• Korean Journal of Food Science and Technology
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• 제46권3호
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• pp.341-346
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• 2014

This study was conducted to evaluate the effect of trehalose on the rheological properties of bread flour dough. Farinographic and viscographic properties, pH, total titratable acidity (TTA), and fermentation power were analyzed for flour dough rheology. Flour dough containing trehalose showed greater water absorption capacity and longer development time. However the stability, degree of softening, and farinograph quality number (FQN) were lower for the trehalose-containing flour dough, however, these factors decreased with increasing amounts of trehalose. Trehalose did not affect the beginning of gelatinization temperature and maximum viscosity temperature of flour. The maximum viscosity was the lowest with 6% trehalose, the end of final holding period, breakdown and setback values decreased with increasing amounts of trehalose. Flour dough with 4% trehalose had the lowest pH value for 120 min fermentation at $30^{\circ}C$, and the highest TTA value. Addition of 4% and 6% trehalose showed larger fermentation volume of dough than the control. The results suggested that trehalose positively affected the rheological properties of flour dough such as bread volume, softness, and staling delay.

• Clean Technology
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• 제24권4호
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• pp.332-338
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• 2018

Currently graphite is used as an anode active material for lithium ion battery. However, since the maximum theoretical capacity of graphite is limited to $372mA\;h\;g^{-1}$, a new anode active material is required for the development of next generation high capacity and high energy density lithium ion battery. The maximum theoretical capacity of Si is $4200mA\;h\;g^{-1}$, which is about 10 times higher than the maximum theoretical capacity of graphite. However, since the volume expansion rate is almost 400%, the irreversible capacity increases as the cycle progresses and the discharge capacity relative to the charge is remarkably reduced. In order to solve these problems, it is possible to control the particle size of the Si anode active material to reduce the mechanical stress and the volume change of the reaction phase, thereby improving the cycle characteristics. Therefore, in order to minimize the decrease of the charge / discharge capacity according to the volume expansion rate of the Si particles, the improvement of the cycle characteristics was carried out by pulverizing Si by a dry method with excellent processing time and cost. In this paper, Si is controlled to nano size using vibrating mill and the physicochemical and electrochemical characteristics of the material are measured according to experimental variables.

• Journal of the Korean Society of Food Culture
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• 제23권1호
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• pp.62-67
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• 2008

This study was conducted to evaluate characteristic of breadmaking for white bread with fermented rice bran (FRB) (5 to 20%). In proximate composition analysis of FRB which was contained 38.72% moisture, 11.06% crude protein, 17.38% crude fat, 12.74% crude fiber and 11.85% ash. The degree of dough fermentation and dough pH tended to decrease depending on the degree of FRB powder, but there were no significant differences between control group and 5% FRB adding group. In bread weight and volume analysis, bread weight was decreased but bread volume was increased with FRB powder adding degrees. The color of crumb became darker according to the addition of FRB powder, but redness and yellowness were increased. The hardness, gumminess and brittleness of white bread showed a tendency to increase while cohesiveness and springness was decreased. In sensory analysis, FRB group showed generally low scores in color, flavor, texture, taste, overall acceptability except for 5% FRB adding group which showed similar results with control group. Taken together, FRB could be used as a nutrition improvement for breadmaking and a suitable FRB adding volume for breadmaking is 5%.

• Journal of the Korean Magnetics Society
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• 제2권3호
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• pp.251-256
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• 1992

Artificial superlattices of Co/Pd were prepared by RF magnetron sputtering Multilayered structure and compositional modulation were analyzed with a side angle x-ray diffractometer. It has been found that expansion of Co lattice occured in this artificial superlattice due to the lattice mismatch between Co and Pd. Perpendicular magnetic anisotropy could be observed when the Co layer thickness became less than 8${\AA}$ and maximum coercivity of 2350 Oe could be obtained in [Co(2.5 ${\AA}$)/Pd(9.3 ${\AA})]_{50}$/Pd$(200\;{\AA})$ with a perfect squareness of magnetic hysteresis loop. Characteristic of perpendicular magnetic anisotropy in Co/Pd superlattices could be related to the expansion of Co lattice caused by Pd layer and it turned out that as the thickness of Pd layer increased, perpendicular magnetic anisotropy increased. The interface anisotropy energy and volume anisotropy energy were calculated to be 0.29 ergs/$cm^2$ and -$6.9{\times}10^6$ ergs/$cm^3$ respectively, which are consistent with the values reported elsewhere.

• Journal of the Korean Geosynthetics Society
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• 제9권3호
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• pp.39-45
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• 2010

When the ground temperature drops below $0^{\circ}C$, wet soils expand due to the ice formation in their porous space. This results in frost heave which causes structural stability problems. Frost heave is attributed by several factors such as physical soil properties and heat transfer including pore water phase change. Due to the complex physical phenomena, reliable and verified multi-dimensional numerical models for frost heave problems are still in a research stage. This study presents an efficient and simple method of overcoming numerical problems associated with sudden jump of heat capacity due to the phase change from water to ice in the pore space. This paper proposes heat transfer equation and finite element method when the saturated soils or porous rocks are subjected to freezing. Numerical analyses using the proposed method agree well with the known closed form solution and the laboratory test results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제38권5호
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• pp.477-481
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• 2010

Some rotorcraft fuel tanks are required to be self-sealing and crashworthy for enhancing the survivability of crews. Self-sealing capability prevents the fuel leakage through contacting fuel with self-sealing material when the tank wall is penetrated by projectiles such as bullets. US army established MIL-DTL-27422D which specifies the detail requirements related to gunfire resistant fuel tank especially for military rotorcraft. The Fuel tanks for Korea Helicopter Program have been developed in accordance with MIL-DTL-27422D. The Self-sealing capability of the fuel tanks has been confirmed by the gunfire resistance test which specified on the MIL-DTL-27422D.

• Korean Chemical Engineering Research
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• 제54권1호
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• pp.16-21
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• 2016

Silicon/Carbon/CNT composites as anode materials for lithium-ion batteries were synthesized to overcome the large volume change during lithium alloying-de alloying process and low electrical conductivity. Silicon/Carbon/CNT composites were prepared by the fabrication processes including the synthesis of SBA-15, magnesiothermic reduction of SBA-15 to obtain Si/MgO by ball milling, carbonization of phenolic resin with CNT and HCl etching. The prepared Silicon/Carbon/CNT composites were analysed by XRD, SEM, BET and EDS. In this study, the electrochemical effect of CNT content to improve the capacity and cycle performance was investigated by charge/discharge, cycle, cyclic voltammetry and impedance tests. The coin cell using Silicon/Carbon/CNT composite (Si:CNT=93:7 in weight) in the electrolyte of $LiPF_6$ dissolved in organic solvents (EC:DMC:EMC=1:1:1 vol%) has better capacity (1718 mAh/g) than those of other composition coin cells. The cycle performance of coin cell was improved as CNT content was increased. It is found that the coin cell (Si:CNT=89:11 in weight) has best capacity retension (83%) after 2nd cycle.

• Journal of Adhesion and Interface
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• 제11권1호
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• pp.26-34
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• 2010

We synthesized polyurethane adhesive having thermal characteristic could be debonded by heat treatment and made a dismantlable polyurethane adhesive including thermally expansive bead. We used dynamic mechanical thermal analyzer (DMA) to confirm thermal characteristic and investigated bond strength, dismantlement property of dismantlable polyurethane adhesive by content of thermally expansive bead, heating trigger and treatment conditions. The dismantlable polyurethane adhesive could be expanded by hot-air or microwave treatment and the dismantlement of the specimens became easier as the weight fraction of the thermally expansive bead increased. At the dismantlable polyurethane adhesive, the content of thermally expansive bead 40% was suitable for both bond strength and dismantlement, in case of using hot-air treatment as trigger for dismantlement, bonded joints were separated easily at $160^{\circ}C$ for 30 min and in case of using microwave as trigger, bonded joints were separated easily by irradiating microwave for 4 min.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.113.2-113.2
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• 2010

세라믹 필터는 여러 종류의 분진제거 시스템에서 연소 배가스 정제를 위한 가장 적절한 소재로 알려져 있다. 현재까지 다양한 형태의 세라믹 필터가 개발되고 있는데, 캔들 타입(candle type), 튜브 타입(tubular type), 평판 타입(parallel flow type) 등이 그 예이다. 통상적으로 세라믹 캔들 필터는 가압유동층복합발전(PFBC, Pressurize Fluidized-Bed Combustion), 석탄가스화복합발전(IGCC, Integrated coal Gasification Combined Cycle), 석탄가스화연료전지복합발전(IGFC, Integrated coal Gasification Fuel cell Combined cycle)에서 고온 배가스 정제용으로 사용되고 있다. 일반적으로 IGCC나 CTL 합성가스 정제시스템의 경우에는 높은 고압(약 25기압)과 미세분진이 함유되어 있는 분위기에서 운전된다. 그러므로 이때 사용되는 초청정용 세라믹 집진필터는 고온, 고압 및 부식 환경에서 50 MPa 이상을 갖는 높은 강도와 내식성을 갖도록 개발되어야 하기 때문에 SiC(Silicon Carbide)가 가장 적절한 캔들 필터 소재로 적용되고 있다. 이에 따라 집진용 SiC 세라믹 캔들 필터를 개발하기 위해서는 고온에서 내산화성이 우수하고, 부피팽창에 의한 균열이 발생하지 않는 무기결합재의 선정 및 이를 통한 소재의 특성 최적화가 가장 중요한 부분이라 할 수 있다. 본 연구에서는 래밍성형 공정을 적용하여 1m급 탄화규소 세라믹 캔들 필터 시작품을 제조하였으며, 래밍성형 공정 이외에 정수압가압성형, 진공압출성형으로 제조되고 있는 세라믹 캔들 필터의 국내외 시장 및 그 전망을 분석하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.109.2-109.2
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• 2010

세라믹 필터는 여러 종류의 분진제거 시스템에서 연소 배가스 정제를 위한 가장 적절한 소재로 알려져 있다. 현재까지 다양한 형태의 세라믹 필터가 개발되고 있는데, 캔들 타입(candle type), 튜브 타입(tubular type), 평판 타입(parallel flow type) 등이 그 예이다. 통상적으로 세라믹 캔들 필터는 가압유동층복합발전(PFBC, Pressurize Fluidized-Bed Combustion), 석탄가스화복합발전(IGCC, Integrated coal Gasification Combined Cycle), 석탄가스화연료전지복합발전(IGFC, Integrated coal Gasification Fuel cell Combined cycle)에서 고온 배가스 정제용으로 사용되고 있다. 일반적으로 IGCC나 CTL 합성가스 정제시스템의 경우에는 높은 고압(약 25기압)과 미세분진이 함유되어 있는 분위기에서 운전된다. 그러므로 이때 사용되는 초청정용 세라믹 집진필터는 고온, 고압 및 부식 환경에서 50 MPa 이상을 갖는 높은 강도와 내식성을 갖도록 개발되어야 하기 때문에 SiC(Silicon Carbide)가 가장 적절한 캔들 필터 소재로 적용되고 있다. 이에 따라 집진용 SiC 세라믹 캔들 필터를 개발하기 위해서는 고온에서 내산화성이 우수하고, 부피팽창에 의한 균열이 발생하지 않는 무기결합재의 선정 및 이를 통한 소재의 특성 최적화가 가장 중요한 부분이라 할 수 있다. 본 연구에서는 IGCC나 CTL 공정에 적용하기 위한 SiC 캔들 필터 소재 개발을 위해 래밍성형 공정으로 1m급의 탄화규소 캔들 필터 시작품을 제작하여 SiC 출발입자 크기와 무기계 결합재인 스트론튬 카보네이트의 첨가량 변화에 따른 필터 소재의 특성 평가를 수행하였다.