• Korean Journal of Food Science and Technology
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• 제40권5호
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• pp.540-544
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• 2008

In this study, response surface methodology was employed in order to optimize the limonin and nomilin extraction conditions from citron seed. The independent variables were extraction temperature, extraction time, and shaking velocity. The yield of limonin and nomilin increased with increased extraction temperature and time. The extraction effects on the limonin and nomilin were higher at extraction temperature (p<0.01). The predicted extraction conditions were validated through actual experiments. The predicted conditions were as follows: $49.7^{\circ}C$ of extraction temperature, 3.3 hr of extraction time, and 400.6 rpm of shaking velocity for the maximum limonin contents (353.9 mg/100 g) and $50.3^{\circ}C$, 3.5 hr, and 399.9 rpm for the maximum nomilin contents (214.5 mg/100 g). The experimental values of limonin and nomilin contents at the predicted conditions were 338.8 and 219.5 mg/100 g, respectively. The predicted values at the optimized conditions were acceptable when compared to the experimental values.

• Journal of the Korea institute for structural maintenance and inspection
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• 제22권1호
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• pp.167-175
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• 2018

This research deals, The characteristics of mechanics and behavior of the tube structural systems, It has been investigated and considered conventional theory and case models, It has shown the suitability, The best location, And optimal shape of the unit module system, Considered variables materials of stiffness increase and decrease in hybrid tube structural systems this study carried out adapting analysis of statistical concepts. In a concrete way, This study exams the effect of reducing horizontal displacement and the shear lag phenomenon, Also, The purpose of this study is to utilize the basic data on the design and study of future high-rise hybrid structural system using this research. As a result, The framed- tube structural system does not effectively cope with horizontal behavior of high-rise buildings, The results of using varying material tested resistance factors and lateral loads in hybrid tube structural system, When each material is compared Bracing material is identified as a key factor in lateral behavior. In a ratio of material quantity framed-tube structural system, The level of sensitivity affecting the horizontal displacement is greater then the beam's column, In case of braced tube structural system, Braced appeared to be most sensitive in comparison of material quantity ratio in columns and beams.

• Journal of the Earthquake Engineering Society of Korea
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• 제12권3호
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• pp.1-10
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• 2008

The seismic performance of a structure designed without consideration of seismic loading can be effectively enhanced through seismic rehabilitation. The appropriate level of rehabilitation should be determined based on the decision criteria that minimize the anticipated earthquake-related losses. To estimate the anticipated losses, seismic risk analysis should be performed considering the probabilistic characteristics of the hazard and the structural damage. This study presents the decision procedure in which the probabilistic seismic demand model is utilized for the effective estimation and minimization of the total seismic losses through seismic rehabilitation. The probability density function and the cumulative distribution function of the structural damage for a specified time period are established in a closed form, and are combined with the loss functions to derive the expected seismic loss. The procedure presented in this study could be effectively used for making decisions on the seismic rehabilitation of structural systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제39권11호
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• pp.1123-1129
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• 2015

A pair of two-way valves typically is used in automotive washing machines, where the water flow direction is frequently reversed and highly pressurized clean water is sprayed to remove the oil and dirt remaining on machined engine and transmission blocks. Although this valve system has been widely used because of its competitive price, its application is sometimes restricted by surging effects, such as pressure ripples occurring in rapid changes in water flow caused by inaccurate valve control. As an alternative, one three-way reversing valve can replace the valve system because it provides rapid and accurate changes to the water flow direction without any precise control device. However, a cavitation effect occurs because of the complicated bottom plug shape of the valve. In this study, the cavitation index and percent of cavitation (POC) were introduced to numerically evaluate fluid flows via computational fluid dynamics (CFD) analysis. To reduce the cavitation effect generated by the bottom plug, the optimal shape design was carried out through a parametric study, in which a simple computer-aided engineering (CAE) model was applied to avoid time-consuming CFD analysis and difficulties in achieving convergence. The optimal shape design process using full factorial design of experiments (DOEs) and an artificial neural network meta-model yielded the optimal waist and tail length of the bottom plug with a POC value of less than 30%, which meets the requirement of no cavitation occurrence. The optimal waist length, tail length and POC value were found to 6.42 mm, 6.96 mm and 27%, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제17권1호
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• pp.468-473
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• 2016

The aim of this study was to measure the opening force of an access door of a pressurized smoke control zone and verify the reliability of the opening force. For the access door opening force, the opening load of the access door was measured before and after pressurized air had entered the smoke control zone. The reliability of the measured values was verified using the Anderson Darling's statistical analysis method of the Minitab Program. Because the analyzed P values were greater than 0.05 except for some floors before and after the operation of the smoke control equipment, the opening force was found to have 95% reliability. The normal distribution of the measured values showed no relationship with the operation of the smoke control equipment and the precision of the force gauge was believed to be reliable. The major factors for the optimal design of the pressurized smoke control equipment include the precision and reliability of the force gauge, the correct posture of the measuring person, and the same conditions for access doors. Therefore, a digital force gauge is believed to be suitable for measuring the opening force of the access door of a pressurized smoke control zone. In addition, standardization of the posture of a measuring person, the setup of the initial opening force of an access door, etc., are major variables for effective measurements of the door opening force of an access door.

• Applied Chemistry for Engineering
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• 제34권2호
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• pp.137-143
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• 2023

In this study, natural surfactants were extracted from Medicago sativa L. The O/W emulsification processes with the extracted natural surfactants were optimized using central composite design model-response surface methodology (CCD-RSM) and a 95% confidence interval was used to confirm the reasonableness of the optimization. Herein, independent parameters were the ratio of saponins to total surfactant (P), amount of surfactant (W), and emulsification speed (R), whereas the reaction parameters were the emulsion stability index (ESI), mean droplet size (MDS), and viscosity (V). Using the multiple reaction, the optimal conditions for the ratio of saponins to total surfactant, amount of surfactant, and emulsification speed for O/W emulsification were 49.5%, 9.1 wt%, and 6559.5 rpm, respectively. Under these optimal conditions, the expected values of ESI, MDS, and V as the reaction parameters were 89.9%, 1058.4 nm, and 1522.5 cP, respectively. The values of ESI, MDS, and V from these expected values were 88.7%, 1026.4 nm, and 1486.5 cP, respectively, and the average experimental error for validating the accuracy was about 2.3 (± 0.4)%. Therefore, it was possible to design an optimization process for evaluating the O/W emulsion process with Medicago sativa L. using CCD-RSM.

• Journal of the Korea institute for structural maintenance and inspection
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• 제28권5호
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• pp.10-19
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• 2024

In this study, FEM analysis was performed with the goal of optimal design of corrugated CFRP panels reinforcing H-shaped beams with slender plate webs. The buckling reinforcement performance of corrugated CFRP panels according to various specifications was evaluated, and in particular, a new reinforcement method was proposed by analyzing the effect of the ratio of vertical reinforcement according to the net height of the abdomen of the H-type beam on the location of the first elastic buckling mode. To minimize the amount of CFRP used, the attachment angle was set to 45 degrees. Furthermore, parameter analysis was performed according to changes in the specifications of the corrugated CFRP panel, and the buckling reinforcement performance of the corrugated CFRP panel was evaluated through the ductility factor. In addition, we attempted to use the material efficiently by simultaneously considering the maximum load and ductility factor along with the volume of the corrugated CFRP panels. It was confirmed that the model with two or three-layer CFRP laminate have a high ductility factor and efficient use of materials, and that the buckling reinforcement performance is predominantly affected by the length and height of the corrugated CFRP panel rather than the width.

• Journal of the Korean Society for Marine Environment & Energy
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• 제13권3호
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• pp.187-197
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• 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.

• Journal of the Korean Society for Marine Environment & Energy
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• 제12권3호
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• pp.217-226
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• 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.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.80-80
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• 2017

국내에서 대부분 생산되는 사료(사일리지) 수확 작업은 베일 생산 및 비닐 래핑 작업이 독립적으로 수행되고 있어서 비효율적이다. 본 연구에서 개발한 조사료 수확기는 수집, 롤링, 베일 네트 생성, 래핑, 래핑 종료 및 베일 방출작업을 통합적으로 수행하도록 설계-제작하였다. 통합형 다목적 조사료수확기의 설계는 3D 디자인 툴 (CATIA V5R18)을 이용하여 실시하였으며, 기구부 23 파트 어셈블리, 전기제어 어셈블리, 유압요소기술을 통합하여 통합시작기를 제작하였다. 기초 프레임, 오거장치파트, 픽업장치파트, 하부롤러파트, 상부롤러파트, 하부 프레임 및 주행부 파트, 래핑회전파트, 롤러부 구동 동력부, 유압파트, 전기제어파트, 드로우바파트, 체결 및 컨트롤러 파트 등 25개 파트로 구성되어 있다. 본 연구에서 개발한 시작기의 견인력 및 소요동력 분석은 선행 연구에서 사용한 Brixius (1987) 제안 모델을 체택하여 분석하였다. 이 Brixius 제안 모델은 견인력 예측에서 토양변수 및 토양강도 특성을 나타내는 원추지수 (Cone Index, CI)를 이용하여 트랙터의 견인력 예측에 사용하였다. 또한 트랙터-조사료수확기 시스템의 소요 견인력을 예측하는데 있어, 트랙터-조사료수확기 시스템이 운용되는 토양조건과 트랙터의 마력에 따른 소요 견인력 특성을 분석하기 위해 대표적으로 3수준의 토양조건 (CI: 356 kPa, 543 kPa, 1,429 kPa)을 적용하였으며, 베일의 개당 최대무게는 최고 수준인 옥수수 기준으로 800 kgf를 적용하였다. 본 연구에서 적용된 3수준의 CI 조건은 연구팀에서 선행연구과정 (토양특성에 따른 최적 경운작업 시스템 개발, 2006)에서 분석한 전국 10개 지역의 33개 지점의 경반층 CI지수의 측정범위인 1,050-3,170 kPa에 대해 견인력이 많이 소요되는 열악한 조건 수준을 적용하였다. 각 작업에 사용된 소요동력은 베일 작업시 (ASABE D497.7, 2011) 그리고 래핑작업시 (Zhortuylov et al., 2013)를 사용하였으며 두 소요마력을 트랙터-조사료 수확기 시스템의 필요 소요마력의 합계로 계산하였다. 트랙터-조사료수확기 시스템의 최소 소요 동력, 차축 소요 동력과 PTO 소요 동력을 Zoz and Grisso (2003)을 이용하여 계산하였다. 연구에서는 기본적으로 ASAE의 작업속도 및 작업효율을 적용하였는데, 적용된 조사료수확기의 현장 작업효율은 60-86%의 범위이고 일반적으로 70%를 적용하고 이때 작업속도는 2.5-8.0 km/h이며 전형적으로 5.0 km/h를 기준하고 있다. 자주식 (SP; sief-propelled machine) 조사료수확기의 경우 작업속도가 2.5-10.0 km/h의 범위에서 작업효율은 60-85% 범위이다. 적용되는 조사료 수확기의 작업효율인 60-85% 범위에서 일반적으로 적용되는 작업효율인 70%를 적용하면 트랙터의 소요동력은 95hp를 적정 작업환경으로 하였다.