• Journal of information and communication convergence engineering
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• 제12권1호
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• pp.39-45
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• 2014

A numerical method for solving Hamiltonian equations is said to be symplectic if it preserves the symplectic structure associated with the equations. Various symplectic methods are widely used in many fields of science and technology. A symplectic method preserves an approximate Hamiltonian perturbed from the original Hamiltonian. It theoretically supports the effectiveness of symplectic methods for long-term integration. Although it is also related to long-term integration, numerical stability of symplectic methods have received little attention. In this paper, we consider explicit symplectic methods defined for Hamiltonian equations with Hamiltonians of the special form, and study their numerical stability using the harmonic oscillator as a test equation. We propose a new stability criterion and clarify the stability of some existing methods that are visually based on the criterion. We also derive a new method that is better than the existing methods with respect to a Courant-Friedrichs-Lewy condition for hyperbolic equations; this new method is tested through a numerical experiment with a nonlinear wave equation.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1996년도 추계학술대회논문집
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• pp.153-159
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• 1996

Usability evaluation can be valuable tool for analyzing and improving computer software. Various usability evaluation methods have been developed in the fields of human-computer interaction and software ergonomics. Although there are several useful methods available, designers or engineers engaged in usability evaluations should really select the most suitable methods for each specific system being evaluated. Even different systems within the same organization may require different evaluation methods to maximize the quality of the data obtained from each evaluation. In this paper, the taxonomy of evaluation methods based on the development life cycle is presented and comparative analysis between methods is performed. In addition, the implications for selecting appropriate usability methods and using them collectively are discussed.

• 한국가구학회지
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• 제15권2호
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• pp.1-17
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• 2004

This paper attempted to review measuring methods of formaldehyde emission from wood-based panel products. Methods included for the discussion were desiccator methods, extraction method, and various chamber methods. First, the procedures and testing conditions of 24-hour desiccator method was critically reviewed, and an improvement of this method was proposed to meet international standards. Two different small chamber methods ($20\ell$ and $1m^3$ chamber methods) were also compared in terms of their advantages and disadvantages. In addition, the regulation levels of formaldehyde emission of wood-based composite panels were compared for different countries. The selection of a reference method of measuring formaldehyde emission of wood panel products should consider the ease of conducting test and cost required. Results should be exchangeable for different methods.

• 한국조경학회지
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• 제27권2호
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• pp.51-57
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• 1999

Planting methods of seeding, seed net, sprig net and sprigging were evaluated for influence on the covering rate and the growth of Phragmites spp. The results were as follows. 1. Covering rate was high within 4 months when propagated by sprig net, seeding and sprigging but became same within 5 months afterwards regardless of Planting methods. 2. Growth of leaf height and width was high on vegetative types of Planting methods such as sprig net and sprigging when compared with on seed types of Planting methods such as seeding and seed net. 3. Sprig net showed good covering rate and growth than sprigging when compared within vegetative types of planting. 4. In this study, sprig net was figured out as the best type of Planting methods than any other types of Planting methods for the restoration of a shore vegetation in a urban stream.

• 한국항공운항학회지
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• 제8권1호
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• pp.83-95
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• 2000

Lift, drag, pitching moment, what we call longitudinal aerodynamic coefficient, effects airplanes directly, so the method to find the accurate result quickly is an important factor from the beginning of the aircraft design. There are different ways to find aerodynamic coefficient such as empirical methods, numerical analysis methods, wind tunnel tests, and finally through an actual flight tests, but choosing the best methods depends on the due date or the cost. The accuracy varies on each design level, but all this methods have relationship to complement and balance each other, so by combining proper methods, the best result can be obtained. At this paper, empirical methods and numerical analysis method were experimented, compared, and reviewed to find the availability of each method and by combining two methods accurate result was obtained. So, we applied this methods to predict the aerodynamic coefficient on cruise configuration aircraft, and was able to obtain more accurate result on the low speed longitudinal aerodynamic coefficient. Also by watching there result, we are able to predict the errors before the actual wind tunnel test.

• Communications for Statistical Applications and Methods
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• 제3권2호
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• pp.53-67
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• 1996

Numerous classical as well as robust methods have been proposed in the literature for the detection of multiple outlier in multivariate data. The effectiveness and power of each of these methods have not been thoroughly investigated. In this paper we first reduce the vast number of outlier detection methods to a small number of viable ones. This reduction is based on previous work of other researches and on some theoretical arguments. Then we design and implement a Monte Carlo experiment for comparing these methods. The main goal of our study is to determine which methods are most powerful in the detection of multiple outlier and in dealing with the masking and swamping problems. The results of the Monte Carlo study indicate that two of the methods seem to hace better performances than the others for the detection of multiple outlier in multivariate data.

• 대한소화기학회지
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• 제72권5호
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• pp.229-236
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• 2018

Accurate diagnosis of Helicobacter pylori (H. pylori) infection is mandatory for the effective management of many gastroduodenal diseases. Currently, various diagnostic methods are available for detecting these infections, and the choice of method should take into account the clinical condition, accessibility, advantage, disadvantage, as well as cost-effectiveness. The diagnostic methods are divided into invasive (endoscopic-based) and non-invasive methods. Non-invasive methods included urea breath test, stool antigen test, serology, and molecular methods. Invasive methods included endoscopic imaging, rapid urease test, histology, culture, and molecular methods. In this article, we provide a review of the currently available options and recent advances of various diagnostic methods.

• Journal of information and communication convergence engineering
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• 제20권2호
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• pp.131-136
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• 2022

The recommendation system applied in museums has been widely adopted owing to its advanced technology. However, it is unclear which recommendation is suitable for indoor museum guidance. This study evaluated a recommender system based on social-filtering and statistical methods applied to actual museum databases. We evaluated both methods using two different datasets. Statistical methods use collective data, whereas social methods use individual data. The results showed that both methods could provide significantly better results than random methods. However, we found that the trip time length and the dataset's sizes affect the performance of both methods. The social-filtering method provides better performance for long trip periods and includes more complex calculations, whereas the statistical method provides better performance for short trip periods. The critical points are defined to indicate the trip time for which the performances of both methods are equal.

• Nuclear Engineering and Technology
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• 제11권3호
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• pp.219-229
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• 1979

The current status of the computational methods and computer codes for the analysis of reactor kinetics is reviewed. Computational methods which have been developed for space-dependent transient analyses are presented and recent progress in the development of methods is discussed.

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2005년도 춘계 학술발표대회 논문집
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• pp.8-9
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• 2005