• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.425-431
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• 2020

The market for small unmanned aerial vehicles (SUAVs) is growing rapidly as technology advances and makes it possible to use them in various fields. However, due to the rapid increase in small drones, breakdowns, collisions and falls are also increasing year by year, and technologies for reducing accident and securing safety are being actively researched. In particular, the application of a fault tolerance system to cope with unexpected failures during flight is essential. According to data released by the US Department of Defense, accidents caused by errors in flight control computers account for about 28% of all accidents. This paper describes the proposal of flight control computer system's dual structure design to tolerate flight control system failure.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.158-161
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• 2004

In order for better management of a medical linear accelerator, the records of the operational failures of Varian CL2100C over ten years were analyzed. The failures were classified according to the involved functional subunits and each class was rated into three levels depending on operational conditions. The relationship between the failure rate and working ratio was investigated. Among the recorded failures ( total 587 failures), the most frequent failure, which was 20% of the total. was observed in the parts related to the collimation system including monitor chamber. Regrading to the operational conditions, the 2nd level of failures, that temporally interrupted treatments, was the most frequent. The 3rd level of failures, that interrupted treatment for more than several hours, was mostly caused by the accelerating subunit. The average life-time of a Klystron and Thyratron became shorter as the working ratio increased, which was 42 and 83% of the expected values, respectively. Recording equipment problems and failures in detail over a long period of time can provide a good knowledge of equipment function as well as the capability to forecast future failure. More rigorous equipment maintenance is required for old medical linear accelerator to avoid the serious failure in advance, and improve the patient treatment quality.

• Proceedings of the ESK Conference
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• 1993.10a
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• pp.65-75
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• 1993

원자력발전소에서 발생하는 고장정지 사건에 내포된 인적오류의 발생내용을 흥미있고 현장감 있게 묘사시킴과 동시에 종사원들의 인적오류를 저감시키기 위한 새로운 교육훈련방 법으로써 멀티미디어 기술의 사용을 고려하였다. 즉, 컴퓨터 환경하에서 숫자와 텍스트, 음 향 및 음성, 그래픽, 애니메이션, 화상 등의 미디어를 사용하여 인적오류로 인한 고장정지 사건발생의 내용을 전달하는 새로운 교육훈련 방법을 사용하는 것이다. 이를 위하여 고장정 지 사건과 관련한 원자력발전소 구성정보와 종사원의 활동정보를 입출력하기 위한 멀티미디어 인터페이스를 설계하였다. 설계는 멀티미디어 제공환경 구축과 인터페이스 운영논리 설정의 두단계로 구성한 절차에 따라 수행하였다. 멀티미디어 인터페이스는 원자력발전소 구성정보를 설계하여 저장시켜둔 퍼스널 컴퓨터 환경하에서 운영되며, 입력 및 출력의 두가지 인터페이스 를 갖는다. 입력 인터페이스는 인적 오류를 포함한 고장정지 사건의 발생내용을 숫자, 텍스트, 음성 미디어로 받아들여 출력 인터페이스에서 사용될 수 있도록 미디어 결합을 수행하고, 컴퓨터 저장장치에 저장하는 기능을 수행한다. 출력 인터페이스는 저장장치에 기록된 내용을 판독하여 고장정지의 진행경위와 인적오류의 발생내용을 숫자, 문자, 텍스트, 음성, 음향, 그래픽 애니메 이션, 정지화상으로 원자력발전소 종사원들에게 출력시켜 주는 기능을 수행한다. 멀티미디어 출력정보는 사용자가 CRT 화면에 제공되는 버튼 또는 Click Touch 메뉴를 사용함에 따라 이전, 이후의 출력정보로 전이할 수 있도록 하였다.상대적으로 중요한 검사 항목으로 나타났다. 또한 상대적 중요도 결과를 적용한 적성검사 성적이 적용하지 않은 적성검사 성적에 비해 비행성적에 대한 예측 능력이 좋은 것으로 평가되었다.al age)가 있다는 것을 의미하는 것이다. 한편, 생산현장에서는 자동화, 기계화가 진보되어 육체적인 노동이 경감된 결과, 중고령자라도 할 수 있는 작업이 많아지고 있다. 또, VDT (Visual Dislay Terminal) 작업과 같은 정보처리 작업의 수요가 증가하여 그 인재의 부족이 지적되고 있다. 따라서 중고령자의 기능을 조사하여 어떠한 작업에 적합한가를 판단하는 것이 중요한 과제로 되었다. 그러나 노동에는 많은 기능이 관여 하고, 그 내용에 따라서 요구되는 기능이 서로 다르기 때문에 노동적응능력의 기본적인 기능으로 보여지는 것에 좁혀서 작업능력의 연령증가 변화에 대하여다원적 평가를 하는 것이 실제적이라고 할 수 있다. 따라서 본 연구에서는 인간이 가지고 있는 다수의 기능중에서 수지교 치성과 연령증가와의 관계를 조사한다. 만약 연령증가 만으로 수지교치성을 평가 할 수 없는 경우에는 어떠한 요인이 수지기민성의 변화에 영향을 미치는가를 검토한다.t list)에서 자동적으로 사건들의 순서가 결정되도록 확장하였으며, 설비 제어방식에 있어서도 FIFO, LIFO, 우선 순위 방식등을 선택할 수 있도록 확장하였다. SIMPLE는 자료구조 및 프로그램이 공개되어 있으므로 프로그래머가 원하는 기능을 쉽게 추가할 수 있는 장점도 있다. 아울러 SMPLE에서 새로이 추가된 자료구조와 함수 및 설비제어 방식등

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.881-887
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• 2011

In this paper, age exploration of ${\bigcirc}{\bigcirc}$ anti-ship missiles which were deployed on RoKN ships were analysed using parametric estimation method. Additionally, Life distribution and failure pattern of ${\bigcirc}{\bigcirc}$ anti-ship missile were analysed by using field data such as collected inspection, fail, maintenance record for 6 years. Storage failure and MTBF of missile and components were analysed by using reliability analysis s/w Weibull++ v7. The results were compared with maintenance policy including periodic inspection and MTBF which were analysed during development phase. Finally, the suggested methodology using field data analysis of oo anti-ship missile will be applied on re-estabilishment of maintenance policy of ${\bigcirc}{\bigcirc}$ anti-ship missile for TLCSM(Total Life Cost System Management) effectively.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.503-509
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• 2011

ECC is a micro-mechanically designed cementitious composite which exhibits tightly controlled crack width and strain hardening behavior in uniaxial tension while using a moderate amount of reinforcing fiber, typically less than 2% fiber volume fraction. Recently, a variety of applications of this material ranging from repair and retrofit of structures, cast-in-place structures, to precast structural elements requiring high ductility are developed. In the present study, a retrofitting method using ECC reinforced with high strength rebar was proposed to enhance load-carrying capacity and crack control performance of deteriorated reinforced concrete (RC) beams. Six beam specimens were designed and tested under a four-point loading setup. The flexural test revealed that load-carrying capacity and crack control performance were significantly enhanced by the use of ECC and high strength rebar. This result will be useful for practical field applications of the proposed retrofitting method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1059-1068
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• 2016

The current operation method for the AVC (Automatic Vehicle Classification) equipment does not generate vehicle speed, traffic volume and vehicle type information when part of the sensors has failed. Inefficiency of current methods would not use the collected data from the normal sensor. In this study was conducted research on the calculating method at the traffic volume and vehicle speed in the sensor failure AVC equipment. The failure situation of the sensor was classified into 4 types. Calculating the traffic volume and vehicle speed information for each type, and accuracy of these informations were analyzed. Analysis results, traffic volume was possible to calculate a highly accurate value (accuracy: 100%, 98%, 97%). In the case of speed, the accuracy of the calculated speed value reaches a level that can be accepted sufficiently (RMSE value is less than 16.8). So, using the methodology proposed in this study are expected to be able to increase the operational efficiency of the AVC equipment.

• Proceedings of the ESK Conference
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• 1998.04a
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• pp.52-58
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• 1998

본 연구에서는 FTA 및 퍼지 FTA 방법을 프로그래밍이 용이한 규칙-기반 지식 표현 방법으로 프로그래밍을 설계하기 위한 것으로, FAT 방법에 필요한 전문지식들을 처 리하기 위하여 객체지향 접근방법으로 FTA 를 설계하였다. FTA의 구성요소들에 대한 자료구조는 다음과 같이 세가지 형태로 분류할 수 있다. 1)구성요소들의 자료구조가 확정적인 값으로 나타나는 경우 2)구성요소들의 자료구조가 부정확한 값으로 나타나는 경우 3)구성요소들의 자료구조가 확정적인 값 및 부정확한값으로 동시에 주어진 경우로 나타날 수 있다. 본 연구에서는 객체지향적 펴지 FTA 전문가 시스템(FFTAES: Fuzzy FTA Expert System)을 활용하여 세 번째 형태인 구성요소들의 자료구조가 확정적인 값 및 부 정확한 값이 동시에 주어진 경우를 정량적으로 고장안전진단을 실시할 수 있도록 설계 하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.513-521
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• 2006

Many studies have been conducted on the high tension bolt friction connection in the view of the field practice. Those effort, however, unfortunately have not been appropriately applied in the design specifications. Recently, particularly for steel bridges, rationalization of design takes greater attention from designers and hence, demand on rationalization of high tension connection becomes more significant. The purpose of this study is to suggest direction for the rationalization of high tension bolt connection and to also provide fundamental information for the improvement of the design specifications. In order to accomplish the purposes, the design specifications in Korea was analyzed and compared with other specification from abroad, and was studied one of the most important factors including slip coefficient, and the specifications on the size of bolt holes. The effect of over-sized bolt hole and the reduction of axial force on bolt was evaluated through the experimental studies on the slippage of the high tension bolt connections. Other research topics included herein includes the difference of slip coefficients, the effect of over-sized bolt holes and the gap distance of members, and the application of filler plate and corrosion protected bolts. From the research results, it is known that the specifications in Korea apply a constant slip coefficient with respect to the contacted surface conditions while various coefficients are available depending on the contacted surface conditions. Therefore, it is recommended that the specifications in Korea also develop and detail the slip coefficient which can appropriately take account of the variation of the contacted surface conditions. It is also suggested that the limitation abroad on the over-sized bolt hole may be applied for enhancing the effectiveness of construction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.7-14
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• 2006

The finite failure NHPP models proposed in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, we propose the Erlang reliability model, which can capture the increasing nature of the failure occurrence rate per fault. Equations to estimate the parameters of the Erlang finite failure NHPP model based on failure data collected in the form of inter-failure times are developed. For the sake of proposing shape parameter of the Erlang distribution, we used to the goodness-of-fit test of distribution. Data set, where the underlying failure process could not be adequately described by the existing models, which motivated the development of the Erlang model. Analysis of the failure data set which led us to the Erlang model, using arithmetic and Laplace trend tests, goodness-of-fit test, bias tests is presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.80-88
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• 2013

In currently developed engine condition monitoring systems, most field engine maintenance engineers have difficulties to use them in fields due to complexity, unpractical use, lack of understanding, etc. Therefore a practical usable engine condition monitoring system must be needed. This work proposes a practical performance condition monitoring of a small turbojet engine through comparing between the on-line performance monitoring data and the initial clean performance data calculated by the base engine performance model. Moreover the proposed monitoring system checks the gas path components' on-line health condition through comparing the component performance characteristics between the running engine represented as a deteriorated engine or a degraded engine and the base engine performance model represented as a clean engine. The proposed condition monitoring system is coded in a friendly GUI type program for easy practical application by a commercial tool, MATLAB/SIMULINK and LabVIEW.