• Parasites, Hosts and Diseases
• /
• v.49 no.2
• /
• pp.115-123
• /
• 2011

Toxoplasma gondii Korean isolate (KI-1) tachyzoites were inoculated intraduodenally to BALB/c mice using a silicon tube, and the course of infection and immune responses of mice were studied. Whereas control mice, that were infected intraperitoneally, died within day 7 post-infection (PI), the intraduodenally infected mice survived until day 9 PI (infection with $1{\times}10^5$ tachyzoites) or day 11 PI (with $1{\times}10^6$ tachyzoites). Based on histopathologic (Giemsa stain) and PCR (B1 gene) studies, it was suggested that tachyzoites, after entering the small intestine, invaded into endothelial cells, divided there, and propagated to other organs. PCR appeared to be more sensitive than histopathology to detect infected organs and tissues. The organisms spread over multiple organs by day 6 PI. However, proliferative responses of splenocytes and mesenteric lymph node (MLN) cells in response to con A or Toxoplasma lysate antigen decreased significantly, suggesting immunosuppression. Splenic $CD4^+$ and $CD8^+$ T-Iymphocytes showed decreases in number until day 9 PI, whereas IFN-${\gamma}$ and IL-10 decreased slightly at day 6 PI and returned to normal levels by day 9 PI. No TNF-${\alpha}$ was detected throughout the experimental period. The results showed that intraduodenal infection with KI-1 tachyzoites was successful but did not elicit significant mucosal immunity in mice and allowed dissemination of T. gondii organisms to systemic organs. The immunosuppression of mice included reduced lymphoproliferative responses to splenocytes and MLN cells to mitogen and low production of cytokines, such as IFN-${\gamma}$, TNF-${\alpha}$, and IL-10, in response to T. gondii infection.

• Korean Journal of Veterinary Service
• /
• v.18 no.2
• /
• pp.113-123
• /
• 1995

The present study was conducted to investigate the prevalent characteristics of Fowl Typhoid and antibiotic susceptibility of Salmonella gallinarum isolated from 56 infective or dead chickens of 20 egg laying farms in Kyung Buk province during the period from August to December 1994. 1. Among 416, 000 chickens of 92 flocks in 20 egg laying farms, 17, 360 chickens of 31 flocks were died of Fowl Typhoid. 2. Salmonella gallinarum was isolated from 56 chickens in liver and spleen, and then blood of infective chickens was positive to Pullorum antigen. 3, In the survey of gross lesion of 56 chickens, 43 chickens(76.8%) were swelled at liver, 39(69.6%) were swelled at spleen, 12(21.4%) were changed with bronze, 3(5.4% ) were hemorrhagic in peritoneal cavity. 4. In transmission pattern, 4 farms were outbreaked the entrance of chicken house at first, but the others were outbreaked at various place. They were transmitted at right and left directions in flock. 5. 2 farms confirmed at the early stage of infection were eradicated by removing infective chickens and administrating antibiotics, but 18 farms at chronic stage were not. 6. The biochemical properties of 112 Salmonella gallinarum from chickens were generally identical to those of the referance, but H$_2$S was not productive, cellobiose was fermentive. 7 Minimum inhibitory concentration(MIC) of 20 isolates was performed by using 21 antibiotics, MICs of Amikacin(Ak), Gentamicin(Gm), Kanamycin(Km), and Tetracycline (Tc) were below 1.6 ug/ml, Ampicillin(Am), Furazolidone(Fu) and Neomycin(Nm) were below 3.1 ug/ml, Cephalothin(Ce), Cefazoline(Cf) and Chloramphenicol(Cm) were below 6.3 ug/ml, Nalidixic acid(Na), Polymyxin(Po) and Rifampicin(Rf) were below 12.5 ug/ml, Penicillin (Pm) was below 25 ug/ml, Colistin(Co) and Streptomycin(Sm) were below 50 ug/ml, Sulfamerazine(Sr) and Sulfamethazine (St) were below 200 ug/ml, Lincomycin(Lm) and Spiramycin(Sp) were below 400 ug/ml, Bacitracin(Ba) was below 800 ug/ml. 8. Among the 20 isolates, all(100%) of those were sensitive to Ak, Am, Ce, Cf, Cm, Fu, Gm, Km, Na, Nm, Po, Rf, Sr, St and Tc, but 6 isolates(30%) were resistent to Co, 20(100% ) to Ba, Lm, Pm, Sm, and Sp. The drug resistance patterns were simple which 6 strains were BaCoLmPmSmSp type, and 14 were BaLmPmSmSp type.

• Microbiology and Biotechnology Letters
• /
• v.18 no.1
• /
• pp.89-93
• /
• 1990

To improve the stability of recombinant pBR322-trip$^+$ plasmid (pLTW24) in E. coli culture, a positive selection system was devised. A DNA fragment containing pheW$^+$ gene (a structural gene for tRNA$^{phe}$ was isolated and inserted into the pBR322-trip$^+$ plasmid(pLTP24). A temperature sensitive host strain. LC901-pheS$^{-ts}$, was constructed for this plasmid by transducing pheS$^{-ts}$ allele (phenylalanyl-tRNA synthetase) to E. coli LC901 using P1kc bacteriophage. The LC901-pheS$^{-ts}$ cells were unable to grow at a restrictive temperature when they had lost the pBR322 :: pheW$^+$ (pLTP24) plasmid. The effects of pheW$^+$ gene on the plasmid stability and the expression level of trip$^+$ gene in LC901-pheS$^{-ts}$ strain were investigated. The proportion of Trip$^+$ colonies among LC901-pheS$^{-ts}$ strain carrying plasmid pLTP24 was 99%, whereas that of LC901 strain carrying plasmid pLTW24 was 7% at the end of 20 generations. After 100 generations of growth, the strain LC901-pheS$^{-ts}$ carrying plasmid pLTP24 showed little loss of plasmids. While the majority of plasmid pLTW24 in LC901 strain were lost in the same period. The activities of tryptophan synthetase (T. Sase) and anthranilate synthetase (A. Sase) in LC901 strain carrying pLTW24 were about 1.2 times and 1.8 times respectively of those in LC901-pheS$^{-ts}$ strain carrying pLTP24.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.10
• /
• pp.291-298
• /
• 2020

The power generation of a PV system changes according to the weather variables, such as solar radiation and temperature. In particular, the output characteristics of photovoltaic systems, which are sensitive to changes in solar radiation, can be produced effectively and reliably in various weather conditions through MPPT (Maximum Power Point Tracking) control. This paper proposes a fuzzy-based MPPT control method to improve the efficiency and stability of the power production from a solar system. To verify the performance of the proposed method, under the same weather environment, the efficiency and stability of the newly proposed fuzzy logic were compared and evaluated empirically with P&O (Perturb and Observe), a representative algorithm of MPPT control. Furthermore, the circuits designed to improve the reliability and reliability of the hardware were manufactured from Printed Circuit Boards (PCB) to conduct experiments. Based on the results of the experiment during a certain period, the fuzzy-based MPPT proposed in this paper improved the efficiency by more than 4.4% compared to the MPPT based on the existing P&O algorithm and decreased the fluctuation width by more than 39.7% at the maximum power point.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.12
• /
• pp.1013-1019
• /
• 2014

Solid-liquid Phase Change Material(PCM) as a thermal control hardware for the electro-optical payload of low earth orbit satellite is numerically studied which can be substituted with Thermal Buffer Mass(TBM). The electro-optical module in LEO satellite is periodically work and high heat is dissipated during the imaging period, however, the design temperature range is very tight and sensitive. In order to handle this problem TBM is added and as a result the time constant of the module temperature increases. TBM is made of Al6010 and its mass directly affects the system design. To save the mass PCM is suggested in this study. The latent heat of melting or solidification is very high and small amount of PCM can play a role instead of TBM. The result shows that only 12% of TBM mass is enough to control the module temperature using PCM.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.150.1-150.1
• /
• 2014

Showerhead is used as a main part in the semiconductor equipment. The face plate flatness should remain constant and the cleaning performance must be gained to keep the uniformity level of etching or deposition in chemical vapor deposition process. High operating temperature or long period of thermal loading could lead the showerhead to be deformed thermally. In some case, the thermal deformation appears very sensitive to showerhead performance. This paper describes the methods for robust design using computational fluid dynamics. To reveal the influence of the post distribution on flow pattern in the showerhead cavity, numerical simulation was performed for several post distributions. The flow structure appears similar to an impinging flow near a centered baffle in showerhead cavity. We took the structure as an index to estimate diffusion path. A robust design to reduce the thermal deformation of showerhead can be achieved using post number increase without ill effect on flow. To prevent the showerhead deformation by heat loading, its face plate thickness was determined additionally using numerical simulation. The face plate has thousands of impinging holes. The design key is to keep pressure drop distribution on the showerhead face plate with the holes. This study reads the methodology to apply to a showerhead hole design. A Hagen-Poiseuille equation gives the pressure drop in a fluid flowing through such hole. The assumptions of the equation are the fluid is viscous-incompressible and the flow is laminar fully developed in a through hole. An equation can be expressed with radius R and length L related to the volume flow rate Q from the Hagen-Poiseuille equation, $Q={\pi}R4{\Delta}p/8{\mu}L$, where ${\mu}$ is the viscosity and ${\Delta}p$ is the pressure drop. In present case, each hole has steps at both the inlet and the outlet, and the fluid appears compressible. So we simplify the equation as $Q=C(R,L){\Delta}p$. A series of performance curves for a through hole with geometric parameters were obtained using two-dimensional numerical simulation. We obtained a relation between the hole diameter and hole length from the test cases to determine hole diameter at fixed hole length. A numerical simulation has been performed as a tool for enhancing showerhead robust design from flow structure. Geometric parameters for the design were post distribution and face plate thickness. The reinforced showerhead has been installed and its effective deposition profile is being shown in factory.

• Journal of Korean Society of Forest Science
• /
• v.82 no.4
• /
• pp.347-353
• /
• 1993

Accumulation of air pollutants such as $SO_2$ and HF, chlorophyll contents, wax concentrations in needle tissue and needle growth of Pinus thunbergii were studied to verify possibilities of bioindicators of air pollution in Yochon Industrial Complex from July to October, 1991. The concentrations of water-soluble sulfur and fluorine increased nearer to the pollution sources regardless of sampling time, but water-soluble sulfur varied little during investigation and fluorine accumulated more with the passage of time. Total chlorophyll contents decreased a little in the slightly polluted site but sharply in the heavily polluted site. The higher the pollution level was, the more decreased chloroform-extractable wax. Air pollution exposure inhibited needle growth of Pinus tbunbergii during the latter part of growth period. Water soluble sulfur, fluorine and wax concentrations in needle of Pinus thunbergii were rather wood sensitive indicators of susceptibility to ambient air pollution from early July to early October. Chlorophyll contents seemed to be able to be used as a bioindicator of air pollution in early stage of needle development and in the severely polluted area. In the meanwhile needle length must be used as a bioindicator in latter part of growing season.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.8
• /
• pp.147-156
• /
• 2016

This study analyzed the impact of changes in the construction business on construction company insolvency according to their size using the vector error correction model. First, this study applied EDF (Expected Default Frequency), which was calculated by KMV (Kealhofer, McQuown and Vasicek) model, as a variable to indicate the insolvency of construction companies. This study set 30 construction companies listed to KOSPI/KOSDAQ for estimating the EDF by size and construction companies were divided into two groups according to their size. To examine the construction business cycles, the amount of construction orders according to the type-residential, non-residential, and civil work- was used as a variable. The serial data was retrieved from TS2000 established by the Korea Listed Companies Association (KLCA), Statistics Korea. The analysis period was between the second quarter of 2001 and fourth quarter of 2015. As a result of calculating the EDF of construction companies by size, as it is generally known, the large-sized construction companies showed lower levels of insolvency than relatively smaller-sized construction companies. On the other hand, impulse response analysis based on VECM confirmed that the level of insolvency of large-scaled companies is more sensitive to business fluctuations than relatively smaller-sized construction companies, particularly changes in the residential construction market. Hence it is a major factor affecting the changes in insolvency of large-sized construction companies.

• Journal of Distribution Science
• /
• v.14 no.6
• /
• pp.89-98
• /
• 2016

Purpose - This article tackles risk communication issues and aims to address the characteristics of MERS risk information distribution in South Korea, and secondly to examine the communicative behavior of the public health authority in terms of the quality of communication strategies. Thirdly, the study attempts to figure out the risk communication to cope with MERS through the applications of SMCRE model in chronological order. We employ the social amplification of risk framework for analyzing the emergent public response as one of the main approaches. Research Design, Data and Methodology - The main framework of this study is theoretically based on the social amplification of risk, which describes signals about risk transmitted and processed by individuals and social groups. The model also reflects the interactions between social groups and institutes about disaster-related risk issues, which are potential amplifiers or attenuators of communication signals. S-M-C-R-E Model is methodologically employed to examine the social amplification for MERS risk information in each period, which we defined operationally. The proposed methodology allows the assessment of effectiveness and ineffectiveness on risk communication to be conceptualized as a countermeasure against disasters. The paper focuses on exploring how social risk amplification can be applied and organized in each stage. Results - The SMCRE model describes the exchange of risk information and is also applied to all forms of communication between stakeholders including public health authority, local government and media. Each factor of risk communication includes source, message, channel, receiver and effect. The results support that the effective risk communication involves not only the improved reliability of public health authority as a key factor of risk communication, but also a close cooperation and good collaboration with local governments. It does not seem to be possible that the government-initiated risk communication based on controllability and management cope effectively with infectious disease in early stage. The results of this study imply that the shared risks between local, regional and national authorities can enhance risk communication system. Conclusions - The study supports that the disparities in how disaster-related risk information is interpreted and coded, have made effective risk communication and public sense-making impeded. Our findings support a more communicative discussion about the role of risk information sharing between governments for the improvement of emergency management and underline the importance of social elements in the risk communication, such as relationship and trust building. Findings suggest that trust building between stakeholders could be added to help explain the processes of social amplification and attenuation of risk. It would be recommended that the continuous risk communication with all the involved stakeholders will be able to help national health promotion policy to be improved regarding emergency management. Furthermore, risk communication has to be a scientific approach for the communication pertaining to potentially sensitive or controversial situations with public concerns and low public trust.

• Journal of the Korean Society of Radiology
• /
• v.9 no.2
• /
• pp.79-99
• /
• 2015

Participants of this study were students of radiology who were attending colleges or universities located in Daegu and Gyeongbuk. This researcher conducted a questionnaire survey of those students from Feb. 3rd to 21st, 2014. The findings of the study can be summarized as follows. 1. Concerning the knowledge of radiation exposure management, the respondents' scores were highest in two items, or 'Materials based on lead or concrete may shield X-rays' and 'The sexual gland is very sensitive to radiation' and lowest in the item which says' 'Occupational radiation exposure dose should not exceed 20mSv a year in average on a 5-year period basis'. 2. The participants' scores for the attitudes of radiation exposure management were higher in two items, or 'Health examination should be made regularly in relation to radiation exposure' and 'Those who work within the area of irradiation should wear protective clothes' and lowest in the item which says 'Radiation exposure dose should be regularly measured for the calibration of the radiation system'. 3. For the behaviors of radiation exposure management, the surveyed students showed highest scores in two items, or 'When irradiating the patient, the radiator should be behind the protective barrier(plate)' and 'It is needed to receive the education of radiation exposure management regularly' While, their score for a behavior described in the item saying 'Before using the radiation system, it is needed to check whether the machine works normally.