• Journal of Institute of Convergence Technology
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• v.5 no.1
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• pp.1-5
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• 2015

SI thermochemical hydrogen production process achieves water splitting into hydrogen and oxygen through three chemical reactions. The process is comprised of three sections and one of them is HI decomposition into $H_2$ and $I_2$ called as Section III. The production of $H_2$ included processes involving EED for concentrating a product stream from Section I. Additionally an $I_2$ crystallization would be considered to reduce burden on EED by removing certain amount of $I_2$ out of a process stream prior to EED. In this study, the current thermodynamic model of SI process was briefly described and the calculation results of the applied Electrolytes NRTL model for phase equilibrium calculations was illustrated for ternary systems of Section III. We calculated temperature and heat duty of an $I_2$ crystallizer and heat duty of heaters using UVa model and heat balance equation of simulation tool. The results were expected to be used as operation information in optimizing HI decomposition process and setting up material balance throughout SI process.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.98-105
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• 2021

Using the frequency-based decomposition, I decompose the consumption growth to explain well-known patterns of stock returns in the Korean market. To be more specific, the consumption growth is decomposed by its half-life of shocks. The component over four years of half-life is called the business-cycle consumption component, and the components with half-lives under four years are short-run components. I compute the long-run and short-run components of stock excess returns as well and use component-by-component sensitivities to price stock portfolios. As a result, the business-cycle consumption risk with half-life of over four years is useful in explaining the cross-section of size-book-to-market portfolios and size-momentum portfolios in the Korean stock market. The short-run components have their own pricing abilities with mixed direction, so that the restricted one short-term factor model is rejected. The explanatory power with short- and long-run components is comparable to that of the Fama-French three-factor model. The components with one- to four-year half-lives are also helpful in explaining the returns. The results about the long-run components emphasize the importance of long-run component in consumption growth to explain the asset returns.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.764-771
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• 2006

The use of 3-D finite elements for the eigen analysis of beam-like structures with arbitrary section shape may not be practical in certain cases, from the aspect of CPU time. In this connection, this paper presents a systematic algorithm for decomposing an arbitrary section into finite number of basic ones and computing essential sectional quantities required for the eigen analysis using the beam theory. The numerical accuracy of the proposed method is assesed from the comparison with the 3-D finite . element method.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.4
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• pp.395-402
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• 2006

Iodine-sulfur(IS) hydrogenation production process consists of three sections, which are so called a Bunsen reaction section, a HI decomposition section and a $H_2SO_4$ decomposition section as a closed cycle. For highly efficient operation of a Bunsen reaction section, we investigated the phase separation characteristics of $H_2SO_4-HI-H_2O-I_2$ system into two liquid phases($H_2SO_4$-rich phase and $HI_x$-rich phase) in the high temperature ranges, mainly from 353 to 393 K, and in the $H_2SO_4/HI/H_2O/I_2$ molar ratio of $1/2/14{\sim}30/0.3{\sim}13.50$. The desired results for the minimization of impurities in each phase were obtained in conditions with the higher temperature and the higher $I_2$ molar composition. On the basis of the distribution of $H_2O$ to each phase, it is appeared that the affinity between $HI_x$ and $H_2O$ was more superior to that between $H_2SO_4$ and $H_2O$.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.2
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• pp.126-136
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• 2021

During operation of nuclear power plants, the fatigue assessment should be conducted repeatedly, considering changes of operating environments. For the case that cumulative usage factors (CUFs) may exceed the acceptance limit, flaw tolerance evaluation can be an alternative method to meet the regulatory requirements. In this respect, this paper analyzes the effects of the input variables for flaw tolerance evaluation based on ASME BPVC Section XI Appendix L. The reference analysis is performed for the example problem in NUREG/CR-6934. Then effects of the crack orientation, stress intensity factor solutions, thermal stress profiles, fatigue stress decomposition and fatigue crack growth curves are considered for the sensitivity analysis. The results show that the stress analysis considering the actual environment plays a crucial role in flaw tolerance evaluation.

• Journal of Ecology and Environment
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• v.41 no.12
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• pp.336-344
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• 2017

Background: Because of climate change, interest in the development of carbon pools has increased. In agricultural ecosystems, which can be more intensively managed than forests, measures to control carbon dioxide ($CO_2$) emission and absorption levels can be applied relatively easily. However, crop residues may be released into the atmosphere by decomposition or combustion. If we can develop scientific management techniques that enable these residues to be stocked on farmland, then it would be possible to convert farmlands from carbon emission sources to carbon pools. We analyzed and investigated soil respiration (Rs) rate characteristics according to input of carbonized residue of red peppers (Capsicum annuum L.), a widely grown crop in Korea, as a technique for increasing farmland carbon stock. Results: Rs rate in the carbonized biomass (CB) section was $226.7mg\;CO_2\;m^{-2}h^{-1}$, which was 18.1% lower than the $276.9mg\;CO_2\;m^{-2}h^{-1}$ from the red pepper residue biomass (RB) section. The Rs rate of the control was $184.1mg\;CO_2\;m^{-2}h^{-1}$. In the following year, Rs in the CB section was $204.0mg\;CO_2\;m{-2}h^{-1}$, which was 38.2% lower than the $330.1mg\;CO_2\;m^{-2}h^{-1}$ from the RB section; the control emitted $198.6mg\;CO_2\;m^{-2}h^{-1}$. Correlation between Rs and soil temperature ((Ts) at a depth of 5 cm) was $R^2=0.51$ in the RB section, which was higher than the other experimental sections. A comparison of annual decomposition rates between RB and CB showed a large difference, 41.4 and 9.7%, respectively. The results showed that carbonization of red pepper residues reduced the rates of decomposition and Rs. Conclusions: The present study confirmed that the Rs rate can be reduced by carbonization of residue biomass and putting it in the soil and that the Rs rate and Ts (5 cm) were positively correlated. Based on the results, it was determined that approximately $1.2t\;C\;ha^{-1}$ were sequestered in the soil in the first year and $3.0t\;C\;ha^{-1}$ were stored the following year. Therefore, approximately $1.5t\;C\;ha^{-1}year^{-1}$ are expected to be stocked in the soil, making it possible to develop farmlands into carbon pools.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.284-293
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• 1999

The rigid-plastic finite element analysis requires a large amount of computation time due to its non-linearity. For economic computation, mismatching refinement, and efficient domain decomposition method with different mesh density for each sub domain, is developed. A modified velocity alternating scheme for the interface treatment is proposed in order to obtain good convergence and accuracy. As a numerical example, the axisymmetric extrusion process is analyzed. The results are discussed for the various velocity update schemes form the viewpoint of convergence and accuracy. The three-dimen-sional extrusion process with rectangular section is analyzed in order to verify the effectiveness of the proposed method. Comparing the results with those of the conventional method of full region analysis, the accuracy and the computational efficiency of the proposed method are then discussed.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.229-234
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• 2005

Thin-walled multicell box girders subjected to an eccentric load can he produced the three global behaviors of flexure, torsion, and distortion. Specially in railway bridges subjected to much eccentric load, it is quite important to evaluate influences of torsion and distortion. But it is very difficult to evaluate each influences of major behaviors numerically. If we can decompose an eccentric load P into flexural, torsional, and distortional forces. we can execute quantitative analysis each influences of major behaviors. Decomposition of Applied Load for Thin-walled Rectangular multi-cell box girders is reserched by Park, Nam- Hoi(Development of a multicell Box Beam Element Including Distortional Degrees of Freedom, 2003). But researches about trapezoidal multi-cell section is insufficient. So, this paper deals with multi-cell trapezoidal box girders. An expanded method, which is based on the force decomposition method for a single cell box girder given by Nakai and Yoo, is developed herein to decompose eccentric load Pinto flexural, torsional, and distortional forces. Derive formulas by decomposition of eccentric load is verified by 3D shell-modelling numerical analysis.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.4
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• pp.475-483
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• 2019

Although radar target signatures(RTS), such as range profiles have played an important role for target recognition in the X-band radar, they would be less effective when a target is designed to have low radar cross section(RCS). Recently, a number of research groups have conducted the studies on the RTS in the VHF-band where such targets can be better detected than in the X-band. However, there is a lack of work carried out on the mathematical description of the VHF-band RTS. In this paper, chirplet decomposition is employed for modeling of the VHF-band RTS and its performance is compared with that of existing scattering center model generally used for the X-band. In addition, the discriminative signal analysis is performed by chirplet parameterization of range profiles from in an ISAR image. Because the chirplet decomposition takes long computation time, its fast form is further proposed for enhanced practicality.

• Wind and Structures
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• v.9 no.6
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• pp.441-455
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• 2006

A more applicable optimization model for extracting flutter derivatives of bridge decks is presented, which is suitable for time-varying weights for fitting errors and different lengths of vertical bending and torsional free vibration data. A stochastic search technique for searching the optimal solution of optimization problem is developed, which is more convenient in understanding and programming than the alternate iteration technique, and testified to be a valid and efficient method using two numerical examples. On the basis of the section model test of Sutong Bridge deck, the flutter derivatives are extracted by the stochastic search technique, and compared with the identification results using the modified least-square method. The Empirical Mode Decomposition method is employed to eliminate noise, trends and zero excursion of the collected free vibration data of vertical bending and torsional motion, by which the identification precision of flutter derivatives is improved.