• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.377-382
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• 2006

Precision approach and landing of aircraft in a remote landing zone autonomously present several challenges. Firstly, the exact location, orientation and elevation of the landing zone are not always known; secondly, the accuracy of the navigation solution is not always sufficient for this type of precision maneuver if there is no DGPS availability within close proximity. This paper explores an alternative approach for estimating the navigation parameters of the aircraft to the landing area using only time-differenced GPS carrier phase measurement and range measurements from a vision system. Distinct ground landmarks are marked before the landing zone. The positions of these landmarks are extracted from the vision system then the ranges relative to these locations are used as measurements for the extended Kalman filter (EKF) in addition to the precise time-differenced GPS carrier phase measurements. The performance of this navigation algorithm is demonstrated using simulation.

• KSTLE International Journal
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• 제3권2호
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• pp.114-118
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• 2002

In this work, head-disk interactions are studied when flying height becomes lower than laser bump height on the landing zone of a disk. With the reduction of the spinning speed in a spin stand, the flying height is decreased under the height of laser bumps. Conventional and padded pico sliders sweep between landing Bone and data zone and, then, the dynamic behavior of the pico sliders and head-disk impacts are investigated using AE and stiction/friction signals. After 200n cycle-sweep tests, bearing analysis and AFM analysis indicate that there are some signs of wear and plastic deformation in the landing zone of a disk, although AE and stiction/friction signals are not significantly changed during the sweep tests. The experimental results of this paper suggest that in CSS tests at component level, more rigorous examination methods of wear and plastic deformation might be necessary as flying height becomes getting lower.

• Ocean Systems Engineering
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• 제6권4호
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• pp.377-400
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• 2016

Dropped objects are among the top ten causes of fatalities and serious injuries in the oil and gas industry (DORIS, 2016). Objects may accidentally fall down from platforms or vessels during lifting or any other offshore operation. Proper planning of lifting operations requires the knowledge of the risk-free zone on the sea bed to protect underwater structures and equipment. To this end a three-dimensional (3D) theory of dynamic motion of dropped cylindrical object is expanded to also consider ocean currents. The expanded theory is integrated into the authors' Dropped Objects Simulator (DROBS). DROBS is utilized to simulate the trajectories of dropped cylinders falling through uniform currents originating from different directions (incoming angle at $0^{\circ}$, $90^{\circ}$, $180^{\circ}$, and $270^{\circ}$). It is found that trajectories and landing points of dropped cylinders are greatly influenced by the direction of current. The initial conditions after the cylinders have fallen into the water are treated as random variables. It is assumed that the corresponding parameters orientation angle, translational velocity, and rotational velocity follow normal distributions. The paper presents results of DROBS simulations for the case of a dropped cylinder with initial drop angle at $60^{\circ}$ through air-water columns without current. Then the Monte Carlo simulations are used for predicting the landing point distributions of dropped cylinders with varying drop angles under current. The resulting landing point distribution plots may be used to identify risk free zones for offshore lifting operations.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.338-340
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• 2014

본 연구는 산악에서 발생되는 비상응급 상황에 대한 응급 구조 헬리콥터의 착륙 지점 및 착륙 불가시 강하 지점을 선정하는 것으로 지리정보시스템(GIS)을 이용하여 비상응급 구조 체제의 의사결정을 지원하는데 목적이 있다. 연구지역은 경기도 포천시 일대로 한정하였다. 산악 내 헬리콥터의 착륙 지점 및 강하지점 2가지 결과 값으로 분류하였으며 수치지형도, 임상도, 산림입지토양도를 기초 자료로 활용하였다. 착륙지점은 경사, 지형특성, 식생특성 및 헬리콥터 제원에 따른 헬리콥터 착륙지점 면적값을 요인으로 하였고, 강하지점은 경사, 식생특성을 요인으로 분류하여 GIS의 중첩기능 기법을 활용하여 분석하였다. 다만, 본 연구는 풍향 및 풍속 요인 등의 인자값을 배재하고 수행되었다. 향후, 기상청 DB와 연계함으로써, 좀 더 분석의 효율을 높일 필요가 있다.

• 한국항공우주학회지
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• 제36권1호
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• pp.39-47
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• 2008

GPS에 의사위성(PL: Pseudolite)을 추가하여 고도 정확도를 향상시키면 무인 항공기의 착륙 성능이 향상된다. 그러나 GPS 위성이 계속 움직이고, 매번 착륙 위치가 바뀌는 환경에서 원하는 정확도를 얻을 수 있도록 의사위성을 설치하고 운영하는 것은 매우 어려운 일이다. GPS와 의사위성으로 얻을 수 있는 서비스의 범위와 측위 정확도는 시뮬레이터로 예측 가능하고 정확하게 예측된 정보는 무인항공기의 운영을 위하여 매우 중요하다. 본 논문에서는 효과적인 의사위성의 활용을 위하여 GPS/PL 시뮬레이터를 개발하고 그 성능을 평가하였다. 시뮬레이터의 서비스 범위 예측은 의사위성의 설치 위치 및 개수, 송신 전력과 무인 항공기의 고도를 고려하여 GIS 데이터와 광선 방출 기법을 이용하여 계산하였다. 측위 정확도는 GPS와 의사위성을 동시에 사용하여 구한 DOP와 NSP를 이용하여 분석하였다. 실제 수신기의 출력과 비교하여 구현된 시뮬레이터를 검증하였으며, 시뮬레이션 결과 2개 이상의 의사위성의 추가로 무인항공기의 자동 착륙에서 요구되는 정확도를 만족시킬 수 있음을 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.842-845
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• 2000

It is essential to reduce stiction between the slider and the disk for super-smooth media such as glass disk for high density recording. We developed a stiction-reduced slider by fabricating mechanical bumps on the air bearing surface of the slider by indentation technique. This paper presents a possibility and concept of Stiction-Free-Slider which can operate on the data zone of a magnetic disk. The slider hat many bumps and their heights are in the tens of nm range. The SFS shows good performance on the data zone. Moreover, little wear of the bumps was observed when the preload was small.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제22권2호
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• pp.35-44
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• 2016

Purpose: Recently, Universal design has been applied to a variety of concepts of social integration in the national legislation and institutions, however, the applying to urban railway station is not satisfied. Most of cases, the handicapped can not work continuously, universal design must be provided. Methods: This study derives the detailed criteria through comparing and analyzing an national and international universal design-related system in transit zone. And the status is investigated in transit zone of domestic urban railway station. Improved national standard requirements are derived considering the type of the handicapped and universal design principles. Result: The domestic status shows that the most lacking entry criteria is not specified in national standards or the design is a lowest-level required by criteria through comparing detailed criteria drawn into domestic analysis. Therefore, in order to provide a pedestrian environment to meet the universal design principles and requirements for the handicapped, there is a need to re-establish with a specific national standards. Implications: This study will draw on universal design standards for seamless transfer in transit zone of urban railway station. The next studies are needed to target the overall paths ranging from outside to landing in urban railway station.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1407-1412
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• 2007

This study examined EM compatibility between noise from electric railway and signal of ILS in the case that an AC double track system is located about 1km far from end zone of runway at the airport. ILS is the most major equipment to help give airplane route during the landing.

• 한국항공운항학회지
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• 제17권2호
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• pp.18-22
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• 2009

In this study, we surveyed the operating status of the Light Sport Aircraft(LSA) in Korea, and reviewed the minimum requirements of the airpark for LSA in other countries. Based on the information, we presented the airpark standards to ensure the safe take-off, landing, and operation of LSA in Korea.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.243-247
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• 2001

As a means to reduce stiction in the landing zone padded sliders can be used. In this work the performance of padded slider was investigated using a commercial spin stand. The friction and acoustic emission signals were measured during the experiment. It is shown that padded slider show superior friction and AE characteristics. However, the wear properties of the pads should be further Improved.