• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.172-179
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• 1998

This paper proposes an identification method for modes of a thin plate where multiple actuators and sensors are bonded. When a natural frequency of a mode is decoupled from all other natural frequencies, the mode can be identified separatedly with a bandpass filter. Since a thin plate has resonant peaks at natural frequencies, the bandpass filter can be designed to extract the signal of the mode to be identified. Parameters of the second order linear differential equation of the mode can be obtained to apply the Least square method to the extract the modal signal. The proposed identification method is applied to an all-clamped plate with two pairs of piezoelectric actuators and sensors. The outputs of the identified model match with the experimental data well.

• Journal of Welding and Joining
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• v.9 no.3
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• pp.34-40
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• 1991

An automatic welding system was constructed with a personal computer to capture the welding data in addition to vision seam tracking for the gas metal arc welding process. The monitoring of welding signals is composed of the acquisition of welding voltage and current, obtained by using two differential amplifiers and A/D converters, and processing of the measured data. Using interrupt handing circuit for time sharing, two jobs of seam tracking and monitoring were performed at the required sampling time. Relations between welding signals and various welding circumstances were analyzed from the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.73-80
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• 2016

The preliminary test for the dual mode plasma torch system was carried out to explore the operation properties in advance. The dual mode plasma torch system that is able to operate in transferred, non-transferred, or dual mode is very adequate for melting the mixed wastes including nonconductive materials such as concrete, asbestos, etc. since it exploits both the high efficiency of heat transfer to the melt in transferred mode and stable operation in non-transferred mode. Also, system operation including restarting is reliable and very easy. A stationary melter with a refractory structure was designed and manufactured considering the melting behavior of slags to minimize the refractory erosion. The power supply for the dual mode plasma torch system built with high power insulated gate bipolar transistor (IGBT) modules has functions for both current control and voltage control and is sufficient to suppress the harmonics during the operation of the plasma torch. The power supply provides two different voltages for transferred operation and non-transferred. It is confirmed that the operation voltage in transferred is always higher than non-transferred. The dual mode plasma torch system was successfully developed and is under operation for a melting experiment to optimize operation data.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.595-600
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• 2011

This study analyzed passenger's access modes that connect to regional railway station and developed a model of access mode choice based on transit smart card data of Seoul station as a case study. The study boundary includes sixteen bus stops around the station. The results show that most passengers access to station have less than two transfers. Of total 15000, eighty percent of passengers use metro and the rest of people take a bus. Interestingly, it is found that almost same proportions of passengers use metro and bus for egress the station. Consequently, metro is found to be most likely used mode compared to bus for both access and egress trips.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.74-77
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• 2011

PSPICE modeling of a commercial LED driver IC (TOP245P) and PC817A optocoupler is proposed for the switch-mode power supply (SMPS) (applicable to LED driver) design and simulation. An analog behavioral model of the TOP245P IC including the shunt regulator, under-voltage(UV) detection, over-voltage(OV) shut-down and SR flip-flop is developed by using PSPICE. The empirical equation of PC817A current transfer ratio (CTR) is fitted from the datasheet of PC817A. Two types of SMPSs are simulated with the averaged-model and switching-model. The simulation results by the proposed PSPICE models are in good agreement with those in the data sheet and an experimental data.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3642-3651
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• 1999

In this paper, we propose a new caching scheme for continuous media data where the buffer allocation unit is divided into two modes : interval and object. All of objects' access patterns are monitored and based on the results of monitoring, a request for an object is decided to cache its data with either interval mode or object mode. The results of our simulation show that our proposed caching scheme is better than the existing caching algorithms such as interval caching where the access patterns of the objects are changed with time.

• Proceedings of the KSRS Conference
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• v.2
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• pp.913-916
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• 2006

Spatial distribution, seasonal and interannual variability of chlorophyll a concentration in Okhotsk Sea from SeaWiFS data between 2001 and 2004 were describe. An Empirical Orthogonal Function method was applied for analysis data. The ten modes described about 85% of total variance. Two maxima were defined - more intensive in spring and weaker in autumn. The first mode showed zones with chlorophyll a concentration during maximum bloom. The second mode specified timing of spring bloom in various regions in Okhotsk Sea. Analysis of SeaWiFS data indicated connection between highest chlorophyll a concentration and sea surface temperature limits during spring bloom. Similar relation was not found during fall bloom.

• Composites Research
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• v.22 no.5
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• pp.30-36
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• 2009

The failure strengths and modes in carbon fiber reinforced polymeric composites, with two serial bolt-fastened composite joints, were investigated to evaluate the typical joint configurations of composite components. The parametric studies were performed experimentally at room temperature dry and elevated temperature wet, $82.2^{\circ}C$ on several different laminate configurations. Based on the experimental data presented, two basic load-displacements curves are observed. Each failure mode has the characteristic curve. It is showed that the bearing failure mode occurs in elevated temperature wet condition. It is analysed that the strength of bearing failure mode is not highly depending on the effective modulus of specimen. The failure strength at elevated temperature wet is decreased by the cause of interfacial deterioration between fiber and matrix with moisture absorption.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.51-58
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• 2010

This paper suggests a control technique of the two axes precision stage. The stage is supported by four flexible spring hinges and driven by two piezoelectric actuators. The dynamic motion of the stage is analysed by the finite element method and identified by the frequency domain modeling technique based on the experimental data. The sliding mode control with integrator is applied to improve the tracking ability of the stage to the complex reference input signal. Experimental results demonstrate that the proposed modeling schemes and control algorithm can be used effectively for the two axes stage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.45-51
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• 2019

Modern file systems have journaling mechanism to maintain their stored state consistently even under unexpected system crashes or disasters. However, the journaling makes I/O throughput lower. This performance degradation comes from the ordering mechanism between the data buffer and metadata buffer and two-staged buffer writing. Especially, if the data buffer and metadata buffer are journalled at the same time, then it incurs significant performance degradation due to the two-staged writing. That shows the trade-off relation-ship between I/O performance and system reliability. In this paper, we propose RFJ: a reliable and fast jour-naling mechanism to deal with this trade-off relationship. We propose an ordering enforced writeback journaling mode and selective journaling mechanism. The Ordering enforced writeback journaling mode achieves low I/O latency and the selective journaling mechanism achieves high reliability. The experimental result shows that the performance of RFJ is almost 5x faster than the journal mode of Ext3 file system but it still supports the same reliability with the journal mode.