• 한국항행학회논문지
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• 제10권3호
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• pp.226-234
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• 2006

항로표지는 해상에서의 인명과 재산의 안전을 확보하기 위하여 매우 중요한 항행지원시설이다. 하지만 이 시설을 설계하고 설치 및 관리 그리고 이용하는 과정에서 매체별 또는 관리주체별로 서로 상이한 위치정보를 포함하고 있다. 항로표지의 위치신뢰도에 가장 영향을 미치는 요인으로서는 조류의 방향과 수심의 함수가 생성하는 선회반경이 있고, 위치측정의 주요 수단인 수평육분의 및 dGPS로 인한 시점별 변수가 있다. 본 논문은 이러한 잠재오차를 수치적으로 해석하고, 요인별 영향력과 감소방안을 제시하였다.

• Nuclear Engineering and Technology
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• 제52권5호
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• pp.889-896
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• 2020

The vertically inverted U-tube steam generator (UTSG) is widely used in the pressurized water reactor (PWR). The reverse flow behavior generally exists in some U-tubes of a steam generator (SG) under both single- and two-phase natural circulations (NCs). The behavior increases the flow resistance in the primary loop and reduces the heat transfer in the SG. As a consequence, the NC ability as well as the inherent safety of nuclear reactors is faced with severe challenges. The theoretical models for calculating single- and two-phase flow pressure drops in U-tubes are developed and validated in this paper. The two-phase reverse flow characteristics in two types of SGs are investigated base on the theoretical models, and the effects of the U-tube height, bending radius, inlet steam quality and primary side pressure on the behavior are analyzed. The conclusions may provide some promising references for SG optimization to reduce the disadvantageous behavior. It is also of significance to improve the NC ability and ensure the PWR safety during some accidents.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1279-1288
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• 2019

The vortex-type fluidic diode (FD) is a key safety component for inherent safety in various advanced reactors such as the sodium fast reactor (SFR) and the molten salt reactor (MSR). In this study, topology optimization is conducted to optimize the design of the vortex-type fluidic diode. The optimization domain is simplified to 2-dimensional geometry for a tangential port and chamber. As a result, a design with a circular chamber and a restrictor at the tangential port is obtained. To verify the new design, experimental study and computational fluid dynamics (CFD) analysis were conducted for inlet Reynolds numbers between 2000 and 6000. However, the results show that the performance of the new design is no better than the original reference design. To analyze the cause of this result, detailed analysis is performed on the velocity and pressure field using flow visualization experiments and 3-D CFD analysis. The results show that the discrepancy between the optimization results in 2-D and the experimental results in 3-D originated from exclusion of an important pressure loss contributor in the optimization process. This study also concludes that the junction design of the axial port and chamber offers potential for improvement of fluidic diode performance.

• 해양환경안전학회지
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• 제25권3호
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• pp.306-312
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• 2019

This paper investigates to design a controller for maritime autonomous surface ship (MASS) by means of adaptive super-twisting algorithm (ASTA). A input-out feedback linearization method is considered for multi-input multi-output (MIMO) system. Sliding Mode Controller (SMC) is suitable for MASS subject to ocean environments due to its robustness against parameter uncertainties and disturbances. However, conventional SMC has inherent disadvantages so-called, chattering phenomenon, which resulted from the high frequency of switching terms. Chattering may cause harmful failure of actuators such as propeller and rudder of ships. The main contribution of this work is to address an appropriate controller for MASS, simultaneously controls surge and yaw motion in severe step inputs. Proposed control mechanism well provides convergence bewildered by external disturbances in the middle of steady-state responses as well as chattering attenuation. Also, the adaptive algorithm is contributed to reducing non-overestimated value of control gains. Control inputs of surge and yaw motion are displayed by smoother curves without excessive control activities of actuators. Finally, no overshoot can be seen in transient responses.

• 대한안전경영과학회지
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• 제25권3호
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• pp.31-36
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• 2023

The use of hanging scaffolding for exterior wall painting and cleaning in building construction and maintenance carries the inherent risk of fall accidents. While periodic rope replacement is crucial for preventing accidents resulting from rope breakage, current regulations lack specificity in determining appropriate disposal period for fiber ropes. This study analyzed the tensile strength of the most commonly used PP fiber ropes with different diameters (16 mm, 20 mm) in the domestic construction industry. Additionally, the effect of outdoor exposure was examined by measuring the tensile strength of new ropes and ropes exposing to outdoor conditions for 30 days and 90 days. The results showed that the new ropes and those exposed to outdoor for 30 days met the KS (Korean Standards) criteria for tensile strength. However, a significant decrease in tensile strength was observed in ropes exposed to outdoor for 90 days compared to both the new ropes and those exposed for 30 days. Furthermore, the ropes exposed for 90 days did not meet the KS criteria. These findings indicate the degradation of PP fiber ropes due to UV (Ultra Violet) radiation, highlighting the importance of considering this factor when determining the replacement period for fiber ropes used in scaffolding work.

• 한국산업보건학회지
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• 제33권4호
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• pp.412-418
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• 2023

As advances in artificial intelligence (AI) increasingly approach areas once relegated to the realm of science fiction, there is growing public interest in using these technologies for practical everyday tasks in both the home and the workplace. This paper explores the applications of and implications for of using ChatGPT, a conversational AI model based on GPT-3.5 and GPT-4.0, in the field of occupational health and safety. After gaining over one million users within five days of its launch, ChatGPT has shown promise in addressing issues ranging from emergency response to chemical exposure to recommending personal protective equipment. However, despite its potential usefulness, the integration of AI into scientific work and professional settings raises several concerns. These concerns include the ethical dimensions of recognizing AI as a co-author in academic publications, the limitations and biases inherent in the data used to train these models, legal responsibilities in professional contexts, and potential shifts in employment following technological advances. This paper aims to provide a comprehensive overview of these issues and to contribute to the ongoing dialogue on the responsible use of AI in occupational health and safety.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2375-2387
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• 2024

The passive safety systems (PSSs) within water-cooled reactors are meticulously engineered to function autonomously, requiring no external power source or manual intervention. They depend exclusively on inherent natural forces and the fundamental principles of reactor physics, such as gravity, natural convection, and phase changes, to manage, alleviate, and avert the release of radioactive materials into the environment during accident scenarios like a loss-of-coolant accident (LOCA). PSSs are already integrated into such operating commercial reactors as the Advanced Pressurized Reactor-1000 MWe (AP1000) and the Water-Water Energetic Reactor-1200 MWe (WWER-1200) are adopted in most of the upcoming small modular reactor (SMR) designs. Examples of water-cooled SMR PSSs are the passive emergency core-cooling system (ECCS), passive containment cooling system (PCCS), and passive decay-heat removal system, the designs of which vary based on reactor system-design requirements. However, understanding the accident-event progression and phases of a LOCA is pivotal for adopting a specific PSS for a new SMR design. This study covers the accident-event progression for direct vessel injection (DVI) small-break loss-of-coolant accident (SB-LOCA), associated physics phenomena, knowledge gaps, and important figures of merit (FOMs) that may need to be evaluated and assessed to validate thermal-hydraulics models with an available experimental dataset to support new SMR design and development.

• 한국지진공학회논문집
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• 제12권2호
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• pp.33-44
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• 2008

교량, 항만 및 각종 구조물과 산업설비에 대한 설계는 주로 결정론적 해석방법(Deterministic Analysis)에 의해 수행되고 있다. 그러나 구조물에 내재된 확률변수의 불확실성에 대한 영향을 보다 명확하게 평가할 뿐만 아니라 경제적인 설계를 위해서는 보다 개선된 평가방안이 요구된다. 이 연구에서는 터빈발전기 기초를 대상으로 합리적인 설계를 위해 확률유한요소법을 이용한 구조신뢰성해석을 수행하였다. 이를 위해 확률유한요소법을 신뢰성이론에 적합하도록 정식화하였으며, 대상 구조물의 부재강성 및 지진하중 등을 확률변수로 고려하여 동적응답해석 및 구조신뢰성해석을 효율적으로 수행할 수 있는 개선된 해석프로그램을 작성하였다. 작성된 해석프로그램을 이용하여 주요부재의 변위 및 부재력 응답에 대한 분산특성을 검토하였다. 아울러, 구조신뢰성해석에 따른 신뢰성지수 및 파괴확률을 제시함으로써, 대상 구조물의 구조 안전성을 정량적으로 평가하였다. 이 연구결과는 향후, 터빈발전기 기초의 개선된 설계방안을 설정함에 있어 기초자료를 제공할 것으로 기대된다.

• 한국콘텐츠학회논문지
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• 제13권12호
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• pp.869-879
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• 2013

현대의학으로 아직 정복 하지 못한 암 질환에 대하여 치료행위 중 하나인 방사선치료에 참여하고 있는 전문직군에 대한 행위의 정당성과 적정 인력에 대하여 분석 하였다. 방사선종양학과(치료방사선과)가 설치된 의료기관에서 의학물리사의 역할이 현행 법 테두리 안에서 준 면허행위임에 틀림없으나 그 행위의 정당성을 부여받을 수 있는 현행 법 규정이 명확하지 않다. 따라서 국외 의학물리사의 인증자격 및 시험 등 제도를 조사하여 국내 규정에 반영할 수 있는 방안을 모색하였다. 더불어 의학물리사 행위가 위법성이 내재된 분야중 하나이기에 그 위법성을 조각할 수 있는 내용 중심으로 "의료법"과 "원자력안전법","의료분야의 방사선 안전관리에 관한 기술기준"에 따라 재해석 하였다. 결론적으로 "의료법"과 "의료분야의 방사선 안전관리에 관한 기술기준"에 합치되는 자격으로 인정하여, 증가하고 있는 방사선치료행위와 방사선 피폭의 안전관리에 대처해야 함이 타당할 것이다.

• 시스템엔지니어링학술지
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• 제11권2호
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• pp.13-29
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• 2015

With the era of big data, the big data has been expected to have a large impact in the NPP safety areas. Although high interests of the big data for the NPP safety, only a limited researches concerning this issue are revealed. Especially, researches on the logical/physical structure and systematic design methods for the big data platform for the NPP safety were not dealt with. In this research, we design a new big data pilot platform for the NPP safety especially focusing on health monitoring and early warning services. For this, we propose a tailored design process based on SE approaches to manage inherent high complexities of the platform design. The proposed design process is consist of several steps from elicitate stakeholders to integration test via define operational concept and scenarios, and system requirements, design a conceptual functional architecture, select alternative physical modules for the derived functions and assess the applicability of the alternative modules, design a conceptual physical architecture, implement and integrate the physical modules. From the design process, this paper covers until the conceptual physical architecture design. In the following paper, the rest of the design process and results of the field test will be shown.