• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.1
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• pp.49-56
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• 2016

Flapper Valve of Korean Utility Helicopter(KUH-1) is an essential equipment in Environmental Control System(ECS) for pilot to perform flight mission. It provides pilots and crews with heating, ventilating and air conditioning. It has function of maintaining room temperature to sustain operational capability for pilot and crew. This paper summarizes pilot comments in flight test which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test at low temperature.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.927-933
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• 2023

In modern times, with advances in semiconductor technology such as electronic devices, the need to improve the quality of onboard equipment with advanced electronic parts in automobiles, drones, airplanes, projectiles, and various fields, and reduce the impact of various disturbances on onboard equipment is becoming more important. Vibration control through hardware must be determined to prevent damage and improve quality to equipment operating in various environments such as automobiles, drones, airplanes, and projectiles. This study focuses on the study of vibration damping systems to protect mounted equipment from various disturbances and improve stability. Dynamic characteristics analysis, including compressive stiffness, damping rate, and frequency response, and vibration characteristics in the frequency domain of rubber dampers were identified through FEM analysis to identify the characteristics of rubber dampers. Through these findings, we would like to present the criteria for selecting a suitable rubber damper under various disturbance conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.498-507
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• 2017

Electronic equipments comprised of high density components with various packaging types have been recently applied to a satellite. Therefore, to guarantee high reliability of electrical equipment, a design approach, which can reduce the development period and cost through an early diagnosis in potential risks of failure, should be established. In the previous research, the reliability assesment of the electronic equipments have based on Steinberg's fatigue failure theory. However, this theory was not enough for further investigation of life prediction and reliability of the electronic equipments comprised of various sizes and packaging types due to its theoretical limitations and analysis results sensitivity with regard to different modeling technic. In that case, if detailed finite element model is established, aforementioned problems can be readily solved. However, this approach might arise disadvantage of spending much time. In this paper, to establish strategy for high reliability design of electronic equipment, we performed mechanical reliability evaluation of CCB (Camera Controller Box) at qualification level based on the approach using Sherlock unlike design techniques applied to existing business.

• Structural Engineering and Mechanics
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• v.24 no.2
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• pp.213-225
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• 2006

The propagation of non-uniformly modulated, evolutionary random waves in viscoelastic, transversely isotropic, stratified materials is investigated. The theory is developed in the context of a multi-layered soil medium overlying bedrock, where the material properties of the bedrock are considered to be much stiffer than those of the soil and the power spectral density of the random excitation is assumed to be known at the bedrock. The governing differential equations are first derived in the frequency/wave-number domain so that the displacement response of the ground may be computed. The eigen-solution expansion method is then used to solve for the responses of the layers. This utilizes the precise integration method, in combination with the extended Wittrick-Williams algorithm, to obtain all the eigen-solutions of the ordinary differential equation. The recently developed pseudo-excitation method for structural random vibration is then used to determine the solution of the layered soil responses.

• Journal of Aerospace System Engineering
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• v.1 no.4
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• pp.13-21
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• 2007

As one of YHF digital data link technologies, VDL Mode 2 is designed to be an air-to-ground subnetwork of the Aeronautical Telecommunication Network (ATN) based on the Open System Interconnection (OSI) architecture. VDL Mode 2 can be used in ATS Applications especially for CPDLC and ADS. And it is also expected to replace ACARS (Aircraft Communications Addressing and Reporting System) which has broadly been used in AOC for over 20 years. This paper presents the design result of VDL Mode 2 system under AOA (ACARS Over AVLC) environment for the implementation of bit-oriented ATS applications. The system is composed of airborne and ground subsystem. Airborne subsystem consists of VDR, CMU and an aircraft test equipment with CPDLC/ADS client applications for operational test and ground system consists of Ground Station which includes ground VDR and ground communication controller, simple DSP (Datalink Service Processor) and a ground test equipment with CPDLC/ADS server applications.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.11
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• pp.735-741
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• 1999

The monitoring and assessment on the insulation condition of generator stator windings have been an important task of utility companies. The interest for the assessment of insulation condition has been increasing due to the need to keep old generating equipment reliable in order to extend the equipment life and to increase the generating capacity. Even though many developments and research activities for the condition assessment of generator insulation have been performed for decades, the assessment criterion in order to consistently predict the actual insulation condition is still in question. In this paper, the correlation between the parameters and the insulation condition is analyzed through the various non-destructive diagnostic tests in order to establish the assessment criterion on insulation deterioration of generator stator windings. By analyzing the correlation, PDI(Partial Discharge Index) as a novel parameter for the assessment criterion on insulation diagnosis of stator winding is proposed and verified.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.5
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• pp.497-506
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• 2008

The purpose of this study was is leading landmark efforts to prevent the major causes of commercial-aviation fatalities about controlled flight into terrain(CFIT) in approach-and-landing accidents. The paper of major analysis for controlled flight into terrain(CFIT) was Guam accident, Mokpo accident and Gimhae accident in commercial transport-aircraft accidents from 1993 through 2002.CFIT occurs when an airworthy aircraft under the control of the flight crew is flown unintentionally into terrain, obstacles or water, usually with no prior awareness by the crew. This type of accident can occur during most phases of flight, but CFIT is more common during the approach-and-landing phase.The paper believed that prevention for CFIT accident was education and training for flying crew and upgrade for equipment such as EGPWS, and need more research for professional organizations of airlines.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.11
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• pp.900-907
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• 2013

Payload fairing(PLF) protects satellites and related equipment from the external environment. They are separated before the satellite separation. Payload fairing made of composite sandwich materials due to their considerable bending stiffness and strength-to-weight ratio. Payload fairing have compression, shear and bending load during the flight. In this study, To check the strength of PLF and connected part, structural test of PLF accomplished using an actuator and a fixture. Purpose of structural test is to verify the strength of PLF in force of separation spring and combination structural load applied. Test result shows that the PLF have an acceptable margin of safety for the combination structural load and force of separation spring.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.490-497
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• 2017

The Main Landing Gear(MLG) of Rotary Wing Aircraft is an essential equipment in Landing System for pilot to perform a flight mission. It supports the fuselage at ground and absorbs the impact from the ground when landing, thereby, these functions sustain operational capability for pilot and crew. However, the A aircraft caused asymmetry and leakage hydraulic when it was stationed on the ground. Therefore, this paper summarizes pilot comments in operation which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.52-58
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• 2018

A Study on the dynamic characteristics of a rotor driven by a tipjet system in hovering condition was carried out. The sectional modeling was performed for the tipjet blade in which the flow path was inserted, and the dynamic characteristics analysis was conducted by modeling the components of the proposed rotor system. The analysis was conducted with respect to the rotational speed and the collective pitch. As a result of the analysis, it was checked that the proposed tipjet rotor did not have aeroelastic instability within the designed operating range. The tipjet test equipment was constructed in order to verify the analysis approach. It was confirmed that the proposed rotor was driven normally by tipjet. The non-rotating eigenmode measurement test and the rotation test were performed, and the validity was proved by comparing the test results and the analysis results.