• 한국재료학회지
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• 제10권1호
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• pp.34-40
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• 2000

디지털형 압전/전왜 액츄에이터 응용을 위하여 상경계(반강유전상/강유전상) 조성인 $Pb_{0.94}Y_{0.04}[(Zr_0.6Sn_0.4)_{0.915}Ti_0.085]O_3$ (PYZST) 계를 택하여 과잉 PbO의 첨가량 및 소결 조건 변화에 따른 상전이 특성, 유전 특성 및 전기장 유기변형 특성을 연구하였다. 사방정 구조를 갖는 PYZST 세라믹스에서 과잉 PbO 첨가에 따른 결정구조의 변화는 거의 확인되지 않았으나, 소결 후 입자가 약간 작아지며 둥근 형태로 변화하였고 첨가량 증가에 따라 적정 소결온도는 감소하였다. 과잉 PbO의 첨가량이 증가함에 따라, 분극측정시 반강유전상이 보다 안정되는 경향을 보였고, 전계유도변형 측정시 인가전기장 제거상태에서의 변형의 형상기억성이 감소하고 디지털형 변형곡선 특성이 강화되었다. 또한 최대 유전상수와 전계 유기변형량은 감소하였으나 반면 상전이(반강유전상$\leftrightarrow$강유전상) 전기장 및 비저항은 증가하는 경향을 나타냈다. 이러한 결과는 과잉으로 첨가된 PbO에 의한 격자 결함반응 및 분역벽 이동 거동 가능성과 연관시켜 설명하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.231-238
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• 2000

Sand piling method is one of the most widely used methods to improve soft soils. There are several methods to install sand piles, but driven pile method is considered as one of the easiest method. This method simply pushes down the sand piles into soft soils, so that the excess pore pressure would be generated if the soil is saturated. This pore pressure acts as consolidation load. If the amount of sand pile induced pore pressure can be predicted in reasonable ways, the effects of sand piling to improve soft soils would be predicted, and the height of preload can be reduced. In this article, sand pile induced excess pressure was predicted by cavity expansion theory, and the predicted values were compared with the field measured values. The results showed fair agreements between the measured and the predicted excess pore pressure.

• 한국지반환경공학회 논문집
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• 제20권1호
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• pp.13-17
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• 2019

This paper presents case history of railway embankment excess settlement on soft clay during service in southern region of Korea. A lot of field observations show that the measured settlements are a lot larger than settlements actually calculated in this area. Back analysis is carried out to verify the soil parameters which are intended to investigate in the subsurface exploration phase and later in a laboratory test program. Recommendations and causes for the engineering practice are suggested to review the determination of excess settlements and, consequently, to improve the settlement prediction. This enormous discrepancy is due to the passing over secondary consolidation, and the design filling did not meet to real construction filling. Immediate settlement could be subsidiary factor of excess settlement.

• 전자공학회논문지T
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• 제36T권3호
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• pp.7-12
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• 1999

본 논문은 (1-x-y)PMN-yPT-xST세라믹스의 유전 및 변위특성을 ST의 양에 따라 조사하였다. ST의 성분은 1∼ 6㏖%이내로 변화시켰고 과잉 MgO에 따른 조성변화에 따라 결과를 조사하였다. ST의 성분의 증가에 따라 유전상수는 5㏖%인 조성에서 최대값을 나타내었다. 큐리온도는 ST의 성분이 증가함에 따라 선형적으로 감소하였다. 항전계와 잔류분극은 l㏖%인 조성에서 최대값을 나타내었다. 과잉 MgO의 효과에 따라 유전상수는 0.8PMN-0.12PT-0.04ST조성에서 MgO를 3㏖%까지 과잉 첨가함에 따라 증가하였으나 변위특성은 감소함을 나타내었다.

• 한국농공학회논문집
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• 제52권2호
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• pp.1-9
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• 2010

This study was carried out to comparison of coefficient of consolidation and the prediction of excess pore water pressure in agricultural reservoir on soft clay ground. For the purpose of verification of the proposed equation, laboratory model tests and field tests were performed and excess pore water pressure was compared to those predicted with the Terzaghi's method. The predicted excess pore water pressure according to ponding was very applicable to practice because it was close to the observed data. Also, for the comparison of coefficient of consolidation, the oedometer, constant rate of strain (CRS), and Rowe cell tests were performed. The coefficient of consolidation at the Rowe cell and CRS tests showed a greate increase than in the oedometer test. The ratio of the vertical and horizontal coefficient of consolidation showed a large difference according to various tests method and mixing ratio. Therefore, it is recommended that careful attention should be paid to predicting the required consolidation period in agricultural reservoir.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.570-573
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• 2002

Pb(Zr0.52Ti0.48)O3 (PZT) thin films were deposited on the Pt/Ti bottom electrode by rf magnetron sputtering method from target containing 5%, 25% and 50% Pb excess for applying ferroelectric random access memory (FRAM). PZT films were deposited at $300^{\circ}C$ and then they were crystallized by rapid thermal annealing (RTA) at $700^{\circ}C$. After RTA treatment, our results showed that all PZT films indicated perovskite polycrystalline structure with preferred orientation (110) and no pyrochlore phase was observed by X-ray diffraction (XRD) and by Scanning electron microscopy (SEM). A well-fabricated PZT film of excess Pb 25% capacitor showed a leakage current density in the order of $2.63{\times}10^{-7}A/cm^2$ at 100kV/cm, a remanent polarization of $3.385{\mu}C/cm^2$ and a coercive field of 41.32 kV/cm. The results showed that Pb excess of target affects to electrical properties of PZT thin film.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.546-551
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• 2006

This study is concerned with the dynamic behaviour of a fluid layer and a submerged deposit of sand in a rigid rectangular container when subjected to horizontal shaking. Detailed analyses are made of the interaction between the fluid pressure field and the excess pore pressure changes in the sand deposit, in terms of finite-element modelling as well as of two-layer fluid theory. It is shown that the predicted performance compares favourably with what has been observed in centrifugal shaking-table testing on submerged sand deposits.

• Progress in Superconductivity
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• 제7권1호
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• pp.87-91
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• 2005

[ $YBa_{2}Cu_{3}O_{7-x}$ ] thin films were fabricated on $LaAlO_3$(100) substrate by TFA-MOD process. Yttrium-excess (0, 2.5, 5, 10, 15, 20 $at\%$) coating solution was prepared by adding extra amount of yttrium into a stoichiometric(Y:Ba:Cu=1:2:3) TFA precursor solution. Results are presented concerning the influence of excess yttrium additions on the microstructure development and superconducting properties of $YBa_{2}Cu_{3}O_{7-x}$ film. Large sized CuO particles was observed by SEM EDS investigation. The addition of excess yttrium affected little on $T_c$ of $YBa_{2}Cu_{3}O_{7-x}$ film. $J_c$ of YBCO film was enhanced with excess yttrium addition. Jc maximum of $2.21\;MA/cm^2$ (77 K, self field) appeared with the $15\;at\%$ addition of excess yttrium. With further yttrium addition up to $20\;at\%$, Jc decreased down to $0.9\;MA/cm^2$.

• 한국농공학회지
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• 제36권2호
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• pp.123-131
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• 1994

Experimental studies were conducted to make clear the soil moisture environment under the condition of paddy-upland rotational fields by investigating water-table depths and soil moisture contents during growing season of crops in two kinds of soil. The following results were obtained. 1.Although water-table depths fluctuated with the amount of rainfall in the experimental field, it seemed that the variation of vater4able depths in the paddy-upland rotational, field was strongly affected by the condition of locations on paddy fields. 2.It is recognized that the concept of sum of excess water depth(SEWxx) and sum of excess water day(SEDxx) can be used to represent the soil moisture stress index due to the fluctuation of water-table depths. 3.The results of this study clearly indicate that drainage in paddy-upland rotational field to maintain an optimum soil moisture content must be made by introducing the concept of block drainage which needs both subsurface drainage and intercept drainage around a field. 4.Soil moisture contents were affected by both the amount of rainfall and water-table depths, however, the moisture content for top soil showed higher correlation with the amount of rainfall while that for subsoil with water-table depths.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.171-174
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• 2012

Thermophotovoltaics is the direct energy conversion technology from thermal to electric (voltaic) energy via photon radiation, without any thermodynamic cycle. It is, in general, accomplished by immersing solid body in high temperature heat source (e.g. combustion field), in order to achieve high intensity irradiation, and by receiving the radiation thereof on photovoltaic cells. In this paper, advantages of combustion in porous inert medium in applying to the thermophotovoltaics are discussed in a view of its excess enthalpy features. In addition, the similarities of flame behaviors in porous inert medium to both in single and multi-channels are described.