• 한국가스학회지
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• 제13권6호
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• pp.1-8
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• 2009

본 연구는 웻지 시스템을 이용하여 3축 방향의 진동 및 충격을 완화시킬 수 있는 감쇠기에 관한 것이다. 기존의 수직방향 진동/충격에 대해서만 흡진하는 디스크 스프링 완충기를 개선하여 웻지를 추가함으로써 종 방향은 물론 횡 방향을 모두 포함한 3축에 대해 흡진이 가능한 댐퍼를 제안하였다. 수학적 모델을 수립하여, 댐퍼내의 중요한 요소로 작동하는 디스크 스프링과 웻지의 특성을 고찰하였으며, 실험을 통해 댐퍼의 거동을 고찰하였다. 수치 해석 결과와 실험 결과가 잘 일치함을 알 수 있었고, 소산된 에너지양을 구한 후, 수직 수평방향에 대한 등가 점성 감쇠를 구하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.539-541
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• 2016

본 논문에서는 스프링 생산기기에 연결되어 생산현황을 표시해 주는 자유장 선별기와 연동하여 동작하는 PLC 연동형 실시간 자유장 모니터링 시스템을 제안하였다. 제안된 시스템은 원격지에서 생산품의 품질과 생산량, 불량률 등을 실시간으로 확인할 수 있게 해 준다. 시스템은 크게 세 부분으로 구성된다. 자유장 선별기로부터 데이터를 수신하여 Wi-Fi 통신을 이용해 서버 프로그램으로 전송하는 PLC 무선연동장치와 PLC 무선연동장치로부터 수신한 데이터를 화면에 표시하고 데이터베이스에 저장하는 서버 프로그램, 그리고 데이터베이스에 저장되어 있는 지난 데이터를 확인 및 엑셀 파일로 추출하는 기능을 제공하는 사용자 GUI 프로그램으로 구성된다.

• 한국정밀공학회지
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• 제22권11호
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• pp.165-172
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• 2005

In MEMS (Micro-Electro-Mechanical System), packaging induced stress or stress induced structure deformation becomes increasing concerns since it directly affects the performance of the device. In the decoupled vibratory MEMS gyroscope, the main factor that determines the yield rate is the frequency difference between the sensing and driving modes. The gyroscope, packaged using the anodic bonding at the wafer level and EMC (epoxy molding compound) molding, has a deformation of MEMS structure caused by thermal expansion mismatch. This effect results in large distribution in the frequency difference, and thereby a lower yield rate. To improve the yield rate we propose a packaged SiOG (Silicon On Glass) process technology. It uses a silicon wafer and two glass wafers to minimize the wafer warpage. Thus the warpage of the wafer is greatly reduced and the frequency difference is more uniformly distributed. In addition. in order to increase robustness of the structure against deformation caused by EMC molding, a 'crab-leg' type spring is replaced with a semi-folded spring. The results show that the frequency shift is greatly reduced after applying the semi-folded spring. Therefore we can achieve a more robust vibratory MEMS gyroscope with a higher yield rate.

• 한국정밀공학회지
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• 제17권10호
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• pp.95-101
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• 2000

The purpose of this study is to develop an improved measuring system, which allows for effectively measure spring clamping forces. This system consists of eight or twelve measuring points in order to acquire the clamping force distribution of the whole range of spring clamp. Each measuring point consists of load cells equipped with 4 strain gauges. Using different bearings, we calibrate the roundness of the measuring points. For quality control and database construction, a software system is established. furthermore, uncertainty is calculated to validate the confidence of this system. Various experiments confirm the effectiveness of this measuring system.

• 열처리공학회지
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• 제9권3호
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• pp.187-197
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• 1996

In this study, the properties of coil spring made by Cu-Zn-Al and B added shape memory alloys are investigated. The measurement of recovery displacement and energy with increasing weight, and thermocycling properties have been studied using displacement measuring device. Transformation temperature and phase change by thermocycling have been also investigated by DSC and X-ray diffractometer. Grain size of the alloy is refined from 1.2mm to $400{\mu}m$ by 0.06wt% of B addition. The maximum recovery energy of the coil spring for B added alloy is larger than that of no B added alloy, it is because of grain refinement. And shape memory ability of the coil spring by thermocycling decrease with increasing thermocycling after thermocycle under load. The degradation of shape memory properties of coil spring by thermocycling is improved by B addition.

• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.85-89
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• 2007

Linear ball guideways have been used recently in precision or ultra-precision positioning devices. However, when the inner balls begin to roll or the moving direction reverses, these guideways are subject to rolling friction or nonlinear spring behavior. An ultra-precision device with a linear motor, referred to as a 'tunnel actuator' (TA), has been constructed to measure these phenomena. The application of a TA is beneficial for two reasons: it mostly cancels the attractive magnetic force between the stator and mover (armature), and its magnetic flux leakage is very low. The influence of the nonlinear spring behavior in ball guideways was investigated in this study using the pure driving force from a TA. The equilibrium between the driving force from the TA and the nonlinear spring force provided great accuracy for a positioning stage using a linear ball guideway.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.245-251
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• 2001

A fretting wear tester is developed for experimental study on the fuel fretting problem of light water reactor. The feature of the developed tester is it can simulate the existence of gap between spring and fuel rod as well as different contacting force including the just-contact condition (0 N on the contact). Used are a servo-motor, an eccentric cylinder and lever mechanism for driving system. A spacer grid cell is constituted with four strap segments (each segment has a spring). This fretting wear tester can also be used as a fatigue tester of a spacer grid spring with the frequency of more than 10 Hz. It is required to simulate the frequency of the vibrating fuel rod due to flow-induced vibration in a reactor. In fretting wear test, up to two span-length of a fuel cladding tube can be accommodated. A specimen of cladding tube of one span-length is specially designed, which can be extended for two-span test. For .fatigue test, a device for clamping the spring fixture is installed additionally, Presently, the tester is designed for the condition of air environment and room temperature. The variation of the reciprocal distance is measured to check the stability of input force, which will be exerted to the cladding (for fretting wear. test) and the spring (for fatigue test) specimen.

• 소음진동
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• 제10권4호
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• pp.584-595
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• 2000

We design a new actuator for high density optical device in order to control the radial tilting motion. The newly designed actuator makes it possible to control the tilting motion actively, while the coventional actuator compress tilting motion with passive spring. First of all, We present 3-dimensional modeling of actuator and accomplish the modal analysis and magnetic analysis of actuator. Due to these results, a new designed actuator has performance of high sensitivity and high second resonance frequency. Secondly, We present the 3-DOF dynamic modeling of the 4-wire spring type actuator. sensitivity analysis is performed to consider the assembling error, such as the difference of mass center and force center. From these results, the sensitivities of rotation due to the assembly error are revealed and design criteria of rotation is presented. And experimental results of a newly designed actuator are presented and compared with theoretical results. Finally, We propose a dynamic tilt compensation and high acceleration actuator for high density optical storage devices.

• 제어로봇시스템학회논문지
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• 제20권4호
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• pp.389-394
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• 2014

This paper presents the effect of a reflective force computed from a first-order-hold method on the stability of a haptic system. A haptic system is composed of a haptic device with a mass and a damper, a virtual spring, a sampler and a sample-and-hold. The boundary condition of the maximum virtual stiffness is analytically derived by using the Routh-Hurwitz criterion and the condition shows that the maximum virtual stiffness is proportional to the square root of the mass and the damper of a haptic device and also is inversely proportional to the sampling time to the power of three over two. The effectiveness of the derived condition is evaluated by the simulation. When the reflective forces are computed by using the first-order-hold method, the maximum available stiffness to guarantee the stability is increased several hundred times as large as when the zero-order-hold method is applied.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권3호
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• pp.158-166
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• 2005

The present study investigated experimentally and numerically the enhancement of absorption performance due to the waviness of falling film in the vertical absorber tube. The momentum, energy and mass diffusion equations were utilized to find out temperature and concentration profiles at both the interfaces of liquid solution and refrigerant vapor and the wall. Flow visualization was performed to find out the wetting characteristics of the falling film. The maximum heat transfer coefficient was obtained for the wavy flow using spring as an insert device through both numerical and experimental studies. Based on the numerical and experimental results, the maximum absorption rate was found for the wavy-flow using spring as the insert device. The differences between experimental and analytical results ranged from $5.0\;to\;25\%\;when\;Re_j>100$.