• Journal of Drive and Control
• /
• v.19 no.4
• /
• pp.54-61
• /
• 2022

This is a basic study analyzing emissions of an agricultural tractor during tillage operations. In this study, CO, THC, NOx, and PM considered as emission factor were analyzed during plow and rotary tillage operation by the tractor. Engine torque and rotational speed were measured through ECU. Engine power was calculated using engine torque and rotational speed. The emissions was calculated based on the number of units, rated power, load factor, and operating time. Results showed that the load factor was calculated almost twice, which was higher than 0.48. It was also observed that the emission of the tractor was variable for different agricultural operations because tractor loads were different based on operations. There was a difference in emissions due to differences in plow and rotary working hours. To estimate the emission of agricultural tractor based field operations in detail, it is necessary to consider TAF (Transient Adjustment Factor) and DFA (Deterioration factor). In the future, TAF and DFA will be considered to estimate emissions of the agricultural tractor. Finally, results of this study can contribute to the literature to estimate tractor emissions accurately.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.1
• /
• pp.73-81
• /
• 2011

The performance of emission factor has been validated by comparison with on-road test data. Emission factor, which is a function of vehicle speed, has been acquired based on chassis dynamometer test with NIER driving pattern. Portable Emission Measurement System, PEMS has measured on-road emission. Test vehicle was operated on defined test routes under different driving conditions, and made ten trips along its route. Emission factors properly simulate on-road test result, although there is some drawback to consider variety of driving condition on real world. Vehicle specific power and acceleration have been used to explain the distributed on-road result within same vehicle speed range. The trend in carbon dioxide and nitrogen oxide emission with respect to specific power and acceleration is clear. It has been found that specific power is a good explanatory variable for microscopic analysis for modal test result. Acceleration is good for microscopic as well as macroscopic analysis.

• Structural Engineering and Mechanics
• /
• v.13 no.3
• /
• pp.329-343
• /
• 2002

In this research, the dynamic stability of an orthotropic elastic conical shell, with elasticity moduli and density varying in the thickness direction, subject to a uniform external pressure which is a power function of time, has been studied. After giving the fundamental relations, the dynamic stability and compatibility equations of a nonhomogeneous elastic orthotropic conical shell, subject to a uniform external pressure, have been derived. Applying Galerkin's method, these equations have been transformed to a pair of time dependent differential equations with variable coefficients. These differential equations are solved using the method given by Sachenkov and Baktieva (1978). Thus, general formulas have been obtained for the dynamic and static critical external pressures and the pertinent wave numbers, critical time, critical pressure impulse and dynamic factor. Finally, carrying out some computations, the effects of the nonhomogeneity, the loading speed, the variation of the semi-vertex angle and the power of time in the external pressure expression on the critical parameters have been studied.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.12
• /
• pp.42-47
• /
• 2011

The design of road lighting is aiming illuminance and luminance requirements for road lighting. In the process, various factors associated with luminaires such as luminous efficacy, light distribution, mounting height, spacing and maintenance factor are considered. However, there has been no restriction on lighting power density. In this study, lighting power density has been comparatively analyzed through a study of related data and a result of measurements on domestic roads. And, it has been analyzed by simulation results for road in which lighting conditions are variable. In terms of the limitation on power density for road lighting, road lighting can be designed using high efficacy lighting systems for energy saving.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.382-384
• /
• 2008

Hold-up time is a special requirement for the front end DC/DC converter in a server power supply. It forces the converter with the variable switching frequency to operate in a wide switching frequency range, which makes the regulation difficult and reduces the power density. In this paper a novel frequency controlled half bridge converter with the hold-up time extension circuit is proposed. During the hold-up time, the auxiliary switches are turned on, thus the resonant inductance is reduced and the voltage conversion ratio is increased. Therefore, the output capacitor of the power factor correction (PFC) circuit can be decreased, and the converter can have high power density. The proposed converter is verified by experimental results from a prototype with 700W, 400V input, and 12V output.

• Journal of the Korean Society of Industry Convergence
• /
• v.21 no.2
• /
• pp.71-78
• /
• 2018

In this paper, we propose the performance enhancement of solar individual string power generation system using booster power control for voltage compensation. The proposed control method determines the variable voltage for the compensator using direct power control (DPC) modeling applied to motion factor estimation. This method also maintains excellent dynamic response to the characteristics of direct power control (DPC) by calculating the mismatch ratio of the arrestered PV modules. The validity of the proposed algorithm is verified through simulation and experiments.

• Nuclear Engineering and Technology
• /
• v.54 no.7
• /
• pp.2435-2443
• /
• 2022

The once-through steam generator used in the small modular reactor needs to consider the stability of the outlet steam pressure and steam superheat of the secondary circuit to achieve better operating efficiency. For this reason, this paper designs a controllable operation scheme for the steam pressure and superheat of the small reactor once-through steam generator. On this basis, designs a variable universe fuzzy controller, first, design the fuzzy control rules to make the controller adjust the PI controller parameters according to the change of the error; secondly, use the domain adjustment factor to further subdivide the input and output domain of the fuzzy controller according to the change of the error, to improve the system control performance. The simulation results show that the operation scheme proposed in this paper have better system performance than the original scheme of the small reactor system, and controller proposed in this paper have better control performance than traditional PI controller and fuzzy PI controller, what's more, the designed control system also showed better anti-disturbance performance in lifting experiment between 100% and 80% working conditions. Finally, the experimental platform formed by connecting the digital small reactor with Matlab/Simulink through OPC(OLE for Process Control) communication technology also verified the feasibility of the proposed scheme.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.21 no.6
• /
• pp.770-777
• /
• 2015

Recently, due to the rapid development of Power Electronics, the usage of Non Linear Load variable frequency drivers (VFDs) is increasing in the electric propulsion vessels and offshore plants. And harmonics which is generated by the variable frequency drives is an important issue should be solved. Ac line reactors and dc link reactors are widely used in variable frequency drives to improve the drive performance such as reducing input current harmonics, elevating input power factor, and protecting the drives from surges, etc. The effectiveness of both types of reactors in reducing input harmonics is affected by the loading of the drives and the system source impedance. And it considered that inductance of DC link reactors should be about 1.7 times of AC line reactors for same effect. The rules to evaluate the needs and effectiveness using ac line or dc link reactors are proposed for practical appications. In this paper, a simulation is performed to investigate of such factors using software PSIM.

• Proceedings of the KIPE Conference
• /
• 1998.11a
• /
• pp.33-37
• /
• 1998

For the high power variable speed applications, the DCTLI(diode clamped three-level inverter) have been widely used. This paper describes the analysis of the neutral point current of the DCTLI and the improved space vector-based PWM strategy considering the switching frequency of power devices, that minimizes the fluctuation of the neutral point current in spite of high modulation index region and low power factor. It contributes to decrease the capacitance of dc-link capacitor bank and to increase the neutral point voltage controllable region. Especially, even if second (or even) order harmonic is induced in load current (at this situation, is was investigated that the general control method can not suppress the neutral point voltage variation), this PWM can provide effective control method to suppress the neutral point voltage variation. Various simulation results by means of Matlab/Simulation are presented to verify the proposed PWM.

• Journal of Fashion Business
• /
• v.5 no.3
• /
• pp.19-34
• /
• 2001

The purpose of this study was to investigate the differences of the general characteristics of subjects, the utilizing realities and the degree of satisfaction in the shopping mall and purchasing intention between group I that specializes in fashion design and group II that doesn't specialize in it. The results are summarized as the following six aspects. First, as a result of the general characteristics of subjects and the utilizing realities, the most different variables were the visiting frequency and the goods purchasing frequency. The result indicated that group II took more interests than group I. Second, as a result of the degree of satisfaction according to the factors of the general characteristics of subjects and the utilizing realities in the shopping mall, both group I and group II showed high degree of satisfaction in factor 1 (variety of event) whereas both groups showed relatively low degree of satisfaction in factor 3 (variety of goods). Third, as a result of the degree of satisfaction according to the general characteristics of subjects and the utilizing realities, group I showed significant differences in the degree of satisfaction according to a monthly allowance of pocket money and goods purchasing frequency and group II showed significant differences in the degree of satisfaction according to grade, the utilizing reason, goods purchasing frequency. Fourth, as a result of purchasing intention of fashion goods according to the general characteristics of subjects and the utilizing realities, group I showed the higher purchasing intention of fashion goods in group that the terms of payment was on-line payment than group that they was credit card. On the other hand, group II showed a significant difference in grade, which showed that group that was above third grade had the higher purchasing intention of fashion goods than group that was under third grade. Fifth, as a result of purchasing intention of fashion goods according to the degree of satisfaction, group I showed significant differences in factor 1 and factor 3 among the degree of satisfaction. In other words, group that had high degree of satisfaction in factor 1 showed the higher purchasing intention of fashion goods than other groups and group that had medium degree of satisfaction in factor 3 showed the higher purchasing intention of fashion goods than other groups. In group II, on the other hands, group that had high total degree of satisfaction showed the higher purchasing intention of fashion goods than other groups. Sixth, as a result of relative influencing power of independent variable with respect to purchasing intention of fashion goods in group I, the higher degree of satisfaction in factor 1 and the lower degree of satisfaction in factor 3 showed, the higher purchasing intention of fashion goods showed. As a result of relative influencing power of independent variable in group II, however, the higher grade and the higher degree of satisfaction in factor 1 showed, the higher purchasing intention of fashion goods showed.