• New & Renewable Energy
• /
• v.3 no.1 s.9
• /
• pp.60-67
• /
• 2007

Catalyst coated membrane [CCM] type and catalyst coated substrate [CCS] type of membrane electrode assembly [MEA] were manufactured and evaluated their performance. Degradation test were conducted to find the difference of long term stability in two types of MEA and the factor for performance degradation problem occurred. Performance degradation test of single cell in two different types of MEA were carried out when current density was $200mA/cm^{2}$. The degradation test had proceeded for 230 hours and performance degradation was checked by I-V curve and impedance measurement at regular intervals. Also, MEA before/after operation and changes of catalyst layer were characterized by SEM, TEM, and XRD. Maximum power density of CCM type was higher than that of CCS type. Meanwhile, an increase of particle size of catalyst and an increase of impedance resistance after long term operation were observed. In the case of using CCM type MEA, the performance was deteriorated 38% of initial performance. In the case of using CCS type MEA, the performance was deteriorated 43% of initial performance. In consideration of difference of initial performance, performance of CCM type is higher than that of CCS type but both types had similar problems during degradation test.

• Journal of Environmental Policy
• /
• v.13 no.1
• /
• pp.3-23
• /
• 2014

TThe CCS, gathering attention as a practical measure against climate change, has various potential risks within itself. Identifying those risks and developing proper countermeasures for each one, therefore, is essential. Failure to take proper measures against such risks may result in significant damages and accidents, causing social anxiety and unwillingness to accept CCS. This study proposes the precautionary principle as a fundamental principle for CCS risk management. While the justifications for the precautionary principle are acceptable, there have been criticisms on its limitations including its impracticality. The purpose of this study was, therefore, to identify detailed application strategies to overcome those limitations. The risk factors related to CCS consist of quantifiable risk domains as well as a number of those with high uncertainty and ambiguity. Thus, there is a need to develop differentiated coping measures, meaning that the precautionary principle should be applied. The risk assessment and management applying the precautionary principle has implication of social appraisal based on wide participation and communication among the interested parties, which may be a useful approach for expanding social applicability.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.11a
• /
• pp.356-359
• /
• 2006

고분자전해질 연료전지의 MEA를 CCM (Catalyst Coated Membrane) CCS(Catalyst Coated Substrate) 형태로 각각 제조하고 백금담지 비율이 서로 다른 백금 담지촉매를 각각 적응하여 MEA를 CCM형태로 제조하여 단위전지 성능평가를 수행하였다 백금담지 비율이 다른 촉매를 적용한 CCM형태 MEA의 표면을 SEM (scanning electron microscopy)으로 분석하였으며, 단위전지 성능평가를 수행하는 동시에 EIS (Electrochemical Impedance Spectroscopy)를 통하여 MEA의 저항을 분석하였다. 고분자전해질 연료전지의 성능은 MEA의 제조방법과 백금담지 촉매의 백금담지비율에 따라 크게 변함을 확인 할 수 있었다.

• Journal of the Korean Institute of Gas
• /
• v.27 no.3
• /
• pp.59-71
• /
• 2023

Carbon capture, and storage (CCS) is important for the reduction of greenhouse gases and achieving carbon neutrality. CCS focuses on storing captured CO₂ permanently in underground reservoirs. CO₂-enhanced oil recovery (CO₂-EOR) is one form of CCS, where CO₂ is injected into the underground to enhance oil recovery. CO₂-EOR not only aids in the extraction of residual oil but also contributes to carbon neutrality by storing CO₂ underground continuously. CO₂-EOR can be classified into miscible and immiscible methods, with the CO₂-water alternating gas (CO₂-WAG) technique being a representative approach within the miscible method. In CO₂-WAG, water and CO₂ are alternately injected into the reservoir, enabling oil production and CO₂ storage. The WAG method allows for controlling the breakthrough of injection fluids, providing advantages in oil recovery. It also induces hysteresis in relative permeability during the injection and production process, expanding the amount of trapped CO₂. In this study, the effects of enhancing oil recovery and storing CO₂ underground during CO₂-EOR were presented. Additionally, cases of CO₂-EOR application in relation to CCS were introduced.

• Journal of the Korean Institute of Gas
• /
• v.20 no.1
• /
• pp.1-6
• /
• 2016

In order to reduce the anthropogenic emission of greenhouse gases, CCS technology has emerged as the most promising and practical solution. Among CCS technology, post-combustion $CO_2$ capture is known as the most mature and effective process to remove $CO_2$ from power plant, but its energy consumption for chemical solvent regeneration still remains as an obstacle for commercialization. In this study, a process alternative integrating $CO_2$ capture with compression process is proposed which not only reduces the amount of thermal energy required for solvent regeneration but also produces $CO_2$ at an elevated pressure.

• Journal of Biomedical Engineering Research
• /
• v.14 no.3
• /
• pp.251-256
• /
• 1993

The conduction velocity of the nerve is of importance to the diagnosis of various negromuscular disorders. A major technical problem encountered in nerve stimulation technique is the control of stimulus artifact and the convenience of nerve stimulator. The remained artifacts must be removed by processing the contaminated signal. This paper discusses about the artifact cancellation algorithms in constant voltage type nerve stimulator(CVS) and constant current type nerve stimulator(CCS).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2018.05a
• /
• pp.234-236
• /
• 2018

기후변화는 더 이상 피할 수 없는 매우 중요한 문제다. 온실가스 중 큰 비중을 차지하는 이산화탄소 배출을 억제하거나 제거하기 위한 많은 연구들이 진행되고 있다. 최근에는 CCS 중 하나인 지중저장(underground storage)의 대안으로 해양에 이산화탄소를 저장하는 기술인 AWL(Accelerated Weathering of Limestone)을 이용한 해양저장(ocean storage)에 대한 연구가 진행되고 있다. AWL은 이산화탄소를 중탄산이온 형태의 농축수로 만들어 해양에 방류하여 희석 저장시키는 방법으로, 대기 중 재방출이 거의 발생하지 않고 배출된 농축수는 해양의 알칼리도를 높여 해양산성화를 방지할 수 있는 장점이 있다. 금회 연구는 AWL에 의한 방법 중 중탄산이온 농축수의 해양방류 시 이산화탄소 등을 포함하는 용존 무기탄소(DIC, Dissolved Inorganic Carbon)의 거동특성을 파악하기 위한 목적으로 수행하였다. 연구대상 해역은 충분한 수심과 작업효율성이 확보되는 울릉도 부근으로 설정하였으며, 거동특성을 파악하기 위하여 표층방류(surface discharge)와 수중방류(submerged discharge)에 의한 물질확산을 계산할 수 있는 CORMIX모형을 채택하였다. 실험결과, 방류 시점으로부터의 희석률을 고려했을 때, 표층방류 시나리오가 농축수 방류에 가장 적합한 방식이라고 사료된다.

• Korean Chemical Engineering Research
• /
• v.48 no.1
• /
• pp.116-120
• /
• 2010

$CO_2$ is regarded as one of the greenhouse gases(GHG), which is the main reason of climate change. In order to achieve lower $CO_2$ emissions, several efforts have been conducted worldwide. $CO_2$ capture & storage(CCS) technology development is needed for a coal-fired combustion power plant because of huge $CO_2$emission. Oxy fuel combustion, one of the CCS technologies has been considered as a primary concern, nowadays. Oxy-fuel combustion needs flue gas recirculation(FGR) for stable operation and enrichment of $CO_2$ concentration in the flue gas. FGR adoption for oxy-fuel combustion requires development of effective desulfurization and dust removal technology. In this study, desulfurization characteristics of lime and dust removal technology have been researched in the laboratory scale coal combustor.

• Clinical and Experimental Reproductive Medicine
• /
• v.35 no.4
• /
• pp.285-291
• /
• 2008

Objective: This study was performed to investigate whether cumulus morphology and oocyte diameter influence on in vitro maturation (IVM) of human germinal vesicle (GV) stage oocytes obtained from stimulated in vitro fertilization (IVF) cycles. Methods: Forty-one GV stage oocytes were obtained from 21 patients who received ovarian hyperstimulation and IVF. According to cumulus morphology before denudation, GV oocytes were classified into oocytes with dispersed cumulus cells (CCs) or compacted CCs. The diameters of denuded oocytes, both including and excluding the zona pellucida, were measured. All oocytes were cultured in commercial IVM medium. Maturation was defined as extrusion of the first polar body and the matured oocytes were inseminated by ICSI method. Results: Overall maturation and fertilization rate were 56.1% and 73.9%. Matured oocytes had significantly higher proportion of oocytes with dispersed CCs compared to oocytes failed to mature (91.3% vs. 55.6%, p=0.023). There were no significant differences of oocytes outer ($155.7{\mu}m$ vs. $152.4{\mu}m$, NS), inner ($114.3{\mu}m$ vs. $113.4{\mu}m$, NS) diameters and zona thicknesses ($41.3{\mu}m$ vs. $39.1{\mu}m$, NS) between matured and not-matured oocytes. In-vitro maturation rate of oocytes with dispersed CCs was significantly higher than which of oocytes with compacted CCs (67.7% vs. 20.0%, p=0.044). Oocyte diameters (outer and inner) and thicknesses were not related with maturational competence. Conclusion: Our results suggest that in vitro maturational competence of GV stage oocytes obtained from stimulated IVF cycles is closely associated with the cumulus morphology but not oocyte diameter.

• Proceedings of the KOSOMBE Conference
• /
• v.1992 no.05
• /
• pp.209-212
• /
• 1992

A major technical problem in encountered in nerve stimulation technique is the control of stimulus artifact and the convenience of nerve stimulator. The artifacts remained must be removed by processing the contaminated signal. This paper discusses about the artifact cancellation algorithms in constant voltage type nerve stimulator(CVS) and constant current type nerve stimulator(CCS).