• Journal of Energy Engineering
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• v.2 no.3
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• pp.315-322
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• 1993

The generalized 23 constants of the Benedict-Webb-Rubin-Starling (BWRS) equation of state were modified to achieve accurate predictions of thermo-physical properties for polar halocarbons. Multiproperty analysis was employed to obtain an optimum set of 23 constants for individual halocarbons. The overall average absolute deviations of predicted properties for those halocarbons using the 23 constants optimized for each halocarbon with use of either an acentric factor or orientation parameters are 0.41% for density, 0.33 Kcal/kg for enthalpy and 0.39% for vapor pressure. These results show a remarkable improvement in predicting properties over the ones obtained by use of the generalized constants for all the ten halocarbons tested here.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.948-953
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• 2004

For stable walking of various biped walking robots(BWR), we need to know the kinematics, dynamics and the Zero Moment of Point(ZMP) which are not easy to analyze analytically. In this reason, we developed a simulation program for BWRs composed of 4 degree-of-freedom upper-part body and 12 degree-of-freedom lower-part of the body. To operate the motion simulator for analyzing the kinematics and dynamics of BWES, inputs for the distance between legs, base angle, choice of walking type, gaits, and walking velocity are necessary. As a result, if stability condition is satisfied by the simulation, angle data for each actuator are generated automatically, and the data are transmitted to BWRS and then, they are actuated by the motion data. Finally, we validate the performance of the proposed motion simulator by applying it to a constructed small sized BWR.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2816-2829
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• 2021

Decay heat residuals of spent nuclear fuel (SNF), i.e., the differences between calculations and measurements, were obtained previously for various spent fuel assemblies (SFA) using the Polaris module of the SCALE code system. In this paper, we compare decay heat residuals to their uncertainties, focusing on four PWRs and four BWRs. Uncertainties in nuclear data and model inputs are propagated stochastically through calculations using the SCALE/Sampler super-sequence. Total uncertainties could not explain the residuals of two SFAs measured at GE-Morris. The combined z-scores for all SFAs measured at the Clab facility could explain the resulting deviations. Nuclear-data-related uncertainties contribute more in the high burnup SFAs. Design and operational uncertainties tend to contribute more to the total uncertainties. Assembly burnup is a relevant variable as it correlates significantly with the SNF decay heat. Additionally, burnup uncertainty is a major contributor to decay heat uncertainty, and assumptions relating to these uncertainties are crucial. Propagation of nuclear data and design and operational uncertainties shows that the analyzed assemblies respond similarly with high correlation. The calculated decay heats are highly correlated in the PWRs and BWRs, whereas lower correlations were observed between decay heats of SFAs that differ in their burnups.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1296-1309
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• 2024

The aim of this work is to explore the effect of the double subdiffusion on the stability in BWRs. A BWR novel reduced order model with double subdiffusion effects: reduced order fractional model (DS-F-ROM) to describe the neutron and heat transfer processes was proposed for this study. The double subdiffusion was developed with a fractional-order two-equation model, and with different fractional-orders and relaxation times. The stability analysis was carried out using the root-locus method and change from the s to the W domain and were confirmed using the time-domain evolution of neutron flux for a unit step change in reactivity. The results obtained using the reduced fractional-order model are presented for different anomalous diffusion coefficient values. Results are compared with normal diffusion and P1 equations, which are obtained straightforwardly with DS-ROM when relaxation time tends to zero, and when the anomalous diffusion coefficient tends to one, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.15-18
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• 2000

We developed a human-sized BWR(biped walking robot) driven by a new actuator based on the ball screw which has high strength and high gear ratio. The robot overcomes the limit of the driving torque of conventional BWRs. Each leg of the robot is composed of three pitch joints and one roll joint. In all, a 10 degree-of-freedom robot with two balancing joints was developed. The BWR was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. In the performance test, the BWR performed nice motions of sitting-up and sitting-down. Through the test, we could find capability of high performance in biped-walking.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.6
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• pp.484-491
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• 2002

We developed a new type of human-sized BWR (biped walking robot) driven by a new actuator based on the ball screw which has high strength and high gear ratio. Each leg of the robot is composed of three pitch joints and one roll joint. In all, a 10 degree-of-freedom robot with two balancing joints was developed. A new type of actuator for the robot is proposed, which is composed of four bar link mechanism driven by the ball screw. The robot overcomes the limit of the driving torque of conventional BWRs. The BWR was designed to walk autonomously by adapting small DC motors for the robot actuators and has a space to board DC battery and controllers. In the performance test, the BWR performed sitting-up and down motion, and walking motion. Through the test, we found the possibility of a high performance biped-walking.

• Journal of the Korean Institute of Gas
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• v.4 no.4 s.12
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• pp.1-5
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• 2000

Cubic and non-cubic equations of state are used to calculate the vapor-liquid equilibrium(VLE) compositions for liquified natural gas(LNG) containing hydrogen sulfide. Modified Benedict-Web-Robin EOS is chosen as a non-cubic equation of state while Peng-Robinson, Soave-Redlich-Kwong EOS are used for a cubic EOS. Modified Benedict-Web-Robin EOS. showed better predictability than the cubic EOS used for the systems $H_2S/CH_4,\;H_2S/iC_4H_{10},\;H_2S/N_2$. specially for liquid composition.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.267-267
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• 2000

We developed a human-sized BWR(biped walking robot) driven by a new actuator based on the ball screw which has high strength and high gear ratio. The robot overcomes the limit of the driving torque of conventional BWRs. Each leg of the robot is composed of three pitch joints and one roll joint. In all, a 10 degree-of-freedom robot with two balancing joints was developed. The BWR was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. In the performance test, the BWR peformed nice motions of sitting-up and sitting-down. Through the test, we could find capability of high performance in biped-walking.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.181-190
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• 2008

To response climate change and Kyoto protocol and to reduce greenhouse gas emissions, marine geological storage of $CO_2$ is regarded as one of the most promising option. Marine geological storage of $CO_2$ is to capture $CO_2$ from major point sources(eg. power plant), to transport to the storage sites and to store $CO_2$ into the marine geological structure such as deep sea saline aquifer. To design a reliable $CO_2$ marine geological storage system, it is necessary to perform numerical process simulation using thermodynamic equation of state. The purpose of this paper is to compare and analyse the relevant equations of state including ideal, BWRS, PR, PRBM and SRK equation of state. To evaluate the predictive accuracy of the equation of the state, we compared numerical calculation results with reference experimental data. Ideal and SRK equation of state did not predict the density behavior above $29.85^{\circ}C$, 60 bar. Especially, they showed maximum 100% error in supercritical state. BWRS equation of state did not predict the density behavior between $60{\sim}80\;bar$ and near critical temperature. On the other hand, PR and PRBM equation of state showed good predictive capability in supercritical state. Since the thermodynamic conditions of $CO_2$ reservoir sites correspond to supercritical state(above $31.1^{\circ}C$ and 73.9 bar), we conclude that it is recommended to use PR and PRBM equation of state in designing of $CO_2$ marine geological storage process.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.191-198
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• 2008

To design a reliable $CO_2$ marine geological storage system, it is necessary to perform numerical process simulation using thermodynamic equation of state. $CO_2$ capture process from the major point sources such as power plants, transport process from the capture sites to storage sites and storage process to inject $CO_2$ into the deep marine geological structure can be simulate with numerical modeling. The purpose of this paper is to compare and analyse the relevant equations of state including ideal, BWRS, PR, PRBM and SRK equation of state. We also studied the effect of thermodynamic equation of state in designing the compression and transport process. As a results of comparison of numerical calculations, all relevant equation of state excluding ideal equation of state showed similar compression behavior in pure $CO_2$. On the other hand, calculation results of BWRS, PR and PRBM showed totally different behavior in compression and transport process of captured $CO_2$ mixture from the oxy-fuel combustion coal-fired plants. It is recommended to use PR or PRBM in designing of compression and transport process of $CO_2$ mixture containing NO, Ar and $O_2$.