• Membrane and Water Treatment
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• v.7 no.4
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• pp.367-375
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• 2016

Although the bucky paper (BP) made from carbon nanotubes (CNTs) possesses beneficial characteristics of hydrophobic nature and high porosity for membrane distillation (MD) application, weak mechanical strength of BP has often prevented the stable operation. This study aims to fabricate the BP with high mechanical strength to improve its MD performance. The strategy was to increase the purity level of CNTs with an assumption that purer CNTs would increase the Van der Waals attraction, leading to the improvement of mechanical strength of BP. According to this study results, the purification of CNT does not necessarily enhance the mechanical strength of BP. The BP made from purer CNTs demonstrated a high flux ($142kg/m^2{\cdot}h$) even at low ${\Delta}T$ ($50^{\circ}C$ and $20^{\circ}C$) during the experiments of direct contact membrane distillation (DCMD). However, the operation was not stable because a crack quickly formed. Then, a support layer of AAO (anodic aluminum oxide) filter paper was introduced to reinforce the mechanical strength of BP. The support reinforcement was able to increase the mechanical strength, but wetting occurred. Therefore, the mixed matrix membrane (PSf-CNT) using CNTs as filler to polysulphone was fabricated. The DCMD operation with the PSf-CNT membrane was stable, although the flux was low ($6.1kg/m^2{\cdot}h$). This result suggests that the mixed matrix membrane could be more beneficial for the stable DCMD operation than the BP.

• Journal of Information Processing Systems
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• v.13 no.6
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• pp.1575-1584
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• 2017

As interest in big data has increased recently, NoSQL, a solution for storing and processing big data, is getting attention. NoSQL supports high speed, high availability, and high scalability, but is limited in areas where data integrity is important because it does not support multiple row transactions. To overcome these drawbacks, many studies are underway to support multiple row transactions in NoSQL. However, existing studies have a disadvantage that the number of transactions that can be processed per unit of time is low and performance is degraded. Therefore, in this paper, we design and implement a multi-row transaction system for data integrity in big data environment based on HBase, a column-based NoSQL which is widely used recently. The multi-row transaction system efficiently performs multi-row transactions by adding columns to manage transaction information for every user table. In addition, it controls the execution, collision, and recovery of multiple row transactions through the transaction manager, and it communicates with HBase through the communication manager so that it can exchange information necessary for multiple row transactions. Finally, we performed a comparative performance evaluation with HAcid and Haeinsa, and verified the superiority of the multirow transaction system developed in this paper.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.286-300
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• 2016

Pd-Ag alloy membranes have attracted a great deal of attention for their use in hydrogen purification and separation due to their high theoretical permeability, infinite selectivity and chemical compatibility with hydro-carbon containing gas streams. For commercial application, Pd-based membranes for hydrogen purification and separation need not only a high perm-selectivity but also a stable long-term durability. However, it has been difficult to fabricate thin, dense Pd-Ag alloy membranes on a porous stainless steel metal support with surface pores free and a stable diffusion barrier for preventing metallic diffusion from the porous stainless steel support. In this study, thin Pd-Ag alloy membranes were prepared by advanced Pd/Ag/Pd/Ag/Pd multi-layer sputter deposition on the modified porous stainless steel support using rough polishing/$ZrO_2$ powder filling and micro-polishing surface treatment, and following Ag up-filling heat treatment. Because the modified Pd-Ag alloy membranes using rough polishing/$ZrO_2$ powder filling method demonstrate high hydrogen permeability as well as diffusion barrier efficiency, it leads to the performance improvement in hydrogen perm-selectivity. Our membranes, therefore, are expected to be applicable to industrial fields for hydrogen purification and separation owing to enhanced functionality, durability and metal support/Pd alloy film integration.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.2
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• pp.162-167
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• 2012

This paper describes the design of a high-performance unified SVM classifier circuit. The proposed circuit supports both linear and non-linear SVM classifications. In order to ensure efficient classification, a 48x96 or 64x64 sliding window with 20 window strides is used. We reduced the circuit size by sharing most of the resources required for both types of classification. We described the proposed unified SVM classifier circuit using the Verilog HDL and synthesized the gate-level circuit using 65nm standard cell library. The synthesized circuit consists of 661,261 gates, operates at the maximum operating frequency of 152 MHz and processes up to 33.8 640x480 image frames per second.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1782-1788
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• 2015

In this paper, analysis of the effects for construction tolerances on the current collection performance of high speed catenary system. The height of the contact wire is the geometrical position of the cantilever directly affects the current collection performance. Contact force when the height of the contact wire exceeds the construction tolerance were analyzed. As a result, the maximum contact force was analyzed to more than 350[N] that are recommended by EN50119. And when the geometrical position of the cantilever to exceeds the construction tolerance, the analysis results of uplift at the mast support points, it becomes 127[mm] that are recommended by UIC 799. If the construction tolerances exceeds the reference value, the current collection performance is deteriorated. Therefore, catenary system require high precision construction. In the future, there is a need for continuing research on the tolerance of catenary system in the actual operating state.

• Journal of Technology Innovation
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• v.29 no.4
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• pp.95-124
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• 2021

Startups play an important role in economic growth and job creation in niche markets, thus governments regularly expand their research and development(R&D) budgets accordingly. As stratups are more dependent on governments to compensate for insufficient resources and capabilities than large and medium-sized companies, trust in government policies will be important. In this study, we analyzed the impact of startups' trust in government R&D policies on innovation performance. There were three major results. The first result is that government R&D investments in startups increase innovation performance in the manufacturing and high-technology industries but did not affect other industries. The second result is that trust in government R&D policies increased innovation in high-and medium-high technology and manufacturing industries. The third result is that trust in government R&D policies affects innovation before, during, and after evaluation of support process. We analyzed the importance of trust to the effectiveness of government R&D support to determine how to effectively provide it. The results show that governments need to differentiate the types of R&D support they provide according to the target firm's technology level and whether they are a manufacturing company and that appropriate R&D support mechanism should be developed for low-technology and non-manufacturing companies. Finally, governments should allocate resources and make fair and transparent decisions to help companies grow, not to better supervise them.

• The Journal of the Korea Contents Association
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• v.19 no.5
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• pp.520-531
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• 2019

The purpose of this study is to understand in depth the experiences regarding the healing of stress that takes place in the process of the job performance of fire fighting officers. For this, by having seven incumbent fire fighting officers as the subjects of the research, the individual in-depth interviews had been conducted. As a result of analyzing their experiences based on the phenomenological research method of Colaizzi, the 17 topic bundles, 5 subcategories, and 3 categories were derived. Regarding the results of the research, firstly, it appeared that the stress resulting from the job performance in the diverse processes of solving the petitions experienced as the obsessive anxiety, feeling of depression and sleep disorder, etc. Secondly, it had appeared that fire fighting officers show the strong feeling of pride and sense of calling regarding the job performance, but their dread regarding the life after the retirement was high. Thirdly, it appeared that such stress were offset and healed through the positive experiences, including the professional vocation, companionship and support by the family, etc. Because the high job stress gets developed into the continuous and complex physical problems and the emotional and psychological problems, it shows that there is a limitation to the healing with only the professional calling, companionship and support by the family. As such, for the healing of stress that takes place in the job performance by fire fighting officers and not just for the environmental improvements that are related with the job, but for the psychological and emotional support, this research arrived at the point of the suggestion that the operations of the complex and systematized supporting programs, including the strengthening of vocation and companionship, emotional support by the family etc., must be carried out.

• Management Science and Financial Engineering
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• v.16 no.1
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• pp.81-117
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• 2010

Semi-supervised learning incorporates unlabeled examples, whose labels are unknown, as well as labeled examples into learning process. Although transductive support vector machine (TSVM), one of semi-supervised learning models, was proposed about a decade ago, its application to large-scaled data has still been limited due to its high computational complexity. Our previous research addressed this limitation by introducing a branch-and-bound algorithm for finding an optimal solution to TSVM. In this paper, we propose three new techniques to enhance the performance of the branch-and-bound algorithm. The first one tightens min-cut bound, one of two bounding strategies. Another technique exploits a graph-based approximation to a support vector machine problem to avoid the most time-consuming step. The last one tries to fix the labels of unlabeled examples whose labels can be obviously predicted based on labeled examples. Experimental results are presented which demonstrate that the proposed techniques can reduce drastically the number of subproblems and eventually computational time.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1319-1325
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• 2010

Quantile regression provides a more complete statistical analysis of the stochastic relationships among random variables. Sometimes quantile functions estimated at different orders can cross each other. We propose a new non-crossing quantile regression method applying support vector median regression to restricted regression quantile, restricted support vector quantile regression. The proposed method provides a satisfying solution to estimating non-crossing quantile functions when multiple quantiles for high dimensional data are needed. We also present the model selection method that employs cross validation techniques for choosing the parameters which aect the performance of the proposed method. One real example and a simulated example are provided to show the usefulness of the proposed method.

• Journal of information and communication convergence engineering
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• v.15 no.4
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• pp.212-216
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• 2017

In this paper, we introduce novel techniques to improve the high performance of AE functions on modern high-end IoT platforms (ARM-NEON), which support SIMD and cryptography instruction sets. For the Sophie Germain Counter Mode of operation (SGCM), counter modes of encryption and prime field multiplication are required. We chose the Montgomery multiplication for modular multiplication. We perform Montgomery multiplication in a parallel way by exploiting both the ARM and NEON instruction sets. Specifically, the NEON instruction performed 128-bit integer multiplication and the ARM instruction performed Montgomery reduction, simultaneously. This approach hides the latency for ARM in the NEON instruction set. For a high-speed counter mode of encryptions for both AE functions, we introduced two-level computations. When the tasks were large volume, we switched to the NEON instruction to execute the encryption operations. Otherwise, we performed the encryptions on the ARM module.