• Smart Structures and Systems
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• v.23 no.6
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• pp.695-702
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• 2019

The number of cable-stayed bridges has been increasing worldwide, causing issues in maintaining the structural safety and integrity of bridges. The stay cable, one of the most critical members in cable-stayed bridges, is vulnerable to wind-induced vibrations owing to its inherent low damping capacity. Thus, vibration mitigation of stay cables has been an important issue both in academia and practice. While a semi-active control scheme shows effective vibration reduction compared to a passive control scheme, real-world applications are quite limited because it requires complicated equipment, including for data acquisition, and power supply. This study aims to develop an Arduino-based integrated cable vibration control system implementing a semi-active control algorithm. The integrated control system is built on the low-cost, low-power Arduino platform, embedding a semi-active control algorithm. A MEMS accelerometer is installed in the platform to conduct a state feedback for the semi-active control. The Linear Quadratic Gaussian control is applied to estimate a cable state and obtain a control gain, and the clipped optimal algorithm is implemented to control the damping device. This study selects the magnetorheological damper as a semi-active damping device, controlled by the proposed control system. The developed integrated system is applied to a laboratory size cable with a series of experimental studies for identifying the effect of the system on cable vibration reduction. The semi-active control embedded in the integrated system is compared with free and passive mode cases and is shown to reduce the vibration of stay-cables effectively.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.138-144
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• 2017

A method for improving the integrated navigation performance in the INS/GPS navigation system by the considering that the condition that the geometric arrangement of the satellite is degraded due to limitation of the line of sight of the satellite such as geographic feature and GPS signal jamming is proposed. A variable covariance extended Kalman filter (VCEKF) that correlated to the measured covariance to the DOP of GPS is suggested. The navigation performance of integrated navigation system using EKF and VCEKF is analyzed by Monte-Carlo simulations. The result is verified that VCEKF has better estimation performance than EKF using fixed covariance on condition that DOP value is larger than the smaller value.

• Korean Journal of Computational Design and Engineering
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• v.17 no.5
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• pp.312-323
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• 2012

Planetary gearing is a gear system consisting of one or more planet gears, revolving about a sun gear. While the planetary gear system has many advantages- for example, high power density, large reduction in a small volume, multiple kinematic combinations, pure torsional reactions, and coaxial shafting, it has not been widely used because of its high bearing loads, inaccessibility, and design complexity. It is also necessary to shift several pairs of gear profiles at a same time. Therefore, designing profile shifted planetary gear system is a difficult and know-how dependent job. This study provides a practical solution to design a profile shifted gear system by the procedural design scheme, and proposes a bearing integrated structure of the dual stage profile shifted gear system with a robust output end. A dual stage profile shifted gear system with the bearing integrated structure is manufactured by the proposed design scheme in this study. This gear system is verified that it is good enough to commercialize, because it has high performance with high gear ratio and robust output end against axial and radial directional runouts in a small space.

• Current Optics and Photonics
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• v.4 no.3
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• pp.229-237
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• 2020

In this study, a beam-coupling system is designed to improve the coupling efficiency of achip-integrated spectrometer when the waveguide is arranged in a linear and discrete manner. In the proposed system the beam is shaped to be anti-Gaussian, to deposit adequate energy in the edge waveguides. The beam is discretely coupled to the corresponding waveguide by a microlens array, to improve the coupling efficiency, and is compressed by a toroidal lens to match the linear discrete waveguides. Based on the findings of this study, the coupling efficiency of the spectrometer is shown to increase by a factor of 2.57. Accordingly, this study provides a reference basis for the improvement of the coupling efficiency of other similar spectrometers.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.563-573
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• 2020

This research examined the effect of KHD Leadership toward Sustainable Shareholder Value and mediated by IT & Business Strategy Alignement and Integrated Supply Chain Management. Therefore, with this research, it is expected to be able to develop the KHD Leadership in State-owned enterprises' (SOEs) Indonesian. The population in this study were all echelon 1, 2, and 3 employees in the PT Pupuk Kalimantan Timur, PT Pupuk Petrokimia Gresik, PT Pupuk Sriwidjaja Palembang, PT Pupuk Kujang Cikampek, PT Pupuk Iskandar Muda, as many as N = 1002 people. The appropriate sampling technique used is Proportional Stratified Random Sampling (n=300 employees). The statistical analysis used is SEM-WarpPLS method. IT & Business Strategy Alignement and Integrated Supply Chain Management significant and positive on Sustainable Shareholder Value. IT & Business Strategy Alignment and IT Integrated Suppy Chain Management is a mediating variable between the influence of KHD Leadership on Sustainable Shareholder Value. Novelty in this research is the development of Ki Hadjar Dewantara Leadership as the development of the concept of Javanese leadership that grows inherent in Indonesian society, especially Javanese society and is believed to be applicable in business and industrial organizations in Indonesia, of course it can also be implemented in Pupuk Indonesia Holding Company.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.49-54
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• 2010

An integrated machining center is developed for high precision and productivity manufacturing. The developed machine is composed of the high precision spindle using ball bearings, the high stiffness bed and the three axis CNC controller with the high resolution AC servo motor. In this paper, structural and modal analysis for the developed machine are carried out to check the design criteria of machine. The analysis is carried out by FEM simulation with using the commercial software, CATIA V5, ANSYS and ARMD. The simulation model of machine is made by shell and solid finite elements. This study also presents the measurement system on the modal analysis of an integrated machining center. The weak part of the machine is found by the analytical evaluation. The results provide with the structural modification data for good dynamic behaviors. And the safety of machine is confirmed by the modal analysis of modified machine design. As this study results can be trustworthy with the analysis of ANSYS and CATIA, integrated machining center can be successfully developed.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.118-127
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• 2014

The configuration such as series, parallel and k-out-of-n of a repairable system directly affects its reliability. The maintenance strategy can also affect the overall performance of the system. The objective of this work is to investigate the possible trade-off between the configuration of a repairable k-out-of-n system and its maintenance strategy. The redundancy is considered to be the design decision variables, whereas the preventive maintenance period is considered to be the maintenance decision variables. The optimization model is used to minimize the overall life cycle cost associated with the system, considering constraint on reliability. Finally, genetic algorithm is used to find the optimal values for the decision variables. The result is compared with optimal values for considering redundancy and maintenance respectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.186-196
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• 1999

The CPS provides data with long-term stability independent of passed time and the INS provides high-rate data with short-term stability. By integrating these complementary systems, a highly accurate navigation system can be achieved. In this paper, a loosely-coupled GPS/INS integration system is designed. It is a simple structure and is easy to implement and preserves independent navigation capability of GPS and INS. The integration system consists of a NCU, an IMU, a GPS receiver, and a monitoring system. The navigation algorithm in the NCU is designed under the multi-tasking environment based on a real-time kernel system and the monitoring system is designed using the Visual C++. The integrated Kalman filter is designed as a feedback formed 15-state filter, in which the states are position errors, velocity errors, attitude errors and sensor bias errors. The van test result shows that the integrated system provides more accurate navigation solution then the inertial or the GPS-alone navigation system.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.2
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• pp.166-178
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• 2024

Objectives: The 12 occupational exposure limits(OELs) for chromium and its compounds in Korea were set by applying the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs). However, this is significantly different from the TLVs after the existing TLVs were integrated and withdrawn in 2018, so it is necessary to review the revision. Methods: Various documents related to chromium OELs were reviewed, including the ACGIH TLV Documentations for chromium and its compounds. A field survey was conducted targeting workplaces handling chromium and its compounds. Based on this, a revised OELs were proposed and a socio-economic evaluation was conducted. Results: The OELs for chromium compounds in Korea was first enacted in 2002, and in 2007, the OELs for chromium (hexavalent) compounds (insoluble) was lowered from 0.05 mg/m³ to 0.01 mg/m³. In 2008, the OELs for strontium chromate was newly established as 0.0005 mg/m³, and in 2018, the OELs for calcium chromate was newly established as 0.001 mg/m³. Total chromium and hexavalent chromium were measured for each of 6 samples at 2 welding sites, 4 plating sites, and 2 spray coating sites. When omparing the average of the results measured by ICP, a total chromium analysis method, and the analysis results by IC, a hexavalent chromium analysis method, only workplace 4 was the same, and total chromium was evaluated more, and total chromium was evaluated at 0.0004 to 0.0027 mg/m³. And hexavalent chromium was evaluated as non-detection ~ 0.0014 mg/m³. Amendment ①: The exposure standard for hexavalent chromium is not divided into water soluble, insoluble, chromium ore processing, and other hexavalent chromium compounds, and is integrated into 0.01 mg/m³, which is the level of chromium (hexavalent) compound (insoluble)., OELs for chromium (metal) and chromium (trivalent) compounds are integrated into chromium (trivalent) compounds, and the exposure level is maintained. Amendment ②: As in the amendment ①, the OELs are integrated, but the level is lowered to 0.005 mg/m³, which is the OELs of OSHA, and there is a grace period of 4 years. Amendment ③: As in the amendment ①, the OELs are integrated, but the level is lowered to 0.0002 mg/m³, which is the exposure standard of ACGIH, and there is a grace period of 5 years. Conclusions: Amendment ①: The change in the OELs is insignificant, so the cost required is small, and the benefit/cost ratio is greater than 1, so there is no problem in applying the amendment. Amendment ②: In all scenarios except chromium 6(insoluble), the benefit/cost ratio is greater than 1, so it is thought that there will be no major problem in applying the amendment. Amendment ③: Since the benefit/cost ratio is less than 1 in all scenarios, it is thought that the total social benefit that can be obtained when applying the amendment is not large.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.7
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• pp.21-31
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• 1996

An intelligent integrated control system is designed for the active steering and the left/right traction force distribution control of electric vehicles, where input-output linearization is employed. Also, a fuzzy-rule-based cornering force estimator is suggested to avoid using an uncertain highly nonlinear expression, and a neural network compensator is additively utilized for the estimator to correctly find cornering forece. With these techniques, the proposed control system is shown by simulation results to be robust against drastic change of the external environments such as road conditions.