• 한국경영과학회지
• /
• 제22권1호
• /
• pp.159-182
• /
• 1997

This study is to establish the validity of EDI adoption model Korean Companies. The research model is hypothesized in the external factors of company directly affect on EDI adoaption and the internal factors of company moderately affect on the direct effect. The external factors of company consists of economic factors, organizational power factors, and technological factor. The internal factors of company consists of the size of the company, innovative tendency of the top management, and maturity of the information technology. In the result of data analysis-the data were collected from a total of 81 companies in 6 industries adopted variables are the existence of EDI standard, transaction frequency, inter-organizational bargaining power, and pressure from industry association. Also size of the company and innovative tendency of the top management in a company's internal factors were adopted as moderate variables.

• Geomechanics and Engineering
• /
• 제12권2호
• /
• pp.313-326
• /
• 2017

Based on the reliability theory and limit analysis method, the roof stability of a shallow tunnel is investigated under the condition of surface settlement. Nonlinear Hoek-Brown failure criterion is adopted in the present analysis. With the consideration of surface settlement, the internal energy and external work are calculated. Equating the rate of energy dissipation to the external rate of work, the expression of support pressure is derived. With the help of variational approach, a performance function is proposed to reliability analysis. Improved response surface method is used to calculate the Hasofer-Lind reliability index and the failure probability. In order to assess the validity of the present results, Monte-Carlo simulation is performed to examine the correctness. Sensitivity analysis is used to estimate the influence of different variables on reliability index. Among random variables, the unit weight significantly affects the reliability index. It is found that the greater coefficient of variation of variables lead to the higher failure probability. On the basis of the discussions, the reliability-based design is achieved to calculate the required tunnel support pressure under different situations when the target reliability index is obtained.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 ITC-CSCC -2
• /
• pp.604-607
• /
• 2000

In this paper we design the robust impedance controller of the robot manipulator with time delay. The designed controller considers time delay in the position loop and stabilizes the closed-loop system. The performance of a controller can be easily degraded by external disturbances. To improve the performance when external disturbances exist, we use the disturbance observer to handle the disturbances in the velocity loop and provide robustness to the control system. To show the validity of the designed controller, several experiments are performed for the 5-DOF robot manipulator equipped with the wrist force/torque sensor system.

• Geomechanics and Engineering
• /
• 제16권6호
• /
• pp.569-575
• /
• 2018

The stability of shallow cavities with an arbitrary profile is a difficult issue in geotechnical engineering. This paper investigates this problem on the basis of the upper bound theorem of limit analysis and the Hoek-Brown failure criterion. The influence of pore pressure is taken into consideration by regarding it as an external force acting on rock skeleton. An objective function is constructed by equating the internal energy dissipation to the external force work. Then the Lagrange variation approach is used to solve this function. The validity of the proposed method is demonstrated by comparing the analytical solutions with the published research. The relations between shallow and deep cavity are revealed as well. The detaching curve of cavity roof with elliptical profile is obtained. In order to facilitate the application of engineering practice, the numerical results are tabulated, which play an important role in tunnel design and stability analysis of roof. The influential factors on potential collapse are taken into consideration. From the results, the impact of various factors on the extent of detaching is seen intuitively.

• Journal of the Korean Physical Society
• /
• 제73권11호
• /
• pp.1663-1674
• /
• 2018

We propose the Poynting vector analysis of the air mode in a top-emitting organic light-emitting diode (OLED) by combining the transfer matrix method and dipole source term. The spatial profiles of the time-averaged optical power flow of the air mode are calculated inside and outside the multilayer structure of the OLED with respect to the thickness of the semi-transparent top cathode and capping layer (CPL). We elucidate how the micro-cavity effect controlled by the thickness variation of the semi-transparent top cathode or CPL affects the internal optical power and absorption loss inside the OLED multilayer and the external optical power coupled into the air. When the calculated absorption loss and external power obtained by the proposed Poynting vector and currently-used point dipole models are compared, two calculation results are identical, which demonstrates the validity of the two models.

• 한국구조물진단유지관리공학회 논문집
• /
• 제10권4호
• /
• pp.145-154
• /
• 2006

본 논문은 외부 긴장재로 보강된 2경간 연속 강합성보의 내하력을 향상시키기 위한 방법을 제시하였다. 긴장재를 정모멘트 구간의 강주형 하부에 설치하였다. 이 방법은 정모멘트 뿐만 아니라 부모멘트도 감소시킬 수 있다. 강합성보를 긴장재로 보강함으로써 내하율 식에서 목표 내하율을 만족시키기 위한 긴장재 개수와 초기 긴장력의 결정방법을 기술하였다. 본 방법을 실교량의 강합성보에 적용하여 타당성을 입증하였다.

• 한국광학회지
• /
• 제11권4호
• /
• pp.265-270
• /
• 2000

이득 스위칭 $1.55\mu\textrm{m}$ UFB 반도체 레이저에서 외부 주입광의 전력과 파장이 시간 지터와 펄스 폭에 미치는 영향을 전송선로 레이저 모델에 기초한 모의 실험을 통하여 분석하였다. 주입 광 전력이 증가함에 따라 시간지터는 감소하고 펄스폭은 증가했으며, 최소 시간 지터는 주입 광의 파장이 첩된 스펙트럼의 중시과 일치할 때에 나타났다. 이에 따라, 외부 광 주입에 의해 펄스 폭의 증가 없이도 시간 지터를 대략 1/2.7배로 감소시킬 수 있었다. 모의 실험 결과는 본 실험결과와는 물론이고 이미 발표된 실험결과와 비교적 잘 일치함을 확인하였으며, 이는 본 모델이 반도체 레이저에 기초한 시스템 분석에 유용함을 입증한다.

• 전력전자학회논문지
• /
• 제5권2호
• /
• pp.105-114
• /
• 2000

본 논문에서는 진행파형 초음파 모터 구동을 위한 직렬형 모터측에 직렬로 삽입되는 인덕터의 설계를 위한 새로운 해석 방법을 제시하였다. 초음파 모터의 구조를 등가적으로 해석하였고 이를 토대로 직렬 인덕터의 선정법을 제시하였다. 직렬 인덕터가 최적으로 설계되었을 때 모터 내부의 기계측 고유 공진 요소에 효율적인 전력이 전달될 수 있음을 시뮬레이션을 통하여 확인하였다. 여러 단계의 외부 인덕터에 대한 실험을 통하여 초음파 모터의 주파수 및 속도 특성이 검토되었다. 그 결과 제안된 외부 인덕터 선정방법의 타당성이 입증되었다.

• Journal of Power Electronics
• /
• 제16권2호
• /
• pp.798-804
• /
• 2016

This paper proposes a new operation and control strategy for Power-Assisted Wheelchairs (PAW) using one brushless DC (BLDC) motor. The conventional electrical wheelchairs are too heavy and large for one person to move because they have two electric motor wheels. On the other hand, the proposed PAW system has a small volume and is easy to move due to the presence of a single wheel motor. Unlike the conventional electric wheelchairs, this structure for a PAW does not have a control joystick to reduce its weight and volume. To control the wheelchair without a joystick, a special control system and algorithm are needed for proper operation of the wheelchair. In the proposed PAW system uses only one sensor to detect the acceleration and direction of PAW's movement. By using this sensor, speed control can be achieved. With a speed control system, there are three kinds of operations that can be done on the speed of a PAW: the increment of PAW speed by summing external force, the decrement of PAW speed by subtracting external force, and emergency breaking by evaluating the time duration of external force. The validity of the proposed algorithm is verified through experimental results.

• Structural Engineering and Mechanics
• /
• 제74권2호
• /
• pp.297-311
• /
• 2020

The main purpose of this study is to analyze the effects of external pressure on the vibration and buckling of functionally graded (FG) spherical panels resting of elastic medium. The material characteristics of the FG sphere continuously vary through the thickness direction based on the power-law rule. In accordance with first-order shear deformation shell theory and by the use of Ritz formulation the governing equations are presented. In this regard, the beam functions are applied in two-dimensions for different sets of boundary supports. The Winkler and Pasternak models of elastic foundations are also taken into account. In order to show the validity and applicability of the presented formulation, various comparison studies are given. Furthermore, a diverse range of numerical results is reported to check the impacts of geometrical and material parameters along with external pressure on the vibration and buckling analysis of FG spherical panels.