Earticle

장시간 저장되어 있다가 사용되는 일회성 군수장비 시스템의 경우, 저장 시간이 지남에 따라 저장신뢰도에 변화가 발생하게 된다. 이에 사용시점이 도래하였을 때 제품 사용에 있어 저장신뢰도가 중요한 품질특성으로 작용하게 되며, 기존의 연구들은 저장신뢰도 향상을 위하여 최적의 정기검사주기 산출을 위한 연구에 초점이 맞춰져 있었다. 본 연구에서는 정기검사주기 뿐 아니라 설계신뢰도를 포함한 분석을 통해 융합적인 관점에서 저장신뢰도에 두 인자가 얼마나 영향을 미치는지 분석을 수행하였다. 이를 위해 일회성 시스템의 대표적인 제품인 유도탄에 기존의 Martinez 저장신뢰도 결정모델을 적용하여 각각 설계신뢰도와 정기검사주기가 미치는 정량적인 효과에 대하여 분석을 수행하였다. 분석 결과를 통해, 현 제품의 설계신뢰도 범주 내에서는 설계신뢰도보다는 정기검사주기 관리가 저장신뢰도 향상에 더 중요한 요인이라는 것을 확인해 볼 수 있었다.

In the case of a one-shot logistic equipment system that has been stored for a long time, reliability changes with the passage of time. Therefore, when the time comes to use, the storage reliability of the product is an important quality characteristic, and the existing studies have focused on the research for calculating the optimal period inspection cycle to improve the storage reliability. In this study, we analyzed the influence of the two factors on the storage reliability at the convergence point by analyzing the design reliability as well as the periodic inspection cycle. To do this, we applied the existing Martinez storage reliability model to the missile, a representative product of a one-shot system, and analyzed the quantitative effects of the design reliability and the periodic inspection cycle. From the results of the analysis, it was confirmed that the maintenance of the periodic inspection cycle is more important for the improvement of the storage reliability than the design reliability in the design reliability category of the current product.

본 연구는 신경망 알고리즘 및 반응표면법을 이용하여 부품의 최적화 설계 치수를 예측하고, 예측된 데이터의 신뢰성을 상호 검증하는 하는 데 있다. 부하가 변할 때, 부품의 치수를 변화시켜 가며 응력 및 변형량의 변화를 해석 데이터로 수집하여 반응표면법 및 신경망학습에 이용하였다. 이를 위해 임의의 조건에서 반응표면법으로 최적화 설계를 수행하고, 동일한 조건에서 신경망 알고리즘의 예측결과와 비교하였다. 그 결과 최대 3.0%의 치수 오차를 보이는 것으로 나타났다. 또한 검증을 위해 반대로 동일한 하중 및 치수 조건에서 유한요소해석을 통해 응력 및 처짐량을 구해 반응표면법 및 신경망학습의 결과를 비교하였으며, 이때 4.2%의 오차를 보였다. 이는 부품의 사양 변경 시 최적화 설계를 위해 반응표면법 및 신경망을 이용할 수 있으며 신뢰성이 있음을 알 수 있었다. 특히 신경망 학습을 통해 보다 효과적으로 최적화 설계가 가능함을 확인할 수 있었다.

본 논문은 해외 공장에서 제조된 부품의 품질 수준을 파악하고 시장 불량에 직결되는 위험인자를 발굴, 불량 발생원인 파악 및 고장 분석을 개선된 프로세스로 수행한다. 또한 전기 제품내의 요소부품을 규정, 고질불량 문제 해결을 위해 TFT(Task Force Team)를 구성하는 방법과 절차를 소개한다. 특히 해외공장은 간단하고 명료 한 품질 시스템이 요구되므로 국내공장에서 확실하게 검증된 방법을 적용해야 만이 실수가 없다. 해외공장의 특수 성 때문에 지역별 품질경영 시스템이 동반되어야 하고 품질지수를 높일 수 있는 신뢰성 성장 설계를 하도록 노력 해야 한다. 개발 단계별 차기 진행여부에 대한 결정이 필요하고 중요도, 시장상황에 맞게 판정해야한다. 최고의 제 품은 사람으로부터 나오게 되므로 협력업체와의 부품 품질관리는 양 사간 공동의 관심이 필요하고 불량품 개선 후 재발되지 않는 유지관리 시스템을 명문화하여 정착시킬 필요가 있다.

This paper identifies the quality level of parts manufactured in overseas factories, discovers risk factors directly linked to market defects, identifies the cause of defects, and conducts fault analysis with an improved process. It also introduces methods and procedures for configuring a TFT (Task Force Team) to define elemental parts in electrical products and solve chronic defect. In particular, overseas factories require a simple and clear quality system, so there is no mistake only when a method that has been reliably verified in domestic factories is applied. Due to the specificity of overseas factories, regional quality management systems should be accompanied, and efforts should be made to design reliable growth that can increase the quality index. It is necessary to decide whether to proceed in the next stage of development, and it should be determined according to its importance and market situation. Since the best product comes from humans, component quality management with partner companies requires joint attention between the two companies and needs to be established by stipulating a maintenance system that does not recur after improving defective products.

Software reliability prediction is a statistical method to put in place a timely software development practice useful for objective assessment of bidders. The current study suggests one research method that enables reliability assessment of such previous projects by studying user satisfaction and project management history. If incorporated into the existing acquisition process, the reliability assessment method will further enhance objectivity and accuracy in bidder selection process. The GQM(Goal Question Metric) paradigm was used to identify assessment metrics for bidder evaluation and questionnaires were collected from users to create user satisfaction indexes. In addition, 'weight of evidence', the most appropriate categorical method, was used to isolate attributes of each variable that may contribute to reliability assessment.

The design variables and material properties as well as the external loads concerned with structural engineering are used to be deterministic in optimization process. These values, however, have variability from expected performance. Therefore, deterministic optimum designs that are obtained without taking these uncertainty into account could lead to unreliable designs, which necessitates the Reliability-Based Design Optimization(RBDO). RBDO involves an evaluation of probabilistic constraints which constitutes another optimization procedure. So, an expensive computational cost is required. Therefore, how to decrease the computational cost has been an important challenge in the RBDO research field. Approximation models, response surface model and Kriging model, are employed to improve an efficiency of the RBDO.

The optimum design of T-stub connection is presented in this research. T-stub can show semi-rigid or rigid behavior, making it possible to adjust the ultimate load and deformation ability. The design variables are assumed to the size and thickness of plate and diameter and number of bolts, while the objective function is the cost function of connection. Probabilistic analysis is rapidly developing into a desirable tool to improve design processes. Incorporating probabilistic with optimization of structures is a step towards improving many current deterministic design systems. This paper deals with applications of two optimization techniques to solve reliability based optimization problems of structures. The constraints are formulated based on the LRFD criteria of AISC specifications. The analytical processes of structural optimization are performed by SQP(i. e. Sequential Quadratic Programming) method which is so superior to solve the nonlinear problem. The reliability based optimization problem is formulated as minimization of structural volume subject to the constraints on the values of componential reliability indices determined by AFOSM approach.

Parametric life-cycle cost(LCC) models have been integrated with traditional design tools, and used in prior work to demonstrate the rapid solution of holistic, analytical tradeoffs between detailed design variations. During early designs stages there may be competing concepts with dramatic differences. Additionally, detailed information is scarce, and decisions must be models. for a diverse range of concepts, and the lack of detailed information make the integration make the integration of traditional LCC models impractical. This paper explores an approximate method for providing preliminary life-cycle cost. Learning algorithms trained using the known characteristics of existing products be approximated quickly during conceptual design without the overhead of defining new models. Artificial neural networks are trained to generalize on product attributes and life cycle cost date from pre-existing LCC studies. The Product attribute data to quickly obtain and LCC for a new and then an application is provided. In additions, the statistical method, called regression analysis, is suggested to predict the LCC. Tests have shown it is possible to predict the life cycle cost, and the comparison results between a learning LCC model and a regression analysis is also shown

The paper reviews the methodologies of confirmatory data analysis(CDA) and exploratory data analysis(EDA) in statistical quality control(SQC), design of experiment(DOE) and reliability engineering(RE). The study discusses the properties of flexibility, openness, resistance and reexpression for EDA.

최근 페이스북(Facebook)과 트위터(Twitter) 등의 폭발적인 성장에 따라 SNS는 사회적·학문적인 관심의 대상으로 부상하고 있다. 그러나, SNS는 이용자의 신상 정보와 사적인 의견 교환을 근간으로 사용자의 프라이버시가 노출될 수 있는 문제가 존재한다. 본 논문에서는 현재 SNS에서 이용자의 개인 프라이버시를 보호하기 위해 사용되고 있는 블록킹 대신 데이터 분리와 데이터 허위 정보를 이용한 SNS 사용자 프라이버시 보호 모델을 제안한다. 제안 모델은 사용자의 내용 정보를 분리하여 분리된 내용 정보에 허위 정보를 추가함으로써 제3자가 사용자의 내용 정보를 수집하여도 정확한 정보를 추출하지 못하도록 하고 있다. 또한, 제3자가 이용자의 정보를 불법적으로 악용하지 않도록 SNS 서비스 제공자가 이용자의 정보를 활용할 경우 이용자에게 사전에 동의를 구한다.

SNS is emerging as an academic and social interest, as Facebook and Twitter are developed explosively. But, SNS has a problem of exposing user's privacy because it is originated by exchanging user's personal information and opinion. This paper proposes SNS user privacy protecting model using data separation and false data information instead of blocking which is using to protect user's personal privacy. The proposed model do not let the third party extract precise information after collecting user's context information by adding false information to separated context information. Also, it gets user's agreement beforehand if SNS service provider uses user's information not to be used illegally by the third party.

본 논문에서는 낮은 위상잡음과 고신뢰성을 갖는 전압제어 발진기를 비선형 설계하였으며 그 위상잡음을 Lesson식과 비교하여 잘 일치함을 확인하였다. 전압제어 발진기의 위상잡음을 개선하기 위하여 유전체 공진기와 결합하는 마이크로 스트립 라인을 고임피던스 변환기를 이용함으로써 공진회로의 Q값이 그대로 능동소자에 전달되도록 하였다. 또한 worst case 해석 및 part stress 해석을 수행함으로써 전압제어 발진기의 신뢰도를 높였다. 제작된 전압제어 발진기는 012 V의 제어전압에서 0.56 MHz/V의 튜닝대역을 가지고 있으며 160 mW의 DC 전력을 소모한다. 또한 -116.5 dBc/Hz @100KHz와 -96.51 dBc/Hz @10KHz의 우수한 위상잡음 특성과 7.33 dBm의 출력을 얻었다.

The VCO(Voltage Controlled Oscillator) with low phase noise and high reliability is implemented using nonlinear design, and its phase noise characteristics are compared with that of Lesson's equation. The microstripline coupled with dielectric resonator is realized as a high impedance inverter to improve the phase noise, and the qualify factor of resonator circuit can be transferred to active device with the enhanced the loaded quality factor. The worst case and part stress analyses are achieved to obtain the high reliability of VCO. The developed VCO has the oscillating tuning factor of 0.56MHz/V for the control voltage range of 012V This VCO requires the DC power of 160mW. The phase noise characteristics exhibit good performances of -96.51dBc/Hz @ 10KHz and -116.3dBc/Hz @ 100KHz, respectively. And, the output power of 7.33 dBm is measured.

웹 크롤링 데이터를 이용한 실시간 시스템은 원격지의 데이터와 동일한 데이터베이스의 데이터를 사용자에게 제공해야 하며, 이를 위해서 웹 크롤러는 원격지 데이터의 변경 여부를 확인하기 위해 원격 서버에 반복적인 HTTP(HyperText Transfer Protocol) 요청을 수행해야 한다. 이 과정은 크롤링 서버와 원격 서버의 네트워크 부하를 일으키며 과도한 트래픽 발생 등의 문제의 원인이 된다. 이러한 문제점을 해결하기 위해 본 논문에서는 사용자 이벤트를 기반으로 크롤링 서버의 데이터와 다중 원격지 데이터와의 동일성을 유지하는 신뢰성을 확보함과 동시에 네트워크의 과부하를 줄일 수 있는 실시간 웹 크롤링 기법을 제안한다. 제안된 방법은 단위 데이터와 목록 데이터를 요청하는 이벤트를 기반으로 크롤링 프로세스를 수행한다. 실험 결과, 제안된 방법은 기존 웹 크롤러에서의 네크워크 트래픽 과부하를 줄이면서 데이터의 신뢰성을 확보할 수 있음을 확인하였다. 향후에는 이벤트 기반 크롤링과 시간 기반 크롤링에 대한 융합에 대한 연구가 필요하다.

Real-time systems using web cralwing data must provide users with data from the same database as remote data. To do this, the web crawler repeatedly sends HTTP(HtypeText Transfer Protocol) requests to the remote server to see if the remote data has changed. This process causes network load on the crawling server and remote server, causing problems such as excessive traffic generation. To solve this problem, in this paper, based on user events, we propose a real-time web crawling technique that can reduce the overload of the network while securing the reliability of maintaining the sameness between the data of the crawling server and data from multiple remote locations. The proposed method performs a crawling process based on an event that requests unit data and list data. The results show that the proposed method can reduce the overhead of network traffic in existing web crawlers and secure data reliability. In the future, research on the convergence of event-based crawling and time-based crawling is required.

시각화기술 중 하나인 가상현실(Virtual Reality)기술은 뛰어난 몰입감을 제공해 준다는 점 때문에 여러 산업 분야에서 폭넓게 활용되어지고 있는 중이다. 건축분야에서도 프레젠테이션 도구로 사용이 되고 있으며 최근 에는 설계과정에서도 적용하려는 움직임이 점차 확대되고 있다. VR기술이 건축설계와 건축설계교육과정에 활용되 었을 때 여러 관점에서 우수한 결과를 준다는 연구결과가 보고되고 있지만 3D 모델링툴 에서 제작된 디지털모델 과 VR환경 안에서 구현된 디지털모델 사이에 수치적으로 일치하는가에 대해서는 아직 검증된 적이 없다. 따라서 본 연구는 이들 둘 사이의 수치적 신뢰성의 정도를 실험을 통하여 분석하고 건축설계 전공학생들을 위한 교육도 구로써의 적합성을 판단하고자 한다.

As one of visualizing technologies, VR(Virtual Reality) technology is being used broadly in many industrial fields due to its ability to provide users with a great immersive experience. VR in architectural field has been utilized as an excellent presentation tool and increasingly used for a design process itself. There are many research to approve that VR can produce excellent results in many perspectives when it is used in architectural design process and education. However, it has not been approved that there is a numerical reliability between a digital model made in a 3D modeling tool and the same one visualized in VR. Therefore, this study tests whether VR is a proper educational tool for architectural students through a set of tests approving for numerical reliability.

This paper presents a study of the influence of cutting parameters on surface finish obtained by face milling. Cutting conditions have significantly great effect on surface quality in high-precision machining. Fundamentally, surface roughness are strongly correlated with cutting parameters such as feed rate, cutting speed and depth of cut. Optimal selection of the cutting parameters can obtain better surface roughness. Therefore, optimization of the cutting parameters in a face milling based on the parameter design of the Taguchi method is adopted in this paper to improve surface roughness. And optimal cutting parameters based on the results of the S/N ratio and ANOVA analyses to performance high-precision machining is obtained and verified by confirmation test.

In order to improve the work of a single path network reliability failure case, this chapter put forward a set of a single backup path algorithm based on the path. In this algorithm, using two disjoint paths as work path to transmit data, and USES the path does not intersect with the job of a set the path as the backup path. Then, this algorithm, is proposed based on a single - a single backup path algorithm of shortest path set to ensure data under the case of the second work path of effective transmission. Theoretical derivation and numerical simulation results show that in a single work path failure cases, and the calculation of DMP - compared to BP algorithm, this scheme can greatly improve network reliability, and save the network resources.

In order to solve the problems of high cost, complicated wiring and inconvenient operation of the elevator monitoring system, this paper designs an elevator safety monitoring system based on Internet of things technologies. In this system, the CC2530 acts as a processor and communication module, the DHT11 as a temperature and humidity sensor module, and the ADXL345 as an accelerometer sensor module. The power supply module uses the chip LM2576S to provide 3V and 3.3V voltage. The fault tree analysis method is employed to analyze the reliability of the system designed in this paper. The data acquisition module, power supply module and MCU I/O port are given relatively large weight, which demonstrates that they are more likely to cause system failure. In this paper, the environmental parameters of elevator in a certain residential area are tested. According to the test results, the average relative errors of temperature, air humidity and velocity are 0.47%, 1.40% and 1.36%, respectively. The experimental results show that this easy-to-operate system can monitor the environmental parameters of the elevator with high precision, and can achieve the real-time monitoring on the running state of the elevator.