• Journal of applied mathematics & informatics
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• v.41 no.1
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• pp.167-179
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• 2023

In this paper, we investigate solutions of equations which are linear (p, q)-difference equation of higher order by using (p, q)-derivative and integral. We also derive the solution of equation in the case of second order.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.610-619
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• 2022

Hydrogen is emerging as an alternative fuel for eco-friendly ships because it reacts with oxygen to produce electrical energy and only water as a by-product. However, unlike regular fossil fuels, hydrogen has a material with a high risk of explosion due to its low ignition point and high flammability range. In order to safely use hydrogen in ships, it is an essential task to study the flow characteristics of hydrogen leakage and diffusion need to be studied. In this study, a numerical analysis was performed on the effect of leakage, ventilation, etc. on ventilation performance when hydrogen leaks in an enclosed space such as inside a ship. ANSYS CFX ver 18.1, a commercial CFD software, was used for numerical analysis. The leakage rate was changed to 1 q, 2 q, and 3 q at 1 q = 1 g/s, the ventilation rate was changed to 1 Q, 2 Q and 3 Q at 1 Q = 0.91 m/s, and the ventilation method was changed to type I, type II, type III to analyze the ventilation performance was analyzed. As the amount of leakage increased from 1 q to 3 q, the HMF in the storage room was about 2.4 to 3.0 times higher. Furthermore, the amount of ventilation to reduce the risk of explosion should be at least 2 Q, and it was established that type III was the most suitable method for the formation of negative pressure inside the hydrogen tank storage room.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.927-931
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• 2010

Recently, high luminance and high efficiency were realized in OLED with multilayer structure including emitting materials such as metal-chelate complexes. We synthesized a new luminescent material, namely, [2-(2-hydroxyphenyl)quinoline] (Zn(HPB)q) which has low molecular compound and emitted in yellowish green region. The ionization potential(IP) and electron affinity(EA) of Zn(HPB)q were measured by cyclic-voltammetry(CV). As a result, IP and EA of Zn(HPB)q were calculated 6.8 eV and 3.5 eV, respectively. We fabricated the devices and observed the possibility of Zn(HPB)q as electron transporting layer. We have obtained an improvement of luminance and decrease of turn-on voltage using Zn(HPB)q as electron transporting layer.

• International journal of steel structures
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• v.18 no.5
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• pp.1497-1507
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• 2018

Most of previous studies on fire resistance of restrained steel beams neglected creep effect due to lack of suitable creep model. This paper presents a finite element model (FEM) for accessing the fire resistance of restrained high strength Q460 steel beams by taking high temperature Norton creep model of steel into consideration. The validation of the established model is verified by comparing the axial force and deflection of restrained beams obtained by finite element analysis with test results. In order to explore the creep effect on fire response of restrained Q460 steel beams, the thermal axial force and deflection of the beams are also analyzed excluding creep effect. Results from comparison infer that creep plays a crucial role in fire response of restrained steel beam and neglecting the effect of creep may lead to unsafe design. A set of parametric studies are accomplished by using the calibrated FEM to evaluate the governed factors influencing fire response of restrained Q460 steel beams. The parametric studies indicate that load level, rotational restraint stiffness, span-depth ratio, heating rate and temperature distribution pattern are key factors in determining fire resistance of restrained Q460 steel beam. A simplified design approach to determine the moment capacity of restrained Q460 steel beams is proposed based on the parametric studies by considering creep effect.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.82-87
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• 2009

In order to characterize the ecological traits of Quercus acutissima, Q. variabilis and Q. mongolica, which dominated in Korean mountain, we treated the sapling of the three oak species under the major environment factors (light, soil moisture and nutrient) with four gradient levels, for 8 months in glass house. Then we measured and analyzed the growth difference among them. The growth of Q. acutissima and Q. variabilis were increased with higher light intensity, but there is no apparent trend in Q. mongolica for light gradients. Q. mongolica did not show high reduction of growth, even in the lowest light intensity. Q. variabilis and Q. mongolica had a constant growth state to soil moisture treatment, but only Q. acutissima grew well in higher soil moisture gradient condition. All the growth of three oak species decreased with higher nutrient gradient condition. The growth reduction was increased in order of Q. variabilis, Q. mongolica and Q. acutissima. with increased nutrient gradient level. These results means that Q. mongolica, Q. acutissima and Q. variabilis have adaptation ability to shade, high moisture and low nutrient condition, respectively.

• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.211-218
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• 2002

The reversed two station method (RSTM) devised by Chun et al. (1987) is widely used to obtain $Q_{Lg}^{-1}$ for Lg wave data with hypocentral distance greater than 90 km. By applying RSTM to the Lg data of central South Korea with hypocentral distance between 95 and 381 km, we obtained high $Q_{Lg}^{-1}$. The value of $Q_{Lg}^{-1}$ is very similar with that of southeastern S. Korea, which is derived from the same method for similar distances. The studied hypocentral range seems to distort $Q_{Lg}^{-1}$ to high value because decay rate in this range is higher than 0.5, which is typical decay rate of surface wave.

• Journal of Veterinary Clinics
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• v.26 no.5
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• pp.413-418
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• 2009

This study was performed to investigate the changes of the serological parameters of the rats fed a high fat and high cholesterol diets with or without quercetin supplement for five weeks. Thirty Sprague-Dawley male rats ($152.1{\pm}17.0\;g$ of body weight) were randomly divided into three groups with 10 rats in each group. Rats in the control(C) group were fed the high fat and high cholesterol diet containing 15% lard, 2% cholesterol and 0.5% sodium cholate (w/w). Rats in two treatment groups were fed the same diet supplemented with 0.25% quercetin (Q-0.25) or 0.5% quercetin (Q-0.5) on the weight to weight basis, respectively. The final body weight, gain of body weight, the amount of feed intake and the feed efficiency of rats in between control and treatment groups were not significantly different. Serum glucose, total protein, albumin, globulin and albumin/globulin (A/G) ratio of rats showed no significant differences between control and treatment groups. Serum total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C) and atherogenic index(AI) of rats in both Q-0.25 and Q-0.5 groups were significantly lower than in C group (p < 0.05). However serum high density lipoprotein-cholesterol (HDL-C) was significantly higher in both Q-0.25 and Q-0.5 groups than in C group (p < 0.05). The levels of triglyceride in sera of rats showed no significant differences between control and treatment groups. The values of AST and ALT in sera of rats showed no significant differences between control and treatment groups. Therefore the supplementation of quercetin to high fat and high cholesterol diet in rats was effective in reducing the levels of serum lipids to cause cardiovascular diseases and in elevating the level of HDL-C to protect cardiovascular diseases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.3
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• pp.343-354
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• 2012

In this paper, various spiral zeroth-order resonators are proposed for wireless power transmission. Since a zerothorder resonance(ZOR) mode of meta-material transmission lines has the characteristic of an infinite wavelength, its frequency is independent of physical length. Also, to obtain high transmission efficiencies high-Q resonators and strong coupling coefficient between coupled resonators are required. Therefore, the resonators consist of spiral inductor and lumped capacitor to use the ZOR mode and they are optimized via parametric study and circuit analysis for a high-Q resonator design. The optimized resonators are simulated and compared with a conventional spiral resonator and one of them was fabricated and measured. The fabricated one has a dimension of $20cm{\times}20cm{\times}8cm$($0.009{\lambda}_0{\times}0.009_{\lambda}_0{\times}0.004{\lambda}_0$) and the transmission efficiency of 80 % is measured at 13.56 MHz at transmitted distance of 40 cm.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.237-240
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• 2005

A novel current mode high Q bandpass filter with electronically tuable values of Q based on second generation current controlled conveyor CCCIIs is presented. The circuit offers the advantages of using a few passive elements. The center frequency and pole-Q can be independently adjusted by via dc bias current of CCCIIs, It is shown from SPICE simulation that the results agree well with theoretical analysis

• The Journal of the Society of Korean Medicine Diagnostics
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• v.15 no.1
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• pp.111-126
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• 2011

Objectives: To characterize Five Woons in 1993, 1994 and 1995. Methods: A diagnostic questionnaire was given to 1066 High School students who were born in Korea from 1993 to 1995. One of the Five Woons was given to the participant based on his and her birthday. The oneway analysis of variance was applied to compare the means of the Five Woons in each year. Results: 1. Developed a reliable questionnaire consisting of 28 items for the purpose of chracterizing five constitutions. 2. Based on the Duncan method, significant differences were observed among the Five Woons in height, weight and BMI (p<0.1). For height, the score of Wood constitution was lowest. For weight the core of Soil constitution was lowest. 3. Based on the Duncan method, at the significant level (p<0.1), the Five Woons were different in each year (Gapsul year, Eulhae year, Gyeyoo year) for 28 items in the questionnaires: Q1, Q2,Q3, Q7, Q8, Q11, Q12, Q15, Q18, Q19, Q21, Q22, Q24, Q26, Q27 and Q28. Conclusions: Further clinical research is necessary to characterize five constitutions and also develop more delicate analyses and questionnaires. Also the diagnosis and corresponding treatments based on the Five Woons should be further studied in view of the Asian medicine.