• 대한간호학회지
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• 제43권2호
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• pp.154-164
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• 2013

Purpose: The purpose of this article is twofold: 1) introducing logistic regression (LR), a multivariable method for modeling the relationship between multiple independent variables and a categorical dependent variable, and 2) examining use and reporting of LR in the nursing literature. Methods: Text books on LR and research articles employing LR as main statistical analysis were reviewed. Twenty-three articles published between 2010 and 2011 in the Journal of Korean Academy of Nursing were analyzed for proper use and reporting of LR models. Results: Logistic regression from basic concepts such as odds, odds ratio, logit transformation and logistic curve, assumption, fitting, reporting and interpreting to cautions were presented. Substantial shortcomings were found in both use of LR and reporting of results. For many studies, sample size was not sufficiently large to call into question the accuracy of the regression model. Additionally, only one study reported validation analysis. Conclusion: Nursing researchers need to pay greater attention to guidelines concerning the use and reporting of LR models.

• Tribology and Lubricants
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• 제30권2호
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• pp.86-91
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• 2014

This paper presents a design procedure for a face gear and pinion used in a handpiece with a $160^{\circ}\acute{y}$ contra angle and 1:2 gear ratio. Based on the geometric theory of gearing, the tooth profile of the face gear and pinion is developed. To analyze the contact pressure, the gear profile should be determined before calculating the stress between the two gears. The concept of calculating the face gear profile is that it can be generated by the coordinate transformation of the shaper profiles, which have involute curves, using a simulation method from the gear manufacturing process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.389-390
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• 2006

The cycloidal reducer is one of the velocity controlling equipments in machinery. It has advantages of the higher reduction ratio, the higher accuracy, the easier adjustment of the transmission ratio and the smaller workspace than any other kinds of the reducers. This paper proposes a simple and exact approach for the lobe profile design of the two teeth difference cycloidal plate gear, which is different from the standard cycloidal reducer, by means of the principle of the instant velocity center in the general contact mechanism and the homogeneous coordinate transformation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.627-627
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• 2009

In this work, the activated carbons (ACs) with high porosity were synthesized from pitch by KOH chemical activation. The structure and surface properties of ACs were characterized by means of elemental analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy(XPS). And, the influence of the KOH-to-pitch ratio on the porosity of the ACs was investigated using the nitrogen adsorption isotherms at 77 K and a scanning electron microscopy (SEM). As a result, pitch could be successfully converted into ACs with well-developed micro and mesopores. The specific surface areas and pore volumes were increased with an increase of the KOH-to-pitch ratio. Furthermore, it was found that the addition of KOH led to the transformation of the micropores to the meso- and macropores. In the application to electric double layer capacitors (EDLC), the pitch-based ACs showed a higher capacitance per weight and per volume, and an excellent electrochemical stability in the high voltage region.

• 한국염색가공학회지
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• 제11권3호
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• pp.41-48
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• 1999

The removal of hemoglobin from acrylic acid grafted Nylon fabrics has been investigated. In order to change detergency of Nylon 6 fabric, acrylic acid(AA) were graft copolymerized on Nylon fabric using ammonium persulfate(APS) as a initiator, and then acrylic acid grafted Nylon was treated with NaOH solution. The graft ratio increased linearly with increasing acrylic acid concentration. The graft ratio was the highest when the concentration of APS was 0.05%, and it decreased as the concentration of APS increased. The surface of Nylon fabric became rough due to graft. Moisture regain was increased by graft and alkaline treatment, contact angle was also improved compared with the ungrafted. The hemoglobin was easily solubilized and removed from grafted Nylon fabric, while it was difficult to remove hemoglobin from ungrafted Nylon fabric. The effects of graft on removal of hemoglobin was related with increase of moisture regain and transformation of COOH to COONa by alkaline treatment.

• Communications for Statistical Applications and Methods
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• 제29권4호
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• pp.453-469
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• 2022

The study of immune cellular composition has been of great scientific interest in immunology because of the generation of multiple large-scale data. From the statistical point of view, such immune cellular data should be treated as compositional. In compositional data, each element is positive, and all the elements sum to a constant, which can be set to one in general. Standard statistical methods are not directly applicable for the analysis of compositional data because they do not appropriately handle correlations between the compositional elements. In this paper, we review statistical methods for compositional data analysis and illustrate them in the context of immunology. Specifically, we focus on regression analyses using log-ratio transformations and the alternative approach using Dirichlet regression analysis, discuss their theoretical foundations, and illustrate their applications with immune cellular fraction data generated from colorectal cancer patients.

• Journal of Smart Tourism
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• 제2권3호
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• pp.17-30
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• 2022

The tourism sector of the Maldives has seen rapid growth since its inception in 1972. One significant development is the transformation of the market composition in recent years. China has surpassed traditional European markets as the single largest source market. In this regard, this study seeks to assess the seasonality in the Maldivian tourism sector using a monthly dataset of visitor arrivals from 2003 to 2019. The seasonality ratio, the seasonality indicator, the Gini coefficient and the seasonal index were used to examine the seasonality patterns. The results of this study show that there are three distinct peaks (January to April, August, and November to December) and two off-peaks (May to July and September) periods. The findings also reveal that the rise of the Chinese market has significantly lessened the seasonality of Maldivian inbound tourism. Finally, some important implications are discussed.

• 한국항만학회지
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• 제8권1호
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• pp.31-40
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• 1994

Experimental study is carried out to verify the advantages of an air chamber structure in controlling the wave transformation and its dynamic responses. The open, cross and vertical mooring systems are employed in experiments to investigate the variations of wave transmission ratio, natural period of the structures and tensile force acting on the mooring line according to the change of the initial air depth inside the air chamber structure. Experimental results show that the air chamber floating structure expresses the smaller wave transmission ratio and tensile force acting on the mooring line than general one without air chamber, expecially in the long period region of incident wave. Therefore, it is concluded that the air chamber structure suggested in this study can play good roles as a wave controlling castal structure, and a substitute structure of a general floating structure.

• 대한기계학회논문집A
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• 제25권1호
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• pp.70-80
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• 2001

A cycloid reducer is one of the rotational velocity reduction equipments of machinery. It has advantages of the higher reduction ratio, the higher accuracy, the easier adjustment of transmission ratio and the smaller workspace than other kinds of reducer. A cycloidal plate gear is a main part of the cycloid reducer. Its tooth shape is peculiar because of gearing with the roller gear that has the several rollers on the circular line. And then it can be designed to contact all teeth to rollers. So, the cycloid reducer has the good characteristics in the dynamic properties and the zero-backlash in the contact motion. It can be used in robots, high-precision machines and high capacity machinery. This paper proposes a new approach for the shape design of the cycloidal plate gear and presents a Computer-Aided-Design program developed by the proposed method. The first part of this paper defines the two types of the cycloid reducers and explains their mechanisms. The second part defines the instant velocity centers for each type of the cycloid reducers and calculates the contact angles and the contact points by using te geometric relationships and the kinematical properties of the reducers. The third part generates the full shape of the cycloidal plate gear by the coordinate transformation technique. Finally, this paper presents two examples for the shape design of the cycloidal plate gear in order to prove the theory of the proposed method in this paper and the accuracy of the \"CycloGear Designer\".

• 품질경영학회지
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• 제42권3호
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• pp.361-372
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• 2014

Purpose: In this paper, we investigate whether the endeavors for 6 sigma quality management by a firm have positive effects on its financial performance and the length of 6 sigma implemented period affects its financial status. Methods: We conduct the analysis using the data from Workplace Panel Survey 2009. We use multiple linear regression in order to analyze the relationship between the efforts for quality management and financial performance. Specifically, the return on assets (ROA) and return on equity (ROE) are investigated as dependent variables and the efforts for quality management as independent variable. The Box-Cox transformation and Cook's distance are also used. Results: As a result of the analysis, the indication is that companies that put effect into the six sigma quality management have a positive result in its financial status. In detail, the efforts for six sigma quality management have positive effects on total asset turnover ratio and six sigma implemented period on net income to net sales ratio. Additionally, companies with longer(shorter) period of six sigma program have more (less) improvement in its financial status. Conclusion: It can be concluded that the company's efforts for quality management positively influence financial performance.