• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.9-17
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• 2019

Interest in renewable energy is rapidly growing around the world. One of the most popular renewable energy sources is solar power, and photovoltaic (PV) systems are the most representative route for generating solar energy. However, with the growing adoption of solar power systems, the demand for land on which to install these systems has increased, which has caused environmental degradation. Recently, floating PV systems have been designed to utilize idle water surface areas of dams, rivers, and oceans. Because floating PV systems will be exposed to harsh environmental stresses, the safety of such systems should be secured before installation. In this study, the structural robustness of a floating PV system was analyzed by conducting numerical simulation to investigate whether the system can withstand harsh environmental stresses, such as wind and wave loads. Additionally, conventional wind and wave load predictions based on the design method and the simulation results were compared. The comparison revealed that the design method overestimated wind and wave loads. The total drag of the PV system was significantly overestimated by the conventional design criteria, which would increase the cost of the mooring system. The simulation offers additional advantages in terms of identifying the robustness of the floating PV system because it considers real-world environmental factors.

• Safety and Health at Work
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• v.13 no.4
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• pp.421-428
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• 2022

Background: The exposure to solar ultraviolet radiation is a significant risk factor generally underestimated by outdoor workers and employers. Several studies have pointed out that occupational solar exposure increased eye and skin diseases with a considerable impact on the lives and productivity of affected workers. The main purpose of this study was to evaluate the effectiveness against ultraviolet radiation of some measures recently undertaken for the protection of lifeguards in a coastal area of Tuscany. Methods: Different shading structures (gazebos and beach umbrella) were tested during a sunny summer's day on a sandy beach by means of two radiometers; the UV protection offered by some T-shirts used by lifeguards was also tested in the laboratory with a spectrophotometer. Results: The analysed shading structures strongly reduced the ultraviolet radiation by up to 90%, however a not always negligible diffuse radiation is also present in the shade, requiring further protective measures (T-shirt, sunglasses, sunscreen, etc.); the tested T-shirts showed a very good-excellent protection according to the Australian/New Zealand standard. Conclusion: Results obtained in this study suggest how the adoption and dissemination of good practices, including those tested, could be particularly effective as a primary prevention for lifeguards who are subjected to very high levels of radiation for long periods.

• Electronics and Telecommunications Trends
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• v.38 no.4
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• pp.81-94
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• 2023

The increased adoption of open source security management in supply chains is gaining worldwide attention. In particular, as security and threatening situations, such as solar winds, Kaseya ransomware, and Log4j vulnerability, are becoming more common in supply chains using software (SW)-defined networks, SW bills of materials (SBOMs) for SW products should be prepared to protect major countries like the United States. An SBOM provides SW component information and is expected to become required for SW supply chain management. We focus on SW supply chain management policies and SBOM trends in major countries and private organizations worldwide for safe SW use and determine the current status of Korea and ETRI's open source SW supply chain management trends.

• KIEAE Journal
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• v.10 no.5
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• pp.3-12
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• 2010

Sustainable design is getting to be controversial issue in all industries over the world particularly, in architecture as the amount of energy usage in architecture occupies 40%. Therefore, it is essential to make the standard for the sustainable design. In order to construct the sustainable design, firstly it should be considered that sustainable design elements based on natural resources to increase building energy efficiency is established and classified. The method of sustainable design divides into passive design and active design. Passive design method should be examined with active one simultaneously for more efficient usage of energy. Next, the study is followed how the sustainable design elements is adopted in buildings through the comparison of cases study of domestic and oversea. The result of case study shows similar adoption of sustainable design elements between oversea and domestic. However, the difference is shown in the building orientation and shape and the window size and position in Solar energy as well as high performance structure in Heat energy. These elements are the most significant elements in order to reduce energy load. In oversea, sustainable design is generated by architects, a client, and consultants based on the close cooperation in the beginning of early design phase before deciding building shape and envelope while in the domestic field adoption for sustainable design is conducted after deciding building shape and material. In order to design sustainable architecture more study is necessary in early stage for Zero Carbon and reducing building energy load through relation with specialists, a client and architects.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.4
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• pp.251-255
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• 2021

a-Si is commonly considered as a primary candidate for the formation of passivation layer in heterojunction (HIT) solar cells. However, there are some problems when using this material such as significant losses due to recombination and parasitic absorption. To reduce these problems, a wide bandgap material is needed. A wide bandgap has a positive influence on effective transmittance, reduction of the parasitic absorption, and prevention of unnecessary epitaxial growth. In this paper, the adoption of a-SiO_x:H as the intrinsic layer was discussed. To increase lifetime and conductivity, oxygen concentration control is crucial because it is correlated with the thickness, bonding defect, interface density (D_it), and band offset. A thick oxygen-rich layer causes the lifetime and the implied open-circuit voltage to drop. Furthermore the thicker the layer gets, the more free hydrogen atoms are etched in thin films, which worsens the passivation quality and the efficiency of solar cells. Previous studies revealed that the lifetime and the implied voltage decreased when the a-SiOx thickness went beyond around 9 nm. In addition to this, oxygen acted as a defect in the intrinsic layer. The D_it increased up to an oxygen rate on the order of 8%. Beyond 8%, the D_it was constant. By controlling the oxygen concentration properly and achieving a thin layer, high-efficiency HIT solar cells can be fabricated.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.134-140
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• 2012

With rapid modernization and industrialization, many urban areas are becoming overcrowded at a rapid pace and such urban ecological problems as heat island effect are becoming serious due to the reduced green zones resulted from the indiscriminate development. To solve this problem, ecological park, constructed wetlands, and greening on the elevation, balcony, and roof of a building that have the structure and function very close to the state of nature are currently being promoted at the urban or regional level. Especially green roof will be able to not only provide the center of a city with a significant portion of green area but also help to relive heat island effect and improve micro climate by preventing concrete of a building from absorbing heat. According to a recent study, the temperature of green roof in the summer season shows a lower temperature than the outdoor temperature, but inversely the concrete surface shows a higher temperature. Accordingly, this study measured the surface temperature of buildings with green roof in Daejeon area in order to determine how the green roof system would have an impact on the distribution of surface temperature and did a comparative analysis of the distribution of the surface temperature of green roof vs non-green roof based on these theoretical considerations. As a result, it was found that the surface temperature of green roof was lower by $4{\sim}7^{\circ}C$ than that of non-green roof. This is expected to contribute to the mitigation of urban heat island effects.

• Journal of the Korean Solar Energy Society
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• v.39 no.6
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• pp.1-13
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• 2019

With the adoption of the Paris Agreement, a new climate regime is intensifying the global interest in reducing greenhouse gas emissions. In the meantime, Korea is preparing to introduce a new renewable energy carbon certification system in order to activate the use of renewable energy and to reduce carbon emissions in the entire life cycle of manufacturing and disposal of renewable energy facilities. Therefore, this study aims to identify the implications for the introduction of the carbon certification system and to establish a theoretical basis for the system design by examining the status of overseas carbon certification, international trade norms and trade disputes. As a result, carbon emissions certification is being implemented in developed countries such as EU, UK, France, USA and Japan, but only France, Germany and EU have adopted carbon certification for renewable energy sector. The analysis of the WTO TBT Agreement and GATT also confirmed the possibility of a violation of the international trade rules of the carbon certification system and derived nine international technical standards related to carbon certification. Finally, by examining the case of trade disputes related to environmental labeling, the minimum requirements to be considered at the institutional design stage were drawn to eliminate the possibility of trade disputes.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.1
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• pp.1-7
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• 2018

Objective signs are everywhere that the stationary energy storage market is growing up quickly. The use of distributed resources such as solar photovoltaics and electric vehicles are expanding at a rapid pace, creating technical challenges for the distribution system that will require energy storage and a new generation of software to address. This paper is intended for distribution utility managers and executives and makes the following points: ${\bullet}$ Utility-integrated (as opposed to merely grid-connected) energy storage projects represent a distinct, new wave of industry growth that is just getting underway and is required to manage distributed energy resources moving forward. ${\bullet}$ Utilities and the energy storage industry have important roles to lower risk in adopting this technology - thereby enabling this wave of growth. ${\circ}$ The industry must focus on engineering energy storage for adoption at scale - including the creation and support of software open standards -both to drive down costs and to limit technology and supplier risk for utilities. ${\circ}$ Utilities need to take a program-based, rather than a project- based, approach to this resource to best balance cost and risk as they procure and implement energy storage. By working together to drive down costs and manage risk, utilities and their suppliers can lay the energy storage foundation for a new, more digital distributed electricity system.

• KIEAE Journal
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• v.13 no.2
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• pp.77-84
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• 2013

Schools are one of favorable public buildings for Renewable Energy(RE) systems due to site conditions and their energy demand profiles(e.g. daytime-based use of hot water and heating/cooling). Although the government encourages schools to be equipped with RE systems, the adoption of RE systems in existing energy supply systems faces technical and financial barriers. For example, when installing a RE-based combination system(RECS) to meet the energy demand at various school scales, identifying cost effective combination of capacities of the RECS is not trivial since it usually requires technically intensive work including detailed simulation and demand/supply analysis with extensive data. This kind of simulation-based approaches is hardly implementable in practice. To address this, a simpler and applicable decision-supporting method is suggested in this study. This paper presents a simplified model in support of decision-making for optimal capacities of RECS within given budget scales and schools sizes. The proposed model was derived from detailed simulation results and statistical data. Using this model, the optimal capacities of RECS can be induced from the number of classes in a school.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.12
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• pp.638-644
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• 2017

Optimal cooling operation algorithm was developed based on a simulation case of a single family house model equipped with renewable energy facility. EnergyPlus simulation results were used as virtual test data. The model contained three energy storage elements: thermal heat capacity of the living room, chilled water storage tank, and battery. Their charging and discharging schedules were optimized so that daily electricity bill became minimal. As an optimization tool, linear programming was considered because it was possible to obtain results in real time. For its adoption, EnergyPlus-based house model had to be linearly approximated. Results of this study revealed that dynamic cooling load of the living room could be approximated by a linear RC model. Scheduling based on the linear programming was then compared to that by a nonlinear optimization algorithm which was made using GenOpt developed by a national lab in USA. They showed quite similar performances. Therefore, linear programming can be a practical solution to optimal operation scheduling if linear dynamic models are tuned to simulate their real equivalents with reasonable accuracy.