• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.292-299
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• 2017

The KUH-1's Wheel Brake Assembly which is Brake System is an essential component to perform flight mission for pilot. It has function of taxing, differential braking and parking to sustain landing capability. However, the skid and abrasion of tire were occurred in mass-produce operation. Also, if it is occurred on the ground, the flight can not be performed. In this case, the defect is a major cause of the decrease in the operation rate of aircraft. In this paper, the cause of the defect in flight was identified and the failure process was organized. Also, it 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.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 Aviation and Aeronautics
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• v.2
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• pp.139-182
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• 1994

조종사들은 비행시에 일상 생활 환경에서는 경험하지 못하는 여러가지 적대환경에 폭로된다. 이러한 환경에서는 인체의 평형기관은 실제와 일치하지 않는 정보를 제공해 주는 경우가 허다하다. 예를들면, 내이의 미로 전정기관이나 피하압력기관기 등은 항공기의 기동으로 발생하는 중력과 지구의 중력을 구별 하지 못하는 기능의 한계성때문에 계기비행하에서는 대개의 경우 공간정위상실, 즉 비행착각을 유발한다. 이 착각으로 인한 항공기 사고는 통계상에서 상당 부분이 치명사고로 나타나고 있는데, 이러한 사실은 비행착각현상이 비행안전에 극히 위험한 요소가 되고 있다는 것을 실증한다고 할 수 있다. 그러므로 조종사들은 비행시 공간정위 유지를 위한 철저한 대비가 있어야 한다. 공간정위 상실현상이 잘 발생하는 경우는 야간이나 기타 계기비행 환경에서 주위시각이 제약을 받을 때이다. 즉, 계기비행 환경에서의 편대비행시나 고기동시, 그리고 대조물이 모호한 야간의 활주로에서 이착륙할때 등을 들 수 있다. 비행시 공간정위 상실현상을 예방하기 위해서는 첫째로 이러한 유형의 사고분석자료를 토대로 하여 항공기의 설계단계에서부터 제작에 이르기까지 착각을 유발할 수 있는 구조적 요인을 제거해야 한다. 둘째로는 이러한 착각을 유발하지 않는 운항이나 기동방식을 택하여 비행임무를 수행토록 해야한다. 세째로 조종사들은 이러한 착각을 정상적인 인체의 반응에 의한 것이므로 자신에게도 당연히 일어난다는 사실을 용인해야 한다. 네째로 조종사들은 계기비행에 대한 구체적이고 실제적인 훈련을 통하여 계기비행 경험을 쌓아야 한다. 다음은 조종사들의 실제비행시 공간정위 상실현상에 봉착했을때의 처리요령이다. 첫째로 계기비행상황에서 자신의 감각과 계기가 일치하지 않을 때는 즉시 계기를 Cross Check하여 항공기의 자세나 기동형태를 정확하게 파악해야 한다. 둘째로 계기가 조종사의 의도대로 나타나도록 조작하고 이를 철저하게 의지하고 믿어야 한다. 세째로 자신의 감각과 계기가 일치할때까지 수평비행을 유지해야 한다. 그리고 마지막으로, 고성능 항공기가 계기비행중 저공에서 비행착각에 봉착하게 될때의 행동절차를 철저하게 숙지하고 있어야 한다.

• Journal of Energy Engineering
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• v.12 no.1
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• pp.11-16
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• 2003

A numerical study was performed on the transient fuel temperatures of a military aircraft stationed under non-operating static condition. Numerical calculation was peformed by an explicit method using modified Dufort-Frankel scheme. It was assumed that the non-operating aircraft is subjected to repeated daily cycles of air temperature with the solar radiation and wind speed corresponding to the 1 % hot day ambient condition. And, the aircraft was assumed to be in turbulent flow. The convective heat transfer coefficient for turbulent flow on the flat plate suggested by Eckert was employed to calculate heat transfer between the aircraft surface and the ambience. The energy conservation equation on fuel was used as governing equation for this analysis. As a result of this analysis, the wing tank temperature showed the highest temperature and the largest rate of temperature changes among fuel tanks. The results of this analysis could be used as initial foe] temperatures for analysis of the transient fuel temperatures in various flight missions. Also, this analysis method could be used to analysis and design of an aircraft thermal energy management system.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.3
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• pp.135-142
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• 2015

As the importance of software to society has grown, more and more schools worldwide teach coding basics in the classroom. Despite the rapid spread of coding instruction in grade schools, experience in the classroom is certainly limited because there is a gap between the curriculum and the existing computing environment such as the mobile and cloud computing. We propose an approach to fill this gap by using a mobile environment and the robot on the cloud-based platform for effective teaching. In this paper, we propose an architecture called Cloudboard that enables knowledge sharing and collaboration among knowledge providers in the cloud-based robot platforms. We also describe five representative architectural patterns that are referenced and analyzed to design the Cloudboard architecture. Our early experimental results show that the Cloudboard can be effective in the development of collective robotic systems.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.167-174
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• 2018

The heater is applied to the lunar lander for securing its survivability under severe lunar thermal environment during 14 days of night time. For this, the heater on/off set-points shall be determined to minimize the power consumption due to the limited power generation of lunar lander during night time. In addition, the temperature changes of the lander according to the heater set-point is also an important factor because it is related to thermo-mechanical reliability on solder joint of on-board electronics. In this study, we investigated thermo-mechanical reliability on solder joint according to the heater set-point by using commercial reliability and a life prediction tool of Sherlock based on the thermal analysis results of lunar lander that is a year of the mission lifetime.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.102-109
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• 2003

The number of engines for fighters has been decided by thrust required and available engines at the time since the beginning of the jet age. However, many factors such as combat effectiveness, survivability, performance, and cost were considered as engine technology has been progressed. From the vietnam war and desert storm, a twin engine fighter was shown slight superiority to a single engine one in an vulnerability，but single engine fighters were a little predominant in susceptibility This paper includes the trade-off study results on the number of engines for the supersonic light attack aircraft with single and twin engines. Twin engine configuration is 8%, 26%, and 13% higher than single engine one in MTOGW, Flyaway Cost, and LCC respectively. Little difference has been found in RM&S, Maneuver and field performance. According to the factors above, single engine fighter is profitable for low class and twin engine one for medium and higher class.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.7
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• pp.537-546
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• 2020

The reliability used as a performance indicator during the development of space launch vehicle should be validated by the launch success probability, and the launch data need to be fed back for reliability management. In this paper, the launch data of space launch vehicles around the world were investigated and statistically analyzed for the success probabilities according to the launch vehicle models and maturity. The Bayesian estimation of launch success probability was reviewed and analyzed by comparing the estimated success probabilities using several prior distributions and the statistical success probability. We presented the method of generating prior distribution function and considerations for Bayesian estimation.

• Journal of Satellite, Information and Communications
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• v.3 no.1
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• pp.29-34
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• 2008

After spacecraft is separated from the launch vehicle, first of all spacecraft deploy the solar array. Solar array deployment is one of the key factors deciding the success of the spacecraft mission. Therefore, It is necessary to predict the solar array deployment motion and check the safety through calculating the load on the tape hinges of solar array using the deployment analysis in the initial design phase. In this paper, solar array deployment analysis is performed by multi-body dynamics simulation program. From the analysis results, assessment on the safety also is carried out. In addition, hinge characteristic test is fulfilled to find out hinge characteristic, and is applied to the deployment analysis.

• Journal of Korea Multimedia Society
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• v.15 no.10
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• pp.1236-1246
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• 2012

Autonomous mobile robot has ability to move itself so it can access to danger area or narrow place, and send acquired data by sensors at the same time. In order to drive to directed place, it should progress to the destination without any collision to other robot. In this study, we built and realized the collision avoidance system for autonomous mobile robot. By using antenna, IR and ultrasonic Sensors for collision avoidance, we made it possible to sense the attached and long-distance obstacle, and can avoid. Also, we used wired and wireless network to send the data after the mission.