• Proceedings of the KSR Conference
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• 2000.05a
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• pp.598-605
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• 2000

The design of a current collection system of high speed train requires the fundamental understandings fer the dynamic characteristics of a catenary system and pantograph. The stiffness of the catenary system of high speed train has the varying characteristics for the change of the contact point with a pantograph, since the supporting pole and hanger make the different boundary conditions for the updown stiffness of a trolley wire. The variation of stiffness results in Mathiue equation, which characterizes the stability of the system. However, the two terms variation of the stiffness due to span length and hanger distance cannot be solved analytically. In this paper, the stiffness variations are calculated, and the physical reasoning of linear model and one term Mathieu equation are reviewed. And the numerical analysis for the two term variation of the stiffness is done for the several design parameters of the pantograph.

• Journal of the Korean Society of Visualization
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• v.19 no.1
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• pp.62-67
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• 2021

Selective catalytic reduction(SCR) is an exhaust gas reduction device to remove nitro oxides (NOx). SCR operation of ship can be controlled through valves for minimizing economic loss from SCR. Valve in SCR-high pressure (HP) system is directly connected to engine exhaust and operates in high temperature and high pressure. Long-term thermal deformation induced by engine heat weakens the sealing of the valve, which can lead to unexpected failures during ship sailing. In order to prevent the unexpected failures due to long-term valve thermal deformation, a failure prediction system using autoregressive integrated moving average (ARIMA) was proposed. Based on the heating experiment, virtual data mimicking temperature range around the SCR-HP valve were produced. By detecting abnormal temperature rise and fall based on the short-term ARIMA prediction, an algorithm determines whether present temperature data is required for failure prediction. The signal processed by the data collection algorithm was interpolated for the failure prediction. By comparing mean average error (MAE) and root mean square error (RMSE), ARIMA model and suitable prediction instant were determined.

• Wind and Structures
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• v.31 no.1
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• pp.21-29
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• 2020

The wind field measurement of severe winds such as hurricanes (or typhoons), thunderstorm downbursts and other gales is important issue in wind engineering community, both for the construction and health monitoring of the wind-sensitive structures. Although several wireless data transmission systems have been available for the wind field measurement, most of them are not specially designed for the wind data measurement in structural wind engineering. Therefore, the field collection is still dominant in the field of structural wind engineering at present, especially for the measurement of the long-term and high-frequency wind speed data. In this study, for remote wind field measurement, a novel wireless long-term and high-frequency wind data acquisition system with the functions such as remote control and data compression is developed. The system structure and the collector are firstly presented. Subsequently, main functions of the collector are introduced. Also novel functions of the system and the comparison with existing systems are presented. Furthermore, the performance of this system is evaluated. In addition to as the wireless transmission for wind data and hardware integration for the collector, the developed system possesses a few novel features, such as the modification of wind data collection parameters by the remote control, the remarkable data compression before the data wireless transmission and monitoring the data collection by the cell phone application. It can be expected that this system would have wide applications in wind, meteorological and other communities.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1102-1114
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• 2002

An electret filter is composed of permanently charged electret fibers and is widely used in applications requiring high collection efficiency and low-pressure drop. In this work, the collection efficiency of the filter media used in manufacturing cabin air filters was investigated by using poly-disperse particles when submicron particles were loaded. Long-term experiments were conducted by applying two different charging states, which were spray electrification and charge equilibrium by bipolar ionization. In order to investigate the effect of particle loading in filter media, NaCl particles were generated from 0.1% and 1% solutions by an atomizer. Liquid DOS particles were used to evaluate the effect of liquid particles on the collection efficiency of an electret filter. The results show significant effect of charge amount and size distribution of loading particles on the collection performance of a filter media in submicron region. Smaller particles loaded in electret fibers cause a more rapid degradation in collection efficiency and have lower minimum efficiency with time. The pressure drop of a filter media do rarely increase when the collection efficiency decreases to the minimum value. For the larger particles charged by spray electrification, which have charge amounts more than that of Boltzmann equilibrium charge distribution, the pressure drop of a filter media slowly increases in comparison with that of equilibrium charged particles. For DOS particles it is shown that the charging level of an electret filter severely decreases and the collection efficiency is below 10% in some particle size range.

• Kyungpook Mathematical Journal
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• v.59 no.4
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• pp.617-629
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• 2019

A term is called linear if each variable which occurs in the term, occurs only once. A hypersubstitution is said to be linear if it maps any operation symbol to a linear term of the same arity. Linear hypersubstitutions have some importance in Theoretical Computer Science since they preserve recognizability [7]. We show that the collection of all linear hypersubstitutions forms a monoid. Linear hypersubstitutions are used to define linear hyperidentities. The set of all linear term operations of a given algebra forms with respect to certain superposition operations a function algebra. Hypersubstitutions define endomorphisms on this function algebra.

• Research in Community and Public Health Nursing
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• v.31 no.3
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• pp.375-383
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• 2020

Purpose: The purpose of this study was to investigate factors influencing care workers' intention of hand hygiene implementation in long-term care hospitals. Methods: A total of 180 care workers working at long-term care hospitals were recruited. Data collection was done from July 22 to September 7, 2018. Results: The significant TPB variables influencing the intention of hand hygiene implementation were perceived behavior control (β=.41, p<.001), normative belief (β=.28, p<.001) and attitude toward behavior (β=.15, p=.014). These factors explain 39% of care workers' intension of implementing hand hygiene in long-term care hospitals. Conclusion: In order to strengthen the commitment of hand hygiene, it is necessary to have a positive attitude toward hand hygiene by eliminating the obstacles to hand hygiene.

• Journal of the Korean Society for information Management
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• v.1 no.1
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• pp.43-62
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• 1984

The present study has two main objectives. The first objective is to devise a new term weighting technique which can be used to weight the significance value of each word stem in a test collection of documents on the subject of "enteral hyperalimentation." The next objective is to evaluate retrieval performance of proposed term weighting technique, together with four other term weighting techniques, by conducting a set of experiments. The experimental results have shown that the performance of Sparck Jones's inverse document frequency weighting and the proposed term significance weighting techniques produced better recall and precision ratios than the other three complex weighting techniques.

• Journal of Information Management
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• v.34 no.4
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• pp.85-107
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• 2003

This paper describes the results of a usage analysis on the scientific and technical journals in order to optimize the collection development at KISTI. By comparing usage data for the journals from 1997/2002, this study identifies the short-term changes in journal use, which were shown on the subject field, language, publication country, SCI journal and electronic journal. The changing of journal use has important implications for collection development strategy in sci-tech libraries.

• Journal of the Korea Society of Computer and Information
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• v.25 no.4
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• pp.141-148
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• 2020

Automatic term extraction is to recognize domain-specific terms given a collection of domain-specific text. Previous term extraction methods operate effectively in unsupervised manners which include extracting candidate terms, and assigning importance scores to candidate terms. Regarding the calculation of term importance scores, the study focuses on utilizing sets of inner and outer terms of a candidate term. For a candidate term, its inner terms are shorter terms which belong to the candidate term as components, and its outer terms are longer terms which include the candidate term as their component. This work presents various functions that compute, for a candidate term, term strength from either set of its inner or outer terms. In addition, a scoring method of a term importance is devised based on C-value score and the term strength values obtained from the sets of inner and outer terms. Experimental evaluations using GENIA and ACL RD-TEC 2.0 datasets compare and analyze the effectiveness of the proposed term extraction methods for English. The proposed method performed better than the baseline method by up to 1% and 3% respectively for GENIA and ACL datasets.

• Journal of the Korean Society for Library and Information Science
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• v.47 no.4
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• pp.125-142
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• 2013

A collection development policy is the library's master plan that provides library's long/short-term plans. It also informs the community of the library's commitment in collection development. However, in Korea, libraries which maintain such a policy are not yet to be easily found. Furthermore, due to increasing importance of electronic resources, libraries are gradually required to have electronic resource management policy that reflects a change in the information environment. The purpose of this study is to suggest a model electronic resource management policy in academic libraries. It derived and verified more than thirty preliminary elements from literature and case studies. The elements were modified and supplemented, and as a result, the selection criteria gained the highest marks. The findings can be applied for selecting the elements of digital collection development policy in the university library and reorganizing them so as to meet its peculiarities. This study, finally, presents a model that includes a guideline for the university library which will establish digital collection development policy.