• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.98-108
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• 1994

An assessment of a mathematical method of synthesing tire tread pitch noise spectra is studied. The method is based on the summation of phasors and the calculated spectra are conveniently generated as computer printout in the form of bar graph. The technique, its usefulness, its limitations and the implications of using such a model are discussed. This paper presents a basic study on optimum pitch arrangement for prediction and control of tire tread pitch noise in constraint condition relatied with tire properties, thus enabling optimum tread pitch arrangements to be determined at the design stage, by application of old tire tread pitch simulation.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.215-216
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• 2015

차세대 지상파 방송 규격인 Advanced Television Systems Committee (ATSC) 3.0 에서는 OFDM 심볼내의 특정 부반송파 대역에서 발생하는 군집 오류(burst errors)로 인한 성능 열화를 극복하기 위하여 주파수 인터리버 (frequency interleaver) 기법을 채택하였다. 주파수 인터리버는 OFDM 심볼 내의 데이터의 위치를 랜덤하게 배열하여 채널에서 발생하는 군집 오류 (burst error)를 분산시켜 성능 열화를 극복한다. 본 논문에서는 다양한 채널 환경에서의 주파수 인터리버의 성능을 펑가하고 효과를 분석한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.633-635
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• 2018

The compensation characteristics of the distorted WDM channels compensated for by dispersion management (DM) and optical phase conjugation in the long-haul (50 fiber spans ${\times}$ 80 km) transmission link with the randomly distributed single mode fiber (SMF) length and residual dispersion per spans (RDPS) are investigated as a function of the arrangement of SMF and dispersion compensating fiber (DCF) and the control position of net residual dispersion (NRD).

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.29-32
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• 2001

본 논문에서는 연구실에서 만든 음성인식기와 합성기를 이용하여 십자말 게임을 구현하였다. 십자말 게임에는 고사성어 600개 정도의 단어가 사용되었으며, 다른 영역별 사전을 추가 할 수 있도록 만들어졌다. 구현된 게임은 시작, 진행 등의 모든 과정이 음성으로 동작하며, 부과적인 정보는 음성 합성(TTS)에 의해 이루어진다. 십자말 게임에 사용되는 단어의 배열은 매번 랜덤하게 선택되도록 구성되며, 음성 인식기는 VCCV (Vowel + Consonant + Consonant + Vowel) 기반의 화자독립으로 구현되었다. 선택된 문제에 대한 설명은 텍스트로 보여주면서, 동시에 TTS 시스템에 의해 음성으로 출력된다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.6
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• pp.381-381
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• 2000

In this paper, we propose a real-time bandwidth allocation scheme of multiplexed VBR MPEG video sequences over ATM network. In order to real time processing, multiplexed source is estimated by linear-prediction per measurement period. If the result CLR value were not sufficient, we proposed a overallocation method and a reallocation one to guarantee QoS. We used two kinds of sources, one is random multiplexed source made of foot different video sources, the other is the one considered the arrange of I frame in the sequence. With those sources, we analyzed the linear prediction, compared overallocation with reallocation method. As a result, in both schemes, the objected CLR value is achieved, the sufficient value COR under 10% when mp is over 1.8 sec, the utilization is over 0.9. Especially, the COR value of the reallocation scheme is better at the same condition.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.6
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• pp.21-27
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• 2000

In this paper, we propose a real-time bandwidth allocation scheme of multiplexed VBR MPEG video sequences over ATM network. In order to real time processing, multiplexed source is estimated by linear-prediction per measurement period. If the result CLR value were not sufficient, we proposed a overallocation method and a reallocation one to guarantee QoS. We used two kinds of sources, one is random multiplexed source made of foot different video sources, the other is the one considered the arrange of I frame in the sequence. With those sources, we analyzed the linear prediction, compared overallocation with reallocation method. As a result, in both schemes, the objected CLR value is achieved, the sufficient value COR under 10% when mp is over 1.8 sec, the utilization is over 0.9. Especially, the COR value of the reallocation scheme is better at the same condition.

• Journal of KIISE
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• v.43 no.8
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• pp.910-918
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• 2016

A tensor is a multi-dimensional array that represents many data such as (user, user, time) in the social network system. A tensor generator is an important tool for multi-dimensional data mining research with various applications including simulation, multi-dimensional data modeling/understanding, and sampling/extrapolation. However, existing tensor generators cannot generate sparse tensors like real-world tensors that obey power law. In addition, they have limitations such as tensor sizes that can be processed and additional time required to upload generated tensor to distributed systems for further analysis. In this study, we propose TeT, a distributed tera-scale tensor generator to solve these problems. TeT generates sparse random tensor as well as sparse R-MAT and Kronecker tensor without any limitation on tensor sizes. In addition, a TeT-generated tensor is immediately ready for further tensor analysis on the same distributed system. The careful design of TeT facilitates nearly linear scalability on the number of machines.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1372-1382
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• 1999

The major source of errors in high-speed networks such as Broadband ISDN(B-lSDN) is buffer overflow during congested conditions. These congestion errors are the dominant sources of errors in 1high-speed networks and result in cell losses. Conventional communication protocols use error detection and retransmission to deal with lost packets and transmission errors. However, these conventional ARQ(Automatic Repeat Request) methods are not suitable for the high-speed networks since the transmission delay due to retransmissions becomes significantly large. As an alternative, we have presented a method to recover consecutive cell losses using forward error correction(FEC) in ATM(Asynchronous Transfer Mode)networks to reduce the problem. The performance estimation based on the cell discard process model has showed our method can reduce the cell loss rate substantially. Also, the performance estimations in ATM networks by interleaving and IP multicast service are discussed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.78-83
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• 2006

In this paper, we propose Active bandwidth allocation scheme of multiplexed streamed MPEG video sequences over BcN network. In order to real time processing, multiplexed source is estimated by linear-prediction per measurement period. n the result target quality value were not sufficient, we proposed a over-allocation method and a reallocation one to guarantee QoS. We used two kinds of sources, one is random multiplexed source made of four different video sources, the other is the one considered the arrange of I frame in the sequence. With those sources, we analyzed the linear prediction, compared over-allocation with reallocation method. As a result, In both schemes, the objected target quality value is achieved, the sufficient valuce bandwidth under 10% when measurement period is over 1.8 sec, the utilization is over 0.9. Especially, the Target of quality value of the reallocation scheme is better at the same condition.

• Polymer(Korea)
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• v.32 no.4
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• pp.359-365
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• 2008

We have fabricated a novel thermo-responsive nanofibrous surfaces by grafting PIPAAm by electron beam irradiation onto poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) nanofibrous mats. The electrospun PHBV nanofiber structures revealed randomly aligned fibers with average diameter of 400 nm. Increased atomic percent of nitrogen was observed on the PIPAAm-grafted PHBV mats after electron beam irradiation determined by ESCA. The amounts of PIPAAm-grafted onto PHBV films were $6.49{\mu}g/cm^2$ determined by ATR-FTIR. The PIPAAm-grafted surfaces exhibited decreasing contact angles by lowering the temperature from 37 to $20^{\circ}C$, while ungrafted PHBV surfaces had negligible contact angle change. This result indicates that PIPAAm surfaces, which are hydrophobic at the higher temperature, became markedly more hydrophilic in response to a temperature reduction due to spontaneous hydration of the surface-grafted PIPAAm. Thermo-responsive nanofibers showed good tissue compatibility. Cultured cells were well detached and recovered from the surfaces by changing culture temperature from 37 to $20^{\circ}C$.