This study deals with replacement analysis of deteriorated equipment for improving productivity of production system. Frequent breakdown of the deteriorated equipment causes a situation that reduces productivity such as low product quality, process delay, and repair cost. However, the replacement of new equipment will be required a high initial investment cost, so it is important to analysis the economic feasibility. Therefore, we analyze the effect of the production system due to the aging effect of the equipment and the feasibility of equipment replacement based on the economic analysis. The process flow, working time, logistics movement, etc. are analyzed in order to build the simulation modeling for a ship and land switchboard production system. Using numerical examples, the economic feasibility analysis of equipment replacement through replacement of existing deteriorated equipment and additional arrangement of new facilities is performed.

Globally, colon cancer is increased gradually and known as one of the major causes of cancer death. Stevia, a substitute of sugar, is known to have many components including alpha-tocopherol and anthocyanin etc, as antioxidants. This study's purpose is to investigate whether stevia plant extract can have a protective effect against colon carcinogenesis induced by azoxymethane (AOM) and dextran sodium sulfate (DSS) in mice. Total 30 male ICR mice were divided into 2 groups; AOM/DSS treatment (control group), AOM/DSS + stevia extract (0.5%, in drinking water). After acclimation for 1 week, five weeks old mice received three intraperitoneal AOM (10 mg/kg b.w.) injections weekly for 3 weeks (0–2nd weeks of the experiment) and 2% DSS as drinking water for the next one week. AIN-76A purified rodent diet and 0.5% stevia extract water were supplied to the animals for 6 weeks. The colons of mice were collected and the number of aberrant crypt foci (ACF) and aberrant crypts (ACs) in colonic mucosa were counted after staining with methylene blue. Malondialdehyde (MDA) concentration in feces were determined. The numbers of ACF and ACs were significantly (p<0.01) decreased in stevia-treated group compared with the control group. The MDA concentration in feces was also significantly (p<0.01) decreased in stevia-treated group compared with the control group. In histopathology of colonic epithelium, hyperplasia of colonic epithelium was less observed in steviatreated group. These results indicate that stevia has a protective effect against colon carcinogenesis induced by AOM/DSS in mice and further study needs to illustrate the protective mechanisms.

Avian pathogenic Escherichia coli (APEC) is an agent associated with colibacillosis and an important primary pathogen with responsible for significant economic losses in chickens. This study investigated the molecular characteristics including virulence and antimicrobial resistance of serotype O78 APEC isolates, the predominant serotype, in Korea. Among 16 O78 APEC isolates, 13 isolates carried the genes conferring resistance to ß-lactam (blaTEM), aminoglycoside [aac(3)-II], plasmid-mediated quinolone (qnrA), tetracycline (tetA and tetB), sulfonamide (sul1 and sul2), or chloramphenicol (catA1). Three isolates showed resistance to gentamicin and carried aminoglycoside-modifying enzyme gene, aac(3)-II, simultaneously. Ten O78 APEC isolates showed resistance to nalidixic acid, but only qnrA gene among plasmid-mediated quinolone resistance genes was detected in one isolate. The tetA and tetB genes were also detected in nine and two isolates, respectively. In distribution of phylogenetic groups, four O78 APEC isolates only belonged to group D. But all isolates carried three to five essential virulence genes regardless of phylogenetic groups. Virulence factors and antimicrobial resistance of the most predominant serotype, O78, in chickens tested in this study can be significant role in persistence of APEC in Korea.

뽕나무깍지벌레는 복숭아, 매실, 뽕나무 등 31종의 기주식물을 가해하는 기주범위가 광범위한 난방제 해충으로 알려져 있다. 2017년도에 뽕나무깍지벌레는 5월 상순부터 부화를 시작하여 암컷성충 1마리가 75.5개(47~159개)의 알을 낳으며 모든 알이 부화하는데 약 19일이 소요되었고, 부화율은 약 87%였다. 반면에 2018년도에는 4월 하순부터 부화를 시작하여 암컷성충 1마리가 49.4개(12~71개)의 알을 낳으며 모든 알이 부화하는데 13일이 소요되었으며, 부화율은 약 72%를 보였다. 부화한 약충들은 이동 후 5월 중순부터 고착약충으로 되고, 6월 중순부터 2세대 성충이 활동하기 시작하였다. 부화약충기에 약제를 살포하여 살충효과를 조사한 결과, 살충률이 100%인 반면에, 고착약충기 에는 살충율은 2.7%로 살충효과가 낮은 것을 확인하였다.

In this study, the internal structure of a Heumgyeonggak-nu (欽敬閣漏) was designed, and the power transmission mechanism was analyzed. Heumgyeonggak-nu is an automated water clock from the Joseon Dynasty that was installed within Heumgyeonggak (欽敬閣), and it was manufactured in the 20th year of the reign of King Sejong (1438). As descriptions of Heumgyeonggak-nu in ancient literature have mostly focused on its external shape, the study of its internal mechanism has been difficult. A detailed analysis of the literature record on Heumgyeonggak-nu (e.g., The Annals of the Joseon Dynasty) indicates that Heumgyeonggaknu had a three-stage water clock, included a waterfall or tilting vessel (欹器) using the overflowed water, and displayed the time using a ball. In this study, the Cheonhyeong apparatus, water wheel, scoop, and various mechanism wheels were designed so that 16 fixed-type scoops could operate at a constant speed for the water wheel with a diameter of 100 cm. As the scoop can contain 1.25 l of water and the water wheel rotates 61 times a day, a total of 1,220 l of water is required. Also, the power gear wheel was designed as a 366-tooth gear, which supported the operation of the time signal gear wheel. To implement the movement of stars on the celestial sphere, the rotation ratio of the celestial gear wheel to the diurnal motion gear ring was set to 366:365. In addition, to operate the sun movement apparatus on the ecliptic, a gear device was installed on the South Pole axis. It is expected that the results of this study can be used for the manufacture and restoration of the operation model of Heumgyeonggak-nu.

The genus Rubus belongs to the Rosaceae family and is comprised of 600-800 species distributed worldwide. Understanding the genetic relationships and genetic structure in Rubus species is important for enabling efficient management, conservation, characterization and utilization of the species. However, as a minor crop, genetic research foundation was limited to explore genetic diversity and relationships in Rubus species. The present study shows the results of application SSR markers that were developed from SSR-enriched libraries of the one Rubus species (Rubus coreanus Mique.) in our previous study. We used 34 polymorphic microsatellite markers to analysis of genetic diversity within the Rubus species, including redraspberry, blackraspberry, blackberry and mountainberry. All the 34 SSR primers pairs produced 483 polymorphic and reproducible amplification fragments. The largest number of alleles per primer pair was confirmed at GB-RC-167, GB-RC-100, GB-RC-076 and GB-RC-245, which contained 26, 25, 23 and 21, respectively. An average value of polymorphic information contents (PIC) were 0.74 with a range of 0.36 to 0.92. Population structure and phylogenetic analyses showed that all Rubus species formed three largely distinct clusters, which were confirmed by principal coordinate analysis (PCoA). We obtained the results that the developed SSR markers showed a substantial degree of genetic diversity in the various Rubus species distributed in Korea.