단일 경계조건을 갖는 단면에 대한 비틀림 상수계산

권민호,김진섭,서현수,임정희 한국복합신소재구조학회 2017 복합신소재구조학회 학술발표회 Vol.2017 No.04

Torsional constants of both rectangular cross section and circular cross section are induced by exact solution, and was easy to calculate since of simple shape. However, it is very difficult to calculate the torsional constant of both an arbitrary cross-section and a composite cross-section. In this study, a finite element formulation was proposed as a method to calculate the torsional constant of both an arbitrary cross-section and a composite cross-section. From the numerical study, numerical results was compared with exact solution.

Fabrication of Hydrophobic Surfaces using Copper Electrodeposition and Oxidation

권민호,지원영,주종남 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

The fabrication process of metallic hydrophobic surfaces was investigated using copper electrodeposition and oxidation. Hierarchical structures have well known advantages for producing super-hydrophobic surfaces. A micro-pillar array with a hierarchical structure of copper was fabricated through a sequential process of laser ablation followed by electrodeposition. Heat oxidation enhanced the hydrophobicity of both flat and micro-structured copper surfaces. Electrodeposition at higher current density gave a hierarchical structure with low surface energy, resulting from the presence of copper oxide. Fabricated surfaces with a depth of more than 100 micrometers display super-hydrophobicity. The effects of copper oxide and hierarchical structure were confirmed by an oxidation test of the fabricated structures, because the thickness of copper oxide was undetectable by XRD and XPS.

PSTS의 충전층 두께에 따른 해석적 성능평가

권민호,김진섭,서현수,임정희,문종윤 한국복합신소재구조학회 2017 복합신소재구조학회 학술발표회 Vol.2017 No.04

In this study, finite element analysis of korean precast concrete panels was performed and 3D infinite element modeling was used. Infinite elements can be formulated in time domain and nonlinear behavior analysis is possible. Based on the numerical results, the performance of the packing layer of korean precast concrete panels was examined.

CMIP5 기후모델에서 나타나는 열대저기압 생성빈도의 연진동과 경년변동성: 잠재생성지수의 이용

권민호 한국지구과학회 2012 韓國地球科學會誌 Vol.33 No.7

The potential for tropical cyclogenesis in a given oceanic and atmospheric environments can be represented by genesis potential index (GPI). Using the 18 Coupled Model Inter Comparison Project phase 5 (CMIP5) models, the annual cycle of GPI and interannual variability of GPI are analyzed in this study. In comparison, the annual cycle of GPI calculated from reanalysis data is revisited. In particular, GPI differences between CMIP5 models and reanalysis data are compared, and the possible reasons for the GPI differences are discussed. ENSO (El Nino and Southern Oscillation) has a tropical phenomenon, which affects tropical cyclone genesis and its passages. Some dynamical interpretations of tropical cyclogenesis are suggested by using the fact that GPI is a function of four large-scale parameters. The GPI anomalies in El Nino or La Nina years are discussed and the most contributable factors are identified in this study. In addition, possible dynamics of tropical cyclogenesis in the Northern Hemisphere Pacific region are discussed using the large-scale factors. 대기 및 해양의 대규모 환경에서 열대저기압 발생의 잠재적 빈도는 잠재생성지수(GPI; Genesis Potential Index)를 이용하여 예측할 수 있다. 본 연구에서는 18개의 CMIP5 기후모델을 이용하여 GPI의 연진동 및 경년변동성이 분석되었다. 비교를 위하여 재분석자료로부터 계산된 GPI의 연진동이 재조명되었다. 특히 CMIP5 기후모델과 재분석자료에 의한 GPI가 비교되었고, 그 차이에 대한 가능한 해석이 논의되었다. ENSO (El Nino and Southern Oscillation)는 열대 저기압 발생 및 경로에 영향을 주는 열대 기후현상이다. 잠재생성지수가 네 개의 대규모 매개변수의 함수임을 이용함으로써 열대저기압발생에 대한 역학적 해석이 제시되었다. 본 연구에서는 엘니뇨 혹은 라니냐 해에 GPI 편차를 논의하였고, 그 편차에 가장 영향을 많이 주는 인자를 찾았다. 또한 여러 대규모 인자를 활용하여 북태평양지역 열대저기압 발생에 대하여 가능한 기작을 논의하였다.

용접접합된 강골조 접합부의 거동

권민호,김진섭,임정희 한국복합신소재구조학회 2017 복합신소재구조학회 학술발표회 Vol.2017 No.04

Two steel-frame joint specimens with welding joint parts were constructed and evaluated. Two types of displacement load, monotonic and cyclic, were used to evaluate the steel-frame joint specimens. According to the experimental results, the maximum moment of the cyclic test results was 80% smaller than that of the monotonic test results. Local buckling was observed in the compression area of the H-beam flange. A finite element analysis model based on the experimental results was proposed to analyze the steel-frame joint specimens. The numerical results predicted the experimental behavior of the steel-frame joint specimens well. Therefore, it is possible to use the proposed finite element analysis model to evaluate middle- and low-rise steel-frame buildings constructed in South Korea.

NCEP 계절예측시스템과 정준상관분석을 이용한 북동아시아 여름철 강수의 예측

권민호,이강진 한국지구과학회 2014 한국지구과학회지 Vol.35 No.1

The seasonal predictability of the intensity of the Northeast Asian summer monsoon is low while that of the western North subtropical high variability is, when state-of-the-art general circulation models are used, relatively high. The western North Pacific subtropical high dominates the climate anomalies in the western North Pacific-East Asian region. This study discusses the predictability of the western North Pacific subtropical High variability in the National Centers for Environmental Prediction Climate Forecast System (NCEP CFS). The interannual variability of the Northeast Asian summer monsoon is highly correlated with one of the western North Pacific subtropical Highs. Based on this relationship,we suggest a seasonal prediction model using NCEP CFS and canonical correlation analysis for Northeast Asian summer precipitation anomalies and assess the predictability of the prediction model. This methodology provides significant skill inthe seasonal prediction of the Northeast Asian summer rainfall anomalies. 현재 최고 수준의 대순환 모형에서 북동아시아 여름몬순 강도의 계절예측 능력은 낮으나 북서태평양 아열대 고기압 강도의 예측률은 상대적으로 높다. 북서태평양 아열대 고기압은 북서태평양 지역 및 동아시아 지역에서 가장 주된기후 변동성이다. 본 연구에서 NCEP 계절예측시스템에서 예측된 북서태평양 아열대 고기압의 예측성에 대해 논의될것이다. 한편, 북동아시아 여름몬순의 경년변동성은 북서태평양 아열대 고기압과 높은 상관성을 가지고 있다. 본 연구에서는 이 관계에 근거하여, NCEP 계절예측시스템과 정준상관분석을 이용한 계절예측 모형을 제안하고 그 예측률을 평가하였다. 이 방법은 북동아시아 지역 여름철 강수량 편차에 대한 계절예측에 있어 통계적으로 유의한 예측성능을 제공한다.

북동아시아 지역 여름철 지상기온의 경년변동성과 관련된 대기의 원격상관

권민호,이강진 한국기상학회 2016 한국기상학회 학술대회 논문집 Vol.2016 No.10

강구조물 지지부의 강성도가 구조물 거동에 미치는 영향

권민호,박문호,장준호,박순응 한국전산구조공학회 2002 한국전산구조공학회논문집 Vol.15 No.1

일반적으로 모멘트 지지 강구조물은 유한요소법에 의해 이상화되고 해석되어 왔으며 기둥과 기둥의 연결부, 기둥과 보의 접합부의 정확한 비선형 해석 결과를 위해 많은 노력을 해온 반면에 기둥의 지지부에 대한 해석은 고정단 또는 힌지로 간단하게 이루어져 왔다 그러나 실제로 기둥의 지지부는 고정단도 힌지도 아닌 그 중간인 반강성으로 거동한다. 본 논문에서는 이러한 기둥 지지부를 반강성모델을 이용해서 해석하고 그 결과를 고찰하여 기둥 지지부의 강성 및 강도의 변화가 미치는 영향을 평가하였다. 미국 시방서에 의해 설계된 전형적인 두개의 3층 모멘트지지 강구조물을 이미 개발된 강성도법 및 유연도법에 기초한 7iber 유한 요소를 사용하여 해석하였다. 기등의 지지부는 고정단과 힌지사이에 있는 반강성 지지부를 모델하기 위해 다양한 강성도를 갖는 회전 스프링을 사용하였다. 실제의 기둥 지지부와 가깝게 모델된 반강성 지지부를 갖는 구조물의 해석 결과는 고정지지부를 갖는 구조물과 어느 정도 비슷한 결과를 보여주었다. 또한 pushover 해석과 비선형 시간 이력 해석을 통해 기둥 지지부의 강성도가 감소함에 따라 1층 보의 소요 처짐각(rotational demand)이 증가하는 현상이 관찰되었다 시공상의 문제 및 노화로 인한 기동 지지부의 강성도 감소는1층의 접합부에 대한 소요 터짐각의 증가를 유발하고 그것은 곧 soft-story mechanism을 유발하게 된다. Generally, the steel rigid frame has been analyzed using finite element analysis tools. While many efforts have been poured into the understanding and accurate prediction for the nonlinear behavior of the columns and beam-columns connections, the base of the columns are modeled as simply hinged or fixed. However, the base of the steel columns practically is neither fixed not hinged. It behaves as semi-rigid. In this paper, the supports of the columns we modeled as semi-rigid and the importance of such approach in moment-resisting columns is evaluated. Two typical buildings designed by the US specification are modeled and analyzed by the finite element based on stiffness method and flexibility method. The column bases of three-story buildings are modeled as rotational springs with a varying degree of stiffness and strength that simulates the semi-rigidity of the base. Depending on the degree of stiffness and strength, the semi-rigidity varies from the hinged to the fixed. Buildings with semi-rigid column bases behaves similarly to the building with fixed bases. It has been numerically observed through the pushover and nonlinear time history analyses that the decrease of the stiffness of the column base induces the rotational demand on the int air beams. an increase of rotation demands on the first store connections and lead to a soft-story mechanists Due often to the construction and environmental effects, undesired reduction of column base stiffness may cause an increase of rotation demands on the first store connections and lead to a soft-story mechanism.

콘크리트의 동결융해와 앵커의 부식에 따른 후 설치 앵커시스템의 성능평가

권민호,김진섭,정우영,권상원 한국구조물진단유지관리공학회 2013 한국구조물진단유지관리공학회 논문집 Vol.17 No.5

In this study, performance of the post-installed anchor system was evaluated with reduced strength of concrete and anchor. One of the post-installed anchors was selected to performance evaluation. Concrete strength was reduced by freeze-thawing test, and the post-installed anchor strength was reduced by corrosion test. The post-installed Anchor was installed in concrete of freezing and thawing and original concrete, and corroded anchor was installed in original concrete only. Anchor diameter and installation depth of the anchor were the variable for each specimen. Performance of post-installed anchor system of each specimen was evaluated by pullout test. Anchor diameter and installation depth of anchor, it may affect the performance of the post-installed anchor system from the experimental test results. Fracture mode of each post-installed anchor system had occurred differently depending on the durability of concrete and anchor. The anchor pullout strength from the experimental test results was used in order to compare with the results of CCD (Concrete Capacity Design) method, and CCD equation was modified. Modified equation was able to predict the anchor pullout strength of post-installed anchor system in Original concrete and freezing and thawing of concrete.

강골조 구조물의 보강을 위한 FRP 패널의 수치해석

권민호,김진섭,임정희 한국복합신소재구조학회 2017 복합신소재구조학회 학술발표회 Vol.2017 No.04

Numerical behavior of FRP(Fiber Reinforced Polymer) panel in steel frame structure was evaluated through the finite element analysis in this study. In order to numerical analysis, a experimental test results was used to develop a three dimensional finite element model of steel frame specimen. Numerical results of the steel frame specimen was well predicted the experimental behavior of steel frame specimen. Based on the developed three dimensional finite element model of steel frame specimen, the behavior of FRP panel in the steel frame specimen was evaluated. From the numerical analysis results, strength of the steel frame specimen with FRP panel was governed by FRP panel. Also, diagonal compression behavior governed the FRP panel in the steel frame specimen in the numerical analysis results.