• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.459-459
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• 2012

Recently, the discharge of global warming gases in dry etching process of TFT-LCD display industry is a serious issue because perfluorocarbon compound (PFC) gas causes global warming effects. PFCs including CF4, C2F6, C3F8, CHF3, NF3 and SF6 are widely used as etching and cleaning gases. In particular, the SF6 gas is chemically stable compounds. However, these gases have large global warming potential (GWP100 = 24,900) and lifetime (3,200). In this work, we chose C3F6O gas which has a very low GWP (GWP100 = <100) and lifetime (< 1) as a replacement gas. This study investigated the effects of the gas flow ratio of C3F6O/O2 and process pressure in dual-frequency capacitively coupled plasma (CCP) etcher on global warming effects. Also, we compared global warming effects of C3F6O gas with those of SF6 gas during dry etching of a patterned positive type photo-resist/silicon nitride/glass substrate. The etch rate measurements and emission of by-products were analyzed by scanning electron Microscopy (SEM; HITACI, S-3500H) and Fourier transform infrared spectroscopy (FT-IR; MIDAC, I2000), respectively. Calculation of MMTCE (million metric ton carbon equivalents) based on the emitted by-products were performed during etching by controlling various process parameters. The evaluation procedure and results will be discussed in detail.

• 한국농공학회논문집
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• 제60권1호
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• pp.79-87
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• 2018

Water management impacts both methane ($CH_4$) and nitrous oxide ($N_2O$) emissions from rice paddy fields. Although irrigation is one of the most important methods for reducing $CH_4$ emission in rice production systems it can also $N_2O$ emissions and reduce crop yields. A feasibility study on the system of rice intensification (SRI) methods with respect to irrigation requirements, greenhouse gas (GHG) emissions was conducted for either 2 or 3 years depending on the treatment in Korea. The SRI methods (i.e. SRI and midsummer drainage (MD) with conventional practice (CT)) reduced the irrigation requirement by 49.0 and 22.0 %, respectively. Global warming contribution of GHG to different depending on the type of GHG. Therefore, the emission of $CH_4$ and $N_2O$ shall be converted to Global Warming Potential (GWP). The GHG emission from the conventional practice with midsummer drainage (MD) and the SRI plots, in GWP were reduced by 49.1 and 77.1 %, respectively. Application of SRI water management method could help to improve Korea's water resources and could thus contribute to mitigation of the negative effects of global warming.

• Perspectives in Nursing Science
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• 제6권1호
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• pp.21-37
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• 2009

The purpose of this GWP project was two-fold:(1) to launch an organizational culture improvement for great workplace (2) to improve the perception of nursing personnel on communication and team work in a surgical nursing department of a teaching hospital in Seoul. Using one group pretest-posttest design, nursing personnel's perception on organizational culture related to communication and team work was evaluated. A 10-item, 5-point scale (1.5) survey was administered to 209 nursing personnel in January 2009 and again to 191 nursing personnel in October 2009. From January 2009, AMANNA team has taken activities focused on trust, pride, and fun. AMANNA is an abbreviation of Korean language, which means wonderful meeting and sharing in English. Monthly activities are as follows: choral concerts by nurse managers, welcome and farewell events, praising members for their services, explaining current circumstances, etc. Special activities are as follows: a New Year's greeting party, a spring picnic, beauty classes, a lecture on drug administration, cultural lectures using videos, and presentations of academic posters and another activity. The reliability of measurement was Cronbach's ${\alpha}$: 0.917(pretest), 0.954(posttest). Most nursing personnel's perception on organizational culture was improved (pretest mean=3.50 and posttest mean=3.78, p<.001). "A sense of belonging" showed the greatest improvement among the 10 items(3.18 vs. 3.56, p<.001). "Trust each other" showed the highest score (mean=3.98) in posttest. Frequency of participation and satisfaction showed a significant relationship(r=0.179, p=.021). We believe that this project has made a contribution towards a positive organizational culture. The keys to this initiative's preliminary success have been the leadership support and flexibility in implementing the interventions tailored to the hospital.

• Tribology and Lubricants
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• 제35권4호
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• pp.206-214
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• 2019

This study investigates alternative refrigerants and refrigerant oils as well as the tendency of protecting the global environment in view of automobile air-conditioning systems. Since decades, the R12 refrigerant is not used in automobile air-conditioners because of the ozone depletion potential (ODP) problem, and for the last 20 years, the ODP-free R134a refrigerant is leading the new automotive air-conditioning market. However, owing to its high global warming potential (GWP), the R134a refrigerant use in automobile air-conditioning system is also prohibited by law, and alternative refrigerants with a low GWP need to be proposed. Therefore, recently, the application of R1234yf, R152a, or other alternative refrigerants has started worldwide. By contrast, natural refrigerant R744 was introduced in the market several years ago by VDA (Verband Der Automobilindustrie), which is a German association in the automotive industry. This study also deals with refrigerant oils. For a long time, polyalkylene glycol (PAG) oil has been traditionally used with automobile air-conditioners, and polyolester (POE) oil is suitable for HEV, PHEV, and EV air-conditioning systems, where it is used by the electrically driven compressor owing to its excellent electrical insulation properties. Finally, PAG is an excellent lubricant for all the R134a, R152a, R1234yf, and R744 refrigerants, and has the advantage that it can be applied rapidly to alternative refrigerant air-conditioning systems.

• 대한환경공학회지
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• 제38권11호
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• pp.589-595
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• 2016

본 연구는 전과정평가 기법으로 석유화학업체에서 발생하는 폐수처리슬러지의 매립처리에 대한 잠재적인 환경영향을 평가하고 매립가스 활용에 의한 환경영향의 저감을 평가하였다. 본 연구의 기능단위는 '폐수처리슬러지 1 ton의 매립'이며, 시스템경계는 폐수처리슬러지가 매립장으로 투입 처리되는 과정을 포함하며 외부에너지 생산 및 이용까지 확장하였다. 환경영향은 매립공정 및 침출수처리공정에서 높게 나타났으며, 지구온난화 및 광화학적산화물생성은 매립공정에서, 자원고갈, 산성화, 부영양화, 오존층파괴는 침출수처리공정에서 높게 나타났다. 영향범주별 주요원인물질은 Crude oil(자원고갈), $NO_X$(산성화, 부영양화), $CH_4$(지구온난화, 광화학적산화물생성), $Cl_2$(오존층파괴) 이었다. 자원고갈, 산성화, 부영양화는 침출수처리과정 중 사용되는 전기의 생산에 의한 부하가 주원인으로 나타났으며, 지구온난화, 광화학적산화물생성은 포집되지 않는 매립가스에 포함된 메탄이 주원인이었다. 이에 매립가스에 의한 전기 생산, 공정개선 등으로 전기사용량을 저감하거나 메탄가스 회수율 향상, Flaring system, 매립가스의 연료대체 등으로 메탄배출량을 저감하는 것이 환경영향을 저감하는 방안이 될 수 있다. 한편, 영향범주별 환경영향은 지구온난화-자원고갈-광화학적산화물생성 순으로 나타나 지구온난화가 약 90% 이상의 절대적 환경영향을 미치는 것으로 나타났다. 이에 환경영향을 줄이는데 메탄의 배출량을 저감하는 것이 전기사용량을 저감하는 것보다 우선순위가 높은 것으로 나타났다. 매립가스의 연료대체에 의한 회피효과를 검토한 결과, B-C유 또는 LNG를 대체할 경우 각각 32.7%, 12.0%의 환경영향을 저감할 수 있는 것으로 나타났다.

• 자원리싸이클링
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• 제32권2호
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• pp.12-18
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• 2023

우리나라는 2018년 기준 전기전자 분야에서 은 수요는 249백만 톤으로 조사되었으며, 태양광 모듈용으로는 81백만 톤으로 조사되었다. 현재 태양광 모듈 설치의 급증으로 해당 분야의 은 사용량 또한 증가하고 있는 추세이다. 그러나 우리나라의 금속자원 및 부존량은 소비량 대비 부족한 실정이며, 금속자원 중 은광의 국내 자급률은 2021년 기준 약 2.2%로 매우 낮은 상황으로 조사되어 이를 개선하기 위해 금속산업에서 발생하는 폐도금액내 함유되어 있는 유가금속 자원회수기술을 통한 재활용이 필요하다고 판단된다. 따라서, 본 연구에서는 전과정평가를 통해 폐도금액 내 유가금속 회수공정 개선에 따른 영향평가 결과를 비교 분석하고자 하였다. 그 결과, 개선을 통해 GWP 및 ADP는 각각 약 49% 및 67% 저감되는 것으로 나타났다. 그 중, 전기 및 상수의 GWP는 각각 98% 및 93% 저감되는 것으로 나타나 에너지 소비 최소화에 크게 기여하는 것으로 나타났다. 따라서, 재자원화 기술의 발전이 화학물질 및 에너지의 사용 절감할 수 있으며, 이를 통해 도시광산산업에서 자원생산성을 향상시킬 수 있을 것으로 판단된다.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.170-176
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• 2007

It is time to prepare the phaseout of R134a, the current refrigerant, in automotive air conditioning system because the EC deadline has been coming with new platform vehicles in 2011 and all vehicles by 2017. Until now a high-pressure carbon dioxide($CO_2$) system is the leading replacement of R134a in European auto-makers but there is no firm agreement in the world automotive market. Recently three new fluids have been announced as the possibilities from Honeywell, DuPont and INEOS Fluor. The new alternative refrigerant should meet the requirements like non flammable, non toxic, no ozone depletion effect and low GWP(under 150 to meet EC regulation). The objectives of this paper are to review the fluid H from Honeywell, the more possible alternative refrigerant in 3 new fluids, compare the properties of R134a & fluid H and see the possibility as a replacement of R134a. In this experimental paper we ran and reviewed the cooling performance data in the bench system, the vehicle and the field test. We found the possibility of fluid H system to meet the R134a system performance with some hardware modifications but agreed that it is still needed to study about the long term safety, environmental effects, material compatibilities and so on.

• 한국지열·수열에너지학회논문집
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• 제13권4호
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• pp.14-20
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• 2017

Refrigerant having high global warming potentials will be phased out due to environmental protection issues. R410A has been widely used in geothermal heat pump. However, it has a little high GWP by 2088 value. One of the recommended substitute for R410A refrigerant is R452B which having a GWP by 698 value. In this paper, the heating and cooling performance of the water-to-water geothermal heat pump unit with R452B was experimentally investigated. The performance of the heat pump adopting R452B was also compared with the system applying R410A. The heating and cooling capacity of R452B heat pump system showed a slightly lower values within 2% comparing with R410A system. However, the R452B system's coefficient of performance was enhanced by 5.2% and 13.7% at heating and cooling mode, respectively.

• 한국수소및신에너지학회논문집
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• 제27권4호
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• pp.462-469
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• 2016

This paper presents the results of thermodynamic cycle analysis and performance tests of alternative mixtures in low temperature applications. Two near-azeotropic binary mixtures R-152a/R-1270 (35:65 by wt.%) and R-290/E170 (35:65 by wt.%) are considered in this study. They have zero ODP (Ozone Depletion Potential) and much lower GWP (Global Warming Potential) than R-404A which is an alternative of R-502. Refrigeration cycle characteristics such as cooling capacity, coefficient of performance, suction and discharge pressures and temperatures are compared to those for the baseline refrigerants (R-502 and R-404A) cycles. The performance tests are conducted at the evaporation and condensation temperatures of $5^{\circ}C$ and $45^{\circ}C$, subcooling and superheating temperatures of $5^{\circ}C$, respectively. Performance comparisons between baseline and alternative refrigerants are conducted on the same cooling capacity. The system performance of newly proposed refrigerant mixtures show promising results.

• 한국수소및신에너지학회논문집
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• 제32권5호
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• pp.356-364
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• 2021

During the hydrogen fueling process, hydrogen temperature inside the compressed tank were limited below 85℃ due to the allowable pressure of tank material. The chiller system to cool compressed hydrogen used R407C, greenhouse gas with a high global warming potential (GWP), as a refrigerant. To reduce greehouse gas emission, it should be replaced by refrigerant with a low GWP. This study proposes a chiller system for fueling hydrogen with R290, consisted in propane, by applying the C3 pre-cooled system use d in the LNG liquefaction process. The proposed system consisted of hydrogen compression and cooling sections and optimized the operating pressure through exergy analysis. It was also compared to the exergy efficiency with the existing system at the optimal operating pressure. The result showed that the optimal operating pressure is 700 kPa in 2-stage, 840 kPa/490 kPa in 3-stage, and the exergy efficiency increased by 17%.