume was increased at maximum state when the fermentation was carried out at 35 $^{\circ}C$ with 0.1% yeast concentration 60% of moisture. The quality of Jeung-Pyun was most preferable in the condition of 0.1% wine yeast(Pasteur Red) for 8 hrs at 35$^{\circ}C$.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.1-7
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• 2004

Roads, like bikeways, parkways and walks, are to be just capable of supporting light traffic and traveling public, but they are required to be human friendly and environmental-oriented. Lately soil-solidifier mixture, a kind of soil-cement, has developed and has been applied to the recycling and environment-oriented pavement as the surfacing material. Soil-solidifier pavement structure has been designed by only experience. To design this pavement mechanically, it is necessary to find out basic engineering properties of soil-solidifier mixture. This study focuses on finding out mechanical characteristics of the mixture according to mixture proportions and aging. Test molds with various mixture proportions are made, and then unconfined strength tests are performed for test molds with aging of the mixture. As the result of this study, it is found that the strength of the mixture increases with amount of cement and that maximum strength is achieved at 6%$\sim$8% of the ratio of solidifier and water. The strength increase rapidly until 14 days, after then slowly. After 28 days the strength of the mixture approaches to the constant value. The heat of hydration during curing of the mixture is measured no significantly. It also shows that temperature characteristics of the mixture is similar to that of soil. Since this mixture is mixed with soil and is able to improve engineering problems in pavement due to temperature, this mixture is expected to use effectively in the environment-oriented pavement for light traffic.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.2
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• pp.77-84
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• 1992

This experiment was designed to gain information on factors affecting stubble death of orchardgrass (Dactylis glomerata L.) during the first rainy season. According to the experimental plan, the effects of sowing methods, drainages and cutting dates on the stubble carbohydrate content of orchardgrass, available soil moisture content of experimental plots, temperatures at the ground level and in the soil, and relative light intensity and humidity at the base of orchardgrass canopy were measured during the rainy season. The carbohydrate content of orchardgrass was sharply decreased to 2.9 % at 3rd day after cutting in the plots cut before rainy season and a gradural recovery was noted following the sharp reduction, but in the plots cut after rainy season, orchardgrass showed 5.5% of carbohydrate content before cutting and 3.0% at the 3rd day after cutting. The same pattern in both carbohydrate reduction and recovery was found between two cutting treatments. The available soil moisture content in the plots cut before rainy season was slightly higher than that in the plots cut after rainy season. But after the rainy season, the available soil moisture content in the plots cut after rainy season was higher than that in the plots cut before rainy season. Soil temperature at lOcm depths in the plots cut before rainy season was higher than that in the plots cut after rainy season. Daily maximum air temperature at the ground level in the plots cut before rainy season was higher than that in the plots cut after rainy season and changeable. Relative humidity at the ground level was below 70% in the plots cut before rainy season, but 75 to 90 % was observed in the plots cut after rainy season. Relative light intensity at the ground level in the plots cut before rainy season was much higher, recorded 50 to 90 %, than that in the plots cut after rainy season showing less than 10%. The results of this study suggest that the stubble death of orchardgrass during the rainy season is due to plant diseases influenced by a decrease of light penetration and increase of relative humidity at the base of the grass canopy.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.353-365
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• 2023

The effects of climate change on green infrastructure and environmental media remain uncertain and context-specific despite numerous climate projections globally. In this study, the extreme weather conditions in seven major cities in South Korea were characterized through statistical analysis of 20-year daily meteorological data extracted fro m the Korea Meteorological Administration (KMA). Additionally, the impacts of extreme weather on Nature-based Solutions (NbS) were determined through a comprehensive review. The results of the statistical analysis and comprehensive review revealed the studied cities are potentially vulnerable to varying extreme weather conditions, depending on geographic location, surface imperviousness, and local weather patterns. Temperature extremes were seen as potential threats to the resilience of NbS in Seoul, as both the highest maximum and lowest minimum temperatures were observed in the mentioned city. Moreover, extreme values for precipitation and maximum wind speed were observed in cities from the southern part of South Korea, particularly Busan, Ulsan, and Jeju. It was also found that extremely low temperatures induce the most impact on the resilience of NbS and environmental media. Extremely cold conditions were identified to reduce the pollutant removal efficiency of biochar, sand, gravel, and woodchip, as well as the nutrient uptake capabilities of constructed wetlands (CWs). In response to the negative impacts of extreme weather on the effectiveness of NbS, several adaptation strategies, such as the addition of shading and insulation systems, were also identified in this study. The results of this study are seen as beneficial to improving the resilience of NbS in South Korea and other locations with similar climate characteristics.