• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1082-1087
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• 2006

Human factors still plays a significant role in railway accidents. The accidents often resulted from multiple causes of hardware failures and human errors. So to ensure the safety of railway operations, human error should be effectively prevented and managed. Among several factors influencing human performance, task load (or task complexity) is well known as a major contributor to human error. In order to reduce the potential of human error, a systematic analysis should be undertaken to evaluate task load and to reduce it by modifying task process and/or education&training. In this paper, we proposed a systematic framework for railway industry to perform task analysis and to evaluate task load, and applied it to KTX operational tasks. According to the application study, we identified 14 generic task types of KTX operation. And also this paper shows the quantitative task load of those generic tasks which were analyzed by NASA-TLX method.

• 한국정보전자통신기술학회논문지
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• 제4권4호
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• pp.295-299
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• 2011

Blind equalization techniques have been widely used in wireless communication systems. In this paper, we propose to apply the balanced information potentials to the criterion of minimum Euclidian distance between two PDFs with constant modulus errors for adaptive blind equalizers. One of the two PDFs is constructed with constant modulus error samples and another does with Dirac delta functions. Two information potentials derived from the criterion are balanced in order to have better performance by putting a weighting factor to each information potentials. The proposed blind algorithm has shown in the MSE convergence performance that it can produce enhanced performance by over 3 dB of steady state MSE.

• ETRI Journal
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• 제41권2호
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• pp.184-196
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• 2019

Wavelet packet modulation (WPM) is a multicarrier modulation (MCM) technique that has emerged as a potential alternative to the widely used orthogonal frequency-division multiplexing (OFDM) method. Because WPM has overlapped symbols, equalization cannot rely on the use of the cyclic prefix (CP), which is used in OFDM. This study applies linear minimum mean-square error (MMSE) equalization in the time domain instead of in the frequency domain to achieve low computational complexity. With a modest equalizer filter length, the imperfection of MMSE equalization results in subcarrier attenuation and noise amplification, which are considered in the development of a bit-loading algorithm. Analytical expressions for the bit error rate (BER) performance are derived and validated using simulation results. A performance evaluation is carried out in different test scenarios as per Recommendation ITU-R M.1225. Numerical results show that WPM with equalization-aware bit loading outperforms OFDM with bit loading. Because previous comparisons between WPM and OFDM did not include bit loading, the results obtained provide additional evidence of the benefits of WPM over OFDM.

• 한국가시화정보학회지
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• 제19권3호
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• pp.22-30
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• 2021

Ventilated cavity shapes by varying angle of attack of a circular cavitator were predicted based on Logvinovich's Independence Principle in order to verify the cavity shape prediction method. The prediction results were compared with model experiments conducted in the high-speed cavitation tunnel. In the prediction of the cavity centerline, the movement of the cavity centerline due to the effect of gravity and cavitator's angle of attack were well predicted. In the prediction of the cavity contour, it was found that the cavity edge prediction error increased as the angle of attack increased. The error of the upper cavity contour was small at the positive angle of attack, and the error of the lower cavity contour was small at the negative angle of attack.

• 조명전기설비학회논문지
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• 제14권6호
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• pp.69-77
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• 2000

본 논문에서는 찬우$\mid$강하법에 의한 접지저항 및 대지첸위 분표의 측캠시 전휴보조전극의 영향에 대하여 기술하였으며, 측정시 오치를 최소화하는 기법을 제안하였다. 전위강해법은 전위와 천류의 측정에 이론적인 비1깅을 두고 있으며, 측정오차는 주로 측정시 설치하는 보조전극의 위치와 자체저항에 기인한다. 피측정 접지전극의 접지저항은 전위강하법에서 전위보조전극을 피측정 접지전극과 전류보조전극이 이루는 일직선상에 위치시킬 때 61.8[%]법칙을 적용하여 측정한다. 하지만 건물이나 포장도로, 구조물 등이 산재해 있는 도심의 경우에는 현장에서 피측정 접지전극과 전류보조전극 사이에 적결한 이격거리 확보가 불가능하거냐 전류보조전극의 접지저행값이 피측정 챔 지전극에 비하여 큰 값을 가지는 경우가 있다. 파측정 접지천극과 전류보조전극을 충분히 이격시키지 않거나 전류류보조전극의 접지저항값이 피측청 접지전극의 접지저항보다 비정상척으로 큰 경우 접지저항의 측정은 오차를 수반하게 되며, 측정된 접지저항값은 오차즐 보정해 주어야 한다. 본 연구애서 측정대상 전극은 길이 2.4[m]의 봉형 접지전극으호 하였으며, 전류보조전극의 영향을 고려할 때 피측정 접지전극과 전류보조전극의 적정한 이격거리는 피측정 접치전극 길이의 5배 이상으로 하여야 전위보조전극을 사설하기가 용이하며 측정정확도의 확보에 유리하다. 또한 전류보존전극의 접지저항값이 피측정 접지전극의 접지저항값 약 36.5배 이하에서는 거의 오차를 발생시키지 않는다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.109-112
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• 1989

Gun system operation is represented as a first-order Markov process, and an optimum linear filter is derived for closed-loop control of mean square error. Potential improvement is then estimated by contrasting the variance in performance and the auto correlation for open-loop system with that for the optimum linearly corrected process.

• Annals of Clinical Neurophysiology
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• 제8권2호
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• pp.125-134
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• 2006

Among the various physiological factors that affect nerve conduction velocity (NCV), temperature is the most important. Because the influence of temperature is the most important source of error. It is known from animal experiments that conduction is eventually completely blocked at low temperatures, the myelinated A fibers being the first affected and the thin fibers of group C the last. Many studies showed that the NCV decreases linearly with lowering temperature within the physiological range. The distal motor latency increased by $0.2msec/^{\circ}C$ drop in temperature between $25^{\circ}C$and $35^{\circ}C$ in the median, ulnar and peroneal nerves. The temperature affect the neuromuscular transmission; The miniature endplate potential (MEPP) and endplate potential (EPP) are increase with increasing temperature. In myasthenia gravis, the reduction in the decremental response is observed following cooling. The lowering temperature make increase the amplitude of sensory compound action potential; make enlarge the surface area of compound muscle action potential with very little increase in amplitude; make diminish the fibrillation potential and increase the myotonia in needle electromyography (EMG). Because of these findings mentioned above, the skin temperature should be routinely monitored and controlled during nerve conduction tests and needle EMG and should be taken into account when interpreting the findings.

• 한국압력기기공학회 논문집
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• 제19권2호
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• pp.93-101
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• 2023

In this study, a deep learning algorithm was used to diagnose electric potential signals obtained through CIPS and DCVG, used indirect inspection methods to confirm the soundness of buried pipes. The deep learning algorithm consisted of CNN(Convolutional Neural Network) model for diagnosing the electric potential signal and Grad CAM(Gradient-weighted Class Activation Mapping) for showing the flaw prediction point. The CNN model for diagnosing electric potential signals classifies input data as normal/abnormal according to the presence or absence of flaw in the buried pipe, and for abnormal data, Grad CAM generates a heat map that visualizes the flaw prediction part of the buried pipe. The CIPS/DCVG signal and piping layout obtained from the 3D finite element model were used as input data for learning the CNN. The trained CNN classified the normal/abnormal data with 93% accuracy, and the Grad-CAM predicted flaws point with an average error of 2m. As a result, it confirmed that the electric potential signal of buried pipe can be diagnosed using a CNN-based deep learning algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1942-1944
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• 2004

In this paper, we studied on the potential characteristics of human-body contacted the charging part. A charging part of electrical facilities and the earth are simulated by the e1ectrode pole and conductive rubber plates respectively. As the results of these follows, when the potential distribution of the human-body contacted the charging part is far from the electrode pole, a lot of currents flow through the human-body. Besides human-body non-contacted the charging part is affected by step voltage. Therefore, we could find out the causes of the electric shock accidents and be expected to the data for minimization of human error occurred the workspace.

• 소성∙가공
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• 제11권2호
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• pp.165-170
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• 2002

The preform design of forging processes plays a key role in improving product qualities, such as defect prevention, dimensional accuracy and mechanical strengths. In the industry, preforms are generally designed by the iterative trial-and-error approach, but it results in significant tooling cost and time. It is thus necessary to minimize lead-time and human intervention through an effective preform design method. In this paper, the equi-potential lines designed in the electric field are introduced to find the preform shape, and then the optimization process is used to choose the equi-potential lines that will keep the die wear to a minimum Because, in the forging process, the die wear is a function of various important factors, such as forming stress and strain, microstructure and mechanical properties of a Product.