• Corrosion Science and Technology
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• 제11권3호
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• pp.89-95
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• 2012

U.S. Electric Power Research Institute (EPRI) has developed CHECWORKS program and applied it to power plant piping lines since some lines were ruptured by flow-accelerated corrosion (FAC) in 1978. Nowadays the CHECWORKS program has been used to manage pipe wall thinning phenomena caused by FAC. However, various erosion mechanisms can occur in carbon-steel piping. Most common forms of erosion are cavitation, flashing, liquid droplet impingement erosion (LDIE), and Solid Particle Erosion (SPE). Those erosion mechanisms cause pipe wall thinning, leaking, rupturing, and even result in unplanned shutdowns of utilities. Especially, in two phase condition, LDIE damages a wide scope of plant pipelines. Furthermore, LDIE is the major culprit to cause such as power runback by pipe leaking. This paper describes the methodologies that manage wall thinning and also predict LDIE wall thinning area. For this study, current properties of two-phase condition are investigated and LDIE areas are selected. The areas are checked by B-Scan method to detect the effect of wall thinning phenomena.

• 한국안전학회지
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• 제26권6호
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• pp.45-53
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• 2011

This study was performed to develop repair and reinforcing materials in sewage drain pipe by using 40% of CAC(Calcium Aluminate Cement) and 4% of Polymer Powder. Regarding reinforcing materials to enhance load-bearing capacity, polyester textile and wire mesh were adopted and then they were evaluated by the measurement of deflection and Stress-strain Relationship. Two types of drain pipe made by concrete and PE were considered as plain specimens and then loading test were performed after repaired by CAC mortar impregnated reinforcing materials. As the test results of the load-bearing test on both drain pipe, there was higher load-bearing capacity on the specimen adopted wire mesh but debonding of repair mortar was found due to stiffness of wire mesh. By the way, repair system using CAC mortar impregnated polyster textile without wire mesh showed satisfactory results including bonding and load-bearing capacity regardless substrate, so this repair system using by mixture of CAC mortar and polyster textile is suggested as the reasonable repairing method within this experimental scope.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2198-2203
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• 2022

As robotics become more sophisticated, there are a growing number of generic systems being used for routine tasks in nuclear environments to reduce risk to radiation workers. The nuclear sector has called for more commercial-off-the-shelf (COTS) devices and components to be used in preference to nuclear specific hardware, enabling robotic operations to become more affordable, reliable, and abundant. To ensure reliable operation in nuclear environments, particularly in high-gamma facilities, it is important to quantify the tolerance of electronic systems to ionizing radiation. To deliver their full potential to end-users, mobile robots require sophisticated autonomous behaviors and sensing, which requires significant computational power. A popular choice of computing system, used in low-cost mobile robots for nuclear environments, is the UP Core single board computer. This work presents estimates of the total ionizing dose that the UP Core running the Robot Operating System (ROS) can withstand, through gamma irradiation testing using a Co-60 source. The units were found to fail on average after 111.1 ± 5.5 Gy, due to faults in the on-board power management circuitry. Its small size and reasonable radiation tolerance make it a suitable candidate for robots in nuclear environments, with scope to use shielding to enhance operational lifetime.

• Applied Microscopy
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• 제50권
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• pp.25.1-25.11
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• 2020

Scanning acoustic microscopy (SAM) or Acoustic Micro Imaging (AMI) is a powerful, non-destructive technique that can detect hidden defects in elastic and biological samples as well as non-transparent hard materials. By monitoring the internal features of a sample in three-dimensional integration, this technique can efficiently find physical defects such as cracks, voids, and delamination with high sensitivity. In recent years, advanced techniques such as ultrasound impedance microscopy, ultrasound speed microscopy, and scanning acoustic gigahertz microscopy have been developed for applications in industries and in the medical field to provide additional information on the internal stress, viscoelastic, and anisotropic, or nonlinear properties. X-ray, magnetic resonance, and infrared techniques are the other competitive and widely used methods. However, they have their own advantages and limitations owing to their inherent properties such as different light sources and sensors. This paper provides an overview of the principle of SAM and presents a few results to demonstrate the applications of modern acoustic imaging technology. A variety of inspection modes, such as vertical, horizontal, and diagonal cross-sections have been presented by employing the focus pathway and image reconstruction algorithm. Images have been reconstructed from the reflected echoes resulting from the change in the acoustic impedance at the interface of the material layers or defects. The results described in this paper indicate that the novel acoustic technology can expand the scope of SAM as a versatile diagnostic tool requiring less time and having a high efficiency.

• 대한심미치과학회지
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• 제29권1호
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• pp.4-12
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• 2020

Laminate veneer는 전부도재 크라운 보다 전.구치 포함 적용범위는 매우 넓다. 또한 치관 형성시 요구되는 시간이 단축되며 침습 또한 적은 장점이 있다. 그러므로 치은에도 우수한 심미성과 기능개선을 가능하게한다. 환자의 고통과 치질손실의 부담도 훨씬 줄일 수 있으므로 앞으로도 잔존 자연치아의 심미성과 기능개선의 중요한 역할을 담당할 것이라 생각한다.

• 인간식물환경학회지
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• 제22권5호
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• pp.467-480
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• 2019

Standard estimates are the numerical data of a unit quantity required for construction work such as the amount of materials, manpower, and the use of equipment required and are also a basis to calculate construction costs. Unfortunately, standard estimates for construction have also been used for garden construction these days as no standard estimates for garden construction have been developed or documented until now. As a result, many problems have arisen at garden construction sites since landscape construction and garden construction differ in terms of scope, size, design and construction methods. The purpose of this study was to develop standard estimates for garden construction for proper calculation of the cost of garden construction and to ensure gardens are created following appropriate construction processes. In order to develop standard estimates for garden construction, a preliminary survey was conducted on experts to understand current issues at first. After that, a questionnaire survey was done to examine problems of construction processes and ways of improvement, and on-site inspections were conducted utilizing CCTVs at construction sites to identify the actual amount of manpower required on site. Based on the results of the surveys and on-site inspections, a draft version of standard estimates for 5 types of planting work for garden construction was developed. Developing standard estimates for garden construction will serve as a stepping stone for the transparent and proper compensation for garden construction work, which will not only contribute to addressing issues between consumers and construction companies, but also to the stabilization of market economy and job creation.

• 대한인간공학회지
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• 제35권4호
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• pp.263-275
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• 2016

Objective: This paper introduces the regulatory oversight approaches and issues to consider in the course of safety culture oversight model development in the nuclear field. Common understanding on regulatory oversight and present practices of international communities are briefly reviewed. The nuclear safety culture oversight model of Korea is explained focusing on the development of safety culture definition and components, and their basic meanings. Oversight components are identified to represent the multiple human and organizational elements which can affect and reinforce elements of defense in depth system for nuclear safety. Result of validation study on safety culture components is briefly introduced too. Finally, the results of the application of the model are presented to show its effectiveness and feasibility. Background: The oversight of nuclear licensee's safety culture has been an important regulatory issue in the international community of nuclear safety regulation. Concurrent with the significant events that started to occur in the early 2000s and that had implications about safety culture of the operating organizations, it has been natural for regulators to pay attention to appropriate methods and even philosophy for intervening the licensee's safety culture. Although safety culture has been emphasized for last 30 years as a prerequisite to ensure high level of nuclear safety, it has not been of regulatory scope and has a unique dilemma between external oversight and the voluntary nature of culture. Safety culture oversight is a new regulatory challenge that needs to be approached taking into consideration of the uncontrollable aspects of cultural changes and the impacts on licensee's safety culture. Although researchers and industrial practitioners still struggle with measuring, evaluating, managing and changing safety culture, it was recognized that efforts to observe and influence licensees' safety culture should not be delayed. Method: Safety culture components which regulatory oversight will have to focus on are developed by benchmarking the concept of physical barriers and introducing the defense in depth philosophy into organizational system. Therefore, this paper begins with review of international regulatory oversight approaches and issues associated with the regulatory oversight of safety culture, followed by the development of oversight model. The validity of the model was verified by statistical analysis with the survey result obtained from survey administration to NPP employees in Korea. The developed safety culture oversight model and components were used in the "safety culture inspection" activities of the Korean regulatory body. Results: The developed safety culture model was confirmed to be valid in terms of content, construct and criterion validity. And the actual applicability in the nuclear operating organization was verified after series of pilot "safety culture inspection" activities. Conclusion: The application of the nuclear safety culture oversight model to operating organization of NPPs showed promising results for regulatory tools required for the organizations to improve their safety culture. Application: The developed oversight model and components might be used in the inspection activities and regulatory oversight of NPP operating organization's safety culture.

• 해양환경안전학회지
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• 제17권3호
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• pp.245-255
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• 2011

우리나라는 선박관리산업의 중요성을 인식한 해운업계 및 학술단체의 전문가들에 의해 지속적으로 노력한 결과 최근 국회의원의 발의에 의하여 "선박관리산업발전법안"이 제안되었다. 이러한 성과는 우리나라의 선박관리산업이 선진국 대열에 진입하게 되는 결정적인 계기가 된다고 생각한다. 이 연구는 최근 발의된 우리나라 "선박관리산업발전법안"을 각 조문별로 소개하고, 조문별 분석을 통해 법적인 문제점과 실효성을 검토하여 개선방안을 제시함으로써 향후 우리나라 선박관리산업의 발전을 위한 법과 제도의 발전에 기여하는 것을 궁극적인 목적으로 한다. 이를 위해 우리나라 "선박관리산업발전법안"의 구성, 목적, 용어의 정의, 다른 법률과의 관계 등을 중심으로 개념을 소개하고, 이 법률안의 핵심이라고 할 수 있는 선박관리산업의 육성 및 지원, 그리고 선박관리우수사업자의 인증을 중심으로 구체적 실효성을 분석하였다.

• 해양환경안전학회지
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• 제29권2호
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• pp.177-187
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• 2023

「선박안전법」은 선박의 감항성(堪航性, Seaworthiness) 유지 및 안전운항에 필요한 사항을 규정하고 있으며, 이와 관련해서 이 법 제10조에서는 선박소유자가 선박검사를 받은 후 해당 선박의 선박검사증서에 적혀 있는 내용을 일시적으로 변경하고자 하는 경우에 임시검사를 받도록 하고 있다. 이와 같은 조치는 이 법 제15조에 따른 선박검사 후 선박의 상태유지에 따른 것으로 여기에는 「항만법」 제39조제1항에 따른 "항만건설작업선"을 포함하고 있다. 그러나 항만건설작업선은 본래 부선(艀船)과 동일한 운용체계를 보이고 있음에도 불구하고 「선박안전법」을 적용받지 아니하고 「건설기계관리법」에 따른 등록 및 검사·점검을 받아오다 2012년 12월 14일 울산항만 내에서 작업 중 발생한 "석정36호" 침몰사고를 발단으로 2016년 「항만법」이 개정되면서 「선박안전법」에 추가해서 적용받게 된 점 등을 고려할 때 항만건설작업선을 「선박안전법」에서 정하고 있는 모든 규정을 따르도록 적용하는 것은 현실적 한계가 있다 할 것이다. 이에 따라 본 논문에서는 항만건설작업선의 개념, 등록, 작업구역, 검사규정, 임시변경 적용사례 등을 통한 작업특성 및 실제 항만건설작업선의 「선박안전법」 적용범위와 관련해서 논란이 되고 있는 사항 등에 대해 살펴보고, 또한 「항만법」의 개정에 따라 항만건설작업선을 「선박안전법」의 검사대상으로 편입하게 된 입법취지 등을 통해 「선박안전법」 제10조에서 규정하고 있는 임시검사 중 "임시변경"에 관한 사항을 적용하는데 있어서의 그 적정범위를 제시하고자 한다.

• 방사성폐기물학회지
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• 제13권2호
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• pp.163-169
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• 2015

국내 원자력발전소에서는 사용후핵연료 저장용량의 확대를 위해 사용후핵연료저장조에 조밀저장대를 설치하고 있지만 한빛원전은 2024년에 포화가 예상된다. 또한 10개의 원자력발전소가 2029년까지 설계수명에 도달하게 된다. 하지만 원전운영과 해체를 위한 국내 사용후핵연료 관리정책은 아직 결정되지 않은 상황이다. 미국의 경우 원전해체시 사용후핵연료를 중간 저장시설 또는 영구처분장으로 이송하기 전까지 임시적으로 독립된 사용후연료저장조(이하 'SFPI') 방식을 운영하는 사례가 있다. SFPI는 원전해체시 운전정지 후 사용후핵연료를 저장하는데 있어서 방사선 노출 저감, 운영비용 절감, 안전성 보강 등의 효과를 기대할 수 있다. 따라서 이 논문에서는 미국의 SFPI 운영경험, 시스템, 적용규정 등에 대한 사례연구를 수행하였다. 결론적으로 SFPI 국내 적용을 위해서는 사용후핵연료저장 계통의 설계변경 범위 및 예상 소요비용 확정, 원전 해체계획에 설비개선 계획 반영제출, 주기적안전성평가(PSR) 방법 등을 활용한 안전성 평가(운영기간 10 년), 설계변경을 위한 운영 변경허가 신청, 규제기관 심사 및 허가 취득, 설계변경 수행, 규제기관의 확인점검, SFPI 운영을 위한 교육 및 시운전, SFPI 운영 및 정기검사, SFPI 해체 등의 절차가 필요하다.