• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.367-370
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• 2003

This study was carried out to suggest the effective reinforcing method which can evaluate the tensile capacity of cast-in-place anchor with cracks. Currently, cast-in-place anchor is used widely for the fastening of equipment in Korean NPPs. 26 test specimens with a single anchor under 4 cracked conditions are prepared using plain concrete. The distance between crack and anchor and reinforcing materials were selected as the main test variable. The tensile force was applied using a actuator with a capacity of 100 tonf using a displacement control method of 0.5 mm/min velocity. Test results from this result show the combination of carbon plate and epoxy will be more available for repair and reinforcement of equipment foundation system in NPPs. Further experimental work is indeed involving the epoxy injection effect and adjustment of reinforcing location of carbon sheet.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.601-604
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• 2006

Reinforcement corrosion is the most important durability problem of reinforced concrete structures. One of the important factors affecting the steel corrosion is carbonation. However, existing carbonation test takes several months to obtain the results. Therefore, in this study, new rapid carbonation test equipment for concrete was developed and its applicability was investigated. The testing period can be reduced by increasing $CO_2$ concentration up to 100% in the equipment. It is found from the test results that the carbonation depth of concrete specimens tested for 2 weeks was $3{\sim}5$ times greater than that of specimens tested by existing test method. In conclusion, it would be possible to get the reliable test results enough to evaluate the durability of concrete structures in a short-period.

• 한국구조물진단유지관리공학회 논문집
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• 제24권2호
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• pp.1-8
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• 2020

원자력발전소와 같은 발전플랜트 시설의 경우 건물 자체뿐만 아니라 내부에 설치된 비구조요소의 내진안정성 또한 중요하다. 특히, 전기기기가 부착되는 캐비닛 구조물 등은 지진에 대비하여 기능적 안전성이 확보되어야 한다. 이에 따라 본 연구에서는 기존 발전플랜트 내부에서 운용 중인 전기기기 캐비닛 구조물의 동특성을 파악하고, 동적거동 시 발생되는 응답 수준을 분석하였다. 그리고 내진보강 방법 중 제진 방식을 적용하기 위해 강재 플레이트 댐퍼를 채택하고 대상기기의 크기에 적합하게 조정하였다. 또한, 최적의 보강방안을 도출하기 위해 부착위치에 따른 변수를 설정하고 보강 전·후의 지진동 입력에 의한 응답에 대하여 분석하는 연구를 수행하였다.

• Design & Manufacturing
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• 제12권2호
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• pp.40-45
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• 2018

Recently, in construction equipment machinery production, development has focused on environmentally-friendly functions to improve existing production capacity. For excavators as well, emphasis has been placed on response to environmental regulations, miniaturization, and noise reduction, while technology is being developed considering cost reduction and safety.Accordingly, the front support, an inner reinforcement part of the excavator, as well as high-strength steel plates to improve safety and reduce weight, are being applied.However, in the case of high-strength materials, Springback occurs in the final formed part due to high residual stress during product forming. Derivation of a forming or product shaping process to reduce springback is needed. Accordingly, regarding the front support, an inner reinforcement part of the excavator, this study derived a method to improve springback and secure shape stiffness through analysis of the springback occurrence rate and springback causes through a forming analysis.As for the results of analyzing the springback occurrence rate of existing products through forming analysis, springback of -22.6 mm < z < 27.35 mm occurred on the z-axis, and it was confirmed that springback occurred due to the stiffness reinforcing bead of the upper and middle parts of the product.To control product residual stress and springback, we confirmed a tendency of springback reduction through local pre-cutting and stiffness reinforcement bead relocation.In the local pre-cutting model, springback was slightly reduced by 5.3% compared with the existing model, an insignificant reduction effect. In the stiffness reinforcement bead relocation model, when an X-shaped stiffness reinforcement bead was added to each corner portion of the product, springback was reduced by at least 80%.The X-shaped bead addition model was selected as the springback reduction model, and the level of stiffness compared to the existing model was confirmed through a structural analysis.The X-shaped bead additional model showed a stress springback of 90% and springback reduction of 7.4% compared with the existing model, indicating that springback and stiffness will be reinforced.

• 한국실내디자인학회논문집
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• 제22권2호
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• pp.211-219
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• 2013

The purpose of this study is to propose the environmental planning guidelines of elementary school settings for a crime safety. The research methodologies To achieve the goal, the literature review analysis and the survey were used as main research methodologies. The survey is organized as follows. First, elementary education facilities were divided into 20 spaces based on the major space. Second, after analyzing the domestic and foreign CPTED Guidelines, elements of environmental planning were classified to fit in the space. Based on this, the expert survey was conducted. The results of this study are as follows; First, it is necessary to consider specific places such as 'toilets', 'parking lot', 'in-between space', 'main access road', 'sub-access road' and 'harmful facilities around school' for safer school environment. Second, it is significant to plan 'equipment facilities' and 'outdoor space in the school setting' with priority for elementary education environment. Third, environmental planning elements for safer elementary schools can be classified into 9 factors(types) including 'natural surveillance planning', 'territoriality reinforcement planning', 'mechanical surveillance planning', 'access control planning' and 'neighborhood reinforcement planning'. Forth, regarding 'indoor space', crime-free elementary school environment can be build through 'natural surveillance planning' and 'territoriality reinforcement planning'. Finally, regarding 'outdoor space', the crime can be prevented through 'natural surveillance planning' and 'access control planning'.

• 인터넷정보학회논문지
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• 제23권5호
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• pp.17-23
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• 2022

Network slicing is a promising paradigm and significant evolution for adjusting the heterogeneous services based on different requirements by placing dynamic virtual network functions (VNF) forwarding graph (VNFFG) and orchestrating service function chaining (SFC) based on criticalities of Quality of Service (QoS) classes. In system architecture, software-defined networks (SDN), network functions virtualization (NFV), and edge computing are used to provide resourceful data view, configurable virtual resources, and control interfaces for developing the modified deep reinforcement learning agent (MDRL-A). In this paper, task requests, tolerable delays, and required resources are differentiated for input state observations to identify the non-critical/critical classes, since each user equipment can execute different QoS application services. We design intelligent slicing for handing the cross-domain resource with MDRL-A in solving network problems and eliminating resource usage. The agent interacts with controllers and orchestrators to manage the flow rule installation and physical resource allocation in NFV infrastructure (NFVI) with the proposed formulation of completion time and criticality criteria. Simulation is conducted in SDN/NFV environment and capturing the QoS performances between conventional and MDRL-A approaches.

• 로봇학회논문지
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• 제17권1호
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• pp.1-7
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• 2022

Robots are widely used in industries and services. Traditional robots have been used to perform repetitive tasks in a fixed environment, and it is very difficult to solve a problem in which the physical interaction of the surrounding environment or other objects is complicated with the existing control method. Reinforcement learning has been actively studied as a method of machine learning to solve such problems, and provides answers to problems that robots have not solved in the conventional way. Studies on the learning of all physical robots are commonly affected by noise. Complex noises, such as control errors of robots, limitations in performance of measurement equipment, and complexity of physical interactions with surrounding environments and objects, can act as factors that degrade learning. A learning method that works well in a virtual environment may not very effective in a real robot. Therefore, this paper proposes a weighted sum method and a linear regression method as an effective and accurate learning method in a noisy environment. In addition, the bottle flipping was trained on a robot and compared with the existing learning method, the validity of the proposed method was verified.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.1959-1974
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• 2024

Nuclear energy plays a crucial role in energy supply in the 21st century, and more and more Nuclear Power Plants (NPPs) will be in operation to contribute to the development of human society. However, as a typical complex system engineering, the operation and development of NPPs require efficient and stable control methods to ensure the safety and efficiency of nuclear power generation. Reinforcement learning (RL) aims at learning optimal control policies via maximizing discounted long-term rewards. The reward-oriented learning paradigm has witnessed remarkable success in many complex systems, such as wind power systems, electric power systems, coal fire power plants, robotics, etc. In this work, we try to present a systematic review of the applications of RL on these complex systems, from which we believe NPPs can borrow experience and insights. We then conduct a block-by-block investigation on the application scenarios of specific tasks in NPPs and carried out algorithmic research for different situations such as power startup, collaborative control, and emergency handling. Moreover, we discuss the possibilities of further application of RL methods on NPPs and detail the challenges when applying RL methods on NPPs. We hope this work can boost the realization of intelligent NPPs, and contribute to more and more research on how to better integrate RL algorithms into NPPs.

• 한국압력기기공학회 논문집
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• 제6권1호
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• pp.72-77
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• 2010

During the period of reinforcement work for the licensing renewal of CANDU NPP, the fuel channels, Calandria tubes and feeders of CANDU Reactor are replaced. The remote visual inspection of Calandria internal is also performed during the period of reinforcement work. This period is a unique opportunity to inspect the inside of the Calandria. The visual inspection for the Calandria vessel and its internals of Wolsong NPP Unit 1 was performed by Nuclear Engineering & Technology Institute(NETEC) of KHNP. To perform this inspection, NETEC developed equipment applied new technology such as the synchronization of 3D CAD, automatic alignment and control system. The inspection confirmed that the Calandria integrity of Wolsong NPP Unit 1 is perfect.

• 동력기계공학회지
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• 제18권6호
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• pp.180-185
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• 2014

Due to the larger and high-speed vessels recently constructed, output and speed of the engines for propulsion or power generation is increasing. These high-power and high-speed engine of the ship is becoming as a major contributor causing excessive noise and vibration. Other fittings as well as equipment installed on board, it makes equipment failure or other defect by resonance. This causes a lot of M/H(Man Hour) for repairs and the reliability of the company is invading even be negative because the clients give much comment. Thus, it's being studied for any fittings installed on board to maintain the safe operation and to prevent any problem during the performance in any operating conditions. In this study, it was investigated to solve these problems for the supports of the various fittings for easy installation-related support that each type of intensity and shape and manufacturing method using structural analysis program(DNV Nauticus Hull 3D Beam). Namely, it would be applied to the very large crude carriers in consideration of mechanics of materials of the support equipment by providing the fact that dynamics analysis of the structural characteristics of the equipment and the support of the production installation is easy and productivity can be high standards for geometry and thereby to simplify the analysis task to design changes at the same time and to minimize the reinforcement for the supports.