• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.552-557
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• 2015

Ballast gravel in a railroad field is often polluted by grease and heavy metals. In this paper, the performances of a dry cleaning method for polluted ballast gravel in which pollutants on the gravel surface can be physically removed was extensively studied. A polluted ballast cleaning device able to shoot emery blasting media onto the surface using compressed air was prepared. Polluted ballast gravel was put into this device for cleaning, with the treatment time varied from 1 to 10 min. The cleaning efficiency of the total petroleum hydrocarbons and heavy metals were studied. The total petroleum hydrocarbon removal efficiency was 70-80% for gravels sampled from a locomotive waiting line, while it was 40-60% for gravels sampled from a turnout area. The heavy metal removal efficiency exceeded 90% for copper and lead, while it was 65-80% for nickel and zinc. This system was found to be effective for the remediation of polluted ballast gravels.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.405-414
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• 2021

This study predicted waxy corn harvest date in South Korea using 30-year (1991-2020) hindcasts (1-6 month lead) produced by the Pusan National University Coupled General Circulation Model (PNU CGCM)-Weather Research and Forecasting (WRF) chain. To estimate corn harvest date, the cumulative temperature is used, which accumulated the daily observed and predicted temperatures from the seeding date (5 April) to the reference temperature (1,650~2,200℃) for harvest. In terms of the mean air temperature, the hindcasts with a bias correction (20.2℃) tends to have a cold bias of about 0.1℃ for the 6 months (April to September) compared to the observation (20.3℃). The harvest date derived from bias-corrected hindcasts (DOY 187~210) well simulates one from observation (DOY 188~211), despite a slight margin of 1.1~1.3 days. The study shows the possibility of obtaining the gridded (5 km) daily temperature and corn harvest date information based on the cumulative temperature in advance for all regions of South Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.3
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• pp.169-178
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• 1974

Concentrations of mercury, cadmium, lead and copper are determined in the surrounding seawater and in seaweeds, Undarta pinnatifida and Sargassun fulvellum, from Suyeong Bay in Busan in the spring tide and neap tide from January to April 1974. The range and mean of the heavy metal concentrations in the surrounding seawater are as follows : mercury 0.00-0.39 ppb, 0. 16ppb; cadmium 0.00-0.46 ppb, 0.18 ppb, lead 0.00-0.94 ppb, 0.26 ppb : copper 0.00-0.86 ppb, 0.25 ppb respectively, and the concentrations varied slightly according to the tide. The mean values of concentration rate of Hg, Cd, Pb and Cu in air dry base were $0.42\times10^3(0.13\times10^3\~1.0\times10^3)$, $2.1\times10^3(0.8\times10^3\~4.9\times10^3)$, $8.9\times10^3(3.1\times10^3\~19\times10^3)$ and $15\times10^3(6.0\times10^3\~28\times10^3)$ in the Undaria pinnatifida, and $0.25\times10^3($0.06\times10^3\~0.56\times10^3)$, $1.0\times10^3(0.61\times10^3\~1.7\times10^3)$, $5.4\times10^3(3.1\times10^3\~8.5\times10^3)$ and $22.8\times10^3(14.4\times10^3\~52.4\times10^3)$ in the Sargassun fulvellum. The concentration rate of Hg, Cd and Pb of the Undaria pinnatifida was almost twice as much as that of the Sargassun fulvellum but the concentration rate of copper of the former was slightly smaller than of the latter.

• Resources Recycling
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• v.16 no.3 s.77
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• pp.50-60
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• 2007

There are several kinds of battery such as zinc-air battery, lithium battery, Manganese dry battery, silver oxide battery, mercury battery, sodium-sulphur battery, lead battery, nickel-hydrogen secondary battery, nickel-cadmium battery, lithium ion battery, alkaline battery, etc. These days it has been widely studied for the recycling technologies of the used battery from view points of economy and efficiency. In this paper, patents on the recycling technologies of the used lithium battery were analyzed. The range of search was limited in the open patents of USA(US), European Union(EP), Japan(JP), and Korea(KR) from 1986 to 2006. Patents were collected using key-words searching and filtered by filtering criteria. The trends of the patents was analyzed by the years, countries, companies, and technologies.

• Resources Recycling
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• v.17 no.2
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• pp.76-84
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• 2008

There are several kinds of battery such as zinc-air battery, lithium battery, manganese dry battery, silver oxide battery, mercury battery, sodium-sulphur battery, lead battery, nickel-hydrogen secondary battery, nickel-cadmium battery, lithium ion battery and alkaline battery, etc. These days it has been widely studied for the recycling technologies of the used battery from view points of economy and efficiency. In this paper, patents on the recycling technologies of the used manganese dry battery were analyzed. The range of search was limited in the open patents of USA (US), European Union (EP), Japan (JP), and Korea (KR) from 1986 to 2006. Patents were collected using key-words searching and filtered by filtering criteria. The trends of the patents were analyzed by the years, countries, companies, and technologies.

• Resources Recycling
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• v.21 no.4
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• pp.16-25
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• 2012

There are several kinds of batteries such as zinc-air battery, lithium battery, Manganese dry battery, silver oxide battery, sodium-sulphur battery, lead acid battery, metal hydride secondary battery, nickel-cadmium battery, lithium ion battery, alkaline battery, etc. These days it has been widely studied for the recycling technologies of the used battery from view points of economy and efficiency. In this paper, patents and published papers on the recycling technologies of the used battery were analyzed. The range of search was limited in the open patents of USA (US), European Union (EU), Japan (JP), Korea (KR) and SCI journal articles from 1972 to 2011. Patents and journal articles were collected using key-words searching and filtered by filtering criteria. The trends of the patents and journal articles were analyzed by the years, countries, companies, and technologies.

• Fashion & Textile Research Journal
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• v.18 no.3
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• pp.351-362
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• 2016

Domestic sewing industry is showing signs of a redevelopment and the demands of the sewing technician are gradually increasing. This study would investigate the opinions of sewing technicians about job environments and training situation in order to solve the shortage of sewing manpower. As a result of a survey with 100 sewing technicians, of the pay systems, the salary system showed the highest satisfaction and preference. Their satisfaction with pay was low. There was a tendency that they work on Saturdays and national holidays, and their satisfaction with the number of holidays was low. Most worked for 10 to 11 hours per day, and they showed low satisfaction with their working hours. There were no places to rest in the company. They showed law satisfaction with the air and vent. The sewing technicians were concerned about respiratory and musculoskeletal diseases because of the working and workplace environment and needed places to rest, vent facilities, and spacious and comfortable spaces. The total lead-time that they were sent to the field as skilled workers was 1 to less than 2 years; they received training from seniors; and the training period, mostly, was 6 months to 2 years. Most of the sewing technicians surveyed had the expertise, did not feel the necessity of retraining related to their tasks, and did not have any willingness to take reorientation due to a lack of time even with their tasks.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.3
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• pp.326-335
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• 2017

It is known that diesel engines have the disadvantage of high emission levels of NOx and PM. Therefore, many combustion strategies have been developed to reduce these harmful NOx and PM emissions in a diesel engine. Among these strategies, HCCI(Homogeneous Charge Compression Ignition) and PCCI(Premixed Charge Compression Ignition) are the most popular as these can reduce NOx and PM simultaneously. However, when a single fuel like diesel is applied, it is difficult to control the combustion phase and this can lead to power reduction. In this study, premixed gasoline and pilot diesel were used to overcome the problems of controllability of the combustion phase and harmful emissions. We injected gasoline directly into the combustion chamber and the gasoline/air mixture was ignited with a pilot diesel fuel near the top dead center. The results showed that the combustion and emission characteristics of dual-fuel combustion were comparable to those of conventional diesel combustion. When we applied the dual-fuel PCCI combustion concept, more than 90 % of NOx and PM emission was reduced simultaneously without significant degradation of efficiency compared to conventional diesel combustion.

• Journal of the Korean Institute of Gas
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• v.24 no.3
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• pp.40-46
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• 2020

Tertbutylperoxymaleate is the one of the organic peroxides used as a raw material of initiator formulations of artificial marble manufacturing. In this study, the thermal decomposition characteristic of TBPM was evaluated using the differential scanning calorimeter in the air and nitrogen circumstance. Regardless of the reaction atmosphere, TBPM showed the exothermic peak due to the drastic decomposition reaction below 130 ℃. The activation energy estimated by dynamic methods had a range of 203~217 kJ/mol and that estimated by model-free analysis method had a range of 118~232 kJ/mol with a thermal conversion. And the ADT₂₄, the temperature that lead to the maximum heating rate within 24 hours, was evaluated as (80~95) ℃ using the estimated activation energy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.9
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• pp.792-798
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• 2007

catalytic combustion is accomplished by the chemical reaction between fuel and oxidizer at the catalyst surface, different from conventional combustion. Therefore, it is important that the fuel and air stream are well mixed and supplied uniformly prior to the combustion region. If the flow is maldistributed, a hot spot may occur that can lead to subsequent catalyst and substrate damage. Therefore, in order to enhance the mixing and flow uniformity, in this study, the perforated plate is used. A numerical simulation is performed to investigate the variation of flow characteristics by changing various parameters. Under each condition, the uniformity of the flow stream at the entrance of the catalyst section is evaluated and compared. The results show that the uniformity can be effectively improved for most of the case by using the well-designed perforated plates.