• Science of Emotion and Sensibility
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• v.10 no.4
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• pp.539-554
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• 2007

Pilots of large airplanes have to land their airplanes with insufficient visual information because of high approach speed, high vertical velocity and high location or altitude of the cockpits from the runway intending to touch down. This study verifies that, due to the insufficient information, large airplane pilots can't exactly perceive height of their airplanes during the flare. Study 1 explored whether it's possible for the pilots to accurately perceive height with the static visual cues only. We showed them pictures of the runway taken from the pilot's pionts of view and asked them to assess the height of the airplanes. They determined exact height of the airplanes at the height of 85 feet, but they could not, at lower than 55 feet which is the flare preparation altitude. Study 2 explored whether it's possible for the pilots to accurately perceive height when dynamic cues were added to the static visual cues. We showed them videos of the runway taken from the pilot's pionts of view. With more cues they determined exact height of the airplanes at the height of 50 feet, but they could not, at the altitude of lower than 30 feet which is the flare altitude. As experience is believed to be a major factor which affects interpretation of the visual cues, we compared the accuracy of the assessment of the experienced captions and that of the in-experienced first officers. We found there was no significant difference between them.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.1
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• pp.81-96
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• 2007

Nonlinear shoaling characteristics over surf zone are numerically investigated based on spatially averaged NavierStokes equation. We also test the validity of gradient model for turbulent stresses due to wave breaking using the data acquainted during SUPERTANK LABORATORY DATA COLLECTION PROJECT(Krauss et al., 1992). It turns out that the characteristics length scale of breaking induced current is not negligible, which firmly stands against ever popular gradient model, ${\kappa}-{\varepsilon}$ model, but favors Large Eddy Simulation with finer grid. Based on these observations, we model the residual stress of spatially averaged NavierStokes equation after Lagrangian Dynamic Smagorinsky(Meneveau et al., 1996). We numerically integrate newly proposed wave equations using SPH with Gaussian kernel function. Severely deformed water surface profile, free falling water particle, queuing splash after landing of water particle on the free surface and wave finger due to structured vortex on rear side of wave crest(Narayanaswamy and Dalrymple, 2002) are successfully duplicated in the numerical simulation of wave propagation over uniform slope beach, which so far have been regarded very difficult features to mimic in the computational fluid mechanics.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.120-131
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• 2004

In this paper, we propose the method of a motion planning generation in which the movement of the 3-link leg subsystem is constrained to a slider-link and a singular posture can be easily avoided. The proposed method is the jumping control moving in vertical direction which mimics a cat's behavior. That is, it is jumping toward wall and kicking it to get a higher-place. Considering the movement from the point of constraint mechanical system, the robotic system which realizes the motion changes its configuration according to the position and it has several phases such as; ⅰ) an one-leg phase, ⅱ) in an air-phase. In other words, the system is under nonholonomic constraint due to the reservation of its momentum. Especially, in an air-phase, we will use a control method using state transformation and linearization in order to control the landing posture. Also, an iterative learning control algorithm is applied in order to improve the robustness of the control. The simulation results for jumping control will illustrate the effectiveness of the proposed control method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.36-41
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• 2014

Electro-Mechanical Actuator installed on aircraft consists of a decelerator which magnifies the torque to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. EMA controls aircraft attitued, position, landing, takeoff, etc. It is important part of a aircraft. Aircraft maneuvering make vibration of EMA. Vibration may cause the vibration fatigue. For that reason, it is necessary to analyze the system safety. In this paper, first EMA is modeled in finite element method and analyzed the response from input vibration. second EMA is tested and analyzed from modal experimental data. third EMA Fe model is updated and re analyzed. and EMA is verified safety with $3{\sigma}$ stress and S/N curves.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.76-83
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• 2004

A Propulsion System of the CRW(Canard Rotor Wing) type UAV(Unmanned Aerial Vehicle) was composed of the turbojet engine to generate the propulsive exhaust gas, and the duct system including main and rotary ducts, the nozzle subsystem including main and tip jet nozzle for three flight modes such as lift/landing mode, low speed transition flight mode and high speed forward flight mode. Transient simulation performance utilized the ICV (Inter-component volume) method and simulated using the SIMULINK. Transient performance analysis was performed on 3 cases. Fuel flow schedules to accelerate from Idle to maximum rotational speed were divided into the step increase of the most severe case and ramp increase cases to avoid the overshoot of turbine inlet temperature, and variations of thrust and the turbine inlet temperature were investigated in some transient analysis cases.

• Ocean Systems Engineering
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• v.5 no.3
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• pp.181-198
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• 2015

An OSV (Offshore Support Vessel) is being used to install a structure which is laid on its deck or an adjacent transport barge by lifting off the structure with its own crane, lifting in the air, crossing splash zone, deeply submerging, and lastly landing it. There are some major considerations during these operations. Especially, when lifting off the structure, if operating conditions such as ocean environmental loads and lifting off velocity are not suitable, the collision can be occurred due to the relative motion between the structure and the OSV or the transport barge. To solve this problem, this study performs the physics-based simulation of the lifting off step while the OSV installs the structure. The simulation includes the calculation of dynamic responses of the OSV and the structure, including the collision detection between the transport barge and the structure. To check the applicability of the physics-based simulation, it is applied to a problem of the lifting off step by varying the ocean environmental loads and the lifting off velocity. As a result, it is confirmed that the operability of the lifting off step are affected by the conditions.

• Acta Via Serica
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• v.9 no.1
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• pp.67-90
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• 2024

India, Southeast Asia in general, and Siam in particular share a long history of cultural and commercial relations. Located in each other's extended neighbourhood, India and Thailand have a shared maritime boundary in the Andaman Sea. Situated in the strategic position, midway between West Asia on the one hand and East Asia on the other, India and Siam combined played a significant role in the maritime transactions in Asia and beyond. The geographical proximity between India and Siam led to multifaceted maritime interactions and exchanges. Siam was in the Indian sphere of cultural, religious, philosophical, technical, and linguistic influence much before the Common Era. The cultural and mercantile networks between India and Siam are well-attested by archaeological and literary sources. The archaeological findings in Siam and other Southeast Asian countries have revealed the dynamic trade and cultural exchange between India and Southeast Asia since the pre-Common Era. The Takola (modern Takua Pa) area served as a more suitable landing place for Indian merchants and there existed the settlement of the Indian mercantile community. Ligor (Nakhon Si Thammarat), Jaya (Chaiya), Patalung (Phatalung), U Thong, Ban Don Tha Pet, Ban U Taphao, Khao Sam Kaeo, and many other sites in Siam have brought to light a large variety of objects which demonstrate that ancient Siam had close mercantile contact with India as well as the Mediterranean world and China. The paper discusses in detail the cultural and trade links between India and Siam and their impact on the Maritime Silk Road.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.1
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• pp.63-70
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• 2008

As the number of cell phone users become growing, some researchers have presented that the imprudent use of mobile phones exerts harmful influence on electronic devices such as medical appliances, takeoff and landing system of aircraft. In this paper, we propose a usage model based on context-awareness which can be applied to mobile devices. The model controls the usage of both mobile devices themselves and mobile contents according to some context information like location, time, the circumference noise, etc. The proposed usage control model includes a dynamic role-based access control approach. To show the effectiveness of the proposed model, we have implemented a prototype system on an embedded board and PC server, and evaluated the performance of the system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.41-49
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• 2005

This paper discusses the test procedure, instrumentation, verification methodology and the results of the ground vibration test(GVT) performed on the KF-16D aircraft to estimate experimentally dynamic characteristics of the aircraft. The modal tests for 7 external store configurations were conducted to estimate effects of external stores on the aircraft vibration modes. To emulate free-free boundary conditions the test aircraft was mounted on its landing gear structure with deflated tires during the GVT. The airframe modal tests were done by burst random excitations with 6 to 8 shakers and about 200 accelerometers. Frequency response functions(FRFs) were measured for each test, and the FRFs were reduced and analyzed to identify the dynamic parameters interested. The analyses were carried out in two steps. To extract modal parameters such as, frequencies and damping ratios, the poly-reference least square complex exponential method was used in the time domain. The mode shape coefficients were estimated with the least squares frequency domain method to identify the vibration modes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.845-855
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• 2018

Cross section design of a prop-blade is carried out for VTOL(Vertical Takeoff and Landing) Quad Tilt Prop-rotor UAV with a maximum takeoff weight of 55 kg and a maximum cruising speed of 180 km/h. Design procedure for cross section design is established and design requirements for prop-blade are identified. Through the procedure, cross section design is carried out to meet the identified requirements. Main design factors including stiffness, weight per unit length, and elastic axis are obtained by using a finite element section analysis program, and the design weight of the prop-blade is predicted. The obtained design factors are used along with the rotor system analysis program CAMRAD II to evaluate the dynamic stability of prop-blade in operating environment. In addition, the prop-blade load is obtained by CAMRAD II software, and it is used to verify the safety of the prop-blade structure. If the design results are not satisfactory, design changes are made in an iterative manner until the results satisfy the design requirements.