• Journal of Korean Society of Transportation
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• v.23 no.6 s.84
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• pp.41-53
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• 2005

The effective utilization of an airport is considerably influenced by natural features and man-made structures inside and outside its boundary. These obstacles affect the airspace available for approaches and departures and the weather minima which dictates the necessary weather conditions for aircraft to be allowed to take-off or land. Certain areas of the airspace near airports must be regarded as the integral parts of the airport system. The availability of the required airspace is as important as are the runway and their associated strips to the safe and efficient use of the airport. For these reasons, ICAO and the member states have established the standards regarding the obstacle limitation surfaces and regulated the construction of the man-made structures in and beyond the surfaces. Existing objects that extend above a obstacle limitation surfaces should as for as practicable be removed except when, in the opinion of the appropriate authority, an objects is shielded an existing immovable objects, or after aeronautical study it is determined that the object would not adversely affect the safety or significantly affect the regularity of operations of airplanes. However, Korea's aviation law does not specified the outer horizontal surface in the obstacle limitation surfaces, while ICAO and most member states do. The absence of the outer horizontal surface regulation has created legal disputes between regulating agencies and private parties. The case study in this paper found that a skyscraper planned beyond Korea's obstacle limitation surfaces does affect the flight safety and the efficient use of an airport. Therefore, in areas beyond the obstacle limitation surfaces. those objects which extend to a height of 150m or more above ground elevation should be regarded as obstacle, unless a special aeronautical study indicates that they do not constitute a hazard to airplanes. We proposed low alternative regulatory schemes for resolving the issues raised in this paper, and we recommended to adopt ICAO's standards and recommended practices.

• 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 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.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.179-186
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• 2007

KTX control systems mutually control OBCS, ATC, MBU, TECA, MDT, ABU, HVAC, TRAE, PID and FDTR, KTX OBCS as master, and controls other sub-control devices as slave, using various serial lines. In order to analyze physical structure of various serial link lines and mutual data transmission structure, serial line analyzer is used in many ways. To use serial line analyzer, prior and professional technics about High Speed Train and experience of using device are necessary. In spite of difficult situation of space and environment where we work for maintenance of High Speed Train, in presenting basic structure about physical connection method aquired by sub-device serial line data collection and about communication data analysis, I hope that this research will be helpful for the person who work for similar area. Also, I hope that this research will help diagnostic work of High Speed Train, which is necessary for test run of independently developed High Speed Train.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.674-680
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• 2013

As the range of marine leisure activity gradually expands to ocean-going, a habitable cruise boat has been getting the limelight. Advanced countries in the marine leisure industry in Europe and North America have already secured their competitiveness in designing and building cruise boats by elegant design, ergonomic structure and fuel efficiency through the adoption of light-weight hull materials. In contrast, mostly small power boats are developed and built in Korea, and GFRP take up the most of hull materials. This study inquired into the design and characteristics of a 50ft-class CFRP that ocean-going is possible. The hull-form of the CFRP cruise boast were analyzed to propose a hull form for the designed ship (MMU-C.B), and based on that, the design model of the MMU-C.B was built. Finally, the MMU-C.B's characteristics of the resistance performance and hull-planing were found by comparative reviews with the results of model tests of GFRP pleasure yachts.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.459-467
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• 2019

The landing gear is a component that requires a high degree of safety to protect the lives of rotary-wing aircraft and boarding personnel, absorbing the impact on transfer/landing and supporting the fuselage during taxiing and mooring on the ground. In particular, the wheel landing gear supporting the aircraft fuselage absorbs most of the shock from the ground through the shock absorber and tires. This ensures the safety of the pilot on board the aircraft and satisfies the operational capability of the soldiers between missions. During the operation of a rotary-wing aircraft, a number of piston pins, which are a component of the right main wheel landing gear, were found to be broken. Therefore, this study examined the root cause of the piston pin crack phenomenon found in the main wheel landing gear. For this purpose, various causes were identified from fracture surface analysis of a flight test. In particular, the possibility of cracking was analyzed based on the influence on the fastening torque with the drag beam component applied to the piston pin at the time of development. This ensures the fatigue life and structural integrity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.971-979
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• 2023

Small ships (<499 GT) constitute 46% of the existing ships, therefore, it can be concluded that they produce relatively high CO₂ gas emissions. Operating in optimal trim conditions can reduce the resistance of the ship, which results in fewer greenhouse gases. An affordable way for trim optimization is to adjust the weight distribution to obtain an optimum longitudinal center of gravity (LCG). Therefore, in this study, the effect of LCG changes on the resistance of a small planing ship is studied using empirical and numerical analyses. The Savitsky method employing Maxsurf resistance and the STAR-CCM+ commercial computational fluid dynamics (CFD) software is used for the empirical and numerical analyses, respectively. Finally, the total resistance from the ship design process is compared to obtain the optimum LCG. To summarize, using numerical analysis, optimum LCG is achieved at the 46.2% length overall (LoA) at Froude Number 0.56, and 43.4% LoA at Froude Number 0.63, which provides a significant resistance reduction of 41.12 - 45.16% compared to the reference point at 29.2% LoA.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.672-680
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• 2023

Weight is a critical factor in the ship design process given that it has a substantial impact on the hydrodynamic performance of ships. Typically, ships are optimally designed for specific conditions with a fixed draft and displacement. However, in reality, weight and draft can vary within a certain range owing to operational activities, such as fuel consumption, ballast adjustments, and loading conditions . Therefore, we investigated how resistance changes under three different loading conditions, namely overload, design-load, and lightship, for small craft, using both model experiments and numerical simulations. Additionally, we examined the sensitivity of weight changes to resistance to enhance the performance of ships, ultimately reducing power requirements in support of the International Maritime Organization's (IMO) goal of reducing CO2 emissions by 50% by 2050. We found that weight changes have a more significant impact at low Froude Numbers. Operating under overload conditions, which correspond to a 5% increase in draft and an 11.1% increase in displacement, can lead to a relatively substantial increase in total resistance, up to 15.97% and 14.31% in towing tests and CFD simulations, respectively.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.710-715
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• 2023

Urbanization brings many challenges such as traffic, housing, and environment. To solve these problems, researchers are working on new transportation systems like urban air mobility (UAM). UAM aircraft should fly safely without burdening the existing air traffic system in the early stage of low-density operation. The airspace should also be managed and operated efficiently. Therefore it is important to make urban air traffic predictable by using corridors and collecting data on low-density operations in the early stage. For this purpose various simulations are needed before operation to create scenarios that estimate potential collisions between UAM aircraft and to evaluate the risks of aircraft spacing, loss of separation (LoS), and near mid air collision (NMAC). This paper focuses on identifying the requirements and considerations for setting separation standards for urban air traffic based on the results of studies.