• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.1
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• pp.322-327
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• 2007

The purpose of this study was to investigate the change of female's Bone Mineral Density after taking herbal medicine. We examined age, sex, marriage, alcohol, smoking, and job of 76 female and their life style related with Osteoporosis. Bone Mineral Density was examined after 1 month (one herbal medicine), 2 months (two herbal medicine), and 3 months (three herbal medicine) between Group I (taking pear extract) and Group II (taking herbal medicine). Bone Mineral Density of Group II after 1 month was increased, but insignificant. Bone Mineral Density was not significantly different between the Group I and Group II after 2 and 3 months. In this study, we can conclude that Bone Mineral Density was increased after 1 month of taking herbal medicine. But we had inaccurate results due to limitations of this study: period of test, accuracy of instrument, impossibility of use young antlers of the deer, and etc. More detailed study should be conducted to yield more concrete results.

• 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.

• Journal of Nutrition and Health
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• v.27 no.1
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• pp.71-78
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• 1994

Recently the incidence of hemorrhoids has been increased. There were various factors related to hemorrhoids, the amount of fiber intake was known as one of them. And so we performed this case-control study to investigate the association of hemorrhoids and fiber intake. The data was obtained by the combination of self-administered questionnaire and personal interview. The study population was consisted of matched 156 pairs, the cases were selected from S-hospital in Seoul, the age and sex matched control from the general population. The statistical analysis was performed by matched-analysis. The results summarized as follow : 1) As socio-economic status were low, the odds ratio of hemorrhoids were high. 2) There was significant association between hemorrhoids and regularity of eating time rather than regularity of defecation. 3) The odds ratio of hemorrhoids was 3 times higher in the presence of constipation. 4) The incidence of hemorrhoids was influenced by psychological characteristics such as somatization, obsessive-compulsive, depression, and anxiety. 5) Fiber intake was significantly lower in the cases compared to the controls. When the constipation was controlled, the fiber intake was still lower in the cases. These data provide additional evidence that the fiber intake was related to hemorrhoids.

• Journal of Korean Dental Science
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• v.3 no.2
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• pp.34-39
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• 2010

In our daily practice, we think about the diagnosis of our patient and get into a situation wherein we have to make a clinical decision. Diagnosis and treatment come from the knowledge and experiences that each dentist should have, but sometimes, we can have doubts on our decisions. "On what evidence did I make such decision? Was that really right?" Drawing our attention these days as a possible answer to this question, evidence-based dentistry seeks to apply the best available evidence gained from the scientific method to medical decision making. To make a good decision, the strength of evidence is assessed. Specifically, randomized controlled trial, systematic review, and meta-analysis are considered the highest level of evidence; cohort study, case control study, case series, animal study, bench test, and biological plausibility follow. With the approach of evidence-based dentistry, we can make objective, scientifically sound clinical decisions. It is also patient-oriented, incorporating clinical experiences and stressing good judgments; thorough and comprehensive, it uses transparent methodology. That is the reason evidence-based dentistry can be better than other assessment methods when we make a clinical decision in modern dentistry.

• 전기의세계
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• v.31 no.1
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• pp.43-49
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• 1982

This paper intends to compare and illustrate the feedback effects of the state feedback scheme to a positional control system by the use of the state observer. As a case study, the dynamic properties of a proposed positional control system lie derived, first, and the design of an optimal state feedback control system by the actual states is intended as a primary case study. For the illustration of the feedback effects with the asymptotic state observer, unobservability of some state variables are assumed and an optimal state feedback design is carried by using the estimated states which is reconstructed through the observer. That is, when some of the states of the system to be controlled are not avalable, an observer is constructed to estimate the unaccessable states. Adigital computer is used for the comparative study of the feedback effects in both cases. The resultant response of the proposed system have shown quite reasonable satisfaction oncontrol quality.

• Journal of Advanced Marine Engineering and Technology
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• v.16 no.4
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• pp.102-112
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• 1992

The three-phase full(6-pulse) bridge controlled rectifier is one of the most widely used types of solid-state converters in DC drive applications for higher performance. In most of the previous designs, the gate control circuits of the converter have been designed with analog method which can be easily affected by noise. Nowdays with advances of microelectronics and power electronics, microprocessor and pheripal LSIs are increasingly used for eliminating this problems. In this paper, a novel general-purpose microprocessor -based firing system and control scheme for a three-phase controlled rectifier bridge has been developed and tested. Using the phase relations between ${\Delta}$-Y transformer in power operation part, gate pulse of the converter is generated with real time process so that microprocessor may share its time to control algorithms efficiently. The firing angle of the converter is smoothly controlled in the range of 0 $^{\dirc}$ to 180$^{\dirc}$ with a fast respone and a constant open loop gain, even for the case where the converter is fed by a weak AC system of unregulated frequency. The hardware and software control circuit implementation built around a 80286 microprocessor is discussed, and the experimental results are given. This scheme uses less hardware components and has higher dynamic performance in variable speed DC drive applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.182-187
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• 2008

This paper dealt with the detection algorithm of series arcing, which is a cause of electric fires in low-voltage wiring systems. To find the distinguished electrical features of series arc, we simulated series arcing by the arc generator specified in UL1699. An electric heater, an inverter-controlled vacuum cleaner, and a phase-controlled incandescent lamp were used as loads to generate series arcing. A high-pass filter (HPF) with the low cut-off frequency of 3 kHz at -3 dB was fabricated and applied to separate the series arc signal from the AC voltage source. The experiment showed that the high frequency signal generates randomly during series arcing, and the phase-controlled incandescent lamp produces high frequency pulses even in normal state. In this case, the magnitude, the width, and the randomness of high frequency signal should be analyzed to estimate series arcing precisely.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.88-93
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• 1987

Chitosan ($\beta$-D-glucosaminan) is chemically prepared from chitin (N-acetyl-$\beta$- D-glucosaminan) which is an unutilized natural resource. We now report on the suitability of the chitosan matrix for use as vehicles for the controlled release of drugs. Salicylic acid and aspirin were used as model drugs in this study. The permeation of salicylic acid in the chitosan membranes was determined in a glass diffusion cell with two compartments of equal volume. Drug release studies on the devices were conducted in a beaker containing 5% sodium hydroxide solution. Partition coefficient (Kd) value for acetate membrane (472) is much greater than that for fluoro-perchlorate chitosan membrane (282). Higher Kd value for acetate chitosan membrane appears to be inconsisstent with the bulk salicylic acid concentration. The permeability constants of fluoro-perchlorate and acetate chisotan membranes for salicylic acid were 3.139 ${\times}10^{-7}cm^2$ min up to 60 min and that of 30% aspirin in the devices was 4.739${\times}10^{-7}cm^2$sec upto 60 min. As the loading dose of aspirin in a chitosan device increased, water up-take of chitosan device increased, but in case of salicylic acid it decreased. The release rate increased with increase in the molecular volume of the drugs. Thses result suggest that the release mechanism may be controlled mainly by diffusion through pores.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.45-51
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• 1999

In this study to assess chip breaking characteristics of cold-drawn free machining steels a newly developed non-dimensional parameter chip breaking index CB has been adopted. And for comparison with free machining steels chip breaking characteristics of conventional carbon steels were investigated. Properly controlled chips were produced with the CB value of 0.05-0.2 regardless of steel types. In case of cold-drawn free machining steels however cycle times of chip breaking are relatively shorter than those of conventional steels. And properly controlled chips were obtained from wider range of feed rate.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.9
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• pp.1013-1020
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• 1992

The conductivity variation of a high resistivity bulk silicon semiconductor, whose electrodes were deposited with aluminum vapor, was studied experimentally by measuring the X-ray intensity and current flow, which was developed by X-ray radiation while applying a pulse voltage to the silicon, in a load resistor connected to the semiconductor. The current flow observed immediately as the X-ray radiated, and when the X-ray decreased. It was found from the observation of switching current for the X-ray intensity and the voltage applied in the semiconductor that the switching current of the semiconductor increased as the intensity of the X-ray and the applied voltage increased. In case of lower applied voltage, the switching current for higher applied voltage depended on the intensity of the X-ray radiated due to the saturation of electron and hole.