Unlike other facilities, maintaining processes is essential in industrial facilities. Pipe racks, which support pipes of various diameters, are important structures used in industrial facilities. Since the transport process of pipes directly affects the operation of industrial facilities, a fragility curve should be derived based on considering not only the pipe racks' structural safety but also the pipes' transport process. There are several studies where the fragility curves have been determined based on the structural behavior of pipe racks. However, few studies consider the damage criteria of pipes to ensure the transportation process, such as local buckling and tensile failure with surface defects. In this study, an analysis model of a typical straight pipe rack used in domestic industrial facilities is constructed, and incremental dynamic analysis using nonlinear response history analysis is performed to estimate the parameters of the fragility curve by the maximum likelihood estimation. In addition, the pipe rack's structural behavior and the pipe's damage criteria are considered the limit state for the fragility curve. The limit states considered in this paper to evaluate fragility curves are more reasonable to ensure the transportation process of the pipe systems.

In the automotive information display device industry, products with high reliability and wide temperature conditions are required, and interest in products that do not cause lighting defects even under extremely low temperature conditions is increasing. In this experiment, we produced an LED backlight unit for car navigation in a cryogenic environment. And to make this backlight unit, we used 12 side-emitting white LEDs with 3[W] high power LEDs. This backlight unit emits up to 18,000[nits] at a power consumption of 36[W] and has a startup voltage time of less than 1[ms] at -50° ambient temperature.

This study explores strategies to address the variability of heat energy using renewable energy and heat grids to achieve carbon neutrality. Renewable energy source introduce fluctuations that can impact the stability of power systems, while heat grids provide a systematic infrastructure for efficient supply of heat energy and power generation. Jeju Island is chosen as a case study, focusing on balance control based on groundwater-based geothermal energy to optimize the distribution of heat energy. The results demonstrate that the 3rd control method is the most effective in maintaining the target temperature in greenhouses, and specific temperature settings and objectives are proposed for each control method based on crop requirements. These research findings contribute to achieving carbon neutrality and reducing power consumption.

최적 운항자세 선정 기술이란 주어진 운항 배수량과 운항 선속에서 최소의 저항을 가지는 즉, 최적의 연료 소비 효율을 가지는 초기 선수흘수와 선미흘수를 제시하는 것이다. 본 논문의 주 목적은 대상선박의 유효동력 데이터를 기반으로 주어진 운항조건에서 최대 의 에너지효율을 가지는 최적의 운항자세를 선정하는 프로그램 개발하는 것이다. 본 프로그램은 인공지능 기법에 의한 파이썬 기반 GUI(Graphical User Interface)로 작성되어 선주가 쉽게 사용할 수 있도록 하였다. 그 과정에 있어 대상 선박 소개, 전산유체역학(CFD)을 통한 유효동력 데이터 수집, 심층학습을 사용한 유효동력 모델 학습 방법 그리고 심층신경망(DNN) 모델을 응용한 최적 운항자세 제시 프로그 램을 구체적으로 설명하였다. 선박은 운항 별로 화물을 싣고 내리게 되고, 이에 화물 적재량이 변화되고 배수량이 변경된다. 선주는 배수 량 별 예상 선속에 따라 최소저항을 가지는 즉, 최대의 에너지효율을 가지는 최적의 운항자세를 알고자 한다. 개발된 GUI는 해당선박의 태블릿 PC와 앱에 설치하여 최적 운항자세 선정에 활용 가능하다.

In order to solve the rapidly increasing domestic delivery volume and various problems in the recent metropolitan area, domestic researchers are conducting research on the development of “Urban Logistics System Using Underground Space” using existing urban railway facilities in the city. Safety analysis and scenario analysis should be performed for the safe system design of the new concept logistics system, but the scenario analysis techniques performed in previous studies so far do not have standards and are defined differently depending on the domain, subject, or purpose. In addition, it is necessary to improve the difficulty of clearly defining the control structure and the omission of UCA in the existing STPA safety analysis. In this study, an improved scenario table is proposed for the AGV horizontal transport device, which is a key equipment of an urban logistics system using underground space, and a process model is proposed by linking systematic STPA safety analysis and scenario analysis, and UCA and Control Structure Guidelines are provided to create a safety analysis.

As the capacity of renewable power generation facilities rapidly increases, the variability of electric power system and gas turbine power generation is also increasing. Therefore, problems may occur that require urgent repair while the gas turbine rotor is stopped. When the gas turbine rotor turning is stopped and then restarted, if the turning period is not appropriate, severe vibration may occur due to rotor bending. As a result of the experiment, it was confirmed that normal operation is possible when the gap data measured at the start of rotor turning after maintenance work is similar to the existing value. And the vibration value at the start of rotor turning was lower as the rotor temperature was lower or the stop period was shorter.

6·25전쟁 시 패퇴하던 북한군에게 있어 중국인민지원군의 지원은 절 대적이었다. 그러나 중국인민지원군은 조중연합사를 구성하여 조선인민 군을 통제하였고 김일성은 추락한 위상을 만회하고 군권을 장악하고자 조중연합사와 협력하고 갈등하며 북한군의 독자적인 군사전략 발전의 필 요성을 느꼈다. 따라서 본 논문은 북한의 주체적인 군사전략이 6·25전쟁 시 조중의 협력과 갈등의 결과로 창출된 것임을 제시하는 것을 목적으로 한다. 이를 위해 조중연합사 운용 간 조중이 협력한 사항과 갈등을 빚은 내용을 분석하고, 6·25전쟁 이후 조중의 협력과 갈등이 북한의 주체적 군사전략 발전에 미친 영향을 분석하였다. 연구 결과 6·25전쟁 중 조중 연합사 운용 간 조중의 협력과 갈등은 김일성으로 하여금 주체적인 군사 전략의 필요성을 인식하게 하였고, 김일성은 자위적 안보에 초점을 둔 배합전략과 속전속결전략의 군사전략을 채택하는 계기가 되었음을 확인 할 수 있었다. 또한 이와 같은 군사전략은 국제적 안보환경과 북한의 핵 무력 완성 등에 따라 다소 유동적일 수는 있어도 김일성 주체사상에 기 초한 배합전략과 속전속결전략은 변함없이 이어질 것으로 예견해 볼 수 있다. 이에 대한 대비가 요구되고 있다.

PURPOSES : This study establishes a methodology for evaluating traffic safety in response to the introduction of one-way traffic using surrogate safety measures and analyzes the impact of one-way traffic safety through a case analysis. METHODS : The SSAM(Surrogate Safety Assessment Measure) was used to analyze traffic conflicts (TTC(Time to Collision) and PET(Post Encroachment Time)), which are safety indicators. The SSAM input variable dataset was constructed using a VISSIM(Verkehr In Städten - SIMulationsmodell) simulation. RESULTS : Introducing one-way traffic rather than the pending issue (two-way operation) improved traffic safety as the possibility of TTC or PET was reduced. In addition, the analysis results showed that the average TTC time and average PET time increased with the introduction of the one-way system. It is anticipated that the avoidance action time taken by the driver to avoid dangerous situations will also increase, which will help improve traffic safety. CONCLUSIONS : As an alternative to solving traffic safety and communication problems occurring at the study site, it was determined that a one-way system would be effective. Furthermore, a one-way system that allows two-lane roads on both sides to move one-way and allows parking in pockets on both sides of the road would be appropriate.

PURPOSES : This paper proposes an artificial neural network (ANN)-based real-time traffic signal time design model using real-time field data available at intersections equipped with smart intersections. The proposed model generates suitable traffic signal timings for the next cycle, which are assumed to be near the optimal values based on a set of counted directional real-time traffic volumes. METHODS : A training dataset of optimal traffic signal timing data was prepared through the CORSIM Optimal Signal Timing program developed for this study to find the best signal timings, minimizing intersection control delays estimated with CORSIM and a heuristic searching method. The proposed traffic signal timing design model was developed using a training dataset and an ANN learning process. To determine the difference between the traditional pre-time model primarily used in practice and the proposed model, a comparison test was conducted with historical data obtained for a month at a specific intersection in Uiwang, Korea. RESULTS : The test results revealed that the proposed method could reduce control delays for most of the day compared to the existing methods, excluding the peak hour periods when control delays were similar. This is because existing methods focus only on peak times in practice. CONCLUSIONS : The results indicate that the proposed method enhances the performance of traffic signal systems because it rapidly provides alternatives for all-day cycle periods. This would also reduce the management cost (repeated field data collection) required to increase the performance to that level. A robust traffic-signal timing design model (e.g., ANN) is required to handle various combinations of directional demands.

One aspect of securing safety from the operation of Nuclear Power Plants (NPPs) is to evaluate the impact on residents at the facility’s exclusive area boundary to confirm that the radiological risk is below the allowable level. Normally, the risks from gaseous and liquid effluents are evaluated during the operation of facilities. Meanwhile, in order to be approved for the decommissioning plan, the environmental risks caused by activities during dismantling is also evaluated. Therefore, this study aims to investigate the exposure pathways considered in evaluating the risks to nearby residents from the operation and decommissioning of nuclear facilities and to examine the differences. The emission rate by radionuclide is calculated by evaluating the amount of leak from nuclear fuel during the operation of the facility through design data of the NPP. Each of the liquid and gaseous effluents is calculated, and the exposure dose received by nearby residents is calculated by considering the exposure pathways with these emission rates. In order to initiate the decommissioning of nuclear facilities, approval of the Final Decommissioning Plan (FDP) must be obtained. The FDP chapter shall describe the results of the environmental impact assessment of the decommissioning. It will not differ significantly in the exposure pathways during operation. However, the decommissioning of nuclear facilities is ultimately to remove Systems, Structures, and Components (SSCs) and to remove the regulation of the Nuclear Safety Act by ensuring that sites and remaining buildings meet the criteria for the license termination. In terms of release and reuse of nuclear facilities, the exposure dose to be considered in evaluating the dose can be considered for two main types: the site and the remaining building. The factors affecting the exposure pathways considered in assessing the environmental impacts considered in the operation and decommissioning of nuclear facilities are due to gaseous and liquid effluents. However, the difference should reflect the impact of NPP operations and decommissioning activities when evaluating the amount of radionuclides released by these effluents. Decommissioning should consider the impact after decommissioning, which is the effect of the receptor by radionuclides remaining on the site and in the remaining buildings. At this time, the effects of the source from the soil and the source from the surface of the building should be considered for the external and internal exposure pathways.

Among domestic Nuclear Power Plants (NPPs), there are a total of 10 nuclear power plants whose operating license expires by 2030, excluding Kori unit 1 and Wolsong unit 1, which are permanently shut downed. Continued operation of these nuclear power plants is being reviewed as a government task. For continued operation, nuclear power plant owners must prepare periodic safety review and other evaluation reports to receive reviews to maintain safety even during continued operation. In the safety evaluation of NPP, it is important to refer to overseas cases and operation experiences. In this study, the matters of radioactive waste management for continued operation of NPP was considered by analyzing the safety evaluation reports and safety enhancements of license renewal of NPP in USA, Radioactive waste generated from NPPs can be classified into solid, liquid, and gaseous states. Radioactive waste generated during the operation and maintenance of power plants is classified, stored and treated in the radioactive waste management system according to the source. Equipment and monitors related to radioactive waste management are continuously operated, managed, inspected according to standards and maintain their original functions. Various activities to reduce the generation and emission of radioactive waste from NPPs are performed. After reviewing the NRC’s safety evaluation report on the application documents for license renewal of US NPPs (Sequoyah, Byron and braidwood) the evaluation details and matters requiring enhancement for the radioactive waste management system were confirmed. As a major check, selective leaching occurred in the body of the gray cast iron valve and the heat exchanger shell containing the copper alloy exposed to the radioactive waste liquid. Selective leaching causes loss of material and may interfere with the original function of the facility, so management is required. For the safe operation and management of NPPs, it is important to refer to overseas cases and experiences. Among the safety evaluations for the continued operation of domestic NPPs, in the field of the radioactive waste management system, if the case of the US NPP is referred to, the review by the regulatory body and the action taken by the licensee will be more efficient.

Hanford site has been operated since 1943 to produce the plutonium for nuclear weapons. Significant amount of radioactive wastes was generated by the nuclear weapons production process. The radioactive wastes are stored in 177 aged underground tanks. Due to the risk of leakage into the air and the Columbia River, the US DOE and EPA, and Washington State Department of Ecology organized the Tri-Party Agreement (TPA) to clean-up the Hanford site in 1989. The LAW (low-activity waste) vitrification facility named WTP (Waste Treatment Plant) is plan to vitrify about 212 million liters of radioactive waste. The US DOE announced that the world’s largest melter to vitrify the LAW was heated up on October 8, 2022.

Domestic nuclear power plants developed the scaling factors for the radioactive waste generated from 2004 to 2008 for the first time. Afterwards, the effectiveness of continuous application of the scaling factors have been evaluated for newly generated radioactive waste over the past two years. It was confirmed that most of the initially developed scale factors were effective within a factor of 10 principle, which is an acceptable range. The scaling factors were updated using the analysis data base from 2004 to 2016. A scaling factor refers to the calculated abundance ratio between Key (Easy-to- Measure) and DTM (Difficult-to-Measure) nuclide at the time of generation of radioactive waste based on the source term in the reactor of an operating nuclear power plant. The effectiveness of continuous application of scaling factors can be evaluated at regular intervals regardless of operation status or when there are events that change scaling factors during nuclear power plant operation, such as zinc injection, large-scale facility replacement, and long-term shutdown etc. Even in the case of a permanently shut down nuclear power plant in which fuel is withdrawn from the reactor and generation of new nuclides by nuclear fission and radiation has stopped, periodic verification is conducted to confirm whether the scaling factor developed before permanent shutdown can be effectively applied to the radioactive waste generated after permanent shutdown. However, depending on the nuclear power plant decommissioning strategy or conditions, the period of permanent shutdown prior to decommissioning can be very long, so preparations are needed to ensure the appropriateness of scaling factor operation. In the case of domestic nuclear power plants, Kori Unit 1, a light water reactor, was permanently shut down in June 2017, and as a heavy water reactor nuclear power plant, the permanent shutdown of Wolseong Unit 1 was finally decided in December 2019 after twists and turns including large-scale facility replacement and long-term shutdown. In this paper, we have predicted when the scaling factors will change significantly due to radioactive decay and the difference in halflife between the Key and DTM nuclides over time after permanent shutdown. We also have tried to find appropriate countermeasures for the operation of scaling factors during permanent shutdown period, such as updating scaling factors or applying correction factors.

It is important that the plasma torch used in the waste treatment field has a high output to increase throughput. In order to increase the output of the plasma torch, there is a method of increasing the current or extending the length of the plasma arc. Among these methods, high power can be easily achieved simply by increasing current, but it is difficult to ensure electrode life. Therefore, it is necessary to check the appropriate current and arc length conditions to achieve high power and stable operation. In this paper, the power performance according to the arc length, current, and operation mode was confirmed in the transfer mode plasma torch. The test conditions are the distance (arc length) between the plasma torch and the external electrode was set to 5-180 mm, and the current was set to be in the range of 90-460 A. As a result of the test, it was confirmed that the reverse polarity operation had a maximum output of 159 kW depending on the arc length and current, and the positive polarity operation had a maximum output of 138 kW. Through this result, it was confirmed that the arc length had an effect on increasing the output, and that the reverse polarity operation had a longer arc than the positive polarity operation.