• 한국정밀공학회지
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• 제19권1호
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• pp.65-70
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• 2002

An analysis method for calculating motion accuarcy of double sides hydrostatic table is proposed in this paper. In this method, profiles of each rails are assumed as periodic function, therefore it is represented as the sum of spacial frequencies. Bearing clearance at any position rail is depended on the variation of linear, angular motion error of table and the form errors of both sides of a rail. Finite element method is applied to calculate pressure distributions in bearing clearance. In order to simplify the analyzing process, double sides table model is converted into equivalent single side table model. Results calculated by the proposed modeling method agree well with the results directly caculated by double sides modeling method, and also agree well with experimental results. From the theoretical and experimental analysis, it is verified that the proposed analysis method is very effective to analyze the motion accuracy of double sides hydrostatic table.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.135-136
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• 2006

A precise linear motion stage supported by magnetically preloaded air bearings is introduced where preloading magnetic actuators are combined with permanent magnets and coils to adjust air bearing clearance by controlling magnetic force actively. Each of the magnetic actuators has a permanent magnet generating nominal magnetic flux for required preload and a coil to perturb the magnetic force resulting adjustment of air-bearing clearance. The characteristics of porous aerostatic bearing are analyzed by numerical analysis, and analytic magnetic circuit model is driven for magnetic actuator to calculate nominal preload and variation of force due to current. A 1-axis linear stage motorized with a coreless linear motor and a linear encoder is built for verifying this design concept. With the active magnetic preloading actuators controlled with DSP board and PWM power amplifiers, the active on-line adjusting tests about the vertical, pitching and rolling motion were performed, and the result shows very good linearity.

• 수산해양기술연구
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• 제26권2호
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• pp.173-179
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• 1990

한국산 자기컴퍼스 카아드의 안정성을 조사하기 위하여 인공자장발생장치에 의한 수평자장의 세기와 카아드의 크기 및 컴퍼스액의 점성계수별 제진특성을 측정한 결과는 다음과 같다. 1. 실험에 사용한 컴퍼스 종류별 수평자장의 세기에 따른 제진특성은 A, B, C, D컴퍼스 모두 수평자장의 세기가 강할수록 주기와 감도는 짧고, 과행각은 크게 나타났으며, 극지와 같이 수평자장이 약한 0.03gauss에서는 진요회수와 마찰각등이 ISO의 허용범위 보다 미달되거나 크게 나타나, 컴퍼스 카아드의 지북단이 자북으로 복귀하지 않았다. 2. 한국근해의 표준자장인 0.30gauss에서 측정한 컴퍼스 종류별 성능제요소를 IMO NAV/ANNEX II 의 성능표준과 비교해 본 결과, 주기를 제외한 전 요소가 IMO NAV/ANNEX II의 성능표준의 허용범위 이내로 한국근해의 사용이 적합하나 지자기의 수평자장이 0.18gauss보다 약한 위도 60$^{\circ}$이상의 고위도 해역에서의 사용은 부적합하다고 생각된다. 3. 한국산 자기컴퍼스 카아드의 크기별 clearance에 대한 제진특성은 clearance가 클수록 감도는 예민하고 주기는 짧아져 방위지시부의 지북단이 자북으로 복귀하는 시간이 짧아진 반면 마찰각은 각각 $1.5^{\circ}$, 0$^{\circ}$, 0.5$^{\circ}$, 2.0$^{\circ}$가 되어 카아드의 크기가 170mm와 175mm로써 clearance가 10.0mm와 12.5mm일때가 마찰오차는 IMO NAV/ANNEX II의 성능표준의 허용범위 이내로 가장 적게 나타났다. 4. 카아드의 크기가 175mm, 자침의 자기능률이 1,925 C. G. S. E. M. U인 자침을 사용할 경우 한국근해의 수평자장 0.30gauss에서는 컴퍼스 액의 점성계수가 0.021poise로서 에칠알콜과 증류수의 혼합비율이 4 : 6일 때가 가장 적합하다고 생각된다.

• IEIE Transactions on Smart Processing and Computing
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• 제5권2호
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• pp.107-116
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• 2016

Premature babies of less than 37 weeks gestation might require oxygen therapy as an integral part of treatment and respiratory support. Because of their under-developed lungs, these so-called "preemies" might contract respiratory distress syndrome (RDS). To treat RDS, neonatal oxygen therapy is administered, where controlled oxygen gas is measured as a fraction of inspired oxygen ($FiO_2$). However, exposure to high oxygen content during long treatment could cause oxygen intoxication, which might cause permanent blindness due to retinopathy of prematurity (ROP), whereas insufficient oxygen exposure could cause severe hypoxia. A doctor would use oxygen saturation ($SpO_2$) data and prescribe a dose of $FiO_2$ to maintain $SpO_2$ within a suitable range. One objective is to maintain $SpO_2$ within the acceptable range using $FiO_2$ that is as low as possible. Adjustment of $FiO_2$ would normally be done by nurses every 15 to 30 minutes, which might not be safe in many situations. An error in $FiO_2$ adjustment during a manual procedure could be as large as +/- 2.5%. This paper presents a system that can determine an $FiO_2$ value suitable to the current $SpO_2$ and that automatically adjusts $FiO_2$ with an error clearance of +/- 0.25%.

• 한국생산제조학회지
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• 제21권1호
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• pp.130-136
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• 2012

Dynamic as well as static and geometric design parameters such as inertia, tooth profile, backlash and clearance can be directly considered via multi-body dynamic analysis along with contact analysis. However, it is time consuming to use finite elements for the consideration of the tooth flexibility in the multi-body dynamic analysis of gears. A computationally efficient procedure, so called, Gear Stiffness Module, is suggested to resolve this calculation time issue. The characteristics of gear tooth compliance are discussed and rotational stiffness element concept for the Gear Stiffness Module is presented. Transmission error analyses for a spur gear system are carried out to validate the reliability and efficiency of the module. Compared with the finite element model, the Gear Stiffness Module yields considerably similar results and takes only 3% of calculation time.

• Journal of Welding and Joining
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• 제21권4호
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• pp.80-86
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• 2003

Arc-spot welding is generally used in joining of precise parts such as case and core in electric compressor. It is important to control joining deformation in electric compressor because clearance control of micrometer order is needed for excellent airtightness and anti-nose. The countermeasures for this deformation in field have mainly been dependent on rule of try and error by operator's experience because of productivities. For control this deformation problem without influence on productivities, development of exact simulation model should be needed. In this study, on the basis of previous study, the analysis model io predict deformation of precise order in arc-spot welded structure with non-uniform stiffness is brought up through feedback and tuning between monitoring data and analysis results. For this, deformation monitoring system was built and boundary condition considering mechanical melting temperature was applied.

• 한국소음진동공학회논문집
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• 제14권3호
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• pp.201-207
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• 2004

High speed rotating airflow inside a HDD chamber causes sub-micron scale disk vibration that could generate significant TMR problems in most of current HDD products. Many publications are presented for the reduction of airflow excitation. One of the most effective methods widely adopted in high-end HDD products is SqueezeAir Bearing Plate (SABP). However, because of its tight assembly clearance between the damper and disk, this method could not be easily implemented in volume production. This article presents a disk damper design that is modified to be feasible for volume production by virtue of a new airflow modeling method.

• Journal of Welding and Joining
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• 제20권4호
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• pp.544-550
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• 2002

Arc-spot welding is generally used in joining of precise parts such as case and core in electronic compressor. It is important to control joining deformation in electronic compressor because clearance control in micrometer order is needed for excellent airtightness and anti-nose. The countermeasures far this deformation in field have mainly been dependent on the rule of try and error by operator's experience because of productivities. For control this deformation problem without influence on productivities, development of exact simulation model should be needed. In this study, to solve this deformation problem in arc-spot welded structure with case and core, we intend to make a simulation model that is able to predict deformation in precise order by tuning and feedback between sensing data and simulation results. This paper include development of heat input model for arc-spot welding, temperature monitoring and make a heat transfer model using sensing data in product.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.579-585
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• 2003

This paper investigates the whirling, tilting and flying motion of a HDD spindle system supported by FDB experimentally. Experimental setup is built to measure the flying, whirling and tilting motion of the HDD spindle system, and three capacitance probes fixed on the xyz-micrometers measure the displacement of a HDD spindle system in the xyz-directions. This research shows that the tilting and whirling motion is mostly dependent on the centrifugal force and the gyroscopic moment due to the unbalanced mass of a HDD spindle. It also shows that the rotating HDD spindle starts to float to the equilibrium position in the z-direction until the weight of the rotating spindle is equal to the supporting pressure generated in the upper and lower thrust bearing.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.227-233
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• 2002

A vehicle longitudinal control strategy with guaranteed string stability for vehicle stop-and-go(SG) cruise control is presented in this paper. The SG cruise control systems should be designed such that string stability can be guaranteed in addition to that every vehicle in a string of SG cruise control vehicles must track any bounded acceleration and velocity profile of its preceding vehicle with a bounded spacing and velocity error. An optimal vehicle following control law based on the information of the 1311owing distance (clearance) and its velocity relative to the vehicle ahead (relative velocity) has been used and string stability analysis has been done based on the control law and constant time gap spacing policy, A validated multi-vehicle simulation package has been shown that the string stability analysis using the approximate model of the vehicle servo-loop which includes vehicle powertrain and brake control system dynamics is valid in the design of the SG cruise control law with guaranteed string stability.