• Tunnel and Underground Space
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• v.12 no.1
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• pp.19-30
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• 2002

Rock joint orientation is one of important geometric attributes that have an influence on the stability of rock structures such as rock slopes and tunnels. Especially, statistical models of the geometric attributes of rock joints can provide a probabilistic approach of rock engineering problems. The result from probabilistic modeling relies on the choice of statistical model. Therefore, it is critical to define a representative statistical model for joint orientation data as well as joint size and intensity and build up a series of modeling procedure including analytical validation. In this paper, we have examined a theoretical methodology for the statistical estimate and hypothesis analysis based upon Fisher distribution and bivariate normal distribution. In addition, we have proposed the algorithms of random number generator which is applied to the simulation of rock joint networks and risk analysis.

• Prospectives of Industrial Chemistry
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• v.22 no.6
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• pp.26-40
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• 2019

고령화 사회에 접어들면서 신경, 정신질환으로 인한 사회경제적 부담이 늘어나고 있다. 이를 해결하기 위해서는 관련된 신경 회로를 직접적으로 자극하거나 그곳에서 일어나는 일을 실시간으로 감지할 수 있는 장비의 개발이 필수적이다. 하지만 이를 위한 수많은 공학적 도구의 개발에도 불구하고, 뛰어난 공간적/시간적 분해능, 세포형의 선택성, 장시간 안정성을 보유한 신경 인터페이스의 개발은 아직까지도 연구가 필요한 분야이다. 특히 신경전달 원리를 모두 이용하고자 하는 다기능 인터페이스의 개발은 최근 많은 연구자들의 관심 주제이고, 유연성을 가지는 인터페이스 개발 또한 안정성뿐만 아니라 신경 신호의 수명을 좌우하는 중요한 요소이기에 그 중요성을 인정받고 있다. 이를 해결하기 위한 여러 가지 과학적 시도 중에서도, 열 인장 공정으로 제작되는 섬유 형태의 장비는 그 통합적 기능을 수행하는 한 가지 방법으로써 많은 관심을 받고 있다. 이 기술은 다양한 기하학적 구조, 기능적 요소 등을 통합하는데 매우 유리하며, 또한 기존 반도체 공정으로 다루기 어려운 유연성 물질로 마이크로 스케일의 인터페이스를 제작하는 데에 매우 효과적이다. 본 기고문에서는 먼저 현재까지 개발되고 있는 다기능 유연 신경 인터페이스의 연구동향을 소개하고, 특히 그 중에서도 최근에 주목받고 있는 광섬유 기반의 인터페이스 개발에 대해 이야기하고자 한다.

• Journal of Korea Multimedia Society
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• v.15 no.3
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• pp.323-335
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• 2012

In this paper, we propose an AR(augmented reality) system using user's bare hand based on computer vision. It is important for registering a virtual object on the real input image to detect and track correct feature points. The AR systems with markers are stable but they can not register the virtual object on an acquired image when the marker goes out of a range of the camera. There is a tendency to give users inconvenient environment which is limited to control a virtual object. On the other hand, our system detects fingertips as fiducial features using adaptive ellipse fitting method considering the geometric characteristics of hand. It registers the virtual object stably by getting movement of fingertips with determining the shortest distance from a palm center. We verified that the accuracy of fingertip detection over 82.0% and fingertip ordering and tracking have just 1.8% and 2.0% errors for each step. We proved that this system can replace the marker system by tacking a camera projection matrix effectively in the view of stable augmentation of virtual object.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.409-422
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• 2013

For stability design and P-${\Delta}$ analysis of steel frames with semi-rigid connections, the explicit form of the exact tangential stiffness matrix of a generalized semi-rigid frame element having rotational and translational connections is firstly derived using the stability functions. And its elastic and geometric stiffness matrix is consistently obtained by Taylor series expansion. Next depending on connection types of semi-rigidity, the corresponding tangential stiffness matrices are degenerated based on penalty method and static condensation technique. And then numerical procedures for determination of effective buckling lengths of generalized semi-rigid frames members and P-${\Delta}$ and shortly addressed. Finally three numerical examples are presented to demonstrate the validity and accuracy of the proposed method. Particularly the minimum braced frames and coupled buckling modes of the corresponding frames are investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.253.2-253.2
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• 2013

탄소나노튜브(CNT)는 나노미터의 직경과 마이크로미터의 길이를 갖는 기하학적 구조와 우수한 전계방출 특성으로 디지털 엑스선 소스와 같은 차세대 전자소스 소자에 활용되고 있다. 본 발표에서는 고밀착성의 CNT 에미터와 진공 브레이징 공정 개발을 기초로 설계, 제작된 CNT 기반 디지털 엑스선 튜브에 대해서 논의한다. 나노 필러를 함유한 페이스트를 제조하여 캐소드 기판에 대한 CNT 에미터의 밀착성을 향상시켰으며, 진공 브레이징을 고온에서 최적화함으로써 진공 밀봉된 엑스선 튜브내의 진공도를 안정적으로 확보하였다. 유방암 진단을 위한 디지털 단층합성 시스템용으로 50 mA 이상의 고전류 엑스선 튜브를 제작함과 아울러 근접 암치료 또는 강내형 엑스선 영상용으로 6 mm 이하의 직경을 갖는 초소형 엑스선 튜브를 제작하였다. 개발된 CNT 기반 엑스선 튜브는 우수한 안정성과 신뢰성을 보이며, 에너지와 강도를 쉽게 제어할 수 있는 디지털 특성도 잘 나타냈다.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.187-196
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• 2000

In this paper, stability analysis is carried out for the out of plane behaviors under compressive loads to the direction of the generator in anisotropic cylindrical shells. It is not easy to obtain the analytic solutions about the stability analysis of anisotropic cylindrical shells consisted of composite materials. For solving this problems, this paper used the finite difference method which is one of the numerical methods. Geometrical property of cylindrical shells transforms the compressive loads into the inplane behaviors. This paper studied the change of stiffness in the direction of the circumferential and stability of shells according to change of fiber angle, curvature, subtended angle and aspect ratio. From result of this study, anisotropic cylindrical shells under compressive loads to the direction of the generator vary greatly with respect to the change of the circumferential stiffness. Therefore, it will be more safe to strengthen the circumferential stiffness of anisotropic cylindrical shells under compressive loads.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10b
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• pp.514-516
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• 2000

게임이나 가상 현실에서의 대화형 처리에서는 다관절체의 동작 생성을 실시간에 비교적 사실적으로 처리되어야 할 필요성이 커지고 있다. 본 논문에서는 복잡한 계산이나 선형 시스템의 풀이 과정이 불필요한, 다관절체의 동작을 비교적 사실적으로 간단하고, 빠르게 생성하는 방법을 제안한다. 이 방법은 다관절체의 동역학적 움직임과 기하학적 제약 조건들을 이용하여, 실제와 유사한 동작을 빠르게 생성할 수 있음을 보인다. 특히, 대화형 시스템에서는 사용자의 요구에 실시간으로 응답을 줄 수 있고, 환경을 설정하는 물리량들과 가상 공간의 환경 요인들을 다양하게 변화시키더라도 적응적으로 반응하는 안정적인 동작을 생성할 수 있다.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.577-587
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• 2007

The length of study area was about 450m, and it was shown the geological condition of distinguished change of rock by cutting slope. In order to establish a slope stability, we carried out an engineering geological investigations about rock constituent, rock structure and a direction of discontinuous plane. The study area was divided into six section considered by direction of cutting slope, height of slope and geological condition. Analysis of cutting slope stability was carried out with stereo-graphic projection method by DIPS program which was feasible of stability analysis with geometrical correlation for a direction of discontinuous plane and direction of cutting slope. From analysis of cutting slope stability considered by construction, stability and economical efficiency, the slope stability countermeasures such as a high tensile wire net, slope protection method and enhanced retaining wall were established and operated which minimized effect caused by lower end of road on a relaxation of huge rock.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.13-23
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• 2010

Toppling failure of a slope is defined as failure behavior accompanying the rotation of rock block which is different from other failure such as sliding along with discontinuities and so on. It generally occurs in the region that discontinuities were developed with inverse dip direction to a slope and it could play a critical role in judging stability of slope. In this study, the stability evaluation was performed about toppling failure on a jointed road cut-slope. To check the deformation behavior, numerical analysis is widely used. However common analysis programs are based on continuum model. Recently, many methods that discontinuity properties can be considered in continuum analysis are suggested. In this study, numerical analysis based on FEM(Finite Element Method) was performed using interface element applied in heterogeneous boundary to simulate effects of discontinuities.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.395-404
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• 2005

This paper presents a reliable numerical procedure for nonlinear time-history analysis of space steel frames subjected to dynamic loads. Geometric nonlinearities of member (P-$\delta$) and frame (P-$\Delta$) are taken into account by the use of stability functions in framed stiffness matrix formulation. The gradual yielding along the member length and over the cross section is included by using a tangent modulus concept and a softening plastic hinge model based on the New-Orbison yield surface. A computer program utilizing the average acceleration method for the integration scheme is developed to numerically solve the equation of motion of framed structure formulated in an incremental form. The results of several numerical examples are compared with those derived from using beam element model of ABAQUS program to illustrate the accuracy and the computational efficiency of the proposed procedure.