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Plastic recycling and material flow of packaging expanded polystyrene by EPR in South Korea
( Hakyun Song ),( Youngsun Kwon ),( Yong-chul Jang ),( Byeonghwan Kim ),( Dong Gyu Shin ),( Yongseon Lee ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-
Expanded polystyrene (EPS) is one of the thermoplastic polymers that are widely used in many industrial applications such as insulation, packaging, aquaculture floats, and buoys. Since it has the property of easy material decomposition into small microplastics under natural environment, stringent management measures for such materials are urgently required. In this study, material flow analysis (MFA) was conducted to determine quantitative flows of the materials by life cycle (manufacturing, use, collection, recycling and disposal). Based on the results, the predicted EPS consumption by 2030 was estimated using several linear regression methods. In 2019, approximately 47,000 tons of packaging EPS out of total 337,000 ton EPS were consumed and distributed in Korea. About 53,000 tons of waste EPS forms were collected by recycling waste streams, out of which 41,900 tons were recycled as ingot (40,871 tons), fire-resistance coatings for steel frames (1,521 tons), and pellet (287 tons). By using the regression analysis, from 2003 to 2019, the amount of EPS consumption was steadily increased, and the cumulative amount of EPS recycling by the period was estimated to be about 412,000 tons by 2030. This study evaluated the potential benefits of resource savings and reduction of greenhouse gas emissions through EPS packaging recycling.
Study on the Effect of Pressurizer Cutting Scenario
Hakyun Lee,Sunil Kim,Minho Lee,Jongsoon Song 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
When a permanently-closed nuclear power plant is to be decommissioned, large structures targeted to be cut in the process include a steam generator, reactor, and reactor coolant pump (RCP). Although there are sufficient preliminary studies being done on these structures to assess the radiation exposure dose, relatively fewer studies are underway regarding pressurizers. Therefore, preliminary evaluations are required to prevent workers from being overexposed to radiation coming from a pressurizer and to avoid an unnecessary increase in the decommissioning cost. This study created a cutting scenario based on disposal drums for solid radioactive wastes. The cutting scenario was based on 200-liter and 320-liter drums for solid wastes and on the assumption that all cutting operations were done 100 centimeters away from the structure to be cut. When are cutting process of a Pressurizer is carried out per scenario, the 200-liter drum produces 272 pieces, whereas the 320-liter counterpart generates 234 pieces. Given that South Korea allocates 75,550 KRW per liter (based on 200 L) for the disposal cost, an increase in the number of drums leads to an exponential growth of the decommissioning cost, which fuels the need to establish more organized cutting strategies. Meanwhile, in terms of radiation dose, plasma, laser, and flame cutting techniques were estimated to record 0.232 mSv, 0.299 mSv, and 0.213 mSv respectively for 200 L, and 0.195 mSv, 0.251 mSv, and 0.179 mSv respectively for 320 L (based on DF-90). When compared with the annual dose limit of 100 mSv (0.0057 mSv·hr?1), the above numbers registered for both 200 L and 320 L were estimated to satisfy the dose limit, with only a negligible difference in the dose between the two capacities. The results generated from this study are expected to be utilized as a meaningful basis to identify applicable cutting techniques of a pressurizer as part of the decommissioning operation and to establish its cutting plans in compliance with ALARA.
A Study on the Development of Fuzzy Linear Regression I
Kim, Hakyun Korea Association of Information Systems 1995 情報시스템硏究 Vol.4 No.-
This study tests the fuzzy linear regression model to see if there is a performance difference between it and the classical linear regression model. These results show that FLR was better as f forecasting technique when compared with CLR. Another important find in the test of the two different regression methods is that they generate two different predicted P/E ratios from expected value test, variance test and error test of two different regressions, though we can not see a significant difference between two regression models doing test in error measurements (GMRAE, MAPE, MSE, MAD). So, in this financial setting we can conclude that FLR is not superior to CLR, comparing and testing between the t재 different regression models. However, FLR is better than CLR in the error measurements.
임하균(Hakyun Lim),김종현(Jonghyun Kim),이정엽(Jeongyeob Lee) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Examination and study of drivetrain layout for special purpose vehicle is essential to select commercial off-the-shelf axles or to develop new axles. Operating environments for special vehicle are pavement rode, off road and water. Part time drives can be considered to enhance a fuel efficiency, handling, turning circle radius, etc. Main target in this study is a decision on the driving axles according to operating road conditions and to examine optimal axle models for each axle related to inter axle differential. Weighted value skill was mainly applied to drivetrain layout assessment. Design processes and parameters in this research are available to use similar drivetrain layout and to select suitable parts.