• 한국수자원학회논문집
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• 제43권2호
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• pp.167-185
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• 2010

설계홍수량산정과 관련하여 국내 실무에서 어려움을 겪는 가장 큰 문제 중 하나는 설계강우의 결정이다. 설계강우와 관련된 문제는 보다 세부적으로 살펴보면 강우의 시간분포와 강우의 공간분포 결정 문제로 집약될 수 있다. 본 연구에서는 강우의 시간분포와 공간분포에 관련된 문제를 해결할 수 있는 방법으로 티센가중치를 반영한 교호블록형 이동강우(TWBK moving storms)에 의한 설계홍수량 산정기법을 제안하고 그 적용성을 검토하였다. 100년 빈도 48시간 이동강우를 한강유역에 적용하여 그 결과를 기존 연구에서 홍수위 실측자료로부터 빈도해석에 의해 구한 홍수량과 비교하여 적용성을 입증하였다.

• 물과 미래
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• 제28권5호
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• pp.205-217
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• 1995

위천대표유역의 11년간의 단독강우사상 3,550개를 선별하여 Yen-Chow의 삼각형 및 사다리꼴, Huff, Pilgrim-Cordery 및 Mononobe의 방법에 의한 지속시간별 설계강우의 시간적분포 특성치를 제시하였다. Yen-Chow 방법의 삼각형분포의 특성치 $a^0$값은 0.44에서 0.50까지 분포하였고, 사다리꼴은 지속시간이 길어질수록 무차원 특성변수 $h^0$의 값이 점차 커지는 경향을 나타내었다. Huff 4분기법에 의한 분석결과는 2구간 강우가 지배적이고 3구간 강우가 낮은 분포를 나타내었다. 또한 Pilgrim-Cordery방법에서는 6시간까지는 전방위 강우형이고, 6시간이상은 점차 후방위로 변화하였다. Mononobe 방법은 시간별 강우량을 중앙집중형으로 나타내었다. 본 방법들의 적용성을 검토하기 위해 위천유역의 32개 관측 강우-유출자료를 이용하였고, 분석결과 Yen-Chow 방법의 삼각형분포가 비교적 재현성이 높게 나타났다. 이들 설계강의의 시간적분포모형들은 미계측유역의 유출해석에 중요한 수단을 제공할 것으로 판단된다.

• Wind and Structures
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• 제4권3호
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• pp.197-212
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• 2001

Observations of extreme wind speeds in the United Kingdom from 1970 to 1980, corrected for the influence of upwind ground roughness and topography, have been analysed using the recently-developed "Improved Method of Independent Storms" (IMIS). The results have been used to compile two new maps of base wind speed and to confirm the climatic factors in current use. One map is 'irrespective' of wind direction and the other is 'equally weighted' by direction. The 'equally weighted' map is expected to be more consistently reliable and appropriate for use with the climatic factors for the design of buildings and structures.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.253-260
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• 2005

최근 한반도를 내습하는 폭풍의 규모가 커지고 이에 대한 피해도 증가하고 있는 실정이어서 외해로 개방된 도서해역이나 연안역에 대한 재해방지를 위한 설계파라메터의 재산정이 필요한 상황이다. 기존의 설계 파라메타는 심해 설계파랑이나 바람자료만을 입력값으로 한 규칙파 모형으로 계산되어, 바람에 의한 파의 성장, 파랑 상호간의 간섭 및 에너지 재분포 등을 다룰 수 없는 문제점에 노출되어 있었다. 따라서, 본 연구에서는 이러한 파랑과 바람에 의한 파의 발달 및 상호간섭을 고려할 수 있는 정상상태 스펙트럼 모델의 하나인 SWAn(Simulation WAves Nearshore)모형을 이용하여 파랑변형 수치모의를 수행하였다. 연구 대상영역에 대한 기존의 설계 파라메타의 비교 결과, 기존 결과와 큰 차이를 나타내고 있으며, 특히, 이들 해역에서 도출된 결과는 장래 항만설계 및 방재 분야에서 널리 이용될 것으로 판단된다.

• Wind and Structures
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• 제29권6호
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• pp.489-497
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• 2019

Wind-adaptable design (WAD) provides a new method for super-tall buildings to lessen design conflicts between architectural prerequisites and aerodynamic requirements, and to increase the efficiency of structural system. Compared to conventional wind-resistant design approach, the proposed new method is to design a building in two consecutive stages: a stage in normal winds and a stage during extreme winds. In majority of time, the required structural capacity is primarily for normal wind effects. During extreme wind storms, the building's capacity to wind loads is reinforced by on-demand operable flow control measures/devices to effectively reduce the loads. A general procedure for using WAD is provided, followed by an exploratory case study to demonstrate the application of WAD.

• Ocean Systems Engineering
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• 제10권1호
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• pp.25-47
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• 2020

A study of the wave conditions for the Asabo offshore location at the Qua Iboe oil field in Eastern Nigeria has been carried out. Statistical analysis was applied to three (3) years of data comprising spectral periods, Tp and significant wave heights, H_s. The data was divided into two (2); data from October to April represents one set of data and data from May to September represents another set of data. The results were compared with similar studies at other locations offshore of West Africa. It was found that there is an absence of direct swellwaves from the Southern Ocean reaching the location under study (the Asabo site). This work suggests that the wave system is largely emanating from the North Atlantic storms. The presence of numerous islands near the Asabo location shields the site from effects of storms from south west and therefore swells from the Southern Ocean. It is noted that the local wind has little or no contribution. An H_s maximum of 2 m is noted at the Asabo offshore location. It is found that the Weibull distribution best describes the wave distribution at Asabo. Thus, the Weibull distribution is suggested to be adequate for long term prediction of extreme waves needed for offshore design and operations at this location.

• Wind and Structures
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• 제38권3호
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• pp.171-191
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• 2024

Wind Driven Rain (WDR) poses a significant threat to the building environment, especially in hurricane prone regions by causing interior and content damage during tropical storms and hurricanes. The damage due to rain intrusion depends on the total amount of water that enters the building; however, owing to the use of inadequate empirical methods, the amount of water intrusion is difficult to estimate accurately. Hence, the need to achieve full-scale testing capable of realistically simulating rain intrusion is widely recognized. This paper presents results of a full-scale experimental simulation at the NHERI Wall of Wind Experimental Facility (WOW EF) aimed at obtaining realistic rain characteristics as experienced by structures during tropical storms and hurricanes. A full-scale simulation of rain in strong winds would allow testing WDR intrusion through typical building components. A study of rain intrusion through a sliding glass door is presented, which accounted for the effects of multiple wind directions, test durations and wind speeds; configurations with and without shuttering systems were also considered. The study showed that significant levels of water intrusion can occur during conditions well below current design levels. The knowledge gained through this work may enhance risk modeling pertaining to loss estimates due to WDR intrusion in buildings, and it may help quantify the potential reduction of losses due to the additional protection from shuttering systems on sliding glass doors during winds.

• Wind and Structures
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• 제10권3호
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• pp.287-300
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• 2007

Wind action is a factor of fundamental importance in the structural design of light or slender constructions. Codes for structural design usually assume that the incident mean wind velocity is parallel to the ground, which constitutes a valid simplification for frequent winds caused by meteorological phenomena such as Extratropical Storms (EPS) or Tropical Storms. Wind effects due to other phenomena, such as thunderstorms, and its combination with EPS winds in so-called squall lines, are simply neglected. In this paper a model that describes the three-dimensional wind velocity field originated from a downburst in a thunderstorm (TS) is proposed. The model is based on a semi empirical representation of an axially-symmetrical flow line pattern that describes a stationary field, modulated by a function that accounts for the evolution of the wind velocity with time. The model allows the generation of a spatially and temporally variable velocity field, which also includes a fluctuating component of the velocity. All parameters employed in the model are related to meteorological variables, which are susceptible of statistical assessment. A background wind is also considered, in order to account for the translational velocity of the thunderstorm, normally due to local wind conditions. When the translation of the TS is caused by an EPS, a squall line is produced, causing the highest wind velocities associated with TS events. The resulting vertical velocity profiles were also studied and compared with existing models, such as the profiles proposed by Vicroy, et al. (1992) and Wood and Kwok (1998). The present model predicts horizontal velocity profiles that depend on the distance to the storm center, effect not considered by previous models, although the various proposals are globally compatible. The model can be applied in any region of interest, once the relevant meteorological variables are known, to simulate the excitation due to TS winds in the design of transmission lines, long-span crossings, cable-stayed bridges, towers or similar structures.

• 물과 미래
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• 제9권2호
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• pp.76-86
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• 1976

The 30-year design flood hydrograph for the Musim Representative Basin, one of the study basins of the International Hydrological Program, is synthesized by the method of unit hydrograph. The theory of unit hydrograph has been well known for a long time. However, the synthesis of flood hydrograph by this method for a basin with insufficient hydrologic data is not an easy task and hence, assumptions and engineering judgement must be exercized. In this paper, the problems often encountered in applying the unit hydrograph method are exposed and solved in detail based on the theory and rational judgement. The probability rainfall for Cheonju Station is transposed to the Musim Basin since it has not been analyzed due to short period of rainfall record. The duration of design rainfall was estimated based on the time of concentration for the watershed. The effective rainfall was determined from the design rainfall using the SCS method which is commonly used for a small basin. The spatial distribution of significant storms was expressed as a dimensionless rainfall mass curve and hence, it was possible to determine the hyetograph of effective design storm. To synthesize the direct runoff hydrograph the 15-min. unit hydrograph was derived by the S-Curve method from the 1-hr unit hydrograph which was obtained from the observed rainfall and runoff data, and then it was applied to the design hyetograph. The exsisting maximum groundwater depletion curve was derived by the base flow seperation. Hence, the design flood hydrograph was obtained by superimposing the groundwater depletion curve to the computed direct runoff hydrograph resulting from the design storm.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.432-437
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• 1998

Power systems have uncertain dynamics due to a variety of effects such as lightning, severe storms and equipment failures. The variation of the effective reactance of a transmission line due to a fault is an example of uncertainty in power system dynamics. Hence, a robust controller to cope with these uncertainties is needed. Recently fuzzy controllers have become quite popular for robust control due to its capability of dealing with unstructured uncertainty. Thus in this paper we design an adaptive fuzzy controller using an input-output linearization approach for the transient stabilization and voltage regulation of a power system under a sudden fault. Simulation results show that satisfactory performance is achieved by the proposed controller.