• 대한수학회지
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• 제52권1호
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• pp.1-21
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• 2015

C-domains are defined via class semigroups, and every C-domain is a Mori domain with nonzero conductor whose complete integral closure is a Krull domain with finite class group. In order to extend the concept of C-domains to rings with zero divisors, we study v-Marot rings as generalizations of ordinary Marot rings and investigate their theory of regular divisorial ideals. Based on this we establish a generalization of a result well-known for integral domains. Let R be a v-Marot Mori ring, $\hat{R}$ its complete integral closure, and suppose that the conductor f = (R : $\hat{R}$) is regular. If the residue class ring R/f and the class group C($\hat{R}$) are both finite, then R is a C-ring. Moreover, we study both v-Marot rings and C-rings under various ring extensions.

• 한국수산과학회지
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• 제52권6호
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• pp.596-604
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• 2019

Vibrio parahaemolyticus causes food poisoning, mainly via marine fisheries products. We investigated the virulence factors and drug resistance of V. parahaemolyticus isolated from fisheries products purchased from the Yeosu Fisheries Market. The isolates were identified using a variety of biochemical tests and the detection of toxR and hns gene. The presence of the virulence factor-encoding genes tdh and trh in the isolates was also investigated by PCR. The resistance of the isolates to 13 antibacterial agents was tested using the disc-diffusion method and carriage of β-lactamase genes and class 1 integrons by ampicillin-resistant isolates was investigated by PCR. Four of seventeen isolates identified as V. parahaemolyticus by biochemical tests produced a species-specific PCR band. Those isolates showed >98% 16S rRNA gene sequence homology with V. parahaemolyticus and only one isolate harbored the tdh gene. All of the V. parahaemolyticus isolates were resistant to ampicillin and amoxicillin; moreover, VPA0477, a class A β-lactamase gene, and class 1 integrons were detected. Therefore, V. parahaemolyticus from fisheries products represents a low risk to human health. Also, V. parahaemolyticus is likely to develop multidrug resistance because it has class 1 integrons.

• 대한수학회지
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• 제35권2호
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• pp.399-422
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• 1998

A useful method of proving the finite decidability of an equationally definable class V of algebras (i.e., variety) is to prove the decidability of the class of finite directly indecomposable members of V. The validity of this method relies on the well-known result of Feferman-Vaught: if a class K of first-order structures is decidable, then so is the class {$\prod$$_{i}$＜n/ $A_{i}$│ $A_{i}$ $\in$ X (i < n), n $\in$ $\omega$}. In this paper we show that the converse of this does not necessarily hold.d.d.

• 대한치과의사협회지
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• 제13권5호
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• pp.415-416
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• 1975

1. The author have had a case of class V and class Ⅲ combined carious lesion extended on to root surface of upper right lateral incisor. 2. The patient was 40 years old female. 3. After routine root canal treatment of the tooth, the gingival flap was made by vertical incision on gingival tissue between distal surface of upper right lateral incisor and mesial surface of upper right canine. 4. Cavity preparation and amalgam filling on the carious lesion were performed and the flap was sutured.

• 전기의세계
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• 제20권4호
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• pp.5-11
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• 1971

This is a study on the insulation methods of home appliances and wiring devices proper to the new electric distribution system, primary side is 22.9/13.2KV, 3 phase 4 wire multigrounding system and secondary side is 380/220V, 3 phase 4 wire common neutral system. 1800V is determined as the electrical insulation voltage of the functional insulation because the abnormal voltage rise of the neutral line is 1300V. In the case of the functional insulation faults, the following safety methods will be suggested to protect the accidental faults: (a) class I appliance (accessible metal part is earthed), (b) class II appliance (doublly insulated), (c) class III appliance (operates at low voltage source). The mechanisms of the wiring devices are not improved to guarantee for the harmful electric shock but also the electrical insulation voltage is rised to 2000V.

• 한국전자파학회논문지
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• 제22권8호
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• pp.805-808
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• 2011

본 논문에서는 220 V의 AC 전원을 공급받아 13.56 MHz의 RF 신호를 출력하는 고효율, 고출력 Class E 전력송신기를 설계하였다. 송신기는 AC-DC 변환기와 class E 전력 증폭기로 구성된다. 설계된 AC-DC 변환기는 220V/60 Hz의 가정용 전원을 공급 받아서 약 290 V의 DC 전압을 출력한다. 이때, AC-DC 변환기는 98.03 %의 매우 높은 변환 효율을 가진다. 변환 효율을 최대로 하기 위하여 별도의 DC-DC 변환기를 사용하지 않고, AC-DC 변환기의 출력 전압을 주 전력 증폭기의 드레인 바이어스 전압으로 사용하였다. 또한, class E 전력 증폭기의 전력손실을 최소화하기 위해 high-Q 인덕터를 제작하였다. 측정 결과, 13.56 MHz에서 동작하는 class E 전력 증폭기는 최대 출력 전력 323.6 Watt에서 84.2 %의 PAE(Power-Added Efficiency)를 가진다. AC-DC 변환기를 포함한 class E 전력 송신기는 323.6 Watt에서 82.87 %의 매우 높은 효율 특성을 나타낸다.

• 한국전자파학회논문지
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• 제26권6호
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• pp.593-596
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• 2015

본 논문은 무선전력전송 시스템에 활용할 수 있도록 낮은 드레인 전압에서 높은 효율을 가지는 class E 전력증폭기를 설계하였다. 붕괴전압이 40 V인 Si MOSFET을 이용하여 드레인 바이어스 전압이 12.5 V인 13.56 MHz 전력증폭기를 설계하였다. 출력 전력 및 효율을 개선하기 위하여 품질계수가 우수한 솔레노이드 인덕터를 제작하여 출력 정합회로에 사용하였다. 발진 방지와 간단한 회로 구성을 위하여 인덕터와 저항으로 입력 정합회로를 구성하였다. 측정 결과, 제작된 전력증폭기는 13.56 MHz에서 38.6 dBm의 출력전력과 16.6 dB의 전력이득, 그리고 89.3 %의 높은 전력부가효율을 보였다.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권3호
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• pp.73-76
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• 2003

In modern EHV (Extra High Voltage) class GCBs (Gas Circuit Breakers), the interruption capability for SLF (Short Line Fault) is one of the most important aspects of performance required for GCBs. Up to now, the SLF interruption capability of EHV class GCBs was partially assisted by the adoption of capacitors able to decrease the dV/dt of the TRV (Transient Recovery Voltage), particularly the TRV on the line side. This paper describes the technique to increase the SLF interruption capability of EHV class GCBs as well as the procedure to develop capacitorless l70kV 50kA GCB.

• 한국통신학회논문지
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• 제40권1호
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• pp.9-15
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• 2015

S급 전력 증폭기 응용을 위한 CMOS 대역 통과 델타 시그마 변조기(BPDSM)와 캐스코드 E급 전력 증폭기를 설계 및 제작 하였다. 대역 통과 델타 시그마 변조기는 1 GHz의 샘플링 주파수로 250 MHz의 입력 신호를 펄스폭 변조 방식의 디지털 신호로 변조하며 양자화 잡음을 효과적으로 제거하였다. 대역 통과 델타 시그마 변조기는 25 dB의 SQNR을 가지며 1.2 V 전원 전압에서 24 mW의 전력을 소비한다. 캐스코드 E급 전력 3.3V 전원에서 동작하며 최대 18.1 dBm의 출력 전력을 가지며 25%의 드레인 효율을 보였다. 두 회로 모두 동부 0.11 um RF CMOS 공정으로 제작되었다.

• Geomechanics and Engineering
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• 제36권1호
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• pp.51-69
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• 2024

Currently, composite lining mountain tunnels in China are generally classified based on the [BQ] method for the surrounding rock grade. Increasingly, tunnel field construction is replicated indoors for scale down model tests. However, the development of analogous materials for model tests of composite lining tunnels with different surrounding rock grades is still unclear. In this study, typical Class III and V surrounding rock analogous materials and corresponding composite lining support materials were developed. The whole processes of excavation-support dynamics of the mountain tunnels were simulated. Data on the variation of deformations, contact pressures and strains on the surrounding rock were obtained. Finally, a comparative analysis between model tests and numerical simulations was performed to verify the rationality of analogous material development. The following useful conclusions were obtained by analyzing the data from the tests. The main analogous materials of Class III surrounding rock are barite powder, high-strength gypsum and quartz sand with fly ash, quartz sand, anhydrous ethanol and rosin for Class V surrounding rock. Analogous materials for rockbolts, steel arches are replaced by aluminum bar and iron bar respectively with both shotcrete and secondary lining corresponding to gypsum and water. In addition, load release rate of Class V surrounding rock should be less than Class III surrounding rock. The fenestration level had large influence on the load sharing ratio of the secondary lining, with a difference of more than 30%, while the influence of the support time was smaller. The Sharing ratios of secondary lining in Class III surrounding rock do not exceed 12%, while those of Class V surrounding rock exceed 40%. The overall difference between the results of model tests and numerical simulations is small, which verifies the feasibility of similar material development in this study.