• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.6
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• pp.64-69
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• 2016

Vehicle clutch measurement for disc cushion variation was developed for the production of high quality Dual clutch transmissions. The developed device is composed of load cells for load measurement and LVDT for measuring the distance variation measurement in cushion variation. The servo motor-driven electric press for flexible loads that was developed was controlled by a PC-based HMI system, LabVIEW, and the device was able to continuously record real time measurement data with the accuracies of ${\pm}0.1\;kgf$ load and ${\pm}5{\mu}m$ cushion amount, which is far above the requirements of commercial vehicle standards.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.170-175
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• 2018

For the seismic performance, it is necessary to prevent the destruction of the expansion joint device due to the appropriate deformation of the expansion joint device due to the seismic force. Recently, the hinge is installed on the fingering of the expansion joint device in Korea, New products are being developed. In this paper, we have experimentally evaluated the real scale resistance of the expansion joints with rotational finger joints against load at right angle to the bridge axis. Experimental results show that the maximum horizontal displacement is about 21.1mm for conventional stretch joints and 51.00mm for seismic stretch joints. It is presumed that the existing expansion joint test specimen is resistant to the load in a direction perpendicular to the throat axis, and then the bending and shear deformation of the finger are excessively generated and the fracture phenomenon is likely to occur. On the other hand, in the case of the seismic expansion joint, the deformation of the load due to the load is absorbed by the hinge of the finger with respect to the load in the direction perpendicular to the throat, so that only horizontal deformation in the direction of load action.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.30-30
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• 2011

국내의 내진설계 기준은 1988년에 처음 도입되었으며, 최근 점차 강화되고 있는 실정이다. 공동주택에 주로 적용되는 전단벽식 구조시스템에서 증가된 지진력에 저항하기 위해서는 벽량과 철근이 증가하게 되어 공사비가 상승하게 된다. 이러한 단점을 보완하기 위한 제진설계의 필요성이 대두되고 있는 실정인데, 기존의 제진장치는 주로 가새형 또는 벽체형을 대부분이라 평면계획에 제약이 있다. 따라서 전단벽식 구조의 공동주택의 제진설계 시에는 우리나라와 같은 중 약진 지역에 적합하고 저렴한 비용으로 충분한 내진성능과 평면의 가변성을 확보할 수 있는 댐퍼의 선택이 필요하다. 본 연구의 목적은 기존의 가새형 및 벽체형 제진장치의 국내 공동주택 적용시의 문제점인 평면의 가변성 확보에 유리하고, 수동형 제진장치의 장점을 추구할 수 있는 마찰댐퍼를 삽입한 커플링보 제진시스템의 내진성능을 조사하는 것이다. 내진성능을 평가하기 위해서 실대형 커플링보 실험체를 계획하고 제작하였다. 실험체는 2개로 구성되어 있으며, 하나는 기존의 철근배근 상세를 갖는 철근콘크리트 커플링보 실험체와 커플링보에 마찰댐퍼가 삽입된 실험체이다. 횡하중에 대한 성능을 평가하기 위해서 유사정적 반복가력실험을 실시하였다. 엑츄에이터로부터 실험체 상보의 가력지그를 통해 하중이 전달되도록 하였으며, 가력은 최초 0.25%의 층간변형각부터 변위제어를 통해 목표 층간변형각인 1.5% 이상까지 진행되도록 하였다. 실험결과, 두 실험체의 이력곡선과 에너지 흡수능력을 평가하였다. RC 실험체는 핀칭현상이 관찰되었고, 가력이 진행됨에 따라 커플링보와 벽체에서의 균열이 확산되어 종국적으로 취성적인 커플링보의 전단파괴가 발생하였다. 마찰댐퍼를 삽입한 실험체는 계획된 마찰거동이 잘 발휘되어 목표 층간변형각인 1.5%까지 이선형거동이 잘 나타났다. 최대 내력은 RC 실험체가 3배 이상 크지만, 누적층간변형각에 따른 에너지 흡수능력은 마찰댐퍼 실험체가 2배 이상 우수한 결과를 보였으며, 커플링보 및 벽체에서의 균열이 매우 저감되었다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.59-66
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• 2001

The post-peak analysis of concrete structures is carried out using a nine-node Reissner-Mindlin(RM) shell element which is formulated by using degenerated solid concepts. In order to avoid element deficiencies inherited in the standard RM shell element, assumed strains are adopted in the present shell element. A microscopic material model is adopted to represent the inelastic characteristic of concrete material. In particular, a concrete softening model is introduced to this material model. The arc-length control method is used to trace the post-peak behaviour of concrete structures. From the numerical test of the single-edge-notched beam, the present shell element shows a reasonable agreement with experimental data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.597-604
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• 2010

This study focuses on the design of a mechanical joint for a zero moment crane (ZMC), which is a specialized loading/unloading system used in a mobile harbor (MH). The mechanical joint is based on the concept of zero moment point (ZMP), and it plays an important role in stabilizing a ZMC. For effective stabilization, it is necessary to ensure that the mechanical joint is robust to a wide variety of loads; further, the joint must allow the structures connected to it to perform rotational motion with two degrees of freedom By adopting a traditional design process, we designed a new mechanical joint; in this design, a universal joint is coupled with a spherical joint, and then, deformable rolling elements are incorporated. The rolling elements facilitate load distribution and help in decreasing power loss during loading/unloading. Because of the complexity of the proposed system, Kriging-based approximate optimization method is used for enhancing the optimization efficiency. In order to validate the design of the proposed mechanical joint, a structural analysis is performed, and a small-scale prototype is built.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.11-22
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• 2006

Message Signs (VMS) structures offer an increase in traffic safety through their ability to relay massages to motorists for warnings of hazards ahead, traffic congestion, accidents, and lane closings. The geometry of these signs sometimes results in the significant cyclic loading of the supports structure due to wind gusts, which can result from passing trucks or from natural wind. This study presents the results of analytical and experimental investigations of VMS structures. The commercially available softwareGTSTRUDL (2003) was used to perform space-frame structural analyses of these welded tubular structures. Fatigue evaluations were performed using stress ranges from field measurements and from structural analyses. Based on the results of the structural analyses that were conducted, where fatigue design loadings that had been derived from AASHTO Specifications for Structural Supports for Highway Signs, Luminaries, and Traffic Signals (2001) were used, the structures that had been studied were found not to have infinite fatigue life. According to the limited measurements that were made in this study, the fatigue design loadings derived from AASHTO Specifications (2001) appear to be conservative, but they are not overly conservative. The results of this study should be used to make a reasonable design of VMS structures, and to maintain their standards.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.761-767
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• 2007

In centralized control system, complicated control systems including sensors, power supply and dampers should be required to satisfy the target response of large-scale structures. The practical applications of the centralized control system, however, is very difficult due to high order finite element model of structures, uncertainty of models, and limitations of the excitation system. In this study, the decentralized response-dependent MR damper of which magnetic field is automatically modulated according to the displacement or velocity transferred to the damper without any sensing and computing systems. this decentralized response-dependent MR damper are investigated according to the ranges of relative magnitude between the control force of MR damper and the story shear force of structures by nonlinear time history analysis. Finally, its performance is compared with centralized LQR algorithm which is used in general centralized control theory for a three story building structure.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.1
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• pp.124-131
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• 2019

A design study of gas turbine engine simulation duct was conducted to investigate the operating characteristics and control gain tunning of the Altitude Engine Test Facility(AETF). The simulation duct design involved testing variable spike nozzle and ISO standard choking nozzle to verify the measurements such as mass flow rate and thrust. The simulation duct air flow area was designed to satisfy Ma 0.4 at the aerodynamic interface plane(AIP) at engine design condition. The test conditions for verifying the AETF controls and measurement devices were deduced from 1D analysis and CFD calculation results. The spike-cone driving part was designed to withstand the applied aero-load, and satisfy the axial traversing speed of 10 mm/s at whole operation envelops.

• Korean Journal of Psychosomatic Medicine
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• v.6 no.1
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• pp.22-27
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• 1998

Thirteen female patients of somatization disorder, undifferentiated somatoform disorder and somatoform disorder, NOS, diagnosed by DSM-IV were studied for their pain threshold and serum testosterone and the results were compared with the respective data of 20 control females. The results are as follows : 1) The pain threshold as measured by Variable Weight Pressure Algometer was significantly lower in the patient group(153.8${\pm}$39.5 gm/$0.05mm^2$) as compared to the control group(197.5${\pm}$66.7 gm/$0.05mm^2$)(p<0.05). 2) There was no significant difference of serum testosterone between the patient(0.175${\pm}$0.081 ng/ml) and the control(0.174${\pm}$0.108 ng/ml) groups. 3) A significant positive correlation was noted between the pain threshold and serum testosterone in the patient group(r=0.632, p<0.05, two tailed, Pearson's correlation test), but not in the normal control group(r= -0.405). From these results, it was suggested that the role of testosterone in endogenous pain control system might be more important in somatoform disorders than normals.