• Membrane and Water Treatment
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• 제8권2호
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• pp.125-136
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• 2017

Reverse osmosis technology is being used on large scale for treatment of ground water, brackish water, wastewater and sea water. The most challenging issue in RO process is carbonate scaling which is directly linked with the efficiency and economy. Considering the natural phenomena of carbonate scaling different adaptations have been made to control scaling on the surface of RO membrane including acid dosage and antiscalant addition. As carbonate scaling is directly related with pH level of feed water, present study describes an experimental approach to reduce scaling on RO membrane by lowering the feed water pH by purging $CO_2$. In this comparative study four different conditions including control process (without any scale inhibitor), with dosage of antiscalant, with purging of $CO_2$ and with co addition of antiscalant and $CO_2$ in a feed stream line; it was established that $CO_2$ is a better appliance to reduce carbonate scaling on the membrane surface by reduce pH of feed stream. It was also observed that $CO_2$ and antiscalant mutually function better for scale control.

• 에너지공학
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• 제27권1호
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• pp.21-32
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• 2018

In this paper, we reported the current technologies of water scaling removal and also water recovery from the flue gases, which are funded by Department of Energy (DOE), USA. Globally, water resources are limited due to the climate change. The potential impacts of climate change is food and water shortages. In the $21^{st}$ century, water shortages and pollution are expected to become more acute as populations grow and concentrate in cities. At present, the water stress increases over 62.0 ~ 75.8% of total water basin area and decreases over 19.7 ~ 29.0%. Many renewable energy sources demand secure water resources. Water is critical for successful climate change mitigation, as many efforts to reduce greenhouse gas emissions depend on reliable access to water resources. Water hardness is one of the major challenge to coal power plants. Department of energy (DOE) funded and encouraged for the development of advanced technologies for the removal of hardness of water (scaling) and also water recovery from the flue gases from coal power plants.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.255-259
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• 2002

To reduce the uncertainty in the calibration of radiation beams, absorbed dose to water for high energy electrons is recommended as the standards and reference absorbed dose by AAPM Report no.51 and IAEA Technical Reports no.398. In these recommendations, water is, defined as the reference medium, however, the water substitute solid phantoms are discouraged. Nevertheless, when accurate chamber positioning in water is not possible, or when no waterproof chamber is available, their use is permitted at beam qualities R$\_$50/ < 4 g/cm$^2$ (E$\_$0/ < 10 MeV). For the electron dosimetry using solid phantom, a depth-scaling factor is used for the conversion of depth in solid phantoms to depth in water, and a fluence-scaling factor is used for the conversion of ionization chamber reading in plastic phantom to reading in water. In this work, the properties, especially depth-scaling factors c$\_$p1/ and fluence-scaling factors h$\_$pl/ of several commercially available water substitute solid phantoms were determined, and the electron dosimetry using these scaling method was evaluated. As a result, it is obviously that dose-distribution in solid phantom can be converted to appropriate dose-distribution in water by means of IAEA depth-scaling.

• Journal of the Korean Data and Information Science Society
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• 제16권2호
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• pp.349-357
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• 2005

Principal component analysis(PCA) was carried out to evaluate the water quality with the monitering data collected from 1997 to 2003 along the coastal area of Ulsan, Korea. To enhance evaluation and to complement descriptive power of traditional PCA, optimal scaling was applied to transform the original data into optimally scaled data. Cluster analysis was also applied to classify the monitering stations according to their characteristics of water quality.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.1052-1065
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• 2024

Advanced Pressurized Water Reactors (APWRs) and Boiling Water Reactors (BWRs) employ a suppression pool as a heat sink to prevent containment overpressure. Steam can be discharged into the pool through multi-hole spargers or blowdown pipes in both normal and accident conditions. Direct Contact Condensation (DCC) creates sources of momentum and heat. The competition between these two sources determines the development of thermal stratification or mixing of the pool. Thermal stratification is of safety concern as it reduces the cooling capability compared to a completely mixed pool condition. In this work we develop a scaling approach to prediction of the thermal stratification in a water pool induced by steam injection through spargers. Experimental data obtained from large-scale pool tests conducted in the PPOOLEX and PANDA facilities, as well as simulation results obtained using validated codes are used to develop the scaling. Two injection orientations, namely radial injection through multi-hole Sparger Head (SH) and vertical injection through Load Reduction Ring (LRR), are considered. We show that the erosion rate of the cold layer can be estimated using the Richardson number. In this work, scaling laws are proposed to estimate both the (i) transient erosion velocity and (ii) the stable position of the thermocline. These scaling laws are then implemented into a 1D model to simulate the thermal behavior of the pool during steam injection through the sparger.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.54-57
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• 2003

Scaling deterioration of port concrete structures due to the combined effects of chemical actions by seawater and the freeze-thaw action is also a problem which has not yet been fundamentally solved. Furthermore, deterioration of concrete surface was considered as accelerate factor of concrete durability tended to decrease. Therefore, we considered the scaling measuring method and decreasing influence of durability of concrete according to kind of binders, such as OPC, Slag, Slag+Fa, due to freeze and haw of sea water. As a results of this study, it was effective method of scaling deterioration of concrete, and confirmed the salt deterioration resistance effect to use slag binder against to sea water.

• 한국통신학회논문지
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• 제31권1C호
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• pp.20-25
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• 2006

본 논문에서는 Tree-LDPC 코드의 성능을 scaling 인자를 이용한 min-sum 알고리즘을 사용하여 나타내고, 그때의 water fall 영역에서의 접근 성능은 density evolution 기법을 사용하여 나타낸다. Density evolution 기법을 통하여 얻어진 최적의 scaling 인자를 사용하게 되면 min-sum 알고리즘을 사용하는 Tree-LDPC 코드는 sum-product 알고리즘을 사용했을 때와 비슷한 성능을 나타낼 정도로 상당한 성능 이득을 갖게 되는 반면 sum-product 알고리즘을 사용했을 때보다 복호 복잡도가 훨씬 줄어들게 된다. 작은 인터리버 크기를 갖는 Tree-LDPC 복호기를 FPGA(Field Programmable Gate Array)로 구현하였다.

• Nuclear Engineering and Technology
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• 제44권6호
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• pp.611-622
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• 2012

"Scaling" plays an important role for safety analyses in the licensing of water cooled nuclear power reactors. Accident analyses, a sub set of safety analyses, is mostly based on nuclear reactor system thermal hydraulics, and therefore based on an adequate experimental data base, and in recent licensing applications, on best estimate computer code calculations. In the field of nuclear reactor technology, only a small set of the needed experiments can be executed at a nuclear power plant; the major part of experiments, either because of economics or because of safety concerns, has to be executed at reduced scale facilities. How to address the scaling issue has been the subject of numerous investigations in the past few decades (a lot of work has been performed in the 80thies and 90thies of the last century), and is still the focus of many scientific studies. The present paper proposes a "roadmap" to scaling. Key elements are the "scaling-pyramid", related "scaling bridges" and a logical path across scaling achievements (which constitute the "scaling puzzle"). The objective is addressing the scaling issue when demonstrating the applicability of the system codes, the "key-to-scaling", in the licensing process of a nuclear power plant. The proposed "road map to scaling" aims at solving the "scaling puzzle", by introducing a unified approach to the problem.

• 한국수자원학회논문집
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• 제56권4호
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• pp.273-284
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• 2023

최근 지속적인 가뭄으로 물 공급에 큰 어려움을 겪고 있으며, 이러한 극한 사상의 발생은 기후변화에 따라 더욱 빈번해질 것으로 전망된다. 본 연구는 기후변화에 따른 댐 운영 가뭄 취약성을 평가하고자, 보다 넓은 범위에서 미래 기후변화의 변동성을 반영할 수 있는 decision scaling 기법을 제안하였다. 충청남도 보령댐을 시범유역으로 선정하고 양적 신뢰도를 이용하여 평가한 결과, 보령댐의 가뭄 취약도는 도수로 반영 여부에 따라 95.80% 에서 98.13%까지 변동하였고, 기후변화에 매우 취약한 것으로 나타났다. 더불어 유전 알고리즘 기반 최적의 헤징룰을 산정하여 가뭄 취약성의 저감 효과를 분석하였고, 다양한 사회·경제적 변화에 대응하기 위해 세 가지 수요 시나리오(고수요, 저수요, 기준수요) 하에서 평가를 진행하였다. 양적 신뢰도와 극한가뭄 발생 빈도를 평가 기준으로 분석한 결과, 두 헤징룰은 K-water의 용수공급 조정기준 대비 저수요 시나리오에서 공급 안정도를 개선시킴으로써 극한가뭄에 적절히 대처할 수 있는 방법으로 사용될 수 있을 것이다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.504-504
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• 2015

수공구조물을 설계하기 위해서는 설계수문량을 빈도해석을 통해 산정할 수 있다. 빈도해석 중 지점빈도해석을 보완한 지역빈도해석을 적용하기 위해서는 군집분석을 통한 지역구분이 무엇보다 중요하다. 또한 스케일 성질(scaling property)은 강우의 시 공간적 특성을 지속기간별 관측된 강우자료를 이용하여 재현기간에 대한 지속기간의 함수로 강우의 IDF곡선을 제시할 수 있는 방법이다. 따라서 스케일 성질을 통해 군집된 지역에서의 강우자료에 적용하여 스케일 인자(scaling exponent)를 추정한 후 수문학적 동질성을 통계적 특성으로 설명하고자 한다. 본 연구를 수행하기에 앞서 군집 분석은 4개의 군집방법(평균연결법, Ward방법, Two-Step방법, K-means방법)을 적용하였고, 한강유역에 위치한 104개의 강우지점은 4개의 지역으로 구분하는 것이 적절하다고 판단되어 비계층적 방법인 k-means방법을 이용하여 지역을 구분하였다. 본 연구에서는 군집된 결과를 바탕으로 4개의 지역으로 구분된 지역에 포함된 강우지점을 대상으로 스케일 인자를 추정하고 수문학적 동질성을 통계적 방법으로 제시하고자 한다.