• Journal of Advanced Information Technology and Convergence
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• v.10 no.1
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• pp.57-69
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• 2020

In general, many IoT devices, including smart phones, use LTE, Wi-Fi, and Bluetooth, and these communication modules generate a lot of energy consumption during periodic data transmission. This paper proposes a method of the data transmission mode change for improving energy efficiency in various communication environments that mobile devices may encounter. We propose an algorithm for setting the mode considering energy efficiency, data transmission performance and cost when the mobile device transmits data, and transmitting the data in an optimized manner according to the state of the mobile device. The proposed algorithm is implemented through experiments on energy efficiency for each communication module, and the scenario is used to verify how efficiently the proposed algorithm uses energy.

• 한국ITS학회:학술대회논문집
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• 2010.05a
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• pp.5-9
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• 2010

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.52-59
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• 2008

This paper describes the secant method for solving the economic dispatch (ED) problem with generator constraints and transmission losses. The ED problem is an important optimization problem in the economic operation of a power system. The proposed algorithm involves selection of minimum and maximum incremental costs (lambda values) and then the evaluation of optimal lambda at required power demand is done by secant method. The proposed algorithm has been tested on a power system having 6, 15, and 40 generating units. Studies have been made on the proposed method to solve the ED problem by taking 120 and 200 units with generator constraints. Simulation results of the proposed approach were compared in terms of solution quality, convergence characteristics, and computation efficiency with conventional methods such as lambda iterative method, heuristic methods such as genetic algorithm, and meta-heuristic methods like particle swarm optimization. It is observed from different case studies that the proposed method provides qualitative solutions with less computational time compared to various methods available in the literature.

• Journal of Magnetics
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• v.22 no.1
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• pp.43-48
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• 2017

In order to detect the current flowing through concealed conductor, this paper proposes a new method based on derivative method. Firstly, this paper analyzes the main peak characteristic of the derivative function of magnetic field generated by a current-carrying conductor, and a relationship between the current flowing through the conductor and the main peak of the derivative function is obtained and applied to calculate the current. Then, the method is applied to detect the conductor current flowing through grounding grids of substations. Finally, the numerical experimental and field experiment verified the feasibility and accuracy of the method, and the computing results show that the method can effectively measure the conductor current of grounding grids with low error, and the error is within 5 %.

• Journal of the Korea Society of Computer and Information
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• v.20 no.8
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• pp.7-13
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• 2015

Recently, there are serviced user customized advertisement of various type using smart device. Representative services are advertisement service using light of smart TV screen or audible sound of smart TV to transmit advertisement information. However, those services have to do a specific action of smart device user for advertisement information or need audible audio information of TV contents. To overcome those weakness, therefore, we propose an advertisement method using inaudible sound of speaker based on smart device. This method supports the transfer of advertising content to the smart device user with no additional action or TV audio signal required to access that content. The proposed method used two high frequencies among 18kHz ~ 22kHz of audible frequency range which smart TV can send out. And it generates those frequencies synthesized with audio of TV contents as trigger signal which can send advertisements to smart device. Next, smart device analysis the trigger signal and request advertisement contents related to the signal to server. After then, smart device can show the downloaded contents to user. Because the proposed method uses the high frequencies of sound signals via the inner speaker of the smart device, its main advantage is that it does not affect the audio signal of TV content. To evaluate the efficacy of the proposed method, we developed an application to implement it and subsequently carried out an advertisement transmission experiment. The success rate of the transmission experiment was approximately 97%. Based on this result, we believe the proposed method will be a useful technique in introducing a customized user advertising service.

• Analytical Science and Technology
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• v.37 no.2
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• pp.114-122
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• 2024

A transmission Raman spectroscopy-based quantitative model, which can analyze the content of a drug product containing naproxen sodium as its active pharmaceutical ingredient (API), was developed. Compared with the existing analytical method, i.e., high-performance liquid chromatography (HPLC), Raman spectroscopy exhibits high test efficiency owing to its shorter sample pre-treatment and measurement time. Raman spectroscopy is environmentally friendly since samples can be tested rapidly via a nondestructive method without sample preparation using solvent. Through this analysis method, rapid on-site analysis was possible and it could prevent the production of defective tablets with potency problems. The developed method was applied to the assays of the naproxen sodium of coated tablets that were manufactured in commercial scale and the content of naproxen sodium was accurately predicted by Raman spectroscopy and compared with the reference analytical method such as HPLC. The method validation of the new approach was also performed. Further, the specificity, linearity, accuracy, precision, and robustness tests were conducted, and all the results were within the criteria. The standard error of cross-validation and standard error of prediction values were determined as 0.949 % and 0.724 %, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2279-2284
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• 2017

Recent wireless communications using the unlicensed band have been on the rise and the range of use is increasing. The license-exempted band is a prerequisite for accepting interference between telecommunication equipment. In particular, the interference phenomenon of Bluetooth, wireless LAN, and RFID (Radio Frequency Identification) using the 2.4 GHz band is getting serious. In such urban areas, the wireless transmission medium may be in a bad state. There are roughly two ways to make effective transmission in this environment. The first is the IEEE 802.11 RTS / CTS method and the second is the frame fragmentation method. In this paper, it is difficult to transmit a frame over a certain size in a jamming environment due to the interference of the wireless environment. In this environment, we implement a frame division transmission scheme that guarantees effective transmission and reliability by dividing a frame into smaller units in order to perform reliability transmission and efficient transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.7
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• pp.380-388
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• 2014

Transmission methods for terrestrial UHDTV broadcasting have been actively studied in order to provide enhanced broadcasting service in many countries. Most of the countries are considering multi-carrier transmission methods based on OFDM and some of them have performed UHDTV experimental broadcasting by using the DVB-T2 standard with the adoption of an improved data compression technique. However, since single carrier transmission methods, which are known to be susceptible to multi-path fading, could remedy this defect by using the SC-FDE method where a frequency domain equalizer is utilized in the receiver, they may achieve a similar transmission performance with multi-carrier transmission methods. In consideration of these circumstances, we compare the transmission performances of two-type methods to provide a decision criterion on a suitable transmission method for UHDTV broadcasting.

• Journal of IKEEE
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• v.18 no.4
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• pp.442-446
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• 2014

A method for applying emergency ratings to improve the reliability of power supply in ACSR overhead transmission lines is described in this paper. Due to re-regulate power industry, most power companies worldwide as well KEPCO have been searching for only economical strategies without new investment. Power demand was rapidly increasing, however, generation amount did not follow sufficiently. Hence in order to increase the transmission capacity for the existing transmission lines in case of peak load, or contingency in transmission lines, an application method of emergency ratings such as short or long term rating is proposed. If applying long term emergency rating instead of static line rating for the period of a peak load, power transmission can be increased to 10 % or more. Furthermore, it was shown that emergency rating can be effectively used in the contingency of double-circuit transmission lines and/or overload cases.

• The Journal of Society for e-Business Studies
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• v.13 no.2
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• pp.149-163
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• 2008

In a ubiquitous sensor network (USN) with several nodes, real-time data processing is one of important factors. In order to process data appropriately, all the nodes should transmit sensor data in time and the transmission between nodes and their server should be managed very systematically. For the purpose of systematic management of transmission in a USN, this paper proposes a system for analyzing transmission time of sensor data. To implement the proposed system, an analyzing process of data transmission time, an analyzing method of clock drift, a collecting method of data send/receive times, and calculating formulas of data transmission duration are proposed. According to the proposed process and methods, this paper presents a system for monitoring and analyzing data transmission duration, and it also shows the results of a sample case.