• Title/Summary/Keyword: 원추

Search Result 530, Processing Time 0.024 seconds

Abutment Sinking and Fitness of Conical Internal Connection Implant System according to Loading Condition (하중조건에 따른 원추형 내측연결 임플랜트 시스템에서 지대주 침하 및 적합에 관한 연구)

  • Lee, Hal-La;Kim, Hee-Jung;Son, Mee-Kyoung;Chung, Chae-Heon
    • Journal of Dental Rehabilitation and Applied Science
    • /
    • v.24 no.1
    • /
    • pp.77-89
    • /
    • 2008
  • The purpose of this study was to evaluate internal conical abutment sinking and fitness according to the loading condition. In this study, Alloden implant fixture and two abutment(conventional, FDI) systems were used. Each abutment was applied 1 time of finger force, 3 times of malleting force, 5 times of 20kg and extra several times to the fixture until the amount of abutment singking showed no change. Then, the length of abutment to fixture which was binding lightly with no pressure state was measured by Vernier caliper. After loading application, the length was remeasured and the amount of sinking was calculated. The implant was buried in unsaturated polyester (Epovia, Cray Valley Inc. Korea) for making a comparison between the change of length and fitness of abutment-fixture connection part. Then All samples were cross-sectioned with high speed precision cut-off(accutom-5, Struers, Denmark). Finally, The result were observed and analyzed using FE-SEM (field emission scanning electron microscopy).

Study in Radius of Corneal Curvature of university Students with Keratometer (RGP 렌즈 착용한 대학생의 각막곡률반경 측정)

  • Kim, Chang-Sik;Ryu, Kwang-Min
    • Journal of Korean Ophthalmic Optics Society
    • /
    • v.11 no.3
    • /
    • pp.181-185
    • /
    • 2006
  • The measurement of the radius of corneal curvature with keratometer was followed in 184 university students who wearing RGP contact lens and consisted of female(167), male(17) and keratoconus patients(3). Overall mean value in the radius of corneal curvature is 7.77mm, and right and left eyes is appeared the same mean value. Overall mean value in horizontal and vertical is 7.88mm and 7.65mm. Horizontal means is larger than vertical means by 0.22mm of the all female and male students. Male's mean value in the radius of corneal curvature(7.84mm) is larger than female's by 0.08mm, and right and left eyes is also the same mean value. Keratoconus patients' mean value in the radius of corneal curvature(6.86mm) is smaller than others students by 0.91mm.

  • PDF

Preliminary Design for Axisymmetric Supersonic Inlet using Conical Flow Solution and Optimization Technique (원추 유동 해와 최적화 기법을 이용한 축대칭 초음속 흡입구의 예비 설계)

  • 정석영
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.34 no.9
    • /
    • pp.11-19
    • /
    • 2006
  • Design program was developed to determine the external shape of the supersonic axisymmetric inlet by combining conical flow solver and approximation technique of conical shock with gradient-based optimization algorithm. Inlet designs were carried out under various operation conditions through optimization with respectively two object functions which consist of pressure recovery and cowl drag and with constraints about shock position, cowl shape, and minimum throat area. New object function consisting of pressure recovery and drag of the external cowl was proposed and the optimized shapes from new object function were compared to the ones from the old object function which maximize only the pressure recovery. Through computations of inviscid and turbulent flow, was tested performance of the design program and performance estimated in design program agreed well with computation results for inlets designed under various flight conditions.

Effect of annular phase apodizer on the read-out signal in an optical disc system (환형 위상변조 Apodizer가 광학디스크 시스템의 재생신호에 미치는 영향)

  • jeong, Ho;Chung, Chang-Sub;Park, Seong-Jong
    • Korean Journal of Optics and Photonics
    • /
    • v.12 no.4
    • /
    • pp.270-275
    • /
    • 2001
  • We have studied effects of annular phase apodizer and bump shapes on the read-out signal in an optical disc system, using scalar diffraction theory. In order to detennine the optimum parameters of annular phase apodizer which will minimize the influence of spherical aberration, we defined WR as the ratio between the maximum wavefront aberration and some absolute value of wavefront aberration at any position r in the pupil. A cylindric bump, a semi-conic bump and a conic bump were$.$ also considered as different types of bump shape. As the radius and shape of bump varies, the read-out signal from an optical disc system with an annular phase apodizer was similar to that from an optical disc system without apodizer. When spherical aberration increases, the maximum read-out signal of an optical disc system with an annular phase apodizer and minimum bump radii giving read-out signal higher than 0.6 rarely varied. Especially, the optimum parameters at $W_R$ = 0.4 , 0.6 gave the most compensated effect of a spherical aberration.ration.

  • PDF

Frequency Characteristics of the Return Loss of a Broadband Double-Cone Antenna with Shorting Plate (단락판을 갖는 이중 원추형 광대역 안테나의 반사손실 특성)

  • Jang, Seung-Hoon;Hong, Deok-Gi;Kim, Hyo-gyun;Jung, Sung-Woo;Kim, Ki-Chai
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.27 no.2
    • /
    • pp.101-107
    • /
    • 2016
  • This paper presents the characteristics of a double-cone broadband antenna with compact and three-dimensional structure that can be used in UWB system. The theoretical analysis is conducted using a finite difference time domain(FDTD) method. The parameters are the radius, a height of broadband double-cone antennas with shorting plate, and the number of plates on a ground plane. This paper examines influence of structural parameters on return loss. The results show that a condition for an optimum structure of broadband double-cone antennas with shorting plate exists. It also shows that the broadband double-cone antennas with shorting plate have radiation patterns similar to those of a dipole antenna. To verify the theoretical analysis, computed results are compared to experimental results.

Correlation between Casagrande Test and Fall Cone Test Methods and their Applicability in Ground Improvement (카사그란데방법과 원추관입시험방법의 상관관계와 지반개량제의 적용성에 대한 연구)

  • Ko, Kun-Woo;Yeo, Dong-Jun;Kim, Kyung-Min;Lee, Byung-Suk
    • Journal of the Korean Geotechnical Society
    • /
    • v.39 no.2
    • /
    • pp.5-17
    • /
    • 2023
  • In this study, a classification and uniaxial compression test of soil was conducted on 15 collapsed sites to use ground improvement with excellent protection effect owing to the increase of localized heavy rain in Korea. The Casagrande method and fall cone test were performed on the field soil to derive an expression for comparing liquid limit and plastic limit values, soil classification, and correlation between each other. By deriving the optimal mixing ratio of the ground improvement agent using uniaxial compressive strength for each soil classification, the classification of the fine-grained soil was not clear owing to the proficiency difference and test error. However, after classifying using the fall cone test, it was possible to suggest a clear optimal mixing ratio.

Liquid and Plastic Limits of Cohesive Soil by Static and Dynamic Test Methods and Testers (정적 및 동적시험법과 실험자에 따른 점토의 액·소성한계)

  • Kim, Chan-Kee;Yeo, Jin-Soo;Moon, Young-Seog;Park, Hyung-Yeol;Kim, Tae-Hyung
    • Journal of the Korean Geotechnical Society
    • /
    • v.33 no.3
    • /
    • pp.5-15
    • /
    • 2017
  • In this study, the liquid and plastic limit tests were conducted on Paju clay with Casagarande method (dynamic) and the fall cone test method (static) to find out the effects of test methods and testers on their values. Six testers, who already have the experience of test, participated. As a results of liquid limit tests, the fall cone test method showed 4% smaller liquid limit compared to the value determined by Casagrande method. As the number of tests increased, the fall cone test method showed less variation between testers and the variation range of level of proficiency was also more stable. In the case of one point method, the liquid limit determined by the fall cone test method varied with smaller range compared to the Casagrande. Consequently, the fall cone test provided more stable liquid limit value than that of Casagrande method. For the results of plastic limit tests, there were no difference between Casagrande method and the fall cone test unlike liquid limit test results. In other words, both methods showed that plastic limit reached the average value as the number of tests increased, and the tendency level of proficiency also showed to get better.

Intramedullary Spinal Lesions Involving the Conus Medullaris: MR Imaging Features for Differential Diagnosis (척수 원추부에 발생한 척수내 병변: 자기공명영상을 이용한 감별 진단)

  • Eun, Na Lae;Ahn, Sung Jun;Chung, Tae-Sub;Cho, Yong-Eun;Kim, Keun Su;Kuh, Sung-Uk;Suh, Sang Hyun
    • Investigative Magnetic Resonance Imaging
    • /
    • v.18 no.2
    • /
    • pp.144-150
    • /
    • 2014
  • Purpose : Intramedullary spinal lesions in the conus medullaris (CM), including tumors and vascular lesion, are rarely reported. We reported various MR features of intramedullary spinal cord lesions involving the CM including ependymoma, hemangioblastomas, dermoid cyst, ventriculus terminalis and spinal AVF and tried to discuss them for differential diagnosis. Materials and Methods: Six patients (male: female = 4:2, mean age = 44.3 year old) were enrolled from the clinical database of our institute from 2004 to 2010 and their radiological images and clinical symptoms were reviewed retrospectively. All patients had taken initial and postoperative MRI with contrast enhancement using gadopentate dimeglumine (Gd-DTPA). These images were analyzed by tumor size, location, signal intensity relative to the spinal cord, vascular flow voids, syrinx or cyst, edema and enhancement pattern. Results: Contrast enhancement was seen in all intramedullary masses. An eccentric enhancing nodule was noted in two hemangioblastomas and unusual peripheral rim enhancement with septation was seen in ventriculus terminalis. Patchy enhancement of the CM was observed in spinal arteriovenous fistula (AVF). Extensive cord edema adjacent to the intramedullary lesions was seen in four cases and syrinx was noted in three cases. Vascular signal voids were found in two hemangioblastomas and one spinal AVF. Conclusion: In evaluation of intramedullary spinal lesions in the CM, it is necessary to consider these unusual MR findings and discriminate various pathologies with prudence and caution.