• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.398-406
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• 2013

Afforestation/reforestation (A/R) clean development mechanism (CDM) is the only forestry-based activities allowed under the Kyoto protocol. This study was conducted to develop a methodology to estimate greenhouse gas (GHG) removals of a small scale A/R CDM pilot project in Goseong, Gangwon Province, Korea. AR-AMS0001 was applied as a methodology and selected tree species were Pinus koraiensis, Larix kaempferi, and Betula platyphylla for total area of 75.0 ha. To improve the accuracy on the GHG removals estimation, selection of the baseline scenario and carbon pools and stratification of the project site were conducted. Based on the developed methodology, net anthropogenic GHG removals were estimated as actual net GHG removals, subtracted by baseline net greenhouse gas removals and leakage. As a result, anthropogenic GHG removals of the project were 12,415 ton $CO_2-e$ and 165.5 ton $CO_2-e/ha$. This project is the first A/R CDM in domestic site and could enhance the technical accuracy of the GHG removals estimation by using countryspecific data reflecting the site condition.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.993-1001
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• 2024

The TANDEM project is a European initiative funded under the EURATOM program. The project started on September 2022 and has a duration of 36 months. TANDEM stands for Small Modular ReacTor for a European sAfe aNd Decarbonized Energy Mix. Small Modular Reactors (SMRs) can be hybridized with other energy sources, storage systems and energy conversion applications to provide electricity, heat and hydrogen. Hybrid energy systems have the potential to strongly contribute to the energy decarbonization targeting carbon-neutrality in Europe by 2050. However, the integration of nuclear reactors, particularly SMRs, in hybrid energy systems, is a new R&D topic to be investigated. In this context, the TANDEM project aims to develop assessments and tools to facilitate the safe and efficient integration of SMRs into low-carbon hybrid energy systems. An open-source "TANDEM" model library of hybrid system components will be developed in Modelica language which, by coupling, will extend the capabilities of existing tools implemented in the project. The project proposes to specifically address the safety issues of SMRs related to their integration into hybrid energy systems, involving specific interactions between SMRs and the rest of the hybrid systems; new initiating events may have to be considered in the safety approach. TANDEM will study two hybrid systems covering the main trends of the European energy policy and market evolution at 2035's horizon: a district heating network and power supply in a large urban area, and an energy hub serving energy conversion systems, including hydrogen production; the energy hub is inspired from a harbor-like infrastructure. TANDEM will provide assessments on SMR safety, hybrid system operationality and techno-economics. Societal considerations will also be encased by analyzing European citizen engagement in SMR technology safety.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.10
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• pp.673-679
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• 2016

Because of the growing interest in supercritical carbon dioxide power cycle technology owing to its potential enhancement in compactness and efficiency, supercritical carbon dioxide cycles have been studied in the fields of nuclear power, concentrated solar power (CSP), and fossil fuel power generation. This study introduces the current status of the research project on the supercritical carbon dioxide power cycle by Korea Institute of Energy Research (KIER). During the first phase of the project, the un-recuperated supercritical Brayton cycle test loop was built and tested. In phase two, researchers are designing and building a supercritical carbon dioxide dual Brayton cycle, which utilizes two turbines and two recuperators. Under the simulation condition considered in this study, it was confirmed that the design parameter has an optimal value for maximizing the net power in the supercritical carbon dioxide dual cycle.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.547-553
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• 2024

Hydrogen is considered a key energy source to achieve carbon neutrality through the global goal of 'Net Zero'. Due to limitations in domestic green hydrogen production, Korean companies are interested in importing green hydrogen produced overseas. Because Australia and the Middle East possess high-quality renewable energy resources, they are attracting attention as suitable regions for producing green hydrogen using renewable energy. The cost of constructing and operating a green ammonia plant varies depending on the region. In this study, an economic feasibility comparison of green ammonia plant construction in Australia and the Middle East is conducted. Through this, it is expected to contribute to the economic analysis and feasibility analysis of the project to import hydrogen in the form of green ammonia into Korea.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.1307-1307
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• 2024

Recent research on heavy equipment has been conducted for the purposes of enhanced safety, productivity improvement, and carbon neutrality at construction sites. A sensor-based approach is being explored to monitor the location and movements of heavy equipment in real time. However, it poses significant challenges in terms of time and cost as multiple sensors should be installed on numerous heavy equipment at construction sites. In addition, there is a limitation in identifying the collaboration or interference between two or more heavy equipment. In light of this, a vision-based deep learning approach is being actively conducted to effectively respond to various working conditions and dynamic environments. To enhance the performance of a vision-based activity recognition model, it is essential to secure a sufficient amount of training datasets (i.e., video datasets collected from actual construction sites). However, due to safety and security issues at construction sites, there are limitations in adequately collecting training dataset under various situations and environmental conditions. In addition, the videos feature a sequence of multiple activities of heavy equipment, making it challenging to clearly distinguish the boundaries between preceding and subsequent activities. To address these challenges, this study proposed a domain adaptation in vision-based transfer learning for automated excavator activity recognition utilizing 3D ResNet (residual deep neural network). Particularly, this study aimed to identify the optimal depth of 3D ResNet (i.e., the number of layers of the feature extractor) suitable for domain adaptation via fine-tuning process. To achieve this, this study sought to evaluate the activity recognition performance of five 3D ResNet models with 18, 34, 50, 101, and 152 layers, which used two consecutive videos with multiple activities (5 mins, 33 secs and 10 mins, 6 secs) collected from actual construction sites. First, pretrained weights from large-scale datasets (i.e., Kinetic-700 and Moment in Time (MiT)) in other domains (e.g., humans, animals, natural phenomena) were utilized. Second, five 3D ResNet models were fine-tuned using a customized dataset (14,185 clips, 60,606 secs). As an evaluation index for activity recognition model, the F1 score showed 0.881, 0.689, 0.74, 0.684, and 0.569 for the five 3D ResNet models, with the 18-layer model performing the best. This result indicated that the activity recognition models with fewer layers could be advantageous in deriving the optimal weights for the target domain (i.e., excavator activities) when fine-tuning with a limited dataset. Consequently, this study identified the optimal depth of 3D ResNet that can maintain a reliable performance in dynamic and complex construction sites, even with a limited dataset. The proposed approach is expected to contribute to the development of decision-support systems capable of systematically managing enhanced safety, productivity improvement, and carbon neutrality in the construction industry.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1244-1249
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• 2023

Recently, the Kingdom of Saudi Arabia (KSA) announced the development of first-of-a-kind(FOAK) and most advanced futuristic vertical city and named as 'The LINE'. The project will have zero carbon dioxide emissions and will be powered by clean energy sources. Therefore, a study was designed to understand which clean energy sources might be a better choice. Because of its nearly carbon-free footprint, nuclear energy may be a good choice. Nowadays, the development of very small modular reactors (vSMRs) is gaining attention due to many salient features such as cost efficiency and zero carbon emissions. These reactors are one step down to actual small modular reactors (SMRs) in terms of power and size. SMRs typically have a power range of 20 MWe to 300 MWe, while vSMRs have a power range of 1-20 MWe. Therefore, a study was conducted to discuss different vSMRs in terms of design, technology types, safety features, capabilities, potential, and economics. After conducting the comparative test and analysis, the fuel cycle modeling of optimal and suitable reactor was calculated. Furthermore, the levelized unit cost of electricity for each reactor was compared to determine the most suitable vSMR, which is then compared other generation SMRs to evaluate the cost variations per MWe in terms of size and operation. The main objective of the research was to identify the most cost effective and simple vSMR that can be easily installed and deployed.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.41-48
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• 2024

The construction industry is a significant contributor to carbon emissions, with its life cycle emissions posing significant environmental challenges. Despite its increasing importance, embodied carbon (EC) generated from the construction process is often ignored. Modular construction (MC), characterized by a combination of off-site manufacturing and on-site assembly, has been recognized for its potential to contribute to environmental benefits. However, there is still a lack of systematic explanation of urban high-rise MC. This study aims to identify whether and to what extent high-rise MC can achieve EC reductions and lay the foundation for effective carbon reductuons in the construction industry. To achieve this, the study develops a multi-level EC measurement framework for assessing EC during the construction process, using a real case to quantify the EC and determine carbon reduction performance. The innovation is a more comprehensive understanding of the boundaries of EC, as MC includes the amount of superstructure work and decoration integration. The results show that although the MC will increase EC from the transportation stage due to heavier modules, it achieves a net reduction in total EC by reducing on-site machinery energy consumption and waste rates. In conclusion, this study contributes to a better understanding of the EC emissions associated with high-rise MC, offering a valuable measurement framework for global regions evaluating the EC impacts of high-rise MC in similar contexts.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.1010-1018
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• 2017

The European Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste project sought to develop best practices in the retrieval, treatment, and disposal of irradiated graphite including other irradiated carbonaceous waste such as structural material made of graphite, nongraphitized carbon bricks, and fuel coatings. Emphasis was given on legacy irradiated graphite, as this represents a significant inventory in respective national waste management programs. This paper provides an overview of the characteristics of graphite irradiated during its use, primarily as a moderator material, within nuclear reactors. It describes the potential techniques applicable to the retrieval, treatment, recycling/reuse, and disposal of these graphite wastes. Considering the lifecycle of nuclear graphite, from manufacture to final disposal, a number of waste management options have been developed. These options consider the techniques and technologies required to address each stage of the lifecycle, such as segregation, treatment, recycle, and ultimate disposal in a radioactive waste repository, providing a toolbox to aid operators and regulators to determine the most appropriate management strategy. It is noted that national waste management programs currently have, or are in the process of developing, respective approaches to irradiated graphite management. The output of the Treatment and Disposal of Irradiated Graphite and other Carbonaceous Waste project is intended to aid these considerations, rather than dictate them.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4067-4071
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• 2021

The ¹³C (α,n)¹⁶O reaction cross-section is important data for nuclear physics, astrophysical, and neutrino physics experiments, however, they exhibit uncertainties due to the discrepancies in the experimental data. In this study, using the Nedis-2m program code, the energy spectrum of α-induced neutrons in a thin carbon target was calculated and the corresponding reaction cross-section was refined in the alpha particle energy range of 5-8 MeV. The results were used to calculate the intensity and energy spectrum of background neutrons produced in the liquid scintillator of KamLAND. The results will be useful in a variety of astrophysical and neutrino experiments especially those based on LS or Gd-LS detectors.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.177-185
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• 2022

In this study, the economic feasibility of a local energy facility that uses forest biomass as an energy source was assessed. We analyzed profitability using data from the Forest Energy Self-sufficient Village Project financed by the Korea Forest Service. The energy facility has a cogeneration generator and wood chip boiler. Wood chip, which has lower heat value and is cheaper than wood pellets, is used as fuel. Revenue comes from the sale of electricity, heat, and renewable energy certificates. Additionally, we considered the sale of carbon credits as substitutes for fossil fuels. The expenditure consists of fuel costs and fixed costs, and the initial investment is treated as a sunk cost. Under the condition of a 55% operation rate and wood chip price of 95,000 KRW per ton, the annual net revenue is positive. Crucial factors for managing the facility sustainably are operation rate and fuel cost. A simulation in which two factors were changed showed that the annual net revenue is negative with a 50% operation rate and 100,000 KRW per ton of wood chip price. To improve net revenue, an increase in the operation rate or a decrease in the wood chip price is required. Additionally, selling carbon credits will make the operation of the facility more profitable. Furthermore, the payment required to procure wood chips could contribute to the rural economy. To foster the use of forest biomass for energy, the price for heat supplied from renewable energy sources should be subsidized.