• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.250-255
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• 2008

Most high-rise building and large building require a cooling tower. Closed cooling tower is a low noise and the high efficiency. also Closed cooling tower is available for four season. Performance of Closed cooling tower is judged by heat transfer coefficient. In this study, Heat transfer coefficient is compared with air velocity, spray flow, heat exchanger type.

• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.165-170
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• 2004

It used the flow system of the stone polishing machine head and it developed a multi axis whetstone polishing system. With the result, the defect by line contact polishing does not occur in both ends of the stone, and it came to trim smoothly. As the index of the surface roughness decreased to 3.6 times, the polishing effect improved greatly. It decreased greatly the dust and a noise with the wet polishing, and the factors of the duty evasion at production site were solved with the work environment improvement against the polishing process of the stone industry and work intensive reduction.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.2
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• pp.133-139
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• 2010

PC camera-based instant messenger have problems of video image break/delay and noise. The reason is caused by a composed problem that PC Camera is belong to the connected PC and operating in the PC. This research suggests an instant messenger that uses network camera connected to LAN instead of PC camera. Therefore, the instant messenger has a component that the camera is separated from PC. This research designs sequence diagram, video calls flow chart, and graphic user interface of the instant messenger. The instant messenger based on network camera provides high quality video calls service and makes it possible to call from a special remote site with real-time video image.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.949-952
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• 2006

An understanding of rheological property on cement paste is one of the important factor to design concrete such as High-fluidity Concrete (HFC) for a specific application. The HFC is a specially proportioned hydraulic cement concrete that enables the fresh concrete to flow easily into the forms and around the reinforcement and prestressing steel without vibration and segregation. Use of this type of concrete for the concrete building construction, manufacture of precast, prestressed bridge elements provides the benefits of increased rate of production and safety, reduced labor needs, and lower noise levels. This paper presents the performance of rheological properties of cement paste incorporating domestic high-water-reduced-admixture (HWRA) for an Ultra-high-fluidity concrete (UHFC). Investigation was carried out on cement pastes with combinations of various dosages of HWRA and water/cement ratios.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.12
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• pp.1236-1248
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• 1991

A new fast algorithm for computing the discrete cosine transform(DCT) Is developed decomposing N-point DCT into an N /2-point DCT and two N /4 point transforms(transpose of an N /4-point DCT. TN/t'and)It has an important characteristic that in this method, the roundoff noise power for a fixed point arithmetic can be reduced significantly with respect to the wellknown fast algorithms of Lee and Chen. since most coefficients for multiplication are distributed at the nodes close to the output and far from the input in the signal flow graph In addition, it also shows three other versions of factorization of DCT matrix with the same number of operations but with the different distributions of multiplication coefficients.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.11
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• pp.1641-1646
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• 2013

Control voltage for baseband channel selection filter to select one of communication channels can be easily fluctuated according to external noise or variation of fabrication. In this paper, we design a voltage regulator with small chip area to keep control voltage constantly using current comparative method. Cut-off frequency of channel selection filter is automatically controlled by detecting current flow using the proposed voltage regulator.

• IE interfaces
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• v.13 no.4
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• pp.717-724
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• 2000

In this paper, an integrated system of optimal design, performance evaluation, and die design and manufacturing of axial fans for cooling tower is presented. The design and performance evaluation are developed based on three dimensional flow analysis so as to ensure low noise and high efficiency. The methodologies are implemented on computer as a GUI system including 3-D surface modeling and 2-D drawing file output modules. The CAD/CAM system is engaged to design the die and generate NC tool path, but the processes are also automated and integrated into the system by means of a part program coded from the design data. It is shown that the newly developed fans have superior performance and shortened lead-time compared to the existing dead-copied fans.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.173-176
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• 1999

Continuing improvement of microprocessor performance involves in the devece size. This allow greater device speed, an increase in device packing density, and an increase in the number of functions that can reside on a single chip. However this has led to propagation delay, crosstalk noise, and power dissipation due to resistance-capacitance(RC) coupling become significant due to increased wiring capacitance, especially interline capacitance between the metal lines on the same metal level. Becase of pattering MSSQ (Methylsilsequioxane), we use RIE(Reactive ton Etching) which is a good anisotrgpy. In this study, according as we control a flow rate of CF$_4$/O$_2$ gas, RF power, we analysis by using ${\alpha}$ -step, SEM and AFM,

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.138-143
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• 2005

Recently, automobile manufacturers regarding stability, economic environmental-friendly problems by the development of automobile, environmental problem as designing the exhaust system. Increasingly strict environmental regulations to lower fuel consumption and reduce emission. Also to reduce the noise and the vibration of the automobile. According to develop variable type muffler, dual muffler and active intelligence exhaust system unit. Improvement in engine performance and fuel consumption rate demand information of pressure fraction and heat characteristics. To be able to determine these factor for we experiment on each case of exhaust system unit. In this study, how back pressure is distributed in flow-through in exhaust system and how to design exhaust system flexibleness, efficiency and combustion charateristics influenced by back pressure. This study furnish basic data for engineers, technicians.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.192-198
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• 2005

Recently, Automobile manufacturers regarding stability, economic environmental-friendly problems by the development of automobile. This reason is increasingly strict environmental regulations to lower fuel consumption and reduce emission. Designing more efficient and low emission control exhaust system results in more efficient Performance, reduced back Pressure and higher convert efficiency. Also to reduce the noise and the vibration of the automobile. According to develop variable type muffler, dual muffler and active intelligence exhaust system unit. Improvement in engine performance and fuel consumption rate, higher conversion efficiency demand information of pressure fraction and heat characteristics. To be able to determine these factor fur we experiment on each case of exhaust system unit. In this study, how back pressure is distributed in flow-through in exhaust system and how to design exhaust system flexibleness, efficiency, lower back pressure and optimal performance. This study furnish basic data for engineers, technicians.