• Journal of the Society of Naval Architects of Korea
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• v.36 no.1
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• pp.22-29
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• 1999

In the development of high speed marine vehicle, lilting devices became important in sharing the pay load or controlling the attitude. The devices are also important to meet the IMO regulation to prevent the marine pollution by keeping the high rudder force for VLCC even in low speed operation. The high lift devices such as the Coanda device have been introduced to the aircraft as a common practice for a long time among the aero-engineers. If the Coanda device can be utilized to the flapped rudder, the severe requirement of rudder force could be provided for the VLCC in low speed operation. The performance of the rudder system has been investigated at the towing tank of Seoul National University.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.132-138
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• 2006

A tape feeder is an important part to supply a micro chip such as 1005 and 0603 components in SMT process. Traditional sprocket wheel type feeder has several problems such as backlash and indexing errors, low compatibility and confidence. However, it is very difficult to solve such problems due to the inevitable fraction defectives of sprocket wheel. Thus, the object of this works is to develop a linear type high precision tape feeding system using cam-slider mechanism. The proposed cam-slider mechanism is composed of several links and a plate, pneumatic actuator is used to generate linear motion. The proposed mechanism has distinct advantages over the conventional mechanism. It has reduced feeding errors, long lift-cycle, and slim width. As a result, the developed tape feeder using cam-slider mechanism shows special characteristics far high precision feeding for chip-mounters.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.176-179
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• 2005

The increasing demand for high density packaging technologies and the evolution to mixed digital and analogue devices has been the con-set of increasing research in thin film multi-layer technologies such as the passive components integration technology. In this paper, Cu and TaO thin film with RF sputtering was deposited for spiral inductor and MOM capacitor on the $SiO_2$/Si(100) substrate. MOM capacitor and spiral inductor were fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, important devices for mobile communication system. Based on the high-Q values of passive components, MOM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and 5 dB for a 900 MHz filter. This paper also discusses a analysis and practical design to thin-film L-C band pass filter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.373-377
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• 2003

Recently, advanced manufacturing systems with high speed and intelligence have been developed for the betterment of machining ability. In this case, reliability prediction work with motion characteristic evaluation of sliding cover(C-plate, Bellows, etc) has also important role from design procedure to manufacturing and assembly process. Accordingly in this study, H/W test-bed system for reliability evaluation of sliding cover has been developed to obtain proper reference data for design of new model, prevention trouble (failure mode), and improvement of quality and lift cycle extremely for advanced mother machinery.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.451-456
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• 2005

The mathematical model for the heat exchangers of absorber and desorber is made in the elementary control volume method and the thermodynamic properties of working fluid. water/ammonia mixture. are calculated by some fundamental subroutines in RefProp 7.0 and flash subroutines made by authors The simulation results show that two-stage cycle has higher COP than single stage if temperature lift is high: the performance of single stage compression cycle can be improved by increase of absorber pressure. but the performance of two-stage compression cycle can not be improved in this way : the compressor discharging temperature of two-stage compression is much lower than that of single stage cycle. which is very important to the safety operation of CA heat pump. Major parameter comparison between the cycles at their optimal configurations is also given.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2005.05a
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• pp.62-69
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• 2005

Maneuverability of ships has been receiving a great deal of attention both concerning navigation safety and the prediction of ship maneuvering characteristics, to improve it. High-lift device could be applied to design of rudder at design stage. Now, we carried out the flow visualization and inversitgation of flow around a flap rudder (trailing-edge flap). Flow visualization results of flap defection shown as the flow around a NACA0020 Flap Rudder will be conducted in a Circulating Water Channel. The purpose of this investigation will be to investigate the development of the separation region on the flap rudder with the variation of angle of attack and determine the angle of attack at which the flow separates and reattaches.

• Journal of computational fluids engineering
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• v.17 no.2
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• pp.100-106
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• 2012

Ice accretion on the surface of aircraft in flight can adversely affect the safety of aircraft. In particular, it can cause degradation of critical aircraft performances such as maximum lift coefficient and total pressure recovery factor in engine air intake. In this study, computational prediction of ice accretion around a rotorcraft air intake is conducted in order to identify the impingement region with high droplet collection efficiency. Then the amount of ice accretion on the air intake, which is essential in determining the required power of ice protection system, is calculated. Finally, the effect of icing wind tunnel size is investigated in order to check the compatibility with the real in-flight test environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.7
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• pp.561-566
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• 2014

Our Korean traditional cultural inheritance Bangpae Kite has the stable rectangular shield shape decorated with artistic paint or poem and a good flight performance due to the central wind hole. In this paper, to analyse the wind hole effect to kite performance we performed the wind tunnel testing of the various design factor of kite model and air flow visualization passing through the wind hole. As the result of aerodynamic analysis, we knew that the wind hole of kite displays similar function of slot system for the wing high lift device. This fact demonstrates that our ancestor understood the function of slot system and applied effectively to the development of kite flight performance.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.35-40
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• 2005

Maneuverability of ships has been receiving a great deal of attention both concerning navigation safety and the prediction of ship maneuvering characteristics, to improve it. high-lift device could be applied to design of rudder at design stage. Now, we carried out the flow visualization and investigation of flow field around a flap rudder(trailing-edge flap). Flow visualization results of flap defection shown as the flow around a NACA0020 Flap Rudder will be conducted in a Circulating Water Channel. The purpose of this investigation will be to investigate the development of the separation region on the flap rudder with the variation of the angle of attack and determine the angle of attack at which the flow separates and reattaches.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.7
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• pp.350-359
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• 2017

Premixed burner is a very strong candidate in household condensing gas boiler burner system because it has low CO and NOx emission with high thermal efficiency. The objective of this study was to determine combustion characteristics of cylindrical premixed burner using different baffle plate and flame holes. Results showed that cylindrical premixed flame mode could be changed into lift-off flame, blue flame, red flame, and green flame with increasing equivalence ratio. In particular, blue flame was found to be very stable at heating load of 8,82~35,280 kcal/h. NOx emission was under 26 ppm between 0.775 to 0.813 of equivalence ratio. CO emission was under 58 ppm under the same equivalence ratio. Thermal efficiency, a very important index in condensing gas boiler, was found to be above 90.13% under the same equivalence region.