• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.85-93
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• 2019

Oil seals are most essential parts in mechanical lubrication system to maintain the close gaps between stationary and high rotating components, and to help prevent oil leakages. Oil seals also can prevent harmful contaminants entering from outside to machinery, especially in severe environments. Therefore, the oil seals have an important performance in the machinery components. The performance of the oil seals are influenced by the design variables such as amount of interference gap between the main lip and shaft, the angle of main lip at air and oil sides and the distance between the garter spring and main lip. In the present study, a finite element analysis was performed to evaluate the oil seal performance with the considerations of number of oil seal dust lips and angle of the lip at oil side with the different design variables. As a result from the FEM analysis, the stress and contact pressure distributions was derived, based on this, performance of the sealing and durability were determined.

• Journal of the Korean Society of Systems Engineering
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• v.18 no.2
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• pp.11-23
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• 2022

Although artificial intelligence(AI) is a key technology in the digital transformation among the emerging technologies, there are concerns about the use of AI, so many countries have been trying to set up a proper regulation system. This study analyzes the cases of the regulation policies on AI in USA, EU and Korea with the aim to set up and improve proper AI policies and strategies in Korea. In USA, the establishment of the code of ethics for the use of AI is led by private sector. On the other side, Europe is strengthening competitiveness in the AI industry by consolidating regulations that are dispersed by EU members. Korea has also prepared and promoted policies for AI ethics, copyright and privacy protection at the national level and trying to change to a negative regulation system and improve regulations to close the gap between the leading countries and Korea in AI. Moreover, this study analyzed the course of policy changes of AI regulation policy centered on ACF(Advocacy Coalition Framework) model of Sabatier. Through this study, it proposes hyper-scale AI regulation policy recommendations for improving competitiveness and commercialization in Korea. This study is significant in that it can contribute to increasing the predictability of policy makers who have difficulties due to uncertainty and ambiguity in establishing regulatory policies caused by the emergence of hyper-scale artificial intelligence.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.2
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• pp.154-173
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• 2010

Database outsourcing is unavoidable in the near future. In the scenario of data stream outsourcing, the data owner continuously publishes the latest data and associated authentication information through a service provider. Clients may register queries to the service provider and verify the result's correctness, utilizing the additional authentication information. Research on On-line Stream Analytics (OLSA) is motivated by extending the data cube technology for higher multi-level abstraction on the low-level-abstracted data streams. Existing work on OLSA fails to consider the issue of database outsourcing, while previous work on stream authentication does not support OLSA. To close this gap and solve the problem of OLSA query authentication while outsourcing data streams, we propose MDAHRB and MDAHB, two multi-dimensional authentication approaches. They are based on the general data model for OLSA, the stream cube. First, we improve the data structure of the H-tree, which is used to store the stream cube. Then, we design and implement two authentication schemes based on the improved H-trees, the HRB- and HB-trees, in accordance with the main stream query authentication framework for database outsourcing. Along with a cost models analysis, consistent with state-of-the-art cost metrics, an experimental evaluation is performed on a real data set. It exhibits that both MDAHRB and MDAHB are feasible for authenticating OLSA queries, while MDAHRB is more scalable.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.8-14
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• 2005

Understanding of the flow past a bluff body close to a moving ground is very important in automobile and aeronautical fields because of aerodynamic characteristic and instability induced by unsteady vortex shedding. The passive control method that mounted the vertical and horizontal plates at the lower surface of the cylinder is studied to suppress the unsteady oscillation motion. When the grounds moves, the diminish of the shear layer on the ground promotes the interaction between the lower and the upper separated shear layers of the cylinder, hence vortex shedding occurs at the lower gap height than the stationary ground.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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• pp.233-241
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• 2005

The present model of a SF6 arc accounts for the copper vapour contamination from the electrodes inside a Laval nozzle of a circuit breaker. Steady state simulations have been done for the arc with electrode gap of 60mm and DC electric current of 500A, 1000A and 1500A for both cases with and without copper contamination. The effects of electrode polarity are considered for the arc current of 1000A. It was found out that evaporation of copper from the anode results in a cooling of the arc in a region close to the electrodes. The electrical potential across the electrodes is not sensitive to the presence of copper vapour, typically less than $4\%$ difference. Transient analysis has been done in order to obtain the arc properties at current zero. The arc current is increased linearly from -1000 to 0A when the upstream electrode is cathode with constant dI/dt of $27.0A/{\mu}s$ (or decreased linearly from 1000 to 0A when upstream electrode is anode). It has been predicted that the presence of copper vapour reduces the interruption capability of the breaker.

• Progress in Superconductivity and Cryogenics
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• v.14 no.3
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• pp.60-64
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• 2012

In this paper, an investigation of a room temperature active magnetic regenerative refrigerator is carried out. Experimental apparatus includes two active magnetic regenerators containing 186 g of Gd spheres. Four E-type thermocouples are installed inside the Active magnetic regenerator(AMR) to observe the instantaneous temperature variation of AMR. Both warm and cold heat exchangers are designed for large temperature span. The cold heat exchanger, which separates the two AMRs, employs a copper tube with length of 80 mm and diameter of 6.35 mm. In order to minimize dead volume between the warm heat exchanger and AMRs, the warm heat exchangers are located close to the AMRs. The deionized water is used as a heat transfer fluid, and maximum 1.4 T magnetic field is supplied by Halbach array of permanent magnets. The AMR plate, which contains the warm and the cold heat exchangers and the AMRs, has reciprocating motion using a linear actuator and each AMR is alternatively magnetized and demagnetized by a Halbach array of permanent magnet. Since the gap of the Halbach array of permanent magnets is 25 mm and two warm heat exchangers have the motion through it, a compact printed circuit heat exchanger (PCHE) is used as a warm heat exchanger. A maximum no-load temperature span of 26.8 K and a maximum cooling power of 33 W are obtained from the fabricated Active Magnetic Regenerative Refrigerator (AMRR).

• The Journal of Asian Finance, Economics and Business
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• v.9 no.2
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• pp.419-426
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• 2022

The digital economy is becoming an increasingly important source of regional competitiveness enhancement. The purpose of this research is to examine the spatial distribution characteristics of China's digital economy from 2016 to 2019. Moran's I analysis was performed to see if China's digital economy has spatial self-correlation. The Getis-Ord General G test was used to determine the clustering type of China's digital economy. In addition, we used OLS and GWR methodologies to figure out what drives China's digital economy level. The findings show that the digital economy is rapidly expanding throughout China; yet, there is a significant regional imbalance in the digital economy level in China, and the agglomeration of the digital economy is increasing over time. Furthermore, the findings reveal that human capital, information staff, telegram income, and Internet access are vital factors in the development of the digital economy. To close the digital economy gap, policymakers must invest in human capital and technology innovation. Simultaneously, the government must speed up the development and implementation of electronic information services.

• Fashion & Textile Research Journal
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• v.24 no.4
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• pp.357-371
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• 2022

With the expansion of the vegan fashion industry and increasing consumer interest in vegan goods, the first inaugural Vegan Fashion Week was held in LA in 2019. However, there are no studies examining the sustainability of vegan fashion brands; this study underlines the necessity to close this research gap. This study aimed to ascertain how these issues are handled by vegan fashion brands. Using the "sustainable criterion of fashion brands," we investigated the companies that participated in Vegan Fashion Week. This study analyzed the featured brands, conducted case studies, and examined each brand's sustainability strategies and procedures. Press releases, news articles, official websites, and web magazines served as raw data for this study. Analyses of individual networks were performed and brands' approaches to veganism and sustainability were evaluated; eco-friendly material, fair trade, local production, and vegan inspiration were among these techniques. Every brand had put at least one of these requirements into practice for their business, with vegan inspiration being the most popular approach. Additionally, it was discovered that vegan fashion brands deliberately employed vegan messaging that aligns with their corporate values. After its initial launch, VFW continues to advance the discourse on vegan fashion both within the industry and with the general public. The study's implications include the analysis of vegan fashion brands' ethical manufacturing, environmental practices, and overall sustainability.

• Journal of the Semiconductor & Display Technology
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• v.23 no.2
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• pp.87-91
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• 2024

SiO₂, renowned for its excellent insulating properties, has been used in the semiconductor industry as a valuable dielectric material. High-quality SiO₂ films find applications in gate spacers and interlayer insulation gap-fill oxides, among other uses. One of the prevalent methods for depositing these SiO₂ films is plasma enhanced chemical vapor deposition (PECVD) favored for its relatively low processing costs and ability to operate at low temperatures. However, compared to the increasingly utilized atomic layer deposition (ALD) method, PECVD exhibits inferior film characteristics such as uniformity. This study aims to produce SiO₂ films with uniformity as close as possible to those achieved by ALD through the adjustment of PECVD process parameters. we conducted a total of nine PECVD processes, varying the process time and gas flow rates, which were identified as the most influential factors on the PECVD process. Furthermore, ellipsometry analysis was employed to examine the uniformity variations of each process. The experimental results enabled us to elucidate the relationship between uniformity and deposition rate, as well as the impact of gas flow rate and deposition time on the process outcomes. Additionally, thickness measurements obtained through ellipsometer facilitate the identification of optimal process parameters for PECVD.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3527-3534
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• 2013

Background: Cancer is a major health problem facing the entire world, and Jordan is no exception. However, patterns of cancer incidence and cancer burden in Jordan have never been explored thoroughly, and the aim of this study was to close this knowldege gap. Materials and Methods: The study was based on data obtained from the Jordan cancer registry from 1996 to 2009. All cancer cases that were diagnosed during the study period were registered and included in this study. Results: A total of 51,626 cases were registered in Jordan during the 14- year period. The incidence rate showed no significant increase in males (percent change PC 6.8%), while in females a marked increase was observed (PC 14.8%). The major cancer sites for males were bronchus and lung, colorectal, bladder, leukemia and prostate. In females, the leading cancer sites were breast, colorectal, leukemia, thyroid and NHL. Conclusions: Compared to other countries in the region, Jordan has comparable rates. On the other hand the rates of cancer are markedly lower in Jordan compared to more industrialized countries such as the US and Europe. There was an overall increase in the incidence of cancer in Jordan, especially among females, which stresses the need for programs to raise awareness on the importance of early diagnosis and preventive life style measures.