• Communications for Statistical Applications and Methods
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• 제24권1호
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• pp.15-27
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• 2017

This paper introduces a two-parameter discrete distribution based on a continuous two-parameter bathtub distribution. It is the only two-parameter discrete distribution that shows a bathtub-shaped hazard function. Some statistical properties of the distribution are discussed. Three different methods are used to estimate its two unknown parameters. The point estimators of the parameters have no closed form. The bootstrap method is used to estimate the distributions of these point estimators. Different approximations of the interval estimations for the two-parameters are discussed. Real data sets are analyzed to show how this distribution works in practice. A simulation study is performed to investigate the properties of the estimations obtained and compare their performances.

• 한국주거학회논문집
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• 제17권1호
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• pp.165-176
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• 2006

In the design guideline about the existing elderly housing, the equipment related to bathroom are the most important in the secure and functional aspect. On the other hand, the present elderly housing is being designed according to foreign design guideline or common housing form instead of reflecting living and physical qualities of the Korean elderly. Therefore, in this study based on the guideline of the existing literature, we made Mockup furnished with the equipments of bathroom and conducted an experiment in finding proper position and height for Korean elderly enough to use the bathroom conveniently and independently. The equipments of bathroom consist of different height wash bowls, toilet stools, grab bars, and a bathtub. As a result, suitable height of wash bowl is 760 mm $\pm{\alpha}$. We can realized that elderly feel comfortable to grab perpendicular bars of toilet stools more than horizontal ones. So it is necessary for elderly to grip perpendicular of grab bars added to prevention slipping and made shape easy to hold. Most of elderly told us that 500 mm of the bathtub setting is suitable. But many other people feel high. So height of the bathtub must be established lower than 500 mm for safety in the bathroom and for convenience.

• 품질경영학회지
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• 제23권3호
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• pp.93-101
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• 1995

We present a brief survey concerning the relations between mean residual life and failure rate. Change points of mean residual life and failure rate are known to be different in general and we explore such situations in this paper. A few parametric models which show bathtub-shaped failure rate are examined in details, including the shape of its corresponding mean residual life function. We give some graphical comparisons of trend changes of mean residual life and failure rate for various choices of parameters for each parametric model.

• International Journal of Reliability and Applications
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• 제2권3호
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• pp.161-187
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• 2001

Starting with the meaning of the word quality, diverse concepts connoted by the term are examined. Instead of a bathtub curve, the desirable shape of a failure rate covering the entire life of a good product, which might be called hockey-stick line, is introduced. From the hockey-stick line and the definition of reliability, two measurements are extracted. The terms reliability, failure rate, product life, and durability are explained. From the customer's standpoint, the concept of product quality is classified in five factors, according to related technology: performance, reliability, conformance to specifications, customer perception, and fundamentals advantage. The correlation of the five factors for a first-class product is discussed, Since the market share of a company is determined as the competition result of its product value, defined as product quality and price, the market share increase is derived mathematically from the increment of product value. The market share increase, $\Delta$S, can be calculated from the present market share, S, and the oriented relative value increment of new product, R, to the current product in the same company for the same market target: $\Delta$S : $\Delta$(1-S). R/(1+S.R). Finally, the importance of separating warranty cost from the profit equation for the durables is explained.

• Corrosion Science and Technology
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• 제4권5호
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• pp.201-206
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• 2005

Starting with the meaning of the word quality, diverse concepts connoted by the term are examined. Instead of a bathtub curve, the desirable shape of a failure rate covering the entire life of a good product, which might be called hockey-stick line, is introduced. From the hockey-stick line and the definition of reliability, two measurements are extracted. The terms r-reliability (failure rate) and durability (product life) are explained. The conceptual analysis of failure mechanics explains that reliability technology pertains to design area. The desirable shape of hazard rate curve of electronic items, hockey-stick line, clarifies that Mean-Time-to-failure (MTTF) as the inverse of failure rate can be regarded a nominal life. And Bx life, different from MTTF, is explained. Reliability relationships between components and set products are explained. Reshaped definitions of r-reliability and durability are recommended. The procedure to improve reliability and the reasons for failing to identify failure mode are clarified in order to search right solutions. And generalized Life-Stress failure model is recommended for the calculation of acceleration factor.

• 전기학회논문지
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• 제66권3호
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• pp.500-506
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• 2017

In 2014, ISO 55000s has been enacted and the power plant asset management is becoming a hot issue for all over the world. The asset management system is being developed as a combination of CBM(Condition Based Maintenance) and RCM(Reliability Centered Maintenance). Therefore, the research on the calculation of the failure rate which is the most basic index of RCM is actively carried out. The failure rate calculation has been going on for a long time, and the most widely used probability distribution is the Weibull distribution. In the Weibull distribution, the failure rate function is determined in three types according to the value of the shape parameter. However, the Weibull distribution has a limitation that it is difficult to apply it when the trend of failure rate changes-such as bathtub curves. In this paper, the failure rate is calculated using the mixture Weibull distribution which can appropriately express the change of the shape of the failure rate. Based on these results, we propose the necessity and validity of applying mixture Weibull distribution.

• Communications for Statistical Applications and Methods
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• 제23권5호
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• pp.399-409
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• 2016

Many of studies have suggested the modifications on Weibull distribution to model the non-monotone hazards. In this paper, we combine two cumulative hazard functions and propose a new modified Weibull distribution function. The newly suggested distribution will be named as a new flexible Weibull distribution. Corresponding hazard function of the proposed distribution shows flexible (monotone or non-monotone) shapes. We study the characteristics of the proposed distribution that includes ageing behavior, moment, and order statistic. We also discuss an estimation method for its parameters. The performance of the proposed distribution is compared with existing modified Weibull distributions using various types of hazard functions. We also use real data example to illustrate the efficiency of the proposed distribution.

• 한국실내디자인학회논문집
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• 제32호
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• pp.36-46
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• 2002

The purpose of this study is to find the characteristics of bathroom through the latest apartment model house, and to investigate the types of design element in bathroom space, that is equipment material, measurement, and shape. Also, this study compare the changes in bathroom investigated through the theoretical study and understand the general design characteristics of modern bathroom. Design characteristics of bathrooms of 19 apartment model houses that are 30pyong to 60pyong model in the south area of the Han river and new city area, Boon-dang were analyzed based on previous studies. The result of the study is as follows. 1) The most remarkable change of bathroom can be found in equipment. The type of bathroom equipment, materials, forms, size have been changing diversely. 2) In addition, the function of bathroom has been changing. Bathroom is not only sanitary place but also place for rest, health-care, beauty-care, storage, and it is possible to add health improving function. 3) On the other hand, $\ulcorner$washstand ＋ toilet ＋ shower booth$\lrcorner$ type is common for family-bathroom, and separate type of $\ulcorner$washstand ＋ toilet ＋ bathtub ＋ shower booth ＋ Powder room ＋ dress room$\lrcorner$type is most common for master-bathroom.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2004년도 춘계학술발표대회 논문집
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• pp.123-126
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• 2004

This study aims to identify the change of bathroom design characteristics through the investigation of bathroom space in apartment model houses. The bathroom space of each private exclusive area was analyzed from the plane characteristics perspective such as quantity, location, size and shape. For this study, site survey and observation was performed to analyze the characteristics of plane and design based on twenty seven model houses of seven large-sized construction firms with Seoul area focused on. Research object was restricted to from ten Pyeong's apartment to sixty Pyeong's in order to understand various characteristics of twenty seven model houses. Since analysis variables were not diverse, the main three factors - frequency, percentage and an average - were represented in Microsoft Excel worksheet, focusing on the quantity of each case, design characteristics and pattern. 1) The quantity of bathrooms: It was turned out that the quantity of bathroom was one in ten Pyeong's apartment while it was two in thirty, forty, and fifty Pyeong's apartment. There were mostly two bathrooms available in twenty Pyeong's apartment even if only one was planned in few cases. All powder rooms and dress rooms in twenty and fifty Pyeong's apartment were designed to be separated and be accessible through bedroom. 2) The size of bathrooms: As private exclusive area increased, the size of bathroom for both family and couple increased. Couple bathrooms had the tendency to be equipped with shower booth and bathtub at the same place or have more tubs than family bathrooms because couple bathrooms were bigger than family bathrooms. 3) The location of bathrooms: Couple bathrooms were usually located beyond dress rooms or powder rooms while family bathrooms were mostly located at the entrance side. 4) The shape of bathrooms: Shower booth was assumed to be in general vogue because family bathrooms, for the most part, were comprised of a flush toilet, a washstand and a shower booth. In the case of couple bathrooms, a flush toilet, a washstand, a shower booth and a tub were generally equipped in more than twenty Pyeong's apartments while a tub was not installed in twenty Pyeong's apartments.

• 한국주거학회논문집
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• 제25권1호
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• pp.63-71
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• 2014

This research is aimed to analyze the basic characteristics of the 16 floor plans of 4 small-sized apartments in DaLian-City. Recently, there are increasing that a small-sized apartments for new younger generation in China. The younger ages intend to got a new floor plan types apartments according to own's life style. Also, a lot of construction company showed the many types of new residential space design during the last about 10 years, in DaLian City. The research results are summarized as follows: First, all of the floor plan types were '-' shape, 'L' shape. Second, there were several co-relational types of space plan between living room, kitchen and dining space. Those are LDK, L K, L DK, LD K. Third, the bedroom of the $30m^2$-floor plan size has an open-space design but over the size of $40m^2$-floor plan the space is closed design. Fourth, The number of bathrooms in all the floor plans is just 1 and it's placed beside the entrance except for B3, C4. The basic equipments of the lavatory was a toilet, a washbowl, a shower. A bathtub is installed in the floor plans greater than $60m^2$. Fifth, almost all of the characteristics of the spatial interrelation - each room position order - based on the location of the entrance. In particular, almost all of the bedrooms are furthest from the entrance for the most privacy.