• Earthquakes and Structures
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• 제3권1호
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• pp.17-35
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• 2012

Simplified equations for fundamental period of vibration of skeletal structures provided by most seismic design provisions suffer from the absence of any associated confidence levels and of any reference to their empirical basis. Therefore, such equations may typically give a sector of designers the false impression of yielding a fairly accurate value of the period of vibration. This paper, although not addressing simplified codes equations, introduces a set of mathematical equations utilizing the theory of error propagation and First-Order Second-Moment (FOSM) techniques to determine bounds on the relative error in theoretically calculated fundamental period of vibration of skeletal structures. In a complementary step, and for verification purposes, Monte Carlo simulation technique has been also applied. The latter, despite involving larger computational effort, is expected to provide more precise estimates than FOSM methods. Studies of parametric uncertainties applied to reinforced concrete frame bents - potentially idealized as SDOF systems - are conducted demonstrating the effect of randomness and uncertainty of various relevant properties, shaping both mass and stiffness, on the variance (i.e. relative error) in the estimated period of vibration. Correlation between mass and stiffness parameters - regarded as random variables - is also thoroughly discussed. According to achieved results, a relative error in the period of vibration in the order of 19% for new designs/constructions and of about 25% for existing structures for assessment purposes - and even climbing up to about 36% in some special applications and/or circumstances - is acknowledged when adopting estimates gathered from the literature for relative errors in the relevant random input variables.

• Environmental Analysis Health and Toxicology
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• 제14권4호
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• pp.203-216
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• 1999

This paper describes a set of multi-pathway models for estimating health risk to lead. The models link concentrations of an environmental contaminant (lead) in air, water and food to human exposure through inhalation, ingestion, and dietary routes. Exposure is used as the foundation for predicting risk of health detriment within the population. The process of estimating exposure using often limited data and extrapolating to a large diverse population requires many assumption, inferences, and simplification. This paper is divided into four section. The first section provides lead contaminant levels on obtaining environmental concentration of air, tap water, and foods. The second section provides a discussion of exposure parameters and uncertainty associated predicting human health risk of contaminants. The third and fourth section illustrate lifetime average daily exposure (LADE) and excess cancer risk (ECR) based on exposure parameters. The relationship between concentration of lead in an environmental medium and human exposure is determined with pathway exposure factors (PEFs). The calculation of LADE and ECR is carried out using Monte-Carlo simulation with probability density function of exposure parameters. Examination of the result reveals that, for lead exposure, ingestion (food) is the dominant route of exposure rather than inhalation (air), and ingestion (tap eater).

• 대한안전경영과학회지
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• 제17권1호
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• pp.149-168
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• 2015

It is expected that the temperature in Pyeongyang will be similar to that ($16.6^{\circ}C$) in Seogwipo in the late 21st century, and most of South Korea will enter the subtropical climate due to climate change. Change in the precipitation pattern like the range of fluctuation caused by climate change will lead to expanded uncertainty in securing reliable water supply, along with a serious impact on demands for living and industrial water due to change in the volume and period of river outflow. As industrial water for production activities is estimated based on the contract quantity, it is difficult to apply rationalization of water usage and incentives in water recycling. Therefore many companies are making efforts in complying with the effluent standard while spending few resources on such rationalization and recycling. This study researched water risk management over 115 Korean companies by 28 questions in 4 categories. Through the research, this study aims to understand water risk management levels and seek response plans.

• 복식문화연구
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• 제21권1호
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• pp.139-150
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• 2013

Fast fashion companies have generated enormous amounts of clothing and large quantities of unsold or short-lived clothing end up in the landfill. As if to counter fast fashion, sustainable fashion has arisen for environmentally friendly garments at different levels from the fiber stage to production stage. However it is still fraught with uncertainty of systems in the industry. Therefore, this study proposed a system to create re-valued clothing from recycled garments for retailers. The target companies are large-sized retailers like Levi's, Polo, Gap, or J-Crew which are consistently producing basic items such as Levi's 501 or Classic Polo shirts with middle-prices. At the material stage, this study recommended additional requirements of designing a garment with a long life cycle based on criteria of an ideal garment developed by Patagonia clothing company. Then, this study explored innovative ways that retailers might connect with consumers to allow direct interaction between them in terms of the process of collecting used clothes. Using recycled clothing as a source material, this study strove to offer a process of redesign where the concept of 'waste to fashion' is developed as reconstructions where old forms are transformed into new ones.

• 한국지진공학회논문집
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• 제2권3호
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• pp.83-86
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• 1998

The results from the Individual Plant Examination of External Event of Yonggwyang nuclear power plants, unit 3 & 4, in Korea have shown that the high degree of diversities of the experts' opinions on seismicity and attenuation models is su, pp.sed to be generic cause of uncertainty of APEs(annual exceedance probability) in the PAHA(probabilistic seismic hazard analysis). This study investigated the sensitivity of the focal depth, which is one of the most uncertain seismicity parameters in Korea, Significant differences in resultant values of annual exceedance probabilities and much more symmetrical shape of the resultant PDFs(probability density functions), in case of consideration of focal depth, are found. These two results suggest that, even for the same seismic input data set including the seismicity models and ground motion attenuation models, to consider focal depth additionally for probabilistic seismic hazard analysis evaluation makes significant influence on the distributions of uncertainties and probabilities of exceedance per year for the whole ranges of seismic hazard levels. These facts suggest that it is necessary to derive focal depth parameter more effectively from the historical and instrumental documents on earthquake phenomena in Koran Peninsula for the future study of PSHA.

• 성인간호학회지
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• 제19권1호
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• pp.12-23
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• 2007

Purpose: The purpose of the present study was to explore the meaning of quality of life in patients with chronic cardiovascular disease. Methods: A grounded theory method guided data collection and analysis. A total of 16 adult outpatients with chronic cardiovascular disease was participated. Data were collected through individual in-depth interviews. All interviews were audio taped and transcribed verbatim. Coding was used to establish different concepts and categories. A theoretical sampling technique was used to obtain diverse data from many relevant categories. Results: Seven categories were extracted, and they divided into constructing and intervening factors of quality of life. Constructing factors were uncertainty, recovery in the sense of control and maintaining social life. Intervening factors were symptom experiences, social support, taking care of themselves, and reflecting life. 'Keeping restrictive conditions under control' was emerged as a core category. The meaning of quality of life in patients with cardiovascular was explained according to the levels of keeping restrictive conditions under control. Conclusion: The result of this study may contribute for health professionals to understand the quality of life in patients with cardiovascular disease.

• Journal of the Korean Wood Science and Technology
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• 제33권5호통권133호
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• pp.66-75
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• 2005

Soybean-based adhesives have recently been reconsidered as alternatives to petroleum-based adhesives due to the uncertainty of availability of petrochemical products and the increased demand for wood adhesives. This study was conducted to investigate the adhesive properties of alkaline phenolic soy (APS) resin for hybrid poplar flakeboard. The APS resin was formulated by crosslinking an alkaline soy flour hydrolyzate with lab-prepared PF resin in the soy hydrolyzate to PF resin weight ratios of 70/30, 60/40, and 50/50. The APS resins were used to fabricate homogeneous hybrid poplar flakeboards with different resin solid levels (5%, 7%, and 9%), press temperatures (175 and $200^{\circ}C$), and press times of 8 and 10 minutes. The IB, wet MOR, and dimensional stability properties of board improved with increasing press time, press temperature, and PF level in APS resins. Increasing press time can be used to offset poor IB strength associated with a 9% resin solid level and the excessive moisture content in the mat. The following conditions were concluded to meet the requirements of the CSA standard for exterior-grade flakeboard: a 50% PF level, a 5% resin content, a $200^{\circ}C$ press temperature, and an 8 minute press time.

• Industrial Engineering and Management Systems
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• 제14권3호
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• pp.248-274
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• 2015

This study discusses a contract to promote collection and recycling of used products in a green supply chain (GSC). A collection incentive contract is combined with a reward-penalty contract. The collection incentive contract for used products is made between a retailer and a manufacturer. The reward-penalty contract for recycling used products is made between a manufacturer and an external institution. A retailer pays an incentive for collecting used products from customers and delivers them to a manufacturer with a product order quantity under uncertainty in product demand. A manufacturer remanufactures products using recyclable parts with acceptable quality levels and covers a part of the retailer's incentive from the recycled parts by sharing the reward from an external institution. Product demand information is assumed as (i) the distribution is known (ii) mean and variance are known. Besides, the optimal decisions for product quantity, collection incentive of used products and lower limit of quality level for recyclable parts under decentralized integrated GSCs. The analysis numerically investigates how (1) contract for recycling activity, (ii) product demand information and (iii) quality of recyclable parts affect the optimal operation for each GSC. Supply chain coordination to shift IGSC is discussed by adopting Nash Bargaining solution.

• 한국물환경학회지
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• 제20권6호
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• pp.685-691
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• 2004

Water quality forecasting with long term flow is important for management and operation of river environment. However, it is difficult to set up and operate a physical model for water quality forecasting due to large uncertainty in the data required for model setting. Therefore, relatively simpler stochastic approaches are adopted for this problem. In this study we try several multivariate time series models such as ARMAX models for the possible substitute for water quality forecasting. Those models are applied to the BOD and COD levels at Noryangin station, Han river, and also evaluated the effect of release from Paldang dam on them. Monthly BOD and COD data from 1985 to 1991 (7 years) are used for model building and another two year data for model testing. As a result of the study, the effect of improvement on water quality is much more effective combining with the water quality improvement of dam release than considering only increment of dam release in the downstream Han river.

• 경영과학
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• 제21권2호
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• pp.123-143
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• 2004

Internet shoppers interact with Internet shopping mall systems while they shop. To understand why Internet shoppers make purchase, this study view Internet shopping malls as information systems. Although this view point seems reasonable, little previous studies employing this perspective are found in the relevant literature. This study develops a research model where Internet shoppers' transaction intentions are affected by the mediating effects of trust and satisfaction. Trust can mitigate uncertainty of the e-commerce environment for consumers, and satisfaction is widely used to measure the effectiveness of information systems. Therefore, we consider them as key elements in this study. We further employ the construct of website quality to explain why shoppers have different levels of trust and satisfaction. We classify website quality into information quality, system quality. and design quality. We collected 282 survey responses from Internet shoppers who have prior experiences with Internet shopping malls to purchase a product or service. The survey data are used to empirically test the proposed nine research hypotheses using LISREL. The LISREL results indicate that information quality and design quality have significant impact on both satisfaction and trust, while system quality has little relation to trust level. Further, trust is shown to have significant influence on satisfaction. Finally. both trust and satisfaction is strongly related to the future transaction intention.