• IEIE Transactions on Smart Processing and Computing
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• v.3 no.1
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• pp.35-39
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• 2014

This paper proposes a Modified Minimum Mean Square Error (M-MMSE) estimator for an Orthogonal Frequency Division Multiplexing (OFDM) System over fast fading Rayleigh channel. The proposed M-MMSE estimator considered the effects of the efficient placement of pilots based on the channel energy distribution. The pilot symbols were placed in a non-linear manner according to the density of the channel energy. Comparative analysis of the MMSE estimator for a comb-type pilot arrangement and M-MMSE estimator for the proposed pilot insertion scheme revealed significant performance improvement of the M-MMSE estimator over the MMSE estimator.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.225-230
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• 2002

Machine of textiles let off is equipment supplying constantly fabrics. Nowdays, as it is replaced band - brake type with hydraulic motor driven type, we looked into characteristic of hydraulic solenoid pilot direction valve(SPDV) for controlling acceleration performance of hydraulic motor. This study deals with controlling the initial speed of textiles let off machine. Finally, to control the initial speed of hydraulic motor, we controlled the adjustment screw of SPDV by a hand. Test which was carried out in the laboratory shows that initial speed of textiles let off could be improved by controlling adjustment screw of SPDV. Also, the results of experiment work were compared with dynamic characteristic of other on/off solenoid direction valve(SDV).

• Journal of the Korean Society for Aviation and Aeronautics
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• v.27 no.4
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• pp.73-82
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• 2019

In order to achieve successful flight training results, various studies on pilot aptitude have been conducted. In this study, we examined the aptitude for the pilots using the teacher aptitude test tool. As a result, the student pilots showed a high aptitude score suitable for conducting aviation training, and the A-type personality type was overwhelmingly large. The study satisfaction of student pilots was classified into educational contents, educational methods, educational environment and facilities, and flight instructors using the questionnaire related to the satisfaction of learning. As a result, the satisfaction of flight instructor among four factors was found to be a major factor in improving flight performance.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.4
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• pp.62-69
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• 2016

The purpose of this study is to develop questionnaire items for the Pilot Aptitude Personality Test(PAPT) which can predict the flight training achievement through personality and personal characteristics. To do this, we investigated the personality traits required to successfully conduct flight training for 30 flight instructors as a subject. The results were as follows: motivation, concentration, concentration, situational awareness, and concentration. Based on this, preliminary 300-item questionnaire was prepared by combining the existing studies related to pilot aptitude. Survey was conducted using preliminary questionnaire for 152 student pilots as a subject. As a result of the correlation analysis between the results of the questionnaire and the flight training, 16 questions were derived. Finally, factor analysis showed that the final 14 questionnaire items were confirmed. The internal concept of an item is categorized as personality, perception, and motivation. This study suggests that the pilot aptitude should be viewed from an extended point of view by analyzing individual characteristics and pilot aptitude in relation to flight training achievement.

• Korean Journal of Construction Engineering and Management
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• v.5 no.2 s.18
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• pp.72-80
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• 2004

The objective of the research is to develop the automated vertical controllable pilot-type equipment for PHC piles. The motivation for the research is that inherent problems related to vertical control during pile driving. The paper explains the current vertical control methods and problems, design and manufacturing of the pilot-type automated equipment and its testing and discussions of the results.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1450-1454
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• 1996

Even though digital control type high speed solenoid valve is a little inferior to analog control type servo valve and proportional control valve in performance, it is cheap and has secure performance against pollutant and simple control circuit. But high speed solenoid valve is hardly used for heavy machinery instead of servo valve or proportional control valve that is used in severe condition because the valve itself is small capacity and it shows wide dead zone during on-off control and chattering of hydraulic cylinder by chattering of pressure. It is desirable to use low-priced and strong pollutant resistant high speed solenoid valve for obtaining reliability of operation from severe working condition because it isn't necessary to acquire response characteristic of high frequency when we consider the characteristic of heavy machinery operation. In this study, PWM control algorithm for pilot pressure control of large capacity pilot operating valve will be used for precision position control of heavy machinery hydraulic cylinder. Not only cost reduction of main control valve but also high reliability of heavy machinery in severe condition can be obtained by using this pilot operating spool valve with high speed solenoid valve.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.358-360
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• 2008

Recently there are many pilot studies for advanced application of first Korea national high resolution satellite image, which is called as KOMPSAT-MSC (Korean Multi-purpose Satellite-Multi-Spectral Camera), in Korea. In this study the forest type classification methodology is developed and its distribution map was constructed by applying high resolution satellite image, KOMPSAT-MSC, based on Tasseled Cap Transformation, especially through comparing the result of detailed filed surveying such as forest type, tree species, tree diameter, tree age and tree crown density in pilot study area.

• Journal of the Korean Home Economics Association
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• v.26 no.1
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• pp.97-108
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• 1988

The purpose of this study is to classify the type of the Korean document chest, mungab through the literature and market survey and to investigate the preference on characteristics of the mungab. It also attempts to find out the aesthetic perception of the type of mungab by using semantic differential scales. A pilot study was conducted to select the types and pictures of the mungab. Three types and six pictures of mungab were selected. Six hundred homemakers of middle and upper class residing in seoul area were selected for the survey and 449 among them were used for data analysis. Data were analyzed using the SPSS program. The major findings are as follows: 1) The esult of pilot test, the presentative characteristics of mungab were classified into naive type, unique type, and elaborate type. 2) it was found that the modernized style of traditional mungab was wood grain and the next one was Najonchiligi. In the characteristics of decoration which was symbolic pattern, Shi-Jang-Saeng was predominant. In wanting style when they buy, the modernized style of traditional Korean chest was predominant, too. 3) Young and low income group preferred modern style using transparent paint and Sa-Goon-Ja, letters in the symbolic patterns of decoration. Old and high income group preferred traditional style using splendid and expensive materials and Ship Jang Saeng in the symbolic decoration. 4) compared with types of mungab in aesthetic perception, modern style of the traditional mungab was evaluated more positively than traditional style. The young and low income group perceived the naive type and unique type positively, but the old and high income group perceived the elaborate type the most positively.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.160-160
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• 2010

ELVs (End-of-Vehicles) in Korea incrasease continusely because of increase of used car. Automobile Shredder Residue (ASR) is final product of ELVs (End-of-Vehicles) after recycling. Automobile Shredder Residue are composed of light and heavy fluffs and soil/dust. In this study, 5 ton/day pilot plant of shaft type has been designed and constructed and 15 times of test run were performed. For the stable operation, operation conditions such as the amount of fed ASR and cokes, air flow and temperature in the gasification melting system have been changed and the composition of the produced gas such as $H_2$, CO and $CH_4$ and air pollution compound including dioxin discharged from the stack have been analyzed.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.37-43
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• 2003

The objective of this work is to investigate the effect of swirl, injection pressure and pilot injection on D.I. diesel combustion by using a transparent engine system. The test engine is equipped with common rail injection system to obtain high pressure and to control injection timing and duration. In this study, the combustion analysis and steady flow test were conducted to estimate the heat release rate from in-cylinder pressure. Soot distribution in diffusion flame according to swirl ratio, injection pressure and pilot injection was investigated by using LII technique. As the results, high injection pressure was found to shorten ignition delay as well as enhance peak pressure and heat release rate was greatly affected by injection timing and pilot injection. In addition, the results showed that the period of soot formation corresponded to the diffusion flame.