• Title, Summary, Keyword: n-dimensional volume

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Investigation on Metal Transfer in GMA Welding through Dimensional Analysis (차원 해석을 통한 GMA 용접의 금속이행 현상에 관한 분석)

  • 최상균;유중돈
    • Journal of Welding and Joining
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    • v.17 no.1
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    • pp.62-70
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    • 1999
  • Since various parameters including the welding conditions and material properties are involved in metal transfer, it is difficult to figure out the effects of each parameter. In this study, dimensional analysis in performed to reduce the number of the parameters and to reveal the effect of each parameter on metal transfer. Dimensionless parameters are derived based on the inertia force and surface tension, and their contributions on metal transfer are estimated by analyzing the calculated results using the volume of fluid (VOF) method. Among several dimensionless parameters, $N_{SE}(=$\mu$_{0}I^{2}/d_{w}${\gamma}$)$ which represents the ratio of the electromagnetic force to surface tension, is found to be appropriate to describe metal transfer and estimate the transition current. Predicted results of transition current and drop size are in reasonably good agreements with available experimental date which show the validity of proposed dimensional analysis.

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The Volume Editor for the Virtual Surgery of Artificial Heart (인공심장 가상수술을 위한 체적 편집기)

  • Lee, D.H.;Kim, D.W.;Ahn, J.Y.;Kim, J.H.;Kim, N.K.;Min, B.G.
    • Proceedings of the KOSOMBE Conference
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    • v.1998 no.11
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    • pp.287-288
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    • 1998
  • The virtual surgery of Artificial Heart has focused on the simple fitting trial. But, as the processes of heart surgery being complex and detail, the requests of virtual surgery become more complex. One of the complex requests is volume editing. It may contain various editing functions: 3-dimensional cutting, registration, merging, splitting, inserting, deleting, translation and deformation. We have designed and implemented 3-dimensional volume editor that can be operated in Windows NT platform. With the results of this research, we can get convenient tools for the total virtual surgery system.

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Changes of Mooring Force due to Structural Modification of a Barge Ship (바지선 구조변경이 계류력 변화와 안정성에 미치는 영향)

  • Park, Jung-Hong;Kim, Kwang-Hoon;Moon, Byung-Young;Jang, Tak-Soo
    • The KSFM Journal of Fluid Machinery
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    • v.14 no.5
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    • pp.48-54
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    • 2011
  • Structural modifications of a ship may cause a fatal accident such as sinking and wrecking of ship. Especially, barge ship can be easily reconstructed to load more bulk cargo. In this study, for a real accident case, change of mooring force due to structural modification was analyzed to evaluate accident risk. A two dimensional dynamic model for the barge ship was constructed to compute mooring forces with related to floating motion. The equation of motion was established in Matlab code and buoyancy was calculated by using direct integration of submerged volume. The results showed that wind force, current force, and mooring force after rebuilding was approximately 4.3 kN, 14 kN, 1,561 kN respectively. The maximum force of mooring force according to the length of mooring cable were 1,614 kN at 30 m of mooring cable. Thus, an arbitrary modification of ship lead instability and unreliable result so that illegal rebuilding of ship should be avoided.

A Study of n Multigrid Finite-Volume Method for Radiation (다중격자 유한체적법에 의한 복사열전달 해석)

  • Kim, Man-Young;Do, Young-Byun;Baek, Seung-Wook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.1
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    • pp.135-140
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    • 2003
  • The convergence of finite volume method (FVM) or discrete ordinate method (DOM) is known to degrade for optical thickness greater than unity and large scattering albedo. The present article presents a convergence acceleration procedure for the FVM based on a full approximation storage (FAS) multigrid method. Among a variety of multigrid cycles, the V-cycle is used and the full multigrid algorithm (FMG) is applied to an analysis of radiation in irregular two-dimensional geometry. Solution convergence is discussed for the several cases of various optical thickness and scattering albedo. At small scattering albedo and optical thickness, there is no advantage to using the multigrid method for calculation CPU time. For large scattering albedo greater than 0.5 and optical thickness greater than unity, however, the multigrid method improves the convergence and the solution is rapidly obtained.

Numerical study on the flow characteristics in Air-conditioner duct of EMU (전동차 공조기 덕트 내의 유동특성에 관한 수치해석적 연구)

  • Kim Seung-Tech;Kim Sung-Jong;Park Geun-Soo;Park Hyung-Soon
    • Proceedings of the KSR Conference
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    • pp.345-350
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    • 2003
  • The inside of EMU is supplied with the cooling air from air-conditioner and the fresh air from exterior through the air-conditioner duct which is one of the air conditioning system. The shape of air-conditioner duct is a major factor in determining the air-conditioning efficiency, thermal comfort and energy efficiency. Therefore, this study is to understand the flow characteristics in the air-conditioner duct by three dimensional numerical simulation. The air-conditioner duct was calculated for the design volume flow rate, $2,726\;m^3/h/unit$. From the result of calculation and measurement, the velocity at diffuser outlet presented good agreement in general. [n this present study, the calculation was also performed for three volume flow rate(1,800, 2,200, 3,000 $m^3/h/unit$) and total pressure characteristic curve with volume flow rate was presented.

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Process Design, Fabrication, and Evaluation of Cold Drawn SUS304N Coil Wedge (SUS304N 코일 웨지 인발 공정의 설계, 제조 및 평가)

  • Jung, J.E.;Kim, S.J.;Bae, S.;Namkung, J.;Kim, S.M.;Kim, S.I.;Lee, K.S.
    • Transactions of Materials Processing
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    • v.28 no.4
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    • pp.212-218
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    • 2019
  • In this study, the first drawing die for the production of coil wedge is redesigned in order to enhance properties such as dimensional accuracy, dimensional uniformity, non-magnetism, and residual stress. The equivalent strain distribution is observed to be asymmetric at certain corners of the product and un-filling of material is also observed at the same location, based on the results of FEM simulation for the current drawing process. Additionally, a relatively huge amount of deformation is concentrated on the surface of the reference product leading to an increase in magnetic component and surface residual stress. After re-designing the cross-section of the first drawing step process conformed to relatively higher amount of reduction ratio, reduction of both surface residual stress and the volume fraction of magnetic component could be achieved for the finally-drawn coil wedge product.

Evaluation and Comparison of Myocardial Perfusion Defects in Patients with Early Breast Cancer Subjected to Different Radiation Simulation Techniques (조기유방암 환자에서 방사선 모의치료 방법의 차이에 따른 심근관류결손의 비교 평가)

  • Nam, Ji-Ho;Ki, Yong-Kan;Kim, Dong-Won;Kim, Won-Taek
    • Radiation Oncology Journal
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    • v.25 no.1
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    • pp.26-33
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    • 2007
  • [ $\underline{Purpose}$ ]: The aim of this study is to evaluate and compare the incidence and aspects of myocardial perfusion defects in patients who were subjected to either two-dimensional or three-dimensional simulation techniques for early left-sided breast cancer. The myocardial perfusion defects were determined from using single photon emitted computerized tomography (SPECT) myocardial perfusion images. $\underline{Materials\;and\;Methods}$: Between January 2002 and August 2003, 32 patients were enrolled in this study. The patients were diagnosed as having early (AJCC stage T1-T2N0M0) left-sided breast cancer and were treated with tangential irradiation after breast-conserving surgery and systemic chemotherapy. The patients were divided into two groups according to the type of simulation received: two-dimensional simulation using an X-ray fluoroscope simulator or three-dimensional simulation with a CT simulator. All patients underwent technetium-99m-sestamibi gated perfusion SPECT at least 3 years after radiotherapy. The incidence and area of myocardial perfusion defects were evaluated and were compared in the two groups, and at the same time left ventricular ejection fraction and cardiac wall motion were also analyzed. The cardiac volume included in the radiation fields was calculated and evaluated to check for a correlation between the amount of irradiated cardiac volume and aspects of myocardial perfusion defects. $\underline{Results}$: A myocardial perfusion defect was detected in 11 of 32 patients (34.4%). There were 7 (46.7%) perfusion defect cases in 15 patients who underwent the two-dimensional simulation technique and 4 (23.5%) patients with perfusion defects in the three-dimensional simulation group (p=0.0312). In 10 of 11 patients who had myocardial perfusion changes, the perfusion defects were observed in the cardiac apex. The left ventricular ejection fraction was within the normal range and cardiac wall motion was normal in all patients. The irradiated cardiac volume of patients in the three-dimensional simulation group was less than that of patients who received the two-dimensional simulation technique, but there was no statistical significance as compared to the incidence of perfusion defects. $\underline{Conclusion}$: Radiotherapy with a CT simulator (three-dimensional simulation technique) for early left-sided breast cancer may reduce the size of the irradiated cardiac volume and the incidence of myocardial perfusion defects. Further investigation and a longer follow-up duration are needed to analyze the relationship between myocardial perfusion defects and clinical ischemic heart disease.

TAH(Total Artificial Heart) Virtual Surgery Using Multi-Volume Visualizing Technique (다중 체적 가시 기법을 이용한 완전인공심장의 가상 수술)

  • Lee, D.H.;Kim, J.H.;Kim, N.K.;Min, B.G.
    • Proceedings of the KOSOMBE Conference
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    • v.1997 no.11
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    • pp.587-589
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    • 1997
  • The virtual surgical trial of TAH is very important in some points as follows. The chests of patients who is under heart-disease are various types of undefine form. It is hard to say that there exist the standard shape of TAH and the position to surgern. So, the virtual surgery system is very important in realizing TAH surgery of human. We have implemented virtual surgery system of TAH that supporting multi volume fitting trial. We have acquired CT images of patients with DICOM format. Each organ of patients was segmented in 2-dimensional CT images. 3-dimensional objects were made with marching cube algorithm and save as file in VRML format. Virtual fitting trial was performed on Cosmo-World; a VRML editor. The collision points of TAH with other organs were well observed. And the best position and angles were determined and saved or each case. We believed that this virtual surgery will be helpful in TAH surgery and TAH customizing.

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VOLUMES OF GEODESIC BALLS IN HEISENBERG GROUPS ℍ5

  • Kim, Hyeyeon
    • Journal of the Chungcheong Mathematical Society
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    • v.32 no.3
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    • pp.349-363
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    • 2019
  • Let ${\mathbb{H}}^5$ be the 5-dimensional Heisenberg group equipped with a left-invariant metric. In this paper we calculate the volumes of geodesic balls in ${\mathbb{H}}^5$. Let $B_e(R)$ be the geodesic ball with center e (the identity of ${\mathbb{H}}^5$) and radius R in ${\mathbb{H}}^5$. Then, the volume of $B_e(R)$ is given by $${\hfill{12}}Vol(B_e(R))\\{={\frac{4{\pi}^2}{6!}}{\left(p_1(R)+p_4(R){\sin}\;R+p_5(R){\cos}\;R+p_6(R){\displaystyle\smashmargin{2}{\int\nolimits_0}^R}{\frac{{\sin}\;t}{t}}dt\right.}\\{\left.{\hfill{65}}{+q_4(R){\sin}(2R)+q_5(R){\cos}(2R)+q_6(R){\displaystyle\smashmargin{2}{\int\nolimits_0}^{2R}}{\frac{{\sin}\;t}{t}}dt}\right)}$$ where $p_n$ and $q_n$ are polynomials with degree n.

Synthesis of Graphene Oxide Based CuOx Nanocomposites and Application for C-N Cross Coupling Reaction

  • Choi, Jong Hoon;Park, Joon B.
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.176.1-176.1
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    • 2014
  • Graphene has attracted an increasing attention due to its extraordinary electronic, mechanical, and thermal properties. Especially, the two dimensional (2D) sheet of graphene with an extremely high surface to volume ratio has a great potential in the preparation of multifunctional nanomaterials, as 2D supports to host metal nanoparticles (NPs). Copper oxide is widely used in various areas as antifouling paint, p-type semiconductor, dry cell batteries, and catalysts. Although the copper oxide(II) has been well known for efficient catalyst in C-N cross-coupling reaction, copper oxide(I) has not been highlighted. In this research, CuO and Cu2O nanoparticles (NPs) dispersed on the surface of grapehene oxide (GO) have been synthesized by impregnation method and their morphological and electronic structures have been systemically investigated using TEM, XRD, and XAFS. We demonstrate that both CuO and Cu2O on graphene presents efficient catalytic performance toward C-N cross coupling reaction. The detailed structural difference between CuO and Cu2O NPs and their effect on catalytic performance are discussed.

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