• Design & Manufacturing
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• 제15권1호
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• pp.8-13
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• 2021

Excavators are construction machines used for digging soil, transporting soil, dismantling buildings and clearing the ground at construction sites. There are various attachments attached to the arm end of the excavator and used for various operations. There are the most common types of buckets attached for excavation and other types of attachments used for foresting, road cleaning, snow removal, and waste disposal. When multiple types of work are done at the same time, several attachments must be replaced and a device called a quick coupler is used to reduce replacement time. Although a quick coupler reduces the replacement time of the Attachment, it is necessary to attach safety devices to prevent unintentional detachment of attached attachments during the operation. To prevent the attachment from leaving or falling regardless of the operator's intention, support is installed in the hook of the bucket pin and controlled through a separate hydraulic cylinder to ensure safety. When attaching an attachment, it shall be attached without any action. This study is intended to verify the design validity of safety devices to prevent falls of attachments occurring at construction sites.

• 한국프랜차이즈경영연구
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• 제6권1호
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• pp.1-20
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• 2015

Home Meal Replacement (HMR) products are ready-to-eat or pre-cooked food products that are consumed at daily home. HMR market has grown rapidly due to societal changes: increases in female social activities, silver population, and one-person households. Consumption channels of HMR can be classified into take-out, delivery, and retail. In Korean HMR market, retail sector is largely growing, but companies are focusing their business on the home delivery sector. Moreover, franchise companies are expanding their areal coverage in the HMR market based on their multi-unit strategy. However, more research on the HMR market is needed as existing studies are limited in conceptualization, classification, and processed food from malls or home-shopping channels. Therefore, we conducted the efficiency analysis on Gukseonsaeng, one of franchises that applied the take-out channel, using DEA method. According to the research on 29 franchisees of Gukseonsaeng, 77.9% of input appeared inefficient for technical efficiency, while 53.3% of input appeared inefficient for scale efficiency. Thus, we found that franchises of Gukseonsaeng are structured in increasing returns to scale (IRS), so enhancing efficiency by expanding scales need to be implemented.

• Advances in concrete construction
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• 제15권1호
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• pp.63-74
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• 2023

All production and consumption activities produce wastes, which often cause damage to our environment and multiple risks to the human health. The valorization of these wastes in concrete technology is a future solution that will allow finding other construction materials sources, optimizing energy consumption and protecting the environment. Among these wastes, there is the marble waste. Every year, huge amount of marble waste is discarded as dust or aggregates form, in open-air storage areas causing serious problems for the environment and public health. In this context, the incorporation of marble waste as a replacement of ordinary aggregates or cement in concrete composition is actively investigated by researchers. This paper presents a comprehensive review of published studies over the last 20 years, dealing the effect of marble waste on fresh and hardened properties of concrete. Most of the studies carried out have used marble waste as dust with substitution rates between 5 and 20%. Besides the economic and ecological benefits, this review showed that marble waste can improve the physical, mechanical and durability properties of concrete. This improvement depends on the form (dust, fine aggregate or coarse aggregate), substitution method (as cement or aggregates replacement) and substitution rate of marble waste. Additionally, the review results showed that the use of 10-15% of marble waste dust as cement substitution can lead to increase the compressive strength.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.470-475
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• 2011

The objective of this study is the developement health & disaster monitoring measurement using ubiquitous active communication digital datalogger system for monitoring measurement of railway construction sites. For the replacement of current passive data communication, ubiquitous active communication digital datalogger system is studied for the first time with in a country. Therefore data communication method and analyzing program of automatic measurement data is developed for the global positioning automatic digital datalogger system. The results of this study will be using both real time automatic monitoring measurement and health & disaster monitoring measurement of railway structures.

• Communications for Statistical Applications and Methods
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• 제9권3호
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• pp.865-870
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• 2002

Burn-in is a widely used method to eliminate the initial failures. Preventive maintenance policy such as age replacement is often used in field operation. In this paper burn-in and maintenance policy are taken into consideration at the same time. The properties of the corresponding optimal burn-in times and optimal maintenance policy are discussed.

• 품질경영학회지
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• 제31권1호
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• pp.142-147
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• 2003

Burn-in is a widely used method to eliminate the initial failures. Preventive maintenance policy such as block replacement with minimal repair at failure is often used in field operation. In this, paper burn-in and maintenance policy are taken into consideration at the same time. The cost of a minimal repair is assumed to be a non-decreasing function of its age. The problems of determining optimal burn-in times and optimal maintenance policy are considered.

• 품질경영학회지
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• 제20권1호
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• pp.39-47
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• 1992

This paper is concerned with cost analysis and determination of warranty period in a stepdown warranty policy. Manufacturer's warranty cost is analyzed for nonrepairable item, where the warranty is assumed to be renewed at any failure within the warranty period. It is shown that from this result in free replacement policy, pro-rata policy and hybrid policy can be easily calculated. The method of determining optimal warranty period is also explored.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.117-120
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• 1998

The objective of this study is to investigate the possibility for application of E.P-dust as both admixture and fillers for aggregates under various mixproportion, replacing method and the ratios of replacement. According to the experimental results, improvement of viscosity and reducing of segregation at fresh state and gain in strength at hardened state can be achieved by applying E.P-dust. It can be considered from the results that application of E.P-dust will be more efficient as fillers for aggregates than as binder

• 한국통계학회:학술대회논문집
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• 한국통계학회 2002년도 추계 학술발표회 논문집
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• pp.147-151
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• 2002

Burn-in is a widely used method to eliminate initial failures. Preventive maintenance policy such as block replacement with minimal repair at failure is often used in field operation. In this paper burn-in and maintenance policy are taken into consideration at the same time. The cost of a minimal repair is assumed to be a non-decreasing function of its age. The problems of determining optimal burn-in times and optimal maintenance policy are considered.

• Communications for Statistical Applications and Methods
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• 제11권2호
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• pp.413-418
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• 2004

Statistically illiterate people seem to believe that there are some strategies for choosing winning numbers in lottery. One seemingly plausible strategy is to select the hot numbers which most frequently appeared in the past. In this article we investigate the existence of hot numbers in the Korean national lottery called Lotto. A numerical method is proposed to estimate the exact sampling distribution of test statistic for checking the existence of hot numbers among 45 possible numbers of choice.