• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.215-216
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• 2008

Electricity unified field is described based on magnetic theory. Maxwell Einstein Lorentz Equation & pair particle photon model was introduced for Photonics. Refractive index is calculated as deceleration and deflection of photon due to photo-induced surface magnetism. MEL equation was proved with magneto-jet assumption.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.771-772
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• 2011

• Korean Journal of Agricultural Science
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• v.13 no.2
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• pp.255-264
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• 1986

The objectives of this study were to examine the viscoelastic behaviour of stem samples of rice in force-relaxation and rheological model to represent its relaxation behaviour, and to study the effects of rate of deformation and initial deformation on the relaxation time. The results were as follows; 1. In the process of loading and unloading, there is any plastic deformation so called elasto-plastic hysterisis. 2. Loading and unloading of stem of rice for several cycles has also shown the reduction of plastic or residual deformation and work hardening. 3. The relaxation behaviour of stem of rice in compression may be described by a generalized Maxwell model consisting of three Maxwell units in parallel. The rheological equation of such a model is given as $$F(t)=C_1e^{{-t/{\tau}}_1}+C_2e^{{-t/{\tau}}_2}+C_3e^{{-t/{\tau}}_3}$$ 4. Force relaxation always increased with increasing rates of deformation and initial deformation.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.458-467
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• 2012

In this study, the linear viscoelastic response of a rectangular laminated plate is investigated. The viscoelastic properties, expressed by two basic spring-dashpot models, that is Kelvin and Maxwell models, is assumed in the range to investigate the influence of viscoelastic coefficients to mechanical behavior. In the present study, viscoelastic responses are performed for two popular equivalent single-layered theories, such as the first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT). Compliance and relaxation modulus of time-dependent viscoelastic behavior are approximately determined by Prony series. The constitutive equation for linear viscoelastic material as the Boltzmann superposition integral equation is simplified by the convolution theorem of Laplace transformation to avoid direct time integration as well as to improve both accuracy and computational efficiency. The viscoelastic responses of composite laminates in the real time domain are obtained by applying the inverse Laplace transformation. The numerical results of viscoelastic phenomena such as creep, cyclic creep and recovery creep are presented.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.522-525
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• 2008

최근 세라믹 막은 우수한 화학적, 열적 안정성으로 기체 분리 공정에 각광을 받아 왔다. 특히 혼합기체에서 고 순도의 수소를 분리해 내는 기술은 연료전지 공정에서 화학 에너지를 전기화학 에너지로 전환시키는데 중요한 역할을 차지한다. 본 연구에서는MTES 템플레이팅 막을 이용하여 이 막 공정의 흡착 및 투과 특성을 규명하고, 이성분 혼합기체에서 고 순도의 수소를 추출해 낼 수 있는 최적 조건을 도출해 내었다. 또한, 기체 분리 거동을 살펴보기 위해 Gproms Dynamic Simulator를 이용하였으며, 이때 기체상의 물질전달을 모사하기 위해 Dust Gas Model(DGM)을, 표면 확산 거동을 모사하기 위해 Generalized Stefan-Maxwell(GSM)식을 적용하였다. 이를 통해 평형론적 흡착 뿐 아니라 속도론적 흡착을 동시에 적용할 수 있게 하였다. MTES 템플레이팅 막의 흡착 및 분리능을 규명하기 위해 본 연구에서는 혼합기체의 투과, 분리 실험이 선행되었다. 실험 조건은 온도범위 323$\sim$473 K, 압력범위 0$\sim$7 atm에서 수행되었으며, 혼합기체는2성분으로 수소-메탄, 수소-이산화탄소, 수소-질소로 기체의 구성비는 각각 50:50 이다. 본 연구를 통해 각 혼합 기체들이 정상상태에 도달하는 시간과 분리능을 계산해 내었으며, 이 분리능을 다시 온도와 압력에 따른 결과로 분석하여 어느 조건에서의 수소 분리도가 최고치를 보이는지를 규명했으며, 시뮬레이션과 비교,대조하여 예측도를 검사하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.1
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• pp.53-60
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• 2012

To reduce the vibration in industrial settings, the viscous fluid dampers have been widely used. Since the damper shows a viscoelastic behavior, many methods to predict the behavior have been investigated. But the methods did not consider a change of damper size that is important factor for practical design engineer. In this study, to predict a change of damper ability with respect to a change of damper size, the dynamic experiment were conducted with fixed aspect ratio and gap. The damping coefficient at zero frequency was computed through theoretical and experiment approach in order to fit the experimental results using fractional derivative Maxwell model.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.105-108
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• 2007

최근 세라믹 막은 우수한 화학적, 열적 안정성으로 기체 분리 공정에 각광을 받아왔다. 특히 혼합기체에서 고 순도의 수소를 분리해 내는 기술은 연료전지 공정에서 화학 에너지를 적기화학 에너지로 전환시키는데 중요한 역할을 차지한다. 본 연구에서는 MTES 템플레이팅 막을 이용하여 이 막 공정의 흡착 및 투과 특성을 규명하고, 이성분 혼합기체에서 고 순도의 수소를 추출해 낼 수 있는 최적 조건을 도출해 내었다. 또한, 기체 분리 거동을 살펴보기 위해 Gproms Simulator를 이용하였으며, 이때 기체상의 물질전달을 모사하기 위해 Dust Gas Model(DGM)을, 표면 확산 거동을 모사하기 위해 Generalized Stefan-Maxwell(GSM)식을 적용하였다. 이를 통해 평형론적 흡착 뿐 아니라 속도론적 흡착을 동시에 적용할 수 있게 하였다. MTES 템플레이팅 막의 흡착 및 분리능을 규명하기 위해 본 연구에서는 혼합기체의 투과, 분리 실험이 선행되었다. 실험 조건은 온도범위 $30{\sim}50$ $^{\circ}C$, 압력범위 $0{\sim}5$ atm에서 수행되었으며, 혼합기체는 2성분으로 수소 메탄, 수소-이산화탄소, 수소-질소로 기체의 구성비는 각각 50:50 이다. 본 연구를 통해 각 혼합 기체들이 정상상태에 도달하는 시간과 분리능을 계산해 내었으며, 이 분리능을 다시 온도와 압력에 따른 결과로 분석하여 어느 조건에서의 수소 분리도가 최고치를 보이는지를 규명했으며, 시뮬레이션과 비교, 대조하여 예측도를 검사하였다.

• Polymer(Korea)
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• v.24 no.5
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• pp.690-700
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• 2000

In this study, an elastomer-assistered compression molding process was investigated by experiments as well as modeling for the long-fiber reinforced thermoset composites. The consolidation pressure generated by fixed-volume and variable-volume conditions was thermodynamically derived for both elastomer and curing prepregs, and was compared with the pressure measured during curing of epoxy matrix. Exhibiting non-linear viscoelastic characteristics in the compressive stress-strain tests, the measured stress was well compared with a modifed KWW (Kohlrausch-Williame-Watts) equation, which is based on the Maxwell viscoelastic model. Using the developed model equations, the consolidation pressure generated by the elastomer was successfully predicted for the compression molding process of thermoset composite materials in tile closed mold system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.1
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• pp.1-7
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• 1998

The near field radiated from the monopole antenna of the cellular phone was calculated by using the modified finite difference time domain algorithm derived from the integral form of Maxwell's equations. Substituting the near field value into the differential form of Maxwell's equations, SAR's distribution in the human head was obtained. The human head was simulated by a model of 800,000 block cells with dielectric constant and conductivity. The cell size was taken to be 0.5 cm. the transmitted power of the cellular phone was assumed to be 0.6 watts at the frequency of 833 MHz. The distance between the head and the cellular phone was 2.0 cm, the maximum SAR induced in the human head was about 1.5 W/kg and was below the IEEE's upper safety limit of 1.6 W/kg.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.515-521
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• 2013

Magnetoelectric(ME) bulk composites with PZT-PNN-PZN/$Fe_2O_4$ were prepared by using a conventional ceramic methods and investigated on the ME voltage vs frequency of ac magnetic fields. We made the electric equivalent circuits by using the Maxwell-Wagner model and simulated the frequency dependence of ME voltage in low frequency region. ME devices were described by a series of two equivalent circuits of piezoelectric and magnetic, which have the relaxation time ${\tau}$ due to the interaction between ME device and load resistor. Equivalent circuit of piezoelectric material is independent of frequency. However ferrite magnetic materials have Debye absorption and dipolar dispersion, whose equivalent circuit is a function of frequency. Therefore we suggest the resistance in the equivalent circuit is proportion to $1+{\omega}^2{\tau}^2$ and the capacitance is in inverse proportion to $1+{\omega}^2{\tau}^2$ in the magnetic materials.