• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.950-955
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• 2013

This paper proposes a new low-cost current detection method to implement vector-controlled inverter of 3-phase induction motor or permanent-magnet synchronous motor using 2 shunt resistors instead of expensive Hall current sensors. The proposed method can detect perfect phase currents without current-immeasurable area in all operating conditions of motor. This method uses 2 shunt resistors in Hall current sensor positions conventionally used to detect phase currents. Therefore, it requires accurate analog differential amplifiers to detect voltages across shunt resistors at high electric potential to ground. We show the good solutions which are implemented by voltage-divider resistors networks and the instrumentation amplifiers using several Op Amps at cheap price. Computer simulations and experiments were performed to confirm the effectiveness of proposed method. These results show that proposed method can perfectly detect phase currents without current-immeasurable area in all operating conditions of motor.

• Journal of Environmental Health Sciences
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• v.31 no.1
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• pp.23-30
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• 2005

Staphylococcus aureus is one of the important pathogenic agents, which are related to the hygienic condition. This study performed for the detection of Staphylococcus aureus and screening staphylococcal enterotoxin a, b, c genes in strains isolated from the environment for production of non-pasteurized strawberry juice. A total of 44 samples were collected from utensils, machinery, employees, raw materials, and strawberry juices in 3 strawberry juice shops in Jinju, western Gyeongnam. The isolation rate of Staphylococcus aureus was 26%. Specially Staphylococcus aureus was frequently isolated from employee's hands, strawberry and strawberry juices. The sea, seb, and sec genes were also investigated by polymerase chain reaction (PCR). One hundred and 55% of each isolate had found sea gene and seb gene, respectively. However, sec gene was not detected anywhere. To prevent food-borne disease associated with juice, the accomplishment of HACCP to be more efficient and systematic is necessary.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1052-1059
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• 2006

For monitoring the fecal pollution at Nak-Dong River, one of the eutrophicated rivers, the differences between total coliforms (TC) and fecal coliforms (FC) using both of membrane filtration (MF)/MPN method, and also fecal streptococcus (FS) by MF-method was investigated. To evaluate the correlation between TC, FC, and FS statistical analyses were performed by using Minitab. And a part of the presumptive TC/FC and background colonies was purified and identified using API 20E kit (Biomeriux). As results, most (89%) of presumptive FC by MF was identified as Escherichia coli while only 14% (MPN) and 11% (MF) of TC were identified as E. coli. Furthermore, FC by MF was correlated significantly with other fecal indicators (TC/FS by MF and FC by MPN), while TC by MPN was not correlated with any other indicators. Thus, the detection of FC by MF-method may be the most reasonable for monitoring the fecal pollution.

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.948-952
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• 2003

New approach for the determination of Ag(I) ion was performed by using a carbon paste electrode (CPE) containing N,N'-Diphenyl oxamide (DPO) with anodic stripping voltammetry. The CMEs have been prepared by making carbon paste mixtures containing an appropriate amount of DPO salt coated onto graphite particles to analyze trace metal ions via complexation followed by stripping voltammetry. Various experimental parameters affecting the response, such as pH, deposition time, temperature, and electrode composition, were carefully optimized. Using differential pulse anodic stripping voltammetry, the logarithmic linear response range for the Ag(I) ion was 1.0 × $10^{-7}$ - 5.0 × $10^{-9}$ M at the deposition time of 10 min, with the detection limit was 7.0 × $10^{-10}$ M. The detection limit adopted from anodic stripping differential pulse voltammetry was 7.0 × $10^{-10}$ M for silver and the relative standard deviation was ± 3.2% at a 5.0 × $10^{-8}$ M of Ag(I) ion (n = 7). The proposed electrode shows a very good selectivity for Ag(I) in a standard solution containing several metals at optimized conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.929-935
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• 2009

As modem industrialized society progresses, the demand for electric power is increasing rapidly. The electric power system is getting amazingly bigger and complicated, which can easily induce serious troubles from the potential of large fault problems and/or system failure. The monitoring and diagnosis of the electric machine for the fault detection and protection has been important part in the electric power system. Most faults in the generator appear in the winding. This paper presents the air-gap magnetic flux characteristic of a small-scale 2-pole synchronous generator according to the faults in the field winding to protect the generator from the fault. The magnetic flux patterns in air-gap of a generator under various fault conditions as well as a normal state are simulated by using finite element method. These results are successfully applied to the detection and diagnosis of the short-circuit condition in rotor windings of a high capacitor generator.

• Journal of Food Hygiene and Safety
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• v.31 no.1
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• pp.28-35
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• 2016

Species identification of animal tissues in meat products is an important issue to protect the consumer from illegal and/or undesirable adulteration; for economic, religious and health reasons. In this reason, accurate analytical methods are needed for the labeling of meat products with requiring simple and fast procedure. Recently, applications of PCR in food analysis have been increased because of their simplicity, specificity and sensitivity. Therefore, in this study, a multiplex PCR assay was developed for the simultaneous identification of eight species of cow, pig, chicken, duck, goat, sheep, horse and turkey from raw meats. The primers were designed in different regions of mitochondrial 16S RNA after alignment of the available sequences in the GenBank database. Two multiplex primer sets were designed as Set 1 (cow, pig, chicken, duck) and Set 2 (goat, sheep, horse, turkey), respectively. Total 274 samples from cow (n = 55), pig (n = 30), chicken (n=30), and duck (n = 30), goat (n = 40), sheep (n = 33), horse (n = 41), and turkey (n = 15) were tested. The primers generated specific fragments of 94, 192, 279, 477 bp (pig, chicken, cow, duck), 670, 271, 152, 469 bp (goat, sheep, horse, turkey) lengths for eight species, respectively. The animal species specificity was 100% in all eight samples in the multiplex PCR assay. The detection limit of the multiplex PCR assay showed from 100 fg to 1 pg of template DNA from extracted from raw meats. When applying multiplex PCR assays to sample from pork/beef and pork/chicken, beef/chicken tested raw mixed meats and heat-treated ($83^{\circ}C$ for 30min, $100^{\circ}C$ for 20min, and $121^{\circ}C$ for 10min) mixtures, detection limit was 0.1% level beef, pork and pork in beef and chicken in pork and 1.0% level pork in chicken. This study suggest that the developed multiplex PCR assay can be used for rapid and simultaneous species identification of cow, pig, chicken, duck, goat, sheep, horse and turkey from meats.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1629-1637
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• 2007

An immunochromatography (ICG) strip test using a nanocolloidal gold-antibody probe was developed and optimized for the rapid detection of aflatoxin B1 (AFB1). A monoclonal antibody specific to AFB1 was produced from the cloned hybridoma cell (AF78), coupled with nanocolloidal gold, and distributed on the conjugate pad of the ICG strip test. The visual detection limit of the ICG strip test was 0.5 ng/ml, and this method showed a cross-reaction to aflatoxin B2, G1, and G2. In total, 172 grain and feed samples were collected and analyzed by both the ICG strip test and HPLC. The results of the ICG strip test showed a good agreement with those obtained by HPLC. These results indicated that the ICG strip test has a potential use as a rapid and cost-effective screening tool for the determination of AFB1 in real samples and could be applied to the preliminary screening of mycotoxin in food and agricultural products, generating results within 15 min without complicated steps.

• Journal of Korean Society on Water Environment
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• v.32 no.6
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• pp.649-669
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• 2016

This study explored the analytical conditions for 21 veterinary antibiotics which have been popularly sold in South Korea in 2014 but have not yet been targeted in EPA method 1694. Most of the selected antibiotics were separated by a reverse-phase C18 column with a combination of (buffered) water and organic polar solvent, which was commonly methanol and acetonitrile in the gradient elution mode. Volatile additives such as formic acid, ammonium acetate and ammonium formate were usually added to the mobile phases to minimize asymmetrical and tailing of antibiotics' peaks and to increase their ionization in mass spectrometry. The analytical methods of aminoglycoside antibiotics were distinct from those of the other antibiotics in terms of adoption of ion-pair chromatography (IPC) and hydrophilic interaction liquid chromatography (HILIC) capable of retaining and separating extremely polar compounds due to their hydrophilicity. Trifluoroacetic acid or heptafluorobutyric acid was frequently added to the mobile phase as an ion-pair reagent for the IPC. Tandem mass spectrometry was numerously applied to the detection of antibiotics using positive electrospray ionization (ESI) and the selected reaction monitoring (SRM) mode. All reviewed analytical methods had been/were validated by evaluating recovery, limits of detection and quantification, decision limit or detection capability of the methods.

• Journal of Veterinary Clinics
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• v.35 no.3
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• pp.97-99
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• 2018

The aim of this study is to determine whether subcutaneous temperature (ST) was correlated with rectal temperature (RT) in cattle with inducing artificial fever. In order to determine the correlation between their temperatures, the experiment was performed as follow: Among nine Holstein steers, lipopolysaccharide (LPS) was intravenously administered at a dose of $0.5{\mu}g/kg$ of body weight to six Holstein steer, then, 6 ml of saline was administrated to three steers as a control group. After LPS injection, ST was recorded using subcutaneously implanted thermo-logger sensors at 10-min intervals, and RT was measured using a digital thermometer at 0, 1, 2, 3, 4, 8 and 12 h. In steers with LPS injection, RT was highest at 3 to 4 h and recovered to a pre-challenge temperature at 8-22 h. A similar fluctuation was shown in ST except for an unexpected decrease at 1 h, and a positive correlation between RT and ST was observed in LPS-challenged steers (r = 0.497, P = 0.04). This result suggests that ST could be utilized as an index for early detection of infectious diseases or physiological events.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.398-404
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• 2021

This paper proposes a method of using a magnetic position sensor to detect accurately the rotor position required to perform vector control of a permanent-magnet synchronous motor, particularly the initial rotor position at startup. In the existing vector control systems, the initial rotor position was determined using the output signals of the Hall sensors, or the control was performed in a sensorless method without using such a sensor. On the other hand, the accuracy is degraded due to the occurrence of a position detection error, and the practicality was not satisfactory. This paper attempts to detect the initial rotor position using a magnetic position sensor to solve this problem. This method is used to solve the deteriorating starting characteristics of the motor in the vector control system. In addition, to lower the price of a low-power vector control inverter, this paper proposes a method of integrating the existing sensors and reducing the price to less than half using a magnetic position sensor for speed and position detection.