• Nuclear Engineering and Technology
• /
• 제53권1호
• /
• pp.164-171
• /
• 2021

The europium sorption on Tamusu clay was investigated by batch sorption experiments and spectroscopic study under the condition of strong ionic strength. The results demonstrated that europium sorption on Tamusu clay increased rapidly with pH value, but decreased with the ionic strength of solution increased. The europium sorption also increased in the presence of humic acid, especially at low pH value. The sorption could be fitted by Freundlich isotherm model and the europium sorption on clay was spontaneous and endothermic reaction. Besides, the result indicates that ion exchange was the main process at low pH value, while inner-sphere surface complexation dominated the sorption process at high pH value. The Backscatter electron scanning/Energy Dispersive Spectrometer(BSE/EDS) and the effect of Na for europium sorption results further suggested that europium sorption on Tamusu clay mainly competed with Na at low pH value. Overall, the results in this research were of significance to understand the sorption behavior of europium on the geological media under high ionic strength.

• 대한설비공학회지:설비저널
• /
• 제17권5호
• /
• pp.598-606
• /
• 1988

The radiation heat-transfer coefficient is generally used to calculate radiant heat exchange of heating space. The coefficient is evenly adopted in most cases, but it is not correct in actual cases. The purpose of this paper is to grasp the changing aspect of radiation heat-transfer coefficient needed for heating load calculation of radiant heating space. Surface temperatures are measured in an Ondol space, and the coefficients are derived and examined. Gebhart's Absorption Factor Method is used for the calculations of the rates of instantaneous radiant exchange in the room. As the result, it is confirmed that the coefficients are variant according to surface temperatures, and proper coefficients are needed for each of conditions.

• 폴리머
• /
• 제36권6호
• /
• pp.816-821
• /
• 2012

본 연구에서는 스티렌(styrene)과 TMSPM(3-(trimethoxysilyl)propyl methacrylate) 단량체를 방사선을 이용하여 ETFE(poly(ethylene-co-tetrafluoroethylene)) 필름에 순차적으로 그래프트시킨 후 졸-젤 반응 및 설폰화 반응을 진행하여 실란 가교구조의 수소이온교환막을 제조하였다. 그래프트시 수소이온 전도성을 부여하게 될 스티렌과 가교구조를 형성시킬 TMSPM의 그래프트 순서가 다른 두 종류의 필름을 제조하여 FTIR을 통하여 구조 변화를 비교하였으며, TGA를 이용하여 열적 특성 변화를 관찰하였다. 두 종류의 필름에 설폰산 작용기를 도입한 후 SEM-EDX 기기를 이용하여 막 내부 설폰산 및 실리콘의 분포를 확인하였다.

• 한국태양에너지학회 논문집
• /
• 제29권6호
• /
• pp.45-55
• /
• 2009

Deterioration of the outdoor thermal environment in urban areas has become worse and worse due to the urbanization and overpopulation, etc. Most of existing researches about thermal environment are focused on the indoor environment in which the radiation heat exchange is relatively constant. However, the outdoor thermal environment is changed with time passages, because the thermal environment is highly effected by solar radiation. Thus, to simulate the outdoor thermal environment with accuracy, the solar radiation calculation should be considered, and the radiation heat exchange between building surface and ground surface should be calculated. The purpose of this study is to develop the simulator that can be possible to evaluate the outdoor thermal environment and pedestrian thermal comfort. In this paper, a new method which is coupled with convective heat transfer simulation and radiative heat transfer simulation will be proposed. And the coupled simulation method will be described through case study for outdoor thermal environment. From the results of simulation, the coupled simulation proposed in this study can assess the outdoor thermal environment with accuracy.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2008년도 Asian Magnetics Conference
• /
• pp.35.2-35.2
• /
• 2008

• 한국막학회:학술대회논문집
• /
• 한국막학회 2003년도 The 4th Korea-Italy Workshop
• /
• pp.1-4
• /
• 2003

LDPE/polystyrene cation exchange membranes were prepared through a monomer-sorption method and UV radiation polymerization. The reaction behaviors in the preparation were investigated. The membranes prepared were characterized in terms of physical and electrochemical properties. The membranes exhibited reasonable properties for an ion-exchange membrane with weight gain (Wr) of above 0.3, electrical resistance of below 1.0 Ω $\textrm{cm}^2$ and ion-exchange capacity of 1.8 meq/g-dry membrane. DSC studies and FE-SEM image revealed the formation of a homogeneous membrane. Both the current-voltage and the chronopotentiometric curves of the membranes indicated that LDPE/polystyrene membranes can be properly used at a high current density, and the surface homogeneity of cation-exchange sites in the membrane was comparable to that in a commercial membrane.

• Nuclear Engineering and Technology
• /
• 제38권3호
• /
• pp.225-230
• /
• 2006

With the advent of inexpensive computing power over the past two decades, applications of Monte Carlo radiation transport techniques have proliferated dramatically. At Los Alamos, the Monte Carlo codes MCNP5 and MCNPX are used routinely on personal computer platforms for radiation shielding analysis and dosimetry calculations. These codes feature a rich palette of variance reduction (VR) techniques. The motivation of VR is to exchange user efficiency for computational efficiency. It has been said that a few hours of user time often reduces computational time by several orders of magnitude. Unfortunately, user time can stretch into the many hours as most VR techniques require significant user experience and intervention for proper optimization. It is the purpose of this paper to outline VR strategies, tested in practice, optimized for several common radiation shielding tasks, with the hope of reducing user setup time for similar problems. A strategy is defined in this context to mean a collection of MCNP radiation transport physics options and VR techniques that work synergistically to optimize a particular shielding task. Examples are offered in the areas of source definition, skyshine, streaming, and transmission.

• 천문학회지
• /
• 제45권4호
• /
• pp.101-110
• /
• 2012

I present here one approach to general relativistic radiation hydrodynamics. It is based on covariant tensor conservation equations and considers only the frequency-integrated total energy and momentum exchange between matter and the radiation field. It is also a mixed-frame formalism in the sense that, the interaction between radiation and matter is described with quantities in the comoving frame in which the interaction is often symmetric in angle while the radiation energy and momentum equations are expressed in the fixed frame quantities in which the derivatives are simpler. Hence, this approach is intuitive enough to be applied straightforwardly to any spacetime or coordinate. A few examples are provided along with caveats in this formalism.

• 환경영향평가
• /
• 제21권2호
• /
• pp.239-246
• /
• 2012

Daily net radiation is essential for heat budget analysis for environmental impact assessment in the coastal zone and longwave radiation is an important element of net radiation because there is a significant exchange of radiant energy between the earth's surface and the atmosphere in the form of radiation at longer wavelengths. However, radiation data is not commonly available, and there has been no direct measurement for most areas where coastal environmental impact assessment is usually most needed. Often an empirical equation, e.g., Penman and FAO-24 formulae is used to estimate longwave radiation using temperature, humidity, and sunshine hour data but local calibration may be needed. In this study, local recalibration was performed to have best fit from a widely used longwave equation using the measured longwave radiation data in Korea Global Atmospheric Watch Center (KGAWC). The results shows recalibration can provided better performance AE=0.23($W/m^2$) and RMSE=14.73($W/m^2$). This study will contribute to improve the accuracy of the heat budget analysis in the coastal area.

• 공업화학
• /
• 제17권3호
• /
• pp.303-309
• /
• 2006

본 연구에서는 음이온 및 요소의 투과유속이 강화된 복막투석용 기능성 음이온 교환막의 제조와 특성에 관한 연구를 수행하였다. 음이온 교환막은 UV와 방사선 그라프트 중합법에 의하여 제조되었다. UV 그라프트 중합법에 의해 제조된 분리막의 경우 HEMA와 VBTAC의 비율이 1:2일때 가장 높은 그라프트율을 보였으며 그 이상의 농도에서는 호모폴리머의 생성이 많아지면서 그에 의한 자외선 침투의 제약으로 그라프트율이 감소하였다. 광개시제의 경우에는 0.2 wt%인 경우에 가장 높은 그라프트율을 나타내었으며 그 이상의 농도에서는 다소 감소하는 경향을 나타냈다. 방사선 그라프트 중합법에 의해 제조된 분리막의 경우 VBTAC/HEMA막의 경우 6 h 반응시 96%, GMA막의 경우 반응시간 2 h에 100% 이상의 그라프트율을 나타내었다. 또한, 음이온 교환막을 제조하기 위해 그라프트율 113% 막을 사용하였으며, 음이온 교환기로는 DEA, TEA를 사용하였다. DEA막의 경우 반응시간 4 h에서 70%, TEA막의 경우 2 h 반응에서 30%의 전화율을 나타내었다. 또한, 두 방법에 의하여 제조된 음이온 교환막은 양이온은 배제시키고 음이온과 요소만을 투과하는 특성을 나타내었다.