• 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.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1562-1573
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• 2024

This study rigorously examined uncertainty in the TMI-1 benchmark within the Uncertainty Analysis in Modeling (UAM) benchmark suite using the STREAM/RAST-K two-step method. It presents two pivotal advancements in computational techniques: (1) Development of an uncertainty quantification (UQ) module and a specialized library for the pin-based pointwise energy slowing-down method (PSM), and (2) Application of Principal Component Analysis (PCA) for UQ. To evaluate the new computational framework, we conducted verification tests using SCALE 6.2.2. Results demonstrated that STREAM's performance closely matched SCALE 6.2.2, with a negligible uncertainty discrepancy of ±0.0078% in TMI-1 pin cell calculations. To assess the reliability of the PSM covariance library, we performed verification tests, comparing calculations with Calvik's two-term rational approximation (EQ 2-term) covariance library. These calculations included both pin-based and fuel assembly (FA-wise) computations, encompassing hot zero-power and hot full-power operational conditions. The uncertainties calculated using both the EQ 2-term and PSM resonance treatments were consistent, showing a deviation within ±0.054%. Additionally, the data compression process yielded compression ratios of 88.210% and 92.926% for on-the-fly and data-saving approaches, respectively, in TMI fuel assembly calculations. In summary, this study provides a comprehensive explanation of the PCA process used for UQ calculations and offers valuable insights into the robustness and reliability of newly developed computational methods, supported by rigorous verification tests.

• Journal of ILASS-Korea
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• v.29 no.3
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• pp.124-133
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• 2024

Heat pumps play a crucial role in achieving the 2050 Net-Zero targets in many countries worldwide. This study addresses this issue by modifying simulation conditions and selecting relevant cases to determine optimal COP conditions using Simulink. By analyzing the efficiency of heat pump heating, utilizing Simulink models provided by MATLAB, and evaluating economic feasibility, we aim to identify the key factors influencing heat pump performance, including the heat source type, refrigerant, heating set temperature, and piping. Our goal is to establish optimal conditions for maximizing the efficiency of these eco-friendly systems while considering economic factors. In this study, it was confirmed that the heat exchanger flow arrangement of the air-source heat pump using R407c was set to cross-flow, and the diameter of the heat exchanger inner tube was set to 0.95 times the existing size, which was found to be optimal for maximizing efficiency. The COP was approximately 4.07 under these conditions.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3276-3285
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• 2024

This paper introduces the creation of a module for Uncertainty Quantification (UQ) specifically designed for VVER analysis through the implementation of the STREAM/RAST-V two-step approach. The aim was to expand the range of use by developing a UQ module tailored for analyzing VVER. This research presents two innovative computational functionalities: (1) development of a library for the pin-based pointwise energy slowing down method (PSM), and (2) extension of the analysis area to study hexagonal-geometry fuel assemblies. The proposed UQ scheme was evaluated through verification using UAM benchmark, and comparative analysis between codes using SCALE 6.2.2 for. STREAM provides an accuracy comparable to that of SCALE 6.2.2. Additionally, a PSM covariance library was utilized in the calculations, achieving 0.7941% and 0.7907% accuracies in the hot full power and hot zero power calculations, respectively. To assess the UQ sequences in the two-step method, the STREAM/RAST-V calculation scheme was verified using the STREAM lattice code. To conclude, this study furnishes comprehensive insights into the development of the UQ module within the two-step method for VVER analysis, and it validates its performance through utilization of the UAM benchmark.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.46
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• pp.265-313
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• 2010

Kyoto Protocol is an international convention on concrete performance program for UNFCCC(United Nations Framework Convention on Climate Change), which regulate and prevent to global warming and officially came into effect on February 16, 2005. Kyoto flexible mechanisms, the agreed environmental system in March 1997 in the Third Conference of Parties in UNFCCC General Assembly, Emission Trading System(ETS), Clean Development Mechanism(CDM) and Joint Implementation(JI), are key policies related to environment. In advanced countries, greenhouse gas emissions should be reduced average 5.2% level compared to 1990 in total emissions during 2008-2012. World leading carbon market finished the trial on the EU ETS I greenhouse gas emissions trading system, EU ETS II is operated regularly after 2008. World Bank leads to make 'Prototype Carbon Fund(PCF)' in April 2004, which is the world first carbon fund and a representative public carbon fund type, World Bank operate various funds including present PCF. Thus, I would like to propose as follows in relation to this study: First, in the validity analysis of carbon funds, it would be needed to analyze the Emission Reduction Cost Efficiency(ERCE) of carbon. The ERCE is a break-even value which brings the Net Present Value(NPV) to zero. NPV approach is used among projects and it enables potential projects to be compared and evaluated the ERCE on the basis of the net present value of net future cash flows. Therefore, according to results of analysis, carbon funds should be developed and invested. Second, it would be necessary to allow of issuing bonds together with carbon funds, carbon finance etc. Third, carbon funds, it would be reasonable to have a relatively enough maturity in project and as a financial derivatives in the international financial markets, it is needed various types of transactions. Fourth, it would be needed to standardize the carbon emissions trading for more efficiently. Fifth, it would be necessary to establish and invest in various kinds of domestic and overseas global carbon funds, including governments, privates, governments and privates sectors. And it is also needed to establish the medium and long term plans for carbon funds. Sixth, it would be needed to foster the advanced trade mechanisms for carbon funds in the most effective ways. Finally, carbon funds should be used in harmony with international societies to reduce global warming as the social responsible investing funds and it should be contribute to sustainable development. In addition, it would seem that carbon funds should be studied on establishing the contributable standard of sustainable development in the future assignment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.328-335
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• 2008

The system performance of NRZ format in WDM transmission system with lumped dispersion management(DM) and optical phase conjugator(OPC) is compared with that of RZ format. It is confirmed that eye opening penalty(EOP) of both NRZ and RZ format in WDM transmission system having lumped DM combined with OPC are greatly improved than those in WDM system with only OPC. The optimal net residual dispersion(NRD) in the case of RZ format is decided to so small value that path-averaged dispersion coefficient become almost zero, while that in the case of NRZ format is decided to larger value, for the best improvement of overall WDM channels. It is also confirmed that EOP in the case of RZ format is more improved than that in the case of NRZ format in lumped DM with optimal NRD. This is resulted from that lumped DM combined with OPC suppress the signal distortion due to intrachannel four-wave mixing(IFWM) and intrachannel cross phase modulation(IXPM). Consequently, lumped DM combined with OPC proposed in this paper is effective technique to mitigate intrachannel nonlinearities in WDM transmitting RZ format.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.211-216
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• 2003

Development and reproduction of Dichromothrips smithi were investigated under different temperatures, Durations of the development from egg to pre-adult of D. smithi were measured under 11 temperature ranges and it was 44.0 days at 13$^{\circ}C$ and 8.7 days at 32$^{\circ}C$. Developmental zero point and total effective temperature for the development of egg and larva, prepupa, pupa and for the complete development (egg to emergence) were 9.4, 8.9, 10.5, 10.8 and 9.5$^{\circ}C$, and 46.1, 90.1, 23.9, 41.2 and 204.4 degree days, respectively. The adult longevity was 28.3 days at 15 C and 14.3 days at 30$^{\circ}C$. The highest average fecundity per female was 69.3 at 25 C. The highest intrinsic rate of natural increase (r$\_$m/) and the highest net reproduction rate (R$\_$o/) were 0.241 at 30$^{\circ}C$ and 56.56 at 25$^{\circ}C$. The optimum temperature range for the growth of D. smithi was between 25$^{\circ}C$ and 30$^{\circ}C$.

• Applied Biological Chemistry
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• v.30 no.1
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• pp.1-8
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• 1987

The distribution of the surface charges in two kinds of peats and their physico-chemical properties have a been studied by means of the potentiometric titration and by ion adsorption in different strength of electrolytes. The organic matter contents were 43.3% and 53.7% in Yeong Yang peat and Peong Tack peat, respectively. Their X-ray diffractograms showed that quartz was dominant in both peats, and illite, kaolinite, hydrated-halloysite and feldspars were contained in a trace. Total acidic group contents was 1.257me/g in Poeng Tack peat that was a little more than of Peong Yang heat were pKa values of Yeong Yang and Poeng Tack peat were 13.1 and 12.65, respectively. The titration curves at different ionic strength of electrolytes crossed at pH 3.9 and 4.4 in Yeong Yang peat, and pH 3.8 and 4.0 in Peong Tack peat. The pH ranges of suspensions when the net surfacecharge of the peats varied from positive to negative value were $pH\;4.55{\sim}5.20\;(NaCl)$ and $pH\;3.95{\sim}5.70\;(CaCl_2)$ in Yeong Fang peat, and $pH\;4.15{\sim}5.40\;(NaCl)$ and $pH\;3.80{\sim}4.15\;(CaCl_2)$ in Peong Tack peat. Therefore it is apparent that the zero point of charge of these peats was about pH 4.0.

• Korean journal of applied entomology
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• v.41 no.2
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• pp.123-128
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• 2002

This study was carried out to test the effects of temperatures between 2$0^{\circ}C$ and 3$0^{\circ}C$ on the reproduction and development of the rice water weevil, Lissorhoptrus oryzophilus. Preoviposition periods were much longer (17.2 to 51.0 days) in the overwintering adult females collected in March than those collected in May, regardless of temperature. Oviposition periods, however, were longer (16.9 to 22.0 days) in the adult females collected in May than those collected in March at the same temperatures. The longer oviposition period observed in the females collected in May were directly associated with higher fecundity. Egg periods were shortened from as temperature increased, but the hatching rate was highest (100%) at 27$^{\circ}C$. The developmental periods from egg to adult were shortened as temperature increased : from 77.9 days at 2$0^{\circ}C$ to 38.3 days at 3$0^{\circ}C$. The developmental zero point temperature (T) and the total effect temperature (K) for egg were 16.3$^{\circ}C$ and 62.1 dgree days, respectively. The T and K from egg to adult emergence were 13.9$^{\circ}C$ and 577.6 dgree days, respectively. The adult females of the first generation did not oviposit at 2$0^{\circ}C$, but did at $25^{\circ}C$ and 3$0^{\circ}C$. The intrinsic rate of natural increase (r$_{m}$) increased as temperature augmented. Net reproductive rate (Ro) per generation was highest (75.3) at $25^{\circ}C$.>.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.4
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• pp.558-563
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• 2013

The present study was conducted to estimate energy requirements for maintenance in laying hens by using indirect calorimetry and energy balance. A total of 576 28-wk-old Nongda-3 laying hens with dwarf gene were randomly allocated into four ME intake levels (86.57, 124.45, 166.63 and 197.20 kcal/kg body weight $(BW)^{0.75}$ per d) with four replicates each. After a 4 d adaptation period, 36 hens from one replicate were maintained in one of the two respiration chambers to measure the heat production (HP) for 3 d during the feeding period and subsequent 3 d fast. Metabolizable energy (ME) intake was partitioned between heat increment (HI), HP associated with activity, fasting HP (FHP) and retained energy (RE). The equilibrium FHP may provide an estimate of NE requirements for maintenance (NEm). Results showed that HP, HI and RE in the fed state increased with ME intake level (p<0.05). Based on the regression of HP on ME intake, the estimated ME requirements for maintenance (MEm) was 113.09 kcal/kg $BW^{0.75}$ per d when ME intake equals HP. The FHP was decreased day by day with the lowest value on the third day of starvation. Except for lowest ME intake level, the FHP increased with ME intake level on the first day of starvation (p<0.05). The FHP at the two higher ME intake levels were greater than that at the two lower ME intake levels (p<0.05) but no difference was found between the two lower ME intake levels. Linear regression of HP from the fed state to zero ME intake yielded a value of 71.02 kcal/kg $BW^{0.75}$ per d, which is higher than the extrapolated FHP at zero ME intake (60.78, 65.23 and 62.14 kcal/kg $BW^{0.75}$ per d for the first, second and third day of fasting, respectively). Fasting time, lighting schedules, calculation methods and duration of adaptation of hens to changes in ME intake level should be properly established when using indirect calorimetry technique to estimate dietary NE content, MEm and NEm for laying hens.