• 한국자동차공학회논문집
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• 제13권1호
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• pp.28-35
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• 2005

Fuel injection rate of an injector is affected by various injection conditions such as injection duration, fuel temperature, injection pressure, and voltage in LPG liquid injection systems for either a port-fuel-injection(PFI) or a direct injection(DI) in a cylinder. Even fuel injection conditions are changed, the air-fuel ratio should be accurately controlled to educe exhaust emissions. In this study, correction factor for the fuel injection rate of an injector is derived from the density ratio and the pressure difference ratio. A voltage correction factor is researched from injection test results on an LPG liquid injection engine. A compensation method of the fuel injection rate is proposed for a fuel injection control system. The experimental results for the LPG liquid injection system in a SI-engine show that this system works well on experimental range of engine speed and load conditions. And the fuel injection rate is accurately controlled by the proposed compensation method.

• 한국CDE학회논문집
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• 제18권6호
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• pp.417-427
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• 2013

Assembly direction is used in order to confirm the generated assembly sequences in an automatic assembly sequence planning system. Moreover, assembly sequence planners can ascertain the feasibility of a sequence during simulation with assembly direction based in a CAD environment. In other words, assembly direction is essential for sequence optimizing and automatic generation. Based on the importance of assembly direction, this paper proposes a method to select the best direction for the generated assembly sequence using disassembly simulation and geometrical common area between assembled parts. Simultaneously, this idea can be applied to verify the generated assembly sequence. In this paper, the automatic selection of assembly direction and sequence correction system is designed and implemented. The developed algorithms and the implemented system are verified based on case study in the CAD environment.

• 대한전자공학회논문지SP
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• 제43권2호
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• pp.48-56
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• 2006

본 논문에서는 사용자가 원하는 미디어를 제공하기위해 터치스크린과 출력 장치인 디지털 포토 프린터 사이의 색역을 고려하는 자동 컬러 보정 모듈을 가진 디지털 사진 인화 시스템인 디지털 포토 키오스크 시스템을 설계하고 구현하였다. 이 모듈은 디지털 카메라나 카메라폰으로 촬영된 영상에 대하여 고품질의 결과물을 제공할 수 있는 이미지 보정 기능을 수행하는 것이다. 이 기능은 실시간 처리를 위해 LUT(look-up table)로 구현되어 사용자의 원터치 방식으로 동작하는 인터페이스를 제공한다. 따라서 흑백모드, 원톤 색상모드, 밝기 및 채도 조절 등의 이미지 편집 기능으로 사용자의 취향에 맞는 사진을 출력할 수 있고, 입출력 장치간의 자동 컬러 보정 모듈을 지원함으로써 본 시스템은 부드러운 계조표현과 촬영 영상과 유사한 색의 사진을 제공할 수 있다.

• 한국멀티미디어학회논문지
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• 제9권4호
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• pp.470-481
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• 2006

본 논문에서는 복합 컬러모델과 얼굴특정 정보를 이용하여 실시간으로 얼굴영역을 검출 추적하고 기울어진 얼굴영상을 보정하는 시스템을 제안하였다. 제안한 시스템은 YCbCr과 YIQ 컬러모텔을 사용하여 얼굴 후보영역을 검출하였다. 얼굴 후보영역에서 수평 수직 투영기법을 사용하여 얼굴을 검출하고 하우스도르프 정합 방법을 사용하여 얼굴을 추적하였다. 또한 검출된 얼굴영상으로부터 눈 특징자의 기울기 정보를 보정함으로써 얼굴 기울기를 보정하였다. 실험결과 제안한 알고리즘이 주위환경 변화가 있는 실시간 얼굴검출과 추적 및 기울어진 얼굴인식에 강인하였다. 실험에서는 110개의 테스트 얼굴 영상을 사용하여 좋은 성능결과를 얻었다. 실험결과 얼굴검출과 얼굴추적율은 각각 92.27%와 92.70%를 나타내었고 얼굴 정보들로부터 90.0%의 얼굴인식율을 얻었다.

• 한국항공우주학회지
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• 제30권8호
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• pp.30-36
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• 2002

풍동시험 모형은 모형 지지부 삽입 등으로 실제 비행체와 다른 형상을 갖게 된다. 이러한 형상의 차이는 비행시험과 다른 힘과 모멘트를 발생시키게 되므로 이에 대한 보정은 필수적이다. 이러한 보정에는 cavity 압력 보정, 모형 지지부 간섭 보정 등이 있다. 본 시험에 사용된 모형은 내장밸런스와 함께 벨리 스팅 지지부를 사용하였으며 보정을 위하여 모형지지부 두께변화 방법과 더미 스팅 방법, wire support 방법의 시험결과를 비교하였다. 모형 지지부 두께 변화 방법은 간섭이 거의 없는 것으로 알려진 wire support 방법과 시험결과가 잘 일치하였다.

• Journal of Astronomy and Space Sciences
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• 제10권2호
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• pp.189-196
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• 1993

상해 천문대 Sheshan 관측소의 레이저 위성거리 측정기기를 이용하여 LAGEOS II위성에 대한 레이저 관측을 수행하여 총 1,838점을 얻었다. 관측된 거리 자료를 지상목표물 관측에 의한 관측기기 지연보정, 대기굴절 보정, 위성의 질량중심거리 보정, 일반 상대론적 보정과 지구 고형체 조석, 극 조석, 대양 조석을 포함한 조석보정을 통해 지연값을 결정하였는데 거리보정의 평균값은 19.12m이다. 결국 다항식 fitting 과 최소 자승법을 이용하여 계산한 관측값의 내부 정밀도 평균은 $\pm$7cm이다. 잡음을 제거하고 보정된 최종 관측점은 1,340점으로 관측점 총수에 대한 잡음비율은 27.1%이다.

• 대기
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• 제31권5호
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• pp.473-488
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• 2021

A new physical/statistical diagnostic downscale model has been developed for use to improve near-surface air temperature forecasts. The model includes a series of physical and statistical correction methods that account for un-resolved topographic and land-use effects as well as statistical bias errors in a low-resolution atmospheric model. Operational temperature forecasts of the Local Data Assimilation and Prediction System (LDAPS) were downscaled at 100 m resolution for three months, which were used to validate the model's physical and statistical correction methods and to compare its performance with the forecasts of the Korea Meteorological Administration Post-processing (KMAP) system. The validation results showed positive impacts of the un-resolved topographic and urban effects (topographic height correction, valley cold air pool effect, mountain internal boundary layer formation effect, urban land-use effect) in complex terrain areas. In addition, the statistical bias correction of the LDAPS model were efficient in reducing forecast errors of the near-surface temperatures. The new high-resolution downscale model showed better agreement against Korean 584 meteorological monitoring stations than the KMAP, supporting the importance of the new physical and statistical correction methods. The new physical/statistical diagnostic downscale model can be a useful tool in improving near-surface temperature forecasts and diagnostics over complex terrain areas.

• Journal of Positioning, Navigation, and Timing
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• 제12권4호
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• pp.349-358
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• 2023

The Satellite-Based Augmentation System (SBAS) plays a significant role in the fields of aviation and navigation: it corrects signal errors of the Global Navigation Satellite System (GNSS) and provides integrity information to facilitate precise positioning. These SBAS systems have been adopted as international standards by the International Civil Aviation Organization (ICAO). In recent SBAS system design, the Minimum Operational Performance Standards (MOPS) defined by the Radio Technical Commission for Aeronautics (RTCA) must be followed. In October 2014, South Korea embarked on the development of a Korean GPS precision position correction system, referred to as Korea Augmentation Satellite System (KASS). The goal is to achieve APV-1 Standard of Service Level (SoL) service level and acquisition of CAT-1 test operating technology. The first satellite of KASS, KASS Prototype 1, was successfully launched from the Guiana Space Centre in South America on June 23, 2020. In December 2022 and June 2023, the first and second service signals of KASS were broadcasted, and full-scale KASS correction signal broadcasting is scheduled to start at the end of 2023. The aim of this study is to analyze the precision of both the GNSS system and KASS system by comparing them. KASS is also compared with Japan's Multi-functional Satellite Augmentation System (MSAS), which is available in Korea. The final objective of this work is to validate the usefulness of KASS correction navigation in the South Korean operational environment.

• Journal of Positioning, Navigation, and Timing
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• 제3권1호
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• pp.17-23
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• 2014

Satellite Based Augmentation Systems (SBAS) provide ionospheric corrections at geographically five degree-spaced Ionospheric Grid Points (IGPs) and confidence bounds, called Grid Ionospheric Vertical Errors (GIVEs), on the error of those corrections. Since the ionosphere is one of the largest error sources which may threaten the safety of a single frequency Global Navigation Satellite System (GNSS) user, the ionospheric correction and integrity bound algorithm is essential for the development of SBAS. The current single frequency based SBAS, already deployed or being developed, implement the ionospheric correction and error bounding algorithm of the Wide Area Augmentation System (WAAS) developed for use in the United States. However, the ionospheric condition is different for each region and it could greatly degrade the performance of SBAS if its regional characteristics are not properly treated. Therefore, this paper discusses key factors that should be taken into consideration in the development of the ionospheric correction and integrity bound algorithm optimized for the Korean SBAS. The main elements of the conventional GIVE monitor algorithm are firstly reviewed. Then, this paper suggests several areas which should be investigated to improve the availability of the Korean SBAS by decreasing the GIVE value.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.478-481
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• 2005

The PMU (Payload Management Unit) is the main subsystem for the management, control and power supply of the MSC (Multi-Spectral Camera) Payload operation. It is the most important function for the electro-optical camera system that performs the Non-Uniformity Correction (NUC) function of the raw imagery data, rearranges the data from the CCD (Charge Coupled Device) detector and output it to the Data Compression and Storage Unit (DCSU). The NUC board in PMU performs it. In this paper, the NUC board system is described in terms of the configuration and the function, the efficiency for non-uniformity correction, and the influence of the data compression upon the peculiar feature of the CCD pixel. The NUC board is an image-processing unit within the PMU that receives video data from the CEV (Camera Electronic Unit) boards via a hotlinkand performs non-uniformity corrections upon the pixels according to commands received from the SBC (Single Board Computer) in the PMU. The lossy compression in DCSU needs the NUC in on-orbit condition.