• Journal of Hydrogen and New Energy
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• v.28 no.5
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• pp.453-458
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• 2017

A study on the modeling of the methane Chemical Looping Reforming system was carried out. It is aimed to predict the temperature and concentration behavior of the product through modeling of oxygen carrier fixed bed reactors composed of multiple stacks. In order to design the reaction system, first of all, the flow rate of the hydrogen to be produced was calculated. The flow rate ratio of the oxidation/reduction reactor was calculated considering the heat of reaction between adjacent reactors. Finally, in this paper, kinetic model including empirical coefficients was suggested.

• Structural Engineering and Mechanics
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• v.60 no.2
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• pp.301-312
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• 2016

In a concrete member under pure tension, the stress in concrete is uniformly distributed over the whole concrete section. It is supposed that a local bond failure occurs at each crack, and there is a relative slip between steel and surrounding concrete. The compatibility of deformation between the concrete and reinforcement is thus not maintained. The bond transfer length is a length of reinforcement adjacent to the crack where the compatibility of strain between the steel and concrete is not maintained because of partially bond breakdown and slip. It is an empirical measure of the bond characteristics of the reinforcement, incorporating bar diameter and surface characteristics such as texture. Based on results from a series of previously conducted long-term tests on eight restrained reinforced concrete slab specimens and material properties including creep and shrinkage of two concrete batches, the ratio of final bond transfer length after all shrinkage cracking, to THE initial bond transfer length is presented.

• Smart Structures and Systems
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• v.9 no.5
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• pp.441-459
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• 2012

Identification of vibration parameters from the analysis of the dynamic response of a structure plays a key role in current health monitoring systems. This study evaluates the capabilities of the recently developed Synchrosqueezed Wavelet Transform (SWT) to extract instant frequencies and damping values from the simulated noise-contaminated response of a structure. Two approaches to estimate the modal damping ratio from the results of the SWT are presented. The results obtained are compared to other signal processing methods based on Continuous Wavelet (CWT) and Hilbert-Huang (HHT) transforms. It was found that the time-frequency representation obtained via SWT is sharped than the obtained using just the CWT and it allows a more robust extraction of the individual modal responses than using the HHT. However, the identification of damping ratios is more stable when the CWT coefficients are employed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.1
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• pp.1-8
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• 1989

This paper treats the temperature effectiveness of the two-fluid counterflow regenerator in a rotary type. To avoid continual interpolation and to obtain the simple result in calculating that, it obtained the particular solution for the direct-transfer-type counterflow heat exchanger by the graphical procedures. Also, it introduced the empirical formula for the influence of the ratio of rotor matrix to minimum working fluid heat capacity rate with the particular solution induced. Particularly, substituting the published results of temperature effectiveness into the program, it obtained the simple and convenient equation which can applicate in the counterflow regenerator in a rotary type. To compare and discuss the results induced, selecting the regenerative air preheater and applying the their running datum and specifications to the related results, it shows that the above results are agree with the published results within absolute relative error, 3.0%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.109-116
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• 1999

To establish optimum cycle of the inverter-driven heat pump with a variation of frequency, the bypass orifice, which is a short tube having a bypass hole in the middle, was designed and tested. Flow characteristics of the bypass orifice were measured as a function of orifice geometry and operating conditions. Flow trends with respect to frequency were compared with those of short tube orifices and capillary tubes. Generally, the bypass orifice showed the best flow trends among them, that will enhance the seasonal energy efficiency ratio of an inverter heat pump system. Based on experimental data, the semi-empirical flow model was developed to predict mass flow rate through bypass orifices. The maximum difference between measured data and model's prediction was within ${\pm}5%$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.929-935
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• 1997

The total energy of fish movement and the maximum burst swimming speed were estimated and formulated in accordance with body length and water temperature for several species in fisheries by empirical methods and also by using published results. Under the assumption of swimming energy reserve of a fish at the initial rest state, the swimming endurance of fish with different body lengths, swimming speeds and angular velocity was calculated using the relevant equations under similar conditions in tank experiments as well as natural conditions in field. Relative swimming energy efficiency or the transition swimming speed between red and white muscle for energy consumption was represented as a trigonometric function of swimming speed ratio. Therefore, this model does closely approach the actual swimming abilities and their limits especially in relation to the fishing gear operation and allow for the greater vitality of the wild fish in the fields.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.845-850
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• 2007

The empirical AISC panel zone thickness provision$(t_z\geq(d_z+w_z)$/90) to prevent the cyclic shear buckling of the panel zone was proposed based on the test data of Krawinkler et al. (1971) and Bertero et al. (1973) However, no published records of the equation development or any other background information appear to be available. The calibrated finite element analysis results of this study indicated that the AISC provision was not reasonable. In this study, through including the effects of the column axial force and the aspect ratio of the panel zone, a new equation for the relative strength between the beam and the panel zone was proposed such that the proposed equation can prevent the panel zone shear buckling and reduce the potential fracture associated with the kinking of the column flanges.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.74-77
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• 2011

PSPICE modeling of a commercial LED driver IC (TOP245P) and PC817A optocoupler is proposed for the switch-mode power supply (SMPS) (applicable to LED driver) design and simulation. An analog behavioral model of the TOP245P IC including the shunt regulator, under-voltage(UV) detection, over-voltage(OV) shut-down and SR flip-flop is developed by using PSPICE. The empirical equation of PC817A current transfer ratio (CTR) is fitted from the datasheet of PC817A. Two types of SMPSs are simulated with the averaged-model and switching-model. The simulation results by the proposed PSPICE models are in good agreement with those in the data sheet and an experimental data.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.1
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• pp.105-113
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• 2005

I investigate whether the efficient ratios used as the proxies of the agency costs maintained by Ang et al.(2000) is significant. Utilizing a sample of 77 manufacturing companies listed on the KOSDAQ from the TS2000 of the KSDA, The results are as follows. Agency costs are found to be decreasing with the ownership share of controlling shareholders and accounting performance becomes higher. But firm value measured by Tobin's Q ratio becomes lower according as the ownership of the controlling shareholders increases. If agency costs decrease in proportion to controlling shareholder's share, firm value should be higher according to the agency theory by Jensen and Meckling(I976). But the results of the empirical test of this study are inconsistent with Jensen and Meckling's(1976). Therefore the following study on the more useful proxies stand for agency costs should be needed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.46
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• pp.73-91
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• 1998

The ratio of Industrial Accident in Korea has been inclined to decrease for recent ten years since industrialization beginnings of Korea. But it is still in high level viewed from international comparison. Up to now, we depended on classical method Accident as the phenomenical and inductive result. And we searched for the counter plan in the basis of the result by this method. But, in this research, we analyzed the distinctions which the structure of the occurrence of Industrial Accident using new model in order to approach the cause of Industrial accident of Korea more basically. In this new model, I am going to arrange the controllable variables in the factors of Industrial Accident and to analyze the effect of these controllable variables in the structure of Industrial Accident.