• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.4
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• pp.275-283
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• 2013

In this paper, the structural optimum design method of composite rotor blade cross-section was investigated with the genetic algorithm. An auto-mesh generation program was developed for iterative calculations of optimum design, and stresses in the blade cross-section were analyzed by VABS (variational asymptotic beam sectional analysis) program. Minimum mass of rotor blade was defined as an object function, and stress failure index, center mass and blade minimum mass per unit length were chosen as constraints. Finally, design parameters such as the thickness and layup angles of a skin, and the thickness, position and width of a torsion box were determined through the structural optimum design method of composite rotor blade cross-section presented in this paper.

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.380-389
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• 2013

The nurse staffing level in the acute care hospitals affects patient safety and performance, and the nurse staffing legislation can be an important tool to guarantee the minimum nurse staffing. In Korea, although the medical law suggests the nurse staffing standards, it is necessary to revise the medical law for quality of nursing care and patient safety. Firstly, the nurse staffing standards in the current medical law enacted in 1962 needs to be revised to reflect changes in health care environment. Secondly, legal nurse staffing standards in the medical law are the minimum nurse staffing that medical institutions should comply with and thus must be managed so that all medical institutions should abide by them. Thirdly, the nurse staffing standards should apply on the basis of RN-to-patient ratios per shift in order to help patients understanding and ensure the easy management. Fourthly, the information of nursing staff level by the nursing unit and nursing shift in hospitals shall be released.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.11-18
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• 1998

A binary line code, called MB46d, is designed by use of the BUDA(Binary Unit DSV and ASV) cell concept to retain the property of being runlength limited, DC tree, and with a power spectral null at the Nyquist frequency. This new code is a stateless line code with a simple encoding and a decoding rule and enables efficient error monitoring. The power spectrum and the eye pattern of the new line code are simulated for a minimum-bandwidth digital transmission system where the sinc function is used as a basic pulse. The obtained power null at the Nyquist frequency is wide enough to enable easy band-limiting as well as secure insertion of a clock pilot where necessary. The eye is also substantially wide to tolerate a fair amount of timing jitter in the receiver.

• Journal of the Korea Society of Computer and Information
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• v.19 no.5
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• pp.19-25
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• 2014

In this paper, I seek the chromatic number, the maximum number of colors necessary when adjoining vertices in the plane separated apart at the distance of 1 shall receive distinct colors. The upper limit of the chromatic number has been widely accepted as $4{\leq}{\chi}(G){\leq}7$ to which Hadwiger-Nelson proposed ${\chi}(G){\leq}7$ and Soifer ${\chi}(G){\leq}9$ I firstly propose an algorithm that obtains the minimum necessary chromatic number and show that ${\chi}(G)=3$ is attainable by determining the chromatic number for Hadwiger-Nelson's hexagonal graph. The proposed algorithm obtains a chromatic number of ${\chi}(G)=4$ assuming a Hadwiger-Nelson's hexagonal graph of 12 adjoining vertices, and again ${\chi}(G)=4$ for Soifer's square graph of 8 adjoining vertices. assert. Based on the results as such that this algorithm suggests the maximum chromatic number of a planar graph is ${\chi}(G)=4$ using simple assigned rule of polynomial time complexity to color for a vertex with minimum degree.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.5769-5777
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• 2015

According to the forming or bending deformation in the press die, the thin plate occurs a work-hardening, the sheet hardening and cam unit's deformation causes incomplete forming during the cam molding process by the reacting spring forces. This study treated the input parameters of the stress and strain as given properties and also used Cam forming pressure considering the sheet hardening in the forming process of the aluminum sheet. The Hyperstudy are operated be linked with the Abaqus of the finite element analysis tool and the shape of Cam were carried out with non-linear shape optimization analysis. As a result removing the deformation of plate, the cam shape were optimized under conditions reduced deformation, having a minimum stress range and the minimum deformation. Therefore, a stress-strain curve and a normal distribution of stress-thickness can be obtained and optimization could be obtained for the shape of the stress and strain on the die plate hardened cam considering the thickness and reaction force of gas spring as iteration process.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.342-351
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• 2018

Purpose: Recently, an increasing number of farms have been cultivating shiitake mushrooms using a sawdust substrate and a cooler/heater. In this study, an attempt was made to develop an environmental control system using a heat pump for cultivating high-quality shiitake mushrooms. Methods: An environmental control system, consisting of an air-to-water type heat pump, a thermal storage tank, and a radiator in a variable opening chamber, was designed and fabricated. The system was also installed in the cultivation facility of a farm cultivating shiitake mushrooms so as to compare the proposed control system with a conventional environmental control system using a cooler-condensing unit and an electric hot water boiler. Results: The uniformity of the environment was analyzed through environment measurements taken at several positions inside the cultivation facility. It was determined that the developed environmental control system is able to control the variations in temperature and relative humidity to within 1% and 3%, respectively. In addition, a maximum temperature difference of $30^{\circ}C$ (maximum of $35^{\circ}C$, minimum of $5^{\circ}C$) and a maximum relative humidity difference of 30% (maximum of 90%, minimum of 60%) can be attained within 30 min inside the cultivation facility through the cooling of the heat pump and heating of the radiator in a variable opening chamber. Thus, the developed control system can be used to cultivate high-quality shiitake mushrooms more effectively than a conventional cooler and heater. Conclusions: In comparison with a conventional environmental control system, the developed system decreased the yield of ordinary mushrooms by 65%, and increased that of high-quality mushrooms by 217%. This corresponds to a 16% increase in gross farm income. Consequently, the developed system is expected to improve the income of shiitake mushroom cultivating farms.

• Journal of dental hygiene science
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• v.21 no.2
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• pp.119-126
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• 2021

Background: Dental caries is mainly composed of various cellular components and is deposited around the tooth surface and gums, causing a number of periodontal diseases. Streptococcus mutans is commonly found in the human oral cavity and is a significant contributor to tooth decay. The use of antibacterial ingredients in oral hygiene products has demonstrated usefulness in the management of dental caries. This study investigated the anticaries effect of the ethanol extract of Terminalia chebula (EETC) against S. mutans and their cytotoxicity to gingival epithelial cells. Methods: The EETC was prepared from T. chebula fruit using ethanol extraction. Disk diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and colony forming unit (CFU) were analyzed to investigate the antimicrobial activity of the EETC. Glucan formation was measured using the filtrate of the bacterial culture medium and sucrose. Gene expression was analyzed using reverse transcription-polymerase chain reaction (RT-PCR). Cytotoxicity was analyzed via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Results: The antibacterial activity of the EETC was explored using disc diffusion and CFU measurements. The MIC and MBC of the EETC were 10 and 20 ㎍/ml, respectively. EETC treatment decreased insoluble glucan formation by S. mutans enzymes and also resulted in reduced glycosyltransferase B (gtf B), gtf C, gtf D, and fructosyltransferase (ftf), expressions on RT-PCR. In addition, at effective antibacterial concentrations, EETC treatment was not cytotoxic to gingival epithelial cells. Conclusion: These results demonstrate that the EETC is an effective anticaries ingredient with low cytotoxicity to gingival epithelial cells. The EETC may be useful in antibacterial oral hygiene products for the management of dental caries.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1179-1188
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• 2023

Escherichia coli, particularly multidrug-resistant (MDR) strains, is a serious cause of healthcare-associated infections. Development of novel antimicrobial agents or restoration of drug efficiency is required to treat MDR bacteria, and the use of natural products to solve this problem is promising. We investigated the antimicrobial activity of dried green coffee (DGC) beans, coffee pulp (CP), and arabica leaf (AL) crude extracts against 28 isolated MDR E. coli strains and restoration of ampicillin (AMP) efficiency with a combination test. DGC, CP, and AL extracts were effective against all 28 strains, with a minimum inhibitory concentration (MIC) of 12.5-50 mg/ml and minimum bactericidal concentration of 25-100 mg/ml. The CP-AMP combination was more effective than CP or AMP alone, with a fractional inhibitory concentration index value of 0.01. In the combination, the MIC of CP was 0.2 mg/ml (compared to 25 mg/ml of CP alone) and that of AMP was 0.1 mg/ml (compared to 50 mg/ml of AMP alone), or a 125-fold and 500-fold reduction, respectively, against 13-drug resistant MDR E. coli strains. Time-kill kinetics showed that the bactericidal effect of the CP-AMP combination occurred within 3 h through disruption of membrane permeability and biofilm eradication, as verified by scanning electron microscopy. This is the first report indicating that CP-AMP combination therapy could be employed to treat MDR E. coli by repurposing AMP.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.37-45
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• 2016

The effect of substrate size on the radiation characteristics of an H-plane 5-elements linear array antenna with an aperture coupled microstrip patch antenna (ACMPA) as unit element is investigated. The distance between the patch center and the substrate edge on the E-plane ($d_E$) and that on the H-plane ($d_H$) at which the maximum broadside gain of an H-plane 5-elements linear array antenna occurs are the same to those of single ACMPA using a unit element. Besides, $d_E$ and $d_H$ at which the minimum broadside gain of an H-plane 5-elements linear array antenna occurs are almost the same to those of single ACMPA using a unit element. The edge effect on the radiation characteristics of an H-plane 5-elements linear array antenna is mainly determined by $d_E$. The optimum substrate size for the radiation characteristics of an H-plane linear array antenna could be obtained from that of single ACMPA using a unit element of an H-plane linear array antenna.

• Geophysics and Geophysical Exploration
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• v.7 no.4
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• pp.245-250
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• 2004

Horizontal-axes on the seismic section have been represented in a distance unit by applying horizontal-distance correction transformation on a 2-D seismic section of single channel marine seismic data. By drawing horizontal-axes in a distance unit, distortion of horizontal distances shown on the seismic section when the ship speed varies during a survey can be diminished considerably. Position information obtained by GPS and stored in each trace of seismic data as well as data collection windows were used for horizontal distance correction. The minimum window length was decided by considering ship speed and shot interval, and the maximum window length wat determined by reflecting radius of the 1st Fresnel zone. In choosing an optimum window length, horizontal resolution and stacking effect were considered simultaneously. By applying horizontal distance correction we could get a 2-D seismic section which is considered at reflecting the real subsurface structure analogously.