• Proceedings of the Korean Statistical Society Conference
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• 2001.11a
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• pp.185-189
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• 2001

In this paper, we consider the problem of testing for parameter changes in time series models based on a sequential test. Although the test procedure is well-established for the mean and variance change, a general parameter case has not been discussed in the literature. Therefore, we develop a sequential test for parameter changes in a more general framework.

• Journal of Power Electronics
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• v.11 no.3
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• pp.304-310
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• 2011

The power series approximation method is proposed for real time implementations of a discrete flux observer. The proposed method improves the performance of the discrete flux observer in the case of a low sampling rate and high speed range, where the simple discrete flux observer converted by the Euler method cannot estimate the actual flux precisely. The performance of discrete flux observers with different orders of approximation is compared to find out the proper order of approximation. The validity of the proposed method is verified through simulation and experiment.

• Smart Structures and Systems
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• v.9 no.6
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• pp.473-487
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• 2012

GPS has become an established technique in structural health monitoring. This paper presents the application of an on-line GPS RTK system on the Zhujiang Huangpu Bridge (China) for monitoring bridge deck and towers movements. In this study, both the form and functions of movements of the deck and towers of the bridge under affecting loads were monitored in lateral, longitudinal and vertical directions. Such movements were described in time and frequency domains by determining the trend, torsion, periodical of the series using probability density function (PDF). The results of the time series GPS data are practical and useful to bridge health monitoring.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.5
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• pp.430-435
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• 2007

This paper describes the results of electrical characteristics assessment for organic insulations of polyethylene(PE) series insulations and acrylonitrile butadiene styrene copolymer(ABS). In the experiment, 4 kinds of specimens by composition density were tested in relative permittivity, specific resistance and tracking duration. A WinDETA system and a tracking test set manufactured for this assessment were used to measure the dielectric parameters and tracking duration, respectively. In measuring the tracking duration, the time from testing voltage application to testing circuit breaking due to the tracking current was measured. As a result, dielectric dispersion was observed in measuring the relative permittivity of ABS. It was confirmed that the relative permittivity decreased with the density of the PE series insulations and it depends rather on the temperature than frequency. In most specimens, specific resistance exponentially decreased with frequency and the result for each specimen was almost similar. By the way, in the tracking test, all the PE series insulations showed more excellent performance than ABS and especially in the case of HDPE, its tracking withstand performance was the best.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.4
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• pp.103-110
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• 2013

In Information Technology era, various amazing IT technologies, for example Big Data, are appearing and are available as the amount of information increase. The number of counselling for violation of personal data protection is also increasing every year that it amounts to over 160,000 in 2012. According to Korean Privacy Act, in the case of treating unique personal identification information, appropriate measures like encipherment should be taken. The technologies of encipherment are the most basic countermeasures for personal data invasion and the base elements in information technology. So various cryptography algorithms exist and are used for encipherment technology. Therefore studies on safer new cryptography algorithms are executed. Cryptography algorithms started from classical replacement enciphering and developed to computationally secure code to increase complexity. Nowadays, various mathematic theories such as 'factorization into prime factor', 'extracting square root', 'discrete lognormal distribution', 'elliptical interaction curve' are adapted to cryptography algorithms. RSA public key cryptography algorithm which was based on 'factorization into prime factor' is the most representative one. This paper suggests algorithm utilizing telescoping series as a safer cryptography algorithm which can maximize the complexity. Telescoping series is a type of infinite series which can generate various types of function for given value-the plain text. Among these generated functions, one can be selected as a original equation. Some part of this equation can be defined as a key. And then the original equation can be transformed into final equation by improving the complexity of original equation through the command of "FullSimplify" of "Mathematica" software.

• Journal of Korean Society of Rural Planning
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• v.25 no.4
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• pp.109-117
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• 2019

The purpose of this study is to present a time series model of onion and garlic prices. After considering the various time series models, we calculated the appropriate time series models for each item and then selected the model with the minimized error rate by reflecting the monthly dummy variables and import data. Also, we examined whether the predictive power improves when we combine the predictions of the Korea Rural Economic Institute with the predictions of time series models. As a result, onion prices were identified as ARMGARCH and garlic prices as ARXM. Monthly dummy variables were statistically significant for onion in May and garlic in June. Garlic imports were statistically significant as a result of adding imports as exogenous variables. This study is expected to help improve the forecasting model by suggesting a method to minimize the price forecasting error rate in the case of the unstable supply and demand of onion and garlic.

• Parasites, Hosts and Diseases
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• v.55 no.1
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• pp.65-69
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• 2017

A case of Taenia asiatica infection detected by small bowel series and colonoscopy is described. The patient was a 42-year-old Korean man accompanied by discharge of movable proglottids via anus. He used to eat raw pig liver but seldom ate beef. Small bowel series radiologic examinations showed flat tape-like filling defects on the ileum. By colonoscopy, a moving flat tapeworm was observed from the terminal ileum to the ascending colon. The tapeworm was identified as T. asiatica by mitochondrial DNA sequencing. The patient was prescribed with a single oral dose (16 mg/kg) of praziquantel.

• The Korean Journal of Applied Statistics
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• v.11 no.1
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• pp.177-184
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• 1998

Most of the research on discrimination and classification analysis has been directed to the situation where the data consist of independent observations. However, it is often the case in practice that a dependence structure between objects does exist, in particular, for the time series data. This article is handling such a case and is concerned with the problem of classifying new object when the dependence can be modelled by a discrete time series via conditional autologistic transition probability.

• The Journal of the Korean dental association
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• v.45 no.3 s.454
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• pp.169-181
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• 2007

In this second part of series report on evidence-based dentistry, the level of evidence and the methods for critical appraisal are discussed. The epidemiologic studies, namely clinical studies have some bias per se, and the degree of bias is somewhat predetermined by the study design. The level of evidence can be defined as the reliability of the clinical study and it is dependent on the degree of bias. Thus, it is important to determine the type of the study and to understand its structure before critically appraising them. Systematic reviews of primary studies, randomized controlled trials, nonrandomized clinical trials, cohort studies, case-control studies, and case reports / series constitute the clinical studies and the level of evidence follows the order of the studies listed above. Critical appraisal is the most important procedure in evidence-based dentistry. It is done to determine the credibility of research papers and their usefulness in the clinician s own practice. Critical appraisal is consisted of multiple questions that are helpful for evaluating validity and usefulness of the studies concerning therapy, diagnosis, prognosis, and causation.

• Korean Journal of Acupuncture
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• v.30 no.3
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• pp.151-160
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• 2013

Objectives : The purpose of this study is to review the thread embedding treatment studies of obesity in Traditional Chinese Medicine. Methods : We reviewed 59 studies on cat-gut-embedding treatment of obesity which were published from 2005 to 2012. The studies were searched using the data base-CAJ(China Academic Journals; 中國期刊全文數據庫)(2005~2012). Results : Selected 59 studies were divided into 27 case series and 32 control studies. The number of studies has increased since 2005, more rapidly in 2011~2012. Most case series reported were about effectiveness of thread embedding monotherapy treating obesity. Control studies reported were about effectiveness of thread embedding treatment compared with acupuncture, electroacupuncture, and medicine. Most studies on thread embedding treatment of obesity showed that its effectiveness was very good. Conclusions : There have been many reports of thread embedding treatment studies of obesity in Traditional Chinese Medicine. We believed that these studies could be applied to the clinical practice and basic research in Korea.