• Food Science of Animal Resources
• /
• v.42 no.6
• /
• pp.915-927
• /
• 2022

Recently, protein-fortified milk powders are being widely consumed in Korea to prevent sarcopenia, and the demand for high-protein food powders is continuously increasing in the Korean market. However, spray-dried milk proteins have poor flowability and wettability owing to their fine particle sizes and high inter-particle cohesive forces. Fluidized bed agglomeration is widely used to improve the instant properties of food powders. This study investigated the effect of fluidized bed agglomeration on whey protein isolate (WPI)-fortified skim milk powder (SMP) at different SMP/WPI ratios. The fluidized bed process increased the particle size distribution, and agglomerated particles with grape-like structures were observed in the SEM images. As the size increased, the Carr index (CI) and Hausner ratio (HR) values of the agglomerated WPI-fortified SMP particles exhibited excellent flowability (CI: <15) and low cohesiveness (HR: <1.2). In addition, agglomerated WPI-fortified SMP particles exhibited the faster wetting time than the instant criterion (<20 s). As a result, the rheological and physical properties of the WPI-fortified SMP particles were effectively improved by fluidized bed agglomeration. However, the fluidized bed agglomeration process led to a slight change in the color properties. The CIE L^* decreased, and the CIE b^* increased because of the Maillard reaction. The apparent viscosity (η_a,10) and consistency index (K) values of the rehydrated solutions (60 g/180 mL water) increased with the increasing WPI ratio. These results may be useful for formulating protein-fortified milk powder with better instant properties.

• Tunnel and Underground Space
• /
• v.33 no.1
• /
• pp.1-9
• /
• 2023

Roadheaders have been operated in the construction of Korean tunneling projects. The note introduces operation manual and management case of transverse type roadhead in a Korean tunneling site. The cutting and reaction forces of axial and transverse type cutting heads were qualitatively analyzed. The shaping surfaces of tunnel faces were visualized in both cases of fixed and auto-controlled telescopic cylinder conditions. Excavating with fixed cylinder, concave surfaces were shaped on tunnel face. The total processes of sumping and shearing were illustrated for excavating hard rock tunneling. The supplementary graphical explanations for total tunneling procedures in Korea were provided.

• Earthquakes and Structures
• /
• v.24 no.1
• /
• pp.21-36
• /
• 2023

Structural vibrations generated by earthquakes and wind loads can be controlled by varying the structural parameters such as mass, stiffness, damping ratio, and geometry and providing a certain amount of passive or active reaction forces. A Double-Tuned Mass Dampers (DTMDs) system, which is simple and more effective than the conventional single tuned mass damper (TMD) system for vibration mitigation is presented. Two TMDs tuned to the first two natural frequencies were used to control vibrations. Experimental investigations were carried out on a three degrees-of-freedom frame model to investigate the effectiveness of DTMDs systems in controlling displacements, accelerations, and base shear. Numerical models were developed and validated against the experimental results. The validation showed a good match between the experimental and numerical results. The validated model was employed to investigate the behavior of a five degrees-of-freedom shear building structure, wherein mass dampers with different mass ratios were considered. The effectiveness of the DTMDs system was investigated for harmonic, seismic, and white noise base excitations. The proposed system was capable of significantly reducing the story displacements, accelerations, and base shears at the first and second natural frequencies, as compared to conventional single TMD.

• Korean Journal of Veterinary Service
• /
• v.46 no.2
• /
• pp.175-179
• /
• 2023

This study was conducted to find out the compensation strategy through kinetic gait analysis by comparing dog with congenital luxation of the shoulder joint and normal dog. Ground reaction forces were recorded for all limbs while normal poodle dog and poodle dog with shoulder joint luxation was allowed to walk on an instrumented platform. The dogs were evaluated for maximal vertical force (MVF), body load distribution (BLD), and symmetry index (SI). The MVF was increased in the contralateral forelimb of luxated shoulder joint. The SI was also increased in a dog with dislocated shoulder joints in the forelimbs. For BLD, the maximum load distribution increased centrally, but the total load distribution decreased in the ipsilateral forelimb paw. In contrast, total load distribution was increased in the contralateral forelimb paw. During forelimb lameness, changes in weight-bearing load showed compensatory load redistribution. These biomechanical changes may lead to changes in the musculoskeletal system in a dog with luxated shoulder.

• International conference on construction engineering and project management
• /
• 2024.07a
• /
• pp.160-166
• /
• 2024

In recent years, as buildings have become taller and taller, the continued usability of elevators after earthquakes has become an important issue. Conventional seismic design of elevators has focused mainly on inertial forces caused by earthquakes, but the influence of the story drift angle of buildings on elevator behavior has been unclear. Therefore, the objective of this study was to clarify the influence of the story drift angle of a building caused by an earthquake on the behavior of elevators through an experiment. The experiment specimens were the counterweight, guide rails, and surrounding components selected from the actual elevator components and mounted on a one-story steel pin frame. A static experiment was conducted using a hydraulic jack to apply force to the specimen by imposing the story drift angle on the steel frame. During the experiment, the reaction force at the end of the jack was monitored, and the displacement and strain of the counterweight, guide rails, and surrounding components were measured. The results of the experiments in one direction showed that even when the elevator components were subjected to a larger story drift angle than assumed in the seismic design of the building, no damage occurred that could lead to fallout.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.37 no.2
• /
• pp.357-367
• /
• 2017

Bending and axial forces simultaneously occur at the cross-section of a shotcrete lining reinforced with steel supports due to the tunnel geometry. The shotcrete has changing flexural stiffness depending on the axial forces and, as a result, severely nonlinear behavior. The mechanical properties of a shotcrete-steel composite also depend on the type of steel support. This study presents a fiber section element model considering the effect of axial force to evaluate the nonlinear behavior of a shotcrete-steel composite. Additionally, the model was used to analyze the effects of different types of steel supports on the load capacity. Furthermore, a modified hyperbolic model for ground reaction, including strain-softening, is proposed to account for the ground-lining interaction. The model was validated by comparing the numerical results with results from previous load test performed on arched shotcrete specimens. The changes in mechanical responses of the lining were also investigated. Results show a lining with doubly reinforcement rebar has similar load capacity as a lining with H-shaped supports. The use of more materials for the steel support enhances the residual resistance. For all types of steel reinforcement, the contribution of steel supports during peak load decreases as the ground becomes stiffer.

• Korean Journal of Applied Biomechanics
• /
• v.19 no.1
• /
• pp.149-157
• /
• 2009

The purpose of this project was to determine biomechanical differences between Type A(Korean brand) and Type B(world top brand) badminton shoes and to make recommendations to improve the fit and function of Type A badminton shoes. Measurements of shoe shape and dimensions, foot movement within the shoe, cushioning of ground reaction forces, in-shoe pressure and outsole traction were performed. In addition, subjective feedback of the fit and function of the shoes was quantified for 17 recreational badminton players. Type A shoe had a much higher heel and shallower heel cup, so the heel was not secured well in the shoe and the ankle joint was higher off the ground. Foot slippage was up to 40% greater in Type A shoe than Type B shoe. Impact forces and peak pressures under the foot were generally higher with Type A shoe compared to Type B shoe. The flexion axis of Type A shoe occurred in the midfoot, not at the ball of the foot like Type B shoe, where you would want the shoe flexion to occur. In summary, there are several characteristics where A Type shoe and B Type differ. Therefore, a few recommendations are provided to help improve the fit and function of A Type shoe.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.10
• /
• pp.7-17
• /
• 2019

With increasing demand for large offshore infrastructures, suction cofferdams have been large, and the lid stiffener arrangement for a suction cofferdam has become a key element in cofferdam design to constrain the flexural deformation effectively. This study analyzed the changes in the structural behavior of a lid for a suction cofferdam due to lid stiffeners to provide insights into effective stiffener arrangements. By investigating conventional suction anchors, several stiffener patterns of a lid for a polygonal suction cofferdam were determined and analyzed. The structural performance of the stiffened lids was estimated by comparing the stress and deformation, and the reaction distributions on the edge of lid were investigated to analyze the effects of the stiffener arrangement on the lid-wall interface. Finite element analysis showed that radial stiffeners contribute dominantly to decreasing the stress and vertical deflection of the lids, but the stiffeners cause an increase in shear forces between the lid and wall; the forces are concentrated on the lid near the areas reinforced with radial stiffeners, which is negative to lid-wall connection design. On the other hand, inner and outer circumferential stiffeners show little reinforcement effects in themselves, while they can help reduce the stress and deformation when arranged with partial radial stiffeners simultaneously.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.3
• /
• pp.221-231
• /
• 2021

In the present study, numerical simulation was performed to investigate aerodynamic characteristics of a ducted fan-upper/lower vanes system in hover. Sensitivity analysis of aerodynamic forces for a system component was conducted with the deflection angle of upper vanes varying but at the constant rotational speed and the collective pitch angle of fan blades. Then, vane control performance and duct airload distributions were analyzed in detail to physically understand operating mechanisms of individual vane and interference effect between duct and vanes. Finally, new control concept of operating upper vanes has been proposed to improve the control performance of the full configuration. It is found that the side force and rolling moment of upper vanes increase linearly with the variation of those deflection angle; however, the total side force is significantly small due to the reaction force acted on the duct. It is also found that upper vanes close to the duct contraction side have a key role in changing vane control forces. It is revealed that the duct suction pressure is induced by the interaction with the suction side of upper vanes, while duct pressure recovery by the interaction with the pressure side, leading to increase in duct asymmetric force. When four upper vanes are kept in situ at 0° deflection angle or removed, the total control performance was improved with duct asymmetric force reduced and the total magnitude of roll remarkably increasing up to 80%.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.6
• /
• pp.659-664
• /
• 2013

The aim of this study is to determine the drought stress index through photochemical analysis in red pepper (Capsiumannuum L.). The photochemical interpretation was performed in the basis of the relation between Kautsky effect and Photosystem II (PSII) following the measurement of chlorophyll, pheophytin contents, and $CO_2$ assimilation in drought stressed 5-week-old red pepper plants. The $CO_2$ assimilation rate was severely lowered with almost 77% reduction of chlorophyll and pheophytin contents at four days after non-irrigation. It was clearly observed that the chlorophyll fluorescence intensity rose from a minimum level (the O level), in less than one second, to a maximum level (the P-level) via two intermediate steps labeled J and I (OJIP process). Drought factor index (DFI) was also calculated using measured OJIP parameters. The DFI was -0.22, meaning not only the initial inhibition of PSII but also sequential inhibition of PSI. In real, most of all photochemical parameters such as quantum yield of the electron transport flux from Quinone A ($Q_A$) to Quinone B ($Q_B$), quantum yield of the electron transport flux until the PSI electron acceptors, quantum yield of the electron transport flux until the PSI electron acceptors, average absorbed photon flux per PSII reaction center, and electron transport flux until PSI acceptors per cross section were profoundly reduced except number of QA reducing reaction centers (RCs) per PSII antenna chlorophyll (RC/ABS). It was illuminated that at least 6 parameters related with quantum yield/efficiency and specific energy fluxes (per active PSII RC) could be applied to be used as the drought stress index. Furthermore, in the combination of parameters, driving forces (DF) for photochemical activity could be deduced from the performance index (PI) for energy conservation from photons absorbed by PSII antenna until the reduction of PSI acceptors. In conclusion, photochemical responses and their related parameters can be used as physiological DFI.