• 한국전문물리치료학회지
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• 제13권4호
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• pp.23-29
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• 2006

The purpose of the present study was to examine gaze effects on spatial and kinematic characteristics during a pointing task. Subjects were asked to watch and point to an aimed target (2 mm in diameter) displayed on a vertically mounted board. Four gaze conditions were developed as combinations of "seeing-aiming" in terms of the eye movements: Focal-Focal (F-F), Focal-Fixing (F-X), Fixing-Focal (X-F), and Fixing-Fixing (X-X). Both the home target and an aimed target were presented for 1 second and then were disappeared in F-F and X-F. In X-F and X-X, only an aimed target disappeared after 1 second. Subjects were asked to point (with index finger tip) to an aimed target accurately as soon as the aimed target was removed. A significant main effect of gaze was found (p<.01) for normalized movement time. Peripheral retina targets had significantly larger absolute error compared to central retina targets on the x (medio-lateral) and z (superior-inferior) axes (p<.01). A significant undershooting to peripheral retina targets on the x axis was found (p<.01). F-F and X-F had larger peak velocities compared to F-X and X-X (p<.01). F-F and X-F were characterized by more time spent in the deceleration phase compared to F-X and X-X (p<.01). The present study demonstrates that central vision utilizes a form of on-line visual processing to reach to an object, and thus increases spatial accuracy. However, peripheral vision utilizes a relatively off-line visual processing with a dependency on proprioceptive information.

• Restorative Dentistry and Endodontics
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• 제44권3호
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• pp.31.1-31.9
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• 2019

Objectives: To compare the formation of dentinal defects using stainless-steel hand K-files (HFs), rotary files, reciprocating files, and Self-Adjusting File (SAF), when used for oval root canals. Materials and Methods: One hundred and forty extracted human mandibular premolar with single root and oval canal were selected for this study. Oval canals were confirmed by exposing to mesio-distal and bucco-lingual radiographs. Teeth with open apices or anatomic irregularities were excluded. All selected teeth were de-coronated perpendicular to the long axis of the tooth, leaving roots segments approximately of 16 mm in length. Twenty teeth were left unprepared (control), and the remaining 120 teeth were divided into 6 groups (n = 20) and instrumented using HF (size 40/0.02), Revo-S (RS; size 40/0.06), ProTaper NEXT (PTN; size 40/0.06), WaveOne (WO; size 40/0.09), RECIPROC (RC; size 40/0.06), and the SAF (2 mm). Roots were then sectioned 3, 6, and 9 mm from the apex, and observed under stereomicroscope, for presence of dentinal defects. "No defect" was defined as root dentin that presented with no visible microcracks or fractures. "Defect" was defined by microcracks or fractures in the root dentin. Results: The control, HF, and SAF did not exhibit any dentinal defects. In roots instrumented by RS, PTN, WO, and RC files exhibited microcracks (incomplete or complete) in 40%, 30%, 55%, and 50%, respectively. Conclusions: The motor-driven root canal instrumentation with rotary and reciprocating files may create microcracks in radicular dentine, whereas the stainless-steel hand file instrumentation, and the SAF produce minimal or less cracks.

• Journal of Trauma and Injury
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• 제19권2호
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• pp.164-172
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• 2006

Background: The authors conducted a retrospective study to evaluate the mechanism of injury, the surgical techniques, the clinical features, the combined injuries, the treatment results, and the surgical complications in patients with atlantoaxial fracture/subluxations. Methods: The authors reviewed 71 cervical fracture/dislocations during a four-year period from September 2002 to August 2006. Among them, there were twenty one C1,2 fracture/subluxations. There were thirteen men (mean age : 43.5 years) and eight women (mean age : 50 years). Their follow-up period was at least 6 months, and the mean follow-up period was 9.6 months. Gardner-Wells tongs traction was used in all patients immediately on presentation. Surgical treatment was performed, depending on the pathologic conditions. Results: Of all 21 cases, 14 cases were injured in motor vehicle accidents, 5 were falls, and 2 were miscellaneous. There were four C1 fracture (5.6%), fourteen C2 fracture (66.7%), one C1 and 2 combined fracture (4.8%), and one C1-2 subluxation (4.8%). The C1 fractures in our series were classified as two Jefferson's fractures and two C1 lateral mass fracture. The C2 fractures were classified as one odontoid type I fracture, two odontoid type II fractures, five odontoid type III fractures, one hangman's fracture, and four C2 body tear-drop fractures. Atlantoaxial fractures were associated with six (28.6%) head injuries, four (19.0%) other spinal injuries, two (9.5%) chest injuries, and three (14.3%) spinal cord injuries. Surgical treatment was performed in nine cases, which included anterior odontoid screw fixation in two cases, transarticular screw fixation with iliac bone graft in one case, posterior fixation by using C2 pedicle screw and C3 lateral mass screw in three cases, lateral mass screw fixation C1-2 with iliac bone graft in one case, O(occipito)-C1-3-4 screw fixation in one case, posterior C2-3 wiring with allograft in one case, and halo vest in six cases. Conservative management was used in the rest of the patients in our trials. Bone fusion was complete in all cases. There were no operation-related complication, except one pin site infection in the case of halo vest. Conclusion: In this study, the choice of appropriate treatment according to the fracture types resulted in safe and effective management of unique atlantoaxial fracture/subluxations.

• 생물환경조절학회지
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• 제13권1호
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• pp.1-7
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• 2004

본 연구는 오이수확기의 매니퓰레이터 개발을 위한 기구학적 분석을 하는 것이다. 매니퓰레이터의 정방향 기구학 및 역방향 기구학 분석을 한 후 실제 장치의 반복오차 측정실험을 통해 이론 값을 검증하였다. 매니퓰레이터는 총 세 개의 링크로서 한 개의 수직링크와 두 개의 호전링크로 구성되어져 있으며, 세 개의 스테핑 모터가 각 관절에 장착되어 링크에 동력을 전달한다. 주요 연구결과를 요약하면 다음과 같다. D-H Parameter를 이용하여 정방향 기구학에 의한 매리퓰레이터의 변환 연산자를 얻었다. 역방향 기구학의 해는 두가지로 나타났으며 삼각함수를 이용하여 해를 구하였다. 매리퓰레이터의 반복오차를 측정한 검증 실험에서는 X, Y, Z축에 대하여 반복 오차가 최대 2.60mm, 2.05mm, 1.55mm로 나타났으며, 정방향 및 역방향 기구학에서 오차의 최대지점 및 최소지점의 실제 좌표는 일치하였다. 반복오차 측정 결과는 매리퓰레이터의 목표지점인 오이의 직경에 비해 비교적 작게 나타났다. 측정오차는 실험중 발생한 실험오차로 판단된다. 매니퓰레이터의 오차를 줄이고 작업능률의 향상을 위해서는 링크의 수를 줄이고 오이의 품종 및 재배환경을 고려하여야 하며, 경량이면서도 견고한 재료를 사용하여 하중을 줄여야 한다.

• 한국임상수의학회지
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• 제30권6호
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• pp.499-502
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• 2013

목 부위에 교상을 입은 8살의 중성화된 수컷 푸들이 내원하였다. 신체 검사에서, 보행이 불가능하였고 심부통증이 있는 사지의 불완전 마비로 UML 증상을 보였다. 방사선과 CT 검사에서 경추 1번의 횡돌기의 골절, 경추 2번의 가시돌기의 골절이 관찰 되었다. 보존적 처지를 1주일 실시 하였으나 증상이 완화 되지 않아 수술적 교정이 선택되었다. 수술적 안정은, 배쪽으로 접근하여 나사, K-wires 와 bone cement를 이용하여 내원 7일차에 실시 되었다. 수술 후 4주 이후 혼자 설 수 있었으며, 6주 이후 보행이 가능하였다. 본 증례에서는 등쪽과 배쪽 부위 중쇠뼈 골절을 교정하기 위하여 배쪽 복합 고정을 실시하였으며, 좋은 예후를 보였다.

• Journal of Yeungnam Medical Science
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• 제11권1호
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• pp.63-71
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• 1994

뇌졸중이 시상하부-뇌하수체-부신축에 미치는 영향을 조사하기 위해 1992년 6월 1일부터 1993년 6월 30일까지 영남대학교 의과대학 부속병원 신경과에 입원한 뇌경색 42례, 뇌출혈 20례 등 총 62례 환자대상군과 대조군 21례를 대상으로 뇌졸중의 각 유형, 병변부위, 병변크기, 운동장애정도, 연령 및 성별 등이 DST결과에 어떤 영향을 미치는지 조사하여 다음과 같은 성적을 얻었다. 뇌경색군에서 혈청 cortisol기저치가 대조군보다 유의하게 높았고 (p<0.01), DST 비억제반응의 빈도는 뇌졸중군에서 대조군보다 유의하게 높았다(p<0.05). 뇌졸중군 중에서 좌측 대뇌반구의 병변이 DST 비억제반응의 빈도가 유의하게 높았다(p<0.01). 뇌졸중의 병변크기가 심할수록 DST 비억제반응의 빈도가 유의하게 높았으나 (P<0.01) 뇌졸중의 각 유형, 운동장애 정도, 연령 및 성별등은 DST 비억제반응의 빈도와 유의한 차이는 없었다. 이로 미루어 볼때 뇌졸중이 HPA축에 영향을 미침을 알 수 있고, 뇌졸중 유형중에는 뇌경색이 가장 많은 장애를 초래하며, 뇌졸중의 병변부위에 따라서는 좌측 대뇌반구가 가장 많은 장애를 야기하며, 병변이 클수록 더 많은 장애를 초래함을 알 수 있어 뇌졸중후 나타나는 우울증등의 시상하부와 연관된 환자에게는 항 우울제투여로 임상효과를 기대할 수 있고 향후 뇌척수액의 신경전달물질 검사 및 뇨의 catecholamine대사산물 측정 등 지속적 연구가 필요할 것으로 사료된다.

• 한국정보통신학회논문지
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• 제19권11호
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• pp.2689-2696
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• 2015

방사선 진단에 사용되는 방사성동위원소 중 사이클로트론을 이용해 생산되는 방사성동위원소는 사이클로트론에서 인출된 양성자 빔이 타겟에 조사될 때 빔의 크기와 모양, 조사되는 위치에서 빔 균일 정도에 따라 생산 수율에 영향을 받는다. 이에 본 논문에서는 사이클로트론 빔 라인에서 빔의 단면을 측정할 수 있는 BPM(Beam Profile Monitor)장치를 개발하였다. LabView로 BPM장치를 원격 제어할 수 있도록 구성하였으며 BPM 프로그램을 이용하여 X축과 Y축으로 텅스텐 와이어를 스캔하면서 얻은 빔의 수치 정보를 2차원 그래프와 3차원 빔 분포 그래프로 표시하여 해석을 쉽게 모니터링 할 수 있도록 하였다. 빔을 측정하는 데 걸리는 시간은 스텝 모터 구동 속도가 2000pps일 때 37초가 걸린다는 것을 확인 할 수 있었다. 측정된 빔 분포정보를 기반으로 빔 재조정을 통해 빔 분포를 최적화함으로써 방사성동위원소 생산 수율을 극대화 시킬 수 있고 공급 안정화에도 기여하리라 본다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.1-2
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• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.