• The Journal of the Acoustical Society of Korea
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• v.18 no.1
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• pp.16-24
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• 1999

Design of SAW ladder filters has been performed by a rather trial and error method, that is, by modifying the design variables step by step until designed performance of the filter satisfies given specifications. In this work, optimal design method has been developed that automatically determines the detailed pattern of the SAW ladder filter to meet the specification once desired performance is given. As a first step for the development, the analysis tool for the SAW ladder filter has been produced by means of the Smith equivalent circuit analysis technique, and its validity has been verified through comparison of its calculation result with experimental data. With the analysis tool, we have investigated the performance variation of the filter with the change of its design factors, and the result has led to the optimal design algorithm. Validity and efficiency of the algorithm has been checked through test design of several SAW ladder filter samples on the market.

• Journal of Power Electronics
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• v.13 no.5
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• pp.829-840
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• 2013

The modified sinusoidal pulse-width modulation (SPWM) is one of the PWM techniques used in three-phase AC-DC buck converters. The modified SPWM works without the current sensor (the converter is current sensorless), improves production of sinusoidal AC current, enables obtainment of near-unity power factor, and controls output voltage through modulation gain (ranging from 0 to 1). The main problem of the modified SPWM is the huge starting current and voltage (during transient) that results from a large step change from the reference voltage. When the load changes, the output voltage significantly drops (through switching losses and non-ideal converter elements). The single-input single-output (SISO) approach with minor-loop voltage feedback controller presented here overcomes this problem. This approach is created on a theoretical linear model and verified by discrete-model simulation on MATLAB/Simulink. The capability and effectiveness of the SISO approach in compensating start-up current/voltage and in achieving zero steady-state error were tested for transient cases with step-changed load and step-changed reference voltage for linear and non-linear loads. Tests were done to analyze the transient performance against various controller gains. An experiment prototype was also developed for verification.

• Journal of Korean Critical Care Nursing
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• v.7 no.1
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• pp.1-10
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• 2014

Purpose: The purpose of this study was developing a nasogastric tube feeding algorithm to prevent aspiration pneumonia. Methods: The algorithm was developed through a methodological design. First, a pilot study was performed to determine the incidence of pneumonia. The second step was development of a preliminary algorithm through a literature review and collection of nurse opinions. The third step was to establish content validity using a panel of 12 experts. The fourth step was revision of the algorithm. Next, 20 intensive care unit nurses applied the revised algorithm for six months to their actual treatment, and the practical feasibility was verified after that. Results: In the patients for whom this algorithm was applied, no cases of pneumonia occurred. The algorithm that was developed by the present author was suitable for clinical application. Conclusion: The effect and practical feasibility of the algorithm was tested with a few patients in this study. The effect of this algorithm should be examined by applying it to more patients on an ongoing basis.

• Journal of the Korea Safety Management & Science
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• v.7 no.1
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• pp.101-115
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• 2005

This study deals with the procedure of safety improvement, productivity increase ,and tact-time reduction through setting up the system about preventive maintenance. Actually, it is hard to establish and carry out preventive maintenance, even though we recognize the importance of the system concerning time, cost, labor, and so forth. In this study in the viewpoint of cost we are for achieving maximum efficiency by change and reduction of planning process adapted to the special work group. At first we briefly will mention the kind ,the necessity ,and the concept of preventive maintenance ,and then divide the equipment used in the assembly line into the two whether it is necessary or not by way of estimating the breakdown loss ,comparing with general establishment of preventive maintenance and modifying it to the case. At the second step we will establish the operation system of plan management related to production and quality in the special case. Check period and category will be set by dividing the assembly equipment into LCL and Focus in the third step. The forth step will contain the operation procedure in detail. And then we must make check and repair record periodically. Finally, on the basis of the record the selection of checking of significance will be conducted. This results in safety improvement, tact time reduction, and productivity improvement.

• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.131-141
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• 2004

This study deals with the procedure of safety improvement, productivity increase, and tact-time reduction through setting up the system about preventive maintenance. Actually, it is hard to establish and carry out preventive maintenance, even though we recognize the importance of the system concerning time, cost, labor, and so forth. In this study in the viewpoint of cost we are for achieving maximum efficiency by change and reduction of planning process adapted to the special work group. At first we briefly will mention the kind, the necessity, and the concept of preventive maintenance, and then divide the equipment used in the assembly line into the two whether it is necessary or not by way of estimating the breakdown loss, comparing with general establishment of preventive maintenance and modifying it to the case. At the second step we will establish the operation system of plan management related to production and quality in the special case. Check period and category will be set by dividing the assembly equipment into LCL and Focus in the third step. The forth step will contain the operation procedure in detail. And then we must make check and repair record periodically. Finally, on the basis of the record the selection of checking of significance will be conducted. This results in safety improvement, tact time reduction, and productivity improvement.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2058-2065
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• 2010

This paper presents the sensor location and step estimation algorithm for personal navigation system (PNS). PNS has the disadvantage in that the position of the sensor must be fixed on a human body. Three-axis acceleration sensor is used to solve the disadvantage and to consider the real situation. We simplify the measurement data by using the band pass filter, witch It has the advantage in the detection of characteristic point. Through the detected characteristic points, it is possible to setup the parameter for the pattern detection. Depending on the sensor location, the parameters have the different type of noise covariance. Particularly, when the position of the sensor is changed, the impulse noise shows up. Considering the noise, we apply the recursive least square algorithm using the variable forgetting factors, which can classify the sensor location based on the estimated parameters. We performed the experiment for the verification of the proposed algorithm in the various environments. Through the experimental results, the effectiveness of the proposed method is verified.

• Journal of the Korean institute of surface engineering
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• v.53 no.5
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• pp.257-264
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• 2020

Anodization of Fe and Fe alloys is one of the most promising techniques to obtain iron oxide films applying to the various electrochemical devices due to their electrochemical catalytic properties. In this study, we investigate on the preparation of anodic iron oxide composite incorporated with WO₃ through a single-step anodization of stainless steel type-304 (STS304) as a substrate. The effects of applied voltage and tungsten precursor on the structural characteristics of iron oxide composite with different amount of incorporated WO₃ were observed. It is demonstrated that when the voltage of 60 V applied with 20 mM of Na₂WO₄ as a precursor, anodic iron oxide composite with a large pore diameter and a thick oxide length in which WO₃ is uniformly incorporated is obtained.

• International journal of advanced smart convergence
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• v.10 no.3
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• pp.131-142
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• 2021

Recently, there has been an active service that provides customized news to news subscribers. In this study, we intend to design a customized news service system through Deep Learning-based Social Network Service (SNS) activity analysis, applying real news and avoiding fake news. In other words, the core of this study is the study of delivery methods and delivery devices to provide customized news services based on analysis of users, SNS activities. First of all, this research method consists of a total of five steps. In the first stage, social network service site access records are received from user terminals, and in the second stage, SNS sites are searched based on SNS site access records received to obtain user profile information and user SNS activity information. In step 3, the user's propensity is analyzed based on user profile information and SNS activity information, and in step 4, user-tailored news is selected through news search based on user propensity analysis results. Finally, in step 5, custom news is sent to the user terminal. This study will be of great help to news service providers to increase the number of news subscribers.

• Journal of Korean Society of Rural Planning
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• v.19 no.2
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• pp.193-202
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• 2013

This study aims at suggesting some measures to establish rural community development information system through ISP. A future model for rural community development information system was established by applying such 3-step ISP methodology as environment analysis, current status(AS-IS) analysis, future(To-Be) directions. As a result, with the vision of realizing comprehensive information service for rural development projects, rural development information system has established such goals as the assistance of project decision making through preparing rural development project data management system and acquiring evaluation efficiency, the preparation of spatial information utilization system, the utilization of objective GIS-based information through the increase of data management efficiency, the community activation and participatory rural development through rural spatial information portal service. In order to attain the goals, four strategical subject matters were derived. They are: 1) one-stop service subject matter for data management including pilot DB building for rural development projects, 2) rural information GIS service strengthening subject matter including DB building for rural development, O&M measures, 3) step-by-step DB building subject matter including the sharing of integrated information system for rural development, and 4) core value increase subject matter of spatial information data including the building of active service delivery system.

• Journal of the Korean Data and Information Science Society
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• v.20 no.3
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• pp.551-562
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• 2009

In this paper, I would present a using method for The Fishing Operation Information(FOI) of National Federation of Fisheries Cooperatives(NFFC) through the availabilities analysis and put out the similarities by the section of the sea through classifying characteristics of fishing patterns by their locations. As a result, although the catch of FOI is nothing more than 33% level to National Fishery Production Statistics(NFPS), FOI data is useful in understanding the patterns of fishing operation by the location because both patterns and correlation were very similar in the usability analysis, comparing the FOI data with NFPS. So I classified optimal clusters for catch, the number of fishing days and the number of fishing vessels through 2 step cluster analysis by the big marine zone and divided fishing patterns.