• 한국전기화학회:학술대회논문집
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• 2004.06a
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• pp.281-286
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• 2004

[ $LiOH{\cdot}H^2O$ ]와 $Ni(OH)^2$를 기계적으로 혼합하여 고상법으로 $LiNiO^2$를 합성하고, $LiNiO^2$의 전기화학적 특성을 조사하였다. 기계적 혼합을 위해 SPEC mill을 사용하였으며, 1시간 동안 milling하여 공기 중 $450^{\circ}C$에서 5시간 동안 전처리한 후 $750^{\circ}C$에서 30시간 동안 산소를 흘려주면서 하소한 시료가 가장 좋은 전기화학적 특성을 나타내었다. $2.7\~4.15V$에서 0.1C로 충${\cdot}$방전시 초기방전용량은 그다지 높지 않았으나(145.8mAh/g) 좋은 싸이클 성능을 나타내었으며, $2.7\~4.2V$에서 0.1C로 충${\cdot}$방전시 높은 초기방전용량(164.7mAh/g)을 나타내었으나 싸비클 성능은 그리 좋지 않았는데, 이는 충${\cdot}$방전시 육방구조$(H^2)$에서 육방구조$(H^3)$로의 상전이가 영향을 주는 것으로 사료된다. 초기방전용량과 방전용량은 Cation mixing을 나타내는 $I^{003}/I^{104}$값보다 hexagonal ordering을 나타내는 R-factor에 더 의존하는 것으로 사료된다.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.601-607
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• 2015

The friction material for automobile is manufactured by mixing several composites to stop the running vehicles. Friction characteristics are changed significantly according to the relative amount of the base materials. However, difference of friction coefficient is sometimes measured at the test for the same friction material. Nevertheless, the study for solving these problems is insufficient. In this paper, the friction tests were carried out by changing the external environment and processing condition when the main ingredients are fixed and also evaluated how the friction coefficient changes. The variables are cooling air speed, humidity (Relative humidity and Absolute humidity), scorching time, soaking time and pad area. And it is analytically considered which environmental factor mainly affects the characteristic of friction coefficient variation by experiment. It is expected that the results from this study can be very useful as a database for development of the friction material.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1299-1300
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• 2007

In this study, low temperature sintering property of (1-x)$TiTe_{3}O_{8}-xMgTiO_{3}$ ceramics were investigated for LTCC application which enable to cofiring with Ag electrode. $TiTe_{3}O_{8}$ mixed with $MgTiO_3$ to improve the temperature property. In the X-ray diffraction patterns, the columbite structure of $TiTe_{3}O_{8}$ phase and ilmenite structure of $MgTiO_3$ phase were coexisted in all specimens. The bulk densities and dielectric constants were decreased with increasing of $MgTiO_3$. However, the quality factors were increased with $MgTiO_3$ addition. Also, TCRF was shifted to negative(-) direction. Microwave dielectric properties of (1-x)$TiTe_{3}O_{8}-xMgTiO_{3}$ ceramics had similar tendency with calculated value by the mixing rule. The dielectric constant, quality factor and TCRF of $05TiTe_{3}O_{8}-0.5MgTiO_{3}$ ceramics sintered at $830^{\circ}C$ for 3h. were 26.19, 43,290GHz and $-3.9ppm/^{\circ}C$, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.57-60
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• 2009

In ultra-high-strength concrete, autogenous shrinkage is larger than dry shrinkage due to the consume of a large amount of cement and cementitous material, and this is a factor deteriorating the quality of structures. Thus, we need a new technology for minimizing the shrinkage strain for ultra-high-strength concrete. So, this paper have prepared super-high-strength concrete with specified mixing design strength of over 150MPa and have evaluated a method of reducing autogenous shrinkage by utilizing expander and shrinkage-reducing agent. According to the results of this study, with regard to the change in length by autogenous shrinkage, an expansion effect was observed until the age of seven days. The expansion effect was higher when the contents of the expander material were higher. In addition, ultra-high-strength concrete showed a shrinkage rate that slowed down with time, and the effect of the addition of expander material on compressive strength was insignificant. That is shown that required more database to be accumulated through experimental research for the shrinkage strain of members.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.1 s.119
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• pp.1-7
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• 2007

Internal fibrillation of pulp fiber is an important factor affecting paper properties. Internal fibrillation of pulp fiber is usually introduced with several kinds of modifications of fiber by the mechanical treatment such as refining, high shear and/or high consistency mixing, etc. Unfortunately there are no standardized methods that can characterize the extent of internal fibrillation and its contribution on the paper properties. The purpose of this study is to try and find the potential methods that can characterize the internal fibrillation of pulp fiber quantitatively. Softwood bleached kraft pulp was treated with Hobart mixer to introduce the internal fibrillation without the significant fiber damage and external fibrillation. The extent of internal fibrillation was increased with the increase of mechanical treatment consistency. Several fiber properties were measured to find the potential means that could characterize and quantity the internal fibrillation. Laminated area could not be used as a means for quantifying the internal fibrillation because of the effect of swelling and the different internal fibrillation behavior at different mechanical treatment consistency. Micro and macro internal fibrillation models were proposed for describing the different behavior for the mechanical treatment at low and high consistencies of pulp. The Internal fibrillation showed good correlation with swelling of fiber wall. This trend was confirmed through the measurement of wall thickness and/or cross section area of fiber. Therefore the internal fibrillation possibly can be described as the indices indicating the change of wall thickness and/or cross section area.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.457-464
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• 2006

Controlled auto ignition (CAI) combustion, also known as HCCI (homogeneous charge compression ignition), offers the potential to simultaneously improve fuel economy and reduce emission. CAI-combustion was achieved in a single cylinder gasoline DI engine, with a cylinder running in a CAI mode. Standard components were used the camshafts which had been modified in order to restrict the gas exchange process. The effects of air-fuel ratio, residual EGR rate and injection timing such as early injection and late injection on the attainable CAI combustion region were investigated. The effect that injection timings on factor such as start of combustion, combustion duration and heat release rate was also investigated. From results early injection caused the mixture to ignite earlier and burn more quickly due to the exothermic reaction during the recompression and gave rise to good mixing of the fuel-air.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.3 s.120
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• pp.274-281
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• 2007

Road traffic noise is not produced by any one factor rather it occurs as a composition of various factors. Its occurrence is made by running engine noise, tire frictional, and exhaust noise etc. The quality of the noise depends on the size of the vehicles, rotation and engine speed, vehicle load, package state of the road and incline etc. The occurrence of any noise level of heavy trucks appears louder than smaller vehicles and the noise levels produced differs according to speed and load etc between similar size vehicles. Other factors such as traffic density, average speed, mixing rate of heavy vehicles, and the distance between vehicles also generate road traffic noise. In this paper we examine 2, 4, and 6-lane roads in Jeonju. Consequently, this study examines the means used to measure road traffic noise. It was found that when there is a large traffic density and the average velocity is below 70 km/h, the noise level could receive a relative proper value by the current measuring means. But in the case of night-time, it was found that the current measuring method is inapposite.

• Korean journal of food and cookery science
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• v.32 no.3
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• pp.279-289
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• 2016

Purpose: This study was to determine the optimal composite recipe of rice cookie with 3 concentrations of Spergularia Marina L. Griseb, sugar and grape seed oil, using central composite design (CCD). Methods: The mixing condition of rice cookie was optimized by subjecting it to sensory evaluation and mechanical and physicochemical analysis using response surface methodology (RSM). Results: The results of mechanical and physicochemical analysis showed significant values for lightness, redness, yellowness, hardness, spread factor, loss rate, leavening rate, density, pH, moisture, sweetness and saltiness (p<0.05), and the results of sensory evaluation showed significant values for color, flavor, taste, texture, appearance and overall quality (p<0.05). As a result, the optimal sensory ratio was found to be 6.40 g of Spergularia Marina L. Griseb, 63.49 g of sugar and 106.19 g of grape seed oil. Conclusion: In conclusion, Spergularia Marina L. Griseb is a good source in natural antioxidant aimed at replacing salt, and it is possible to use in cookie or other food products to substitute salt.

• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.282-289
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• 2010

In preparation of silica aerogel-based hybrid coating materials, the combination of hydrophobic aerogel with organic polar binder material is shown to be very limited due to dissimilar surface property between two materials. Accordingly, the surface modification of the aerogel would be required to obtain compatibilized hybrid coating sols with homogeneous dispersion. In this study, the surface of silica aerogel particles was modified by using both surfactant adsorption and heat treatment methods. Four types of surfactants with different molecular weights and HLB values were used to examine the effect of chain length and hydrophilicity. The surface property of the modified aerogel was evaluated in terms of visible observation for aerogel dispersion in water, water contact angle measurement, and FT-IR analysis. In surface modification using surfactants, the effects of surfactant type and content, and mixing time as process parameter on the degree of hydrophilicity for the modified aerogel. In addition, the temperature condition in modification process via heat treatment was revealed to be significant factor to prepare aerogel with highly hydrophilic property.

• Journal of Environmental Science International
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• v.30 no.5
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• pp.399-406
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• 2021

The dissolution of ionized gas in dielectric barrier plasma, similar to the principle of ozone generation, is a major performance-affecting factor. In this study, the plasma gas dissolving performance of a gas mixing-circulation plasma process was evaluated using an experimental design methodology. The plasma reaction is a function of four parameters [electric current (X₁), gas flow rate (X₂), liquid flow rate (X₃) and reaction time (X₄)] modeled by the Box-Behnken design. RNO (N, N-Dimethyl-4-nitrosoaniline), an indictor of OH radical formation, was evaluated using a quadratic response surface model. The model prediction equation derived for RNO degradation was shown as a second-order polynomial. By pooling the terms with poor explanatory power as error terms and performing ANOVA, results showed high significance, with an adjusted R² value of 0.9386; this indicate that the model adequately satisfies the polynomial fit. For the RNO degradation, the measured value and the predicted values by the model equation agreed relatively well. The optimum current, gas flow rate, liquid flow rate and reaction time were obtained for the highest desirability for RNO degradation at 0.21 A, 2.65 L/min, 0.75 L/min and 6.5 min, respectively.