• Bulletin of the Korean Chemical Society
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• v.20 no.6
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• pp.672-676
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• 1999

Gas-Permeable polymeric membranes containing carboxyl groups which are suitable for enzyme immobilization were investigated in order to use them as gas electrode membranes in biosensors. Carboxylated polyurethane (CPU) was synthesized via a reaciton between 2,2-bis(hydroxymethyl)propionic acid as a chain extender and prepolymers prepared from polycarprolactone(Mn=2,000) and 4,4'-diphenylmethane diisocynate. It was difficult to prepared membranes from the pure CPU because of its high elasticity and cohesion. However, transparent free-standing membranes were easily prepared from the blend solution of CPU and carboxylated poly(vinyl chloride)(CPVC) in tetrahydrofuran. Both elasticity and cohesion of the CPU/CPVC membranes were decreased with increasing the content of CPVC. DSC experiment suggests that CPU and CPVC may be well mixed. Permeability coefficients for O₂and CO₂(Po₂and Pco₂)in the membranes increased as the proportion of CPU increased. The addition of dioxtyl phthalate(DOP), a plasticizer, significantly enhanced the Po₂and Pco₂which were 4,4 and 30 barrer, respectively, in the CPU/CPVC(80/20 wt/wt) membranes containing 20% of DOP at 25℃ and 100psi. Thus this type of membranes may have a potential for the use as gas electrode membranes in biosensors.

• Asian Journal of Turfgrass Science
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• v.7 no.1
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• pp.13-18
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• 1993

Much attention has been given recently to solve the environmental contamination in golf courses Changing to culture practice rather than chemical practice that depends on pesticides and fertilizers is a hot issue in golf courses or grasslands. Organic soil conditioners improve soil-plant envirormental conditions rich in physical properties. In this study, measuring systems to evaluate soil conditioning effects were set up for on-site purpose. After establishing the methodology for evaluating soil conditioner effects, 2 kinds of organic conditioners were rested for examination. The systems for the methodology included a set of simulating equipment for field capacity, an impact type soil column compactor, and an infiltration-percolation system. Test results using the systems showed bulk density and infiltration rate of mixed soil were decreased at highter rates of conditioner, but total porocities were increased. Increased porocities were most capillary pore space which has a positive effect on soil water potential. The systems and methodology in this study seem to have an efficiency to measure the effects of soil conditioner on site purpose.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.192-195
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• 2019

Single-crystal diamond obtained by chemical vapor deposition (CVD) exhibits great potential for use in next-generation power devices. Low defect density is required for the use of such power devices in high-power operations; however, plastic deformation and lattice strain increase the dislocation density during diamond growth by CVD. Therefore, characterization of the dislocations in CVD diamond is essential to ensure the growth of high-quality diamond. In this work, we analyze the characteristics of the dislocations in CVD diamond through synchrotron white beam X-ray topography. In estimate, many threading edge dislocations and five mixed dislocations were identified over the whole surface.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.2
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• pp.1-9
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• 2019

In a ground-source heat pump (GSHP) system, a vertical ground heat exchanger (GHE) is widely accepted due to a higher thermal performance. In the vertical GHE, grout (also called grouting material) plays an important role in the heat transfer performance and the initial installation cost of the GHE. Bentonite-based grout has been used in practice because of its high swelling potential and low hydraulic conductivity. This study evaluated the thermo-physical properties of the bentonite-based grouts through lab-scale measurements. In addition, we conducted performance simulation to analyze the effect of mixed ratio of grouts on the design length and thermal performance of the vertical GHE. The simulation results show that thermally-enhanced grouts improve the heat transfer performance of the vertical GHE and thus reduce the design length of GHE pipe.

• Asian Journal of Innovation and Policy
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• v.8 no.1
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• pp.122-140
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• 2019

Providing free primary care to everyone is an important goal pursued by many countries under universal health care programs. Countries like India need to efficiently utilize their limited capacities towards this purpose. Unfortunately, due to a variety of reasons, patients incur substantial travel and out-of-pocket expenses for getting primary care from publicly-funded facilities. We propose a set-covering optimization model to assist health policy-makers in managing existing capacity in a better way. Decision-making should consider upgrading centers with better potential to reduce patient expenses and reallocating capacities from less preferred facilities. A multinomial logit choice model is used to predict the preferences. In this article, a brief background and literature survey along with the mixed integer linear programming (MILP) optimization model are presented. The working of the model is illustrated with the help of numerical experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.797-800
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• 2009

RFID enabled credit cards are becoming increasingly popular as contactless credit cards. We envision a future where RFID credit cards will be used for online shopping. RFID system has tremendous potential to render electronic payments more secure than normal credit cards. The word RFID enabled credit cards may bring in mixed passion, enthusiasm and perhaps even rage! This is partly paranoia and partly reality. The reality is that an intruder can read RFID cards without the user even noticing it. This brings in a zone of discomfort and leads to paranoia. Certain interactivity should exist to bring back this comfort to the user. This paper tries to make an effort in that direction. In this paper we propose mobile phone based architecture for secured electronic payments using RFID credit cards.

• Advances in environmental research
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• v.9 no.4
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• pp.295-312
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• 2020

The earlier literature widely documented the role of natural resources in economic development and confined their findings either in support of resource blessing growth or resource curse hypothesis. The ample research on the stated theme has available in the relevant databases, supported with empirical data, while a few studies used a case study or mixed-method approach. The study identified plenty of room on a given topic by conducting a systematic literature review and synthesizing the literature in more meaningful inferences. After a thorough investigation of the literature review through systematic intervention, the study concludes that natural resource management is imperative for a country's sustained growth. Simultaneously, it is desirable to reduce resource conflicts, improve institutional performance, decrease corruption, and stabilize the political environment to get maximum natural resource management potential globally.

• Steel and Composite Structures
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• v.45 no.1
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• pp.147-157
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• 2022

This study assessed the compressive and tensile strengths and modulus of elasticity of waste polyethylene terephthalate (PET) using the ASTM standard tests. In addition, short carbon and glass fibers were mixed with waste PET to examine the improvements in ductility and strength during compression. The bonding was examined via field-emission scanning electron microscopy. The strength degradation of the waste PET tested under UV was 40-50%. However, it had a compressive strength of 32.37 MPa (equivalent to that of concrete), tensile strength of 31.83 MPa (approximately ten times that of concrete), and a unit weight of 12-13 kN/m3 (approximately half that of concrete). A finite element analysis showed that, compared with concrete, a waste PET pile foundation can support approximately 1.3 times greater loads. Mixing reinforcing fibers with waste PET further mitigated this, thereby extending ductility. Waste PET holds excellent potential for use in foundation piles, especially while mitigating brittleness using short reinforcing fibers and avoiding UV degradation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.161-162
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• 2023

Limestone slag cement is a green and sustainable building material with huge market potential. However, its shortcoming of low early compressive strength needs to be improved. A method of using aluminum sulfate to improve the early strength of ternary mixed mortar was proposed, and its effect and optimal dosage were tested. Macroscopic properties such as mechanical properties and surface electrical resistivity were measured at different dosages (0%, 1%, 2%, 3%). The microstructure and products of the mixtures were tested in detail, including by scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction. The results show aluminum sulfate enhances mechanical properties and significantly increases surface electrical resistivity. The 1% and 2% doses had no adverse effects on the 28-day mechanical properties, while the 3% dose reduced the 28-day strength. Considering the changes in mechanical properties and surface electrical resistivity, 1% aluminum sulfate is the optimal dosage.

• Journal of Korean Academy of Nursing
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• v.46 no.4
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• pp.501-513
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• 2016

Purpose: The current challenges faced by nurses in providing high quality and evidence-based practice (EBP) supported care require profound changes in nursing education. To understand the changes needed to strengthen EBP education, the researchers examined EBP self-efficacy, course needs, barriers, and facilitators for academic faculty and clinical nurse preceptors to teach EBP in undergraduate nursing curricula. Methods: For this study, mixed-method approach was used with survey data collected from 73 academic faculty members from 54 universities. Further, 17 clinical nurse preceptors in three academic hospitals provided qualitative data for exploration of barriers and facilitators to teaching EBP. Data analysis used SPSS/WIN 21.0 and content analysis. Results: Quantitative data showed that although the overall level of self-efficacy among faculty was moderate, the implementation levels were relatively low. Most faculty members agreed with the need to integrate EBP courses into undergraduate nursing curricula. The qualitative data showed that the barriers to teaching EBP were lack of knowledge, skill, and initial investment for teaching EBP; hierarchical, rules-oriented nursing culture; potential learner overloads in processing EBP; limited research dissemination and application. Facilitators were identified as the importance of EBP to the profession of nursing; collaboration in schools and hospitals; and continuing education in teaching/utilizing EBP. Conclusion: The findings indicate that for successful integration of EBP ni nursing education there is a need for faculty training and integrated EBP courses.