• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.1-10
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• 2024

Gimpo International Airport is only available for alternate airport for code F aircraft and it is difficult to operate larger aircraft capable of transporting more passengers than B747-400. This study has conducted to review the compatibility based on risk assessment to introduce the B747-8 operation procedures, excluding the A380 for practical reasons. Risk factors for main gear deviation when driving on curved sections of the taxiway was identified. The risk was analyzed as "high" level. As a risk reduction measure, the proceduralization of specific taxiing method "judgemental oversteer" was reviewed, and the result of the risk re-evaluation was lowered to a "low" level. As a result, the B747-8 was analyzed to be compatible. Additionally, It is suggested that review of pavement strength, de/anti-icing facilities, and passenger boarding bridge is necessary for actual operations.

• Aerospace Industry
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• s.108
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• pp.56-59
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• 2010

점보제트라는 애칭으로 더욱 친숙한 보잉 B747은 한 번에 무려 400명 이상을 수송할 수 있는 최초의 대형여객기였다. 그러나 에어버스의 야심작 A380이 등장하면서 상황이 뒤바뀌고 말았다. 영원히 깨지지 않을 것만 같았던 B747의 각종 기록을 A380이 보란 듯이 갈아 치워버렸기 때문이다. 그리고 지금, 명예회복을 위해 보잉이 준비한 야심작 B747-8이 A380과의 한판 승부를 준비하고 있다. 이 흥미진진한 경쟁구도를 살펴봤다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.27 no.2
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• pp.70-78
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• 2019

CPDLC-DCL (Controller Pilot Data Link Communications-Departure Clearance) began in 2016 with 62 Towers in the United States. The application of this procedure is to utilize equipment different from existing ACARS PDCs or ACARS-DCLs. The purpose of this study is to provide information and understanding of CPDLC-DCL operation methods. Also, B747-8 aircraft considered operational cases related to departure procedures at U.S. airports. This procedure is currently not mandatory but will be mandatory in the future. The Flight Crew Procedures for CPDLC-DCL, as an appendix, will be a useful resource for B747-8 pilots.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.3
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• pp.40-47
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• 2018

Reducing aircraft speed is the important task in the Rejected Takeoff and/or landing process. It is known that the effect of the Speedbrake is most important factor during the rejected takeoff maneuver in particular near V1 on the critical field length runway. The B747 designer created Automatic Speedbrake Control System to relieve pilot workload, improves brake operation and ensures proper Speedbrake operation for rejected take off. However, those who make the Rejected Takeoff procedure ignored the Automatic function and made it does all manual operations. This lets procedures difficult, complicated, and a cause of confusion and pilot error. This study was conducted to commentary the mechanism and function of the Automatic Speedbrake Control System of B747-8 and to propose appropriate B747-8 Rejected Take off procedures for its function to reduce the workload of pilots and contribute to reduce the possibility of pilot error during Rejected Takeoff.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.8 no.1
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• pp.7-21
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• 2000

Magnitudes of Magnetic field, Electronic field and Microwave was measured during the each stage of flight in the airline operation. The results was much higher than the safety standard and proved to be serious to the cockpit crews on their duty. We also identified that the magnitude of electronic field was much decreased by all three kinds of microwave protection equipments. We recommend that the cockpit crew have to wear the protection clothes to reduce the hazardous effects on their duty and the aircraft manufacturers have to consider the microwave-reduced cockpit in the initial stage of aircraft design.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.4
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• pp.276-281
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• 2010

A 2.5 V feed-forward second-order deltasigma modulator for audio application is presented. A 9-level quantizer with a tree-structured dynamic element matching (DEM) was employed to improve the linearity by shaping the distortion resulted from the capacitor mismatch of the feedback digital-toanalog converter (DAC). A chopper stabilization technique (CHS) is used to reduce the flicker noise in the first integrator. The prototype delta-sigma analogto-digital converter (ADC) implemented in a 65 nm 1P8M CMOS process occupies 0.747 $mm^2$ and achieves 109.1 dB dynamic range (DR), 85.4 dB signal-to-noise ratio (SNR) in a 24 kHz audio signal bandwidth, while consuming 14.75 mW from a 2.5 V supply.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.62-68
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• 2016

The feeder cable assembly is an automotive part used for telecommunication. If it malfunctions, the control and safety of the automobile can be put at risk. ALT (Accelerated Life Testing) is a testing process for products in which they are subjected to conditions (stress, strain, temperatures, etc.) in excess of their normal service parameters in an attempt to uncover faults and potential modes of failure in a short amount of time. Failure is caused by defects in the design, process, quality, or application of the part, and these defects are the underlying causes of failure or which initiate a process leading to failure. Thermal shock occurs when a thermal gradient causes different parts of an object to expand by different amounts. Thermal shock testing is performed to determine the ability of parts and components to withstand sudden changes in temperature. In this research, the main causes of failure of the feeder cable assembly were snapping, shorting and electro-pressure resistance failure. Using the Coffin-Manson model for ALT, the normal conditions were from Tmax = $80^{\circ}C$ to Tmin = $-40^{\circ}C$, the accelerated testing conditions were from Tmax = $120^{\circ}C$ to Tmin = $-60^{\circ}C$, the AF (Acceleration Factor) was 2.25 and the testing time was reduced from 1,000 cycles to 444 cycles. Using the Bxlife test, the number of samples was 5, the required life was B0.04%.10years, in the acceleration condition, 747 cycles were obtained. After the thermal shock test under different conditions, the feeder cable assembly was examined by a network analyzer and compared with the Weibull distribution modulus parameter. The results obtained showed good results in acceleration life test mode. For the same reliability rate, the testing time was decreased by a quarter using ALT.

• Journal of the Korean Society of Food Culture
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• v.14 no.5
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• pp.517-527
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• 1999

The health, anthropometry, food habits, food intake frequency and nutrition intake of 747(219 men and 528 women) elderly people living in Inchon were investigated. Mean BMI, WHR, triceps skinfold thickness, BIA, blood pressure of the subjects were 23.4, 1.0, 15.6mm, 28.6%, 137.5/78.8mmHg in men and 24.9, 0.87, 22.6mm, 36.2%, 130.8/73.8mmHg in women respectively. Over the half of the subjects perceived themselves unhealthy and 86.2% of the elderly suffered from one or more illness. Ratios of the smoking and the drinking elderly were 40%, 43% in men and 12%, 11% in women. The major reason to stop smoking or drinking was the concern about their health. Food habit score of the subjects was relatively high (14.45/18.0) but food intake frequency score were relatively low (21.18/33.0) except the food groups of cereal & grain, white vegetable and sweets. The foods consumed by the elderly were very limited in quality and also in quantity. The daily intakes of calorie, protein, iron, vit. B1, niacin and vit. C were less than 2/3 of RDA and the amounts of calcium, vit. A and vit. B2 consumption were less than 1/2 of RDA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.741-747
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• 2002

In this paper, NRD guide band pass filter with newly designed inductive iris structure is proposed and analyzed with its test results. In case of common NRD guide filter with air gap coupled structure, it was not easy to fabricate and process or each NRD guide dielectric resonator blocks using PTFE. However, in this our research, each dielectric resonator fabricated in a single NRD guide is coupled with inductive iris located on metal plates. The structure is suitable for mass production of a precise and reliable millimeter-wave filter applications. As a result of measurements, designed NRD guide inductive iris filter has superior performance. The pass band is 38.66~39.06 MHz with 400 MHz bandwidth, insertion loss is about 1.4 dB and return loss is below -18 dB.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.164-171
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• 2020

Adsorption characteristics of reactive red 120 (RR 120) dye by a coal-based granular activated carbon (CGAC) from an aqueous solution were investigated using the amount of activated carbon, pH, initial concentration, contact time and temperature as adsorption variables. Isotherm equilibrium relationship showed that Langmuir's equation fits better than that of Freundlich's equation. The adsorption mechanism was considered to be superior to the adsorption of monolayer with uniform energy distribution. From the evaluated Langmuir separation coefficients (R_L = 0.181~0.644), it was found that this adsorption process belongs to an effective treatment area (R_L = 0~1). The adsorption energy determined by Temkin's equation and Dubinin-Radushkevich's equation was E = 15.31~7.12 J/mol and B = 0.223~0.365 kJ/mol, respectively. The adsorption process showed the physical adsorption (E < 20 J/mol and B < 8 kJ/mol). The adsorption kinetics followed the pseudo first order model. The adsorption reaction of RR 120 dye on CGAC was found to increase spontaneously with increasing the temperature because the free energy change decreased with increasing the temperature. The enthalpy change (12.747 kJ/mol) indicated an endothermic reaction. The isosteric heat of adsorption (△H_x = 9.78~24.21 kJ/mol) for the adsorption reaction of RR 120 by CGAC was revealed to be the physical adsorption (△H_x < 80 kJ/mol).