• Title/Summary/Keyword: zero pattern

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A Study on the method for the measurement of vibrating amplitude and frequency with Laser Doppler Vibrometer (레이저 도플러 진동계를 이용한 진동변위와 주파수 측정방법 연구)

  • Kim, Seong-Hoon;Kim, Ho-Seong
    • Proceedings of the KIEE Conference
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    • 1998.07e
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    • pp.1824-1827
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    • 1998
  • A Laser Doppler Vibrometer(LDV) was developed using He-Ne laser as a light source. The heterodyne method was employed and its output signal was digitally processed with a $\mu$-processor and the result was displayed with LCD. The frequency shifted object beam(40 MHz) by a Bragg cell was focused on the surface of the moving target and the Doppler shifted reflected beam was recombined with reference beam at the fast photodetector to produce frequency modulated signal centered at 40 MHz. The signal from the detector was amplified and downconverted to intermediate frequency centered at 1 MHz after mixing process. The voltage output that was proportional to the velocity of the moving surface was obtained using PLL. With the same method, the fringe pattern signal of the moving surface is obtained. This fringe pattern signal is converted to TTL signal with ZCD(zero-crossing detector) and then counted to calculate the displacement due to the vibration, which is displayed with LCD. This LDV can be used to measure the resonant frequency of the electric equipments such as circuit breakers and transformers, of which resonant frequencies are changed when they are damaged.

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Fashion Design Study by Whole Cut Way (Whole cut에 의한 패션디자인 연구)

  • Park, You Shin
    • Journal of Fashion Business
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    • v.19 no.5
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    • pp.199-212
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    • 2015
  • Environmentally-friendly whole-cut designs can minimize carbon dioxide emissions which are harmful to the earth, and reduce energy, labor force and time in cutting or sewing clothes. The design and way of wearing clothing will be investigated by classifying whole-cut clothing appearing in the history of costume and past traditional outfits such as Drapery, a Pancho, Tunic, or Loincloth. According to the results from the analysis of whole-cut methods applied in design, they were classified as follows: whole-cut, utilizing square-panels as is, pleats, smoking, lip band, origami, cutting way, and subtraction-cutting whole-cut design. The whole-cut design utilizing square panel as it is can minimize the waste of energy and material but can also maximize the possibility of circulation by recycling. In utilizing an all square panel, it broke away from the existing whole-cut in the western pattern, namely, the pattern of clothes clinging to the body, and was found to have new aesthetic value with a new approach. Due to the whole-cut method having a restriction in the use of dart and line cutting in its designing process, there were only designs that did not show the body line, such as designs clinging to the body. Therefore we developed a design similar to those that cling to the body by whole-cut, In addition, the work produced was with high efficiency and variability, which produces simple designs but can be worn in a variety of ways.

3D finite element simulation of human proximal femoral fracture under quasi-static load

  • Hambli, Ridha
    • Advances in biomechanics and applications
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    • v.1 no.1
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    • pp.1-14
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    • 2014
  • In this paper, a simple and accurate finite element model coupled to quasi-brittle damage law able to describe the multiple cracks initiation and their progressive propagation is developed in order to predict the complete force-displacement curve and the fracture pattern of human proximal femur under quasi-static load. The motivation of this work was to propose a simple and practical FE model with a good compromise between complexity and accuracy of the simulation considering a limited number of model parameters that can predict proximal femur fracture more accurately and physically than the fracture criteria based models. Different damage laws for cortical and trabecular bone are proposed based on experimental results to describe the inelastic damage accumulation under the excessive load. When the damage parameter reaches its critical value inside an element of the mesh, its stiffness matrix is set to zero leading to the redistribution of the stress state in the vicinity of the fractured zone (crack initiation). Once a crack is initiated, the propagation direction is simulated by the propagation of the broken elements of the mesh. To illustrate the potential of the proposed approach, the left femur of a male (age 61) previously investigated by Keyak and Falkinstein, 2003 (Model B: male, age 61) was simulated till complete fracture under one-legged stance quasi-static load. The proposed finite element model leads to more realistic and precise results concerning the shape of the force-displacement curve (yielding and fracturing) and the profile of the fractured edge.

A Study on the Vibration Characteristics of Thin Plate with Crack under Tension using ESPI (ESPI기법에 의한 하중을 받는 균열 박판의 진동 특성에 관한 연구)

  • Kim, Koung-Suk;Kang, Ki-Soo;Choi, Ji-Eun;Park, Chan-Ju;Hong, Jin-Who
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.2
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    • pp.182-188
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    • 2001
  • This paper presents the vibration characteristics of a rectangular plate with $45^{\circ}$ oblique crack subjected to a uniaxial tension. The experiment is adopted by the time-average Electronic Speckle Pattern Interferometry(ESPI) method. The natural frequency and mode shape are considered accurately according to the increase of tensile load. When tensile load is zero, the vibration modes we agreed with the smooth and the $45^{\circ}$ obliquely cracked plate. But according to the increasement of load it is shown that vibration modes are extremely varied. The effects of the crack under the vibration are discussed in detail. It is indicated that the increase of load makes the variation of the frequencies and modes complicate in the range of even a small load. The results are agreed with the FEM analysis within 5%.

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Seasonal Occurrence Pattern of Peach Pyralid Moth, Oichocrosis punctiferalis, in Fuyu Persimmon Orchards and Fruit Damage at Harvesting Time (단감원에서 복숭아명나방의 발생양상과 수확기 단감의 피해과율)

  • 박정규;강창헌;이규철;이동문
    • Korean journal of applied entomology
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    • v.41 no.2
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    • pp.107-112
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    • 2002
  • Seasonal occurrence pattern of the peach pyramid moth (PPM), Dichocrosis punctfferahs, was studied by sex pheromone traps and mercury light traps in several Fuyu persimmon orchards under different control pressures in southern region of Korea in 2000 and 2001. Fruit damage by the larvae was also checked at harvesting time from 1999 to 2001. The pattern showed 3 distinct peaks; the 1st one in mid to late June, the 2nd one in mid to late August, and the 3rd one in late September. Number of PPM catches was higher in less controlled than in intensively controlled orchards. There were no persimmon fruits damaged by the larvae of PPM and persimmon fruit moth, Stathmopoda masinissa, in our samples from the testing orchards at harvesting time. Therefore, it is unlikely that these two quarantine pests are included in the exporting fruits. Considering flora adjacent to the tested orchards and zero levels of fruit damage by the larvae, there is a strong possibility that the moths flew from neighbouring chestnut trees or other host plants to be attracted to the traps in the persimmon orchards.

A Study on the Wet Clutch Pattern Design for the Drag Torque Reduction in Wet DCT System (습식 DCT의 드래그 토크 저감을 위한 클러치 패드 유로 설계)

  • Cho, Junghee;Han, Juneyeol;Kim, Woo-Jung;Jang, Siyoul
    • Tribology and Lubricants
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    • v.33 no.2
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    • pp.71-78
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    • 2017
  • The drag torque in the wet clutch system of a dual clutch transmission system is investigated because it is relatively high, up to 10 of the total output torque of the engine, even when the clutch is in the disengagement state with zero torque transfer. Drag torque results from the shear resistance of the DCTF between the friction pad and separator plate. To reduce the drag torque for ensuring fuel economy, the groove pattern of the wet clutch friction pad is designed to have a high flow rate through the pattern groove. In this study, four types of groove patterns on the friction pad are designed. The volume fraction of the DCTF (VOF) and hydrodynamic pressure developments in the gap between the friction pad and separator plate are computed to correlate with the computation of the drag torque. From the computational results, it is found that a high VOF and hydrodynamics increase the drag torque resulting from the shear resistance of the DCTF. Therefore, a patterned groove design should be used for increasing the flow rate to have more air parts in the gap to reduce the drag torque. In this study, ANSYS FLUENT is used to solve the flow analysis.

Crystalline Qualities and Surface Morphologies of As-Grown $YBa_2Cu_3O_{7-x}$ Thin Films on MgO(100) Substrate by Reactive Coevaporation Method (반응성 동시 증착법에 의한 As-grown $YBa_2Cu_3O_{7-x}$ 박막의 결정 특성 및 표면형상에 관한 연구)

  • Jang, Ho-Yeon;Watanabe, Yasuhiro;Doshida, Yutaka;Shimizu, Kenji;Okamoto, Yoichi;Akibama, Ryozo;Song, Jin-Tae
    • Korean Journal of Materials Research
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    • v.1 no.2
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    • pp.93-98
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    • 1991
  • The as-grown $YBa_2Cu_3O_{7-x}$ superconducting thin films on MgO(100) substrate have been prepared by a reactive coevaporation method. The superconducting transition temperature, surface morphology and crystalline quality were examined as a function of the substrate temperature ranging from $450^{\circ}C$ to $590^{\circ}C$. From the reflection high energy electron diffraction (RHEED) analysis, it was found the film consisted of almost amorphous phase with a halo pattern deposited at the substrate temperature of $450^{\circ}C$. The film deposited at the substrate temperature of $510^{\circ}C$ consisted of polycrystalline phase, showing a broad ring pattern. On the other hand, for the film deposited at $590^{\circ}C$, RHEED showed spotty pattern indicating that this film consisted of single crystal phase. It has rough film surface due to the surface outgrowth. The surface outgrowth increased as the substrate temperature increased from $510^{\circ}C$ to $590^{\circ}C$. the surface outgrowth may be due to the anisotropic growth rate. The highest transition temperature obtained in this study was $Tc_{zero}$ of 83K with $Tc_{onset}$ of 88K for the film deposited at $590^{\circ}C$ using activated RF oxygen plasma.

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Study on the Application of Oriental Medical Evaluation to Dementia (치매 한의진단 평가도구 적용 연구)

  • Kim, Ka-Na;Bae, Hyunsu;Hwang, Wei-Wan;Cho, Seung-Hun
    • Journal of Oriental Neuropsychiatry
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    • v.25 no.4
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    • pp.383-388
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    • 2014
  • Objectives: Patients with dementia are increasing in Korea. So the importance of accurate diagnosis and treatment of dementia is growing. In this paper, we evaluated the result of employing the Korean medical diagnostic pattern as a tool in clinics. Methods: Patients diagnosed with Alzheimer's disease were evaluated using the Korean medical diagnostic pattern tool. Results: The number of patients with liver-kidney yin deficiency pattern/syndrome was 35. Analyzing the ratio difference between the 'liver-kidney yin deficiency' group and the 'not liver-kidney yin deficiency' group revealed that the ratio of the responses to the fourth question was less than zero. The ratio of the responses to the fifth, seventh, and eight questions were all less than 10%. The ratio of the responses to the first and second questions were greater than 30%. Conclusions: Of the six diagnostic patterns, liver-kidney yin deficiency was the greatest in the study subjects. The fourth question in the liver-kidney yin deficiency tool tests for the lack of appropriateness whereas the fifth, seventh, and eight questions test for lack of discrimination. Applying more weight to the first and second questions was an excellent choice to increase the discrimination.

Gait Pattern Generation of S-link Biped Robot Based on Trajectory Images of Human's Center of Gravity (인간의 COG 궤적의 분석을 통한 5-link 이족 로봇의 보행 패턴 생성)

  • Kim, Byoung-Hyun;Han, Young-Joon;Hahn, Hern-Soo
    • Journal of KIISE:Software and Applications
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    • v.36 no.2
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    • pp.131-143
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    • 2009
  • Based on the fact that a human being walks naturally and stably with consuming a minimum energy, this paper proposes a new method of generating a natural gait of 5-link biped robot like human by analyzing a COG (Center Of Gravity) trajectory of human's gait. In order to generate a natural gait pattern for 5-link biped robot, it considers the COG trajectory measured from human's gait images on the sagittal and frontal plane. Although the human and 5-link biped robot are similar in the side of the kinematical structure, numbers of their DOFs(Degree Of Freedom) are different. Therefore, torques of the human's joints cannot are applied to robot's ones directly. In this paper, the proposed method generates the gait pattern of the 5-link biped robot from the GA algorithm which utilize human's ZMP trajectory and torques of all joints. Since the gait pattern of the 5-link biped robot model is generated from human's ones, the proposed method creates the natural gait pattern of the biped robot that minimizes an energy consumption like human. In the side of visuality and energy efficiency, the superiority of the proposed method have been improved by comparative experiments with a general method that uses a inverse kinematics.

Trajectory Parameter Optimization using Genetic Algorism (유전알고리즘을 이용한 워킹 궤적 파라미터의 최적화)

  • Son, In-Hye;Kim, Dong-Han;Park, Chong-Kug
    • Proceedings of the KIEE Conference
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    • 2008.04a
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    • pp.75-76
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    • 2008
  • In oder for the robot to walk with stability, trajectory generation method for the biped robot is important. In this paper proposed the genetic algorithm to optimize biped robot motion parameters. Because most of trajectory generation, the walking parameters determined arbitrarily. Formulating the constraints of the motion parameters, and the trajectory is derived by cubic spline function. Finally walking patterns are described through simulation studies. When the ZMP(zero moment point) and DSM(dynamic stability margin) are satisfied, the walking pattern is chosen.

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