• The Journal of the Korea Contents Association
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• v.6 no.4
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• pp.63-68
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• 2006

For the almost co티am convergent series $S_n$ of independent random variables, by investigating the limiting behavior of the tail series, $T_n=S-S_{n-1}=\sum_{i=n}^{\infty}X_i$, the rate of convergence of the series $S_n$ to a random variable S is studied in this paper. More specifically, the equivalence between the tail series weak law of large numbers and a limit law is established for a quasi-monotone decreasing sequence, thereby extending a result of Previous work to the wider class of the norming constants.

• Journal of Aerospace System Engineering
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• v.7 no.3
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• pp.15-19
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• 2013

Tail wing is important to designing of civil aircrafts, because it is responsible for aircraft stability and control. Tail wing has a role in aircraft control and makes aircraft fly stably without any pilot control input. Also, designing of tail wing determine trim drag force in whole aircraft. Center of gravity(CG) of aircraft travels with various effects as placement of passenger's seats, location of cargo bay, etc. In designing horizontal tail volume, aircraft CG travel has to be considered to have margin so that it should be sized to provide adequate stability and control for the airplane's entire CG range throughout the flight envelope. Finally, it is essential to have sufficient elevator control to perform stall at forward CG for all flaps down configurations. Such stalls establish the FAR stall speed which airplane take-off and landing performance. This paper deals with the process for tail wing design regarding the aircraft CG travel and results for 95-seat type turboprop aircraft.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.421-428
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• 2005

This paper described operation and vibration characteristics of a 'tail-fan' anti-torque performance test system. KARI (Korea Aerospace Research Institute) developed a 'tail-fan' anti-torque system of a helicopter and a performance test-rig to test the performance of the tail-fan. The performance test-rig consists of driving, supporting and rotating parts. In the process of the performance test, firstly, operation test of the test-rig were carried out to verify design specifications. Secondly, natural frequencies of fan blade and test-rig were measured respectively. Lastly, to find the operation rotating speed for the performance test, vibration test were carried out using accelerometers on tail gear box. The performance test conditions of the tail-fan to avoid a resonance were found from the fan-plot and vibration test results. The tail-fan performance tests were well done safely.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.308-317
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• 2016

The tail flip of the decapod shrimp is a main feature in escaping behavior from the mesh of the codend in the trawl. The characteristics of tail flip in target prawn was observed and analyzed in a water tunnel in respect of flow condition and mesh penetration by a high speed video camera (500 fps). The tail bending angle or bending time in static water was significantly different than in flow water (0.7 m/s) and resultantly the angular velocity in static water was significantly higher than in flow water when carapace was fixed condition. When escaping through vertical traverse net panel in water flow the relative moving angle and relative passing angle to flow direction during tail flip, it significantly decreases the number of shrimps escaping than the case of blocking shrimp. The bending angles of tail flip between net blocking and passing through mesh were not significantly different while the bending time of shrimp passing through mesh was significantly longer than when shrimp blocking on the net. Accordingly the angular velocity of passing through mesh was significantly slower than blocking on the net although the angular velocity of the tail flip was not significantly related with carapace length. The main feature of tail flip for mesh penetration was considered as smaller diagonal direction as moving and passing angle in relation to net panel as right angle to flow direction rather than the angular velocity of tail flip.

• The Korean Journal of Physiology
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• v.23 no.1
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• pp.139-149
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• 1989

Although tail flick reflex (TFR) in rats has been used as a classic model of the nociceptive test to evaluate the action of analgesics, there have been few studies on the origin of the latent period of TFR. Present study was performed to elucidate the mechanism of increase in latency of TFR by morphine in anesthetized rats. Tail skin and dorsolateral tail nerve were stimulated electrically and EMG activities were recorded from abductor caudae dorsalis muscle participating in tail flick reflex. In the case of noxious radiant heat stimulation to tail, the tail flick tension was recorded before and after administration of morphine. Then changes in latency and conduction velocity of peripheral nerve were evaluated. The results obtained were as follows: 1) The latencies of TFR evoked by the electrical stimulation of tail skin and dorsolateral tail nerve were all within 40 ms and were elongated by several milliseconds from control after the administration of morphine. Peripheral conduction velocities of tail flick afferent nerve were within the range of 10-25 m/s. 2) The conduction velocity of peripheral nerve was significantly reduced after morphine administration, therefore the afferent time (utilization time+conduction time to spinal cord) was significantly increased. But the time for central delay and efferent time was not affected by morphine. 3) The conduction velocity under room temperature $(20-25^{\circ}C)$ was significantly reduced after morphine while that under vasodilation state $(40{\sim}42^{\circ}C)$ increased, 30 min and 45 min after morphine. The conduction velocity under vasodilation state without treatment of morphine increased continuously 4) The latency in tension response of TFR evoked by electrical stimulation was elongated by several milliseconds from control while the latency evoked by noxious radiant heat was elongated by several seconds compared with that of control. From the above results, it could be concluded that: 1) the increased latency of TFR evoked by electrical stimulation of the tail after morphine administration was due to the reducton in conduction velocity of peripheral nerve, which was the secondry effect of morphine on the peripheral vasomotion and 2) increased latency of TFR evoked by noxious radiant heat was also due to the same effect of morphine and the increase in cutaneous insulation to the noxious heat.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2868-2872
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• 2007

In this study, a passive control using a boat-tail device is conducted for a three-dimensional car model in ground proximity. We consider various boat-tails and investigate the mechanism of drag reduction by them. By varying the length and slant angle of boat-tail, we obtain drag reductions up to 40%. From the oil-surface flow visualization and hot-wire measurement, the drag reduction by the boat-tail is characterized by the shear-layer instability and reattachment on the boat-tail, forming a small separation bubble at the upstream part of boat-tail surface, resulting in the delay of main separation and drag reduction. At high slant angles, the flow fully separates and drag is nearly same as that of no control.

• Journal of Korean Society for Quality Management
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• v.31 no.2
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• pp.194-204
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• 2003

It is very important to understand and interpret the meaning of the sigma level correctly through the Six Sigma project. Especially, the confusion over the relation between sigma level from the short-term point of view and defective proportion or DPMO from the long-term point of view may make a big gap between expected results of the Six Sigma project and real results in the field. The one-tail approximation is commonly used to calculate the sigma level both in most literatures introducing Six Sigma and actual cases of the Six Sigma project. Since the one-tail approximation undervalues the sigma level of the fields such as business and service of which the sigma level is generally low, however. there can be misleading results of the explanation of the sigma level and inappropriate project evaluation. This paper describes the relation between sigma level and defective proportion in detail and clears the difference between the one-tail and two-tail approximation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.1
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• pp.23-27
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• 2011

This study analyzes about the variation of pressure and stream velocity according to the movement of tail wing. The pressure at the front part of airplane becomes lower than at the rear part and the stream velocity has decreased by being bumped against the wing of airplane. The pressure at the front part of rudder becomes higher than at its rear part according to the movement of rudder among the tail wings of airplane. The more stream velocity becomes decreased, the more rudder spreads out. As the tail wing of airplane folds, the pressure at its front part becomes higher. And the pressure at its rear part becomes lower than at its front part. The more tail wing of airplane folds, the more stream velocity becomes decreased.

• Proceedings of the Korean Statistical Society Conference
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• 2005.05a
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• pp.185-190
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• 2005

For the almost certainly convergent series $S_n$ of independent random variables the limiting behavior of tail series ${T_n}{\equiv}S-S_{n-1}$ is reviewed. More specifically, tail series strong laws of large number and tail series weak laws of large numbers will be introduced, and their relationship will be investigated. Then, the relationship will also be extended to the case of Banach space valued random elements, by investigating the duality between the limiting behavior of the tail series of random variables and that of random elements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1715-1720
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• 2016

In the upcoming 5-generation mobile communication system, various techniques for improving the power efficiency and spectral efficiency have been proposed. 5G mobile communication system also have been studied a lot of multi-carrier-based modulation techniques like the 4G mobile communication system. In this paper, we analyzed the conventional system structure of the Zero-tail DFT-s-OFDM and UW (Unique Word) -DFT-s-OFDM system based on DFT-s-OFDM system in these techniques. UW and zero are added and used each system, and CP is removed. the result of quality of systems for simulation, OOB(Out of Band) power of Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM use the less time resource as long as CP length, also both systems are reduced about 11dB than DFT-s-OFDM system. In these result, Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM system are more effective than DFT-s-OFDM system.