• Progress in Superconductivity and Cryogenics
• /
• v.14 no.4
• /
• pp.41-45
• /
• 2012

An HTS (high temperature superconducting) coil without insulation has been investigated since a metallic insulation was suggested in the mid-1980s. The advantage of an insulationless HTS pancake coil is that it is more stable than an insulated HTS pancake coil. This paper focuses on the various characteristics of the insulationless HTS pancake coil related with stability, especially under the external magnetic field. Because HTS pancake coil may be influenced by the external magnetic field in a real operational environment of electrical devices. First, charge-discharge test was performed for the characteristics evaluation of the insulationless HTS pancake coil as compared with insulated HTS pancake coil in liquid nitrogen at 77 K. Based on the experiment results, characteristics evaluation of the insulationless HTS pancake coil was implemented under the external magnetic field. In order to carry out the experiment, we have fabricated a cylindrical solenoid coil to apply the magnetic field. The various characteristics of the insulationless HTS pancake coil were evaluated for charge-discharge and over-current conditions. This paper proves that the insulationless HTS pancake coil is more stable than the insulated HTS pancake under the external magnetic field.

• Journal of Korean Society of Forest Science
• /
• v.88 no.4
• /
• pp.523-532
• /
• 1999

The studies were carried out to develop an urban forest aromatic bath in the idle space within city area for handicapped persons, patients and city workers, who having less chance to visit the natural forest aromatic bath. The environmental conditions were checked in the experimental double vinyl house where native and exotic aromatic woody and herbaceous plants were growing with minimum energy input in the periods of mid-winter and mid-summer. The growth and photoperiodic responses of the plants to the low and high temperatures were observed during winter and summer respectively. The most of herbaceous plants in the double vinyl house with the controlled minimum night temperature of $-2^{\circ}C$ had no winter injury but did not grow and started the growth in April. The exotic herbs such as Catnip faassen's(Nepeta x faassenia) and Lemon bergamot(Monarda citriodora) grew better in the longer photoperiodic conditions. The growth rates of Abies koreana, Thuja koraiensis and Pinus sylvestriformis in the early spring were affected mainly by the night minimum temperature and less affected by the photoperiodic conditions during winter. The native aromatic herbs such as Robdosia japonica, Molsa punctulata, Agastache rugosa and Codonopsis lanceolata showed stimulatory growth at the 16 hours day-length in case of the high temperature vinyl hose. The height and root collar diameter growth of pine seedlings were inhibited in maxim temperatures over $40^{\circ}C$ during summer.

• Korean Journal of Ecology and Environment
• /
• v.36 no.4 s.105
• /
• pp.420-426
• /
• 2003

During a three-year study (2000-2002), dramatic changes in the phytoplankton biomass and high transparency were repeatedly observed during mid-spring in the lower part of the Nakdong River. Rotifers (Brachionus, Keratella, Polyarthra) , sharply increased toward the middle and end of spring. As hydrologic retention time increased (to near 20 days) and water temperature increased from $10^{\circ}C$ to > $20^{\circ}C$ toward the end of spring, small cladocerans noticeably increased. Once phytoplankton biomass passed their peak stage in the mid-spring, a short period (one or two weeks) of relatively low phytoplankton biomass and high Secchi transparencies occurred. Grazing by the zooplankton was highest in spring, thus, it seems that high grazing activities of zooplankton grazing regulated phytoplankton dynamics in the river. The results indicate that the role of zooplankton grazing in controlling the phytoplankton biomass becomes more important during the spring when river water is relatively stagnant.

• 한국해양학회지
• /
• v.14 no.2
• /
• pp.54-60
• /
• 1979

Distribution of drifting larvae of scallop, Patinopecten yessoensis, was studied in the Yeong-il Bay in 1973, 1978, and 1979. The range of the bottom water temperature was 10∼19$^{\circ}C$ and that of salinity was 32.58∼34.55 . The larvae appeared from early March to mid-July with maximum abundance from mid- April to early June. Drifting period of larvae is about a month, and then the larvae begin to settle on the substratum. In the Yeong-il Bay setting period was from early Arpil to late June with maximum abundance from mid-May to eary June. The highest density of drifting larvae was found in the vicinity of Dae-dong-bae(Station H) among the observed stations, and the density was much higher in 1979 than in the other years observed. Vertical distribution of the larvae is closely related to the depth of the water column. High density of the larvae was observed in the bottom layer. The larvae were most abundant in the bottom-most layer, and in the place where the water depth is 24m, 42% appeared in the 4m layer from the bottom, and 80% in the 8m layer from the bottom, and where the water depth is 16m, 50% in the bottom-most 4m, and 90% in the layer up to 8m.

• Asian Journal of Turfgrass Science
• /
• v.22 no.2
• /
• pp.133-140
• /
• 2008

The growth of root and shoot normally decline dramatically in mid-summer of Korea, moreover the cool-season turfgrassgrass eventually wither to death over $30^{\circ}C$. The increase of air temperature also drives the heat of soil, that makes stress on root system. The heat stress affects physiological mechanisms of hormonal unbalance that stimulates shoot growth, photosynthesis, and transpiration. To solve those problems, many studies have been carried out to control soil moisture and OM content to decrease soil temperature for dissolving the growth retardant by heat stress. This study initiated to analyze the change of soil temperature with soil moisture, and the effect of soil depth and moisture content on heat transmit and thermal changes on turfgrass growth(productivity, green color, and damage by dryness and high temperature). Kentucky bluegrass plots prepared with 25%, 33%, 40% soil moisture treatments. Soil temperature was measured every five min. with four thermo-sensors at 12 and 2 cm soil depth. The most acceptable growth showed at 33% soil moisture, but the worst result showed at 40%. The soil moisture seriously affected on the growth of Kentucky bluegrass, however the quality of turfgrass may acceptable if we can control soil moisture down to 33% when the flooding season of monsoon.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.294-298
• /
• 2008

Snow cover is a potential water resource for later spring and summer seasons as well as a thermal mirror with high reflectivity causing decreases of surface air temperature during cold winter seasons. In this study, current and future changes in Northern Hemisphere snow extent and their potential linkages with atmospheric circulation are examined. The NOAA AVHRR visible snow extent (1967-2006) data as well as observational (NCEP-DOE 1979-2006) and modeled (GFDL 2.1 2081-2100) pressure and surface air temperature data are used. Analyses of observational data demonstrate that the snow extent in meteorological spring (March to April) and summer (June to August) has significantly decreased since the late 1980s. The offset of snow seasons (the timing of snow melt in spring) have also significantly advanced particularly in Europe, East Asia, and northwestern North America. Analyses of pressure fields reveal that the spatial patterns of the earlier snow melt are associated with changes in atmospheric circulation such as the Arctic Oscillation (AO). In the positive winter AO years, multiple positive pressure departure cores in the upper troposphere (200hPa) are observed over the mid-latitude regions from March to mid-April, while a negative pressure departure core (70hPa) prevails over the Arctic Ocean. The reversed anomaly patterns related to later snow melt occur in negative winter AO years. The comparison between current and future thermal spring onsets suggest that snow melt patterns will intensify with larger greenhouse gas emissions, indicating earlier hydrological spring onset.

• Toxicological Research
• /
• v.11 no.1
• /
• pp.37-42
• /
• 1995

Effect of cadmium on the early amphibian development was analyzed through FETAX (Frog Embryo Teratogenesis Assay: Xenopus). Embryos manifested concentration-dependent mortality and realformations; shortage of anterior-posterior axis gut realformation, ocular anomalies, bent notochord, misshapen dorsal fin, and derreal blisters. The treatment with 1.5ppm cadmium solution caused 100% mortality and concentration of lppm did not kill the embryos that caused 100% anomaly. The teratogenic index (TI = LC50 /EC50) was 2.8 indicating that $CdCl_2$ is teratogenic for Xenopus laevis. Embryos that were pulsetreated with at early to late blastula stage (St. 3-9) and mid to late blastula stage (St. 6-10) showed relatively strong resistance to cadmium, but the embryos treated at gastrula stage (St. 10-13) showed high mortality. And the embryos treated at tailbud stage (after St. 25) showed highest mortality of any other early stages. Effects of temperature were studied through pulse- treatment during gastrula stage at $20^{\circ}C$ and $30^{\circ}C$. The embryos treated with 7.5ppm at $30^{\circ}C$ and 15ppm at $20^{\circ}C$ caused 100% mortality respectively, indicating that higher temperature had more severe toxic effect. One of the most peculiar effect of cadmium at gastrulation was distortion of the tail. The probable cause of toxic effect of Cd was discussed.

• Atmosphere
• /
• v.23 no.4
• /
• pp.401-412
• /
• 2013

East Asia experienced extremely cold weather in January 2011, while the previous December and the following February had normal winter temperature. In this study National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data are used to investigate the characteristic features observed in the meteorological fields such as temperature, sea-level pressure, geopotential height, and wind during this winter period. In January the planetary-wave pattern is dominated by stationary-wave form in the mid-to-high latitude region, while transient waves are significant in the previous month. To understand the planetary-wave features quantitatively, harmonic analyses have been done for the 500-hPa geopotential height field. In the climatological-mean geopotential heights the wave numbers 1, 2, and 3 are dominant during the whole winter. In January 2011 the waves of number 1, 2, and 3 are dominant and stationary as in the climatological-mean field. In December 2010 and February 2011, however, the waves of number 4, 5, and 6 play a major role and show a transient pattern. In addition to the distinctive features in each month the planetary-wave patterns dependent on the latitude are also discussed.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.34 no.2
• /
• pp.170-176
• /
• 1989

Experiments were conducted to find out varietal responses of low temperature; 14$^{\circ}C$ and 12$^{\circ}C$. at rooting stage of the recommended rice varieties in middle boreal area. The varieties showed discoloration resistance are Sobaegbyeo. Baegambyeo. Hwaseongbyeo Chiagbyeo. Dobongbyeo and Daeseongbyeo. varieties wi th no root growing under low temperature are Taebaegbyeo. Samgangbyeo. Baegyangbyeo. Pungsanbyeo and Sangpungbyeo. The varieties showed dark green leaf color and high rooting rate are Sangpungbyeo. Chiagbyeo. Odaebyeo. Unbongbyeo. Dobongbyeo. Hwaseongbyeo. Sobaegbyeo and Daeseongbyeo. light-green of leaf color and low rate of rooting are Taebaegbyeo. Baegyangbyeo. Samgangbyeo and Nongbaegbyeo.

• Journal of Aquaculture
• /
• v.13 no.4
• /
• pp.339-351
• /
• 2000

Optimal environmental conditions, that sustained fastest growth, lowest mortality and abnormality of the scallop Patinopecten yessoensis, were identified from field experiments undertaken at Chumunjin during 1991-1998. Temperature within the water column 10~30 m depth ranged between 5 and 23$^{\circ}C$; high temperature and daily fluctuation resulted in growth retardation and heavy mortality of the scallop. Optimal salinity range was between 31.5 and 34.5%0 and water transparency 6.0 and 18.1 m, which was significantly affected by phytoplankton density. Chlorophyll concentration ranged between 0.04 and 3.51 f.lgfL. Low temperature and high chlorophyll concentration appear to support faster growth of the scallop. Optimal periods of transplantation for intermediate culture were between mid July and early November: cultured under high density during July-August as a first step and under low density during mid September through early November as a second step. Optimal stocking density in square net cage (<35${\times}$35 em) for intermediate culture was 30-40 individuals per cage for main culture using lantern net and 80 -100 individuals of the size of 1.5 ~ 3.0 em shell height per cage for sowing culture. During the intermediate culture, the highest growth was realized, when the cage was held at water depth between 10 and 15 m. Water depth below 25 m, however, was best to avoid mass mortality during the periods of abnormally high water temperature and high variation of water temperature. The daily growth rate during the intermediate culture was between 0.019~0.381 mm; low in January and February but high in March and April. It is suggested that the main culture is commenced before June under low stocking density to avoid the possibility of mass mortality during summer by high water temperature.