• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.15-21
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• 2010

A differential case equipped with LSD(limited slip differential) has several advantages over a normal type for rear wheel drive vehicles. Specially, the torque distribution can be done between left and right drive wheel in the state of limited slip differential. Also although LSD types are very various according to operating type, medium and torque distribution, a multi-clutch type is generally applied to rear wheel drive vehicles. So, this study presents the analysis of design parameters for development of a friction plate for multi-clutch type LSD using vehicle road test, the simulation of analytical model and the development of vehicle dynamics model by a benchmark product. According to this investigation, the design parameters which are pre-load of coil spring, friction plate and contact area quantity, friction coefficient and TBR(torque bias ratio) for a friction plate are derived from experiment and simulation and consequently, vehicle dynamics model has been constructed for the development of friction plate for multi-clutch type LSD.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.806-813
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• 2016

To alleviate the vibration problem or to satisfy the required criteria for manifesting the guaranteed performance of precise equipment, various vibration isolation materials or apparatus, such as viscoelastic material, air and coil spring, have been developed and applied. Among them, a wire mesh material is regarded as one of the good candidate for reducing the vibration in terms of moderate material price, easy shape machining and long life cycle without the property deterioration induced by the aging or environmental effects. In this paper, prior to wire mesh isolator design, the static and dynamic elastic modulus of wire mesh materials are extracted from the experiment by the simple shaped cylindrical specimens and their characteristics for applying to vibration isolator design are examined. The simple shaped specimens were made as considering the design parameters of a wire mesh mount; i.e. the density, wire diameter and wire mesh slope, and the sensitivity analysis were also performed from a view point of the extracted elastic modulus.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.113-120
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• 2013

This paper proposes a design optimization approach for core of solenoid actuators by combining optimization techniques with the finite element method (FEM). A solenoid is an important element part which hydraulically controls a transmission system, etc. The demanded feature of the solenoid is that it performs an electromagnetic force output being constant regardless of the stroke and being proportional to coil current. The plunger compresses a spring with a minimum force of 12 N over an 1.7 mm travel. The orthogonal array, analysis of variance (ANOVA) techniques and response surface optimization, are employed to determine the main effects and their optimal design variables. The methodology is demonstrated as a optimization tool for the core design of a solenoid actuator.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1301-1307
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• 2011

Electrosurgical knee wand (EKW) is a high-frequency thermocautery instrument and is often used for coagulation, ablation, excision, and extirpation of knee ligaments and tissues. In order to maximize the success rate, ease, and safety of knee surgery using EKW and radiofrequency ablation, it is necessary to ensure that the EKW selectively approaches the lesion with utmost accuracy and safety. The key feature of this instrument is its excellent maneuverability. Hence, the authors constructed a tensile spring model based on a shape memory alloy (SMA), which exhibits the shape memory effect. This model can be used in knee surgery as it is considered the most biocompatible femorotibial surgical actuator. The changes in external temperature with current and the thermoelectric characteristics of the SMA were investigated. The relationship between the restoring force and the typical stroke (TS) in response to the conditions in the SMA tensile spring design were evaluated. In conclusion, as the diameter of the SMA tensile spring decreased, the maximum temperature increased. The strain in the actuator caused a stable and proportional increase in the force and induced current for up to 15s, but this increase became very unstable after 30s. Moreover, the relationship between the current and the TS was more stable than that between the current and the restoring force.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.174-181
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• 2001

Nowadays, the improvement and development of Multi-media and information & communication technology is rapidly processed. They need large data storage capacity. So that, many studies and researches in data storage have been carried out. According to them, the data storage capacity has been increased. But the limitation of storage capacity is happened for several problems. One of them is spot & pit size in optical and magnetic data storage and another is the resolution of actuators. The problems in spot & pit size are covered by new data storage methods-- for examples, AFM(Atomic Force Microscopy), MO(Magneto-optical) system, and NFR(Near-Field decoding) system etc. But the resolution limit of an actuator was not developed and doesn\`t follow up the development of spot & pit size. Because of them, we should improve a resolution of an actuator. Especially, in this paper an actuator if studied and designed for NFR (in using SIL(Solid Immersion Lens) system. It is a dual stage actuator, which consists of a Fine actuator and a Coarse actuator. and should desire 100nm accuracy. Its actuating force generation method is VCM(Voice Coil Motor). The Fine actuator is composed of 4-leaf springs and a bobbin wrapped by coil. The Coarse actuator has Coils and 3-Roller bearings. Also, The Characteristics of designed actuator for NFR system is estimated by Sine-Swept mode and LDV(Laser Doppler Vibro-meter).

• The korean journal of orthodontics
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• v.49 no.6
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• pp.372-380
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• 2019

Objective: To determine the effects of a local injection of leukocyte-platelet-rich plasma (L-PRP) on orthodontic tooth movement in rabbits. Methods: Twenty-three male New Zealand white rabbits were included in a split-mouth design. Tooth movement with a 100-g nickel-titanium closed-coil spring was performed on the maxillary first premolars. L-PRP was injected submucosally at the buccal and lingual areas of the first premolar in one random side of the maxilla and the other side served as the control and received normal saline. The amount of tooth movement was assessed on three-dimensional digital models on days 0, 3, 7, 14, 21, and 28. Histological findings and osteoclast numbers were examined on day 0 as the baseline and on days 7, 14, and 28. Results: The L-PRP group showed significantly greater cumulative tooth movement at all observed periods. However, a significantly higher rate of tooth movement was observed only on days 0-7 and 7-14. The osteoclast numbers were significantly increased in the L-PRP group on days 7 and 14. Conclusions: Local injection of L-PRP resulted in a transient increase in the rate of tooth movement and higher osteoclast numbers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.415-421
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• 2015

This paper describes the study of the design procedure for the step-by-step setup parameters and of the magnetizing method for performance and size reduction in the development of a haptic vibrator. The study of magnetization was accomplished by comparing the electromagnetic force in accordance with the horizontal and the vertical magnetization. The theoretical results indicated that the horizontal magnetization resulted in a better performance. The systematic design of a step-by-step procedure for establishing the design parameters was verified by testing the characteristics of the fabricated prototype product. The vibration response function analysis and electric field analysis were processed by decoupling of the analytical method, and these were determined to be in good agreement with the test results. The design parameters to contributing to the product reliability included the spring height, the welding position, and the coil position. The sensitivity of the electromagnetic field and the performance change were analyzed based on the design parameters. As a result, we proposed a design method to implement a reliability-based, high performance haptic vibrator.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.599-607
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• 2011

In this paper, a reaction-force compensation system for an XY linear motion stage, without an additional external isolation structure or extra motors, is developed. This system consists of a movable magnet track, a spring, a dummy weight, and a dedicated sensor module that measures the relative positions of the movable magnet track with respect to the motor coil. The reaction force compensation system is modeled, and simulations are carried out to optimize design parameters such as the moving distance of the magnet track, the transmission force, the dummy weight, and the allowed size of the mechanism. An XY linear motion stage is built, incorporating the reaction force compensation system, and the performance of the system is verified experimentally. For acceleration and deceleration values of 10 m/$s^2$, 85% of the reaction force is absorbed by the reaction force compensation system.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.197-203
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• 2014

The safety and arming device(SAD), one of the components of the fuzes, shall provide safety that is consistent with handling, storage, transportation, use, and disposal. In this paper, we describes the design of the SAD which includes the solenoid assembly and the solenoid driving circuit to improve the safety of the fuzes. The solenoid assembly consists of a coil assembly, a restoring spring, and a core. The solenoid assembly is added in the SAD as an additional safety device. In case of the normal circumstances, the core of the solenoid assembly restrains the $1^{st}$ and $2^{nd}$ safety devices of the SAD for those devices not to operate at all, so that the SAD can secure safety for storage, transportation, and use. In contrast, when the battery power is provided to the solenoid driving circuit just before the flight, the core confirms the power level and starts removing the restraint from the $1^{st}$ and $2^{nd}$ safety devices of the SAD, and then the SAD is able to change its mode from safety mode to armed mode. After firing, once the SAD's operations complete, the turned-on arming switch stops providing the power to the solenoid assembly automatically. It can reduce the power consumption at solenoid assembly. Therefore, the proposed solenoid driving circuit for the solenoid assembly not only unlocks the restrained solenoid assembly from the safety devices, but also saves the power consumption during the flight.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.6
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• pp.684-689
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• 2007

The aim of this study is to examine the change of the osteoclastic activity in the surrounding bone with or without tooth movement after corticotomy by histologic study. Eighteen male Sprague Dawley rats with an average body weight of 300 g(range 250-350 g) were used. The rats were divided into three groups of six animals. They were operated corticotomy-assisted tooth movement and killed after 1 week, 2 weeks, and 3 weeks after tooth movement. Corticotomy was done in the surrounding of the both upper first molar. A split mouth design was used by referring to the contralateral side as control. After flap suturing, the upper left first molar was moved anteriorly by closed coil spring. The force applied was 1 N. The average of tooth movement of the 1 week group was $0.24{\pm}0.09mm,\;0.20{\pm}0.26mm$ in 2 weeks group and $0.41{\pm}0.39mm$ in 3 weeks group, respectively. The difference between the 1 week and the 2 weeks groups was very small to compare with the 3 weeks group. In the treatment group, the average numbers of cells that positively reacted to TRAP were 14.5 in the 1 week group, 12.0 in the 2 weeks group, and 6.0 in the 3 weeks group. In the control group, the numbers were 8.3 in the 1 week group, 12.8 in the 2 week group, and 1.5 in the 3 week group, respectively. The amount of tooth movement of the 3 week group was about twice as large as those of the 1 week and 2 week groups. From the standpoint of histology, the average number of cells that positively reacted to TRAP was initially larger in the treatment group than in the control group, similar in both group in 2 weeks, and became less in the treatment group in 3 weeks. Additionally, in the control group, their activity of osteoclast was higher in 2 weeks than in 1 week, and decreased rapidly in 3 weeks.