• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.65-71
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• 2019

The development of adsorbed natural gas (ANG) has emerged as one of potential solutions. It is desirable to reduce the weight of vessel by applying light-weighed a composite carbon fiber in order to response to a egulation of $CO_2$ emission. Through understanding of a composite carbon fiber, and material characteristic of a composite carbon fiber is required in order for better application of a reduction of weight and an analysis of material characteristic. Herein, this study suggest the composite carbon fiber vessel applied to the characteristic of carbon fiber, and it decides the preliminary shape based on the test of material characteristic for ANG vessel applied to a composite carbon fiber, and its basic shape calculate through on the netting theory. Moreover, the detail shape design is analyzed by a finite element analysis, and in the stage of detail sahp design and analysis of stress was performed on the typical shape using a finite element analysis, and the result of preliminary design was verified.

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.389-395
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• 2018

The odor substances generated in a feed manufactory operating for the commercialization of animal-vegetable materials were analyzed and the odor reduction efficiency by a chemical scrubber was evaluated. The major causative substances in the feed manufactory comprised about 45.4% of ketone compounds and about 13.3% of aldehyde compounds. On the other hand, the removal efficiencies of diacetyl and acetoin as ketone compounds were 77.3% and 78.1%, respectively, by a chemical scrubber. Additionally, the removal efficiencies of acetaldehyde, butyraldehyde, valeraldehyde, 2-furancarboxaldehyde, and nonanal were 86.0%, 78.9%, 67.4%, 52.8%, and 71.9%, respectively. These rates were higher than the odor generation substance contribution rate as a result of treating the exhaust gas generated from the feed manufactory by the chemical scrubber using 5% of C3. It was also found that xylene, methylcyclopentane, benzene, ethylbenzene, 1,3,5-trimethylbenzene, and decane were almost not removed.

• The Korean Journal of Food And Nutrition
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• v.34 no.1
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• pp.132-136
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• 2021

The purpose of this study is to measure the levels of eluted and dissolved CO2, and CO, volatile organic substances and radiation composition of Cheongsong mineral water which were collected from November 2019 to July 2020 during the autumn, spring, and summer seasons at collection points located in the upper, middle and lower spring waters. Data of the upper, middle and lower spring waters include the following: the amount of eluted water (average value±standard deviation, mL/min) was 30.07±0.52, 15.03±0.16, 23.73±0.42, and the amount of CO2 gas was 1,000 ppm or more. In addition, there was no detection of CO or total volatile organic substances (TVOC) and the radiation dose was 0.08 to 0.13. μSv/h. A blank test value of 0.08 to 0.10 μSv/h, when compared with the median value, showed a high value of 0.02 μSv/h, and the uranium test results provided by the Cheongsong-gun Office were 0.0118 mg/L (date 2019.06.18) and 0.0091 mg/L (date 2020.06.04.) respectively, which was less than the permission limit of 0.03 mg/L. However, it is believed that further research using more precise devices is needed in order to guarantee the safety and health of the water.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.612-617
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• 2007

This research was performed to evaluate the effect of 'Food Wastes (FW) Direct Landfilling Prohibition' on characteristics of landfill gas (LFG) and leachate and the appropriateness of current legislation. Approximately 45% (Exp.45) and 15% (Exp.15) of FW were filled in two lysimeters. During 570 days, 1400 L of LFG was generated from Exp.45%, which was much more than 906 L of Exp.15. There was no significant difference of LFG composition between Exp.15 and Exp.45. 2~30 ppmv of odorous hydrogen sulfide was detected in Exp.45, while 2~7 ppmv was in Exp.15. There was also no significant difference in the leachate generation between the two. On day 570, $BOD_5$ of Exp.45 and Exp.15 were 37000 mg/Land 25630 mg/L and $COD_{Cr}$ of Exp.45 and Exp.15 were 45480 mg/L, 30294 mg/L. TOC of Exp.45 was 2~3 times higher than Exp.15. Higher portion of FW in landfilling increased LFG generation. However, it generated more odor and made the quality of leachate. Therefore, 'FW direct Landfilling Prohibition' was evaluated as an appropriate legislation.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.1
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• pp.44-49
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• 2013

Hydrogen penetration into a metal leads to damages and mechanical degradations and its content measurement is of importance. For a precise measurement, a sample preparation procedure must be optimized through a series of studies on sample washing and drying. In this study, two-step washing with organic solvents and thermal soaking in inert gas were tried with a rod-shaped, API X65 steel sample. The samples were machined from a steel plate and then washed in acetone and etyl-alcohol for 5 minute each and dried with compressed air. After then, the samples were thermally soaked in a home-made nitrogen gas chamber during 10 minute at different heat gun temperatures from 100 to $400^{\circ}C$ and corresponding temperature range in the soaking chamber was from 77 to $266^{\circ}C$ according to the temperature calibration. Hydrogen residue in the samples was measured with a hot extraction system after each soaking step; hydrogen residue of $0.70{\pm}0.12$ wppm after the thermal soaking at $77^{\circ}C$ decayed with increase of the soaking temperature. By adopting the heat transfer model, decay behavior of the hydrogen residue was fitted into an exponential decay function of the soaking temperature. Saturated value or lower bound of the hydrogen residue was 0.36 wppm and chamber temperature required to lower the hydrogen residue about 95% of the lower bound was $360^{\circ}C$. Furthermore, a thermal desorption spectroscopy was done for the fully soaked samples at $360^{\circ}C$. Weak hydrogen peak was observed for whole temperature range and it means that hydrogen-related contaminants of the sample surface are steadily removed by heating. In addition, a broad peak found around $400^{\circ}C$ means that parts of the hydrogen residue are irreversibly trapped in the steel microstructure.

• Journal of Climate Change Research
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• v.2 no.2
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• pp.69-77
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• 2011

While increased use of energy and fossil fuel in the recent years could worsen air quality and climate change, only few studies have been conducted on estimation of greenhouse gas emissions and characterization of emission types by sectors and regions in Korea. In this study, greenhouse gases emissions based on resions(Si, Gun, Gu) and emitted sectors(industry, transport, cemmercial and institutional, residential, waste, agriculture, others) were investigated using GHG-CAPSS(Greenhouse GasClean Air Policy Support System) developed to support to national and regional greenhouse gases reduction strategies. GHG-CAPSS follows IPCC(Intergovernmental Panel on Climate Change) Guideline methodology to categorize the emission sources and estimation of greenhouse gases using bottom-up approach. Estimated total greenhouse gases emissions were 588,011 thousand tons as $CO_2$ equivalent. Industry(50.1%) sector exhibited the highest portion followed by transport(17.6%), commercial and institutional(12.6%), residential(12.6%), waste(2.6%), agriculture(2.5%). Based on regional estimation, Gyeonggi(14.9%) demonstrated the highest emitted greenhouse gases among big cities followed by Jeonnam(12.4%), Gyeongbuk(11.0%), Ulsan(9.2%) and Seoul(8.9%).

• Korean Chemical Engineering Research
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• v.62 no.3
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• pp.214-224
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• 2024

Valves play an essential role in a chemical plant such as regulating fluid flow and pressure. Therefore, optimal selection of the valve size and type is essential task. Valve size and type have been selected based on theoretical formulas about calculating valve sizing coefficient (Cv). However, this approach has limitations such as requiring expert knowledge and consuming substantial time and costs. Herein, this study developed a model for predicting valve sizes and types using machine learning. We developed models using four algorithms: ANN, Random Forest, XGBoost, and Catboost and model performances were evaluated using NRMSE & R² score for size prediction and F1 score for type prediction. Additionally, a case study was conducted to explore the impact of phases on valve selection, using four datasets: total fluids, liquids, gases, and steam. As a result of the study, for valve size prediction, total fluid, liquid, and gas dataset demonstrated the best performance with Catboost (Based on R², total: 0.99216, liquid: 0.98602, gas: 0.99300. Based on NRMSE, total: 0.04072, liquid: 0.04886, gas: 0.03619) and steam dataset showed the best performance with RandomForest (R²: 0.99028, NRMSE: 0.03493). For valve type prediction, Catboost outperformed all datasets with the highest F1 scores (total: 0.95766, liquids: 0.96264, gases: 0.95770, steam: 1.0000). In Engineering Procurement Construction industry, the proposed fluid-specific machine learning-based model is expected to guide the selection of suitable valves based on given process conditions and facilitate faster decision-making.

• Economic and Environmental Geology
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• v.48 no.2
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• pp.147-160
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• 2015

In 2014, on 31 August and 1 September, the emissions of $CH_4$, $CO_2$, and $O_2$ gases were measured six times using the closed chamber method from exposed tidal flat sediments in the same position relative to the low point of the tidal cycle in the Eoeun-ri, Taean-gun, on the Mid-western Coast of Korea. The concentrations of $CH_4$ in the air sample collected in the chamber were measured using gas chromatography with an EG analyzer, model GS-23, within 6 hours of collection, and the other gases were measured in real time using a multi-gas monitor. The gas emission fluxes (source (+), and sink (-)) were calculated from a simple linear regression analysis of the changes in the concentrations over time. In order to see the surrounding parameters (water content, temperature, total organic carbon, average mean size of sediments, and the temperature of the inner chamber) were measured at the study site. On the first day, across three measurements during 5 hours 20 minutes, the observed $CO_2$ flux absorption was -137.00 to $-81.73mg/m^2/hr$, and the $O_2$ absorption, measured simultaneously, was -0.03 to $0.00mg/m^2/hr$. On the second day using an identical number of measurements, the $CO_2$ absorption was -20.43 to $-2.11mg/m^2/hr$, and the $O_2$ absorption -0.18 to $-0.14mg/m^2/hr$. The $CH_4$ absorption before low tide was $-0.02mg/m^2/hr$ (first day, Pearson correlation coefficient using the SPSS statistical analysis is -0.555(n=5, p=0.332, pronounced negative linear relationship)), and $-0.15mg/m^2/hr$ (second day, -0.915(n=5, p=0.030, strong negative linear relationship)) on both measurement days. The emitted flux after low tide on both measurement days reached a minimum of $+0.00mg/m^2/hr$ (+0.713(n=5, p=0.176, linear relationship which can be almost ignored)), and a maximum of $+0.03mg/m^2/hr$ (+0.194(n=5, p=0.754, weak positive linear relationship)) after low tide. However, the absolute values of the $CH_4$ fluxes were analyzed at different times. These results suggest that rate for $CH_4$ fluxes, even the same time and area, were influenced by changes in the tidal cycle characteristics of surface sediments for understanding their correlation with these gas emissions, and surrounding parameters such as physiochemical sediments conditions.

• Clean Technology
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• v.24 no.3
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• pp.221-232
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• 2018

This research was conducted to evaluate the operational performance of landfill facility and landfill gas energy facility from the questionnaire survey. In order to evaluate overall operational performance, three types of weighting methods were applied to each technical, economical, and environmental item. There was no significant difference between an equal weighted method, a weighted method of 40% for technology, 30% for economy, and 30% for environment, and a weighted method of 30% for technology, 40% for economy, and 30% for environment. In technical performance, large and middle scales of landfill facilities showed higher scores of 14.8 ~ 19.7 and 14.3 ~ 19.0 than 9.8 ~ 13.0 of small scale one. In environmental performance, large, middle, and small scales of landfill facilities showed 21.3 ~ 23.7, 17.6 ~ 19.6, and 20.8 ~ 23.1 scores, respectively. However, in economical performance, there was significant difference between them with scale. Large and middle scales of landfill facilities showed higher scores of 22.0 ~ 29.3 and 20.5 ~ 27.3 than 6.0 ~ 8.0 of small scale one. As a result of evaluation for landfill gas energy facility, large scale facility showed 19.2 ~ 25.6 and 17.8 ~ 23.7 scores in technical performance and 23.1 ~ 25.7 and 21.3 ~ 23.7 scores in environmental performance, respectively. However, in economical performance evaluation, large scale of landfill gas energy facility showed relatively higher of 27.8 ~ 33.3 score than 18.8 ~ 25.1 of small scale one. From these results, it was shown that economy evaluation heavily effect on the operational performance of landfill facility and landfill gas energy facility compared to technology and environment evaluation.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.281-291
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• 2014

In March to August 2013, the emission of gases ($CH_4$, VOC, $CO_2$, $O_2$, and LEL) was measured three times from the intertidal flat sediments at Sogeun-ri, Taean-gun, in the Mid-western seashore of Korea by using chamber method. After analyzing gas emission concentrations inside of flux enclosure chamber by using a GC equipped with Agilent 6890. The gas emission fluxes were calculated from a linear regression of the changes in the concentrations with time. The ranges of gas flux during the experimental period were $+0.06{\sim}+0.60mg/m^2/hr$ for $CH_4$, $+58.45{\sim}+95.58mg/m^2/hr$ for $CO_2$, $-0.02{\sim}-0.20mg/m^2/hr$ for $O_2$, and $-0.60{\sim}+0.65mg/m^2/hr$ for VOC, respectively. The flux measurement results revealed that $CH_4$ fluxes during March in the relatively low sediment temperature ($14.5^{\circ}C$) were significantly higher ($+0.60mg/m^2/hr$) than during June and August ($+0.06{\sim}+0.18mg/m^2/hr$) in high sediment temperature ($32.0{\sim}36.8^{\circ}C$). $CH_4$ flux to mean size of sediments and temperature of inner chamber exhibited strong positive correlation ($R^2=-0.97$ and $R^2=-0.89$, respectively).