• Applied Chemistry for Engineering
• /
• v.29 no.2
• /
• pp.237-243
• /
• 2018

The surface chemistry of WCK-AC, WCN-AC and WCZ-AC which are activated carbons prepared from waste citrus peel using KOH, NaOH, and $ZnCl_2$ as activating chemicals were investigated. Also the relationships between the adsorption capacities of the target gases such as acetone, benzene and methyl mercaptan (MM) by the prepared activated carbons and the pore characteristics of each activated carbon were examined. According to XPS analysis of the prepared activated carbons, graphite and phenolic were the main surface functional groups of C1, and the sum of phenol, carbonyl and carboxyl groups increased in the order of WCK-AC > WCN-AC > WCZ-AC. The breakthrough curves obtained from the adsorption experiments for the three target gases in the fixed bed adsorption reactor were well simulated by the empirical equations proposed by Yoon and Nelson. The adsorption capacity for acetone, benzene and MM was larger for activated carbons with the larger sum of surface functional groups. The larger the specific surface area and the pore volume of activated carbons and the smaller the pore size, the better the adsorption performance. In particular, the specific surface area was the best criterion for the adsorption performance of activated carbons used in this study.

• Korean Chemical Engineering Research
• /
• v.51 no.1
• /
• pp.127-135
• /
• 2013

In this study, both pressure drop and microbe-population-distribution were observed while running a novel biofilter system with improved design in which the biofilter system is composed of two, upper and lower biofilters with both equal feed-rates of up-flow and down-flow, respectively. Then they were compared with the pressure drop and microbe-population-distribution observed in a conventional biofilter of the same effective volume with unidirectional flow. The pressure drop-value of biofilter system with improved design turned out to be less at the incipient stage of run or steady-state long term operation by more than 40~80% of that of the conventional biofilter. The microbe-population-distribution was observed to be lower and higher at higher and lower column of biofilter, respectively, for both the conventional biofilter and the biofilter system with improved design. The microbe-media of waste-tire crumb showed much greater CFU counts than GAC. In the biofilter system with improved design, the $bottom{\rightarrow}up$ feeding of waste air showed greater microbe-population growth than the $top{\rightarrow}down$ feeding for both the microbe-media of waste-tire crumb and GAC. However, it was more prominent for the former than the latter. Comparing the microbe-population-distributions of both of the conventional biofilter and the biofilter system with improved design, the microbe-population of latter was distributed ca. 15 and 2.5 times more evenly for GAC and the media of waste-tire crumb, respectively, than that of former.

• Journal of the Korean Ceramic Society
• /
• v.41 no.11
• /
• pp.864-871
• /
• 2004

Porous pseudo-boehmite gel was prepared through the aging process of amorphous aluminum hydroxides gel precipitated by the hydrolysis reaction of dilute NaOH solution and AlCl$_3$ solution. In this study, the synthesis method was studied on porous pseudo-boehmite gel having maximum pore volume, as being investigated the changes of crystal structure, infrared rays absorption spectrum, BET surface area and pore structure when the hydrolysis reaction is controlled in the range of pH 7.6~11.6 and the aging process is hold up for 2~24 h at 60~10$0^{\circ}C$. We could find that the gel precipitates deposited in in range of pH 7.6~9.6 were developed into porous pseudo-boehmite which surface area was 250~357 $m^2$/g, pore volume was 0.4~0.7 cc/g and average pore size was 58~l14$\AA$. However, the gel precipitates deposited in range of pH 10.6~11.6 were developed into bayerite which pore volume was very little.

• Journal of the Korea Institute of Building Construction
• /
• v.17 no.3
• /
• pp.269-277
• /
• 2017

In this work, as a preliminary experimental works, which focuses on utilizing separated pastes from activated (or radioactive) concrete as solidifying agents for radioactive waste immobilization, were performed. It was found that density of hydrated cement paste, which was lower than that of ordinary portland cement, increased as temperature for heat treatment increased. Highest compressive strength was observed with the specimens that was heat treated at $600^{\circ}C$. However, heat treatment over $700^{\circ}C$ showed higher CaO content that caused higher heat of hydration after in contact with water, lows of workability, and lower strength. Based on experimental results, it is suggested that $600^{\circ}C$ heat treatment is more appropriate for waste cement paste to be used as a solidifying agent.

• International Journal of Highway Engineering
• /
• v.7 no.1 s.23
• /
• pp.21-29
• /
• 2005

One way to recycle the construction wastes is to use the waste concrete aggregates as the pavement materials. Although there are many studies and technical developments about waste concrete aggregates, the impurities produced in the process of the aggregate production prevent the use of the waste concrete aggregates in the pavement construction. In this study, the impurities included in the recycled waste aggregates were classified into inorganic and organic ones according to their characteristics, and the influences of each impurities on the pavement performance were presented. It was also showed that the limit of impurity content in the lean concrete base through the correlation between the inorganic impurity content and the compressive strength, and that in the granuler subbase layer through the correlation between the organic impurity content and the modified CBR. In conclusion, it is possible to apply waste concrete aggregates for the pavement when inorganic impurity content is less than 10% in the lean concrete base, and organic impurity content is less than 2% in granular subbase.

• Applied Chemistry for Engineering
• /
• v.28 no.6
• /
• pp.649-654
• /
• 2017

An activated carbon was prepared from waste citrus peel produced in large amounts in Jeju Island, Korea, using KOH activation and its characteristics was examined. Under the condition of the KOH ratio between 100 and 300%, activation temperature from 400 to $900^{\circ}C$ and activation time from 0.5 to 1.5 h, the iodine adsorptivity of the activated carbon prepared increased but the yield decreased with respect to the increase of each conditions. The iodine adsorptivity and yield of the activated carbon prepared at the activation time of more than 1.5 h were similar to those of using 1.5 h. In addition, as the KOH ratio increased, the specific surface area and pore volume of the activated carbon increased, but the pore diameter decreased. The activated carbon has an average pore diameter of $20{\sim}25{\AA}$. Also, the activated carbon prepared at 300% KOH and $900^{\circ}C$ for 1.5 h has the highest specific surface area of $1,527m^2/g$ and iodine adsorptivity of 1,246 mg/g.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.5 no.3
• /
• pp.171-177
• /
• 2007

This study suggested a new method to stabilize molten salt wastes generated from the pyre-process for the spent fuel treatment. Using conventional sol-gel process, $SiO_2-Al_2O_3-P_2O_5$ (SAP) inorganic material that is reactive to metal chlorides were prepared. In this paper, the reactivity of SAP with the metal chlorides at $650{\sim}850$, the thermal stability of reaction products and their leach-resistance under the PCT-A test method were investigated. Alkali metal chlorides were converted into metal aluminosilicate($LixAlxSi1-_xO_{2-x}$) and metal phosphate($Li_3PO_4\;and\;Cs_2AlP_3O_{10}$) While alkali earth and rare earth chlorides were changed into only metal phosphates ($Sr_5(PO_4)_3Cl\;and\;CePO_4$). The conversion rate was about $96{\sim}99%$ at a salt waste/SAP weight ratio of 0.5 and a weight loss up to $1100^{\circ}C$ measured by thermogravimetric analysis were below 1wt%. The leach rates of Cs and Sr under the PCT-A test condition were about $10^{-2}g/m^2\;day\;and\;10^{-4}g/m^2\;day$. From these results, it could be concluded that SAP can be considered as an effective stabilizer for metal chlorides and the method using SAP will give a chance to reduce the volume of salt wasteform for the final disposal through further researches.

• Progress in Medical Physics
• /
• v.26 no.4
• /
• pp.234-240
• /
• 2015

The purpose of this study is to analyze dosimetric parameters of patient with large and pendulous breast receiving breast radiotherapy in the prone versus supine position. The patient underwent computed tomography simulation in both prone and supine position. The homogeneity index (HI), conformity index (CI), coverage index (CVI) to the left breast as planning target volume (PTV) and the doses to the lung, heart, and right breast as organ at risk (OAR) were compared by using dose-volume histogram. The lifetime attributable risk (LAR) according to the prone and supine position was measured for the lung and right breast. The HI, CI of the PTV decreased 21.7%, 6.49%, respectively and the CVI increased 10.8% with the prone position. The mean and maximum dose to the left lung decreased 91.6%, 87.0%, respectively and the volume parameters also decreased over 99% with the prone position. The parameters to the right lung were same regardless of the position. The mean and maximum dose to the heart decreased 51.6%, 14.2% with the prone position. But the mean and maximum dose to the right breast increased unlike the other OARs. The LARs to the lung decreased 80.3% (left), 24.2% (right) but the LAR to the right breast doubled with the prone position. The prone position is a favorable alternative for irradiation of breast in patients with large and pendulous breasts.

• The Journal of Korean Society for Radiation Therapy
• /
• v.24 no.2
• /
• pp.123-135
• /
• 2012

Purpose: It is essential to minimize the movement of tumor due to respiratory movement at the time of respiration controlled radiotherapy of non-small cell lung cancer patient. Accordingly, this Study aims to evaluate the usefulness of restricted respiratory period by comparing and analyzing the treatment plans that apply free and restricted respiration period respectively. Materials and Methods: After having conducted training on 9 non-small cell lung cancer patients (tumor n=10) from April to December 2011 by using 'signal monitored-breathing (guided- breathing)' method for the 'free respiratory period' measured on the basis of the regular respiratory period of the patents and 'restricted respiratory period' that was intentionally reduced, total of 10 CT images for each of the respiration phases were acquired by carrying out 4D CT for treatment planning purpose by using RPM and 4-dimensional computed tomography simulator. Visual gross tumor volume (GTV) and internal target volume (ITV) that each of the observer 1 and observer 2 has set were measured and compared on the CT image of each respiratory interval. Moreover, the amplitude of movement of tumor was measured by measuring the center of mass (COM) at the phase of 0% which is the end-inspiration (EI) and at the phase of 50% which is the end-exhalation (EE). In addition, both observers established treatment plan that applied the 2 respiratory periods, and mean dose to normal lung (MDTNL) was compared and analyzed through dose-volume histogram (DVH). Moreover, normal tissue complication probability (NTCP) of the normal lung volume was compared by using dose-volume histogram analysis program (DVH analyzer v.1) and statistical analysis was performed in order to carry out quantitative evaluation of the measured data. Results: As the result of the analysis of the treatment plan that applied the 'restricted respiratory period' of the observer 1 and observer 2, there was reduction rate of 38.75% in the 3-dimensional direction movement of the tumor in comparison to the 'free respiratory period' in the case of the observer 1, while there reduction rate was 41.10% in the case of the observer 2. The results of measurement and comparison of the volumes, GTV and ITV, there was reduction rate of $14.96{\pm}9.44%$ for observer 1 and $19.86{\pm}10.62%$ for observer 2 in the case of GTV, while there was reduction rate of $8.91{\pm}5.91%$ for observer 1 and $15.52{\pm}9.01%$ for observer 2 in the case of ITV. The results of analysis and comparison of MDTNL and NTCP illustrated the reduction rate of MDTNL $3.98{\pm}5.62%$ for observer 1 and $7.62{\pm}10.29%$ for observer 2 in the case of MDTNL, while there was reduction rate of $21.70{\pm}28.27%$ for observer 1 and $37.83{\pm}49.93%$ for observer 2 in the case of NTCP. In addition, the results of analysis of correlation between the resultant values of the 2 observers, while there was significant difference between the observers for the 'free respiratory period', there was no significantly different reduction rates between the observers for 'restricted respiratory period. Conclusion: It was possible to verify the usefulness and appropriateness of 'restricted respiratory period' at the time of respiration controlled radiotherapy on non-small cell lung cancer patient as the treatment plan that applied 'restricted respiratory period' illustrated relative reduction in the evaluation factors in comparison to the 'free respiratory period.

• Korean Journal of Heritage: History & Science
• /
• v.44 no.2
• /
• pp.46-57
• /
• 2011

The aim of this study was to examine the current situation of otter inhabitation and conservation and to collect basic information for establishing appropriate policies. We conducted the study around the Bukhan river from April to October 2009, mostly focusing on otter distribution, feeding habits, threats, and conservation measures. We divided the study area into 2 sectors: the dam area and the stream. We found 39 spraint sites in the dam area and 70 in the stream area. A significant difference was observed in the number of spraint sites between the upper stream and the lower stream. To evaluate the feeding habit, we collected and analyzed the frequency and bulk occurrence of the spraints. Among the prey items, fish were the most numerous (36.99%) followed by amphibians (17.22%). Fish showed the highest bulk occurrence in the dam area, and the bulk occurrence of amphibians and insects seemed to increase in the stream area. However, the bulk occurrence in the dam area seemed to be lower than that in the stream area (ANOVA, F = 3.99, p < 0.05). Fyke nets and abandoned fishing nets were found to be the most threatening factors. Further research on the systematic management of otters and the use of stop grids is required for better conservation of otters.