• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.6
• /
• pp.870-875
• /
• 2013

After introducing diagnosis equipment power failure prevention activities for distribution system have become more active. To do facility diagnosis and maintenance work more efficiently we need to evaluate reliability for the system and should determine the priority line with appropriate criteria. Thus, to calculate risk factor for the power distribution line that are composed of many component facilities its historical failure events for the last 5 years are collected and analysed. The failure statics show that more than 60% of various failures are related to environment factors randomly and about 20% of the failures are refer to the aging. As a strategic evaluation system reflecting these environmental influence is needed, a system on the basis of the probabilistic approach related statical variables in terms of failure rate and failure probability of electrical components is proposed. The figures for the evaluation are derived from the field failure DB. With adopting Bayesian rule we can calculate easily about conditional probability query. The proposed evaluation system is demonstrated with model system and the calculated indices representing the properties of the model line are discussed.

• Geomechanics and Engineering
• /
• v.13 no.6
• /
• pp.977-995
• /
• 2017

It is well accepted that rock failure mechanism influence the cutting efficiency and determination of optimum cutting parameters. In this paper, an attempt was made to research the factors that affect the failure mechanism based on discrete element method (DEM). The influences of cutting depth, hydrostatic pressure, cutting velocity, back rake angle and joint set on failure mechanism in rock-cutting are researched by PFC2D. The results show that: the ductile failure occurs at shallow cutting depths, the brittle failure occurs as the depth of cut increases beyond a threshold value. The mean cutting forces have a linear related to the cutting depth if the cutting action is dominated by the ductile mode, however, the mean cutting forces are deviate from the linear relationship while the cutting action is dominated by the brittle mode. The failure mechanism changes from brittle mode with larger chips under atmospheric conditions, to ductile mode with crushed chips under hydrostatic conditions. As the cutting velocity increases, a grow number of micro-cracks are initiated around the cutter and the volume of the chipped fragmentation is decreasing correspondingly. The crack initiates and propagates parallel to the free surface with a smaller rake angle, but with the rake angle increases, the direction of crack initiation and propagation is changed to towards the intact rock. The existence of joint set have significant influence on crack initiation and propagation, it makes the crack prone to propagate along the joint.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.8
• /
• pp.3086-3101
• /
• 2021

To supply precise marketing and differentiated service for the electric power service department, it is very important to predict the customers with high sensitivity of electric power failure. To solve this problem, we propose a novel grouped 𝑙_1/2 sparsity constrained logistic regression method for sensitivity assessment of electric power failure. Different from the 𝑙₁ norm and k-support norm, the proposed grouped 𝑙_1/2 sparsity constrained logistic regression method simultaneously imposes the inter-class information and tighter approximation to the nonconvex 𝑙₀ sparsity to exploit multiple correlated attributions for prediction. Firstly, the attributes or factors for predicting the customer sensitivity of power failure are selected from customer sheets, such as customer information, electric consuming information, electrical bill, 95598 work sheet, power failure events, etc. Secondly, all these samples with attributes are clustered into several categories, and samples in the same category are assumed to be sharing similar properties. Then, 𝑙_1/2 norm constrained logistic regression model is built to predict the customer's sensitivity of power failure. Alternating direction of multipliers (ADMM) algorithm is finally employed to solve the problem by splitting it into several sub-problems effectively. Experimental results on power electrical dataset with about one million customer data from a province validate that the proposed method has a good prediction accuracy.

• Journal of Korean Society of Forest Science
• /
• v.89 no.1
• /
• pp.33-40
• /
• 2000

This study was carried out to evaluate the fill slope failure possibility of forest road in Metamorphic rock area using fuzzy theory which is non-linear model. The results were summarized as follows. The potential slope failure by nine factors was mainly occurred under the such conditions as the total road width ranging from 4m to 5m, longitudinal gradients below $2^{\circ}$, fill slope length greater than 8m, fill slope gradients steeper than $40^{\circ}$, road on ridge position, soil types with weathered rock, slope gradients steeper than $40^{\circ}$, aspect of NW, and longitudinal slope form in convexity. The weight of importance by factors on fill slope failure was ranked in the order of fill slope length, fill slope gradient, road position, soil type, aspect and longitudinal slope form. The analysis showed that the fill slope failure possibility was low with less than 0.485 of the fuzzy integral value and high with more than 0.620 of the value. And the discriminant accuracy was 74.6%. The analysis with six out of nine factors indicated that the possibility was low with less than 0.441 of the fuzzy integral value and high with more than 0.583 of the value. In this case, the discriminant accuracy was slightly increased to 78.0%.

• Proceedings of the Safety Management and Science Conference
• /
• 2011.04a
• /
• pp.731-746
• /
• 2011

The successful and sustainable growth of SMEs depends on their ability of strengthen their competitiveness in quality and cost and service more than anything else as a fundamental of operation. Among these key competitive factors of SMEs, quality is the most critical factor in manufacturing business fields. Because quality strongly influence cost and service performance on this manufacturing business field. There are many different ways to improve the quality performance but it needs proper management decision to choose the best way what can maximize outputs with minimum inputs. And it needs effective measurement methods and some indicators to analysis the quality performance properly. The quality cost is one of the simplest key indicators to measure the quality performance and the effectiveness of quality related management decisions. The major purpose of this study is to diagnose the categorized current level of actual quality cost of local SMEs to maximize their quality management effectiveness through comparing their level with others what's expressed in early studies. In this study, through survey on local SMEs, we found that their average annual quality cost ratio versus turnover - Total amount of annual quality cost divided by annual turnover - is around 3.69% excluded some SME's performances what have different quality control measures with others. And we found some results what corresponded with the early studies on the correlations between those categorized quality costs factors and some discrepancies between some of the literature model and the early case study results as follows. There were negative correlations between the Prevention costs and the External failure costs, and the Appraisal costs and the External failure costs, and there was positive correlation between the Appraisal costs and Internal failure costs same as early studies. But, we couldn't found any strong negative correlations between the Cost of control - Preventive costs & Appraisal costs - and the Cost of Failure of control - Internal & External failure costs -. It reveals not only the lack of effectiveness on their preventive or appraisal activities but also it can reveal there were so many effective ways to prevent the failure costs properly such as some innovative investment on Factory automation includes Error Proofing and more preventive actions to improve the effectiveness of the typical management methods likes CE (Concurrent Engineering), APQP (Advanced Product Quality Planning), FMEA (Failure Mode & Effect Analysis) etc.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.27 no.2
• /
• pp.23-37
• /
• 1985

This studies were carried out to get characteristics of frequency distribution, probable flood flows according to the return periods, and the correlation between return periods and those length of records affect the Risk of failure in the annual maximum series of the main river systems in Korea. Especially, Risk analysis according to the levels were emphasized in relation to the design frequency factors for the different watersheds. Twelve watersheds along Han, Geum, Nak Dong, Yeong San and Seom Jin river basin were selected as studying basins. The results were analyzed and summarized as follows. 1. Type 1 extremal distribution was newly confirmed as a good fitted distribution at selected watersheds along Geum and Yeong San river basin. Three parameter lognormal Seom Jin river basin. Consequently, characteristics of frequency distribution for the extreme value series could be changed in connection with the watershed location even the same river system judging from the results so far obtained by author. 2. Evaluation of parameters for Type 1 extremal and three parameter lognormal distribution based on the method of moment by using an electronic computer. 3. Formulas for the probable flood flows were derived for the three parameter lognormal and Type 1 extremal distribution. 4. Equations for the risk to failure could be simplified as $\frac{n}{N+n}$ and $\frac{n}{T}$ under the condition of non-parametric method and the longer return period than the life of project, respectively. 5. Formulas for the return periods in relation to frequency factors were derived by the least square method for the three parameter lognormal and Type 1 extremal distribution. 6. The more the length of records, the lesser the risk of failure, and it was appeared that the risk of failure was increasing in propotion to the length of return periods even same length of records. 7. Empirical formulas for design frequency factors were derived from under the condition of the return periods identify with the life of Hydraulic structure in relation to the risk level. 8. Design frequency factor was appeared to be increased in propotion to the return periods while it is in inverse proportion to the levels of the risk of failure. 9. Derivation of design flood including the risk of failure could be accomplished by using of emprical formulas for the design frequency factor for each watershed.

• Journal of Korean Library and Information Science Society
• /
• v.22
• /
• pp.139-169
• /
• 1995

The purpose of this study is to analyze the search pattern and search outcome of the National Central Library OPAC users by measuring their success rates and identifying the factors of failure and the personal background which bring about the differences of the search outcome. Various methods have been used for the study. Personal interview was used to find the pattern of the search, observation method was used to investigate the search process and the failure factors, and a questionnaire was used to survey personal background of searchers. The data were collected during the period of 7 days from April 17, 1995 through April 23, 1995. The search of 1, 217 cases, sampling systematically 25% out of the whole users, were collected and analyzed for the study. The findings of the study can be summarized as follows : First, in regard to the pattern, known-item search(72.6%) was preferred to the subject search(27.4%) and in case of known-item search the access point used were in the order of title, author, title and author. Second, the overall success rate of known-item search was 50.3% and the success rates were in order of author and date, title, and author. The failure factors of known-item search were divided into users factor of 67% and the database factor of 33%, respectively. Third, in case of subject search, its overall success rate was 44.1% and the keyword was the major access point, and the average of precision ratio was very low. Fourth, the analysis of the personal background related to the search outcome has shown significant differences by sex, the experience of using OPAC, education level, and the frequency of using other information retrieval systems. Based on the results the following suggestions can be made to improve the search outcome : First, the system should be su n.0, pplemented online help function to assist users to overcome the failure during search. Second, user instruction in group or individual should be implemented for the users to understand the system.

• Radiation Oncology Journal
• /
• v.37 no.2
• /
• pp.73-81
• /
• 2019

Purpose: There is sparse literature on treatment outcomes research on resectable oral tongue squamous cell carcinoma (OTSCC). The aim of this study was to measure the treatment outcomes, explore the failure patterns, and identify the potential clinicopathological prognostic factors affecting treatment outcomes for resectable OTSCC. Materials and Methods: It is a retrospective analysis of 202 patients with resectable OTSCC who underwent upfront primary surgical resection followed by adjuvant radiotherapy with or without concurrent chemotherapy if indicated. Results: The median follow-up was 35.2 months (range, 1.2 to 99.9 months). The median duration of locoregional control (LRC) was 84.9 months (95% confidence interval, 67.3-102.4). The 3- and 5-year LRC rate was 68.5% and 58.3%, respectively. Multivariate analysis showed that increasing pT stage, increasing pN stage, and the presence of extracapsular extension (ECE) were significantly associated with poorer LRC. The median duration of overall survival (OS) was not reached at the time of analysis. The 3- and 5-year OS rate was 70.5% and 66.6%, respectively. Multivariate analysis showed that increasing pT stage and the presence of ECE were significantly associated with a poorer OS. Conclusion: Locoregional failure remains the main cause of treatment failure in resectable OTSCC. There is scope to further improve prognosis considering modest LRC and OS. Pathological T-stage, N-stage, and ECE are strong prognostic factors. Further research is required to confirm whether adjuvant therapy adds to treatment outcomes in cases with lymphovascular invasion, perineural invasion, and depth of invasion, and help clinicians tailoring adjuvant therapy.

• Journal of the Korea Society of Computer and Information
• /
• v.18 no.10
• /
• pp.199-205
• /
• 2013

This study examined the factors of failure of new-type computer which has a functions of replacing and supplementing of existing product by being unaccepted by market. Placing the reason of market failure in a customer's negative perception of the value of the product, influential relationship was explored by distinguishing the factors that influence value perception between benefit of use of product and the cost of using product. As a result of this empirical research on netbook, a customer's negative perception of the value of new product had an negative influence on intention of use. And a customer's perceptional cost of new-type computer had an significant influence on negative perception of the value of the new product. However, even if a customer perceived benefit of new-type computer negatively, this did not impact on negative influence.

• Investigative and Clinical Urology
• /
• v.59 no.6
• /
• pp.371-375
• /
• 2018

Purpose: To compare patients with sepsis due to obstructive urolithiasis (Sep-OU) and underwent drainage by percutaneous nephrostomy (PCN) or a double-J (DJ)-ureteral stent and to identify predictive risk factors of DJ stent failure in these patients. Materials and Methods: We reviewed our records from January 2013 to July 2018 and identified 286 adult patients with Sep-OU out of which 36 had bilateral involvement, thus total 322 renal units were studied. Urologic residents in training carried out both ureteral stenting and PCN tube placement. Demographic data and stone characteristics were recorded along with Charlson comorbidity index. For predicting risk factors of DJ stent failure, those variables that had a p-value <0.1 in univariate analysis were combined in a multinomial regression analysis model. Results: The patients with PCN placement were significantly older than those with DJ stent placement (p=0.001) and also had significant number of units with multiple calculi (p=0.018). PCN was also placed more frequently in those patients with a upper ureteric calculi (p<0.05). On multinomial regression analysis multiple calculi (p=0.014; odds ratio [OR], 4.878; 95% confidence interval [CI], 1.377-17.276) and larger calculi size (p=0.040; OR, 0.974; 95% CI, 0.950-0.999) were the significant predictors of DJ stent failure. Conclusions: In patients with sepsis from obstructive urolithiasis due to larger and multiple calculi a PCN placement might be better suited although this data requires further prospective randomized studies to be extrapolated.