• Smart Structures and Systems
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• 제21권5호
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• pp.623-635
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• 2018

In order to study the mechanical behavior of shield tunnel segments during assembly stage, the in-situ tests and FDM numerical simulation were conducted based on the Foguan Shiziyang Tunnel with large cross-section. Analysis for the load state of the assembling segments in different assembly steps as well as the investigation for the changing of inner forces and longitudinal stress of segments with assembling steps were carried out in this paper. By comparing the tested results with the simulated results, the conclusions and suggestions could be drawn as follows: (1) It is the most significant for the effects on axial force and bending moment caused by the assembly of adjacent segment, followed by the insertion of key segment while the effects in the other assembly steps are relative smaller. With the increasing value of axial force, the negative bending moment turns into positive and remains increasing in most monitored sections, while the bending moment of segment B1and B6 are negative and keeping increasing; (2) The closer the monitored section to the adjacent segments or the key segment, the more significant the internal forces response, and the monitored effects of key segment insertion are more obvious than that of calculation; (3) The axial forces are all in compression during assembling and the monitored values are about 1.5~1.75 times larger than the calculated values, and the monitored values of bending moment are about 2 times the numerical calculation. The bending moment is more sensitive to the segments assembly process compared with axial force, and it will result in the large bending moment of segments during assembling when the construction parameters are not suitable or the assembly error is too large. However, the internal forces in assembly stage are less than those in normal service stage; (4) The distribution of longitudinal stress has strong influence on the changing of the internal forces. The segment side surface and intrados in the middle of two adjacent jacks are the crack-sensitive positions in the early assembly stage, and subsequently segment corners far away from the jacks become the crack-sensitive parts either.

• Journal of applied mathematics & informatics
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• 제1권1호
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• pp.1-12
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• 1994

We consider a single channel CSMA/CD system with D homogeneous stations and impeded buffer of infinite size. We find a sufficient condition for the model to be stable under the threshold control policy and derive the limiting distri-bution of the number of messages in the system at the moment of service completion. We also derive the limiting distributing of the number of messages in the system size at arbitrary time by using Markov regenerative processes. Some numerical examples and special cases are also treated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.359-362
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• 2003

Carbon fiber sheet is attractive due to its good tensile strength, resistance to corrosion, and low weight. The strengthening of concrete structures with externally bonded carbon fiber sheets is increasingly being used for repair and rehabilitation of existing structures. However CFS strengthened beams break down under the service loads. As rupture strain is not reached ultimate value, reduction of the tensile strength is recommended. This study evaluate CFS tensile strength reduction factor which is required to analyze bending moment.

• 한국전자거래학회지
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• 제5권1호
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• pp.93-104
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• 2000

Domestic automotive industry is also facing the moment it should be with a competitively priced and highly qualified automotive ta compete with worldwide automotive makers of world market through global marketing and global sourcing. At this point, weve been studying xNX model of USA, Japan and Europe with OEMs, suppliers and KAMA(Korea Automotive Manufacturers Association) to give a network infrastructure of guaranteed service quality network performance, reliability, security and trouble handling. We hope all efforts above mentioned will make the whole industry more competitive and powerful.

• 품질경영학회지
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• 제45권4호
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• pp.649-664
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• 2017

Purpose: This paper introduces the technology of prognostics for Industry 4.0 and presents its application procedure for fitness-for-service assessment of natural gas pipelines according to ISO 13374 framework. Methods: Combining data-driven approach with pipe failure models, we present a hybrid scheme for the gas pipeline prognostics. The probability of pipe failure is obtained by using the PCORRC burst pressure model and First Order Second Moment (FOSM) method. A fuzzy inference system is also employed to accommodate uncertainty due to corrosion growth and defect occurrence. Results: With a modified field dataset, the probability of failure on the pipeline is calculated. Then, its residual useful life (RUL) is predicted according to ISO 16708 standard. As a result, the fitness-for-service of the test pipeline is well-confirmed. Conclusion: The framework described in ISO 13374 is applicable to the RUL prediction and the fitness-for-service assessment for gas pipelines. Therefore, the technology of prognostics is helpful for safe and efficient management of gas pipelines in Industry 4.0.

• Steel and Composite Structures
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• 제38권4호
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• pp.415-430
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• 2021

The effective flange width was usually introduced into elementary beam theory to consider the shear lag effect in steel-concrete composite beams. Previous studies have primarily focused on the effective width under positive moments and elastic loading, whereas it is still not clear for negative moment cases in the normal service stages. To account for this problem, this paper proposed simplified formulas for the effective flange width and reinforcement stress of composite beams under negative moments in service stages. First, a 10-degree-of-freedom (DOF) fiber beam element considering the shear lag effect and interfacial slip effect was proposed, and a computational procedure was developed in the OpenSees software. The accuracy and applicability of the proposed model were verified through comparisons with experimental results. Second, a method was proposed for determining the effective width of composite beams under negative moments based on reinforcement stress. Employing the proposed model, the simplified formulas were proposed via numerical fitting for cases under uniform loading and centralized loading at the mid-span. Finally, based on the proposed formulas, a simplified calculation method for the reinforcement stress in service stages was established. Comparisons were made between the proposed formulas and design code. The results showed that the design code method greatly underestimated the contribution of concrete under negative moments, leading to notable overestimations in the reinforcement stress and crack width.

• 대한영양사협회학술지
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• 제13권2호
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• pp.138-156
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• 2007

The purposes of this study were to a) measure the service quality attributes of foodservice type such as school foodservice, hospital foodservice and business & industry(B&I) foodservice, managed by contract management company(CMC), b) compare with service quality attributes by CMC scale, c) analyze overall customer satisfaction(CS) by the foodservice type and the CMC scale, and d) identify the effect of service quality attributes on an overall CS by the foodservice type and the CMC scale. The questionnaires were handed out to 6,620 customers of 207 school, 38 hospital, and 86 B&I foodservices in 108 CMCs. The statistical data analysis was completed using SPSS Win(ver 12.0) for descriptive analysis, t-test, reliability analysis, and multiple linear regression analysis. From an analysis on service quality attributes, 'proper arrangement of table and chair at hall distribution(3.53)', 'operation of nutrition education(3.50)' were highly perceived to student, 'correctable serving(4.08)', 'serve at fixed distribution time(4.08)', 'kindness of serving employee(4.04)' were highly perceived to patient, 'employee's kindness(3.84)' were highly perceived to customer of B&I. In comparison of service quality attributes by CMC scale, most scores of large enterprise(LE) were significantly higher than small and medium sized enterprise(SME) in school foodservice, hospital foodservice and B&I foodservice. Overall CS levels were 3.53 out of a maximum 5 on B&I, 3.46 on school, and 3.44 on hospital and were evaluated differently CS score by CMC scale. Finally, regression results for the effects of service quality attributes on overall CS by each of foodservice type were identified significantly different service quality attributes by foodservice type such as school, hospital, B&I(p<.001) and by CMC scale. For considering the goal of enterprise on profit-making through CS and the needs of customer on CS at moment of truth(MOT), the findings should be applied to the CMC and the foodservice industry.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.5541-5548
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• 2013

서비스의 속성상 어떠한 기업도 서비스 실패로부터 자유로울 수 없다. 때문에 이러한 서비스 실패를 적절하게 회복하기 위한 노력은 무엇보다 중요한 의미를 가지게 된다. 본 연구는 서비스 회복에 대한 대응 노력의 과정에서 서비스 실패의 상황을 심각성과 통제성으로 구분하였다. 이때, 공정성 지각이 신뢰와 만족에 미치는 영향과 더불어 종업원 진정성의 역할을 실증적으로 검증하여 중요성을 제시하고자 한다. 연구 대상은 서비스 불만을 제기한 경험이 있는 206명의 설문 자료를 SPSS, AMOS를 이용하여 분석하였다. 연구 결과를 요약하면 첫째, 서비스 실패 심각성은 공정성에 부(-)의 영향을 미치지 않았고, 서비스 실패 통제성만이 공정성에 부(-)의 영향을 미치는 것으로 나타났다. 둘째, 공정성 지각은 신뢰와 만족의 관계에서 정(+)의 영향을 미치는 것으로 나타났으며, 회복된 신뢰는 만족에 유의한 영향을 미치는 것으로 나타났다. 셋째, 심각성, 통제성, 공정성, 신뢰와 만족간의 구조적 관계에서 진정성에 의해 조절효과가 있는 것으로 나타났다. 이러한 연구 결과에 근거하여 시사점을 제시하고 미래 연구를 제안하였다.

• 한국치위생학회지
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• 제13권1호
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• pp.45-60
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• 2013

Objectives : The number of North Korean refugees is remarkably increasing nowadays and there are many social and cultural issues related to their settlements in Korea. Stereotyping of group is generally unique and has influences on emotions and behaviors. The aim of this study was to investigate the relationship among stereotyping, emotion and service behavior of South Korean dentist towards North Korean refugee. Methods : Questionnaires for stereotyping, emotions and service behaviors were devised based on previous researches. Two-hundred and eighteen Korean dentists were randomly chosen and questionnaires were distributed. Correlation analysis, reliability analysis and primary component analysis were performed. Student t-test and one-way ANOVA were done to elucidate differences according to demographic factors. To examine the relationship among constructs, regression analysis was performed. Results : Stereotyping, emotions, and service behaviors are significantly related each other construct. South Korean dentists' stereotyping and emotions toward North Korean refugees are significantly different from those toward South Korean but service behavioral intentions were not different according to any demographic factor. Conclusions : The results imply that more contacts and education system are necessary to South Korean dentists to change their negative stereotyping and emotions toward North Korean refugees although their service behaviors are not affected at the moment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.455-458
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• 1999

It has been known that buildings having inappropriate expansion joints in their spacings may be subject to exterior damages due to extensive cracks on the outer walls under service loads, and structural damages due to excessive moment induced by temperature changes at ultimate load conditions. Rather inconsistent code provisions are available regarding spacings of expansion joints from different foreign structural codes and even worse, no quantiative measure on spacings is given in our codes for building structures. In order to establish a rational measure on the spacing of expansion joints, theoretical approaches are taken in this study. The developed theoretical formula is, then, converted to design chart for structural designer's convenience in its use. The chart considers both service and ultimate load stages.