• Tribology and Lubricants
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• v.21 no.6
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• pp.272-277
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• 2005

Continuously variable transmission (CVT) of toroidal type has a elliptical shape of contact zone under the elastohydrodynamic lubrication (EHL) condition, where the power is transmitted only by shearing the lubricant. Due to the small contact area of elliptical shape, the traction of the shear behaviors of lubricant over the contact zone is under extremely high contact pressure over 1.0GPa. During the power transmission by shearing the fluid, many kinds of mechanical movements occur such as squeezing, sliding, rolling and spin. Among the movements, the spin effect that is the most undesirable contact behavior in transmitting the power frequently makes significant abnormal wear damage. In this work, the analysis of elliptical contact of EHL with spin effect is performed, which will give very useful information to understand the traction behaviors in toroidal type of CVT system.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.412-415
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• 2000

Generally, the fault of transmission facilities occurs by natural and artificial causes. Also, these faults are frequently developed by the lightning, a natural phenomenon. Therefore, In this paper, we investigated the case of lightning faults for transmission lines occurred for five years in the west and south of chung-nam province, and then considered a suitable countermeasure for lighting faults in these area

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.220-222
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• 2005

Power system restoration following a wide area or complete blackout starts with energizing primary restorative transmission systems. During this primary restoration process, unexpected over-voltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. This is known as the harmonic resonance phenomenon that may cause burning out of transformer or other devices. Since the harmonic resonance originates from the nonlinear characteristics, it is very difficult to predict the occurrence of this phenomenon. This paper reports the possible existence of the harmonic resonance in Korean power system. Analysis of the harmonic over-voltage is presented based on the various simulations using PSCAD/EMTDC.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.38-39
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• 2006

KEPCO is executing a project in Cambodia consisting of two components, "Power Development Master Plan and Institutional Strengthening" and "Greater Mekong Sub-region (GMS) Power Project Preparation" upon request by the government of the Ministry of Industry, Mines and Energy of Cambodia, contracted on $29^{th}$ September 2005. This paper includes a basic design and review of economical efficiency for constructing the two (2) cross border 115 kV transmission lines, which run from the border of Vietnam and Laos to Cambodia, and four (4) 115kV substations. The main contents of the paper include the process of design and results of a review of line route selection, tower and hardware design regarding transmission line design, as well as the type of substation, and arrangement and specifications of equipment with expects to substation design. Also, long-term demand forecasting, and an economic analysis of the project area are included.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.63-65
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• 2005

Korea Electric Power Corporation (KEPCO) is in charge of the operation and the maintenance for transmission lines and substations in Korean power system which is under the deregulation power market. KEPCO has a main constrain of transmission line toward SEOUL area which is a capital of KOREA because SEOIJL is a huge load of Korean power system. The Korea Electric Power Research Institute (KEPRI)), a division of KEPCO was tasked to study the ATC enhancement of transmission line toward SEOUL using a new line or/and FACTS. This paper summarizes the results of those studies, enhancing the ATC and evaluating the economics.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.305-310
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• 2014

Optimal position of access point (AP) is important for multi-gigabit wireless transmission in terahertz (THz) wireless local area network (WLAN)-type applications, where there exist the THz characteristic multiple clusters in channel propagation. By considering the multiple clusters in THz indoor communications, this paper investigates the optimal AP position when two APs are issued for increasing the system capacity. Numerical results reveal that the central position of each AP within each half service region, which offers the shortest cumulated path length for line-of-sight paths, is optimal to achieve the maximal system capacity.

• Journal of the Optical Society of Korea
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• v.8 no.3
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• pp.104-107
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• 2004

The periodic transmission spectrum of a solid etalon for wide-band capability is analyzed both theoretically and experimentally. In the transmission spectrum with an incident area of a photodetector, the peak wavelength and transmittance are deeply dependent on the incident angle and the divergence angle of the input laser beam. A thermal adjustment for a solid etalon is an optional way to control the transmission spectrum instead of the inefficient fine-angle alignment. In the result, we present the deviations of free spectral range (FSR) by the change in angle and temperature over wide wavelength range.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2006.05a
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• pp.143-147
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• 2006

Wireless sensor networks(WSN) technology has various applications such as surveillance and information gathering in the uncontrollable area of human. One of major issues in WSN is the research for reducing the energy consumption and reliability of data. A system with forward error correction(FEC) can provide an objective reliability while using less transmission power than a system without FEC. In this paper, we propose to use LDPC codes of various code rate(0.53, 0.81, 0.91) for FEC for WSN. Also, we considered node-to-node interference in addition to AWGN channel. The proposed system has not only high reliable data transmission at low SNR, but also reduced transmission power usage.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1628-1632
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• 1994

KEPCO is now promoting the new project of upgrading its highest system voltage from 345kV to 765kV. The main reason of this project is an insurance of bulk power transmission from power complexes at coast to power demand center at Kyoung-In area. The new system needs a careful approach to basic design to secure its reliability and to reduce the increase of investment cost. So, We introduced the basic philosophy of insulation design in spring meeting of this transaction. This paper, after preceding paper, deals with the insulation design example for 765kV transmission lines.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.195-199
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• 2003

BEE 802.11 Wireless LAN protocol uses fixed transmission power. It does not consider a power control mechanism based on the distance between the transmitter and the receiver in order to improve overall channel utilization. In home environment, where stations generally lie around an AP, the AP is subject to use transmission power more than it needs. And wireless LAN stations may require different minimal desired received power. If there are many adjacent BSSs in densely populated WLAN area, they might cause RF interference to one another. In this paper we focus on the improvement of aggregate utilization by mitigating RF interference among BSSs. We show that RF interference by APs can be reduced by controlling transmission power using Link Margin information. The reduced interference will then lead to the increased aggregate throughput which is efficient resource utilization.