• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.349-355
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• 2009

As electrical power demand is gradually increasing, the construction of power transmission facility is unavoidable. However difficulties which resulted from increasing of complaints and NYMBY make power transmission tower to be more environmentally friendly. As an alternative proposal, a new method which is changing conventional iron arm for insulation arm which is made of FRP(Fiber Glass Reinforced Plastics) is in progress. In this paper, we discussed environmentally friendly characteristic of domestic 154 kV testing transmission tower whose insulation arms have same mechanical and excellent electrical properties compare to conventional heavy iron arm.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.2
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• pp.63-66
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• 2018

Lattice towers and tubular steel poles have been commonly used for electrical power transmission in Korea as well as the other countries. They are durable, structurally stable, simple and can easily be constructed in limited spaces. However, residents are opposed to construct transmission lattice towers in their areas because they are not visually attractive, and electrical field occur at the transmission lines. Underground transmissions have been used instead of the traditional towers to resolve these problems, however they are not cost effective to construct and run. Therefore, we have developed compact towers that are more attractive, well blend into the surrounding environment and much more economical than underground transmissions. This paper shows the design of a compact towers with insulation arm, in order to reduce the height of tower and the separation between phases. The compact tower can be installed in a narrow right-of-way. Insulation arms are easily applied to lattice and steel tubular towers instead of steel arms. Compact towers with insulation arm are also considered as a solution to have public acceptance or to create a familiar atmosphere among towers and people. Compact tower compared with a conventional tower, insulation arms reduces the width and height of the tower by 20% and 15% respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.1-4
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• 2005

The electric power demand is steadily high. It becomes difficult to secure the land for overhead transmission lines year after year. Downsizing of overhead transmission lines can be most effectively achieved by applying polymer insulation arm. This paper describes the outline of compact overhead transmission lines and the result of mechanical evaluation of FRP for the compact transmission towers. Bending strength of FRP was evaluated according to the fiber orientation because the fiber orientation in FRP has a great effect on the strength of FRP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.341-347
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• 2009

As a right-of-way security for the high power transmission line tower construction is becoming more and more difficult, the friendly environmental compact tower design is required. For a proper insulation for the compact tower, the polymer material are being tried. Some countries has already adapted, in the various polymer application and management data, polymer arm insulator to the transmission tower, and shown a stable operation. However, in our country, the polymer arm insulator has left much to be desired in the installation on the transmission line tower. But polymer material has been developed by high strength and technology and is expected to be used in various electric equipments. The polymer arm insulator is a one of good electric insulation materials to expand the power supply capacity in the rapid power demand increasement In this research, the new polymer am insulator is designed and its electric specifications are analyzed. Its mechanical specifications is verified through the field test on the compact tower which is modified by the polymer arm insulator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.870-878
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• 2009

The large increase in the use of electricity has resulted in an ever-growing electric power demand. It has created the need for the construction of power transmission facility located close to the load centers and it also has to require wide right-of-way and large lots, that are not always available, for especially the installation of the towers. The difficulties in acquiring right-of-way have put pressure on energy companies to either upgrade a line on an existing right-of-way to higher voltage or build a new line on a narrow right-of-way. This paper presents the design of a compact tower with polymer Insulation arm, in order to reduce the separation between phases. the compact tower can be built on a narrow right-of-way. the compact tower can be designed based on 345 kV Tower regarding electrical clearances and right of way, therefore the conventional 154 kV Tower can be upgrading transmission line voltages have moved to 345 kV levels.

• Journal of National Security and Military Science
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• s.1
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• pp.231-247
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• 2003

To get the basic data for making comfortable military uniforms and to examine the distribution of clothing microclimate, seasonal fluctuations of skin temperature, subjective sensation, and clothing microclimate were measured from 10 males. The subject were questioned on thermal comfort in experiment. Clothing microclimate temperature at breast, skin temperature at four sites (breast, upper arm, thigh, leg), deep body temperature at eardrum( tympanic temperature), and subjective sensation were measured for an hour in the controlled climatic chamber. The subjects felt comfortable when skin temperature were recorded $34.43^{\circ}C$ at breast, $33.53^{\circ}C$ at upper arm, $32.9^{\circ}C$ at thigh, and 32.50 at leg. Then mean skin temperature was $33.55\pm$$0.63^{\circ}C$. Clothing microclimate temperature ranged from 31.2 to $33.8^{\circ}C$, and clothing microclimate humidity ranged from 49.80～52.41%. In the comparison of these results with the microclimate of military uniforms, it needs more insulation in clothing for military uniforms. It also says that military uniforms should be made of the textiles which can control humidity.

• Journal of Power Electronics
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• v.15 no.3
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• pp.660-669
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• 2015

This paper presents a control scheme with a focus on the combination of phase disposition pulse width modulation (PDPWM) and DC capacitor voltage control for a chopper-cell based modular multilevel converter (MMC) for the purpose of eliminating the time-consuming voltage sorting algorithm and complex voltage balancing regulators. In this paper, the convergence of the DC capacitor voltages within one arm is realized by charging the minimum voltage module and discharging the maximum voltage module during each switching cycle with the assistances of MAX/MIN capacitor voltage detection and PDPWM signals exchanging. The process of voltage balancing control introduces no extra switching commutation, which is helpful in reducing power loss and improving system efficiency. Additionally, the proposed control scheme also possess the merit of a simple executing procedure in application. Simulation and experimental results indicates that the MMC circuit together with the proposed method functions very well in balancing the DC capacitor voltage and improving system efficiency even under transient states.

• Journal of Power Electronics
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• v.17 no.2
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• pp.346-357
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• 2017

The Modular Multilevel Converter (MMC) is particularly attractive for medium and high power applications such as High-Voltage Direct Current (HVDC) systems. In order to reach a high voltage, the number of cascaded submodules (SMs) is generally very large. Thus, in the applications with hundreds or even thousands of SMs such as MMC-HVDCs, the sorting algorithm of the conventional voltage balancing strategy is extremely slow. This complicates the controller design and increases the hardware cost tremendously. This paper presents a Two-Way Merge Sort (TWMS) strategy based on the prediction of the capacitor voltages under ideal conditions. It also proposes an innovative Insertion Sort Correction for the TWMS (ISC-TWMS) to solve issues in practical engineering under non-ideal conditions. The proposed sorting methods are combined with the features of the MMC-HVDC control strategy, which significantly accelerates the sorting process and reduces the implementation efforts. In comparison with the commonly used quicksort algorithm, it saves at least two-thirds of the sorting execution time in one arm with 100 SMs, and saves more with a higher number of SMs. A 501-level MMC-HVDC simulation model in PSCAD/EMTDC has been built to verify the validity of the proposed strategies. The fast speed and high efficiency of the algorithms are demonstrated by experiments with a DSP controller (TMS320F28335).

• Journal of the Korean Society of Clothing and Textiles
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• v.16 no.2
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• pp.245-254
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• 1992

The purpose of this study was to evaluate the mechanical thermal resistances and comfort properties of ski wear made with vapor-permeable water repellent (VPWR) fabrics and thermal insulation battings. Four types of experimental clothing were made with the combination of two VPWR fabrics (Hipora-$TM^{\circledR}$, Hipora-$CR^{\circledR}$) and two thermal insulation battings ($Viwarm^{\circledR},\;Airseal^{\circledR}$). Thermal resistances of ski wear were objectly evaluated by thermal manikin experiment ($21{\pm}\;2^{\circ}C,\;50{\pm}5\%$ R.H.,0.25 m/sec air velocity) and thermographic accessment ($2{\pm}2^{\circ}C,\;0\%$ R.H.,0.25 m/sec air velocity, and emissivity level : 1). Garment wear tests of ski wear included the measurement of the microclimate (inner temp. and relative humidity) of the experimental clothing by digital thermohygrometer and subject wear sensation using McNall's thermal comfort ratings. CBo values of experimental clothing 4 (Hipora-$CR^{\circledR}+Airseal^{\circledR}$) and 1 (Hipora-$TM^{\circledR}+Viwarm^{\circledR}$) were significantly higher than those of 2 (Hipora-$TM^{\circledR}+Airseal^{\circledR}$) and 3 (Hipora-$CR^{\circledR}+Viwarm^{\circledR}$). Thermal resistances in the points of breast, back, belly, and loin was significantly higher than those of upper am, fore arm, and shank of measuring points on the thermal manikin. According to the color map of the thermogram, the experimental clothing 4 indicated higher surface temperatures than the others showing more yellowish spots on the surface of clothing. Inner temperature of experimental clothing was not significantly different among the four types of ski wear, but relative humidities of experimental clothing were significantly different. Relative humidities of experimental clothing 1 and 3 showed higher than those of 2 and 4. Relative humidity of experimantal clothing was affected largely by the thermal resis- tance of thermal insulation batting materials. The subject wear sensation of experimental clothing 2 and 4 showed lower humidity than the others. Subject wear sensation was affected more by humidity sensation than by thermal sensation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.645-650
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• 2010

The continuous increase demand for electric power leads to the additional construction of transmission facilities, but it is not easy to acquire right-of-way for transmission facilities. Therefor, there is a need for compact tower that can be built on a narrow right-of-way the compact tower with polymer insulation arm is a solution. It can be upgrading conventional 154 kV transmission line voltages to 345 kV levels. However transmission voltage is increasing, environment interference (corona noise, radio interference, etc.) will occur gradually. This environment interference is depending on the electrical clearances of tower and configuration of conductors. Therefore the analysis of the factors of environmental interference is necessary in order to upgrading transmission voltage. This paper presents the design factor of a compact tower to meet the environmental interference standard.