• The Journal of Engineering Geology
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• v.19 no.3
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• pp.261-268
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• 2009

Tunnel measurements provide crucial information on the ground stability during the excavation, visualizing the ground behavioral characteristics with quantitative dada. Generally, the frequency of the measurements is greater during the early stage of the tunnelling process and reduced with time. However, there are no quantitative criteria established for either the activities, such as the time, location and frequency of the measurement or the management guidance, especially for the site of subtle and unexpected displacement during the excavation. It is, however, still challenging to assess behavioral characteristics of subtle and unexpected displacement after stabilization. In this study, we propose a new method to assess stability and to analysis the behavioral characteristics of subtle and unexpected displacement after stabilization using statistic control charts of displacements. We also present a test result on the applicability of control chart and CUSUM control chart to measured displacements.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.3
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• pp.79-86
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• 2001

The CTD(Cumulative Trauma Disorder) as a new kind of occupational disease occurs mainly to workers on handling line under the highly-specialized industrial environments. This study took into account their exposure to Cumulative Trauma Disorders(CTD) by the utilization of EMG system, with respect to worker's muscle fatigue test according to fulfillment of iterative and simple task. The findings of this study were as follows : From the result of AEMG test analysis, worker's fatigue extent according to elapsed time of task was inclined to be increased continually. On the other hand, after its task ending, their fatigue extent was inclined to be decreased than before-circumstance of refractory brick lifting. The transference of MF(Median Frequency) and MPF(Mean Power Frequency) had highly significant difference between muscle fatigue and the elapsed time of work. Especially, their fatigue extent to erectorspinae and multifidus to lift firebrick was increased in the mean time. The transference of ZCR(Zero Crossing Rate) had considerable significant difference between muscle fatigue and the elapsed time of work. In short, as the work went of the muscle fatigue extent increased gradually. Thus, it can be concluded that the fatigue of erectorspinae and multifidus extent according to fulfillment of iterative and simple task is gradually being increased.

• Korean Journal of Cognitive Science
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• v.27 no.2
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• pp.221-245
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• 2016

Peer assessment refers to having students, rather than the instructor, make assessments of one another's work. Peer assessment is often used as a tool to train writing skills or a tool to apply or extend learning in higher education. Park(2016) recently proposed a system which utilizes peer assessment as a part of preparatory activity for college courses. Before weekly class, students studied given material on their own, wrote a one page essay on a given question based on their reading, and assessed the essays of other students. In this study, the system was implemented in undergraduate courses at S University over 2 semesters and the results were analyzed. The reliability of weekly scores given by students was not very high, but the correlation was high between the cumulative scores given by students across weeks and the scores of the end of the term paper assessed by the instructor. Based on these findings, the possibility of utilizing the results of the peer assessments as part of the final grades was discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.85-94
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• 2014

Tolerance accumulation has serious effect on the performance of an assembled body. This paper proposes the method which analyzes tolerance accumulation using Monte Carlo Simulation. This method can predict tolerance distribution of fully assembled body using the dimensional tolerance distribution of each part to be assembled. In this analysis, it is assumed that the tolerance of each part has the nominal distribution or uniform distribution. This analysis method is applied to ECV(External Control Valve), and the accumulated tolerance of the fully assembled ECV is obtained from the analysis. The results show that initial tolerance given to each part do not meet the design requirement of ECV. Hence, the tolerances of each part are modified and the additional analysis with the modified tolerances yields the results which satisfy the design requirements of ECV.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.85-90
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• 2013

In this paper, 6bit SAR ADC tolerant to ionizing radiation is presented. Radiation tolerance is achieved by using the Dummy Gate Assisted (DGA) MOSFET which was proposed to suppress the leakage current induced by ionizing radiation and its comparing sample is designed with the conventional MOSFET. The designed ADC consists of binary capacitor DAC, dynamic latch comparator, and digital logic and was fabricated using a standard 0.35um CMOS process. Irradiation was performed by Co-60 gamma ray. After the irradiation, ADC designed with the conventional MOSFET did not operate properly. On the contrary, ADC designed with the DGA MOSFET showed a little parametric degradation of which DNL was increased from 0.7LSB to 2.0LSB and INL was increased from 1.8LSB to 3.2LSB. In spite of its parametric degradation, analog to digital conversion in the ADC with DGA MOSFET was found to be possible.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.11
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• pp.15-21
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• 1999

The scalability of optical cross-connect nodes is analyzed based on the limiting factor of transmission performance. The limiting factors considered are ASE noise accumulation and gain saturation in the optical amplifiers, and crosstalk in both wavelength multiplexers/demultiplexers and optical switches. When the wavelength multiplexer/demultiplexers crosstalk is lower than 25dB, Power Penalty is below 1dB for the cascaded transmission of 10 nodes with 4 input/output ports. When 10Gbps signals are transmitted through nodes with 4 and 16 input/output Ports, performance degradation due to switch crosstalk is dominant compared to that due to ASE noise accumulation if the switch crosstalk is larger than 30dB and 45dB, respectively. For the single stage transmission of 10Gbps signal with 21dB fiber link loss, the maximum loss of optical cross-connect nodes must be under 34dB to achieve the BER of $10^{-12}$.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.470-483
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• 2003

As the amount of radioactive waste and related information to be managed are increasing, some organizations are trying or planning to computerize the management on radioactive waste. When we consider that information on safe management of radioactive waste should be used In association with national radioactive waste management project, standardization of data form and its protocol is required. Korea Institute of Nuclear Safety(KINS) will establish and operate nationwide integrated database in order to effectively manage a large amount of information on national radioactive waste. This database allows not only to trace and manage the trend of radioactive waste occurrence and in storage but also to produce reliable analysis results for the quantity accumulated. Consequently, we can provide necessary information for national radioactive waste management policy and related industry's planing. This study explains the database design which is the essential element for information management.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.166-172
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• 2012

The standard wave height measurement system is usually based on spectrum analysis for measuring wave height. The spectrum analysis is complicated because of the FFT, and the FFT is not for real time processing since it requires the saved data segments. In this paper, we carried out the performance evaluation of real-time and simpler wave height measurement system using the kalman filter and inertial sensors. The kalman filter theory is complicated, but its algorithm is simpler than the FFT and the kalman filter is used to estimate wave height by integrating acceleration data. But the accumulated error is occurred when the acceleration data is integrated. We developed the algorithm using the wind wave characteristic to decrease the accumulated error. In this paper, the performance evaluation of the wave height measurement system is carried out for various wind wave conditions. Through the experiments, we verified that it shows high measurement performance with the 3.5% margin of error in wind wave condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.637-644
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• 2006

This paper presents performance and implementation comparisons of standard and fast DCT algorithms that are commonly used for subband filter bank in MPEG audio coders. The comparison is made according to the architectural difference of the implementation hardware. Fast DCT algorithms are known to have much less computational complexity than the standard method that involves computing a vector dot product of cosine coefficient. But, due to structural irregularity, fast DCT algorithms require extra cycles to generate the addresses for operands and to realign interim data. When algorithms are implemented using DSP processors that provide special operations such as single-cycle MAC (multiply-accumulate), zero-overhead nested loop, the standard algorithm is more advantageous than the fast algorithms. Also, in case of the finite-precision processing, the error performance of the standard method is far superior to that of the fast algorithms. In this paper, truncation errors and algorithmic suitability are analyzed and implementation results are provided to support the analysis.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.230-235
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• 2009

We have conducted an experimental study to analyze characteristics of the wheel profile wear and an influence of the wheel flange wear on the vehicle's vibration characteristics. In experiment with EMU, wheel profile wear is severe at the beginning of the commercial operation. In this stage, the variations of the wheel dimension parameters and equivalent conicity is changed rapidly. Along with a mileage of the test vehicle, the wear of the wheel flange is increased and also the vibration level of the car-body is increased. The peak-peak mean value of the body vibration is estimated as good level, but the level is approached at the limit of the good level as mileage increases. Especially, the peak-peak maximum value of the body vibration shows the distinct increase of vibration level.