• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.2
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• pp.126-133
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• 2007

Lately, there exist growing demands to increase the firepower of mid-calibre automatic guns despite spatial limitations of armament. In this context, ammunitions of simple cylindrical shape are considered so advantageous that associated automatic guns are under development incorporating an intermittently rotating chamber mechanism. In this paper, relevant subsystems for such guns are to be described, and a digital controller to automate the entire system as well. Via dynamic simulations it proves to function well being able to drive the chamber at any constant speed up to 200spm, which is merely limited by the recoil performance. It is remarkable that the system synchronization idea in use is applicable to any other multi-actuator systems that should operate on the basis of event rather than time.

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.49-53
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• 2013

In this paper, we proposed a laser-based non-contact temperature measuring method for high speed rotating polycarbonate (PC) disk using transparency change of thermocolor. The thermocolor has abilities to change color and transparency due to a change in temperature. The thermocolor is applied on one side of polyvinylidene fluoride (PVDF) membrane. The thermocolor applied membrane is attached to inside of reaction chamber in disk. An optical system consisted of a laser beam radiator and a laser photometer is installed. Laser is irradiated at the bottom side of disk and the transmitted laser beam is detected by the laser photometer at the opposite side of disk. During the disk is rotating, laser is irradiated and detected simultaneously. The laser photometer senses the transmitted laser power and generates voltage as output. The temperature of disk can be detected during the disk is rotating up to 3000 RPM.

• Journal of the Korean Society of Visualization
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• v.11 no.2
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• pp.34-40
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• 2013

A flow visualization near submerged nozzle of solid rocket motor was conducted by experiments. A numerical simulation was also performed to reveal detailed phenomena. Radial cold flow simulating hot gas was introduced by a porous grain model which was manufactured by perforated steel plates. The grain model was mounted in high-pressure chamber which has quartz glass at the top of the grain model. From the high-speed images, a rotating vortex was observed and the two type of counter-rotating momentums were generated in numerical results. The rotating momentum was generated at the fin-slot grain because of unbalance between high-velocity flow from slots and low-velocity flow from fin-bases. As a result, roll torques can be produced by the rotating vortex tube.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.998-1003
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• 2003

The aerodynamically excited vibration and natural frequency of rotating CD and DVD disks are analytically and experimentally studied in this paper The theoretical analysis uses a fluid-structure model where the aerodynamic effects are represented in terms of elastic, lift and damping components. The explicit expression on natural frequency of the air coupled disk is obtained as functions of the three aerodynamic coefficients. The experiments performed using a vacuum chamber and CD/DVD disks rotating in vacuum, open air and enclosure give three main results. One is that the aerodynamic effect by the surrounding air reduces the natural frequencies and critical speeds of the vibration modes. The second is that natural frequency of disks rotating in open air is larger than that in enclosure. Finally, it is shown that the disk vibration is reduced as the gap between the disk and the rigid wall decreases.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.16-23
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• 2001

Spray dispersion in high pressure diesel engines have been simulated experimentally with a special emphasis on the effect of swirl by using a liquid injection technique. A constant volume chamber was designed to be rotatable in order to generate a continuous swirl and to have the flow field closely resembling a solid body rotation. Emulsified fuel was injected into the chamber and the developing process of fuel sprays was visualized. The effect of swirl on the spray dispersion was quantified by calculating non-dimensionalized dispersion area according to the spray tip penetration length. The results show that the effect of swirl on the spray dispersion is different between short and long spray penetrations. For short range of spray tip penetration, the effect of swirl on spray dispersion is quite small. However, as the spray tip is penetrated into longer distance in spray chamber, the effect of swirl on spray dispersion becomes larger. These results can be used as a basic data for designing combustion chamber and injection system of direct injection diesel engine.

• The KSFM Journal of Fluid Machinery
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• v.1 no.1 s.1
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• pp.58-63
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• 1998

To investigate turbine flow fields under realistic conditions, a rotating turbine test facility has been developed at the Inha University Propulsion Laboratory. The experimental facility consists of an air inlet, settling chamber, single turbine stage test section, and diffuser. This turbine has a design flow coefficient of 0.55 and work coefficient of 1.88. The turbine test rig has four features. First, a large scale test section improves space resolution. Second, low speed rpm enhances safety and reduces required power, Third, DC motor/generator is able to regenerate blower power. Fourth, various types of experiment can be carried out.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.362-367
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• 2001

A reciprocating compressor unit with variable rotating speed driven by BLDC motor is mounted inside hermetic chamber on an internal suspension composed of 4 coil springs and a discharge pipe. A method for predicting the dynamic behavior of compressor frame is required to reduce the transmitted vibration level. Mechanical characteristics such as mass, spring and discharge pipe stiffness properties are obtained with experimentation. To confirm the vibration model for compressor frame, free vibration analyses are performed with theoretical and experimental methods. Results for analytical and experimental investigations on dynamic behavior of the compressor frame are presented, and the agreement between measured and predicted results are satisfactory.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.18-19
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• 2005

EDDC(Evaporation using Drum in Dual Chamber) deposition system was manufactured for 100m long superconducting coated conductor. It is composed of reaction chamber, evaporation chamber and differential chamber. The drum is located across the differential and exposed to both of the evaporation chamber and the reaction chamber, and the tape is wound on the drum. The elements of superconducting material are co-evaporated from respective element boats in the evaporation chamber and deposited on the drum and reacted with oxygen in the reaction chamber. This process repeats by rotating the drum. When the total pressure of the reaction chamber was 5 mTorr, that of the evaporation chamber was $5{\sim}10^{-5}$Torr. This atmosphere can be achieved by means of differential pumping. There are four evaporator in the evaporation chamber. One is the radiation heating evaporator and the others are the high frequency induction evaporator. EDDC is one of promising methods for commercialization of superconducting coated conductor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1369-1370
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• 2013

• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.1051-1060
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• 2001

Flow visualizations and hot-wire measurements on the inside flows of two different incubators are presented in this paper. An anatomically-correct neonate model was fabricated using the rapid prototyping machine, based on the 3-D scanned data. The result showed that air flow in the incubator was affected not only by the air circulation system but also by the design of incubator chamber. Large rotating motions were located around the corners of free space. A number of small eddies were found in regions of high shear flow, in areas such as that between the air inlet and the neonate. But, these small eddies were found to be stationary at that locations. Those small eddies might interfere with convective and evaporative heat transfers from the neonate. This study has led to a better understanding of flow mechanism in an incubator chamber and provided the guidance needed for the advancement of improved computational fluid dynamic models.