• 한국정밀공학회지
• /
• 제20권2호
• /
• pp.40-49
• /
• 2003

Ferrule is widely used as fiber optic connecters. In fiber-optic communications. the shape accuracy such as coaxiality and cylindricity of ferrule affects insertion loss. When coaxial grinding of ferrule supported by two pin. pin alignment and chucking accuracy are very important. In this research, the kinematic behavior of the ferrule centers are investigated in the case where the ferrule is chucked with the cone-shaped center pins and bail centers, With homogeneous coordinate transformation and numerical analysis, the obtained results are as follows: In the case of cone-type center, the alignment errors between center pins alone do not affect the rotation accuracy of ferrule. The alignment errors between center holes cause sinusoidal displacement of ferrule. And the maximum displacement of ferrule centers is proportional to the center pin angle. In the case of ball-type center, the displacements of ferrule centers has similar pattern as cone-type center, and the alignment errors art proportional to ball diameters.

• Imaging Science in Dentistry
• /
• 제45권2호
• /
• pp.109-115
• /
• 2015

Central odontogenic fibroma (COF) is a rare benign tumor that accounts for 0.1% of all odontogenic tumors. A case of COF (simple type) of the mandible in a four-year-old boy is described in this report. The patient showed asymptomatic swelling in the right inferior border of the lower jaw for one week. A panoramic radiograph showed a poorly-defined destructive unilocular radiolucent area. Cone-beam computed tomography showed expansion and perforation of the adjacent cortical bone plates. A periosteal reaction with the Codman triangle pattern was clearly visible in the buccal cortex. Since the tumor had destroyed a considerable amount of bone, surgical resection was performed. No recurrence was noted.

• Imaging Science in Dentistry
• /
• 제37권4호
• /
• pp.205-209
• /
• 2007

Purpose: To determine the physical properties of a newly developed cone beam computed tomography (CBCT). Materials and Methods: We measured and compared the imaging properties for the indirect-type flat panel detector (FPD) of a new CBCT and the single detector array (SDA) of conventional helical CT (CHCT). Results: First, the modulation transfer function (MTF) of the CBCT were superior to those of the CHCT. Second, the noise power spectrum (NPS) of the CBCT were worse than those of the CHCT. Third, detective quantum efficiency (DQE) of the indirect-type CBCT were worse than those of the CHCT at lower spatial frequencies, but were better at higher spatial frequencies. Although the comparison of contrast-to-noise ratio (CNR) was estimated in the limited range of tube current, CNR of CBCT were worse than those of CHCT. Conclusion: This study shows that the indirect-type FPD system may be useful as a CBCT detector because of high resolution.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 E
• /
• pp.1614-1616
• /
• 1998

Insulation performance of major components of prefabricated joint such as epoxy insulation unit and premolded rubber cone are guaranteed by material selection design and proper manufacturing. On the other hand insulation performance of the interfaces between the premolded rubber cone and the epoxy insulation unit and the cable insulation is maintained by keeping the premolded rubber cone to close contact with such insulation by spring. Electric characteristics of a interface depend on the contact pressure, but the required characteristics are assured so far as a proper contact pressure is maintained. In this report, the interfacial pressure by pressure sensors both in the early stage and after heating cycle were measured and the simulation by FEM program were presented. The comparison of these two results show that interfacial pressure could be controlled optimally by changing the spring length and lubricant state of the interface.

• 한국자동차공학회논문집
• /
• 제6권5호
• /
• pp.199-210
• /
• 1998

The skill that utilizes atomization of the liquid has been widely used in the field of industry and engineering. Though there are dozens of methods to make atomization, the pressure type injection nozzle is frequently used in washing of parts, pastourization and painting because it has relatively simple system. This study is to reveal the characteristics of atomizing formed by three different types of the pressure type injection nozzle. We measured velocity and diameter of droplet to compare and analyze characteristic of each nozzle. In case of velocity, atomization of hollow-cone nozzle is irregular than others and change of radial direction is especially large. Atomization of flat nozzle is nearly uniform. In case of diameter, atomization of hollow-cone nozzle is increased rapidly, as measurement point become more distant from the center of nozzle. Atomization of flat nozzle has the most fixed magnitude. Accordingly, full-cone nozzle can be used irrespective of the form of subject and hollow-cone nozzle is proper to the occasion to spray large and smooth subject. Also, flat nozzle is proper to the occasion to spray a part of subject and long groove.

• 동력기계공학회지
• /
• 제4권4호
• /
• pp.25-31
• /
• 2000

This paper represents the vector fields and three dimensional mean velocities in the X-Y plane of cone type swirl gas burner measured by using X-probe from the hot-wire anemometer system. This experiment is carried out at flowrate 350 and $450{\ell}/min$ respectively in the test section of subsonic wind tunnel. The vector plot shows that the maximum axial mean velocity component is focused in the narrow slits distributed radially on the edge of a cone type swirl burner, for that reason, there is some entrainment of ambient air in the outer region of the burner and the rotational flow can be shown in the inner region of the burner because mean velocity W is distributed about twice as large as mean velocity V due to inclined flow velocity ejecting from the swirl vanes of a cone type baffle plate of burner. Moreover, the mean velocities are largely distributed near the outer region of burner within $X/R{\fallingdotseq}1.5$, hence, the turbulent characteristics are anticipated to be distributed largely in the center of this region due to the large inclination of mean velocity and swirl effect.

• 구강회복응용과학지
• /
• 제32권1호
• /
• pp.32-37
• /
• 2016

목적: Cone beam형 전산화 단층영상(CBCT)을 이용하여 한국인의 하악 제2대구치에서 C형 근관계의 해부학적인 특징을 결정하기 위함이다. 연구 재료 및 방법: 824개의 영상을 평가하였다. 2013년 치과임플란트 진단 및 치료를 위해 CBCT를 찍은 환자를 대상으로 하였다. 711개의 하악 제2대구치가 조사되었다. 근관계의 형태는 변형된 Melton 분류를 이용하여 분류하였다. 결과: 711개의 하악 제2대구치에서 21.5%가 C형 근관계를 가졌다. 이러한 분포는 치아 위치에 따라 달라지지 않았다. 양쪽으로 존재하는 대구치에서 대부분의 C형 근관은 대칭적으로 나타났다. C형 근관에서 가장 흔한 형태는 orifice 부분에서 Melton's Type I (89%), 치근단부위에서는 Melton's Type III (83.8%) 이었다. C형 근관은 남성(13.9%)보다 여성(25%)에서 더 많이 나타났다. 결론: 한국인의 하악 제2대구치에서 C형 근관은 매우 높게 나타난다. 성공적인 C형 근관의 치료를 위해 근관계의 특성을 이해하는 것은 중요하다.

• Animal cells and systems
• /
• 제7권4호
• /
• pp.331-335
• /
• 2003

Vertebrates with different habitats have different proportions of visual cells, with the rod cells responding to scotopic vision and the cone cells responding to photopic and color vision in their retinas. The present work studied whether the kinds and arrangement patterns of the cone cells and interlocking morphology of the lens were related to the kind of preys and habitats in the genus Zacco. The retinas were observed by a light microscopy using H-E staining method and the interlocking formula of the lens fibers were investigated by a scanning electron microscopy. The interlocking formula of the lens fibers of Z. temmincki is an ' anchor and socket ' connection, and that of Z. platypus is a ' ball and socket ' connection. The cone cells of Z. platypus and Z. temmincki constituted compacted mosaic patterns of row type. Away from the center, the double and single cone cells gradually increased in diameter. Zacco temmincki had identical double cone cells and Z. platypus had non-identical double and single cone cells. The eyes of Z. temminckifeeding on a moving aquatic insects in relative limpid water and swift current of mid and upper stream have better resolution than that of Z. platypus feeding on mainly adhesive algae and some aquatic insects in slightly turbid water of mid stream.

• 한국전기전자재료학회논문지
• /
• 제32권3호
• /
• pp.207-212
• /
• 2019

A flat-type piezoelectric ceramic ultrasonic transmitter was successfully fabricated for application in acoustic devices with cone-free diaphragms. The transmitter, possessing a center frequency of 40.6 kHz, exhibited a higher displacement characteristic for a multilayer type compared with a single layer type. Surface roughness treatment of an Al elastic diaphragm influenced a slight increase (1.1 dB) in the sound pressure level (SPL) at $10V_{rms}$ due to the enlarged surface area. The fabricated multilayer piezoelectric ceramic ultrasonic transmitter showed increasing SPL with increasing input voltage, with a maximum SPL of approximately 123.6 dB at $10V_{rms}$. This implies a doubly increased SPL density of $3.6dB/mm^3$, superior to that of a commercial open-type transmitter with a cone.

• 한국지반신소재학회논문집
• /
• 제16권4호
• /
• pp.1-11
• /
• 2017

본 연구에서는 헬리컬 파일의 관입시간과 극한하중에 관한 연구를 진행하고자 1/6 축소모형 실험을 진행하였다. 균질한 상대밀도의 사질토 지반을 형성하기 위하여 강사법을 사용하였다. 실험 조건으로 헬리컬 파일의 나선형 원판(heilx plate) 간격을 50mm와 150mm 두 Type으로 제작하였고, 헬리컬 파일의 회전관입 시 회전속도를 15rpm과 30rpm으로 진행하였다. 관입 완료된 헬리컬 파일에 콘 장비를 항타하여 관입하였다. 콘 장비 관입으로 헬리컬 파일의 극한하중 증가와 폐색의 정도를 확인 할 수 있었다. 위의 실험 결과를 토대로 헬리컬 파일의 관입시간은 "회전속도 30rpm-나선형 원판 간격 50mm"에서 단축 되었고, 극한하중은 "회전속도 30rpm-나선형 원판 간격 150mm-콘 장비 유"인 조건에서 높은 극한하중을 보였다.