• Title/Summary/Keyword: wheel loading

Search Result 178, Processing Time 0.026 seconds

통신해양기상위성의 휠오프로딩 지상국 소프트웨어 검증시험 (Ground Software Validation Test for Wheel Off-loading of COMS)

  • 박영웅;양군호
    • 항공우주기술
    • /
    • 제9권2호
    • /
    • pp.51-56
    • /
    • 2010
  • 통신해양기상위성의 정상임무 수행시 자세제어계에 대한 중요한 지상국 소프트웨어에는 궤도위치 유지와 휠오프로딩이 있는데, 본 논문에서는 외팔보 태양전지판 형상으로 인해 E3000 heritage로부터 설계 변경을 수행하여 해석을 수행한 휠오프로딩 임무에 대한 지상국 소프트웨어 검증시험을 정리하여 기술하였다. 휠오프로딩 지상국 소프트웨어는 크게 2가지로 구분되는데, 하나는 휠오프로딩을 위한 추력기 조합 변경 시기에서의 변수 변경이고 다른 하나는 위성으로 전달해야 하는 모멘텀기준값 변경이다.

단차 상태 차량 윤중 감소율 시험 절차 및 결과 (Wheel Off-loading test procedure and result)

  • 김진태;이원상
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2002년도 추계학술대회 논문집(II)
    • /
    • pp.857-862
    • /
    • 2002
  • 철도차량의 주행장치는 비틀림 선로를 주행할 경우 윤중감소가 발생하게 되며 이 값은 모든 하중 조건 및 공기스프링의 충기/배기 상태에서 UIC/ORE 보고서에서 규정한 기준치 60% 이내를 준수하여야만 한다. 이 논문은 인도 DMRC 전동차를 대상으로 시험을 실시하여 DMRC 선로 중 최악의 조건에서 UIC / ORE 에서 규정하고 있는 차량의 윤중감소율( Wheel Off-loading)의 기준을 만족하는 지에 대한 평가한 것을 기술하였다.

  • PDF

Study on Triaxiality Velocity of COMS induced by Wheel Off-loading

  • Park, Young-Woong;Kim, Dae-Kwan;Lee, Hoon-Hee
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
    • /
    • 한국우주과학회 2008년도 한국우주과학회보 제17권2호
    • /
    • pp.36.3-36.3
    • /
    • 2008
  • KARI (Korea Aerospace Research Institute) is going to launch a Communication, Ocean and Meteorological Satellite (COMS) at summer of 2009. It will be first thing to be developed for a geostationary satellite through domestic technology. Of course, KARI has performed this development program with EADS Astrium in France since 2005. COMS has the non-symmetric configuration that the solar array is only attached on the south panel. Due to the configuration, momentum of satellite will be rapidly accumulated induced by solar pressure and then 3 wheels of large momentum are located on roll-yaw plane for attitude control. Therefore, to prevent the saturation of wheel momentum, wheel off-loading will be performed two times per day during 10 minutes for each one. At the moment, translation movement on 3-axes direction appears because of using thrusters. In this paper, strategy of the wheel off-loading and triaxiality which is the translation effect on 3-axes are introduced. Consequently, the result of optimized triaxiality considering the wheel off-loading strategy is summarized.

  • PDF

지하철의 브레이크 디스크와 차륜방식브레이크의 내구성 연구 (Durability Study of Subway Brake Disc and Wheel-type Brake)

  • 한문식;조재웅
    • 한국기계가공학회지
    • /
    • 제18권7호
    • /
    • pp.22-28
    • /
    • 2019
  • In this study, as part of the subway braking system, the structural analysis was performed with the fatigue analysis by comparing subway brake disc and wheel-type brake. When structural analysis was performed, it was possible to verify that the wheel-type brake were higher than the brake discs in case of total deformation. As the same loading conditions were given to the subway brake disc and wheel-type brake, wheel-type brakes was shown to have more deformation than brake disk but lower damage than the subway brake disc. Comparing with each fatigue loading condition, the maximum fatigue life for 'Sample history' is found to be about 60 times longer than for 'SAE bracket history'.

A STUDY ON THE EAST/WEST STATION KEEPING PLANNING CONSIDERING WHEEL OFF-LOADING

  • Lee, Sang-Cherl;Park, Bong-Kyu;Kim, Bang-Yeop;Ju, Gwang-Hyeok;Yang, Koon-Ho
    • 대한원격탐사학회:학술대회논문집
    • /
    • 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
    • /
    • pp.263-266
    • /
    • 2006
  • Now, on the developing COMS(Communication, Ocean and Meteorological Satellite) has solar panel on the South panel only. Therefore, the wheel off-loading has to be performed periodically to reduce a induced momentum energy by a asymmetric solar panel. One of two East/West station keeping maneuver to correct simultaneously longitude and eccentricity, orbit corrections may be performed during one of the two wheel off-loading manoeuvres per day to get enough observation time for meteorological and ocean sensor. In this paper, we applied a linearized orbit maneuver equation to acquire maneuver time and delta-V. Nonlinear simulation for the station keeping is performed and compared with general station keeping strategy for fuel reduction.

  • PDF

CBN 연삭숫돌의 초음파 인프로세스 드레싱 기법 (A Study on the Ultrasonic In-Process Dressing Method of CBN Grinding Wheel)

  • 이석우;정해도;최헌종
    • 한국정밀공학회지
    • /
    • 제17권2호
    • /
    • pp.43-50
    • /
    • 2000
  • A CBN wheel was used for the highly efficient and precision grinding of the mold material(STD11). The grinding form accuracy by a CBN wheel is very excellent due to its low wheel wear, but grinding fragments resemble fine powders rather chips. A fine powders by this fragmentation can easily get attached to the wheel surface and therefore causing a loading. In order to prevent this fragmentation phenomena, the alumina stick is use to processing. Because the dressing with alumina stick should be interrupted for a processing, the automation of the processing and high productivity was very difficult. The investigation on the effect of Ultrasonic In-Process Dressing(ULID) on the grinding characteristics focuses in this Paper. This ULID method is that ultrasonic vibration in my Position of wheel is used to remove impurities on the wheel surface. Finally, the rate of surface roughness change in grinding by the ULID method was less than grinding without ultrasonic vibration. Loading phenomena by the ULID method were more prevented than grinding without ultrasonic vibration.

  • PDF

휠로더 굴착 자동화를 위한 버킷 부하특성 연구 (A Study on the Bucket Loading Characteristics for Wheel-loader Loading Automation)

  • 서동관;서현재;강인필;권영민;이상훈;황성호
    • 대한기계학회논문집A
    • /
    • 제33권11호
    • /
    • pp.1332-1340
    • /
    • 2009
  • The front end wheel loader is widely used for the loading of materials in mining and construction fields. It has repetitive digging, loading and dumping procedures. The bucket is subjected to large resistance force from the soil during scooping. We considered the soil reaction force characteristics from scooping procedure, the protection by overload and automatic scooping mode algorithm. The main topic of this paper is the analysis of the soil reaction force characteristics. The analysis of soil mechanics is carried out and the developed soil model is verified by experimental results from the simplified experimental equipment. A simplified model of the soil shape and bucket trajectory is used to determine the scooping direction based on an estimation of the resistance force applied on the bucket during the scooping motion. In the future, this model will be used for the generation of an appropriate path for the wheel loader automation.

PRELIMINARY COMS AOCS DESIGN FOR OPTIMAL OPTICAL PAYLOADS OPERATIONS

  • Park, Young-Woong;Park, Keun-Joo;Lee, Hun-Hei;Ju, Gwang-Hyuk;Park, Bong-Kyu
    • 대한원격탐사학회:학술대회논문집
    • /
    • 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
    • /
    • pp.290-293
    • /
    • 2006
  • COMS (Communication, Ocean and Meteorological Satellite) shall be operated with two remote sensing payloads, MI (Meteorological Imager) and GOCI (Geostationary Ocean Color Imager). Since both payloads have rotating mechanisms, the dynamic coupling between two payloads is very important considering the pointing stability during GOCI operation. In addition, COMS adopts a single solar wing to improve the image quality, which leads to the unbalanced solar pressure torque in COMS. As a result, the off-loading of the wheel momentum needs to be performed regularly (2 times per day). Since the frequent off-loading could affect MI/GOCI imaging performance, another suboptimal off-loading time needs to be considered to meet the AOCS design requirements of COMS while having margin enough in the number of thruster actuations. In this paper, preliminary analysis results on the pointing stability and the wheel off-loading time selection with respect to MI/GOCI operations are presented.

  • PDF

동축 가공기용 드레싱 장치 개발 (Development of Dressing System for Co-axial Grinding Machine of Ferrule)

  • 이석우;최헌종;안건준;최동열
    • 한국정밀공학회:학술대회논문집
    • /
    • 한국정밀공학회 2002년도 추계학술대회 논문집
    • /
    • pp.70-73
    • /
    • 2002
  • Using zirconium ceramics makes the ferrule, which is the part of optical communications. The quality of optical communications is directly affected by the concentricity of the optic ferrule. The products of optic ferrule should be meet the following general conditions which are the outer diameter of 2.5mm and the inner diameter of 0.125mm, and high quality conditions which are the concentricity of 0.1~$0.3\mu\textrm{m}$, the form accuracy of $0.2\mu\textrm{m}$, the roundness and the cylindricity of $0.1\mu\textrm{m}$ and the surface roughness of 10nm. Generally, the diamond wheel is used for the high efficiency and precision grinding of the materials. It is good for keeping the shape as it has little wear. Because of the loading phenomena, however, it is difficult to keep the fresh surface of the wheel. In grinding process, grinding fragments resemble fine powders rather than chips. It can easily get attached to the wheel surface and thus cause a loading. The loading takes place, in which the impurities stick to the wheel surface, and the grinding characteristics of wheel is deteriorated. To prevent all of these, a suitable dressing method should be used for the wheel. In this research, the dressing system fur co-axial grinding machine was designed and produced for the machining of ferrule, which is a high performance part. The performance of the developed dressing system was evaluated by measuring the form accuracy of ferrule, which is machined by the dressed wheel in developed dressing system.

  • PDF

단속 연삭지석에 의한 스테인레스강의 연삭특성에 관한 연구 (A Study on the Grinding Characteristics of Stainless Steel Using Intermittent Grinding Wheel)

  • 권오병;김정두
    • 대한기계학회논문집A
    • /
    • 제20권9호
    • /
    • pp.2866-2874
    • /
    • 1996
  • In the grinding of difficult-to-materials, the major problmes of conventional grinding are grinding burn, wheel wear, grinding surface crack, loading and glazing, When a conventioanl grinding wheel is used, wheel wear and grinding surface crack easily occur in low heat conductive material and annealed steel. Intermittent grinding is suitable for diffcult-to-matrical such as stainless steel, titanium alloy, aluminum alloy and copper alloy. The purpose of this paper is to develop a new type intermittent wheel of the grinding system for improving the problem of stainless steel grinding, to observe the effect of intermittent grinding on surface quality and grinding characteristics of stainless steel grinding using intermittent grinding wheel. The characteristics of intermittent grinding system improve surface quality, low grinding temperature and low loading.