• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.300-304
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• 2012

It has a limitation to satisfy the phosphorus effluent criteria of 0.2 mg/L which will be reinforced from 2012 with the Biological Nutrient Removal (BNR) process. The chemical coagulation process has been operated in parallel with the biological treatment process for advanced treatment of phosphorous in the developed countries including Europe. However, the coagulation process has some disadvantages such as the desired goal may not be achieved without injecting the optimum dosage of the coagulant. This study developed the automatic control system to inject the optimum dosage of phosphorous coagulant into the coagulation process. The adopted coagulant was 10% Poly Aluminum Chloride (PAC) in this study. The automatic control system developed in this study was adopted for the treatment of the phosphorus from the effluent in SBR process. The automatic control system was composed of the data receiving part, the optimum coagulant dosage control part and the data transmit part. The result of the phosphorous advanced treatment of the SBR effluent using the automatic control system showed the removing efficiency over 95% consistently with the phosphorous concentration under 0.02 ~ 0.15 mg/L. The reproducibility analysis for checking the safety of automatic control system showed more than 95% correlation.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.43-51
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• 2013

This paper describes the development of the telemetry link system for the high data rate transmission in high speed rocket application. In consideration of bandwidth efficiency, frequency selective fading and doppler frequency offset, we used DQPSK instead of PCM/FM which has been the primary modulation format in aeronautical telemetry. Also we used the spatial diversity with multiple receiving antennas to mitigate multipath interference which is the dominant channel impairment and the Turbo Product Code for Forward Error Correction to improve bit error rate performance.

• Wind and Structures
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• v.20 no.6
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• pp.751-761
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• 2015

A multi-platform offshore wind farm is receiving the worldwide attention for the sake of maximizing the wind power capacity and the dynamic stability at sea. But, its wind power efficiency is inherently affected by the interference of wake disturbed by the rotating blades, so its layout should be appropriately designed to minimize such wake interference. In this context, the purpose of this paper is to introduce a layout optimization for multi-platform offshore wind farm consisted of 2.5MW spar-type floating wind turbines. The layout is characterized by the arrangement type of wind turbines, the spacing between wind turbines and the orientation of wind farm to the wind direction, but the current study is concerned with the spacing for a square-type wind farm oriented with the specific angle. The design variable and the objective function are defined by the platform length and the total material volume of the wind farm. The maximum torque loss and overlapping section area are taken as the constraints, and their meta-models expressed in terms of the design variable are approximated using the existing experimental data and the geometry interpretation of wake flow.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.845-853
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• 2009

This study recognize the problems about the High-speed IT building certification system and the technical standards of telecommunication facility, broadcasting public receiving facility including Home-network facility which are installed at apartments for the successful building of the Ubiquitous city that the government is driving and suggested a sweeping change of the housing law interrelated for making up a housing efficiency grade-display system and systematizing the maintenance by solutions. Also, presented the integrate-construction model designs separately of the residential IT line about the buildings applied to technical standards, the building acquired second grade below of High-speed IT building and the building when the above solutions get to he systematized.

• Korean Journal of Agricultural Science
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• v.43 no.2
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• pp.288-297
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• 2016

This study is to evaluate the 'Private antidesertification afforestation support project' in the Kubuqi Desert through a survey of local residents and interviews with relevant personnel. Based on this survey, gender, age, and occupational differences in perception of the project were analyzed. In addition, the project was evaluated based on the OECD/DAC criteria using survey results and in-depth interviews with the relevant personnel. The survey analysis results show that the participants answered most of the questions positively, claiming that they were receiving social, economic, and environmental benefits through the project. However, most of the participants answered negatively to questions regarding the understanding of the project and relevant information. Gender differences in perception of the project were not found, whereas, age and occupational differences in perception were found. Older age groups showed higher levels of perception. Participants in the agro-livestock industry and office workers showed higher levels of perception compared to middle/high school students, the unemployed and college students. Teenagers, in particular, showed the lowest level of perception of the project, and thus, promotional activities targeting teenagers should be conducted in the future. Results of this evaluation of the project based on the OECD/DAC's five criteria (relevance, effectiveness, efficiency, impact, and sustainability) showed that the project operated effectively for the most part.

• Journal of Magnetics
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• v.20 no.4
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• pp.394-399
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• 2015

Electromagnetic Induction Launchers (EIL) have been receiving great attention due to their advantages of non-contact between the coils and a projectile. This paper describes the modeling and design of 3-stage EIL to accelerate a copper projectile of 50 kg with 290 mm diameter. Our EIL consists of three independent driving coils and pulsed power modules to generate separate driving currents. To find efficient acceleration conditions, the appropriate shape of the driving coils and the position of the projectile have been calculated by using a finite element analysis (FEA) method. The results showed that the projectile can be accelerated more effectively as the gap between the coils is smaller; a final velocity of 45 m/s was obtained. The acceleration efficiency was estimated to be 23.4% when a total electrical energy of 216 kJ was discharged.

• Journal of electromagnetic engineering and science
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• v.7 no.4
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• pp.169-174
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• 2007

This paper presents a method of superimposing the rotation phases over the pilot and data symbols in order to reduce the peak-to-average power ratio(PAPR) in orthogonal frequency division multiplexing(OFDM). The phases of the rotation vector are added to those of the pilot symbols and those of the data symbols by interlaying them between any two pilot symbols. The receiver restores the data symbols by utilizing the channel estimation of the pilot symbols. Therefore, the bandwidth efficiency is improved by not using the subcarriers that are assigned for the reduction of the PAPR. Also, the enormous increase of the bit error rate which would be caused by incorrectly receiving the side information, i.e. the phases of the rotation vector, is prevented. The simulation results of the bit error rate performance for the BPSK are given using the COST-207 channel model.

• Journal of Korea Multimedia Society
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• v.3 no.6
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• pp.604-610
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• 2000

A stereo acoustic echo canceller has significant cross-correlation between each channel signal. As the result, the adaptive filter coefficient that estimates the acoustic echo path of a receiving room can misconverge to the path or converge slowly. In this paper, a new preprocessor using absolute difference in stereo signals is proposed to reduce cross-correlations and to improve the removal efficiency of the stereo acoustic echo. Compared to the previous preprocessor using a half wave rectifier, the newly proposed preprocessor showed better performance according to computer simulation. In addition, when the paths of transmitting room were changed the performance of the proposed preprocessor was not degraded.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.634-639
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• 2008

In mobile communication networks, the main power consumption is due to the actual transmissions power. Therefore, power efficiency network structures have gained considerable importance in mobile multi-hop systems and networks in recent years. In this paper, the performance of mobile multi-hop wireless system with M-QAM signal and forward error control (FEC) technique are analyzed The FEC technique uses extra processing power related to encoding and decoding, it is need complex functions to be built into the communication node. The probability of receiving a correct bit and codeword for relaying a data frame over h hop relay station to the final station is evaluated as a function of channel parameter and number of hops, and the distance between the different station.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.950-956
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• 2009

Nowdays the mobile traffic have been greatly increasing. This traffic increment has been caused the lack of frequency. To solve this problem, many study to improve the frequency efficiency in the field of mobile communication has been performed in a variety angle. However this kind of study was focused to 1:1 traffic. This paper propose the allocation scheme of the receiving channel in 1:N group traffic. This method apply to the TRS(Trunk Radio System) that use for the emergency disaster telecommunications. The result of the study show the performance improvement in the call loss ratio and load distribution in the group channel.