• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.2
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• pp.191-198
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• 2008

Flow accelerated corrosion (FAC) phenomenon of low alloy carbon steels in nuclear power plant has been known as one of major degradation mechanisms. It has a potential to cause nuclear pipe rupture accident which may directly impact on the plant reliability and safety. Recently, the equipotential switching direct current potential drop (ES-DCPD) method has been developed, by the present authors, as a method to monitor wall loss in a piping. This method can rapidly monitor the thinning of piping, utilizing either the wide range monitoring (WiRM) or the narrow range monitoring (NaRM) technique. WiRM is a method to monitor wide range of straight piping, whereas NaRM focuses significantly on a narrow range such as an elbow. WiRM and NaRM can improve the reliability of the current FAC screening method that is based on computer modeling on fluid flow conditions. In this paper, the measurements by ES-DCPD are performed with signal sensitivity analyses in the laboratory environment for extended period and showed the viability of ES-DCPD for real plant applications.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.110.2-110.2
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• 2011

바이오가스 생산은 현재 정부에서 추진하고 있는 저탄소 녹색성장으로 인해 더욱 그 가치의 중요성이 부각되고 있다. 스웨덴 Scandinavian Biogas Fuel AB(SBF) 사의 바이오 가스 생산 기술을 이용함으로 소화효율을 개선하고 바이오가스 발생량을 극대화하였다. 전국 403개 공공하수처리시설 중 소화조가 설치된 처리시설은 65 개소이며 이중 57 개소에서 총 64개 소화조를 운영 중이다. 하지만 국내 소화조의 효율은 유입수질 저하, 운영, 관리 미숙으로 인해 전진국의 1/4 수준으로 에너지 이용률이 미미한 편이다. 환경부는 2010년부터 에너지 이용, 생산사용 확대, 추진을 위해 하수처리시설별 이용 가능한 에너지 잠재력의 종류, 양, 지역 내 수요자, 공급자 의 현황 규모 등을 정리해 2012년부터 에너지 이용사업 확대를 추진한다. SBF의 기술을 바탕으로 하수처리시설에서 들어오는 하루 슬러지 $1370m^3$와 음식물쓰레기 180t을 함께 처리하며 바이오가스 생산량을 더욱 늘렸다. 각 $7,000m^3$의 달걀모양(egg shape) 소화조 2개를 운영하며 생 슬러지와 음식물 쓰레기 처리 후 바로 소화조로 투입, 혐기 소화하는 방식이며 슬러지 최종처분방법은 탈수 후 소각된다. 반입되는 생 슬러지의 평균 TS 1.7%, VS 63% 이며 농축 후에는 평균 TS 9%, VS 75% 이다. 또 소화조로 들어가는 음식물 쓰레기는 평균 TS 8%, VS 85% 이며 소화 후 평균 TS 3.6% VS 59% 이다. 그리고 소화조의 pH는 7.3~7.8,유기산의 농도는 150mg/L~350mg/L, 가스발생량은 하루 평균 $26,500Nm^3$이며 소화효율은 평균 67%이다. 혐기성소화는 산소가 없는 무 산소 상태 에서 분해 가능한 유기물을 분해시켜 메탄으로 전환시키고 우리는 현재 이 가스를 소화조 가온에 사용하고, 판매하고 있다. 소화효율을 높이기 위하여 가온과 교반이 행해지는데 가온방식은 직접가온방식(증기주입식)과 간접가온방식(열교환방식)이 있다. 그중 우리는 간접가온방식을 채택하여 소화효율을 높였고 일반중온 혐기소화온도보다 약간 높은 $38^{\circ}C$로 운전한다. 그리고 일반적으로 알려진 교반방식인 가스교반, 기계교반, 이 둘은 병행한 교반이 아닌 독자적인 방법을 이용, 소화조 내의 슬러지가 정체되어 교반되지 않는 부분을 최소화 하였다. 이때 미생물이 투입되기 힘든 소화조 아래 쪽 으로도 고루분포 되어 슬러지를 이용 하게 되고 소화조 상하부의 온도차가 $1^{\circ}C$ 이하로 거의 완벽한 교반상태를 보여 줌 으로써 소화효율을 최대한으로 한다. 더욱이 소화일수 부족으로 인한 전반적 소화효율 저하가 발생하지 않도록 input과 output 조절을 통한 적정소화일수 20~25일을 최대한 맞추어 운전하여 소화조 설계용량의 평균 90%를 활용하고 있다.

• Journal of Korea Port Economic Association
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• v.27 no.3
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• pp.331-348
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• 2011

Recently, international society strongly concerns global green house effect. As a result each nation introduces green policy for their economy and sustainable development. The emissions of carbon dioxide come from various sources, such as ports and port activities. Especially, port is a logistics hub for shipping, road and railways. Therefore, successful reduction of emissions in the port may encourage other transportations to reduce emissions. Korea as developing country is excused from Annex I countries which committed themselves to reduce four greenhouse gases. However, Korea is going to be placed in Annex I countries in 2013. Korean economy is heavily dependent on international trade and especially, 99.8% of its international trade cargoes is transported through the ports. Therefore, Eco-port plays a very important role in future Korean sustainable development. By introducing the most advanced port pollution regulations, Japan has taken a immediate step for Eco-port policy. International trade is very significant in Korea as well as in Japan, both nations have similar industrial structure. Therefore, Korea should pay attention to Japanese Eco-port policy and activities. This paper examines Japanese Eco-port policy and its' implications in order for Korea to find the most efficient way to reduce the emissions as Korea should reduce greenhouse gas emissions in post kyoto system.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.493-499
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• 2013

For the purpose of utilizing fly ash from gasification of low rank coal, we performed the series of experiments such as pyrolysis and char-$CO_2$ gasification on fly ash by using the thermogravimetric analyzer (TGA) at non-isothermal heating conditions (10, 20 and $30^{\circ}C/min$). Pyrolysis rate has been analyzed by Kissinger method as a first order, the reliability of the model was lower because of the low content of volatile matter contained in the fly ash. The experimental results for the fly ash char-$CO_2$ gasification were analyzed by the shrinking core model, homogeneous model and random pore model and then were compared with them for the coal char-$CO_2$ gasification. The fly ash char (LG coal) with low-carbon has been successfully simulated by the homogeneous model as an activation energy of 200.8 kJ/mol. In particular, the fly ash char of KPU coal with high-carbon has been successfully described by the random pore model with the activation energy of 198.3 kJ/mol and was similar to the behavior for the $CO_2$ gasification of the coal char. As a result, the activation energy for the $CO_2$ gasification of two fly ash chars don't show a large difference, but we can confirm that the models for their $CO_2$ gasification depend on the amount of fixed carbon.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.445-455
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• 2023

Sea level rise due to global warming is accelerating. According to the IPCC survey, the expected sea level rise in 2100 was analyzed to be 47cm in the low-carbon scenario (SSP 1-2.6) and 82cm in the high-carbon scenario (SSP 5-8.5). Sea level rise can cause serious damage to port infrastructure and reduce the safety of ships docked inside ports. In this study, Mokpo Port, which frequently suffers from flooding during high tide, was selected and the sensitivity of mooring evaluation factors was analyzed for actual berthing ships according to sea level rise scenarios. From the analysis, we found that the tension of mooring line, the load of bollard, vertical angle of mooring line, and ship's motion of 6-DOF, which are evaluation factors, generally increased when the sea level increased. The most sensitive evaluation factor was sway motion of 6-DOF. Also, we analyzed that the value of mooring evaluation factors decreased when the crown height was raised. This was beneficial in improving ship and pier safety. The results of this study can be used as basic data to secure measures to improve port and ship safety according to sea level rise in Mokpo Port.

• Journal of Climate Change Research
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• v.2 no.2
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• pp.93-106
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• 2011

Republic of Korea officially announced its mid term reduction target which reduce about 30% of BAU GHG emission by 2020 in the 15th meeting of UNFCCC(COP 15) held in Copenhagen, Denmark 2009. To achieve this goal, it is necessary to understand the serious of climate change and take part in GHG reduction not only industry but also the nation. However, such positive participation in green life which may cause inconvenient of the life of the people. It should be accomplished with providing reliable information. This study suggests the scientific potentialities of GHG emission by guideline on low carbon life and green life to form and change a lifestyle suitable for coping with climate change. And also, this study quantitate the GHG reduction which may reduce demand for air conditioning by cool biz and warm biz. In Korea, this campaign has become known as 'CoolMaebsi' by Ministry of Environmental of Korea. 'CoolMaebsi' is a compound word of 'Cool' which means feel refreshed, and 'Maebsi' is a Korean word which means attire. Though this campaign is effective and significant to reduce the GHG emission yet there were no study on quantitative analysis. Therefore this study calculated reduced energy consumption and potential GHG emission by measuring variation of skin temperature. As the result, wearing warm biz and cool biz have an effect of reducing not only the energy consumption but also GHG emission. To achieve the low carbon society, it is necessary to improve the energy saving system and introduce the policy which guide to change a life style.