• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2477-2482
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• 2008

Effect of computational domain size in simulating of periodic obstacle flow has been investigated for the flow past tube banks. Reynolds number, defined by freestream velocity (U) and cylinder diameter (d), was fixed as 200, and center-to-center distance (P) as 1.5d. In-line square array was considered. Drag coefficient, lift coefficient and Strouhal number were calculated depending on domain size. Circular cylinders were implemented on a Cartesian grid system by using an immersed boundary method. Boundary condition is periodic in both streamwise and lateral directions. Previous studies in literature often use a square domain with a side length of P, which contains only one cylinder. However, this study reveals that size is improper. Especially, RMS values of flow-induced forces are most sensitive to the domain size.

• Journal of Applied Reliability
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• v.6 no.1
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• pp.37-50
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• 2006

The accelerated life tests of the catalytic gas sensor were performed at three different gas concentration conditions. From the test data, the power-Weibull model was estimated and the acceleration factor between test condition 25%LEL(Lowe Explosive Limit) and use condition 5%LEL was about 3 according to this acceleration model. Using this acceleration factor, life test specification for qualifying that B10 lifetime of the catalytic gas sensor meets the goal lifetime (5 years) was designed.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.660-664
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• 2005

There are operated the six thousand train in the interior of a country, $95\%$ of them are possible usage of resuscitation, Especially, Among them VVVF-Inverter vehicle has a merit of the highest recycle rate, but we don't use a apt recycled energy. Although the existing recycle energy used inverter method supply with electric power, it is decided in accordance with the state of sources. So efficiency of recycled electric power is of poor quality and catenary-voltage-fluctuation be generate because of recycled electric power. and it is able to affect system of safety train service. We'll research the method of supply according to wire condition after storing recycle energy made during train's stopping relation to Advanced EMU Research. Those methods are divided SMES, Fly-Wheel and Supercapacitor. and Considering the both economical efficiency and system application, we'll develop recycle energy storage system suitable our country condition.

• ETRI Journal
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• v.35 no.4
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• pp.726-729
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• 2013

For secure multimedia communications, existing encryption techniques use an online session key for the key exchange, for which key size is limited to less than 10 digits to accommodate the latency condition caused by user devices only being able to handle low computational loads. This condition results in poor security of recorded encrypted data. In this letter, we propose a packet key scheme that encrypts real-time packets using a different key per packet for multimedia applications. Therefore, a key of a relatively small size can provide after-transmission confidentiality to data of a real-time session.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.9
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• pp.107-116
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• 1996

In the stochastic structure for doing exact calculationk, an input number must be changed to a pulse stream. Because the performance of random number generator (RNG) is controlled by its initial condition, we suggested newly modified cellular automata (MCA) which is uses a counter for boundary condition. We compared newly suggested MCA RNG to previously reported RNGs using the AND gate passing outputs which have the same meaning of multiplication in the stochastic calculation. In order to use stochastic we studied about the method, one large RNG can generate many small random numbers. In this method, RNG must have large drive capabilities for many input comparator. So we studied about drive capabilities using BiCMOS circuit and CMOS circit by SPICE.

• Speech Sciences
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• v.11 no.4
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• pp.67-73
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• 2004

Packet loss, jitter, and delay in the Internet are caused mainly by the shortage of network bandwidth. It is due to queuing and routing process in the intermediate nodes of the packet network. In the Internet whose bandwidth is changing very rapidly in time depending on the number of users and data traffic, controlling the peak transmission bit-rate of a VoIP. system depending on the channel condition could be very helpful for making use of the available network bandwidth. Adapting packet size to the channel condition can reduce packet loss to improve the speech quality. It has been shown in [1] that a VoIP system with an AMR speech codec provides better speech quality than VoIP systems with fixed rate speech codecs. With the adaptive codec mode assignment. algorithm proposed in [1], in this paper, we performed the voice transmission experiments using the wireless LAN through the real Internet environment. Experimental results are analyzed and discussed with our findings.

• Journal of Sasang Constitutional Medicine
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• v.10 no.2
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• pp.305-349
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• 1998

We wanted to classify the food constitutionally. That was used to make the constitutional diet plan. And we checked through the clinical test. So the food was classified constitutionally by Sasang Constitutional Medicine(SCM). Constitutional diet plan was considered to Nutrition and Constitution. The clinical trial(use Taeumin diet plan) had performed during 8 weeks. We checked the Health and Nutrition condition. As the result, the Taeumin diet plan didn't change the health and nutrition condition of each constitution in good health. That could be presumed that constitution diet plan do not harm to healthy person.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.06a
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• pp.13-19
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• 2001

The use of reinforced soil have been increased due to it's cost effectiveness, flexibility and so on. In this study, a full-scale reinforced soil with rigid facing were constructed to investigate the soil pressure variation of reinforcing system. The results of soil pressure during backfill construction are described. The influence of facing stiffness on soil pressure is addressed. The results show that lateral earth pressures on the wall are active state during backfill. It is obtained that the lateral soil pressure highly depends on the installation condition of pressure cell and construction condition. Long-term measurement will be followed to verify the design assumptions with respect to the distribution of lateral stress on the facing.

• KIEAE Journal
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• v.2 no.1
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• pp.41-48
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• 2002

This study aims to investigate and evaluate the room acoustic designs of a multi purpose gymnasiums which do not use adjustable treatments in order to change the acoustical characteristics. Considering the main uses of gymnasium and auditorium, experiments were carried out using both nondirectional speakers on the stage and loudspeaker installed on the ceiling. The result from the study are as follows; Measured RT under unoccupied condition was a little longer than the expected value, therefore, in the case of occupied condition RT would be close to the optimum value. However, parameters that evaluate intelligibility and speech transmission property appeared to be low and have large differences depending on the measuring points, therefore, more effective sound reflecting surfaces and sound reinforcement systems should be considered.

• Journal of Technologic Dentistry
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• v.16 no.1
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• pp.5-11
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• 1994

On purpose of relative comparison of between air-vent attached pattern and non attached one, casting tests were accomplished by castability analysis unrig wax screen mesh pattern. Experimental specimens are divided Into 4groups. 1) Air-vent attached pattern with high casting pressure(coil spring type centrifugal casting machine 2.5turn). 2) Air-vent attached pattern with low casting pressure(coil spring type centrifugal casting machine 1.5turn). 3) Air vent non attached pattern with high casting pressure(coil spring type centrifugal casting machine 2.5turn). 4) Air-vent non attached pattern with low casting pressure(coil spring type centrifrgal casting machine 1.5turn). The main results are as follows : 1) The condition of high casting pressure no.1, no.3 were showed perfect castability. 2) The condition of low-casting pressure, there is a wide difference between no.2, no.4 group. Castability of no.2 group preferable to no.4 group(p<0.001). 3) Low casting pressure and complex shape cause the low-castability. So it is recommanded that use of air-vent in case of complex shaped wax pattern with low easting pressure.