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A study on the improvement of the local stress field in a displacement-formulated finite element solution (변위형 유한요소 해에서 국부응력장 향상에 대한 연구)

  • Song, Kee-Nam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.2
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    • pp.278-288
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    • 1998
  • An efficient and useful method to improve the local stress field in a displacement-formulated finite element solution has been proposed using the theory of conjugate approximations for a stress field and the Loubignac's iterative method for a displacement field. Validity of the proposed method has been tested through three test examples, to improve the stress field and displacement field in the whole domain and the local regions. As a result of analysis on the test examples, it is found that the stress field in the local regions are approximated to those in the whole domain within a few iterations which have satisfied the original finite element equilibrium equation. In addition, it is found that the local stress field are by far better approximated to the exact stress field than the displacement-based stress field with the reduction of the finite-element mesh-size.

Design and fabrication of race-track type field coil for the high temperature superconduction generator

  • Baik, S.K.;Jo, Y.S.;Ha, H.S.;Lee, E.Y.;Jeong, D.Y.;Kwon, Y.K.;Ryu, K.S.;Sohn, M.H.
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.248-251
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    • 2000
  • The fabrication and characteristics of HTS race-track type field coil for generators was carried out. Field coils are composed of 3 pancake coils wound by 37-filamental Bi-2223/Ag-alloy tapes. The winding machine is horizontal type. The critical currents (I$_c$) of the superconducting tapes were measured with variation of bending strain and external magnetic fields. I$_c$ of both whole field coils and 3 pancake coils were measured as a function of temperature. At 77K under the self-field, I$_c$ of whole field coils was 12A, while in the case of middle pancake coil, I$_c$ was 15A. The distribution of magnetic field B was obtained, using 3-D FEM. Our simulation showed that maximums of B${\bot}$A in x-y plane were locally distributed in both the upper and the lower coils. In addition, the fabrication processes and the characteristics of field coil are described.

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Study on Growth Responses of Soybean in Paddy Field for Establishing Environment-Friendly Cropping System (친환경 논 밭 윤환 콩 재배법 확립을 위한 논 콩 재배시 품종별 생육반응 연구)

  • Kim, Yong-Wook;Cho, Joon-Hyeong
    • Korean Journal of Organic Agriculture
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    • v.12 no.4
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    • pp.437-450
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    • 2004
  • This study was conducted with two objectives ; one was to select the suitable soybean cultivars for cultivation in paddy field and the other was to establish the environment-friendly rotational cropping system of soybean instead of rice in paddy field. In order to evaluate growth adaptation and yields, Eve soybean cultivars were cultivated in Yeoncheon, Keonggi province, with two cultivation methods such as level row and high ridge. Growth of the top plants, such as stem length, number of branches, diameter of stem, were higher in high ridge than in level row, however, the differences among the cultivars were bigger than those between the cultivation methods. Dry weight of top plant was significantly different among the cultivars during whole growth stages, however, it was higher in level row than in high ridge at V5 stage while it became higher in high ridge as growth progressed. Roots were more developed in high ridge than in level row during whole growth stages. T/R ratio in level row was higher than that in high ridge. During whole growth stages, significant differences were observed among the cultivars in growth and yields in each cultivation method and yields of Eunhakong was the highest. In results, number of nodules and T/R ratio at V5 stage, number of pods at R2 stage, and number of seeds and T/R ratio at R5 stage had highly correlated with yields, respectively.

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Treatment Planning Correction Using MRI in the Radiotherapy of Cervical Cancer (자궁 경부암의 방사선 치료계획에서 자기공명 영상을 이용한 조사야 교정)

  • Shin, Sei-One;Cho, Kil-Ho;Park, Chan-Won
    • Journal of Yeungnam Medical Science
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    • v.12 no.2
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    • pp.203-209
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    • 1995
  • Purpose: To evaluate the role of MRI in the management of cervical cancer treated by conventional four-field whole pelvic irradiation. Method and material: Between 1993-march and 1994-february, 20 patients(4 Stage I B, 3 Stage II A, 13 Stage II B) with invasive cervical cancer were eligible for evaluation of accuracy of conventionally designed lateral treatment field without MRI determination. Results: 5 out of 20 Patients had inadequate margin without MRI. The position of uterine fundus was more important than cervix in correction of field size and the center of treatment field. Conclusion: This Preliminary data show MRI determination of uterine position prior to radiotherapy planning is essential in the case of four-field whole pelvic irradiation technique.

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Whole Mitochondrial Genome Sequence of an Indian Plasmodium falciparum Field Isolate

  • Tyagi, Suchi;Pande, Veena;Das, Aparup
    • Parasites, Hosts and Diseases
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    • v.52 no.1
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    • pp.99-103
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    • 2014
  • Mitochondrial genome sequence of malaria parasites has served as a potential marker for inferring evolutionary history of the Plasmodium genus. In Plasmodium falciparum, the mitochondrial genome sequences from around the globe have provided important evolutionary understanding, but no Indian sequence has yet been utilized. We have sequenced the whole mitochondrial genome of a single P. falciparum field isolate from India using novel primers and compared with the 3D7 reference sequence and 1 previously reported Indian sequence. While the 2 Indian sequences were highly divergent from each other, the presently sequenced isolate was highly similar to the reference 3D7 strain.

Whole brain radiotherapy using four-field box technique with tilting baseplate for parotid gland sparing

  • Park, Jaehyeon;Yea, Ji Woon
    • Radiation Oncology Journal
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    • v.37 no.1
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    • pp.22-29
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    • 2019
  • Purpose: The aim of this study is to evaluate the efficacy and feasibility of four-field box whole brain radiotherapy (FB-WBRT) with tilting baseplate by comparing bilateral WBRT (B-WBRT). Methods and Materials: Between March 2016 and September 2018, 20 patients with brain metastases underwent WBRT using the four-field box technique. WBRT is performed with a dose of 30 Gy in 10 fractions daily. Two computed tomography simulations per person were performed. One was in the traditional supine position for B-WBRT and the other by applying the tilting acrylic supine baseplate to elevate the head by 40° for FB-WBRT. The B-WBRT used the field-in-field technique, which is the most commonly used method in our institution. The FB-WBRT comprised anterior, posterior, and bilateral beams. A wedge was applied in anterior and posterior fields to compensate for skull convexity. Results: The average of Dmean of both parotid glands was 10.2 Gy (range, 3.8 to 17.8 Gy) in B-WBRT and 5.4 Gy (range, 2.0 to 11.7 Gy) in FB-WBRT (p < 0.05). Compared to B-WBRT, FB-WBRT reduced the mean dose of the right and left parotid glands from 10.1 Gy to 4.9 Gy and from 10.4 Gy to 5.8 Gy, respectively (p < 0.05). Further, V5, V10, V15, V20, and V25 for the parotid gland decreased significantly in FB-WBRT (p < 0.05). The Dmax and Dmean of lens decreased according to the dose-volume histogram. Conclusion: Compared to B-WBRT, FB-WBRT with a tilting baseplate is a simple and effective method that takes feature of noncoplanar beam to protect the parotid gland.

Growth Characteristics and Feed Value of Whole Crop Silage Rice on Paddy Field and Reclaimed Tidal Land (일반답과 간척답에서 사료용벼 재배시 생육특성 및 사료가치)

  • Cho, Kwang-Min;Back, Nam-Hyun;Yang, Chang-Hyu;Shin, Pyung;Noh, Tae-Hwan;Lee, Geon-Hwi;Lee, Kyeong-Bo;Park, Ki-Hun
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.59 no.4
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    • pp.526-531
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    • 2014
  • This study was carried out to compare the growth characteristics and feed values of the whole crop silage rice from paddy field and reclaimed paddy field. The heading dates of tested varieties was August 8 to August 30 in the paddy field, 1~2 days later than the reclaimed paddy field's August 6 to August 29. Plant height was in the range of 105~135 cm in paddy field, and 97~126 cm in reclaimed paddy field, respectively. The plant height of Mokyang was tallest in the paddy field, but Suwon 544 was tallest in the reclaimed paddy field. The number of tiller per plant of Nokyang was largest in the paddy field. Dry matter (DM) yield of whole crop rice ranged from 15.26 to $23.24MT\;ha^{-1}$ in the paddy field and 11.94 to $18.89MT\;ha^{-1}$ in the reclaimed paddy field. The highest DM yield in both fields was attained by Mokwoo. Comparing with the paddy field, the reclaimed paddy field achieved 78~84% in the DM yield. The crude protein content of varieties was 8.5 to 11.6% in the reclaimed tidal land and 6.7~8.7% in the paddy field. Neutral detergent fiber (NDF) of varieties in both fields ranged from 31.2 to 55.5%. Suwon 544 recorded the highest NDF contents in both fields. All varieties did not show any significant difference in acidic detergent fiber (ADF) which had values ranging from 22.3 to 33.2%. Total digestion nutrient (TDN) was more than 60% overall in both fields. Regarding TDN yield, Mokwoo recorded $16.54MT\;ha^{-1}$ in reclaimed tidal land and $12.69MT\;ha^{-1}$ in the paddy field, which showed the highest figure among the varieties. These results suggest the feasibility for cultivation of the whole crop silage rice in reclaimed paddy field, which showed 80% of the yield compared to paddy field, and implied that Mokwoo would show the most excellent yield and feed value.

Studies on the Forage Production and Utilization on Paddy Field in Korea (한국에 있어서 답리작을 이용한 양질 조사료 생산기술)

  • Seo, Sung;Yook, W.B.
    • Proceedings of the Korean Society of Grassland Science Conference
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    • 2002.09b
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    • pp.5-56
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    • 2002
  • The problems in the current domestic forage production were evaluated, and the prospective improvement was suggested in this paper. Grassland development in forest, production of high quality forages in upland and paddy land, efficient utilization of rice straw, development of new varieties of forages suitable for our environmental conditions and imported forages were described Among them, preferential production and utilization of forages using paddy field after rice harvest . should be enlarged for domestic supply of forages in Korea. Several studies were carried out to select the promising forage crops and barley cultivars for whole crop silage production, to determine productivity, nutritive value and production cost of forages produced in paddy field, and feeding effect of forages with Hanuwoo and milking cow for whole crop silage with forages produced in paddy field, 1999 to 2001, and also discussed restraint factors and activation plans for enlargement of forage production in paddy land. The promising forage crops in paddy field were rye and barley for Middle region, and rye, barley, early maturing Italian ryegrass and wheat for Southern region. The promising barley cultivars for whole crop silage in paddy field were Albori in Suwon, Keunalbori, Milyang 92, Saessalbori, and Naehanssalbori in Iksan, and Keunalbori, Albori, Naehanssalbori, and Saegangbori in Milyang, respectively. Silage production, quality and animal palatability of silage by trench and round bale were also compared. The production yields of whole crop barley silage(WBS) were 17,135kg as a fresh matter, and 6,011kg as a dry matter per ha, and the quality of WBS was 2∼3 grade, while that of rice straw silage was 4 grade as a farm basis. The production cost of WBS per kg was 83won as a fresh matter, and 238won as a dry matter. Feeding of WBS as forages on Hanwoo was very desirable for the improvement of live-weight gain, beef quality and farm income, particularly in growing stage of Hanwoo. Milk production and income were also increased, and feed cost was decreased by feeding of WBS. The daily voluntary intake of WBS in milking cow was 26.3kg as a fresh matter(DM 7.7kg) per head. Milk production when WBS was fed, was very similar to that of imported hay feeding such as Kentucky bluegrass or domestic corn silage. The issues to be solved in near future f3r stable forage production and supply in paddy land are sustainable livestock-forages policy, development & seed production of new varieties of barley, rye, Italian ryegrass and other promising forages, efficient demand & supply system of forages, solidification for mass production and utilization of forages, efficient application management of animal slurry on paddy field considering environmental agriculture/livestock industry, and break k development of bottleneck technique in production field. Domestic production & supply of high cost agricultural machine (round baler, wrapper, handler and so on), plastic wrapping film, and silage additives are also important.

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AC loss of HTS magnet for AMR refrigerator using magnetic field formulation and edge element in cylindrical coordinates

  • Kim, Seokho;Park, Minwon;Jeong, Sangkwon
    • Progress in Superconductivity and Cryogenics
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    • v.15 no.1
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    • pp.29-34
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    • 2013
  • AMR (Active Magnetic Regenerative) refrigerators require the large variation of the magnetic field and a HTS magnet can be used. The amount of AC loss is very important considering the overall efficiency of the AMR refrigerator. However, it is very hard to estimate the precise loss of the HTS magnet because the magnetic field distribution around the conductor itself depends on the coil configuration and the neighboring HTS wires interact each other through the distorted magnetic field by the screening current Therefore, the AC loss of HTS magnet should be calculated using the whole configuration of the HTS magnet with superconducting characteristic. This paper describes the AC loss of the HTS magnet by an appropriate FEM approach, which uses the non-linear characteristic of HTS conductor. The analysis model is based on the 2-D FEM model, called as 'magnetic field formulation and edge-element model', for whole coil configuration in cylindrical coordinates. The effects of transport current and stacked conductors on the AC loss are investigated considering the field-dependent critical current. The PDE model of 'Comsol multiphysics' is used for the FEM analysis with properly implemented equations for axisymmetric model.