• Journal of the Korean Society for Marine Environment & Energy
• /
• v.13 no.3
• /
• pp.187-197
• /
• 2010

Carbon dioxide Capture and Storage(CCS) is regarded as one of the most promising options to response climate change. CCS is a three-stage process consisting of the capture of carbon dioxide($CO_2$), the transport of $CO_2$ to a storage location, and the long term isolation of $CO_2$ from the atmosphere for the purpose of carbon emission mitigation. Up to now, process design for this $CO_2$ marine geological storage has been carried out mainly on pure $CO_2$. Unfortunately the $CO_2$ mixture captured from the power plants and steel making plants contains many impurities such as $N_2$, $O_2$, Ar, $H_2O$, $SO_2$, $H_2S$. A small amount of impurities can change the thermodynamic properties and then significantly affect the compression, purification, transport and injection processes. In order to design a reliable $CO_2$ marine geological storage system, it is necessary to analyze the impact of these impurities on the whole CCS process at initial design stage. The purpose of the present paper is to compare and analyse the relevant physical property models including BWRS, PR, PRBM, RKS and SRK equations of state, and NRTL-RK model which are crucial numerical process simulation tools. To evaluate the predictive accuracy of the equation of the state for $CO_2-SO_2$ mixture, we compared numerical calculation results with reference experimental data. In addition, optimum binary parameter to consider the interaction of $CO_2$ and $SO_2$ molecules was suggested based on the mean absolute percent error. In conclusion, we suggest the most reliable physical property model with optimized binary parameter in designing the $CO_2-SO_2$ mixture marine geological storage process.

• Korean Journal of Food Science and Technology
• /
• v.40 no.4
• /
• pp.406-411
• /
• 2008

This study was conducted to examine the quality enhancement of fermented soybean pastes (cheonggukjang) using microorganisms with high enzyme activities and proper experimental design. The microorganisms for soybean paste fermentation were selected from a specific area of Gyeonggi and were idenlified by 16S rDNA sequence analysis. To prepare the cheonggukjang, an optimum mixing ratio of selected microorganisms was determined using contour plots and numerical optimization methods. A total of 39 microorganisms were isolated from the soybean paste, consisting primarily of Bacillus subtilis and Bacillus licheniformis, and no mold was found. Three microorganisms showing high enzyme activities were selected and used to formulate an optimum mixing ratio for cheonggukjang preparation. Based on levels of amino-nitrogen, ammonium-nitrogen, antioxidant activity values, and sensory preference results, the optimum mixing ratio of 50% of Bacillus sp. SC-1 and 50% SC-3 was suggested for the manufacture of high quality of cheonggukjang.

• Journal of the Korea Society for Simulation
• /
• v.17 no.4
• /
• pp.219-227
• /
• 2008

The DEVS (Discrete Event Systems Specification) formalism supports specification of discrete event models in a hierarchical modular manner. MATLAB/Simulink is widely used for modeling, simulating and analyzing continuous and discrete time systems. This paper proposes a realization of the DEVS formalism in MATLAB/ Simulink. The proposed design enables to use a great amount of mathematical packages and functions included in MATLAB /Simulink. The design is also employed as real time simulation and hybrid system simulation which is a mixture of continuous systems and discrete event systems. The paper introduces Simulink-DEVS model, in which a simulation algorithm is embedded. The model consists of a Simulink-atomic model and a Simulink-coupled model. In addition, the time advance algorithm to simulate the model is suggested. The algorithm handles the time synchronization and the accommodation of different concepts specific to continuous and discrete event models. Two experimental results are presented for a pure discrete event model and a hybrid model.

• Journal of the Korean Dietetic Association
• /
• v.19 no.1
• /
• pp.1-13
• /
• 2013

The purpose of this study was to determine the optimal mixing condition of tomato powder and sugar for producing chiffon cake. The experiment was designed according to the central composite design of response surface, which yielded ten experimental points, including two replicates. Physiochemical and sensory properties were measured, and theses values applied to mechanical models. A canonical form and perturbation plot showed the influence of each ingredient on the final product mixture. The results of the physiochemical analysis of each sample showed significant differences in sweetness (P<0.01), color L (P<0.001), color a (P<0.001), color b (P<0.05), hardness (P<0.05), and cohesiveness (P<0.01). The sensory measurements were significantly different in color (P<0.05), appearance (P<0.05), flavor (P<0.05), sweetness (P<0.01), moistness (P<0.05), and overall acceptability (P<0.05). The optimal formulation, calculated using the numerical and graphical method, was determined to be 59.27 g tomato powder and 285.66 g sugar. The sensory evaluation showed significantly higher preferences in the color, flavor, appearance, texture, sweetness, tenderness, moistness and overall quality of the optimized chiffon cake compared to the controlled chiffon cake. The optimized chiffon cake also showed a high antioxidative activity compared to the controlled chiffon cake. Our results show that chiffon cake prepared with tomato powder enhances sensory characteristics and antioxidative activity.

• ETRI Journal
• /
• v.24 no.3
• /
• pp.211-220
• /
• 2002

This study characterizes an oxide etching process in a magnetically enhanced reactive ion etching (MERIE) reactor with a $CHF_3/CF_4$ gas chemistry. We use a statistical $2^{4-1}$ experimental design plus one center point to characterize the relationships between the process factors and etch responses. The factors that we varied in the design include RF power, pressure, and gas composition, and the modeled etch responses were the etch rate, etch selectivity to TiN, and uniformity. The developed models produced 3D response plots. Etching of $SiO_2$ mainly depends on F density and ion bombardment. $SiO_2$ etch selectivity to TiN sensitively depends on the F density in the plasma and the effects of ion bombardment. The process conditions for a high etch selectivity are a 0.3 to 0.5 $CF_4$ flow ratio and a -600 V to -650 V DC bias voltage according to the process pressure in our experiment. Etching uniformity was improved with an increase in the $CF_4$ flow ratio in the gas mixture, an increase in the source power, and a higher pressure. Our characterization of via etching in a $CHF_3/CF_4$ MERIE using neural networks was successful, economical, and effective. The results provide highly valuable information about etching mechanisms and optimum etching conditions.

• Nuclear Engineering and Technology
• /
• v.54 no.10
• /
• pp.3855-3863
• /
• 2022

An evaluation of the radiation shielding performance of high-Z-particle-loaded polylactic acid (PLA) composite materials was pursued. Specimens were produced via fused deposition modeling (FDM) using copper-PLA, steel-PLA, and BaSO₄-PLA composite filaments containing 82.7, 75.2, and 44.6 wt% particulate phase contents, respectively, and were tested under broad-band flash x-ray conditions at the Sandia National Laboratories HERMES III facility. The experimental results for the mass attenuation coefficients of the composites were found to be in good agreement with GEANT4 simulations carried out using the same exposure conditions and an atomistic mixture as a model for the composite materials. Further simulation studies, focusing on the Cu-PLA composite system, were used to explore a shield design parameter space (in this case, defined by Cu-particle loading and shield areal density) to assess performance under both high-energy photon and electron fluxes over an incident energy range of 0.5-15 MeV. Based on these results, a method is proposed that can assist in the visualization and isolation of shield parameter coordinate sets that optimize performance under targeted radiation characteristics (type, energy). For electron flux shielding, an empirical relationship was found between areal density (AD), electron energy (E), composition and performance. In cases where ${\frac{E}{AD}}{\geq}2MeV{\bullet}cm{\bullet}g^{-1}$, a shield composed of >85 wt% Cu results in optimal performance. In contrast, a shield composed of <10 wt% Cu is anticipated to perform best against electron irradiation when ${\frac{E}{AD}}<2MeV{\bullet}cm{\bullet}g^{-1}$.

• Food Science of Animal Resources
• /
• v.43 no.2
• /
• pp.232-244
• /
• 2023

We investigated the effects of different phosphate replacements on the quality of ground pork products cured with sodium nitrite or radish powder to determine their potential for achieving clean-label pork products. The experimental design was a 2×5 factorial design. For this purpose, the ground meat mixture was assigned into two groups, depending on nitrite source. Each group was mixed with 0.01% sodium nitrite or 0.4% radish powder together with 0.04% starter culture, and then processed depending on phosphate replacement [with or without 0.5% sodium tripolyphosphate; STPP (+), STPP (-), 0.5% oyster shell calcium (OSC), 0.5% citrus fiber (CF), or 0.5% dried plum powder (DPP)]. All samples were cooked, cooled, and stored until analysis within two days. The nitrite source had no effect on all dependent variables of ground pork products. However, in phosphate replacement treatments, the STPP (+) and OSC treatments had a higher cooking yield than the STPP (-), CF, or DPP treatments. OSC treatment was more effective for lowering total fluid separation compared to STPP (-), CF, or DPP treatments, but had a higher percentage than STPP (+). The STPP (+) treatment did not differ from the OSC or CF treatments for CIE L^* and CIE a^*. Moreover, no differences were observed in nitrosyl hemochrome content, lipid oxidation, hardness, gumminess, and chewiness between the OSC and STPP (+) treatments. In conclusion, among the phosphate replacements, OSC addition was the most suitable to provide clean-label pork products cured with radish powder as a synthetic nitrite replacer.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.3
• /
• pp.217-226
• /
• 2009

Marine geological storage of $CO_2$ is regarded as one of the most promising options to response climate change. Marine geological storage of $CO_2$ is to capture $CO_2$ from major point sources, to transport to the storage sites and to store $CO_2$ into the marine geological structure such as deep sea saline aquifer. Up to now, process design for this $CO_2$ marine geological storage has been carried out mainly on pure $CO_2$. Unfortunately the captured $CO_2$ mixture contains many impurities such as $N_2$, $O_2$, Ar, $H_2O$, $SO_x$, $H_2S$. A small amount of impurities can change the thermodynamic properties and then significantly affect the compression, purification and transport processes. In order 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 the present paper is to compare and analyse the relevant equations of state including PR, PRBM, RKS and SRK equation of state for $CO_2-N_2$ mixture. To evaluate the predictive accuracy of the equation of the state, we compared numerical calculation results with reference experimental data. In addition, optimum binary parameter to consider the interaction of $CO_2$ and $N_2$ molecules was suggested based on the mean absolute percent error. In conclusion, we suggest the most reliable equation of state and relevant binary parameter in designing the $CO_2-N_2$ mixture marine geological storage process.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.5
• /
• pp.55-63
• /
• 2018

Recently, the use of duplex stainless steel which with a two-phase microstructure (equal mixture of ferrite and austenite) has been increased in a variety of industrial fields due to higher strength leading to weight saving, greater corrosion resistance(particularly, stress corrosion cracking) and lower price. However, currently, stainless steels are not included in the structural materials of Korean Building Code and corresponding design standards are not specified. In this paper, experimental studies have been performed to investigate the structural behaviors of duplex stainless steel (STS329FLD) bolted connection with two bolts for providing the design data. Main variables are shear connection type (single shear and double shear) and end distance parallel to the direction of applied force. Fracture modes at the final step of test were classified into typical block shear fracture, tensile fracture and curling. Curling occurrence in single shear connection led to ultimate strength drop by up to 20%. Test strengths were compared with those by current design specifications such as AISC/AISI/KBC, EC3 and AIJ and proposed equations by existing studies. For specimens with no curling, Clement & Teh's equation considering the active shear plane provided a higher strength estimation accurancy and for specimens with curling, Kim & Lim's equation considering strength reduction by curling was also overly unconservative to predict the ultimate strength of curled connections.

• The Korean Journal of Food And Nutrition
• /
• v.20 no.1
• /
• pp.1-8
• /
• 2007

Tortillas were prepared using rice and wheat flour. The experimental design incorporated thee independent variables(rice, wheat flour and moisture content) producing 14 samples of different proportions of each variable for each tortilla. The following were analysed using Design Expert 6 to unveil the influences of these variables on tensile strength and color(L, a, b). Results indicated that tensile strength increased with increasing rice and wheat flour content, however, decreased with increasing moisture content. Lighteness(L), of the tortilla increased with increased rice content whereas yellowness(b) increased with increased wheat flour content. The model suggests that tensile strength and color(L, a, b) in tortillas are highly correlated(SD Comment - give correlation coefficient and p-value). As well, the numerical optimization method suggests that the ratio of wheat flour to rice flour to moisture content which maximizes the three responses(tensile strenth, L and b) is 18.26 : 33.92 : 39.24%, 28.15 : 25.77 : 37.50%.