• Journal of Ship and Ocean Technology
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• 제8권3호
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• pp.50-60
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• 2004

In this paper, a continuum-based design sensitivity analysis (DSA) method is developed for the weakly coupled thermo-elasticity problems. The temperature and displacement fields are described in a common domain. Boundary value problems such as an equilibrium equation and a heat conduction equation in steady state are considered. The direct differentiation method of continuum-based DSA is employed to enhance the efficiency and accuracy of sensitivity computation. We derive design sensitivity expressions with respect to thermal conductivity in heat conduction problem and Young's modulus in equilibrium equation. The sensitivities are evaluated using the finite element method. The obtained analytical sensitivities are compared with the finite differencing to yield very accurate results. Extensive developments of this method are useful and applicable for the optimal design problems incorporating welding and thermal deformation problems.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1689-1696
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• 2007

Equilibrium molecular dynamics (EMD) simulations are used to evaluate the transport coefficients of argonkrypton mixtures at two liquid states (state A: 94.4 K and 1 atm; state B: 135 K and 39.5 atm) via modified Green-Kubo formulas. The composition dependency of the volume at state A obeys close to the linear model for ideal liquid mixture, while that at state B differs from the linear model probably due to the high pressure. The radial distribution functions for the Ar-Kr mixture (x = 2/3) show a mixing effect: the first peak of g11 is higher than that of g(r) for pure Ar and the first peak of g22 is lower than that of g(r) for pure Kr. An exponential model of engineering correlation for diffusion coefficient (D) and shear viscosity (η) is superior to the simple linear model for ideal liquid mixtures. All three components of thermal conductivity (λpm, λtm, and λti) at state A and hence the total thermal conductivity decrease with the increase of x. At state B, the change in λtm is dominant over those in λpm and λti, and hence the total thermal conductivity decrease with the increase of x.

• Bulletin of the Korean Chemical Society
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• 제20권11호
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• pp.1281-1287
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• 1999

The low-lying electronic states of diazirine and 3,3'-dimethyldiazirine have been studied by high level ab initio quantum chemical methods. The equilibrium geometries of the ground state and the first excited singlet and triplet states have been optimized using the Hartree-Fock (HF) and complete active space SCF (CASSCF) methods, as well as using the Møller-Plesset second order perturbation (MP2) theory and the single configuration interaction (CIS) theory. It was found that the first excited singlet state is of 1 B1 symmetry resulting from the n- π* transition, while the first excited triplet state is of 3 B2 symmetry resulting from the π- π* transition. The harmonic vibrational frequencies have been calculated at the optimized geometry of each electronic state, and the scaled frequencies have been compared with the experimental frequencies available. The adiabatic and vertical transition energies from the ground electronic state to the low-lying electronic states have been estimated by means of multireference methods based on the CASSCF wavefunctions, i.e., the multiconfigurational quasidegenerate second order perturbation (MCQDPT2) theory and the CASSCF second-order configuration interaction (CASSCF-SOCI) theory. The vertical transition energies have also been calculated by the CIS method for comparison. The computed transition energies, particularly by MCQDPT2, agree well with the experimental observations, and the electronic structures of the molecules have been discussed, particularly in light of the controversy over the existence of the so-called second electronic state.

• 한국자기공명학회논문지
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• 제28권1호
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• pp.1-5
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• 2024

IscU, the iron-sulfur (Fe-S) cluster scaffold protein, is an essential protein for biogenesis of Fe-S clusters. Previous studies showed that IscU manifests a metamorphic structural feature; at least two structural states, namely the structured state (S-state) and the disordered state (D-state), interconverting in a physiological condition, was observed. Moreover, subsequent studies demonstrated that the metamorphic flexibility of IscU is important for its Fe-S cluster assembly activity as well as for an efficient interaction with various partner proteins. Although solution nuclear magnetic resonance (NMR) spectroscopy has been a useful tool to investigate this protein, the detailed molecular mechanism that sustains the structural heterogeneity of IscU is still unclear. To tackle this issue, we applied a high-pressure NMR (HP-NMR) technique to the IscU variant, IscU(I8K), which shows an increased population of the S-state. We found that the equilibrium between the S- and D-state was significantly perturbed by pressure application, and the specific regions of IscU exhibited more sensitivity to pressure than the other regions. Our results provide novel insights to appreciate the dynamic behaviors of IscU and the related versatile functionality.

• 유통과학연구
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• 제13권11호
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• pp.39-46
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• 2015

Purpose - In Korea, there has been a recent trend that shows housing prices have risen rapidly following the International Monetary Fund crisis. The rapid rise in housing prices is spreading recognition of this as a factor in housing price volatility. In addition, this raises the expectations of housing prices in the future. These expectations are based on the assumption that a relationship exists between the current housing prices and expected housing prices in the real estate industry. By performing an empirical analysis on the validity of the claim that an increase in current housing prices can be correlated with expected housing prices, this study examines whether a long-term equilibrium relationship exists between expected housing prices and existing housing prices. If such a relationship exists, the recovery of equilibrium from disequilibrium is analyzed to derive related implications. Research design, data, and methodology - The relationship between current housing prices and expected housing prices was analyzed empirically using the Vector Error Correction Model. This model was applied to the co-integration test, the long-term equilibrium equation among variables, and the causality test. The housing prices used in the analysis were based on the National Housing Price Trend Survey released by Kookmin Bank. Additionally, the Index of Industrial Product and the Consumer Price Index were also used and were obtained from the Bank of Korea ECOS. The monthly data analyzed were from January 1987 to May 2015. Results - First, a long-term equilibrium relationship was established as one co-integration between current housing price distribution and expected housing prices. Second, the sign of the long-term equilibrium relationship variable was consistent with the theoretical sign, with the elasticity of housing price distribution to expected housing price, the industrial production, and the consumer price volatility revealed as 1.600, 0.104,and 0.092, respectively. This implies that the long-term effect of expected housing price volatility on housing price distribution is more significant than that of the industrial production and consumer price volatility. Third, the sign of the coefficient of the error correction term coincided with the theoretical sign. The absolute value of the coefficient of the correction term in the industrial production equation was 0.006, significantly larger than the coefficients for the expected housing price and the consumer price equation. In case of divergence from the long-term equilibrium relationship, the state of equilibrium will be restored through changes in the interest rate. Fourth, housing-price volatility was found to be causal to expected housing price, and was shown to be bi-directionally causal to industrial production. Conclusions - Based on the finding of this study, it is required to relieve the association between current housing price distribution and expected housing price by using property taxes and the loan-to-value policy to stabilize the housing market. Further, the relationship between housing price distribution and expected housing price can be examined and tested using a sophisticated methodology and policy variables.

• 방사선산업학회지
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• 제9권3호
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• pp.111-117
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• 2015

In this paper, production of $^{166}Ho$ by double neutron capture from HANARO research reactor was evaluated. This production approach provides $^{166}Ho$ with high specific activity. $^{164}Dy$ is transmuted into $^{165g+m}Dy$ by (n,${\gamma}$) reaction, then $^{165g+m}Dy$ is transmuted into $^{166}Dy$ by (n,${\gamma}$) reaction. At the end of neutron irradiation, population of $^{166}Dy$ atoms reaches highest point. And $^{164}Dy$ exists as a mixture with $^{165m}Dy$, $^{165}Dy$, $^{166}Ho$ and $^{165}Ho$ at this point. To obtain $^{166}Ho$ with high specific activity, Ho isotopes from irradiated target is separated out. Then $^{166}Ho$ decayed from $^{166}Dy$ is eluted at radioactive equilibrium state. At each step, the number of relevant nuclide is calculated by the state equation. The neutron irradiation time for maximum $^{166}Dy$ is calculated for 283 hour. When 100 mg target of $Dy_2O_3$ (96.8% enriched $^{164}Dy$) is used, possible activity of $^{166}Ho$ is 3.54 Ci($1.31{\times}10^{11}Bq$). For separation efficiency of Dy/Ho is 99.99%, $^{166}Ho/Ho$ is 0.62.

• 대한기계학회논문집B
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• 제22권6호
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• pp.832-839
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• 1998

The potential work is defined as the maximum available work extractable from a composite system. It is important concept to understand the behavior of a composite system because it is a property of the composite system and shows the possible room for the system to change its state by itself. To explain this concept quantitatively, the behavior of a composite system composed of two simple ideal gas systems is analyzed. The potential work of the composite system is estimated, the various reversible processes from a given state to the equilibrium state and the processes on which potential works are constant are shown on the T-P and S-V planes. Such an effort will be necessary to understand and characteristics of composite systems as well as helpful for a deeper comprehension of the energy conversion principles.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2385-2391
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• 2018

This paper is devoted to detecting decomposition characteristics of Iodotrifluoromethane ($CF_3I$) under alternating current (AC) discharges or load current interruptions. The decomposition products are measured utilizing chromatography-mass spectroscopy. It is found that less than 1% $CF_3I$ gas decomposed after several interruptions at load current of 200 A or hundred times of AC discharges. However, under interruptions at a current of 400 A, more than 95% $CF_3I$ gas decomposed into carbon tetrafluoride ($CF_4$) and hexafluoroethane ($C_2F_6$). The equilibrium compositions based on Gibbs free energy minimization of $CF_3I$ was calculated to explain the decomposition mechanism.

• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.344-347
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• 2007

A interpenetrating polymer network (IPN) hydrogel, composed of chitosan (CS) and poly(diallydimethylammonium chloride) (PDADMAC) was prepared, which exhibited electrical sensitive behavior. The swelling behavior of the CS/PDADMAC SIPN hydrogel was studied by immersion of the gel into various pH buffer solutions, and their stimuli response in electric fields also investigated. In order to clarify the relationship between the equilibrium swelling ratio and bending behavior of the SIPN hydrogels, the state of water in the SIPN hydrogel was also investigated using differential scanning calorimetry (DSC).

• 대한기계학회논문집A
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• 제20권5호
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• pp.1383-1391
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• 1996

The steady-state response for a coupled structure-acoustic-cavity systme has been investigated by numerical technique using a directly coupled finite element method(FEM) and Boundary Element Method(BEM) model. The Laplace tranformed matrix equations for the structure and the acoustic cavity are coupled directly satisfying the necessary equilibrium and compatibility conditions. The coupled FEM-BEM code is verified by comparing its prediction for an example with known analytical, numerical and experimental results. The example involves a coupled structure-acoustic-cavity system which is a box-type cavity with one end as experimentally excited pinned-pinned plate.