• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.350-356
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• 2013

Photogrammetry has been widely used for measuring the important physical quantities in aerospace areas because it is a remote and non-contact measurement method. In this study, we analyzed photogrammetric error which can be occur in six degrees of freedom(6DOF) analysis among coordinates systems with single camera. Error analysis program were developed, and validated using geometric problem converted from imaging process. We analogized that the statistic from estimated camera pose which is need to 6DOF analysis is normally distributed, and quantified the photogrammetric error using estimated population standard deviation.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.479-484
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• 2003

A non-contact 6D motion tracking system is proposed. The system consists of two color cameras, a color image grabber and a host computer, Motions of a floating vessel was measured by the constructed system. The instantaneous forces of the floating vessel are analyzed. The floating vessel was put on the water in a small water container in free conditions. The measured forces are reconstructed by the measurement results. The system can be used to non-contact measurements for 6D dynamic analysis of floating vessels.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.3
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• pp.125-130
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• 1992

A digital 6-dof motion measuring system is developed using 7 accelerometers following Miles'[1] method. A snoic wave height gauge is also developed to measure the relative wave height at the foremost end of the ship. By combining the time series of both 6-dof motions and relative wave height, we can estimate the time series of real sea wave. Results of model tests shows the validity of the developed system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.8
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• pp.673-679
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• 2013

Photogrammetric techniques were used to analyze separation characteristics of store in safe separation flight test. In this analysis, we used single camera method to analyze 6 degrees of freedom of separated store. We established instrumentation requirements based on theoretical background of photogrammetry and guidelines of MIL-HDBK-1763. We applied the photogrammetry to flight test and extracted separation trajectory. We empirically estimated the input variables uncertainties of photogrammetry and its effects on separation trajectory. Using this trajectory which includes the photogrammetric error, we analyzed the safety of separation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.284-285
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• 2012

레저선박 중 하나인 8톤급 낚시선박에 대한 설계에 앞서, 우수한 복원성을 가지기 위해서는 실해역에 가장 적합한 선형의 개발이 중요하다. 특히 선행되어야 할 것은 선박의 운동 중 횡요 운동이 선박의 안전성 및 승선감에 미치는 영향에 대한 평가라 할 수 있다. 본 논문에서는 모형선 시험 중 전통적으로 사용되는 경사시험, 자유 횡요 시험 및 GZ 곡선을 통하여 기존선형과 대상선형에 대한 횡요 감쇠효과 및 복원성 평가를 수행하였다. 그리고 선형개선에 따른 GM계산 및 횡요운동 주기와 복원성 조사를 통해 낚시선박의 안전성과 승객의 승선감에 대한 영향을 조사하였다. 특히 자유횡요시험 시, 비접촉식 6자유도 운동계측기(Rodym DMM)와 무선 경사계를 이용한 계측 두 가지 방법을 함께 수행함으로서 횡요감쇠효과에 대한 신뢰도를 높였고 그 결과 기존 선형보다 대상 선형에 의한 감쇠효과가 더 크게 나타남을 확인할 수 있었다. 따라서 개선된 대상선형의 GZ곡선을 이용하여 설계시 적합한 복원성을 조사하였으며 자유횡요시험을 통하여 횡요주기가 증가함으로서 대상선형의 승선감이 더욱 향상된 것으로 분석되었다.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.187-200
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• 1999

An extensive investigation is performed to analyze the behavior of tieback anchored wall. Finite element method is used and several case histories are collected to investigate the relationship of wall deflection, anchor unbonded length, and anchor load. The finite element method can calculate wall deflection with changing the anchor unbonded length and the anchor load. Wall deflection normalized by excavation height can be related to anchor location so that it may produce a zone chart. It is found that a different chart showing the relation of the wall deflection, the anchor load, and anchor unbonded length can be constructed. It is necessary to collect more case histories considering soil conditions and to perform FE analysis extensively with changing bonded length to extend the capability of this relation chart into practice.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.4
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• pp.371-377
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• 2012

This paper presents an experimental investigation to figure out slamming impact pressure and flow characteristics of a rectangular Marine structure($800{\times}250{\times}50mm^3$) in free fall. The flow field has been obtained by 2-frame grey level cross correlation PIV(Particle Image Velocimetry) method, the impact pressure of the free fall model by a pressure acquisition system(Dewatron). The angles between a model and the free surface are adapted $10^{\circ}$ and $20^{\circ}$ respectively. Velocity field of water exit has higher better than water entry. The highest point, P2 of impact pressure under the bottom of the model has been appeared about 6 % higher values at 20 degrees than 10 degrees.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.6
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• pp.529-535
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• 2016

This study focuses on the comparison of measured data from 6-DOF motion sensor and strain gauge installed in the IBRV ARAON during 2015 summer voyage in the Arctic. Procedures to calculate the global ice load from MotionPak II inertial measurement system and the local load from stain gauge system are discussed. The ship's speed and peak load are determined in the concept of an ice collision "event". It is found that the peak values in the global ice calculated form whole ship motion analysis fall in the range of 1.5~3 times of the local ice load based in strain gauge measurement.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.163-171
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• 2020

A model test for assessment of towing stability and seakeeping of a multi-purpose mobile base (MMB) was performed in calm water and wave conditions. Scale ratio of the MMB was 1/48. Tension of the towing line was measured during tests to estimate effective power to tow the full scale MMB. The tests were repeated with towing speed. In addition, an inertial measurement unit was used to measure six DOF motion of the model. Seakeeping performance was assessed through the captive model test.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.4
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• pp.32-42
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• 1990

The method using Rankine Soure distribution over the hull surface and undisturbed free surface was applied to calculate the free surface flow around a ship. The ship hull as well as a local portion of the undisturbed free surface arc geometrically represented by quadrilateral panels and the source density is determined so as to satisfy the linearized free surface condition based on the double model flow. The pressure distribution, wave resistance, wave profile and hydrodynamic sinkage force and trim moment for the Wigley hull and the Series 60 hull with $C_B=0.60$ were calculated in the fixed condition. The calculated results were compared with the measured values. The dependance of the solution on the panel arrangement, particularly on the free suraface, was also studied through 11 numerical test cases for the Wigley hull.