• Journal of KIISE:Databases
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• v.28 no.3
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• pp.315-323
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• 2001

The concept of vertical partitioning has been discussed so far in an objective of improving the performance of query execution and system throughput. It can be applied to the areas where the match between data and queries affects performance, which includes partitioning of individual files in centralized environments, data distribution in distributed databases, dividing data among different levels of memory hierarchies, and so on. In general, a vertical partitioning algorithm should support n-ary partitioning as well as a globally optimal solution for the generation of all meaningful fragments. Most previous methods, however, have some limitations to support both of them efficiently. Because the vertical partitioning problem basically includes the fuzziness property, the proper management is required for the fuzziness problem. In this paper we propose an efficient vertical $\alpha$-partitioning algorithm which is based on the fuzzy theory. The method can not only generate all meaningful fragments but also support n-ary partitioning without any complex mathematical computations.

• Journal of Korean Library and Information Science Society
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• v.22
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• pp.27-59
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• 1995

The present writers have raised some basic questions related to writing. Do the theses produced in the library and information science field tell our story\ulcorner Are they field-oriented\ulcorner Are they easy to be read and to be a n.0, pplied by the librarians\ulcorner Problems in writing include research theme, research method and writing style. The present writers have a n.0, pplied phenomenological a n.0, pproach to these problems, using the observation of 'Co-workers Team' and interpretation of the 'Term Paper Collection'(vol.1-vol.5). Co-workers Team members consist of professors and graduate students in the Department of Library, Archives and Information Studies of the Pusan National University. We have made some proposals in this paper: First, we should not talk about American story. We should talk about our own story, and go back to basic themes. This proposal is related to the innovation of research theme. Second, qualitative research method should be introduced extensively in library and information science. Third, the strict 'thesis-oriented' and 'text-oriented' writing style should be overcome. The prevalent writing style in our field is so uniform that they are not capable of describing the intricate problems like "our living library".ary".uot;.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.4
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• pp.338-347
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• 1989

In this paper, the digital frequency synthesizer with the clock ccunting method is designed and implemented to increase the performace of the digital frequency synthesizer with pahse accumulating method which was developed before. Unlike an phase accumulating method, clock countind method is supplied a continually changeable clock frequency with PLL(Phase Locked Loop) and allocated a fixed phase step with N-ary counter. Form the experimenta results, it is confirmed that any periodic distorition phenomena are disappeared, and truncation harmonics are more reduced. But the output bandwidths are decreased in inverse proportion to the counter counting number and the circuits are somewhat complex than phase accumulating method.

• Journal of the Korean Vacuum Society
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• v.5 no.3
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• pp.245-250
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• 1996

$Y_2O_3$ thin film on si(100) was successfully grown by ionized cluster beam(ICBD) technique at substrate temperature of around $500^{\circ}C$ and pressure of ~$10^{-5}$Torr.To prevent the oxidation of Si substrae, a very thin yttrium layer was deposited on Si before reactive depositing of oxygen and yttrium source. In asdeposited stage, b.c.c and h.c.p strucutres of $Y_2O_3$ were observed from S-ary analysis. From the observation of spots and ring patterns in selected area diffractin(SAD) patterns. crystallane formation and growth could be proceeded during the deposition. $Y_2O_3$/mixed layer/$SiO_2=170\AA/50\AA/10\AA$ structure were verified by high resolution transmition electron imcroscopy(HRTEM) image, and the formation of amorphous layer of SiO2 was discussed . Electricla charateristics of the film were also investigated . In as-deposited Pt/$Y_2O_3$/Si sturcuture, leakage current was less than $10^{-6}$A/$\textrm{cm}^2$ at 7MV/cm strength.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.442-450
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• 1994

In this paper, the tracking of SFH/MFSK signals by using a paeallel correlator and a bank of BPF which is implemented by DFT recursively is studied. During symbol period, M-ary signal`s spectrum is analyzed by the step of n multiple of sampling period. The bank of BPF output which is stored for hop duration input to the parallel correlator. The time difference of the receiver and the transmitter is corrected by using sampling position and correlation time at which the largest output of correlator is generated. Syncronization signal detection rate and distribution of the largest output of correlator are evaluated by computer simulation in HF channel evironments for the performance analysis of proposed tracking method.