• Elastomers and Composites
• /
• 제43권3호
• /
• pp.166-172
• /
• 2008

268 nm두께의 PVAc가 코팅된 수정결정 미소저울(QCM)을 사용하여 저항과 진동수 변화를 측정하였다. 이를 이용하여 온도($25^{\circ}C\sim42^{\circ}C$)와 톨루엔의 증기압(12.4$\sim$28.4 torr)변화에 따른 톨루엔의 폴리비닐아세테이트에 대한 용해도를 측정하였다. 진동수는 온도가 증가함에 따라 증가하였으나 톨루엔의 증기압이 증가하면 감소하는 경향을 보였다. 톨루엔의 온도가 증가함에 따라 저항은 감소하였으며, 증기압이 증가하면 저항도 증가하는 경향을 나타내었다. Sauerbrey 식을 이용하여 온도와 압력변화에 따른 용해도 변화를 측정하였다.

• 대한전자공학회논문지
• /
• 제25권11호
• /
• pp.1282-1285
• /
• 1988

2개의 측온 저항체 온도 센서(RTD)를 이용한 온도차-주파수 변환기를 개발했다. 2개의 측온 저항체 온도 센서(RTD)의 저항차는 콜피츠 발진기의 공진 회로를 형성하는 등가 인덕턴스로 변환된다. 제안한 변환기는 35$^{\circ}C$에서 155$^{\circ}C$의 온도차 범위에서 16Hz/$^{\circ}C$의 변환 감도와 2.15%의 최대 직선 오차를 나타낸다. 발진기 자체의 주파수 드리프트는 $\pm$ 0.5Hz이다. 따라서, 최소 검출 가능 온도차는 $\pm$ 0,013$^{\circ}$C로 평가된다. 측온 저항체 온도 센서(RTD)을 제외한 모든 회로는 모노리딕 IC형태로 제작 할 수 있다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1985년도 하계학술회의논문집
• /
• pp.341-343
• /
• 1985

In designing the high frequency oscillator with FET, it may be necessary to make the FFT unstable using feedback. For convenient realization, sir feedback type is usually employed. It is convenient to determine the load which makes oscillation possible, with the contour plot of the negative resistance of the FET positively feedback for each type. Analytic formulas are given for this contour plot in this paper, and the results are discussed.

• 전기전자학회논문지
• /
• 제23권2호
• /
• pp.722-726
• /
• 2019

본 논문에서는 고주파 영역에서의 전원잡음제거 (PSR) 특성이 개선된 low drop-out (LDO) 레귤레이터를 제안한다. 특히, PMOS 전력 스위치의 유한한 출력저항을 관통하는 고주파 전원잡음을 상쇄하기 위해 출력저항이 큰 NMOS 트랜지스터를 보상 회로로 추가하였다. 보상 트랜지스터에 의한 전원잡음제거는 해석적으로 설명하여 개선에 대한 방향을 제시하였다. $0.35{\mu}m$ 표준 CMOS 공정으로 회로를 제작하고 Spectre 시뮬레이션을 수행하여 10MHz에서 기존의 LDO 레귤레이터 대비 26dB의 PSR 개선을 확인하였다.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 1997년도 특별강연 및 춘계학술발표 개요집
• /
• pp.151-153
• /
• 1997

• Geomechanics and Engineering
• /
• 제19권1호
• /
• pp.11-20
• /
• 2019

The use of electrokinetic dissipation method to study the fluid flow law in micro-pores is of great significance to reservoir rock microfluidics. In this paper, the micro-capillary theory was combined with the coupling model of the seepage field and the current field under the excitation of the harmonic signal, and the coupling theory of the electrokinetic effect under the first-order approximation condition was derived. The dissipation equation of electrokinetic dissipation and viscous resistance dissipation and its solution were established by using Green's function method. The physical and mathematical models for the electrokinetic dissipation of reservoir rocks were constructed. The microscopic mechanism of the electrokinetic dissipation of reservoir rock were theoretically clarified. The influencing factors of the electrokinetic dissipation frequency of the reservoir rock were analyzed quantitatively. The results show that the electrokinetic effect transforms the fluid flow profile in the pores of the reservoir from parabolic to wavy; under low-frequency conditions, the apparent viscosity coefficient is greater that one and is basically unchanged. The apparent viscosity coefficient gradually approaches 1 as the frequency increases further. The viscous resistance dissipation is two orders of magnitude higher than the electrokinetic effect dissipation. When the concentration of the electrolyte exceeds 0.1mol/L, the electrokinetic dissipation can be neglected, while for the electrolyte solution (<$10^{-2}M$) in low concentration, the electrokinetic dissipation is very significant and cannot be ignored.

• Corrosion Science and Technology
• /
• 제20권6호
• /
• pp.492-492
• /
• 2021

• 대한수의학회지
• /
• 제20권2호
• /
• pp.113-118
• /
• 1980

Total of 11 strains of Ldctobacillus isolated from lactobacillus-fermented milk and-beverage in March 1980 were examined for susceptibility to 8 drugs, and transferability and transfer frequency of R plasmids by conjugation. Of 11 isolates each 2 strains were classified as L. cellobiosus and L. helveticus, each 1 strain as L. plantarum, L. lactis, L. acidophilus, L. delbrueckii, L. casei subsp. casei, L. casei subsp, tolerans and L. salivarius subsp, salivarius by Bergey's manual. Resistance was the most active to na lidixic acid(NA), followed in decreasing order by chloramphenicol(CP), ampicillin(AP), kanamycin(KM) and streptomycin(SM). All of isolates were resistant to NA, each 10 strains to CP and AP, 7strains to KM and 6 strains to SM, indicating all of the isolates were resistant to two or more drugs in combination. No strain was resistant to erythromycin(EM), penicillin(PC) and tetracycline(TC). The most frequently encountered resistant patterns were CP NA AP SM KM, followed by CP NA AP KM, NA AP, CP NA, CP NA AP and CP NA AP SM in order. Transfer experiment of drug resistance showed that of 11 resistant strains, 9 strains transferred parts of their resistance to AP or AP CP or SM AP, indicating 9 strains carried R plasmids determining R(AP), R(AP CP) and R(SM AP). The conjugal frequency of R(AP) from Lactobacillus to E. coli ranged from 2.5{\times}10^{-1} to $5.6{\times}10^{-4}%$, that of R(CP) ranged from 5.0{\times}10^{-1} to 5.0{\times}10^{-3}% and that of R(SM) ranged from 6.0{\times}10^{-5} to 1.4{\times}10^{-5}%, at $37^{\circ}C$ for 18 hours of incubation.

• Childhood Kidney Diseases
• /
• 제21권2호
• /
• pp.121-127
• /
• 2017

Purpose: The aim of this study was to determine the prevalence of antibiotic susceptibility and resistance of Escherichia coli in urinary tract infections (UTIs) in children. Methods: We retrospectively reviewed the clinical records of 212 inpatients aged 18 years or younger with UTIs treated at the Pediatric Department of Dongguk University Gyeongju Hospital between January 2008 and December 2016. For comparison, patients were divided into three groups according to age as follows: group 1, ${\leq}1$ month; group 2, >1 month to ${\leq}12$ months; and group 3, ${\geq}13$ months. The antibiotic resistance rates from January 2008 to December 2012 (study period 1) and from January 2013 to December 2016 (study period 2) were analyzed statistically by group. Results: As the patient age increased, the antibiotic resistance rate to ampicillin (P=0.013), levofloxacin (P=0.050), piperacillin/tazobactam (TZP) (P<0.001), and trimethoprim/sulfamethoxazole (P=0.002) increased. The frequency of extended spectrum beta-lactamase producing E. coli showed a significant difference from 5 cases (4.6%) in study period 1 and 16 cases (15.8%) in study period 2 (P=0.007). The antibiotic resistance rate of E. coli was compared between the two time periods and we found that the antibiotic resistance rate to cefotaxime was significantly increased from 5.4% to 16.8% (P=0.008) and that to TZP was significantly decreased from 40.5% to 7.9% (P<0.001). Conclusion: Over the past 9 years, the resistance rate to cefotaxime has increased but the resistance rate to TZP has decreased. Thus, it is important to continue to investigate the antibiotic resistance rates of bacteria in the community.

• 한국전기전자재료학회논문지
• /
• 제32권1호
• /
• pp.40-46
• /
• 2019

To study the frequency response characteristics of alternating-current-driven organic light-emitting diodes (OLEDs), we fabricated blue-fluorescent OLEDs and analyzed their electroluminescent characteristics according to the alternating current voltage and frequency. The luminance-frequency characteristics of alternating-current-driven OLED was similar to that of a low-pass filter, and the luminance of high-voltage OLED decreased at higher frequency than low-voltage OLED. The luminance characteristics of the OLED according to the frequency is due to the capacitive reactance in the OLED, generated during the alternating current driving. The frequency response characteristics of the OLED according to the voltage is due to the decrease in internal resistance of the organic layer. In addition, the negative voltage component of the alternating current did not affect the frequency response of the OLED. Therefore, the electroluminescent characteristics of OLED with an alternating current power of 60 Hz are not influenced by the frequency.