• Bulletin of the Korean Chemical Society
• /
• v.20 no.7
• /
• pp.815-818
• /
• 1999

The method of calculating the excess Helmholtz free energy from the averaged effective acceptance ratio for the Lennard-Jones fluid and the inverse twelve fluid has been slightly modified and applied to the two-center-Lennard-Jones liquid. The excess Helmholtz free energy is calculated directly from the average of the modified effective acceptance ratio through a single Metropolis Monte Carlo simulation. Therefore this method does not need any reference system. The results of the present method were satisfactory compared with those of the perturbation theories and the overlap ratio method.

• Korean Journal of Community Nutrition
• /
• v.22 no.4
• /
• pp.279-288
• /
• 2017

Objectives: Recommended Menu (RM) prepared according to the Target Pattern expected to meet the dietary reference intake (DRI) of nutrients. Nutritional adequacy of RM in 'DRI for Koreans 2015' were analyzed to verify whether such expectation was fulfilled. Methods: Dishes in RM are categorized by 5 food groups, and number and types of dishes for main meal and between-meals were analyzed. The energy and 12 nutrients (protein, dietary fiber, Ca, P, Fe, Na, K, vitamin A, thiamin, riboflavin, niacin and vitamin C) contents in 10 RMs were calculated using the food composition table (CD) in 'DRI for Koreans'. Energy, energy contribution ratio, and nutrient contents in 10 RMs for 18 age groups were evaluated based on the 'DRI for Koreans 2015'. Results: Number of dishes per meal were 4.83, and representative table setting consisted of cooked rice + soup (or stew) +3 side dishes. Energy contents of RM were 75~109% of estimated energy requirement (EER). None of the RM met the DRI of all 12 nutrients examined. Calcium was the most insufficient nutrient. Only 1-2 years' RM met the DRI, all the other RMs did not meet the calcium DRI. Dietary fiber and potassium contents were also insufficient in most RM. In adult male's RM, only 1 nutrient, i.e. calcium did not meet the DRI, but in female adult's RM, 5~6 nutrients did not meet the DRI. Energy contribution ratio of carbohydrate, protein, and fat in RM were 59.0~70.4%, 15.7~17.5%, 12.1~23.5%, respectively. And 4 RMs out of 10 exceeded the upper limit of acceptable macro-nutrient distribution range (AMDR) of carbohydrate and 3 RMs out of 10 RM were below the lower limit of fat AMDR. Contribution ratio of nutrients were ${\geq}40%$ by food groups were as follows: grain group in energy and carbohydrate; meat fish egg legume group in fat, protein, and niacin; vegetables group in dietary fiber, vitamin A, and vitamin C; milk dairy products group in calcium. Conclusions: RM prepared according to the Target Pattern did not meet nutritional adequacy as expected. Especially calcium, potassium, and dietary fiber contents are needed to be increased in many RMs. Further, energy content in RM needs to be adjusted for fat sugar food group assigned in Target Pattern and condiment.

• Korean Chemical Engineering Research
• /
• v.59 no.3
• /
• pp.393-398
• /
• 2021

In order to optimize the performance of a lithium-ion battery, a performance prediction modeling technique that considers various degradation factors is required. In this work, mathematical modeling was carried-out to predict the change in discharging behavior and cycle life, taking into account the cycle aging of lithium-ion batteries. In order to validate the modeling, a cycling test was performed at the charge/discharge rate of 0.25C, and discharging behavior was measured through RPT (Reference Performance Test) performed at 30 cycle intervals. The accuracy of cycle life prediction was improved by considering the break-in mechanism, one of the phenomena occurring in the BOL (beginning of life), in the model for predicting the cycle life of lithium-ion batteries. The predicted change in cycle life based on the model was in good agreement with the experimental results.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2017.10a
• /
• pp.73-73
• /
• 2017

Pyroprocessing at KAERI (Korea Atomic Energy Research Institute) consists of pretreatment, electroreduction, electrorefining and electrowinning. SFR (Sodium Fast Reactor) fuel is prepared from the electrowinning process which is composed of LCC (Liquid Cadmium Process) and Cd distillation et al. LCC is an electrochemical process to obtain actinides from spent fuel. In order to recover actinides inert anodes such as carbon material are used, where chlorine gas ($Cl_2$) evolves on the surface of the carbon material. And, stainless steel (SUS) crucible should be installed in large-scale electrowinning system. Therefore, the effect of chlorine on the SUS material needs to be studied. LiCl-KCl-$UCl_3$-$NdCl_3$-$CeCl_3$-$LaCl_3$-$YCl_3$ salt was contained in 2 kinds of electrolytic crucible having an inner diameter of 5cm, made of an insulated alumina and an SUS, respectively. And, three kinds of electrodes such as cathode, anode, reference were used for the electrochemical experiments. Both solid tungsten (W) and LCC were used as cathodes. Cd of 45 g as the cathode material was contained in alumina crucibles for the deposition experiments, where the crucible has an inner diameter of 3 cm. Glassy carbon rod with the diameter of 0.3 cm was employed as an anode, where shroud was not used for the anode. A pyrex tube containing LiCl-KCl-1mol% AgCl and silver (Ag) wire having a diameter of 0.1cm was used as a reference electrode. Electrodeposition experiments were conducted at $500^{\circ}C$ at the current densities of $50{\sim}100mA/cm^2$. In conclusion, Fe ions were produced in the salt during the electrodeposition by the reaction of chlorine evolved from the anode and Fe of the SUS crucible and thereby LCC system using SUS crucible showed very low current efficiencies compared with the system using the insulated alumina crucible. Anode shroud needs to be installed around the glassy carbon not to influence surrounding SUS material.

• Journal of the Society of Naval Architects of Korea
• /
• v.49 no.6
• /
• pp.469-477
• /
• 2012

This paper describes the characteristic analysis of ice impact force for the Arctic structure shape. In the present study an energy method has been used to predict the impact force during the ice-structure collision. This study also employs two concepts for reference contact area and normalized stress in analysis procedure. The influences of factors, such as impact velocity, full penetration depth, structure shape and ice floe size, are investigated. Full penetration occurs, particularly at lower impact velocity when ice thickness increase. But "typical size" ice floe does not expected ever to achieve full penetration during the impact procedure. The structure shape is the dominant factor in ice impact force characteristic. The results for various ice-structure collision scenarios are analyzed.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.5
• /
• pp.1746-1752
• /
• 2014

This paper presents an application of proportional-resonant (PR) current controllers in modular multilevel converter-high voltage direct current (MMC-HVDC) system under unbalanced voltage conditions. The ac currents are transformed and controlled in the stationary reference frame (${\alpha}{\beta}$-frame). Thus, the complex analysis of the positive and negative sequence components in the synchronous rotating reference frame (dq-frame) is not necessary. With this control method, the ac currents are kept balanced and the dc-link voltage is constant under the unbalanced voltage fault conditions. The simulation results based on a detailed PSCAD/EMTDC model confirm the effectiveness of the proposed control method.

• Nuclear Engineering and Technology
• /
• v.28 no.3
• /
• pp.247-256
• /
• 1996

This paper presents a new approach for assessing accident management strategies using containment event trees (CETs) developed during an individual plant examination (IPE) for a reference plant (CE type, 950 MWe PWR). Various accident management strategies to reduce risk have been proposed through IPE. Three strategies for the station blackout sequence are used as an example : 1) reactor cavity flooding only, 2) primary system depressurization only, and 3) doing both. These strategies are assumed to be initiated at about the time of core uncovery. The station blackout (SBO) sequence is selected in this paper since it is identified as one of the most threatening sequences to safety of the reference plant. The effectiveness and adverse effects of each accident management strategy are considered synthetically in the CETs. A best estimate assessment for the developed CETs using data obtained from NUREG-1150, other PRA results, and the MAAP code calculations is performed. The strategies are ranked with respect to minimizing the frequencies of Various containment failure modes. The proposed approach is demonstrated to be very flexible in that it can be applied to any kind of accident management strategy for any sequence.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.534-538
• /
• 2001

Energy storage devices with high energy density as well as high power density are expected to be developed from the point of view of compensation of fluctuating load and generated power by distributed generations such as wind turbines, photovoltaic cells and so on. SMES (Superconducting Magnetic Energy Storage) has higher power density than other energy storage methods, and secondary batteries have higher energy density than SMES. The hybrid energy storage device using SMES and secondary batteries is proposed as the energy storage method with higher power and energy density, the sharing method of power reference value for each storage device, simulation and experimental results are presented.

• Nuclear Engineering and Technology
• /
• v.53 no.1
• /
• pp.314-321
• /
• 2021

As Indonesia is rich in natural resources, nuclear power remains a low priority among energy alternatives. However, Indonesia needs to introduce nuclear power to improve the atmospheric environment and to support sustainable economic growth. This study conducted a two-stage survey of logit-probit and analytic hierarchy process to analyze the perception of Indonesian energy policymakers regarding the introduction of nuclear power, the potential for change, and key decision factors. The analysis confirms that the perception of nuclear power is positive and that the willingness to expand nuclear power can improve if negative conditions, such as underdeveloped technology level, foreign aid and assistance, and safety issues are addressed. In addition, it is confirmed that the policy makers consider political/social and environmental factors to be more important for decision-making. The results of this study can give inplications and be used as a key reference for Indonesia's nuclear power policy

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.16 no.4
• /
• pp.1-8
• /
• 2020

For a central cooling system of a medical facility composed of absorption chiller and screw chiller, the study was conducted on how to minimize the energy cost. In consideration of the energy cost, the optimal operation method in which the operation method of the heat source is changed according to the size of the cooling load was derived through simulation analysis. When applying the optimal operation method, the indoor environment, energy consumption, and energy cost were analyzed and compared with the reference operation method.