• Journal of Electrical Engineering and Technology
• /
• v.8 no.1
• /
• pp.137-143
• /
• 2013

This paper presents development of variable speed generation (VSG) system with energy saving function. The rubber tyred gantry crane (RTGC) requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. Energy saving VSG system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operations.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.1
• /
• pp.36-43
• /
• 2017

This paper describes a hybrid multi-output three-level DC/DC converter suitable for a wide, high-input voltage range of an auxiliary power supply for a high-power photovoltaic generating system. In a high-power photovoltaic generating system, the solar panel output voltage depends on solar radiation quantity and varies from 450Vdc to 1100Vdc. The proposed hybrid multi-output three-level DC/DC converter, which is an auxiliary power supply, would be used as power source for control printed circuit boards and relay and cooling fans in a high-power photovoltaic generating system. The proposed multi-output ($24V_{DC}/30A$, $230V_{DC}/5A$) hybrid three-level boost converter, which uses an energy recovery snubber, is controlled by variable-frequency and phase-shifted modulations and can achieve zero-voltage switching with all operating conditions of input voltage and load range. Experimental results of a 2kW prototype are evaluated and implemented to verify the performance of the proposed converter.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.5
• /
• pp.170-175
• /
• 2003

A control algorithm is developed for highly efficient operation of auxiliary power unit (APU) that consists of a diesel engine and a directly coupled induction generator in series hybrid electric Bus (SHEB). In a series hybrid configuration the APU supplies the electric power needed for maintaining the state of charge (SOC) of the battery unit in various conditions of vehicle operation. As the rotational speed of generator does not depend on the vehicle speed, an optimized operation of engine-generator unit based on the efficiency map of each component can be achieved. The output torque of diesel engine can be controlled by the amount of fuel injection, and the power converted from mechanical to electrical energy can be adjusted by generate control unit (GCU) using the decoupling vector control of torque and flux. As for the given reference of the generating power, the multiply of speed and torque, many combinations of operating speed and torque are possible. The algorithm decides the new operating point based on the engine efficiency map and generator characteristic curve. During the transition of operating points, the speed controller saturation is avoided using variable limit and filtering of generator torque reference. A test rig and SHEB consist of a 1.5L diesel engine and a 30kw induction generator are constructed by Hyundai Motor Company.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.39 no.6
• /
• pp.563-569
• /
• 2021

With the launch of Compact Advanced Satellite 500 series of various characteristics and the operation of KOMPSAT-3/3A, uses of high-resolution satellite images have been continuously increased. Especially, in order to provide satellite images in the form of ARD (Analysis Ready Data), various pre-processing such as geometric correction and radiometric correction have been developed. For pre-processing of high spatial satellite imagery, auxiliary information, such as solar zenith, solar azimuth and offnadir angle, should be required. However, most of the high-resolution satellite images provide the solar zenith and nadir angle for the entire image as a single variable. In this paper, the solar zenith and offnadir angle corresponding to each pixel of the image were calculated using RFM (Rational Function Model) and auxiliary information of the image, and the quality of extracted information were evaluated. In particular, for the utilization of pixel-based solar zenith and offnadir angle, pixel-based auxiliary data were applied in calculating the top of atmospheric reflectance, and comparative evaluation with a single constant-based top of atmospheric reflectance was performed. In the experiments using various satellite imagery, the pixel-based solar zenith and offnadir angle information showed a similar tendency to the auxiliary information of satellite sensor, and it was confirmed that the distortion was reduced in the calculated reflectance in the top of atmospheric reflectance.

• Journal of Digital Convergence
• /
• v.11 no.2
• /
• pp.175-182
• /
• 2013

In this paper, the simulation model of house price is presented on the basis of pricing mechanism between the demand and the supply of apartments in seoul. The algorithm of house price simulation model for calculating the rate of price over time includes feedback control theory. The feedback control theory consists of stock variable, flow variable, auxiliary variable and constant variable. We suggest that the future price of apartment is simulated using mutual interaction variables which are demand, supply, price and parameters among them. In this paper we considers three items which include the behavior of apartment price index, the size of demand and supply, and the forecasting of the apartment price in the future economic scenarios. The proposed price simulation model could be used in public needs for developing a house price regulation policy using financial and non-financial aids. And the quantitative simulation model is to be applied in practice with more specific real data and Powersim Software modeling tool.

• Journal of Preventive Medicine and Public Health
• /
• v.28 no.3 s.51
• /
• pp.663-677
• /
• 1995

Special health examination institute has done periodic health examination for workers who have worked in the hazardous workplace. However, assessment on outcome in special health examination institute about detection ability of occupational disease has not been. In this circumstances, we studied on the differences of health examination outcome among special health examination institutes and identified related factors which affected outcome of special health examination in the special health examination institutes. The summary of the results were as follows. 1. 50 special health examination institutes were examined in this study. Among them, university institutes were 13 cases(26.0%), hospitals were 20 cases(40.0%), a corporation aggregates were 9 cases(18.0%) and an auxiliary organs of company were 8 cases(16.0%). There were 29(58.0%) institutes with a preventive medicine specialist, but 21 institutes(42.0%) were not. 2. Total workers examined in 50 institutes were 606,948 and workers diagnosed as occupational disease$(D_1)$ were 3,156. The rate of occupational disease was 6 workers per 1,000 examined workers. Workers needed for close observation(C) were 95,809 and the rate of workers needed for close observation was 141 per 1,000 examined workers. 3. The rate of occupational disease of university institutes was highest(11.3 per 1,000 examined workers), and followed by hospitals(6.0 per 1,000 examined workers), a corporation aggregates(4.2 per 1,000 examined workers), and an auxiliary organs of company(1.2 per 1,000 examined workers). The difference of the rate of occupational disease between university institutes and an auxiliary organs of company was statistically moderate significant(p<.1). The rate of occupational disease in special health examination institutes with establishment duration was more than 10 years was statistically higher than institutes with establishment duration was less than 10 years(p<.1). 4. The results of multiple regression, $R^2$ was 0.3394(adjusted $R^2$ was 0.2109), F-value was 2.6416(p<.05), and statistically significant variables were establishment duration(p<.01), number of examined workers per one doctor(p<.1), and auxiliary organs of company(p<.1), which dependent variable was the rate of occupational disease and independent variables were number of examined workers per one doctor, classification of institute, the rate of working environment exceeding TLV, duration of institute establishment, presence of a preventive medicine specialist.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.20 no.4
• /
• pp.440-445
• /
• 2011

This paper presents a new regenerative brake system of electric vehicles that employs a continuous variable transmission(CVT) and a flywheel. The developed device has advantages over existing regenerative brakes from a standpoint of reliability and versatility in actual driving conditions. The system consists of a CVT, two wheels, a flywheel, a coupling and auxiliary powertrain components. The CVT is designed as a combination of two cones and a roller, which causes the velocity difference between the wheel and the flywheel. The power flow of the flywheel system is controlled by the CVT roller and the coupling through step motors. A prototype has been developed and then its performance has been investigated for various operating conditions. Results show that the storage efficiency of the flywheel is much affected by the vehicle's velocity and it is reduced below 20% for high speed, as compared to the 25% efficiency for an ideal condition. The CVT is a primary factor for lowering the flywheel efficiencies due to large friction and slipping between the cone and the roller.

• Communications for Statistical Applications and Methods
• /
• v.16 no.1
• /
• pp.169-183
• /
• 2009

The simplicity and wide application of Greenberg et al. (1971) prompts to propose a set of alternative estimators of population total for multi-character surveys that elicit simultaneous information on many. sensitive study variables. The proposed estimators take into account the already known rough value of the correlation coefficient between Y(the characteristic under study) and p(the measure of size). These estimators are biased, but it is expected that the extent of bias will be smaller, since the proposed estimators are suitable for situations in between those optimum for the usual estimators and the estimators based on multi-characters for no correlation. The relative efficiency of the proposed estimators has been studied under a super population model through empirical study. It has been found through simulation study that a choice of an unrelated variable in the Greenberg et al. (1971) model could be made based on its correlation with the auxiliary variable used at estimation stage in multi-character surveys.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.11
• /
• pp.861-867
• /
• 2014

In this study, a semi-active isolator was constructed from applying a MR damper that used the MR fluid to an isolator. The parameter identification was also performed to determine the characteristics of this semi-active isolator during which the least squares method and the auxiliary variable method were applied to produce a value closest to the true value. In addition, the MR damper's nonlinear damping force was closely analyzed to greatly reduce the range of error. Based on this analysis, it was discovered that the parameter tended to increase with more electric current. Such analysis of the dynamic properties of semi-active isolator proved that constructing an isolator that provides a more stable operation could be achieved.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.33 no.8
• /
• pp.289-298
• /
• 1984

The single phase induction motor is recently requested to meet a broad speed control and smooth forward and reverse operation due to the multifarious usages. This paper deals with two phase operation of a two winding motor by reference current adaptive inverter which can supply the currents to satisfy the balanced oeration into the main and auxiliary winding through the entire operational region. According to the roposed system, the starting, forward and reverse and variable speed control of a two winding motor eliminated the capacitor from the capacitor-run motor is also possible. The formation and its principle of the reference current adaptive inverter and characteristic analysis of the motor fed by this apparatus are described in this paper. Excellent agreement with the measured results and calculated values by computer simulation is obtained.