• Restorative Dentistry and Endodontics
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• 제38권4호
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• pp.222-226
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• 2013

Objectives: The aim of this study was to assess the influence of operator experience level on the lifespan of the WaveOne Primary file (Dentsply Maillefer, Ballaigues, Switzerland) in extracted teeth. Materials and Methods: Moderately curved canals of extracted maxillary and mandibular molars were randomly distributed into 2 groups: experienced and inexperienced operators. Ten files were allocated to each group (n = 10). Each canal was prepared until the working length was reached, and the same file was used to prepare additional canals until it separated. The number of canals prepared before file separation was recorded. The fragment length of each file was measured, and the location of the fragment in the canal was determined. Data were statistically analysed using the independent 2-sample t-test. Results: The 2 operators prepared a total of 324 moderately curved canals of maxillary and mandibular molars. There was no significant intergroup difference in the mean number of canals prepared (p = 0.27). The average lifespan of the WaveOne Primary file was 17.1 and 15.3 canals, and the longest lifespan was 25 and 20 canals, when used by experienced and inexperienced operators, respectively. There were no statistically significant intergroup differences in separated fragment length and location. Conclusions: Within the limitations of this study, operator experience level appears to have no effect on the lifespan of the WaveOne Primary file in preparation of moderately curved canals. Single teeth with multiple canals can be prepared safely even by a novice operator by using a single file.

• 정보학연구
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• 제4권1호
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• pp.9-22
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• 2001

본 논문에서는 웹브라우저를 이용하여 로봇을 원격 제어한다. 4대의 독립된 PC를 사용하여 자각의 기능을 분리하고 상호 연동하는 구조로 PC를 연결하였다. 조작자가 시간과 장소에 제약받지 않고 웹브라우저를 이용하여 제어값을 입력하면 제어값은 웹 서버를 거쳐 데이터베이스에 저장된다. 로봇과 연결된 PC는 데이터베이스에서 1ms 간격으로 제어값을 입력받아 제어값의 변화가 있을 경우만 제어값의 변화량으로 로봇이 동작한다. 스텝모터를 이용하여 간단한 로봇을 제작하고 이를 웹 브라우저를 이용하여 실제 동작시킨다. 조작자가 원하는 제어값이 최종 수신단의 로봇에 제대로 전달되어 동작하는지 확인하고 웹브라우저를 이용한 로봇제어의 가능성을 확인하였다

• Journal of Magnetics
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• 제16권2호
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• pp.108-113
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• 2011

The electron spin resonance lineshape (ESRLS) function for the electron spin resonance linewidth (ESRLW) of $Cr^{3+}$ (S = 3/2) in ferroelectric lithium niobate single crystals doped with 0.05 wt% of Cr, is obtained by using the projection operator technique (POT), developed by Argyres and Sigel. The ESRLS function is calculated to be axially symmetric about the c - axis and analyzed by using the spin Hamiltonian $H_{SP}={\mu}_B(B{\cdot}{^\leftrightarrow_{g}}{\cdot}S)+S{\cdot}{^\leftrightarrow_{D}}{\cdot}S$ with the parameters g = 1.972 and D = $0.395\;cm^{-1}$. In the ca plane, the linewidths show a strong angular dependence, whereas in the ab plane, they are independent of the angle. This result implies that the resonance center has an axial symmetry along the c - axis. Further, from the temperature dependence of the linewidths that is shown, it can be seen that the linewidths increase as the temperature increases, at a frequency of v = 9.27GHz. This result implies that the scattering effect increases with increasing temperature. Thus, the POT is considered to be more convenient to explain the scattering mechanism as in the case of other optical resonant systems.

• ETRI Journal
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• 제26권6호
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• pp.665-668
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• 2004

The introduction of a mobile virtual network operator (MVNO) system is expected to increase consumer benefits, boost competition in the mobile market, utilize idle bandwidth, and expedite mobile-fixed line convergence and growth in the mobile Internet market. This research endeavors to study the optimal access charge for an MVNO system, which is expected to be introduced to the Korean mobile communications market. We found that the optimal access charge is higher in the interdependent model than in the independent model if demand for mobile phone service is based on a substitution relationship. We also found that the optimal access charge is higher than the marginal cost.

• Korean Journal of Mathematics
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• 제15권2호
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• pp.101-114
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• 2007

For an $m$ by $n$ nonnegative real matrix A, the maximal column rank of A is the maximal number of the columns of A which are linearly independent. In this paper, we analyze relationships between ranks and maximal column ranks of matrices over nonnegative reals. We also characterize the linear operators which preserve the maximal column rank of matrices over nonnegative reals.

• Journal of Microbiology and Biotechnology
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• 제4권3호
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• pp.176-182
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• 1994

The light-organ symbiont of pine cone fish, Vibrio fischeri, senses its presence in the host and responds to environmental changes by differentially expressing its symbiosis-related luminescence genes. The V. fischeri luminescence genes are activated by LuxR protein in the presence of an autoinducer. In an effort to elucidate the mechanism of regulation of luxR, a plasmid containing luxR was mutagenized in vitro with hydroxylamine and a luxR mutant plasmid was isolated by its ability to activate luminescence genes cloned in E. coli in the absence of the autoinducer. The specific base change identified by DNA sequencing was only single base transition at ＋78 from the transcriptional start of luxR. Based on a Western immunoblot analysis, the nucleotide change directed the synthesis of much higher level of LuxR protein without any amino acid substitutions. The results suggest that the region including the ＋78th base is presumably internal operator required for autorepression of luxR, and the increased cellular level of LuxR results in activation of luminescence genes by autoinducer independent fashion.

• 항공우주정책ㆍ법학회지
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• 제22권2호
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• pp.27-51
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• 2007

The cumulative result of the work by the ICAO Secretariat, the Secretariat Study Group and the Council Special Group on the Modernization of the Rome Convention of 1952 are two draft Conventions, namely: "Draft Convention on Compensation for Damage Caused by Aircraft to Third Parties, in case of Unlawful Interference", and "Draft Convention on Compensation for Damage Caused by Aircraft to Third Parties" The core provisions of the former draft Convention are as follows: The liability of the operator is strict, that is, without the necessity of proof of fault. It would be liable for damage sustained by third parties on condition only that the damage was caused by an aircraft in flight(Article 3). However, such liability is caped based on the weight of the aircraft(Article 4). It is envisaged to create an independent organization called the Supplementary Compensation Mechanism, with the principle purpose to pay compensation to persons suffering damage in the territory of a State Party, and to provide financial support(Article 8). Compensation shall be paid by the SCM to the extent that the total amount of damages exceeds the Article 4 limits(Article 19). The main issues on the farmer draft Convention are relating to breaking away from Montreal Convention 1999, no limits on individual claims but a global limitation on air carrier liability, insurance coverage, cap of operators' strict liability, and Supplementary Compensation Mechanism. The core provisions of the latter draft Convention are as follows: the liability of the operator is strict, up to a certain threshold tentatively set at 250,000 to 500,000 SDRs. Beyond that, the operator is liable for all damages unless it proves that such damage were not due to its negligence or that the damages were solely due to the negligence of another person(Article 3). The provisions relating to the SCM and compensation thereunder do not operate under this Convention, as the operator is potentially for the full amount of damages caused. The main issues on the latter draft Convention are relating to liability limit of operator, and definition of general risks. In conclusion, we urge ICAO to move forward expeditiously on the draft Convention to establish a third party liability and compensation system that can stand ready to protect both third party victims and the aviation industry before another 9/11-scale event occurs.

• 대한수학회지
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• 제32권3호
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• pp.541-551
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• 1995

The nonlinear Klein Gordon equation $$ (1) \frac{\partial t^2}{\partial^2 u} - \Delta u + V_u(u) = f $$ where $\Delta$ is the Laplacian operator in $R^d (d = 1, 2, 3), V_u(u)$ is the derivative of the "potential function" V, and f is a source term independent of the solution u, in various areas of mathematical physics.l physics.

• 대한수학회지
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• 제37권6호
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• pp.1031-1042
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• 2000

The equations prescribed in Ω⊂R(sup)n are called loaded, if they contain some operations of the traces of desired solution on manifolds (of dimension which is strongly less than n) from closure Ω. These equations result from approximations of nonlinear equations by linear ones, in the problems of optimal control when the control when the control actions depends on a part of independent variables, in investigations of the inverse problems and so on. In present work we study the nonlocal boundary value problems for first-order loaded differential operator equations. Criterion of unique solvability is established. We illustrate the obtained results by examples.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.533_534
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• 2009

본 논문에서는 수요반응(Demand Response) 프로그램 적용 시 각 소비자의 부하패턴 변화에 따른 계통운영자(Independent System Operator : ISO)의 총 발전비용 변화량을 Shapley Value를 이용하여 각 소비자가 총 발전비용 감소에 기여한 정도를 파악할 것이다. 또한 사례연구를 통하여 수요반응 프로그램에서의 각 부하패턴 변화 유형에 따른 총 발전비용 감소에 대한 기여도 및 Shapley Value 적용 전후의 결과를 비교 분석하였다.