• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.25-30
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• 2012

Renewable energy has been interested because of fluctuation of oil price, depletion of fossil fuel resources and environmental impact. Amongst renewable energy resources, hydropower is most reliable and cost effective way. In this study, to develop a new type of micro hydro turbine which can be operated in the range of very low specific speed, a cross-flow hydro turbine with simple structure is proposed. The turbine is designed to be used at the very low specific speed range of hydropower resources, such as very high-head and considerably small-flow rate water resources. CFD analysis on the performance and internal flow characteristics of the turbine is conducted to obtain a practical data for the new design method of the turbine. Results show that optimized arrangement of guide vane angle and inner guide angle can give contribution to the turbine performance improvement.

• Korean Institute of Interior Design Journal
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• v.15 no.3 s.56
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• pp.48-55
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• 2006

A sustainable building must produce an interior environment that is safe, healthy, comfortable and supportive of human performance and well-being. The medical human comfort: performance and productivity cost of unhealthy environment may cause much cost for healing. Research that buildings with daylight, fresh air, eco-materials and sustainable interior design are consistently rated as more comfortable and occupants performance, satisfaction and health. This study is to categorize systematically interior environmental design elements for improving sustainability with a view to developing an evaluation model of super high-rise apartment unit plans. With a literature survey and design guide lines concerning sustainable design elements, three hierarchical categorization levels of human, environment, energy and resources systems that consists of upper, middle, low design elements have been proposed. A total of 6 items have been suggested for middle level of categorization and 24 items for lower level. Finally a total of 107 design elements concerning the 24 items and their relationahips have been revealed. The needs for a systematic approach to interior environmental design for sustainability have been discussed.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.1
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• pp.69-78
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• 2018

The purpose of this study is propose eco-friendly remodeling while protecting the living environment of existing residents and preserving the living in pleasant by considering the characteristic of high density sloped residential area. And then, the optimum insulation condition is analyzed based on the energy efficiency, economic analysis and environmental effect. It will be possible as the basic information for remodeling of each housing in sloped area. The energy demanding, cost and the carbon emission reduction is analyzed with the residential area in Seo-gu, Busan by eco-remodelling.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.35-57
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• 2021

Fog computing aims to provide the solution of bandwidth, network latency and energy consumption problems of cloud computing. Likewise, management of data generated by healthcare IoT devices is one of the significant applications of fog computing. Huge amount of data is being generated by healthcare IoT devices and such types of data is required to be managed efficiently, with low latency, without failure, and with minimum energy consumption and low cost. Failures of task or node can cause more latency, maximum energy consumption and high cost. Thus, a failure free, cost efficient, and energy aware management and scheduling scheme for data generated by healthcare IoT devices not only improves the performance of the system but also saves the precious lives of patients because of due to minimum latency and provision of fault tolerance. Therefore, to address all such challenges with regard to data management and fault tolerance, we have presented a Fault Tolerant Data management (FTDM) scheme for healthcare IoT in fog computing. In FTDM, the data generated by healthcare IoT devices is efficiently organized and managed through well-defined components and steps. A two way fault-tolerant mechanism i.e., task-based fault-tolerance and node-based fault-tolerance, is provided in FTDM through which failure of tasks and nodes are managed. The paper considers energy consumption, execution cost, network usage, latency, and execution time as performance evaluation parameters. The simulation results show significantly improvements which are performed using iFogSim. Further, the simulation results show that the proposed FTDM strategy reduces energy consumption 3.97%, execution cost 5.09%, network usage 25.88%, latency 44.15% and execution time 48.89% as compared with existing Greedy Knapsack Scheduling (GKS) strategy. Moreover, it is worthwhile to mention that sometimes the patients are required to be treated remotely due to non-availability of facilities or due to some infectious diseases such as COVID-19. Thus, in such circumstances, the proposed strategy is significantly efficient.

• Journal of Korea Multimedia Society
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• v.19 no.8
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• pp.1487-1497
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• 2016

Explosively growing service of digital multimedia data increases the need for highly scalable low-cost storage. This paper proposes the new storage architecture based on torus network which does not need network switch and erasure coding for efficient storage usage for high scalability and efficient disk utilization. The proposed model has to compensate for the disadvantage of long network latency and network processing overhead of torus network. The proposed storage model was compared to two most popular distributed file system, GlusterFS and Ceph distributed file systems through a prototype implementation. The performance of prototype system shows outstanding results than erasure coding policy of two file systems and mostly even better results than replication policy of them.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.3
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• pp.218-222
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• 2011

This paper proposes a single-joint optical torque sensor with one body structure. Conventional optical torque sensors consist of three parts, two plates and an elastic structure. They have slightly slipping problem between plates and elastic structure due to the manufacturing tolerance. Since the order of measurement range of optical sensor is about ten micrometers, the slipping problem causes large measurement error, especially in the case of vibrational or high speed plant. This problem does not occur in the proposed design due to the one body structure. The proposed sensor has advantage of low cost, light weight, and small size. And it is easy to design and manufacture. Simulation works that analysis of stress and strain are performed accurately. To demonstrate the performance of proposed sensor, experiments were implemented to compare with a commercial force/torque sensor (ATI Mini45).

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.517-520
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• 2003

Commercial video scope use CCD sensor and frame grabber for image capture and A/D interface but application limited by input resolution and high cost. In this paper we introduce portable video scope using CMOS sensor, USB pen and tuner card (low frame grabber) in place of commercial CCD sensor and frame grabber. Our video scope serves as an essential link between advancing commercial technology and research, providing cost effective solutions for educational, engineering and medical applications across an entire spectrum of needs. The software implementation is done using Direct Show in second version after initial trials using First version VFW (video for window), which gave very low frame rate. Our video scope operates on windows 98, ME, XP, 2000. The drawback of our video scope is crossover problem in output images caused due to interpolation, which has to be rectified for more efficient performance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.141-142
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• 2019

As part of the recent low-energy policy, insulation standards for buildings are increasing every year. In addition, the conventional styrofoam heat insulation material has a problem in that the thickness of the heat insulation material to achieve the standard heat transmission rate is rapidly increased. Although the risk of spreading the structure vulnerable to fire due to insufficient spacing between buildings due to thickened insulation is increasing, the high cost of high efficiency insulation is difficult to solve. On the other hand, it is known that the method to be used as a formwork using insulation is excellent in cost reduction effect by reducing the amount of formwork used and simplifying the subsequent insulation work. The purpose of this study is to evaluate the strength characteristics of multi - layered insulation materials with appropriate strength by reducing the thickness of the insulation by appropriately combining high performance phenolic foam insulation and styrofoam insulation.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.229-241
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• 1999

The paper describes the development of the ABS(Anti-Lock Bracke Sytem) real-time simulator which is composed of the real hydraulic modulator, the brake system, and the control software. This useful too supports the development enviornment of the ABS in great flexible mamer. It offers an efficient and cost-effective method of ABS development which includes the various realistic road conditons, the vehicle characteristics , and the brake characteristics. The performance of the ABS is compared with the normal braking results. Thepresented experimental results are braking on the high friction road, thetransient friction road(high to low , low to high), the split friction road, and the high friction road with steer angle. The paper shows the effectiveness and the safety of the ABS compared with the normal brake system , and the powerful and conventient tool in developing the ABS.

• The Journal of the Acoustical Society of Korea
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• v.31 no.4
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• pp.225-234
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• 2012

The anechoic chamber is essential tool to measure the various acoustic parameters with high precision. The chamber provides the climate controlled indoor environments but requires the dedicated room at a great cost in order to isolate and absorb sound field. Provided the purpose of the chamber is specific to the experiments of sound localization, the performance requirements excluding free field can be alleviated for cost effective solution. This paper designs low cost and profile anechoic chamber based on acoustic pyramids and evaluates the performance specified by the Annex of ISO 3745. Data analysis is employed to measure the free and hemi-free field performance over five straight paths for working areas and four paths for non-working areas. The identical two measurement campaigns were conducted for free and hemi-free field chamber which is easily interchangeable by simple labor in this chamber design. In the working area with conventional speaker, the results of these analyses demonstrate that lab-designed anechoic chamber is in conformance with ISO 3745 for 250 Hz - 16 kHz one-third octave band at free field chamber and for 1 kHz - 16 kHz one-third octave band at hemi-free field chamber.