• 에너지공학
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• 제24권1호
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• pp.17-23
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• 2015

전기식 출입문 시스템은 철도차량 영업운전에 영향을 주는 가장 중요한 시스템 중의 하나이다. 도시철도차량의 출입문은 승객들의 승하차를 담당하는 장치로써 고장이 발생할 경우 승객의 안전과 직접적인 영향을 미치기 때문에 열차운행에 영향을 미치는 중요한 장치이다. 최근에는 전기식 출입문 시스템의 신뢰도 목표값을 철도운영자가 철도차량 설계와 제작을 위한 발주사양 기술 요구조건에 포함하는 경향이 있으며, 차량 제작자는 제작시 발주사양기술 요구조건에서 철도운영자가 제시한 전기식 출입문 시스템의 신뢰도 목표값을 만족시켜야 하고, 철도운영자는 유지보수 데이터를 기반으로 공급자의 신뢰도 목표값 달성여부를 확인하고 승인하여야 한다. 본 연구에서는 전기식 출입문 시스템의 유지보수 현장 데이터를 수집하여 신뢰도를 미니탭 통계프로그램으로 분석하였다. 현장 데이터를 적용한 신뢰도 분석은 철도차량에 대한 새로운 유지보수 정책이나 유지보수 주기를 바꾸는데 매우 유용할 것이다.

• 한국철도학회논문집
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• 제10권5호
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• pp.527-532
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• 2007

본 논문은 철도신호에서 사용되는 이중계제어장치의 전원공급방식에 대하여 상수고장률을 기반으로 하는 평균고장률에 의한 설계와 신뢰도함수에 의한 설계방안을 제안한다. 일반적으로 시스템 운명이전에 신뢰도 요구사항 만족을 위한 시스템의 신뢰도 예측은 RBD모델을 사용하였다. 하지만 이중계제어장치와 같이 여분을 갖는 시스템의 신뢰도를 RBD와 같은 조합모델에 의해 정확한 신뢰도를 모델링하기에 부적합하다. 따라서 본 논문에서는 다중계구조 제어기의 설계과정에서 단순조합모델에 의한 설계방식 선정보다는 결함발생에 대한 여분구조의 모델링을 통한 설계방식 선정이 보다 정확한 신뢰도를 갖는 시스템구축을 가능하게 하며, 운영중에 발생되는 유지보수비용 및 고장으로 인한 손실비용의 효율화를 위해 필요함을 입증한다.

• 한국정밀공학회지
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• 제33권6호
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• pp.499-508
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• 2016

This paper describes a study of performance prediction of an electric propulsion system for multirotor UAVs. The electric propulsion system consists of motors, propellers, batteries and speed controllers, and significantly affects performance characteristics of the platform. The performance of the electric propulsion system for multirotor UAVs was predicted using an analytical model derived from the characteristics of each component, operation experiments and statistical analyses. Ground performance tests and endurance flights were performed to verify the reliability of the proposed performance prediction method. A quadrotor platform was designed to demonstrate the parcel delivery service used in the endurance flight. From the result of verification tests, it was confirmed that the proposed method has a good agreement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2488-2511
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• 2015

Data redundancy has high impact on Wireless Sensor Network's (WSN) performance and reliability. Spatial and temporal similarity is an inherent property of sensory data. By reducing this spatio-temporal data redundancy, substantial amount of nodal energy and bandwidth can be conserved. Most of the data gathering approaches use either temporal correlation or spatial correlation to minimize data redundancy. In Collective Prediction exploiting Spatio Temporal correlation (CoPeST), we exploit both the spatial and temporal correlation between sensory data. In the proposed work, the spatial redundancy of sensor data is reduced by similarity based sub clustering, where closely correlated sensor nodes are represented by a single representative node. The temporal redundancy is reduced by model based prediction approach, where only a subset of sensor data is transmitted and the rest is predicted. The proposed work reduces substantial amount of energy expensive communication, while maintaining the data within user define error threshold. Being a distributed approach, the proposed work is highly scalable. The work achieves up to 65% data reduction in a periodical data gathering system with an error tolerance of 0.6℃ on collected data.

• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1021-1027
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• 2007

A construction noise is the main reason for people's petition among the pollution. The purpose of this study is to develop the noise prediction program to see the level of the noise on the construction site more accurately. For this purpose, the database of the power level on the various equipments was made. The noise reduction by distance and the noise reduction by diffraction of barrier were mainly considered and calculated. The simple noise prediction program will provide the information about proper height and length of the potable barrier which satisfies noise criteria of the construction sites from a construction planning stage. To investigate the reliability of this program, the predicted data was compared with the measured data. An average of difference between measured data and predicted data is $0.1{\sim}2.8\;dB(A)$ and a coefficient of correlation is about $0.85{\sim}0.95$.

• Journal of Welding and Joining
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• 제21권3호
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• pp.92-98
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• 2003

This paper describes the numerical prediction of the thermal fatigue life of a $\mu$BGA(Micro Ball Grid Array) solder joint. Finite element analysis(FEA) was employed to simulate thermal cycling loading for solder joint reliability. Strain values, along with the result of mechanical fatigue tests for solder alloys were then used to predict the solder joint fatigue life using the Coffin-Manson equation. The results show that Sn-3.5mass%Ag solder had the longest thermal fatigue life in low cycle fatigue. Also a practical correlation for the prediction of the thermal fatigue life was suggested by using the dimensionless variable ${\gamma}$, which was possible to use several lead free solder alloys for prediction of thermal fatigue life. Furthermore, when the contact angle of the ball and chip has 50 degrees, solder joint has longest fatigue life.

• 대한기계학회논문집A
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• 제33권8호
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• pp.739-744
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• 2009

Rail-pad is an important and readily replaceable component of a railway track, as it is the elastic layer between the rail and the sleeper. Characteristics and useful lifetime prediction of rail-pad was very important in design procedure to assure the safety and reliability. In this paper, the degradation of rail pad properties as a function of their in-service life is studied with a view of developing a technique for predicting the optimum period of track maintenance with regard to pad replacement. In order to investigate the useful lifetime, the accelerate test were carried out. Accelerated test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the acceleration test, several useful lifetime prediction for rail-pads were proposed.

• 한국통신학회논문지
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• 제39A권10호
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• pp.616-618
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• 2014

본 논문에서는 RF SAW 듀플렉서에 대하여 가속수명시험을 설계하고 수명예측방법에 대하여 제시하였다. 가속수명시험설계 시 가속스트레스는 RF 입력전력으로 정하고 삽입손실이 0.5[dB] 증가하는 기간을 듀플렉서의 수명으로 정의하였다. 듀플렉서의 수명예측결과는 $85^{\circ}C$ 주위온도와 30[dBm] RF입력전력에서 약 82,900시간으로 추정되었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.425-426
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• 2016

본 논문에서는 Delay Tolerant Networks(DTNs)에서 노드의 속성 정보를 Markov Chain으로 분석하여 노드의 이동 경로를 예측하는 알고리즘을 제안한다. 기존 DTN에서 예측기반 라우팅 기법은 노드가 미리 정해진 스케줄에 따라 이동하거나 노드 간 접촉정보와 같은 추가 정보가 필요하다. 이러한 네트워크에서는 추가적인 정보가 없는 경우 노드의 신뢰성이 낮아진다. 본 논문에서 제안하는 알고리즘은 노드의 속성 정보 중 노드의 속도와 방향성을 상태로 맵핑한 후, Markov chain을 이용하여 확률전이 매트릭스를 생성하여 노드의 이동 경로를 예측하는 알고리즘이다. 주어진 모의실험 환경에서 노드의 이동 경로 예측을 통해 중계 노드를 선정하여 라우팅 함으로써 메시지 전송률이 증가하고 전송 지연 시간이 감소함을 보여주고 있다.

• 동서간호학연구지
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• 제12권1호
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• pp.5-13
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• 2006

Purpose: This research has been conducted in order to confirm the major factors that prediction organizational commitment in registered nurses. Method: The subjects were 350 registered nurses from 3 hospitals in Seoul. The sample for data collection consisted of 329 useable questionnaires (94% overall return rate) for 2 weeks. The Instrument tools utilized in this study were organizational commitment scale, empowerment scale, job stress scale and job satisfaction scale and thoroughly modified to verify validity and reliability. The collected data have been analyzed using SPSS 11.0 program. Three outliers which were bigger than 3 in absolute value were found, so after taking them off, Multiple Regression was used for further analysis. Result: The major factors that prediction organizational commitment in registered nurses were job satisfaction, empowerment, age and unit experience, which explained 51.9% of organizational commitment. Conclusion: It has been confirmed that the regression equation model of this research may serve as a organizational commitment prediction factors in Registered Nurses.