• The Korean Journal of Applied Statistics
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• v.35 no.1
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• pp.1-17
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• 2022

We propose a test of consistency for two differentially private histograms using parametric bootstrap. The test can be applied when the original raw histograms are not available but only the differentially private histograms and the privacy level α are available. We also extend the test for the case where the privacy levels are different for different histograms. The resident population data of Korea and U.S in year 2020 are used to demonstrate the efficacy of the proposed test procedure. The proposed test controls the type I error rate at the nominal level and has a high power, while a conventional test procedure fails. While the differential privacy framework formally controls the risk of privacy leakage, the utility of such framework is questionable. This work also suggests that the power of a carefully designed test may be a viable measure of utility.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4400-4419
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• 2021

In the 4th Industrial Revolution, the healthcare industry is undergoing a paradigm shift from post-care and management systems based on diagnosis and treatment to disease prevention and management based on personal precision medicine. To optimize medical services for individual patients, an open ecosystem for the healthcare industry that allows the exchange and utilization of personal health records (PHRs) is required. However, under the current system of hospital-centered data management, it is difficult to implement the linking and sharing of PHRs in practice. To address this problem, in this study, we present the design and implementation of a patient-centered PHR platform using blockchain technology. This platform achieved transparency and reliability in information management by eliminating the risk of leakage and tampering/altering personal information, which could occur when using a PHR. In addition, the patient-consent system was applied to a PHR; thus, the patient acted as the user with ownership. The proposed blockchain-based PHR platform enables the integration of personal medical information with scattered distribution across multiple hospitals, and allows patients to freely use their health records in their daily lives and emergencies. The proposed platform is expected to serve as a stepping stone for patient-centered healthcare data management and utilization.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.1-8
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• 2023

This paper analyzes the trends of identification proofing services(PIPSs) to identify and authenticate users online and proposes a method to improve PIPS based on alternative means of resident registration numbers in Korea. Digital identity proofing services play an important role in modern society, but there are some problems. Since they handle sensitive personal information, there is a risk of information leakage, hacking, or inappropriate access. Additionally, online service providers may incur additional costs by applying different PIPSs, which results in online service users bearing the costs. In particular, in these days of globalization, different PIPSs are being used in various countries, which can cause difficulties in international activities due to lack of global consistency. Overseas online PIPSs include expansion of biometric authentication, increase in mobile identity proofing, and distributed identity proofing using blockchain. This paper analyzes the trend of PIPSs that prove themselves when identifying users of online services in non-face-to-face overseas situations, and proposes improvements by comparing them with alternative means of Korean resident registration numbers. Through the proposed method, it will be possible to strengthen the safety of Korea's PIPS and expand the provision of more reliable identification services.

• Journal of Information Processing Systems
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• v.19 no.6
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• pp.767-777
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• 2023

In modern society, user privacy is emerging as an important issue as closed-circuit television (CCTV) systems increase rapidly in various public and private spaces. If CCTV cameras monitor sensitive areas or personal spaces, they can infringe on personal privacy. Someone's behavior patterns, sensitive information, residence, etc. can be exposed, and if the image data collected from CCTV is not properly protected, there can be a risk of data leakage by hackers or illegal accessors. This paper presents an innovative approach to "machine learning based reversible chaotic masking method for user privacy protection in CCTV environment." The proposed method was developed to protect an individual's identity within CCTV images while maintaining the usefulness of the data for surveillance and analysis purposes. This method utilizes a two-step process for user privacy. First, machine learning models are trained to accurately detect and locate human subjects within the CCTV frame. This model is designed to identify individuals accurately and robustly by leveraging state-of-the-art object detection techniques. When an individual is detected, reversible chaos masking technology is applied. This masking technique uses chaos maps to create complex patterns to hide individual facial features and identifiable characteristics. Above all, the generated mask can be reversibly applied and removed, allowing authorized users to access the original unmasking image.

• Transactions of Materials Processing
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• v.33 no.3
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• pp.169-177
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• 2024

Recently, hydrogen energy has been widely used because of strict regulations on greenhouse gas emissions. For using the hydrogen energy, it is required to supply hydrogen through a tube trailer. However hydrogen tube trailer can have excessive load problems during transportation due to reasons such as road shape and driving method, which may lead a risk of hydrogen leakage. So it is necessary to secure a high level of safety. The purpose of this study is to evaluate structural safety for the conservative design of hydrogen tube trailer. First, finite element(FE) modeling of the designed hydrogen tube trailer was performed. After that, safety evaluation method was established through static structural simulation based on the standard GC207 conditions. In addition, effectiveness of the designed model was confirmed through the results of the structural safety evaluation. Finally, driving simulation was used to derive acceleration graph according to time, which was considered as a dynamic property for the evaluation of conservative tube trailer safety evaluation. And dynamic structural simulation was conducted as a condition for actual transportation of tube trailer by applying dynamic properties. As a results, conservative safety was evaluated through dynamic structural simulation and the safety of hydrogen tube trailer was confirmed through satisfaction of the safety rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.9
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• pp.2764-2781
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• 2024

Federated learning (FL) has been proposed as an emerging distributed machine learning framework, which lowers the risk of privacy leakage by training models without uploading original data. Therefore, it has been widely utilized in the Industrial Internet of Things (IIoT). Despite this, FL still faces challenges including the non-independent identically distributed (Non-IID) data and heterogeneity of devices, which may cause difficulties in model convergence. To address these issues, a local surrogate function is initially constructed for each device to ensure a smooth decline in global loss. Subsequently, aiming to minimize the system energy consumption, an FL approach for joint CPU frequency control and bandwidth allocation, called FCBAFL is proposed. Specifically, the maximum delay of a single round is first treated as a uniform delay constraint, and a limited-memory Broyden-Fletcher-Goldfarb-Shanno bounded (L-BFGS-B) algorithm is employed to find the optimal bandwidth allocation with a fixed CPU frequency. Following that, the result is utilized to derive the optimal CPU frequency. Numerical simulation results show that the proposed FCBAFL algorithm exhibits more excellent convergence compared with baseline algorithm, and outperforms other schemes in declining the energy consumption.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.5
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• pp.490-498
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• 2024

Ammonia is an eco-friendly marine fuel that does not emit carbon dioxide and is a primary contributor to global warming. Despite its benefits, ammonia poses significant risks owing to its toxicity, explosiveness, and corrosiveness, thus necessitating robust safety measures to manage its potential leaks on ships. This study investigates the characteristics of ammonia leaks and ventilation dynamics in a ship fuel-preparation room, with emphasis on the ef ect of varying the positions of air supply and exhaust outlets. The leakage rate is set at 0.1 kg/s, with a ventilation rate of 30 ACH (air changes per hour). The scenario with air supply at Aft - Top - Stbd and exhaust at Fwd - Top - Stbd (Case 1) results in the highest average ammonia concentration after 100 s. Conversely, the scenario with air supply at Aft - Bottom - Stbd and exhaust at Fwd - Bottom - Port (Case 14) results in the lowest concentration. After 50 s, Case 1 indicate ammonia concentrations exceeding 1500 ppm toward Aft, whereas Case 14 indicate a consistent stagnation zone along the Fwd wall. The distribution of ammonia concentration and velocity varies by height owing to the positioning of the air supply and exhaust outlets as well as the equipment configuration, thus resulting in higher concentrations in areas with slower airflow. When a small amount of ammonia leaked at 0.1 kg/s for 10 s, explosive gas formed near the leak point at a height of approximately 1 m, thus indicating an extremely low risk of explosion from slight ammonia leaks. This study confirms that the optimal combination of air supply and exhaust-duct positions can effectively control ammonia concentration. This finding is expected to contribute to the establishment of design standards and ensure safety when using ammonia as marine fuel.

• Journal of Environmental Impact Assessment
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• v.26 no.4
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• pp.242-256
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• 2017

In this paper, dispersion scenarios concerning various meteorological conditions and real urban structures were made to estimate the impacts of hazardous substance leakage accidents and to reduce damages. Based on the scenario of the hazardous substance dispersion, the characteristics of the risk in the pedestrian environment were analyzed in Gangnam, Seoul. The scenarios are composed of 48 cases according to the meteorological conditions of wind direction and wind speed. In order to analyze the dispersion characteristics of the hazardous substances, simulations were conducted using a computational fluid dynamic (CFD) model with hydrogen fluoride releases. The validation for the simulated wind was conducted at a specific period, and all the calculated verification indices were within the valid range. As a result of simulated dispersion field at pedestrian level, it was found that the dispersion pattern was influenced by the flow, which was affected by the artificial obstacles. Also, in the case of the weakest wind speed of the inflow, the dispersion of the hazardous substance appeared in the direction of the windward side at the pedestrian level due to the reverse flow occurred at lower layers. Through this study, it can be seen that the artificial structures forming the city have a major impact on the flow formed in urban areas. The proposed approach can be used to simulate the dispersion of the hazardous substances and to assess the risk to pedestrians in the industrial complexes dealing with actual hazardous substances in the future.

• Journal of Trauma and Injury
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• v.24 no.1
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• pp.1-6
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• 2011

Purpose: Even though traumatic pancreatic injuries occur in only 0.2% to 4% of all abdominal injuries, the morbidity and the mortality rates associated with pancreatic injuries remain high. The aim of this study was to evaluate the clinical outcomes of traumatic pancreatic injuries and to identify predictors of mortality and morbidity. Methods: We retrospectively reviewed the medical records of 26 consecutive patients with a pancreatic injury who underwent a laparotomy from January 2000 to December 2010. The data collected included demographic data, the mechanism of injury, the initial vital signs, the grade of pancreatic injury, the injury severity score (ISS), the revised trauma score (RTS), the Glasgow Coma Scale (GCS), the number of abbreviated injury scales (AIS), the number of associated injuries, the initial laboratory findings, the amount of blood transfusion, the type of operation, the mortality, the morbidity, and others. Results: The overall mortality rate in our series was 23.0%, and the morbidity rate was 76.9%. Twenty patients (76.9%) had associated injuries to either intra-abdominal organs or extra-abdominal organs. Two patients (7.7%) underwent external drainage, and 18 patients (69.3%) underwent a distal pancreatectomy. Pancreaticoduodenectomies were performed in 6 patients (23.0%). Three patients underwent a re-laparotomy due to anastomosis leakage or postoperative bleeding, and all patients died. The univariate analysis revealed 11 factors (amount of transfusion, AAST grade, re-laparotomy, associated duodenal injury, base excess, APACHE 11 score, type of operation, operation time, RTS, associated colon injury, GCS) to be significantly associated with mortality (p<0.05). Conclusion: Whenever a surgeon manages a patient with traumatic pancreatic injury, the surgeon needs to consider the predictive risk factors. And, if possible, the patient should undergo a proper and meticulous, less invasive surgical procedure.

• Journal of Energy Engineering
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• v.21 no.4
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• pp.339-345
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• 2012

RMembrane LNG storage tanks have been recently investigated to replace full-containment LNG storage tanks because of safety and cost aspects. Quantitative Risk Analysis (QRA) and Finite Element Method (FEM) were used to evaluate safety of membrane LNG storage tanks. In this study, structural safety evaluation results via FEM analysis showed that both membrane type and full-containment type cryogenic LNG storage tanks with 140,000 $m^3$ capacity were equivalently safe in terms of strength safety and leakage safety of a storage tank system. Also, Fault Tree Analysis (FTA) was used to improve the safety of membrane LNG storage tanks and membrane LNG tanks were modified by adding three safety equipments: impact absorber structure for the low part of the membrane, the secondary barrier to diminish the thermal stress of the corner part of the outer tank, and a pump catcher in case of falling of a pump. Consequently, the safety of the modified membrane LNG storage tanks were proved to be equivalent to that of full-containment LNG storage tanks.