• Journal of the Korean Electrochemical Society
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• v.25 no.3
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• pp.105-112
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• 2022

For the commercialization of all-solid-state batteries, it is essential to develop a solid electrolyte that can be operable at room temperature, and it is necessary to manufacture all-solid-state batteries by adopting materials with high ionic conductivity. Therefore, in order to increase the ionic conductivity of the existing oxide-based solid, Li₇La₃Zr₂O₁₂ (LLZO) doped with heterogeneous elements was used as a filler material (Al and Nb-LLZO). An electrolyte with garnet-type inorganic filler doped was prepared. The binary metal element and the polymer mixture of poly(ethylene oxide)/poly(propylene carbonate) (PEO/PPC) (1:1) are uniformly manufactured at a ratio of 1:2.4, The electrochemical performance was tested at room temperature and 60 ℃ to verify room temperature operability of the all-solid-state battery. The prepared composite electrolyte shows improved ionic conductivity derived from co-doping of the binary elements, and the PPC helps to improve the ionic conductivity, thereby increasing the capacity of all-solid-state batteries at room temperature as well as 60 ℃. It was confirmed that the capacity retention rate was improved.

• Journal of the Korean Electrochemical Society
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• v.17 no.1
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• pp.7-12
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• 2014

There is increasing demand on the reducing the weight and the volume of the major components in lithium secondary battery to improve energy density. Separator not only provides pathway for lithium ion movement but also prevents direct contact between anode and cathode. Herein we fabricated polyethylene separator by varying biaxial stretching ratio to obtain membrane thickness of 16, 12, and $9{\mu}m$. Mechanical and thermal properties of the separator with different thickness were investigated. Also rate capability and charge-discharge cycle property up to 500 cycles were studied using coin type full-cell with $LiCoO_2$ and graphite as a cathode and an anode, respectively. All the cells using separator with different thickness demonstrated excellent capacity retention after 500cycles (around 80%). Considering the rate capability, cell using separator with thickness of $9{\mu}m$ showed best performance. Interestingly, separator thickness of $9{\mu}m$ was more resistant to heat contraction compared to that of $16{\mu}m$ separator.

• The Korean Journal of Pain
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• v.4 no.2
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• pp.127-132
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• 1991

Recently a non-electronic, disposable and portable infusor(Baxter infusor with patient control module, Baxter health care Co., Deerfield IL 60015 USA: BI $\bar{c}$ PCM) has been developed that will deliver both a continuous drug infusion as well as allow the patient to deliver extra doses of medication on a demand basis under predetermined limitation of analgesics. Patients may also not require as high analgesic dose rate to control pain when the acceptable and tolerable level of pain relief can be maintained by this device. From April l99l, we have used a total l93 units of BI $\bar{c}$ PCM. These units consisting of two components which one made by a balloon reservoir(capacity 65 ml, flow rate 0.5 ml/hr) to store medication and to regulate the pump power(490 torr), and another two PCMs to regulate additional analgesic administration by patients demand at intervals of 1S minutes and 60 minutes. The dose administered to the patient can be varied by changing the concentration of the infusate within the balloon reservoir. These devices were utilized for the pain control of 44 patients. These patients were divided into two groups. Twenty seven cases had cancer pain and 17 cases had non-cancer pain. The Touhy needle(No. l8 G.) tip was inserted into the epidural space and was used to guide the catheter to the spinal nerve level corresponding to the most painful area. The device was connected to the opposite site of the catheter tip and was filled with 60 ml of mixture solution such as 0.5% bupivacaine 15 ml, morphine HCl 10 mg, trazodone 10 ml, Tridol 3 ml and normal saline 31 ml were administed as the initial dose. When the initial dose was less effective, the next dose could be varied by increasing the concentration of bupivacaine, by adding more morphine (5~10 mg), and by reducing the volume of normal saline. Using these modules of drug self administration, we experienced the following: 1) Improvement of patient's self titration of analgesic requirement was provided. 2) The patients anxiety with pain recurrence resulting from delays in administering pain control medication was decreased significantly. 3) The working load accompanying with the single bolus injection as the usual method was reduced remarkably. 4) There was urinary retention in 5 cases and pruritus in 4 eases which developed as side effects but respiratory depression and vomiting was not encountered in a single case.

• Korean Journal of Environmental Agriculture
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• v.8 no.2
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• pp.142-147
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• 1989

In this report, we set up a simple device which enabled us to obtain data useful to estimate the relative capacity of thermal energy retention of greenhouse built with various plastic coverings. A box($20cm{\times}20cm{\times}30cm$) framed with flexiglass at the edges and covered with thin plastic films was made, in which were placed a thermostat-controlled nichrom wire heater and a thermal probe made of thermister to monitor temperature changes. A wheaston-bridge type transducer and a chart recorder were used to record the changes of temperature inside the box The data obtained by using the device showed that the relative rate of heat toss through plastic films with identical thickness decreased in the order of PE film>EVA film>PVC film and that IR additives such as fine silica gel improved the insulating power of plastic films. This observations are in well accord with general information, demostrating the feasibility of the device in usefulness for the purpose of screening of various commercial plastic coverings.

• Korean Journal of Materials Research
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• v.20 no.12
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• pp.669-675
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• 2010

One of the greatest challenges for our society is providing powerful electrochemical energy conversion and storage devices. Rechargeable lithium-ion batteries and fuel cells are among the most promising candidates in terms of energy and power density. As the starting material, $TiCl_4{\cdot}YCl_3$ solution and dispersing agent (HCP) were mixed and synthesized using ammonia as the precipitation agent, in order to prepare the nano size Y doped spherical $TiO_2$ precursor. Then, the $Li_4Ti_5O_{12}$ was synthesized using solid state reaction method through the stoichiometric mixture of Y doped spherical $TiO_2$ precursor and LiOH. The Ti mole increased the concentration of the spherical particle size due to the addition of HPC with a similar particle size distribution in a well in which $Li_4Ti_5O_{12}$ spherical particles could be obtained. The optimal synthesis conditions and the molar ratio of the Ti 0.05 mol reaction at $50^{\circ}C$ for 30 minutes and at $850^{\circ}C$ for 6 hours heat treatment time were optimized. $Li_4Ti_5O_{12}$ was prepared by the above conditions as a working electrode after generating the Coin cell; then, electrochemical properties were evaluated when the voltage range of 1.5V was flat, the initial capacity was 141 mAh/g, and cycle retention rate was 86%; also, redox reactions between 1.5 and 1.7V, which arose from the insertion and deintercalation of 0.005 mole of Y doping is not a case of doping because the C-rate characteristics were significantly better.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.173-179
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• 2020

Electric vehicles (EVs) using lithium secondary batteries (LIBs) with excellent power and long-term cycle performance are gaining interest as the successors of internal combustion engine (ICE) vehicles. However, there are few systematic researches for fast charging to satisfy customers' needs. In this study, we compare the degradation of LIB where its composition is LiNi_0.5Co_0.2Mn_0.3/Graphite with the constant current and constant power-charging method. The charging speed was set to 1C, 2C, 3C and 4C in the constant current mode and the value of constant power was calculated based on the energy at each charging speed. Therefore, by analyzing the battery degradation based on the same charging energy but different charging method; CP charging method can slow down the battery degradation at a high rate of 3C through the voltage curve, capacity retention and DC-IR. However, when the charging rate was increased by 4C or more, the deviation between the LIBs dominated the degradation than the charging method.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.596-601
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• 2001

This study was carried out to determine the effect of base carriers such as zeolite or vermiculite on change of concentration of polyoxyethylene laury ether[$C_{12}H_{25}O(C_{2}H_{4}O)_{3}H$, PLE] and on initial wetting of peat-vermiculite medium in the development of a soil wetting agent using the mixture of PLE and polyoxyethylene+polyppro-pyleneoxide tridecylether (1:1, w/w, CM-1). The concentration of PLE in the treatment of vermiculite was higher than that of zeolite during the period from 2 to 6 weeks. The cumulative concentration of PLE released in the treatment of vermiculite was about $2800mg{\cdot}L^{-1}$ and zeolite was about $2300mg{\cdot}L^{-1}$. The treatments of PLE+CM-1 with zeolite or vermiculite as a carrier were effective in initial water retention of root media having more than 510 mL of water per pot, where as those of $AquaGro^{G}$ and control had 490 mL and 400 mL of water per pot, respectively. In the evaporative water loss, the treatment of zeolite and $AquaGro^{G}$ were faster than that of control and vermiculite. The control treatment had the fastest water movement in and the highest volume of water infiltrating into root medium among all treatments. Increased application rate of PLE+CM-1 did not increase water retention capacity. The treatment of $0.6g{\cdot}L^{-1}$ had the highest evaporative water loss and that of $0.3g{\cdot}L^{-1}$ had the highest amount of water infiltrating into root media among all other treatments.

• Journal of Soil and Groundwater Environment
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• v.11 no.1
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• pp.65-76
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• 2006

This paper outlines the methodology of grid-based water balance for estimating the spatial distribution of recharge, which is applied to Woedo catchment in the northern area of the Jeju Island. The catchment is divided into grids and a daily water balance in each grid is computed for the period of 5 years. Daily rainfall data in each grid is interpolated from the data of 10 rainfall gauging stations. The spatial distributions of parameters such as SCS curve number, soil water retention capacity and crop coefficients are derived from GIS analyses of soil and land use characteristics. The SCS curve number is obtained by calibrating simulated runoffs with respect to the observed runoffs. The results show that the average annual rainfall increases from 1,665 mm/year to 3,382 mm/year in accordance with the topographic elevation, and the average annual recharge varies from 372 mm/year to 2,576 mm/year according to the average annual rainfall increases. Spatial variability of recharge is the highest among the water balance components such as rainfall, direct runoff, evaprotranspiration and recharge because the rate of runoff and evapotranspiration in the area with relatively low rainfall is higher than the other area.

• Korean Journal of Weed Science
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• v.11 no.1
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• pp.11-18
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• 1991

Seven formulations of oxyfluorfen selected from the previous studies(4. 5) were tesed to evaluate crop injury and herbicidal efficacy on two rice cultivars and several annual and perennial weeds in a greenhouse. Each formulation at two different rates was applied to rice transplanted with 8-, 22- and 32-day old seedlings and to direct-seeded rice. Among the formulations, Elvan, Bentonite B. Chitosan and Coal Slag gave lower injury than a control formulation, Sand-coated oxyluorfen, and they did not have a problem with excessive release if active ingredient at once. Especially, the formulations of Elvan, Chitosan and Bentonite B controlled annual weeds (Echinochloa crus-galli, Monochoria vaginalis, Cyperus difformis., and Scirpus juncoides) and perennial weeds (Sagittaria pygmaea, and Cyperus serotinus). The surface structure of the formulations indicate the different possibilities of releasing of oxyfluorfen by different cracking and hole sizes, namely retention capacity.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.490-500
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• 2004

Brown rice grains were coated by spraying aqueous protein solution extracted from rice bran using 10% ethanol, and dried at room temperature. Coating procedure was repeated 1-5 times to determine effect of repeated coating, Quality changes in coated brown rice grains were observed during 8 weeks storage. Most coated rice grains gave lower peroxide and acid values, which indicate antioxidative effects of coating. Lipase and lipoxygenase activities generally decreased in grains coated more than three times. Microscopic images of whole kernel and longitudinal section revealed cracking on all brown rice grains including control, and hydration rate constants were not significantly different among treated grains. Compared to non-coated brown rice grains, those coated more than three times, after 8 week storage, showed better quality retention observed in (meaning not clear) higher water-binding capacity, lower gel consistency decrease, less browning, and better textural properties in cooked rice, resulting in better sensory quality.