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사륜 독립구동 차량시스템의 제어입력 조정을 통한 결함진단
박성호(Sungho Park),박영진(Youngjin Park),박윤식(Youn-sik Park) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
In this research, quantitative measurement of fault isolation is defined to evaluate fault isolate performance in parity equation. If it is hard or impossible to isolate fault components with parity equation, fault diagnosis method by adjustment of input distribution is applied to overcome the limitation of parity equation method. Noticeable characteristic in four wheels independently driven vehicle system is that there are lots of input distribution to achieve equivalent control performance. In normal case, controller makes optimal input distribution. But if there exist probability to have fault components, fault diagnosis system makes input perturbation and analyze system response to isolate fault components.
Park, Kwangwoo,Bak, Jino,Park, Sungho,Choi, Wonhoon,Park, Suk Won Institute of Physics in association with the Ameri 2016 Physics in medicine & biology Vol.61 No.3
<P>A semiempirical method based on the averaging effect of the sensitive volumes of different air-filled ionization chambers (ICs) was employed to approximate the correction factors for beam quality produced from the difference in the sizes of the reference field and small fields.</P> <P>We measured the output factors using several cylindrical ICs and calculated the correction factors using a mathematical method similar to deconvolution; in the method, we modeled the variable and inhomogeneous energy fluence function within the chamber cavity. The parameters of the modeled function and the correction factors were determined by solving a developed system of equations as well as on the basis of the measurement data and the geometry of the chambers. Further, Monte Carlo (MC) computations were performed using the Monaco<SUP>®</SUP> treatment planning system to validate the proposed method.</P> <P>The determined correction factors (<img ALIGN='MIDDLE' ALT='$k_{{{Q}_{\text{msr}}},Q}^{{{f}_{\text{smf}}},\,{{f}_{\text{ref}}}}$ ' SRC='http://ej.iop.org/images/0031-9155/61/3/1293/pmbaa0e14ieqn001.gif'/>) were comparable to the values derived from the MC computations performed using Monaco<SUP>®</SUP>. For example, for a 6 MV photon beam and a field size of 1 × 1 cm<SUP>2</SUP>, <img ALIGN='MIDDLE' ALT='$k_{{{Q}_{\text{msr}}},Q}^{{{f}_{\text{smf}}},\,{{f}_{\text{ref}}}}$ ' SRC='http://ej.iop.org/images/0031-9155/61/3/1293/pmbaa0e14ieqn002.gif'/> was calculated to be <img ALIGN='MIDDLE' ALT='$1.125$ ' SRC='http://ej.iop.org/images/0031-9155/61/3/1293/pmbaa0e14ieqn003.gif'/> for a PTW 31010 chamber and <img ALIGN='MIDDLE' ALT='$1.022$ ' SRC='http://ej.iop.org/images/0031-9155/61/3/1293/pmbaa0e14ieqn004.gif'/> for a PTW 31016 chamber. On the other hand, the <img ALIGN='MIDDLE' ALT='$k_{{{Q}_{\text{msr}}},Q}^{{{f}_{\text{smf}}},\,{{f}_{\text{ref}}}}$ ' SRC='http://ej.iop.org/images/0031-9155/61/3/1293/pmbaa0e14ieqn005.gif'/> values determined from the MC computations were 1.121 and 1.031, respectively; the difference between the proposed method and the MC computation is less than 2%. In addition, we determined the <img ALIGN='MIDDLE' ALT='$k_{{{Q}_{\text{msr}}},Q}^{{{f}_{\text{smf}}},\,{{f}_{\text{ref}}}}$ ' SRC='http://ej.iop.org/images/0031-9155/61/3/1293/pmbaa0e14ieqn006.gif'/> values for PTW 30013, PTW 31010, PTW 31016, IBA FC23-C, and IBA CC13 chambers as well.</P> <P>We devised a method for determining <img ALIGN='MIDDLE' ALT='$k_{{{Q}_{\text{msr}}},Q}^{{{f}_{\text{smf}}},\,{{f}_{\text{ref}}}}$ ' SRC='http://ej.iop.org/images/0031-9155/61/3/1293/pmbaa0e14ieqn007.gif'/> from both the measurement of the output factors and model-based mathematical computation. The proposed method can be useful in case the MC simulation would not be applicable for the clinical settings.</P>
Electrochemical Synthesis of Dumbbell-like Au-Ni-Au Nanorods and Their Surface Plasmon Resonance
Park, Yeon Ju,Liu, Lichun,Yoo, Sang-Hoon,Park, Sungho The Korean Electrochemical Society 2012 Journal of electrochemical science and technology Vol.3 No.2
In this report, we demonstrate that the longitudinal localized surface plasmon resonance mode can be suppressed when the nanorods were in dumbbell shape. The seed nanorods were synthesized by electrochemical deposition of metals into the pores of anodic aluminum oxide templates. The dumbbell-like nanorods were grown from seed Au-Ni-Au nanorods by a rate-controlled seed-mediated growth strategy. The selective deposition of Au atoms onto Au blocks of Au-Ni-Au nanorods produced larger diameter of Au nanorods with bumpy surface resulting in dumbbell-like nanorods. The morphology of nanorods depended on the reduction rate of $AuCl_4^-$, slow rate producing smooth surface of Au nanorods, but high reduction rate producing bumpy surface morphology. Through systematic investigation into the UV-Vis-NIR spectroscopy, we found that the multiple localized surface plasmon resonance (LSPR) modes were available from single-component Au nanorods. And, their LSPR modes of Au NRs with bumpy surface, compared to the smooth seed Au NRs, were red-shifted, which was obviously attributed to the increased electron oscillation pathways. While the longitudinal LSPR modes of smoothly grown Au NRs were blue-shifted except for a dipole transverse LSPR mode, which can be interpreted by decreased aspect ratio. In addition, dumbbell-like nanorods showed an almost disappeared longitudinal LSPR mode. It reflects that the plasmonic properties can be engineered using complex nanorods structure.
Study on Sliding Wear Characteristics and Processing of MoSi
Park, Sungho,Park, Wonjo,Huh, Sunchul Korean Society of Ocean Engineers 2012 International journal of ocean system engineering Vol.2 No.4
In this study, a monolithic MoSi2 matrix reinforced with 20 vol% SiC particles, a SiC/MoSi2 composite matrix reinforced with 20 vol% ZrO2 particles, and a ZrO2/MoSi2 composite were fabricated using hot press sintering at $1350^{\circ}C$ for 1 h under a pressure of 30 MPa. The Vickers hardness and sliding wear resistance of the monolithic MoSi2, ZrO2/MoSi2, and SiC/MoSi2 composite were investigated at room temperature. A wear behavior test was carried out using a disk-type wear tester with a silicon nitride ball. The ZrO2/MoSi2 composite showed an average Vickers hardness value and excellent wear resistance compared with the monolithic MoSi2 and SiC/MoSi2 composite at room temperature.
Park, Soohyeong,Nam, Sungho,Kim, Joonhyeon,Seo, Jooyeok,Jeong, Jaehoon,Woo, Sungho,Kim, Hwajeong,Kim, Youngkyoo American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.9
<P>Here, the improved performance of organic field effect transistors (OFET) by doping inorganic nanoparticles into a semiconducting polymer as a channel layer is briefly reported. Nickel(II) oxide nanoparticle (NiOnp) was used as an inorganic dopant while regioregular poly(3-hexylthiophene) (P3HT) was used as a matrix polymer for the channel layer in the OFETs. The doping ratio of NiOnp was made 1 wt.% so that it would minimally influence the nanostructure of the P3HT channel layer. The results showed that the optical absorption spectrum of the P3HT film was slightly red-shifted by the NiOnp doping, which reflects the improved crystallinity of the P3HT domains in the P3HT:NiOnp films. The drain current of the OFETs with the P3HT:NiOnp films was significantly enhanced ca. three-to-seven fold by the NiOnp doping under appying gate voltages while the hole mobility of the OFETs P3HT:NiOnp films was improved as much as three fold by the NiOnp doping. The enhanced performance has been assigned to the role of NiOnp that has relatively higher hole mobility than the P3HT polymer.</P>
THE SENSITIVITY OF STRUCTURAL RESPONSE USING FINITE ELEMENTS IN TIME
Park, Sungho,Kim, Seung-Jo The Korean Society for Energy 2002 Journal of Theoretical and Applied Mechanics Vol.3 No.1
The bilinear formulation proposed earlier by Peters and Izadpanah to develop finite elements in time to solve undamped linear systems, Is extended (and found to be readily amenable) to develop time finite elements to obtain transient responses of both linear and nonlinear, and damped and undamped systems. The formulation Is used in the h-, p- and hp-versions. The resulting linear and nonlinear algebraic equations are differentiated to obtain the first- and second-order sensitivities of the transient response with respect to various system parameters. The present developments were tested on a series of linear and nonlinear examples and were found to yield, when compared with results obtained using other methods, excellent results for both the transient response and Its sensitivity to system parameters. Mostly. the results were obtained using the Legendre polynomials as basis functions, though. in some cases other orthogonal polynomials namely. the Hermite. the Chebyshev, and integrated Legendre polynomials were also employed (but to no great advantage). A key advantage of the time finite element method, and the one often overlooked in its past applications, is the ease In which the sensitivity of the transient response with respect to various system parameters can be obtained. The results of sensitivity analysis can be used for approximate schemes for efficient solution of design optimization problems. Also. the results can be applied to gradient-based parameter identification schemes.