• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.118-124
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• 2017

An air cooling, open cathode type polymer electrolyte membrane fuel cell (PEMFC) has the advantages of system simplification and cost effectiveness. Open cathode PEMFC could suffer from reduced performance due to the membrane dehydration in low humidity of air. Effects of the cathode air flow rate, anode purge interval and long term storage on PEMFC performance were investigated in this work. Fan voltage is an important factor on air cooling PEMFC performance because the cathode air flow rate and stack temperature were controlled by fan voltage. The dead ended anode (DEA) method was applied to increase hydrogen usage. Periodical purge was used to discharge accumulated water and gas. The influence of long term non-operating condition on PEMFC performance degradation due to the membrane dehydration was also studied and the quick recovery method was developed.

• Membrane Journal
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• v.25 no.2
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• pp.180-190
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• 2015

PVDF (polyvinylidene fluoride) nanofiber has the advantages such as excellent strength, chemical resistance, nontoxic, non-combustibility. Flat membranes with 0.3 and $0.4{\mu}m$ pore size respectively, were manufactured by PVDF nanofiber, and then each spiral wound module was prepared with them. A woven paper was not included in preparing the module with $0.3{\mu}m$ pore size; however, it was included the module with $0.4{\mu}m$ pore size. The permeate fluxes and rejection rates of the two modules were compared using pure water and simulation solution including kaolin and humic acid. The recovery rate and filtration resistance were calculated after water back-washing. In addition, the effect of flow rate and trans-membrane pressure on treatment efficiency and filtration resistance were investigated for the spiral wound module with $0.4{\mu}m$ pore size.

• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.473-483
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• 2018

In this study, we have developed a lab scale bioreactor to identify the characteristics of nitrification reaction according to operation condition (temperature, inhibitor (as Cl), activated nitrifying bacteria (ANB). etc) to improve nitrification efficiency at low temperature. Recovery rate of nitrification took about 4 days to reach the normal level by injected ANB after inhibition shock of CI injection at $20^{\circ}C$, when measured the concentration of $NO_2{^-}-N+NO_3{^-}-N$ in the effluent. In the case of $10^{\circ}C$, recovery of nitrification rate took about 4 days to reach the level of half to the normal level and 7 days for complete recovery which took 3 days more than those at $20^{\circ}C$. At $10^{\circ}C$ considering the winter season, the specific nitrification rate(SNR) of the from 1 day to 6 days after injected ANB according to its operation condition increased from 0.029 to 0.767 mgN/gSS/hr. The simulated SNR for the 8th day after the injected ANB at $10^{\circ}C$ was 0.840, 3.625 mgN/gSS/hr, respectively as linear function and exponential function, expecting to exceed level of 2.592 mgN/gSS/hr at normal condition. It was confirmed that injection of ANB during low temperature operation has many effects for improving nitrification efficiency through this study. In future studies, if further studies are carried out the determination of ANB injection and the design of efficient ANB reactor considering the changes of operating characteristics by site, it will contribute to the improvement of nitrification efficiency in winter season.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.2025-2036
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• 2000

A physicochemical process called ultra rapid coagulation(URC) was applied as a pilot scale to recover eutrophicated lake water at Inkyung Lake located on-campus in Inha university. The URC was uniquely designed to completely remove the presence of phosphorus up to 95%, which in turn leading to lessen the level of eutrophication of lake. For a pilot test of period, the lake was restored showing Carlson's Trophic State Index(TSI) of mesotrophic state which accounts for the reduction of total phosphorus and chlorophyll-a down to approximately 55 from 70 and 73, respectively. A residual presence of aluminum and additional coagulants in the effluent was tested for their potential effects on Photobacterium phosphoreum. The effect concentration ($EC_{50}$-15 min) observed in the effluent revealed that the bioactivity of Photobacterium phosphoreum was not influenced by the residual presence of coagulants. After the pilot test of period, the lake was consequently restored as a mesotrophic state in obtaining the second grade of lake water quality. The URC may be further applied for restoration of greater scale of lake in eutrophication.

• Journal of Energy Engineering
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• v.25 no.3
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• pp.27-33
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• 2016

The heat recovery system that was applied in this study, is the energy-saving type that can produce the maximum cooling capacity less power in use. In order to have a more precise control function the temperature and humidity of the constant temperature and humidity machine, control algorithm is applied to designed a fuzzy PID controller, and the outside air compensation device (air-cooled) demonstrated excellent ability to dehumidify the moisture, $-20^{\circ}C$ in winter. High efficiency and the low-noise type sirocco fan operate quitely and designed to fit the bottom-up and top-down in accordance with the characteristics of equipment. as a result of experiment data, the conversion efficiency is 95% or more, power recovery time is within 5sec, stop delay time is within 30sec, pump down time is 10sec, pump delay time is 5sec, heating delay time is 5sec, temperature deviation is ${\pm}2^{\circ}C$ (cooling deviation: $2^{\circ}C$, Heating deviation : $2^{\circ}C$), humidity deviation is a ${\pm}5%$ (humidification deviation 3.0%, dehumidification deviation 3.0%). Recently, ubiquitous technology is important. so, the constant temperature and humidity machine designed to be able to remotely control to via the mobile phone, and more scalable to support MMI software and automatic interface. Further, the life of the parts and equipment is extended by the failure.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.15-20
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• 2011

The contamination effect of toluene in the airstream on PEM fuel cell performance was studied with various toluene concentration under different operation conditions. And the recovery of the cell performance by applying clean air and the removal of toluene in the air by adsorption of active carbon were investigated. The toluene concentration range used in the experiments was from 0.1 ppm to 5.0 ppm. The performance degradation and recovery were measured by constant-current discharging and electrochemical impedance spectroscopy(EIS). Toluene adsorption capacity of KOH impregnated active carbon was obtained from the adsorption isotherm curve. The severity of the contamination increased with increasing toluene concentration, current density and air stoichiometry, but decrease with increasing relative humidity. The cell performance was recovered by toluene oxidation with oxygen and water in humidified neat air. EIS showed that the increase of charge transfer resistance due to toluene adsorption on Pt surface mainly reduced the performance of PEMFC. Toluene adsorption capacity of active carbon decreased as KOH weight increased in KOH impregnated active carbon.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.150-150
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• 2012

본 연구에서 개발된 Enhanced huels형 플라즈마 발생장치는 초음속 공기 플라즈마 환경에 대한 열 보호 물질의 개발과 시험평가를 위한 지상 시뮬레이션 시험을 목적으로 개발되었다. Enhanced Huel형 플라즈마 토치는 고출력에도 불구하고 전극 부식에 의한 오염도를 최소화할 수 있고, 일반적인 직류 토치로는 얻을 수 없는 초고엔탈피 플라즈마 열유동을 얻을 수 있는 특징이 있다. 구축된 장치는 최대 직류 전력 1,200 kW까지의 출력 제공이 가능한 DC 전원과 플라즈마 토치, 플라즈마의 진단계측 및 재료 시험 수행이 가능한 진공쳄버, 플라즈마를 기체로 회복시켜주기 위한 디퓨저, 디퓨저를 빠져나오는 초고온 열 유동으로부터 열을 제거하기 위한 열교환기, 쳄버 전체의 압력을 제어하기 위한 진공 장치, 후처리 시스템, 가스 공급부 시스템, 냉각수 공급 시스템으로 구성되어 있다. 또한 플라즈마 진단계측장비로는 enthalphy 측정시스템과 각 종 열유속 측정 탐침기, pyrometers, 분광계, 적외선 카메라, 고속 카메라를 갖추고 있다. 시운전 결과 토치 공급전력 412 kW, 공기공급 12.31 g/s , 토치 내부압력 4.14 bar의 운전조건에서 62%의 효율로 플라즈마 엔탈피 16.7 MJ/kg의 성능을 얻었다.

• Journal of Convergence for Information Technology
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• v.8 no.1
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• pp.147-152
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• 2018

A polarizing spectacle lens having a perfect blocking of ultraviolet light and a partial blocking of blue light and having photochromic properties has been developed. It is a functional spectacle lens which can be used as a spectacle lens in the daytime, which plays a role of sunglass in a space with strong ultraviolet rays, dramatically reducing glare caused by late-night driving or reflected light. Photochromism was recovered in 0.5 second dark reaction and 3 seconds recovery time. The polarization function was about 95%. Ultraviolet rays were completely blocked and blue light was reduced by about 30%. A lens that combines photochromic and UV blocking and polarization functions is the first attempt at investigating the domestic market.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.713-714
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• 2006

$SF_6$ 가스절연 Recloser는 선로에 일시적인 과전류가 발생하면 개방 후 자동 재투입 하면서 선로의 정상적인 운전상태를 회복하고, 영구 고장 시에는 정해진 Sequence에 따라 개방, 투입을 반복한 후 개방완료 상태에 이르게 하는 보호기기이며, 조작부는 주로 Solenoid Actuator 방식을 채택해왔었다. 그러나 Solenoid Actuator 방식은 구조가 복잡하고 부품수가 많은 단점이 있어 최근에는 사용 부품수를 획기적으로 감소 시키고 조작 신뢰성을 증대시킨 Magnetic Actuator 방식을 채택하여 사용하는 경향을 보이고 있다. 이 Magnetic Actuator 방식은 구조가 간단하고 부품수가 적어 높은 신뢰성을 확보할 수 있고 유지 보수가 거의 필요하지 않는 장점을 가지고 있다. 이에 본 논문에서는 $SF_6$ 가스절연 Recloser의 조작부에 Magnetic Actuator 방식(이하 PMA (Permanent Magnetic Actuator))을 채용 하였으며, 이를 적용하기위한 입력전원 및 투입, 개방 코일을 패러미터로 하여 PMA의 동적특성을 실험하였으며, 이 실험 자료에 근거하여 27[kV] $SF_6$ 가스절연 Recloser의 PMA 조작부를 설계 및 제작하였다.

• Membrane Journal
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• v.14 no.1
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• pp.66-74
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• 2004

Total resistance of membrane in a micro-filtration system using a metal membrane was mainly attributed to the permeate resistance of cake layer($R_c$), which was formed by deposited particles from the physico-chemical interactions of solids on membrane surface. Intermittent back ozonation was highly effective than the air backwashing for fouling reduction. As far the operational effect, under same ozone injection, the increase of gas flow-rate was more favorable than the increase of injection time far the recovery of permeation flux. As the filtration time was longer, the effect of flux recovery by intermittent back-ozonation decreased. Therefore, it is preferable to operate membrane cleaning before the foulant is consolidated on membrane surface.