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A fire in the main control room of a thermal power plant is a significant threat to the entire power plant by incapacitating the concept of performance design to secure the safety of the power plant. In this study, using the PyroSim and Pathfinder programs to evaluate fire and evacuation risk of the main control room, the appropriate time and fire shape for evacuating people calmly were confirmed when the available safe egress time and required safe egress time of the main control room were compared. In the case of a cable fire, the simulation results indicate the heat generation rate to be more serious than the actual experimental results showed. This is because heat generation was lower in the experiment as the polymer material constituting the cable fell to the floor during combustion and no loger burns. The fire dynamics simulator results indicate that the power plant facility is safe because even these points are not considered.

The high-throughput DNA sequencing (HTS) method is used to identify microbes in cheese and their potential functional properties. The technique can be applied to the microbiota of the cheese processing environment, raw milk, curd, whey, and starter cultures, and be used to improve the quality, safety, and other physicochemical properties of the final product. The HTS method is also utilized to study the microbiota shift of different types of cheeses during processing, as the composition and functional properties of the microbiome provide unique characteristics to different cheeses. Although there are several reviews that focused on microbiota of various types of cheeses, this review focuses on evaluating the microbiota shift of different types of cheese production and highlights key bacteria in each step of the processing as well as microbiota of various types of cheeses. KEY POINTS: • High-throughput sequencing can be applied to identify microbiota in cheese. • Microbiota in cheese is changed during making process and aging. • Starter culture plays an important role to establish microbiota in cheese.

Diarrhea is a major public health concern associated with pathogenic Escherichia coli infections. Foodborne pathogenic E. coli can lead to large diarrheal outbreaks and hence, there is a need to estimate the frequency of pathogenic E. coli load in the various types of meat available in markets. In the present study, we classified and characterized diarrheagenic E. coli isolates collected from 399 raw meat samples from retail sources in Korea. Shiga toxin-producing E. coli (STEC) were detected in 11 (9.7%) samples, including nine strains (8.0%) in beef and two strains (1.8%) in chicken. The frequency of the detected virulence markers were as follows: astA, 28.3%; escV,18.6%; eaeA,17.7%; ent, 7.0%; EHEC-hly, 4.4%; stx1, 3.5%; and stx2, 3.5%. We did not observe any typical EPEC, EIEC, or ETEC virulence determinants in any of the samples. The STEC serotype O26 was detected in one sample, but no other serogroups (O91, O103, O128, O157, O145, O111, and O121) were found. Further research is needed to better understand the virulence mechanism of STEC serotypes, their ecology, and prevalence in animals, food, and the environment. These results will help improve risk assessment and predict the sources of food poisoning outbreaks.

During refrigerated storage, aged beef is liable to undergo alterations in its physicochemical properties. This study aimed to evaluate changes in the community of microorganisms, volatile compounds, and amino acids in aged beef under cold storage conditions. In addition, volatile basic nitrogen (VBN) values were measured to determine the putrefaction degree. Raw-, dry-, and wet-aged beef were stored at 4°C for 21 days. The initial pH of beef under the three conditions ranged from 5.52 to 5.60 and decreased from 5.04 to 5.33 over time. After 21 days, VBN values ranged 20.53-22.59 mg/100 g, which exceeded the standard of spoilage (20 mg/100 g) in the Korean Food Code. As time passed, numbers of psychrophilic and lactic acid bacteria increased in the raw beef. In contrast, number of mesophilic, psychrophilic, and lactic acid bacteria decreased in dry- and wet-aged beef. Among the volatile substances and amino acids, 2,3-butanedione, 2-butanone, tyrosine, and arginine contributed the most to the high VBN levels in aged beef, where the VBN was 21 mg/100 g at 21 days, which was beyond the acceptable limit. In conclusion, clear alterations were observed in the physicochemical properties and microorganism communities in cold-stored aged beef, providing basic information that could benefit the beef industry and boost consumer acceptance.

We determined the toxin gene profile, toxin production, antibiotic resistance coagulase serotype, and genetic diversity of 42 coagulase‐positive Staphylococcus aureus (CPS) isolates collected from 1,464 cream‐filled bakery products in Korea. Among the CPS isolates, 37 (88.1%) produced enterotoxin genes in combination with another toxin; 26 (61.9%) of the strains were positive for sea, 1 (2.4%) for sea‐seb, and 4 (9.5%) for sea‐sec. Among the strains showing antibiotic resistance, 28 (66.7%) showed resistance to only one antibiotic, whereas nine (21.4%) showed resistance to multiple antibiotics: 4 (9.5%) strains were both mecA‐positive and oxacillin‐resistant. Most strains are resistant to at least one antibiotic—benzyl penicillin. The CPS isolates were classified into eight coagulase serotypes. This information will be valuable for assessing the capability risks of CPS food poisoning, contributing a better known of the epidemiology result associated with CPS contamination in bakery products.

Compressed sensing (CS) is a technique which reconstructs an approximated full image using reduced samples. With the CS technique, the measurement time is reduced and high-resolution reconstructed data are obtained. On the other hand, the computational time is increased because the CS algorithm requires slightly more time than conventional reconstruction algorithms. Therefore, reducing the computational time is a critical issue. In this paper, an improved CS algorithm is proposed. The proposed algorithm is based on a greedy algorithm which solves CS problems using an iteration method. By reducing the number of iterations, the computational time of the proposed algorithm is reduced. The proposed CS algorithm is applied to a simple discrete Fourier transform problem and to millimeter-wave ground-based synthetic aperture radar imaging for verification.

Clostridium difficile is an anaerobic, toxin-producing pathogen that causes human infection possibly through the consumption of meat. Clostridium difficile was isolated from 45 of 415 (10.8%) various raw meat samples collected in nationwide markets in Korea between 2013 and 2014. Among the 45 isolated strains, the highest prevalence rate was found in September (28.6%) and detected in chicken (16.4%), pork (8.3%) and beef (6.8%). According to an antibiotic resistance test, resistance was found only for clindamycin (2.2%). The genetic similarity of ribotypes O78 and O27 and strains isolated from raw meats was determined using DiversiLab. Among the isolates studied, four different rep-PCR types were identified, genetically distinct from ribotypes O78 and O27. An ELISA reaction confirmed that the two strains have toxin A and toxin B and showed 89% genetic similarity. This study suggests that food animals could be potential routes of foodborne transmission in C. difficile-associated human infection.

본 연구는 자동화 MPN 분석 장비인 TEMPO (TEMPOBC)와 MYP 배지법을 이용한 바실러스 정량 시험 결과에 대한 상관관계와 유의성을 연구하였다. 자연적으로 오염되어 있는 B. cereus 다빈도 검출 식품을 선별하여(N = 384)두 시험법으로 정량 시험한 결과값의 차가 1 log CFU/g 미만이 95.3%였으며, B. cereus가 검출된 시료에서는 92.5%였다. 통계학적으로 TEMPO BC 시험법과 MYP 배지법은 유의적 차이가 없었다(p < 0.05). 국내 정량 규격이 있는 식품에 인위적으로 B. cereus를 접종하고 두 시험법을 비교하였다. R2값은 소스류(0.98), 조림식품류(0.98), 젓갈류(0.96)에서 유의적인 차이가 없었으나, 생식류(0.94), 청국장류(0.86), 된장류(0.71)는 시험법 간의 유의적인 차이가 있었다. 콩, 메밀 등의 곡류 제품은 TEMPO BC 결과값의 오류가 날 수 있는 재료로 명시되어 있으므로 선식류와 청국장류, 된장류는 자동화 시험법인 TEMPO BC로 사용하기 위해서는 시험법을 추가적으로 검증 할 필요성이 있다고 생각된다. 자연적으로 오염되어 있는 식품 시료와 인위적으로 접종한 시료에 대한 선형 방정식은 log(TEMPO BC) =0.8453 × log (MYP배지) + 0.1642이며 paired t-test를 이용하여 검증한 결과 유의적인 차이가 없었다. 최근 식품의 안전성에 대한 소비자의 관심이 증가하여 식품공전 및 국제 기준에 정량기준이 강화되고 있는 추세이므로 TEMPOBC의 수요증가가 예상된다. 따라서 본 연구는 이에 대비하여 식품의 안전성 평가에 사용되는 기존의 실험법과의 비교 및 타당성 연구 기초 자료로 쓰일 것이라 생각된다.

In this study, specific and rapid enrichment and growth conditions for the most important, classic non-O157 enterohemorrhagic Escherichia coli (EHEC) serogroups were assessed. Three enrichment broth types, namely, EC medium with MUG broth, BRILA broth, and mTSB broth with novobiocin, were compared to identify the optimum enrichment broth for EHEC isolation. Four kinds of selective media, namely, ENDO agar, Chromocult agar, TBX agar, and CHROMagar TM STEC medium, were compared to identify the optimum one for non-O157 EHEC isolation. The results suggested that incubation in EC medium with MUG broth at 42℃ for 20 h is optimum for the enrichment of non-O157 EHEC. TBX agar was identified to have the highest specificity among the tested media. Consequently, a combination of complementary selective media according to serotype must be considered for comprehensive isolation of specific EHEC.

A range-cell-focusing algorithm is proposed in order to improve the quality of the target image. In a synthetic aperture radar (SAR) imaging system, the range resolution depends on the frequency bandwidth and determines the ability to distinguish between targets that are very close to each other. In cases where the resolution and the SNR from the environment are not adequate, targets cannot be accurately visualized. In order to successively classify targets that are close, we are combining an enhanced-multiple-signal-classification spectrum as a weighting function to reproduce the raw data. The proposed algorithm improves classification and separation for close targets while suppressing artifacts in the final images. The targets of interest are stationary point scatterers. The results are obtained from both simulated and experimental data to demonstrate that the proposed algorithm provides better performance than a conventional SAR imaging algorithm, the range migration algorithm.

Design of an electric machine such as the axial flux permanent magnet synchronous motor (AFPMSM) requires a 3-D finite-element method (FEM) analysis. The AFPMSM with a 3-D FEM model involves too much time and effort to analyze. To deal with this problem, we apply a surrogate assisted multi-objective optimization (SAMOO) algorithm that can realize an accurate and well-distributed Pareto front set with a few number of function calls, and considers various design variables in the motor design process. The superior performance of the SAMOO is verified by comparing it with conventional multi-objective optimization algorithms in a test function. Finally, the optimal design result of the AFPMSM for the electric bicycle is obtained by using the SAMOO algorithm.

In this paper, we propose a microwave imaging technique that involves an adaptive back-projection (BP) algorithm based on a climb method. In general, the range migration algorithm (RMA) provides high computational efficiency and high accuracy for synthetic aperture radar (SAR) imaging. However, RMA involves wavenumber domain interpolation, which may adversely affect the accuracy of the target imaging. The BP algorithm, which has its origins in medical imaging techniques, has been studied to overcome this problem in SAR imaging, because it avoids interpolation associated with domain conversion, but it also has a huge computational cost. Therefore, this paper proposes adaptive processing based on a climb method to find the target indicator as real target responses. The real target responses are predetermined and the raw data are reproduced to reduce the computational cost and to improve the image quality. Finally, the superiority of proposed algorithm is demonstrated using both the simulated and experimental data.

A novel method for buried target extraction, the active phase compensation technique is proposed. The range migration algorithm (RMA) is the conventional method for synthetic aperture radar (SAR) image reconstruction, but if targets exist in different media, identification of the target can be difficult because of losses and the significant reflection from the boundary face. In this regard, the matrix pencil method is utilised to actively find the boundary point and buried target responses. Then, the reflection effect can be eliminated, and range cells corresponding to estimated target responses can be compensated by applying newly created compensation functions. It improves the detection accuracy of buried targets. Finally, experimental results demonstrated that the proposed technique performs better than the classic RMA.

Vibrio is a genus of Gram-negative, curved, halophilic, and non-spore-forming bacteria. Some of the Vibrio species, such as V. cholerae and V. parahaemolyticus, often contaminate seafood products and occasionally cause human diseases when the seafood products are ingested. A total of 24 Vibrio strains were isolated from shrimp samples on Thiosulphate citrate bile salt sucrose (TCBS) media in this study. All of the 24 isolates were confirmed to belong to the genus Vibrio by using 16S rRNA gene sequence analyses. Vitek 2 system and species-specific poly- merase chain reaction (PCR) methods were used to further identify a total of 29 Vibrio strains at the species level, including the 24 shrimp Vibrio isolates and five Vibrio reference strains. The specificities of the two methods to iden- tify Vibrio strains at the species level were compared in this study. The species-specific PCR method was designed to detect five different Vibrio species, such as Vibrio cholerae, Vibrio parahaemolyticus, Vibrio vulnificus, Vibrio algi- nolyticus, and Vibrio mimicus. From the 24 Vibrio shrimp isolates, the Vitek 2 system method could identify 15 (62.5%) strains as Vibrio species and 7 (29.2%) strains as non-Vibrio species, but could not identify the rest 2 (8.3%) strains. But species-specific PCR method could identify 16 (66.7%) strains as Vibrio species and could not identify the rest 8 (33.3%) strains. Among the 24 Vibrio shrimp strains, these two methods could unanimously identify 7 (7/24, 29.2%) strains (2 V. parahaemolyticus, 4 V. alginolyticus, and 1 V. mimicus). Considering that such different identifi- cation results were obtained using the two different methods in this study, identification method for Vibrio species must be carefully chosen.

Da-Yeon Lee, Joo-Young Lee, Hae-Jin Wang, Dong-Bin Shin, and Yong-Sun Cho*Food Analysis Center, Korea Food Research InstituteAbstract Pathogenic Escherichia coli is recognized as an important cause of diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome worldwide. This study was conducted to investigate the prevalence E. coli contamination in the Koreantraditional food bibimbap. E. coli were isolated from 84 of 1142 (7.3%) bibimbap investigated from 2005 to 2011.Antibiotic resistance profiling demonstrated that 6 of the 84 isolates (7.2%) showed multiple drug resistance. Fifteenvirulence genes specific for pathogenic E. coli such as Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli(EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), and enteroaggregative E. coli (EAEC) wereexamined by multiplex PCR for mixed bacterial cultures derived from bibimbap samples. The EPEC virulence gene (ent)was detected in 5 strains (5.9%), while ETEC, EAEC, and EIEC were not detected. STEC serotypes O103 (1.2%), O91(1.2%), and O128 (6.0%) were found, but other serogroups such as O26, O157, O145, O111 and O121 were not detecded.Automated Repetitive-Sequence-Based PCR analysis showed different patterns.Keywords: bibimbap, Escherichia coli, antibiotic resistance, virulence gene, genetic diversity

Clostridium difficile is an anaerobic, toxin-producing pathogen that causes human infection possibly through the consumption of meat. Clostridium difficile was isolated from 45 of 415 (10.8%) various raw meat samples collected in nationwide markets in Korea between 2013 and 2014. Among the 45 isolated strains, the highest prevalence rate was found in September (28.6%) and detected in chicken (16.4%), pork (8.3%) and beef (6.8%). According to an antibiotic resistance test, resistance was found only for clindamycin (2.2%). The genetic similarity of ribotypes O78 and O27 and strains isolated from raw meats was determined using DiversiLab. Among the isolates studied, four different rep-PCR types were identified, genetically distinct from ribotypes O78 and O27. An ELISA reaction confirmed that the two strains have toxin A and toxin B and showed 89% genetic similarity. This study suggests that food animals could be potential routes of foodborne transmission in C. difficile-associated human infection.

In this paper, a numerical method for analyzing coupling between high-altitude electromagnetic pulse (HEMP) as external field and a shielded twisted pair (STP) cable is proposed, which is based on an expanded chain matrix. Load responses of electromagnetic (EM) field excitation in uniform transmission line (TL) are solved by Baum-Liu-Tesche (BLT) equations in frequency domain, however, it is difficult to apply BLT equations to solve load responses of STP cable because the iteratively changing configuration of each twisted pairs are involved in cable. To avoid this problem and decrease memory and CPU time, we proposed the expanded chain matrix modeling method that is calculated using ABCD parameters, and applied multi-conductor transmission line (MTL) theory to consider the EMP coupling effectiveness of each twisted pairs. The results implemented by the proposed method are presented and compared with those obtained by the finitedifference time domain (FDTD) method as a kind of 3D full wave analysis.

Synovial sarcoma comprises approximately 10% of soft tissue sarcomas. Primary pulmonary synovial sarcoma is a rare tumor. It makes up only 0.5% of all primary lung malignancies. It typically presents in adolescents and young adults. The usual progress of the tumor is unknown. We report the rapid progress of a primary pulmonary sarcoma that developed in a 67-year-old woman. In this case, metastatic sarcoma was excluded by positron emission tomography-computed tomography. Synovial sarcoma was histologically confirmed by a biopsy from the lung tissue. The patient had two masses located at the upper lobe of the lung. The patient refused all medical treatment and left our hospital. Two months later, she was readmitted and diagnosed with multiple metastases in the other lung and pancreas. She expired due to syndrome of inappropriate antidiuretic hormone secretion and superior vena cava syndrome four days after admission.

In this study the automated technique TEMPO STA method, a new automated enumeration based on MPN method, was compared to the direct plate count method by testing various ready-to-eat compound food prod- ucts. Artificially inoculated food samples with Staphylococcus aureus - Bibimbap, Bibimnaengmyeon, Mulnaengmy- eon, Kimmaki, Salad, Japchae, and Sushi- were tested. Statistical analysis of the results showed above 99% in agreement between the two enumeration methods. Also, we monitored 466 various ready-to-eat compound food prod- ucts samples. The measure uncertainties of the two methods is also familiar, while TEMPO STA automated method is simpler, less time-consuming, more effective and more stable.

Staphylococcus aureus is a major human pathogen that produces a wide array of toxins, leading to various disease symptoms. The prevalence of S. aureus in rice cakes was investigated from 2006 to 2011. S. aureus was isolated from 79 of 1,151 (6.9%) rice cake samples collected in Korea, and the prevalence of S. aureus contamination was found to be highest in jeolpyeon (stramed rice cake). Of the tested strains showing antibiotic resistance properties, 15 strains (19.0%) showed multiple antibiotic resistance and 3 showed both mec A positive and oxacillin resistance. In total, 67.1% of the tested strains showed 1 or more enterotoxin genes and 11.4% showed the tst gene. Most of the enterotoxigenic strains produced SEA or SEA in combination with another toxin. Total typing using automated repetitive-sequence-based PCR revealed that the 79 S. aureus isolates could be grouped into 13 distinct clusters. S. aureus showed different fingerprint patterns although some of the patterns carried the same type of SE genes and antibiotic resistance.

The fault current of the power transmission system is greater than that of the power distribution system. Therefore, the introduction of superconducting fault current limiter (SFCL) is more needed to reduce the increased fault current. The trigger-type SFCL consists of the high-temperature superconducting element (HTSC), the current limiting reactor (CLR) and the circuit breaker (CB). The trigger-type SFCL can be used to supplement the disadvantages of the resistive-type SFCL. The operation characteristics of the current ratio differential relay which is usually applied to the protection device of the power transmission system are expected to be affected under fault conditions and the applicability of the trigger-type SFCL. In this paper, we analyzed the operating characteristics, by the fault conditions, between the current ratio differential relay for line protection and the trigger-type SFCL in the power transmission system through the PSCAD/EMTDC simulation.

Staphylococcus aureus is a major human pathogen that produces a wide array of toxins, leading to a number of adverse symptoms. We examined 275 strains of Staphylococcus aureus isolated from various foods between 2006 and 2008 for antimicrobial susceptibility. At least 259 (94.2%) of the tested strains showed antibiotic resistant properties, and 106 (40.7%) of them showed multiple antibiotic resistance. Eleven of the tested strains were resistant to oxacillin and mec A-positive. Moreover, oxacillin-resistant strains were significantly more likely to be multi-drug resistant (p

In the current paper, we propose a new modeling algorithm to analyze the coupling between an incident electromagnetic field (EMF) and a twisted conducting line, which is a kind of non-uniform line. Typically, analysis of external field coupling to a uniform transmission line (TL) is implemented by the Baum-Liu-Tesche (BLT) equation so that the induced load responses can be obtained. However, it is difficult to apply this method to the analysis of a twisted conducting line. To overcome this limitation, we used a chain matrix composed of ABCD parameters. The proposed algorithm expands the dimension of the previous chain matrix to consider the EMF coupling effectiveness of each twisted pair, which is then applied to multi-conductor transmission line (MTL) theory. In addition, we included a comparative study that involves the results of each method applied in the conventional BLT equation and new proposed algorithm in the uniform two-wire TL case to verify the proposed method.

The South Korean power grid has a network structure for the flexible operation of the system. The continuously increasing power demand necessitated the increase of power facilities, which decreased the impedance in the power system. As a result, the size of the fault current in the event of a system fault increased. As this increased fault current size is threatening the breaking capacity of the circuit breaker, the main protective device, a solution to this problem is needed. The superconducting fault current limiter (SFCL) has been designed to address this problem. SFCL supports the stable operation of the circuit breaker through its excellent fault-current-limiting operation [1] , [2] , [3] , [4] , [5] . In this paper, the quench and fault current limiting characteristics of the flux-coupling-type SFCL with one three-phase transformer were compared with those of the same SFCL type but with three single-phase transformers. In the case of the three-phase transformers, both the superconducting elements of the fault and sound phases were quenched, whereas in the case of the single-phase transformer, only that of the fault phase was quenched. For the fault current limiting rate, both cases showed similar rates for the single line-to-ground fault, but for the three-wire earth fault, the fault current limiting rate of the single-phase transformer was over 90% whereas that of the three-phase transformer was about 60%. It appears that when the three-phase transformer was used, the limiting rate decreased because the fluxes by the fault current of each phase were linked in one core. When the power loads of the superconducting elements were compared by fault type, the initial (half-cycle) load was great when the single-phase transformer was applied, whereas for the three-phase transformer, its power load was slightly lower at the initial stage but became greater after the half fault cycle.

We examined antimicrobial susceptibility and serotypes of 33 L. monocytogenes isolates collected from ready-to-eat seafood and food processing environments. The isolated strains belonged to the 1/2b (73%), 4b (15%), and 1/2a (12%) serotypes; 11 of the obtained environmental swab samples belonged to the 1/2b serogroup. Antimicrobial resistance to benzyl penicillin (100%), clindamycin (100%), oxacillin (100%), ampicillin (97%), and tetracycline (18%) was detected, and 27/33 isolates (82%) showed resistance to four antibiotics and 6/33 (18%) were resistant to five. Total typing by automated repetitive sequence-based PCR revealed that the 33 isolates grouped into four distinct clusters with significantly correlated serotypes. These findings provide important information about the safety of ready-to-eat seafood and suggest that control measures should be adopted in order to mitigate the risk to humans posed by L. monocytogenes contaminated seafood.

In this study, a new concept is proposed on a combination device with functions of a commercial transformer and a superconducting fault current limiter (SFCL). This device serves as a transformer by stepping the voltage up or down in normal condition. When a transient phenomenon occurs in the power system, it serves as an SFCL to limit the fault current. The device quickly detects the line current using a current transformer (CT), and is based on the high-speed, silicon-controlled rectifier (SCR) interrupter operation. This is done by identifying the fault using an SCR switching control system. The test results showed that the fault current was limited by the impedance of the superconducting element a half cycle after a fault occurred. An SCR that initially had a normally open contact was turned on within a half cycle. However, an SCR with a normally close contact was turned off after a half cycle because the current dropped below the holding current after a half cycle. The voltage of the superconducting element was low in the step-down turn ratio condition of the transformer. This was because the secondary and tertiary windings were connected in series due to the SCR-1 turn-off condition, and the sum of voltages on each winding appeared on the superconducting element. By combining the existing power device technology and an SFCL technology, it is expected that the existing problems of an SFCL can be addressed to construct a smart power system.

In this paper, the operational characteristics due to the introduction of the superconducting fault current limiter(SFCL) with a peak current limiting function were analyzed in the power distribution system. The parallel structure of the superconducting element can operate the peak current limiting function depending on the transient amplitude of fault current. We studied the operating characteristics of the introduction of the SFCL with a peak current limiting function in the power distribution system. Furthermore, we were analyzed between the SFCL with a peak current limiting function and the protection devices in the power distribution system, through the short circuit experiments.