• Journal of the Optical Society of Korea
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• 제15권4호
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• pp.335-339
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• 2011

Recently, we reported a single input channel joint transform correlator for the color pattern recognition which decomposes the input color image into three R, G, and B gray components and adds those components into a single gray image in the input plane. This technique has the merit of a single input channel instead of three input channels. However, we found this technique has some problems with discrimination impossibility in the case of a simple primary color pattern which results in the same gray level through the addition process. Thus, we propose a modified coding technique which selectively recombines the decomposed three R, G, and B gray components instead of the simple adding process. Simulated results show that the modified coding technique can accurately discriminate a variety of kinds of color images.

• Asia pacific journal of information systems
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• 제12권2호
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• pp.25-44
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• 2002

The internet-based electronic commerce is considered as a new strategic alternative to boost competitiveness for small and medium-sized enterprises(SMEs). However, very little research about them has been reported. Meanwhile, the cyber shopping shops in Korea are growing rapidly in their numbers, scales, and diversity of business models. The primary purpose of this study is to investigate the factors influencing outsourcing decisions in the implementation of small and medium-sized cyber shopping shops. Based on the previous studies on IS outsourcing, marketing channel, and their related theories, three areas of determinants(IT & organizational, product, marketing channel characteristics) were identified. Responses of 125 cyber shopping shops from e-mail survey indicate that IT capability, technical specificity of shop implementation, degree of product customization, average amount of order, marketing capability are negatively associated with outsourcing of cyber shopping shop implementation. The results also indicate that the outsourcing decision on systems implementation and marketing channel selection(direct/indirect selling) is performed separately.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.290-295
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• 2000

An experimental study was carried out in a cavity with upper channel and square heat surface by visualization equipment with Mach-Zehnder interferometer and laser apparatus. The visualization system consists of 2-dimensional sheet light by Argon-Ion Laser with cylindrical lens and flow picture recording system. Instant simultaneous velocity vectors at whole field were measured by 2-D PIV system(CACTUS'2000). Obtained result showed various flow patterns. Severe unsteady flow fluctuation within the cavity are remarkable and sheared mixing layer phenomena are also found at the region where inlet flow is collided with the counter-clockwise rotating main primary vortex. Photographs of Mach-Zehnder are also compared in terms of constant heat flux.

• ETRI Journal
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• 제44권4호
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• pp.531-542
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• 2022

With the increasing demand for unlicensed spectrum, several regulators have been opening up the 6-GHz band for unlicensed use while ensuring compliance with the technical requirement to avoid harmful interference in the existing primary services (PSs). In this paper, we present two methodologies, a channel-based method and a frequency-based method, which are applicable to a frequency coordination system that calculates the permissible transmit power in the channels or frequencies available to a secondary service (SS). In addition, we have demonstrated that the available transmit power of an SS can be maximized by adjusting the power allocation of the assigned resource units under the condition that the channel of the SS is partially overlapped with that of the PS. Based on the analysis results, it is suggested that it would be better to utilize the two methods selectively according to the operating channel conditions of the PS and the SS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권4호
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• pp.1192-1207
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• 2014

Dynamic spectrum sharing is a key technology to improve spectrum utilization in wireless networks. The elastic spectrum management provides a new opportunity for licensed primary users and unlicensed secondary users to efficiently utilize the scarce wireless resource. In this paper, we present a game-theoretic framework for dynamic spectrum allocation where the primary users rent the unutilized spectrum to the secondary users for a monetary profit. In reality, due to the ON-OFF behavior of the primary user, the quantity of spectrum that can be opportunistically shared by the secondary users is limited. We model this situation with the renewal theory and formulate the spectrum pricing scheme with the Bertrand game, taking into account the scarcity of the spectrum. By the Nash-equilibrium pricing scheme, each player in the game continually converges to a strategy that maximizes its own profit. We also investigate the impact of several properties, including channel quality and spectrum substitutability. Based on the equilibrium analysis, we finally propose a decentralized algorithm that leads the primary users to the Nash-equilibrium, called DST. The stability of the proposed algorithm in terms of convergence to the Nash equilibrium is also studied.

• 한국수산과학회지
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• 제18권1호
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• pp.74-83
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• 1985

대한해협 서수도의 거제도 남단 연근해를 중심으로 3개 정점에서 계절별로 수층별 chlorophyll a 함양을 분석하고 in situ 법으로 기초생산량을 측정하였다. 1. 1983년 추계의 기초생산력은 표층에서 $9.24{\sim}13.05\;mg\;C/m^3/h$ 범위로서 연중 가장 높았다. chlorophyll a 함량은 $0.66{\sim}1.22\;mg/m^3$ 범위로서 역시 가장 높았다. 2. 1984년 동계의 기초생산력은 표층에서 $0.75{\sim}1.77\;mg\;C/m^3/h$ 범위로서 하계보다 높았다. chlorophyll a 함량은 $0.19{\sim}0.41\;mg/m^3$ 범위로서 역시 하계보다 높았다. 3. 1984년 춘계의 기초생산력은 표층에서 $3.42{\sim}6.68\;mg\;C/m^3/h$범위로서 추계보다 낮았다. chlorophyll a 함량은 $0.34{\sim}0.64\;mg/m^3$ 범위로서 역시 추계 보다 낮았다. 4. 1984년 하계의 기초생산력은 표층에서 $0.57{\sim}0.79\;mg\;C/m^3/h$ 범위로서 연중 가장 낮았다. chlorophyll a 함량은 $0.11{\sim}0.17\;mg/m^3$ 범위로서 역시 가장 낮았다. 5. 동화수는 연중 비교적 높았으며 특히 추계와 춘계에 높았고 겨울에 가장 낮았다. 6. 기초생산량은 수심의 증가에 따라 급격히 감소하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제20회 KOSCO SYMPOSIUM 논문집
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• pp.162-168
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• 2000

This paper conducted experimental study of turbulent diffusion flame, equipped with a unique double swirler combustor for gas fuel. The burner has two vane swirlers which are fitted to primary, secondary air channel. Temperature, and NOx emission concentrations are measured in combustion flame region and velocity in cold flow for various primary/secondary air ratio conditions. The results showed the characteristics of swirl flame and decreasing NOx concentrations with increasing primary/secondary air ratio.

• Journal of Communications and Networks
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• 제17권3호
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• pp.265-266
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• 2015

In a recent paper [1], the authors investigated the maximum stable throughput region of a network composed of a rechargeable primary user and a secondary user plugged to a reliable power supply. The authors studied the cases of an infinite and a finite energy queue at the primary transmitter. However, the results of the finite case are incorrect. We show that under the proposed energy queue model (a decoupled M/D/1 queueing system with Bernoulli arrivals and the consumption of one energy packet per time slot), the energy queue capacity does not affect the stability region of the network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.287-304
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• 2012

Spectrum sensing is an important functionality for cognitive users to look for spectrum holes before taking transmission in dynamic spectrum access model. Unlike previous works that assume perfect knowledge of the SNR of the signal received from the primary user, in this paper we consider a realistic case where the SNR of the primary user's signal is unknown to both fusion center and cognitive radio terminals. A Kalman filter based adaptive Takagi and Sugeno's fuzzy system is designed to make the global spectrum sensing decision based on the observed energies from cognitive users. With the capacity of adapting system parameters, the fusion center can make a global sensing decision reliably without any requirement of channel state information, prior knowledge and prior probabilities of the primary user's signal. Numerical results prove that the sensing performance of the proposed scheme outperforms the performance of the equal gain combination based scheme, and matches the performance of the optimal soft combination scheme.

• 한국정보통신학회논문지
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• 제10권1호
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• pp.184-190
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• 2006

본 논문에서는 다중빔 스위칭 기능을 갖는 Ka 대역 통신해양기상위성의 통신 중계기를 이용한 고속 통신 서비스를 위한 링크 설계와 양질의 전송 서비스를 제공할 수 있는 최적의 전송 채널을 제안한다. 다양한 전송 서비스를 제공하는 Ka 대역 통신 중계기의 열화 요인으로 작용하는 군지연 및 비선형 그리고 이득 평탄도에 대한 채널 모델링과 성능 열화를 해석한다. 전송 데이터가 증가함에 따라 군지연과 비선형에 의한 영향은 증가하며, 군지연의 선형 성분과 비선형의 AM-AM 성분이 시스템 성능 열화에 지배적으로 작용하는 것을 알 수 있었다. 고속 데이터에 따른 광대역 전송 대역폭으로 낮은 군지연과 이득 평탄도를 얻기가 어려우므로 주로 열화 요소를 등화하여 넓은 범위의 초고속 위성통신 서비스에 효과적으로 제공하여야 한다. 분석된 결과는 통신해양기상위성을 이용한 최적의 고속 위성전송 시스템을 설계하고 운용하는데 활용될 수 있다.