• 전자공학회논문지 IE
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• v.43 no.3
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• pp.22-27
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• 2006

This paper presents the control system of high-efficiency automotive 35W metal-halide lamp ballast using the new control method and planar transformer. In this paper, the electronic ballast is designed so that digital control method by microcontroller can be applied to the electronic ballast for the lamp requirement and peripheral environment in order that metal-halide lamp, which has the complicated transient features, is to be applied to the automobile even if it has superior features in brightness, color rendering, light efficiency, and lifespan compared to the conventional halogen lamp. Also, the efficiency increase of the ballast is devised by being varied the switching frequency of Flyback Converter following the battery input voltage of the automobile. Being designed for high-frequency switching transformer of converter in planar form, reduction of loss, weight, overall size are realized and efficient power control in the automobile that had the limited energy and the limited space of battery is devised. The results of the proposed system is verified through various experiment results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.463-468
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• 2007

Some network equipments made in Korea were exposed to severe earthquake in Japan several years ago. More than a hundred slim base transfer network stations had been seized with the severe earthquake at Nigata and it was reported that less than fifteen sets showed blackout by interruption of electricity, not by the structural failure. The purpose of this paper is to check the structural safety of the network equipments by performing table test, and the static and dynamic finite element analysis. For the dynamic test, the station weighing 200 kg was subjected to the Zone 3 earthquake loading of GR-63-CORE on the shaking table to obtain the dynamic responses to compare with the analysis results. It is shown that the FE analysis results are a little bit larger than that of the experimental values. And the sensitivity analysis and optimization for the natural frequency is performed and it is found that the first natural frequency is sensitive to small design change as shown in the results. And the dynamic response of optimized design is less than the original design.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.54-60
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• 2008

The objective of this study is to obtain the optimal process condition and the maximum decomposition efficiency by measuring the decomposition efficiency, electricity consumption, and voltage in accordance with the change of the process variables such as the frequency, maintaining time period, concentration, electrode material, thickness of the electrode, the number of windings of the electrode, and added materials etc. of the harmful atmospheric contamination gases such as NO, $NO_2$, and $SO_2$ etc. with the plasma which is generated by the discharging of the specially designed and manufactured $TiO_2$ catalysis reactor and SPCP reactor. The decomposition efficiency of the NO, the standard samples, is obtained with the plasma which is being generated by the discharge of the combination effect of the $TiO_2$ catalysis reactor and SPCP reactor with the variation of those process variables such as the frequency of the high voltage generator($5{\sim}50kHz$), maintaining time of the harmful gases($1{\sim}10.5sec$), initial concentration($100{\sim}1,000ppm$), the material of the electrode(W, Cu, Al), the thickness of the electrode(1, 2, 3mm), the number of the windings of the electrode(7, 9, 11turns), basic gases($N_2$, $O_2$, air), and the simulated gas($CO_2$) and the resulting substances are analyzed by utilizing FT-IR & GC.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.376-383
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• 2022

The improved performance of computer parts, such as graphic card, CPU, and main board, has led to the need for power supplies with a high power output. The dynamic load profile rapidly changes the usage of power consumption depending on load operations, such as PC power and air conditioner. Under dynamic load profile conditions, power consumption can be classified into maximum, normal, and standby power. Several problems arise in the case of maximum power. Peak power is generated at the system power source in the maximum-power situation. Frequent generation of peak power can cause high-frequency problems and reduce the life of high-pressure parts (especially high-pressure capacitors). For example, when a plurality of PCs are used, system overload occurs due to peak power generation and causes problems, such as power failure and increase in electricity bills due to exceeded contract power. To solve this problem, a system peak power limit/compensation power circuit is proposed for a power supply under dynamic load profile conditions. The proposed circuit detects the system current to determine the power situation of the load. When the system current is higher than the set level, the circuit recognizes that the system current generates peak power and compensates for the load power through a converter using a super capacitor as the power source. Thus, the peak power of loads with a dynamic load profile is limited and compensated for, and problems, such as high-frequency issues, are solved. In addition, the life of high-pressure parts is increased.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.389-394
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• 2004

A Fuzzy Logic Sliding Mode Control or FLSMC for the uninterruptible power system (UPS) is presented, which is tracking a sinusoidal ac voltage with specified frequency and amplitude. The FLSMC algorithm combines feedforward strategy with the Variable Structure Control (VSC) or Sliding Mode Control (SMC) and fuzzy logic control. The control function is derived to guarantee the existence of a sliding mode. FLSMC has an advantage that the stability of FLSMC can be proved easily in terms of VSC. Furthermore, the rules of the proposed FLSMC are independent of the number of system state variables because the input of the suggested controller is fuzzy quantity sliding surface value. Hence the rules of the proposed FLSMC can be reduced. The simulation results illustrate that the purposed approach gives a significant improvement on the tracking performances. It has the small overshoot in the transient and the smaller chattering in the steady state than the conventional VSC. Moreover, its can achieve the requirements of robustness and can supply a high-quality voltage power source in the presence of plant parameter variations, external load disturbances and nonlinear dynamic interactions.

• Journal of Information Science Theory and Practice
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• v.5 no.3
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• pp.61-70
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• 2017

This study investigated the use of e-journals by health researchers in the Nigerian Institute of Medical Research (NIMR). A descriptive survey method was adopted for the study and a questionnaire was used for data collection. The study population was comprised of fifty-four (54) respondents who are health researchers in the institute. The data collected were presented and analyzed using tables, frequency distribution, simple percentages, and charts. The result of the study revealed that all the respondents are aware of the availability of e-journals and attest to making use of them. The study revealed that electronic journals were mostly used for the purpose of conducting research work and the PDF format was preferred for downloading e-journals. However, it was observed that low Internet connectivity and intermittent electricity supply constitute a major obstacle to the use of e-journals. The study, therefore, recommended that the institute's management invest more resources on network connectivity, particularly its bandwidth, and ensure reliable power supply.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1261-1267
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• 2011

Electricity meters using in Korea are about 1.8 million units. From among these, electronic meters for high voltage, about 170 thousand units were installed to the digital type meter and ones for low voltage installed hundreds of thou-sands of meters through a model project. Recently, low voltage meter are expected to complete the installation within several years. Domestic power metering technology is being beyond a simple framework with an electronic type and is rapidly evolving to intelligent smart metering systems in conjunction with promotion of a national smart grid project. Accordingly, it is important to ensure an immunity of meter for electromagnetic field and environmental noise at the installation site. In this paper, we are going to check the validity of international standard that focusing on RF electromagnetic field immunity of meter to secure the quality and improve the reliability in field operation of meter. And we will verify the validity of test specification focused on actual installation environment and are going to offer the improvement plan of test standard.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.151-157
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• 2017

In this paper, it is the result of analysis of the stability by power system analysis about the influence on the power system when the southwest - offshore wind power demonstration complex is constructed to 60MW and it is linked with the onshore power system. Considering the position of the wind turbine actually installed and the length of the cooperating line, we modeled the wind generators, offshore substation and the turbine step-up transformer. Changes of voltage when internal and external faults occurred is analyzed and the reactive power demand according to the amount of electricity generation is derived. And also phase angle stability and frequency is observed through a transient analysis. This paper clarify that there is no problem in the system when only offshore wind power is linked with the grid and try to present the reactive power amount necessary for maintaining the voltage of the point of cooperation appropriately.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.5
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• pp.86-92
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• 1997

An ultrasonic motor(USM) has good characteristics such as compact size, silent motion, high speed responce, low speed and high torque. The USM is driven by 2-phase AC electricity. The control parameters of USM are voltage, phase, and frequency of input powers, etc. In this paper, the fine elasticity and viscosity control with no force feedback can be implemented by a phase difference parameter. Experiment results show the change of torque with regard to elasticity and viscosity. Therefore the USM can be used as a micro-actuator in the automation field of the installation.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.6
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• pp.88-95
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• 1996

The ultrasonic motor(USM) has good characteristics such as compact size, silent motion, high speed responce, low speed and high torque. The USM is driven by 2-phase AC electricity. The control parameters of USM are voltage, phase, and frequency of input powers, etc. In this paper, a voltage difference control is proposed. The voltage difference control has more advantage than phase difference control. Specially, current and power is lower than that of phase difference control. For this voltage diffrence control, we designed USM controller to adjust volatage and phase using PLSI(Programmable Large Scale Integration).