• 한국수자원학회논문집
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• 제47권4호
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• pp.307-319
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• 2014

최근 지구온난화 및 기후변화에 의한 재난이 빈발하고 있어 미국이나 네덜란드 같은 제방 선진국에서는 특수한 경우 적게는 500년, 크게는 10,000년 빈도의 홍수위까지도 고려하는 극단적인 수준의 제방설계기준을 적용하고 있다. 우리나라도 지난 몇 년간 국가하천을 중심으로 대하천 정비사업이 추진되었다. 주로 하천준설과 제방증축 및 신축 등으로 진행된 사업에 의해 하천환경이 광범위하게 변화되었으나 제방의 안전과 관련된 하천환경 변화에 대응하는 구체적인 대응방안을 제시하지는 못하고 있는 실정이다. 따라서 본 연구에서는 제방침투감지시스템 Testbed가 구축되어 있는 낙동강 회천의 율지제를 대상으로 제방 안전성을 평가하였다. 평가방법은 간극수압 계측자료를 이용하여 2차원 지하수 침투모형인 SEEP/W를 이용하여 제방의 파이핑 현상을 분석하였으며, 제방의 형상과 홍수파형에 따른 침투현상을 모의하여 제방안정성을 평가하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.551-554
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• 2001

A necessity of remote control robots or various searching robots etc. that accomplish works given instead of human under long distance and extreme environment such as volcano, universe, deep-sea exploration and nuclear power plant etc. is increasing, and so the development and the research regarding these mobile robots are actively progressing. The wheel mobile robot or the track mobile robot have a sufficient energy efficiency under this en, but also have a lot of limits to accomplish works given which are caused from the restriction of mobile ability. Therefore, recently many researches for the walking robot with superior mobility and energy efficiency on the terrain, which is uneven or where obstacles, inclination and stairways exist, have been doing. The research for these walking robots is separated into fields of mechanism and control system, gait research, circumference environment and system condition recognition etc. greatly. It is a research field that the gait research among these is the centralist in actual implementation of walking robot unlike different mobile robots. A research field for gait of walking robot is classified into two parts according to the nature of the stability and the walking speed, static gait or dynamic gait. While the speed of a static gait is lower than that of a dynamic gait, a static gait which moves the robot to maintain a static stability guarantees a superior stability relatively. A dynamic gait, which make the robot walk controlling the instability caused by the gravity during the two leg supporting period and so maintaining the stability of the robot body spontaneously, is suitable for high speed walking but has a relatively low stability and a difficulty in implementation compared with a static gait. The quadruped walking robot has a strong point that can embody these gaits together. In this research, we will develope an autonomous quadruped robot with an asaptibility to the environment by selectry appropriate gait, element such as duty factor, stride, trajectory, etc.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권5호
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• pp.487-495
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• 2016

In the offshore project such as semi-submersible FPU and FPSO, the free fall type life boat called TEMPSC (Totally Enclosed Motor Propelled Survival Craft) has been installed for the use of an emergency evacuation of POB (People on Board) from the topside platform. For the design of life boat arrangement for semi-submersible FPU in the initial design stage, the drop height and launch angle are required fulfill with the limitation of classification society rule and Company requirement, including type of approval as applicable when intact and damage condition of the platform. In this paper, we have been performed the numerical studies to find proper arrangement for the life boats consider drop height in various environmental conditions such as wave, wind and current. In the calculations, the contributions from static and low frequency (LF) motions are considered from the hydrodynamic and mooring analysis as well as damage angle from the intact and damage stability analysis. Also, Air-gap calculation at the life boat positions has been carried out to check the effect on the life boat arrangement. The air-gap assessment is based on the extreme air-gap method includes the effect of 1st order wave frequency (WF) motions, 2nd order low frequency roll/pitch motion, static trim/heel and set down.

• 한국해양환경ㆍ에너지학회지
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• 제19권2호
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• pp.129-136
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• 2016

부유식 해양 구조물은 계류선을 이용하여 다양한 종류의 환경하중에 따른 표류를 방지하게 된다. 따라서 구조물의 초기 설계 단계에서 신뢰성 있는 계류선의 설계는 매우 중요한 요소라 할 수 있다. 하지만 다양한 해양의 하중 조건을 견딜 수 있도록 설계된 계류선이라 하더라도 극한 조건의 하중이나 오랜시간 반복된 피로 하중으로 인하여 파손되는 경우가 발생하기도 한다. 일부 계류선의 파손은 잔여 계류선의 장력 변화를 야기하여 경우에 따라서는 전체 구조물의 점진적인 파손을 초래한다. 본 연구에서는 10 MW급 부유식 파력-해상풍력 복합발전 구조물에 연결된 12개의 계류선 중 일부가 손상된 경우의 구조물의 과도 응답을 시간 영역의 수치 시뮬레이션을 통하여 해석하였다. 이를 통하여 일부 계류선 손상 시 전체적인 구조물의 거동 변화 및 잔여 계류선의 장력 변화를 확인하였다.

• Structural Engineering and Mechanics
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• 제32권2호
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• pp.283-300
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• 2009

The characteristic response of a structure to blast load may be divided into two distinctive phases, namely the direct blast response during which the shock wave effect and localized damage take place, and the post-blast phase whereby progressive collapse may occur. A reliable post-blast analysis depends on a sound understanding of the direct blast effect. Because of the complex loading environment and the stress wave effects, the analysis on the direct effect often necessitates a high fidelity numerical model with coupled fluid (air) and solid subdomains. In such a modelling framework, an appropriate representation of the blast load and the high nonlinearity of the material response is a key to a reliable outcome. This paper presents a series of calibration study on these two important modelling considerations in a coupled Eulerian-Lagrangian framework using a hydrocode. The calibration of the simulated blast load is carried out for both free air and internal explosions. The simulation of the extreme dynamic response of concrete components is achieved using an advanced concrete damage model in conjunction with an element erosion scheme. Validation simulations are conducted for two representative scenarios; one involves a concrete slab under internal blast, and the other with a RC column under air blast, with a particular focus on the simulation sensitivity to the mesh size and the erosion criterion.

• Steel and Composite Structures
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• 제42권4호
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• pp.501-511
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• 2022

Earthquake Resistant Design Philosophy seeks (a) no damage, (b) no significant structural damage, and (c) significant structural damage but no collapse of normal buildings, under minor, moderate and severe levels of earthquake shaking, respectively. A procedure is proposed for seismic design of low-rise reinforced concrete special moment frame buildings, which is consistent with this philosophy; buildings are designed to be ductile through appropriate sizing and reinforcement detailing, such that they resist severe level of earthquake shaking without collapse. Nonlinear analyses of study buildings are used to determine quantitatively (a) ranges of design parameters required to assure the required deformability in normal buildings to resist the severe level of earthquake shaking, (b) four specific limit states that represent the start of different structural damage states, and (c) levels of minor and moderate earthquake shakings stated in the philosophy along with an extreme level of earthquake shaking associated with the structural damage state of no collapse. The four limits of structural damage states and the three levels of earthquake shaking identified are shown to be consistent with the performance-based design guidelines available in literature. Finally, nonlinear analyses results are used to confirm the efficacy of the proposed procedure.

• KEPCO Journal on Electric Power and Energy
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• 제2권3호
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• pp.453-460
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• 2016

해상풍력터빈 시스템은 크게 상부의 풍력터빈과 하부의 지지구조로 구성된다. 해상풍력발전은 육상용 풍력발전보다 우수하다는 평가가 지배적이지만 육상용 풍력발전에서 고려되지 않는 파랑에 의한 주기적인 하중이 추가로 고려되기 때문에 다양한 외부 환경조건에 대하여 높은 안정성 확보가 요구된다. 본 연구에서는 전산유체역학 기법을 활용하여 설계된 해상풍력 하부구조에 대한 하중해석을 수행하고 유한요소해석을 통해 설계된 자중조절형 해상풍력 기초에 대한 구조 건전성을 검토하였다.

• 한국환경보건학회지
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• 제36권1호
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• pp.20-26
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• 2010

Temperature change has been shown to affect daily mortality even though different analytical methods produce different results. The effect of air pollution on the relationship between the temperature and the mortality is not large, although differences exist between temperature models. The aim of this study was to examine how the temperature change affected the daily mortality in Seoul by comparing the results from the temperature model using two study periods: one from 1994 to 2007 and the other from 1997 to 2007. Generally mean temperature, minimum temperature and Q10 temperature was derived as an optimal model, even though there are differences between age and cause of death. The analysis of threshold using total mortalities in all ages from 1994 to 2007 and from 1997 to 2007 showed that the number of the deaths increased 7.02% (95% CI: 6.06~7.98) and 2.51% (95% CI: 1.83~3.19), respectively as the mean temperature increased $1^{\circ}C$ from a threshold temperature of $27.5^{\circ}C$ and $25.7^{\circ}C$ respectively. These results indicated that the temperature has less effect on the number of death than does an extreme heat wave period.

• 한국해안·해양공학회논문집
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• 제28권2호
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• pp.92-100
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• 2016

응력집중계수를 이용하여 해상풍력발전기 트라이포드 지지구조물에 대한 신뢰성 해석을 수행하였다. 파랑과 풍하중의 극치분포함수는 POT방법을 사용하여 동적응답을 분석함으로써 추정되었다. 일계신뢰도법을 사용하여 신뢰성해석을 수행하였으며, 한계상태함수는 지지구조물의 이음부에서 발생하는 응력을 기반으로 정의하였다. 보 요소에서 계산된 응력에 응력집중계수를 곱하는 방법과 판 요소를 사용하여 계산하는 두 가지 방법으로 최대응력을 계산하여 신뢰성 해석을 수행하고 결과를 비교 분석하였다.

• 한국항공우주학회지
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• 제37권1호
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• pp.82-88
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• 2009

정상파 시스템의 구조는 발열반응으로 상변화를 하는 물질의 연속방정식에 의해 타당성을 검증받는다. 1차원 연속체 충격 구조 분석에서의 이론적 배경을 기반으로, 상변화 현상과 관련된 파의 마이크로 두께를 산출하였다. 상변화를 하는 물질로써, n-heptane은 탄화수소 연료의 증발과 응축 분석에 사용하였고, HMX은 고체 로켓 연료의 용융과 응고 분석에 사용하였다. n-heptane의 증발-응축 면의 산출 두께는 $10^{-2}$ 마이크론 차수이고, 반면에 HMX의 용융-응고 면의 산출 두께는 1 마이크론 차수 이다. 소개된 상면 두께 산출 이론은 실험적으로 얻을 수 없는 방대한 범위의 에너지 물질까지 계산범위를 확장시킬 수 있다.