• Nuclear Engineering and Technology
• /
• 제45권6호
• /
• pp.731-744
• /
• 2013

Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energy supplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given the desire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technology options available for baseload electricity generation. Further complicating this issue is the desire for energy sources to be sustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its current form meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed the Traveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalable for the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared to conventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowest cost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation concerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generation infrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need to be built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costs and 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. With advanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuel from LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areas covered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selected information on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safety performance.

• 한국식품과학회지
• /
• 제52권4호
• /
• pp.409-414
• /
• 2020

시중에 분쇄된 상태로 판매되는 CFBF와 faba bean 원물을 직접 분쇄하여 제조한 FBF, 그리고 분쇄한 faba bean 가루에서 알칼리 추출법으로 추출한 FBS의 물리화학적 특성을 확인하였다. FBS의 녹말 입자는 타원형에 표면에 갈라짐이 있으며 CFBF와 FBF는 일정하지 않은 크기의 입자를 보였다. FBS는 상대적으로 낮은 용해도와 겉보기 점도를 보여주었다. CFBF와 FBF는 호화 특성을 나타내지 못한 반면 FBS는 비교적 낮은 trough와 높은 setback값의 호화 특성을 보여주어 차이를 나타냈다. FBS의 호화 엔탈피는 12.9 J/g으로 CFBF와 FBF 보다 높은 값을 나타내었다. 상대결정화도에서도 역시 FSB가 CFBF와 FBF와 비교하여 상대적으로 높은 값을 나타내었다. CFBF와 FBF는 여러 실험들의 결과에서 서로 크게 차이 나지 않고 비슷한 경향의 특성을 확인하였으나 FBS는 CFBF, FBF와는 크게 다른 물리화학적 특징들을 보였다. 이는 서로 다른 단백질 함량 때문이라 판단된다. FBS는 녹말 추출을 위하여 NaOH 용액을 이용하여 단백질을 제거하여 단백질 함량이 CFBF, FBF와 비교했을 때 상당히 낮고 단백질을 제거하기 위한 공정 중 녹말의 변화가 있으며 CFBF와 FBF의 단백질은 녹말과 수분의 반응에 관여하여 물리화학적 특성에 영향을 끼쳤다고 판단되었다. 한국에서는 faba bean 가루와 녹말을 다양하게 사용하고 있지 않은데 이 연구의 결과는 식품산업에 faba bean을 적용하기 위한 기초자료로 사용될 수 있을 것이다.

• 공업화학
• /
• 제31권3호
• /
• pp.341-345
• /
• 2020

하폐수처리 및 정수처리에 사용되는 활성탄 흡착 공정에서 기존의 활성탄 열재생법 비해 활성탄 손실과 불완전 연소로 인한 오염물질 발생도 적으며, 사용 활성탄의 인발-재생-재충진에 소요되는 시간의 절약이 가능한 재생 방법으로 오존수를 이용한 in situ regeneration에 대한 기초연구를 수행하였다. 활성탄 흡착 컬럼 상에서 페놀(phenol) 및 PEG를 흡착 파과 시킨 후 오존수 접촉으로 흡착물질을 분해 제거하는 흡착-재생 싸이클을 반복하였다. 오존수 접촉에 의한 재생 횟수가 증가할수록 페놀 흡착용량은 어느 정도 감소하지만, 일정 수준으로의 감소 후에는 구조 변화가 안정화되어 추가적인 감소가 일어나지 않았다. 흡착 용량이 감소하는 이유는 오존과의 반응에 의해 활성탄의 미세공 크기가 증가하면서 비표면적이 감소하기 때문으로 나타났다. 이러한 세공 크기의 변화와 비표면적의 변화로 인하여 재생 후 in-pore adsorption이 우세한 페놀과 같은 저분자량 물질의 흡착효율은 감소하게 되나 external adsorption 비율이 큰 PEG와 같은 고분자량 물질의 흡착효율은 크게 영향을 받지 않았다. 세공 크기 및 비표면적의 변화는 오존수와의 접촉시간이 길어질수록 심화되므로 제거하려는 물질의 크기를 고려하고 접촉시간을 조절함으로써 흡착 효율의 유지를 제어하는 것이 필요하다.

• Journal of the Korean Wood Science and Technology
• /
• 제33권6호통권134호
• /
• pp.63-70
• /
• 2005

$225^{\circ}C$에서 $325^{\circ}C$ 이하의 저온에서 열처리한 셀룰로오스의 물성과 에틸아민 흡착특성을 열처리온도별로 조사하였다. 열처리온도의 증가와 더불어 수율이 감소하고, 탄소함량이 증가하는 반면, 수소나 산소의 함량은 감소하였다. 표면관능기량을 Boehm 법으로 측정한 결과, 열처리온도가 $300^{\circ}C$까지 올라가면 산성관능기량이 증가하였으나 그 이상의 온도에서는 다소 감소하는 경향이 있었다. 염기성관능기는 거의 존재하지 않았으며 열처리온도 $325^{\circ}C$에서 미량 확인할 수 있을 정도였다. 열처리셀룰로오스를 1점법으로 측정한 비표면적은 처리온도가 높으면 다소 증가하는 경향이 있었으나 매우 적었다. 열처리 온도가 증가할수록 셀룰로오스의 에틸아민증기 흡착량이 증가하여 $300^{\circ}C$ 처리 셀룰로오스의 에틸아민흡착에 의한 중량증가가 최대 113%를 나타내었다. $275^{\circ}C$에서 열처리셀룰로오스는 에틸아민 흡착 시, 팽윤이 일어나고 용해현상이 일어났다. $275^{\circ}C$ 이상의 온도에서 열처리한 셀룰로오스는 X선회절도 상에서 무정형화 하는 것으로 나타났다. 에틸아민 흡착한 열처리셀룰로오스의 용해 현상은 셀룰로오스의 결정구조 붕괴와 염기성 가스의 흡착량 증가에 의한 것으로 추측된다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
• /
• pp.62-62
• /
• 1999

Carbon based materials have many attractive properties such as a wide band gap, a low electron affinity, and a high chemical and mechanical stability. Therefore, researches on the carbon-based materials as field emitters have been drawn extensively to enhance the field emission properties. Especially, diamond gives high current density, high current stability high thermal conductivity durable for high temperature operation, and low field emission behaviors, Among these properties understanding the origin of low field emission is a key factor for the application of diamond to a filed emitter and the verification of the emission site and its distribution of diamond is helpful to clarify the origin of low field emission from diamond There have been many investigations on the origin of low field emission behavior of diamond crystal or chemical vapor deposition (CVD) diamond films that is intentionally doped or not. However, the origin of the low field emission behavior and the consequent field emission mechanism is still not converged and those may be different between diamond crystal and CVD diamond films as well as the diamond that is doped or not. In addition, there have been no systematic studies on the dependence of nondiamond carbon on the spatial distribution of emission sites and its uniformity. Thus, clarifying a possible mechanism for the low field emission covering the diamond with various properties might be indeed a difficult work. On the other hand, it is believed that electron emission mechanisms of diamond are closely related to the emission sites and its distributions. In this context, it will be helpful to compare the spatial distribution of emission sites and field emission properties of the diamond films prepared by systematic variations of structural property. In this study, we have focused on an understanding of the field emission variations of structural property. In this study, we have focused on an understanding of the field emission mechanism for the CVD grown undoped polycrystalline diamond films with significantly different structural properties. The structural properties of the films were systematically modified by varying the CH4/H2 ratio and/or applying positive substrate bias examined. It was confirmed from the present study that the field emission characteristics are strongly dependent on the nondiamond carbon contents of the undoped polycrystalline diamond films, and a possible field emission mechanism for the undoped polycrystalline diamond films is suggested.

• 한국식품영양학회지
• /
• 제10권2호
• /
• pp.234-240
• /
• 1997

식품산업을 포함한 다양한 분야에서 이용되고 있는 한천의 용도를 개발하기 위하여 각종 물리적인 처리가 한천의 열적 특성에 미치는 영향과 각 처리에 다른 표면구조의 변화를 조사하였다. 시차주사 열량분석기를 이용하여 w사한 일반한천의 흡열개시온도(To), 최대흡열점의 온도(Tp) 및 흡열완료온도(Te)는 81.20, 95.51 및 $112.14^{\circ}C$였으며, 분무건조한천은 60.11, 76.45 및 $89.54^{\circ}C$였고, 압출성형한천은 41.30, 61.72 및 $80.50^{\circ}C$로 압출성형한천이 가장 낮은 온도에서 진행되었다. 또한 엔탈피도 일반한천 3.22cal/g, 분무\ulcorner한천 1.53cal/g, 압출성형한천 0.73cal/g의 순서로 압출성형한천에서 가장 낮았다. 완전히 가열용해한 각 한천을 다시 냉각, 응고 후에 다시 승온하였을 때의 To, Tp 및 Te는 일반한천 80.70, 95.61 및 $110.92^{\circ}C$, 붐무건조한천 79.54, 93.76 및 $109.84^{\circ}C$, 압출성형한천 79.25, 93.19 및 $108.77^{\circ}C$로 한천의 종류에 따른 차이는 없었다. 엔탈피 역시 큰 차이를 보이지 않았다. 광학현미경과 주사전자현미경에 의해 표면구조를 관찰한 결과, 일반한천의 경우 단단한 구조로 균열이나 기공들이 관찰되지 않았고, 분무건조한천은 많은 미세입자들이 다량으로 느슨하게 붙어있는 다공질구조로 외부에 노출되는 표면적이 넓었으며, 압출성형한천은 굴곡, 요철 및 균열이 생겨서 수분침투가 용이한 구조를 이루고 있었다.

• 천문학회보
• /
• 제35권1호
• /
• pp.57-57
• /
• 2010

We report the discovery of a bright mid-infrared (MIR) source with prominent crystalline silicate emission using the space telescope AKARI and Spitzer. This source, IRAS 15099-5856, has a spectacular morphology with a bright central compact source (CCS) surrounded by knots, spurs, and several extended (~4') arc-like filaments. The source is seen only in infrared at ${\geq}10{\mu}m$. The Spitzer MIR spectrum of the CCS shows prominent emission features from Mg-rich crystalline silicates and strong [Ne II] 12.88 ${\mu}m$ and several other faint ionic lines. We model the MIR spectrum as thermal emission from several independent dust components and compare their properties to those of the Herbig Be star HD 100546 which shows very similar MIR spectrum. Our molecular line observations reveal two molecular clouds around the source, but no associated dense molecular cores. We discuss two possible origins for IRAS 15099-5856; a deeply embedded massive young stellar object on the other side of the Galaxy and a disrupted, protoplanetary disk being photoevaporated by the UV radiation from the nearby O star Muzzio 10.

• 마이크로전자및패키징학회지
• /
• 제21권3호
• /
• pp.31-35
• /
• 2014

본 연구에서는 $TiO_2$ 나노입자를 LED패키지의 봉지재인 실리콘에 분산시키고, 이에 따른 굴절률, 투과율 및 광효율 변화를 평가하였다. $TiO_2$ 나노입자는 LED 봉지재의 굴절율을 증가시켜 LED 패키지의 광추출 효율을 향상시키기 위해 봉지재에 적용되었다. $TiO_2$는 수열합성법을 통해 합성되었고, 합성된 $TiO_2$ 입자에 긴 체인구조의 vinyl silane을 코팅하여 분산시켰다. 분산 처리를 실시한 후에는 대부분의 $TiO_2$ 나노입자가 10~40 nm 이하로 분산되었으나, 100 nm 이상의 긴 입자도 관찰되었다. 실리콘 봉지재에 $TiO_2$ 나노입자 양이 증가할수록 굴절율은 증가하였으나, 투과율은 감소하였다. $TiO_2$ 나노입자가 포함된 실리콘 봉지재로 LED 패키지를 제조하였고, $TiO_2$ 나노입자가 분산된 LED가 $TiO_2$ 나노입자가 없는 LED패키지에 비해 약 13% 이상 광효율이 향상되었다.

• 한국세라믹학회지
• /
• 제43권6호
• /
• pp.369-375
• /
• 2006

[ $(Ba_{0.5}Sr_{0.5})_{0.99}Co_{x}Fe_{1-x}O_{3-{\delta}}$ ] [x=0.8, 0.2](BSCF) powders were synthesized by a Glycine-Nitrate Process (GNP) and the electrochemical performance of the BSCF cathode on a scandia stabilized zirconia, $[(Sc_{2}O_3)_{0.11}(ZrO_2)_{0.89}]-1Al_{2}O_3$ was investigated. In order to prevent unfavorable solid-state reactions between the cathode and zirconia electrolyte, a GDC ($Gd_{0.1}Ce_{0.9}O_{2-{delta}}$) buffer layer was applied on ScSZ. The BSCF (x = 0.8) cathode formed on GDC(Buffer)/ScSZ(Disk) showed poor electrochemical property, because the BSCF cathode layer peeled off after the heat-treatment. On the other hand, there were no delamination or peel off between the BSCF and GDC buffer layer, and the BSCF (x = 0.2) cathode exhibited fairly good electrochemical performances. It was considered that the observed phenomenon was associated with the thermal expansion mismatch between the cathode and buffer layer. The ohmic resistance of the double layer cathode was slightly lower than that of the single layer BSCF cathode due to the incorporation of platinum particle into the BSCF second layer.

• 대한치과기공학회지
• /
• 제33권4호
• /
• pp.349-357
• /
• 2011

Purpose: In this study, for the reasons of observing the changes when using bonding agent with Ni-Cr alloy and Co-Cr alloy and using VM13 and Vintage MP ceramic which have the disparity in coefficient of thermal expansion, it is carried out to evaluate the characteristics of the bonding agent through the analysis of the interface between metal and ceramic and the analysis of bond strength by variable. Methods: The surface treatment was performed on the two kinds of alloy(Ni-Cr alloy and Co-Cr alloy) specimens, which were sandblasted and were treated with bonder application. The metal-ceramic interfaces were analyzed with EPMA in order to ionic diffusion, and the shear test was performed. Results: As a result of observation of metal-ceramic interfacial properties, it was observed that Cr atoms were spread from the alloy body to the ceramic floor in the specimen of Group B. It was also seen that Cr, W atoms were spread from the alloy body to the ceramic floor in the specimen of Group S. In consequence of observing Shear bond strength, it was calculated that the specimen of BSV was 27.75(${\pm}11.21$)MPa, BSM was 27.02(${\pm}5.23$)MPa, BCV was 30.20(${\pm}5.99$)MPa, BCM was 27.94(${\pm}10.76$)MPa, SSV was 20.83(${\pm}2.58$)MPa, SSM was 23.98(${\pm}3.94$)MPa, SCV was 32.32(${\pm}4.68$)MPa, and SCM was 34.54(${\pm}10.63$)MPa. Conclusion: In the metal-ceramic interface of Bellabond plus sample group, diffusion of Cr atoms was incurred and diffusion of C Cr atoms and W atoms in the sample group of $Starloy{(R)}\;C$ was observed. Using bonding agent showed the higher bond strength than using the sand blasting treatment. In the Bellabond plus alloys, the specimen group with the use of binding materials showed higher shear bond strength, but didn't show statistically significant differences (p>0.05). In the $Starloy{(R)}\;C$ alloys, the specimen group with the use of binding materials showed higher shear bond strength and statistically significant differences(p<0.05). In terms of VM13 ceramic, it was in the Bellabond plus alloys that the high shear bond strength was showed, but there's no statistically significant differences(p>0.05). In terms of Vintage MP ceramic, it was in the $Starloy{(R)}\;C$ alloys that the high shear bond strength was showed and statistically significant differences(p<0.05). Metal-ceramic to fracture of the shear strength measurements and an analysis of all aspects of military usage fracture of the composite, respectively.