• Parasites, Hosts and Diseases
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• 제61권1호
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• pp.78-83
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• 2023

The use of an effective antimalarial drug is the cornerstone of malaria control. However, the development and spread of resistant Plasmodium falciparum strains have placed the global eradication of malaria in serious jeopardy. Molecular marker analysis constitutes the hallmark of the monitoring of Plasmodium drug-resistance. This study included 96 P. falciparum PCR-positive samples from southern Somalia. The P. falciparum chloroquine resistance transporter gene had high frequencies of K76T, A220S, Q271E, N326S, and R371I point mutations. The N86Y and Y184F mutant alleles of the P. falciparum multidrug resistance 1 gene were present in 84.7 and 62.4% of the isolates, respectively. No mutation was found in the P. falciparum Kelch-13 gene. This study revealed that chloroquine resistance markers are present at high frequencies, while the parasite remains sensitive to artemisinin (ART). The continuous monitoring of ART-resistant markers and in vitro susceptibility testing are strongly recommended to track resistant strains in real time.

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1250-1258
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• 2009

Bacillus spp., as a type of plant growth-promoting rhizobacteria (PGPR), were studied with regards promoting plant growth and inducing plant systemic resistance. The results of greenhouse experiments with tobacco plants demonstrated that treatment with the Bacillus spp. significantly enhanced the plant height and fresh weight, while clearly lowering the disease severity rating of the tobacco mosaic virus (TMV) at 28 days post-inoculation (dpi). The TMV accumulation in the young non-inoculated leaves was remarkably lower for all the plants treated with the Bacillus spp. An RT-PCR analysis of the signaling regulatory genes Coil and NPR1, and defense genes PR-1a and PR-1b, in the tobacco treated with the Bacillus spp. revealed an association with enhancing the systemic resistance of tobacco to TMV. A further analysis of two expansin genes that regulate plant cell growth, NtEXP2 and NtEXP6, also verified a concomitant growth promotion in the roots and leaves of the tobacco responding to the Bacillus spp.

• Smart Structures and Systems
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• 제28권6호
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• pp.737-744
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• 2021

In this study, structural health monitoring (SHM) methods of carbon fiber reinforced plastics (CFRPs) were investigated using electrical resistance. The developed sensing technique monitored electrical resistance in accordance with the impact damage of a CFRP. The changes in electrical resistances with multiple electrode sets enabled SHM without extra sensors so that this technique can be called self-sensing. Moreover, this study proposed electrodes only at peripheral side of a structure to minimize the number of electrodes compared to those in an array which has square number of sensors as the sensing area increases. For the intensive investigation, electromechanical sensitivity in terms of electrode distance was analyzed and optimized under drop weight impact testing. Then, SHM methods with electrodes in an array and electrodes in peripheral edges were comparatively investigated. The developed methods successfully localized impact damages into 2D coordinates. Furthermore, damage severity can be shown with a damage map by calculating electrical resistance change ratio. Therefore, structural health self-sensing system using electrical resistance was successfully developed with the minimum number of electrodes.

• 대한기계학회논문집A
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• 제22권3호
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• pp.644-653
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• 1998

In resistance spot weld, the assurance of weld quality has been a long-standing problem. Since the weld nuggets if resustance spot welding form between the workpieces, visual detection of defects in usually impossible. Welding quality of resistance spot welding can be verified by non destructive and destructive inspections such as X-Ray inspection and testing of weld strength. But these tests, in addition to being time-consuming and costly, can entail risks due to sampling basis. The purpose of this study is the development of the monitoring system based on fuzzy inference, aimed at diagonosis of quality in resistance spot welding. The fuzzy inference system consists of fuzzy input variables, fuzzy membership functions and fuzzy rules. For inferring the welding quality(strength), the experimental data of the spot welding were acquired in various welding conditions with the monitoring system designed. Some fuzzy input variables-maximum, slop and difference values of electrode movement signals-were extracted from the experimental data. It was confirmed that the fuzzy inference values of strength have a .${\pm}$5% error in comparison with actual values for the selected welding conditions(9-10.5KA, 10-14 cycle, 250-300 $kg_f$). This monitoring system can be useful in improving the quality assurance and reliability of the resistance spot welding process.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.172-173
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• 2014

The study is used to verify the applicability of the sensor to monitor penetration of chloride into the concrete, like real coastal environment. After manufacturing the specimen adapt corrosion sensor for chloride penetration monitoring, chloride spray experiment was conducted. And then, It was checked the possibility of monitoring of the penetrated chloride by measuring the resistance of the corrosion sensor that was embedded in each depth of the concrete. Experimental results, it is confirmed that the corrosion resistance of the sensor was increased depending on the concentration of chloride. Therefore, it is estimated that the sensor is available for monitoring of chloride penetration.

• 비파괴검사학회지
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• 제35권6호
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• pp.414-420
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• 2015

Concrete undergoes significant phase changes from liquid to solid states as hydration progresses. These phase changes are known as the setting process. A liquid state concrete is electrically conductive because of the presence of water and ions. However, since the conductive elements in the liquid state of concrete are consumed to produce non-conductive hydration products, the electrical conductivity of hydrating concrete decreases during the setting process. Therefore, the electrical properties of hydrating concrete can be used to monitor the setting process of concrete. In this study, a parameter identification method to estimate electrical parameters such as ohmic resistance of concrete is proposed. The effectiveness of the proposed method for monitoring the setting process of concrete is experimentally validated.

• Journal of Welding and Joining
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• 제29권1호
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• pp.115-122
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• 2011

This study is to propose an in-process monitoring system for micro resistance spot welding processes using minute accelerometer. A minute accelerometer is mounted on the upper moving electrode tip holder. With its high sensitivity and frequency response characteristics, accelerometer output signal has been successfully recorded and integrated twice to reflect electrode expansion during micro spot welding processes. The analysis of electrode expansion pattern was attempted to find its correlation with spot weld quality. Major previous findings1-6) regarding spot weld quality assessment with the electrode expansion signal in large scale resistance spot welding processes were proved to be true in this in-process monitoring system.

• Parasites, Hosts and Diseases
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• 제58권1호
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• pp.99-102
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• 2020

Two-point mutations (V419L and L925I) on the voltage-sensitive sodium channel of bed bugs (Cimex lectularius) are known to confer pyrethroid resistance. To determine the status of pyrethroid resistance in bed bugs in Korea, resistance allele frequencies of bed bug strains collected from several US military installations in Korea and Mokpo, Jeollanamdo, from 2009-2019 were monitored using a quantitative sequencing. Most bed bugs were determined to have both of the point mutations except a few specimens, collected in 2009, 2012 and 2014, having only a single point mutation (L925I). No susceptible allele was observed in any of the bed bugs examined, suggesting that pyrethroid resistance in bed bug populations in Korea has reached a serious level. Large scale monitoring is required to increase our knowledge on the distribution and prevalence of pyrethroid resistance in bed bug populations in Korea. Based on present study, it is urgent to restrict the use of pyrethroids and to introduce effective alternative insecticides. A nation-wide monitoring program to determine the pyrethroid resistance level in bed bugs and to select alternative insecticides should be implemented.

• 대한기계학회논문집
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• 제17권2호
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• pp.393-406
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• 1993

In resistance spot welding process, size of molten nuggest have been utilized to assess the integrity of the weld quality. However real-time monitoring of the nugget size is an extremely difficult problem. This paper describes the design of an artificial neural networks(ANN) estimator to predict the nugget size for on-line use of weld quality monitoring. The main task of the ANN estimator is to realize the mapping characteristics from the sampled dynamic resistance signal to the actual negget size through training. The structure of the ANN estimator including the number of hidden layers and nodes in a layer is determined by an estimation error analysis. A series of welding experiments are performed to assess the performance of the ANN estimator. The results are quite promissing in that real-time estimation of the invisible nugget size can be achieved by analyzing the dynamic resistance signal without any conventional destructive testing of welds.

• 대한토목학회논문집
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• 제32권2C호
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• pp.37-47
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• 2012

본 연구에서는 필댐을 위한 모니터링 기술에 적용할 수 있는 물리량으로 간극수압, 온도와 전기저항을 선정하였고, 이를 원심모형시험 상에서 계측할 수 있는 시스템을 구축하였다. 또한, 코아형 필댐 모형 단면을 설계하고, 코아죤에 취약부가 없는 정상적인 경우, 코아죤 하부에 부분적인 취약부가 발생한 경우, 코아죤 하부에 취약부가 커져서 상하류 사력죤이 연결되는 경우를 포함하여, 총 세 가지 모형을 제작하고, 원심모형시험을 수행하였다. 원심력장이 작용하는 조건에서, 담수시에 나타나는 침투 흐름의 변화에 따라 간극수압, 온도 및 전기저항의 변화를 모니터링하였다. 원심모형시험을 통하여, 간극수압, 온도 및 전기저항의 변화가 취약부 존재에 따라 다르게 나타나는 것을 확인할 수 있었고, 간극수압, 온도와 전기 저항이 필댐의 내부 취약부를 탐지하기 위한 모니터링 기술 개발에 적용될 수 있음을 확인하였다.