• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.295-310
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• 2015

In the present study, an unstructured mixed mesh flow solver was used to conduct a numerical prediction of the aerodynamic performance of the S-76 rotor in hover. For the present mixed mesh methodology, the near-body flow domain was modeled by using body-fitted prismatic/tetrahedral cells while Cartesian mesh cells were filled in the off-body region. A high-order accurate weighted essentially non-oscillatory (WENO) scheme was employed to better resolve the flow characteristics in the off-body flow region. An overset mesh technique was adopted to transfer the flow variables between the two different mesh regions, and computations were carried out for three different blade configurations including swept-taper, rectangular, and swept-taper-anhedral tip shapes. The results of the simulation were compared against experimental data, and the computations were also made to investigate the effect of the blade tip Mach number. The detailed flow characteristics were also examined, including the tip-vortex trajectory, vortex core size, and first-passing tip vortex position that depended on the tip shape.

• International Journal of Control, Automation, and Systems
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• v.5 no.2
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• pp.117-127
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• 2007

Many real world control systems usually track several control objectives, simultaneously. At the moment, it is desirable to meet all specified goals using the controllers with simple structures like as proportional-integral (PI) and proportional-integral-derivative (PID) which are very useful in industry applications. Since in practice, these controllers are commonly tuned based on classical or trial-and-error approaches, they are incapable of obtaining good dynamical performance to capture all design objectives and specifications. This paper addresses a new method to bridge the gap between the power of optimal multiobjective control and PI/PID industrial controls. First the PI/PID control problem is reduced to a static output feedback control synthesis through the mixed $H_2/H_{\infty}$ control technique, and then the control parameters are easily carried out using an iterative linear matrix inequalities (ILMI) algorithm. Numerical examples on load-frequency control (LFC) and power system stabilizer (PSS) designs are given to illustrate the proposed methodology. The results are compared with genetic algorithm (GA) based multiobjective control and LMI based full order mixed $H_2/H_{\infty}$ control designs.

• Preventive Nutrition and Food Science
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• v.22 no.3
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• pp.241-245
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• 2017

Aged garlic has been reported to possess beneficial pharmacological activities, including anti-stress and anti-fatigue properties, and to exert protective effects on the cardiovascular system and liver. Pine needles are widely used in folk medicine and as food additives owing to their pharmacological properties such as anti-aging and anti-inflammatory effects. It has long been known that combining certain phytochemicals with other phenols or organic acids can produce synergistic effects. Therefore, the purpose of this study was to develop an optimal formula of aged garlic with added pine needle powder for improved antioxidant activity using the statistical technique of response surface methodology. The antioxidant activities of aged garlic mixed with pine needle powder were confirmed by measuring oxygen radical absorbance capacity and total polyphenol content. An optimized antioxidant formula was identified that contained 5.08 g aged garlic and 1.97 g pine needle powder. The antioxidant activities of the mixture prepared using this optimal formula were significantly higher than the predicted values according to an additive model. Hence, this study confirms that the addition of pine needle powder to aged garlic can improve its antioxidant activity. This study demonstrated an optimal mixing ratio to produce an aged garlic product with improved functionality through the addition of pine needle powder that could be successfully employed by the food industry to prepare functional foods.

• Journal of Acupuncture Research
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• v.26 no.5
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• pp.105-116
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• 2009

The use of acupuncutre has been increased worldwide, and large number of researches on acupuncture with improved quality has been conducted. Nevertheless, results of acupuncture treatment in those research tend to show mixed results, while many patients continuously seek acupuncture treatment as an adjuvant or alternatives for their health. Researchers and clinicians relevant to acupuncture are faced at this problematic discrepancy between the results of acupuncture in clinical trial including an randomized controlled trial and those of day-to-day clinical practice. The methodology of pragmatic clinical trial seems to be one of the promising research tools administering this problem especially in the area of complementary alternative medicine and traditional Korean medicine. In this study we first reviewed articles on the pragmatic clinical trial, summarized the essential concepts of 'explanatory' clinical trial 'pragmatic' clinical trial and then presented recent recommendations and arguments on this issue. We also analyzed and compared two similar pragmatic clinical trial protocols to show the readers the complexity of research designing. We hope more researchers in traditional Korean medicine will be interested in the methodology of pragmatic clinical trials and this study will serve to produce various high-quality clinical trials.

• Korean journal of food and cookery science
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• v.25 no.3
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• pp.337-344
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• 2009

The principal objective of this study was to determine the optimal mixing conditions of three different amounts of small black soybeans, sugar, and plain yogurt, for the preparation of a small black soybean smoothie. The experimental design utilized herein was based on the Central composite design methodology of response surface, which included 16 experimental points, including 2 replicates for the small black soybeans, sugar, and plain yogurt. The physiochemical and sensory properties of the test were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the mixed final product. The L value and a value decreased with increasing quantities of small black soybeans, but the b values increased with greater additions of small black soybeans. Sweetness increased with increasing amount of added sugar. The results of sensory evaluation showed very significant values for color (p<0.01), taste (p<0.05) and overall quality (p<0.05) in the predicted model. As a result, the optimum formulations by numerical and graphical methods were calculated as follows: small black soybean 79.46 g, plain yogurt 275.07 g, sugar 21.20 g.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.3166-3175
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• 2022

The most numerical investigations of the thermal-hydraulic phenomena following the loss of the residual heat removal capability during the mid-loop operation of the pressurized water reactor were performed according to simplifications and are not sufficiently accurate. To perform more accurate and more reliable predictions of thermal-hydraulic accidents in a nuclear power plant using computational fluid dynamics codes, a more detailed methodology is needed. Modelling results identified that thermal stratification and natural convection are observed. Temperatures of lower monitoring points remain low, while temperatures of upper monitoring points increase over time. The water in the heated region, in the upper unheated region and the pipe region was well mixed due to natural convection, meanwhile, there is no natural convection in the lower unheated region. Water temperature in the pipe region increased after a certain time delay due to circulation of flow induced by natural convection in the heated and upper unheated regions. The modelling results correspond to the experimental data. The developed computational fluid dynamics methodology could be applied for modelling of two-component single/two-phase natural convection and thermal stratification phenomena during the mid-loop operation of the pressurized water reactor or other nuclear and non-nuclear installations at similar conditions.

• Korean Journal of Construction Engineering and Management
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• v.17 no.4
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• pp.28-39
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• 2016

The multi-mixed complex medical care facility consisting of mainly hospital and other associated facilities such as retail, office, accommodation, healthcare services, and so on, is currently recognized as a new segment in the real estate market. This study intends to identify the customer choice criteria for the development of multi-mixed complex medical care facility. Based on literature review and expert consultation, the 3 criteria with 12 sub-criteria for customer choice have been defined. And the AHP methodology has been implemented for the development of relative weight of those criteria depending on the type of facility including 'medical facility', 'supporting facility', 'healthcare service facility' and 'other ancillary facility'. Research findings indicated the implication for the optimal combination of facility development based on the customer choice criteria controlled by facility. Accordingly, this research intends to provide the guidance toward the development of multi-mixed complex medical care facility.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.44
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• pp.93-101
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• 1997

This paper describes the application of Genetic Algorithms(GAs) to nonlinear constrained mixed optimization problems. Genetic Algorithms are combinatorial in nature, and therefore are computationally suitable for treating discrete and integer design variables. But, several problems that conventional GAs are ill defined are application of penalty function that can be adapted to transform a constrained optimization problem into an unconstrained one and premature convergence of solution. Thus, we developed an improved GAs to solve this problems, and two examples are given to demonstrate the effectiveness of the methodology developed in this paper.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.651-656
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• 1991

A mixed $H_2/H{\infty}$ design methodology is proposed for a single-input-single-output system. The reciprocal stability margin(RSM) function is defined for the perturbed plant with additive uncertainties. A suboptimal $H_2$ controller is sought to minimize the RSM function.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.174-176
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• 2005

The introduction of competition in the electricity market requires a new paradigm in the capacity planning. This paper presents a methodology on a transmission planning considering dispatch in the government view point. The proposed model is mixed integer programming that minimized operation and construction costs. The proposed idea is exorcised on a case study.