• 대한기계학회논문집
• /
• 제12권2호
• /
• pp.359-372
• /
• 1988

본 연구에서는 두 노즐간의 거리와 분사압력을 변화시켜 하류로 전개되는 이중분무의 분무형태를 살펴보았다.

• 대한소아치과학회지
• /
• 제32권1호
• /
• pp.89-100
• /
• 2005

형태학적으로 아주 유사한 상, 하악 제2유구치와 제1대구치의 교합면 형태를 분석하고자 정상교합의 유치열기 아동(Hellman dental age II A) 100명(남자 50명, 여자 50명)과 영구치열기의 성인(Hellman dental age IV A) 86명 (남자 43명, 여자 43명)을 대상으로 하였다. 상, 하악 제2유구치와 제 1대구치의 상, 하악 석고모형의 3차원 형상 data로부터 각 교두정간 거리, 교두정을 최소한의 오차로 지나는 평면과 교합면사이의 체적, 평면에서 교두정간 까지의 방향별 Section curve를 구하여 다음과 같은 결론을 얻었다. 1. 형성된 표준평면과 각 교두정과의 거리에 관한 오차는 하악 제2유구치에서 남자 0.05-0.09mm, 여자 0.04-0.09mm로서 제일 작았다. 2. 각 교두정간의 거리는 하악 제2유구치와 제 1대구치 에서 남자가 크게 나타났다. 특히 제2 유구치에서는 유의성이 존재하였다(p<0.05). 3. 남녀 모두에서 사주 교두거리를 제외하고, 상악 제2유구치는 원심 협측교두와 설측교두 사이가, 하악 제2유구치는 원심교두와 원심 설측교두 사이가, 상악 제1대구치는 근심 설측교두와 협측교두 사이가, 하악 제1대구치는 원심 설측교두와 근심 설측교두 사이의 거리가 가장 크게 측정되었다. 4. 제2유구치와 제1대구치에서 교합면 체적은 하악에서 크게 나타났고, 영구치가 1.40-1.75배 값을 보였으며(p<0.05), 남녀간에는 남자가 큰 값을 보이긴 하였지만 통계적인 유의성이 없었다. 5. 대부분의 경우 유치열에서 보다 영구치열에서 section curve가 넓고 깊었으며 교두사이의 사선거리를 제외하고 상악의 경우 근심 협측과 설측교두 사이에서 유치열과 영구치열 모두에서 가장 깊은 section curve를 이루었으며 하악에서는 영구치열은 원심 협측과 원심교두사이 유치열은 원심 설측과 원심교두 사이에서 가장 깊은 section curve를 이루었다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
• /
• pp.83-86
• /
• 1987

A vision algorithm is presented for the separation of near objects from distant objects. In the algorithm, a difference field of a stereo pair of images is computed to obtain the range information and the median filter is used for the suppression of distant objects. The objects within a given distance is segmented by thresholding the gray scale cross-section of the median filtered difference field. The experiment is performed in a laboratory setting.

• 한국터널지하공간학회 논문집
• /
• 제7권4호
• /
• pp.335-341
• /
• 2005

대단변 NATM터널에서 지반자체로 막장의 안정을 유지하기 위해 분할굴착공법을 사용한다. 분할굴착을 해야 한다면 더 나은 응력 상태를 유지할 수 있는 분할굴착공법을 강구해야할 것이다. 따라서 본 연구에서는 터널의 단면분할 굴착공법 중 CD굴착 (중벽분할굴착)공법에서 굴착순서에 따른 응력분포를 수치해석적인 방법을 이용하여 검토하고, 막장주변의 응력집중을 최소로 하는 최적의 막장 이격거리와 굴착순서를 도출하였다. 해석에 사용한 프로그램은 국내에서 상용화되고 있는 3차원 연속체 해석 프로그램인 FLAC-3D Ver 2.1을 사용하였고, 암반등급 3과 5에 대해 막장거리 2m, 4m, 6m, ${\cdots}$, 20m, 40m를 적용하여 안정성 검토를 행하였다.

• Restorative Dentistry and Endodontics
• /
• 제28권6호
• /
• pp.485-490
• /
• 2003

Complete understanding of the exterior and interior structure of the tooth would be prerequisite to the successful clinical results, especially in the restorative and endodontic treatment. Although three-dimensional reconstruction method using x-ray microtomography could not be used in clinical cases, it may be the best way to reconstruct the morphologic characteristics of the tooth structure in detail without destructing the tooth itself. This study was done to three dimensionally reconstruct every teeth in the arch in order to increase the understanding about the endodontic treatment and to promote the effective restorative treatment by upgrading the knowledge of the tooth morphology. After placing tooth between the microfocus x-ray tube and the image intensifier to obtain two-dimensional images of each level. scanning was done under the condition of 80 keV, $100{\;}\mu\textrm{m}$, 16.8 magnification with the spot size of $8{\;}\mu\textrm{m}$. Cross-section pixel size of $16.28{\;}\mu\textrm{m}$ and 48.83 cross-section to cross-section distance were also used. From the results of this study, precise three dimensional reconstructed images of every teeth could be obtained. Furthermore, it was possible to see image that showed interested area only, for example. enamel portion only, pulp and dentin area without enamel structure, pulp only, combination image of enamel and pulp, etc. It was also possible to see transparent image without some part of tooth structure. This image might be used as a guide when restoring and preparing the full and partial crown by showing the positional and morphological relationship between the pulp and the outer tooth structure. Another profit may be related with the fact that it would promote the understanding of the interior structure by making observation of the auto-rotating image of AVI file from the various direction possible.

• 한국전자파학회논문지
• /
• 제29권6호
• /
• pp.433-440
• /
• 2018

레이다 안테나에서 송신한 신호가 어떠한 물체에 도달한 뒤 다시 안테나로 수신되는 과정에서, 환경에 의해 생성되는 클러터는 원하지 않는 요소이다. 클러터는 안테나의 빔 패턴과 어떠한 물체의 거리, 고도 등에 의해 계산되며, RCS로 나타낼 수 있다. 지면 기반 레이다에서 임의의 물체에 대한 지표면 클러터 RCS를 구하고, 레이다 방정식을 이용하여 지표면 클러터 RCS가 지면 기반 레이다 안테나에 수신되는 신호에 미치는 영향을 분석해본다.

• 한국정밀공학회지
• /
• 제34권3호
• /
• pp.217-224
• /
• 2017

Structural pipe frames are usually manufactured by complex processes, in which a straight pipe with an arbitrary cross-section is prepared via a roll-forming process and then fabricated into three-dimensional shapes by a secondary process. These conventional processes have low productivity. Recently, the inefficiency of the conventional processes has created the need to develop new forming technologies. In this study, a new incremental roll-forming process is proposed. The study is aimed at verifying the feasibility of the proposed process and investigating the fundamental process parameters using finite-element simulations. The result of the simulation demonstrates that the proposed process can be used effectively for cold fabrication of various shapes of structural pipes. In addition, the result of the investigation of parameters shows that the forming amount, number of roll sets, and distance between roll sets are significant factors to be considered in resolving dimensional errors of the product and improving its quality.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2005년도 지반공학 공동 학술발표회
• /
• pp.601-612
• /
• 2005

In mountainous area, Two parallel tunnels have been usually recognized as a road tunnel which has benefits in aspects of cost and stability. However, Design and construction of 2-Arch road tunnel are growing recently due to environmental destruction, compensation of land and difficulty of route separation. As studies are mainly undergoing on only guaranteeing stability and developing a waterproofing-drainage system to avoid water leakage through comprehension for characteristics of 2-arch tunnel behaviors, there is a tendency to evaluate quantity of support by empirical method with a tunnel which has a complicated cross-section and lack of construction ability. In this study, therefore, we made a plan of tunnel cross-section which had shown good construction ability and developed the waterproofing-drainage system which is able to solve the water leakage problem fundamentally by analyzing precedented 2-arch tunnels and investigating their sites in and out of nation. We also determined fixed quantity of support by a large-scale model test and numerical analysis. We want to contribute to 2-arch tunnel design hereafter introducing design procedure and method applied here.

• 한국의류산업학회지
• /
• 제18권1호
• /
• pp.91-102
• /
• 2016

This study classified the lower body types of female adults aged 18 to 69. The lower body was divided into front, lateral front, and lateral back. In order to understand the shape and somatotype of each segment, 592 people were analyzed based on girth, height, length, depth, width, angle and cross section distance for each segment. For data analysis, SPSS 18.0 was performed for descriptive statics, principal component analysis, K-means cluster analysis, ANOVA, and Duncan's test (as verification). Factor analysis was performed based on index values, calculation values, angles, and cross section distances. The measured items resulted in a.) 16 items were extracted to 5 factors in the case of the front factor (FF) of the lower body, and b.) 24 items were extracted to 6 factors in the case of lateral front factor (LFF) and lateral back factor (LBF). Each factor was put through K-means cluster analysis, classifying the lower bodies into one of four types of based on the front type (FT), the lateral front type (LFT), and the lateral back type (LBT) respectively. This study proposed an understanding of various lower body shapes by segmenting and classifying the lower body shapes for each type.

• Structural Engineering and Mechanics
• /
• 제5권3호
• /
• pp.257-268
• /
• 1997

The elastic deflections and Euler buckling loads are investigated for a class of tapered and initially curved cantilevered beams subjected to loading at the tip. The beam's width increases linearly and its depth decreases linearly with the distance from the fixed end to the tip. Unloaded, the beam forms a circular are perpendicular to the axis of bending. The beam's deflection responses, obtained by solving the differential equations in closed form, are presented in terms of four nondimensional system parameters: taper ratio ${\kappa}$, initial shape ratio ${\Delta}_0$, end load ratio f, and load angle ${\theta}$. Laboratory measurements of the Euler buckling loads for scale models of tapered initially straight, corrugated beams compared favorably with those computed from the present analysis. The results are applicable to future designs of the end structures of highway guardrails, which can be designed to give the appropriate balance between the capacity to deflect a nearly head-on vehicle back to its right-of-way and the capacity to buckle sufficiently that penetration of the vehicle may be averted.