• 대한산업공학회지
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• 제34권2호
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• pp.216-222
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• 2008

The determination of spectrum charges for the operators is a main issue to efficiently manage the limited radio spectrum resources. In this paper, we propose a model to compute the optimal charges for radio spectrum usage. The objective is to determine that will maximize the spectrum charges, and decision variables of ratios for actual or estimated revenues are considered. The spectrum charges are maximized under satisfying the least profit for operators based on Log-Linear demand function. The parameters of actual sales and minimum profit of operators are analyzed to make an efficient management for radio spectrum. The results show that the spectrum charges increase as the actual sales increase, but it decrease as the required minimum profit of operator increases. It is also observed that the government should increase the ratio for estimated sales if anticipating the poor market in the future, otherwise they should increase the ratio for actual sales to maximize the spectrum charges.

• 한국통신학회논문지
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• 제34권11B호
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• pp.1261-1271
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• 2009

경제적 가치가 급증하고 있는 주파수자원은 희소성으로 인하여 효율적으로 배분하는 것이 전파관리의 중요한 과제가 되고 있다. 특히, 지나치게 높은 수준의 주파수 할당대가는 초기 투자비용을 증대시켜 경쟁력 있는 시장 형성과 원활한 서비스 제공을 저해하는 요소가 되며, 이에 따라 소요되는 비용은 소비자 요금으로 부당하게 부과될 수 있다. 따라서 본 연구에서는 주파수 이용대가를 국가별로 비교하여 현재 우리나라의 주파수 할당대가 수준을 분석한다. 세계적으로 주파수 할당대가의 산정방법은 3세대 이동통신(3G 서비스, IMT-2000)의 사업자 선정을 기준으로 판단할 때 비교심사제도와 경매제도로 나누어 진행되어오고 있으며, 방법에 따라 주파수 이용대가의 결과는 다양하게 나타났다. 본 논문에서는 ITU, OVUM 등의 자료를 바탕으로 27개 국의 3G 서비스 주파수 할당대가 산정 결과를 정리한다. 또한 주파수 할당대가 산정 시 영향을 미치는 요인을 관련 선행연구를 토대로 선정하여 회귀분석을 실시한다.

• 산업경영시스템학회지
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• 제35권2호
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• pp.181-188
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• 2012

The fee system on spectrum usage is a usage fee that is charged for using spectrum provided by a wireless tower, and is used for management and promotion of the waves. The current fee system for spectrum usage in South Korea has faced many problems, such as complex calculation for fees, unjustified charges, unfairness in cost sharing among providers, and general inefficiency of operation. This study focuses on comparison of fee systems for spectrum usage of South Korea and other foreign countries, extraction of the root causes and problems by case analyses, and recommendation for better solutions to make a reasonable fee system for spectrum usage. The result of this study can be used as a solution to render spectrum usage more effective.

• 한국염색가공학회지
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• 제19권4호
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• pp.32-37
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• 2007

In this study, we have obtained the protein patterns using the membrane patterning of soft-lithography technique. The rapid detection of protein including bovine serum albumin (BSA) was resulted from the interaction with 1,3-bisdicyanovinylindane. For the proof of the interaction between BSA and dye, the UV-vis absorption spectra of BSA and dye were observed at 278 nm and 580 nm, respectively. As expected, the absorption spectrum of the interaction between BSA and dye was observed at 584nm. The absorption spectrum of the interaction was red-shifted. In addition, the optical images of the selectively reacted protein patterns showed the distinctive change of patterned color at different pH conditions. Because the dye has negative charges, the charge of BSA at different pH conditions could influence the interaction behavior between dye and BSA. Therefore, in the case of pH 7, the selectively patterned protein substrates obtained deep blue color pattern caused by electrostatic interaction between negative charges of the dye and positive charges of the BSA. However, in the case of pH 10, selectively patterned protein substrates obtained light blue color pattern because the electrostatic interaction was relatively lower than pH 7 due to the change of overall charge distribution of BSA.

• ETRI Journal
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• 제32권4호
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• pp.512-519
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• 2010

A cooperative model is presented to enable sharing of the spectrum with secondary users. Compared with the optimal model and competitive model, the cooperative model could reach the maximum total profit for secondary users with better fairness. The cooperative model is built based on the Nash equilibrium. Then a conceding factor is introduced so that the total spectrum required from secondary users will decrease. It also results in a decrease in cost which the primary user charges to the secondary users. The optimum solution, which is the maximum total profit for the secondary users, is called the collusion state. It is possible that secondary users may leave the collusion state to pursue the maximum of individual profit. The stability of the algorithm is discussed by introducing a vindictive factor to inhabit the motive of deviation. In practice, the number of secondary users may change. Adaptive methods have been used to deal with the changing number of secondary users. Both the total profit and fairness are considered in the spectrum allocating. The shared spectrum is 11.3893 with a total profit of 65.2378 in the competitive model. In the cooperative model, the shared spectrum is 8.5856 with the total profit of 73.4963. The numerical results reveal the effectiveness of the cooperative model.

• 대한의생명과학회지
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• 제12권3호
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• pp.267-274
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• 2006

Klebsiella pneumoniae is the leading cause of nasocomial infection and the most commonly isolated from clinical specimens. $Extended-spectrum-{\beta}-lactamase$ (ESBL) producing K. pneumoniae infection was associated with a significantly longer duration of hospital stay and greater hospital charges. The purpose of this study is to investigate the antibiotic resistant patterns and the DNA fingerprint types of extended-spectrum ${\beta}-lactamase$ (ESBL) producing K. pneumoniae. 223K. pneumoniae strains were collected from three general hospitals with more than 500 beds in Busan, Korea from September 2004 to October 2005. The minimum inhibitory concentration (MIC) of antibiotics was measured using the Gram negative susceptibility (GNS) cards of VITEK (Vitek system, Hazelwood Inc., MO). Random amplified polymorphic DNA method was used to detect DNA fingerprint of the organisms. Of the 226 K. pneumoniae isolates 65 ESBL-producing K. pneumoniae strains were detected by the Vitek system and confirmed by the double-disk synergy test. All the 65K. pneumoniae strains were resistant cefazolin, cefepime, ceftriaxone and aztreonam, and 83.0% of the organisms were resistant to ampicillin/sulbactam, 66.1% to tobramycin, 67.6% to piperacillin/tazobactam, 61.5% to ciprofloxacin, and 47.6% to trimethoprim/sulfamethoxazole and 43.0% to gentamicin. The RAPD patterns were distincted as 10 types by three random 10-mer primers (208, 272, 277). Among ten type patterns, three types (Ic, IIb, IIIe) were remarkably represented at patient of internal department, nerve surgery department, general surgery department, and neonatal room. These results indicate that RAPD can be useful for DNA of strains typing in the epidemiological investigations. Therefore more investigation are needed in order to prevent the ESBL type-producing K. pneumoniae from spreading resistance to oxyimino cephalosphorin antibiotics.

• Journal of Communications and Networks
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• 제16권6호
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• pp.627-638
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• 2014

In this paper, we study the joint price and power allocation in spectrum sharing macro-femtocell networks. The proposed game theoretic framework is based on bi-level Stackelberg game where macro base station (MBS) works as a leader and underlaid femto base stations (FBSs) work as followers. MBS has fixed data rate and imposes interference price on FBSs for maintaining its data rate and earns revenue while FBSs jointly adjust their power for maximizing their data rates and utility functions. Since the interference from FBSs to macro user equipment is kept under a given threshold and FBSs compete against each other for power allocation, there is a need to determine a power allocation strategy which converges to Stackelberg equilibrium. We consider two cases for MBS power allocation, i.e., fixed and dynamic power. MBS can adjust its power in case of dynamic power allocation according to its minimum data rate requirement and number of FBSs willing to share the spectrum. For both cases we consider uniform and non-uniform pricing where MBS charges same price to all FBSs for uniform pricing and different price to each FBS for non-uniform pricing according to its induced interference. We obtain unique closed form solution for each case if the co-interference at FBSs is assumed fixed. And an iterative algorithm which converges rapidly is also proposed to take into account the effect of co-tier interference on interference price and power allocation strategy. The results are explained with numerical simulation examples which validate the effectiveness of our proposed solutions.

• 한국전기전자재료학회논문지
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• 제14권2호
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• pp.145-151
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• 2001

In this study, blue light emiting, soluble PPV copolymers were synthesized by Witting reaction and characterized. ITO/copolymer/Ca and ITO/copolymer/A1 structured light emitting diodes(LED) were fabricated and their I-V characteristics were examined. Copolymers showed $\pi$-$\pi$ transition in UV-Vis./NIR spectra. The PL and abosorption spectrum showed the symmetric vibration modes with mirror images which means that copolymers are highly aligned. By introducing aliphatic hydrocarbon group on polymer main chain, the solubility of copolymers was improved and no significant effects of substituent were observed. The band offset of copolymers are well suited as light emitting material for LED application than monomer or oligomer does. THe band offset of copolymers is ∼3eV in PL spectrum and the threshold voltages of ITO/copolymer/Ca and ITO/copolymer/Al structured LED 3V, 12V respectively. In the case of ITO/copolymer/Ca LED, it is believed that the amount of electrons and holes is well balanced and the recombination of opposite charges occurs easily because the work functions of Ca and Al electrodes are 2.9 and 4.3eV respectively and the difference in barrier height between polymer and electrode was small.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.37-40
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• 2004

CdTe nanoparticles were synthesized in aqueous solution by colloidal method. The absorption and photoluminescence(PL) spectrum of the synthesized CdTe nanoparticles revealed the strong exitonic peak in the visible region. Photocurrent of CdTe nanoparticles were observed in the structure of Al/CdTe/ITO that was fabricated by spin coating of CdTe nanoparticles. The wavelength dependence of photocurrent was very similar to the absorption spectrum, indicating the charges generated by the absorption of photons give direct contribution to photocurrent. This study suggests that CdTe nanoparticles are very prospective materials for optoelectronics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.84-87
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• 2003

HgTe quantum dots(QDs) were synthesized in aqueous solution by colloidal method. The absorption and photoluminescence(PL) spectrum of the synthesized HgTe QDs revealed the strong exitonic peak in the IR region. And the photocurrent measurement of colloidal QDs are performed using IR light source. The lineshape of the wavelength dependent intensity of photocurrent was very similar to the absorption spectrum, indicating the charges generated by the absorption of photons give direct contribution to photocurrent. The channels of dark current are supposed $H_2O$ containing in thiol by the remarkable drop of current at the state of vacuum. It was thought that the proper passivation layer on the top of HgTe film reduce the dark current and the adequate choice of capping material improves the efficiency of the photocurrent in the HgTe QDs. This study suggests that HgTe QDs are very prospective materials for optoelectronics including photodetectors in the IR range.