• Journal of the Korean Society of Industry Convergence
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• v.3 no.2
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• pp.131-139
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• 2000

Gear train in the automobile to be used for controlling gas flow in automobiles consists of spur gears with involute tooth type in multiple stages. This spur gear is designed considering to the high power transfer efficiency, bending stress and contact stress in the static and dynamic analysis. The torque has been increased simultaneously the angular velocity has been decreased through the stages after being supplied by AC synchronous motor. This apparatus is controlled by electrical devices such as the PIC microprocessor, hall sensor and other electric components. By comparing the preset data of PIC microcomputer which is supplied by external DC electric power with the value set of hall sensor which detects the rotation angle position, PIC microcomputer thus controls AC motor and gear train according to the program algorithm which includes the on-off control and PWM motor driving method. As the result of the experiment such as performance, fatigue, torque test, we can conclude that this system is superior to the same and familiar foreign systems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.358-362
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• 2005

An effective control of the axial thrust of a turbopump is one of the critical issues for its operational stability. In order to assure the stability of a turbopump-type fuel pump for a liquid rocket engine, an axial thrust measurement system was developed and a series of axial thrust tests were performed in water environment. In the tests, the axial thrust of the fuel pump at the design flowrate satisfied the axial force condition of the bearing of the pump. Also, it was found that by using orifices with different geometries in the secondary flow passage the overall axial thrust of the pump could be controlled.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.2
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• pp.55-65
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• 2012

In the winter season, when the ventilation system is operating, the fresh cold air from the slot-type openings of broiler house which directly reached the animal zone can cause various problems such as thermal stress, decreasing of feed and water consumption, occurrence of respiratory disease, and etc. Therefore it is very important to control the trajectory of aero-flow from the slot openings to induce an efficient thermal heat change. Jet-drop distance model was proposed to predict and control the jet-trajectory. However their study was restricted due to the small scaled model and difficulties of measuring the Jet-drop distance. In this study, CFD was applied to analyze qualitatively and quantitatively the jet-drop distance in a real broiler house. The various variables were considered such as installed slot-angle, designed ventilation rate, and the outdoor ambient temperature. From the present study, two linear-regression models using the Jet-drop factor and corrected Archimedes number, and their R-squared values 0.744 and 0.736, respectively, were used. From this study, the applicability of CFD on the analysis of Jet-drop distance model was confirmed.

• Journal of Power Electronics
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• v.12 no.4
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• pp.567-577
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• 2012

This paper introduces a new scheme to balance the DC bus voltages of a cascaded H-bridge converter which is used as a Distribution Static Synchronous Series Compensator (D-SSSC) in electrical distribution network. The aim of D-SSSC is to control the power flow between two feeders from different substations. As a result of different cell losses and capacitors tolerance the cells DC bus voltage can deviate from their reference values. In the proposed scheme, by individually modifying the reference PWM signal for each cell, an effective balancing procedure is derived. The new balancing procedure needs only the line current sign and is independent of the main control strategy, which controls the total DC bus voltages of cascaded H-bridge. The effect of modulation index variation on the capacitor voltage is analytically derived for the proposed strategy. The proposed method takes advantages of phase shift carrier based modulation and can be applied for a cascaded H-bridge with any number of cells. Also the system is immune to loss of one cell and the presented procedure can keep balancing between the remaining cells. Simulation studies and experimental results validate the effectiveness of the proposed method in the balancing of DC bus voltages.

• Journal of the Korea Society of Computer and Information
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• v.17 no.11
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• pp.19-26
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• 2012

Reversible lanes in urban intersections is used to efficiently control vehicles, reduce traffic congestion and increase the capacity of a roadway. But by far traffic control systems in urban intersections are simple and manually operated by police officers. In this study, we present a hybrid algorithm that intelligently resolve the moving direction of reversible lanes to efficiently manage the flow of traffic at intersection. The proposed algorithm consists of three stages:(i) fuzzy inference method to get the efficiency of moving direction, (ii) a provisional decision whether to change the reversible lane to different direction, (iii) a final evaluation criterion for changing the directions of the reversible lanes. The fuzzy inference results of efficiency are shown by using matlab application.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.4
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• pp.13-21
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• 2001

Electrorheological(ER) fluid is a kind of smart material with variable shear stress and dynamic viscosity under various electric field intensity. Electric field can control the damping characteristics of ER damper. The objective of this study is the analysis of the performance of ER damper and its application to shock absorber. Idealized nonlinear Bingham plastic shear flow model is used to predict the velocity profile between electrodes. Cylindrical dashpot ER damper with moving electrode is constructed and tested under various electric fields. The analytic and experimental results for damping force are compared and discussed. Drop test system using ER damper is prepared to identify transient vibration characteristics. The rebound is eased as the applied electric field increases. When semi-active control algorithm is applied, rebound phenomenon disappears and vibration energy level decays faster than the case of zero electric field.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.127-128
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• 1998

It is necessary to maintain constant intravenous (IV) infusion rate. While infusion pump is able to control infusion rate with great accuracy, its rather large size and weight make it difficult for patients to move around. The most commonly used infusion device is gravity IV infusion set with its administration chamber being clamped according to the observed drip rate. In this case it may be easier and more accurate to maintain IV rate to given value if we automate the drip-counting process and tube-clamping work by electronic devices. We calculated volume infusion rate of specific fluid using optical drip rate meter which we had developed. To regulate fluid flow rate, we equipped the rate meter which we had developed with a miniaturized clamping apparatus using DC motor. Also, we Implemented drip detection and clamp control algorithm with PIC16C73 $\mu$-controller (Microchip). This system provides user interface through LCD display and key buttons.

• Natural Product Sciences
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• v.18 no.2
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• pp.83-88
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• 2012

In order to facilitate the quality control of the fruits of Crataegus pinnatifida, a simple, accurate and reliable HPLC method was developed for the simultaneous determination of the three bioactive compounds: chlorogenic acid (1), rutin (2), and hyperin (3), which were selected as the chemical markers of C. pinnatifida. Separation was achieved on an Agilent Eclipse XDB-C18 column with a gradient solvent system of 0.1% trifluoroacetic acid aqueous-acetonitrile at a flow-rate of 1.0 mL/min and detected at 254nm. All three calibration curves showed good linearity ($R^2$ > 0.998). The recoveries of three marker compounds were in the range of 94.87~111.52 %. The contents of chlorogenic acid (1), rutin (2), and hyperin (3) of the fruits of C. pinnatifida collected from 23 district markets in Korea, Japan, and China were 0.16~0.65 mg/g, 0.07~1.24 mg/g, and 0.03~0.62 mg/g, respectively. The results demonstrated that this method is simple and reliable for the quality control of the fruits of C. pinnatifida.

• Journal of Bio-Environment Control
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• v.1 no.2
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• pp.175-180
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• 1992

Cherry tomatoes(Lycopersicon esculentum) were grown in circulating deep flow hydroponic system. The pH of the nutrient solution was increased and the EC was decreased with time. The clusters of ‘Mini Carol’ were branched severely, whereas those of ‘Chelsea Mini’ and ‘Popo’ were a little branched or not. The vegetative growth was similar between cultivars. But the yield of fruits was by far the largest in ‘Mini Carol’ compared to other cultivars, and not different between ‘Chelsea Mini’ and ‘Popo’. Internal qualities of fruits, like as sugar, sugar/organic acid, and vitamin C, are good in ‘Mini Carol’. As the result of panel test, ‘Mini Carol’ is good for softness, easeness of eating, toughness of skin and so on, so it is believed that ‘Mini Carol’ is the most acceptable to consumers in hydroponic culture.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.48-55
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• 2012

An ambient hot-firing test was carried out for the hydrazine thruster which may be employed in the space launch vehicles. The thruster is designed to produce 67 N (15 $lb_f$) of nominal steady-state thrust at an inlet pressure of 2.41 MPa (350 psia). A scrutiny into the performance characteristics of thruster is made in terms of thrust, propellant supply pressure, mass flow rate, chamber pressure, and temperature at the steady-state firing mode. As a result, it is ensured that the practical performance efficiencies are above 89.1% compared to its ideal requirements.