• 제어로봇시스템학회논문지
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• 제8권3호
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• pp.208-219
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• 2002

A novel measurement method to obtain the 6-DOF motions of arbitrary rigid bodies is proposed in this paper. The method adopts a specially fabricated mirror called 3-facet mirror, which looks like a triangular pyramid haying an equilateral cross-sectional shape. The mirror is mounted on the objects to be measured, illuminated by a laser beam having circular profile, and reflects the laser beam in three different directions. Three PSDs(position sensitive detector) detect the three beams reflected by the mirror, respectively. From the signals of the PSDs, we can calculate the 3-dimensional position and orientation of the 3-facet mirror, and thus enabling us to determine the 3-dimensional position and orientation of the objects. In this paper, we model the relationship between the 3-dimensional position and orientation of an object in motion and the outputs of three PSDs. A series of experiments are performed to demonstrate the effectiveness and accuracy of the proposed method. The experimental results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects and provide resonable measurement accuracy.

• Journal of Korean Neurosurgical Society
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• 제58권4호
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• pp.341-345
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• 2015

Objective : To measure the orientation of the facet joints of cervical spine (C-spine) segments in the sagittal plane, known as the pedicle-facet (P-F) angle, and to use these measurements to evaluate the relationship between the P-F angle and the amount of vertebral anterolisthesis in patients with degenerative cervical spondylolisthesis (DCS). Methods : A retrospective case-control study was performed including 30 age- and sex-matched patients with DCS and 30 control participants. Anterior-posterior and lateral view radiographs of the C-spine were obtained in a standing position. The P-F angle at all cervical levels and the amount of anterolisthesis at C4-5 were measured from lateral view plain radiographs. Results : The P-F angles at C4-5 were $141.14{\pm}7.14^{\circ}$ for the DCS group and $130.53{\pm}13.50^{\circ}$ (p=0.012) for the control group, and at C5-6 were $137.46{\pm}8.53^{\circ}$ for the DCS group and $128.53{\pm}16.01^{\circ}$ for the control group (p=0.001). The mean P-F angle at C4-5 did not correlate with the amount of anterolisthesis (p=0.483). The amount of anterior slippage did correlate with age (p<0.001). Conclusion : The P-F angle was intrinsically higher at C4-5, compared to C5-6, in both the DCS and control groups, which might explain the increased likelihood for anterolisthesis of C4. Higher P-F angles in the DCS group may be a predisposing factor to slippage. The P-F angle may interact with age to increase incidence of anterolisthesis with increasing age.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.50-50
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• 2000

In this paper, a new measuring system is :proposed which can measure the fine 6-DOF displacement of rigid bodies. Its measurement principle is based on detection of laser beam reflected from a specially fabricated mirror that looks like a triangular pyramid having an equilateral cross-sectional shape. The mirror has three lateral reflective surfaces inclined 45$^{\circ}$ to its bottom surface. We call this mirror 3-facet mirror. The 3-facet mirror is mounted on the object whose 6-DOF displacement is to be measured. The measurement is operated by a laser-based optical system composed of a 3-facet mirror, a laser source, three position-sensitive detectors(PSD). In the sensor system, three PSDs are located at three corner points of a triangular formation, which is an equilateral triangular formation tying parallel to the reference plane. The sensitive areas of three PSDs are oriented toward the center point of the triangular formation. The object whose 6-DOF displacement is to be measured is situated at the center with the 3-facet mirror on its top surface. A laser beam is emitted from the laser source located at the upright position and vertically incident on the top of the 3-fatcet mirror. Since each reflective facet faces toward each PSD, the laser beam is reflected at the 3-facet mirror and splits into three sub-beams, each of which is reflected from the three facets and finally arrives at three PSDs, respectively. Since each PSD is a 2-dimensional sensor, we can acquire the information on the 6-DOF displacement of the 3-facet mirror. From this principle, we can get 6-DOF displacement of any object simply by mounting the 3-facet mirror on the object. In this paper, we model the relationship between the 6-DOF displacement of the object and the outputs of three PSDs. And, a series of simulations are performed to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.9-13
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• 2017

This study presents a simple method to control the seed orientation which leads to the various growth characteristics of a single grain REBCO (RE: rare-earth elements) bulk superconductors. Seed orientation was varied systematically from c-axis to a-axis with every 30 degree rotation around b-axis. Orientations of a REBCO single grain was successfully controlled by placing the seed with various angles on the prismatic indent prepared on the surface of REBCO powder compacts. Growth pattern was changed from cubic to rectangular when the seed orientation normal to compact surface was varied from c-axis to a-axis. Macroscopic shape change has been explained by the variation of the wetting angle of un-reacted melt depending on the interface energy between $YBa_2Cu_3O_{7-y}$ (Y123) grain and melt. Higher magnetic levitation force was obtained for the specimen prepared using tilted seed with an angle of 30 degree rotation around b-axis.

• 대한후두음성언어의학회지
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• 제20권2호
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• pp.126-130
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• 2009

Arytenoid motion has long been recognized as complex. Misunderstandings about the specifics of arytenoid motion remain prevalent. The resultant misunderstandings have led to erroneous or suboptimal clinical approaches to the treatment of vocal fold immobility. A thorough understanding of the anatomy of the arytenoid and cricoid cartilages, the cricoarytenoid joint, and related ligaments, muscles, and other structures is essential in order to fully understand laryngeal motion disorders. Arytenoid motion occurs in three directions. Movements involving a change anteriorly and posteriorly, as well as vertically, are due to the revolving or pitchlike motion of the arytenoid along the minor axis of the cricoid's elliptically shaped facet. The medial and lateral movements are due to the orientation of the arytenoid which in turn is determined by the forward, lateral, and inferior inclination of the cricoid-arytenoid facet. During adduction it is the outward angulation of the vocal process from the body of the arytenoid that allows the entire length of the vocal proceses to approximate one another and to have this meeting occur at the proper vertical height.

• 한국세라믹학회지
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• 제33권7호
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• pp.761-770
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• 1996

Silicon carbide (SiC) films were deposited by low pressure chemical vapor deposition (LPCVD) using MTS (CH3SICl3) in a hydrogen atmosphere onto graphite substrates. Depletion effects of reactants which usually occur in the hot wall horizaontal reactor were increased with deposition temperature and pressure. Below 50 torr of total pressure (111) plane was preferenctially grown irrespectrive of deposition temperature and deposition site. Over 50 torr of total pressure however (220) plane was preferentially deposited under 130$0^{\circ}C$ and at inlet site. The surface morphologies of SiC films were uniform at all deposition sites under low pressure but greatly changed with pressure. It shows that a facet structure which was formed above 125$0^{\circ}C$ played an important role in the changed of preferred orientation and surface roughness.

• 대한정형외과학회지
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• 제56권5호
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• pp.413-418
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• 2021

목적: 경추에서 후관절 비대칭성이 후관절 퇴행과 추간판 퇴행에 미치는 영향력에 대해 조사하고자 한다. 대상 및 방법: 2017년 1월부터 2018년 12월까지 총 100명의 환자를 대상으로 경추 제5-6번의 후관절 비대칭성을 후향적으로 분석하였다. 컴퓨터 단층촬영(computed tomography, CT)에서 수평면, 시상면, 관상면에 대한 양쪽 후관절 각도를 측정하였으며 자기공명영상 촬영(magnetic resonance imaging, MRI) 및 CT에서 후관절의 퇴행을 등급 체계를 이용하여 평가하였다. 추간판 퇴행은 MRI 시상면, 수평면에서 5등급으로 나누어 평가하였다. 좌우 후관절 각도 차이가 7도 이상인 경우를 비대칭군으로, 7도 미만인 경우를 대조군으로 구분하였다. 결과: 환자의 평균 나이는 비대칭군에서 55.44±12.3세(31-81세)였으며 대조군에서는 55.66±10.7세(32-76세)였다. 비대칭군의 경우 남성이 32명, 여성이 18명이었고 대조군에서는 남성이 24명, 여성이 26명이었다. 관절 퇴행은 비대칭군에서 24명(48.0%), 대조군에서 14명(28.0%)으로 측정되었으며 유의한 차이를 보였다(p=0.037). 추간판 퇴행은 비대칭군에서 29명(58.0%), 대조군에서 17명(34.0%)으로 측정되었으며 유의한 차이를 보였다(p=0.005). 다변량 분석 결과상 후관절 비대칭성이 후관절 퇴행과 추간판 퇴행에 영향을 주는 인자였다. 결론: 경추 제5-6번에서 경추 후관절 퇴행 및 추간판 퇴행이 유의하게 많이 발생하였으며 후관절 비대칭성이 후관절 퇴행 및 추간판 퇴행에 영향을 주는 인자로 생각된다.

• 한국결정학회지
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• 제12권3호
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• pp.171-176
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• 2001

(100), (111), (211)CdZnTe 기판 및 (100)GaAs 기판위에 HgCdTe 박막을 MOVPE 법으로 성장하였다. 기판의 방위에 따라 성장된 박막의 표면형상, 전기적 특성, 결정성 및 조성의 변화를 분석하였다. (111) CdZnTe 기판 위에서는 3차원적인 facet 형태의 성장이 일어났다. (100) CdZnTe 기판 위에 성장된 HgCdTe 박막의 경우 DCX반치폭은 55arcsec 정도로 125 arcsec의 반치폭을 보인 (100) GaAs에 비하여 우수한 결정성을 나타내었다. 그러나 전기적인 특성은 GaAs 기판의 경우, 이동도가 높은 n-형 전도성을 보였으나 CdZnTe 기판을 사용한 경우에는 10/sup 16/㎤ 이상의 운반자 농도를 갖는 p-형 전도성을 나타내었다.

• 한국초전도ㆍ저온공학회논문지
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• 제20권3호
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• pp.5-10
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• 2018

This study presents that various grain boundary junctions are prepared by controlling the seed orientation combined with an artificial hole in a melt process REBCO bulk superconductor. Large grain YBCO superconductors have been fabricated with various grain boundary junctions that the angle between the grain boundary and the <001> axis of Y123 crystal is $0^{\circ}$, $30^{\circ}$ and $45^{\circ}$, respectively. The presence of the artificial hole is beneficial for the formation of clean grain boundary junction and single peak trapped magnetic field profiles have been obtained. Artificial hole makes two growth fronts meet at a point on a periphery of the artificial hole. The presence of artificial hole is not likely to affect on the distribution of Y211 particles. The newly formed <110> facet lines are explained by the formation of new Y123/liquid interface with (010) crystallographic plane.

• 한국세라믹학회지
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• 제34권2호
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• pp.131-138
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• 1997

희석기체로써 Ar 및 H2를 사용하여 MTS(CH3SiCl3)를 원료물질로 한 탄화규소막을 흑연 기판 위에 화학증착시켰다. 본 연구는 증착온도 130$0^{\circ}C$, 총압력은 10 torr 및 MTS와 원료 운반기체의 총유량은 100 sccm으로 일정하게한 상태에서, 각 희석기체의 첨가에 따른 성장거동의 변화를 고찰하고자 하였다. 증착속도는 희석기체와 상관없이 첨가량이 200sccm일 때 최대값을 갖는 모양을 보였으나, Ar을 첨가할 때가 H2에 비해 더 빠른 증착속도를 나타냈다. 이러한 증착속도 특성은 전체 증착속도가 물질전달 율속단계에 있을 때, 각 희석기체의 첨가에 따라 변화되는 경막 두께(boundary layer thickness) 및 원료물질 농도의 상관관계에 기인한다고 여겨졌다. 우선배향성은 Ar의 경우 모든 첨가량의 범위에서 (220)면으로 우선배향되었으나, H2의 경우에는 200sccm이상에서 첨가량에 비례하여 (111)면으로 우선배향되는 경향을 보였다. 표면미세구조는 Ar을 첨가한 경우에 일정하게 facet구조를 유지하였으나, H2의 경우에는 facet에서 평탄한(smooth)구조로 변화되었다. 표면조도의 경우 첨가량이 늘어남에 따라 지속적으로 Ar에서는 증가하였지만, H2에서는 감소하였다.