• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.1-11
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• 2020

In this study, a hot-firing test of a lab-scale gel rocket motor using liquid kerosene and gelled kerosene as fuel was performed in order to analyze the discrepancy of the static and dynamic pressure between the two fuels. The static pressure, characteristic velocity, and characteristic velocity efficiency of the liquid kerosene and gelled kerosene did not show any significant difference. However, in the case of dynamic pressure characteristics, the pressure oscillation amplitude in a specific high frequency region of the gelled kerosene demonstrated a significantly higher amplitude than liquid kerosene case. This is considered to be the effect of an intrinsic combustion mechanism of the gel propellant, and it can be postulated that this may act as a dominant factor influencing the high frequency combustion instability of the gel rocket motor.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.257-265
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• 2000

Brushless DC(BLDC) motors are widely used as AC servo motors in factory automation fields because of their quick instantaneous mobility, good energy saving efficiency and easiness of design for control system comparing with induction motors. Recently, a Two-Degree-of-Freedom(2DOF) PI control law has been adopted to some application parts to accomplish an advanced speed control of BLDC motors. The method can treat the two conflicting performances, minimum tracking errors versus reference inputs without large overshoot and rejection of some disturbances including modeling errors, independently. However, the method can not design the optimal system which is able to minimize tracking errors and energy consumption simultaneously. In this paper, a 2DOF integral type optimal servo control method is investigated to promote the speed control performances of BLDC motors considering energy consumption. In order to applicate the method to the speed servo system of the BLDC motor, the motor is modeled in the state space using the vector control and decoupling technique. To verify the validity of the suggested method, some simulations and experiments are performed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1203-1211
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• 2017

This paper proposes a robust controller for flexible joint robots to achieve tracking performance and to improve robustness against both matched and mismatched disturbances. The proposed controller consists of a disturbance observer(DOB), passivity-based controller, and integral sliding mode controller(ISMC) in a backstepping manner. The DOB compensates the mismatched disturbance in the link-side and formulates the reference input for the motor-side controller. Interconnection and damping assignment passivity-based controller (IDA-PBC) performs tracking control of motor-side, and it is integrated to nominal control of ISMC to guarantee the over-all stability of the nominal system, while, matched disturbances are decoupled by the discontinuous control of ISMC. In the design of the link-side controller, PD type impedance controller is designed with DOB and this leads the continuous control input which is suitable to the reference input for the motor-side.

• Korean Journal of Microbiology
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• v.47 no.2
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• pp.158-162
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• 2011

Amino acid sequence alignment shows that $\underline{P}$roteus $\underline{m}$irabilis $\underline{t}$ranscription $\underline{r}$egulator (PMTR) has cystein sequence homology at metal binding domain to CueR (copper resistance) protein, which conserves two cysteins (Cys 112 and Cys 120 in PMTR). Gel shift assay revealed that PMTR protein bound to promoter region of Escherichia coli copA (copper-translocating P-type ATPase) and Proteus mirabilis atpase (putative copper-translocating P-type ATPase) genes except that of E. coli zntA (zinc-translocating P-type ATPase) gene. DNase I protection experiment indicated that PMTR protein protected the region over -35 box and close to -10 box. DNase I hypersensitive bases were shown at C and A bases of labeled template strand and at G and C bases of labeled non-template strand of DNA. These hypersensitive bases were appeared in other metalloregulatory proteins of MerR family, which suggests protein-induced DNA bending.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.369-374
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• 2010

Linear motors are easily affected by load disturbances, force ripples, friction, and parameter variations because there are no mechanical transmissions that can reduce the effects of model uncertainties and external disturbance. In this study, a nonlinear adaptive controller to achieve high-speed/high-accuracy position control of a two-axis linear motor is designed. The operation of this controller is based on a cross-coupling algorithm. Nonlinear effects such as friction and force ripples are estimated and compensated for. An enhanced cross-coupling algorithm is proposed for effectively improving the biaxial contour accuracy while achieving closed-loop stability. The proposed controller is evaluated by performing computer simulations.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.9-18
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• 2016

In this research, the modeling of erosive burning and analysis of effective parameters were carried out for the application of fluid-structure integration analysis. The manufacture, test, and analysis of erosive burning motors were carried out to estimate the erosive burning applying Lenoir & Robillard model considering effective parameters. The erosive burning phenomenon was detected from experimental results. Erosive burning model and its effective parameters were evaluated and analyzed considering existence of aluminum in propellant, relationship among erosive burning coefficients according to characteristic length, effect of grain initial temperature. The erosive burning model was applied to the fluid-structure integration analysis, and the estimated results were close to the experimental results.

• Journal of the Korea Convergence Society
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• v.10 no.5
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• pp.165-171
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• 2019

Engineering and Technology have been influencing a lot in the field of sports. Competitiveness, attributes of sports, have forced not only sports players but sports goods to enhance those performance. Particularly in the field of motorsports, the convergence of sports and technology has long been done to satisfy between performance and safety. In this study, strength analysis was carried with FEM to develop CFRP Laminate(Carbon Fiber Reinforced Plastic Laminate) bucket seat targeted to motorsports and car tuning industries and FIA($F\acute{e}d\acute{e}ration$ Internationale de l'Automobile) regulation was applied to design the racing seat and evaluate its strength. FEM modeling considered the attributes of composites was followed by strength evaluation based on Tsai-Wu failure index were done according to Lay-up sequence and layer numbers. The result showed that the lay-up sequence with stacking angle such as $[0^{\circ}/30^{\circ}/60^{\circ}/90^{\circ}/-30^{\circ}/-60^{\circ}]_4$ with 3mm form core was optimal selection in the field of weight and strength evaluation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.115-124
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• 2004

This paper suggested the vibration characteristic improvement by variation mode of ring type ultrasonic motor. Design for the piezoelectric ceramic and elastic body of stator were calculated by the finite element method(FEM) that consider the resonance frequency, vibration mode and coupling efficiency etc. Through the result of vibration analysis from 6 order mode to 8 mode, the 7 order mode was gained very an excellent results that it was the coupling efficient, minimum power loss and bending vibration value. Here over 7 order mode, was acquired that an output current for input voltage was very a large increased results. The result of vibration calculation, from thickness 0.5[mm] to 2[mm], know the fact that the vibration displacement at 0.5[mm] is an high value too. From such analysis result, this paper was manufactured the ultrasonic motor of outer diameter 50[mm], inter 22[mm] having the about 43.86[KHz] resonance frequency. We have gated that a simulation result is 42.2[KHz] and an experiment result is 43.86[KHz]. Then, a propriety of this paper was established the result almost similar to though comparison, investigation of simulation and experiment result.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.233-236
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• 2009

In this study, the characteristic of the hybrid rocket motor with $LN_2O$(Liquid Nitrous oxide) was investigated experimentally. HDPE(High Density PolyEthlene) was used as fuel with different sized single port. When used $LN_2O$, combustion efficiency is lower than using $GN_2O$(Gas Nitrous oxide), because of completeness of vaporization of droplet and mixing. And regression rate was changed by different oxidizer phase. This behavior was considered that flame temperature and combustion of solid fuel front/end surface.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.79-85
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• 2007

An internal ballistic model to predict the performance of a Polyethylene-GOX (PE-GOX) hybrid motor was proposed and evaluated. A theoretical treatment of the model was followed by detail discussion of each of the factors affecting the overall performance. The present model consists of the governing equations by considering the unsteady burn-back rate of the fuel grain and on-off response characteristics of a oxygen-supply valve. The numerical results using the 4th order Runge-Kutta scheme with temporal physicochemical properties showed good agreements with test results and the global effects of the performance parameters, such as the burning area of the fuel grain, O/F ratio, and etc., on the performance of the motor were analyzed.