• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.200-205
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• 2004

The pantograph for Korean High Speed Train was developed and had been evaluating by through 'G7-R&D project for home grown high speed train technology' In this study, in mechanical aspect, the variation trend of contact force between pantograph and catenary according to the train running speed and driving pattern is conducted. A measuring system for current collecting performance and mechanical characteristics is used for this study, developed and installed on the prototype Korean High Speed Train, and physical characteristics were measured while the KHST runs on the test track. Through this study, remarkable trends of variation are found and analyzed from measured acceleration and vertical contact force between the pan head in pantograph and contact wire in catenary system according to the driving pattern and the train raised a running speed up to 300km/h.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.109-114
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• 2004

Measurement of noise is not only to know the information of acoustic pressure but to assess human response for noise. Provided that want to find human response for transportation noise, we will have to reproduce the measured noise. The method of reproduction is largely divided into monaural and binaural reproduction techniques. Human fundamentally hears sound through both ears, which is binaural hearing. And binaural technique includes the more information of physical phenomena like acoustical reflection and deflection. So, binaural reproduction is more suitable for assessment of the psychoacoustical and physiological response for transportation noise exposures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.730-735
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• 2004

Nowadays, most small form-factor drives adapt a load/unload mechanism and the flying height of the head becomes more and more low. So, the load/unload velocity also becomes one of the important factors to ensure the reliability of the load/unload operation. To control the load/unload velocity accurately, velocity sensing is most important because there is no special velocity sensor during the load/unload operation. In this paper, we proposed a very practical method that measures the velocity from the BEMF voltage of a VCM. Then, the proposed method is applied to the load/unload velocity control using 2.5' drives in order to verify its usefulness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.468-471
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• 2000

HDD가 비동작중 외부충격을 받았을 경우에 대해 수치해석을 이용하여 HSA(head stack ass'y)의 거동과 헤드가 디스크 면에서 멀어지는 Lift-off level을 고찰하고, actuator의 arm blade(primary system)의 끝단에 보조의 구조물(auxiliary system)을 붙여 반사인파의 가속도입력에 의해 발생되는 HSA의 진폭을 감소시키고 내충격성능을 향상시키고자 한다. 보조 구조물의 형태와 재료는 arm blade의 공진과 연계한 공진주파수의 최적화과정에 의해 결정된다. 실제 제품의 취급에서 가장 쉽게 발생할 수 있는 0.5ms의 duration time으로부터 제품의 성능평가 요건인 2ms의 duration time까지의 반사인파의 입력에 대한 응답을 고찰한 결과 보조의 구조물을 가졌을 경우 주 시스템보다 훨씬 높은 충격에서 헤드의 lift-off이 발생되어 전체 시스템의 내충격성능을 향상시킴을 알 수 있다.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.70-75
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• 2000

After the patterning and probe process of wafer have been achieved, the dicing process is necessary to separate chips from a wafer. The dicing process cuts a wafer to lengthwise and crosswise direction to make many chips by using narrow circular rotating diamond blade. But inferior goods are made under the influence of complex dicing environment such as blade, wafer, cutting water and cutting conditions. This paper describes a monitoring algorithm using feature extraction in order to find out an instant of vibration signal change when bad dicing appears. The algorithm is composed of two steps: feature extraction and decision. In the feature extraction, two features processed from vibration signal which is acquired by accelerometer attached on blade head are proposed. In the decision. a threshold method is adopted to classify the dicing process into normal and abnormal dicing. Experiment have been performed for GaAs semiconductor wafer. Based upon observation of the experimental results, the proposed scheme shown a good accuracy of classification performance by which the inferior goods decreased from 35.2% to 12.8%.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.79-87
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• 2002

An attempt to automate the surface finishing process of the die and mould has been carried out. An UMB(Ultrasonic Micro Burnishing) equipment which brought the micro plastic cold deformation to the 3D sculptured surface of mold and dies by ultrasonic vibration and static load, was developed and installed at the head stock of a vertical machining center. To be satisfied with the required surface roughness and hardness, the DB based program was also developed and applied. This equipment composes of UMB equipement, CNC vertical machining center, CAD/CAM system and the DB based program fer optimal condition. UMB processing effect was obtained from initial value Ral.25 and Hk337 to Ra0.085 and Hk521 and similar result was shown in industrial mould application.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.898-901
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• 2003

In order to get the drive reliability and low Power-consumption characteristics, most of small form factor HDD has und the load/unload mechanism instead of CSS type. Compared with CSS mechanism, the load/unload system has little opportunity of head/media contact during the disk spin-up and down. However, the load/unload mechanism needs the precise integration technology with slider, suspension, ramp and load/unload velocity, and all of these component s should be designed simultaneously, not an individually. In this paper, we focus the design of the suspension stiffness using the specified ABS design. We use the CML software to calculate the load/unload dynamic and use the RSM(Response surface method) to get the optimal condition of the suspension stiffness.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.9
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• pp.41-50
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• 2002

Optical disk system aiming at fast data transfer rate and high-density recording requires the improvement in performance of the pickup head. Especially, the pickup actuator needs better linearity and stability. So, a lever actuator for optical disk is proposed. In this paper, the role of lever and its structure are discussed and the flexure hinge is introduced to enhance the precise movement. Using the Newoton's method, the motion of equation for the lever actuator is obtained. The results are compared with the analysis results by the FEM (Finite Element Method) for the vibration and the magnetic field. Consequently, the lever actuator has the 2"d system characteristics in 3-axis moving directions and superior stability for the external vibration.tion.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.19 no.1
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• pp.16-20
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• 2008

Excising part or all part of a larynx as a cancer operation results in changes that transgress anatomic, physiologic, psychologic, and social priciples. The quality of life of a patient's life after any given cancer surgery usually is regarded as a second-priority consideration after oncologic safety. With laryngeal surgery, excision of malignant disease typically results in change that significantly influence an individual for the duration of his or her life. Nonetheless, with appropriate rehabilitation the surgical side effects can be minimized to allow for an excellent quality of life. Successful conservation surgery for laryngeal cancer requires careful interdependent selection for patients, lesions and procedure. The technical goal is to minimize trauma to uninvolved tissue and to wisely utilized local tissues or tree flap for reconstruction, while insuring for oncologically sound procedure. Rehabilitation should aim to produce a glottal sound source if possible, however voice therapy to promote false vocal fold vibration and arytenoid to epiglottis source of vibration can produce very satisfactory phonatory results.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.193-200
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• 2002

Simple spring-damper-mass models have been widely used to investigate whole-body vortical biodynamic response characteristics of the seated vehicle driver. Most previous models have not considered the effect of wobbling masses; i.e. heart, lungs, liver, intestine, etc. In this study, 4 -DOF seated driver model including one non-rigid mass representing wobbling visceral mass, 5-DOF model including intestine, and 10-DOF model including five lumbar vertebral masses were proposed. The model parameters were identified by a combinatorial optimization technique. simulated annealing method. The objective function was chosen as the sum of error between model response of seat-to-head transmissibility and driving point mechanical impedance and those of experimental data for subjects seated erect without backrest support. The model response showed a good agreement with the experimental response characteristics. Using a 10-DOF model, calculated resonance frequency of lumbar spine at 4Hz was matched well with experimental results of Panjabi et al.