• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.205-211
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• 2009

In this study, the membrane filter method was compared to the MPN method for the analysis of total coliforms from raw water using raw test waters and controls including 6 standard strains of coliforms, and the various factors were analyzed on the detection of general and fecal origin coliforms. The range of error rate for the detection of 5 standard strains using the membrane filter and the MPN methods was 0 to 6% and 45 to 133%, respectively. The error rate of the membrane filter method was lower than that of the MPN method. The membrane filter method (m-Endo) showed 10% (11 out of 111) of difference for the detection sensitivity of coliforms isolated from raw water compared to the MPN method (BGLB). The membrane filter method was less affected by the factors including temperature, turbidity, charcoals of powder form, contamination, and reverse pressure. In conclusion, the membrane filter method is a better method for the analysis of total coliforms from raw water than the MPN method, considering the accuracy of detection and the tolerance to various experimental factors.

• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.979-985
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• 2001

A fluorometric detection technique for HDL (High Density Lipoprotein) and LDL (Low Density Lipoprotein) was developed for application in a fiber-optic immunosensor using a protein A Langmuir-Blodgget (LB) film. For the fluorescence immunoassay, antibodies specific to HDL or LDL were imobilied on the protein A LB film, and a fluorescence amplification method was developed to overcome their weak fluorescence. The deposition of protein A using the LB technique was monitored using a surface pressure-are $({\pi}-A)$ curve, and the antibody immobilization of the protein A LB film was experimentally verified. The immobilized antibody was used to separate only HDL and LDL from a sample, then the fluorescence of he separated HDL or LDL was amplified. The amount of LDL or HDL was measured using the developed fiber optic fluorescence detection system. The optical properties resulting from the reaction of HDL or LDL with o-phtaldialdehyde, detection range, response time, and stability of the immunoassay were all investigated. The respective detection ranges for HDL and LDL were sufficient to diagnose the risk of coronary heart disease. The amplification step increased the sensitivity, while selective separation using the immobilized antibody led to linearity in the sensor signal. The regeneration of the antibody-immobilized substrate could produce a stable and reproducible immunosensor.

• Smart Structures and Systems
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• v.15 no.4
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• pp.997-1018
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• 2015

Structural health monitoring along with damage detection and assessment of its severity level in non-accessible reinforced concrete members using piezoelectric materials becomes essential since engineers often face the problem of detecting hidden damage. In this study, the potential of the detection of flexural damage state in the lower part of the mid-span area of a simply supported reinforced concrete beam using piezoelectric sensors is analytically investigated. Two common severity levels of flexural damage are examined: (i) cracking of concrete that extends from the external lower fiber of concrete up to the steel reinforcement and (ii) yielding of reinforcing bars that occurs for higher levels of bending moment and after the flexural cracking. The purpose of this investigation is to apply finite element modeling using admittance based signature data to analyze its accuracy and to check the potential use of this technique to monitor structural damage in real-time. It has been indicated that damage detection capability greatly depends on the frequency selection rather than on the level of the harmonic excitation loading. This way, the excitation loading sequence can have a level low enough that the technique may be considered as applicable and effective for real structures. Further, it is concluded that the closest applied piezoelectric sensor to the flexural damage demonstrates higher overall sensitivity to structural damage in the entire frequency band for both damage states with respect to the other used sensors. However, the observed sensitivity of the other sensors becomes comparatively high in the peak values of the root mean square deviation index.

• Journal of the Korean GEO-environmental Society
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• v.19 no.1
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• pp.5-14
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• 2018

All kinds of monitoring data in construction site could have outlier created from diverse cause. In this study generation technique of synthesis value, its regression, final outlier detection and assessment are conducted to distinct outlier data included in extensive time series dataset. Synthesis value having weight factor of correlation between a number of datasets consist of many monitoring data enable to detect outlier by increasing its correlation. Standard artificial dataset in which intentional outliers are inserted has been used for assessment of synthesis value technique. These results showed increase of detection accuracy for outlier and general tendency in case of having different time series models in common. Accuracy of outlier detection increased in case of using more dataset and showing similar time series pattern.

• Convergence Security Journal
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• v.14 no.4
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• pp.3-8
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• 2014

Wireless Ad hoc Network is threatened from many types of attacks because of its open structure, dynamic topology and the absence of infrastructure. Attacks by malicious nodes inside the network destroy communication path and discard packet. The damage is quite large and detecting attacks are difficult. In this paper, we proposed attack detection technique using secure authentication infrastructure for efficient detection and prevention of internal attack nodes. Cluster structure is used in the proposed method so that each nodes act as a certificate authority and the public key is issued in cluster head through trust evaluation of nodes. Symmetric Key is shared for integrity of data between the nodes and the structure which adds authentication message to the RREQ packet is used. ns-2 simulator is used to evaluate performance of proposed method and excellent performance can be performed through the experiment.

• Convergence Security Journal
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• v.13 no.3
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• pp.33-38
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• 2013

Security between mobile nodes and efficient communication is one of the most important parts of the MANET. In particular, the wireless network is significantly higher for the attack threats because of collaborative structure for open communication media and communication. However, application of existing security mechanisms and intrusion detection system is not easy due to the characteristics of MANET. It is because collection and integration of adult data by the dynamic topology due to the mobility of nodes and many network sensors is difficult. In this study, we propose cooperative security system technique that can improve the reliability based on authentication assessing confidence about the whole nodes which joins to network and detect effectively this when intrusion occurs. Cluster head which manages the cluster performs CA role for the certificate issue and the gateway node performs role of intrusion detection system. Intrusion detection is performed by cooperating with neighboring nodes when attack is not detected in one intrusion detection node. The performance of the proposed method was confirmed through experiments comparing with the SRP technique.

• Journal of the Korean Geographical Society
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• v.47 no.6
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• pp.825-835
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• 2012

The aim of this research is to develope technique and mapping for detecting distribution of vegetation dieback areas in the subalpine zone of Mt. Baekdu. A detection technique developed the rule-based model using MODIS images. Dieback areas could be classified as 4 categories of initial dieback, middle dieback, and end dieback by pruning stages of leaves. Dieback area was $28km^2$ from year 2001 to year 2006, intial dieback was $16km^2$, middle dieback was $10km^2$, and end dieback was $2km^2$ by the each stage. Dieback area was $35km^2$ from year 2006 to year 2011. Total area was $35km^2$ from year 2001 to year 2011, areas of middle dieback and end dieback were increased. The research method for this study may help to support in application with preliminary detection of dieback areas in the mountains by the global warming.

• The Plant Pathology Journal
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• v.23 no.4
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• pp.260-265
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• 2007

Testing a large number of samples from field monitoring and routine indexing is cumbersome and the available virus detection tools were labor intensive and expensive. To circumvent these problems we established tissue blot immunoassay (TBIA) method an alternative detection tool to detect Barley mild mosaic virus (BaMMV) and Barley yellow mosaic virus (BaYMV) infection in the field and greenhouse inoculated plants for monitoring and routine indexing applications, respectively. Initially, leaf and stem were tested to determine suitable plant tissue for direct blotting on nitrocellulose membrane. The dilutions of antibodies were optimized for more efficient and economical purposes. Results showed that stem tissue was more suitable for direct blotting for it had no background that interferes in the reaction. Therefore, this technique was referred as direct stem blot immunoassay or DSBIA, in this study. Re-used diluted (1:1000) antiserum and conjugate up to 3 times with the addition of half strength amount of concentrated antibodies was more effective in detecting the virus. The virus blotted on the nitrocellulose membrane from stem tissues kept at room temperature for 3 days were still detectable. The efficiency of DSBIA and RT-PCR in detecting BaMMV and BaYMV were relatively comparable. Results further proved that DSBIA is a rapid, reliable and economical detection method suitable for monitoring BaMMV and BaYMV infection in the field and practical method in indexing large scale of barley materials for virus resistance screening.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.641-646
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• 2002

A new damage detection technique using static displacement data was developed, in order to assess the structural integrity of bridge structures. In conventional damage assessment techniques using dynamic response, the variation of natural frequencies is intrinsically insensitive to the damage of the bridge: thus, it is usually difficult to obtain them from the measured data. The proposed detection method enables the estimation of the stiffness reduction of bridges using the static displacement data that are measured periodically, without requiring a specific loading test. Devices such as a laser displacement sensor can be used to measure static displacement data due to the dead load of the bridge structure. In this study, structural damage was represented by the reduction in the elastic modulus of the element. The damage factor of the element was introduced to estimate the stiffness reduction of the bridge under consideration. Likewise, the proposed algorithm was verified using various numerical simulations and compared with other damage detection methods. The effects of noise and number of damaged elements on damage detection were also investigated. Results showed that the proposed algorithm efficiently detects damage on the bridge.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.1
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• pp.28-32
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• 2014

For a signal such as speech showing piece-wise linear shape in a very short time period, a nonuniform sampling method based on the inflection point detection (IPD) is proposed to reduce data rate. The method exploits the geometrical characteristics of signal further than the existing local maxima/minima detection (MMD) based sampling method. As results, the reconstructed signal by the interpolation of the IPD based sampled data resembles the original speech more. Computer simulation shows that the proposed IPD based method produces about 9~23 dB improvement over the existing MMD method. To show the usefulness of the IPD technique, it is applied to speech coding, and compared to the continuously variable slope delta modulation (CVSD). The nonuniformly sampled data is binary coded with one bit flag set "1". Noninflection samples are not sent, but only flag bits set 0 are sent. The method shows 0.3 ~ 9 dB SNR and 0.5 ~ 1.3 mean opinion score (MOS) improvements over the CVSD.