• 한국세라믹학회지
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• 제50권5호
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• pp.341-347
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• 2013

Kaolin-based membranes with a pore size of 0.30-0.40 ${\mu}m$ were successfully prepared by a simple pressing route using low-cost starting materials, kaolin and sodium borate. The prepared green bodies were sintered at different temperatures ranging between 900 and $1200^{\circ}C$. The sintered membranes were characterized by X-ray diffraction, mercury porosimetry, scanning electron microscopy, and capillary flowmetry. It was observed that the porosity decreased with an increase in both the sintering temperature and the sodium borate content, whereas the flexural strength increased with an increase in both the sintering temperature and the sodium borate content. The air flow rate decreased with an increase in the sodium borate content. The typical porosity, flexural strength, and specific flow rate of the kaolin-based membrane sintered with 5 wt% sodium borate at $1100^{\circ}C$ were 37%, 19 MPa, and $1{\times}10^{-3}L/min/cm^2$, respectively, at a p of 30 psi.

• 자원환경지질
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• 제53권1호
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• pp.71-85
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• 2020

본 연구에서는 지반공학 및 지질공학적 측면에서 단층핵의 거동을 이해하기 위해 화강암, 퇴적암 및 화산암 단층대에서 채취된 단층핵 시료를 대상으로 물리적 특성(각력 및 점토함량, 단위중량, 공극률, 함수비)과 마찰 특성(내부마찰각, 점착력)의 관계를 분석하였다. 실내시험으로부터 산정된 물리적 특성을 분석한 결과, 단층핵 내 각력은 단위중량과 양(+)의 상관관계를 가지고, 점토함량, 공극률 및 함수비와는 음(-)의 상관관계를 가진다. 직접전단시험으로부터 산정된 내부 마찰각과 점착력에 대한 사분위수 범위(IQR)는 각각 16.7-38.1°, 2.5-25.3 kPa로 나타났다. 또한, 단층핵의 마찰특성에 미치는 물리적 특성의 영향을 분석한 결과, 마찰각은 모든 암종에서 각각 각력함량 및 단위중량과 양(+)의 상관관계를 가지고, 점토함량, 공극률 및 함수비와 음(-)의 상관관계를 보인다. 대조적으로, 단층핵의 점착력은 각력함량 및 단위중량과 음(-)의 상관관계를 가지고, 점토함량, 공극률 및 함수비와 양(+)의 상관관계를 보인다.

• 한국세라믹학회지
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• 제22권3호
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• pp.60-66
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• 1985

The formation mechanism of unstable alkali and its existing states in the clinker were studied. The relation of unstable alkali content vs. other water-soluble components porosity and the distributionof potassium were investigated. The results are as follows :1) Two states of unstable alkali seem to exist in clinker ie compounds of $K_2O-Al_2O_3$ system and free $K_2O$ 2) The content of water-soluble $Al_2O_3$ tends to increase with increase of unstable alkali content, 3) Most of alkalies in clinker are concentrated in liquid phase at high temperature. Therefore it is possible to make various $K_2O-Al_2O_3$ system compounds according to the content of $K_2O$ in the liquid phase of clinker. In this experiment we found out a $K_2O-Al_2O_3$ compound of high $Al_2O_3$ content (34%) and high $K_2O$ content (33%) in clinker with 1.09% unstable alkali. 4) The porosity of clinker tends to increase with increase of unstable alkali content. 5) The amount of trapped alkali vapor may increase in closed pore in the clinker with high alkali and low $SO_3$ condecent. Therefore free $K_2O$ is the condensed alkali on the wall of closed pore in the clinker.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.592-598
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• 2011

Electrode of solid oxide fuel cell must have sufficient porosity to allow gas transport to the interface with electrolyte effectively but high porosity has a negative impact on structural stability in electrode support. Thus, the upper limit of porosity is based on consideration of mechanical strength of electrode. In this study, the effect of microstructure of Ni-YSZ anode supported SOFC on the mechanical and electrical property was investigated. LSCF composite cathode and 8YSZ electrolyte were used. The porosity of the anode was modified by the amount of graphite powder and added graphite contents were 24, 18, 12 vol%, respectively. The higher the porosity, the better the electrical performance, $P_{max}$. While the flexural strength decreased with increasing the amount of graphite. But the rate of increase in electrical performance and the rate of decrease in mechanical strength were not directly proportional to amount of graphite. The optimum graphite content incorporating both electrical and mechanical performance was 18 vol%.

• 한국재료학회지
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• 제10권10호
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• pp.659-664
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• 2000

연료극 지지체식 원통형 고체산화물 연료전지를 개방하기 위해 연료극 지지체와 전해질이 코팅된 연료극 원통관의 제조 및 그것의 특성에 대해 연구하였다- 연료극 지지체는 20-50vol.%의 탄소함량에 따라 만들어졌으며, 탄소량이 증가함에 따라 연 료극 지지체의 기공율도 점차 증가하였으며, 적절한 기공율을 가지기 위한 최적 탄소량은 30vol.%임을 확인하였다. 연료극 지지체 관은 압출법으로 제작하였으며, 전해질은 슬러리 코팅법으로 원통판의 바깥쪽에 코팅하였고, $1400^{\circ}C$에서 공소결을 성공적으로 실시하였다. 소결후 물리척특성과 미세구조를 조사하였으며, 연료극 지지체관의 기공율은 35%이었고 연료전지의 요구조건을 만족하였다. 기체투과율 시험을 통하여, 연료극 지지체관 자체는 충분히 다공성을 나타내었으나, 전해질층을 코팅한 경우에는 매우 낮은 기체부과율을 나타냄을 확인하였다. 이것은 코팅된 전해질층이 매우 치밀하다는 것을 의미하며, 본 연구를 통해서 연료극 지지체식 원통형 고체산화물 연료전지가 제조될 수 있음을 확인하였다.

• 한국세라믹학회지
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• 제14권4호
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• pp.236-241
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• 1977

Three kinds of specimen, consisting of the graded pyrophyllite particles alone, a substituent of 8 percent fire clay for the finer portion ($F_2$) of it, and 0.8 percent inorganic binder-added composite were prepared under the following conditions respectively; moisture content=4.5~5.0%, forming pressure=250kg/$\textrm{cm}^2$ and sintering temperature=1, 000~1, 30$0^{\circ}C$. The various properties such as modulus of rupture, apparent porosity, bulk specific gravity, pore size and pore distributiion were measured in order to collaborate with sintering phenomena. The results obtained are as follows: (1) Apparent porosity isgradually decreased with rising the sintering temperature to 1, 25$0^{\circ}C$. (2) The binder-added specimen showed the lowest value in porosity. (3) The optimum sintering temperature of specimens was considered to be 1, 25$0^{\circ}C$. (4) The wider differences between pore volumes of specimens could be obtained by method of mercurypenetration porosimeter than by the conventional method for porosity.

• 펄프종이기술
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• 제34권2호
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• pp.47-53
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• 2002

Three types of sludges including printing paper, newsprint and tissue paper were prepared at 5% concentration for filtration-expression operations. Filtration-expression characteristics of sludge were measured in different pressure and wastepaper powder dosage. Specific filtration resistance and porosity were calculated with theoretical formula. Higher pressure increased the progresses of filtration and expression while it decreased porosity. The addition of 5% wastepaper powder more accelerated the progresses of filtration and expression than that of 10% wastepaper powder. The lowest porosity value was also measured at 5% dosage of wastepaper powder. The decrease of porosity implied the decrease of moisture content in cake. The results indicated that dewatering of sludge was efficient in high pressure and 5% dosage of wastepaper powder.

• 한국세라믹학회지
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• 제43권6호
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• pp.351-357
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• 2006

The fabrication process of the honeycomb filter was investigated using synthesized cordierite with the addition of pore former and extrusion additives (either organic matter or graphite). Also, the effect of additives on the resultant properties of honeycomb filter such as porosity, thermal expansion coefficient and mechanical strength were investigated. With increasing the organic matter up to 10 wt%, porosity was increased but compressive strength was decreased. With increasing the graphite content, however, both porosity and compressive strength were increased. The specimen with an optimum processing condition (C-17A30G, sintering at $1150^{\circ}C$) was demonstrated 59% in porosity, 69 MPa in compressive strength, and $2.4{\times}10^{-6}/^{\circ}C\;(25{\sim}1000^{\circ}C$) in thermal expansion coefficient, which physical properties are appropriate for the honeycomb filter applications.

• Carbon letters
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• 제3권3호
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• pp.133-141
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• 2002

It is well known that the porosity and adsorption capacity in a carbon depends on the nature of precursor, pyrolysis and activation conditions and the ash content. The studies on carbon prepared from the dry and wet babbool wood were under taken to ascertain the effect of initial state of precursor on the development of porosity in the resulting activated carbon. The characterization and adsorption studies carried out shows the presence of mainly mesoporosity in the carbon prepared from dry wood while more of microporosity was observed in the activated carbon prepared from wet wood. The results on porosity in both the cases have been compared and correlated with their processing conditions.

• 한국축산식품학회지
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• 제42권3호
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• pp.411-425
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• 2022

Semi-dried restructured sausages are restructured meat products with a high nutritional and economic value. However, excessively long drying times can have negative effects on the energy consumption, texture, and sensory properties of semi-dried restructured sausages. The objective of this study was to investigate the effects of different water contents on the drying and physicochemical characteristics of semi-dried restructured sausages. Sausages were prepared with different initial moisture contents (0%-50%) and drying time (0-580 min). The drying characteristics, including the drying rate, effective moisture diffusivity, and water activity of sausage were significantly improved as the initial moisture content was increased. When the initial moisture content of the sausage was 50%, physicochemical properties, such as color, porosity, shear force, and volatile basic nitrogen, were improved the most along with the decreased drying time. Scanning electron microscopy data showed greater porosity and pore size in sausages with the increase of initial moisture content. Collectively, our data suggest that an increase in the initial moisture content of semi-dried restructured sausages improves their drying characteristics and physicochemical properties.