• KIEE International Transactions on Power Engineering
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• v.12A no.1
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• pp.31-35
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• 2002

This paper presents a new operation scheme of UPFC to minimize both generation costs and active power losses in a normal operation state of power system. In a normal operation, cost minimization is a matter of primary concern among operating objectives. This paper considers two kinds of costs, generation costs and transmission losses. The total generation cost of active powers can be minimized by optimal power flow, and active power losses in the transmission system can be also minimized by power flow control of UPFC incorporated with minimization of generation costs. In order to determine amounts of active power reference of each UPFC required for the cost minimization, an iterative optimization algorithm based on the power flow calculation using the decoupled UPFC model is proposed. For verification of the proposed method, intensive studies have been performed on a 3-unit 6-bus system equipped with a UPFC.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.1
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• pp.41-48
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• 2007

In this paper, we propose an optimal placement of sensor nodes with 2.4GHz wireless channel characteristics. The proposed method determines optimal transmission range based on log-normal path loss model, and optimal number of sensor nodes calculating the density of sensor nodes. For the lossless data transmission, we search the optimal locations with self-organizing feature maps(SOM) using transmission range, and number of sensor nodes. We demonstrate that optimal transmission range is 20m, and optimal number of sensor nodes is 8. We performed simulations on the searching for optimal locations and confirmed the link condition of sensor nodes.

• Smart Media Journal
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• v.4 no.1
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• pp.25-32
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• 2015

Powering wireless sensors with energy harvested from the environment is coming of age due to the increasing power densities of both storage and harvesting devices and the electronics performing energy efficient energy conversion. In order to maximize the functionality of the wireless sensor network, minimize missing packets, minimize latency and prevent the waste of energy, problems like congestion and inefficient energy usage must be addressed. Many sleep-awake protocols and efficient message priority techniques have been developed to properly manage the energy of the nodes and to minimize congestion. For a WSN that is operating in a strictly energy constrained environment, an energy-efficient transmission strategy is necessary. In this paper, we present a novel transmission priority decision scheme for a heterogeneous body sensor network composed of normal nodes and an energy harvesting node that acts as a cluster head. The energy harvesting node's decision whether or not to clear a normal node for sending is based on a set of metrics which includes the energy harvesting node's remaining energy, the total harvested energy, the type of message in a normal node's queue and finally, the implementation context of the wireless sensor network.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.550-553
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• 1993

Methods of Alternating Noise Canceling were previously developed for the optical instrumentation;one using a dual photo sensor and another using a single photo sensor that could cancel normal mode noise on a transmission line, even if the noise was of equal status noise. But the methods could not remove noise on sensor line. This paper discusses a new method of using a photo sensor with a resistance sensordummy, effectively canceling equal status normal mode noise not only on a sensor line but also on a transmission line of an optical instrumentation. The accuracy of this method has been verified by experiments using sinusoidal wave as an equal status noise on a sensor line and/or rectangular wave as an equal status wide band noise on a transmission line respectively.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.25-33
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• 2021

Energy-harvesting wireless sensor networks(EH-WSNs) can collect energy from the environment and overcome the technical limitations of existing power. Since the transmission distance in a wireless sensor network is limited, the data are delivered to the destination node through multi-hop routing. In EH-WSNs, the routing protocol should consider the power situations of nodes, which is determined by the remaining power and energy-harvesting rate. In addition, in applications such as environmental monitoring, when there are urgent data, the routing protocol should be able to transmit it stably and quickly. This paper proposes an adaptive routing protocol that satisfies different requirements of normal and urgent data. To extend network lifetime, the proposed routing protocol reduces power imbalance for normal data and also minimizes transmission latency by controlling the transmission power for urgent data. Simulation results show that the proposed adaptive routing can improve network lifetime by mitigating the power imbalance and greatly reduce the transmission delay of urgent data.

• Journal of Plant Biology
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• v.18 no.4
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• pp.139-142
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• 1975

The rye strain 72-1 derived from the cross between ♀(OB, normal)$\times$♂(2B, Ⅵ＋and Ⅵ-) were investigated. It was found that (Ⅵ＋, Ⅵ-), Ⅵ＋, Ⅵ- were segregated and the frequency of quadrivalent per PMC were varied in different plants. The frequency of transmission of B chromosome to the strain 72-1 showed 61.9%. The plnat 72-1-15 was found to be trisomic together with 2 B chromosomes.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1256-1258
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• 1999

Electric industry has been the object of major reforms in many countries. These reforms are aimed at attaining efficiency through competition. Thus network companies do not charge transmission cost for line user the same as method at past. This paper presents a transmission cost allocation through reliability differentiated transmission pricing in competitive electric industry. The proposed method considers only the line capacity affecting the reliability of transmission pricing under normal state and contingency state.

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.89-96
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• 1996

This paper presents a study on the analysis and evaluation for ELF( Extremely Low Frequency) electric and magnetic fields under the transmission line according to the power system states. The power system states are classified into two types, normal state resulting from normal operation and alert state from outages. The current in a system is changed continually owing to the load fluctuations even in a normal operation. To calculate the current of the concerned line in a normal state, the system load level is devided into light, base and heavy load level. In case of contingency, an efficient algorithm based on matrix inversion lemma is developed to figure out the current changes. In order to analyze the variations of ELF field caused by the current fluctuations the electrostatic field approach which is far simpler than the electromagnetic field one based on Maxwell equation is introduced in this paper. The suggested method is applied to the IEEE 14 bus system to demonstrate the usefulness.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.555-557
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• 2003

As electric power transmission systems grow to supply the increasing electric power demand, transmission capacity is larger. but that's really difficult to secure the location for power transmission and distribution to user. The high temperature superconducting(HTS) cable is a method to solve this problem. But for applying to real systems, it needs to investigate the effect of HTS cable. The most important things is the investigation of fault condition. the fault on HTS cable include the quench state. When a fault occur in a circuit, three critical parameters(temperature, current density, magnetic field) exist. when one of these parameters exceeds the critical value, the superconducting becomes normal-conducting. f the cooling power is insufficient to recover the superconducting state, the normal-conducting zone expands. In order to solve these problem, this paper present simulate the quench state considering the over-current and over-voltage in the informal circuit and analyze the quench state.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.60-62
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• 2004

Transmission line outage is influenced by several weather factors: wind, rain snow, temperature, cloud and humidity. And most power system reliability studies assume a failure rate. It can be calculated by transmission line outage data and weather data. Also weather is divided into normal weather and adverse weather by failure rate analysis. The effect of failure rate is discussed with both normal weather and adverse weather. It can be used in effective information about system operation and planing.