• 자동차안전학회지
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• 제12권2호
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• pp.21-26
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• 2020

This paper presents an anti-lock braking system for commercial vehicles with pneumatic brake system by using slip ratio. By virtue of system reliability, most commercial vehicles adopt pneumatic brake system. However, pneumatic brake systems control is more difficult than hydraulic systems due to a longer time delay and the system nonlinearity. One of the major factors in generating braking forces is the wheel slip ratio. Accordingly, the proposed ABS strategy employs the slip ratio threshold-based valve on/off control. This threshold-based algorithm is simple but effective to control the pneumatic brake systems. The control performance of the proposed algorithm has been validated via simulation studies using MATLAB/Simulink and Trucksim. The results show ABS by using slip ratio reduces the braking distance and improves vehicle control.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.418-420
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• 2003

The fault current limiting characteristics at the initial fault time for flux-lock type high-Tc superconducting fault current limiter(SFCL) were investigated. The amplitude of initial fault current of the flux-lock type SFCL was dependent on the inductance ratio of coil 1 and 2. After fault current limiting mode was analyzed, we compared the calculated value with the experimental one for the initial fault current. The effect of initial fault current due to the inductance ratio of coil 1 and 2 on fault current limiting characteristics was discussed.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 봄 학술발표논문집 Vol.30 No.1 (A)
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• pp.184-186
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• 2003

실시간 운영체제는 태스크 수행의 논리적인 정확성뿐만 아니라 시간적인 정확성도 만족하는 스케줄링을 하는 운영체제이다. 태스크가 공유자원을 사용할 때 가용한 자원이 없으면 그 자원을 얻기 위해 기다리는 Pending 상태가 된다. 이러한 상태가 일반적인 상황에서 발생하면 스케줄러에 의해서 적절하게 관리되지만 인터럽트 상태나 시그널 상태와 같은 특수한 경우에 발생하면 데이터의 충돌이나 심지어 실시간 운영체제가 붕괴되는 상황이 발생할 수 있다. 이를 해결하기 위해 상용 RTOS 에서는 개발자가 ISR 에서 이러한 상황이 발생하지 않도록 주의 깊게 사용할 것을 경고하며, 커널 내부적으로는 복잡한 처리과정을 거쳐 해결할 수 있다. 본 논문에서는 이러한 상황이 발생할 가능성이 있을 때 PENDING LOCK/UNLOCK 함수를 사용하여 개발자에게 개발상의 편의를 제공하고, 실시간 운영체제의 안정성 및 신뢰성을 보장할 수 있도록 설계 및 구현한 내용을 기술한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.191-193
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• 2005

Flash memories are one of best media to support portable computer's storages. However, we need to improve traditional data management scheme due to the relatively slow characteristics of flash operation as compared to RAM memory. In order to achieve this goal, we devise a new scheme called Flash Two Phase Locking (F2PL) scheme for efficient data processing. F2PL improves transaction performance by allowing multi version reads and efficiently handling slow flash write/erase operation in lock management process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.709-710
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• 2008

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.432-434
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• 2006

We investigated the quench characteristics of a flux-lock type superconducting fault current limiter (SFCL) according to the number of the superconducting elements at the subtractive polarity winding of a transformer. The flux-lock type SFCL consists of the transformer with a primary winding and two secondary windings connected in parallel, and the superconducting element was connected with secondary winding in series, respectively. The applied voltage at that tin was 200V. when two superconducting elements of the secondary winding was connected in parallel, the peak lie current increased up to 99A, while that flowing in a superconducting element in conventional flux-lock type SFCL showed 50A under the same conditions, the impedance of secondary winding under the same situation showed the opposite behavior. This enabled the parallel structure to be easy to increase the capacity of power system, in the meantime, The quench between two superconducting elements in the SFCL with two secondary windings connected in parallel was achieved simultaneously. While the quench-starting point was slightly different in the SFCL with two superconducting elements connected in series. We found that the parallel connection between the secondary windings increased the power capacity and let quench characteristics improve through their mutual linkage.

• 한국항공우주학회지
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• 제37권5호
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• pp.502-510
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• 2009

레이저 관성항법장치는 링 레이저 자이로와 가속도계로 구성되어 있다. 링 레이저 자이로는 링 레이저 자이로 내부의 레이저 공진기에 장착된 반사경의 후방산란으로 인하여 0.1deg/sec 이하의 각속도가 측정되지 않는 lock-in 영역이 존재하기 때문에 이를 제거하기 위해서 Dither 운동이라는 정현파 각속도 운동을 몸체에 가한다. 이러한 Dither 운동은 레이저 관성항법장치가 정상동작하는 경우 항상 RLG/가속도계 측정치에 포함되어 나타난다. 이러한 레이저 관성항법장치의 특징을 이용하여 본 논문에서는 RLG/가속도계 측정치를 실시간으로 FFT를 수행하여 Dither 운동이 측정치에 포함되어 있는 가를 실시간으로 감시하여 레이저 관성항법장치의 고장을 검출하는 방법을 제안하였으며 정지상태 시험 및 차량탑재 시험을 통해 유용성을 검증하였다.

• 한국항행학회논문지
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• 제22권1호
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• pp.43-47
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• 2018

최근 우리나라에서는 자전거 열풍이 불고 있으며 자전거는 가까운 거리의 이동수단이 되었다. 또한 사물인터넷에 대한 관심이 집중되어 있고 최근에 사물인터넷에 많은 관심이 집중되고 있다. 하지만 이와 같은 자전거 시장의 발전에도 불구하고 자전거 거치대는 이렇다 할 발전이 없는 점이 현실이며 여전히 잠금을 위해서는 별도의 자물쇠가 필요하다는 단점이 있다. 이와 관련해서 몇 가지 문제점을 발견하여 해결 하려고 한다. 본 논문에서는 현재의자전거 거치대가 갖는 문제점인 방치 자전거의 수거 또는 회수를 도울 수 있도록 하며 앱과 아두이노를 통신하여 자전거 거치대의 위치 및 사용여부를 실시간으로 제어 할 수 있는 시스템을 구현하였고 사용자에게 도움이 되는 스마트 거치대를 제공한다. 또한 지인, 타인과의 공유하는 서비스를 제공하여 사물인터넷 기반의 공유경제 시스템을 확립하고, 실시간 서비스 제공으로 사용자 편의성을 높일 수 있는 방안에 대하여 제시하고자 한다.

• 대한치과보철학회지
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• 제30권1호
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• pp.1-14
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• 1992

The purpose of this study was to evaluate the accuracy of reproduction of stone casts made from complete-arch impressions using different trays. The trays used were : 1) nonperforated custom tray, 2) perforated custom tray, 3) nonperforated Rim-Lock tray, 4) perforated stock tray. Impressions were made from an dentulous acrylic resin model with metal inserts in first premolars and second molars. Transverse distance, sagittal distance and diagonal distance were measured using 4 landmarks. Measurements were made by using 3 dimensional measuring machine. The impression material used was an addition silicone. Impressions were poured at once with a Type IV dental stone. Data were analyzed using ANOVA and student t-test with a sample size of five. The results were as follows : 1. There were statistical differences in amount of dimensional change in according to the tray types. In amount of mean dimensional change, perforated custom tray was the first smallest, nonperforated custom tray was the second, nonperforated Rim-Lock tray and perforated stock tray were the largest. 2. There were statistical differences in amount of dimensional change between nonperforated custom tray and nonperforated Rim-Lock tray, and between perforated custom tray perforated stock tray. 3. There were satistical differences in amount of dimensional change between nonperforated custom tray and perforated custom tray, but there was not a statistical difference between nonperforated Rim-Lock tray and perforated stock tray. 4. There was not a statistical difference in amount of dimensional change between upper and lower arch in all tray types.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.467-470
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• 2006

Superconducting fault current(SFCLs) are expected to improve not only reliability but also stability of real power systems. The analysis on the single line-to-ground fault current of the integrated three phase flux-lock type SFCL, which consists of three flux-lock reactor wound on an iron core in each single phase and three YBCO thin films, was investigated in current limiting operating characteristics. We compared additive polarity winding with the subtractive one in the flux lock reactor. Its turns ratio each phase between the primary and the secondary coils is 63:42. When a single line-to-ground fault occurred in any phase, the peak value of line current in the fault phase of the additive polarity winding increased up to 31.44[A] during first-half cycle. On the other hand, the peak value in the subtractive polarity winding increased up to 81.77[A] under the same conditions. This is because the current flow between the primary and the secondary windings becomes to be additive or subtractive in each winding direction. We confirmed that the current limiting behavior in the additive polarity winding was more effective for a single-line-to ground fault.