• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.366-370
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• 2002

A kinematic ball bar measurement system can analyze the various errors of a machine tool easily and rapidly in a procedure and can measure many types of equipment such as chip mounter, PCB router, precision stage, etc. In this paper, the thermally induced errors are loused among various errors of a chip mounter because it affects the accuracy of the machine very much. Linear regression technique is adapted for the thermal error modeling. While the measurement and calibration of a chip mounter is difficult in general, this developed system is not only easy to apply for it but also improves the accuracy by 4 times or more.

• Annual Conference of KIPS
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• 2015.10a
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• pp.1763-1764
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• 2015

사이버나이프 시스템은 독특한 형태의 정위적 방사선 치료를 수행하는 로봇 팔을 이용하는 방사선 수술 시스템으로 치료 중 환자의 호흡 등에 따른 신체의 움직임에도 1mm 이내의 오차 범위에서 정확하게 방사선을 조사해야하며, 여러 병소를 동시에 치료할 수 있다. 사이버나이프 시스템은 로봇 팔, 선형 가속기, 병소 위치 추적 장치, 방사선 조사 스케줄러와 같은 다양한 모듈들이 통합된 시스템으로, 이를 통합 제어하기 위한 주제어 시스템이 필요하다. 본 논문에서는 본 연구원에서 개발하고자 하는 사이버나이프 주제어 시스템의 설계에 관하여 기술한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.135-143
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• 2009

Integrating the Global Positioning System (GPS) and Inertial Navigation System (INS) sensor technologies using the precise GPS Carrier phase measurements is a methodology that has been widely applied in those application fields requiring accurate and reliable positioning and attitude determination; ranging from 'kinematic geodesy', to mobile mapping and imaging, to precise navigation. However, such integrated system may not fulfil the demanding performance requirements when the baseline length between reference and mobil user GPS receiver is grater than a few tens of kilometers. This is because their positioning/attitude determination is still very dependent on the errors of the GPS observations, so-called "baseline dependent errors". This limitation can be remedied by the integration of GPS and INS sensors, using multiple reference stations. Hence, in order to derive the GPS distance dependent errors, this research proposes measurement processing algorithms for multiple reference stations, such as a reference station ambiguity resolution procedure using linear combination techniques, a error estimation based on Kalman filter and a error interpolation. In addition, all the algorithms are evaluated by processing real observations and results are summarized in this paper.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.166-168
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• 2023

기존 eLoran 수신기는 보정기준국(인천·평택항 반경 30km 이내에서만 이용 가능하며 ASF 맵보정 정보를 저장하는데 한계가 있음. 자체 오차정보를 보정하는 기능을 가진 eLoran/GPS 통합수신기의 알고리즘 및 성능 분석을 통해 더 넓은 해역에서 eLoran 서비스를 백업항법시스템으로 이용하기 위한 기반 마련

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.457-467
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• 2018

Currently, the regulation and rules for public surveying and the UCPs (Unified Control Points) adapts those of the triangulated traverse surveying. In addition, such regulations do not take account of the unique characteristics of GNSS (Global Navigation Satellite System) surveying, thus there are difficulties in field work and data processing afterwards. A detailed procesure of GNSS processing has not yet been described either, and the verification of accuracy does not follow the generic standards. In order to propose an appropriate procedure for field surveys, we processed a short session (30 minutes) based on the scenarios similar to actual situations. The reference network in Seoul was used to process the same data span for 3 days. The temporal variation during the day was evaluated as well. We analyzed the accuracy of the estimated coordinates depending on the parameterization of tropospheric delay, which was compared with the 24-hr static processing results. Estimating the tropospheric delay is advantageous for the accuracy and stability of the coordinates, resulting in about 5 mm and 10 mm of RMSE (Root Mean Squared Error) for horizontal and vertical components, respectively. Based on the test results, we propose a procedure to estimate the daily solution and then combine them to estimate the final solution by applying the minimum constraints (no-net-translation condition). It is necessary to develop a web-based processing system using a high-end softwares. Additionally, it is also required to standardize the ID of the public control points and the UCPs for the automatic GNSS processing.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.214-227
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• 2018

An object oriented crop model was developed to perform crop growth simulation taking into account complex interaction between biotic and abiotic factors in an agricultural ecosystem. A set of classes including Atmosphere class, Plant class, Soil class, and Grower class were designed to represent weather, crop, soil, and crop management, respectively. Objects, which are instance of class, were linked to construct an integrated system for crop growth simulation. In a case study, yield of corn and soybean, which was obtained at an experiment farm in Rural Development Administration from 1984 to 1986, were compared with yield simulated using the integrated system. The integrated system had relatively low error rate of corn yield, e.g., <4%, under sole and intercropping conditions. In contrast, the system had a relatively large underestimation error for above ground biomass except for grain compared with those observed for corn and soybean. For example, estimates of biomass of corn leaf and stem was 31% lower than those of observed values. Although the integrated system consisted of simple models, the system was capable of simulating crop yield under an intercropping condition. This result suggested that an existing process-based model would be used to have more realistic simulation of crop growth once it is reengineered to be compatible to the integration system, which merits further studies for crop model improvement and implementation in object oriented paradigm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.5
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• pp.417-428
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• 2017

In this paper, we describe the architectural design, unit component hardware design and core software design(Helmet Pose Tracking Software and Terrain Elevation Data Correction Software) of IHDS(Intelligent Helmet Display System), and describe the results of unit test and integration test. According to the trend of the latest helmet display system, the specifications which includes 3D map display, FLIR(Forward Looking Infra-Red) display, hybrid helmet pose tracking, visor reflection type of binocular optical system, NVC(Night Vision Camera) display, lightweight composite helmet shell were applied to the design. Especially, we proposed unique design concepts such as the automatic correction of altitude error of 3D map data, high precision image registration, multi-color lighting optical system, transmissive image emitting surface using diffraction optical element, tracking camera minimizing latency time of helmet pose estimation and air pockets for helmet fixation on head. After completing the prototype of all system components, unit tests and system integration tests were performed to verify the functions and performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.80-87
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• 2005

T-50 supersonic jet trainer aircraft using digital flight-by-wire flight control system receives aircraft flight conditions such as altitude, VCAS(Calibrated Airspeed) and Angle of Attack from IMFP(Integrated Multi-Function Probe). IMFP sensors information have triplex structure using three IMFP sensors. Air-data selection logic is mid-value selection in three information from three IMFP sensors in order to have more reliability. From supersonic flight test at high altitude, air-data information is dropped simultaneously because of supersonic shock wave effect. This error information may affect to aircraft stability and safety in supersonic area at low altitude. This paper propose that sensitivity analysis and HQS(Handling Quality Simulator) pilot simulation in order to analyze flight stability and controllability in supersonic area at low altitude when these information is applied to flight control law.

• Journal of IKEEE
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• v.22 no.4
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• pp.1036-1043
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• 2018

This paper presented future power system protection technologies through the HW/SW integration platform with IEC 61850 and IEEE c37.238 standards. To determine the implementation performance of the integrated platform, an example of EVM (Evaluation Module) was constructed to satisfy the standards. The platform has been identified as a future power system integrated IED(Intelligent Electronic Device) HW/SW technology that meets the level of error required by the time sync standard and the level of delay required by protecting the power system.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.309-317
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• 1992

현재 3차원 좌표측정기(Coordinate Measuring Machine:CMM)는 기계가공품의 수치검사(Dimensional inspection)에 널리 사용된다. 검사과정의 자동화를 향상시키기 위해 CMM을 이용한 컴퓨터통합검사시스템이 필요하게 되었다. 이 논문에서는 자유곡면 형상에 대해 CAD지향의 검사개념을 사용하여 CMM을 이용 자동측정하고 그 결과를 토대로 측정한 자유곡면에 대한 형상오차를 분석하는 부분을 다룬다.