• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.196-201
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• 2001

Electro-Rheological(ER) fluids change their apparent viscosity according to the electric field strength. Therefore, there are many practical applications using the ER fluids. ER effect on the dispersive system of polarizable fine powder/dielectric oil has been investigated. The electrical and rheological properties of starch based ER fluid were reported. Yield stress of the fluids were measured on the couette cell type rheometer as a function of electric fields, particle concetrations, and temperatures. The electric field is applied by high voltage DC power supply, The outer cup is connected to positive electrode(+) and the bob becomes ground(-). And the temperatures the viscosity(or shear stress) versus shear rates were measured. In this experiment shear rates were increased from 0 to 200s$^{-1}$ in 2 minutes. This thesis presents Bingham properties of ER fluids subjected to temperature variations. The temperature dependence of the viscosity was determined for ER fluids consisting of 35 weight % starch particles in automatic transmission oil.

• Korean Journal of Metals and Materials
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• v.49 no.9
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• pp.708-714
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• 2011

The premature failure of a servovalve used for six months in a thermal power plant has been analyzed. The servovalve was made of stainless steel, containing 16Cr-0.44Mo, along with other elements. An overload of oil-supply pumping and an abnormal increase in the oil flux were observed during operation. A study revealed that erosion and corrosion could be the main causes of the failure. The visual examination of the servovalve did not show any appreciable damage. However, corrosion and erosion of the servovalve were observed using scanning electron microscopy (SEM). Upon examination of the servovalve, the corrosion was found to have occurred throughout the bushing and spool; however, erosion occurred at only the edge-side. In addition, the condition of the electrohydraulic control system (EHC) oil was investigated with respect to its satisfaction of the management standard.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.2
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• pp.236-243
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• 1999

This study deals with the application of high speed on-off valves to an electro-hydraulic servo indexing system incorporated electro-hydraulic servo valces. Comparing with the electro-hydraulic servo valve the high speed on-off valve has some merits. Which included low price robustness to the oil contamination and dircect control without D/A converter. The considered sys-tem of this study is controlled by pulse width modulation(PWM) of the control law which is pro-duced by a PID controller which is used broadly in industrial equipments. The dynamic character-istics corresponding to variations of system parameters such as inertia moment system gain and supply pressure are investigated by computer simulation and experiment. Consequently the availability of the application of high speed on-off valve to servo indexing system instead of electro-hydraulic servo valve is confirmed.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.37-43
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• 2008

The durability test of turbo-blower for PEM fuel cell is very important process of BOP development. It is a major barrier to the commercialization of these systems for stationary and transportation power applications. Commercial viability depends on improving the durability of the air supply system to increase the reliability and to reduce the lifetime cost. In this study, turbo-blower supported by oil-free bearing is introduced as the air supply system used by 80kW proton exchange membrane fuel systems. The turbo-blower is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. The impeller of blower was adopted mixed type of centrifugal and axial. So, it has several advantages for variable operating condition. The turbo-blower test results show maximum parasitic power levels below 1.67kW with the 30,000 rpm rotating speed, the flow rate of air has maximum 163SCFM(@PR1.1). For proper application of FCV, these have to durability test. This paper describes the experiment for confirming endurance and stability of the turbo-blower for 500 hours.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1173-1176
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• 2007

The breaker noise is one of the main noise sources of construction site. It is very important to assess and measure the breaker noise accurately, because the noise labelling will be in effect January 2008 in Korea. Therefore, It is necessary to measure the sound power level of breakers and use a appropriate test method in accordance with international standard. In this study, we measure the sound power level of breakers by using the breaker noise measurement system. This system makes it possible to measure the breaker noise more accurately than to measure the noise of that attached with excavator, because this system can control main factors affecting breaker noise such as hydraulic input power, hydraulic supply pressure, breaker inlet oil flow and so on.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.262-265
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• 2004

As a cryogen, LOx is a light blue, odorless, transparent liquid. Also it is not shock sensitive and does not decompose. However, it is a strong oxidizer and will vigorously support combustion. Therefore all harmful contaminants (such as grease, oil, fingerprint and organic materials) that could cause malfunctions, fires, or explosions in a oxygen environments must be completely removed prior to the introduction of oxygen. Especially, grease ingredient located inside of the LOx supply line, pipe and PHS (Pneumo-Hydraulic System) part can make drastic chemical reaction with oxygen. Therefore, to protect rapid reaction such as explosion, grease ingredient must be surely eliminated by a regular and irregular degreasing. Study on the availability, effectiveness and selection of degreasing detergents and method is described in this paper, and it will be useful for the construction and management of IPP test facility.

• Journal of Oriental Neuropsychiatry
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• v.20 no.3
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• pp.1-13
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• 2009

Objectives : The glial cell, located in between the blood vessel and nerve cell, takes charge of the cell support, nutrition supply, elimination of body waste, and cell action. GagamSohabhwangwon(GGSH), a chinese traditional medicinal prescription has been used orally for the treatment of seizures, infantile, convulsion, stroke and so forth. This paper examines the effect of the GagamSohabhwangwon(GGSH) essential oil on cell activity and anti oxidation. Methods : MTT assay methods were employed to measure the cell activity based on the amount of the GagamSohabhwangwon(GGSH) essential oil by using primarily cultivated glial cell. In addition, this paper measured a viability of the glial cell after a protein active retarder control to confirm the multiplication of the cell and examined the cell extinction by the active oxygen, an extinction shielding effect with different amount of the GagamSohabhwangwon(GGSH) essential oil to observe anti oxidation. Furthermore, this paper measured a viability of the cell and phosphorylation(phosphorylation) of the protein which affects the multiplication of the glial cell. Results : When controlling the amount of the GagamSohabhwangwon(GGSH), there was a multiplication effect of the primary glial cell, the multiplication of the cell was dependent on the density of the GagamSohabhwangwon. The multiplication power of the primary glial cell was suppressed by PKA inhibiter (H89). In compliance with the active oxygen the extinction of the primary glial cell was dependent on the density of the GagamSohabhwangwon, there was a shielding effect of the cell extinction when GagamSohabhwangwon(GGSH) was preprocessed. When inducing the multiplication of the primary glial cell, phosphorylation of the Akt, BDNF, CREB, ERK and ERM were increased. Conclusions: Based on the results, GagamSohabhwangwon essential oil will have the effect which activates the nervous system cell and protects the cell through anti oxidation.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.307-322
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• 2014

With the rate of worldwide LNG demand expected to grow faster than that of gas demand, most major oil companies are currently investing their resources to develop floating LNG-FLNG (i.e. LNG FSRU and LNG FPSO). The global Floating LNG (FLNG) market trend will be reviewed based on demand and supply chain relationships. Typical technical issues associated with FLNG design are categorized in terms of global performance evaluation. Although many proven technologies developed through LNG carrier and oil FPSO projects are available for FLNG design, we are still faced with several technical challenges to clear for successful FLNG projects. In this study, some of the challenges encountered during development of the floating LNG facility (i.e. LNG FPSO and FSRU) will be reviewed together with their investigated solution. At the same time, research of new LNG-related technologies such as combined containment system will be presented.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.86-92
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• 2004

This paper describes the properties of temperature-viscosity characteristics of hydrous and anhydrous electro-rheological fluids containing starch and titanium particle in silicone oil ER effects arise from electrostatic forces between the starch particles and titanium particles dispersed to the electrically insulating silicone oil induced when electric field is applied ER fluids under electric field control have been found to provide resonable estimates of ER fluid viscosity variation characteristics. Yield shear stress of the ER fluids were measured the couette cell type rheometer as a function of electrlc fields. The outer cup is connected to positive electrode(+) and bob becomes ground(-). The electrie field is applied by high voltage DC power supply. In this experiment shear rates were increased from 0 to 200 $s^{-1}$ in 2 minutes. The ER fluid's viscosity change is very small and stable at the temperature range of $40^{\circ}C$ to $60^{\circ}C$. Therefore, applications of a new ER fluid to control systems application are suitable.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.670-675
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• 2000

The purpose of the study is development and investigation about basic performance of the system operation on a dual fueled cogeneration system(CGS), which is operated with biogas and gas oil. As often seen in dual fueled CGS performance, the electric generating efficiency was obtained about 26□. Methane contained in the biogas could not bum completely at lower load, and it was discharged into exhaust gas. Considerable amount of the methane burned in the exhaust pipe, and the heat recovery ratio was 42□ on heat balance. As a result, the total heat efficiency, which is a summation of generating efficiency and heat recovery efficiency reached to about 70□. The supply of biogas into the engine reduces smoke density and NOx concentration in exhaust gas. At lower load, methane burned slowly and large portion of it was discharged without burning. Therefore the measures are desirable that promotes combustion of methane at lower load.