• Development and Reproduction
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• v.13 no.1
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• pp.35-41
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• 2009

In the present study, we investigated the effects of rearing condition during the winter period on artificial maturation and reproduction of cultured female eel, Anguilla japonica. The female eel was adapted by combination of environmental conditions (seawater/low temperature, $10^{\circ}C$; seawater/high temperature, $20^{\circ}C$; freshwater/low temperature, $10^{\circ}C$; freshwater/high temperature, $20^{\circ}C$) during 8 weeks of the winter period. Then, the female eel cultivated by different conditions during the winter were transferred to seawater at $20^{\circ}C$ for induction of artificial maturation by salmon pituitary extraction (SPE) injection. The results shown that gonadosomatic index (GSI) and plasma levels of estradiol-$17{\beta}$ (E2) were significantly higher in female eel were reared in seawater than in freshwater, and were the highest at eel adapted by seawater/low temperature. Also, reproduction coefficient were higher in seawater/low temperature than in the other groups. These results will provide valuable information for elevation of the artificial maturation and reproduction coefficient in the cultured female eel.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.366-371
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• 2011

The sea squirt Halocynthia roretzi is mainly cultured in Tongyeong, Southern coastal area of Korea. This study presents the physiological rates of respiration, excretion, feeding and assimilation efficiency of the sea squirt Halocynthia roretzi to analyze the SFG(scope for growth) and net growth efficiency, determined during 2007. Oxygen consumption and nitrogen excretion rates increased with a rise in temperature during the summer period whereas feeding rates decreased. The O:N ratio was high during winter(October to February). Assimilation efficiency showed an annual average of 75.4% during the experimental period, except during a period of elevated temperature in July to September(average $25^{\circ}C$). Net growth efficiency($K_2$) was 8.7 to 64.2% except for May to September, when temperature increased at the aquaculture farm. SFG was negative from May to September, reflecting high temperatures and low feeding rates during this period; its highest positive values occurred during winter.

• Journal of Biosystems Engineering
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• v.32 no.1 s.120
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• pp.20-29
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• 2007

Korean farmers have purchased agricultural dryer and low temperature storage system apart. In this study, the system was designed and constructed to investigate the practical application possibility of the air to air heat pump as drying and low temperature storage system for agricultural products with providing basic data. The performance and drying characteristics of the system evaluated by drying red pepper. The value of coefficient of performance of the system for heating was from 1.8 to 2.2 when ambient air temperature varied from 13$^{\circ}C$ to 23$^{\circ}C$. For operating the heat pump as dryer for drying red pepper by setting three drying air temperature of 50, 55 and 60$^{\circ}C$, specific moisture extraction rates meaning amount of energy consumption for removing moisture of 1kg from red pepper were 1.095, 1.017 and 1.094 kg$_{water}$/kWh, respectively. The drying period up to moisture ratio of 0.02 were 31, 26 and 21 hour, respectively. The lightness, redness, yellowness and chroma differences of red pepper dried by the heat pump dryer were lowered than those of red pepper dried by conventional heated air dryer except for yellowness difference at drying air temperature of 60$^{\circ}C$.

• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.545-553
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• 2016

The failure probabilities of the reactor pressure vessel (RPV) for low temperature over-pressurization (LTOP) and cool-down transients are calculated in this study. For the cool-down transient, a pressure-temperature limit curve is generated in accordance with Section XI, Appendix G of the American Society of Mechanical Engineers (ASME) code, from which safety margin factors are deliberately removed for the probabilistic fracture mechanics analysis. Then, sensitivity analyses are conducted to understand the effects of some input parameters. For the LTOP transient, the failure of the RPV mostly occurs during the period of the abrupt pressure rise. For the cool-down transient, the decrease of the fracture toughness with temperature and time plays a main role in RPV failure at the end of the cool-down process. As expected, the failure probability increases with increasing fluence, Cu and Ni contents, and initial reference temperature-nil ductility transition ($RT_{NDT}$). The effect of warm prestressing on the vessel failure probability for LTOP is not significant because most of the failures happen before the stress intensity factor reaches the peak value while its effect reduces the failure probability by more than one order of magnitude for the cool-down transient.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.2
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• pp.42-54
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• 2023

The population is concentrated in the metropolitan areas in Korea, and low-density residential areas are transforming into high density residential areas through redevelopment to meet this demand. However, large-scale redevelopment in a short period of time has a negative impact on the urban climate, such as generating a heat island effect due to the reduction of urban green areas. In this study, the change in surface temperature from 2013 to 2022 in the redevelpment areas of Godeok-dong and Dunchon-dong, Gangdong-gu, Seoul, was analyzed using Landsat 8 satellite images. In the Godeok-dong area, the difference in surface temperature was analyzed for the target redevelopment area, forest area, mixed forest and urban area, and low density residential area. In the Dunchon-dong area, the difference in surface temperature was analyzed for the target redevelopment area, forest area, and low density residential area. The difference in surface temperature was analyzed through multiple regression analysis conducted yearly over the three different stages in redevelopment period. The results from the multiple regression analysis show that in both areas, the land surface temperature of target redevelopment area was higher than that of the forest area and lower than low density residential area. It can be seen that these results occurred because the low-density residential area in Godeok-dong and Dunchon-dong had a lower green area ratio and a higher building-to-land ratio than the target redevelopment area. The results of this study suggest that even if low-density residential areas are transforming into high-density areas, adjusting the management of green areas and building-to-land ratio can contribute to lessen urban heat island effect.

• Journal of Life Science
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• v.12 no.5
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• pp.589-594
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• 2002

Changes in the content of volatile terpenoids were investigated with heat-treated carrot. As heat treatment temperature became higher, the amount of volatile terpenoids decreased significantly. According to heat-treatment period, the volatile terpenoids, a-pinene and total terpenoids, decreased drastically during the initial 30-minutes of heat treatment but the rate of decrease slowed down afterwards. When changes in the content of volatile terpenoids in carrot juice were investigated according to sterilization temperature and period, the content decreased quickly with higher sterilization temperature. According to sterilization period, the content of volatile terpenoids decreased drastically during the initial 20-minutes of sterilization but decreased gradually afterwards. The amount of total terpenoids decreased more when sterilization was done at 10$0^{\circ}C$ for 20 minutes compared to sterilization at 6$0^{\circ}C$ and 8$0^{\circ}C$ for 60 min. In order to reduce the amount of volatile terpenoids in carrot juice, sterilization at high temperature for a short period of time would be more effective compared with sterilization at low temperature for a long period of time.

• Korean Journal of Veterinary Research
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• v.45 no.2
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• pp.263-271
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• 2005

To compare the sedative effects using intermittent intravenous bolus injection with tiletamine-zolazepam (n = 5, TZ group), xylazine-ketamine (n = 5, XK group) and propofol (n = 5, PI group), we investigated the changes of hemodynamic (heart rate, arterial pressure), $SpO_2$, rectal temperature, respiratory rate and pain score during 60 minute sedation and 40 minute recovery period in beagle dogs. The value of rectal temperature was significantly higher in PI groups (p<0.05) during recovery period. The value of heart rate was significantly lower in XK group (p<0.05) during sedation. The changes of respiratory rate were similar tendency in all groups. The change of $SpO_2$ was stable during sedation and value was significantly higher in PI group (p<0.05) during recovery period. The value of systolic arterial pressure (SAP) was significantly lower in XK group (p<0.05) than PI group during sedation and recovery period. Low analgesic effect occurred in PI group. We concluded that intravenous anesthesia by intermittent bolus injection with propofol is useful in stabilizing rectal temperature, $SpO_2$ and hemodynamic during sedation and provide fast recovery, but have low analgesic effect.

• Environmental Engineering Research
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• v.25 no.4
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• pp.554-560
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• 2020

This study focuses on nitrification through a biological aerated filter (BAF) that is filled with a zeolite medium at low concentrations of ammonia. The zeolite medium consists of natural zeolite powder. The BAF is operated under two types of media, which are a ball-type zeolite medium and expanded poly propylene (EPP) medium. Nitrification occurred in the zeolite BAF (ZBAF) when the influent concentration of ammonia nitrogen was 3 mg L-1, but the BAF that was filled with an EPP medium did not experience nitrification. The ammonia nitrogen removal efficiency of ZBAF was 63.38% and the average nitrate nitrogen concentration was 1.746 mg/L. The ZBAF was tested again after a comparison experiment to treat pond water, and municipal wastewater mixed pond water. The ZBAF showed remarkable ammonia-nitrogen treatment at low concentration and low temperature. During this period, the average ammonia nitrogen removal efficiency was 64.56%. Especially, when water temperature decreased to 4.7℃, ammonia nitrogen removal efficiency remained 79%. On the other hand, the chemical-oxygen demand (COD) and phosphorus-removal trends were different. The COD and phosphorus did not show as efficient treatment as the ammonia-nitrogen treatment.

• The Plant Pathology Journal
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• v.17 no.2
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• pp.101-105
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• 2001

A disease survey on the carnation (Dianthus caryophyllus L.) wilt was conducted during the high temperature period (June through August) and the low temperature period (February through May) in 58 greenhouses of its major cultivation areas, including Pusan, Kimhae, and Changwon in Korea from 1998 to 1999. The disease incidence was averaged 5.4% and 11.9% in the low and high temperature periods, respectively. Severe damage was found in summer with high incidences of around 50% in some greenhouses. Close examination of the symptoms and isolation of the causal agent revealed that there was a new disease different from Fusarium wilt caused by Fusarium oxysporum f. sp. dianthi, which was determined as the stub dieback caused by F. was cetermined as the stub dieback caused by F. graminearum (teleomorph : Gibberella zeae). The stub dieback symptoms involved brown rot of stem that started usually from the portion of cutting without discoloration of inner vascular tissues. Seven out of 38 isolates from the wilted plants were identified as F. graminearum, while the others as F. oxysporum f. sp. dianthi. Mycological characteristics of the stub dieback pathogen including colony color, absence of microconidia, and the shape of macroconidia, were consistent with F. graminearum previously described. This is the first report of the carnation stub dieback in Korea.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.6
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• pp.76-86
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• 1994

Combustion of diesel engine depends on the mixing of air and evaporating fuel during ignition delay greatly. Variation of air-fuel mixing rate and ignition delay for engine operating condition causes difference of combustion, performance and exhaust emissions. This study is investigated in a turbocharged diesel engine of IDI swirl chamber type. In the results, As injection timing is advanced until $12.6^{\circ}$ BTC, ignition delay decreases. NOx concentration and smoke level in exhaust gas increases for advanced injection timing Ignition delay, combustion period, pressure rise rate and exhaust gas temperature are increased with increasing engine speed. And ignition delay at high load is more decreased than that at low load. Ignition delay and combustion period are decreased with increasing intake pressure. Power increases, temperature and CO, NOx concentration in exhaust gas decreases as intake pressure increases. With increasing load, ignition delay is decreased and combustion period, motoring pressure are increased.