• Title/Summary/Keyword: Reliability of Selection

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The Comparative Study for NHPP Software Reliability Growth Model Based on Non-linear Intensity Function (비선형 강도함수를 가진 NHPP 소프트웨어 신뢰성장 모형에 관한 비교 연구)

  • Kim, Hee-Cheul
    • Convergence Security Journal
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    • v.7 no.2
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    • pp.1-8
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    • 2007
  • Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault (intensity function). In this paper, intensity function of Goel-Okumoto model was reviewed, proposes Kappa (2) and the Burr distribution, which maked out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method. For model determination and selection, explored goodness of fit (the error sum of squares) The methodology developed in this paper is exemplified with a software reliability real data set introduced by NTDS (Naval Tactical Data System)

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A Study on the Selection Factors of Mobile Fashion Shopping Apps

  • Jung, Na-Eun;Lee, Hyung-Seok
    • Journal of the Korea Society of Computer and Information
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    • v.27 no.2
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    • pp.229-236
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    • 2022
  • In this study, we proposed a hierarchical model of a mobile fashion shopping apps to find out factors that consumers consider when choosing a mobile fashion shopping apps, and also derived priorities by calculating the weights of the selection factors. To estimate the priorities of selection factors, we analyzed survey data collected from consumers who are currently using a mobile fashion shopping apps. As a result of this study, the first-step selection factors of the mobile fashion shopping apps consisted of economics, informativity, convenience, reliability, and additional service, and economics factor revealed to be the most important. Additionally, in the result of synthesizing the weights of the first-step and second-step selection factors, the coupons and discount event factor was found to be the most important. In the fierce competition of various mobile fashion shopping apps, the findings of this study not only proposed the evaluation model of mobile fashion shopping apps using the AHP technique but provided the priority of consumers' selection factors for mobile fashion shopping apps.

A Study on the Selection Attribute of Bakery Stores using Correspondence Analysis (대응일치분석을 이용한 국내 제과점의 선택 속성 분석)

  • Lee, Kwang Suck;Kim, Eun Ji;Jung, Hyo Sun
    • Korean journal of food and cookery science
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    • v.30 no.4
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    • pp.412-418
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    • 2014
  • This study considered the selection attributes of bakery consumers and schematized characteristic attributes of being selected by customers by image through a correspondence analysis in terms of own preferring bakery. Self-administrated questionnaires were completed by consumers (452 samples), and the data were analysed by frequency, chi-square, one-way ANOVA, reliability analysis and correspondence analysis. According to the survey results regarding the mean value on bakery selection attributes, it was shown to be in the order of taste ($4.73{\pm}0.70$), sanitation ($4.70{\pm}0.68$), service ($4.21{\pm}0.84$), price ($4.03{\pm}0.92$), consideration ($4.01{\pm}0.96$), communication ($4.01{\pm}0.96$), health ($3.99{\pm}0.98$), and location ($3.83{\pm}0.99$). In the analysis of difference with regard to the selection attributes according to the preferred bakery, both consideration ($4.05{\pm}0.90$) and communication ($3.98{\pm}0.93$) showed a high value in individual bakery, thereby presenting a significant difference (p<0.05). As a result of having carried out correspondence analysis in order to prepare an image map according to the preferred bakery, the selection attributes of employees' service and communication showed the closest image map to individual bakery. Location and sanitation were very close to franchise bakery. Further, other bakery shops were schematized in a relatively close distance to price.

Low-complexity Joint Transmit/Receive Antenna Selection Algorithm for Multi-Antenna Systems (다중 안테나 시스템을 위한 낮은 복잡도의 송/수신안테나 선택 알고리즘)

  • Son, Jun-Ho;Kang, Chung-G.
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.10A
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    • pp.943-951
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    • 2006
  • Multi-input-multi-output (MIMO) systems are considered to improve the capacity and reliability of next generation mobile communication. However, the multiple RF chains associated with multiple antennas are costly in terms of size, power and hardware. Antenna selection is a low-cost low-complexity alternative to capture many of the advantages of MIMO systems. We proposed new joint Tx/Rx antenna selection algorithm with low complexity. The proposed algorithm is a method selects $L_R{\times}L_T$ channel matrix out of $L_R{\times}L_T$ entire channel gain matrix where $L_R{\times}L_T$ matrix selects alternate Tx antenna with Rx antenna which have the largest channel gain to maximize Frobenius norm. The feature of this algorithm is very low complexity compare with Exhaustive search which have optimum capacity. In case of $4{\times}4$ antennas selection out of $8{\times}8$ antennas, the capacity decreases $0.5{\sim}2dB$ but the complexity also decreases about 1/10,000 than optimum exhaustive search.

The Effect of Security Major University Students' Major Selection Motivation on Major Satisfaction and Career Decision (물리보안 전공 대학생들의 선택 동기가 전공만족도 및 진로결정에 미치는 영향)

  • Ye-Jin Jang;Jeong-Il Choi
    • Convergence Security Journal
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    • v.22 no.1
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    • pp.159-166
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    • 2022
  • The purpose of this study conducted to conduct a survey to understand the effect of security major college students' major selection motives on major satisfaction and career decisions. The questionnaire was written as "First, motivation for choice, second, major satisfaction, third, career decision". In this study, Chronbach's Alpha coefficient was calculated to analyze the reliability and importance of variables and to identify exploratory factors. And the Berimax method was performed. Both the AVE and CR values of the measured items were calculated to be above the reference value of 0.7, and thus, the convergent validity of each item was investigated as favorable. In the hypothesis test results, the standardization coefficient of 'selection motive ⇨ major satisfaction' was 0.653 and 'major satisfaction ⇨ career decision' was 0.403, so both research hypotheses were adopted. However, 'selection motive ⇨ career decision' was rejected with 0.392. In the future, universities and related professors seem to need more efforts to simultaneously increase the selection motive and major satisfaction in order to improve the career decisions of college security students.

Perceptions of eco-friendly young-children's wear and selection criteria for young-children's wear and stores - A comparison of eco-friendly and ordinary children's wear purchasers - (친환경 유아복에 대한 인식이 유아복 구매시의 제품과 점포 선택기준에 미치는 영향 - 친환경 유아복 구매자와 비 구매자 비교 -)

  • Hong, Eun Bee;Hwang, Choon Sup
    • The Research Journal of the Costume Culture
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    • v.20 no.6
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    • pp.895-911
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    • 2012
  • The purpose of this study was to examine consumers' perceptions of eco-friendly children's-wear and their impact on the selection criteria for children's-wear and stores. A descriptive survey method using a self-administered questionnaire was employed. The sample consisted of mothers with children under the age of 13 residing in Seoul and the Gyeonggi area. Data were collected from September 2011 to October, 2011. The collected data were analyzed to find the differences between purchasers and non-purchasers of eco-friendly children's-wear in terms of their perceptions of eco-friendly children's-wear, as well as the influence of these perceptions on the consideration degree of criteria for the selection of children's wear and store. The results indicate that perceptions of eco-friendly children's-wear implied five key factors related to quality reliability, expected value, style, degree of recognition, and dissatisfaction with design and price. The results also revealed some differences between the group purchasing eco-friendly children's-wear and the group not purchasing eco-friendly children's-wear. These different perceptions were related to the aspects of quality reliability, expected value, style, degree of recognition. In general, the non-purchasing group displayed a lower mean score than the purchasing group. Both groups showed a low interest in aesthetic appreciation and the degree of recognition factor. The results showed that consumer's perceptions of eco-friendly children's-wear had an influence on the criteria for the selection of children's-wear and store type in both groups. Considering the findings of the study, it is clear that both purchasers and non-purchasers of eco-friendly children's-wear showed differences in their perceptions and purchasing behavior. Therefore, marketing strategies to appeal to the non-purchasing group should be differentiated from strategies used to ensure the loyalty of the purchasing group.

Probabilistic Reliability Based HVDC Expansion Planning of Power System Including Wind Turbine Generators (풍력발전기를 포함하는 전력계통에서의 신뢰도 기반 HVDC 확충계획)

  • Oh, Ungjin;Lee, Yeonchan;Choi, Jaeseok;Yoon, Yongbeum;Kim, Chan-Ki;Lim, Jintaek
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.1
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    • pp.8-15
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    • 2018
  • New methodology for probabilistic reliability based grid expansion planning of HVDC in power system including Wind Turbine Generators(WTG) is developed in this paper. This problem is focused on scenario based optimal selection technique to decide best connection bus of new transmission lines of HVDC in view point of adequacy reliability in power system including WTG. This requires two kinds of modeling and simulation for reliability evaluation. One is how is reliability evaluation model and simulation of WTG. Another is to develop a failure model of HVDC. First, reliability evaluation of power system including WTG needs multi-state simulation methodology because of intermittent characteristics of wind speed and nonlinear generation curve of WTG. Reliability methodology of power system including WTG has already been developed with considering multi-state simulation over the years in the world. The multi-state model already developed by authors is used for WTG reliability simulation in this study. Second, the power system including HVDC includes AC/DC converter and DC/AC inverter substation. The substation is composed of a lot of thyristor devices, in which devices have possibility of failure occurrence in potential. Failure model of AC/DC converter and DC/AC inverter substation in order to simulate HVDC reliability is newly proposed in this paper. Furthermore, this problem should be formulated in hierarchical level II(HLII) reliability evaluation because of best bus choice problem for connecting new HVDC and transmission lines consideration. HLII reliability simulation technique is not simple but difficult and complex. CmRel program, which is adequacy reliability evaluation program developed by authors, is extended and developed for this study. Using proposed method, new HVDC connected bus point is able to be decided at best reliability level successfully. Methodology proposed in this paper is applied to small sized model power system.

Cleaning Interval Selection for SCR Considering Endurance Reliability and Emissions Reduction Efficiency in Heavy Duty Commercial Engine (대형 상용 엔진에서 SCR의 클리닝 주기 선정 및 저감효율에 따른 내구신뢰성 특성 연구)

  • Shin, Jaesik;Kang, Jungho;Kim, Hyongjun
    • Journal of Applied Reliability
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    • v.18 no.1
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    • pp.66-71
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    • 2018
  • Purpose: Performance recovered from SCR through cleaning was studied, measuring differential pressure, NOx reduction efficiency, fuel consumption and engine power before and after cleaning. Ideal cleaning intervals are proposed based on SCR mileage and differential pressure. SCR endurance and reliability improvements through cleaning were studied through physicochemical testing of SCR durability at 43,000km 50,000km, and 110,000km respectively. Methods: Engine power, fuel consumption and exhaust gas were measured using engine full load tests and ND-13 MODE by installing the SCR before cleaned at total engine mileages of 400,000 km, 300,000km and 200,000km. The same tests were performed after cleaning the SCR catalytic converter. Endurance and reliability of the SCR cleaning was studied through the same test by SCR catalyst after each 43,000km 50,000km, 110,000km, durability test on SCR cleaning. Conclusion: We confirmed the low-performance of the SCR due to clogging is restored by SCR cleaning technology. The NOx reduction efficiency was restored to 82%, 86% and 88% from 69%, 72% and 79%. As well as the NOx reduction efficiency, it was confirmed that the engine power, fuel consumption and back pressure was restored to fresh SCR levels. As a result of the durability and reliability achieved through SCR cleaning, we confined the appearance and reduction efficiency through visual inspection and ND-13 MODE are similar to new SCR catalysts. Finally, it was judged that there was no change in performance even when driving the SCR without cleaning throughout the 100,000 km mileage warranty.

A Method for Selecting Software Reliability Growth Models Using Partial Data (부분 데이터를 이용한 신뢰도 성장 모델 선택 방법)

  • Park, Yong Jun;Min, Bup-Ki;Kim, Hyeon Soo
    • KIPS Transactions on Software and Data Engineering
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    • v.4 no.1
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    • pp.9-18
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    • 2015
  • Software Reliability Growth Models (SRGMs) are useful for determining the software release date or additional testing efforts by using software failure data. It is not appropriate for a SRGM to apply to all software. And besides a large number of SRGMs have already been proposed to estimate software reliability measures. Therefore selection of an optimal SRGM for use in a particular case has been an important issue. The existing methods for selecting a SRGM use the entire collected failure data. However, initial failure data may not affect the future failure occurrence and, in some cases, it results in the distorted result when evaluating the future failure. In this paper, we suggest a method for selecting a SRGM based on the evaluation goodness-of-fit using partial data. Our approach uses partial data except for inordinately unstable failure data in the entire failure data. We will find a portion of data used to select a SRGM through the comparison between the entire failure data and the partial failure data excluded the initial failure data with respect to the predictive ability of future failures. To justify our approach this paper shows that the predictive ability of future failures using partial data is more accurate than using the entire failure data with the real collected failure data.

Selection of Optimal Location and Size of Distributed Generation Considering Power Loss (전력손실을 고려한 분산전원의 최적 위치 및 용량 선정)

  • Lee, Soo-Hyoung;Park, Jung-Wook
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.4
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    • pp.551-559
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    • 2008
  • Increase in power consumption can cause a serious stability problem of an electric power system without construction of new power plants or transmission lines. Also, it can generate large power loss of the system. In costly and environmentally effective manner to avoid constructing the new infrastructures such as power plants and transmission lines, etc, the distributed generation(DG) has paid great attentions so far as a solution for the above problem. Selection of optimal location and size of the DG is the necessary process to maintain the stability and reliability of existing system effectively. However, the systematic and cardinal rule for this issue is still open question. In this paper, the method to determine optimal location of the DG is proposed by considering power loss when the DG is connected to an electric power grid. Also, optimal size of not only the corresponding single DG but also the multi-DGs is determined with the proposed systematic approach. The IEEE benchmark 30-bus test system is analyzed to evaluate the feasibility and effectiveness of the proposed method.