• Korean Journal of Remote Sensing
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• v.38 no.4
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• pp.355-364
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• 2022

In this study a tendency of abnormal sea surface temperature (SST) occurrence in the seas around South Korea is analyzed from daily SST data from satellite and 14 buoys from August 2020 to July 2021. As thresholds 28℃ and 4℃ are used to determine marine heatwaves(MHWs) and abnormal low water temperature (ALWT), respectively, because those values are adopted by the National Institute of Fisheries Science for the breaking news of abnormal temperature. In order to calculate frequency of abnormal SST occurrence spatially by using satellite SST, research area was divided into six areas of coast and three open seas. ALWT dominantly appeared over a wide area (7,745 km²) in Gyeonggi Bay for total 94 days and it was also confirmed from buoy temperature showing an occurrence number of 47 days. MHWs tended to be high in frequency in the coastal areas of Chungcheongdo and Jeollabukdo and the south coastal areas while in case of buoy temperature Jupo was the place of high frequency (32 days). This difference was supposed to be due to the low accuracy of satellite SST at the coasts. MHWs are also dominant in offshore waters around Korean Peninsula. Although detecting abnormal SST by using satellite SST has advantage of understanding occurrence from a spatial point of view, we also need to perform detection using buoys to increase detection accuracy along the coast.

• Journal of the Korean Chemical Society
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• v.40 no.12
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• pp.748-755
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• 1996

The effects of temperature on the conformational properties of poly(ethylene oxide) (PEO) in aqueous and aqueous urea solutions are reported. The values of intrinsic viscosity and Huggins coefficients for the PEO dissolved in water and urea/water mixtures (urea concentration 0.2, 1, and 2 M) were obtained using a viscometry method and discussed with respect to the change of water structure. At low temperatures (below 22 $^{\circ}C)$, the PEO-water interaction is favorable and the chain can be extended, whereas at higher temperatures (above 24 $^{\circ}C)$, it is less favorable and the chain can be contracted by a hydrophobic hydration, i.e., the PEO-water interaction becomes to be unfavorable with the increase in temperature. As the urea is added to the system, the PEO chain can be more extended and huged by the perturbation of the structured water originating from the unfavorable PEO-water interaction. The effect of temperature on the intrinsic viscosity values shows an Arrhenius behavior. The activation energies of the viscous flow were obtained and discussed.

• Journal of the Korean Ceramic Society
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• v.55 no.6
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• pp.590-596
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• 2018

To improve the injection behavior of brushite cement, dense ${\beta}-Ca_3(PO_4)_2$ (${\beta}-TCP$) granules were added to the starting material. The spherical ${\beta}-TCP$ granules prepared by spray-drying and subsequent sintering at $1000{\sim}1200^{\circ}C$ accounted for fractions of from 0.5 to 0.7 of the total ${\beta}-TCP$. The injection behavior was evaluated by measuring the injected mass divided by the loaded mass of paste in the syringe pump. The injected amount was increased with the increase in the fraction and sintering temperature of ${\beta}-TCP$ granules, except at $1200^{\circ}C$. The increase in the fraction of ${\beta}-TCP$ and its sintering temperature resulted in a decrease in the plastic limit, which is the volume of water required to liquefy the compact. The rest water could be utilized in the cement with the reduced plastic limit for improved injectability. The amounts of rest water assigned for powdery phase were estimated, and correlated with the injectability of paste.

• Journal of Korea Water Resources Association
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• v.33 no.4
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• pp.495-503
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• 2000

In this study the average air temperature in April at Taegu city is analyzed and forecasted by applying an intervention model of stochastic analysis. As it is unavailable to get the data of carbon dioxide emission from a city in Korea, the points of intervention have been decided from the analysis of the data observed to be the years of 1947 and 1970. As a result of the study the mean temperature of April in Taegu city is shown to increase for a long time in the future and will also remain 0.015$^{\circ}C$/year even after 70 years from now. Even though the air temperature changes in the future will vary depending on the future exhaustion of carbon dioxide, a significant increase of air temperature cannot be avoided if the emission of carbon dioxide continues at today's level.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.65-67
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• 2003

Flounder (Paralichthys olivaceus) fish goes through metamorphosis in the larvae phase. In this phase, it secretes much thyroid hormone to control metamorphosis. Sharp change in the environment and nutrition deficiency may cause stress in the metamorphosis phase. It leads to interfering with the development of thyroid hormone and finally inhibits the normal growth of larvae. In this study, the correlation between the change in thyroid hormones and the albinism appearance was examined by growing them with low temperature ($13^{\circ}C$) stress over the premetamorphosis stages (stage $D\~F$) of flounder metamorphosis. Albinism rate was $15\%$ in the low temperature group and $25\%$ in the control goup. $T_{4}\;and\;T_{3}$ of the control group tended to increase from stage F as larvae grew. $T_{4}$ increased 2 times compared to the control group as 72 ng/g at stage H, the increasing phae of water temperature, in the low temperature group. $T_{3}$ increased 8 times compared to the control group as 2.9 ng/g at stage E, the decreasing phase of water temperature. Therefore, it is judged that the albinism appearance of flouner is caused from the sharp increase in $T_{3}$ by the inappropriate secretion of thyroid hormone.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.12a
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• pp.103-114
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• 2005

Chlorine disinfection has been used in drinking water supply to disinfect the water-borne microbial disease which may cause to serious human disease. As Chlorination is still the least costly, relatively easy to use, chlorination is the primary means to disinfect portable water supplies and control bacterial growth in the distribution system. However, chlorine also reacts with natural organic matter (NOM), which presents in nearly all water sources, and then produces disinfection by-product (DBps), which may have adverse health effects. Although the existent DBPs have been reported in drinking water supplies, it is not feasible to predict the levels of the various DBPs due to the complex chemistry reaction involved. The objectives of this study were to investigate seasonal variation of DBPs formation and difference of DBPs concentration in the plant to tap water. The average concentration of THMs was 20.04 ${\mu}g/{\ell}$, HAAs 8-15 ${\mu}g/{\ell}$, HANs 2-4.5 ${\mu}g/{\ell}$ respectively. Distant variation of DBPs formation is that THMs concentration increase by 17% at 2 km point from the plant and by 28% at 7 km and HAAs, HANs also increase each by 16%, 32%, at 2 km from the plant and 35%, 56%, at 7 km. DBPs increase in water supply pipe continually. The seasonal occurrence of DBPs is that in May and August DBPs concentration is very high then in March, in May DBPs concentration is highest. The temperature is main factor of DBPs formation, precursor also. Precursor which was accumulated for winter flowed into the raw water by flooding in spring and summer and produced DBPs. Therefore for the supply of secure drinking water, it is required to protect precursor of flowing into raw water and to add to BCAA and DBAA to drinking water standards.

• Korean Journal of Poultry Science
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• v.22 no.3
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• pp.133-144
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• 1995

One metabolism trial(Experiment I) and another respiration trial(Experiment II) were conducted to investigate the effects of dietary fiber supplementation(20% wheat bran) on the water balance, blood acid-base balance, body temperature, and metabolic rate of heat-stressed adult roosters. In Experiment I, twenty 20-wk-old SCWL roosters(BW 1.6 kg) were randomly alloted to 4 treatments with 5 birds per treatment and one per replicate. The 4 treatments were consisted of two temperature(21~22˚C vs. 34~35˚C) and two dietary fiber treatment(0% and 20% wheat bran), making Experiment I a 2x2 factorial. After 4 d of preliminary period, birds we subjected to 3-d collection period. Sixteen 20-wk-old SCWL roosters(BW 1.6 kg) were employed Experiment H, with two temperature(21~22˚C vs. 34~35˚C) and two wheat bran levels(0% and 20%). Brids were housed in individual metabolism cages under normal temperature(21~22˚C), at fed one of the experimental diet. After 4 d of preliminary period, a respiration trial with open-circuit gravimetric respiratory apparatus was carried out for each bird for 6 h, one by one, normal(20~21˚C) and hot(34~35˚C) temperatures. The ANOVA test and comparisons among treatment means were done at 5% probability level for both experiments. Results obtained from Experiment I and, II were summarized as follows, 1.The amounts of DM intake and excretion were significantly(P<.05) decreased by heat stress. The DM intake was not affected by the addition of 20% wheat bran, however, the amount of DM excretion was significantly increased by the high fiber diet. Thus, the DM metabolizability decreased significantly by the addition of 20% wheat bran. 2. The heat-stressed roosters increased the water intake and excreta moisture content significantly. Although not significant, the water intake tended to increase in roosters fed the 20% wheat bran diet. 3. The amounts of total water input and evaporative water loss were increased significantly by heat stress, and the addition of 20% wheat bran did not exert any influence on the total water input and evaporative water loss. However, roosters fed the 20% wheat bran diet increased the excreta water output significantly. 4. Neither the heat stress nor the dietary fiber did affect the blood pH, pCO2, and HCO$_3$- significantly. 5. The body temperature increased significantly by the heat stress. However, the high fiber deit failed to decrease the body temperature. 6. The heat-stressed roosters decreased the 02 consumption and C0$_2$ production, and increased the evaporative water loss significantly. However, the high fiber diet did not exert any infulence in this regard. It appears that the beneficial effect, if any, of high fibrous diet during heat stress episode may be due to the increased heat loss through the enhanced excreta water.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.11-21
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• 2017

The paper presents experimental results of self-healing effects of OPC-GGBFS paste with cracked and uncracked specimens. The self-healing of cracked specimens is processes of crack closing with re-hydration of unhydrated in crack surface. The OPC paste with GGBFS replacement ratios of 0%, 10%, 20% and 30% were prepared having a constant water-binder ratios of 0.5. The OPC-GGBFS paste specimens immersed in tap-water and sea-water. The temperature of tap and sea-water was $5^{\circ}C$, $15^{\circ}C$ and $25^{\circ}C$. The cracked specimens after deterioration were immersed for 60 days. The relationship between self-healing effect and age-effect was calculate based upon the experimental results. The self-healing effect was measured in ultrasonic pulse velocity (UPV) before and after loading. When the relative change rate of UPV is increases with the increase in GGBFS replacement ratios. Moreover, the self-healing effect is increased with the temperature of tap-water is increase. But the cracked specimens immersed in sea-water was unclear effects of different temperature. Furemore, most of the healing for OPC-GGBFS specimens immersed in tap-water and sea-water occurred during the first 30 days. The self-healing effect until 30 days is higher than that the age-effect. After 30 days, self-effect and age-effect was largely decreases. SEM/EDS analysis of crack on the surface of the specimens in tap-water were covered with aragonite, and sea-water were covered with brucite.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.1
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• pp.9-18
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• 2011

The spalling phenomenon occurs in high-strength concrete when several factors such as sharp temperature increase, high water content, low water/cement ratio and local stress concentration in material combine in the concrete material. On the basis of the factors, the preventing methods from the spalling are known as reduction of temperature increase, preventing of concrete fragmentation and fast drying of internal moisture. In this study, the reduction of temperature increase was proposed as the most effective spalling-preventing method among the spalling-preventing methods. Engineered cementitious composite for fireproof and repair materials was developed in order to protect the new and existing RC structures form exterior deterioration factors such as fire, cloride ion, etc. This study was carried out to estimate the fire-resisting performance of high strength concrete slab or tunnel lining by repaired engineered cementitious composite (ECC) or fiber reinforcement cemetitious composite (FRCC) under fire temperature curve. and them we will descrike the result of HIDA tunnel in Japan.

• Journal of the Korean Society of Food Science and Nutrition
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• v.16 no.2
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• pp.69-74
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• 1987

The effects of soaking temperature on hydration and cooking rates of Chunmabyeo(Japonica) and Kayabyeo(J/Indica) rice were investigated. Water uptake and volume increase rates of milled rice were increased as a function of soaking temperature$(4^{\circ}C{\sim}30^{\circ}C)$. The rate of volume increase of milled rice was greater than that of weight increase, which was more pronounced at low soaking temperature. The soaking of milled rice prior to cooking had a definite effect on the degree of gelatinization. The soaked milled rice was more easily gelatinized than unseated one. The water uptake rate, volume increase rate, degree of gelatinization and cooking rate of milled rice were faster in Kayabyeo than Chunmabyeo.