• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.289-290
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• 2007

In order to improve the performance of a speech recognition system in the presence of noise, we propose a noise robust front-end using two-channel speech signals by separating speech from noise based on the computational auditory scene analysis (CASA). The main cues for the separation are interaural time difference (ITD) and interaural level difference (ILD) between two-channel signal. As a result, we can extract 39 cepstral coefficients are extracted from separated speech components. It is shown from speech recognition experiments that proposed front-end has outperforms the ETSI front-end with single-channel speech.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권4호
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• pp.257-262
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• 2003

A straightforward and effective method is presented for immobilizing enzymes on a microchip platform without chemically modifying a micro-channel or technically microfabricating a column reactor and fluid channel network. The proposed method consists of three steps: the reconstitution of a nitrocellulose (NC) membrane on a plane substrate without a channel network, enzyme immobilization on the NC membrane, and the assembly of another substrate with a fabricated channel network. As a result, enzymes can be stably and efficiently immobilized on a microchip. To evaluate the proposed method, two kinds of enzymatic reaction are applied: a sequential two-step reaction by one enzyme, alkaline phosphatase, and a coupled reaction by two enzymes, glucose oxidase and peroxidase, for a glucose assay.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.455-461
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• 2000

A multichannel signal processing algorithm for generating real time virtual sound field was proposed. Evaluation of the system performance was done by an objective function that minimizes the difference between the real and generated signals at each control point. Since impulse responses at the surface of a rigid sphere show characteristics similar to those of real HRTF, a rigid sphere model was adequate to simulate the multichannel sound system. A two-channel system and two four-channel systems were studied with various combinations of source locations and speaker positions. The results show that a two-channel system has its best configuration when the angle spanned by the loudspeakers is less than $60^{\circ}$. In the case of four-channel systems, the overall performance was highly improved with one pair of speakers fixed at an optimal position. Left/right symmetry was a reasonable choice, but the additional front/back symmetry degraded the performance of system.

• 한국통신학회논문지
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• 제36권8B호
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• pp.939-946
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• 2011

인터넷 뱅킹 서비스는 기존의 오프라인 서비스에 비해 편리성을 제공하지만, 해킹 등에 보안에 대한 많은 문제점을 가지고 있다. 이에 대해 금융기관은 보안을 강화하기 위해서 공인인증서, 보안토큰, 보안카드 OTP와 같은 인증 방법들을 제공하여 취약점을 보완토록 하였지만, 해킹 사건이 끊이지 않고 발생하고 있다. 특히 기존 인증방법들은 메모리해킹이나 중간자 공격과 같은 해킹에 대해서 취약점이 제기되고 있어, 새로운 인증방법이 필요하게 되었다. 본 논문에서는 인터넷 뱅킹에서 전자금융거래를 할 때 사용자의 PC와 Mobile 기기에서 이중으로 인증을 받는 Two Channel 인증 방식을 제안하고, 기존의 방식들과 비교분석을 통하여 안전성 및 신뢰성 측면이 강화되는 것은 확인할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.389-405
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• 2014

Outdated Channel State Information (CSI) was proved to have negative effect on performance in two-way relay networks. The diversity order of widely used opportunistic relay selection (ORS) was degraded to unity in networks with outdated CSI. This paper proposed a multiple relay selection scheme for amplify-and-forward (AF) based two-way relay networks (TWRN) with outdated CSI. In this scheme, two sources exchange information through more than one relays. We firstly select N best relays out of all candidate relays with respect to signal-noise ratio (SNR). Then, the ratios of the SNRs on the rest of the candidate relays to that of the Nth highest SNR are tested against a normalized threshold ${\mu}{\in}[0,1]$, and only those relays passing this test are selected in addition to the N best relays. Expressions of outage probability, average bit error rate (BER) and ergodic channel capacity were obtained in closed-form for the proposed scheme. Numerical results and Simulations verified our theoretical analyses, and showed that the proposed scheme had significant gains comparing with conventional ORS.

• 한국해양학회지
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• 제19권2호
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• pp.200-209
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• 1984

1982년 여름에 실시된 해양관측자료에 의하면 대마난류의 흐름은 한국해협 서수도에서 70cm/sec 이상의 강한 표면유속을 갖는 두 개의 분지 형태를 보였다. 부산에서 약 8km 부근에 나타나는 동한 난류로 불리우는 한 개의 분지는 한국 동해안을 따라 북쪽으로 흐르며, 부산으로부터 약 20km 떨어져 나타난 제2분지는 한국해협 통과 후 동쪽으로 향한다. 두 개의 흐름으로 분기되는 현상은 대마난류가 부산-대마도 단면에 이르기 이전에 형성되며, 두 분지의 용적 수송량 및 흐름의 폭은 큰 차이를 보이지 않는다. 분지의 갯수는 서수도의 폭에 의해 좌우되는 듯 하며, 두 분지의 흐름은 층두께의 변화와 서수도와 동해의 폭의 비율과 관련되는 것으로 보인다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.14-19
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• 2011

Two difference cavitation models based on the homogeneous mixture model are used to study cavitating flows through converging-diverging channel. Here, the cloud cavities, pressure distributions and other results have been obtained and compared to evaluate two cavitation models. What's more, differences are observed in the simulated results, due to the differences in characteristics of each model. Analytical results shows that the new improvement cavitation model is validated to have better effects on simulating cavitating flows

• 한국전산유체공학회지
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• 제7권3호
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• pp.53-59
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• 2002

A two-dimensional laminar flow through a channel with a pair of symmetric vertical fins is investigated. At far up- and down-stream from the fins, the plane Poiseuille flow exists in the channel. The Stokes flow for this channel is first investigated analytically and then the other laminar flows by numerical method. For analytic method, the method of eigen function expansion and collocation method are employed. In numerical solution for laminar flows, finite difference method(FDM) is used to obtain vorticity and stream function. From the results, the streamline patterns are shown and the additional pressure drop due to the attached fins and the force exerted on the fin are calculated. It is clear that the force depends on the length of fins and Reynolds number. When the Reynolds number exceeds a critical value, the flow becomes asymmetric. This critical Reynolds number Re/sub c/ depends on the length of the fins.

• 한국소음진동공학회논문집
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• 제27권1호
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• pp.94-99
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• 2017

Breaking the rigid connection between the two faces of the wall can significantly improve the sound transmission loss of the wall. This is usually achieved by resiliently mounting the gypsum board on one of the two faces of the wall using resilient channel. Resilient channel with less stiffness than that of air cavity could move the resonance frequency of the light-weight wall. So we can get higher sound transmission loss at low frequencies for light-weight wall using resilient channel. It's sound transmission loss is 17 dB higher than that of single stud wall, and 5 dB higher than that of double stud wall.

• 한국통신학회논문지
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• 제30권10A호
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• pp.949-957
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• 2005

In this paper, the performances of a single-user DS-UWB system applying two simple proposed channel estimation schemes are introduced, according to the newly updated DS-UWB PHY Layer standard from IEEE P802.15.3a. The performances of error control coding, different combining schemes in selective Rake receiver for DS-UWB system are analyzed. Both of the two channel estimation schemes using data-independent structure work well in DS-UWB system with few pilot bits. For the purpose of channel estimation and reduces the number of pilot bits, we apply a pilot symbol spreaded with $2{^8}-1\;or\;2{^9}-1$ periods of m-sequence for different channel estimation schemes.