• Nonlinear Functional Analysis and Applications
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• 제28권2호
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• pp.497-520
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• 2023

Numerous problems in science and engineering defined by nonlinear functional equations can be solved by reducing them to an equivalent fixed point problem. Fixed point theory provides essential tools for solving problems arising in various branches of mathematical analysis, such as split feasibility problems, variational inequality problems, nonlinear optimization problems, equilibrium problems, complementarity problems, selection and matching problems, and problems of proving the existence of solution of integral and differential equations.The theory of fixed is known to find its applications in many fields of science and technology. For instance, the whole world has been profoundly impacted by the novel Coronavirus since 2019 and it is imperative to depict the spread of the coronavirus. Panda et al. [24] applied fractional derivatives to improve the 2019-nCoV/SARS-CoV-2 models, and by means of fixed point theory, existence and uniqueness of solutions of the models were proved. For more information on applications of fixed point theory to real life problems, authors should (see [6, 13, 24] and the references contained in).

• 한국전자통신학회논문지
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• 제7권4호
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• pp.707-714
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• 2012

1단 2차 다중 피드백 델타-시그마 변조기와 2단 2차 MASH 델타-시그마 변조기를 해석하였으며 Simulink와 Matlab을 사용한 시뮬레이션을 수행하여 동작 특성을 비교한 결과 다음과 같은 결과를 얻었다: 1) 두 델타-시그마 변조기는 군지연 왜곡을 일으키지 않는다. 2) 잡음 성형 성능은 거의 같으며 잡음 성형의 결과 전력 스펙트럼 밀도는 40 dB/dec의 기울기를 갖는다. 3) 스퓨리어스 톤은 없다. 4) 두 변조기의 입력 범위는 공통적으로 -1부터 1까지이다. 5) 2단 MASH 변조기는 출력이 2 비트(4 레벨)이어서 PLL의 주파수 분주기와 charge pump의 설계가 복잡해진다.

• 대한지역사회영양학회지
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• 제7권3호
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• pp.354-360
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• 2002

The purposes of this study were (1) to understand how customers trade off one attribute against another when they choose a pizza restaurant, (2) to compare the importance of individual attributes with their relative importance and (3) to compare customers'brand choice patterns with the prediction of pizza restaurant operators. Empirical data for this study were collected from the customers (n=307) and operators (n=273) of flour famous pizza franchise restaurants in Korea, Pizza Hut, Mister Pizza, Domino's Pizza and Pizza Mall. The attributes and attribute levels for the hypothetical profiles were decided from the focus group discussion. A total of 16 profiles was selected from fractional factorial designs. The SPSS conjoint procedure was used to calculate utility scores and simulate profiles. The overall group statistics showed the relative importance of all attributes compared with one other. Taste was the most important attribute (32.48%) in choosing a pizza restaurant, followed by service (21.87%) , atmosphere (17.23%), price (15.17%) and speed of delivery (13.26%). There was a difference between the customers'ratings of the importance of the individual attributes and the ranking of the same attributes'relative importance as derived from the conjoint analysis. The operators rated service (26.54%) as also being important, as well as taste (27.76%), in choosing a pizza restaurant. The rankings of relative importance for pizza taste, service and price were statistically different in the customers'and operators'data (p < 0.001, p < 0.1, p < 0.5). Operators who want to differentiate themselves from their competitors should make decisions based on an increased understanding of their customers'brand choice decision process and measure the hidden needs of their customers.

• 한방재활의학과학회지
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• 제30권1호
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• pp.31-45
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• 2020

Objectives In this study, we investigated the antimicrobial activity of a 70% ethanol extract of Maneung-hwan (MEH), which is prescribed by practitioners of oriental medicine for use against methicillin-resistant Staphylococcus aureus (MRSA). Methods The antibacterial activity of MEH against MRSA strains was evaluated using the disc diffusion method, broth microdilution method (minimal inhibitory concentration, MIC), checkerboard dilution test, and time-kill test. The mechanism of action of MEH was investigated by bacteriolysis using detergents or ATPase inhibitors Additionally, mRNA and protein expression were investigated by quantitative reverse transcription-polymerase chain reaction and western blot assay, respectively. Results The MIC of MEH was 25~1,600 ㎍/mL against all the tested bacterial strains. We showed that MEH extract exerts strong antibacterial activity. In the checkerboard dilution test, the fractional inhibitory concentration index of MEH in combination with antibiotics indicated synergism or partial synergism against S. aureus. The time-kill study indicated that the growth of the tested bacteria was considerably inhibited after a 24-h treatment with MEH and selected antibiotics. To measure the cell membrane permeability, MEH (3.9 ㎍/mL) was combined with Triton X-100 (TX) at various concentrations N,N-dicyclohexylcarbodimide (DCCD) was also tested as an ATPase inhibitor. TX and DCCD cooperation against S. aureus exhibited synergistic action. Accordingly, the antimicrobial activity of MEH in the context of cell membrane rupture and ATPase inhibition was assessed. Additionally, the expression of genes and proteins associated with resistance was reduced after exposing MRSA to MEH. Conclusions These results suggest that MEH possesses antibacterial activity and acts as a potential natural antibiotic against MRSA.

• 한국임상수의학회지
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• 제36권3호
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• pp.159-165
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• 2019

Pimobendan is an inodilator used to treat canine heart failure, and pentoxifylline is reported to be beneficial for microcirculation and heart disease. The purpose of this study was to evaluate the pharmacokinetic and pharmacodynamic profiles of a novel pimobendan-pentoxifylline liquid mixture after oral administration to dogs. Eight healthy Beagle dogs were included in the study. The dogs were divided into the control group (orally administered water; n = 4) and experimental group (orally administered pimobendan-pentoxifylline liquid mixture [pimobendan 0.25 mg/kg, pentoxifylline 15 mg/kg]; n = 4). Plasma samples were obtained and echocardiographic indices were measured for 24 hours after administration. The concentrations of pimobendan and pentoxifylline were quantified by using a liquid chromatography-mass spectrometer (LC-MS). The elimination half-life ($T_{1/2}$) was $32.96{\pm}9.80mins$ for pimobendan and $29.49{\pm}6.67mins$ for pentoxifylline. The time to reach maximum concentration ($T_{max}$) were $52.50{\pm}31.22mins$ for pimobendan and $41.25{\pm}18.87mins$ for pentoxifylline. The maximum blood concentration ($C_{max}$) was $96.92{\pm}75.64ng/mL$ for pimobendan and $7074.07{\pm}3261.1ng/mL$ for pentoxifylline. Of the echocardiographic indices, fractional shortening (FS) and left ventricular internal diameter at end systole (LVIDs) were significantly altered at 1-3 hours after the administration of pimobendan-pentoxifylline liquid mixture. The pimobendan-pentoxifylline liquid mixture was well tolerated by the dogs, with no adverse effects observed during the study.

• 정신신체의학
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• 제25권2호
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• pp.153-165
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• 2017

연구목적 최근의 신경영상 연구들은 주요 우울장애의 기전을 인지 회로와 감정 회로 연결의 기능장애 즉, 후외방 전두피질과 전전두엽을 번연계로 연결하는 전측대상피질의 연결성 장애에 초점을 맞추고 있다. 소아청소년 주요 우울장애에서 확산텐서영상(diffusion tensor image, DTI)을 사용한 종전의 연구들은 양측 구상회속, 양측 하측 전두후두속, 좌측 전측대상피질, 좌측 상종속 등에서 신경연결의 감소를 보고하였다. 이 연구에서 우리는 정신과적 투약력이 없는 초발 주요 우울장애 청소년에서의 신경 연결성을 DTI를 이용하여 정상 대조군과 비교하였다. 방 법 고려대학교 구로병원을 내원한 청소년 환아들 중 정신과적 투약력이 없으며 주요 우울장애를 처음으로 진단받은 환아들(n=26, 남성 10명, 여성 16명) 및 대조군(n=27, 남성 5명, 여성 22명)을 모집하였다. 정신과적 면담, 지능지수, 해밀턴 우울척도를 포함한 심리검사, 확산강조영상을 포함한 MRI 검사가 항우울제 투약 전에 시행되었다. Fractional anisotropy(FA), radial diffusivity, mean diffusivity, axial diffusivity가 DTI를 사용하여 계산되었다. 통계적 분석을 위해 FMRIB Software Library-Tract Based Spatial Statistic가 사용되었다. 결 과 전체 뇌의 분석에서는 유의한 구조적 변화를 관찰할 수 없었다. 그러나 관심영역을 지정하여 시행한 분석을 하였을 때, 환아군에서 대조군에 비해 우측 상종속 부위에 유의미한 FA값의 감소를 보인 3개의 다발이 관찰되었다. 결 론 주요 우울장애를 진단받은 청소년 환아군에서 대조군에 비해 DTI에 기반하여 우측의 상종속에 연결성 감소를 보였다. 따라서 DTI를 통한 구조적 연결성은 정신과적 투약력이 없는 초발 주요 우울장애 청소년에서도 생체 표지자로 사용될 수 있을 것이라 생각된다.

• 천문학회지
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• 제24권2호
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• pp.217-271
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• 1991

We have observed dense core around young stellar objects, DR21, S140, Orion-KL, and L1551 using four millimeter-wave transitions of $HC_3N\;J$=4-3, J=5-4, J=10-9, and J=12-11. The spatial distribution of $HC_3N$ emission closely resembles the morphology of the previous CS observations that trace high density gas. These observations reveal the existence of $HC_3N$ dense cores around central IR source, elliptical in shape and almost perpendicular to the CO bipolar outflow axis. Small differences can be explained by that $HC_3N$ molecular line is more optically thin and is seen to be more detailed structure in the neighborhood of central IR sources. In S140 and Orion-KL, massive(${\sim}10\;M_{\odot}$), slowly rotating dense cores lie near at the central IR sources of bipolar outflows. The velocity channel maps of DR21 show that the bipolar outflow gas may have a correlation with the dense core of DR21. We analyzed intensities of the four lines to derive physical conditions in dense core from two methods, LTE and LVG. The column density of $HC_3N$, $N(HC_3N)$, between LTE and LVG calculations agree well with each other. The abundances of $HC_3N$ in each observing source have been estimated using the average values of $n(H_2)$ and $N(HC_3N)$ and assuming the size of dense core. The fractional $HC_3N$ abundances in massive dense cores of DR21, S140, and Orion-KL have a range of $(2-7){\times}10^{-10}$, while that of low mass dense core, L1551, has one order of magnitude greater value of $2{\times}10^{-9}$. This should be considered good agreement with the result by Morris et al.(1976). It may be considered that dense cores of DR21, S140, and Orion-KL may have almost same stage of chemical evolution, and their abundances have a small values relative to that of L1551. The column density $N(HC_3N)$ decreases with increasing distance from the densest part of the cloud, the central infrared source, and have the relation of $N(HC_3N){\varpropto}R^{\alpha}$, where a has a range of 0.65 to 0.89. The values of $n(H_2)$ are not varied with increasing distance from the dense core, and have almost same values. Therefore, it is considered that the dense cores in these regions probably consist of dense clumps in diffuse molecular gas medium, and $n(H_2)$ of each clump is ${\sim}10^5\;cm^{-3}$. Levels in the $T_{ex}$ increases with $n(H_2)$. It is considered that the $HC_3N$ dense cores are not completely thermalized. We examine the relationships between the luminosity of central infrared sources versus mass of the dense cores, and the luminosity of central infrared sources versus molecular hydrogen column density. Luminosities of the central IR sources show good correlation with mass and hydrogen column density of the dense core. Same has been found from CS observations. However, mass and size derived from $HC_3N$ observations are one order of magnitude smaller than those from CS. It can be interpreted that we see more central part of the cloud cores in $NC_3N$ lines than CS lines.

• 대한의용생체공학회:의공학회지
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• 제25권6호
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• pp.439-445
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• 2004

확산 텐서 영상은 조직 내 물 분자의 확산 현상을 이용하는 영상기법으로 조직 구조의 비등방성 및 방향성에 대한 정보를 제공해준다. 근육이나 뇌백질과 같은 조직에서는 신경다발들이 일정한 방향성을 가지고 있어서 그 방향에 대해서 확산이 잘 일어난다. 이러한 확산을 비등방성이라 한다. 확산의 비등방성의 정도는 RA, VR 그리고 FA와 같은 지표를 이용하여 나타낸다. 본 연구에서는 다른 확산 경사자장의 수에 대하여 각각 FA 영상을 만들었다. FA영상에 관심영역을 설정하고 FA 평균값 및 FA의 표준편차를 계산하였다. 그 결과, 경사자장의 방향수가 증가함에 따라서 FA값 및 FA의 표준편차가 감소하였다. 또한 ADC 측정 오차에 대한 표준 오차도 확산 경사자장의 방향수가 증가함에 따라서 감소하였다. 결론적으로 경사자장의 방향수에 따라서 잡음의 영향이 다르며, 더 많은 방향수를 사용하는 것이 FA영상의 질을 향상시킨다는 것을 알 수 있었다. 그러나 영상획득 시간과 FA의 표준편차 등을 고려했을 때. 임상적으로 사용될 확산 텐서영상의 방향수는 23개 정도가 적당하다고 결론 내릴 수 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권11호
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• pp.1558-1564
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• 2015

Cutaneous evaporative heat loss in Bos indicus and Bos taurus has been well documented. Nonetheless, how crossbreds with different fractional genetic proportions respond to such circumstances is of interest. A study to examine the physiological responses to cutaneous evaporative heat loss, also lactation period and milk yield, were conducted in Sahiwal (Bos indicus, n = 10, $444{\pm}64.8kg$, $9{\pm}2.9years$), Holstein Friesian (Bos taurus, HF100% (n = 10, $488{\pm}97.9kg$, $6{\pm}2.8years$)) and the following crossbreds: HF50% (n = 10, $355{\pm}40.7kg$, $2{\pm}0years$) and HF87.5% (n = 10, $489{\pm}76.8kg$, $7{\pm}1.8years$). They were allocated so as to determine the physiological responses of sweating rate (SR), respiration rate (RR), rectal temperature (RT), and skin temperature (ST) with and without hair from 06:00 h am to 15:00 h pm. And milk yield during 180 days were collected at days from 30 to 180. The ambient temperature-humidity-index (THI) increased from less than 80 in the early morning to more than 90 in the late afternoon. The interaction of THI and breed were highly affected on SR, RR, RT, and ST (p<0.01). The SR was highest in Sahiwal ($595g/m^2/h$) compared to HF100% ($227g/m^2/h$), and their crossbreds both HF50% ($335g/m^2/h$) and HF87.5% ($299g/m^2/h$). On the other hand, RR was higher in HF87.5% (54 bpm) and both HF100% (48 bpm) and HF50% (42 bpm) than Sahiwal (25 bpm) (p<0.01). The RT showed no significant differences as a result of breed (p>0.05) but did change over time. The ST with and without hair were similar, and was higher in HF100% ($37.4^{\circ}C$; $38.0^{\circ}C$) and their crossbred HF50% ($35.5^{\circ}C$; $35.5^{\circ}C$) and HF87.5% ($37.1^{\circ}C$; $37.9^{\circ}C$) than Sahiwal ($34.8^{\circ}C$; $34.8^{\circ}C$) (p<0.01). Moreover, the early lactation were higher at HF100% (25 kg) and 87.5% (25 kg) than HF50% (23 kg) which were higher than Sahiwal (18 kg) while the peak period of lactation was higher at HF100% (35 kg) than crossbreds both HF87.5% and HF50% (32 kg) which was higher than Sahiwal (26 kg) (p<0.05). In conclusion, sweating and respiration were the main vehicle for dissipating excess body heat for Sahiwal, HF and crossbreds, respectively. The THI at 76 to 80 were the critical points where the physiological responses to elevated temperature displayed change.

• 한국식품영양과학회지
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• 제41권9호
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• pp.1220-1225
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• 2012

본 연구는 곤달비(Ligularia stenocephala)의 생리 효능을 체계적으로 밝히기 위한 기초 자료를 얻고자 80% 에탄올 추출물과 순차적 분획물에 대하여 항산화 및 항균 효과를 검증하였다. 곤달비 에탄올 추출물의 추출수율은 21.36%이었으며, 이에 대하여 용매별로 분획한 수율은 water 분획물이 60.35%로 가장 높았으며, n-butanol, n-hexane, ethyl acetate 순이었다. 곤달비 추출물 및 분획물의 총 폴리페놀 함량은 ethyl acetate 분획물에서 254.00 mg/g으로 가장 높게 나타났다. DPPH radical 소거활성을 측정한 결과, 곤달비 ethyl acetate 분획물에서 $IC_{50}$ 값이 0.28 mg/mL로 높은 활성을 나타내었다. 0.5 mg/mL 농도에서의 ABTS 라디칼 소거활성은 ethyl acetate 분획물에서 96.67%의 활성을 보였다. FRAP 활성 역시 1 mg/mL 농도에서 ethyl acetate 분획물이 2.70 mM의 가장 높은 활성을 나타내었다. 항균활성은 B. cereus 균주에 대해 ethyl acetate 분획물 5 mg/disc에서 10.2 mm의 저해환을 나타내었다. 이상의 결과에서 곤달비의 추출물 및 분획물 중 ethyl acetate 분획물의 경우 높은 항산화 활성과 약간의 항균활성을 나타내었으며 천연물소재로서 식품첨가물 및 화장품 원료로의 가능성이 있는 것으로 사료된다.