• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.1
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• pp.14-19
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• 2002

This paper describes an automatic parts design system for gears, brake, and clutch. These parts are important components of the power transmission assembly. In conventional design process, the design of power transmission requires a number of recurrent calculations and drawings. In this paper, we propose a three-dimensional automatic design system that reduces the number of recurrent calculations and drawings. The system consists of three modules for designing gear, brake, and clutch. The proposed system has been applied to develop a transmission of forklift truck and shown to be a useful system.

• Current Photovoltaic Research
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• v.8 no.3
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• pp.79-85
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• 2020

The growing demand for new energy infrastructure has often been encountered with the difficulties of siting in power plants and electric transmission lines. Siting such large-scale and complex facilities produces so many-sided issues that it is highly necessary to develop an approach to resolving the related problems and conflicts. This paper introduces how the stakeholders have handled the issues and resolved conflicts with residents opposed the construction of 765 kV transmission line. The solar photovoltaic power generation, called "Hee-Mang Sunlight Power project", is used for persuading residents to agree with constructing high-voltage transmission line and sharing benefits. It is considered how the project performance such as generation output and resident's profits is and proposed what the project should be revised and supplement. The project is shown that the intractable spiting in energy systems can be smartly resolved with cost-effective institutional solutions instead of relatively expensive technical ones.

• Journal of Power Electronics
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• v.13 no.3
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• pp.487-496
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• 2013

The three-phase synchronous reference frame phase-locked loop (SRF-PLL) is widely used for synchronization applications in power systems. In this paper, a new control strategy for three-phase grid-connected LCL inverters without a PLL is presented. According to the new strategy, a current reference can be generated by using the instantaneous power control scheme and the proposed positive-sequence voltage detector. Through theoretical analysis, it is indicated that a high-quality grid current can be produced by introducing the new control strategy. In addition, a kind of independent control for reactive power can be achieved under unbalanced and distorted grid conditions. Finally, the excellent performance of the proposed control strategy is validated by means of simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.2
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• pp.184-189
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• 2009

Lightning has been identified as one of the leading causes of outages on transmission and distribution systems. As sensitive loads and reliance on electric power increase year by year, it is getting more focus on stable and high quality of power supply. To protect the transmission and distribution line from lightning, the transmission lightning arrester can be the effective facility on the power system. This paper discusses Gapped type Arresters application results by analysing effects of lightning arresters on transmission and distribution line.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.172-174
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• 2003

Power system restoration following a large black-out starts with charging of primary transmission lines. As the power systems are gradually enlarged and become more complex, the power plant and transmission of electricity units are being expanded continuously. Accordingly, evaluation and reconfiguration of the primary transmission system is needed. So far it has been decided to analyze and evaluate with the knowledge and experience of the corresponding expert. This paper presents an expert system for configuring the optimum primary transmission system based on expert knowledge, static analysis and configuration data.

• Journal of Information Processing Systems
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• v.15 no.3
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• pp.593-603
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• 2019

In wearable healthcare systems, sensor devices can be deployed in places around the human body such as the stomach, back, arms, and legs. The sensors use tiny batteries, which have limited resources, and old sensor batteries must be replaced with new batteries. It is difficult to deploy sensor devices directly into the human body. Therefore, instead of replacing sensor batteries, increasing the lifetime of sensor devices is more efficient. A transmission power control (TPC) algorithm is a representative technique to increase the lifetime of sensor devices. Sensor devices using a TPC algorithm control their transmission power level (TPL) to reduce battery energy consumption. The TPC algorithm operates on a closed-loop mechanism that consists of two parts, such as sensor and sink devices. Most previous research considered only the sink part of devices in the closed-loop. If we consider both the sensor and sink parts of a closed-loop mechanism, sensor devices reduce energy consumption more than previous systems that only consider the sensor part. In this paper, we propose a new approach to consider both the sensor and sink as part of a closed-loop mechanism for efficient energy management of sensor devices. Our proposed approach judges the current channel condition based on the values of various body sensors. If the current channel is not optimal, sensor devices maintain their current TPL without communication to save the sensor's batteries. Otherwise, they find an optimal TPL. To compare performance with other TPC algorithms, we implemented a TPC algorithm and embedded it into sensor devices. Our experimental results show that our new algorithm is better than other TPC algorithms, such as linear, binary, hybrid, and ATPC.

• Smart Structures and Systems
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• v.14 no.4
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• pp.617-641
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• 2014

The energy constraint is still a common issue for the practical application of wireless sensors, since they are usually powered by batteries which limit their lifetime. In this paper, a practical compound energy efficiency strategy is proposed and realized in the implementation of a real time wireless sensor platform. The platform is intended for wireless structural monitoring applications and consists of three parts, wireless sensing unit, base station and data acquisition and configuration software running in a computer within the Matlab environment. The high energy efficiency of the wireless sensor platform is achieved by a proposed adaptive radio transmission power control algorithm, and some straightforward methods, including adopting low power ICs and high efficient power management circuits, low duty cycle radio polling and switching off radio between two adjacent data packets' transmission. The adaptive transmission power control algorithm is based on the statistical average of the path loss estimations using a moving average filter. The algorithm is implemented in the wireless node and relies on the received signal strength feedback piggybacked in the ACK packet from the base station node to estimate the path loss. Therefore, it does not need any control packet overheads. Several experiments are carried out to investigate the link quality of radio channels, validate and evaluate the proposed adaptive transmission power control algorithm, including static and dynamic experiments.

• KIEE International Transactions on Power Engineering
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• v.2A no.3
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• pp.95-101
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• 2002

This paper illustrates a new fuzzy effective load model for probabilistic and fuzzy production cost simulation of the load point of the composite power system. A model for reliability evaluation of a transmission system using the fuzzy set theory is proposed for considering the flexibility or ambiguity of capacity limitation and overload of transmission lines, which are subjective matter characteristics. A conventional probabilistic approach was also used to model the uncertainties related to the objective matters for forced outage rates of generators and transmission lines in the new model. The methodology is formulated in order to consider the flexibility or ambiguity of load forecasting as well as capacity limitation and overload of transmission lines. It is expected that the Fuzzy CMELDC (CoMposite power system Effective Load Duration Curve) proposed in this study will provide some solutions to many problems based on nodal and decentralized operation and control of an electric power systems in a competitive environment in the future. The characteristics of this new model are illustrated by some case studies of a very simple test system.

• International Journal of Computer Science & Network Security
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• v.22 no.4
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• pp.367-373
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• 2022

Femtocells have recently been recognized for their potential to boost network capacity, improve end-user QoS and throughput, and do so at a cheap cost and with ease of implementation. The use of femtocells in indoor environments, such as residential buildings with neighboring homes, is becoming more popular. Femtocells are subject to interference from other femtocells, and the unwanted effects of interference are amplified when femtocells are deployed in close proximity to one another. As a consequence, the network's overall performance is degraded to a significant degree. One of the strategies that is thought to be effective in reducing the impact of interference is altering the transmission power of the femtocells. In this paper, a dynamic downlink transmission power of femtocells is suggested. In accordance with the observed cost function unit, each femtocell automatically changes its transmission power. If a femtocell causes too much interference for its neighbors, its transmission power level will be limited by that interference's rate. A simulation experiment is conducted to validate the effectiveness of the suggested system when compared with other schemes. When compared to previous schemes, which are addressed in this study, the numerical results show that the proposed strategy could provide more capacity while also ideally mitigating the influence of interference among co-channel deployed femtocells.

• 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.