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미생물 전기화학 기술이 적용된 단일 혐기성소화조에서 전극재질에 따른 바이오가스 생성 효율 평가
신원범(Wonbeom Shin),박준규(Jungyu Park),이범(Beom Lee),김용근(Yonggeun Kim),전항배(Hangbae Jun) 大韓環境工學會 2017 대한환경공학회지 Vol.39 No.2
최근, 미생물전기화학기술(microbial electrochemical technology, MET)을 혐기성 소화에 적용하여 바이오가스 발생량을 증대시키는 연구가 활발하게 이루어지고 있다. 하지만, 내부저항에 따른 Scale-up 측면에서는 아직 활발한 연구가 필요하며, 내부저항을 최소화하기 위한 방안으로는 전류밀도가 높은 전극의 선정, 이온강도 및 전기전도도의 증가, 다양한 전극의 형태 및 재질 선정 등이 보고되고 있다. 최근 Stainless steel은 내구성이 강할 뿐만 아니라 비용 역시 저렴하고, 특히 음극으로 사용되는 경우 백금 금속이나 탄소기반의 섬유재질의 전극과 유사한 효율이 나타남에 따라 그 관심이 높아지고 있다. 따라서, 본 연구에서는 Graphite carbon에 전기전도도 및 전류밀도, 내구성을 향상시킬 수 있는 Ni, Cu, Fe의 코팅 여부와 최근 주목받고 있는 Stainless steel 재질의 판형과 그물망 형태의 전극을 사용하여 전기화학적 특성과 바이오가스 발생량을 비교함으로서 그 효율을 평가하였다. 그 결과, 각 전극 재질에 따른 전류밀도는 GC-CM, GC, SUS-P, SUS-M이 각각 2.03, 1.36, 1.04, 1.13 A/m²으로 나타났으며, 메탄수율은 GC-CM, GC, SUS-P, SUS-M이 각각 0.27, 0.14, 0.19, 0.21 L-CH₄/g-CODrem.로 나타났다. 즉, Stainless 재질의 금속이 코팅된 Graphite carbon과 유사한 전류밀도와 메탄수율을 나타냄을 확인할 수 있었다. MET (Microbial Electrochemical Technology), such as MFC (Microbial Fuel Cell) and MEC (Microbial Electrolysis Cell), is a promising technology for producing sustainable biogas from an anaerobic digester (AD). At current stage, however, the most likely limiting factors, large internal resistances, should be overcome for successful scale up of this technology. Various researchers reported that application of electrode materials containing high current density, increase of ion strength and conductivity, configuration of electrode are good methods for minimizing internal resistances. Recently, stainless steel is receiving great attention because of not only high performance and durability but also low cost. Therefore, in this study, we evaluate electrochemical characteristics and biogas production rate using various electrode materials and configuration (graphite carbon coated with catalysts (GC-CM) or not (GC), stainless steel mesh (SUS-M) and plate (SUS-P)). As the results, current densities of GC-CM, GC, SUS-P, SUS-M were 2.03, 1.36, 1.04, 1.13 A/m², respectively. Methane yields of GC-CM, GC, SUS-P, SUS-M were 0.27, 0.14, 0.19, 0.21 L-CH₄/g-CODrem., respectively. Stainless steel shows high current density and methane yield, which are similar as graphite carbon coated with catalysts.
백색광 LED를 사용한 독서등의 최적 색온도에 따른 사람의 시력 변화 연구
김주현,장원범,이석환,정광교,김동현,김정미,류재준,문성득,이승현,고영수,허산,장미나,정창호,장지호,Kim, Juhyun,Chang, Wonbeom,Lee, Seokhwan,Jung, Kwangkyo,Kim, Donghyun,Kim, Jeongmi,Ryu, Jaejun,Moon, Seongdeuk,Lee, Seunghyun,Ko, Youngsu,Huh, Sa 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.1
White light emitting diode (LED) determined the most appropriate color temperature in reading lighting evaluated fatigue degree of eye according to color temperature. The eye fatigue degrees are determined by brightness and color temperature. Therefore, we measured the results of eyes test according to the change of color temperature and brightness. Experiments except for astigmatic corrected visual acuity of 0.8 more and age 20 to 25 years old, male and female college students was conducted in 100 patients. And constant illumination conditions, visual acuity was measured by varying the color temperature. The optometry at 10 minutes in the darkroom adapted eye. And then the temperature of $25{\pm}3$ degrees, the humidity was carried out at $50{\pm}5%$. As a result of typical color temperature of white light (5,600 K) has identification of the readability.
안영남,김철희,이원범,김정한,Ahn, Young-Nam,Kim, Cheolhee,Lee, Wonbeom,Kim, Jeonhan 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.6
Gas nitriding is a surface hardening process where nitrogen is introduced into the surface of a ferrous alloy. During fusion welding of nitrided carbon steel, the nitride inside weld metal is dissolved and generates nitrogen gas, which causes porosities - blow holes and pits. In this study, several laser welding processes such as weaving welding, two-pass welding, dual beam welding and laser-arc hybrid welding were investigated to elongate the weld pool to enhance nitrogen gas evacuation. The surface pits were successfully eliminated with elongated weld pool. However blowholes inside the weld metal were effective reduced but not fully disappeared.