• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.164-168
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• 2005

In this paper a statcom is developed to improve the power quality in a dc traction system. The proposed statcom can be used as both inverter and active filter. As an active filter, it can compensate harmonic distortion and reactive power and as an inverter, it can recycle regenerative energy caused by decelerating trains. The simulation results are carried out by using PSCAD/EMTDC software.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.210-215
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• 1998

In this paper, systemaic approach is studied about assembility and disassemblility of parts of the gear system in order to reduce the assembly cost, and to disassemble products easily which is possible to recycle the parts. That is, an estimation of disassembly and assembly with considering of reliability life. In this study, we use symbolic chart method for an economic model for optimal disassembly and assembly.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.04b
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• pp.13-24
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• 1999

폐수 재활용방법은 반도체업계나 도금, 기타 산업에서 주로 2차 세정수를 회수하여 저급수로 직접 사용하는 방법 또는 간단한 전처리를 거쳐 원수에 혼합하여 정수처리하는 RECLAM SYSTEM과 1차 세정폐수를 분리하여 전처리와 RO 등을 거쳐 용수로써 재활용하는 PROCESS RECYCLE SYSTEM, 종합 폐수처리 후 방류수를 재활용하는 방류수 재활용설비로 구분할 수 있다. 막분리를 사용한 폐수 재활용기술에서는 방류수 재활용(종합폐수 재활용)와 원폐수 재활용(성상변 분리 재활용)만을 다루고져 한다.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.528-532
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• 2012

This study investigated the possibility of phosphogypsum (PG) recycle as an embankment material by eco-toxicity experiments for S. capricornutum, T. suecica and D. magna. The eco-toxicity experiment was studied according to column leachates from PG mixing ratio, and a specific growth rate of S. capricornutum was usually higher than that of T. suecica. For D. magna, 0.3 of toxicity unit was obtained, which indicated the below of toxicity value of 1 at PG50 condition during a 48-hr test. A minor effect of column leachate samples on three organisms was observed. This study suggested that PG was satisfied with the criteria of waste recycle and could be reused at PG30 condition.

• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.23-29
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• 2008

It has been mentioned that CSTR (Completely Stirred Tank Reactor) and UASB (Upflow Anaerobic Sludge Blanket) processes, the existing anaerobic processes, have problems in the treatment of highly concentrated particulate organic wastewater (HCPOW). Therefore, this paper discusses the treatment possibility of distillery wastewater which is a typical HCPOW using ADEPT (anaerobic Digestion Elutriated Phased Treatment) process. In the comparison of CSTR and ADEPT, ADEPT produced much higher gas than that of CSTR removing more organic matters and suspended solids in ADEPT process, ADEPT had no effect on the decrease in pH by volatile fatty acids and showed steady pH in spite of relatively short HRT. In the results of removal rate according to recycle ratios between 6Qin and 2Qin in ADEPT, 6Qin showed high removal rate during the operation time. Therefore it appears that ADEPT had an applicability for the treatment of distillery wastewater. ADEPT could be a economical process, due to the short HRT, the energy recovery by the methane production, and the utilization for carbon source of produced organic acid from the ADEPT-acid reactor.

• Hwankyungkyoyuk
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• v.11 no.1
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• pp.151-164
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• 1998

Conclusion and the improvement plan according to the survey on recycling wastes in 'the program of woman and environmental education' mainly for the chairwomen of the women's association of the apartment house in City and County of Chungchongnamdo during the first half of 1998 (from March tp April) are as follows. 1. Conclusion 1) It showed that the rate of recognition for recycle has no difference by regional groups and the rate of recognition is 57.4% but they mainly know vaguely or they do not know. 2) It showed that the rate they do not know how the separated wastes are recycled is 30.4% and the scope of their knowledge is approximative.(52.6%) 3) It showed that it is the housewives who mainly do the separate garbage collection (72.7%) and 19.1% of the people have no interest in the separate discharge. 4) It showed that the rate they filter the garbage or remove water from the garbage at house is 53.1%. And 20% of the people in the urban region dump untreated wastes but 8.5% of the people in the rural region do the same, so the rate of using garbage in the rural region is higher than that in the urban region. 5) It showed that the separate state of the garbage is 29.2% for the removal of toothpick and paper and 47.4% for the removal of vinyl and stopper. 6) It showed that 66.7% of the motive for recycling waste is the education activity for environment by the women's association and SAEMAEUL association and 34.5% of that is the influence of TV and radio. 7) It showed that the rate of making compost and feed using garbage in the rural region is higher than that in the urban region and in some urban regions, the rate they sprinkle the garbage in provisional compost state on the floor garden is high. 8) It showed that the recognition rate for the material of separately collected garbage corresponding to the separate waste system of 5-6 classification is 12.5% 9) It showed that the major variable which has an effect on the recycle is the education activity for environment by the neighborhood meeting(P<0.05) and by the women's association of saemaeul activity(P<0.05)

• Korean System Dynamics Review
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• v.9 no.2
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• pp.129-154
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• 2008

As a practical means to upgrade urban sustainability, this paper focuses on resource cyclical systems concerned with the waste of electric and electronic equipment (WEEE) in Korea. Borrowing System Dynamics concepts and approaches, it examines behavioral changes of WEEE dynamics to observe whether the existing management methods can be readjusted. The measurement is based upon both reuse and material and thermal recycle simulation works in the individual stage of WEEE discharge, collection, and treatment, going beyond the traditional recycle-only customs. This research estimates that the newly introduced Extended Producer Responsibility (EPR) system would definitely exert a significant impact on the final stage of WEEE treatment, decreasing the final treatment volume in the first half of the research period. The trend, nonetheless, would be reversed in the second half, mainly owing to the additional waste volume originated from the local government and recycling center. Sensitivity analysis poses, among others, that the local government-supported reuse center should take charge of a pivotal role in the long run. The research also shows that sufficientand necessary conditions for the WEEE management and treatment should be given to the combined efforts, both from the private sectors and the public domains. Based on these research findings, the paper recommends that key stakeholders including the producer and the public organizations should devise how to jointly carry out specific agenda centered around partnership or network buildings.

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.233-239
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• 2007

The main objective of this study was to evaluate the effect of recycled PET fiber made from waste PET bottle on the control of plastic shrinkage cracking of cement based composites. PET is blown as a plastic material and used in a variety products such as a beverage bottle. However, waste PET bottles are thrown after the usage, raising huge problems in terms of the environment. Thus, the research on the method to recycle the PET bottles indicates important aspects in environment and economy. The method to recycle waste PET bottles as a reinforcing fiber for cement based composites is one of effective methods in terms of the recycle of waste PET bottles. In this research, the effect of recycled PET fiber geometry and length on the control of plastic shrinkage was examined through thin slab tests. A test program was carried out to understand the influence of fiber geometry, length and fiber volume fraction. Three type of recycled PET fibers including straight, twist crimped and embossed type. Three volume fraction and two fiber length were investigated for each of the three fiber geometry. Test results indicated that recycled PET fibers are effective in controlling plastic shrinkage cracking in cement based composites. In respect to effect of length of fiber, longer fiber was observed to have efficient cracking controlling with low volume fraction in same fiber geometry while shorter fiber controled plastic shrinkage cracking efficiently as addition rate increase. Also, embossed type fibers were more effective in controlling plastic shrinkage cracking than other geometry fiber at low volume fraction. But, for high volume fraction, straight type fibers were most effective in plastic shrinkage cracking controlling in cement based composites.

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.245-250
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• 1985

In order to increase citric acid productivity. several attempts were made; isolation and characterization of the mutant strain produced citric acid in a high yield, citric acid fermentation in a medium containing relatively higher amount of glucose and citric acid production by the use of semicontinuous ceil recycle system. By the treatment of Candide lipolytica S-109 with NTG, a mutant J-24 was selected as the highest producer of citric acid among the strains formed larger CaCO$_3$ lytic zone. it produced 72g/1 citric acid in 10％ glucose medium. Because mutant J-24 produced 85g/l citric acid and showed 53％ yield in 16％ glucose medium, several factors were adjusted to increase the yield in 16％ glucose medium. 0.8-1.0$\times$10$^{-3}$ P/C ratio, 0.15％ urea, 0.25％ yeast extract were suitable at citric acid production in 16％ glucose medium. Under this condition, J-24 strain produced 93g/l citric acid and showed 58％ yield. Semicontinuous cell recycle system was used to protons the effective production phase, to minimize the product inhibition and to shorten the lag phase. The productivity of semicontinuous cell recycle system was 0.79g/l h while that of batch system was 0.53g/l.h

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.421-429
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• 2018

We performed process and CFD simulations of a 100 kW fuel cell system. By process simulation, we derived the input flow rate of each unit process and the recycle diesel flow rate. Through CFD simulation considering the recycle diesel flow, more efficient operational condition was found. Using 6 desulfurize reactors, a TSA process for a 100 kW fuel cell system was successfully constructed. Heat interference between reactors was found to be negligible. These results will contribute to increasing the efficiency of fuel cell system and the developed desulfurizing module design will contribute to the clean petrochemical technology as well as fuel cell systems.