• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.214-215
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• 2011

2대의 교류발전기 G1과 G2가 병렬운전 중 일 때 내부 기전력 E1, E2는 같은 위상이지만, 크기가 E1>E2로 될 때 두 발전기 사이에는 전위차가 있으므로 횡류 Ic가 흐르게 된다. 남강수력발전소는 주변압기(15MVA, 3.45/66kV) 한대에 수차발전기(7MVA) 2대가 병렬로 운전 중인데, 남강수력 제1호 수차발전기 AVR 시스템의 고장(RS 1기판)으로 G1 발전기의 내부 유기전압과 G2 발전기의 내부 유기전압에 차가 생기고, 이 양자의 차 전압을 전원으로 하여 발전기 G1과 G2를 환류하는 전류가 발생하여 발전 기동 중 비상정지 하였다. 본 논문에서는 고장원인 분석과정 및 AVR 시스템 보수 전 후 파형 비교 및 사고원인을 논하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1218-1219
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• 2011

본 논문은 KA555 Timer을 이용한 PWM회로로 구성된 아날로그 방식의 DC-DC Buck Converter와 AVR ATmega128를 이용한 PWM회로로 구성된 디지털 방식의 Buck Converter을 설계하여 각각의 특성을 비교 분석하였다. 제안된 컨버터들은 공통적으로 전원을 공급받아 전압분압회로를 통해 DC-DC Buck Converter의 PWM 제어회로부에 공급되며, 아날로그방식 컨버터의 제어부는 KA555 timer을 이용하여 구형파회로와 미분회로를 구성하고, 출력된 삼각파와 정현파를 KA555 timer을 이용하여 PWM파형으로 제어한다. 디지털방식의 컨버터는 AVR RISC 8-bit 마이크로프로세서 ATmega128을 이용하여 PWM 제어부를 구성하고 이를 LCD창을 통해 그 값을 확인할 수 있도록 설계하였다. 본 논문에서는 두 가지 방식의 제어부를 구성하여 제작 및 실험함으로써, 각각의 장단점을 비교하여 시스템 구성시 요구조건인 소형경량, 단가저감, 효율 등을 비교하여 그 상황에 맞는 설계가 가능할 것이다.

• The Plant Pathology Journal
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• 제25권3호
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• pp.256-262
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• 2009

The potential of. nonpathogenic Fusarium oxysporum strain Avr5, either alone or in combination with chitosan and Bion, for inducing defense reaction in tomato plants inoculated with F. oxysporum f. sp lycopersici, was studied in vitro and glasshouse conditions. Application Bion at concentration of 5, 50, 100 and $500{\mu}g$/ml, and the highest concentration of chitosan reduced in vitro growth of the pathogen. Nonpathogenic F. oxysporum Avr5 reduced the disease severity of Fusarium wilt of tomato in split plants, significantly. Bion and chitosan applied on tomato seedlings at concentration $100{\mu}g$ a.i./plant; 15, 10 and 5 days before inoculation of pathogen. All treatments significantly reduced disease severity of Fusarium wilt of tomato relative to the infected control. The biggest disease reduction and increasing tomato growth belong to combination of nonpathogenic Fusarium and Bion. Growth rate of shoot and root markedly inhibited in tomato plants in response to tomato Fusarium wilt as compared with healthy control. These results suggest that reduction in disease incidence and promotion in growth parameters in tomato plants inoculated with nonpathogenic Fusarium and sprayed with elicitors could be related to the synergistic and cooperative effect between them, which lead to the induction and regulation of disease resistance. Combination of elicitors and non-pathogenic Fusarium synergistically inhibit the growth of pathogen and provide the first experimental support to the hypothesis that such synergy can contribute to enhanced fungal resistance in tomato. This chemical could provide a new approach for suppression of tomato Fusarium wilt, but its practical use needs further investigation.

• 정보보호학회논문지
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• 제30권4호
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• pp.527-536
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• 2020

정보보호용 디바이스의 부채널 정보인 소비 전력 파형을 이용하면 내장된 비밀 키 뿐만 아니라 동작 명령어를 복구할 수 있음이 밝혀졌다. 최근에는 MLP 등과 같은 딥러닝 모델을 이용한 프로파일링 기반의 부채널 공격들이 연구되고 있다. 본 논문에서는 마이크로 컨트롤러 AVR XMEGA128-D4가 사용하는 명령어에 대한 역어셈블러를 구현하였다. 명령어에 대한 템플릿 파형을 수집하고 전처리하는 과정을 자동화하였으며 CNN 딥러닝 모델을 사용하여 명령-코드를 분류하였다. 실험 결과, 전체 명령어는 약 87.5%의 정확도로, 사용 빈도가 높은 주요 명령어는 99.6%의 정확도로 분류될 수 있음을 확인하였다.

• Journal of Chest Surgery
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• 제17권3호
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• pp.346-355
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• 1984

77 cases of Aortic Valve Replacement, which were composed of 64 rheumatic valvular heart disease and 13 combined congenital heart disease, were operated at Seoul National University Hospital for Aortic valvular disease during the period from June 1968 to December 1983. Among these 64 rheumatic aortic valvular heart disease cases, 8 patients were expired during and immediate after operation and overall mortality rate was 12.5%. For more precise remarks, these patients were divided into two periodic groups, 1st period [from 1968 to 1976] and 2nd [from 1977 to 1983] when annual open heart surgery were over 100 cases, and in 1st period three of four patients were died and in 2nd period five of sixty patients were died and its mortality rate was 8.3%. There were 12 cases of postoperative complication, which were 3 cases of remaining other valvular heart disease required MVR, 2 paravalvular leaks [one of them got Redo AVR], 4 thromboembolism or problem of anticoagulant therapy, 2 late death due to SBE with replaced valve failure and one functional AS with small sized valve. Operative death was affected by pump-time and aortic cross-clamping time, heart size, Ejection Fraction, LVEDP and symptom duration, and other many factors may influence the survival rate. Improved operative technique and myocardial protection and meticulous evaluation of the preoperative patient status will make the AVR safer.

• 전기학회논문지P
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• 제58권4호
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• pp.397-403
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• 2009

In this paper, an exciter current control of a synchronous generator for ships using a compound type digital automatic voltage regulator (DVAR) in order to provide a constant output voltage of the generator is presented. The compound type DAVR is composed of a controller part to adjust output voltage and an power source unit to supply power to the exciter. The controller part, which generates the PWM switching pattern via the PI controller, drives a power MOSFET for bypass to limit the SG's exciter current. The power source unit part is parallel connected to an output terminal of the generator through a reactor and a power CT. The residual magnetic flux of SG provides exciter current to the exciter through the reactor during the initial running or no load state and load current supplies field current to the exciter through the power CT during loading state. This paper confirmed an experiment to verify the validity of compound type DAVR system for controlling output voltage of synchronous generator.

• International Journal of Contents
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• 제3권4호
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• pp.36-40
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• 2007

Robot has been developed as something to help human beings, and robot will be very important field as an entertainment. This paper intends to contribute to developing golf robot as an entertainment using AVR ATmega Chips. It is believed that the entertaining robot giving a pleasure to human beings has good prospects for the rapid growth along with other robot industry. Golf robot developed in this paper has been developed for entertainment and has a similar sense in comparison with the real golf. This golf robot is represented in the way of putting the ball in the hall by hitting the ball just like the actual golf game and putting through making robot come close to the ball with the putting robot. This golf robot can playa game with several people like the actual golf if many putting robots can be used. It is, therefore, considered that the development of golf robots for entertainment using AVR has a high value of the golf robot as an entertainer on the ground that it can playa real golf.

• The Plant Pathology Journal
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• 제26권3호
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• pp.209-215
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• 2010

Plant pathogenic oomycetes, such as Phytophthora spp., are the causal agent of the most devastating plant diseases. During infection, these pathogens accomplish parasitic colonization of plants by modulating host defenses through an array of disease effector proteins. These effectors are classified in two classes based on their target sites in the host plant. Apoplastic effectors are secreted into the plant extracellular space, and cytoplasmic effectors are translocated inside the plant cell, through the haustoria that enter inside living host cell. Recent characterization of some oomycete Avr genes showed that they encode effector protein with general modular structure including N-terminal conserved RXLR-DEER motif. More detailed evidences suggest that these AVR effectors are secreted by the pathogenic oomycetes and then translocated into the host plant cell during infection. Recent findings indicated that one of the P. infestans effector, Avrblb2, specifically induces hypersensitive response (HR) in the presence of Solanum bulbocastanum late blight resistance genes Rpi-blb2. On the other hand, another secreted RXLR protein PexRD8 originated from P. infestans suppressed the HCD triggered by the elicitin INF1. In this review, we described recent progress in characterized RXLR effectors in Phytophthora spp. and their dual functions as modulators of host plant immunity.

• Journal of Chest Surgery
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• 제22권1호
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• pp.106-115
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• 1989

Clinical results with the xenograft cardiac valves were reviewed for 212 patients who underwent heart valve replacement from January 1981 to December 1987. One hundred and twenty-four Carpentier-Edwards k 88 Ionescu Shiley valves were used. Overall operative mortality was 11 out of 212[5.1%]: 5 out of 153[3.39o] for mitral valve replacement [MVR], 2 out of 34[5.9%] for aortic valve replacement [AVR], 0 out of 4[0%] for Tricuspid valve replacement [TVR], and 4 out of 21[19.1%] for double valve replacement [DVR;MVR+ AVR]. Two hundred and one operative survivors were followed up for a total of 824.3 patient-years [a mean 3.9*1.8 yrs], and the follow up was 78.1%. The linealized complication rates were 0.1% emboli / patient-year, 1.0% endocarditis/ patient-year and 2.2% overall valve failure / patient-year. A linealized rate of primary tissue failure was 0.7*/o/ patient-year. The actuarial survival rates including the operative mortality were 92*2.8% at 4 years and 85*4.3% at 7 years after surgery using the Xenograft cardiac valves. Probabilities of freedom from thromboembolism and overall valve failure were 73*11.0% and 69*2.4% at 7 years after surgery using the Xenograft cardiac valves respectively. The intrinsic durability of the Xenograft cardiac valves appears to be relatively well satisfactory over the long term [4 to 7 years] and the risk of failure appears well balanced by the advantages of a low incidence of thromboembolism and no mandatory anticoagulant therapy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.253-256
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• 1997

This paper describes a novel design method for compensating field time-constant of micro-synchronous machine so that its terminal flux can show the same characteristics as large-scale synchronous machine's. In addition to it, the suggested design method can determine the field time-constant regulator's parameters considered the nonlinearities of micro-synchronous machine such as saturation and loading effect. This method applied to 5kVA micro-synchronous machine, and the digital time-constant regulator with digital AVR were designed such that the short field time-constant, $T_{do}'=1.12\;sec$, can take on the large-scale synchronous machine time constant, $T_{do}'=1.47\;sec$. After determining the parameters of controllers, the real time digital time-constant regulator and digital AVR algorithm were implemented by using the PC with Penumum processor, and the usefulness of suggested real time digital time-constant regulator was verified by observing its good performance on the excitation of micro-synchronous machine.