• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.689-692
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• 2001

대용량 hard disk를 내장하고 있는 DTV용 PVR(Personal video recorder)에서는 단순히 수신되는 방송 stream을 녹화하고 재생하는 기능 뿐만 아니라 다른 여러 가지의 부가적인 기능들을 지원하는 것이 필요하다. 그 중의 하나가 기존의 아날로그 VCR의 사용자들에게 친숙한 fast-forward play, reverse play, pause 등과 같은 trick mode play기능을 지원하는 것이다. 그러나 MPEG video는 화면간의 상관관계를 이용하여 압축하는 방식을 채택하고 있으므로 재생하고자 하는 frame이 intra frame이 아닌 한 독립적으로 재생할 수가 없어서 trick mode play 기능을 구현하기가 용이하지 않다. 특히 reverse trick mode의 경우에는 original stream에서의 마지막 frame이 먼저 display되어야 하는데 이를 위해 하나의 GOP가 모두 decoding되어야 하므로 더욱 그 구현이 어렵다. 본 논문에서는 reverse trick mode를 구현하기 위한 여러 알고리즘을 소개하고 이에 대한 system 복잡도, 메모리 사용량 성능 등을 분석하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5B
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• pp.476-481
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• 2004

Since the bands 27.5 ∼ 28,350㎓ and 31.0 ~ 31.30Hz for existing fixed-satellite service were allocated to tile HAPS system in WRC-2000, the analysis on the interference effects between the existing FSS/GSO system and FS/HAPS system should be needed. To do study on the interference effects between above two systems, we can consider two frequency operational conditions, one is the Reverse mode, the other is Forward mode. In this paper, we analyzed the interference effects from airship of HAPS systems to satellite of the GSO system in the case of Reverse condition mode due to the C/I criterion, the latitude of HAPS and transmitting power of HAPS airship. In future, these results will be vital data to share between HAPS and GSO systems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.2
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• pp.185-188
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• 2006

We studied on the reverse twist near the pixel edge depending on the rubbing direction for the fringe field switching (FFS) mode. Liquid crystal (LC) dynamic and the transmittance near the pixel edge, where the various field directions are generated, depend on the initial rubbing direction because the position of reverse twist is decided by the angle between the electric direction and the LC director at a bias voltage. For example, when the rubbing angle is $7^{\circ}$, the reverse twist appears on the bottom position of the right sharp comer of the pixel edge so that the reverse region exists far away from main active region. But, when the rubbing angle is $-7^{\circ}$, the reverse twist appears on the top position of the right sharp comer of the pixel edge, resulting that the region becomes more close to the main active area and the unstable disclination lines (DLs) easily intrude into the active region. Therefore, it is necessary to keep the reverse twist region far from the active region and it is possible by controlling the rubbing direction in the design of a pixel electrode.

• Imaging Science in Dentistry
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• v.45 no.3
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• pp.141-145
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• 2015

Purpose: This study evaluated the diagnostic accuracy of the reverse contrast mode in intraoral digital radiography for the detection of proximal dentinal caries, in comparison with the original digital radiographs. Materials and Methods: Eighty extracted premolars with no clinically apparent caries were selected, and digital radiographs of them were taken separately in standard conditions. Four observers examined the original radiographs and the same radiographs in the reverse contrast mode with the goal of identifying proximal dentinal caries. Microscopic sections $5{\mu}m$ in thickness were prepared from the teeth in the mesiodistal direction. Four slides prepared from each sample used as the diagnostic gold standard. The data were analyzed using SPSS (${\alpha}=0.05$). Results: Our results showed that the original radiographs in order to identify proximal dentinal caries had the following values for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy, respectively: 72.5%, 90%, 87.2%, 76.5%, and 80.9%. For the reverse contrast mode, however, the corresponding values were 63.1%, 89.4%, 87.1%, 73.5%, and 78.8%, respectively. The sensitivity of original digital radiograph for detecting proximal dentinal caries was significantly higher than that of reverse contrast mode (p<0.05). However, no statistically significant differences were found regarding specificity, positive predictive value, negative predictive value, or accuracy (p>0.05). Conclusion: The sensitivity of the original digital radiograph for detecting proximal dentinal caries was significantly higher than that of the reversed contrast images. However, no statistically significant differences were found between these techniques regarding specificity, positive predictive value, negative predictive value, or accuracy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1033-1037
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• 2005

We have studied on the effect of the operation voltage according to the reverse twist for the different fringe field switching (FFS) structure. The FFS structure with a vertically patterned edge of the pixel electrode (VPP) has lower operation voltage comparing to the one with a horizontally patterned edge of the pixel electrode (HPP). The reason is like that the number of the pattern of the pixel edge for the VPP structure is one third comparing with the HPP structure and thus, there is small reverse twist area for the VPP structure. Actually, the reverse twist disturbs the twist of LC near adjacent active area, result that LCs near there have the unstable dynamics. That is, the operation voltage increases as the reverse twist area increases. Therefore, it is very important to design pixel electrode with a small reverse twist region for the FFS mode.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.495-502
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• 2014

Fast recovery diodes (FRDs) were developed using the $p^{{+}{+}}/n^-/n^{{+}{+}}$ epitaxial layers grown by low temperature epitaxy technology. We investigated the effect of electrostatic discharge (ESD) stresses on their electrical and switching properties using current-voltage (I-V) and reverse recovery time analyses. The FRDs presented a high breakdown voltage, >450 V, and a low reverse leakage current, < $10^{-9}$ A. From the temperature dependence of thermal activation energy, the reverse leakage current was dominated by thermal generation-recombination and diffusion, respectively, at low and high temperature regions. By virtue of the abrupt junction and the Pt drive-in for the controlling of carrier lifetime, the soft reverse recovery behavior could be obtained along with a well-controlled reverse recovery time of 21.12 ns. The FRDs exhibited excellent ESD robustness with negligible degradations in the I-V and the reverse recovery characteristics up to ${\pm}5.5$ kV of HBM and ${\pm}3.5$ kV of IEC61000-4-2 shocks. Likewise, transmission line pulse (TLP) analysis reveals that the FRDs can handle the maximum peak pulse current, $I_{pp,max}$, up to 30 A in the forward mode and down to - 24 A in the reverse mode. The robust ESD property can improve the long term reliability of various power applications such as automobile and switching mode power supply.

• ETRI Journal
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• v.35 no.4
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• pp.603-609
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• 2013

In this paper, we present a 600-V reverse conducting insulated gate bipolar transistor (RC-IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC-IGBT uses the deep reactive-ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC-IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.523-528
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• 2004

The bands 27.5 ∼ 28.35GHz and 31.0 ∼ 31.3GHz were allocated to the High Altitude Platform Station in WRC-2000. However, since these bands were already allocated to the existing fixed-satellite service, the analysis on the interference effects between the existing FSS/GSO system and FS/HAPS system should be needed. To do study on the interference effects between above two systems, we can consider two frequency operational conditions, one is the Reverse mode and the other Forward mode. In this paper, we considered the Forward mode as the frequency operational condition and analyzed the interference effect from a number of GSO satellites to HAPS ground station due to the I/N values, the latitude of HAPS and the satellite separation. In future, these results will be vital data to share between HAPS and GSO systems.

• The KSFM Journal of Fluid Machinery
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• v.18 no.1
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• pp.20-28
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• 2015

The pump-turbine impeller is the key component of pumped storage power plant. Current design methods of pump-turbine impeller are private and protected from public viewing. Generally, the design proceeds in two steps: the initial hydraulic design and optimization design to achieve a balanced performance between pump mode and turbine mode. In this study, the 3D inverse design method is used for the initial hydraulic impeller design. However, due to the special demand of high performance in both pump and reverse mode, the design method is insufficient. This study is carried out by modifying the geometrical parameters of the blade which have great influence and need special consideration in obtaining the high performance on the both modes, such as blade shape type at low pressure side (inlet of pump mode, outlet of turbine mode) and the blade lean at blade high pressure side (outlet of pump mode, inlet of turbine mode). The influence of the geometrical parameters on the performance characteristic is evaluated by CFD analysis which presents the efficiency and internal flow results. After these investigations of the geometrical parameters, the criteria of designing pump-turbine impeller blade low and high sides shape is achieved.

• Journal of the Korea Safety Management & Science
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• v.11 no.4
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• pp.193-199
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• 2009

Recently, an industrial production-distribution planning problem has been widely investigated in Supply Chain Management(SCM). One of the key issues in the current SCM research area is reverse logistics network. This study have developed a simulation model for the reverse logistics network. The simulation model analysis reverse logistics network issues such as inventory policy, manufacturing policy, transportation mode, warehouse assignment, supplier assignment. Computational experiments using commercial simulation tool ARENA show that the real problems. The model can be used to decide an appropriate production-distribution planning problem in the research area.