• Korean Journal of Materials Research
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• v.15 no.6
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• pp.413-418
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• 2005

Perovskite $Pb(Ni_{1/3}Nb_{2/3})O_3-Pb(Zr,Ti)O_3[PNN-PZT]$ ceramics were synthesized by conventional ceramic processing technique. In order to modify piezoelectric properties for sensor application in this system, NiO addition was considered to provide $Ni^{+2}$ as an acceptor, which was known to occupy with B site in the structure. The effect of NiO addition up to $8\;mol\%$ on the following piezoelectric properties as well as sintering properties was investigated. When NiO added more than $1\;mol\%$, average grain size was decreased and second phase was found to form. Moreover, the second phase caused decrease in relative dielectric constant $(\varepsilon_{33}T/\varepsilon0)$, electro-mechanical coupling factor $(k_p)$, and piezoelectric charge constant $(d_{33})$, while increasing mechanical quality factor $(Q_m)$. When $1\;mol\%$ NiO was added, density, dielectric properties and piezoelectric properties were abruptly increased.

• Carbon letters
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• v.25
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• pp.50-54
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• 2018

Large-size graphene samples are successfully prepared by combining ultrosonic assisted liquid phase exfoliation process with oxidation-deoxidation method. Different from previous works, we used an ultrasound-treated expanded graphite as the raw material and prepared the graphene via a facile oxidation-reduction reaction. Results of X-ray diffraction and Raman spectroscopy confirm the crystal structure of the as-prepared graphene. Scanning electron microscopy images show that this kind of graphene has a large size (with a diameter over $100{\mu}m$), larger than the graphene from graphite powder and flake graphite prepared through single oxidation-deoxidation method. Transmission electron microscopy results also reveal the thin layers of the prepared graphene (number of layers ${\leq}3$). Furthermore, the importance of preprocessing the raw materials is also proven. Therefore, this method is an attractive way for preparing graphene with large size.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.365-370
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• 2014

Objectives: The major objective is development of an eco-friendly non-phthalate plasticizer using crude glycol derived from the biodiesel process. Methods: Glycerol monolaurate(GML) was synthesized from glycol and triglyrcerides. Glycerol diacetomonolaurate(GDAL) was synthesized from GML and acetic acid. Results: The synthesis of the GDAL plasticizer was measured with nuclear magnetic resonance spectroscopy(NMR). Mechanical properties were measured by universal testing machine(UTM) and the experimental values were compared with phthalate plasticizers such as dioctyl phthalate(DOP). In particular, the values for tensile strength and elongations with GDAL were higher than with DOP. Conclusions: We confirmed the development of an eco-friendly non-phthalate plasticizer by NMR. Based on our results, applicability for food and drug packaging materials was found.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.37-38
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• 2007

This paper reports the characteristics of piezoelectric microspeakers that are audible in open air with high quality piezoelectric AlN thin film according to the materials properties. When we use a tensile-stressed silicon nitride diaphragm as a supporting layer, the Sound Pressure Level (SPL) is relatively small. However, the SPL of the fabricated microspeakers that have compressive-stressed composite diaphragm show higher output pressure than those of tensile-stressed diaphragm. It produces more than 60dB from 100Hz to 15kHz and the highest SPL is about 100dB at 9.3kHz with 20 Vpeak-to-peak sinusoidal input biases and at 10 mm distances from the fabricated microspeakers to the reference microphone.

• New & Renewable Energy
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• v.17 no.2
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• pp.24-31
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• 2021

Renewable energy has become more popular with the increase in the use of solar power. Consequently, the disposal of defective and old solar panels is gradually increasing giving rise to a new problem. Furthermore, the efficiency and power output decreases with aging. Researchers worldwide are engaged in solving this problem by developing eco-module technologies that restore and reuse the solar panels according to the defect types rather than simple disposal. The eco-module technology not only solves the environmental problem, but also has economic advantages, such as extending the module life. Replacement of encapsulants contributes to a major portion of the module maintenance plan, as the degradation of encapsulants accounts for 60% of the problems found in modules over the past years. However, the current International Electrotechnical Commission (IEC) standard testing was designed for the commercialization of solar modules. As the problem caused by long-term use is not considered, this method is not suitable for the quality assurance evaluation of the eco-module. Therefore, to design a new accelerated test, this paper provides an overview of EVA degradation and comparison with the IEC and accelerated tests.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.10-11
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• 2019

The purpose of this study is to validate the environmental performance of the 'eco-friendly lightweight form' in the construction process. Unlike existing euro form and aluminum form, the proposed form does not require form oil during the process of concrete casting and is lightweight because it is made of engineering plastic. Therefore, eco-friendly lightweight form will reduce the $CO_2$ emissions in the construction process. To verify the hypothesis, the study compared existing forms and eco-friendly light weight form's $CO_2$ emissions in each stage in construction process when using 1,000 forms and 100 times from the LCI(Life Cycle Inventory) data. The total $CO_2$ emissions of the eco-friendly light weight form were 30,487kg $CO_2$, which equated to about 58% and 20% less emissions than the euroform and aluminum form. The result of the study verified that the eco-friendly lightweight form was effectively reduced $CO_2$ emission in the construction process.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.538-543
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• 2008

Urban development and industrialization cause many problems on urban environment such as climate changes, natural disasters and a decreasing number of species. Problems on urban environment are the main factor of that lower the quality of life and obstruct continual development. As a result, eco space becomes the important part of a urban planning. This research, building plan U-Eco city which is establishing with the clean environment and high technology for solve the development thoughtless for the city environment problem and ecological problem. We suggest U-Eco space system which accreted with Ubiquitous technology to three physical divisions, which are lithosphere (land), hydrosphere (water), and aerosphere (air), that interact with the whole biosphere by forming the system. It has composed with U-Green belt that corresponds to lithosphere, U-Blue belt that is applicable to hydrosphere, and U-White belt that comes under aerosphere.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.522-530
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• 2009

In this paper, we propose an efficient methodology to fix timing violation in ECO step for ASIC process. Timing violation can occur from various reasons and the major cause is inconsistent correlation between EDA tools. The most frequent violation is setup time and hold time violation. First, we analyzed the reason of violation creation, and then proposed the adjusting method for overcome them. Each violation can be fixed by increasing data required time or decreasing data arrival time. We proposed the detailed technique on a case basis. It is difficult to execute these methods by routine of algorithm or principle. Therefore ASIC engineer needs to apply these technique to violation as conditions of the implemented design.

• Journal of the Korean Graphic Arts Communication Society
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• v.26 no.2
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• pp.79-89
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• 2008

Eco printing offers the perfect balance between getting all our printing jobs done without endangering the environment. It is important to realize that the printing industry is no exception to this rampant destruction of the planet's natural resources. In fact, surprisingly enough, its effect on the environment is an extremely harmful one. Like most other production operations, printing houses also produce harmful waste products that pollute the air we breathe in. They also put a great drain on precious natural resources. Printing houses emit what are known as volatile organic compounds (VOCs), caused by the use of petroleum-based inks, laminates, varnishes and adhesives. Studies show that these compounds, when inhaled, greatly increase the risk of asthma attacks. Eco printing, however, has a larger scope than is apparent. Eco printing has a dual essence. In order to understand what it is really all about, the issue of conservation is no less important than the need to stop polluting the environment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1377-1385
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• 2015

Construction industry that was the core driving force of Korean economic growth is now being classified as an industry with the largest environmental load emission. Although various efforts were made accordingly to realize eco-friendliness, its effects is insufficient currently. Based on the understanding that eco effect of construction industry would be significant if Eco VE is applicable in the initial project stage, NIA model for understanding the eco VE decision of project owner was developed with simulations in this paper. Based on the proposal report of a private project to develop the Gyeongbuk Northern Region Environmental Energy Town, 20 questions on eco VE decision were used through simulations. The result showed 50% eco-friendly decision. The result of this study can be used to provide decision-making data for eco design in the initial stage of construction by utilizing NIA upon conducting survey research to deduce eco VE decision.