• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.332-335
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• 2011

As our interests in eco-friendly materials have been significantly increased, the utilization of porous zeolite concrete that has structural functionality and permeability has been increased. In this paper, the mixture of porous concrete and zeolite, which can be used as multirole boulders, was investigated for the suitability of an environment-friendly product by evaluating of the water purification ability. The contamination removal rates of BOD, TOC, T-N, and T-P in stagnant water tank were 70.6, 67.0, 57.7, and 50.6%, respectively. Also for the non-point source pollution with the inflow and the outflow, the removal rates of Zn, Pb, BOD, and COD were 99.9, 90.0, 69.2, and 33.5%, respectively. The performance of the heavy metal contamination removal for the porous zeolite showed better than that of stagnant system. Therefore, it is expected that the installation of the porous zeolite concrete can play a role as an eco-friendly products by its high contamination removal.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.719-731
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• 2012

One of the most important point in the Internet crime investigation is tracing back and pointing out a criminal host. However, criminals can forge a crime record stored in the crime host, or can utilize malicious applications in order not to leave a crime record. In addition, criminals can change the source IP address of a crime host and deny their involvement. In this study, we suggests the Network Forensic Evidence Generation and Verification Scheme (NFEGVS) to rectify the current limitation of Network Forensic technologies. This scheme can prove who and when the crime has occurred. In addition, this prevents leaking of symmetric key for guaranteeing certification and integrity of Forensic Evidence by proposing the Timestamp Secret Key Distribution Scheme, and minimizes performance degradation of router when generating forensic evidence with the Flow-Based Selection Scheme. In this paper, we implement the proposed scheme and evaluate overall performance of the proposed system.

• Korean Journal of Materials Research
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• v.34 no.5
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• pp.223-234
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• 2024

This review explores the potential of pillared bentonite materials as solid acid catalysts for synthesizing diethyl ether, a promising renewable energy source. Diethyl ether offers numerous environmental benefits over fossil fuels, such as lower emissions of nitrogen oxides (NO_x) and carbon oxides (CO_x) gases and enhanced fuel properties, like high volatility and low flash point. Generally, the synthesis of diethyl ether employs homogeneous acid catalysts, which pose environmental impacts and operational challenges. This review discusses bentonite, a naturally occurring alumina silicate, as a heterogeneous acid catalyst due to its significant cation exchange capacity, porosity, and ability to undergo modifications such as pillarization. Pillarization involves intercalating polyhydroxy cations into the bentonite structure, enhancing surface area, acidity, and thermal stability. Despite the potential advantages, challenges remain in optimizing the yield and selectivity of diethyl ether production using pillared bentonite. The review highlights the need for further research using various metal oxides in the pillarization process to enhance surface properties and acidity characteristics, thereby improving the catalytic performance of bentonite for the synthesis of diethyl ether. This development could lead to more efficient, environmentally friendly synthesis processes, aligning with sustainable energy goals.

• Korean Journal of Ecology and Environment
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• v.50 no.2
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• pp.238-253
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• 2017

The sewage and wastewater (SAW) are a well-known major source of eutrophication and greentide in freshwaters and also a potential source of thermal pollution; however, there were few approaches to thermal effluent of SAW in Korea. This study was performed to understand the behavioral dynamics of the thermal effluents and their effects on the water quality of the connected streams during winter season, considering domestic sewage, industrial wastewater and hot spring wastewater from December 2015 to February 2016. Sampling stations were selected the upstream, the outlet of SAW, and the downstream in each connected stream, and the water temperature change was monitored toward the downstream from the discharging point of SAW. The temperature effect and its range of SAW on the stream were dependent not only on the effluent temperature and quantity but also on the local air temperature, water temperature and stream discharge. The SAW effects on the stream water temperature were observed with temperature increase by $2.1{\sim}5.8^{\circ}C$ in the range of 1.0 to 5.5 km downstream. Temperature effect was the greatest in the hot spring wastewater despite of small amount of effluent. The SAW was not only related to temperature but also to the increase of organic matter and nutrients in the connected stream. The industrial wastewater effluent was discharged with high concentration of nitrogen, while the hot spring wastewater was high in both phosphorus and nitrogen. The difference between these cases was due to with and without chemical T-P treatment in the industrial and the hot spring wastewater, respectively. The chlorophyll-a content of the attached algae was high at the outlet of SAW and the downstream reach, mostly in eutrophic level. These ecological results were presumably due to the high water temperature and phosphorus concentration in the stream brought by the thermal effluents of SAW. These results suggest that high temperature of the SAW needs to be emphasized when evaluating its effects on the stream water quality (water temperature, fertility) through a systematized spatial and temporal investigation.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.233-242
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• 2020

As studies and developments of nano-material increase, the release of the nano-sized material to water environment increase. Especially, silver nanoparticles have been found as dissolved and particulate state since nano-silver particle have been intensively used in industrial and our living environment due to the anti-bacterial effect of the nano-particles. The silver nano-particles and silver ion gives adverse effect on ecology and US-EPA set a secondary drinking water standards as 0.1 mg/L. Current study focused on the analysis of silver in groundwater, small scale water supply systems in Gyeongbook area. The results have been compared with the secondary drinking water standards and discussed at the point of characteristics of the local area and purpose of use of the water sample. Among the total of 298 samples, 2 samples exceed the secondary drinking water standards of EPA, 0.64% rate. Community drinking water and simplified water service showed relatively high detection rate and groundwater gave relatively higher concentration of silver indicating anthropogenic source and natural source could contribute simultaneously on groundwater.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8870-8878
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• 2015

During the carbon-dioxide capture and storage(CCS) process, $CO_2$ is captured from large point source, and then injected and stored in stable geological structure for thousands and more years. Inside the captured $CO_2$ flow, various impurities, such as $N_2$, $O_2$, argon, etc, are included inevitably. These impurities affect on the CCS process on various aspects. In this study, we designed and built experimental facility to evaluate the various impurity effect on the $CO_2$ pipeline flow, and analyzed the effect of argon ratio and pressure variation on the pressure drop of $CO_2$ flow. By comparing experimental data with 4 kinds of pressure drop model, we figured out and recommended the Cicchitti's model since it showed most accurate result among compared models in this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.446-452
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• 2016

Recently, heat resistant super alloys (which are wear-resistant, corrosion-resistant, and heat-resistant), have been used as the basic structural material in offshore and petrochemical plants. On the other hand, making valves from very expensive, high heat-resistant alloys increases the production cost and decreases its market competitiveness. To solve these problems, the technique of overlaying only those that flow on the fluid has been used as an effective method. Nevertheless, because the former technique of overlaying the ball is performed manually, it takes too much time and perfect welding is difficult to perform. To solve this problem, this study developed a robot automation system that can make uniformly overlay welding of the ball for ball-valves. The system consists of a 6-axis welding robot with a welding torch and additional 2 axes for the rotation of positioner, the controller, and a robot path OLP (Off-Line Programming). The CAD drawing data was entered in the Off-line program to obtain the robot teaching point and drive source. Overlay welding paths were implemented using Matlab. Through an automated overlaying system that implemented the OLP, the productivity rose 2.58 times, as the amount of time required for work decreased from 88 hours to 41 hours.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4411-4417
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• 2010

This study was retrospectively to compare the exposure dose and the imaging quality in coronary CT angiography by using the 64 channel multidetector computed tomography and the 128 channel DSCT. Effective dose was calculated dose length product (DLP) by multiplied the convention factor of chest (0.017). Imaging quality was assessed by radiologists using the 5-point Likert scale. The DLP was ranged from 851 to $1277mGy{\cdot}cm$ (mean: 17.23 mSv) in the 64 channel MDCT and from 82 to $110mGy{\cdot}cm$ (mean: 1.58 mSv) in the of 128 channel DSCT, respectively. The score of imaging quality was respectively $3.31{\pm}0.62$ in 64 channel MDCT and $4.05{\pm}0.46$ in the 128 channel DSCT. The exposure dose of 128 channel DSCT has decreased 1ess 1/10. The score of imaging quality was significant difference between two modalities and the frequency (>4 good) in the 128 channel DSCT is about three times than that of the 64 channel MDCT. Therefore, the 128 channel DSCT in coronary CT angiography is clinically more effective modality for both investigators and patients.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.403-412
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• 2021

Despite strengthening requirements for fire retardancy and applied buildings of insulation panels, the number of fires and influence of damage have increased. In this study, the thermal effects were evaluated as the separation distances, and three types of EPS panel, glass wool panel, and gypsum board panel were then selected. Temperature sensors on the panels were installed vertically from the ground. The fire source on the lamination layer of lumber was ignited by changes in the separation distances (0 cm, 25 cm, 50 cm) from the panels. The test results suggested that the maximum temperature was 349 ℃ in the EPS panel. The inside/outside shape changes were limited by the height of the low and middle positions until the critical point of a 25 cm separation distance. Furthermore, the combustion marks appeared after 500 s on average, and then the EPS panel with a high fire strength showed a broad "U type" pattern, glass wool panel, and gypsum board panel showed medium or narrow "V type" pattern. Therefore, the acquired data can provide valuable information for evaluating the fire risks and verifying fire investigation from buildings composed of these insulation panels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.475-487
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• 2020

The current water-management paradigm is changing from the expansion of reservoirs and facilities for simple outflows and non-point source management to the building of a sound water circulation system throughout the watershed. Based on this, water management for the watershed as a whole is establishing standards through local ordinances. The purpose of this study is to establish water cycle targets that are resilient to water management even after the development of cities in watersheds where water management is highly needed. This was done by referring to research and ordinances related to water circulation by local governments. A method is proposed based on a storage and infiltration method for rainfall. Through a comparison of percentiles, it was found that the water circulation target of a planned waterside city can be treated with 52% of total rainfall and 80% of rainfall of 17 mm per day. To quantitatively improve the quality results of these calculation procedures, it is estimated that the calculation of water cycle targets will be more reliable if other various variables such as the safety of low impact development factors or the selection of appropriate specifications are considered later.