• Geomechanics and Engineering
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• v.34 no.1
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• pp.87-102
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• 2023

The cover plate and the building loads often make the semi-covered deep excavations with existing buildings bearing asymmetric load, presenting different deformation characteristics with normal excavations, which is not absolutely clear in current studies. Based on a typical engineering, the building storeys, the basement storeys, the pile length, the existence of the cover plate (CP) and the depth of the diaphragm walls (DW) were selected as variables, and 44 groups of simulation were designed to study the influence of existing buildings and the semi-covered supporting system on the deformation of the excavations. The results showed that the maximum lateral displacement of DW, δ_hm, and the depth of δ_hm, H_m, are affected seriously by the building storeys and the basement storeys. Asymmetric structures and loading lead to certain lateral displacement of DW at the beginning of excavation, resulting in different relationships between δ_hm and excavation depth, H. The maximum surface settlement outside the pit, δ_vm, increases significantly and the location, d_m, moves away from the pit with the building storeys increases. δ_vm has a quadratic correlation with H due to the existing buildings. CP and building load will affect the style of the lateral displacement curve of DW seriously in different aspects.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.4
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• pp.497-504
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• 2008

This study was conducted for the optimization of ingredients in salad dressing using Bokbunja (Rubus coreanum Miquel) juice. The experiment was designed according to the D-optimal design of mixture design, which included 14 experimental points with 4 replicates for three independent variables (Bokbunja juice $15.70\sim47.10%$, oil $23.50\sim39.20%$, vinegar $3.90\sim19.60%$). The compositional and functional properties of the prepared products were measured, and these values were applied to the mathematical models. A canonical form and trace plot showed the influence of each variable on the quality attribute of final mixture product. By the use of F-test, viscosity, color values (L, a, and b), emulsion stability and sensory characteristics (color) were expressed by a linear model, while the color values (L) and sensory characteristics (smell, taste, and overall acceptance) were by a quadratic model. The optimum formulations by numerical and graphical method were analogous: Bokbunja juice, oil and vinegar of 36.02%, 26.48%, and 12.00% by numerical method, respectively; those of 36.00%, 26.44%, and 12.06% by graphical method, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.3
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• pp.299-306
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• 2002

The load frequency control(LFC) of power system is one of important subjects in view of system operation and control. That is, even though the rapid load disturbances are applied to the given power system, the stable and reliable power should be supplied to the users, converging unconditionally and rapidly the frequency deviations and the tie-line power flow ones of each area into allowable boundary limits. Nonetheless of such needs, if the internal parameter perturbation and the sudden load variation are given, the unstable phenomena of power systems can be often brought out because of the large frequency deviation and the unsuppressible power line one. So, an optimal modulation controller for UC of multi-area power system is designed by a recursive algorithm that determines the state weighting matrix Q of a linear quadratic performance criterion. The optimal modulation controller is based on optimal control and can obtain the exact dynamic response of the UC of multi-area power system in the time domain. The performances of the resultant optimal modulation control, that is, the steady-state deviations of frequency and tie-line power flow and the related dynamics, were investigated and analyzed in detail by being applied to the UC of multi-area power system in the perturbations of predetermined internal parameters. Through the simulation results tried variously in this paper for disturbance of stepwise load changes, the superiorities of the proposed optimal modulation controller in robustness and stability were proved.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.46-54
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• 1998

This paper presents a method for designing robust fuzzy $H^{\infty}$ controllers which stabilize nonlinear systems with parameter uncertainty adn guarantee an induced $L_{2}$ norm bound constraint on disturbance attenuation for all admissible uncertainties. Takagi and Sugeno's fuzzy models with uncertainty are used as the model for the uncertain nonlinear systems. Fuzzy control systems utilize the concept of so-called parallel distributed compensation(PDC). Using a single quadratic Lyapunov function, the stability condition satisfying decay rate and disturbance attenuation condition for Takagi and Sugeno's fuzzy model with parameter uncertainty are discussed. A sufficient condition for the existence of robust fuzzy $H^{\infty}$ controllers is then presented in terms of linear matrix inequalities(LMIs). Finally, design examples of robust fuzzy $H^{\infty}$ controllers for uncertain nonlinear systems are presented.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.1
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• pp.16-22
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• 2016

The research on two-wheeled inverted pendulum (TWIP) mobile robots has been ongoing in a number of robotic laboratories around the world. In this paper, we consider a robust controller design for the TWIP mobile robot driving on uniform slopes. We use a 2 degree-of-freedom (DOF) model which is obtained by restricting the spinning motion in a 3 DOF motion dynamic equation. In order to design the robust controller guaranteeing stability of the TWIP mobile robot driving on inclined surface, we propose a sliding mode control based on the theory of variable structure systems and design a sliding surface using the theory of the linear quadratic regulation (LQR). For simulation, the dynamic model of the TWIP mobile robot is constructed using Mathworks' Simulink and the sliding mode control is also implemented using Simulink. From simulation results, we show that the proposed controller effectively controls the TWIP mobile robot driving on slopes.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.5
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• pp.367-375
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• 2012

In this study, hull form of main vessel of Korean large purse seiner fishing industry is developed for the improvement of resistance performance as well as for the satisfaction to the Standard of Fishing Convention, ILO. Through the modification of reference hull form parameters and local characteristics, the hull form development is carried out. The optimum hull form parameters are searched by Sequential Quadratic Programing(SQP) method with the power estimation method of Holtrop & Mannen. To minimize the wave resistance, bulbous bow parameters are determined by the bulbous bow design method of Alvarino. The plasmatic curve is redesigned from that of the reference hull by using Lackenby method. The resistance performances of the reference and designed hull forms are estimated by using numerical simulation method. Also, the judgment of seakeeping ability and the estimation of intact stability for the designed hull form is carried out. As a result, the optimum hull form is proposed. To verify the improvement of resistance performance, model tests are carried out in towing tank. The results show that the resistance of the designed hull form is about 14% smaller than that of the reference hull from at design speed. A new hull form proposed in this study can contribute to the development of the main vessel hull form of Korean large purse seiner fishing system.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.5
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• pp.391-399
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• 2012

This paper presents a method of hull form design for the assistant vessel which is used both as a lighting boat and a fish carrying boat for the fleet of newly formated purse seiner vessels. The optimum hull form parameters are searched by the Sequential Quadratic Programing(SQP) method with the power estimation method of Van Oortmerssen. The prismatic curve is redesigned from that of the reference hull by the Lackenby method. Through the modification of the hull form by using a CAD system, the design procedure is completed. The resistance performances of the reference and the modified hull forms are estimated by using a numerical simulation method. Also, the estimation of seakeeping ability and stability for the modified hull forms are carried out. And then, an optimum hull form is proposed for the designed hull form. Ship model tests for the reference and the designed hull forms are carried out at ship model basin. The results of the experiments show that the effective horse power of the designed hull form is about 22% smaller than that of the reference hull form at design speed. The designed hull form proposed in this study will contribute to the development of the hull form for Korean large purse seiner vessels.

• Culinary science and hospitality research
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• v.23 no.7
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• pp.20-30
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• 2017

This study was conducted for the optimization of ingredients in salad dressing using Hwangdo peach (Prunus persica L. Batsch). The experiment was designed according to the D-optimal design of mixture design, which included 14 experimental points with 4 replicates for three independent variables (olive oil 40~65%, peach puree 27~50%, vinegar 8~20%). The linear regression models for pH, viscosity and color value and the quadratic regression models for emulsion stability, all sensory evaluation of the products were proven to be valid by the F-test for the overall significance of the regression model at a 5% level. Viscosity and pH of the products increased as olive oil content. Color value, viscosity and pH of the products increased as peach puree content. pH, viscosity, redness, and yellowness of the products decreased as vinegar content. Sensory evaluation result of the products showed that general preference for the products were increasingly affected by the increases in contents then decreased as they exceeded the optimum levels. In consequence, according to result from the first stage of the experiment, the optimum ingredients ratios of the raw materials were set in olive oil 52.43%, peach puree 35.07%, and vinegar 13.91% for ingredients of apricot dressing. These results provided the possibility that peach can be applied to the preparation of a dressing, and thereby present baseline data for the development of new dressings. This is also presumed to meet demands of customers who are always in pursuit of new products.

• Wind and Structures
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• v.4 no.3
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• pp.177-196
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• 2001

At present the most popular turbulence models used for engineering solutions to flow problems are the $k-{\varepsilon}$ and Reynolds stress models. The shortcoming of these models based on the isotropic eddy viscosity concept and Reynolds averaging in flow fields of the type found in the field of Wind Engineering are well documented. In view of these shortcomings this paper presents the implementation of a non-linear model and its evaluation for flow around a building. Tests were undertaken using the classical bluff body shape, a surface mounted cube, with orientations both normal and skewed at $45^{\circ}$ to the incident wind. Full-scale investigations have been undertaken at the Silsoe Research Institute with a 6 m surface mounted cube and a fetch of roughness height equal to 0.01 m. All tests were originally undertaken for a number of turbulence models including the standard, RNG and MMK $k-{\varepsilon}$ models and the differential stress model. The sensitivity of the CFD results to a number of solver parameters was tested. The accuracy of the turbulence model used was deduced by comparison to the full-scale predicted roof and wake recirculation zone lengths. Mean values of the predicted pressure coefficients were used to further validate the turbulence models. Preliminary comparisons have also been made with available published experimental and large eddy simulation data. Initial investigations suggested that a suitable turbulence model should be able to model the anisotropy of turbulent flow such as the Reynolds stress model whilst maintaining the ease of use and computational stability of the two equations models. Therefore development work concentrated on non-linear quadratic and cubic expansions of the Boussinesq eddy viscosity assumption. Comparisons of these with models based on an isotropic assumption are presented along with comparisons with measured data.

• Journal of Ginseng Research
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• v.45 no.2
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• pp.236-245
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• 2021

Background: Red ginseng (RG) extract, especially ginsenoside Rg1 and Rb1 fractions has been reported to have antithrombotic activities. However, gastric instability and low intestinal permeability are considered to be obstacles to its oral administration. We hypothesized that stability, permeability, and activities of RG might be improved by encapsulation within nanoparticles (NPs) prepared with antithrombotic coating materials. Methods: RG-loaded chitosan (CS) NPs (PF-NPs) were prepared by complex ionic gelation with the antithrombotic wall materials, polyglutamic acid (PGA), and fucoidan (Fu). The concentrations of PGA (mg/mL, X₁) and Fu (mg/mL, X₂) were optimized for the smallest particle size by response surface methodology. Antithrombotic activities of RG and PF-NPs were analyzed using ex vivo and in vivo antiplatelet activities, in vivo carrageenan-induced mouse tail, and arteriovenous shunt rat thrombosis models. Results: In accordance with a quadratic regression model, the smallest PF-NPs (286 ± 36.6 nm) were fabricated at 0.628 mg/mL PGA and 0.081 mg/mL Fu. The inhibitory activities of RG on ex vivo and in vivo platelet aggregation and thrombosis in in vivo arteriovenous shunt significantly (p < 0.05) increased to approximately 66.82%, 35.42%, and 38.95%, respectively, by encapsulation within PF-NPs. For an in vivo carrageenan-induced mouse tail thrombosis model, though RG had a weaker inhibitory effect, PF-NPs reduced thrombus significantly due to the presence of PGA and Fu. Conclusion: PF-NPs contributed to improve the activities of RG not only by nanoencapsulation but also by antithrombotic coating materials. Therefore, PG-NPs can be suggested as an efficient delivery system for oral administration of RG.