• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.30-38
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• 2017

In this paper, we propose an underwater acoustic sensor fault detection method for passive sonar systems. In general, a passive sonar system displays processed results of array signals obtained from tens of the acoustic sensors as a two-dimensional image such as displays for broadband or narrowband analysis. Since detection result display in the operation software is to display the accumulated result through the array signal processing, it is difficult to determine the possibility where signal may be contaminated by the fault or failure of a single channel sensor. In this paper, accordingly, we propose a detection method based on the analysis of RMSCR (Root Mean Square Crossing-Rate), and the processing techniques for the faulty sensors are analyzed. In order to evaluate the performance of the proposed method, the precision of detecting fault sensors is measured by using signals acquired from real array being operated in several coastal areas. Besides, we compare performance of fault processing techniques. From the experiments, it is shown that the proposed method works well in underwater environments with high average RMS, and mute (set to zero) shows the best performance with regard to fault processing techniques.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.119-128
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• 2014

In this paper, a fast human detection method using adaptive UV-histogram and template matching is proposed. The proposed method improves the detection rate in the scene of complex environment. The method firstly generates U-histogram to extract human candidates and adaptively generates V-histogram for each labled U-histogram, thus it could extract humans correctly, which was impossible in the previous method. The method tries to match the human candidates with the adaptively sized omega shape template to the focal length and distance in order to improve the detection accuracy. It also detects false positives by rematching the template with accumulated foreground images and hence is robust to the occlusion. Experimental results showed that the proposed method has superior performance to the Bae's method in the complex environment with about 15% improvement in precision and 80% in recall and has 20 times faster processing time than Xia's method.

• The Journal of the Acoustical Society of Korea
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• v.15 no.2E
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• pp.14-23
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• 1996

This paper is a on the neural network to recognize the phonemes, the weight initialization to reduce learning speed, and LR parser for continuous speech recognition. The neural network spots the phonemes in continuous speech and LR parser parses the output of neural network. The whole phonemes recognized in neural network are divided into several groups which are grouped by the similarity of phonemes, and then each group consists of neural network. Each group of neural network to recognize the phonemes consisits of that recognize the phonemes of their own group and VGNN(Verify Group Neural Network) which judges whether the inputs are their own group or not. The weights of neural network are not initialized with random values but initialized from learning data to reduce learning speed. The LR parsing method applied to this paper is not a method which traces a unique path, but one which traces several possible paths because the output of neural network is not accurate. The parser processes the continuous speech frame by frame as accumulating the output of neural network through several possible paths. If this accumulated path-value drops below the threshold value, this path is deleted in possible parsing paths. This paper applies the continuous speech recognition system to the threshold value, this path is deleted in possible parsing paths. This paper applies the continuous speech recognition system to the continuous Korea digits recognition. The recognition rate of isolated digits is 97% in speaker dependent, and 75% in speaker dependent. The recognition rate of continuous digits is 74% in spaker dependent.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.61-69
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• 2010

In this paper, we present the methodology about an optimal probability distribution selection as well as survival rate estimation with the national highway database from 1999 to 2008. Probability paper methods are adopted to estimate the parameters of each hazard model. The goodness-of-fit test, such as the Anderson-Darling statistics, was performed. As a result, we found that Lognormal distributionan is an appropriate distribution of newly constructed sections as well as overlayed sections. We also ascertained that the results of survival rate for pavement life between the proposed method and observed data are similar. Such a selection methodology and measures based on reliability theory can provide useful information for maintenance plans in pavement management systems as long as additional life data on pavement sections are accumulated.

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.41-48
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• 2022

2-Chloro-N-(Cyano-2-thienyl methyl) acetamide (CCTA) is an intermediate used for synthesizing pesticides. It is stable at room temperature and pressure but can be decomposed when heat is accumulated. In this study, the decomposition characteristics were evaluated by measuring the weight change according to temperature using a Thermogravimetry analyzer(TGA), and the thermal decomposition characteristics were evaluated using Differential Scanning Calorimeter(DSC). The exothermic decomposition reaction occurred rapidly at about 91 ℃, and the activation energy determined by using Kissinger method, Kissinger-Akahira-Sunose(KAS) method, and Flynn-Wall-Ozawa(FWO) method were 162 kJ/mol, 149 kJ/mol and 139 kJ/mol, respectively. T_D24, the temperature at which the maximum heating rate is reached within 24 hours, was evaluated as 52~55 ℃ using the estimated activation energy.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1101-1109
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• 2014

In this study we followed biofilm formation and development in a granular activated carbon (GAC) filter on pilot-scale during the 12 months of operation. GAC particles and water samples were sampled from four different depths (-5, -25, -50 and -90 cm from surface of GAC bed) and attached biomass were measured with adenosine tri-phosphate (ATP) analysis and heterotrophic plate count (HPC) method. The attached biomass accumulated rapidly on the GAC particles of top layer throughout all levels in the filter during the 160 days (BV 23,000) of operation and maintained a steady-state afterward. During steady-state, biomass (ATP and HPC) concentrations of top layer in the BAC filer were $2.1{\mu}g{\cdot}ATP/g{\cdot}GAC$ and $3.3{\times}10^8cells/g{\cdot}GAC$, and 85%, 83% and 99% of the influent total biodegradable dissolved organic carbon ($BDOC_{total}$), $BDOC_{slow}$ and $BDOC_{rapid}$ were removed, respectively. During steady-state process, biomass (ATP and HPC) concentrations of middle layer (-50 cm) and bottom layer (-90 cm) in the BAC filter were increased consistently. Biofilm development (growth rate) proceed highest rate in the top layer of filter (${\mu}_{ATP}=0.73day^{-1}$; ${\mu}_{HPC}=1,74day^{-1}$) and 78%~87% slower in the bottom layer (${\mu}_{ATP}=0.14day^{-1}$; ${\mu}_{HPC}=0.34day^{-1}$). This study shows that the combination of different analytical methods allows detailed quantification of the microbiological activity in drinking water biofilter.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.57-62
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• 2015

The test of comparing liquid flow calibration system (approved by KOLAS) for accuracy and structure change test was performed in the test bed in order to evaluate the typical characteristics of the electromagnetic flow meters and parshall flume that are generally used in the water discharging facilities. The results of the accuracy comparing test with liquid flow calibration system showed the error of less than 2%. Pharshall plume got error up to -8.3% (low flow) from the flow rate test, but less than 4% from the accumulated flow test because of offset error at high flow rate and low flow rate. Evaluation of structual change test was tested with only parshall flume using structure and it consisted of installation angle (parshall flume and level sensor) and position change. Installation angle, water level sensor angle and position changing test for parshall flume had errors of 3.1%~-9.2%, 0.4%~-5.6% and 0.2%~1.3% respectively. Especially, the error showed the largest increase when the water level sensor measured the point of decreased flow by the structure change. Therefore, error factors (change of straight pipe length, installation of obstacle or effect of foreign substances on water level sensor) that can often occur in the field should be derived and the research for optimized installation method should be carried out continuously.

• Communications for Statistical Applications and Methods
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• v.19 no.3
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• pp.433-450
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• 2012

As a worker performs a certain operation repeatedly, he tends to become familiar with the job and complete it in a very short time. That means that the efficiency is improved due to his accumulated knowledge, experience and skill in regards to the operation. Investing time in an output is reduced by repeating any operation. This phenomenon is referred to as the learning curve effect. A learning curve is a graphical representation of the changing rate of learning. According to previous literature, learning curve effects are determined by subjective pre-assigned factors. In this study, we propose a new statistical model to clarify the learning curve effect by means of a basic cumulative distribution function. This work mainly focuses on the statistical modeling of binary data. We employ the Newton-Raphson method for the estimation and Delta method for the construction of confidence intervals. We also perform a real data analysis.

• Water for future
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• v.26 no.4
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• pp.85-95
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• 1993

Three purposes of this study are as follows: The first was the development of the extention method for the limited data observed in an urban drainage basin. The second was the analysis of the correlation between storm water runoff and NPS(non-point source) pollutant discharge, The last was the calculation of the monthly and annual specific NPS loads using the established correlation. the selected model was the SWMM monthly and annual specific NPs loads using the established correlation. The selected model was the SWMM (Storm Water Management model) developed by the US EPA(environmental Protection Agency). As a result of this study, the best correlation between storm wate runoff and NPS pollutants discharge was produced by the non-linear correlation between runoff rate(mm/hr)and specific loads rate(g/ha/sec)for all pollutants studied ; SS, COD, BOD, and TN. The best correlation through the analysis based on evently total mass was made by the linear correlation between the specific accumulated runoff(mm) and the specific accumulated loads(kg/ha) for CASE 1., and by the non-linear correlation for CASE 2. The NPS annual specific loads for the urban basin studied were 4933 kg/ha/year for SS, 775kg/ha/year for BOD, 3094kg/ha /year for COD,257kg/ha/year for TN, respectively. And the proportion of the NPS annual specific loads to the total annual specific loads were 42 % for SS, 13 % for BOD, 29% for COD, and 21 % for TN.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.31-41
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• 2016

Damage to structures, such as bridge piers, are increasing rapidly due to the debris moving along rivers at the time of flooding. Therefore, the debris fin, debris deflector and debris sweeper, which are debris reduction systems, were produced in this study and an accumulation experiment was carried out on the experimental channel according to the existence of the reduction system. The debris fin is the reduction system that creates parallel flow on debris accumulated on the bridge to pass through the bridge, which was produced using wood. In addition, the debris deflector was produced using steel pipes and it has the type of detouring the direction of debris. The debris sweeper passes the debris using the magnetic force rotation of a screw-shaped cylindrical structure by water flow and it was produced using acrylic material. The experiment was carried out by analyzing the level of accumulation according to the hardness and dropping method of the debris and comparing the accumulation rate of reduction systems, and the experiment was carried out 5 times. According to the experimental results, there was a difference in the accumulation rate according to the type of reduction system and the shape of debris, and it often depended significantly on the initial shape of debris accumulation. The direct debris reduction effect on the bridge was higher in the order of the debris deflector, debris sweeper and debris fin, but in case of the debris deflector, damage, such as stream turbulence, changes in water level and river bed, and the loss of deflector can occur due to debris accumulated directly on the debris deflector. Therefore, it is necessary to design the debris deflector considering these issues.