• Advanced Composite Materials
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• v.18 no.4
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• pp.315-326
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• 2009

PCC (precipitated calcium carbonate) and ground calcium carbonate have been widely used in alkaline papermaking. Unfortunately, although increasing filler level in papers can improve the paper properties such as brightness, opacity, stiffness gloss, smoothness, porosity, and printability, as well as decrease cost, some strength of the paper is negatively affected. In this research, needle-like aragonite was synthesized using $Ca(OH)_2$ and $CO_2$ as reactants in the presence of $MgCl_2$ and characterized with scanning electronic microscopy (SEM) and X-ray diffraction (XRD). The physical and optical properties of the paper handsheets containing these needle-like aragonite fillers were evaluated. Results indicated that tensile strength, Z-direction tensile strength and folding endurance of the paper were improved by the needle-like aragonite crystals compared to the paper using commercial PCC (precipitated calcium carbonate) as filler. The stiffness of the paper handsheet on the machine direction was increased, but no evident difference in the cross direction was found. The improvement of paper strength mainly resulted from the twining effect between the aragonite whiskers and paper fibers. The optical properties of the paper were slightly decreased with the use of the needle-like aragonites compared to commercial PCC. These results suggest that paper cost can be decreased by increasing the content of needle-like aragonite filler while paper strength will not be decreased compared to PCC filler.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.1
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• pp.46-51
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• 2007

The file sharing method from P2P environments with client/server method to be different price does not use an expensive server from radio environment not to be, uses only the client computers and dispersed the joint ownership and a management of data. Human occurs from the client/server method which uses the server of large dosage with like this reason, will be able to minimize the waste of the waste of the material resources. Also valence increasing number of days rock operation of the user provides their benefit of etc. their result comes to be high. Like this is caused by with reason and the many people have an interest in P2P, also currently footlights the researches whice use P2P even in the mobile relation field which is receiving actively, is advanced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.87-88
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• 2006

It is needed several large reservoirs and long time in order to remove suspended solid like steel fines and iron oxide at steel making factory. If removing rate of suspended solid in rolling coolant is improved, the productivity of working process can be increased and the area of reservoir can be reduced. Pre-treatment to add extra magnetization of suspended solid was studied Iron hydroxide and electrolytic dissociation were used for pretreatment. High gradient magnetic separation (HGMS) system was used for removing of magnetized suspended solid. Removing ratio showed over than 99% in the coolant containing magnetic fines. Magnetic properties of suspended solid were investigated after mixed with Al2(SO2)3 and organic flocculant by using electrochemical treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.620-626
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• 2023

Energy harvesting technology, which converts wasted energy sources in everyday life into usable electric energy, is gaining attention as a solution to the challenges of charging and managing batteries for the driving of IoT sensors, which are one of the key technologies in the era of the fourth industrial revolution. Hybrid energy harvesting technology involves integrating two or more energy harvesting technologies to generate electric energy from multiple energy conversion mechanisms. In this study, a hybrid energy harvesting device called TMPPEG (thermo-magneto-piezoelectric-pyroelectric energy generator), which utilizes low-grade waste heat, was developed by incorporating PVDF polymer piezoelectric components and optimizing the system. The variations in piezoelectric output and thermoelectric output were examined based on the spacing of the clamps, and it was found that the device exhibited the highest energy output when the clamp spacing was 2 mm. The voltage and energy output characteristics of the TMPPEG were evaluated, demonstrating its potential as an efficient hybrid energy harvesting component that effectively harnesses low-grade waste heat.

• Resources Recycling
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• v.24 no.4
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• pp.38-49
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• 2015

The importance of recycling came to the fore by increasing of waste electrical and electronic equipment(WEEE) generation. Small WEEE recycling in particular represents a big challenge in Korea because it has various items and components. Main materials of small WEEE are typically well known for metals (copper, iron, aluminum, etc.), PCBs and plastics. Not only Korea but also overseas, the laws for small WEEE were in effect in order to recycle effectively, but the technology is not catched up with the regulation which has to recycle an allocated account of WEEE. In addition, recycling technologies and processes for small WEEE are not developed enough to recycling center properly. In that sense, if we develope the recycling process, have not only technology competitiveness but also resource conservation, improving the environment and economic profits. Therefore, through the analysis of economic value of recycled small WEEE, and current technologies both domestically and internationally, we design conceptual recycling process of small WEEE, and consider the way forward.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1287-1294
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• 2021

This paper is a study on the implementation of a sensor-based smart compression system for improving home and street environments. Since modernization, the amount of garbage has been increasing every year, and this has seriously adversely affected not only people but also ecosystems such as marine pollution and soil pollution. In particular, in large cities with large floating populations, garbage is dumped on the streets without proper measures to deal with the amount of waste generated. In order to improve this problem, this paper intends to implement a system with automatic compression and opening/closing functions using sensors. This system is designed to activate automatic opening/closing function through an infrared sensor, and automatically opening and closing when the inclination is changed using an impact sensor. In addition, by installing a distance sensor, the amount of internal waste can be easily monitored from the outside, and a manual compression switch and a manual opening/closing switch is separately designed to enable opening and closing and compression as needed to increase the effectiveness.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1239-1244
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• 2023

In this study, we developed an IoT-based management system to manage a can/PET crusher. Various sensors such as two load cells, DHT22 temperature and humidity sensor, and fine dust meter were interfaced with ESP32 to construct an IoT device, and a management server was built using Node-RED. The system monitors the weight of pressed cans and shredded PET bottles in real time and sends a text message to the manager when the weight exceeds the predetermined threshold for timely collection. The results of the operational test confirmed that the system provides accurate monitoring and efficient notification functions, and offers the possibility of solving environmental problems by improving the efficiency of waste management such as cans and PET bottles.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.397-401
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• 2008

Most of the topic in PCB industry was about increasing the volume of product for the development of electronics in numerous industrial application area. However, it has been emerged that yield improvement quality manufacturing via detecting any suspicious process in order to minimize the scrapped product and material waste. In addition, recently, restriction of hazardous substances (RoHS) claims that electronic manufacturing environment should reduce the harmful chemicals usage, thus the importance of monitoring copper etchant and detecting any mis-processing is crucial for electronics manufacturing. In this paper, we have developed real-time chemical monitoring system using RGB sensor, which is simpler but more accurate method than commercially utilized oxidation reduction potential (ORP) technique. The developed Cu etchant monitoring system can further be utilized for copper interconnect process in future nano-semiconductor process.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.558-559
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• 2023

지구온난화와 기후변화로 인해 전세계적으로 기업, 정부는 ESG(Environmental, Social and Corporate Governance)에 관심을 가지고 있다. 이에 따라 폐기물 분류 및 재활용에도 관심을 가지고 있지만 국내 외 폐기물 분류는 정확하게 이루어 지지 않고 있다. 이에 본 논문에서는 객체 인식의 대표 모델인 YOLOv5 를 이용해 폐기물 중 대표인 페트병 탐지 시스템을 제안한다. 제안하는 시스템은 페트병 사이 다른 폐기물을 감지해 내고 페트병 중 유색과 투명 페트병을 분류를 한다. 향후, 제안하는 시스템의 성능 평가가 필요하고 다른 폐기물로 확장이 필요하다.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.482-488
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• 1997

Copper recovery from waste water of electronic industry has been conducted effectively in a fluidized bed reactor. Initial concentration of copper in the waste water, liquid flow rate in the reactor, reaction temperature and time and current density between the cathode and anode in the reactor have been selected as operating variables. The effects of operating variables on the recovery of copper have been studied. It has found that the copper resolved in the waste water can be recovered continuously by means of a fluidized bed reactor The recovery of copper decreased with an increase in the initial concentration of copper in the waste water, while it increased with increasing reaction time and current density, however, it exhibited its maximum value with the variations of liquid flow rate and reaction temperature. The optimum reaction condition to maintain the copper recovery around 85% is as follows ; $X_o=3wt%$, $U_L=0.5cm/s$, $T=25^{\circ}C$, $I=7A/dm^2$ and t=2hrs within this experimental condition.