• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.131-136
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• 2008

Silica- or titania-filled poly (vinylidene fluoride-co-hexafluoropropylene)-based polymer electrolytes were prepared by phase inversion technique using N-methyl-2-pyrrolidone and dimethyl acetamide as solvent and water as non-solvent. The polymer electrolytes were adopted to the lithium metal polymer battery using high-capacity cathode $Li[Ni_{0.15}Co_{0.10}Li_{0.20}Mn_{0.55}]O_2$ and lithium metal anode. After the repeated charge-discharge test for the cell, it was proved that the cell adopting the polymer electrolyte based on the phase-inversion membrane containing 40~50 wt% silica showed the highest discharge capacity (180 mAh/g) until 80th cycle and then abrupt capacity fade was just followed. The capacity fade might be due to the deposition of lithium dendrite on the polymer electrolyte, in which the capacity retention was no longer sustainable.

• Korean Journal of Materials Research
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• v.10 no.11
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• pp.760-769
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• 2000

Mechanical properties of HSLA cast steels alloyed with 0.15% Nb, Ti or V were tested as variations of austenizing temperatures and tempering times. The test results are as follows. The hardness of HSLA cast steels austenized for 2hrs at 115$0^{\circ}C$ was shown the highest value regardless of alloying elements and then decreased as the temperature decreased below 110$0^{\circ}C$. The hardness of HSLA cast steels with 0.15% Ti austenized for 2 hrs at $1150^{\circ}C$ was higher than that of any other HSLA cast steels, and chich was mainly attributed to the relatively high amount of bainite, and solid solution hardening. Charpy impact energy of HSLA cast steels was comparable to the C-Mn cast steel except HSLA cast steels with 0.15% Ti austenized at 115$0^{\circ}C$. The hardness of HSLA cast steels austenized for 2 hrs at $1150^{\circ}C$ increased at a ten-minute tempering, and after that, the hardness kept almost sililar level except HSLA cast steels with 0.15% V.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.250-256
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• 2005

Coating appearance is the most important problem in automotive industry. To increase the coating appearance quality, the corrosion resistance and the coating adhesion on metal substrates must be basically solved. The phosphating film made by the pretreatment of metal substrate is important factor to increase the coating adhesion. During the cathodic electrodeposition, the pH at the cathode surface increases up to about 12. In such a highly alkaline condition, the dissolution of metal substrate and phosphate film occurs. These phenomena result in the decrease of the bonding strength between the phosphating film and the substrate. Generally, the structure of zinc phosphating film is hopeite or phosphophyllite. It has been known that the phosphophyllite film contains better corrosion resistance and paint adhesion for hot water immersion test because of the decrease of dissolving amount of both metal substrate and phosphating film during the cathodic electrodeposition. It is found that the addition of Ni and Mn composition increase P-ratio and then can improve the paint adhesion on metal surface and the corrosion resistance.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.141-146
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• 2007

A new class of LC-resonator for micro magnetic sensor device was invented and fabricated by means of MEMS technique. The micro LC-resonator consists of a solenoidal micro-inductor with a bundle of soft magnetic microwire cores and a capacitor connected in parallel to the micro-inductor. The core magnetic material is a tiny glass coated $Co_{83.2}B_{3.3}Si_{5.9}Mn_{7.6}$ microwire fabricated by a glasscoated melt spinning technique. The core materials were annealed at various temperatures $150^{\circ}C,\;200^{\circ}C\;,250^{\circ}C\;,$ and $300^{\circ}C$ for 1 hour in a vacuum to improve soft magnetic properties. The solenoidal micro-inductors fabricated by MEMS technique were $500{\sim}1,000{\mu}m$ in length with $10{\sim}20$ turns. The changes of inductance as a function of external magnetic field in micro-inductors with properly annealed microwire cores were varied as much as 370%. Since the permeability of ultra soft magnetic microwire is changing rapidly as a function of external magnetic field. The inductance ratio as well as magnetoimpedance ratio (MIR) in a LC-resonator was varied drastically as a function of external magnetic field. The MIR curves can be tuned very precisely to obtain maximum sensitivity. A prototype magnetic sensor device consisting of the developed microinductors with a multivibrator circuit was test successfully.

• Economic and Environmental Geology
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• v.54 no.4
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• pp.483-494
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• 2021

This study was carried out to investigate the feasibility of reducing clean cover soil using a flooded column test in arsenic-contaminated farmland reclamation of abandoned coal mine area that shows generally low or about worrisome level (25 mg/kg) of Korea soil environment conservation act unlike abandoned metal mine. During the monitoring period of soil solution for 4 months, chemical properties (pH, EC, ORP, Fe, Mn, Ca, and As) in each layer (clean soil cover and contaminated/stabilized soil) showed different variation. This result revealed that soil solution in stabilized or contaminated soil rarely affected that in cover soil. Whether stabilized or not, arsenic concentrations in the rice roots grown in the soil covers with the thickness of 40 cm decreased by 98% in compared with the that grown in the control soil. In case of the soil covers with 20 cm thickness on stabilized soil, it decreased by 80% and this was 22 percentage point higher than when the soil of lower layer was not stabilized. Thus, reducing clean cover soil could be possible in contaminated farmland soil reclamation if appropriate stabilization of contaminated soil is carried.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.100-105
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• 2021

Recently, all-solid-state batteries have attracted much attention to improve safety of rechargeable lithium batteries, but the solid-state batteries of conductive ceramics or solid polymer electrolytes show poor electrochemical properties because of several problems such as high interfacial resistance and undesired reactions. To solve the problems of the reported all-solid-state batteries, a hybrid solid electrolyte is suggested, in this study, NASICON-type nanoparticle Li_1.5Al_0.5Ti_1.5P₃O₁₂ (LATP) conductive ceramic, PVdF-HFP, and a carbonate-based liquid electrolyte were composited to prepare a quasi-solid electrolyte. The hybrid solid electrolyte has a high voltage stability of 5.6 V and shows an suppress effect of lithium dendrite growth in the stripping-plating test. The LiNi_0.83Co_0.11Mn_0.06O₂ (NCM811)-based battery with the hybrid solid electrolyte exhibits a high discharge capacity of 241.5 mAh/g at a high charge-cut-off voltage of 4.8V and stable electrochemical reaction. The NCM811-based battery also shows 139.4 mAh/g discharge capacity without short circuit or explosion at 90℃. Therefore, the LATP-based hybrid solid electrolyte can be an effective solution to improve the safety and electrochemical properties of rechargeable lithium batteries.

• Journal of Korean Society of Forest Science
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• v.111 no.3
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• pp.418-427
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• 2022

Our aim was to evaluate the quality of pine seeds after long-term storage and to analyze the correlation between germination and physiological characteristics. Therefore, we investigated the germination and physiological characteristics of seeds stored for different periods and storage temperatures. Pine seeds lost little viability and vigor after 12 years of storage at 4℃; it is even possible to prolong the storage period at -18℃. The deterioration process operating through long-term storage was characterized by a loss of seed vigor before a loss in seed viability. Electrical conductivity of the seed leachate was significantly higher in seeds that completely lost their viability, and was also found to be significantly correlated with the germination percentage, T50, mean germination time, and germination speed. Among the minerals leaked to the leachate, K had the highest concentration, followed by Na, Ca, Cu, Mg, and Fe, while Mn and Zn were not detected. Concentrations of K, Ca, Cu, Mg, and Fe in the leachate differed significantly by treatment, and in the cases of K, Ca, Cu, Na, and Mg, we observed large differences in the leachate between the seeds that were collected in 2003 and those collected in other years.. Germination percentage was significantly negatively correlated to the concentrations of Ca, Cu, K, Mg, and Na. The coefficient of uniformity of germination was significantly negatively correlated to Cu concentration. The other germination characteristics were not significantly correlated with the mineral concentration. Therefore, the mineral concentrations of pine seed leachate were not reliable indicators of seed deterioration when the differences in quality between seed lots were small. However, electrical conductivity could be an indicator of seed viability and vigor of pine seeds under long-term storage.

• Journal of Food Hygiene and Safety
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• v.33 no.3
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• pp.207-213
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• 2018

This study aimed to evaluate the genotoxicity of Litsea japonica fruit-hexane extract (LJF-HE). In order to examine the genotoxicity, we carried out bacterial reverse mutation assay, chromosome aberration assay, and a micronucleus induction (MN) test according to the OECD and the Korea Ministry of Food and Drug Safety (MFDS) toxicity test guidelines. In the bacterial reverse mutation assay, no significant increase in revertant colonies, nor bacterial toxicity, was observed in the LJF-HE treatment group, regardless of the absence or presence of metabolic activation by the S9 mixture. However, in the positive control group, revertant colony counts were shown to be more than twice that of the negative control group. The chromosome aberration test showed that the repetition rate of abnormal chromosome aberration was less than 5%, regardless of the treatment time, and with or without the S9 mixture. No significant change was observed when (p < 0.05) compared with the negative control group. The micronucleated polychromatic erythrocytes (MNPCE) repetition rate of the polychromatic erythrocytes (PCE) showed no significant changes when compared with the negative control group (p < 0.05). The PCE portion of total erythrocytes also showed no significant changes (p < 0.05). These results showed that LJF-HE had no significant genotoxic effects.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.95-95
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• 2022

Maize is one of the world's three largest crops and has a long cultivation history, and is an important crop used for various purposes such as food, feed, and industrial raw materials. Recently, the agricultural environment is changing, in which the limit of cultivation of crops is shifted to the north due to the rise in temperature due to climate change. This study was conducted in experimental field of Suwon in 2022 by setting a seeding period earlier than the sowing time to establish the North Korean agricultural climatic zone and meteorological conditions. The test cultivars were silage cultivars, Kwangpyeongok and Dacheongok. As a priming test method, it was used to directly plant seeds in the field through immersion using 4mM zinc (Zn) and 2.5mM manganese (Mn), which are trace elements for seeds. The planting season was early on March 15th, April 1st, and April 15th. The number of days from sowing to silk stage of the two cultivars sown on March 15, April 1, and April 15 was 107, 93, and 85 days for Kwangpyeongok and 109, 95, and 87 days for Dacheongok, respectively. The seed priming test did not show any difference from the control group in the growth survey up to the middle stage of growth. In another test, low-temperature recovery was confirmed through nitrogen (2-5%) foliar fertilization after 3 days, 5 days, and 7 days in refrigeration (0 degrees), a selective low temperature treatment for com in the third leaf stage. As a result of this study, it was confirmed that the low-temperature damaged com treated at 0℃ showed the same growth as that of the untreated com through nitrogen foliar fertilization. These results suggest that urea foliar fertilization for low-temperature damage reduction of corn for silage in high-latitude climates will be helpful. In addition, through the results of the study, additional studies are needed on the recovery mechanism and field application through urea foliar fertilization.

• Journal of Oral Medicine and Pain
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• v.33 no.1
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• pp.85-95
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• 2008

The purpose of this study was to evaluate the effects of oral habits on the muscles of mastication and facial expression by means of two parameters: muscle stiffness and elasticity. 10 healthy, fully-dentate male subjects in their twenties were selected for this study; all had normal Class I occlusal relationships. Muscle stiffness and elasticity were measured with a tactile sensor(Venustron, Axiom Co., JAPAN) while subjects were asked to relax and perform various parafunctional activities such unilateral clenching(biting the bite force recorder with a force of 50kg on each subject's preferred side), jaw thrusting and lip bracing. The following muscles were examined: temporalis anterior(Ta), masseter(Mm), frontalis(Fr), inferior orbicularis oculi(OOci), zygomaticus major(Zm), superior and inferior orbularis oris(OOrs and OOri) and mentalis(Mn). Paired t-test, Correlation Coefficients, ANOVA and Multiple Comparison t-tests were used for statistical analysis. Unilateral clenching was highly correlated with bilateral stiffness and elasticity of all the muscles tested. Mm was affected by all three oral habits; Ta was affected by unilateral clenching(p<0.05); Zm was affected by unilateral clenching and OOrs, OOri and Mn were most affected by lip bracing(p<0.05). This study indicates that not only the masticatory muscles but also the muscles of facial expression, mainly circumoral muscles, can be significantly influenced by parafunctional activities such as unilateral clenching and lip bracing.