• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.180-185
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• 2021

In accordance with the revision of the US-Korea missile guidelines, restrictions on the use of solid propellants for space launch vehicles have been completely lifted. The solid propellant can be used as a solid propellant rocket like the KSR-1 (Korea Sounding Rocket-1), and can also be used as a thrust augmentation booster for liquid fuel launch vehicles. It is known that solid propellants have a lower risk of explosion than liquid propellants. but if an accident such as an explosion at the Alcantara Launch Center in Brazil occurs, it can lead to a large-scale personal accident. In order to prevent such large-scale accidents, it is necessary to review and reflect the minimum safety distance during use, storage and combustion test of solid propellants from the planning phase of the project. In this paper, the minimum safety distance for safe use of the solid propellant is presented by dividing it into storage facilities and combustion tests.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.119-143
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• 2021

Selecting liquid methane as fuel is a prevailing trend for recent rocket engine developments around the world, triggered by its affordability, reusability, storability for deep space exploration, and prospect for in-situ resource utilization. Given years of time required for acquiring a new rocket engine, a national-level R&D program to develop a methane engine is highly desirable at the earliest opportunity in order to catch up with this worldwide trend towards reusing launch vehicles for competitiveness and mission flexibility. In light of the monumental cost associated with development, fabrication, and testing of a booster stage engine, it is strategically a prudent choice to start with a low-thrust engine and build up space application cases.

• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.167-179
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• 2023

The rifampicin-resistant strain E9-302 of Edwardsiella ictaluri strain 669 (WT) was generated by continuous passage on BHI agar plates containing increasing concentrations of rifampicin. E9-302 was attenuated significantly by 119 times to zebrafish Danio rerio compared to WT in terms of the 50% lethal dose (LD₅₀). Zebrafish vaccinated with E9-302 via intraperitoneal (IP) injection at a dose of 1 × 10³ CFU/fish had relative percentage survival (RPS) rates of 85.7% when challenged with wild-type E. ictaluri via IP 14 days post-vaccination (dpv). After 14 days of primary vaccination with E9-302 via immersion (IM) at a dose of 4 × 10⁷ CFU/ml, a booster IM vaccination with E9-302 at a dose of 2 × 10⁷ CFU/ml exhibited 65.2% RPS against challenge with wild-type E. ictaluri via IP 7 days later. These results indicated that the rifampicin-resistant attenuated strain E9-302 had potential as a live vaccine against E. ictaluri infection. A previously unreported amino acid site change at position 142 of the RNA polymerase (RNAP) β subunit encoded by the gene rpoB associated with rifampicin resistance was identified. Analysis of the whole-genome sequencing results revealed multiple missense mutations in the virulence-related genes esrB and sspH2 in E9-302 compared with WT, and a 189 bp mismatch in one gene, whose coding product was highly homologous to glycosyltransferase family 39 protein. This study preliminarily explored the molecular mechanism underlying the virulence attenuation of rifampicin-resistant strain E9-302 and provided a new target for the subsequent study of the pathogenic mechanism of E. ictaluri.

• Korean Journal of Veterinary Research
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• v.63 no.1
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• pp.5.1-5.9
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• 2023

Feline panleukopenia virus (FPV), feline calicivirus (FCV), and feline herpesvirus type-1 (FHV-1) are major infectious pathogens in cats. We evaluated the immunogenicity of a new vaccine containing inactivated FPV, two FCVs, and FHV-1 in animals. An FPV, two FCVs, and an FHV-1 isolate were continuously passaged 70, 50, 80, and 100 times in CRFK cells. FP70, FC50, FC80, and FH100 were propagated and used as vaccine antigens. Two inactivated feline virus vaccines, feline rehydragel-adjuvanted vaccine (FRAV) and feline cabopol-adjuvanted vaccine (FCAV) were prepared and inoculated into mice and guinea pigs. Humoral immune responses were measured using hemagglutination inhibition (HI) for FPV and virus-neutralizing antibody (VNA) for two FCVs and FHV-1 tests. Serial passages in CRFK cells resulted in increase in titers of FPV and two FCVs but not FHV-1 The FCAV induced higher mean HI and VNA titers than the FRAV in guinea pigs; therefore, the FCAV was selected. Cats inoculated with FCAV developed a mean HI titer of 259.9 against FPV, and VNA titers of 64, 256, and 3.2 against FCV17D03, FCV17D283, and FHV191071, respectively. Therefore, cats inoculated with the FCAV showed a considerable immune response after receiving a booster vaccination.

• Journal of Veterinary Science
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• v.24 no.5
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• pp.54.1-54.13
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• 2023

Background: Porcine reproductive and respiratory syndrome virus (PRRSV) vaccines do not provide full cross-protection, mainly due to the virus genetic variability. Despite this, vaccines based on modified-live PRRSV (PRRSV-MLV) reduce the disease impact. Objectives: To assess the efficacy of two commercial vaccines-one based on PRRSV1 (PRRSV1-MLV) and another on PRRSV2 (PRRSV2-MLV)-against a Japanese PRRSV2 field strain. Methods: Two groups of three-week-old piglets were vaccinated (G1: PRRSV1-MLV; G2: PRRSV2-MLV) and two were kept as non-vaccinated (INF and CTRL). One month later, G1, G2, and INF were challenged with a PRRSV2 field strain. Results: After the challenge, clinical signs were only observed in INF. Moreover, the highest rectal temperatures and values for the area under the curve (AUC) were observed in INF. Regarding viral detection, both AUC and the proportion of positive samples in blood were higher in INF. In G1, viremic animals never reached 100%. At necropsy (21 d after the challenge), differences for titers among groups were only found in tonsils (G1 < G2 and INF). One animal (belonging to G1) was negative in all tissues. Regarding humoral responses, G1 and G2 seroconverted after vaccination, as detected in the corresponding enzyme-linked immunosorbent assay. Specific neutralizing antibodies (NA) against PRRSV1-MLV were already detected at 14 d after vaccination in G1, showing a significant booster after the challenge, while PRRSV2-MLV NA were detected in G2 at the end of the experiment. Conclusions: Despite genetic differences, PRRSV1-MLV has been demonstrated to confer partial protection against a Japanese PRRSV2 strain, at least as good as PRRSV2-MLV.

• Pediatric Infection and Vaccine
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• v.31 no.1
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• pp.64-74
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• 2024

Purpose: Despite the recent increased number of nosocomial measles, the outbreak investigation reports are not usually standardized, thus posing unclear understanding of magnitude of its public health burden. We used the Outbreak Reports and Intervention Studies of Nosocomial Infection (ORION) statement, to compare nosocomial outbreaks and synthesize evidence to prevent hospital transmission of measles. Methods: A PubMed, Web of Science, Embase, Scopus, and Cochrane search in English, using the medical subject headings "measles," "nosocomial," "hospital," and "healthcare," was performed. We evaluated the quality of outbreak reports of nosocomial measles infection worldwide using the ORION statement findings and recommendations. Results: We reviewed 24 studies in accordance to the ORION statement. Measles transmission in healthcare settings is a significant burden on the morbidity, mortality, and economy of measles. The healthcare workers' booster vaccination guidelines should be monitored and enhanced during the post-elimination period of measles. The outcomes of infections must be explicit for outbreak reports. Conclusions: This study identified the epidemiological and clinical characteristics of nosocomial measles infections and provided strong evidence for infection control policies in hospitals.

• Journal of fish pathology
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• v.37 no.1
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• pp.71-78
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• 2024

Streptococcosis, caused by Streptococcus iniae and Streptococcus parauberis is an important bacterial disease that affects in olive flounder in Korea. In Korea, multivalent bacterial vaccines are used to prevent streptococcal diseases in aquaculture. In this study, commercial vaccines containing formalin-inactivated bacterial cells of S. iniae and S. parauberis were administered at six fish farms and one unvaccinated fish farm were designated for investigation (Wando; 4 sites and Jeju; 3 sites). Blood was collected from vaccinated and unvaccinated olive flounders, and titers of antibodies against S. iniae and S. parauberis in serum were analyzed using ELISA. After a one shot vaccination in the farms at Jeju (farm A) and Wando (farm D), the proportion of individuals with specific antibodies against S. parauberis OD values of 0.4 or higher was 60% and 53.5%, respectively. But after booster vaccination, the proportion of individuals with serum OD values of 0.4 or higher was higher substantially increased to 96.6% (farm A) and 100% (farm D). The levels of S. parauberis specific antibodies of olive flounder were increased after vaccination in three fish farms (farm D, E, and F), but not S. iniae specific antibodies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.4
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• pp.327-335
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• 2024

A simultaneous analytical method was developed to quantify antifouling agents and triazine herbicides in seawater using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The target compounds included diuron, irgarol 1051, and prometryn, which are prevalent in marine environments owing to their extensive use in antifouling coatings and agriculture. The analytical procedure involves solid-phase extraction (SPE) using HLB cartridges followed by LC-MS/MS analysis for precise quantification. The method exhibits high recovery rates for diuron (101% ± 1.25), irgarol 1051 (94.7% ± 2.08), and prometryn (93.7% ± 3.06). Seawater samples from 30 coastal sites in Korea were analyzed. Irgarol 1051 was not detected, whereas diuron was consistently detected across all sites, with concentrations from 0.68 to 11.3 ng/L, and prometryn was present at levels between 0.12 and 7.06 ng/L. The highest diuron and prometryn concentrations were recorded along the southeastern and western coasts, respectively. These findings underscore the critical need for continuous monitoring and regulations to manage these contaminants in marine ecosystems, thereby safeguarding ecological integrity and public health. This study establishes a robust analytical framework for the comprehensive assessment of multiple marine contaminants.

• Journal of Hydrogen and New Energy
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• v.35 no.4
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• pp.353-362
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• 2024

In this study, several studies were conducted on the construction of gas conversion process system for a pilot plant using a small-scale hydrogen liquefaction system. The pilot plant considered in this study includes a liquefier, a storage tank, an evaporator, a gas booster, and a gas storage tank. First, the suspected leak area of the container was checked using the sprayed method of helium gas. The small-scale hydrogen liquefaction system was designed based on the analysis results of the pre-cooling system and the liquefaction system. Additionally, the program was developed to maintain pressure within vessel for an automatic production of liquid hydrogen. The evaporator for liquid hydrogen was manufactured based on the designed analysis data, and the pollution of gas in the vessel was analyzed through a gas recovery line system.

• Journal of Microbiology and Biotechnology
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• v.34 no.7
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• pp.1419-1424
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• 2024

Secretin PilQ is an antigenically conserved outer membrane protein that is present in most meningococci and PorA is a major protein that elicits bactericidal immune response in humans following natural disease and immunization. In the present study, BALB/c mice were immunized subcutaneously with rPilQ406-770 or rPorA together with Freund's adjuvant (FA). Serum antibody responses to serogroup A and B Neisseria meningitides whole cells or purified proteins and functional activity of antibodies were determined by ELISA and serum bactericidal assay (SBA), respectively. Serum IgG responses were significantly increased in the immunized group with rPilQ406-770 or rPorA together with FA compared to control groups. IgG antibody response of mice immunized with rPilQ406-770 was significantly more than mice immunized with rPorA (OD at 450 nm was 1.6 versus 0.83). The booster injections were effective in increasing the responses of antirPilQ406-770 or anti-rPorA IgG significantly. Antisera produced against rPilQ406-770 or rPorA demonstrated strong surface reactivity to serogroup B N. meningitides in comparison with control groups. Antisera raised against rPorA or rPilQ406-770 and FA demonstrated SBA titers from 1/1024 to 1/2048 against serogroup B. The strongest bactericidal activity was detected in sera from mice immunized with rPilQ406-770 mixed with FA. These results suggest that rPilQ406-770 is a potential vaccine candidate for serogroup B N. meningitidis.