• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.468-473
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• 2012

Cost is an important aspect in designing a target drone, however the poor performance of low cost IMU, GPS, and microcontrollers prevents the use of complex algorithms, such as ARS, or INS/GPS to estimate attitude angles. We propose an autopilot which uses rate gyro and GPS only for a target drone to follow a prescribed path for anti-aircraft training. The autopilot consists of an altitude hold, roll hold, and path following controller. The altitude hold controller uses vertical speed output from a GPS to improve phugoid damping. The roll hold controller feeds back yaw rate after filtering the dutch roll oscillation to estimate the roll angle. The path following controller operates as an outer loop of the altitude and roll hold controllers. A 6-DOF simulation showed that the proposed autopilot guides the target drone to follow a prescribed path well from the view point of anti-aircraft gun training.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4665-4671
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• 2013

Engine mounting system is the most responsible system for NVH performance of vehicle. The vibration at idle shake, road shake, Key ON/OFF, gear shift tuned by the engine mount position and stiffness. Previously described Engine mounting system theory investigated and summarized in this paper. Decoupling of the Power train rigid mode and Reducing the angle between Torque-Roll-Axis and Elastic-roll-Axis is starting point of optimization. Multi-optimization analysis was performed because of variety simulation case and FE-model. Eventually, Find the best mount location and the stiffness has improved the performance of the vehicle NVH.

• Korean Journal of Materials Research
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• v.32 no.2
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• pp.72-79
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• 2022

A cold roll-bonding process using AA1050, AA5052 and AA6061 alloy sheets is performed without lubrication. The roll-bonded specimen is a multi-layer complex aluminum alloy sheet in which the AA1050, AA5052 and AA6061 sheets are alternately stacked. The microstructural evolution with the increase of annealing temperature for the roll-bonded aluminum sheet is investigated in detail. The roll-bonded aluminum sheet shows a typical deformation structure in which the grains are elongated in the rolling direction over all regions. However, microstructural evolution of the annealed specimen is different depending on the type of material, resulting in a heterogeneous microstructure in the thickness direction of the layered aluminum sheet. Complete recrystallization occurs at 250 ℃ in the AA5052 region, which is lower by 100K than that of the AA1050 region. Variation of the misorientation angle distribution and texture development with increase of annealing temperature also differ depending on the type of material. Differences of microstructural evolution between aluminum alloys with increase of annealing temperature can be mainly explained in terms of amounts of impurities and initial grain size.

• Structural Engineering and Mechanics
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• v.68 no.5
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• pp.633-638
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• 2018

One of the important problems in the vehicle design is vehicle handling and stability. Effective parameters which should be considered in the vehicle handling and stability are roll angle, camber angle and scrub radius. In this paper, a planar vehicle model is considered that two right and left suspensions are double wishbone suspension system. For a better analysis of the suspension geometry, a kinestatic model of vehicle is considered which instantaneous kinematic and statics relations are analyzed simultaneously. In this model, suspension geometry is considered completely. In order to optimum design of double wishbones suspension system, a multi-objective genetic algorithm is applied. Three important parameters of suspension including roll angle, camber angle and scrub radius are taken into account as objective functions. Coordinates of suspension hard points are design variables of optimization which optimum values of them, corresponding to each optimum point, are obtained in the optimization process. Pareto solutions for three objective functions are derived. There are important optimum points in these Pareto solutions which each point represents an optimum status in the model. In other words, corresponding to any optimal point, a specific geometric position is determined for the suspension hard points. Each of the obtained points in the Pareto optimization can be selected for a special design purpose by designer to create an optimum condition in the vehicle handling and stability.

• Journal of Practical Agriculture & Fisheries Research
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• v.26 no.2
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• pp.25-30
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• 2024

This study was conducted to develop the hanging type circular-patterned system that at maximizing the spatial efficiency of strawberry cultivation to increase yields, while also reducing labor and improving energy efficiency. The system consists of a cultivation bed units, longitudinal moving device, bed lifting device, front and rear transfer devices, lateral transfer device, nutrient supply device, and control unit. Performance testing revealed that the operational motor for longitudinal movement should have a torque of at least 0.1Nm based on the design weight and traction force of the cultivation bed unit. The power consumption required to move one cycle was calculated to be approximately 149Wh when performing harvesting or maintenance tasks for all 10 cultivation beds. Vibration angles measured during bed movement showed that the lateral transfer resulted in a roll angle ranging from -0.62° to 0.68° and a pitch angle ranging from -3.79° to 5.26°. For longitudinal transfer, the roll angle ranged from -3.37° to 3.36°, and the pitch angle ranged from -0.45° to 0.49°.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.239-245
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• 2014

Purpose : The purpose of this study is to verify the accuracy of dose delivery according to the pitch and roll rotational setup error with 6D robotic couch in Intensity Modulated Radiation Therapy (IMRT) for pelvic region in patients. Materials and Methods : Trilogy(Varian, USA) and 6D robotic couch(ProturaTM 1.4, CIVCO, USA) were used to measure and analyze the rotational setup error of 14 patients (157 setup cases) for pelvic region. The total 157 Images(CBCT 78, Radiography 79) were used to calculate the mean value and the incidence of pitch and roll rotational setup error with Microsoft Office Excel 2007. The measured data (3 mm, 3%) at the reference angle ($0^{\circ}$) without couch rotation of pitch and roll direction was compared to the others at different pitch and roll angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) to verify the accuracy of dose delivery by using 2D array ionization chamber (I'mRT Matrixx, IBA Dosimetry, Germany) and MultiCube Phantom(IBA Dosimetry, Germany). Result from the data, gamma index was evaluated. Results : The mean values of pitch and roll rotational setup error were $0.9^{\circ}{\pm}0.7$, $0.5^{\circ}{\pm}0.6$. The maximum values of them were $2.8^{\circ}$, $2.0^{\circ}$. All of the minimum values were zero. The mean values of gamma pass rate at four different pitch angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) were 97.75%, 96.65%, 94.38% and 90.91%. The mean values of gamma pass rate at four different roll angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) were 93.68%, 93.05%, 87.77% and 84.96%. when the same angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$) of pitch and roll were applied simultaneously, The mean values of each angle were 94.90%, 92.37% and 87.88%, respectively. Conclusion : As a result of this study, it was able to recognize that the accuracy of dose delivered is lowered gradually as pitch and roll increases. In order to increase the accuracy of delivered dose, therefore, it is recommended to perform IGRT or correct patient's position in the pitch and roll direction, to improve the quality of treatment.

• Design & Manufacturing
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• v.18 no.2
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• pp.1-8
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• 2024

Unlike the roll-to-roll process that uses a steel roll and a nip roll, a vacuum roll can hold and transfer a thin film using a single roll. To precisely manufacture a vacuum roll, a thin outer cylinder must be machined, which is assembled on the outside of the roll and contacts the film via vacuum pressure. In this study, the effects of jaw width and chucking force on the deformation of the outer cylinder during the turning process were investigated using analysis, and a precision machining and burr removal process was developed. The deformation of the outer cylinder decreased almost linearly with increasing jaw width and increased with higher chucking force and larger cylinder diameter. Additionally, the deflection due to the weight of the outer cylinder was approximately three times greater than that caused by film tension. For the machined outer cylinder, a burr removal experiment was conducted, and concentricity and cylindricity were measured. Using a device that removes burrs by rotating a wheel connected to the main shaft at high speed, it was found that burrs generated on the inner diameter could be removed very efficiently. On the vacuum side, the concentricity errors of the inner and outer diameters were 0.015 mm and 0.014 mm, respectively, and on the opposite side, they were 0.006 mm and 0.010 mm, respectively. Additionally, the measurement of Total Indicator Runout (TIR) according to the angle showed that the maximum cylindricity of the outer and inner diameters was 0.02 mm and 0.025 mm, respectively. Finally, through burr-height measurement at the hole boundary, it was found that the heights were within 0.05 mm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.517-524
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• 2019

The overdrive hub clutch is attached to a 6-speed automatic transmission to reduce fuel consumption by using the additional power of the engine. This paper proposes a means to minimize the load and roll-over ratio on the punch during the piercing process for the overdrive hub clutch product. Die clearance, shear angle, and friction coefficient, which can affect the load and roll-over ratio of the punch during processing, were set as the design variables. Sensitivity analysis was also conducted to determine the influence of each design variable on the punch load and roll-over ratio. As a result, shear angle, friction coefficient and die clearance were found to be sensitive to load and roll-over ratio. The punch load and roll-over ratio were set as the objective function and the equation of each design variable and objective function was derives using the Response Surface Method. Finally, the optimal value of the design variables was derived using the Response Surface Method. Application of this model to finite element analysis resulted in 22.14% improvement in the roll-over ratio of the punch load and material.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.32-45
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• 2007

The T-50 advanced supersonic jet trainer employs the Relaxed Static Stability (RSS) concept to improve the aerodynamic performance while the flight control system stabilizes the unstable aircraft and provides adequate handling qualities. The T-50 flight control laws employ a proportional-plus-integral type controller based on a dynamic inversion method in longitudinal axis and a proportional type controller based on a blended roll system with simple roll rate feedback and beta-betadot feedback system. These control laws are verified by flight tests with various maneuver set flight envelopes and the control laws are updated to resolve flight test issues. This paper describes several concepts of flight control laws used in T-50 to resolve those flight test issues. Control laws for solving the roll-off problem during pitch maneuver in asymmetric loading configurations, improving the departure resistance in negative angle of attack conditions and enhancing the fine tracking performance in air-to-air tracking maneuvers are described with flight test data.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.342-351
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• 2012

Purpose: Aerial spraying with an agricultural unmanned helicopter became a new paradigm in the agricultural practice. Laterally tilting behavior of a conventional agricultural helicopter, resulting in the biased down-wash and uneven spray deposit is a physically intrinsic phenomenon while hovering and cruise flights. Authors studied and developed a roll-balanced agricultural helicopter with a raised pylon tail rotor system. In this study, the attitude of the roll-balanced helicopter was determined using the Kalman filter algorithm, and the quality of roll balancing of a bare-airframe helicopter was evaluated. Methods: Instantaneous attitudes were estimated using the advantage of gyroscope, followed by the long term correction and prediction using accelerometer data for the advantage of convergence. The attitudes of the fuselage were calculated by applying the Kalman filter algorithm. The spraying maneuver of the helicopter was performed at a field of 50 m long, and the attitude data were acquired and evaluated. Results: The determination of attitude using the inertial measurement unit(IMU) and Kalman filter was reliable and practical. The intrinsic attitude of the developed helicopter was stable and roll-balanced. The deviation of roll angle was ${\pm}6.3^{\circ}$ with an average of $0^{\circ}$, referring to roll-balanced. Conclusions: Handling quality of the roll attitude determined to be steadily balanced. The balancing behavior of the developed helicopter would result in an even spray pattern during aerial application.