• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.29.1-29.1
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• 2008

The temperature control system which is using liquid and gaseous nitrogen has been known as the most economical system to simulate space temperature condition due to relatively not expansive price of the liquid nitrogen (less than 0.2 USD per liter). And, among these systems, the closed loop system which circulates compressed nitrogen gas come from sprayed liquid nitrogen by blower and makes a target temperature with heat from an electrical heater and flow rate of liquid nitrogen is prevail all over the world. But, this complete closed loop system requires expansive equipments such as blower, heater, and liquid nitrogen injector, and special maintenance on the system. Therefore, KARI is developing efficient and simple open loop system which utilizes liquid and gaseous nitrogen with eliminating a special blower and other expansive units. In this study, this open loop system with more efficiency and flexibility will be designed and introduced.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2850-2855
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• 2008

Very High Temperature Reactor (VHTR) has been selected as a high energy heat source for a nuclear hydrogen generation. The VHTR heat is transferred to a thermo-chemical hydrogen production process through an intermediate loop. Both Process Heat Exchanger and sulfuric acid evaporator provide the coupled components between the VHTR intermediate loop and hydrogen production module. A small scaled Compact Nuclear Hydrogen Coupled Components test loop is developed to simulate the VHTR intermediate loop and hydrogen production module. Main objective of the loop is to screening the candidates of NHDD (Nuclear Hydrogen Development and Demonstration) coupled components. The operating condition of the gas loop is a temperature up to $950^{\circ}C$ and a pressure up to 6.0MPa. The thermal and fluid dynamic design of the loop is dependent on the structures that enclose the gas flow, especially primary side that has fast gas velocity. We designed and constructed a small scale sulfuric acid experimental system which can simulate a part of the hydrogen production module also.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1504-1511
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• 2005

The efficiency of the hydraulic transport of soil-water mixtures is an important factor in designing and operating a pump & pipeline system and is directly connected with dredging cost and working period. However, the hydraulic transport mechanism in the slurry flow inside the pipeline such as frictional losses, specific energy consumption, deposition velocity has not been well established. In this study a new dredging test loop system was designed and built. It is composed of a slurry pipeline with pipes of different diameters, a centrifugal slurry pump and a diesel engine connected with the slurry pump. and equipped with modern measuring facilities that enable to measure all important characteristics of a transportation system. The objective of this paper is to discuss the efficiency of the hydraulic transport of the Jumoonjin sand-water mixtures in the dredging test loop and to present simple equations induced from the test results of the loop that can express the transport product and the transport productivity.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.8
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• pp.669-672
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• 2004

This paper considers the implementation and experiments of an open-loop Cylindrical Vibratory Gyroscope(CGV). An open-loop CGV composed of thin cylindrical vibrating element, electromagnetic drive and pick-off element with open-loop control was designed and fabricated. The experimental performance tests of the open-loop CGV were done using a temperature chambered rate table. Also, the limitations of open-loop CGV were analyzed and the solution for the limitations was proposed.

• Advances in concrete construction
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• v.6 no.5
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• pp.527-543
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• 2018

Crack control of precast members is crucial for durability. However, there is no clear provision to check the crack width of precast joints. This study presents an experimental investigation of loop joint details for use in a precast bridge deck system. High strength concrete of 130 MPa was chosen for durability and closer joint spacing. Static tests were conducted to investigate the cracking and ultimate behavior of test specimens. The experimental results indicate that current design codes provide reasonable estimation of the flexural strength and cracking load of precast elements with loop joint of high strength concrete. However, the crack width control of the loop joints with high strength concrete by the current design practices was not appropriate. Some recommendations to improve crack control of the loop joint were derived.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.601-606
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• 2004

Vibration spectrums of the test loop according to flow conditions were analyzed in order to identify the sources of vibration at peak frequencies. While a flow condition of the sweep test was changed by varying pump rotational speed from 450 rpm to 1500 rpm by the step 150 rpm, midspan acceleration of the test section in width-direction and dynamic pressure perturbation in the test section were measured. Other sources of vibration due to the flow structure interactions, such as acoustic resonance, blade pulsing frequency and bellows wrinkles, were investigated. Pressure perturbation in the section and acoustic resonance due to branch pipe give major effects to the vibration of the test section in high frequency range of 1.5 kHz to 2.8 kHz.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.15-18
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• 2008

This study fulfilled analysis of startup characteristics of Turbo pump unit-Gas generator open loop test from the viewpoint of simulation. The test results were investigated and the calculated results were compared to test results. The curve for RPM developing predicted by simulation agreed well with test result. The slope of transient combustion pressure of gas generator correspond with test result.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.19-22
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• 2008

This study fulfilled analysis of startup characteristics of Turbo pump unit-Gas generator closed loop test from the viewpoint of simulation. The test results were investigated and the calculated results were compared to test results. The curve for RPM developing predicted by simulation agreed well with test result. The slope of transient combustion pressure of gas generator correspond with test result.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.444-447
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• 2008

A nuclear fuel test loop (after below, FTL) is installed in IR1 of an irradiation hole in HANARO for testing neutron irradiation characteristics and thermo hydraulic characteristics of a fuel loaded in a light water power reactor (PWR) or a heavy water power reactor (CANDU). There is an in-pile section (IPS) and an out-pile section (OPS) in this test loop. When HANARO is normally operated, the fuel loaded in the IPS has a nuclear reaction heat generated by a neutron irradiation. To remove the generated heat and to maintain an operation condition of the test fuel, a main cooling water system (MCWS) is installed in the OPS of the FTL. The pump can not continuously suck a fluid and not pressurize the fluid during a cold function test. To verify the flow characteristics of the MCWS, a flow net work analysis has been conducted. When the higher elevation pipelines wholly filled with coolant, it was confirmed through the analysis results that the pump pressurized the coolant normally. And the analysis results described the system characteristics with operation temperature and pressure variation satisfactorily.

• International Journal of Control, Automation, and Systems
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• v.5 no.1
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• pp.35-42
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• 2007

This paper presents an INS(Inertial Navigation System) grade, surface micro-machined differential resonant accelerometer(DRXL) manufactured by an epitaxially grown thick poly silicon process. The proposed DRXL system generates a differential digital output upon an applied acceleration, in which frequency transition is measured due to gap dependent electrical stiffness change. To facilitate the resonance dynamics of the electromechanical system, the micromachined DRXL device is packaged by using the wafer level vacuum sealing process. To test the DRXL performance, a nonlinear self-oscillation loop is designed based on the extended describing function technique. The oscillation loop is implemented using discrete electronic elements including precision charge amplifier and hard feedback nonlinearity. The performance test of the DRXL system shows that the sensitivity of the accelerometer is 24 Hz/g and its long term bias stability is about 2 mg($1{\sigma}$) with dynamic range of ${\sigma}70g$.