• 대한치과교정학회지
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• 제28권2호
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• pp.175-187
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• 1998

본 연구는 치료후 빈번한 재발로 인해 치료에 어려움을 겪는 III급 부정교합의 치료후 예후를 예측하는 데 도움을 주고자, 교정치료후 관찰기간동안 측모와 교합이 양호한 상태로 유지된 안정군(Stable group, n=12)과 그렇지 않고 재발의 경향을 보인 재발군(Relapse group, n=13)으로 나누고, 초진시 계측항목을 이용한 t-test, 상관분석 그리고 판별분석을 시행한 결과 다음과 같은 결론을 얻었다. 1. 상하악골의 전후방적인 위치와 관계를 나타내는 항목인 SNA, SNB, ANB, Angle of convexity 그리고 APDI에서 두 군간 통계학적으로 유의성 있는 차이를 보여주지 않아(p>0.05) 두 군간 전후방적 인 골격 형태에 있어서는 차이가 나지 않음을 알 수 있었다. 2. 교합평면의 경사도와 관련된 항목인 Wits, AB to Occlusal plane angle 그리고 Occlusal plane to Mandibular Plane angle에서 두 군간 통계학적으로 유의성 있는 차이를 보여(p<0.05)재발군의 교합평면이 안정군에 비해 전하방으로 많이 경사져 있음을 알 수 있었다. 3. 상하치열관계를 나타내는 항목인 Overjet에서 안정군이 재발군에 비해 절대치로 더 커(p<0.01) 전후방 골격부조화에 의한 것이 아닐 경우 치열의 전후방부조화가 클수록 치료후 예후가 좋음을 알 수 있었다. 4. 상관분석결과 Overjet과 Occlusal plane to Mandibular plane angle만이 통계학적으로 유의성 있는 상관관계를 보여 주었다(p<0.001, p<0.01). 5. 판별에 기여도가 높은 3항목 즉 Overjet, AB to Occlusal paine angle 그리고 Articular angle을 이용한 판별식을 도출하였으며, 이를 이용할 때 본 연구에 사용한 표본의 88%를 올바르게 판별할 수 있었다.

• ETRI Journal
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• 제28권4호
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• pp.495-501
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• 2006

This paper presents a new CMOS fully-differential second-generation current conveyor (FDCCII). The proposed FDCCII is based on a fully-differential difference transconductor as an input stage and two class AB output stages. Besides the proposed FDCCII circuit operating at a supply voltage of ${\pm}1.5\;V$, it has a total standby current of $380\;{\mu}A$. The applications of the FDCCII to realize a variable gain amplifier, fully-differential integrator, and fully-differential second-order bandpass filter are given. The proposed FDCII and its applications are simulated using CMOS $0.35\;{\mu}m$ technology.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.903-906
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• 2003

In this paper, we proposed high slew-rate and low-power OP-AMP of the data driver for TFT-LCDs. Proposed OP-AMP contains newly developed rail-to-rail class-AB input circuit which enables the low-quiescent current and high slew-rate OP-AMP. The slew-rate and the quiescent current of the proposed OP-AMP are 31.2V/$\mu$sec and 5$\mu$A, respectively.

• Restorative Dentistry and Endodontics
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• 제25권2호
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• pp.243-253
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• 2000

The purpose of this in vitro study was to evaluate dentin bonding by two different dentin bonding systems(DBS) using acetone based primer or adhesive [All Bond 2(AB2), One Step(OS)] when they were applied by wet or dry bonding technique. Morphology of resin-dentin interface and hybrid layer thickness(HLT) were investigated using Confocal Laser Scanning Microscope(CLSM) and compared to shear bond strength(SBS). 72 extracted sound human molars were randomly divided into 4 groups of 18 teeth each - Group 1.(AW); AB2 by wet bonding. Group 2(AD); AB2 by dry bonding. Group 3.(OW); OS by wet bonding, Group 4.(OD); OS by dry bonding. In 6 teeth of each group, notch-shaped class V cavities(depth 2mm) were prepared on buccal and lingual surface at the cementoenamel juction(12 cavities per group). To obtain color contrast in CLSM observation, bonding resins of each DBS were mixed with rhodamine B and primer of AB2 was mixed with sodium fluorescein. Prepared teeth of each group were treated with AB2, OS, respectively according to the manufacturer's instructions except for dentin surface moisture treatment after acid etching. In group 1 and 3, after acid etching, excess water was removed with wet tissue(Kimwipes), leaving consistently shiny, visibly hydrated dentin surface. In group 2 and 4, dentin surface was dried for 10 seconds at 1 inch distance. The treated teeth were then packed with composite resin(${\AE}$litefil) and light-cured. 12 microscopic samples($60{\sim}80{\mu}m$ thickness) of each group were obtained after longitudinal section and grinding(Exakt cutting and grinding system). Morphological investigation of resin-dentin interface and HLT measurement using CLSM were done. For measurement of SBS, remaining 12 teeth of each group were flattened occlusally to remove all enamel and grinded to 500 grit SiC(Pedemet Specimen Preparation Equipment). After applying DBS on the exposed dentin surface, composite resin was applied in the shape of cylinder, which has 5mm diameter, 1.5mm thickness, and light cured. SBS was measured using Instron with a crosshead speed of 0.5mm/min. It was concluded as follows, 1. HLT of AW(mean: $2.59{\mu}m$) was thicker than any other group, and followed by AD, OW, OD in descending order(mean; 2.37, 2.28, $1.92{\mu}m$). Only OD had statistically significant differences(p<0.05) to AW and AD. 2. There were intimate contact of resin and dentin at the interface in wet bonding groups, but gaps or irregular interfaces were observed in dry bonding groups. 3. The length, diameter, density of resin tags were various even in the same group without significant differences between groups and lots of adhesive lateral branches were observed. 4. There were no statistically significant difference of SBS between AB2 and OS, but SBS of wet bonding groups were significantly higher(p<0.05) than dry bonding groups. 5. There were no consistent relationships between HLT and SBS.

• 대한수학회보
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• 제57권5호
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• pp.1205-1213
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• 2020

Let R be a commutative ring with 1 ≠ 0. In this paper, we introduce a subclass of the class of 1-absorbing primary ideals called the class of strongly 1-absorbing primary ideals. A proper ideal I of R is called strongly 1-absorbing primary if whenever nonunit elements a, b, c ∈ R and abc ∈ I, then ab ∈ I or c ∈ ${\sqrt{0}}$. Firstly, we investigate basic properties of strongly 1-absorbing primary ideals. Hence, we use strongly 1-absorbing primary ideals to characterize rings with exactly one prime ideal (the UN-rings) and local rings with exactly one non maximal prime ideal. Many other results are given to disclose the relations between this new concept and others that already exist. Namely, the prime ideals, the primary ideals and the 1-absorbing primary ideals. In the end of this paper, we give an idea about some strongly 1-absorbing primary ideals of the quotient rings, the polynomial rings, and the power series rings.

• Korean Journal of Mathematics
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• 제17권2호
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• pp.189-196
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• 2009

Let D be an integral domain, and let U be a group of units of D. Let $D^*=D-\{0\}$ and ${\Gamma}=D^*/U$ be the commutative cancellative semigroup under aU+bU=abU. We prove that $Cl(D)=Cl({\Gamma})$ and that D is a PvMD (resp., GCD-domain, Mori domain, Krull domain, factorial domain) if and only if ${\Gamma}$ is a PvMS(resp., GCD-semigroup, Mori semigroup, Krull semigroup, factorial semigroup). Let U=U(D) be the group of units of D. We also show that if D is integrally closed, then $D[{\Gamma}]$, the semigroup ring of ${\Gamma}$ over D, is an integrally closed domain with $Cl(D[{\Gamma}])=Cl(D){\oplus}Cl(D)$; hence D is a PvMD (resp., GCD-domain, Krull domain, factorial domain) if and only if $D[{\Gamma}]$ is.

• 전자공학회논문지
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• 제50권4호
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• pp.43-51
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• 2013

디지털 보청기에 적합한 저전력 3차 델타-시그마 모듈레이터를 설계하였다. 적분기의 출력 스윙을 최소화 하도록 모듈레이터 구조의 계수를 최적화하고, AB급 출력단을 갖는 2단 연산증폭기와 switched-capacitor 구조를 사용하여 전력소모를 최소화 하였다. 본 모듈레이터는 130nm CMOS 공정을 이용하여 제작되었으며, 샘플링 주파수가 3.2MHz일 때 100Hz-10kHz의 신호대역에서 79dB의 SNR(Signal-to-Noise Ratio)이 측정되었다. 전력소모는 1.2V 전원전압에서 $60{\mu}W$에 불과하며 A/D 변환기 코어의 크기는 $0.53mm{\times}0.53mm$ 이다.

• 한국정보통신학회논문지
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• 제9권2호
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• pp.262-267
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• 2005

본 논문에서는 여러 가지 효율 개선 방법 중에서 Doherty Amplifier에 관해 논하였다. 간단한 회로를 이용하여 하나의 PEP 180w급 LDMOS를 사용하여 효율성과 선형성 개선에 관한 성능분석을 하였다 제작된 Doherty Amp의 성능을 검증하기 위해 Balanced Class AB Amplifier와 성능을 비교하였다. 실험결과 peaking Amp의 $V_gs.P$가 1.53V일 때 효율이 최대 11.6$\%$ 이상 증가되었으며 매뉴얼로 gate bias 조절을 통하여 선형성 개선의 최적 bias point를 찾은 후 WCDMA 4fA에서는 $V_gs.P$가 3.68V일 때 IMSR (InterModulation to Signal Ratio)이 최대 3.34dB가 증가됨을 보였다. 특히 1.53V로 peaking amp의 bias point를 맞추게 되면 출력 전력 434Bm에서 -324Bc 이하의 IMSR과 탁월한 효율 증가를 얻을 수 있었다.

• 대한치과교정학회지
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• 제31권4호
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• pp.439-445
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• 2001

본 연구의 목적은 기능성 및 골격성 전치부 반대교합 환자에 대한 형태학적 차이점을 비교하는 것이다. 전치부의 기능성 반대교합을 보이는 28증례와 골격성 반대교합을 보이는 31증례를 각각 실험군과 대조군으로 삼았다. 실험군과 대조군의 평균연령은 $9.6{\pm}1.8$세와$9.9{\pm}1.9$세이었다. 측모두부방사선 사진을 촬영하였으며 두 군간의 형태학적 차이를 비교하기 위해 49개 항목에 대한 계측 및 통계학적인 분석을 시행하였다. 계측항목 중 cranial deflection, maxillary depth, ANB, convexity, NPo-AB, APDI, Mx 1-SN, Mx 1-NA angle, Mx 1-NA, Md 1-NB angle and Md 1-NB에서 통계학적인 유의차가 나타났다. 실험군에서는 Class III로의 성장 가능성, 상악골의 전방위치, 상하악골간의 전후방적 부조화 감소, 상악 중절치의 후퇴, 직립 및 하악 중절치의 전돌, 순측경사를 보였다.

• ETRI Journal
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• 제39권1호
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• pp.51-61
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• 2017

This paper demonstrates a systematic approach for the design of broadband, high efficiency, high power, Class-AB RF amplifiers with high gain flatness. It is usually difficult to simultaneously achieve a high gain flatness and high efficiency in a broadband RF power amplifier, especially in a high power design. As a result, the use of a computer-aided simulation is most often the best way to achieve these goals; however, an appropriate initial value and a systematic approach are necessary for the simulation results to rapidly converge. These objectives can be accomplished with a minimum of trial and error through the following techniques. First, signal gain variations are reduced over a wide bandwidth using a proper pre-matching network. Then, the source and load impedances are satisfactorily obtained from small-signal and load-pull simulations, respectively. Finally, two high-order Chebyshev low-pass filters are employed to provide optimum input and output impedance matching networks over a bandwidth of 100 MHz-500 MHz. By using an EM simulation for the substrate, the simulation results were observed to be in close agreement with the measured results.