• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.853-859
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• 2017

This study was conducted in an effort to investigate the effect of Maillard reaction products (MRPs) on enzymatic browning of burdock and their anti-oxidant activity. The MRPs were prepared by heating glucose and amino acids at $90^{\circ}C$, which served to produce a strong inhibitory effect on burdock polyphenol oxidase. As the reaction time of the solution containing glucose and amino acid increased at $90^{\circ}C$, the production of MRPs increased and intensity of the brown color deepened. When MRPs were prepared by heating at $90^{\circ}C$ for five hours, the absorbance of MRPs from glucose and lysine was 6.44, while those of glucose and glycine was 1.95. The MRPs synthesized from the glucose and lysine also reduced the pH of MRPs from 5.60 to 4.51, but those from glucose and glycine decreased slightly from 5.57 to 5.33. The Michealis-Menten constant value ($K_m$) of burdock PPO with pyrocatechol as a substrate was 16.0 mM, and MRPs were a non-competitive inhibitor against burdock PPO. The anti-oxidant activity of MRPs was measured by evaluating its radical scavenging activities of DPPH radicals, ABTS radicals and reducing power. The color intensity of MRPs produced by lysine and glucose were deeper than that produced by glucose and glycine. It was also found that MRPs produced from glucose and lysine exhibited stronger anti-oxidant properties than those produced by glucose and glycine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.470-475
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• 2009

In the present study, the heat transfer characteristics of the fin-tube and PF heat exchangers and the performances of the air-conditioner are experimentally investigated. Also, Cooling Seasonal Performance Factor(CSPF) of the air-conditioner is evaluated. For the heat exchanger experiment, the heat transfer and pressure drop are obtained. For the air-conditioner experiment, the cooling capacity, input power and COP are obtained. The air-enthalpy calorimeter and the constant temperature water bath are used. As the inlet air velocity increases, the heat transfer rate and pressure drop of the heat exchanger increased. PF heat exchanger has smaller refrigerant weight and larger capacity and COP than the fin-tube heat exchanger. The performance of PF-2 heat exchanger with the squarer fin is more excellent than that of PF-1 heat exchanger with the triangler fin. Also, CSPF of the fm -tube and PF heat exchanger is evaluated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3139-3145
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• 2014

This paper describes the design of a size-reduced ring hybrid coupler for microwave band using an artificial dielectric substrate(ADS). ADS structure adopts the second substrate on which has lots of the metalized via-holes. The effective capacitance and effective dielectric constant per unit length of ADS increases compared to the normal substrate due to the via-holes. This enables the physical length of microstrip transmission line to be reduced by adopting ADS instead of the normal substrate. In order to present an example of size-reduction of microwave wireless circuit by ADS, a size-reduced 3GHz ring hybrid coupler is designed, fabricated and measured in this work. The designed coupler has the smaller size from the normal one by 65% due to the ADS, while no critical degradation from ideal performances is observed. The measured power division ratio at two output ports are -3.05dB and -3.135dB, respectively. In addition, the phase differences are 3o for in-phase division and 176o for out of phase split. The measured performances are so similar to ideal ones, and prove the design of size-reduced ring hybrid coupler using ADS is successful.

• Journal of Drive and Control
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• v.12 no.3
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• pp.52-59
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• 2015

An electro hydraulic poppet valve (EHPV) and a variable orifice poppet are assembled in a single block, which is referred to as a RHINO but is also generally called a pilot-operated flow control valve. In this study, we analyzed the structure and the operating principle for a RHINO applied in a 21-ton electric excavator system. The RHINO was experimentally tested to measure the dynamic responses and the pressure energy loss. In this test, we investigated the variation in the conductance coefficient according to the increase in the supply pressure under a constant current and a variation in the flow rate according to the increase in the current. Then, the geometrical shapes and the spring stiffness of the RHINO were considered to develop an analysis model. The characteristics (current-force and hysteresis) for the solenoid based on the experimental data were reflected in the analysis model that was developed, and the reliability of the analysis model was also verified by comparing the experimental and analytical results. The developed model is thus considered to be reliable for use in a wide range of applications, including optimum design, sensitivity analysis, parameter tuning, etc.

• Journal of Drive and Control
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• v.13 no.2
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• pp.34-41
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• 2016

Unlike the commonly used On/Off solenoid, constant attraction force which is independent of plunger displacement is a considerably important characteristic to proportional solenoid of the EPPR Valve. Attraction force uniformity is mainly affected by the internal shape design parameters. Due to a number of shape design parameters, the optimal parameter values are very complex and time consuming to find by trial and error method. Much research has been conducted or are still in progress to find the optimal parameter values by applying various optimization techniques like Genetic Algorithm, Evolution Strategy, Simulated Annealing, or the Taguchi method. In this paper, the design parameters which have primary effects on the attraction force uniformity and the average attraction force are decided by main effects analysis of Design of Experiments. Optimal parameter values are derived using finite-element analysis and a neural network model.

• Geomechanics and Engineering
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• v.22 no.5
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• pp.415-431
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• 2020

In this study, dynamics responses of advanced composite plates resting variable elastic foundations via a quasi-3D theory are developed using an analytical approach. This higher shear deformation theory (HSDT) is included the shear deformation theory and effect stretching that has five unknowns, which is even inferior to normal deformation theories found literature and other theories. The quasi-three-dimensional (quasi-3D) theory accounts for a parabolic distribution of the transverse shear deformation and satisfies the zero traction boundary conditions on the surfaces of the advanced composite plate without needing shear correction factors. The plates assumed to be rest on two-parameter elastic foundations, the Winkler parameter is supposed to be constant but the Pasternak parameter varies along the long side of the plate with three distributions (linear, parabolic and sinusoidal). The material properties of the advanced composite plates gradually vary through the thickness according to two distribution models (power law and Mori-Tanaka). Governing differential equations and associated boundary conditions for dynamics responses of the advanced composite plates are derived using the Hamilton principle and are solved by using an analytical solution of Navier's technique. The present results and validations of our modal with literature are presented that permitted to demonstrate the accuracy of the present quasi-3D theory to predict the effect of variables elastic foundation on dynamics responses of advanced composite plates.

• Cross-Cultural Studies
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• v.36
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• pp.123-147
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• 2014

The purpose of this essay is three-fold: to trace the genealogy of the Korean musical, which ever since its inception in the 1960s has been seeking to modernize Korean theater with Broadway as a constant role model; to investigate how the national and the global conflict and are conflated in the form of the Korean musical in the process of its (dis)identification with Broadway; and to examine how its intercultural translations reveal and reflect the dilemma and ambivalence posed by globalization in our era. Drawing on Richard Dyer's signature article Entertainment and Utopia, I analyze how the Korean musical manifests and conduits competing utopian impulses of Korean/Global audiences. I also attempt to problematize the formulaic notion of Broadway musicalsthe Superior Other!which implies a global hegemony that does not, in fact, exist because the boundary between the global and the local as well as the power dynamics of global culture are not fixed but constantly moving and changing. Today's musical scene in Korea shows interesting reversals from the 1990s, when Korean producers were eager to debut on Broadway and impress American audiences. Korean producers no longer look up to Broadway as a final destination; instead they want to make Seoul a new Broadway. They import Broadway musicals and turn them into Korean shows. The glamor of Broadway is no longer the main attraction of musicals in Korea. What young audiences look for most is the glamor of K-pop idols and utopian feelings of abundance, energy, intensity, transparency and community, which they can experience live in the musical with their favorite stars right in front of their eyes. In conclusion, I delve into the complex dynamics of recent Korean musicals with Thomas Friedman's theory of Globalization 3.0 as reference. The binary formula of Global/America versus Local/Korea cannot be applied to the dynamic and intercultural musical scene of today. Globalization is not a uniform phenomenon but rather a twofold (multifold) process of global domination and dissemination, in which the global and the local conflict and are conflated constantly. As this study tries to illuminate, the Korean musical has evolved in a huge net of interdependences between the global and the local with a range of sources, powers and influences.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.862-865
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• 2008

Wireless energy supply for an MAV propulsion system using microwave was developed. This system consists of three sub system; the transmitter system, the rectenna system, and the tracking system. In the transmitter system five horn antennas were used as the antenna elements for the phased array system and both the beam divergence and steering angle was about 9deg. Eight rectennas were arrayed in parallel to obtain enough power to drive the electric motor on the MAV(the voltage was 250mV and the current was 6.8mA) in rectenna system. In tracking system two units of antenna system with leaf pattern which received the linearly-polarized wave despite the MAV yaw angle were set in each axis(x, y) for tracking an MAV in a 2-Dimentional space. And three output voltages $V_{com},\;V_1$ and $V_2$ were loaded in the PC to detect if the distance between transmitter and receiver was not constant. Finally when the microwave beam was steered by the phased array system the output voltage from rectenna was measured at 62cm while the MAV circled around above the transmitter system.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.270-277
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• 2021

In the power ultrasound fields, the flange position for fixing the transducer is an important factor influencing on electro-mechanical efficiency of the transducer. We suggested a practical method that can determine the installation position of the flange for different resonance modes of the bolt-clamped type Langevin ultrasonic transducer. A semicircular wedge-shaped jig was manufactured and moved along the lateral surface of the transducer. The vibration characteristics were examined after a constant pressure was applied to the semicircular wedge-shaped jig. By observing the change of the input admittance of the transducer depending on the position of the pressure application, the optimum position for the flange installation could be determined. The resonant modes of the transducer were calculated by a Mason's equivalent circuit, and the particle velocity distribution for each resonance mode was calculated by a transmission line model. Since the optimum positions determined from an experimental result show a good correspondence with the node positions of the vibration modes calculated by the transmission line model, the validity of the suggested method was verified.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.68-74
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• 2018

Study on the Ti-6Al-4V have been carried out using cutting simulation, and researches for cutting force and chip shape prediction have been actively conducted under various conditions. However, a 3D printer application method using Ti-6Al-4V metal powder material as a high-power method has been studied for the purpose of prototyping, mold modification and product modification while lowering material removal rate. However, in the case of products / parts made of 3D printers using powder materials, problems may occur in the contact surface during tolerance management and assembly due to the degradation of the surface quality. As a result, even if a 3D printer is applied, post-processing through cutting is essential for surface quality improvement and tolerance management. In the cutting simulation, the cutting force and the chip shape were predicted based on the Johnson-Cook composition equation, but the shape of the shear type chip was not predictable. To solve this problem, we added a damaging term or strain softening term to the Johnson-Cook constitutive equation to predict chip shape. In this thesis, we applied the constant value of the S-K equations to the cutting simulation to predict the cutting force and compare with the experimental data to verify the validity of the cutting simulation and analyzed the machining characterization by considering conditions.