• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.128-134
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• 2013

A 2-way solenoid valve regulates to maintain the pressure of ullage volume of propellant tanks when the command is given by control system for the liquid-propellant feeding system of space launch vehicle. The simulation model of solenoid valve for pressurization is designed with AMESim to verify the designs and evaluate the dynamic characteristics and pneumatic behaviors of valve. To improve the accuracy of the model, numerical flow analysis by using FLUNET code. The simulation results of their operating durations of valve by AMESim analysis are matched up with the results of experiments and validate valve model. Using the model, we analyze performance of valve; opening/closing pressure, operating time on various design factors of basic valve and control valve; geometrical size of valve seat, ratio of basic valve and sealing area.

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.10-19
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• 2020

Valve leak accidents in petrochemistry plants and gas utilities cause human and property damage. The main reason why happen gas inhalation, poisoning, fire and explosion accidents is gas valve leakage. To prevent gas leakage, inspectors check the facilities in the field. And they are at risk of gas leak accidents. So we applied IoT-based risk assessment, monitoring and automatic control system. It can detect both internal and external gas leakage, do real-time monitoring of industrial valve in the plant by using hybrid sensor. As the new safety management system for industrial valve is developed, it needs method to evaluate device performance and environmental components for the system. This study is about development of method to verify performance of the explosion-proofed hybrid sensing system include gas detector and optical fiber sensor supporting wire and wireless communication.

• ICROS
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• v.5 no.1
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• pp.35-40
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• 1999

• Journal of Korean Society of Water and Wastewater
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• v.35 no.1
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• pp.15-25
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• 2021

In this study, a method of leakage detection was proposed to locate leak position for a reservoir pipeline valve system using wavelet coherence analysis for an injected pressure wave. An unsteady flow analyzer handled nonlinear valve maneuver and corresponding experimental result were compared. Time series of pressure head were analyzed through wavelet coherence analysis both for no leak and leak conditions. The leak information can be obtained through either time domain reflectometry or the difference in wavelet coherence level, which provide predictions in terms of leak location. The reconstructed pressure signal facilitates the identification of leak presence comparing with existing wavelet coherence analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.96-103
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• 2005

The main purpose of launch vehicle is to insert satellite into a target orbit safely and correctly. To accomplish the main purpose of launch vehicle, the inserting velocity, inserting angle, and final mass of launch vehicle should be within the allowable range. In general, such requirements are satisfied with applying TCS(Thrust Control System) and TDS(Tank Depletion System), which manage thrust and mixture ratio by controlling propellant flow rate with thrust and mixture ratio control valves. In this study, the control characteristics of thrust and mixture ratio control valve were examined by PID control logic for stable operation of liquid-Propellant rocket engine at on-dosing point. The analysis on the control characteristics of control valves was done with AMESim code and the results from control valve test facility at KARI.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1193-1198
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• 2011

The solenoid valve used in fuel cell system need to have good sealing performance because the work fluid can explode in the system. Moreover, the temperature of the work fluid is extremely high in order to maintain the properties of the rubber ring that seals the solenoid valve. This study deals with the rubber ring which is made from a fluoro-elastomer. The life cycle of the rubber ring was estimated by the relational expression of Arrhenius, and the solenoid valve was tested to confirm the sealing characteristics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.732-736
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• 2016

Air conditioning part designs are moving towards higher efficiency and productivity. The expansion device is one of the core parts of an air conditioning system and controls the refrigerant quantity, evaporation load, compression capacity, and condensation capacity. In this study, an electronic expansion valve for two working fluids ($CO_2$ and R134a) was developed for air conditioning systems in vehicles. The valve uses an eccentric cam driving structure instead of a lead screw to decrease manufacturing costs and increase productivity. The pressure resistance and flow rate performance was evaluated using numerical analysis. At maximum operation conditions and burst pressure conditions with $CO_2$, the maximum stresses on the valve model were about 98 MPa and 223 MPa, respectively. The maximum flow rates of $CO_2$ and R134a with different orifice openings were about 550 kg/h and 386 kg/h, respectively. The performance with R134a was verified by experiments.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.5
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• pp.369-374
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• 2021

Apartment recently built in kitchen is made is made because the gas hose with built-in ways invisible inside the sink. In this case, if the gas leaks, it is a dangerous method that can accumulate inside the sink and lead to an explosion. In this study, since the hose connected between the gas range and the intermediate valve is inside the sink, it is not possible to test for gas leaks, so a valve system that can easily check for gas leaks using a pressure sensor was studied. As for the pressure measurement method, the pressure of the hose connecting the intermediate valve and the gas range was measured so that data could be collected and analyzed using the I2C communication method. In addition, the calculation of the gas pressure supplied to the home was investigated for the atmospheric pressure error for the value calculated by adding the average value of the gas gauge pressure of 22.46 mbar at the inlet of the gas meter to the atmospheric pressure. A valve system was developed to detect minute gas leaks.

• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.140-148
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• 2009

MOV(Main Oxidizer shut-off Valves) control the combustion of launch vehicle systems by the supply and the isolation of liquid oxygen to a main combustion chamber in launch vehicle systems. Moreover, in the steady operational state, the MOV should secure a constant flow rate of liquid oxygen for combustion instability in the combustion chamber. Concerning the development of MOV, TM(Technology Model) has been manufactured and normal operations of the valve have been verified. However, the Cv of TM has been proved to be too low as compared with a design specification value. Therefore, CFD analysis have been performed by modification of the configurations of TM in order to increase sufficiently Cv of EM(Engineering Model), which is the following model of TM. The modifications of TM configurations such as partial scale-up of valve, increase of stroke length, and outlet angle of 120o would result in a considerable augmentation of Cv. It has been verified by flow capacity tests that the improved Cv of EM is min. 212, which is higher than Cv of TM, 161 by about 32%.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1100-1106
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• 2009

Recently, there are quite a lot of attention is drown on the researches related to of Miller method applied high expansion cycle. For this study, high expansion cycles are formed and analyzed with the base view point of thermodynamics, and the features of each factors are also investigated. As a result of analysis, the expansion-compression ratio is expected with a decrease of effective compression ratio as intake valve closing time retarded, however, the decrease of mean effective pressure and its output is accompanied with the counterflow of intake air. Accordingly, as the consequence of such failure, it is expected that an alternative is needed for the realization of high expansion cycles, and the improvement over thermal efficiency. To materialize such cycle, the control system to delay the closing time of intake valve was designed and VVT, the 3 S/B low speed diesel engine, is applied to evaluate the efficiency. The result of the trial shows that there was no significant errors.