• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 봄 학술발표회 논문집
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• pp.135-142
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• 1998

• Food Science and Biotechnology
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• 제18권4호
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• pp.1013-1018
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• 2009

Several rheological terms were introduced to estimate the properties of cooked noodles with different starch content using tensile tests. Ring-shaped specimens were prepared by connecting both ends of the noodle strip before cooking. Hencky strain and rate, as well as true stress were applied in constant deformation tests. The elastic region on the curves of strain vs. stress was not clearly identified. Strain hardening in the subsequent plastic region was more prominent in low-starch noodles. Elongational viscosities at lower strain rates were used to differentiate noodles with different starch content, representing the dominant effect of protein content in the range of lower strain rates. In stress relaxation tests, the reciprocal of Peleg's constant $K_1$ (initial decay rate) and $K_2$ (asymptotic level) increased and decreased respectively, with an increase in starch content. This indicated that addition of starch contributed to the noodles becoming viscous liquid rather than elastic solid.

• 한국전기전자재료학회논문지
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• 제14권1호
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• pp.20-25
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• 2001

To develop the piezoelectric actuator, the structural, dielectric and piezoelectric properties and electric fieldinduced strain of the ceramics(Pb$\_$1-2/Ba$\_$x/)[Mg$\_$1/2/W$\_$1/2/)$\_$0.03/-Ni$\_$1/3/Nb$\_$2/3/)$\_$0.12/-(Zr$\_$0.5/Ti$\_$0.5/)$\_$0.85/]O$_3$(x=0, 0.01, 0.03, 0.05, 0.07, 0.1) were investigated with the substitution of Ba. The tetragonality of crystal structure and grain size decreased by the substitution of Ba. Curie temperature decreased due to the decrease of the tetragonality, and dielectric constants increased with the substitution of Ba. The coercive field, remnant polarization and electromechanical coupling factor also decreased, whereas the piezoelectric constatns d$\_$33/ and d$\_$31/ were showed the highest value of 430 and 209(x10$\^$-12/C/N), respectively, because of the increase of dielectric constant. The strain induced by 60Hz AC electric field had the maximum value of 204x10$\^$-6/Δℓ/ℓ at the substitution of Ba 3mol%. As the applied electric field approaches to the coercive field, the piezoelectric element is depolarized and the electric field induced strain revealed non-linearity.

• Elastomers and Composites
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• 제40권4호
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• pp.258-265
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• 2005

스포츠화 중창용으로 사용되는 PU, IP 및 PH 등 세가지 종류의 발포체를 일정한 응력으로 반복압축한 후, 반복압축에 따른 발포체의 압축력, 영구변형, 회복력 등에 미치는 영향을 고찰하였다. 발포체의 반복압축에 따른 최대압축력은 PU의 경우는 거의 변화하지 않는 것으로 나타났으나 IP의 경우 최대 압축력은 크게 저하되었다. PU는 반복압축에 따른 발포체의 영구변형은 미소하였으나 PH의 경우 반복압축횟수가 증가함에 따라 현저하게 증가하는 경향을 나타내었다. 경도 45인 발포체를 5만회 반복압축 한 경우 발포체의 영구변형은 PU

• 한국지반공학회논문집
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• 제16권1호
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• pp.99-106
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• 2000

기존의 Oedometer 시험은 간단한 시험장치의 편리함으로 인해 널리 이용되어 왔다. 그러나 이 방법은 장시간의 시험기간, 각 단계 하중에서의 불규칙적인 응력상태, 매우 연약한 점토에 대한 시험의 어려움 및 시료의 포화문제와 같은 여러 문제점을 노출하게 되었다. 따라서 이런 단점을 보완 할 수 있는 시험 방법의 하나로 일정 변형률 압밀시험 이 개발되어 널리 이용되고 있다. 본 논문에서는 세가지 변형률을 이용한 CRS시험을 실시하였으며, 이 결과를 수정된 Wissa(1971)의 비선형 이론을 이용해 해석하고, 기존의 Oedometer시험 및 직접투수시험과 비교분석함으로서 CRS시험의 효율성 및 적용성 유무를 판단하고자 한다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.455-460
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• 1998

This study performed to establish tile characteristics of constant rate of strain consolidation(CRSC) tests. The values obtained by the CRCS tests were compared with oedometer tests. From the comparision of the results of oedometer and CRSC tests for soft soil from Haenam, Korea, it was concluded that. 1. When rate of strain is 0.9mm/hr, compression curve of CRSC test was not coincided with those of tile oedometer test, then preconsolidation stress was larger than those of other rates of strain. 2. Permeabilities from CRSC tests and direct measurements were about same each other, but permeabilities from Oedometer tests were large than those from others.

• 한국농공학회지
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• 제45권2호
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• pp.86-95
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• 2003

During this study, constant stress ratio tests with previous compression anisotropic stress history are performed on compacted decomposed granite soil sampled at Iksan, Jeonbuk. Yielding points are determined from stress-strain curves. The shape and characteristics of compression anisotropic yield curves is examined. In addition, the measured value of yielding curve and stress-strain behavior is predicted by Yasufuku's anisotropic constitutive model based on non-associated flow rule. The main results are summarized as follows : 1) Shape of yielding curves shows almost ellipse but asymmetry with respect to stress path during previous consolidation stress. 2) Yasufuku's anisotropic constitutive model is suitable in evaluation of yielding curves on anisotropic consolidated decomposed granite soil. 3) The predicted stress-strain curve shows reasonable agreement to measured behaviours.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.455-462
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• 2002

There exist several kinds of continuous consolidation tests to analyze the consolidation behavior of soft clay. The constant rate of strain (CRS) test has been adopted as a standard method by several countries, and some researches also have been peformed by domestic researchers. Among those, the constant pressure ratio (CPR) test is peformed with the constant ratio of excess porewater pressure to vertical effective stress. The test has the advantage of considerable reduction of duration time. In the study, the consolidation characteristics are analyzed by performing the CPR test as validate the pressure ratio with undisturbed soft clay and remolded clay, Also, results of the standard consolidation test and CRS test are compared to verify the CPR test can be employed for practical use. As a result, effects of variation of the pressure ratio on consolidation parameter are similar to the strain rate in the CRS test. Therefore, the test can be used to analyze the consolidation behavior of soft clay But the test have some problems such as expensive cost of equipment and highly skilled workmanship.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.943-946
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• 2007

In-plane piezoelectric charge constant of Electro-Active paper (EAPap) was investigated based on direct and converse piezoelectric effects. EAPap samples were made with cellulose film with very thin gold electrode coated on both sides of the film. To characterize direct piezoelectricity of EAPap, induced charge was measured when mechanical stress was applied to EAPap. In-plane piezoelectric charge constant was extracted from the relation between induced charge and applied in-plane normal stress. To investigate converse piezoelectricity, induced in-plane strain was measured when electric field was applied to EAPap. Piezoelectric charge constant was also extracted from the relation of induced in-plane strain and applied electric field. Piezoelectric charge constants obtained from direct and converse piezoelectricity are 31 pC/N and 178 x 10-12m/V for 45 degree sample, respectively. Measured piezoelectric charge constants of EAPap provide promising potential as a piezoelectric material.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.331-334
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• 1998

The solid solutions of the Pb(Sc$\_$0.5/Nb$\_$0.5/)$\_$0.57/Ti$\_$0.43/O$_3$ system were prepared. In the PSNT system, it had been known that two-phase region between the rhombohedral and tetragonal phases was observed between 0.425 of PT at room temperature. In this paper, Fe$_2$O$_3$-doped 0.57PSN-0.43PT composition was prepared by conventional method. The dielectric and strain properties were examined using an computerized measuring apparatus, and the resonance characteristics were measured using an impedance gain phase analyzer. We got the data of dielectric constant, dielectric loss, piezoelectric coefficient, piezoelectric voltage coefficient, frequency constant strain constant mechanical quality factor and electromechanical coupling factor.