• Title/Summary/Keyword: sheath

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A Generalized Model for the Prediction of Thermally-Induced CANDU Fuel Element Bowing (CANDU 핵연료봉의 열적 휨 모형 및 예측)

  • Suk, H.C.;Sim, K-S.;Park, J.H.
    • Nuclear Engineering and Technology
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    • v.27 no.6
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    • pp.811-824
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    • 1995
  • The CANDU element bowing is attributed to actions of both the thermally induced bending moments and the bending moment due to hydraulic drag and mechanical loads, where the bowing is defined as the lateral deflection of an element from the axial centerline. This paper consider only the thermally-induced bending moments which are generated both within the sheath and the fuel and sheath by an asymmetric temperature distribution with respect to the axis of an element The generalized and explicit analytical formula for the thermally-induced bending is presented in con-sideration of 1) bending of an empty tube treated by neglecting the fuel/sheath mechanical interaction and 2) fuel/sheath interaction due to the pellet and sheath temperature variations, where in each case the temperature asymmetries in sheath are modelled to be caused by the combined effects of (i) non-uniform coolant temperature due to imperfect coolant mixing, (ii) variable sheath/coolant heat transfer coefficient, (iii) asymmetric heat generation due to neutron flux gradients across an element and so as to inclusively cover the uniform temperature distributions within the fuel and sheath with respect to the axial centerline. As the results of the sensitivity calculations of the element bowing with the variations of the parameters in the formula, it is found that the element bowing is greatly affected relatively with the variations or changes of element length, sheath inside diameter, average coolant temperature and its variation factor, pellet/sheath mechanical interaction factor, neutron flux depression factor, pellet thermal expansion coefficient, pellet/sheath heat transfer coefficient in comparison with those of other parameters such as sheath thickness, film heat transfer coefficient, sheath thermal expansion coefficient and sheath and pellet thermal conductivities.

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A Case of Nerve Sheath Myxoma on the Fingertip (수지첨부에 발생한 신경초 점액종)

  • Lee, Yong-Seok;Kim, Chul-Han;Kang, Sang-Gue;Tark, Min-Seong
    • Archives of Plastic Surgery
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    • v.37 no.1
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    • pp.67-70
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    • 2010
  • Purpose: Nerve sheath myxoma is a rare cutaneous neoplasm originating from the peripheral nerve sheath and divided into three groups : myxoid, cellular and mixed type. There is a controversy on it's origin whether schwannian cell or perineurial differentiation, or anything else. Myxoid nerve sheath myxoma is asymptomatic, soft, papule or nodule in middle-age adults. We report a case of myxoid nerve sheath myxoma on the fingertip. Methods: A 53-year-old woman presented with a painful, $0.4{\times}0.4{\times}0.6\;cm $sized, corn shaped nodule on the left 3rd fingertip. We put into surgical excision and studied it by histopathologically and specific immnohistochemical stain. Results: The tumor has well defined nodules separated by thin fibrous connective tissue with abundant myxoid stroma and were positively stainded for S-100 protein, NSE and GFAP. After surgical treatment it was healed without recurrence. Conclusion: Nerve sheath myxoma is rare neoplasm and located mainly on face, but very rarely on the fingertip. We report a case of painful myxoid nerve sheath myxoma located on the 3rd fingertip.

Detail relation of negative ion density with positive ion mass and sheath parameters

  • Kim, Hye-Ran;Woo, Hyun-Jong;Sun, Jong-Ho;Chung, Kyu-Sun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.470-470
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    • 2010
  • Negative ions are generated in fusion edge plasmas, material processing plasmas, ionospheric plasmas. Analytic formulas for the deduction of the absolute density of negative ions was given by using the current-voltage(IV) characteristics of two electric probes at two different pressures [1], and negative ion density has been measured by one electric probe using the current-voltage characteristics of three different pressures [2]. Ratios of ion and electron saturation currents and electron temperatures and sheath areas of different pressures are usually incorporated into two equations with two unknowns for the negative ion density. In the previous publications, the sheath factor(sheath area, sheath density, sheath velocity) and effective masses of background ions with different pressures are qualitatively incorporated for the deduction of negative density. In this presentation, the quantitative and detailed relation of negative ion density with sheath factor and effective masses are going to be given. The effect of these parameters on the change of IV characteristics will be addressed.

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Characteristics of Sheath Circulating Current by Underground Transmission Systems Analysis (지중송전시스템 해석을 통한 시스순환전류 특성 분석)

  • Jung, Chae-Kyun;Lee, Jong-Beom;Kang, Ji-Won
    • Proceedings of the KIEE Conference
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    • 2002.07a
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    • pp.449-451
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    • 2002
  • Sheath circulating current rises from the change of sheath mutual impedance which is caused by imbalanced cable system, and different section length between joint boxes. However, mixed burying typo and imbalance section length take many parts of main reasons of sheath circulating current increment in domestic underground transmission power cables. Therefore, the increment reason and variation characteristics of sheath circulating current is analysed with simulation using EMTP/ATPDraw and measuring data of practical cable system which has a problem of exceeding sheath circulating current in this paper.

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I-V Characteristics of Negatively DC Pulsed Target in ECR Plasma for Landmine Detection (지뢰탐지를 위한 ECR 플라즈마에서 타깃에 고전압 DC 펄스 인가시 전압-전류 특성 분석)

  • Kim, Seong Bong;Lee, Hui Jea;Park, Seungil;Yoo, Suk Jae;Cho, Moohyun;Han, Seung-Hoon;Lim, Byeongok
    • Journal of the Korean institute of surface engineering
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    • v.47 no.1
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    • pp.53-56
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    • 2014
  • I-V characteristics of a cylindrical target in an ECR plasma were studied for sheath spatial evolutions when the target was pulsed biased to a high negative potential. The magnetic field effects on sheath thickness and sheath boundary speed were investigated by comparison between the experimental results and the theoretical results using the Child-Langmuir sheath model. The results showed that the magnetic field suppressed electron motion away from the target so that sheath thickness and sheath boundary speed decreased.

Microstructure and Mechanical Property of Aluminum Powder Compact by Powder-in Sheath Rolling Method (분말시스압연법에 의해 제조된 알루미늄 분말성형체의 조직 및 기계적 성질)

  • 이성희
    • Journal of Powder Materials
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    • v.9 no.3
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    • pp.153-160
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    • 2002
  • A nitrogen gas atomized aluminum powder was consolidated by powder-in sheath rolling method. A pure aluminum tube with outer diameter of 12 mm and wall thickness of 1mm was used as a sheath. The aluminum tube filled with the aluminum powder, first, was cold-rolled to the thickness of 6mm for performing, and then consolidated by the cold rolling and/or subsequent hot rolling at 360, 460 and $560^{\circ}C$. The aluminum powder compact fabricated by the sheath rolling showed high relative density more than 0.96 at any rolling conditions. The 0.2% proof stress increased with increasing hot rolling reduction and hot rolling temperature. Tensile strength was hardly affected by change in the hot rolling reduction, whereas it decreased with increasing hot rolling temperature. The powder compact showed the large elongation when cold rolling or hot rolling reduction was large. It was found that the sheath rolling was an effective method for consolidation of aluminum powder.

Concurrence of Malignant Peripheral Nerve Sheath Tumor at the Site of Complex Regional Pain Syndrome Type 1 - A Case Report -

  • Jeong, Yeong Ho;Choi, Eun Joo;Nahm, Francis Sahngun
    • The Korean Journal of Pain
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    • v.26 no.2
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    • pp.160-163
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    • 2013
  • Malignant peripheral nerve sheath tumors (MPNSTs) are very rare sarcomas derived from various cells in the peripheral nerve sheath. Malignant peripheral nerve sheath tumors have a known association with neurofibromatosis type 1. Diagnosis of MPNSTs is difficult in patients with chronic pain, when MPNST occurs at an overlapping area of chronic pain. Therefore, the diagnosis can be missed unless clinicians pay attention to the possibility of this disease. Here in, we report a case of concurrent malignant peripheral nerve sheath tumor with complex regional pain syndrome type 1. A 44-year female patient, who was diagnosed with complex regional pain syndrome (CRPS) type 1 in her left ankle, visited our clinic because of aggravated pain. The cause of the aggravated pain was revealed as concurrent MPNST in the left common peroneal nerve territory, which overlapped the site of pain from CRPS.

Effect of Leaf Sheath Removals on Growth Responses in Forcing of Lilium spp. (나리속(屬) 식물의 촉성 재배에 있어 엽초 제거가 생육에 미치는 영향)

  • Jung, Woo-Yoon;Choi, Sang-Tai;Park, In-Hwan;Kim, Seung-Tae;Park, Hyun-Gun
    • Current Research on Agriculture and Life Sciences
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    • v.21
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    • pp.31-37
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    • 2003
  • The study aimed to identify leaf sheath through the investigation a characteristic of leaf by planting depth and leaf sheath function through the investigation of effect of leaf sheath removals on growth and flowering in forcing of Lilium cultivars. The number of leaf sheath of 'Jolanda', 'Dream Land', 'Casablanca' were 6, 5, 11 in 0cm planting depth and 6, 5, 14 in 6cm planting depth. The number of leaf sheath in 'Jolanda' and 'Dream Land' were little different in according to planting depth. The other hand, the number of leaf sheath in 'Casablanca' were increased 3 when it were planted in 6cm planting depth. As leaf sheath were removed, plant height and stem root growth were decreased in 'Le Reve' and 'Casablanca'. Whereas the growth of basal root and flower number varied among of Lillium and stem diameter, the days of flowering and flower size were little different.

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The Function of Leaf Sheath on Growth and Development of Gladilous (글라디올러스의 생육에 미치는 엽초의 역할)

  • Jung, Woo-Yoon;Chang, Young-Deug;Ahn, Hyung-Geun;Choi, Sang-Tai;Park, In-Hwan
    • Current Research on Agriculture and Life Sciences
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    • v.21
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    • pp.17-21
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    • 2003
  • This study aimed to identify leaf sheath function through the investigation of effect of removal times and removed number of leaf sheath on growth and flowering in gladiolus. The leaf sheath influenced on the growth and flowering regardless of light condition at early growth stages. When total leaf sheath were removed in early growth stages, flower stalk length and spike length remarkably decreased. Whereas days of flowering were little different by leaf sheath removal. Also when removed numbers of leaf sheath were 1, 2 and 3, the growth and flowering were little different compared to control. But when removed numbers of leaf sheath were 4, flower stalk length decreased above 25cm compared to others treatment, spike length and number of flower decreased and stem diameter became thick abnormally.

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Mechanical properties at Bi-2223 HTS tapes with various sheath materials (기지금속을 달리한 Bi-2223 초전도 선에서의 기계적 특성 변화)

  • Ha, Dong-Woo;Lee, Dong-Hoon;Yang, Joo-Sang;Kim, Sang-Chul;Hwang, Sun-Yuk;Ha, Hong-Soo;Oh, Sang-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.551-554
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    • 2004
  • Bi-2223 HTS tapes are used widely for application of superconducting power systems. However there are need the properties of high strength and low AC loss. Two kinds of Bi-2223 HTS tapes with different Ag sheath were used to know the effect of sheath alloying for the strength and the resistivity. The workability and reaction degree of superconducting phase at Bi-2223 HTS tapes were investigated. We designed conventional type-Ag/alloy and double sheathed mono filament type-Ag/alloy/alloy in order to increase the strength and resistivity of matrix in Bi-2223 HTS tapes. The effect of axial strain and thermal cycling on the critical current was investigated for the Bi-2223 HTS tapes. Because the workability of double sheath Bi-2223 HTS tape was lower than one sheath Bi-2223 HTS tape, it was need additional softening treatment. Bi-2223 formation reaction was decreased by Ag alloy matrix during sintering process. Two kinds of Bi-2223/Ag tapes with different Ag sheath were used to know the effect of sheath alloying for the tensile strain. Critical current is drastically decreased for Ag/alloy and Ag/alloy/alloy sheathed tapes at tensile strain above 0.24 % and 0.34 %, respectively. This result showed that mechanical strength was increased over than 40 % by introduce double sheath at mono filament stage.

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