• Journal of the Semiconductor & Display Technology
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• v.6 no.1 s.18
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• pp.31-36
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• 2007

Effect of coulomb friction and backlash on the single loop position control has been studied for the precision position control. We have showed the limit cycle on the single loop system which used a ball screw that had the backlash. Also, we have made an inner loop with a classical velocity and torque controller which was forcing the current of d axis to be zero by using a permanent-magnet synchronous motor and composed the outer loop with linear encoder for sensing a position of the loader. Also, we have used least squares fit(LSF) observer for reducing noise when we got velocity from position outputs. We have shown a good result by using the dual loop through simulation and experiment.

• Dementia and Neurocognitive Disorders
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• v.22 no.4
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• pp.139-147
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• 2023

Background and Purpose: Dual walking task such as crossing over an obstacle may serve as an excellent tool for predicting early cognitive decline. Thus, this study aimed to investigate correlation between walking while crossing over an obstacle and executive functions under different gait phases to validate the use of walking with an obstacle for predicting early cognitive decline. Methods: A cross-sectional study was conducted on 48 elderly individuals from 2 day-care centers and 3 welfare-centers in Seoul and Gyeonggi, Korea. Executive function tests (Trail Making Test, Stroop test) and dual walking tests (gait speed, cadence, stance time, gait cycle time) were performed and compared using partial correlation analysis. Results: There were significant correlations between executive function and most of the gait variables (stance time, cadence, and gait cycle time) (p<0.05) when crossing over an obstacle while walking. Especially, stance time exhibited significant correlations with most executive functions (p<0.05). Conclusions: When evaluating executive function during walking with an obstacle, post-obstacle-crossing phase and stance time need to be observed.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.187-190
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• 2012

An experimental study was performed to provide the effect of PM reduction and the improvement of diesel alternative ratio utilizing diesel-natural gas dual-fuel combustion mode in a retrofit 3.4-liter diesel engine. In order to achieve the same power as the original diesel engine, engine control unit (ECU) of the dual-fuel engine was calibrated. As a result, diesel alternative ratio was found that the maximum value of diesel alternative ratio was about 96%. Finally PM emission experiment was performed in C1-8 mode cycle and it was shown PM emission was extremely reduced down to $7.42{\ast}10^{-7}g/kWh$ comparing with mechanical diesel engine.

• Journal of Power Electronics
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• v.16 no.1
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• pp.133-141
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• 2016

This paper focuses on the development of a Five-Level Flying-Capacitor Dual Buck Inverter (FLFCDBI) based on the main circuit of dual buck inverters. This topology has been described as not having any shoot-through problems, no body-diode reverse recovery problems and the half-cycle work mode found in the traditional Multi-Level Flying-Capacitor Inverter (MLFCI). It has been shown that the flying-capacitor voltages of this inverter can be regulated by the redundant state selection within one pole. The voltage balance of the flying-capacitors can be achieved by charging or discharging in the positive (negative) half cycles by choosing the proper logical algorithms. This system has a simple structure but demonstrates improved performance and reliability. The validity of this inverter is conformed through computer-aided simulation and experimental investigations.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.37-40
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• 2005

Reinforced dual concrete beam (RDC beam) is the reformed system that improves the overall structural properties of beam by partially applying high performance steel fiber reinforced concrete (HPSFRC) in the lower tension part of conventional reinforced concrete beam (RC beam). Fatigue test was done to prove the structural superiority of RDC beam. As a result of fatigue test, the deflection of RDC beam was decreased obviously and the slope of number of cycle-deflection relation curve of RDC beam was increased gently in comparison with RC beam.

• Journal of the Korean Institute of Gas
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• v.22 no.4
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• pp.63-73
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• 2018

Innovative technical process for Energy Storage System (ESS), Liquid Air Energy Storage system (LAES) is mature technologies based on the gas liquefaction process. In spite of many advantages such as high energy density, no geographical constraints, low investment costs and long useful life, the system has not yet widely commercialized due to low round trip efficiency. To improve RTE and acquire high yield of liquid air, various configurations of LAES process have been considered. In this research, dual refrigerants cycle (R-600a and methanol) for air liquefaction and thermal oil circulation for power generation via liquid air gasification have been applied to improve cycle performance significantly using Aspen HYSYS simulator.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.227-227
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• 2017

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.1
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• pp.110-125
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• 2007

Various different types of yard cranes are used in container terminals. Examples are rubber tired gantry cranes,rail mounted gantry cranes, overhead bridge cranes, dual rail-mounted gantry cranes, and automated stacking cranes. The kinematics and handling characteristics of these yard cranes are different from each other. Ttiis study analyses charactehstics of generic types of yard cranes which represent various yard cranes m practice Demg used in several types of block layouts, Considering specifications of yard cranes and block layouts, expected cycle times and variances of the cycle time are estimated for different handling activities.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.148-153
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• 2023

A digital controller uses a microprocessor and is a controller implemented as a program. This method has the advantage of being more maintenance-friendly than existing analog controllers. However, it inevitably requires computation time to execute the internal program. Therefore, the digital controller uses a method of controlling the system at a certain cycle by considering this time, and this cycle is very closely related to the performance of the microprocessor used. In other words, in the case of very high performance, this control cycle can be shortened to near real time, but this may result in a disadvantage in terms of cost. In this paper, we propose a method to solve this problem by implementing two processors with slightly lower performance in a control system in a series-parallel structure. For this purpose, we will use a digital distributed control system and implement an experimental system to examine its effectiveness.

• Plant Journal
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• v.15 no.2
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• pp.46-55
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• 2019

This paper presents a LNG Liquefaction cycle configuration using two stages of methane expansion (i.e. spliting into two stages as warm & cold to generate an additional inflection point within a cold composite curve) and a single stage of nitrogen expansion to improve the efficiency of the conventional Methane & Nitrogen Expansion Cycle. In comparison with Double Nitrogen Expansion Cycel and Methane & Nitrogen Expansion Cycle, the cycle efficiency has increased approximately from 13.92 and 13.13 to 12.08 kW/ton/day (8~15% efficiency increase). A Life Cycle Cost (LCC) analysis based on Net Present Value (NPV) also show an improvement in therms of project NPV, against a minor increment of a CAPEX.