• 한국지반공학회논문집
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• 제30권4호
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• pp.81-92
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• 2014

하천제방 건전도 평가는 하천설계기준 해설(2009), 구조물기초 설계기준 해설(2009) 등 관련 기준을 토대로 한계동수경사법, 한계유속법 등에 의한 파이핑 안전성과 제내지 및 제외지의 활동안전성 평가에 의하여 수행된다. 이때 수위파형은 건전도 평가 시 가장 중요한 설계입력자료이나 관련 국가기준에서 그 결정방법을 제시하지 못함으로서 부정확한 설계가 이루어지고 있다. 본 논문에서는 낙동강 문산제를 대상으로 평수위 상승, 홍수위 지속, 수위하강, 홍수빈도 등 개별 수위파형을 변화시켜가면서 제방 안정성에 미치는 영향 정도와 합리적인 수위파형특성을 제안하였다. 평가결과, 문산제 조립토 제방의 설계수위파형은 최대 57시간 이상의 평수위상승시간 및 53시간 이상의 홍수위지속시간 등을 반영할 것을 제안하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1444-1452
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• 2011

At present, Kyungbu high-speed railway is operated with 300km/h, Honam high-speed railway is being constructed with 350km/h, and the development for the overhead contact line system is to be conducted for the next-generation high-speed railway with the speed of 400km/h. It is necessary to set up the specification and criteria for the key parts such as dropper, termination clamp and tension insulator for the 400km/h railway line. In this paper, the specification and the criteria for dropper, termination clamp and tension insulator has been reviewed and proposed in order to secure long-term reliability and stability under the maximum speed of 400km/h. Also, the specification, criteria and international standards for 300km/h class and 350km/h class railway line system and the international standards related with the insulators have been reviewed, compared and analysed.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1991년도 가을 학술발표회 논문집
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• pp.102-107
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• 1991

This study a reliability based design criteria for the Pile foundation, Which is common type of bridge founfation, and also proposes the theoretical bases limit state equations of stalbility analvsis of Pile foundation and the uncertainty measuring algorithms of each equation are also derived by MFOSM using the pile reations of displacement method, Terzaghi's bearing capacity formula, and chang's lateral load formula. The Level of uncertainties comesponding to these algorithms are proposed approprite values considering our actuality. It may be asserted that the proposed LRFD reliability based design criteria for the pile foundation may have to be incorporated in to the current Highway Bridge Design codes as a design provision corresponding to the USD(or LFD) provisions of the current Highway Bridge Design Code.

• 한국해양공학회지
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• 제18권6호
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• pp.101-107
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• 2004

In this paper, the design criteria of future container crane for megaships are investigated. The current loading/unloading capacity of a typical container crane, roughly 30 moves/hr, is too law to meet the requirements of future super containerships, which are expected over 15,000 TEU. After examining the transition of containerships through the years and studying the research trend in developed countries, the specifications of the container crane that can Meet a 15,000 TEU containership are proposed. The structure, trolley and hoist mechanism, outreach, backreach, capacity, speeds, durability, and stability of the future container crane are described.

• 대한물리의학회지
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• 제6권1호
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• pp.51-58
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• 2011

Purpose : This study was designed to identify the effects of carrying bag positions (None, left hand, right hand, left shoulder, right shoulder) on static balance. Methods : Fourteen healthy adult females participated in the this study. The exclusion criteria were orthopedic or neurologic disease, predominant left side. Measurements were performed initial effects. Results were evaluated by OSI, APSI, and MLSI in the biodex stability system. Results : There are among the three assessments (overall stability index(OSI), antero-posterior stability index (APSI), medio-lateral stability index(MLSI) significants difference for the carrying bags positions (None bag, left hand, right hand, left shoulder, right shoulder)(p<.05). The post-hoc test revealed a significant difference between none bag and both left hand and left shoulder in the OSI, APSI, MLSI (p<.05). Also, comparing the carrying positions significant difference between right hand and both left hand and left shoulder in the MLSI (p<.05). Conclusion : The results suggest that none dominant side with carrying bag improve more imbalance than none bag and right hand of dominant with carrying bag improve more balance than non dominant side. When comparing the four carrying bag conditions, right hand was more effective than another conditions in static balance.

• International Journal of Aeronautical and Space Sciences
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• 제12권4호
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• pp.305-317
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• 2011

This paper presents an overview on flutter boundary prediction in tests which is principally based on a system stability measure, named Jury's stability criterion, defined in the discrete-time domain, accompanied with the use of autoregressive moving-average (AR-MA) representation of a sampled sequence of wing responses excited by continuous air turbulences. Stability parameters applicable to two-, three- and multi-mode systems, that is, the flutter margin for discrete-time systems derived from Jury's criterion are also described. Actual applications of these measures to flutter tests performed in subsonic, transonic and supersonic wind tunnels, not only stationary flutter tests but also a nonstationary one in which the dynamic pressure increased in a fixed rate, are presented. An extension of the concept of nonstationary process approach to an analysis of flutter prediction of a morphing wing for which the instability takes place during the process of structural morphing will also be mentioned. Another extension of analytical approach to a multi-mode aeroelastic system is presented, too. Comparisons between the prediction based on the digital techniques mentioned above and the traditional damping method are given. A future possible application of the system stability approach to flight test will be finally discussed.

• Journal of Power Electronics
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• 제16권3호
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• pp.1163-1175
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• 2016

In recent years, microgrids have been the focus of considerable attention in distributed energy distribution. Microgrids contain a large number of power electronic devices that can potentially cause negative impedance instability. Harmonic impedance is an important tool to analyze stability and power quality of microgrids. Harmonic impedance can also be used in harmonic source localization. Precise measurement of microgrid impedance and analysis of system stability with impedances are essential to increase stability. In this study, we introduce a new square wave current injection method for impedance measurement and stability analysis. First, three stability criteria based on impedance parameters are presented. Then, we present a new impedance measurement method for microgrids based on square wave current injection. By injecting an unbalanced line-to-line current between two lines of the AC system, the method determines all impedance information in the traditional synchronous reference frame d-q model. Finally, the microgrid impedances of each part and the overall microgrid are calculated to verify the measurement results. In the experiments, a simulation model of a three-phase AC microgrid is developed using PSCAD, and the AC system harmonic impedance measuring device is developed.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.12-23
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• 2021

In the conventional experiment to assess the towing operations, the towing stability of the towed vessel has been evaluated under the condition without lateral motion of the tug-boat. However, the tug-boats may have a lateral force to change the direction of the towed vessel. In this study, experiments have been conducted considering unsteady conditions in the towing system. First, a towing test system in a Circular Water Channel (CWC) using the conventional experimental method is built. Second, the towing characteristics of the towed vessel are investigated using the conventional method, and they are compared with other research results and stability discriminant criteria. Third, the lateral motion of the tug-boat was modeled as a sinusoidal motion using a forced oscillation device changing frequency and amplitude. Finally, the discussion is given in terms of both towing- and course-stability of the towed vessel according to the lateral motion of the tug-boat.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.477-482
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• 1989

In this paper, the effect of coefficient quantization error is analyzed for digital PID controllers. Stability margins are used as peformance criteria, and the statistical wordlength concept is adopted for coefficient wordlength selection. Finally, an illustrative example is given.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.178-182
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• 2004

To establish the design criteria for construction of the rubble mound on improved ground, two kinds of analyses for the soil deformation behavior and the slope stability were performed on various cases for rubble mounds, soft grounds and back fills with application of the finite element method and the Bishop simplified method. The horizontal displacements and settlements at the crest of rubble mounds were analyzed as a function of the safety factor of embankments. The analyzed result shows that the soil movement increases considerably when the safety factor of rubble mounds is lower than 1.3.