• Journal of Digital Convergence
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• v.18 no.12
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• pp.543-548
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• 2020

The purpose of this study is to implement various movements of multiple objects using a small number of power devices in producing a kinetic design, achieving an effect similar to a work comprised of multiple objects controlled using multiple power devices. While it is more typical to control various objects using multiple power devices, the use of multiple devices leads to higher costs and heavier overall weight. In addition, more power is required to operate the multiple power devices. This study applied a mechanism that allows multiple objects to perform various movements using a small number of power devices. The mechanism significantly reduces overall weight and power consumption. In addition, various movements could be expressed by increasing the rows and columns of objects through the use of the camshaft structure that changed the position and shape of the cam and the use of bevel gears. The significance of this study lies in presenting a new method of controlling multiple objects for designers involved in kinetic design.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2335-2343
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• 2018

This paper proposes an optimal damping control algorithm of the DTI (Direct Two-level Inverter) to miniaturize and reduce the weight of auxiliary power supply for railway vehicles. The conventional auxiliary power supply for railway vehicles uses a DC-DC converter to maintain the inverter input power from the line voltage smoothly. The proposed topology does not use a DC-DC converter for reducing of manufacturing and maintenance costs. It also proposes a DTI topology removed damping resistors that generate ground signal noise in a certain period. At this time, a resonance phenomenon of DC-link voltage occurs due to variation of the inductive load, and a method of controlling the resonance phenomenon of DC-link voltage is required. In order to suppress the resonance phenomenon of the DC-link voltage, at a point before resonance occurs, this paper introduces an algorithm to suppress the resonance phenomenon of DC-link voltage by compensating the resonance component of the q axis voltage of the synchronous reference frame. The proposed algorithm verifies the effect through simulation and experiment.

• Journal of Power System Engineering
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• v.13 no.1
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• pp.46-52
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• 2009

The steel impeller placed in a water pump has been studied with the aim to understand corrosion phenomena on the surface responsible for reducing the pumping efficiency of water inside cooling system. This preliminary experiment includes a period (over 5 months) observation with a powered microscope and weight measurements. The experiments are carried out at different conditions of water and mixtures of water and coolants, based on the water contents of 25%, 50%, 75%, and 100% water (pure tap water). From the visual results of microscopy, most of the steel surface is fitted and clear rusty or corrosion phenomena are noticeable as time goes. In addition, the weight loss of the sample specimen submerged in the water is linearly increased, whereas those in the mixtures of water initially be constant and then gain weight linearly.

• Journal of Power Electronics
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• v.16 no.2
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• pp.399-413
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• 2016

This paper presents a topology for a modular power electronic transformer (PET) and a control scheme. The proposed PET consists of a cascaded H-Bridge rectifier on the primary side, a high-frequency DC/DC conversion cell in the center, and a cascaded H-Bridge inverter on the secondary side. It is practical to use PETs in power systems to reduce the cost, weight and size. A detailed analysis of the structure is carried out by using equivalent circuit. An algorithm to control the voltages of each capacitor and to maintain the power flow in the PET is established. The merits are analyzed and verified in theory, including the bi-directional power flow, variable voltage/frequency and high power factor on the primary side. The experimental results validated the propose structure and algorithm.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.55-59
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• 2022

This paper introduce Renewable Energy forecasting technology, which is a part of renewable management system. Then, calculation method of dedicated transmission line's meteorological data to forecast renewable energy is suggested. As the case of dedicated transmission line, there is only power output data combined the number of renewable plants' output that acquired from circuit breakers. So it is need to calculate meteorological data for dedicated transmission line that matched combined power output data. this paper suggests two calculation method. First method is select the plant has the largest capacity, and use it's meteorological data as line meteorological data. Second method is average with weight that given according to plants' capacity. In case study, suggested methods are applied to real data. Then use calculated data to Renewable forecasting and analyze the forecasting results.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.357-362
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• 2000

Allowable stress design(ASD) method has been widely used to design steel structures such as boiler and heat recovery steam generator(HRSG) of power plant. However, many researchers are recently intrested in road and resistance factor design(LRFD) method which may take the place of ASD. In this work, the weight calculation of steel structure was compared when ASD and LRFD were applied respectively. For the calculation of weight of steel structure, computer program was developed and applied to obtain beam weight. Using this program and GTSTRUDL, structural design program, weight of steel structure is calculated. As a result of weight calculation, maximum 5.4% of weight reduction is achieved among examples of this study by applying LRFD comparing with the result of ASD, and those results quite dependent on the applied load and member classification.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.479-490
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• 2002

A dynamic model of a power shuttle transmission was developed and its validity was verified using the experimental data obtained from a transmission test bench. A 40㎾, 4WD tractor was also modeled using an application software EASY5 to investigate parameters and their effects on the power shifting performance. For a tractor model, the manual reverse gear was replaced by a power shuttle transmission. The tractor model also included an engine, main-gears for transmission, wheels, differentials and planet gears. Using the tractor model, the effects of the parameters such as modulating pressure and time, engine speed, tractor speed. tractor weight. reverse to forward speed ratio and torsional damper on the transient characteristics at starting and shuttle shifting were investigated by the computer simulation. The transient characteristics were represented by variations in clutch pressure, torque transmitted to input shaft and driving wheels, and power transmission capacity of the clutch. It was found that the modulating pressure and time affected most significantly the torque transmission and shifting time. The input torque, axle torque, power transmission capacity of the clutch and transmission time all increased with increase in engine speed, tractor speed. tractor weight and ratio of reverse to forward speeds. However, the axle torque decreased with tractor speed. Both the axle torque and power transmission capacity of the clutch also decreased with the ratio of reverse to forward speeds.

• Journal of Surface Science and Engineering
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• v.57 no.4
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• pp.296-305
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• 2024

The aim of this in vitro study was to evaluate the changes in the roughness and weight of titanium discs treated with 3 different types of magnetostrictive ultrasonic scaler tip. Eighty identical disks (10 mm in diameter), 50 for surface roughness and 30 for weight change, were investigated in this study. For this study, 3 types of scaler tip were used as follows; Powerline(FSI-PWR-1000), Slimline(FSI-SLI-1000), and Thinsert(-16 00037374). The power was set to high power(HP), medium power(MP), and low power(LP), in the blue zone recommended by the manufacturer. Surface topography analysis was carried out using scanning electron microscopy (SEM). Surface roughness measurements, the average surface roughness (Ra) and mean roughness profile depth (Rz), were compared between treated and non-treated surfaces with a profilometer. A PowerLINE-MP of magnetostrictive ultrasonic scalers for implant patients might be recommended when considering changes in the roughness and weight of titanium discs.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.38-60
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• 1999

The main objective of this study is systemization of the technique of ROC quantification and optimization of baseline design by applying CE principle to the acquisition process of a weapon system. QFD and TOA techniques can be employed to a good working example of the conceptual design of a future main battle tank. In this paper, Product Planning Phase, the first phase of four QFD phases, is deployed in terms of eight steps including customer requirements and final product control characteristics. TOA is carried out considering only combat weight. In order to perform combat weight analysis and performance TOA, Preliminary Configuration Synthesis Methodology is used. Preliminary Configuration Synthesis Methodology employs the method of least squares and described linear equations of weight interrelation equation for each component of tank. As a result of QFD based upon the ROC, it was cleared that armor piercing power, main armament, type of ammunition, cruising range, combat weight, armor protection, power loading, threat detection and cost are primary factors influencing design and that combat weight is the most dominant one. The results of TOA based on the combat weight constraint show that 5100 lb reduction was required to satisfy the ROC. The baseline design of a future main battle tank is illustrated with assumption that all phases of QFD are employed to development and production process of subsystems, components, and parts of main battle tank. TOA is applied in iterative process between initial baseline design and ROC. The detailed design of each component is illustrated for a future main battle tank.

• Journal of Welding and Joining
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• v.21 no.1
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• pp.48-53
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• 2003

The object of this study is to examine the effect of short circuit time ratio (SCTR) and current rise delay time (Td) on the spatter generation at low and medium current range in $CO_2$ welding. The spatter was evaluated by the weight generated in the welding of bead-on-plate for 30 seconds (3 times). Td was varied by order of 0, 0.4, 0.8 and 1.2 msec. At each Td, the short circuit time ratio was varied by the output voltage of the welding power source. In the low current range, it was found that the optimum SCTR was 20~25%, and the minimum spatter generation weight was obtained in the case of Td=0.4msec and SCTR=22% even though the remarkable difference was not showed by the application of Td. In the medium current range, it was confirmed that the arc was stable though the SCTR was increased from 20% to 40% by the control of current wave. Spatter generation weight depended on the variation of Td, and the lowest value of spatter generation weight occurred at Td=0.8~1.2msec.