• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.1
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• pp.49-60
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• 2004

Northern Gyeonggi Province(NGP), consisting of 3 counties, is the northernmost region in South Korea adjacent to the de-militarized zone with North Korea. To supplement insufficient spatial coverage of official climate data and climate atlases based on those data, high-resolution digital climate models(DCM) were prepared to support weather- related activities of residents in NGP Monthly climate data from 51 synoptic stations across both North and South Korea were collected for 1981-2000. A digital elevation model(DEM) for this region with 30m cell spacing was used with the climate data for spatially interpolating daily maximum and minimum temperatures, solar irradiance, and precipitation based on relevant topoclimatological models. For daily minimum temperature, a spatial interpolation scheme accommodating the potential influences of cold air accumulation and the temperature inversion was used. For daily maximum temperature estimation, a spatial interpolation model loaded with the overheating index was used. Daily solar irradiances over sloping surfaces were estimated from nearby synoptic station data weighted by potential relative radiation, which is the hourly sum of relative solar intensity. Precipitation was assumed to increase with the difference between virtual terrain elevation and the DEM multiplied by an observed rate. Validations were carried out by installing an observation network specifically for making comparisons with the spatially estimated temperature pattern. Freezing risk in January was estimated for major fruit tree species based on the DCMs under the recurrence intervals of 10, 30, and 100 years, respectively. Frost risks at bud-burst and blossom of tree flowers were also estimated for the same resolution as the DCMs.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.92-96
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• 2003

Effects of vitamin C on the properties of bread including number of yeast cells, volume of bread, specific loaf volume, and hardness and sensory characteristics were evaluated. Vitamin C was added at various amounts to frozen doughs made through sponge &dough method using sweet dough formula and quickly frozen at $-40^{\circ}C$. Doughs were stored for 4 weeks at $-20^{\circ}C$. Evaluations were done after frozen dough was thawed, fermented, and baked every week. The bread with 150 ppm vitamin C revealed higher yeast cell survival rate during freezing storage, and higher specific and bread volumes than other doughs. Hardness of bread increased with increasing amount of vitamin C added. Bread with 100 ppm vitamin C revealed the highest sensory score. Consequently, addition of 100 ppm vitamin C to bread dough resulted in the highest overall evaluation.

• Macromolecular Research
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• v.12 no.4
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• pp.367-373
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• 2004

We have developed a rigorous heat treatment method to improve the biocompatibility of chitosan as a tissue-engineered scaffold. The chitosan scaffold was prepared by the controlled freezing and lyophilizing method using dilute acetic acid and then it was heat-treated at 110$^{\circ}C$ in vacuo for 1-3 days. To explore changes in the physicochemical properties of the heat-treated scaffold, we analyzed the degree of deacetylation by colloid titration with poly(vinyl potassium sulfate) and the structural changes were analyzed by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffractometry (WAXD), and lysozyme susceptibility. The degree of deacetylation of chitosan scaffolds decreased significantly from 85 to 30% as the heat treatment time increased. FT-IR spectroscopic and WAXD data indicated the formation of amide bonds between the amino groups of chitosan and acetic acids carbonyl group, and of interchain hydrogen bonding between the carbonyl groups in the C-6 residues of chitosan and the N-acetyl groups. Our rigorous heat treatment method causes the scaffold to become more susceptible to lysozyme treatment. We performed further examinations of the changes in the biocompatibility of the chitosan scaffold after rigorous heat treatment by measuring the initial cell binding capacity and cell growth rate. Human dermal fibroblasts (HDFs) adhere and spread more effectively to the heat-treated chitosan than to the untreated sample. When the cell growth of the HDFs on the film or the scaffold was analyzed by an MTT assay, we found that rigorous heat treatment stimulated cell growth by 1.5∼1.95-fold relative to that of the untreated chitosan. We conclude that the rigorous dry heat treatment process increases the biocompatibility of the chitosan scaffold by decreasing the degree of deacetylation and by increasing cell attachment and growth.

• Korean Journal of Veterinary Service
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• v.30 no.3
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• pp.445-457
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• 2007

This report studied the individual number, their favorite habitat, and change pattern of family and group number in Cheolwon Basin, starting in the early Oct. 2004 until late March. 2005 to investigate the ecological features of the Red-crowned Crane and the White-naped Crane. The Cranes arrived Cheolwon Basin in mid-October until next mid-March, and passed the winter in mid-November until next late-February The most visiting number amounted to 550 individuals and, that period was the most frosting mid-January to mid-February. The White-naped Crane visited Cheolwon Basin in autumn, the early winter and spring. Approximately, the wintering-number is 550 individuals, also, the mid-March was the peak-period of arrival and, the number amounted to 2,162 individuals. The cranes chose the farming area around mountains as their wintering habitat and were less likely to choose the farming area around lake as habitat. The Red-crowned Crane and the White-naped Crane showed the different periodical pattern in familial and group numbers. In case of the crane, the familial pattern was stable, but varied in grouping number, and this pattern was similar to the variation of overall individual number. And, also, the most grouping number was shown in the most freezing period of wintering period. The White-naped Crane showed the similar pattern of the Red-crowned Crane that is, stable family number and varying group number, this pattern affected the total number of entire individuals. Grouping number increased in migration period. Parasite infection rate is G japonensis 35.0%, G vipio 38.7%.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.546-554
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• 1995

Vacuum cooling of crisphead lettuce by pilot-scale vacuum cooling apparatus, transportation under the conventional and cold-chain systems and distribution were carried out for its freshness prolongation and application of cold-chain system for fresh fruits and vegetables. Changes in temperatures of crisphead lettuce were also measured during transportation. $Q_{10}$ value for respiration rate of crisphead lettuce was $1.7{\sim}2.4$ and its initial freezing point was $-0.2^{\circ}C$. Cooling the vegetable to $0^{\circ}C$ was possible in less than 30 minutes by vacuum cooling. The shelf-life was extended by more than 90% by the combination of vacuum cooling and low temperature distribution.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.477-480
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• 2008

With an increase of power consumption due to industrial development, the generation of coal ash has been growing tremendously and, accordingly, environmental concern over its disposal and insufficiency in disposal sites have been raised as other issues to be considered. In order to examine the usability of coal ash as an aggregate for concrete, such fundamental information as slump, air contents, mechanical properties and durability of concrete has been secured by way of setting 10, 20 or 30 wt. % of fine aggregate alternative rate of ash and identifying its basic properties at each pond-ash contents. The results of the study indicate that slump and air content heavily depend on the site of generation, and this might greatly influence on the content of fine particles of the ash. It is also shown that its freezing and thawing resistance tends to be relatively lower than that of Plain, which requires comprehensive examination over next few years on the absorptiveness and properties of mixed water of the ash collected from each disposal site.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.189-197
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• 2007

Developed safety system which transfers danger information to rear cars for accident prevention when drivers detect a accident, a dropping or a freezing during driving on the high way. To prevent an accident, each vehicles mount OBU which is made up of a GPS unit and a transmitter-receiver and the trace of road is always renewed and saved in OBU per a regular past distance. When the driver see dangerous situation, transfer a danger pattern and a trace information by pressing button. All cars which receive information compare the received data with the original data. And then, only cars which are located at the rear in a regular distance respond and occur a warning. Performed a road test at the rate of $30{\sim}50$ kilometer a hour using two test cars which saved about 120meter's space between them were mounted OBU which had 447Mhz transceiver. As a result of the experiment, communication between test cars had no problem. Accordingly, it can use a safety driving device because driver can notice a danger situation and set themselves ready for it using this system in advance.

• Journal of Pharmaceutical Investigation
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• v.26 no.4
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• pp.299-308
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• 1996

In order to develop the controlled release of a drug from the suppsitories, in vitro drug release and in vivo absorption in rabbits were investigated. Various suppository forms with hollow cavities, into which drugs in the form of fine powder or solid dispersion system(SDS) could be placed, were utilized. The polyvinyl alcohol(PVA) hydrogel as a base, and propranolol HCl(PPH) as a model drug were employed. In vitro drug dissolution studies showed that the dissolved amounts(%) of PPH from PPH-methylcellulose(MC)-SDS and PPH-ethylcellulose(EC)-SDS reached 100% and 63% in 4.5-hours, respectively. In the relative strength test for PVA hydrogel, PVA hydrogel became harder and more rigid when the number of freezing-thawing cycles and the ratio of PVA 2000 were increased. In vitro drug release profile revealed that the release rate(%) of PPH from PPH-EC-SDS and PPH-MC-SDS hollow type suppositories were sustained. The release amount(%) of PPH from PPH-EC-SDS hollow type suppositories was not affected by storage time, but since the use of hydrophilic MC made PPH diffuse into the hydrogel after it absorbed the water of base, the various release patterns were appeared as the storage time went by. In vivo absorption experiments with rabbits showed that PPH-EC-SDS(PPH : EC=1:3) hollow type suppository delayed the absorption of PPH, significantly. The $C_{max}$, $AUC_{0{\rightarrow}8}$ and MRT of PPH powder hollow type suppository were $196.37{\pm}5.63\;ng/ml$, 1105.26 ng/ml/min and 8.66 min, respectively. The $C_{max}$, $AUC_{0{\rightarrow}8}$ and MRT of PPH-EC-SDS(PPH : EC=1:3) were $91.30{\pm]14.14\;ng/ml$, 554.69 ng/ml/min, 235.99 min, respectively.

• Journal of Embryo Transfer
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• v.11 no.2
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• pp.151-158
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• 1996

This study was carried out to investigate the effect of equilibration time, sucrose concentration and age of embryo on survival and developmental rates of bovine IVF expanding blastocysts frozen-thawed by direct transfer method. The bovine oocytes were collected from 2~5mm follicles, matured for 20~24hrs in 5% $CO_2$incubator and then fertilized with frozen-thawed semen. Expanding blastocysts at day 7, 8, 9, 10 and 11 after IVF were frozen in 1.8M ethylene glycol(EG). Survival and hatching rates of frozen-thawed IVF embryos were examined. The results were as follow ; Survival and hatching rate of TVF expanding blastocysts after 10, 20, 3Omin exposure in 1.8M EG were 100,0,90.9, 47.1, 85.0, 75.0 and 62.5% respectively. Survival rates of IVF expanding blastocysts frozen with 1.8M EG and various concentration(0, 0.25, 0.5, 1M) of sucrose were 73.3, 25. 0, 16.7, 9.1% respectively. Survival and hatching rates of IVF expanding blastocysts frozen-thawed according to age of embryo(Day 7, 8, 9,10, 11) were 86.1, 84.8, 79.3, 61.4, 51.3, 74.2, 76.9, 71.7, 63.0 and 65.0% respectively. In conclusion, the age of the embryo(Day 7, 8) is very important for the successful freezing of IVF bovine embryos and 1.8M ethylene glycol not containing sucrose may be effective cryoprotectant for direct transfer method.

• Journal of Embryo Transfer
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• v.24 no.4
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• pp.253-257
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• 2009

To enhance the embryo preservation technology and better application of embryo transfer technique to the field (dairy science or animal reproduction. etc.), we examined the viabilities of bovine embryos produced in vitro and in vivo after cryopreservation according to their developmental stage and thawing temperature. Bovine embryos from in vivo/vitro fertilization (Hanwoo) were examined at day 7, 8, and 9. Survival rates and total cell numbers of in vivo fertilized embryos were as follows: morulae 68.8% and $67\;{\pm}\;6.0$; blastocysts 80.5% and $120\;{\pm}\;10$; expanded blastocysts 77.4% and $138\;{\pm}\;9.7$, respectively. Rates of embryo development for blastocysts and expanded blastocysts after thawing were significantly higher than that of morula stage embryos (p<0.05). While survival rates of in vitro fertilized embryos according to developmental stage showed no significant difference among groups (morula 67.9%; blastocyst 74.3%; and expanded blastocyst 79.4%), total cell numbers were significantly lower than those of other groups (morula $64\;{\pm}\;5.9$; blastocyst $116\;{\pm}\;8.7$; and expanded blastocyst $135\;{\pm}\;9.1$) For the viability according to thawing temperature, survival rate was higher in $37^{\circ}C$.