• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.105-111
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• 2006

The aircraft engine is to generate thrust for the maneuver of aircraft and to provide the power to the related hydraulic system and electrical system. Since the power provided to the systems is extracted from the high pressure compressor of aircraft engine, the extracted power is called horsepower extraction (HPX). If the HPX provided from the engine is smaller than the HPX required from the related systems, there could be abnormal engine behavior, like engine rollback or stall. Analysis on comparing the required HPX and the engine HPX capability had been performed during the T/A-50 FSD (Full Scale Development) period. The analysis results make the engine schedule changed, and T/A-50 flight test has been performed with the changed engine schedule. The analysis results and changing the engine control schedule were verified to be valid with the flight test results.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.537-558
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• 2005

This paper addresses the results of HAUSAT-2 radiation environment and effect analyses, including TID and SEE analyses. Trapped proton and electron, solar proton, galactic cosmic ray models were considered for HAUSAT-2 TID radiation environment analysis. TID was analyzed through total dose-depth curve and the radiation tolerance of TID for HAUSAT-2 components was verified by using DMBP method and sectoring analysis. HAUSAT-2 LET spectrum for heavy ion and proton were also analyzed for SEE investigation. SEE(SEU, SEL) analyses were accomplished for MPC860T2B microprocessor and K6X8008T2B memory. It was estimated that several SEUs may occur without SEL during the HAUSAT-2 mission life(2 years). Software Hamming Code EDAC has been implemented to detect and correct the SEU. In this study, all radiation analyses were conducted by using SPENVIS software.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.2
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• pp.108-115
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• 2015

Electro-mechanical actuator installed on aircraft consists of a decelerator which magnifies the torque in order to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. Electro-mechanical actuator controls aircraft altitude, position, landing, takeoff, etc. It is an important part of a aircraft. Aircraft maneuvering causes vibrations to electro-mechanical actuator. Vibrations may result in structural fatigue. For that reason, it is necessary to analyze the system structural safety. In order to analyze the system structural safety. It is needed reasonable finite element model and structural response stress closed to real value. In this paper, analytic model is derived by using the simplified finite element model, and damping ratio which is closely related to response stress is derived by using modal test. So, we developed analytic model in less than 10 % error rate, compared with modal test. Vibration response stress close to real value was estimated from analytic model modified with modal experimental damping ratio. Estimation method for damping ratio with empirical formula was suggested partly. Finally, It was proved that electro-mechanical actuator had reasonable structure margin of safety at environmental random $3{\sigma}$ stress during life cycle.

• Journal of the Mineralogical Society of Korea
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• v.5 no.1
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• pp.6-13
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• 1992

Thermodynamic data of mineral reactions were used to construct a phase diagram for the formation of illite from andalusite at one bar and 325${\circ}C$ in the hydrothermal alteration. Based on chemical compositions, the free energy of formation of illite coexisting with andalusite was calculated by assuming the ideal mixing ina bunary system consisting of muscovite and pyrophyllite components. For illite with structural formula $K_{0.86}Al_{2.93}Si_{3.03}O_{10}(OH)_2$, its free energy of formation is -1147.727 kcal/mole at the condition under consideration. The stability area of illite is more narrow than that of end-member muscovite and prefers lower activity of silica. Illite was formed by hydration of andalusite while pyrophyllite decomposed. Illitization took place preferentially at margin and/or along fractures of andalusite.

• Journal of Fashion Business
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• v.16 no.1
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• pp.150-159
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• 2012

This study intend to analyze differences between 3D body scanning sizes and direct measurement sizes of same subjects. The subjects of study are female students of university in China. 3D data analyze as a 3D Body Measurement Soft System. The conclusion found is as below: In case of circumferences, error between direct-measurement size and 3D body scanning size is from 4.9mm to 62.2mm. The neck circumference size of directmeasurement is bigger than 3D body scanning size. The height error range is from 0.6mm to 51mm. Height of underbust, waist and hip are that direct-measurement sizes are higher than 3D body scanning sizes. Gap of width is from 3.8mm to 21.9mm. The gap range is too narrow relatively to others. Only direct-measurement size of neck width is wider than 3D body scanning size. Error range of length is from 0.3mm to 41.8mm. 3D body scanning sizes of lateral neck to waistline, upperarm length, arm length, neck shoulder point to breast point, shoulder center point to breast point, lateral shoulder to breast point are longer than direct-measurement sizes. They have a negative margin of error. I intend to set up same measurement point between direct-measurement and 3D body scanning but they have some errors because direct-measurement point is applied by a person. 3D body scanning measurement point is settled by automatic system. A measurement point of direct-measurement and 3D body scanning isn't unite. So we need to make a standard of setting up measurement points.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.9
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• pp.103-113
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• 2004

The satellite is exposed to the severe vibration environments such as random vibration environments such as random vibration, acceleration, shock, and acoustics during launch ascent and transportation. It is also faced with various space environments such as thermal vacuum, radiation and microgravity during the mission life. The satellite should be designed, manufactured, assembled and tested to be able to endure in these harsh environments. This paper addresses the results of the structural and thermal design and analyses for the HAUSAT-1 picosatellite which is scheduled to launch in the first quarter of 2005 by Russian launch vehicle "Dnepr". The qualification vibration and thermal vacuum tests have been conducted and passed at the satellite level to ensure that the HAUSAT-1 mechanical system was designed to be stable with enough margin.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.46-52
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• 2018

A simple Crocco's $n-{\tau}$ time delay model and linear analysis of fluid flow coupled with acoustics are combined to investigate the high frequency combustion instability in the combustion chamber of LOX/hydrocarbon engines. The partial differential equation of the velocity potential is separated into ordinary differential equations, and eigenvalues that correspond to tangential resonance modes in the cylindrical chamber are determined. A general solution is obtained by solving the differential equation in the axial direction, and boundary conditions at the injector face and nozzle entrance are applied in order to calculate the chamber admittance. Frequency analysis of the transfer function is used to evaluate the stability of system. Stability margin is determined from the system gain and phase angle for the desired frequency range of 1T mode. The chamber model with variable baffle length and configurations are also considered in order to enhance the 1T mode stability of the combustion chamber.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.183-186
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• 2006

It is studied the implementation possibility of some encryption algorithms which meet the performance requirements in the smart card used in the TETRA system End-to-End Encryption. It is measured the operation time of the algorithm in the smart card which has 32 bit smart card controller made by Samsung Electronics. The algorithms used in the performance comparison are AES, ARIA, 3DES, SEED, IDEA which are the domestic or international standards. The input and output time of the smart card are measured using the smart card protocol analyzer. The pure algorithm operation time is calculated by the repeated algorithm operations. This measurement results can be used as the criteria for the selection of algorithm which will be used in the TETRA End-to-End encryption system. The algorithm which has better performance can be used for the implementation of additional functions in the smart lard, because of the enough time margin.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.31-41
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• 2010

The objective of this paper is to evaluate production efficiency of the commercial road freight transportation industry using quarterly actual data by individual truck drivers from January 2005 to September 2009. In addition, this study analyzes various impact factors that influence production efficiency, including regulatory factors (e.g., entrust management system and multi-level transactions). For this purpose, this study uses data envelopment analysis and a truncated Tobit model. As a result, production efficiency of the general freight sector is higher than those of the other two sectors. Also, production efficiency in the steel goods sector ranks the highest; meanwhile, production efficiency in the oil goods sector ranks the lowest. In particular, production efficiency indicators of the commercial road freight transportation industry fluctuate with time by a small margin, and have an upward tendency on the whole. Finally, some policy implications are given to promote production efficiency of the commercial road freight transportation industry.

• Journal of the Korean Society of Tobacco Science
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• v.29 no.1
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• pp.41-51
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• 2007

This study was implemented to examine the effect of tobacco on operation of a retail store and propose a relevant direction to development of a retail store. In terms of an examination method, the questionnaire was conducted in respect of supermarkets and convenience stores(CVS) around the nation. As a result of analysis based on such questionnaire, although there was a little difference in between a supermarket and a convenience store, a similar result could be found in general. In other words, retailers selling tobacco regarded the tobacco as a medium to solicit customers. Since the significance of tobacco in terms of total sales volume was so high, without the tobacco, they might have suspend the business. Consequently, the effect of tobacco was enormous. In addition, under the premise that many regular customers should be acquired to develop such retail stores, it was found that it would be necessary to increase $15{\sim}20%$ in terms of a margin in tobacco, preserve the profit ratio by the government, make efforts to enhance a quality and design by a tobacco company, actively recommend a particular brand, and actively display a tobacco publicity booklet, etc. Moreover, the proper number of tobacco stores in comparison with habitual smokers was one per 200 persons. In respect of the most unreasonable tobacco policy, a minor-related system and a policy of increasing a tobacco price were named. Thus, under the premise that a medium such as tobacco is highly important with respect to an operation of retail store, it is necessary to pay a more careful attention to an improvement of a reasonable and equitable system to further develop a retail store.