• Nuclear Engineering and Technology
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• v.56 no.11
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• pp.4843-4850
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• 2024

Realistic simulation of nuclear fuel performance requires not only validated models capable of describing the thermomechanical phenomena that take place within the fuel under irradiation conditions, but a detailed description of the thermal hydraulics of the channel surrounding the fuel rods, which provides the boundary conditions of the system. In this work, the main results and outlooks of coupling the thermal hydraulics code SubChanFlow with the fuel performance code DIONISIO are presented. To achieve this, an internal coupling was implemented, wherein DIONISIO is used as a master code controlling SubChanFlow as a thermal hydraulics subroutine replacing the simplified version already embedded in DIONISIO. Several tests were conducted to ensure the performance and quality of the coupling under normal operation conditions as a first approach. In addition, it was observed that the coupling demonstrated a significant improvement in the description of the cladding temperature and related variables, such as oxide thickness and hydrogen uptake, when compared with experimental data.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.1
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• pp.7-14
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• 2017

This study carried out a numerical analysis of the effects of hot waste water supply on the performance of a Type II absorption heat pump. There are two types of hot waste water supply, regular series flow and reverse series flow. Also it investigated the interaction between each type of flow and heat exchange solutions. As the effectiveness of heat exchange solutions increase, the steam generation and (COP) increase as well. If the effectiveness of a heat exchange solution is lower than 0.566, the steam generation rate of the reverse flow is lower than that of the regular series flow. A high effectiveness of heat exchange solution is therefore required to make a larger amount of steam in reverse series flow than with ordinary series flow. The COP difference between the two types of flow decreases with the increasing effectiveness of the heat exchange solution. Thus, a reverse flow type absorption heat pump can match the high steam generation rate and COP of the ordinary flow type when a highly effective heat exchange solution is applied.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.819-826
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• 2005

To guarantee the disinfection ability in clearwell, a value of CT is considered where C[mg/l] is disinfectant residual at the exit of clearwell and T[min] means $T_{10}$, the contact time when 10% of tracer is out of clearwell after introducing the tracer at the inlet. To meet a CT value required, increasing the C value is not recommended because high C value can increase potential of producing disinfection by product like THMs. Increasing the hydraulic efficiency surrogated by $T_{10}$ is thus an option widely recommended. Right now, it is widely adopted estimating $T_{10}$ considering LW ratio only due to the suggestions of previous researches. The authors think however there are other factors to consider including shape, flow rate, configuration of inlet and outlet, and the existence of intra basin. This study is initiated to closely look at the effects of two factor on hydraulic efficiency. The factors are shape and inlet flow velocity, i.e., inflow. For that, computational fluid dynamics (CFD) model is developed and pilot test is also carried out. The results show that at a L/W ratio, disinfection ability is overestimated with larger length in shape and higher inlet flow velocity. This suggests that in determining $T_{10}$, the shapes of clearwell and inlet flow velocity should also be considered as well as L/W ratio.

• Korean Journal of Materials Research
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• v.18 no.2
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• pp.92-97
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• 2008

In spray pyrolysis, the effects of the preparation temperature, flow rate of the carrier gas and concentration of the spray solution on characteristics such as the morphology, size, and emission intensity of $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders under long-wavelength ultraviolet light were investigated. The phosphor powders obtained post-treatment had a range of micron sizes with regular morphologies. However, the composition, crystal structure and photoluminescence intensity of the phosphor powders were affected by the preparation conditions of the precursor powders. The $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders prepared at temperatures that were lower and higher than $700^{\circ}C$ had low photoluminescence intensities due to deficiencies related to the of Cl component. The phosphor powders with the deficient Cl component had impurity peaks of $Ca_2SiO_4$. The optimum flow rates of the carrier gas in the preparation of the $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders with high photoluminescence intensities and regular morphologies were between 40 and 60 l/minute. Phosphor powders prepared from a spray solution above 0.5 M had regular morphologies and high photoluminescence intensities.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.156-161
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• 2005

Dynamic flow characteristics of a solenoid valve are affected by pressure difference in inlet and outlet of orifice, gas temperature, and supply voltage of a coil. In this paper, the dynamic flow characteristics for deviations of various conditions are studied Static and dynamic flow for variation on-time of a solenoid valve open signal are measured in basic bench test. The solenoid valve is applied to a compressed natural gas(CNG) engine test for validation of flow control performance. The experimental results show that flow of high pressure gas can controlled precisely by using a solenoid valve.

• Biomolecules & Therapeutics
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• v.13 no.2
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• pp.95-100
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• 2005

This study was performed to investigate the mechanism of cerebral blood flow of adenosine $A_{2B}$ receptor agonist in the rats, and to define whether its mechanism is mediated by nitric oxide (NO) and guanylate cyclase. In pentobarbital-anesthetized, pancuronium-paralyzed and artificially ventilated male Sprague-Dawley rats, all drugs were applied topically to the cerebral cortex. Blood flow from cerebral cortex was measured using laser-doppler flowmetry. Topical application of an adenosine $A_{2B}$ receptor agonist, 5'-N-ethylcar-boxamidoadenosine (NECA; $4{\mu}mol/l$) increased cerebral blood flow. This effect of NECA ($4{\mu}mol/l$) was blocked by pretreatment with NO synthase inhibitor, $N^G$-nitro-L-argine methvlester (L-NAME; $40{\mu}mol/l$) and guanylate cyclase inhibitor, LY-83,583 ($10{\mu}mol/l$). These results suggest that adenosine $A_{2B}$ receptor increases cerebral blood flow. It seems that this action of adenosine $A_{2B}$ receptor is mediated via the NO and the activation of guanylate cyclase in the cerebral cortex of the rats.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.115-120
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• 1998

The $TiN_x$ thin films were prepared on glass substrate by RF(radio-frequency) magnetron sputtering apparatus from a Ti target in a gaseous mixture of argon and nitrogen. In deposition, a RF power supply was used as a power source with a constant power of 240W, and the substrate was heated to $200^{\circ}C$. The films were obtained at nitrogen flow rates in the range 3-9 seem with a constant argon flow rate of 20 seem. For the films obtained, the chemical binding energy of the films was investigated by XPS (x-ray photoelectron spectroscopy) in order to analyze the chemical nature and composition of the films.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.1
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• pp.21-25
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• 1999

The TiN, thin films were prepared on glass substrate by RF(radio-frequency) magnetron sputtering apparatus from a Ti target in a gaseous mixture of argon and nitrogen. In deposition, a RF power supply was used as a power source with a constant power of 240W, and the substrate was heated to $200^{\circ}C$. The films were obtained at nitogen flow rates in the range 3-9 sccm with a constant argon flow rate of 20 secm. For the films obtained, the sheet resistance and the chemical binding energy of the films was observed by four-point-probe method and x-ray photoelectron spectroscopy(XPS) depth profiling respectively. In addition, we investigated the relationship between the surface resistance and the chemical nature of the films.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.112-117
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• 2024

Numerical simulations on the onset and the growth of viscous fingering during the miscible displacement due to the radial source flow were conducted. With introduction of a new stability criterion, the critical log-viscosity ratio, R_c, was found as a function of the Peclet number, Pe. Similar to the previous linear stability analyses, Pe made the system unstable, i.e., accelerated the onset of instability. For a large Pe system, the present numerical simulation yielded much stable results than the previous theoretical predictions This discrepancy was commonly encountered in the comparison between the theoretical prediction and the experimental finding. Additionally, the difference between the rectilinear system and the present one was also discussed. The present system was found more insensitive to the Peclet number than the rectilinear one.

• Journal of the Korean Society of Combustion
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• v.8 no.2
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• pp.7-16
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• 2003

The transfer of air pollutants between passenger room and service room in train are investigated by the computational analysis. The effects of service room temperature, inlet velocity, initial concentration and heating are studied. The flow induced by the difference of density between two rooms is found to take the major role in transfer of polluted air. Low temperature of service room enhances the polluted air flow into passenger room along the floor. Exhaust fan above the door between two rooms is not effective for this case. Strong inlet flow is found to suppress polluted air flow from service room. The heating of passenger room can promote air pollution.