• International Journal of Aeronautical and Space Sciences
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• 제14권4호
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• pp.350-355
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• 2013

Electrical resistance change measurements were performed, to detect fatigue damage of a quasi-isotropic CFRP and cross-ply CFRP laminates. A four-probe method was used to measure the exact electrical resistance change. A three-probe method was used to measure the electrical contact resistance change, during long cyclic loading. The specimen side surface was observed using a video-microscope to detect damage. The measured electrical resistance changes were compared with the observed damage. The results of this study show that the electrical resistance increase of the quasi-isotropic laminate was caused by a delamination crack between ${\pm}45^{\circ}$ plies. Matrix cracking caused a small electrical resistance increase of the cross-ply laminate, but the decreased electrical resistance caused by the shear-plastic deformation impedes matrix-cracking detection.

• Journal of the Korean Wood Science and Technology
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• 제36권2호
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• pp.56-62
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• 2008

The surface and edge structure of OSB is defined by surface strand orientation and strand mat thickness variation parallel to the length of the panel using video-microscope. The bending strength of OSB was correlated with surface strand orientation and decreased with increasing the orientation angle in the direction parallel to length of the panel. Average strand mat thickness variation parallel to the length of the panel did not influence the bending strength, but the bonding characteristics among the outermost strands affects the bending strength of OSB. Hankinson formula can be used to predicts the MOE according to strand orientation in the surface of OSB, and more precise strand alignment and reducing thickness variation should be important in the structural performance of OSB panels.

• 한국포장학회지
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• 제18권1_2호
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• pp.39-44
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• 2012

표면살균처리(초음파수, 염소수, 전해수) 후 PE 필름으로 진공포장 되어진 슬라이스 더덕의 저장 중 효과를 살펴보았다. 저장 초기에는 대조구에 비하여 표면살균처리된 신선편이 더덕은 총균수와 대장균군이 10배 이상 적게 측정되었다. 저장 20일 후 초음파수 처리구는 미생물뿐만 아니라 중량감모율, 부패율, 조직감과 표면색택이 대조구와 차이를 보이지 않을 정도로 품질이 저하되었다. Video microscope system을 이용하여 슬라이스더덕의 표면을 측정하였을 때 염소수와 전해수 처리구는 저장 10일까지는 초기와 큰 차이를 보이지 않았다. 그러나 저장 20일 후에는 슬라이스더덕 표면을 전해수 처리하여 PE필름으로 진공포장한 것이 조직감 뿐만 아니라 표면색의 갈변이 가장 적음에 따라, 저장 중 품질 유지에 가장 효과적인 것으로 나타났다.

• 구강회복응용과학지
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• 제28권4호
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• pp.339-347
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• 2012

Hydroxyapatite 코팅 임플란트의 세포반응성을 증가시키기 위한 다양한 연구들이 진행되어 왔다. 본 연구에서는 Hydroxyapatite 코팅된 타이타늄 시편을 NaCl 수용액에 다양한 기간 동안 담그어 놓았을 때 발생하는 표면거칠기, 표면접촉각, 표면에너지 등의 표면 특성의 변화를 관찰하였다. Hydroxyapatite 코팅 타이타늄 시편을 0.9% NaCl 용액에 담근 후 각각 7일, 14일, 21일간 $37^{\circ}C$를 유지하였다. 담그지 않은 동일한 시편을 대조군으로 하였다.(n=3) 모든 시편을 공기 중에서 완전 건조 후 공초점레이저주사현미경(CLSM)를 이용하여 표면거칠기를 측정하였다. 증류수를 시편 표면에 떨어뜨린 후 표면접촉각을 video contact angle analyzer를 이용하여 측정하였고 세 가지 용액을 떨어뜨려 접촉각을 측정하여 표면에너지를 산출하였다. 표면을 관찰하기 위해 Field Emission-Scanning Electron Microscope 촬영을 시행하였다. 본 연구 결과 Hydroxyapatite 시편을 Nacl 수용액에 담그는 간단한 방법을 통해 표면거칠기 및 친수성이 증가하는 것을 관찰할 수 있으며, 이러한 표면특성의 개선을 통하여 세포반응성이 증가하는 것을 기대할 수 있다.

• Archives of Plastic Surgery
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• 제47권3호
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• pp.242-249
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• 2020

Background The Exoscope is a novel high-definition digital camera system. There is limited evidence signifying the use of exoscopic devices in microsurgery. This trial objectively assesses the effects of the use of the Exoscope as an alternative to the standard operating microscope (OM) on the performance of experts in a simulated microvascular anastomosis. Methods Modus V Exoscope and OM were used by expert microsurgeons to perform standardized tasks. Hand-motion analyzer measured the total pathlength (TP), total movements (TM), total time (TT), and quality of end-product anastomosis. A clinical margin of TT was performed to prove non-inferiority. An expert performed consecutive microvascular anastomoses to provide the exoscopic learning curve until reached plateau in TT. Results Ten micro sutures and 10 anastomoses were performed. Analysis demonstrated statistically significant differences in performing micro sutures for TP, TM, and TT. There was statistical significance in TM and TT, however, marginal non-significant difference in TP regarding microvascular anastomoses performance. The intimal suture line analysis demonstrated no statistically significant differences. Non-inferiority results based on clinical inferiority margin (Δ) of TT=10 minutes demonstrated an absolute difference of 0.07 minutes between OM and Exoscope cohorts. A 51%, 58%, and 46% improvement or reduction was achieved in TT, TM, TP, respectively, during the exoscopic microvascular anastomosis learning curve. Conclusions This study demonstrated that experts' Exoscope anastomoses appear non-inferior to the OM anastomoses. Exoscopic microvascular anastomosis was more time consuming but end-product (patency) in not clinically inferior. Experts' "warm-up" learning curve is steep but swift and may prove to reach clinical equality.

• 폴리머
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• 제32권5호
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• pp.440-445
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• 2008

정수압 상태의 선형저밀도 폴리에틸렌 튜빙의 파손 메커니즘과 파손 모폴로지를 연구하였다. 비디오현미경과 주사전자현미경을 이용한 관찰 결과, 선형저밀도 폴리에틸렌 튜빙의 파손모드는 내면에서 외면으로 진전되는 크랙을 수반하는 취성파괴임을 확인하였다. 또한 산화유발시간과 적외선분광분석을 통하여, 파손된 선형저밀도 플리에틸렌 튜빙의 단면상에 열화에 의한 발열 피크와 카르보닐 피크의 증가를 관찰하였다. 열 가속에 의한 음력과 수명특성 사이의 관계를 고려한 선형저밀도 폴리에틸렌 튜빙의 가속수명시험법 및 시험장치를 개발하였다. 선형저밀도 폴리에틸렌 튜빙의 장기 정수압 상태의 수명을 예측하기 위해 아레니우스 모델과 와이블 분포를 적용한 통계학적 기법을 도입하였다. 그 결과, 사용온도 $25^{\circ}C$에서의 선형저밀도 폴리에틸렌 튜빙의 장기수명을 평가/분석하였다.

• Journal of Korean Neurosurgical Society
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• 제64권2호
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• pp.289-296
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• 2021

Objective : Though the operating microscope (OM) has been the standard optical system in neurosurgery, a new technology called three-dimensional (3D) exoscope has emerged as an alternative. Herein, two types of 3D exoscopes for brain tumor surgery are presented. In addition, the advantages and limitations compared with the OM are discussed. Methods : In the present study, 3D exoscope VOMS-100 or VITOM 3D was used in 11 patients with brain tumor who underwent surgical resection; the Kinevo 900 OM was used only in emergency. After completion of all surgeries, the participants were surveyed with a questionnaire regarding video image quality on the display monitor, handling of equipment, ergonomics, educational usefulness, 3D glasses, and expectation as a substitute for the OM. Results : Among 11 patients, nine patients underwent neurosurgical resection with only 3D exoscope; however, two patients required additional aid with the OM due to difficulty in hemostasis. Regarding video image quality, VITOM 3D was mostly equivalent to the OM, but VOMS-100 was not. However, both 3D exoscopes showed advantages in accessibility of instruments in the surgical field and occupied less space in the operating theater. Differences in ergonomics and educational usefulness between the exoscopes were not reported. Respondents did not experience discomfort in wearing 3D glasses and thought the exoscopes could be currently, and in the future, used as a substitute for the OM. Conclusion : Although many neurosurgeons are not familiar with 3D exoscopes, they have advantages compared with the OM and similar image quality. Exoscopes could be a substitute for OM in the future if some limitations are overcome.

• 한국추진공학회지
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• 제16권2호
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• pp.65-72
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• 2012

초음파 결함 분석 프로그램은 초음파 반사법을 기반으로 초음파 신호처리 기법을 적용하여 개발되었고, FRP 층간분리 및 FRP/내열고무 미접착 결함을 정량적으로 측정할 수 있었다. 복합재 연소관에서 검출된 결함은 절단하여 전산화 단층촬영 및 영상 현미경으로 분석하였고, 결함 분석 프로그램의 결과와 일치하였다. 본 논문은 복합재 연소관의 초음파시험 데이터를 C-Scan 영상으로 변환하여 결함을 분석할 수 있는 프로그램 개발 과정을 기술하였다.

• 한국염색가공학회지
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• 제22권4호
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• pp.362-372
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• 2010

This paper surveys the physical properties of the multiwall carbon nanotube (MWNT) and polyurethane composite film for improvement of mechanical properties and electrical characteristics. The modification of MWNT was carried out by acid treatment with nitric and sulphuric acid mixed solution, and then followed by thermal treatment for enhancing MWNT dispersion with polyurethane. This modified MWNT was mixed with polyurethane by changing the loading content of MWNT and dispersion time under the dimethylformamide solution in the ultrasonic wave apparatus. Various physical characteristics of the modified PU/MWNT films were measured and analyzed in terms of the loading content and dispersion time. The maximum absorbance of the PU/MWNT films were observed with the 2wt% loading at dispersion times of 2 and 24 hour, respectively. The minimum electrical volume resistivity of PU/MWNT film was shown at the loading content of 0.5wt% or more irrespective of dispersion treating time. However the optimum condition was assumed to 2wt% loading at dispersion time of 2 hours by assessing the surface profile of the film using video microscope. The breaking stress and strain of the PU/MWNT film decreased with increasing loading content, but no change of physical properties was shown with increasing in dispersion time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.852-855
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• 2002

In order to investigate the fracture behaviors(penetration modes) and resistance to penetration during ballistic impact of surface hardening treated Aluminum, Titanium alloy laminates, ballistic tests were conducted. In this paper, Anodized Al 5083-H131 alloy laminates and nitrified Ti (Gr.2) alloy laminates were used to achieve higher surface hardness. Surface hardness test were conducted using a Micro victor's hardness tester and thickness of surface hardening treated specimens was measured by video microscope. Resistance to penetration is determined by the protection ballistic limit($V_50$), a statistical velocity with 50% probability far complete penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are respectfully observed at and above ballistic limit velocities, as a result of $V_50$ test and Projectile Through Plates (PTP) test methods. PTP tests were conducted with $0^{\circ}$ obliquity at room temperature using 5.56mm ball projectile. $V_50$ tests with $0^{\circ}$ obliquity at room temperature were conducted with projectiles that were able to achieve near or complete penetration during PTP tests.