• Journal of the Korean Home Economics Association
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• v.43 no.5 s.207
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• pp.149-161
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• 2005

The purpose of this study was to use content analysis for the periodic trend of newspapers regarding disabled children in the 1960s (1961, 1962), 1980s (1981, 1982) and 2000s (2001,2002), at intervals of 20 years with the Year of World Disabled People (1981) as the basic point. The results showed that the number of articles was increasing. Topics such as 'medical rehabilitation'. or 'educational environment' were emphasized in the 1960s, 'the environment for social awareness' in the 1980s, and 'educational environment' and 'environment for social awareness' in the 2000s. As for the types of disability, general disability, physical disability, sight impairment, hearing impairment, and other disabilities were covered, but the range of coverage was not comprehensive. The framing pattern followed the trend of the times, with marginal flaming on the decline and diverse framing on the rise. The tones of the articles were positive on the whole.

• Honam Mathematical Journal
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• v.31 no.1
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• pp.75-85
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• 2009

We show the existence of the nontrivial periodic solution for a class of the system of the nonlinear suspension bridge equations with Dirichlet boundary condition and periodic condition by critical point theory and linking arguments. We investigate the geometry of the sublevel sets of the corresponding functional of the system, the topology of the sublevel sets and linking construction between two sublevel sets. Since the functional is strongly indefinite, we use the linking theorem for the strongly indefinite functional and the notion of the suitable version of the Palais-Smale condition.

• Journal of Power Electronics
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• v.14 no.3
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• pp.572-579
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• 2014

As a non-linear time variant system, the four-quadrant line converter of an electric multiple unit (EMU) was expressed by linear time periodic functions near an operating point and modeled by a steady-state harmonic domain matrix. The components were then combined according to the circuit connection and relations of the feedback control loops to form a complete converter model. The proposed modeling method allows the study of the amplitude of harmonic impedances to explore harmonic coupling. Moreover, the proposed method helps provide a better design for the converter controllers, as well as solves the problem in coordination operation between the EMUs and the AC supply. On-site data from an actual $CRH_2$ high-speed train were used to validate the modeling principles presented in the paper.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.115-120
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• 2005

This paper introduces models for preventive maintenance policies and considers periodic preventive maintenance policy with minimal repair when the failure of system occurs. It is assumed that minimal repairs do not change the failure rate of the system. The failure rate under prevention maintenance received an effect by a previously prevention maintenance and the slope of failure rate increases the model where it considered. Also the start point of failure rate under prevention maintenance considers the degradation of system and that it increases quotient, it assumed. Per unit time it bought an expectation cost from under this prevention maintenance policy. We obtain the optimal period time and the number for the periodic preventive maintenance by using Nakagawa's Algorithm, which minimizes the expected cost rate per unit time. Finally, it suppose that the failure time of a system has a Weibull distribution as an example and we obtain an expected cost rate per unit time the optimal period time and the number when cost of replacement and cost of minimal repair change.

• Advances in aircraft and spacecraft science
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• v.5 no.1
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• pp.1-19
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• 2018

The present work shows many aspects concerning the use of a numerical wave-based methodology for the computation of the structural response of periodic structures, focusing on cylinders. Taking into account the periodicity of the system, the Bloch-Floquet theorem can be applied leading to an eigenvalue problem, whose solutions are the waves propagation constants and wavemodes of the periodic structure. Two different approaches are presented, instead, for computing the forced response of stiffened structures. The first one, dealing with a Wave Finite Element (WFE) methodology, proved to drastically reduce the problem size in terms of degrees of freedom, with respect to more mature techniques such as the classic FEM. The other approach presented enables the use of the previous technique even when the whole structure can not be considered as periodic. This is the case when two waveguides are connected through one or more joints and/or different waveguides are connected each other. Any approach presented can deal with deterministic excitations and responses in any point. The results show a good agreement with FEM full models. The drastic reduction of DoF (degrees of freedom) is evident, even more when the number of repetitive substructures is high and the substructures itself is modelled in order to get the lowest number of DoF at the boundaries.

• The Transactions of the Korea Information Processing Society
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• v.7 no.7
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• pp.2229-2237
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• 2000

This paper intends to improve the problems of the slack stealing algorithm scheduling for periodic tasks with fixed priority and aperiodic tasks which occur dynamically. The Slack stealing algorithm reduces unnecessary waiting time by making the service possible immediately when the slack stealing server gives suitable priority to aperiodic tasks according to the status of aperiodic tasks arrivals at runtime. But no performs the slack stealing, we must calculate execution time of periodic tasks till the point of random. And, execution time of periodic tasks is being repeatedly every hours while the slack algorithm is applied. We show time complexity hen is used as to O(n) if the nubmer of tasks which is applied to the calculation is n. In this appear, due to stored in tables slack times and the execution times of the scheduled periodic tasks, the complexity of aperiodic tasks which is occurring dynamically reduced to O(log n) and improves the responses times. We prove the algorithm proposed in this paper through the simulation.

• Korean Journal of Remote Sensing
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• v.35 no.4
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• pp.573-587
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• 2019

A multi-temporal approach using remotely sensed time series data obtained over multiple years is a very useful method for monitoring land covers and land-cover changes. While spectral-based methods at any particular time limits the application utility due to instability of the quality of data obtained at that time, the approach based on the temporal profile can produce more accurate results since data is analyzed from a long-term perspective rather than on one point in time. In this study, a multi-temporal approach applying a multi-periodic harmonic model is proposed for classification of remotely sensed data. A harmonic model characterizes the seasonal variation of a time series by four parameters: average level, frequency, phase, and amplitude. The availability of high-quality data is very important for multi-temporal analysis.An satellite image usually have many unobserved data and bad-quality data due to the influence of observation environment and sensing system, which impede the analysis and might possibly produce inaccurate results. Harmonic analysis is also very useful for real-time data reconstruction. Multi-periodic harmonic model is applied to the reconstructed data to classify land covers and monitor land-cover change by tracking the temporal profiles. The proposed method is tested with the MODIS and GOCI NDVI time series over the Korean Peninsula for 5 years from 2012 to 2016. The results show that the multi-periodic harmonic model has a great potential for classification of land-cover types and monitoring of land-cover changes through characterizing annual temporal dynamics.

• The Journal of Engineering Research
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• v.8 no.1
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• pp.107-118
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• 2006

The difficulties to build a 3-dimensional water quality model for the coastal water quality improvement and the environmental recovery estimation are the lack of periodic observed data and the many problems to observe continuously. I observed the rainfall and non-point pollutants outflow patterns in Jinhae-Masan basin as mid-step researches for the water quality simulation and management method development in a coastal area. I applied Landsat image system and Geographic Information System to analyze the runoff and non-point pollutants outflow patterns. A water quality simulation model (SWMM) applied to Jinhae-Masan basin with results of the land use distribution, non-point pollution loads, and watershed informations from GIS(IDRISI used). I proposed some improved survey and GIS application methods reflect upon the pollutant characteristics from the observed non-point pollutant outflow patterns.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.85-91
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• 1996

The drilling experiment of carbon fiber epoxy composite material with WC-drill has been done under the various cutting condition in order to minimize the problems occured in the material when being drilled. It has been comfirmed by a frequencyanalysis of the cutting force signals that the variation of cutting force resulted from the periodic variation of the angle between the rotating drill and the stacking angle of the carbon fiber. The drilling experiment has been done with several drills having different point angles and the drilling characteristics, like the effects such that change in the point angle influences the cutting force and the external surface condition, was evaluated.

• Research in Community and Public Health Nursing
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• v.4 no.2
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• pp.139-145
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• 1993

The purpose of this study was to identify the degree and the relationship of the Knowledge, Attitude and Practice of industrial health care services of workers. This information will provide useful data for an effective industrial health care service. The was collected from 600 data employees in Kwang-ju city & Chonnam province. The data was gathered by questionnaire from Dec 20, 1992 to Jan 20, 1993. The questionnaire was developed by the Academic Affairs of Community Health Nursing Academy. Data was analyzed by using the statistical computer package, SPSS to manipulate the data along with percentages, means, standard deviations, modes, t-test and ANOVA. The results in this study were summarized as follows: 1. General characteristics of workers: Distributions of workers was laborer(76.2%). in the 25-34 age group(50.2%), married(63.3%), males comprised(77.5%), the educational level with the highest percentage was high school graduates (71.1%), with a monthly income of 300-700 thousand won(43.8%), and has been working in the present career over seven years (31.5%). 2. The Knowledge, Attitude and Practice levels of employees about industrial health care services The levels were measured according to a five point scale. The total mean score of knowledge was 2.92 points out of 4. The following are the scores of Knowledge of special medical examination and location of industrial clinic(3.48), periodic medical examination (3.18), occupational disease(3.08), personal protective equipment (2.92), and health education(1.37). The total mean score of Attitude was 2.77 point out of 4. The following are the scores of Attitude in order of working environment (3.35), necessity of periodic medical examination and health education(3.15), the worker's perception influence on the working environment to health was high(3.11). But, the level of satisfaction in the content of periodic medical examination was low(2.19). The total mean score of Practice was 2.70 points out of 4. The scores of Practice in order were, practice of periodic medical examination(3.70), utilization of industrial clinic(2.92), and to participate in health education(1.47). 3. The relationship of general characteristics to Knowledge, Attitude, and Practice of workers: Knowledge had a significant difference by sex (P<.01), marital status(P<.01), education level (P<.05) and monthly income(P<.01). Attitude was significantly different with sex(P<.05) and Practice was significantly related to monthly income (P<.01).