• KIEAE Journal
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• 제11권5호
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• pp.91-96
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• 2011

This study is to analysis the characteristics of electric power consumption of apartments complex in Korea. This study shows the pattern of electric power consumption and correlation of each apartment complex's completion year monthly and timely. With this result, we are able to predict the demand pattern of electricity in a house and make the schedule by demand pattern. It is expected this data is used as reference of electric consumption of Daejeon area to operate the simulation tools to predict the building energy. The yearly data of 10 apartment complexes of 2010 are analyzed. The results of this study are followed. The averaged amount of electricity consumption in winter is higher as summer because of the high capacity of heating equipment. All of the house has electric base load from 0.26kWh to 0.5kWh. The average of the electricity consumption of month is shown as 310.2kWh. A week is seperated, as 4 part such as week, weekend, Saturday and Sunday. During week, the average of timely electricity consumption is shown as 0.426kWh. The Saturday consumption is 0.437kWh. The Sunday is 0.445kWh. The peak electricity consumption in summer and winter is measured. The peak consumption on summer season is 1.389kW on 22th August 64% higher than winter season 0.887kW on 3rd January.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.129.2-129.2
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• 2010

As a part of the government renewable energy policy, KOWEPO is constructing 300MW IGCC plant in Taean. IGCC plant consists of gasification block, air separation unit and power block, which performance test is separately conducted. Overall performance test for IGCC plant is peformed to comply with ASME PTC 46. Major factors affected on the overall efficiency for IGCC plant are external conditions, each block performance(gasification, ASU, power block), water/steam integration and air integration. Performance parameters of IGCC plant are cold gas efficiency, oxygen consumption, sensible heat recovery of syngas cooler for gasification block and purity of oxygen, flow amount of oxygen and nitrogen, power consumption for air separation unit and steam/water integration among the each block. The gas turbine capacity applied to the IGCC plant is 20 percent higher than NGCC gas turbine due to the low caloric heating value of syngas, therefor it is possible to utilize air integration between gas turbine and air separation unit to improve overall efficiency of the IGCC plant and there is a little impact on the ambient condition. It is very important to optimize the air integration design with consideration to the optimized integration ratio and the reliable operation. Optimized steam/water integration between power block and gasification block can improve overall efficiency of IGCC plant where the optimized heat recovery from gasification block should be considered. Finally, It is possibile to achieve the target efficiency above 42 percent(HHV, Net) for 300MW Taean IGCC plant by optimized design and integration.

• 한국구조물진단유지관리공학회 논문집
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• 제20권6호
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• pp.91-97
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• 2016

초고강도 콘크리트를 이용한 부재의 내화 성능을 검토하기 위해서는 실제부재 단위의 시험에 의한 평가가 요구되고 있다. 그러나 실제부재 실험을 하기 위해서는 재하 능력이 큰 시험 장비가 필요하기 때문에, 재료 모델을 이용한 해석적 연구를 통해 내화 성능을 평가하고 있다. 본 연구에서는 80, 130 및 180 MPa의 초고강도 콘크리트를 대상으로 고온 가열시의 변형 특성을 실험적으로 평가하고 초고강도 콘크리트에 대한 기존 변형 모델의 적용을 검토했다. 그 후, 최소 제곱법에 의해 실험 값과 기존의 변형 모델을 적용한 계산 값의 누적 오차가 가장 작은 상수 값을 도출하고 초고강도 콘크리트에 적용 할 수 있는 변형 모델을 제시했다.

• Carbon letters
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• 제26권
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• pp.31-42
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• 2018

Adsorption is one of the best methods for wastewater purification. The fact that water quality is continuously decreasing requires the development of novel, effective and cost available adsorbents. Herein, a simple procedure for the preparation of a magnetic adsorbent from agricultural waste biomass and ferrofluid has been introduced. Specifically, ferrofluid mixed with wheat straw was directly pyrolyzed either by microwave irradiation (900 W, 30 min) or by conventional heating ($550^{\circ}C$, 90 min). Magnetic biochars were characterized by X-ray powder diffraction, $M{\ddot{o}}ssbauer$ spectroscopy, textural analysis and tested as adsorbents of As(V) oxyanion and cationic methylene blue, respectively. Results showed that microwave pyrolysis produced char with high adsorption capacity of As(V) ($Q_m=25.6mg\;g^{-1}$ at pH 4), whereas conventional pyrolysis was not so effective. In comparison to conventional pyrolysis, one-step microwave pyrolysis produced a material with expressive microporosity, having a nine times higher value of specific surface area as well as total pore volume. We assumed that sorption properties are also caused by several iron-bearing composites identified by $M{\ddot{o}}ssbauer$ spectroscopy ([super] paramagnetic $Fe_2O_3$, ${\alpha}-Fe$, non-stoichiometric $Fe_3C$, ${\gamma}-Fe_2O_3$, ${\gamma}-Fe$) transformed from nano-maghemite presented in the ferrofluid. Methylene blue was also more easily removed by magnetic biochar prepared by microwaves ($Q_m=144.9mg\;g^{-1}$ at pH 10.9) compared to using conventional techniques.

• 한국세라믹학회지
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• 제43권2호
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• pp.121-125
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• 2006

[ $LiFePO_4$ ] is one of the promising materials for cathode material of secondary lithium batteries due to its high energy density, low cost, environmental friendliness and safety. $LiFePO_4$ was synthesized by the solid-state reaction method at 500 - 800°C. The crystal structure of $LiFePO_4$ was analyzed by X-ray powder diffraction. The samples synthesized at 600 and $700^{\circ}C$ showed a single phase of a olivine structure. The particle sizes were increased and the specific surface areas were decreased with heating temperatures. The electrochemical performance was investigated by coin cell test. The discharge capacities at 0.1 C-rate were 118 mAh/g and 112 mAh/g at $600^{\circ}C,\;700^{\circ}C$, respectively. In an attempt to improve the electrical conductivity of cathode materials, $LiFePO_4/graphite$ composite was prepared with various graphite contents. The electrical conductivity and discharge capacity were increased with increasing the graphite contents in composite samples. The rate capabilities at high current densities were also improved.

• 한국건설순환자원학회논문집
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• 제7권4호
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• pp.104-112
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• 2012

플라이애시의 주요 성분은 $SiO_2$, $Al_2O_3$, $Fe_2O_3$로서 이들 세 성분이 전체의 80~90%를 차지한다. 최근 알칼리 자극제를 활용하여 플라이애시를 활성화하여 제조한 결합재에 대한 연구가 활발하게 진행되고 있다. 알칼리 활성화 반응에 의한 결합재는 시멘트 수화생성물인 C-S-H와 수산화칼슘을 형성하지 않으므로 $500^{\circ}C$이상에서도 현저한 강도저하 현상이 발생하지 않기 때문에 효율적인 내화성 마감재를 제조할 수 있다. 본 연구는 플라이애시를 활용하여 알칼리 활성화 결합재를 제조하고 고온에서의 내부구조 분석을 통하여 고온에서 안정한 재료임을 확인하고 내화성 마감재로의 적용에 대한 효용성을 확인할 수 있었다.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.115-123
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• 2010

Cool-down performance after soaking is important because it affects passenger's thermal comfort. The cooling capacity of HVAC system determines initial cool down performance in most cases, the performance is also affected by location, and shape of panel vent, indoor seat arrangement. Therefore, optimal indoor designs are required in developing a new car. In this paper, initial cool down performance is predicted by CFD(computational fluid dynamics) analysis. Experimental time-averaging temperature data are used as inlet boundary condition. For more reliable analysis, real vehicle model and human FE model are used in grid generation procedure. Thermal and aerodynamic characteristics on re-circulation cool vent mode are investigated using CFX 12.0. Thermal comfort represented by PMV(predicted mean vote) is evaluated using acquired numerical data. Temperature and velocity fields show that flow in passenger's compartment after soaking is considerably unstable at the view point of thermodynamics. Volume-averaged temperature is decreased exponentially during overall cool down process. However, temperature monitored at different 16 spots in CFX-Solver shows local variation in head, chest, knee, foot. The cooling speed at the head and chest nearby panel vent are relatively faster than at the knee and foot. Horizontal temperature contour shows asymmetric distribution because of the location of exhaust vent. By evaluating the passenger's thermal comfort, slowest cooling region is found at the driver's seat.

• 한국진공학회지
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• 제14권1호
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• pp.1-6
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• 2005

비증발형 게터용 금속이나 합금의 표면은 대기중에서 얇은 산화층등으로 덮여있다. 이들이 제품 내에서 게터역할을 하기 위해서는 진공이나 불활성 분위 내에서 가열하여 표면 산화층을 제거하는 활성화공정이 필요하며 활성화온도는 장착 제품을 결정하는 중요한 인자가 된다. 게터의 기본적인 특성은 활성화 및 각종가스에 대한 흡수능으로 대별할 수 있다. 이중 게터의 흡수능에 대해서는 ASTM등에서 규정하고 있으나 활성화온도에 대해서는 아직 표준적인 방법이 제시되어 있지 못하다. 본 연구에서는 온도에 따른 도달압력 측정에 의해 게터의 활성화온도를 결정하는 비교적 간단한 방법을 제시하였다. 본 방법으로 측정한 TiZrV 합금의 활성화온도가 100℃～200℃ 범위에 있다.

• 한국철도학회논문집
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• 제13권2호
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• pp.194-200
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• 2010

최근 지하철 시공 확대와 국토의 지형적인 특수성, 시공기술의 발달 등으로 인하여 장대터널이 증가하고 있는 실정이다. 터널 및 지하구조물에서 발생되는 화재는 지하공간이라는 폐쇄된 공간특성으로 인해 지상화재에 비해 많은 인명과 경제적 피해를 발생시킨다. 국내의 경우 터널 및 지하구조물에 대한 내화 연구가 진행 중이나 고온 시 콘크리트의 폭열 발생으로 인한 내하력 저하 및 안전성 평가에 대한 연구가 부족한 실정이다. 따라서 본 연구에서는 시간가열 온도곡선(RABT 및 RWS)에 따른 콘크리트 내화 특성을 평가하고 실제 발생한 화재사례와 비교 검토하여 적용성을 제시하였다. 또한 유한요소 기반의 수치모델을 적용한 열-역학 연동해석을 실시하여 화재로 인한 지하구조물의 단면 손실 및 손상정도를 예측 평가하였다.

• 한국조경학회지
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• 제34권6호
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• pp.39-53
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• 2007

Unlike conventional roof landscaping, where various kinds of plants and structures are employed, a grass roof is a roof on which herbaceous plants are grown in planting medium and which is not accessed or maintained, mainly because it doesn't have sufficient load capacity to support a regular roof garden. They are mostly built on existing roofs, whether flat slab or gabled. Planting on roofs has numerous advantages, such as creating a biotope, purifying urban air, adding moisture to the atmosphere, storing rain water, preventing flash floods, reducing energy use for heating and air conditioning, enhancing the urban landscape and providing relaxation to the city dwellers, not to mention the alleviation of global warming by absorbing $CO_2$. In addition to the general merits of roof planting, the grass roof has its own unique qualities. Only herbaceous species are planted on the roof, resulting in light weight which allows roofs of existing buildings to be planted without structural reinforcement. The species chosen are mostly short, tough perennials that don't need to be maintained. These conditions provide an ideal situation where massive planting can be done in urban areas where roofs are often the only and definitely the largest space available to be planted. If roofs are planted on a massive scale they can play a significant role in alleviating global warming, heat island effects and energy shortages. Despite the advantages of grass roofs, there are some problems. The most significant problem is the invasion of neighboring plants. They may be brought in with the planting medium, by birds or by wind. These plants have little aesthetic value comparing to the chosen species and are usually taller. Eventually they dominate and prevail over the original species. The intended planting design disappears and the roof comes to look wild. Since the primary value of a grass roof is ecological, a change in attitude towards what constitutes beauty on the roofscape is necessary. Instead of keeping the roof neat through constant maintenance, people must learn that the wild grass with bird's nests on their roof is more beautiful as it is.