• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.1274-1277
• /
• 2004

최근 에너지 소비구조의 선진화에 따라 전력수요는 매년 10%이상 증가하고 있지만 철탑부지확보 및 환경 문제 둥에 의해 신규 송전선의 건설은 점차 어려워지고 있다. 이에 대한 대책으로 철탑의 교체 없이 송전선의 전류용량간 증가시키는 방안이 우선적으로 고려되어 적용되고 있다. 이미 국내에서도 기존 송전선인 ACSR 전선을 중용량 저이도의 특성을 가진 STACIR/AW(Super Thermal-resistant Aluminum alloy Conductors, aluminum-clad Invar-Reinforced)송전선으로 교체하여 전력 수송량을 증가시키고 있다. STACIR/AW전선은 도체의 내열성을 향상시켜 연속허용온도$(210^{\circ}C)$를 높임으로 전류용량을 증가시키고, ACSR에 사용되는 강심재료인 고탄소강선을 선팽창계수가 낮은 인바강선(INVAR)으로 대체함으로 고온환경에 따른 이도증가를 방지하고 있다. 그러나 STACIR/AW 송전선은 ACSR 송전선에 비하여 연속허용온도가 높고 경간의 거리가 멀기 때문에 열화에 의한 피로특성의 변화 가능성이 높다. 따라서 본 연구에서는 증용량저이도전선의 강심소재인 INVAR/AW강선을 소정의 온도에서 경년 열화하고, 열화시간에 따른 강도와 피로특성의 변화를 조사하여, STACIR/AW전선의 안정적 운전을 위한 재료물성적 관리인자를 도출하고자 하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.108-108
• /
• 2016

스마트워터그리드(Smart Water Grid; 이하 SWG)란 현재 직면에 있는 물 부족, 물 안보, 물 복지 등 물에 대한 문제를 ICT 기술을 활용하여 물관리의 새로운 패러다임을 제시할 수 있는 융합 기술이다. 즉, SWG는 기존의 수자원 관리 시스템의 한계를 극복하기 위해 첨단 정보통신기술을 이용하는 고효율의 차세대 인프라 시스템으로 다양한 수원을 활용하고 물을 효율적으로 배분 관리 운송하여 수자원의 불균형을 해소하고, 첨단센서네트워크를 이용해 용수관리 전분야에 걸쳐 양방향 실시간으로 용수정보를 감시 대응하여 용수관리와 에너지 효율의 최적화된 메가시티(mega-city)에 적합한 지능형 물관리가 가능할 것으로 예상되는 시스템이다. 따라서 국토교통부 과제로 추진중인 SWG 연구단에서 개발한 스마트 워터 기술을 영종도 112 블록에 적용하여 지역주민의 물복지 향상 및 물 사용자에 대한 소비자 만족도를 높이는데 목적을 두고 데모플랜트를 구축 방안을 수립하였다. 영종도 112블록(인천 운서동 및 운북동 일원)은 인천 공촌정수장에서 해저관로를 지나 영종통합 가압장에서 가압 후 공항신도시배수지에서 물을 공급받고 있는 지역으로 면적은 $17.41km^2$, 인구는 약 17,000명, 물사용량 $8,000m^3$/일, 총관로연장 약 55km, 유수율이 겨우 73.2% 지역이다. SWG 적용성 평가를 위해 영종도 112 블록에 유수율 제고 및 운영비용 저감을 목적으로 데모플랜트를 구축하였다. 스마트 계측을 위해 스마트미터 469개(15~20mm), 디지털미터 172개(25~200mm), 누수유무센서 1개소, 다항목 수질측정기 1개소, 유량계 3개소, 수압계 5개소, AMI 시스템 641개 및 물효율 운영프로그램과 물정보 App서비스 기능으로 구성하였다. 물효율 운영프로그램은 실시간 수요량 예측, 배수지 운영에 따른 취수량, 송수량, 펌프 대수조합 및 운전스케줄링이 가능한 경제적 물공급 스케줄링, 관망상태 감시 및 제어(실시간 유량/수압 분석을 통한 누수분석) 기능이 탑재되어 통합운영센터에서 운영할 계획이다. 데모플랜트 운영을 통해 수자원의 효율적인 배분 및 공급, 유지관리 향상, 운영 비용 최소화 등의 결과를 바탕으로 신도시 및 기존도시의 물관리 정책수립에 활용할 수 있을 뿐만아니라 시간적 공간적 불균형 해소 및 물시장 발전에 크게 기여할 것으로 사료된다.

• Korean Chemical Engineering Research
• /
• v.57 no.6
• /
• pp.853-860
• /
• 2019

In order to meet more severe environmental regulations, oxy-fuel circulating fluidized bed(CFB) boilers or ultra supercritical CFB boilers, which are a kind of process in that solid particles moves similar to fluid, have been developed in the world. In CFB power generation processes, the method to reduce or remove sulfur dioxide is in-situ desulfurization reaction via limestone directly injected into CFB boilers. However, the desulfurization efficiencies have continuously changed because limestones injected into CFB boilers are affected by various operation conditions (Bed temperature, pressure, solid circulating rate, solid holdup, residence time, and so on). In this study, a prediction method with physical and chemical properties of limestone and operation conditions of CFB boiler for in-situ desulfurization reaction in CFB boilers has developed by integrating desulfurization kinetic equations and hydrodynamics equations for CFB previously published. In particular, the prediction equation for in-situ desulfurization was modified by using experimental results from desulfurization reactions of various domestic limestones.

• Resources Recycling
• /
• v.30 no.6
• /
• pp.12-18
• /
• 2021

The water-gas shift reaction is the subsequent step using steam for hydrogen enrichment and H₂/CO ratio-controlled syngas from gasification. In this study, a water-gas shift reaction was performed using syngas from an RPF gasification system. The water-gas shift using a catalyst was performed in a laboratory-scale tube reactor with a high temperature shift (HTS) and a low temperature shift (LTS). The effects of the reaction temperature, steam/carbon ratio, and flow rate on H₂ production and CO conversion were investigated. The operating temperature was 250-400℃ for the HTS system and 190-220℃ for the LTS system. Steam/carbon ratios were between 1.5 and 3.5, and the composition of reactant was CO : 40 vol%, H₂ : 25 vol%, and CO₂ : 25 vol%. The CO conversion and H₂ production increased as the reaction temperature and steam/carbon ratio increased. The CO conversion and H₂ production decreased as the flow rate increased due to reduced retention time in the catalyst bed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.5
• /
• pp.554-560
• /
• 2021

CRUD (chalk river unidentified deposits) is a porous material deposited on the surface of nuclear fuel during nuclear power plant operation. The CRUD is composed of metal oxides, such as iron, nickel, and chromium. It is essential to investigate the effects of the CRUD layer on the wall heat transfer between the nuclear fuel surface and the coolant in the event of a nuclear accident. CRUD only negatively affects the temperature of the nuclear fuel due to heat resistance because the effects of the CRUD layer on two-phase boiling heat transfer are not considered. In this study, the physical property models for the porous CRUD layer were developed and implemented into the SPACE code. The effects of boiling heat transfer models on the peak cladding temperature and quenching were investigated by simulating a reflood experiment. The calculation results showed some positive effects of the CRUD layer.

• Korean Chemical Engineering Research
• /
• v.57 no.4
• /
• pp.531-538
• /
• 2019

As the performance of PEMFC has been improved, the water and heat generated by reaction have increased so, the water and heat management of PEMFC is becoming more important. In this study, hydrogen recirculation was applied as the water management technique and the effect of recirculation flow rate, purge interval and duration on the performance of PEMFC was investigated. Anode pressure, fuel humidity and utilization, water discharge amount was measured to check the effect of purge conditions on performance. As the recirculation flow rate has increased, the performance of PEMFC became lower due to decrease of anode outlet pressure. According to the purge conditions, instantaneous voltage drop has occurred because of accumulated water. In frequent purge conditions, the performance of PEMFC gradually decreased due to fuel humidity control failure. Stable performance and high fuel utilization was achieved on this work by analyzing the effect of purge conditions.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.27 no.2
• /
• pp.51-56
• /
• 2019

$H_2S$ is a detrimental impurity that must be removed for upgrading biogas to biomethane. This study investigates an economic method to mitigate $H_2S$ content, combining scrubbing and aeration. The desulfurization experiments were performed in a laboratory apparatus using EDTA-Fe or landfill leachate as the catalyst and metered mixture of 50-52% (v/v) $CH_4$, 32-33% (v/v) $CO_2$ and 500-1,000 ppmv $H_2S$ balanced by $N_2$ using the C city landfill gas. Dissolved iron concentration in the liquid medium significantly affected the oxidation efficiency of sulfide. Iron components in landfill leachate, which would be available in a biogas/landfill gas utilization facility, was compatible with an external iron chelate. More than 70% of $H_2S$ was removed in a contact time of 9 seconds at iron levels at or over 28 mM. The scrubbing-aeration process would be a feasible and easy-to-operate technology for biogas purification.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.6
• /
• pp.181-186
• /
• 2018

With progress in industrialization, facilities for generating, delivering, and receiving high levels of electric power are in great demand. The scale of electric power equipment is increasing in both size and complexity. This has contributed to the development of our modern, high-tech and information-based society. However, if the generation of electric power is suspended due to unexpected accidents at power facilities or power stations, a range of equipment the operations of which are dependent on electric power can be damaged, causing substantial socioeconomic losses in an industrial society. A great deal of time and money would be expended to repair damaged facilities at a power station, causing enormous economic loss. In order to detect the deterioration processes of power cables, and to prevent the destruction of power cables, the operation status of power cables should be monitored on a regular basis. We studied the method in order to improve accuracy and reliability for diagnosising the junction where accident occurs frequently. We present the method of data acquisition and statistical processing.

• Korean Journal of Remote Sensing
• /
• v.34 no.6_1
• /
• pp.1131-1142
• /
• 2018

The autonomous vehicles are being developed and operated widely because of the advantages of reducing the traffic accident and saving time and cost for driving. The vehicle localization is an essential component for autonomous vehicle operation. In this paper, localization algorithm based on sensor fusion is developed for cost-effective localization using in-vehicle sensors, GNSS, an image sensor and reference images that made in advance. Information of the reference images can overcome the limitation of the low positioning accuracy that occurs when only the sensor information is used. And it also can acquire estimated result of stable position even if the car is located in the satellite signal blockage area. The particle filter is used for sensor fusion that can reflect various probability density distributions of individual sensors. For evaluating the performance of the algorithm, a data acquisition system was built and the driving data and the reference image data were acquired. Finally, we can verify that the vehicle positioning can be performed with an accuracy of about 0.7 m when the route image and the reference image information are integrated with the route path having a relatively large error by the satellite sensor.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.8
• /
• pp.923-929
• /
• 2019

The stability of the propulsion system is crucial for the autonomous vessel. Multiple power generation and propulsion systems should be provided for the stability of the propulsion system. High power generation capacity is calculated for stability, resulting in economical decline due to low load operation. To solve this problem, we need to optimize the power system. In this paper, an OPMS for electric propulsion ship is constructed. The OPMS consists of a hybrid power generation system, an energy storage system, and a control load system. The power generation system consists of a dual fuel engine, the energy storage system is a battery, and the control load system consists of the propulsion load, continuous load, intermittent load, cargo part load and deck machine load. The power system was constructed by modeling the characteristics of each system. For the experiment, a scenario based on ship operation was prepared and the stability and economical efficiency were compared with existing electric propulsion ships.