• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.104-110
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• 2005

GIS(Gas Insulated Switchgear) is used in electric power system, to insure non conductivity, breaking capacity and operating reliability. The commercial dynamic analysis code COSMOS MOTION and 3-D modeling program SOLID WORKS were used to simulate dynamic analysis of the closing resistors of the GIS in this paper. To reduce chatter vibration of closing resistors, the motion of moving and fixed parts of closing resistors were simulated by varying the spring constant, the damping coefficient and the mass of moving and fixed parts. The simulated results were compared with experimental results. As a result, chatter vibration of closing resistors of the GIS could be reduced by using the results. These data can be used to determine the spring constant, the damping coefficient and mass of a moving part to reduce chatter vibration when the next model is developed.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1607-1613
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• 2006

GIS (Gas Insulated Switchgear) is used in electric power system to insure non conductivity, breaking capacity and operating reliability. In the present study, dynamic analysis on the closing resistors of the GIS has bees carried out by the commercial dynamic analysis code COSMOS MOTION and 3-D modeling program SOLID WORKS. In order to find the minimum value of chatter vibration of closing resistors, the motion of moving and fixed resistor parts of closing resistors were simulated by varying the spring constant, the damping coefficient and the mass of moving and fixed resistor parts. The simulated results were compared with experimental results. The application of the results could reduce chatter vibration of closing resistors of the GIS. These data are also useful on the development of future model GIS with minimum chatter vibration for the determinations of the spring constant, the damping coefficient and mass of a moving part.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.535-542
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• 2013

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor using bed inserts, effect of bed insert geometry on CO conversion of WGS catalyst was measured and investigated. Small scale fluidized bed reactor was used as experimental apparatus and tablet shaped WGS catalyst and sand particle were used as bed materials. The cylinder type and the spring type bed inserts were used to hold the WGS catalysts. The CO conversion of WGS catalyst with the change of steam/CO ratio was determined based on the exit gas analysis. Moreover, gas flow direction was confirmed by bed pressure drop measurement for each case. The measured CO conversion using the bed inserts showed high value comparable to previous results even though at low catalyst content. Most of input gas flowed through the bed center side when we charged tablet type catalyst into the cylinder type bed insert and this can cause low $CO_2$ capture efficiency because the possibility of contact between input gas and $CO_2$ absorbent is low in this case. However, the spring type bed insert showed good reactivity and good distribution of gas, and therefore, the spring type bed insert was selected as the best bed insert for SEWGS process.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.18-23
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• 2018

This study tries to analyze the injection amount of injector according to the external environment temperature of CNG vehicle. Especially, We investigated the effect of low temperature environment on gas injector performance by measuring the variation of injection amount under the same conditions as in coldstart condition. This experimental compared two products with different spring characteristics. The experimental device consist of a fuel supply unit, a flowrate measurement unit, a temperature chamber, and an injector control unit (ECU). According to the test result, the initial injection amount of the injector is increased in the low temperature environment and the needle opening time is delayed according to the change of the spring length.

• Plant Resources
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• v.8 no.2
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• pp.91-95
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• 2005

In spring, to determine the optimal planting date and plant density of rapeseed in southern areas of Korea. $Taiwan^{\#1}$ variety for spring sowing, the highest yielding variety was grown under five different planting date and plant density. Yield components such as plant height, ear length, number of seedling stand per $m^2$, number of per ear and seed set percentage were highest at the plots with Mar. 5 of planting date and 50/20cm drilling of plant density. Yield of seed, oil, gas and 1,000 grains weight and erucic acid content were highest at the Mar. 5 of planting date and 50/20cm drilling of plant density. Judging from the results reported above, at optimum planting date and plant density of rapeseed seemed too be Mar. 5 of planting date and 50/20cm plant density in spring sowing.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.682-687
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• 2001

This study represents effect of exhaust performance by according to active muffler valve spring. The experimental parameter were divided engine speed and torsion coil spring constant. The sound pressure level was generally low at engine speed 2000-2500rpm but That was showed the lowest at spring constant k=0.75. Flow speed of exhaust gas was showed the fast at spring constant k=0.75 but the low value was showed at k=0.97. It was contained a rather low concentration of carbon monoxide(CO) at engine speed 2000-2500rpm and k=0.81, low concentration of hydrocarbon(HC) at spring constant k=0.81 but that was high at spring constant k=0.97. A conclusion based on FFT analysis was generally low concentration value at k=0.79 and k=0.81. The temperature distributions into the muffler was shown similar conditions. Heat transfer was well spreaded at thermocouple No.8 because valve was opened.

• Journal of the Korean Institute of Gas
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• v.4 no.1 s.9
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• pp.63-68
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• 2000

We have developed a new relief valve which is a safety device for the domestic gas-fired hot water boilers. The relief valve has been designed to expand the inner diameter of the inlet, the outlet and the seat of the valve considering the relief capacity, and also to separate the spring from the room heating water. Therefore, we could minimize the adhesion and/or obstruction of the inlet and the corrosion phenomena of the spring which used to be the problem of the conventional relief valves. Test results of the developed relief valve showed that the performance of the opening pressure, reseating pressure, tightness, endurance were excellent, and the operating boiler with developed relief valve was evaluated as very good. The standardization and application of the relief valve can provide the advantage of component exchange and easy maintenance and repair.

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.329-334
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• 2006

This paper presents the evaluation of LPG (Liquefied petroleum gas) regulators for home use. For the evaluation, several properties of the regulators were experimentally analyzed, such as the operation of safety device, the adjusting and lock-up pressure, the adjusting spring and the diaphragm, with respect to the used time of the regulators. Experimental results showed that the initial operation performances of regulators were degraded with increase of the service time and also showed that the degradation of the performance and material property could become serious after about six-year-use of the regulators.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.5
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• pp.390-396
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• 2017

In this paper, an exact mathematical model is derived for an exhaust gas recirculation (EGR) valve actuator driven by an H-bridge converter. Particularly, a spring torque model of the EGR valve is proposed. The spring torque model is proposed by converting spring force and Coulomb frictional force in linear motion into a rotational torque. Moreover, a mechanical end-stop model was proposed by the valve mechanism. The accuracy of the proposed model is verified by comparing the experimental results with the simulated results.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.435-443
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• 2023

Global concern over climate change, driven by greenhouse gas emissions, has prompted widespread interest in sustainable solutions. In the agricultural sector, biochar has emerged as a focal point for mitigating these emissions. This study investigated the impact of continuous biochar application on CO₂ and N₂O emissions during the spring cabbage cultivation period. Greenhouse gas emissions in the biochar treatment groups (soils treated with 1, 3, and 5 tons/ha of rice husk biochar) were compared to those in the control group without biochar. During the spring cabbage cultivation period in 2022, the total CO₂ emissions were in the range of 71.6-119.0 g/m² day, and in 2023, with continuous biochar application, they were in the range of 71.6-102.1 g/m² day. The total emissions of N₂O in 2022 and 2023 were in the range of 11.7-23.7 and 7.8-19.9 g/m² day, respectively. Overall, greenhouse gas emissions decreased after biochar treatment, confirming the positive influence of biochar on mitigating greenhouse gas release from the soil. Nevertheless, further research over an extended period exceeding five years is deemed essential to delve into the specific mechanisms behind these observed changes and to assess the long-term sustainability of biochar's impact on greenhouse gas dynamics in agricultural settings.