• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.7
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• pp.800-808
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• 2004

Wind tunnel test of an airplane model with forward swept wing was done in KARI LSWT to evaluate and measure the aerodynamic characteristics of initially designed configuration. Since the given wing planform did not fully satisfy the design requirements, local flow control devices such as vortilon, vortex generator and flow fence were used to delay separation and to enhance aerodynamic characteristics. Also decision making processes of design parameters such as vertical tail boom length, the location, size and the incidence angle of horizontal tail were discussed. The general aerodynamic characteristics of forward swept wing for various control surface deflection conditions of flap, aileron and elevator were also given.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.1
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• pp.25-31
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• 2019

An underwater glider is a type of autonomous unmanned vehicle and it advances using a vertical zig-zag glide. For this purpose, the position of an internal battery is regulated to control its attitude, and the amount of water in a buoyancy bag is regulated to control the depth. Underwater glider is suitable for a long-distance mission for a long time, because the required energy is much smaller than the conventional autonomous unmanned vehicle using propeller propulsion system. In this paper, control of horizontal tail wing is newly added to the conventional battery position and buoyancy control. The performance of the proposed controller is shown through Matlab simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.9
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• pp.708-713
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• 2013

KARI is developing a solar-electric powered HALE UAV(EAV-3). For demonstrating the technology, EAV-2H, a down-scaled version of EAV-3, is developed and after EAV-2H's initial flight test, the directional stability and control need to be improved. Thus, the vertical tail and rudder of EAV-2H are redesigned with Advanced Aircraft Analysis(AAA). Size of the rudder is increased from mean chord ratio of rudder to vertical tail, $C_r/C_v(%)=30$ to $C_r/C_v(%)=60$ and size of the vertical tail is reduced 15%. As a result, the directional control to side wind($v_1$) is improved to sideslip angle, ${\beta}(deg)=25^{\circ}$ and $v_1(m/sec)=3.54$. Also, variation of airplane side force coefficient with sideslip angle ($C_{y_{\beta}}$) and variation of airplane side force coefficient with dimensionless rate of change of yaw rate ($C_{y_r}$) are reduced 15% and 22%, respectively to minimize the effect of side wind. The empennage design of EAV-2H is verified with flight tests and applied to design of KARI's solar-electric-powered EAV-3.

• Journal of the Korea Institute of Building Construction
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• v.5 no.4 s.18
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• pp.145-152
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• 2005

Long-term axial shortening of the vertical elements of tail buildings results in differential movements between two elements and may lead to the additional moments of connection beam and slab elements, and other secondary effects, such as cracks of partitions or curtain walls. Accurate prediction of time-dependent column shortening is essential for tall buildings from both strength and serviceability aspects. The compensation method is different from reinforced concrete and SRC(Steel Reinforced Concrete) members. The SRC columns are usually compensated according to total differential shortening between two vertical elements. In this study, column shortenings of 37-story W building under construction are predicted and compensated. The SRC column shortenings are compared with the actual column shortening by field measurement and the column shortenings are reanalysed and recompensated.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.2
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• pp.213-224
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• 2012

The integrated core network architecture and various mobile subscriber behavior can result in a significant increase of signaling load inside the evolved packet core network proposed by 3GPP in Release 8. Consequently, an authentication signaling analysis can provide insights into reducing the authentication signaling loads and latency, satisfying the quality-of-experience. In this paper, we evaluate the signaling loads in the EPS architecture via analytical modeling based on the renewal process theory. The renewal process theory works well, irrespective of a specific random process (i.e. Poisson). This paper considers various subscribers patterns in terms of call arrival rate, mobility, subscriber's preference and operational policy. Numerical results are illustrated to show the interactions between the parameters and the performance metrics. The sensitivity of vertical handover performance and the effects of heavy-tail process are also discussed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.3
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• pp.193-203
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• 2018

Capture efficiencies of commercial shrimp trawls may improve if their designs took into better account behavioral responses of wild shrimp to approaching cod-end of the trawls. Here we report results of water tunnel-based experimental studies of responses of wild California target prawns to several different near-realistic netting configurations over a range of water velocities (0.3-0.7 m/s). Netting panels were oriented at parallel to water flows (FP) on the bottom of test section, vertical (VT) or diagonal sloping backward (DG), bottom to top. Behavioral responses were recorded by video camera and analyzed frame by frame. Measured responses included rates of penetrating through netting by behavioral features and tail-flip frequencies. Frequencies of prawn passing through the nets increased with flow speed for both orientations and were higher at given speeds for sloped nets. Other behavioral features (e.g., passage head-or tail-first) also varied significantly with water velocities and netting orientation. Interactions of penetrating rates between netting orientations and flow speeds also were significantly dependent, except for prawn size. Additional studies are needed of other shrimp species and at higher water velocities more similar to actual field operations using trawls to improve size selectivity.

• International Journal of High-Rise Buildings
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• v.7 no.3
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• pp.255-264
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• 2018

This paper introduces three distinctive means for the use of a 189-meter high damped structure ensuring safety against earthquake: 1. Realization of L-shaped elevational structural planning: The bottom and top of the tower have belt trusses and hat trusses respectively to restrain the bending deformation. Furthermore, large-capacity oil dampers (damping force 6,000 kN) are installed in the middle part of the tower to restrain the higher-mode deformation. 2. Realization of L-shaped planar structural planning: We devised a means of matching the centers of gravity and rigidity by adjusting planar rigidity. Moreover, viscous damping devices are located at the edges of the L-shaped plan, where torsional deformation tends to be amplified. We call this the "Damping Tail" system. 3. Composite foundation to equalize deformations under different loading conditions: We studied the vertical and horizontal deformations using sway-rocking and 3D FEM models including the ground, and applied multi-stage diameter-enlarged piles to the tower and a mat foundation to the podium to keep the foundations from torsional deformations and ensure structural safety.

• Archives of Plastic Surgery
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• v.43 no.4
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• pp.321-327
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• 2016

There are many women who want larger and brighter eyes that will give a favorable impression. Surgical methods that make the eye larger and brighter include double eyelidplasty, epicanthoplasty, as well as lateral canthoplasty. Double eyelidplasty produces changes in the vertical dimension of the eyes, whereas epicanthoplasty and lateral canthoplasty create changes in the horizontal dimension of the eyes. Epicanthoplasty, a surgical procedure which enlarges the eye horizontally, is performed at the inner corner of the eye, whereas lateral canthoplasty enlarges the outer edge of the eye. In particular, if the slant of the palpebral fissure is raised and the horizontal dimension of the palpebral fissure is short, adjusting the slant of the palpebral fissure through lateral canthoplasty can achieve an enlargement of eye width and smoother features. Depending on the patient's condition, even better results can be achieved if this procedure is performed in conjunction with other procedures, such as double eyelid-plasty, epicanthoplasty, eye roll formation surgery, fat graft, and facial bone contouring surgery. In this paper, the authors will introduce in detail their surgical method for a cosmetic lateral canthoplasty that lengthens the lateral canthal angle and corrects the outer tail of the eyes, in order to ease the unfavorable impression.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.35-41
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• 2018

Unmanned Aerial Vehicles (UAV) have been used for various purposes in multiple fields, such as observation, communication relaying, and information acquisition. Nowadays, UAVs must have high performance in order to acquire more precise information in larger amounts than is now possible while performing for long periods. At present, domestically, a high-altitude long-endurance UAV (HALE UAV) for long-term flight in the stratosphere has been developed in order to replace some functions of the satellite. In this study, as a part of structural soundness evaluation of the aircraft structure developed for the HALE UAV, the structural soundness of the fasteners of the fuselage and tail is evaluated by calculating the margin of safety(M.S). The result confirms the validity of the design of the fasteners in the aircraft structure of the UAV.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.432-435
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• 2005

Extensive width reduction of slabs is an important technology to achieve continuous production between the steelmaking and hot rolling processes. Conventionally, a vertical roll process has been used to achieve extensive width reduction. However, it is impossible to avoid the defects such as dog-bone, fish tail and camber. The deformation behavior in the width sizing process is more favorable than that in conventional vertical rolling edger, i.e. the material better flows toward the center of slab. This study is carried out to investigate the deformation of slab by two-step sizing press. The FE-simulation is utilized to predict plastic deformation mode in compression by a sizing press of slabs far hot rolling. In this paper, the various causes of the asymmetrical rolling phenomena are mentioned for the purpose of understanding of rolling conditions. Analytical results of slab-deformation by sizing press are presented below in this study.