• Title/Summary/Keyword: Force Density Method

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MANDIBULAR DISTRACTION OSTEOGENESIS WITH COMPRESSION FORCE - BONE DENSITY, HISTOLOGICAL FINDINGS AND TMJ RESPONSE (압축력을 병용한 하악골 신장술)

  • Hwang, Young-Seob;Heo, June;Kim, Uk-Kyu;Park, Seong-Jin;Hwang, Dae-Seok;Kim, Yong-Deok;Chung, In-Kyo;Kim, Kyu-Cheon
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.28 no.6
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    • pp.531-548
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    • 2006
  • The purpose of this study was to investigate the biomechanical, histologic findings of distracted regenerate and TMJ response in modified distraction osteogenesis (DO) technique combined with compression force as biomechanical stimulation method which has been suggested in 2002, and developed thereafter by authors. This study was performed with two experiments. First experiment was designed to explore the optimal ratio of compression force versus distraction force for the new DO technique. Second experiment was planned to evaluate the reaction of TMJ tissue, especially condyle, disc after application of the DO technique with compression force. Total 52 New Zealand adult male-rabbits with 3.0kg body weight were used for the study. For the first study, 30 adult male-rabbits underwent osteotomy at one side of mandibular body and a external distraction device was applied on each rabbit with same manner. In the control group of 10 rabbits, final 8 mm of distraction with 1 mm rate per day was done with conventional DO technique after 5 latency days. For the experimental group of 20 rabbits, a compression force with 1 mm rate per day was added to the distracted mandible on 3-latency day after over-distraction (over-lengthening). As the amount of the rate of compression versus distraction, experimental subgroup I (10 rabbits) was set up as 2 mm compression versus 10 mm distraction (1/5) and experimental subgroup II (10 rabbits) was set up as 3 mm compression versus 11 mm distraction (about 1/3). All 30 rabbits were set up to obtain final 8 mm distraction and sacrificed on postoperative 55 day to analysis on biomechanical, and histologic findings of the bone regenerates. For second study, 22 adult male-rabbits were used to evaluate TMJ response after the DO method application with compression force. In the control group, 10 rabbits was used to be performed with conventional DO method, on the other hand, in a experimental group of 10 rabbits, 10 mm distraction with 2 mm compression (1/5 ratio) was done. The remaining 2 rabbits served as the normal control group. Histomorphologic examinations on both condyle, histological studies on condyle, disc were done at 1, 2, 3, 4, 7 weeks after distraction force application. The results were as follows: 1. On the bone density findings, the experimental group II (force ratio - 1/3) showed higher bone density than the other experimental group (force ratio - 1/5) and control group (control group - $0,2906\;g/cm^2$, experimental group I - $0.2961\;g/cm^2$, experimental group II - $0.3328\;g/cm^2$). 2. In the histologic findings, more rapid bone maturation like as wide lamellar bone site, more trabeculae formation was observed in two experimental groups compared to the conventional DO control group. 3. In morphologic findings of condyle, there were no differences of size and architecture in the condyle in the control and experimental groups. 4. In histologic findings of condyles, there were thicker fiberous and proliferative layers in experimental group than those of control group until 2 weeks after distraction with compression force. But, no differences were seen between two groups on 3, 4, 7 weeks after compression. 5. In histologic findings of disc, more collagen contents in extracellular matrix, more regular fiber bundles, and less elastin fibers were seen in experimental group than control group until 2 weeks after distraction with compression. But, no differences were seen between two groups on 3, 4, 7 weeks after distraction with compression. From this study, we could identify that the new distraction osteogenesis technique with compression stimulation might improve the quality of bone regeneration. The no remarkable differences on TMJ response between control and experimental groups were seen and TMJ tissues were recovered similarly to normal TMJ condition after 3 weeks.

Monitoring of Chatter Vibration by Frequency Analysis of AE Signals (AE 신호의 주파수분석에 의한 Chatter 진동의 감시)

  • 조대현
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.5
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    • pp.157-164
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    • 2000
  • A machine tool generally has some serious stability problems in the form of tool chatter during the cutting process. Chatter vibration deteriorates the surface finish, reduce tool and machine life, accelerates machine tool system component wear, and may lead to an unacceptable noise sound in the working environment. In this study, the behavior of spectral density of AE signal and principal cutting force signal in order to monitor the chatter vibration in the cutting process has been investigated. From the results, the reliability of proposed monitoring method has been confirmed.

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An Analysis of Heat and Fluid Flow in the Laser Surface Melting with a Deformed Surface. (굴곡의 표면을 가진 금속의 레이저 용융에 대한 열 및 유체유동 해석)

  • Kim, Young-Deuk;Sim, Bok-Cheol;Kim, Woo-Seung
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.139-144
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    • 2003
  • Laser melting problems with deformed substrates are investigated by axisymmetric numerical simulations. Source-based method is used to solve the energy equation, and the momentum equations are solved in the liquid domain with SIMPLER algorithm. Using a laser beam with a top-hat heat flux distribution, this study is performed to examine the effect of surface deformation, beam power density and surface tension force on the melt pool during laser melting. Surface temperature decreases with increasing surface deformation, while surface velocity increases. It is found that surface deformation, beam power density and surface tension force have a very significant effect on heat transfer and fluid flow during laser melting.

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An Analysis of Heat and Fluid Flow in the Laser Surface Melting with a Deformed Surface (굴곡의 표면을 가진 금속의 레이저 용융에 대한 열 및 유체유동 해석)

  • Kim, Young-Deuk;Sim, Bok-Cheol;Kim, Woo-Seung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.1 s.232
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    • pp.1-8
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    • 2005
  • Laser melting problems with deformed substrates are investigated by axisymmetric numerical simulations. Source-based method is used to solve the energy equation, and the momentum equations are solved in the liquid domain with SIMPLER algorithm. Using a laser beam with a top-hat heat flux distribution, this study is performed to examine the effect of surface deformation, beam power density and surface tension force on the molten pool during laser melting. Surface temperature decreases with increasing surface deformation, while surface velocity increases. It is found that surface deformation, beam power density and surface tension force have a very significant effect on heat transfer and fluid flow during laser melting.

Back EMF Design of an AFPM Motor using PCB Winding by Quasi 3D Space Harmonic Analysis Method

  • Jang, Dae-Kyu;Chang, Jung-Hwan;Jang, Gun-Hee
    • Journal of Electrical Engineering and Technology
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    • v.7 no.5
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    • pp.730-735
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    • 2012
  • This paper presents a method to design the waveform of a back electromotive force (back EMF) of an axial flux permanent magnet (AFPM) motor using printed circuit board (PCB) windings. When the magnetization distribution of permanent magnet (PM) is given, the magnetic field in the air gap region is calculated by the quasi three dimensional (3D) space harmonic analysis (SHA) method. Once the flux density distribution in the winding region is determined, the required shape of the back EMF can be obtained by adjusting the winding distribution. This can be done by modifying the distance between patterns of PCB to control the harmonics in the winding distribution. The proposed method is verified by finite element analysis (FEA) results and it shows the usefulness of the method in eliminating a specific harmonic component in the back EMF waveform of a motor.

Analysis on electromagnetic characteristics of linear induction motor using the analytical method (해석적인 방법에 의한 직선형 유도 전동기의 전자기적 특성해석)

  • Jang, Seok-Myeong;Choi, Ji-Hwan;Ko, Kyoung-Jin;Kim, Hyun-Kyu;Kim, Il-Jung
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.804_805
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    • 2009
  • This paper deals with analysis on electromagnetic characteristics of linear induction motor(LIM) using the analytical method. As a analytical method, space harmonics method which is applied to multilayer region is used in this paper. Using the flux density obtained by analytical method, thrust and normal force are calculated through Maxell stress tensor. The results such as flux densitty, eddy current and force are verified by comparison between analytical results and FEM.

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Design and Characteristic Analysis of Linear Oscillating Actuator with Structure (직선 왕복 액추에이터의 구조에 따른 설계 및 특성 검토)

  • Kim, Hae-Joong;Lee, Choong-Sung;Hong, Jung-Pyo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.4
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    • pp.537-544
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    • 2015
  • This paper provided two types of design method on moving core type LOA and one type of design method on moving coil type LOA, and compared and examined each of its characteristics. In order to conduct parametric design process, voltage equation was used to schematize Lmin/K and L/M map, and the schematized map was used to determine Lmin, K or L, M. In order to meet requirements such as thrust force and input voltage and to satisfy the target values of Lmin, K or L, M, the types and sizes of each type were designed using geometry design process. 2-FEA was conducted for each of the designed model. After examining thrust force based on the location of the mover, Type-1 showed radical change in thrust force as movers moved, and Type-2 and Type-3 showed constant appearance of thrust force. The total volume of the designed LOA model was compared to select the model with highest thrust force density. Also, the weight of the mover for each model was compared in order to select the model that was predicted to have highest mechanical responsiveness and stroke characteristics.

Simulation analysis on the separation characteristics and motion behavior of particles in a hydrocyclone

  • Xu, Yanxia;Tang, Bo;Song, Xingfu;Sun, Ze;Yu, Jianguo
    • Korean Journal of Chemical Engineering
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    • v.35 no.12
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    • pp.2355-2364
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    • 2018
  • We evaluated the effect of particle size and associated dynamics on a hydrocyclone separation process in order to understand the movement of the particle trajectories inside the hydrocyclone via numerical analysis, with particles of acid hydrolysis residues discharged in $TiO_2$ production via the sulfate method as a case study. The values obtained from the numerical simulation were successfully compared with those from experimental tests in the literature, allowing a description of the dynamics of the particles, their acting forces, and their relevant properties together with separation efficiency. The results showed that particle motion is jointly controlled by the drag force, the pressure gradient force and the centrifugal force. With increasing particle size, the influence of the drag force is weakened, whereas that of the centrifugal force and pressure gradient is strengthened. Factors including particle density, slurry viscosity, and inlet slurry flow rate also contribute to a clear and useful understanding of particle motion behavior in the hydrocyclone as a method for improving the separation efficiency.

Simple Analysis Method for the Interrupting Capability of a Contact System in a Molded Case Circuit Breaker

  • Choi, Young-Kil;Jee, Seung-Wook
    • Journal of Electrical Engineering and Technology
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    • v.12 no.3
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    • pp.1257-1261
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    • 2017
  • This paper focuses on understanding the interrupting capability of an arc contact system in a molded case circuit breaker (hereafter MCCB). We selected four types of MCCBs and analyzed the magnetic flux density distributions in the contact systems caused by the fault currents. We ascertained that the magnetic flux density profile varies according to the shape of the contact system and was asymmetric at both the ends of an arc, perpendicular to the arc column because of the magnetic grid installed in the contact system. The asymmetric difference creates a magnetic force that pushes the arc current outwards and provides an interrupting capability. We have introduced a simple analysis method for determining the interrupting capability of the contact system for an MCCB by the arc-driving magnetic flux density.

Application of probabilistic method to determination of aerodynamic force coefficients on tall buildings

  • Yong Chul Kim;Shuyang Cao
    • Wind and Structures
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    • v.36 no.4
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    • pp.249-261
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    • 2023
  • Aerodynamic force coefficients are generally prescribed by an ensemble average of ten and/or twenty 10-minute samples. However, this makes it difficult to identify the exact probability distribution and exceedance probability of the prescribed values. In this study, 12,600 10-minute samples on three tall buildings were measured, and the probability distributions were first identified and the aerodynamic force coefficients corresponding to the specific non-exceedance probabilities (cumulative probabilities) of wind load were then evaluated. It was found that the probability distributions of the mean and fluctuating aerodynamic force coefficients followed a normal distribution. The ratios of aerodynamic force coefficients corresponding to the specific non-exceedance probabilities (Cf,Non) to the ensemble average of 12,600 samples (Cf,Ens), which was defined as an adjusting factor (Cf,Non/Cf,Ens), were less than 2%. The effect of coefficient of variation of wind speed on the adjusting factor is larger than that of the annual non-exceedance probability of wind load. The non-exceedance probabilities of the aerodynamic force coefficient is between PC,nonex = 50% and 60% regardless of force components and aspect ratios. The adjusting factors from the Gumbel distribution were larger than those from the normal distribution.