• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.4
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• pp.324-332
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• 2016

In this paper, the terminal homing loop with a IIR-type strapdown seeker and a roll rate gyroscope is proposed. Basically, the proposed homing loop is based on the look-angle-control guidance. Since the range of the seeker is strictly limited, the missile is delivered to a point to lock the target on the seeker via non-guided flight during the midcourse guidance. The non-standard firing table is developed to compensate the wind and the target movement. To secure the delay margin is very important to prevent the instability of the homing loop when the time delay of the seeker is included. To validate the proposed homing loop, the 6-DOF nonlinear simulation is performed, and the Monte-Carlo simulation is also done for checking the robustness for the various kinds of uncertainty.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.317-325
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• 2014

For a missile with a strapdown seeker, line-of-sight rate for guidance is obtained by compensating the look angle rate from the strapdown seeker by the body angular rate from rate gyros. However, the body angular rate from rate gyros has different signal properties when it compared to the body angular rate implicitly included in the look angle rate. Typically this discrepancy causes instability of homing loop. In this paper, we propose a design method of homing loop where seeker delay is compulsively placed in the output signal of the rate gyros for accordance of both body rates. Also, PID control loop is considered for obtaining stabilized guidance command even though uncertainties of seeker delay is associated. The stability analysis for the linear homing loop before and after the compensation has been done. The stability and performance of the designed terminal homing loop is verified through full nonlinear 6-DOF simulations.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.1
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• pp.1-7
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• 2014

In this study, the effect of the automotive haptic-seat technology which can transmit the driving information by the vibro-stimulus from the seat was investigated to overcome previous system's limitation relied on the visual and audial method and to help handicap driving. A prototype haptic seat covers with 30 coin-type motors and driver module were developed for this sake. A driving simulator on the 6-DOF motion-base was used for driving situation and we executed the seat vibro-stimulus test with 10 young participants who have normal tactile sense. The haptic recognition ratio by 30 locations was measured and analyzed in the result. The intensity of vibro-stimulus was adjusted by input voltage of motors (1.5V,2.5V,3.5V). All vibro-stimulus locations at 2.5V and 3.5V could be recognized by all participants and even in the lowest recognition ratio of 1.5V. The results showed that the seat vibration stimulus could be useful to transfer the drivers' information while driving.

• Journal of Digital Contents Society
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• v.5 no.1
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• pp.22-27
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• 2004

To handle the high level radioactive materials such a spent fuel, the master-slave manipulaters (MSM) are wide1y used as a remote handling device in nuclear facilities such as the hot cell with sealed and shielded space. In this paper, the Digital Mockup which simulates the remote operation of the Advanced Conditioning Process(ACP) is developed. Also, the workspace and the motion of the slave manipulator, as well as, the remote operation task should be analyzed. The process equipment of ACP and Maintenance/Handling Device are drawn in 3D CAD model using IGRIP. Modeling device of manipulator is assigned with various mobile attributes such as a relative position, kinematics constraints, and a range of mobility. The 3D graphic simulator using the extermal input device of spare ball displays the movement of manipulator. To connect the exterral input device to the graphic simulator, the interface program of external input device with 6 DOF is deigned using the Low Level Tele-operation Interface(LLTI). The experimental result show that the developed simulation system gives much-improved human interface characteristics and shows satisfactory reponse characteristics in terms of synchronization speed. This should be useful for the development of work`s education system in the environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.232-239
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• 2009

The prediction of the separation trajectories of external stores carried by military aircraft is an important task in the area of aircraft design having the objective to define the operational, release envelopes. This paper presents the results obtained for safe store separation from a fighter aircraft by experimental methods in the subsonic wind tunnel. The problems associated with separation of external stores can be studied by the use of several wind-tunnel test techniques. Attention is given the two most useful techniques: 1) dynamically scaled drop-model testing, 2) grid testing. A description of each method is given and data obtained are shown to validate the similarity within acceptable limits.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2751-2757
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• 2015

To obtain the system requirement specification in the beginning of the precision guidance and control system development, the effectiveness and reliability analysis for the system are necessary. The main purpose of this research is to obtain the system requirement specification by carrying out the effectiveness analysis using the modeling and simulation(M&S) scheme. M&S model is constructed using 6-DOF dynamic model, environment model, guidanc -navigation & control model. Assume that the navigation sensor is consist of inertial navigation sensor(INS) and doppler velocity log(DVL), and the speed and direction of current is environment parameter. The effectiveness analysis is carried out using circular error probability(CEP) and variance analyze scheme. Also, the effectiveness analysis is utilized for cost-performance analysis considering the cost of commercial INS and DVL sensor. This paper shows the high-level INS and the low-level DVL configure a high price-performance integrated navigation system.

• Journal of KIISE:Software and Applications
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• v.33 no.3
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• pp.335-343
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• 2006

This paper proposes a novel technique of marker-based 2D-3D registration to combine 3D information obtained from preoperative CT images into 2D image obtained from intraoperative x-ray fluoroscopy image. Our method is divided into preoperative and intraoperative procedures. In preoperative procedure, we generate CT-derived DRRs using graphics hardware and detect markers automatically. In intraoperative procedure, we propose a hierarchical two- step registration to reduce a degree of freedom from 6-DOP to 2-DOF which is composed of in-plane registration using principal axis method and out-plane registration using minimal error searching method in spherical coordinate. For experimentation, we use cardiac phantom datasets with confirmation markers and evaluate our method in the aspects of visual inspection, accuracy and processing time. As experimental results, our method keeps accuracy and aligns very fast by reducing real-time computations.

• Journal of Ocean Engineering and Technology
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• v.32 no.6
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• pp.433-439
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• 2018

An investigation was conducted to determine whether the changes in the maneuvering forces and moments acting on a hull could be affected by changing the vertical center of gravity (VCG) of a tanker. The changes in the hydrodynamic forces and moment acting on a hull according to the restraint conditions of motion were examined using CFD for cases where the VCG was located at the design draught (100% of draught), under the design draught (75% of draught), and at half of the design draught (50% of draught). The following motion restraint conditions were selected: (1) fixed restraints for everything; (2) heave, pitch, and roll free restraint; and (3) heave and pitch free restraints. It was found that restraint condition (2) had the best agreement with the model experiment results. In addition, it was found that the hydrodynamic forces and moment acting on the hull with restraint condition (2) could be greatly affected in the model tests and CFD calculations by the various configurations for the vertical center of gravity of the hull. Finally, it was concluded that the location of the vertical center of gravity of the hull could be an important factor when more accurate hydrodynamic maneuvering forces and moment are estimated.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.127-138
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• 2018

In this study, the operational characteristics of a domestic vegetable transplanter were investigated. The main functional components and power path of the tranplanter were analyzed. The link structure of transplanting device waskinematically analyzed, and 3D modeling and dynamic simulation were performed. Based on this analysis, the trajectory of the bottom end of the transplanting hopper was analyzed. Also, the plant spacing according to the engine speed and the shifting stage of transplanting transmission was analyzed and verified by field test. As main results of this study, the transplanting device is one degree of freedom(DOF) 4-bar link type mechanism which comprises 10 links and 13 rotating joints. The transplanting hopper plants seedlings in a vertical direction while maintaining a constant posture by the links of transplanting device. The power is transmitted to both the driving part and transplanting part from the engine, and the maximum and minimum plant spacing of the transplanting device were 428.97 mm and 261.20 mm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.187-194
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• 2019

The off-axis Infra-Red(IR) seeker is mounted on the nose cone side of the anti-air high speed missile to alleviate thermal shield effect due to aerodynamic heating. The seeker output can not be regarded as the Line-of-Sight(LOS) rate any more as missile's roll motion to keep the target tracking is associated. In this paper, we propose a method to calculate the LOS rate for off-axis seeker on a 2-axis gimbal. Firstly, true LOS rate equations are analytically derived but not implementable because boresight error rate is not measurable. And then the first order lag approximation to obtain boresight error rate is proposed. The proposed LOS rate calculation method can compensate the coupling effect by considering the rotations of missile and gimbal. The performance of the proposed method is verified via full nonlinear 6-DOF(Degree of Freedom) simulations.