• The Korean Journal of Food And Nutrition
• /
• v.22 no.3
• /
• pp.377-386
• /
• 2009

The principal objective of this study was to evaluate the influence of temperature and salt concentration on the physicochemical properties of salted Chinese cabbage. Salted Chinese cabbage samples were prepared with various concentrations of salt(4, 5, 6 and 7%), and were stored for 10 days at three temperatures(8, 14, and $25^{\circ}C$). The salting ratio of Chinese cabbage evidenced a decreasing trend regardless of the salting temperature and salt concentration, and their decrement appeared relatively high as the salting temperature increased. The period required to achieve a critical salting ratio(85%) decreased with increases in the salt concentration at $25^{\circ}C$, and a similar trend was observed at lower temperatures(8 and $14^{\circ}C$). The salinity of all samples evidenced an increasing trend during the salting period, and at $25^{\circ}C$, in particular, a continuous increment was observed. At salt concentrations of 4%, the critical salinity(2.2%) was not achieved regardless of the temperature and salting period. The pH of salted Chinese cabbage achieved critical pH in 3 days at a salting temperature of $25^{\circ}C$, but the critical pH 5.5 of samples at 8 and $14^{\circ}C$ appeared after a long period of approximately 4 to 10 days. The average hardness values of salted Chinese cabbage at a salting ratio of 85% were approximately 1.49 MPa, 1.87 MPa, and 1.97 MPa, respectively, at three temperatures($25^{\circ}C$, $14^{\circ}C$, and $8^{\circ}C$). The initial reducing sugar content of cabbage juice was 11.8 mg/$m{\ell}$, and this value decreased substantially to 3 to 5 mg/$m{\ell}$ on day 1.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.11a
• /
• pp.179-180
• /
• 2015

In this study, the experimental study on Insulation performance of insulated forms utilizing NT frame heat insulation at low Temperature. For this study, placing insulated TEGO film plywood based form between two constant temperature and humidity chamber that maintaining 10℃, decrease temperature of one chamber to -10℃ and -20℃. Each of steps, maintaining period of temperature was 1 hour. After placing the insulated form, measure temperature of outside if insulated form. As a result of experiment, temperature difference of Fumed Silica Vacuum insulation was lowest.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.05a
• /
• pp.57-58
• /
• 2015

In this study, the experimental study on Thermal Performance of Insulated Forms with Different Insulating Methods at Low Temperature. For this study, placing insulated plywood based form between two constant temperature chamber that maintaining 10℃, decrease temperature of one chamber to -10℃ and -20℃. Each of steps, maintaining period of temperature was 1 hour. After placing the form, measure temperature of opposite side of the insulated form. As a result of experiment, temperature difference of rigid urethane was lowest.

• Atmosphere
• /
• v.22 no.2
• /
• pp.209-219
• /
• 2012

Extreme heavy snowfall episodes have been investigated in case of accumulated snowfall amount larger than 50 cm during the past ten years, in order to understand the association of low-level stability with heavy snowfall in the Yeongdong region. In general, the selected 4 events have similar synoptic setting such as the Siberian High extended to East Sea along with the Low passing by the southern Korean Peninsula, eventually inducing easterly in the Yeongdong region. Specifically moist-adiabatically neutral layer has been observed during the heavy snowfall period, which was easily identified using vertical profiles of equivalent potential temperature observed at Sokcho, whereas convective unstable layer has been formed over the East sea due to relatively warm sea surface temperature (SST) about $8{\sim}10^{\circ}C$ and lower temperature around 1~2 km above the surface, obtained from RDAPS. Difference of equivalent potential temperature between 850 hPa and surface as well as difference between air and sea temperatures altogether gradually increased before the snowfall period. Instability-induced moisture supply to the atmosphere from the East sea, being cooled and saturated by the upper cold surge, would make low-level ice cloud, and eventually move inland by the easterly flow. Heavy snowfall will be enhanced in association with low-level convergence by surface friction and upslope wind against Taebaek mountains. This study emphasizes the importance of low level stability in the Yeongdong region using the radiosonde sounding and RDAPS data, which should quantitatively be examined through numerical model as well as heat and moisture supply from the ocean.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.3
• /
• pp.42-49
• /
• 2003

In this paper, we provide the results of polishing temperature distribution by way of infrared ray measurement system as well as polishing resistance, which can be interpreted as tribological aspects of CMP, using force measurement system. The results include the trend of polishing temperature, its distribution profile and temperature change during polishing. The results indicate that temperature affects greatly to the removal rate. Polishing temperature increases gradually and reaches steady state temperature and the period of temperature change occurs first tens of seconds. Furthermore, the friction force also varies as the same pattern with polishing temperature from high friction to low. These results suggest that the first period of the whole polishing time greatly affects the nonuniformity of removal rate.

• Journal of the Korean Geographical Society
• /
• v.50 no.1
• /
• pp.1-21
• /
• 2015

The present study aims to characterize the synoptic climatic patterns of winter extreme low temperature events occurred in different regions of Korea based on daily temperature data observed at 61 weather stations under the supervision of the Korea Meteorological Administation and NCEP/NCAR reanalysis I data for the recent 40 years (1973~2012) period. Analyses of daily maximum and minimum temperatures below 10th percentile thresholds show that high frequencies of winter extreme low temperature events appear across the entire regions of Korea or in either the western or eastern half region divided by major mountain ridges at the 2~7 dayintervals particularly in the first half of the winter period (before mid-January). Composite analyses of surface synoptic climatic data including sea level pressure and wind vector reveal that 13 regional types of winter extreme low temperature events in Korea are closely associated with the relative location and intensity of both the Siberian high pressure and the Aleutian low pressure systems as well as major mountain ridges. Investigations of mid-troposphere (500 hPa) synoptic climatic charts demonstrate that the blocking-like upper troposphere low pressure system advecting the cold air from the Arctic toward the Korean Peninsula may provide favorable synoptic conditions for the outbreaks of winter extreme low temperature events in Korea. These results indicate that the monitoring of synoptic scale climatic systems in East Asia including the Siberian high pressure system, the Aleutian low pressure system and upper level blocking system is critical to the improvement of the predictability of winter extreme low temperature events in Korea.

• Korean Journal of Ecology and Environment
• /
• v.38 no.spc
• /
• pp.22-26
• /
• 2005

Egg incubation periods of 14 species of plecoptera were examined at $10^{\circ}\;{\sim}\;11^{\circ}C$, $15^{\circ}\;{\sim}\;16^{\circ}C$, $20^{\circ}C$, and $23^{\circ}C$ under dark conditions. The total effective temperature (TET) was calculated by multiplying mean egg incubation days and water temperature of incubation periods. The relation between the TET and the incubation temperature was used to compare the life cycle of respective species. Perlodid species had higher TET values with a positive relation to incubation temperature than those of other species. Perlid species had low TET values in the 14 species with negative to variable relation, and Chloroperlid species showed variable to positive relations to incubation temperature. These results suggest that the relation between the TET and the water temperature reflected on their habitat of respective species.

• Membrane and Water Treatment
• /
• v.10 no.5
• /
• pp.331-338
• /
• 2019

This study aimed to investigate the membrane fouling and sludge characteristics in a pilot-scale submerged membrane bioreactor (MBR) operated under low temperature ($7^{\circ}C$). To elucidate the mechanisms of membrane fouling at low temperature, we studied the correlation between MBR performances and physicochemical properties of sludge including extracellular polymeric substance (EPS), relative hydrophobicity (RH) and floc size during long-term operation. The MBR was shown able to remove chemical oxygen demand (COD) stably and efficiently (>90 %) in the case of overgrowth of filamentous bacteria (bulking sludge) at low temperature. On the other hand, the occurrence of filamentous bulking greatly accelerated membrane fouling, as indicated by membrane filtration period of 14 days for filamentous bulking at $7^{\circ}C$, in comparison with that of 27 days for non-bulking sludge at $24^{\circ}C$ The overgrowth of filamentous bacteria resulting from low-temperature condition led to an increased release of EPS, higher RH, smaller floc size and lower fractal dimension of sludge. These factors accelerated the formation of compact cake layer on membrane surface in association with performance diminution in terms of increase in transmembrane pressure (TMP) of the membrane and thus the decrease in membrane permeability.

• The Plant Pathology Journal
• /
• v.26 no.1
• /
• pp.17-24
• /
• 2010

A logistic model for describing combined effects of both temperature and wetness period on appressorium formation was developed using laboratory data on percent appressorium formation of Colletotrichum acutatum. In addition, the possible use of the logistic model for forecasting infection risks was also evaluated as compared with a first-order linear model. A simplified equilibrium model for enzymatic reactions was applied to obtain a temperature function for asymptote parameter (A) of logistic model. For the position (B) and the rate (k) parameters, a reciprocal model was used to calculate the respective temperature functions. The nonlinear logistic model described successfully the response of appressorium formation to the combined effects of temperature and wetness period. Especially the temperature function for asymptote parameter A reflected the response of upper limit of appressorium formation to temperature, which showed the typical temperature response of enzymatic reactions in the cells. By having both temperature and wetness period as independent variables, the nonlinear logistic model can be used to determine the length of wetness periods required for certain levels of appressorium formation under different temperature conditions. The infection model derived from the nonlinear logistic model can be used to calculate infection risks using hourly temperature and wetness period data monitored by automated weather stations in the fields. Compared with the nonlinear infection model, the linear infection model always predicted a shorter wetness period for appressorium formation, and resulted in significantly under- and over-estimation of response at low and high temperatures, respectively.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.15 no.2
• /
• pp.106-111
• /
• 1995

This study was planned to identify the effect of low-temperature stress on Alcohol dehydrogenase(ADH) isozyme in sixteen varieties of Italian ryegrass using starch gel electrophoresis. The specific electrophoretic zymograms of each variety were observed by ADH isozyme. The results were summarized as follows: 1. All tested varieties displayed two band zone by ADH and R.f values were 0.63 and 0.60, respectively. 2. There were four band type for ADH isozyme of 16 varieties classified with ADH isozyme dyeing intensity. According to dyeing intensity 7, 2, 1 and 6 varieties belong to banding type I,II,III and IV, respectively(Fig.2-A, B). 3. The effect of short tern low-temperature stress induces ADH gene expresson in Italian ryegrass, which may reflect a fundmental shift in energy metabolism to ensure plant tissue survival during the low-temperature stress period.