• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.959-965
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• 2011

As the usage of mobile stations increases thanks to various services, power saving mechanisms of mobile station operated by battery power have been gained much attention. This paper presents a power saving mechanism(PSM) of IEEE 802.16m, called Mobile WiMAX, for 4G mobile technology. This paper first presents different points of the PSM of IEEE 802.16m from IEEE 802.16e, which is a basis of IEEE 802.16m. This paper proposes a dynamic sleep cycle adjustment algorithm for improving the performance of IEEE 802.16m PSM by considering the arrival pattern of incoming packets from base station. Performance of the algorithm is analyzed in terms of energy consumption as well as waiting time of packets.

• Journal of Communications and Networks
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• v.14 no.2
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• pp.179-187
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• 2012

Power saving is one of the most important features that extends the lifetime of portable devices in mobile wireless networks. The IEEE 802.16e mobile broadband wireless access system adopts a power saving mechanism with a binary truncated exponent algorithm for determining sleep intervals. When using this standard power saving scheme, there is often a delay before data packets are received at the mobile subscriber station (MSS). In order to extend the lifetime of a MSS, the battery energy must be used efficiently. This paper presents a dynamically alternating sleep interval scheduling algorithm as a solution to deal with the power consumption problem. We take into account different traffic classes and schedule a proper sequence of power saving classes. The window size of the sleep interval is calculated dynamically according to the packet arrival rate. We make a tradeoff between the power consumption and packet delay. The method achieves the goal of efficiently reducing the listening window size, which leads to increased power saving. The performance of our proposed scheme is compared to that of the standard power saving scheme. Simulation results demonstrate the superior performance of our power saving scheme and its ability to strike the appropriate performance balance between power saving and packet delay for a MSS in an IEEE 802.16e mobile broadband wireless access system.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1235-1240
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• 2005

This paper supposes the perfect power control at micro-cell and macro-cell. Under this supposition, we calculate SIR and decide the call admission by SIR. When we calculate SIR, we use the ratio of the power received the base station of micro-cell and the power received the base station of macro-cell. We analysis the performance of the system by the computer simulation while changing the ratio of power.

• Journal of Industrial Technology
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• v.31 no.B
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• pp.17-21
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• 2011

Since the railway passenger services have been recognized as important factor for success in railway, electrical energy consumption in railway station for high quality service has greatly increased. Furthermore, the number of the private railway station has gradually increased. Therefore, the operation conditions for railway power distribution system is dramatically changed in comparison with the past. So, this paper proposes the optimal construction method for railway power distribution system considering economical efficiency and the reliability of power supply to establish the railway power distribution system standard for the future railway industry.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4331-4346
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• 2015

The femtocell network, which is designed for low power transmission and consists of consumer installed small base stations, coexists with macrocells to exploit spatial reuse gain. For its realization, cross-tier interference mitigation is an important issue. To solve this problem, we propose a joint access and power control scheme that requires limited information exchange between the femto and macro networks. Our objective is to maximize the network throughput while satisfying each user's quality of service (QoS) requirement. To accomplish this, we first introduce two distributed interference detection schemes, i.e., the femto base station and macro user equipment based schemes. Then, the proposed scheme dynamically adjusts the transmission power and makes a decision on the access mode of each femto base station. Through extensive simulations, we show that the proposed scheme outperforms earlier works in terms of the throughput and outage probability.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.12
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• pp.522-528
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• 2006

Korean power system has some problems like as curtailing investment and the NIMBY (Not In My Back Yard) phenomena, because of power demand concentration in downtown area. In this time, superconducting power devices rise as a very attractive solution. This study proposes a basic concept of superconductivity power system with distributed switching station, and identifies the items for technical and economic analysis. The proposed system consists of superconducting cables/ transformers/FCLs(fault current limiters). The basic concept is to replace 154kV conventional cables with 22.9kV superconducting cables and to convert a 154kV substation into 22.9kV distributed switching stations in downtown area.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.87-92
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• 2022

Recently, there has been an increasing demand for electric equipment installed on the ground to be installed in an underground space. Accordingly, U-CDS (Underground-Compact Distribution Station) installed in the underground is supplied, and to improve its weak ventilation performance, an Airdam-type structure was applied and the effect was analyzed. As a result, the temperature around the transformer was reduced by up to 9.5 degrees, and the air flow increased by up to 1.17 m/s. Airdam structure can be supplied in the form of various sculptures because it is possible to design freely while maintaining its principle.

• Proceedings of the KOR-KST Conference
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• 1996.06a
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• pp.95-128
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• 1996

Dipped track profiles between rail transit stations can significantly reduce propulsive energy, braking energy and travel times. This work quantifies their potential benefits for circumstances reflected in various values for dips, speed and acceleration limits, station spacings, and available power. A deterministic simulation model has been developed to precisely estimate train motions and performance using basic equations for kinematics, resistance, power and braking. For a dip of 1% of station spacing, in which gradients never exceed 4%, our results show savings (compared with level tracks) exceeding 9% for propulsive energy, 15% for braking energy and 5% for travel time between stations.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1868-1872
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• 2010

The LED illuminator has merits that it has low power consumption, long life and emits low Co2 gas. As it has many merits in comparison with existing illuminator it is a realistic alternative. but its possession in illuminator market shows slow increasement unexpectedly. Because its price is very high only low power consumption can not keep pace with economical efficiency. In this paper I analyzed economical efficiency about LED illuminator when it is applied at subway station.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2396-2398
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• 1998

The Distribution Automation System(DAS) Master Station(MS) is the core of the system, which has the functions of supervising, data acquisition, processing and man-machine interface. In this paper, we suggested the optimal configuration of the medium/small scale DAS MS in accordance with the consideration of various requirements such as reliability, scalability flexibility, etc.