• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.505-513
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• 2022

In this study, 143 strains of Enterococcus spp. were isolated from inland pollution sources near shellfish farms on the west coast of South Korea. Not all isolated Enterococcus spp. strains possessed vancomycin resistance genes (VanA and VanB). However, since vancomycin-resistance Enterococcus (VRE) have been detected not only in the clinical field but also out in the world, it is possible that the VRE gene may be transferred to other bacterial strains commonly found in coastal waters where seafood is produced. It is important to monitor trends in the appearance of VRE. In addition, antimicrobial resistance patterns of isolates were examined in this study. Overall antimicrobial resistance rates were high: ciprofloxacin (32.2% of isolates resistant), chloramphenicol (30.8%), quinupristin/dalfopristin (19.6%), and tylosin (15.4%). Eight E. faecium strains (6.2%), out of the 129 strains assessed, showed multidrug resistance. All multidrug-resistant E. faecium showed resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin, in all 14 strains. All multidrug-resistant E. faecalis showed resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin. Both multidrug-resistant E. faecium and multidrug-resistant E. faecalis showed common resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin.

• Microbiology and Biotechnology Letters
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• v.51 no.3
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• pp.268-279
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• 2023

The pharmaceutical industry in Bangladesh produces a diverse range of antibiotics for human and animal use, however, waste disposal management is inadequate. This results in substantial quantities of antibiotics being discharged into water bodies, which provide suitable environment for the growth of antibiotic-resistant bacteria, capable of spreading resistance genes. This study intended for exploring the bacterial antibiotic resistance profile in adjoining aquatic environmental sources of pharmaceutical manufacturing facilities in Bangladesh. Seven surface water samples were collected from the vicinity of two pharmaceutical industries located in the Savar area and 51 Escherichia coli isolates were identified using both phenotypic and genotypic methods. Antibiotic susceptibility tests revealed the highest percentage of resistance against ampicillin, azithromycin, and nalidixic acid (100%) and the lowest resistance against meropenem (1.96%) out of sixteen different antibiotics tested. 100% of the study E. coli isolates were observed with Multidrug resistance phenotypes, with the Multiple Antibiotic Resistance (MAR) value ranging from 0.6-1.0. Furthermore, 69% of the isolates were Extended Spectrum Beta-Lactamases (ESBL) positive as per the Double Disk Diffusion Synergy Test (DDST). ESBL resistance genes bla_TEM, bla_CTX-M-13, bla_CTX-M-15, and bla_SHV were detected in 70.6% (n = 36), 60.8% (n = 32), 54.9% (n = 28), and 1.96% (n = 1) of the isolates, respectively, by Polymerase Chain Reaction (PCR). Additionally, 15.68% (n = 8) of the isolates were positive for E. coli specific virulence genes in PCR. These findings suggest that pharmaceutical wastewater, if not properly treated, could be a formidable source of antibiotic resistance spread in the surrounding aquatic environment. Therefore, continued surveillance for drug resistance among bacterial populations around drug manufacturing facilities in Bangladesh is necessary, along with proper waste disposal management.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.3
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• pp.335-342
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• 1999

The purpose of present research is to develop and efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. Havelock was considered the wave resistance of a post extending vertically downwards through the water from the surface, its section by a horizontal plane being the same at all depths and having its breadth small compared with its length. This enables us to elucidate certain points of interest in ship resistance. However, the ship has not infinite draft. So, the problem which is investigated ind detail in this paper is the wave resistance of a mathematical quadratic model in a uniform stream. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. The numerical results using the panel shift method and finite difference method are compared with the experimental results for wigley mono hull. There are no differences in the wave resistance. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

• Journal of Biosystems Engineering
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• v.4 no.2
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• pp.53-63
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• 1979

The knowlege of thermal properties of rough rice has become of greate importance to the analysis of heat and mass transfer phenomenon in rice drying and storage process. Some information is available on the thermal properties of rough rice in foreign countries but is not available for these properties in Korea. A fundamental study was made to determine the thermal conductivity and thermal diffusivity of rough rice with line source method and to select current and resistance suitable for these properties from investigating the effect of current and resistance of heating wire on the temperature rise. The result of this study may be summarized as follows ; 1. Even through the power per unit length of heating wires is about the same, the tendency of temperature rise showed a little difference among them , and the suitable range of it for thermal properties was found to be 3.56-5.37w/m. 2. the most desirable resistance and current of heating wire was 18.40 ohm/m, 0.44 amperes among three kinds of heating wires and currents, respectively. because it took 13 minutes or so for the heating wire to reach equilibrium temperature. 3. The thermal conductivity of rough rice was 0.120-0.130 w/m$ ^\circ C$. and thermal diffusivity of it was $5.8210 $\times10^{-8} -9.7529 $\times10^{-8} m^2 /s.$ 4.The thermal conductivity showed a little difference in variation with resistance of heating wire but the variation of current of heating wire at the same resistance did not affect the thermal conductivity , and the thermal diffusivity was not affected by the variation of resistance and current.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.104-110
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• 2008

In this paper we proposed a new source-drain structure for N-type MOSFET which can suppress the output resistance reduction of a device in saturation region due to soft break down leakage at high drain voltage when the gate is biased around relatively low voltage. When a device is generally used as a switch at high gate bias the current level is very important for the operation. but in electronic circuit like an amplifier we should mainly consider the output resistance for the stable voltage gain and the operation at low gate bias. Hence with T-SUPREM simulator we designed devices that operate at low gate bias and high gate bias respectively without a extra photo mask layer and ion-implantation steps. As a result the soft break down leakage due to impact ionization is reduced remarkably and the output resistance increases about 3 times in the device that operates at the low gate bias. Also it is expected that electronic circuit designers can easily design a circuit using the offered N-type MOSFET device with the better output resistance.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.4
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• pp.32-40
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• 2012

Geothermal heat pump(GHP) systems use vertical borehole heat exchangers to transfer heat to and from the surrounding ground via a heat carrier fluid that circulates between the borehole and the heat pump. An Important feature associated with design parameters and system performance is the local thermal resistances between the heat carrier flow channels in the borehole and the surrounding ground. This paper deals with the in-situ experimental determination of the effective thermal properties of the ground. The recorded thermal responses together with the line-source theory are used to determine the thermal conductivity and thermal diffusivity, and the steady-state borehole thermal resistance. In addition, this paper compares the experimental borehole resistance with the results from the different empirical and theoretical relations to evaluate this resistance. Further, the performance simulation of a GHP system with vertical borehole heat exchangers was conducted to analyze the effect of the borehole thermal resistance on the system performance.

• Clinical and Experimental Pediatrics
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• v.64 no.1
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• pp.12-20
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• 2021

The mean age at menarche (AAM) of Korean females has been rapidly decreasing over the last 50 years; currently, the prevalence of early menarche (<12 years) is 22.3%. Female adolescents who experience early menarche are known to be at greater risk of psychosocial and behavioral problems along with several physical health problems such as menstrual problems. They also tend to achieve a shorter final height and develop obesity. Population-based Korean studies have shown a strong association between early menarche and the risk of obesity, insulin resistance, metabolic syndrome, nonalcoholic fatty liver disease, diabetes, breast cancer, and cardiovascular disease in adulthood. Although the exact mechanism of how early menarche causes cardiometabolic derangement in later adulthood is unknown, childhood obesity and insulin resistance might be major contributors. Recent studies demonstrated that an excessive consumption of fructose might underlie the development of obesity and insulin resistance along with an earlier AAM. A positive association was observed between sugar-sweetened beverages (a major source of fructose) intake and obesity, metabolic syndrome, insulin resistance, and cardiometabolic risk in Korean females. In pediatrics, establishing risk factors is important in preventing disease in later life. In this regard, early menarche is a simple and good marker for the management of cardiometabolic diseases in adulthood. Decreasing one's fructose intake might prevent early menarche as well as the development of obesity, insulin resistance, and cardiometabolic diseases.

• The Plant Pathology Journal
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• v.38 no.4
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• pp.296-303
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• 2022

The cucurbit powdery mildew (CPM) caused by different fungal species is a major concern for cucurbit crops around the world. In Argentina CPM constitutes the most common and damaging disease for cucurbits, especially for squash crops (Cucurbita moschata). The present study displays initial insights into the knowledge of the disease in western Argentina, including the determination of the prevalent species causing CPM, as well as the evaluation of the resistance of squash cultivars and breeding lines. Fungal colonies were isolated from samples collected in Mendoza province, Argentina. A field trial was also performed to assess the resistance of five squash accessions, including commercial cultivars and breeding lines. The severity of CPM was analyzed and epidemiological models were built based on empirical data. The morphological determinations and analysis with specific molecular markers confirmed Podosphaera xanthi as the prevalent causal agent of CPM in Mendoza. The results od the field trial showed differences in the resistance trait among the squash accessions. The advanced breeding line BL717/1 showed promising results as source of CPM resistance for the future development of open pollinated resistant cultivars, a crucial tool for an integrative control of the disease.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.543-543
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• 2013

Thin-film transistors (TFTs) based on oxide semiconductors have been regarded as promising alternatives for conventional amorphous and polycrystalline silicon TFTs. Oxide TFTs have several advantages, such as low temperature processing, transparency and high field-effect mobility. Lots of oxide semiconductors for example ZnO, SnO2, In2O3, InZnO, ZnSnO, and InGaZnO etc. have been researched. Particularly, zinc-tin oxide (ZTO) is suitable for channel layer of oxide TFTs having a high mobility that Sn in ZTO can improve the carrier transport by overlapping orbital. However, some issues related to the ZTO TFT electrical performance still remain to be resolved, such as obtaining good electrical contact between source/drain (S/D) electrodes and active channel layer. In this study, the bottom-gate type ZTO TFTs with staggered structure were prepared. Thin films of ZTO (40 nm thick) were deposited by DC magnetron sputtering and performed at room temperature in an Ar atmosphere with an oxygen partial pressure of 10%. After annealing the thin films of ZTO at $400^{\circ}C$ or an hour, Cu, Mo, ITO and Ti electrodes were used for the S/D electrodes. Cu, Mo, ITO and Ti (200 nm thick) were also deposited by DC magnetron sputtering at room temperature. The channel layer and S/D electrodes were defined using a lift-off process which resulted in a fixed width W of 100 ${\mu}m$ and channel length L varied from 10 to 50 ${\mu}m$. The TFT source/drain series resistance, the intrinsic mobility (${\mu}i$), and intrinsic threshold voltage (Vi) were extracted by transmission line method (TLM) using a series of TFTs with different channel lengths. And the performances of ZTO TFTs were measured by using HP 4145B semiconductor analyzer. The results showed that the Cu S/D electrodes had a high intrinsic field effect mobility and a low effective contact resistance compared to other electrodes such as Mo, ITO and Ti.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.787-793
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• 2012

A hull form design technique to enhance the wave-making resistance performance for a medium size high speed Ro-Pax ship was studied introducing an optimization method and an automatic hull form modification method. SQP(sequential quadratic programming) was applied as the optimization algorithm and the geometry of hull surface was represented and modified using the NURBS(Non-Uniform Rational B-Spline). The wave-making resistance performance as an objective function in the optimization procedure was evaluated using the Rankine source panel method in which nonlinearity of the free surface boundary conditions and the trim and sinkage of the ship was fully taken into account. Using the Ro-Pax ship as a base hull, the hull-form optimization method was applied to obtain the hull shape that produced the lower wave-making resistance. To verify the validity of the hull-form optimization method, the numerical results was compared with the model test results.