• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.633-637
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• 2023

Recently, with the development of the smart device market, the integration of high-functional devices has increased the heat density, causing overload of the device, and resulting in various problems such as shortened lifespan, performance degradation, and failure. Therefore, research on heat dissipation materials is being actively conducted to realize next-generation electronic products. The heat dissipation material is characterized in that it is easy to dissipate heat due to its high thermal conductivity and minimizes leakage current flowing through the heat dissipation material due to its low electrical conductivity. In this study, flower-shaped Al₂O₃ and BN composites were engineered with a simple hydrothermal synthesis approach, and their thermal conductivity characteristics were compared and evaluated for each synthesis condition for the application to a heat dissipation material. Spherical BN and flower-shaped Al₂O₃ were easily obtained, and SEM/EDS analyses confirmed the uniform presence of BN between the Al₂O₃, and it can be expected that these shapes can affect the thermal conductivity.

• Convergence Security Journal
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• v.24 no.2
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• pp.9-17
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• 2024

This paper examines the security threats to enterprise Generative Artificial Intelligence systems and proposes countermeasures. As AI systems handle vast amounts of data to gain a competitive edge, security threats targeting AI systems are rapidly increasing. Since AI security threats have distinct characteristics compared to traditional human-oriented cybersecurity threats, establishing an AI-specific response system is urgent. This study analyzes the importance of AI system security, identifies key threat factors, and suggests technical and managerial countermeasures. Firstly, it proposes strengthening the security of IT infrastructure where AI systems operate and enhancing AI model robustness by utilizing defensive techniques such as adversarial learning and model quantization. Additionally, it presents an AI security system design that detects anomalies in AI query-response processes to identify insider threats. Furthermore, it emphasizes the establishment of change control and audit frameworks to prevent AI model leakage by adopting the cyber kill chain concept. As AI technology evolves rapidly, by focusing on AI model and data security, insider threat detection, and professional workforce development, companies can improve their digital competitiveness through secure and reliable AI utilization.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.28 no.1
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• pp.34-41
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• 2024

Backgrounds/Aims: Liver transplantation (LT) provides a favorable outcome for patients with hepatocellular carcinoma (HCC) and was launched in Vietnam in 2004. In this study, we evaluated the short-term and long-term outcomes of LT and its risk factors. Methods: This retrospective study analyzed HCC patients who underwent LT at Viet Duc University hospital, Vietnam, from 01/2012-03/2022. The following data were gathered: demographics, virus infection, tumor characteristics, alpha-fetoprotein (AFP) level, Child-Pugh and MELD scores, selection criteria, type of LT, complications, 30-day mortality, and disease-free and overall survival (DFS and OS). Results: Fifty four patients were included, the mean age was 55.39 ± 8.46 years. Nearly 90% had hepatitis B virus-related HCC. The median (interquartile range) AFP level was 16.2 (88.7) ng/mL. The average MELD score was 10.57 ± 5.95; the rate of Child-Pugh A and B were 70.4% and 18.5%, respectively. Nearly 40% of the patients were within Milan criteria, brain-dead donor was 83.3%. Hepatic and portal vein thrombosis occurred in 0% and 1.9%, respectively; hepatic artery thrombosis 1.9%, biliary leakage 5.6%, and postoperative hemorrhage 3.7%. Ninety-day mortality was 5.6%. Five-year DFS and OS were 79.3% and 81.4%, respectively. MELD score and ChildPugh score were predictive factors for DFS and OS (p < 0.05). In multivariate analysis, Child-Pugh score was the only significant factor (p < 0.05). Conclusions: In Vietnam, LT is an effective therapy for HCC with an acceptable complication rate, mortality rate, and good survival outcomes, and should be further encouraged.

• The Journal of the Convergence on Culture Technology
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• v.10 no.6
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• pp.741-750
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• 2024

The ALOHA program was used to propose an improvement plan for antifouling agents by reflecting the effects of toxicity, overpressure, and radiant heat around the storage tank of dangerous goods manufacturers. The ALOHA program was used to analyze the damage effects of isooctane on the toxicity, overpressure, and radiant heat of isooctane for the surrounding effects of the isooctane leakage accident, which is the first class of petroleum. As a result, it was analyzed that the toxicity was 117m in the area above the PAC-2 concentration, the overpressure was 114m in the range of 1 psi or more, and the radiant heat was 1,900m in the range of 2kW/m2 or more. Therefore, it is necessary to implement a performance-oriented dike design by applying a risk assessment reflecting the physical and chemical characteristics of dangerous substances that reduce and store the amount of octane in the antifouling agent by installing an dike for each storage tank of isooctane at a minimum distance of 38m from the center of the tank.

• Journal of Platform Technology
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• v.12 no.3
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• pp.55-61
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• 2024

As the digital environment becomes more complex and cyber attacks become more sophisticated, the importance of data protection is emerging. As various security threats such as data leakage, system intrusion, and authentication bypass increase, secure key management is emerging. Key Management System (KMS) manages the entire encryption key life cycle procedure and is used in various industries. There is a need for a key management system that considers requirements suitable for the environment of various industries including public and finance. The purpose of this paper is to derive the characteristics of the key management system for each industry by comparing and analyzing key management systems used in representative industries. As for the research method, information was collected through literature and technical document analysis and case analysis, and comparative analysis was conducted by industry sector. The results of this paper will be able to provide a practical guide when introducing or developing a key management system suitable for the industrial environment. The limitations are that the analyzed industrial field was insufficient and experimental verification was insufficient. Therefore, in future studies, we intend to conduct specific performance tests through experiments, including key management systems in various fields.

• Journal of the Korean Vacuum Society
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• v.18 no.2
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• pp.141-146
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• 2009

PLZT ferroelectric thin films were deposited on Pt/Ti/$SiO_2$/Si substrate with $TiO_2$ buffer layer in between by rf magnetron sputtering method. In order to investigate the effect of Ar/$O_2$ partial pressure ratio on the ferroelectric properties of PLZT thin films, PLZT thin films were deposited at various Ar/$O_2$ partial pressure ratio ; 27/1.5 seem, 23/5.5 seem, 21/7.5 seem and 19/9.5 seem. The crystallinities of PLZT thin films were analyzed by XRD. The surface morphology was observed using FE-SEM. The P-E hysteresis loops, the remanent polarization characteristics and the leakage current characteristics were obtained using a Precision LC. The crystallinity and elaborateness of PLZT thin films were decreased as increasing the oxygen partial pressure ratio. And preferred orientation of PLZT thin films changed from (110) plane to (111) plane. The oxygen partial pressure ratio affects the thin film surface morphology and the ferroelectric properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.307-312
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• 2018

Liquid phases in ZnO varistors cause more complex phase development and microstructure, which makes the control of electrical properties and reliability more difficult. Therefore, we have investigated 2 mol% $CaCO_3$ doped $ZnO-Co_3O_4-Cr_2O_3-La_2O_3$ (ZCCLCa) bulk ceramics as one of the compositions without liquid phase sintering additive. The results were as follows: when $CaCO_3$ is added to ZCCLCa ($644{\Omega}cm$) acting as a simple ohmic resistor, CaO does not form a secondary phase with ZnO but is mostly distributed in the grain boundary and has excellent varistor characteristics (high nonlinear coefficient ${\alpha}=78$, low leakage current of $0.06{\mu}A/cm^2$, and high insulation resistance of $1{\times}10^{11}{\Omega}cm$). The main defects $Zn_i^{{\cdot}{\cdot}}$ (AS: 0.16 eV, IS & MS: 0.20 eV) and $V_o^{\bullet}$ (AS: 0.29 eV, IS & MS: 0.37 eV) were found, and the grain boundaries had 1.1 eV with electrically single grain boundary. The resistance of each defect and grain boundary decreases exponentially with increasing the measurement temperature. However, the capacitance (0.2 nF) of the grain boundary was ~1/10 lower than that of the two defects (~3.8 nF, ~2.2 nF) and showed a tendency to decrease as the measurement temperature increased. Therefore, ZCCLCa varistors have high sintering temperature of $1,200^{\circ}C$ due to lack of liquid phase additives, but excellent varistor characteristics are exhibited, which means ZCCLCa is a good candidate for realizing chip type or disc type commercial varistor products with excellent performance.

• 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.

• The Journal of Korean Academic Society of Nursing Education
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• v.9 no.1
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• pp.51-63
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• 2003

The purpose of this study was to identify the prevalence of urinary incontinence of community residing climacteric women, and to identify the relationship between urinary incontinence and quality of life. The subjects of this study were 156 women(45 to 59 years old). Data was collected from Sep. 1 to Dec. 1 2002 by an interview or self-reporting by a structured questionnaire. The questionnaire was composed of items of general characteristics, urinary characteristics, and conditions of urinary incontinence, using the modified Henderickson's stress incontinence scale(1981), and the quality of life scale developed by RO, You Ja(1988). The data was analyzed by the SPSS/WIN program using descriptive statistics, Pearson correlation coefficients, t-test and AVOVA. The results of the study were as follows : 1. The prevalence of urinary incontinence was 76.3%. Of the incontinent women, 42.0% had experienced urinary incontinence for a period of one to three years. Frequency of urinary incontinence was once or twice per day for 42.9% of the urinary incontinent women. Most of the participation with urinary incontinence(91.6%) had mild leakage of urine. In the whole urinary incontinent women, 70.6% had never treated or managed their urinary incontinence. Most of the subjects(79.8%) were mildly incontinent, and the prevalence of moderate and severe urinary incontinence was 20.2%. The mean scores among the items of urinary incontinence, in descending order, were increase of abdominal pressure($1.45{\pm}1.05$), coughing($1.16{\pm}0.93$), and sneezing($1.03{\pm}0.92$). 2. The average score in the level in the quality of life variables was 3.12. The urinary incontinence and quality of life were correlated negatively(r=-0.103, p<0.001). 3. There were statistically significant differences in the score of climacteric woman's self reported quality of life according to : amount of urinary incontinence(F=12.68, P=0.001), duration of urinary incontinence(F=6.97, P=0.009), number of urinary incontinence(F=4.77, P=0.03), existence of urinary incontinence(t=148, P=0.05). In conclusion, this study was a preliminary study to provide nursing practice guidelines for climacteric woman with urinary incontinence. Nurses working with climacteric woman should develop and provide adequate care for the incontinent climacteric subjects. In future research, it is recommended to identify comprehensive factors related to urinary incontinence, including the effective management of urinary incontinence.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.195-200
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• 1998

We have investigated the crystal structure and electrical properties of Pt/SBT/$CeO_2$/Si(MFIS) and Pt/SBT/Si(MFS) structures for the gate oxide of ferroelectric memory. XRD spectra and SEM showed that the SBT film of SBT/$CeO_2$/Si structure had larger grain than that of SBT/Si structure. Furthermore HRTEM showed that SBT/$CeO_2$/Si had 5 nm thick $SiO_2$layer and very smooth interface but SBT/Si had 6nm thick $SiO_2$layer and 7nm thick amorphous intermediate interface. Therefore, $CeO_2$film between SBT film and Si substrate is confirmed as a good candidate for a diffusion barrier. The remanent polarization decreased and coercive voltage increased in Pt/SBT/$CeO_2/Pt/SiO_2$/Si structure. This effect may increase memory window of MFIS structure directly related to the coercive voltage. From the capacitance-voltage characteristics, the memory of Pt/SBT(140 nm)/$CeO_2$(25 nm)/Si structure were in the range of 1~2 V at the applied voltage of 4~6 V. The memory window increased with the thickness of SBT film. These results may be due to voltage applied at SBT films. The leakage currents of Pt/SBT/$CeO_2$/Si and Pt/SBT/Si were $ 10^8A/\textrm{cm}^2$ and $ 10^6 A/\textrm{cm}^2$, respectively.