• 제목/요약/키워드: National physical laboratory

검색결과 648건 처리시간 0.027초

기상청 현업 지역통합모델 물리과정 최적화를 통한 예측 성능 향상 (The Improvement of Forecast Accuracy of the Unified Model at KMA by Using an Optimized Set of Physical Options)

  • 이주원;한상옥;정관영
    • 대기
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    • 제22권3호
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    • pp.345-356
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    • 2012
  • The UK Met Office Unified Model at the KMA has been operationally utilized as the next generation numerical prediction system since 2010 after it was first introduced in May, 2008. Researches need to be carried out regarding various physical processes inside the model in order to improve the predictability of the newly introduced Unified Model. We first performed a preliminary experiment for the domain ($170{\times}170$, 10 km, 38 layers) smaller than that of the operating system using the version 7.4 of the UM local model to optimize its physical processes. The result showed that about 7~8% of the improvement ratio was found at each stage by integrating four factors (u, v, th, q), and the final improvement ratio was 25%. Verification was carried out for one month of August, 2008 by applying the optimized combination to the domain identical to the operating system, and the result showed that the precipitation verification score (ETS, equitable threat score) was improved by 9%, approximately.

앵커 그룹으로서 아자크라운 에테르를 포함한 새로운 이온교환체에 의한 리튬 동위원소의 농축 (Enrichment of Lithium Isotope by Novel Ion Exchanger Containing Azacrown Ether as Anchor Group)

  • 김동원;이남수;정영규;류해일;김창석;김봉균
    • 분석과학
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    • 제11권4호
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    • pp.231-234
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    • 1998
  • $N_3O_3$가 앵커 그룹으로 포함된 이온교환체를 사용하여 $^6Li$$^7Li$의 분리인자를 측정하였다. 이온교환체의 이온교환 용량은 2.0 meq/g 이었다. 3M 염화암모늄 수용액을 용리액으로 하였으며, 내경 0.3 cm, 높이 30 cm의 칼럼을 이온교환크로마토그래피에 사용하였다. 가벼운 동위원소 $^6Li$는 유체상에, 무거운 동위원소 $^7Li$는 수지상에 농축되었다. 용리곡선과 동위원소 비를 가지고 Glueckauf의 이론에 따라 분리인자를 구하였으며, 그 값은 1.018이었다.

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Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event

  • Bucknor, Matthew;Grabaskas, David;Brunett, Acacia J.;Grelle, Austin
    • Nuclear Engineering and Technology
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    • 제49권2호
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    • pp.360-372
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    • 2017
  • Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event.

Cell thickness dependence of liquid crystal parameters

  • Sood, Nitin;Khosla, Samriti;Singh, Darshan;Bawa, S.S.
    • Journal of Information Display
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    • 제13권1호
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    • pp.31-36
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    • 2012
  • Ferroelectric liquid crystal parameters, spontaneous polarization, and transition temperature were studied as a function of cell thickness. These parameters were found to increase with increasing cell thickness, but an exception was observed for the transition temperature in the case of a thin cell. A simple Landau model is presented to interpret the theoretical and experimental observations. The anomalous behavior is attributed to the electroclinic effect and is explained using the Landau model.

Challenges in Carbon/Carbon Composites Technologies

  • Dhami, T.L.;Bahl, O.P.
    • Carbon letters
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    • 제6권3호
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    • pp.148-157
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    • 2005
  • Carbon/Carbon Composites due to their far superior thermo-mechanical properties are used in a number of demanding applications. However, the material still is used only in specific high tech applications with few exceptions in general industrial applications. The material is extremely expensive and the major challenge is to reduce its cost. Various innovative processing routes are outlined to reduce the cost of processing.

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아자크라운 에터를 포함한 이온교환수지에 의한 리튬 동위원소의 농축 (Enrichment of Lithium Isotope by an Ion Exchange Resin Containing Azacrown Ether)

  • 김동원;정용순;최기영;이용일;정영규;장영훈
    • 분석과학
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    • 제10권6호
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    • pp.403-407
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    • 1997
  • Anchor group으로서 1,7,13-trioxa-4,10,16-triazacyclooctadecane($N_3O_3$)을 가지고 있는 이온교환수지를 사용하여 $^6Li$$^7Li$의 분리인자를 측정하였다. 가벼운 동위원소 $^6Li$는 액상에, 무거운 동위원소 $^7Li$는 이온교환수지상에 농축되었다. 2.0M 염화암모늄 용액을 용리액으로 사용한 컬럼 [0.9cm(내경)${\times}$20cm(높이)] 크로마토그래피에 의하여, 1.009의 분리인자, ${\alpha}$, $(^7Li/^6Li)_{resin}$/$(^7Li/^6Li)_{solution}$값을 얻었다. 이 값은 용리곡선과 동위원소비로부터 Glueckauf 이론을 적응하여 얻은 것이다.

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Effect of Solvents on Physical Properties and Release Characteristics of Monolithic Hydroxypropylmethylcellulose Matrix Granules and Tablets

  • Cao Qing-Ri;Choi Yun-Woong;Cui Jing-Hao;Lee Beom-Jin
    • Archives of Pharmacal Research
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    • 제28권4호
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    • pp.493-501
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    • 2005
  • Effect of solvents on physical characteristics and release characteristics of monolithic acetaminophen (APAP) hydroxypropylmethylcellulose (HPMC) matrix granules and tablets were examined. Various types and amounts of solvents were employed for granulation and coating. APAP and other excipients were mixed and were then wet-granulated in a high-speed mixer. The dried granules were then directly compressed and film-coated with low viscosity grade HPMC. As the amount of water increased, the size of granules also increased, showing more spherical and regular shape. However, manufacturing problems such as capping and lamination in tableting occurred when water was used alone as a granulating solvent. The physical properties of HPMC matrix granules were not affected by the batch size. The initial release rate as well as the amount of APAP dissolved had a tendency to decrease as the water level increased. Addition of nonaqueous solvent like ethanol to water resulted in good physical properties of granules. When compared to water/ethanol as a coating solvent, the release rate of film-coated HPMC matrix tablets was more sensitive to the conditions of coating and drying in methylene chloride/ethanol. Most of all, monolithic HPMC matrix tablet when granulated in ethanol/water showed dual release with about $50\%$ drug release immediately within few minutes followed by extended release. It was evident that the type and amount of solvents (mainly water and ethanol) were very important for wet granulation and film-coating of monolithic HPMC matrix tablet, because the plastic deforming and fragmenting properties of material were changed by the different strengths of the different solvents.

Laboratory/In situ Sound Velocities of Shelf Sediments in the South Sea of Korea

  • Kim, Dae-Choul;Kim, Gil-Young;Jung, Ja-Hun;Seo, Young-Kyo;Wilkens, Roy H.;Yoo, Dong-Geun;Lee, Gwang-Hoon;Kim, Jeong-Chang;Yi, Hi-Il;Cifci, Gunay
    • Fisheries and Aquatic Sciences
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    • 제11권2호
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    • pp.103-112
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    • 2008
  • Compressional sound velocities of shelf sediments in the South Sea of Korea, were measured in situ and in the laboratory for six cores. In situ sound velocity was measured using the Acoustic Lance (frequency of 7.5-15 kHz), while laboratory velocity was measured by the pulse transmission technique (frequency of 1MHz). Physical properties were relatively uniform with sediment depth, suggesting little effect of sediment compaction and/or consolidation. Average in situ velocity at each core site ranged from 1,457 to 1,488 m/s, which was less than the laboratory velocity of 1,503 and 1,604m/s. In muddy sediments the laboratory velocity was 39-47 m/s higher than in situ velocity. In sandy sediments, the difference was greater by an average of 116 m/s. Although the velocity data were corrected by the velocity ratio method based on bottom water temperature, the laboratory velocity was still higher than the in situ velocity (11-21 m/s in muddy sediments and 91 m/s in sandy sediments). This discrepancy may be caused by sediment disturbance during core collection and/or by the pressure of Acoustic Lance insertion, but it was most likely due to the frequency difference between in situ and laboratory measurement systems. Thus, when correcting laboratory velocity to in situ velocity, it is important to consider both temperature and frequency.

A Case of Visceral T Cell Lymphoma with Prominent Histiocyte Infiltration in a Dog

  • Myung-Chul Kim;Du-Min Go;Sang-Ho Woo;Jeong-Seop Oh;Dae-Yong Kim;Na-Yon Kim;Yeseul Yang;Jae-Ha Jung;Hwa-Young Youn;Yongbaek Kim
    • 한국임상수의학회지
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    • 제40권5호
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    • pp.387-392
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    • 2023
  • A 13-year-old intact male English Springer Spaniel presented with anorexia. Physical examination revealed a palpable abdominal mass without peripheral lymphadenopathy. Ultrasonography revealed hepatosplenomegaly and a markedly enlarged hepatic lymph node. Fine-needle aspiration of the splenic and nodal lesions revealed atypical round cells admixed with numerous histiocytes. The dog was euthanized owing to deteriorating condition despite a month of chemotherapy with lomustine. Histopathology revealed obliteration of the normal architecture of the liver, spleen, kidney, and hepatic and mesenteric lymph nodes by CD3+ neoplastic lymphocytes, accompanied by extensive F4/80+ histiocytic infiltration. This report describes a rare presentation of T-cell lymphoma with prominent histiocytic infiltration that may initially be misdiagnosed as histiocytic neoplasia in a dog.