• Composites Research
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• v.35 no.5
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• pp.309-316
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• 2022

The demand for cold-resistant cable material is increasing due to the rapid increase in the development of devices that operate in a low temperature environment. Cold tolerance of a thermoplastic polymer largely depends on the type and content of about 20 or more additives used to make the polymer. The phenomenon of polymer hardening at low temperature can be classified into hardening by simple temperature effect, embrittlement at the glass transition temperature, and hardening by crystallization of polymers that tend to crystallize. In this study, a thermoplastic polymer having a low glass transition temperature, a flame retardant, and an additive were mixed to evaluate the mechanical properties of a thermoplastic polymer composite material for electric wires. It has been confirmed that mechanical properties and processability are determined depending on the additives and compatibilizers added, and this study is considered to be useful as basic data for optimization to meet the performance requirements of wires developed for low-temperature use.

• Journal of Powder Materials
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• v.30 no.3
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• pp.249-254
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• 2023

The influence of MgO addition on the densification and microstructure of alumina (Al₂O₃) was studied. Compacted alumina specimens were manufactured using ball-milling and one-directional pressing followed by sintering at temperatures below 1700℃. Relative density, shrinkage, hardness, and microstructure were investigated using analytical tools such as FE-SEM, EDS, and XRD. When the MgO was added up to 5.0 wt% and sintered at 1500℃ and 1600℃, the relative density exhibited an average value of 97% or more at both temperatures. The maximum density of 99.2% was with the addition of 0.5 wt% MgO at 1500℃. Meanwhile, the specimens showed significantly lower density values when sintered at 1400℃ than at 1500℃ and 1600℃ owing to the relatively low sintering temperature. The hardness and shrinkage data also showed a similar trend in the change in density, implying that the addition of approximately 0.5 wt% MgO can promote the densification of Al₂O₃. Studying the microstructure confirmed the uniformity of the sintered alumina. These results can be used as basic compositional data for the development of MgO-containing alumina as high-dielectric insulators.

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.197-204
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• 1998

This study was conducted to determine the activity of ALS, content of endogenous free amino acids and fatty acids affected by herbicide mixture of cyhalofop-butyl, pyribenzoxim and pyrazosulfuron-ethyl. $I_{50}$ values (concentration required for 50% inhibition of ALS activity) of pyribenzoxim herbicide on the activity of ALS in Echinochloa crus-galli and Cyperus serotinus in vitro were recorded at 4${\times}$100 nM and 5${\times}$10 nM, respectively, while $I_{50}$ values of pyrazosulfuron against E crus-galli and C. serotinus were 4.5${\times}$10 nM and 4${\times}$10 nM, respectively, and the mixture of two herbicides showed additive effect on ALS activity at the low application rate, and independent effect at the high application rates of two herbicides. The inhibition rates of the three herbicides mixture treatment on the three branch-chain amino acids such as valine, leucine and isoleucine were 74.6%, 66.6% and 57.9% in C. serotinus and 36.6% 51.1% and 48.1% in E. crus-galli, respectively. A little bit higher inhibitory effect on the three branch-chain amino acids in C. serotinus and E. crus-galli seedlings was observed in two herbicide mixture of pyribenzoxim with pyrazosulfuron than three herbicide mixture of cyhalofop with pyribenzoxim and pyrazosulfuron. The interaction among three herbicides showed non-antagonism on the amounts of endogenous free amino acids.

• Journal of the Korean Electrochemical Society
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• v.23 no.2
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• pp.47-55
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• 2020

Highly loaded LiCoO₂ positive electrodes are prepared to construct high-energy density lithium-ion batteries, their electrochemical performances are evaluated. For the standard electrode, a loading of about 2.2 mAh/㎠ is used, and for a high-loading electrode, an electrode is manufactured with a loading level of about 4.4 mAh/㎠. The content of carbon black as electronic conducting additive, and the porosity of the electrode are configured differently to compare the effects of electron conduction and ionic conduction in the highly loaded LiCoO₂ electrode. It is expected that the electrochemical performance is improved as the amount of the carbon black increases, but the specific capacity of the LiCoO₂ electrode containing 7.5 weight% carbon black is rather reduced. When the conductive material is excessively provided, an increase of electrode thickness by the low content of the LiCoO₂ active material in the same loading level of the electrode is predicted as a cause of polarization growth. When the electrode porosity increases, the path of ionic transport can be extended, but the electron conduction within the electrode is disadvantageous because the contact between the active material and the carbon black particles decreases. As the electrode porosity is lowered through the sufficient calendaring of the electrode, the electrochemical performance is improved because of the better contact between particles in the electrode and the reduced electrode thickness. In the electrode design for the high-loading, it is very important to construct the path of electron conduction as well as the ion transfer and to reduce the electrode thickness.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.5
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• pp.606-612
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• 2006

Obtaining powder form of seaweed is essential for the use of seaweed as a food additive. The deterioration of seaweed caused by high temperatures during homogenization and powder processing is a serious problem and limits the use of seaweed as a food or pharmaceutical ingredient. Furthermore, many powder particles are not fluidized very well because of the interaction between particles. In order to solve this problem, sea tangle was hydrolyzed to a level of single cell detritus (SCD) by Vibrio sp., isolated from Batillus cornutus. with strong hydrolytic activity. The crude protein and amino acid contents of sea tangle SCD were higher than those of the powder, whereas the reverse was true for ash content. Sea tangle powder contained more mineral than its SCD, whereas total amino acid content was 5 times more in SCD than in power. The anticancer activities of sea tangle SCD and powder were 31.20 and 29.07%, respectively, with no significant difference (p<0.05), but about 15% higher than that of the control. The ACE inhibitory activity of the sea tangle powder, 39.31%, was higher than the 26.07% of the SCD. The antithrombin activity of the sea tangle powder, 55.3 seconds, was higher than the 34.5 seconds of the SCD. Moreover, there was no antioxidative and ischemic activities in both tile sea tangle powder and SCD.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.2
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• pp.261-269
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• 1997

The autoxidation of cholesterol and lipid was investigated in mackerel during its salting for 50 days. Furthermore, the effects of antioxidants such as ascorbic acid and BHA on their autoxidation were studied. The cholesterol of mackerel during salting was continuously decreased. Its content was quantified by 23.3mg/100g in salted control sample after 50 days and that is only about 33% of total cholesterol content in fresh mackerel. The addition of BHA in mackerel during salting inhibited cholesterol oxidation more effectively than ascorbic acid.7-Ketocholesterol, unique cholesterol oxidation products was detected in this experiment and malonaldehyde, one of lipid oxidation products, contineuosly increased in control sample all the salting days by the almost same pattern but in the additive samples of ascorbic acid or BHA by different patterns, respectively. BHA was more effective antioxidant against cholesterol and lipid autoxidation than ascorbic acid.

• Fisheries and Aquatic Sciences
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• v.17 no.2
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• pp.255-261
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• 2014

An 8-week feeding trial was conducted to investigate the effects of dietary taurine supplementation on the growth performance of juvenile rock bream, Oplegnathus fasciatus. Triplicate groups of 25 fish averaging $2.72{\pm}0.04$ g ($mean{\pm}SD$) were fed one of six experimental diets prepared by adding taurine at 0%, 0.25%, 0.5%, 1.0%, 1.5% and 3.0% (Control, $Tau_{0.25}$, $Tau_{0.5}$, $Tau_{1.0}$, $Tau_{1.5}$ and $Tau_{3.0}$, respectively). At the end of the feeding trial, the weight gain, specific growth rate and protein efficiency ratio of fish fed the $Tau_{0.5}$, $Tau_{1.0}$ and $Tau_{1.5}$ diets were significantly higher (P < 0.05) than those of fish fed the Control and $Tau_{0.25}$ diets. The feed efficiency of fish fed the $Tau_{0.5}$ diet was significantly higher than that of fish fed the Control, $Tau_{0.25}$ and $Tau_{3.0}$ diets. Fish fed the $Tau_{1.0}$ diet had higher whole-body crude protein content than fish fed the Control diet, while the crude lipid content of fish fed the $Tau_{1.5}$ and $Tau_{3.0}$ diets was significantly lower than that of fish fed the Control and $Tau_{0.25}$ diets. An ANOVA suggested that the optimum level of dietary taurine supplementation to improve growth and reduce the body lipid contents of juvenile rock bream, O. fasciatus, was 0.5%, while a broken line analysis of weight gain indicated a level of 0.62%.

• Journal of Food Hygiene and Safety
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• v.19 no.4
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• pp.203-208
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• 2004

The shells of Anadarac tegillarca granosa, Crassostrea gigas, Crassostrea nippona, and Patinopecten yessoensis were used for preparation of calcium carbonate with high purity. Calcium content in ash of shell was the highest $64.9\%$ in Anadarac tegillarca granosa ashed for 5 hr at $900^{\circ}C$, and followed as Patinopecten yessoensis $62.5\%$, Crassostrea gigas $62.4\%$, and Crassostrea nippona $61.5\%$. Whiteness of ash was the highest 81.6-85.8 in Patinopecten yessoensis shell. Calcium contents in calcium carbonates made with shells of Anadarac tegillarca granosa by using ammonium chloride process (ACP) and ammonium nitrate process (ANP) were higher $40.03-40.04\%$ than $39.92\%$ in Anadarac tegillarca granosa ash. Calcium content was the highest $40.04\%$ in pH adjusted calcium carbonate prepared by using ANP. Whiteness of calcium carbonate prepared by using ACP and ANP was the level of 101.0-101.5. Therefore, we estimated that the calcium carbonate made by using ACP and ANP could be used potentiality as a food additive for calcium supplement.

• Journal of the Korean Geotechnical Society
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• v.21 no.6
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• pp.41-52
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• 2005

Because the allowable current loading of buried electrical transmission cables is frequently limited by the maximum permissible temperature of the cable or of the surrounding ground, there is a need fur cable backfill materials that can maintain a low thermal resistivity even while subjected to high temperatures for prolonged periods. Temperatures greater than $50^{\circ}C\;to\;60^{\circ}C$ may lead to breakdown of cable insulation and thermal runaway if the surrounding backfill material is unable to dissipate the heat as rapidly as it is generated. This paper describes the results of studies aimed at the development of backfill material to reduce the thermal resistivity. A large number of different additive materials were tested to determine their applicability as a substitute material. Tests were carried out for Dongrim river sand, a relatively uniform sand of very high thermal resistivity, $50^{\circ}C-cm/watt\;at\;10\%$ water content, $260^{\circ}C-cnuwatt$ when dry, and Jinsan granite screenings, and D-2 (sand and granite screenings mixture), E-1 (rubble and granite screenings mixture), a well-graded materials with low thermal resistivity, about $35^{\circ}C-cm/watt$ when at 10 percent water content, $100^{\circ}C-cm/watt$ when dry. Based on this research, 3 types of backfill materials were suggested for improved materials with low thermal resistivity and the applicability was assessed through field tests.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.2
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• pp.308-312
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• 2010

Quality characteristics of apple vinegar by using agitated and static cultures without any additive were compared. pH was reduced with passage of acetic acid fermentation time. Total acidity of the agitated culture vinegar (A) was 6.08% at the 8 day according to the progress of fermentation and that of the static culture vinegar (B) recorded 5.20% at the 60 day of fermentation. There was no significant difference in sugar content of (A) and (B). L value was lower in (B) than (A) but a and b values were higher in (B) than (A). Organic acid content of (A) was high only in acetic acid but malic, citric and succinic acids appeared high in (B). As free sugar, fructose and glucose were observed in both of them. In sensory examination results, (B) showed the highest taste and overall preferences. From all of these results traditional static culture are expected to be used to make high-quality vinegar.