• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.8-13
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• 2011

A percentage current differential relay is widely used for transformer protection. Because many percentage current differential relays recently use modified methods instead of conventional methods for deciding the operating characteristics of the large current region, in this paper, the operating region of a percentage current differential relay is analyzed in input-output current domain instead of operating-restraint current domain. An effective method to set the operating region when a CT is saturated is proposed with a series of investigations comparing a conventional method with the proposed modified method. The performance of the proposed method is evaluated for internal and external faults of a power transformer having the voltage rating of 345/154kV. EMTP-RV is used for the relaying data collection.

• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.4
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• pp.61-70
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• 1982

The hydrodynamic effects on resistance and propulsive performance were studied by using the data from model test and full scale speed trials. A series of model tests on 3 geosims for a 60,000 DWT Bulk Carrier was conducted at KIMM's Ship Experimental Towing Tank and the results analyzed by 1978 ITTC Performance Prediction Method show the correlation between 3 geosim models. Also powering data of full scale speed trials were analyzed by the newly developed computer program and the correlation analysis between ship and model was studied.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1996.09a
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• pp.117-124
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• 1996

When navigating in or near an area of restricted visibility it is necessary to be heard the whistle bell and/or the siren of lighthouses or ships at times. Even though we can get the brief informations about the property of sound the direction and range of a sound radiator it is not easy to get the accurate informations for decision making. generally the audio frequency is known as 16-20,000Hz but the earshot is shorten and discrimination of sound is more difficult when there is some noise. The sound pressure is 60dB at the moment when human speaks 1 meter away. Usually the noise pressure in a silent room is 40dB and 60dB on the quiet street. In this study we suggest the basic algorithm to trace the direction and range of the source radiator using the signal received through not a physical sense but the microphone sensors and a series of signal of signal processing.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.60-62
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• 2018

본 논문에서는 리눅스에서 제공하는 성능 분석 도구들을 활용하여 사용자가 원하는 모니터링 매트릭을 동적으로 등록하고 모니터링 할 수 있는 확장 가능한 하둡 응용 모니터링 서비스의 시계열 데이터 관리 방안을 다룬다. 본 논문에서는 이를 위해서 시계열 데이터를 위한 관계형 데이터베이스인 TimeScaleDB를 사용하였으며 동적으로 변경가능한 모니터링 메트릭 데이터가 하이퍼테이블의 관리를 통해서 구조화된 밀집 데이터 형태로 효율적으로 관리될 수 있음을 제시하였다.

• Kyungpook Mathematical Journal
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• v.60 no.4
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• pp.767-779
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• 2020

This paper primarily discusses and proves the Hyers-Ulam stability of three types of polynomial equations: xn+a1x+a0 = 0, anxn+⋯+a1x+a0 = 0, and the infinite series equation: ${\sum\limits_{i=0}^{\infty}}\;a_ix^i=0$, in dislocated quasi-metric spaces under certain conditions by constructing contraction mappings and using fixed-point methods. We present an example to illustrate that the Hyers-Ulam stability of polynomial equations in dislocated quasi-metric spaces do not work when the constant term is not equal to zero.

• Bulletin of the Korean Chemical Society
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• v.16 no.3
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• pp.261-264
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• 1995

A series of samples of the Nd1-x(Ba0.40Mg0.60)1+xFeO4-y (x=0.00, 0.10, 0.20, and 0.30) system has been synthesized at 1450 ℃ under an atmospheric air pressure. The x-ray powder diffraction analysis of the solid solutions assigns the structure of all the compositions to orthorhombic system. Mohr salt analysis shows that τ and y values increase with x value and nonstoichiometric chemical formulas of the system can be formulated from the x, τ, and y values. Oxygen vacancies are distributed along c-axis in the perovskite layer. The magnetic ordering temperature remains unchanged with x value. Electrical conductivity and activation energy depend only on the mixed valence state of Fe ion. Conduction mechanism can be suggested as the hopping of electron between eg orbitals of Fe3+ and Fe4+ ions through Fe3+-O-Fe4+ bonds. Magnetic susceptibility and electrical conductivity are discussed with the nonstoichiometric chemical formulas.

• Korean Journal of Veterinary Research
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• v.32 no.3
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• pp.309-319
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• 1992

This study was undertaken to establish the sequence of development of ages and its time of the fetal endochondral ossification in the scapula of the Korean native cattle. This study was also designed to confirm through histological observation the earliest stages of both chondrification and ossification. Thirty eight scapulae, a series of embryos and fetuses from the pregnant Korean native cattle ranging from 11 to 110mm in crown-rump (C-R) length, were used. The following results were obtained. The ossification center was observed in the supra- and infra- spinous fossa in the 5th group (CRL 51-60mm), that was markedly ossified in the 6th group (CRL 61~70mm) by Alizarin red S stain. The chondrogenic center of scapula was observed in the 1st group (CRL 11~20mm). The primary ossification center was presented in the 4th group (CRL 41~50mm). In the 5th group(CRL 51~60mm), the endochondral ossification progressed actively. Alcianophility was markedly increased in the interterritorial matrix in the 3rd group (CRL 31~40mm. However this reaction was markedly decreased in the interterritorial matrix the adjacent portion to the marrow cavity and trabecula in the 5th group (CRL 51~60mm).

• Journal of Industrial Technology
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• v.21 no.A
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• pp.329-336
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• 2001

In this study, a series of fatigue tests are carried out in order to estimate quantitatively the characteristics of fatigue crack growth rate for high strength steels of SM570, POSTEN60, and POSTEN80 steel, that is, the influence on fatigue crack growth rate according to the welding line, the characteristics of fatigue crack growth according to the welding method and the kinds of steel, and the characteristics of fatigue crack growth for base metal, heat affected zone and weld metal. From the test results, in case that the notch if parallel to welding line, it knows that the retardations of fatigue crack growth rate in crack tip at early stage increase remarkably than in case that the notch is perpendicular to welding line due to compressive residual stress. And the characteristics of fatigue crack growth rate according to welding method are that the dispersion of fatigue crack growth rate in case of FCAW method is smaller than that of SAW method. Also, it knows that the fatigue crack growth rate converges in high stress intensity factor range.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.114-118
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• 2011

Dye-Sensitized Solar Cells(DSSCs) consist of a titanium dioxide($TiO_2$) nano film of the photo electrode, dye molecules on the surface of the $TiO_2$ film, an electrolyte layer and a counter electrode. But two transparent conductive oxide(TCO) substrates are estimated to be about 60[%] of the total cost of the DSSCs. Currently novel TCO-less structures have been investigated in order to reduce the cost. In this study, we suggested a TCO-less DSSCs which has titanium double layer electrodes. Titanium double layer electrodes are formed by electron-beam evaporation method. Analytical instruments such as electrochemical impedance spectroscopy, scanning electron microscope were used to evaluate the TCO-less DSSCs. As a result, the proposed structure decreases energy conversion efficiency and short-circuit current density compared with the conventional DSSCs structure with FTO glass, while internal series impedance of TCO-less DSSCs using titanium double layer electrodes decreases by 27[%]. Consequently, the fill factor is improved by 28[%] more than that of the conventional structure.

• Journal of the Korean Society for Library and Information Science
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• v.46 no.2
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• pp.5-28
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• 2012

Great Books of the Western World(GBWW) is a series of books published in 1952 by Encyclopaedia Britannica to present the famous works in 54 volumes. The series is now in its second edition and contains 60 volumes. A syntopicon compiled by M. Adler is a two-volume index, published as volumes 2 and 3 of GBWW. The syntopicon was coined specifically for this undertaking, which means a collection of topics. Syntopicon lists, under each idea, is where every occurrence of the concept can be located in the collection's famous works. This study aims to analyze the structure and utility of topic index, syntopicon in GBWW. The syntopicon consists of 102 chapters on the 102 ideas. Each chapter is broken down into five distinct sections: the introduction, an outline of topics, references, cross-references, and additional readings. The syntopicon can serve as a reference book, as a selection tool of book to be read, instrument of liberal education, instrument of discovery and research, syntopical reading of other reading material, development tool of convergent education, and analysis tool of works.