• Journal of Energy Engineering
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• v.27 no.4
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• pp.50-63
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• 2018

The issue of global warming and environmental pollutant has become an international concern due to the widespread use of fossil fuels, and thus waste heat recovery technologies has become important to improve energy utilization. The global market of power generation system using industrial waste heat is rapidly growing at an average rate of 5% due to its advantage of increasing energy efficiency. In order to design an optimal waste heat recovery system, it is necessary to develop a program that offers economic evaluation of each power generating technology according to the heat source conditions. In this paper, the economic analysis module to calculate LCOE is developed and verified the reliability against NETL economic analysis results. As a result of the verification, the error rate is about 6 ~ 7%, which satisfy the accuracy for business feasibility evaluation. In order to enhance the reliability, the module was improved by applying the levelization method used by NETL. As a result of the verification of reliability, the error rate is less than 1% and the accuracy is improved.

• Journal of Plant Biotechnology
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• v.45 no.4
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• pp.347-356
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• 2018

Chionanthus retusus is a small deciduous tree that is widely used in landscaping due to its beautiful white spring flowers and ornamental value. Conventional propagation through seeds requires one to two years of breaking dormancy. The objective of this study was to determine the conditions of in vitro germination in C. retusus. In vitro embryo culture was carried out to investigate the effects of six factors: basal media (McCown Woody Plant Medium (WPM) and Murashige and Skoog (MS)); plant growth regulators (different combinations and concentrations of naphthaleneacetic acid (NAA), 6-Benzylaminopurine (BA), and gibberellic acid ($GA_3$)); embryo age (collected weekly beginning 36 days after fruit setting); low temperature pretreatment (storing $4^{\circ}C$ for 1, 2, 3, and 4 weeks); coconut additives (100, 200, and $300ml{\cdot}L^{-1}$); and genotype (grouping plants depending on their flowering nature). The basal medium used in this study was WPM with $2mg{\cdot}L^{-1-1}\;GA_3$, $20g{\cdot}L^{-1}$ sucrose, and $6g{\cdot}L^{-1}$ Agar. WPM medium mixed with $GA_3$, resulted in higher germination rate as compared to when using a combination of auxin and cytokinin. $GA_3$ at $2mg{\cdot}L^{-1}$ was the most effective of all combinations and concentrations of PGRs. WPM medium with $2mg{\cdot}L^{-1}GA_3$ resulted in better and faster germination (75.93%). Embryos collected at 57 days after fruit setting had the highest percent of germinated seeds (87.04%) while low-temperature pretreatment of fruits at $4^{\circ}C$ for two weeks produced the highest germination (95.37%). These results of this study could be an open ground for development of an efficient protocol for commercial production of the ornamental tree.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.78-85
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• 2019

The effect of various lithium sources such as LiCl, LiOH, and Li-metal on the microstructure and electrochemical properties of granulated $SiO_x$ powders were investigated. Various lithium sources were metallurgically added for a passive pre-lithiation of $SiO_x$ to improve its low initial coulombic efficiency. In spite of using the same amount of Li in various sources, as well as the same process conditions, different lithium silicates were obtained. Moreover, irreversible phases were formed without reduction of $SiO_x$, which might be from additional oxygen incorporation during the process. Accordingly, there were no noticeable electrochemical enhancements. Nevertheless, the $Li_4SiO_4$ phase changes the initial electrochemical reaction, and consequently the relationship between the microstructure and electrochemical properties of metallurgically pre-lithiated $SiO_x$ could provide a guideline for the optimization of the performance of lithium ion batteries.

• Environmental Engineering Research
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• v.23 no.4
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• pp.474-484
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• 2018

The cleaning efficiency of reverse osmosis (RO) membranes inevitably fouled by organic foulants depends upon both chemical (type of cleaning agent, concentration of cleaning solution) and physical (cleaning time, flowrate, temperature) parameters. In attempting to determine the optimal procedures for chemical cleaning organic-fouled RO membranes, the design of experiments concept was employed to evaluate key factors and to predict the flux recovery rate (FRR) after chemical cleaning. From experimental results and based on the predicted FRR of cleaning obtained using the Central Composite Design of Minitab 17, a modified regression model equation was established to explain the chemical cleaning efficiency; the resultant regression coefficient ($R^2$) and adjusted $R^2$ were 83.95% and 76.82%, respectively. Then, using the optimized conditions of chemical cleaning derived from the response optimizer tool (cleaning with 0.68 wt% disodium ethylenediaminetetraacetic acid for 20 min at $20^{\circ}C$ with a flowrate of 409 mL/min), a flux recovery of 86.6% was expected. Overall, the results obtained by these experiments confirmed that the equation was adequate for predicting the chemical cleaning efficiency with regards to organic membrane fouling.

• Food Science of Animal Resources
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• v.39 no.1
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• pp.1-12
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• 2019

The objective of this study was to establish an optimized 1D $^1H$ quantitative nuclear magnetic resonance (qNMR) analytical method for analyzing polar metabolites in meat. Three extraction solutions [0.6 M perchloric acid, 10 mM phosphate buffer, water/methanol (1:1)], three reconstitution buffers [20 mM 3-morpholinopropane-1-sulfonic acid, 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid, phosphate buffer], and two pulse programs (zg30, noesypr1d) were evaluated. Extraction with 0.6 M perchloric acid and 20 mM phosphate resulted in a stable baseline and no additional overlap for quantifying polar metabolites in chicken breast. In qNMR analysis, zg30 pulse program (without water-suppression) showed smaller relative standard deviation (RSD) and faster running time than noesypr1d (water-suppression). High-performance liquid chromatography was compared with qNMR analyses to validate accuracy. The zg30 pulse program showed good accuracy and lower RSD. The optimized qNMR method was able to apply for beef and pork samples. Thus, an optimized 1D $^1H$ qNMR method for meat metabolomics was established.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.914-920
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• 2018

The intrinsic kinetic parameters of steam-methane reforming reactions over commercial nickel-based catalyst were determined. The reaction rate equations were derived from the reaction mechanism-based Langmuir-Hinshelwood chemisorption theory. As the experimental variables for the kinetic study, the reaction temperature ranged from 630 to $750^{\circ}C$ and the steam-to-carbon ratio also varied from 2.7 to 3.5. Based on the experimental data, the efficient optimization algorithm was used to determine the intrinsic kinetic parameters due to the high-dimensional objective function. It is confirmed that the parameter estimation results showed good agreement with the experimental values. Thus, this proposed mathematical reaction model can be used as the basic information to design a catalytic reactor and to optimize operating conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.25-29
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• 2019

Various process technologies for manufacturing power inductors are under development. The core goal is to increase the mixing ratio of the soft magnetic powder in the epoxy, and to uniformly disperse it in a molding-type power inductor, manufactured by the injection molding method. In this study, we investigated the effect of dispersant and silane on the dispersion of soft magnetic metal powders in epoxy. We added 0.6 wt% of dispersant and 2.0 wt% of silane, and an excellent dispersibility resulted. Under the conditions of 0.3 wt% of dispersant and 0.5 wt% of silane, we added both dispersant and silane together to observe the effect of their interaction on dispersibility. Similarly, the addition of 0.3 wt% of dispersant and 0.1 wt% of silane resulted in a sharp increase in viscosity, considered to be due to the interaction of the dispersant and silane. The addition of 0.1 wt% of dispersant with 0.5 wt% of silane resulted in a sharp rise in viscosity, and sedimentation-height decreased sharply due to the dispersion optimization.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.638-643
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• 2019

In order to reduce the cost and weight of the soft-foamed instrument-panel (IP), it was developed the new IP which is made by the two kinds of injection methods. One is the compression-injection with back-foamed foil inserted, and the other is two-shot injection with the passenger airbag door. We named it 'IMX-IP' which means that all components ('X') of the IP with different resins are made in a mold. The development procedure of this technology was introduced (1) Design of the new injection mold through TRIZ method, (2) Optimization of the injection conditions and back foamed-foil for minimizing the foam loss and thickness deviation, (3) Development of CAE for two-shot injection compression, (4) Reliability performance test and application to the mass production. The reduction of the processes through the two-shot injection with back foamed-foil inserted made it possible to enhance soft feeling on IP and reduce the cost and weight simultaneously.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.84-93
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• 2018

Three-dimensional (3D) numerical simulations have been carried out to study how coolant injection conditions influence the cooling efficiency and projectile ejection performance in a mixture-gas ejection system (or gas-steam launch system). The 3D single-phase computational model was verified using a 1D model constructed with reference to the previous research and then a two-phase flow computation simulating coolant injection on to hot gas was performed using a DPM (Discrete Phase Model). As a result of varying the coolant flow rate and number of injection holes, cooling efficiency was improved when the number of injection holes were increased. In addition, the change of the coalescence frequency and spatial distribution of coolant droplets caused by the injection condition variation resulted in a change of the droplet diameter, affecting the evaporation rate of coolant. The evaporation was found to be a critical factor in the design optimization of the ejection system by suppressing the pressure drop while the temperature decreases inside the breech.

• Safety and Health at Work
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• v.10 no.2
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• pp.219-223
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• 2019

Background: Ice cooling vests can cause tissue damage and have no flexibility. Therefore, these two undesirable properties of ice cooling vest were optimized, and the present study was aimed to compare the impact of the optimized ice cooling vest and a commercial paraffin cooling vest on physiological and perceptual strain under controlled conditions. Methods: For optimizing, hydrogel was used to increase the flexibility and a layer of the ethylene vinyl acetate foam was placed into the inside layer of packs to prevent tissue damage. Then, 15 men with an optimized ice cooling vest, with a commercial paraffin cooling vest, and without a cooling vest performed tests including exercise on a treadmill (speed of 2.8 km/hr and slope of %0) under hot ($40^{\circ}C$) and dry (40 %) condition for 60 min. The physiological strain index and skin temperature were measured every 5 and 15 minutes, respectively. The heat strain score index and perceptual strain index were also assessed every 15 minutes. Results: The mean values of the physiological and perceptual indices differed significantly between exercise with and without cooling vests (P < 0.05). However, the difference of the mean values of the indices except the value of the skin temperature during the exercises with the commercial paraffin cooling vest and the optimized ice cooling vest was not significant (P > 0.05). Conclusions: The optimized ice cooling vest was as effective as the commercial paraffin cooling vest to control the thermal strain. However, ice has a greater latent heat and less production cost.