• Journal of Environmental Science International
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• v.21 no.2
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• pp.135-144
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• 2012

This study aims at classifying and analyzing the vegetation structure of Castanopsis sieboldii forest, one of the evergreen broad-leaved forests found under the warm-temperate climate of Korea. It is also compared with the ones of the Castanopsis sieboldii forest in Japan where most similar such forest of Korea, to find unique vegetation structures of the only Korean forest. Vegetation structure of Korean Castanopsis sieboldii forest was divided into two units at the level of community units both of Ardisia japonica-Castanopsis sieboldii community and Ardisio-Castanopsietum sieboldii association. The association carries similar type with the vegetation system of Japan, but any subunits differentiated with the Japan were found vary much. Hierarchical cluster analysis brings in similar result with the analysis on the vegetation structure as well.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.1
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• pp.38-41
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• 2014

Fixture units and the diversity curve are used, in order to determine the required size of water supply pipe. However, the values of the National Plumbing Code, International Plumbing Code and National Standard Plumbing Code of America are not the same. The objective of this study is to comparatively analyze the fixture units and the peak flows of a 10th story office building, at any instant of time, according to the three codes.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.1
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• pp.10-20
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• 2004

Experiments have been conducted in order to make comparisons of characteristics of a R410a cycle with a R22 cycle in terms of cooling capacity and coefficient of performance (COP). The parameters examined in the present work include air flow rate, indoor and outdoor air temperatures, and indoor relative humidity. These two refrigeration cycles constructed for this study share all components except compressor, accumulator, oil separator, and piping. The measurements were made using a psychrometric calorimeter. The experimental results show that the R410A cycle has several advantages for indoor units while the R22 cycle yields better performance for outdoor units.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.158-160
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• 2015

Efficient scheduling and resource management are the key factor to reduce construction project budget (e.g., labor cost, equipment cost, material cost, etc.). Resource-based line of balance (LOB) technique has been used to complement the limitations of existing time-driven scheduling techniques (e.g., critical-path method). Optimizing construction alternatives contributes to cost savings while honoring the project deadline. However, existing LOB scheduling is lack of identifying optimal resource combination. This study presents a method which identifies the optimal construction alternatives, hence achieving resource minimization in a repetitive construction by using genetic algorithm (GA). The method provides efficient planning tool that enhances the usability of the system.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.51-58
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• 2005

The development of the high-efficiency machine-tools equipment and new cutting tool materials with high hardness, heat- and wear-resistance has opened the way to application of high-speed cutting process. The basic argument of using of high-speed cutting processes is the reduction of time and the respective increase of machining productivity. In this sense, the spindle units may be regarded as one of the most important units, directly affecting many parameters of high-speed machining efficiency. One of the possible types of spindle units for high-speed cutting is the air-bearing type. In this paper, we propose the mathematical model of the dynamic behavior of the air-bearing spindle. To provide the high-level of speed capacity and spindle rotation accuracy we need the adequate model of "spindle-bearings" system. This model should consider characteristics of the interactions between system components and environment. To find the working characteristics of spindle unit we should derive the equations of spindle axis movement under the affecting factors, and solve these equations together with equations which describe the behavior of lubricant layer in bearing (bearing stiffness equations). In this paper, the three influence coefficients are introduced, which describe the center of spindle mass displacement, angle of shaft rotation around the axes under the unit force application and that under the unit torque application. These coefficients are operated in the system of differential equations, which describes the spindle axis spatial movement. This system is solved by Runge-Kutta method. Obtained trajectories and amplitude-frequency characteristics were then compared to experimental ones. The analysis shows good agreement between theoretical and experimental results, which confirms that the proposed model of air-bearing spindle is correctis correct

• International journal of advanced smart convergence
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• v.13 no.1
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• pp.37-47
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• 2024

This study presents the results of designing a system that determines the location of a person in an indoor environment based on a single IMU sensor attached to the tip of a person's shoe in an area where GPS signals are inaccessible. By adjusting for human footfall, it is possible to accurately determine human location and trajectory by correcting errors originating from the Inertial Measurement Unit (IMU) combined with advanced machine learning algorithms. Although there are various techniques to identify stepping, our study successfully recognized stepping with 98.7% accuracy using an artificial intelligence model known as Long Short-Term Memory (LSTM). Drawing upon the enhancements in our methodology, this article demonstrates a novel technique for generating a 200-meter trajectory, achieving a level of precision marked by a 2.1% error margin. Indoor pedestrian navigation systems, relying on inertial measurement units attached to the feet, have shown encouraging outcomes.

• Korean Journal of Optics and Photonics
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• v.30 no.4
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• pp.133-141
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• 2019

Revision of the International System of Units (SI) in terms of fundamental constants was achieved by the 26th General Conference on Weights and Measures (CGPM) in November 2018. Four base units (kilogram, ampere, kelvin, and mole) of SI were redefined by fixing the values of the Planck constant h, elementary charge e, Boltzmann constant k, and Avogadro constant $N_A$ respectively. In this paper the scientific principle for redefining the kilogram from the Planck constant with the Kibble balance is explained as an example. The revised SI takes effect on May 20, 2019.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.69-88
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• 2024

Purpose : This study was conducted to examine the Experience of Adaption to Work in Comprehensive Nursing Service Units of Nurses. Methods : Empirical data were collected from 8 nurses through in-depth interviews. Eight participants who had more than 6 months of clinical experience in the general ward and had more than 6 months of work experience in Comprehensive Nursing Service Units were selected as participants. The main question was what does it mean to work in Comprehensive Nursing Service Units? All interviews were recorded and transcribed, and then analyzed using Giorgi's interview. Results: As a result of the analysis, five topics were derived. 'Facing a changed work environment', 'A sense of unexpected heterogeneity in work', 'Evaluation of immediate reality.', 'Finding strategies and promoting balance', 'Growing up as a professional nurse.' Conclusion: Based on these findings, There is a need to build a system that can adapt to work and continue to develop programs for capacity building in Comprehensive Nursing Service Units of Nurses.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.1
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• pp.37-42
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• 2001

In order to answer the challenge that development gave to environment, Chinese cities are making up and putting into effect the green space system planning. The planning main keys are: set down standards and scope of green space; bring the characteristics of every types of green space in to full play and made into basic units of the system; formed powerful links of the system; make full use of the natural system of city, constituted the urban and countryside as a organic whole green space system, therefore give full play their function and ecological effect. In fact, this green space system is a complex system. It is the main body of city ecological system, a main container of the citizen activities of leisure and recreation and a leading factor for making characteristic city landscape. Therefore it is a system carrying city's environment sustainable development.

• International Journal of Reliability and Applications
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• v.16 no.2
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• pp.99-111
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• 2015

In this paper, we study the reliability analysis of a repairable system with two types of failure in which switching failures and reboot delay are considered. Let units in this system be cold standby, and failure rate and repair rate of [type1, type2] components be exponentially distributed. The expressions of reliability characteristics - such as the system reliability and the mean time to system failure MTTF - are derived. We use several cases to graphically analyze the effect of various system parameters on the system reliability and MTTF. We also perform a sensitivity analysis of the reliability characteristics with changes in specific values of the system's parameters.