• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.10
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• pp.95-106
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• 2018

Currently, the way of providing housing in Korea has been regarded as public rental housing through large-scale development by the government. However, there is an increasing need for qualitative growth not only in quantitative growth but also in policies, systems, and sustainable design. The purpose of this study is to explore the applicable methods for domestic social housing through the policy and design guideline study of UK social housing which has achieved qualitative growth through diversification of development subject. First, the concept of social housing in the UK and sustainable housing design elements will be examined. Second, the characteristics and policy direction, project background, management and sustainability of five social housing projects over the last 10 years in the UK will be analyzed. In conclusion, in order to achieve the sustainable design of social housing, the construction of the social housing in terms of policy and environment must include safe and eco-friendly design adaptability that can secure local identity and respond flexibly to social change. In addition, the social housing in the UK, which forms a sustainable complex through cooperation between the public and the private sector based on its place and history, can be a guideline for establishing policies and design guidelines in terms of urban regeneration.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.2
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• pp.1-10
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• 2021

Lithium-ion batteries with high energy density, long cycle life and other advantages, have been widely used to energy storage systems(ESS). But as ESS fires frequently occur, the safety concern has become the main obstacle that hinders the large-scale applications of lithium-ion batteries. Especially, thermal runaway is the key scientific problem in battery safety research. Therefore, in this study, we performed a numerical analysis on the thermal runaway phenomenon of NCM111, NCM523 and NCM622 batteries using a two-dimensional analysis model. The results show that the two-dimensional simulation results are generally matched with three-dimensional simulation. Also, In the case of NCM111 with a low Ni content in the temperature range used in this study, thermal runaway phenomenon does occurred very slowly, but as the Ni content is increased, the thermal runaway phenomenon occurs rapidly and the thermal stability tends to be decreased. And, in NCM523 and NCM622 batteries, chain reactions occur almost simultaneously, but in the case of NCM111 battery, it is found that after the SEI(Solid Electrolyte Interface) layer decomposition reaction, the cathode-electrolyte reaction is appeared sequentially. After that, the anodic decomposition reaction is increased and leads to the thermal runaway reaction.

• Journal of Sensor Science and Technology
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• v.30 no.3
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• pp.170-174
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• 2021

As the rising attention to the medical and healthcare issue, Bio-MEMS (Micro electro mechanical systems) platform such as bio sensor, cell culture system, and microfluidics device has been studied extensively. Bio-MEMS platform mostly has high resolution structure made by biocompatible material such as polydimethylsiloxane (PDMS). In addition, three dimension structure has been applied to the bio-MEMS. Lithography can be used to fabricate complex structure by multiple process, however, non-rectangular cross section can be implemented by introducing optical apparatus to lithography technic. X-ray lithography can be used even for sub-micron scale. Here in, we demonstrated lines with round shape cross section using the tilted gold absorber which was deposited on the oblique structure as the X-ray mask. This structure was used as a mold for PDMS. Molded PDMS was applied to the cell culture platform. Moreover, molded PDMS was bonded to flat PDMS to utilize to the sub-micro channel. This work has potential to the large area bio-MEMS.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.5
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• pp.1847-1870
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• 2021

With the development of information and communication technologies, especially wireless networks and cell phones, the e-voting system becomes popular as its cost-effectiveness, swiftness, scalability, and ecological sustainability. However, the current e-voting schemes are faced with the problem of privacy leakage and further cause worse vote-buying and voter-coercion problems. Moreover, in large-scale voting, some previous e-voting system encryption scheme with pairing operation also brings huge overhead pressure to the voting system. Thus, it is a vital problem to design a protocol that can protect voter privacy and simultaneously has high efficiency to guarantee the effective implementation of e-voting. To address these problems, our paper proposes an efficient unidirectional proxy re-encryption scheme that provides the re-encryption of vote content and the verification of users' identity. This function can be exactly applied in the e-voting system to protect the content of vote and preserve the privacy of the voter. Our proposal is proven to be CCA secure and collusion resistant. The detailed analysis also shows that our scheme achieves higher efficiency in computation cost and ciphertext size than the schemes in related fields.

• Journal of Surface Science and Engineering
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• v.54 no.4
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• pp.164-170
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• 2021

Vanadium redox flow batteries (VRFB) have emerged as large-scale energy storage systems (ESS) due to their advantages such as low cross-contamination, long life, and flexible design. However, Hydrogen evolution reaction (HER) in the negative half-cell causes a harmful influence on the performance of the VRFB by consuming current. Moreover, HER hinders V²⁺/V³⁺ redox reaction between electrode and electrolyte by forming a bubble. To address the HER problem, carbon nanotube/graphite felt electrode (CNT/GF) with oxygen functional groups was synthesized through the hydrothermal method in the H₂SO₄ + HNO₃ (3:1) mixed acid solution. These oxygen functional groups on the CNT/GF succeed in suppressing the HER and improving charge transfer for V²⁺/V³⁺ redox reaction. As a result, the oxygen functional group applied electrode exhibited a low overpotential of 0.395 V for V²⁺/V³⁺ redox reaction. Hence, this work could offer a new strategy to design and synthesize effective electrodes for HER suppression and improving the energy density of VRFB.

• New & Renewable Energy
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• v.17 no.4
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• pp.9-27
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• 2021

Floating solar power markets are rapidly growing worldwide. The main policy instrument utilized to expand renewable energy use in foreign countries with many floating solar power installations is Feed-in-Tariffs (FITs). Foreign countries apply FIT to projects that have a secured grid connection, and lately, there has been a change in the direction of introducing or expanding auction systems. Vietnam and Taiwan give higher FIT to floating solar installations than land solar ones, and China, Vietnam, and Taiwan have higher FITs for certain regions. Compared to foreign countries where large-scale floating solar power installations have been installed, Korea has utilized Renewable Energy Certificate (REC) weights for residents' participation are provided additionally under the Renewable Portfolio Standard (RPS). In contrast to Korea, where residents' participation and benefit profit sharing are emphasized, the Netherlands provides opportunities for local residents to participate in floating solar power projects through cooperatives to improve the residents' acceptance.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2924-2932
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• 2022

Motivated by learning from experience and exploiting existing knowledge in civil nuclear operations, we have developed in-house generic Probabilistic Safety Assessment (PSA) models for pressurized and boiling water reactors. The models are computationally light, handy, transparent, user-friendly, and easily adaptable to account for major plant-specific differences. They cover the common internal initiating events, frontline and support systems reliability and dependencies, human-factors, common-cause failures, and account for new factors typically overlooked in many PSAs. For quantification, the models use generic US reliability data, precursor analysis reports, the ETHZ Curated Nuclear Events Database, and experts' opinions. Moreover, uncertainties in the most influential basic events are addressed. The generated results show good agreement with assessments available in the literature with detailed PSAs. We envision the models as an unbiased framework to measure nuclear operational risk with the same "ruler", and hence support inter-plant risk comparisons that are usually not possible due to differences in plant-specific PSA assumptions and scopes. The models can be used for initial risk screening, order-of-magnitude precursor analysis, and other research/pedagogic applications especially when no plant-specific PSAs are available. Finally, we are using the generic models for large-scale precursor analysis that will generate big picture trends, lessons, and insights.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.7
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• pp.2328-2344
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• 2022

2D human pose estimation still faces difficulty in low-resolution images. Most existing top-down approaches scale up the target human bonding box images to the large size and insert the scaled image into the network. Due to up-sampling, artifacts occur in the low-resolution target images, and the degraded images adversely affect the accurate estimation of the joint positions. To address this issue, we propose a multi-resolution input feature fusion network for human pose estimation. Specifically, the bounding box image of the target human is rescaled to multiple input images of various sizes, and the features extracted from the multiple images are fused in the network. Moreover, we introduce a guiding channel which induces the multi-resolution input features to alternatively affect the network according to the resolution of the target image. We conduct experiments on MS COCO dataset which is a representative dataset for 2D human pose estimation, where our method achieves superior performance compared to the strong baseline HRNet and the previous state-of-the-art methods.

• Smart Structures and Systems
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• v.29 no.2
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• pp.287-299
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• 2022

Rather than using smartphones as seismometers with designated locations and orientations, this study proposes to employ crowds' smartphones in buildings to perform fast safety assessment of buildings. The principal advantage of using crowds' smartphones is the potential to monitor the safety of millions of buildings without hardware costs, installation labor, and long-term maintenance. This study's goal is to measure the maximum interstory drift ratios during earthquake excitation using crowds' smartphones. Beacons inside the building are required to provide the location and relevant building information for the smartphones via Bluetooth. Wi-Fi Direct is employed between nearby smartphones to conduct peer-to-peer time synchronization and exchange the acceleration data measured. An algorithm to align the orientation between nearby smartphones is proposed, and the performance of the orientation alignment, interstory drift measurement, and damage level estimation are studied numerically. Finally, the proposed approach's performance is verified using large-scale shaking table tests of a scaled steel building. The results presented in this study illustrate the potential to use crowds' smartphones with the proposed approach to record building motions during earthquakes and use those data to estimate buildings' safety based on the interstory drift ratios measured.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.12
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• pp.4081-4098
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• 2022

With the aim of tackling the contradiction between computation intensive industrial applications and resource-weak Edge Devices (EDs) in Industrial Internet of Things (IIoT), a novel computation task offloading scheme in SDIN-enabled MEC based IIoT is proposed in this paper. With the aim of reducing the task accomplished latency and energy consumption of EDs, a joint optimization method is proposed for optimizing the local CPU-cycle frequency, offloading decision, and wireless and computation resources allocation jointly. Based on the optimization, the task offloading problem is formulated into a Mixed Integer Nonlinear Programming (MINLP) problem which is a large-scale NP-hard problem. In order to solve this problem in an accessible time complexity, a sub-optimal algorithm GPCOA, which is based on hybrid evolutionary computation, is proposed. Outcomes of emulation revel that the proposed method outperforms other baseline methods, and the optimization result shows that the latency-related weight is efficient for reducing the task execution delay and improving the energy efficiency.