• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.171-173
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• 2008

The amount of incident solar rays on inclined surfaces with various directions has been widely utilized as important data in installing solar collector, hot water system, and designing solar buildings and house. This is because the performance of the solar energy applied systems is much affected by angle and direction of incident rays. Recognizing those factors mentioned above are of importance, actual experiment has been performed in this research to obtain the angle of inclination with which the maximum incident rays can be absorbed. The results obtained in this research could be used in designing optimal solar thermal systems.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.3
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• pp.215-221
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• 2013

The basic quantitative tool for the study of hypersonic rarefied flows is the direct simulation Monte Carlo method (DSMC). The DSMC method requires a large amount of computer memory and performance and is unreasonably expensive at the first stage of spacecraft design and trajectory analysis. A possible solution to this problem is approximate engineering methods. However, the Monte Carlo method remains the most reliable approach to compare to the engineering methods that provide good results for the global aerodynamic coefficients of various geometry designs. This paper presents the calculation results of aerodynamic characteristics for spacecraft vehicles in the free molecular, the transitional and the continuum regimes using the local engineering method. Results and methods would be useful to calculate aerodynamics for new-generation hypersonic vehicle designs.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.3
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• pp.27-38
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• 2012

The purpose of this study is to analysis the concept of location efficiency, a base for the qualitative evaluation of TOD, and to propose the method of urban design for the improvement of location efficiency. Because of the environmental crisis by urbanization, sprawl and global warming, the importance of the solution through TOD has been increasing. For the future development of TOD, it becomes important to evaluate TOD qualitatively. From the study, it is grasped that location efficiency contains the concepts of value recapture, QoL and choice, financial return, and efficient regional land use and patterns. And the method of urban design for location efficiency is proposed as the followings: Form Based Zoning as land use plan, TOD and TOC model as node function, and street systems, mixed-use development, characteristic housing with various types, and networking of neighborhood facilities as place function.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.119-124
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• 2004

In this study, a rotor blade of a Curtis turbine is investigated. Bezier curve is generally used to define the profile of turbine blades. However, this curve gives a feature of global control, which is not proper to a supersonic impulse turbine blade. Thus, a blade design method is developed by using B-spline curve so that local control is possible to obtain an optimized blade section. To design a Curtis turbine blade section systematically, the blade section has been changed by varying three design parameters using central composite design method. Flow analyses have been carried out for the blade sections, and the effects of design parameters are evaluated.

• Journal of the Korea Safety Management & Science
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• v.9 no.6
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• pp.81-88
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• 2007

This study deals with the overall meta-cognitive aspects of ATC-Pilot miscommunications pertinent to cognitive human errors based on the previous literature research which it has been focused on the issue of the global aviation English use in regard with aircraft accident and incident. Especially, it addresses the concern over the ICAO aviation English language proficiency evaluation program which will be implemented globally in March, 2008. In addition, It presents the analysis related to the on-going English language proficiency level four test conducted for Korean civil airlines pilots and air traffic controllers.

• Electronics and Telecommunications Trends
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• v.35 no.2
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• pp.1-16
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• 2020

"Artificial Intelligence+" is a key strategic direction that has garnered the attention of several global medical device manufacturers and internet companies. Large hospitals are actively involved in different types of medical AI research and cooperation projects. Medical AI is expected to create numerous opportunities and advancements in areas such as medical imaging, computer aided diagnostics and clinical decision support, new drug development, personal healthcare, pathology analysis, and genetic disease prediction. On the contrary, some studies on the limitations and problems in current conditions such as lack of clinical validation, difficulty in performance comparison, lack of interoperability, adversarial attacks, and computational manipulations are being published. Overall, the medical AI field is in a paradigm shift. Regarding international standardization, the work on the top 10 standardization issues is witnessing rapid progress and the competition for standard development has become fierce.

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.3
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• pp.109-116
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• 2018

SSDs that are not allowed in-place update within the allocated page cause another allocation of a new page that will replace the previous page at the moment data modification occurs. This intrinsic characteristic of SSDs requires many changes to the existing HDD-based IO theory. In this paper, we conduct a performance comparison of FTL caching strategy in perspective of cache hashing (Global vs. grouped) and caching algorithm (LRU vs. NUR) through a simulation. Experimental results show that in terms of energy consumption for flash operation the grouped management of cache is not suitable and NUR algorithm is superior to LRU algorithm. In particular, we found that the cache hit ratio of LRU algorithm is about 10% point higher than that of NUR algorithm while the energy consumption of LRU algorithm is about 32% high.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.5 no.1
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• pp.46-52
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• 2002

A robust nonlinear observer, utilizing the sliding mode concept, is developed for the dynamic positioning of ships. The observer provides the estimates of linear velocities of the ship and bias from slowly varying environmental loads. It also filters out wave frequency motion to avoid wear of actuators and excessive fuel consumption. The main advantage of the proposed observer is in its robustness. Especially, the observer structure with a saturation function makes the proposed observer robust against neglected nonlinearties, disturbances and uncertainties. Since the mathematical model of DP ships is difficult to obtain and includes uncertainties and disturbances, it is very important for the observer to be robust. A nonlinear output feedback controller is derives based on the developed observer using the observer backstepping technique, and the global stability of the observer and control law is shown by Lyapunov stability theory.. A set of simulation was carried out to investigate the performance of the proposed observer for dynamic positioning of ships.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.14-19
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• 2014

The global demand for reduction in the weight of automobiles has led many countries to focus on the development of hybrid, eco-friendly, and electric cars. Reduction in the weight of materials can both increase fuel efficiency and maximize automobile performance. Therefore, the design of automobile should be inclined towards the safety aspects. but at the same time, it also consider reducing the structural weight of an automobile. In this study, CFRP side members with circular and double hat shaped section was manufactured. The impact collapse tests performed with change of the stacking condition, such as variation of interface number and outerlayer angle. The impact collapse load and absorbed energy were quantitatively analyzed according to the changes in section shapes and stacking condition. This analysis was performed to obtain design data that can be applied in the development of optimum lightweight members for automobiles.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.9
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• pp.2349-2354
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• 1996

Convergence analysis on Godard's quartic (GQ) algorithm used forblind equalization is accomplished in this paper. The first main result is an explanation of the lacal behavior of the GQ algorithm around the global minimum point of the average performance functio, from which we can determine the adaptation gain. It is show that the normalized adaptation gain of the GQ algorithm should be smaller than that of the decision directed (DD) algorithm. In addition, it is observed that the GQ algorithm converges faster than the DD equalization algorithm.