• 한국산학기술학회논문지
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• 제21권9호
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• pp.92-102
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• 2020

최근 도로 교통소음 대책으로 다공성포장이 새로운 대안으로 주목받고 있다. 다공성포장은 아스팔트 혼합물 속에 세립자의 비율을 줄여서 여러 개의 공극을 형성하게 하는 포장을 말한다. 이 공극으로 물이 배수되게 하여 교통사고를 줄이고 타이어 노면의 마찰 소음을 줄여주는 역할을 하게 된다. 저소음포장이 일반적으로 활발히 적용되기 위해서는 소음저감 효과에 대한 많은 검증이 필요하다. 본 연구에서는 단층 저소음포장과 복층 저소음포장의 소음저감 효과를 분석하기 위해서 수행되었다. 먼저 단틍 저소음포장과 복층 저소음포장이 시공되어 있는 세종구간을 선정하고 도로변에서 도로교통 소음을 측정하는 방식인 SPB방법으로 교통소음을 측정하였다. 교통영향요소로는 교통량, 속도 그리고 중차량 혼입률을 측정하였다. 측정결과, 복층저소음포장이 단층저소음포장보다 평균 7.95dB(A) 작게 평가되었다. 95% 신뢰도 수준에서는 7.57dB(A) 작게 평가되었다. 도로교통 소음에 미치는 영향요소로는 속도나 대형차 혼입률 보다는 교통량이 가장 크게 영향을 미쳤다. 교통량이 증가할수록 소음은 모두 증가했지만 두 포장 사이의 소음차이는 점차 감소하였다. 도로교통소음에 영향을 미치는 요소로는 교통요소보다 도로포장의 차이가 가장 크게 나타났다. 본 연구를 통해서 도로교통 소음을 줄이기 위한 대책으로 교통속도를 줄이거나 중차량의 통행을 제한하거나 교통량을 줄이는 것보다 도로포장을 바꾸는 것이 가장 효과적인 방법임을 알았다. 이를 검증하고 정량화하기 위한 광범위한 연구가 필요하다.

• 한국소음진동공학회논문집
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• 제18권10호
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• pp.997-1005
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• 2008

Linear motor stage is a useful device in precision engineering field because of its simple power transmission mechanism and accurate positioning. Even though linear motor stage shows fine positioning accuracy along travel axis, geometric dependent errors which relay on machining and assembling accuracy should be addressed to increase total positioning performances. In this paper, we suggests a cost effective yaw error compensation servo-system which is mounted on platform of the stage and nullify travel position dependent yaw error. This paper also provides a method of designing a sliding mode control which is robust to existing friction disturbance and model uncertainties. The reachability condition of slinding mode control for the yaw error compensating servo-system has been established. From some experimental results by using an experimental set-up, the sliding mode control showed its effective in disturbance rejection and its performance was superior to conventional linear controls.

• 한국소음진동공학회논문집
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• 제19권8호
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• pp.788-794
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• 2009

Various types of latch designs for hard disk drives using load/unload mechanism have been introduced to protect undesired release motions of a voice coil motor(VCM) actuator from sudden disturbances. Recently, various inertia-type latches have been widely used because locking performance is better than that of other types of latch. However there has been a limit in the inertia type in order to guarantee perfect latch and unlatch operations because of changes in latch/unlatch conditions due to mechanical tolerance and temperature-dependent friction. In this paper, a reliable and robust magnetic latch mechanism is proposed through only simple modifications of coil and yoke shapes in order to overcome the mechanical limit of current inertia-type latches. This new magnetic latch does not have only a simple structure but it also ensures reliable operations and anti-shock performance. The operating mechanism of the proposed latch is theoretically analyzed and optimally designed using an electromagnetic simulation.

• 한국소음진동공학회논문집
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• 제23권2호
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• pp.185-191
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• 2013

This paper presents a new method for roller design of IRB(isolation roller bearing) seismic isolation device using experimental evaluation. Three layered plate is adopted for the IRB in which the upper plate is placed on x direction and the lower plate is placed on y direction. The rollers placed in each plate make a plate movement. The roller is then optimally designed using variable geometric conditions. Stress distribution depends on the diameter and length of the roller and hence this is used for the determination of optimal geometry of the roller. In the experimental evaluation, it is observed that stress concentration at the end sides of roller is decreased and geometric coefficients depend on crowning dimension. In addition, in order to determine optimal design parameters of the roller the plastic deformation and friction are experimentally identified.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 말뚝기초 학술발표회
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• pp.65-84
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• 2000

Europe and US which have more restrictive regulations than Korea about the noise and vibration during construction are using Auger-cast Pile to reduce the problem relating with noise and vibration. However Auger-cast Pile has problems like difficult quality control and low bearing capacity. In Europe, Displacement in-situ concrete Pile has been used to sove that problems since 1990s, and Korea has performed the test construction in 1997 and it has been used as the real structural foundation since 1998. Test and real construction results verified that the allowable capacity of the pile(diameter = 410mm) is between 70 and 100ton. Though De Beer & Van Imps design method utilizing CPT result is used to calculate the bearing capacity of the Displacement in-situ Pile, Korea is dependant upon the SPT as the sounding test, so design method utilizing SPT result is necessary to promote the application of the pile. To find out reasonable design method using SPT result, rearing capacity of the pile constructed in sand and clay in Korea was calculated using Meyerhof, SPT-CPT translation method, Nordlund, Douglas and DM-7 method, and the calculation results were compared to the load test result. Analysis result shows that SPT-CPT translation method is more reliable than others and economical design can be possible because it considers efficiently the friction capacity of Displacement in-situ Pile.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.467-472
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• 2005

Load/Unload(L/UL) technology includes the benefits, that is, increased areal density, reduced power consumption and improved shock resistance contrary to contact start stop(CSS). It has been widely used in portable hard disk drive and will become the key technology for developing the small form factor hard disk drive. The main objectives of L/UL are no slider disk contact or no media damage. For realizing those, we must consider many design parameters in L/UL systems. In this paper, we focus on the effect of the ramp profile. We can find out the lateral velocities in L/UL process through experiments and simulations for force of voice coil motor and friction force on ramp. And then, we will gain the optimal design of ramp slope to maintain the minimum clearance of suspension dimple and slider with FE model. In special, after finding the point at which air bearing breaks and designing the ramp, we will identify the results for improving unload performance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.473-477
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• 2005

This paper presents a highly efficient HDD (Hard Disk Drive) spindle motor with a passive magnetic thrust bearing and a fluid dynamic journal bearing and its effectiveness is verified through experiment. It eliminates the mechanical friction loss of a thrust bearing which is around 18% of total power consumption of a 3.5' HDD spindle motor, by replacing a conventional fluid dynamic thrust bearing with a passive magnetic thrust bearing. The passive magnetic thrust bearing using permanent magnets is inherently unstable in radial direction. However, the radial fluid dynamic force of the fluid dynamic journal bearing counterbalances the radial magnetic force of magnetic thrust bearing to achieve the stability as the motor spins up. It has less or equivalent runout and less flying height than the conventional spindle motor.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.840-846
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• 2007

This paper investigates the dynamic behavior of a HDD spindle system due to the imperfect roundness of a rotating shaft. The shaft of a spindle motor rotates with eccentricity by the unbalanced mass of the rotating part. The eccentricity generates the run-out of a spindle motor which results in the eccentric motion of a rotating part. Roundness of a shaft affects this motion which limits the memory capacity of a HDD. This research proposes a modified Reynolds equation for the coupled journal and thrust FDBs to include the variable film thickness due to the roundness. Finite element method is used to solve the Reynolds equation for the pressure distribution. Reaction forces and friction torque are obtained by integrating the pressure and shear stress, respectively. The dynamic behavior is determined by solving the equations of a motion of a HDD spindle system in six degrees of freedom with the Runge-Kutta method to characterize the motion of a rotating part. This research shows that the roundness of a rotating shaft causes the excitation frequency with integer multiple of a rotating frequency.

• 한국소음진동공학회논문집
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• 제16권12호
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• pp.1215-1223
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• 2006

A leaf spring suspension has been widely used since it can carry big load and its simplicity. But one major drawback is the poor ride performance because of the friction in the system and the high stiffness coefficient. To overcome these, an air spring suspension can be used. The air spring suspension system can improve the ride of the heavy vehicle significantly and also it can adjust the height to the loading and unloading. The road tests for the truck with the leaf spring suspension and air spring suspension are performed to compare the ride quality of the two systems. To develop the air spring suspension system tailored to the target truck, chassis development procedure using CAE has been applied.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.852-858
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• 2007

This paper investigates the dynamic characteristics of a tilted HDD spindle system with fluid dynamic bearings (FDBs). Tilting motion of a HDD spindle system may be caused by improper manufacturing tolerance, such as imperfect cylindricity between shaft and sleeve of FDBs, imperfect perpendicularity between shaft and thrust as well as the gyroscopic moment of the unbalanced mass of the rotating part. Tilting motion may result in the instability of the HDD spindle system and it may increase the disk run-out to limit memory capacity. This research proposes a modified Reynolds equation for the coupled journal and thrust FDBs to include the variable film thickness due to the cylindricity and the perpendicularity. Finite element method is used to solve the Reynolds equation for the pressure distribution. Reaction forces and friction torque are obtained by integrating the pressure and shear stress, respectively. The dynamic behavior is determined by solving the equations of a motion of a HDD spindle system in six degrees of freedom with the Runge-Kutta method to study whirling and tilting motions. This research shows that the cylindricity and the perpendicularity increase the tilting angle and whirl radius of the rotor.