• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.274.1-274.1
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• 2013

We report the circumferential alignment of human aortic smooth muscle cells (HASMCs) in an orthogonally micropatterned circular microfluidic channel to form an in vivo-like smooth muscle cell layer. To realize a biomimetic smooth muscle cell layer which is aligned perpendicular to the axis of blood vessel, we first fabricated a half-circular polydimethylsiloxane (PDMS) microchannel by soft lithography using a convex PDMS mold. The orthogonally micro wrinkle patterns were generated inside the half-circular microchannel by stretching-releasing operation under UV irradiation. Upon UV treatment with uniaxial 40 % stretch of a PDMS substrate and releasing process, the microwrinkle patterns perpendicular to the axial direction of the circular microchannel were generated, which could guide the circumferential alignment of HASMCs successfully during cultivation. The analysis of orientation angle, shape index, and contractile protein marker expression indicates that the cultured HASMCs revealed the in vivo-like cell phenotype. Finally, we produced circular microchannels by bonding two half-circular microchannels, and cultured the HASMCs circumferentially with high alignment and viability for 5 days. These results are the first demonstration for constructing an in vivo-like 3D smooth muscle cell layer in the circular microfluidic channel which can provide novel bioassay platforms for in-depth study of HASMC biology and vascular function.

• Structural Engineering and Mechanics
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• 제20권1호
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• pp.21-43
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• 2005

Masonry is a composite non-homogeneous structural material, whose mechanical properties depend on the properties of and the interaction between the composite components - brick and mortar, their volume ratio, the properties of their bond, and any cracking in the masonry. The mechanical properties of masonry depend on the orientation of the bed joints and the stress state of the joints, and so the values of the shear modulus, as well as the stiffness of masonry structural elements can depend on various factors. An extensive testing programme in several countries addresses the problem of measurement of the stiffness properties of masonry. These testing programs have provided sufficient data to permit a review of the influence of different testing techniques (mono and bi-axial tests), the variations caused by distinct loading conditions (monotonic and cyclic), the impact of the mortar type, as well as influence of the reinforcement. This review considers the impact of the measurement devices used for determining the shear modulus and stiffness of walls on the results. The results clearly indicate a need to re-assess the values stated in almost all national codes for the shear modulus of the masonry, especially for masonry made with lime mortar, where strong anisotropic behaviour is in the stiffness properties.

• Steel and Composite Structures
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• 제43권1호
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• pp.107-116
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• 2022

This paper presents results of numerical studies completed on unreinforced and doubler plate reinforced Elliptical Hollow Section (EHS) T-joints subjected to axial compressive loading on the brace member. Non-linear finite element (FE) models were developed using the finite element code, ABAQUS. Available test data in literature was used to validate the FE models. Subsequently, a parametric study was carried out to investigate the effects of various geometrical parameters of main members and reinforcement plates on the ultimate capacity of reinforced EHS T-joints. The parametric study found that the reinforcing plate significantly increases the ultimate capacity of EHS T-joints up to twice the capacity of the corresponding unreinforced joint. The thickness and length of the reinforcing plate have a positive effect on the ultimate capacity of Type 1 joints. This study, however, found that the capacity of Type 1 orientation is not dependent on the brace-to-chord diameter ratio. As for type 2 orientations, the thickness and length of the reinforcement have a minimal effect on the ultimate capacity. A new design method is introduced to predict the capacity of the reinforced EHS T-joints Type 1 and 2 based on the multiple linear regression analyses.

• Current Optics and Photonics
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• 제8권4호
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• pp.421-426
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• 2024

The use of stimulated emission depletion (STED) microscopy has significantly improved resolution beyond the limits imposed by diffraction; Furthermore, STED microscopy adopts a 4Pi-geometry to achieve an isotropic improvement in resolution. In isoSTED microscopy, a polarizing beam splitter and retarders are used in a 4Pi cavity to split beams of identical power, generating constructive and destructive interference for lateral and axial resolution improvements, respectively. The precise alignment of the retarders is crucial for optimizing the performance of isoSTED microscopy, because this orientation affects the quality of the depletion focus, necessitating zero intensity at the center. Incomplete destructive interference can lead to unwanted fluorescence inhibition, resulting in degraded resolution and contrast. However, measuring the intensity and polarization state in each optical path of the 4Pi cavity is complex and requires additional devices such as a power meter. Here, we propose a simple and accurate alignment method for the 4Pi cavity in isoSTED microscopy. Our approach demonstrates the equal allocation of power between upper and lower beam paths and achieves complete destructive interference using a polarizing beam displacer and a single CCD camera positioned outside the 4Pi cavity.

• 암석학회지
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• 제14권2호
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• pp.108-115
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• 2005

경기육괴 중앙부의 광주시 일대에 분포하는 선캠브리아기의 경기편마암 복합체는 흑운모호상 편마암 및 석영장석질 편마암으로 구성되어 있다 지질구조 분석결과 연구지역은 적어도 다섯 번의 변형작용을 받은 것으로 밝혀졌다. 첫 번째 변성작용(M1) 및 변형작용(Dl)중에 퇴적암(층리; S0)이 변성되어 흑운모호상 편마암으로 되었으며, 성분엽리(S1)가 발달되었다. 심성암이 관입 후 두 번째 변성작용(M2) 및 변형작용(D2)이 일어났으며, 이때 심성암이 엽리(S2)가 발달된 석영장석질 편마암으로 변하였다. 세 번째 변형작용(D3) 중에 수십 cm 규모의 밀착습곡 및 등사습곡(F3)이 발달하였으며, 축면방향으로 성분엽리(S3)가 발달하였다. 변위작용에 의해 뿌리 없는 습곡(F3)이 S3 엽리와 평행하게 발달되어 있다. 네 번째 변형작용(D4) 중에 남북방향의 압축력에 의해 약 100m의 축면분리를 가지는 F4 습곡이 동서 방향으로 발달하였다. 다섯 번째 변형작용 중에 동서 방향의 압축력에 의해 축면분리가 약 3km 규모의 남북 방향의 F5 습곡이 발달하였다. F5 습곡의 중심부에서는 F4 습곡에 F5 습곡작용이 중첩되어 F5 습곡의 습곡축면과 평행한 남북방향으로 F4 습곡이 발달되어 있으며 날개 사잇각 및 축면분리가 작아졌다. 반면에 F5 습곡의 서쪽 날개 지역에서는 북동방향으로, 동쪽 날개 지역에서는 북서방향으로 F4 습곡이 회전되었다. 연구지역에 발달되어 있는 엽리의 궤적은 주로 F4 습곡 및 F5 습곡에 의해 지배되어 있다. F4 습곡작용 동안에 취성변형작용에 의해 절리 및 단층이 발달하였으며 F5 습곡의 양쪽 날개부에는 부채꼴 절리가 우세하게 발달하고, 힌지대에는 be-절리가 우세하게 발달하였다 그 이후에 북서 방향의 주향이동 단층이 지질도 규모로 발달하였다. 제4기 동안에 발생한 산사태가 일부 절리 및 엽리의 방향을 반시계방향으로 약 $15^{\circ}$ 회전시켰다.

• Composites Research
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• 제17권3호
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• pp.29-37
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• 2004

본 연구에서는 대변형 보이론을 이용하여 정지 비행 시 복합재 무베어링 로우터 시스템의 공력탄성학적 안정성 해석을 수행하였다. 무베어링 로우터 시스템은 유연보, 토오크 튜브, 피치 링크, 그리고 메인 블레이드로 구성된다. 유연보, 토오크 튜브, 그리고 메인 블레이드를 각각 플랩 굽힘, 리드-래그 굽힘, 비틀림 그리고 축 방향 변형의 탄성 운동을 하는 보로 가정하고, 1차원 보 요소로 모델링을 하였다. 또한, 유연보를 복합재료 적층판으로 구성된 비틀림에 유연한 직사각형 단면을 갖는 보로 모델링 하여, 1차원 보 해석에 필요한 유효 단면 상수를 얻었다. 외력으로는 2차원 준-정상 공기력 모델을 적용하였으며, 보의 유한 요소 지배방정식은 헤밀턴 원리(Hamilton's principle)를 이용하여 얻었다. 공력 탄성학적 안정성 해석을 수행하기 위하여 p-k 방법을 이용하였으며, 유연보의 적층각과 적층 순서에 따른 구조적 연성이 무베어링 로우터 시스템의 공란성 안정성에 미치는 영향을 알아보았다.

• 한국임상수의학회지
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• 제33권6호
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• pp.340-345
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• 2016

The present study determined the normal reference ranges for the femoral and tibial joint orientation angles of small-breed dogs. For this purpose, 60 each of cadaveric canine femurs and tibias from normal small-breed dogs (Maltese, Poodle, Shih Tzu, Yorkshire Terrier) were examined with radiographs and photographs. Axial and frontal radiographs and photographs of each bone were obtained, from which anteversion and inclination angles, anatomic lateral proximal and distal femoral angles (aLPFA and aLDFA), mechanical lateral proximal and distal femoral angles (mLPFA and mLDFA), and mechanical medial proximal and distal tibial angles (mMPTA and mMDTA) were measured. The 95% CI for radiographic values of all femurs and tibiae were anteversion angle, $23.4-27.4^{\circ}$; inclination angle, $128.4-130.4^{\circ}$; aLPFA, $117.8-122.1^{\circ}$; aLDFA, $93.7-95.2^{\circ}$; mLPFA $113.8-117.3^{\circ}$; mLDFA $99.2-100.5^{\circ}$; mMPTA $96.8-98.5^{\circ}$; mMDTA $89.4-90.7^{\circ}$. The Maltese had a larger anteversion angle than the Poodle and the Yorkshire Terrier and a larger mLPFA than the Poodle. In the comparison between the radiographs and the photographs, significant differences were found in the anteversion angle, mLPFA, mMPTA, and mMDTA. The established normal reference values might be useful for determining whether a valgus or varus deformity of the femur or the tibia is present and if so, the degree of angular correction needed.

• Journal of the Optical Society of Korea
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• 제12권2호
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• pp.98-102
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• 2008

Optical Coherence Tomography (OCT) is an important noninvasive medical imaging technique that can reveal subsurface structures of biological tissue. OCT has demonstrated a good correlation with histology in sufficient resolution to identify morphological changes in articular cartilage to differentiate normal through progressive stages of degenerative joint disease. Current OCT systems provide individual cross-sectional images that are representative of the tissue directly under the scanning beam, but they may not fully demonstrate the degree of degeneration occurring within a region of a joint surface. For a full understanding of the nature and degree of cartilage degeneration within a joint, multiple OCT images must be obtained and an overall assessment of the joint surmised from multiple individual images. This study presents frequency domain three-dimensional (3-D) OCT imaging of degenerative joint cartilage extracted from bovine knees. The 3-D OCT imaging of articular cartilage enables the assembly of 126 individual, adjacent, rapid scanned OCT images into a full 3-D image representation of the tissue scanned, or these may be viewed in a progression of successive individual two-dimensional (2-D) OCT images arranged in 3-D orientation. A fiber-based frequency domain OCT system that provides cross-sectional images was used to acquire 126 successive adjacent images for a sample volume of $6{\times}3.2{\times}2.5\;mm^3$. The axial resolution was $8\;{\mu}m$ in air. The 3-D OCT was able to demonstrate surface topography and subsurface disruption of articular cartilage consistent with the gross image as well as with histological cross-sections of the specimen. The 3-D OCT volumetric imaging of articular cartilage provides an enhanced appreciation and better understanding of regional degenerative joint disease than may be realized by individual 2-D OCT sectional images.

• 스마트미디어저널
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• 제5권1호
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• pp.44-48
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• 2016

장기추적 뇌영상 연구에서 자기공명영상장치의 노후 또는 기술 발전에 따른 업그레이드로 인해 연구기간 내 동일한 촬영 조건을 유지하기 어렵다. 특히, 자장 세기가 1.5T에서 3T로 증가한 경우가 많아, 기존 1.5T 영상을 새로운 3T 영상과 통합해서 분석에 사용하는 것이 가능한지 확인할 필요가 있다. 본 논문에서는 자장 세기와 스캔 방향이 다른 자기공명영상에서 측정한 해마 체적의 재현성을 연구 분석하였다. 실험참가자 296명의 3차원 T1 영상을 1.5와 3T 자기공명영상장치 각각에서 스캔 방향을 달리하여 획득하고 뇌영상 연구에 널리 사용되는 Freesurfer를 이용하여 실험참가자의 해마 체적을 측정하였다. 해마 체적의 영상종류 간 차이를 확인하기 위해 대응표본t-검정을 수행한 결과, 자기공명영상장치의 자장 세기와 스캔 방향에 따라 해마체적이 유의하게 차이가 있음을 확인하였다. 이런 결과는 촬영조건에 따라 측정된 해마체적이 달라질 수 있음을 의미하므로, 촬영 조건이 다른 영상을 통합 분석할 수 있는 기법의 개발이 필요하다고 판단된다.

• 대한방사선기술학회지:방사선기술과학
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• 제44권4호
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• pp.301-306
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• 2021

The skull has peripheral organs such as the crystalline lens and thyroid gland, which are highly radiosensitive, but the examination is performed without considering the uneven dose distribution due to the heel effect at the time of the current Skull Town's examination. However, no studies have been conducted on the exposure dose of surrounding organ tissues due to the difference in image density due to the heel effect and the non-uniformity of the dose. Using the cathode (-) and anode (+) set on the Tube to measure the scattered radiation along the Tube direction as a guide, change 30° and 37° in the cathode direction and 30° and 37° in the anode direction. It was given and investigated 5 times to obtain scattered radiation. image measurements were SNR, PSNR, RMSE, and MAE. Measurement results Measurement results of surrounding organ doses when the Tube direction was 30° and 37° The dose was low when the direction was cathodic in all organs (p<0.000). Both cathodes were higher in the image measurements(p<0.04). Continuous research may be needed for diagnostically valuable imaging and minimization of patient exposure dose.