• Nuclear Engineering and Technology
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• 제49권2호
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• pp.442-449
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• 2017

Risk management of the Fukushima Daiichi Nuclear Power Station decommissioning is a great challenge. In the present study, a risk management framework has been developed for the decommissioning work. It is applied to fuel assembly retrieval from Unit 3 spent fuel pool. Whole retrieval work is divided into three phases: preparation, retrieval, and transportation and storage. First of all, the end point has been established and the success path has been developed. Then, possible threats, which are internal/external and technical/societal/management, are identified and selected. "What can go wrong?" is a question about the failure scenario. The likelihoods and consequences for each scenario are roughly estimated. The whole decommissioning project will continue for several decades, i.e., long-term perspective is important. What should be emphasized is that we do not always have enough knowledge and experience of this kind. It is expected that the decommissioning can make steady and good progress in support of the proposed risk management framework. Thus, risk assessment and management are required, and the process needs to be updated in accordance with the most recent information and knowledge on the decommissioning works.

• 한국정밀공학회지
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• 제15권1호
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• pp.130-136
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• 1998

A procedure of stress and strength analysis has been proposed for the centrifuge rotor of composite materials of quasi-isotropic laminates. The goal in this study is to maximize the allowable rotating speed, that is, to minimize maximum strength ratio with the given path length by changing the geometric parameter-outer radius and ply angles in quasi-isotropic laminates. Optimum values of the geometric parameter-outer radius and ply angles are obtained by multilevel optimization. All the geometric dimensions and stresses are normalized such that the result can be extended to a general case. Two dimensional analysis at each cross section with an elliptic tube hole subjected to internal hydrostatic pressures by samples as well as the centrifugal body forces has been performed along the height to calculate the stress distribution with the plane stress assumption, and Tsai-Wu failure criterion is used to calculate the strength ratio. The maximum allowable rotating speed can be increased by changing the radii of the outer surface along the height with the maximum strength ratio under the unit value : The optimal number of ply angles maximizing the allowable rotating speed in quasi-isotropic laminates is found to be the half number of tube hole, and the optimal laminate rotation angle is the half of $[{\pi}/m]$. A $[{\pi}/3]$ laminate, for instance, is stronger than a $[{\pi}/4]$ laminate for the centrifuge rotor of 6 tube hole number even though they have the same stiffness.

• 대한간호학회지
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• 제34권2호
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• pp.290-296
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• 2004

Purpose: The purpose of this study was to develop a home care nursing network system for operating home care effectively and efficiently by utilizing a wire-wireless network and mobile computing in order to record and send patients' data in real time, and by combining the headquarter office and the local offices with home care nurses over the Internet. It complements the preceding research from 1999 by adding home care nursing standard guidelines and upgrading the PDA program. Method: Method/l and Prototyping were adopted to develop the main network system. Result: The detailed research process is as follows: 1 )home care nursing standard guidelines for Diabetes, cancer and peritoneal-dialysis were added in 12 domains of nursing problem fields with nursing assessment/intervention algorithms. 2) complementing the PDA program was done by omitting and integrating the home care nursing algorhythm path which is unnecessary and duplicated. Also, upgrading the PDA system was done by utilizing the machinery and tools where the PDA and the data transmission modem are integrated, CDMX-1X base construction, in order to reduce a transmission error or transmission failure.

• 한국의류학회지
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• 제35권7호
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• pp.841-855
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• 2011

This study examines the structured model of building fashion customer loyalty by service recovery and scrutinizes the effect of explanations on perceived justice and the proposed model. The data of a total of 300 women were collected through an online survey. Employing structural equation modeling, this study demonstrated that both distributive and interactional justice had a positive impact on customers' satisfaction with service encounter that subsequently led to overall satisfaction with the brand. Overall satisfaction influenced the attitudinal loyalty of customers that induced their behavioral loyalty. To examine the effect of explanations on perceived justice and the process of building fashion customer loyalty by service recovery, t-test and multi-group SEM were employed. The result displayed that the group who received explanations after service failure perceived higher level of justice than the one who did not. There was a significant difference between two groups on the direct path from interactional justice to overall satisfaction with the brand. This study clarifies how perceived justice influences fashion customer loyalty mediating by satisfaction in and confirms the critical role of explanations in service recovery context. By implying the understanding of the important role of explanations in service recovery context, this study provides fashion marketers with insight for delivering more successful service recovery strategies that enhance customer loyalty.

• 대한소아치과학회지
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• 제24권4호
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• pp.771-775
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• 1997

Ectopic eruption is defined as abnormal eruption and results in malpositioned teeth and abnormal root resorption of adjacent teeth. Ectopic eruption, first reported by Chapman, occurs in 3% of the population and that mostly in the maxilla. Etiologic factors include narrow maxilla, large maxillary teeth, retarded calcification of the first molar, inclined eruption path of the first molar and retruded position of the maxilla. Impaction of the second molar is rare and occurs mostly in the mandible. Major causes are large teeth and insufficient arch length. Halterman has devised a method of distalizing a ectopically erupting first molar by cementing a band on the second deciduous molar with a hook soldered and a button bonded to the occlusal surface of the first permanent molar. Ectopically erupted posterior teeth should be treated early to maintain normal development of the dentition, harmony of facial growth and occlusal support, a failure to do so could result in severe malocclusion, periodontal damage and continued root resorption of the adjacent teeth. Early detection and treatment is thus vital. The author is submitting this report as he has obtained favorable results in treating a patient who came to the SNUDH Dept. of Pediatric Dentistry complaining of the first molar by using a modified Halterman appliance.

• 대한토목학회논문집
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• 제7권2호
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• pp.21-28
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• 1987

본(本) 연구(硏究)는 불안정(不安定)현상을 포함한 대변위(大變位)를 고려한 해석(解析)에 8절점(節點) 등매개(等媒介) 변수요소(變數要素)를 적용하여 그 요소(要素)의 우수성을 증명하고 있다. 여기서 채택하고 있는 비선형(非線形) 공식(公式)은 Total Lagrangian 공식(公式)이며, 해석(解析)방법은 하중증분(荷重增分)을 병행한 Newton-Raphson 방법을 이용했다. 안정해석(安定解析)을 수행할 경우 비선형(非線形) 경로(經路)를 따라 반복함으로써 최종 파괴하중을 매 순간 측청할 수 있도록 프로그램을 작성했다. 검증(檢證)을 위해 등분포(等分布) 하중(荷重)을 받는 원개형(圓箇形)쉘, 축(軸)하중을 받는 단순지지(單純支持)형 평판, 그리고 등분포(等分布) 하중(荷重)을 받는 고정된 평판 등과 같은 예제를 수행하여 이론해(理論解) 및 다른 결과(結果)들과 비교 분석했다.

• Computers and Concrete
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• 제2권6호
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• pp.499-516
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• 2005

A composite model is used to represent the heterogeneity of plain concrete consisting of coarse aggregates, mortar matrix and the mortar-aggregate interface. The composite elements of plain concrete are modeled using triangular finite element units which have six interface nodes along the sides. Fracture is captured through a constitutive single branch softening-fracture law at the interface nodes, which bounds the elastic domain inside each triangular unit. The inelastic displacement at an interface node represents the crack opening or sliding displacement and is conjugate to the internodal force. The path-dependent softening behaviour is developed within a quasi-prescribed displacement control formulation. The crack profile is restricted to the interface boundaries of the defined mesh. No re-meshing is carried out. Solutions to the rate formulation are obtained using a mathematical programming procedure in the form of a linear complementary problem. An event by event solution strategy is adopted to eliminate solutions with simultaneous formation of softening zones in symmetric problems. The composite plain concrete model is compared to experimental results for the tensile crack growth in a Brazilian test and three-point bending tests on different sized specimens. The model is also used to simulate wedge-type shear-compression failure directly under the loading platen of a Brazilian test.

• 한국터널지하공간학회 논문집
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• 제19권6호
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• pp.1013-1028
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• 2017

본 논문은 원형 자유면을 이용한 암반 파쇄에 대한 수치해석적 연구이다. 암반 파쇄시 균열 발생에 대한 메커니즘을 알아보기 위하여 수치해석을 통해 응력 및 변형율 경로를 분석하였다. 수치해석 결과로부터 균열선의 주응력 분석으로 최대 주응력을 산출하여 취성 재료의 파괴와 균열 진전에 대하여 분석 규명하였다. 또한 본 연구결과를 통하여 암반파쇄시 균열 진전 방향이 전환되는 거동 메커니즘을 제시하였다.

• 전력전자학회논문지
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• 제10권1호
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• pp.61-69
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• 2005

NPC 인버터는 많은 수의 전력용 반도체 소자로 구성되어 있으므로 다른 고장의 유형보다 전력용 반도체 스위치의 고장 발생 가능성이 더욱 크다. 고장발생시에 시스템의 연속적인 운전을 위한 대책의 개발은 매우 필요하며, 이러한 고장은 제안된 방법을 이용함으로써 시스템의 고장 허용 능력을 향상할 수 있다. 제안된 방법은 하나의 전력용 반도체 고장발생시 고장난 전력용 반도체가 포함된 고장상을 직렬 연결된 커패시터의 접속점에 연결한 후 나머지 두상을 이용하여 제어함으로써 직류-링크 전압을 유지하고, 일정한 크기를 가지는 출력 부하상전류를 연속적으로 시스템에 공급할 수 있다. 제안된 방법은 몇가지 특별한 분야에서 값비싼 다른 대안책들보다 더 경제적인 대안이다.

• 한국통신학회논문지
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• 제41권2호
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• pp.238-240
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• 2016

최근 실시간 서비스에 대한 요구가 날로 증대 하면서 높은 가용성과 신뢰성 높은 서비스 제공이 중요한 쟁점으로 대두 되고 있다. 이런 면에서 실질적으로 데이터의 경로를 제어하는 라우터에 대한 가용성, 신뢰성 및 확장성이 매우 중요한 문제로 인식되고 있으며, 데이터 통신망에서 라우터의 장애로 발생하게 될 손실 비용을 최소화하기 위해 신뢰성 및 가용성을 향상시키기 위한 많은 방법들이 연구되고 있다. 본 논문에서는 여러 가지 라우팅 프로토콜 중, TCP(Transmission Control Protocol)를 이용하는 프로토콜인 BGP(Border Gateway Protocol)세션의 고가용성을 지원하기 위해 Docker 기반의 BGP 세션 절체방안에 대해 연구하였다.