• Journal of Sensor Science and Technology
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• v.11 no.2
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• pp.111-117
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• 2002

In this paper, we proposed calibration techniques to improve measurement accuracy in the characteristic analysis system for semiconductor devices. Systematic errors can be reduced using proposed calibration techniques. Also, error current reduction procedures including leakage current and offset current are proposed to measure low-level current in pA level. Calibration parameters are calculated and stored by microprocessor using least-square fitting with measured sample data. During measurement time microprocessor corrects measured data using stored calibration parameters. Experimental results show that current measurement error above nA level is less than 0.02%. And they also show that current measurement in pA level can be performed with about 0.2% accuracy.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.77-87
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• 1997

The earthquake data(M$\geq$4.0) for post-1900 in the Korean Peninsula show temporal variation with active and quiet periods. The pattern is quite similar to northeastern China and Inner Zone of Southwest Japan. Yeongweol earthquake occurred in the seismic gap region of the Korean Peninsula. This is the first medium-size earthquake in inland region of the southern peninsula since 1978. The intensity based on the felt area estimation of about 400 places shows MMI III-Ⅷ in inland region. IIon Cheju Island and Ion Ulreung Island. The isoseismal of MMI Ⅶ shows an elongated circle in the direction of NE-SW and covers some parts of Jungdong-myon, Yeongweol-kun, Sindong-eup and Nam-myun, Jeongseon-kun. There occurred quite strong shaking, numerous cracks on the walls of buildings, falling and movement of slate and tiles on the roofs, falling of tiles from the wall and falling of materials from desks, rook falling from mountain and collapse of gravel lauers on the river side. The least square fitting of the intensity data of the Yeongweol earthquake by a popular intensity attenuation relation yields the following : I=Io＋1.82249 - 0.65295*InR - 0.00707*R

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.16-23
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• 2018

In the paper, a robot control technique by employing Biomimetics is described. Rhythmic movements of the diving beetle's leg were analyzed and the formulated equations on the motion were drawn by applying Fourier least mean square fitting method. Simple control parameters were defined by comparing the observed locomotion through a motion capture system and reproduced motions according to changes in the values in the equation. Subsequently, the correlation of each parameter was discovered and expressed in a parameter space. Apparently, it was confirmed that various bio-mimicking motions can simply be generated for controlling the robot. Additionally, robot designing based on adopting structural advantages which the living organism possess have been briefly introduced. The proposed bio-mimicking motion generating technique was observed to be applicable to robot system developments under various environmental conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.3
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• pp.296-304
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• 2001

A new method of measuring the thermal diffusivity of solid material at room temperature using photothermal displacement is proposed. The influence of the parameters, such as radius and modulation frequency of the pump beam and the sample thickness, was studied. From the minimum position of phase of measured deflection with respect to the pump beam, the thermal diffusivity of the materials can be obtained. The position where phase has the minimum value is determined using multiparameter least-square regression fitting. The experimental values for different samples obtained by applying the new method are in good agreement with the literature values.

• International Journal of Automotive Technology
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• v.4 no.3
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• pp.125-133
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• 2003

Several models for the evaluation of Gross Heat Release from the internel combustion engine (ICE) are often used in literature. One of these is the First Law - Single Zone Model (FL-SZM), derived from the First Law of Thermodynamic. This model present a twice advantage: first it describes with accuracy the physic of the phenomenon (charge heat release during the combustion stroke and heat exchange between gas and cylinder wall); second it hat a great simplicity in the mathematical formulation. The evaluation of Heat Release with the FL-SZM is based on pressure experimental measurements inside the cylinder, and ell the assumption of several parameters as the specific heat ratio, wall temperature, polytropic exponent for the motored cycle evaluation, and many others. In this paper the influence of gases thermodynamic properties on Cross Heat Release has been esteemed. In particular the influence of an appropriate equation for k=k(T) (specific heat ratio vs. temperature) which describes the variations of gases thermodynamic properties with the mean temperature inside the cylinder has been evaluated. This equation has been calculated by new V order Logarithmic Polynomials (VoLP), fitting experimental gases properties through the least square methods.

• Industrial Engineering and Management Systems
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• v.9 no.2
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• pp.131-140
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• 2010

Biclustering is a method of finding meaningful subsets of objects and attributes simultaneously, which may not be detected by traditional clustering methods. It is popularly used for the analysis of microarray data representing the expression levels of genes by conditions. Usually, biclustering algorithms do not consider a sequential relation between attributes. For time series data, however, bicluster solutions should keep the time sequence. This paper proposes a new biclustering algorithm for time series data by modifying the plaid model. The proposed algorithm introduces a parameter controlling an interval between two selected time points. Also, the pruning step preventing an over-fitting problem is modified so as to eliminate only starting or ending points. Results from artificial data sets show that the proposed method is more suitable for the extraction of biclusters from time series data sets. Moreover, by using the proposed method, we find some interesting observations from real-world time-course microarray data sets and apartment price data sets in metropolitan areas.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.91-95
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• 1993

In this work we have studied the spin-lattice relaxation of $^{19}$F spins in benzotrifluoride in our quest for a reliable method of discriminating the contribution due to dipolar relaxation mechanism from that due to spin-rotational mechanism for nuclear spins located on methyl or substituted methyl group in organic molecules. Over the temperature range of 248-268 K the decay of normalized longitudinal magnetization was found to be well described by a two parameter equation of the form R(t) = exp(-st){$\frac{5}{6}$exp(-s$_1$)+$\frac{1}{6}$} which was derived under the assumption that interactions in the A3 spin system are modulated randomly and predominantly by internal rotational motions of -CF_3$ top, and it was shown that the separation of contribution due to dipolar interactions from that due to spin-rotation interaction could be successfully achieved by least-square fitting of observed data to this equation. The results indicate that the spin-rotational contribution is overwhelmingly larger than that of dipolar origin over the given temperature range and becomes more deminating at higher temperature.

• Korean Journal of Metals and Materials
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• v.47 no.5
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• pp.283-289
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• 2009

This paper dealt with a statistical analysis for evaluating the creep crack growth rate (CCGR) for Modified 9Cr-1Mo (ASTM Grade 91) steel. The CCGR data was obtained by the creep crack growth (CCG) tests conducted under various applied loads at $600^{\circ}C$. To obtain logically the B and q values used in the CCGR equation, three methods such as the least square fitting method (LSFM), the mean value method (MVM) and the probabilistic distribution method (PDM) were adopted and their CCGR lines were compared, respectively. In addition, a number of random variables were generated by using the Monte Carlo simulation (MCS), and the CCGR lines were predicted probabilistically. It was found that both the B and q coefficients followed a 2-parameter Weibull distribution well. In the case of the ranges of 10-90% for the probability variables, P(B, q), the CCGR lines were predicted. Fractographic study was conducted from the specimen after the CCG tests.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.4112-4112
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• 2001

The feasibility of NIR spectroscopy as a quick and nondestructive method for quality control of uniformity of coating thickness of pharmaceutical tablets was investigated. Near infrared spectra of a set of pharmaceutical tablets with varying coating thickness were measured with a diffuse reflectance fiber optic probe connected to a Broker IFS 28/N FT-NIR spectrometer. The challenging issues encountered in this study included: 1. The similarity of the formulation of the core and coating materials, 2. The lack of sufficient calibration samples and 3. The non-linear relationship between the NIR spectral intensity and coating: thickness. A peak at 7184 $cm^{-1}$ was identified that differed for the coating material and the core material when M spectra were collected at 2 $cm^{-1}$ resolution (0.4 nm at 7184 $cm^{-1}$). The study showed that the coating thickness can be analyzed by polynomial fitting of the peak area of the selected peak, while least squares calibration of the same data failed due to the lack of availability of sufficient calibration samples. Samples of coal powder and solid pieces of coal were analyzed by FT-NIR diffuse reflectance spectroscopy with the goal of predicting their ash content, percentage of volatile components, and energy content. The measurements were performed on a Broker Vector 22N spectrometer with a fiber optic probe. A partial least squares model was constructed for each of the parameters of interest for solid and powdered sample forms separately. Calibration models varied in size from 4 to 10 PLS ranks. Correlation coefficients for these models ranged from 86.6 to 95.0%, with root-mean-square errors of cross validation comparable to the corresponding reference measurement methods. The use of FT-NIR diffuse reflectance measurement techniques was found to be a significant improvement over existing measurement methodologies in terms of speed and ease of use, while maintaining the desired accuracy for all parameters and sample forms.(Figure Omitted).

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.3
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• pp.121-128
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• 2024

There are growing concerns that the recently implemented Earthquake Early Warning service is overestimating the rapidly provided earthquake magnitudes (M). As a result, the predicted damages unnecessarily activate earthquake protection systems for critical facilities and lifeline infrastructures that are far away. This study is conducted to improve the estimation accuracy of M by incorporating the observed S-wave seismograms in the near source region after removing the site effects of the seismograms in real time by filtering in the time domain. The ensemble of horizontal S-wave spectra from at least five seismograms without site effects is calculated and normalized to a hypocentric target distance (21.54 km) by using the distance attenuation model of Q(f)=348f^0.52 and a cross-over distance of 50 km. The natural logarithmic mean of the S-wave ensemble spectra is then fitted to Brune's source spectrum to obtain the best estimates for M and stress drop (SD) with the fitting weight of 1/standard deviation. The proposed methodology was tested on the 18 recent inland earthquakes in South Korea, and the condition of at least five records for the near-source region is sufficiently fulfilled at an epicentral distance of 30 km. The natural logarithmic standard deviation of the observed S-wave spectra of the ensemble was calculated to be 0.53 using records near the source for 1~10 Hz, compared to 0.42 using whole records. The result shows that the root-mean-square error of M and ln(SD) is approximately 0.17 and 0.6, respectively. This accuracy can provide a confidence interval of 0.4~2.3 of Peak Ground Acceleration values in the distant range.