• Title, Summary, Keyword: 역나선

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위암의 진단방법으로 CT스캔의 역할

  • 조준식
    • Journal of Gastric Cancer
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    • v.2 no.4
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    • pp.175-179
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    • 2002
  • 위암의 진단에서 CT스캔은 수술 전 병기결정이나 수술 후 추적검사에서 필수적인 검사방법으로 인정을 받고 있고, 보편적으로 가장 많이 유용되고 있다. 그러나 나선식 CT를 사용하고 여러 가지 스캔방법의 개선에도 불구하고, 인접장기로의 직접침윤, 작은 크기의 간전이의 발견, 정상 크기범위의 림프절에서 전이의 발견, 양성 림프절과 전이의 감별, 복막전이에 대한 평가에서 지금까지의 보고들은 만족스러운 결과를 얻지 못하고 있으며 CT의 한계점으로 남아 있다. 그러나 최근에는 나선식 CT보다 더 빠른 시간내 더 얇은 두께의 절편을 얻을 수 있고, 이를 이용하여 관상면 및 시상면으로 정밀하게 재구성하거나 3D영상을 얻을 수 있는 다검출식 나선식 CT가 개발되어 사용되고 있고, CT 진단의 정확도를 높일 것으로 기대한다.

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A study on the characteristics of wide bandwidth connector for automotive communication (자동차 통신을 위한 광대역 커넥터 특성 연구)

  • Kim, Byeong-Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.1
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    • pp.33-38
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    • 2012
  • In this paper, helical wave wire have been proposed as the vehicle connector for the wireless access in vehicular environments(5.925GHz) communication. This helical slow wave connector is design by considering the properties of critical parameter like helical mean radius, helical pitch, helical wire radius and distance of helical wire to shield. The design simulation and results can be used to determine the most suitable helical wave wire dimensions for vehicle communication connector. The optimized WAVE connector inserted the helical wave wire has insertion loss less than -0.76dB at 5.925GHz. It provides 31% of insertion loss with good performance. Therefore, the simulated results can be effectively used for optimum design of high frequency connector for vehicle communication.

Stiffness Analysis of a Low-DOF Parallel Manipulator using the Theory of Reciprocal Screws (역나선 이론을 이용한 저자유도 평행구조 기구의 강성해석)

  • Kim, Han-Sung
    • Proceedings of the KSME Conference
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    • pp.573-578
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    • 2004
  • This paper presents a methodology for the stiffness analysis of a low-DOF parallel manipulator. A low-DOF parallel manipulator is a spatial parallel manipulator which has less than six degrees of freedom. The reciprocal screws of actuations and constraints in each leg can be determined by making use of the theory of reciprocal screws, which provide information about reaction forces due to actuations and constraints. When pure force is applied to a leg, the leg stiffness is modeled as a linear spring along the line. For pure couple, it is modeled as a rotational spring about the axis. It is shown that the stiffness model of an F-DOF parallel manipulator consists of F springs related to actuations and 6-F springs related to constraints connected from the moving platform to the base in parallel. The $6{\times}6$ Cartesian stiffness matrix is obtained, which is the sum of the Cartesian stiffness matrices of actuations and constraints. Finally, a 3-UPU parallel manipulator is used as an example to demonstrate the methodology.

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Stiffness Analysis of a Low-DOE Parallel Manipulator using the Theory of Reciprocal Screws (역나선 이론을 이용한 저자유도 병렬형 기구의 강성해석)

  • Kim Han Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.5
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    • pp.680-688
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    • 2005
  • This paper presents a methodology for the stiffness analysis of a low-DOF parallel manipulator. A low-DOF parallel manipulator is a spatial parallel manipulator which has less than six degrees of freedom. The reciprocal screws of actuations and constraints in each leg can be determined by making use of the theory of reciprocal screws, which provide information about reaction forces due to actuations and constraints. When pure farce is applied to a leg, the leg stiffness is modeled as a linear spring along the line. For pure couple, it is modeled as a rotational spring about the axis. It is shown that the stiffness model of an it_DOF parallel nipulator consists of F springs related to actuations and 6-F springs related to constraints connected from the moving platform to the base in parallel. The 6x f Cartesian stiffness matrix is derived, which is the sum of the Cartesian stiffness matrices of actuations and constraints. Finally, the 3-UPU, 3-PRRR, and Tricept parallel manipulators are used as examples to demonstrate the methodology.

Stiffness Analysis of a Low-DOF Planar Parallel Manipulator (저자유도 평면 병렬형 기구의 강성 해석)

  • Kim, Han-Sung
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.8
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    • pp.79-88
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    • 2009
  • This paper presents the analytical stiffness analysis method for a low-DOF planar parallel manipulator. An n-DOF (n<3) planar parallel manipulator to which 1- or 2-DOF serial mechanism is connected in series may be used as a positioning device in planar tasks requring high payload and high speed. Differently from a 3-DOF planar parallel manipulator, an n-DOF planar parallel counterpart may be subject to constraint forces as well as actuation forces. Using the theory of reciprocal screws, the planar stiffness is modeled such that the moving platform is supported by three springs related to the reciprocal screws of actuations (n) and constraints (3-n). Then, the spring constants can be precisely determined by modeling the compliances of joints and links in serial chains. Finally, the stiffness of two kinds of 2-DOF planar parallel manipulators with simple and complex springs is analyzed. In order to show the effectiveness of the suggested method, the results of analytical stiffness analysis are compared to those of numerical stiffness analysis by using ADAMS.

Role of CT Scan in Gastric Cancer as a Diagnostic Tool (위암의 진단방법으로 CT스캔의 역할)

  • 조준식
    • 대한위암학회:학술대회논문집
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    • pp.11-18
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    • 2002
  • 위암의 진단에서 CT스캔은 수술 전 병기결정이나 수술 후 추적검사에서 필수적인 검사방법으로 인정을 받고 있고, 보편적으로 가장 많이 유용되고 있다. 그러나 나선식 CT를 사용하고 여러 가지 스캔방법의 개선에도 불구하고, 인접장기로의 직접침윤, 작은 크기의 간전이의 발견, 정상 크기범위의 림프절에서 전이의 발견, 양성 림프절과 전이의 감별, 복막전이에 대한 평가에서 지금까지의 보고들은 만족스러운 결과를 얻지 못하고 있으며 CT의 한계점으로 남아 있다. 그러나 최근에는 나선식 CT보다 더 빠른 시간내 더 얇은 두께의 절편을 얻을 수 있고, 이를 이용하여 관상면 및 시상면으로 정밀하게 재구성하거나 3D영상을 얻을 수 있는 다검출식 나선식 CT가 개발되어 사용되고 있고, CT 진단의 정확도를 높일 것으로 기대한다.

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나선 은하의 화학적 진화 : 우리 은하의 초기 질량함수와 별탄생율

  • An, Hong-Bae;Im, Jeong-Ae;Gang, Yong-Hui
    • Publications of The Korean Astronomical Society
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    • v.6 no.1
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    • pp.1-15
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    • 1991
  • 원반 및 해일로의 이중역 (two-zone) 모형을 바탕으로하여 나선은하의 화학적 진화 모형을 만들었다. 모형의 검증을 위하여 구체적인 수치계산을 수행하고 그 결과를 태양 부근에서 관측된 중원소 분포 등, 화학적 진화와 관련된 제반 관측 사실과 비교함으로써 은하계의 진화를 추론하였다. 모형의 수치계산 결과에 의하면 나선은하의 화학적 진화는 헤일로외 붕괴 과정과 별탄생율에 크게 의존하며, 원반의 초기질량함수와 별탄생율에 따라 서로 다른 양상을 보인다. 태양 부근 원반의 중원소 분포 등을 성공적으로 설명할 수 있는 진화 모형에서, 별탄생율은 가스의 질량 또는 표면밀도의 멱승에 비례하거나 시간에 따라 단조 감소하는 지수함수로써 표현되며, 초기질량함수는 헤일로에서는 다양한 형태의 함수 모두로써 가능하지만, 원반의 경우에는 시간에 따라 변화하는 질량함수를 채택하여야 한다. 우리 은하의 헤일로의 고속붕괴 모형에서는 시간에 따라 지수함수로 변화하는 별탄생율이 관측과 부하되지만, 반면 저속붕괴의 경우에는 가스 질량의 멱함수로 표현되는 별탄생율이 관측과 부합된다.

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Power Noise Suppression Methods Using Bead with Spiral Resonator (비드와 나선형 공진기를 이용한 전원 노이즈 저감 방안 연구)

  • Chung, Tong-Ho;Kang, Hee-Do;Yook, Jong-Gwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.2
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    • pp.152-160
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    • 2013
  • In this paper, to the aim of wideband SSN(Simultaneous Switching Noise) suppression characteristic, investigation of spiral resonator are used in conjunction with bead which is commonly used for noise suppression method. Bead works effectively to suppress the power noise up to the first harmonic of fundamental frequency, 0.8 GHz, and spiral resonator suppress noise well in the frequency range of SRF(Self Resonance Frequency) which is inversely proportional to the length of spiral. Thus, when bead used in conjunction with a spiral the noise suppression characteristic is determined by the one of higher impedance element of the two in the frequency range and achieves more broadband filtering characteristic. The case for using 22 nH bead turns out 4.8, 2.0, 0, and, 0.6 dB, and the case for using 22 nH bead in conjunction with 3-turns spiral achieves more wideband characteristic of 9.5, 8.3, 6.1, and 9.9 dB power noise suppression performances at the first, second, third, and fourth harmonics, respectively. The peak-to-peak voltage levels decrease from 76 mV to 56 mV using 22 nH bead, and the level decrease rapidly to 34 mV when using in conjunction with bead and 3-turn spiral. Thus more wideband SSN suppression characteristic can be achieved using bead with spiral.

A Study on the New Manager Model in Service Economy Era (서비스경제시대의 신경영자 모델 연구)

  • Kim, Hyunsoo
    • Journal of Service Research and Studies
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    • v.10 no.3
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    • pp.1-22
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    • 2020
  • This study was conducted to derive the new manager model in service economy era. It was logically explained that the modern economic society is different from the existing economic society, the modern organization that is the subject of management is different from the existing organization, and the tasks required by management are different from the existing tasks. It suggested the managerial model required for new managers. According to the proposed manager's model, the tasks required of new managers and essential qualities as managers to perform the tasks were presented. It suggested the role model that managers with required qualities should play. The role of a manager who becomes one with customers, the role of a manager who controls even his irrationality, the role of a manager who combines discernment and indiscriminateness, a flexible leadership role that combines charisma and tenderness, an administrator role that embraces regulations and non-regulations, and vision and non-vision. We derived the role of a manager who manages management, and a manager role model that utilizes both competition and non-competition. The managers engage in two opposing roles and perform management activities in a spiral dialectical cycle that develops while resolving the contradictions of each role. The method of embracing the two opposing parties internally and externally and the dialectical management execution process according to the change of the space-time axis were presented by borrowing the models of The Book of Change. Future research needs an empirical analytical study on this new Model. There is a need for studies that expand this study and develop it into a practical model and verify it in an analytical way.