• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.7
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• pp.560-565
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• 2010

This paper presents the design factor of an overhead transmission tower structure in order to reduce the tower weight. The behaviour of transmission tower structures are affected by the horizontal angle of the tower structure, the equivalent wind pressure group, the slope of the main post of the tower, the separation of the internode and the use of high-strength materials in their construction. Tower weight can be reduced by approximately 30% reduce weight by means of optimal design based on a consideration of all the above factors. In addition, the design of the foundation of the tower with the shear key installation to increase horizontal support together with a modified angle of inclination to the ground can reduce by about 37% the amount of concrete used during construction. The area of ground disturbed by the construction of the tower foundation can thus be reduced by approximately 33%. Therefore it is possible to build an environmently-friendly T/L tower with the mechanical properties of existing towers.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.135-146
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• 2013

PURPOSES : This study aimed to analyze the impact the operation of pre-signals at 4-leg signalized intersections and present primary environmental factors of roads that need to be considered in the installation of pre-signals. METHODS : Shift of proportions safety effectiveness evaluation method which assesses shifts in proportions of target collision types to determine safety effectiveness was applied to analyze traffic crash by types. Also, Empirical Bayes before/after safety effectiveness evaluation method was adapted to analyze the impact pre-signal installation. Negative binomial regression was conducted to determine SPF(safety performance function). RESULTS : Pre-signals are effective in reducing the number of head on, right angle and sideswipe collisions and both the total number of personal injury crashes and severe crashes. Also, it is deemed that each factor used as an independent variable for the SPF model has strong correlation with the total number of personal injury crashes and severe crashes, and impacts general traffic crashes as a whole. CONCLUSIONS: This study suggests the following should be considered in pre-signal installation on intersections. 1) U-turns allowed in the front and rear 2) A high number of roads that connect to the intersection 3) Many right-turn traffic flows 4) Crosswalks installed in the front and rear 5) Insufficient left-turn lanes compared to left-turn traffic flows or no left-turn-only lane.

• Steel and Composite Structures
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• v.32 no.6
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• pp.769-778
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• 2019

The specially prefabricated steel moment connections with pyramid head is one of the significant innovations in the steel structures forms to improve the installation time and simplify the construction procedure. The beams in this structure form are supported by two top and bottom angles and web double angles. Such a configuration despite its advantages increases the welding operation and filed installation time and costs. In this paper, the effect of using beams with channel and I section in three classes of seismically compact, seismically non-compact, and slender section according to width-to-thickness ratio on the behavior of the connection was investigated under monotonic and cyclic loading. Modeling was performed by ABAQUS and verified by the results of an experimental specimen. The findings indicated that using I and channel section instead of angle section reduces the amount of welding materials as well as easing the installation procedure. However, it has no significant effect on the ultimate strength and ductility of the connection. Furthermore, if the beam section is seismically compact, this form is considered as a special moment frame that has a rotation capacity up to 0.04 radians without any reduction in connection moment resistance.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.78.1-78.1
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• 2010

Recently, as much supplied with new-renewable energy, as much invested in PV system. PV system consists of PV module, PCS and Monitering system, and also could be classified into the type and the capacity by installation method and cost etc. When various systems are installed in the field, it is needed to research for applying in the field and establish infrastructure in order to ensure stable efficiency and reliability. In this study, as the basic design of the demonstration test facility, it is designed the basic PV systems for each capacity to test each PCS. In addition, It is drew the climatic conditions such as insolation, temperature and the design parameters such as installation angle, shades for the local demonstration project and expected the generation of each PV system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.138-146
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• 2010

On wind turbine generators, the speed and volume of the wind affect the turbine angle speed which finally determines the output level of the electric power. However it is very difficult to forecast correctly the future power output and quality based on previous fixed sampling methods. This paper proposes a variable sampling method based on Buneman frequency estimation algorithm to reflect the variations of the frequency and amplitude on wind power outputs. The proposed method is also verified through the performance test by comparing with the results from previous fixed sampling methods and the real measurement data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.9
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• pp.89-95
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• 2015

This paper presents a current sensorless maximum torque control of a synchronous reluctance motor drive. Stator current and current angle vs. maximum torque are obtained using measured d-axis and q-axis inductances. Then, d and q-axis stator voltage references for current sensorless maximum torque control are calculated from stator voltage equations. The proposed method is verified by simulation results comparing with conventional method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.60-65
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• 2003

In this paper, we analyzed theoretically design requirement of a clamp-type optical current transformer(COCT)head, and manufactured a COCT head based on design requirement. Also, we measured and analyzed the current of conductor, and change of optical power and sensitivity with incidence angle of light using COCT head, and demonstrated the feasibility of manufactured COCT through those experiments.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.2
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• pp.84-95
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• 1991

Mostly, phase control method is used to control the single phase AC power. The phase control method has some advantages such as ease to control and simple configuration. But the retardation of firing angle causes a lagging current even if load is purely resistive. So phase control causes a lagging power factor and a low efficiency at the input side in comparing with the system without switching device. A new PWM control method which can improve these defects for single phase AC power control circuit is proposed in this paper. The performances of the single phase AC power control circuit using the proposed method was investigated theoretically. Both power factor and waveform of load current can be improved better than those of the conventional methods.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.229-232
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• 2002

In this paper, we described the laboratory layout of the optical CT in connection with the measurement of large current for the GIS. The aim of this study is the development and application of optical CT based on Faraday effect. It was used He-Ne laser for light source (633nm) and was used PIN-Photodiode for light receiver. The laser source passes through optical fiber in single mode. We used the polarizer to polarize the light source and the beam splitter to divide the output light, and the optical fiber is connected for the measuring the angle polarized in the magnetic field.

• 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.81-87
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• 1996

This paper is to develop a digital inverter using microcontroller for a Switched Reluctance Motor (SRM) driver. The closed-loop speed control system with fixed switching angle and variable voltage control is used to from a flat-topped phaes current and to simplfiy the drive system. This could be driven in a wide speed range with flat-topped current. Mifcrocontroller os used to be compact and to have a flexbility in the control system.