• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.561-567
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• 2018

In this study, the electrochemical characteristics of Silicon/Carbon anode materials were analyzed to improve the cycle stability of silicon as an anode materials of lithium ion battery. Porous silicon was prepared from TEOS by the $st{\ddot{o}}ber$ method and the magnesiothermic reduction method. Silicon/Carbon anode materials were synthesized by varying the mass ratio between porous silicon and pitch. Physical properties of the prepared Silicon/Carbon anode materials were analyzed by XRD and TGA. Also the electrochemical performances of Silicon/Carbon anode materials were investigated by constant current charge/discharge, rate performance, cyclic voltammetry and electrochemical impedance tests in the electrolyte of $LiPF_6$ dissolved in organic solvents (EC : DEC = 1 : 1 vol%). The Silicon/Carbon anode composite (silicon : carbon = 5 : 95 in weight) has better capacity (453 mAh/g) than those of other composition cells. The cycle performance has an excellent capacity retention from 2nd cycle to 30th cycle.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.424-428
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• 2003

This study was conducted to find out the optimum cultural method for hybrid seed production of Chalok 2. Higher seed yield was obtained when KW3 was used as a seed parent (female). KW7 was shown Higher barren stalk occurrence which caused significant seed yield reduction when it was used as a seed parent (female). The ratio of female (KW3) to male (KW7) rows with 4 to 1 had higher seed yield than that of 2:1 or 3:1. In case of using KW3 toy a seed parent, KW3 was susceptible to stem and ear rotting disease. The 35th day after silking was optimal period to harvest due to higher 100-grain weight, lower rotten grain, and higher germination rate.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.543-550
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• 2007

As an emerging materials in construction fields, FRP(fiber reinforced polymer) has been used in many area of civil engineering for its light weight and high strength. In this study we chose the 2nd Jindo-Bridge as a prototype, and evaluate effect of replacing steel components to FRP components through simplified 3D linear analysis. Static and modal analysis are done and the analysis results are compared with steel case analysis. From the static analysis results, the maximum stress of each component and maximum displacement of middle span are compared. Due to the reduction of deadload, the FRP structure causes less deflection than the original steel structure and from the reduced section (cable) analysis we confirmed the previous result. The occurrence wind velocity of flutter is compared by the frequency ratio.

• Analytical Science and Technology
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• v.9 no.3
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• pp.235-243
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• 1996

A carbon paste electrode were chemically modified using ${\alpha}$-cyclodextrin. Characteristics of chemically modified carbon paste electrodes were studied on the basis of the inclusion complex formation of ${\alpha}$-cyclodextrin and p-nitrophenol in solution. Cyclic voltammetry and differential pulse voltammetry were used to monitor the efficiency of the chemical modification. When the ${\alpha}$-cyclodextrin and carbon powder ratio of 2 : 1 in weight were used, the reduction peak current of p-nitrophenol was decreased almost completely, whereas those of o-nitrophenol and hydroquinone were not changed much. This result is due to the large difference in the inclusion complex formation constants of p-nitrophenol and the other probes with ${\alpha}$-cyclodextrin. Taking advantage of this difference, we can determine the concentration of o-nitrophenol even in the presence of p-nitrophenol.

• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.373-384
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• 1999

The shell structures with composite materials have the advantages in strength, corrosion resistance, and weight reduction. The objective of this study is to analyze anisotropic composite circular cylindrical shells with shear deformation theory. In applying numerical methods to solve differential equations of anisotropic shells, this paper use finite difference method. The accuracy of the numerical method can be improved by taking higher order of interval ${\Delta}$ to reduce error. This study compares the results of finite difference method with the results of ANSYS based on finite element method. Several numerical examples show the advantages of the stiffness increasement when the composite materials aroused. Therefore, it is expected that results of this study give various guides for change of the subtended angles, load cases, boundary conditions, and side-to-thickness ratio.

• Journal of Nutrition and Health
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• v.18 no.1
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• pp.29-35
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• 1985

This study was designed to evaluate the effects of tocopherol supplementation on serum $HDL_{2}$ and $HDL_{3}$ subfraction and lipoprotein pattern of young rabbits fed the different levels of dietary polyunsaturated fatty acids. White male rabbits with an average bo요 weight of 90kg were assigned into 4 groups : LP( Low PUFA) ; HP( High PUFA) ; LPT( Tocopheror added to LP), HPT(Tocopherol added to HP) by feeding safflower oil or coconut oil at loft( w/w )in addition to thew diet with or without tocopherol for 4 weeks. HDL-Chol and HDL subfractions were determined by polyanionic precipitation method, and the relative amount of lipoprotein by electrophoresis. Serum total cholesterol and TG wer slightly lowered in the group of high PUFA diet and its effect was more in the case of tocopherol supplemented. HDL-Chol level was reduced in the high PUFA diet with or without tocopherol, but overall, HDL-Chol level was not influenced by tocopherol addition and also no significant change in lipoprotein pattern when tocopherol added to the HP diet. $HDL_{2}$ level was increased in HPT group but not in LPT group when tocopherol was added to each HP and LP group, respectively. $HDL_{3}$ levels of both LP and HP groups were reduced with tocopherol supplement, but the reduction was less in the high PUFA groups so that $HDL_{2}$ : $HDL_{3}$ ratio of HP was rather close to that of LP, but it was increased when tocopherol supplemented to the HP diet. Therefore, high PUFA diet could improve the anti atherogenic factor when tocopherol supplemented.

• Journal of the Korean Wood Science and Technology
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• v.38 no.2
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• pp.124-134
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• 2010

This study was performed to evaluate the efficiency of using softwood as the sawdust medium for Lentinula edodes cultivation, effect of nutrient on the mycelial growth, spawning, the mushroom yield, and quality. The nitrogen nutrition significantly enhanced the mycelial growth of L. edodes. The glutamic acid in the L. leptolepis and P. koraiensis, and asparagine in the P. densiflora were appeared to slight increase in the mycelial growth. The vegetable oil showed very effective on the mycelial growth in the P. koraiensis sawdust medium. Carbon/nitrogen ratio of all the test was reduced after mycelial growth. The mycelial growth was exclusively dependent on reduction of carbon. The mushroom yield (32.7%) of the P. densiflora sawdust medium (carbon source: 3% active carbon, nitrogen source: 0.4% asparagines) was the best in mushroom production of L. edodes, followed by the Q. variabilis sawdust (35.4%) of the control medium. The diameter of mushroom cap was obtained from the P. densiflora sawdust (carbon source: 3% sucrose, nitrogen source: 0.4% potassium nitrate) and P. koraiensis sawdust (carbon source: 3% sucrose, nitrogen source: 0.4% potassium nitrate), and the P. koraiensis sawdust (carbon source: 3% xylose, nitrogen source: 0.4% glutamic acid, supplement: 0.05% amino acid), with values 71.5 mm, 71.5 mm and 72.1 mm, respectively. In the polypropylene bag cultivation, the weight losses of the block medium gradually increased for 80 days in the dark (13.8~16.8%) and then became stable in the range of 20.7~25.8%.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.142-150
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• 2001

Automotive manufactures have taken more interests in tailored sheet metals for improving the rigidity, weight reduction, crash durability, and cost savings so that their application to auto-bodies has been increased. However, since the tailored sheet metals do not behave like un-welded sheet metals in press forming operations, the stamping engineers no longer rely only on conventional forming techniques. Futhermore, there is no clear understanding of the characteristics of welded metal which influence the overall press formability of tailored sheet metals. Recently, the computer simulations are prevailing for the evaluation of the formability. Unfortunately, the mechanical property of tailored sheet metal has to be quantitatively defined in the simulation. In this study, the analytical equations are formulated in order to find the mechanical properties of the welded metal in the tailored sheet metal welded by co$_2$laser. Based on force distribution assumption, the constitutive behavior of the welded metal is investigated using uniaxial tensile test results of base metals and tailored sheet metal. Then, the strength coefficient, work-hardening exponent, and plastic strain ratio of laser-welded metal are calculate from those of base metals and tailored sheet metal. In addition, the existence of weld defects in the welded metal is indirectly detected by examining the slop of strength coefficient of the welded metal.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.248-252
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• 1999

This study examined the effects of growth retardants and midsummer drainage on lodging-related characters in direct seeding rice culture on flooded paddy surfaces. Treatments included in this study were continuous flooding, two time midsummer drainages (TTD), and inabenfide or trinexapac-ethyl application after TTD. Culm length was reduced most by 11.4cm in trinexapac-ethyl treatment after TTD, followed by 4.1cm in inabenfide treatment after TTD compared to TTD treatment. A significant reduction in culm length occurred at the 3rd internode in inabenfide treatment applied at 40 days before heading (DBH), while trinexapac-ethyl application at 8 DBH reduced the 3rd>2nd>1st internode. The culm diameter of the 4th internode was increased by the application of trinexapac-ethyl following TTD compared to TTD treatment. Thickness of culm wall was significantly increased by trinexapac-ethyl but not by inabenfide applications. Lodging index was the highest in continuous flooding and the lowest in trinexapac-ethyl treatment after TTD. Subsequently, field lodging did not occur in plots treated by trinexapac-ethyl. Rice plants subjected to midsummer drainage or growth retardants showed higher ripened grain ratio and 1000-grain weight, resulting in higher rice yield. These results indicate that trinexapac-ethyl, which can be applied at the relatively later growth stage after proper judgement of lodging occurrence, could be a useful tool for reducing lodging in direct seeding rice culture on flooded paddy fields.

• Korean Journal of Human Ecology
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• v.22 no.1
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• pp.131-140
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• 2013

Eco-friendly and health-functional clothing is now becoming the target of the worldwide hot trends. The purpose of this study is to develop an eco-friendly textiles to decrease environmental pollution and to be harmless for human health by investigating how the natural chorangak liquid treatment affects the changes of mechanical properties and the hand of silk fabrics according to different treatment conditions. Treatment was varied with various temperatures ($85^{\circ}C$, $90^{\circ}C$, $95^{\circ}C$) for 90 seconds after degumming. The results were as follows: 1) The natural chorangak liquid is the most effective at the ratio of glacial acid 200ml with eggshell 20g minimizing the time limit and sludge reduction. Its treatment of silk fabrics is optimized at $90^{\circ}C$ for 90 seconds with 25% conc. after degumming when considering tenacity and elongation. 2) After the treatment, tenacity and elongation of specimen are increased compared with those of degummed silk fabrics. 3) After analyzing the effect of the treatment on the characteristic values of basic mechanical properties of silk fabrics, mechanical properties (tensile, bending, shearing, compression, surface) are overall improved. The properties of thickness and weight are increased as well. 4) Based on the clear analysis on effects of the treatment on the mechanical properties and the hand of silk fabrics, the level of THV was enhanced from good to excellent. Therefore, chorangak liquid can be utilized satisfactorily as a new finishing agent for developing eco-friendly textiles.