• Proceedings of the KIEE Conference
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• summer
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• pp.785-787
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• 2004

The purpose of this paper is characteristic analysis of permanent magnet generator for AVR power of brushless synchronous generator. However, the PMG has a spoke type rotor with overhang, so we perform the analysis considering overhang for the precise airgap flux density. In this paper, dynamic analysis model with 2D FEM considering overhang is proposed by use of 2D, 3D static FEM results. The proposed method is verified by the results of PMG load test.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.177-183
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• 2010

Bum-type $CO_2$ generators are widely used in greenhouses for the purpose of $CO_2$ supply for photosynthesis and greenhouse heating. However harmful gases included in the air might give severe effects on the plant growth. For investigating the possible emission of harmful gases from commercial bum-type $CO_2$ generators, we carried out the analysis of the harmful by-products (NO, NOx, $NO_2$, CO, and VOCs) and $CO_2$ caused by using a bum-type $CO_2$ generator in greenhouses. And the harmful by-products from different type of fuels such as kerosene, LPG, and LNG were quantified. In order to minimize the uncertainties from a $CO_2$ generator, 4 different $CO_2$ generators were utilized in four plastic greenhouses and a glasshouse located at different places during the experimental works. The results showed that the concentration of NOx is proportional to $CO_2$ concentration. Levels of harmful gases in the most of greenhouses, where the new bum-type $CO_2$ generators were installed, were lower than 1.0 ppm when $CO_2$ concentration was set at 1,000 ppm. In case of LNG combustion, the concentration of CO reached out up to 300 ppm and pre-treatment for CO reduction, such as the adsorption process, would be inevitable to abate the adverse effects on plant growth.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.439-445
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• 2013

This study is on the system that can integrate generator and charger to use as a welder and generator for need. Specifically, it was hybrid generator consisted with select switch to use generator controller and multiple function welder, that function were auto-stopping generator when generator power finish to recharge in recharger battery and Co2 MMA TIG MIG MAG are devide depend on supplying gas. This control system of voltage, high-frequency, motor and gas valve was implemented in order to improve the performance and convenience of existing welders to choose only one or two at a time.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.391-394
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• 2008

Global warming and air pollution have increased the amount $CO_2$ in the atmosphere. In order to decrease the amount of $CO_2$, lots of researches are conducted toward using Hydrogen energy. Because of its high efficiency energy level and environmental friendly features, many companies have researched on developing hydrogen engine system and distributed generation system. Especially, the focus of this research provides the operation method of linear generator for hydrogen fuel combustion linear engine. During an ignition, linear generator is operated by motor to create the initial condition of engine combustion. Once the engine combustion is stabilized, the generator supplies electric power to grid. In order to stabilize the engine, linear generator is required to control mover frequency, direction, and force; Hence the PCS(Power Conversion System) place three H-bridge type inverter stacks in parallel to control phase current independently. As well, by using Back-to-Back method, it can receive electric power from both end.

• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.111-116
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• 2018

This study were carried out to evaluate the efficiency of using burn-type $CO_2$ generators in greenhouse for cultivation 'Seolhyang' strawberry ($Fragaria{\times}ananassa\;Duch.$) during winter season. The concentration of $CO_2$ was 200 to $600{\mu}mol{\cdot}mol^{-1}$ in the control, and 800 to $1,100{\mu}mol{\cdot}mol^{-1}$ in using burn-type $CO_2$ generator between 6 and 11 hours. At other times, it was observed that at similar concentration in the control and using burn-type $CO_2$ generator. Measured greenhouse air temperature inside the of using burn-type $CO_2$ generator was $2{\sim}3^{\circ}C$ higher than the control at 6 ~ 10 am. There was no temperature difference between treatments after 11 o'clock. Plant height, leaf length, leaf width, root diameter, fresh weight, and dry weight were not different between treatments. The marketable yield (kg/10a) of using burn-type generator were 4,131 kg, which was 519 kg higher than the control. Therefore, the total fruit yields increased 17% compared to the control.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.205-207
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• 1994

This paper presents an analyzing method of the distortion factor of the output voltage in generator on the basis of the stator coil flux linkage calculation. In the simulation, 2 dimensional finite clement method is used considering the rotor movement. As an application of the proposed method, we calculated the harmonics of air gap flux and the output voltage in the 150KW class synchronous generator.

• Proceedings of the KIEE Conference
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• summer
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• pp.911-913
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• 2004

This paper presents characteristic analysis of claw-pole type generator. The analysis is performed using 2D equivalent model by 2D FEM. 3D FEM is used to check whether 2D equivalent model reflects the magnetic characteristics of the actual machine. Initially, 2D equivalent model of the claw-pole type generator is designed only by 3D geometry. Using 2D equivalent model, back emf characteristics are estimated and compared to measurements. The analysis results agree with measurements well and take less time comparing to 3D FEM.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.859-866
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• 2001

During the Pre-service Inspection for Wolsong Unit 3&4 in 1997/1998 respectively, 17 Distorted Roll Transition indications(over expanded beyond tubesheet secondary face) were identified at the Unit 4 (S/G B, D). Six(6) tubes out of these tubes were plugged in 1998. However the first Periodic Inspection identified additional 110 indications in 1999 and 2000. The additionally identified 110 indication call, not reported at the Pre-service Inspection, are; 2 Not-Finally-Expanded-Tubes and 108 Distorted Roll Transition tubes. Design limit of each Steam Generator tube Plugging is 6.4%. Plugging was performed by the Steam Generator manufacturer under the warranty. When Distorted Roll Transition indications were first identified on the Unit 4 in 1998 the degree of Over-expansion was measured using an inner dial-gage to make the disposition of Nonconformance report. 2 Not-Finally-Expanded-Tubes were plugged and 10 tubes out of 108 Distorted Roll Transition Tubes were also plugged as a preventive measure.

• Journal of Aerospace System Engineering
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• v.15 no.3
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• pp.79-86
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• 2021

For a preliminary study on a thrust-throttleable Variable Flow Ducted Rocket, a gas generator and flow control valve were developed, and ground combustion tests were performed. The gas generator and flow control valve operated at the required performance level for parameters, such as heat-resistance, combustion-time, pressure, and temperature. The combustion characteristics of a fuel-rich solid propellant mixed with Boron/MgAl/AP, etc., were also analyzed. A Plunger-type flow control valve was designed to control the discharge flow area, and it was confirmed that the flow control valve was able to control the combustion gas flow rate and pressure. However, due to the reduction of the discharge flow area caused by adhesion of combustion products, the combustion pressure continuously increased. The analysis of the pressure increase is covered in Part 2 of this paper.

• Journal of Advanced Information Technology and Convergence
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• v.10 no.2
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• pp.1-13
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• 2020

This paper presents an emergency brushless synchronous generator having rotating exciter status monitoring and protection functions. For monitoring the rotating exciter status, a wireless rotor status detector and a digital AVR(Automatic Voltage Regulator), which has a wireless communication capability, are proposed. The proposed rotor status detector detects temperatures of exciter armature and main field windings and input voltage and current of the main field. Therefore, it is possible to protect the generator from the over-temperature of windings and detect the exciter bridge diode fault. Furthermore, the proposed digital AVR has rotor status monitoring and protection function, and remote generator tuning, wireless group parallel operation function. So the operator can efficiently operate the generator using a smartphone from a remote area.