• 응용통계연구
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• 제8권2호
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• pp.87-97
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• 1995

$2 \times 2$ 요인계획법에서 주효과가 전혀 존재하지 않거나 단지 하나만이 존재하는 경우의 교호작용을 위한 일반적인 F 검정과 순위변환을 이용한 F 검정 (FR 검정)의 제1종 오류율과 검정력은 전반적으로 비슷한 수준이나 정규분포보다는 지수분포하에서의 FR 검정의 검정력이 상당히 높은 수준임을 알 수 있다. 반면에 주효과들이 모두 존재하는 경우의 FR 검정의 제1종 오류율은 F 검정에 비하여 효과의 크기가 증가할수록 감소하고 주효과의 구성방법에도 영향을 받으며, 검정력은 효과의 크기와 표본의 크기를 크게할수록 증가하되 FR 검정의 검정력은 F 검정에 비하여 낮은 수준이며 주효과의 구성방법 및 모집단의 분포형태에 따라 민감하게 변화함을 알 수 있다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.464-467
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• 2010

Ice accretion on aircraft surface in icing condition induces external shape changes that may result in a hazard factor for aircraft safety. In case of aircraft main wing with high lift equipment, ice accretion is observed around leading edge and flap. During the design phase, location of ice accretion and associated aerodynamic characteristics must be investigated. In this study, icing effects on aerodynamic characteristics of the main wing section of KC-100 aircraft are investigated using an Eulerian-based FENSAP-ICE code in various icing conditions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.977-984
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• 2006

Generally main girders and steel piers of temporary bridges form the steel rahmen structure. In this study, the rational stability design procedure for main members of temporary bridges is presented using 3D system buckling analysis and second-order elastic analysis. 2 types of temporary bridges, which are possible to be designed and fabricated in reality, are chosen and the buckling design for them is performed considering load combinations of dead and live loads, thermal load, and wind load. Effective buckling length of steel piers, effects of live loads on effective length of main members, transition of ~id buckling modes, and effects of second-order analysis are investigated through case study of 2 temporary bridges.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.993-1000
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• 2006

Practical stability design method of main members of cable-stayed bridges is proposed and discussed through a design example. For this purpose, initial tensions of stay cables and axial forces of main members are firstly determined using initial shaping analysis of bridges under dead loads. And then the effective buckling length using system elastic/inelastic buckling analysis and bending moments considering $P-{\delta}-{\Delta}$ effect by second-order elastic analysis are calculated for main girder and pylon members subjected to both axial forces and moments, respectively. Particularly, load combinations of dead and live loads, in which maximum load effects due to live loads are obtained, are taken into account and effects of live loads on effective buckling lengths are investigated.

• Journal of Plant Biology
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• 제18권2호
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• pp.45-52
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• 1975

Effects of air pollutants on vegetation were reviewed and discussed with special reference to sulfur dioxide. Main contents were on the sources, meteorological factors, injury symptoms, relative sensitivity, growth/yield, indicator/diagnosis, combined effects, injury mechanism and effects on plant metabolism, injury diminishing measures, and future research needs.

• KEPCO Journal on Electric Power and Energy
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• 제8권1호
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• pp.5-7
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• 2022

KEPCO's plan is undergoing a trial operation to replace the open-loop section with ring main units configuration where underground distribution lines are installed, by linking the multi-way circuit breakers auto (MCA) on the power side of each pad-mounted transformer. However, ring main units application mentioned above may cause the ripple effects, when implementing the configuration without a study of protection coordination. Because ring main units with classical pre-set protection devices contribution in fault condition didn't consider yet. For the reliable ring main units operation, it is necessary to resolve several protection issues such as the protection coordination with substation side, prevention of the transformer inrush current. These issues can radically deteriorate the distribution system reliability Hence, it is essential to design proper protection coordination to reduce these types of problems. This paper presents a scheme of ring main units' configuration and MCA's settings of time-current curves to preserve the performance of protection coordination among the switchgears considering constraints, e.g. prevention of the ripple effects (on the branch section when a transformer failure occurs and the mainline when a branch line failure occurs). It was confirmed that the propagation of the failure for each interrupter segment could be minimized by applying the proposed TCC and the interrupter settings for the MCAs (branch, transformer). Further, it was verified that the undetected area of the distribution automation system (DAS) could be supplemented by having the MCA configurated ring main units operate first, instead of the internal protection equipment in the transformer such as the fuse, STP when a transformer failure occurs.

• 한국생산제조학회지
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• 제24권3호
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• pp.278-286
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• 2015

The effects of the main bearing stiffness combined with vertical non-torque force on the input load and shaft deflection of a gearbox were investigated for the three-point suspension drive train of a wind turbine. A finite element analysis model for the drive train was studied experimentally, and its applicability to the present study was verified. The results show that, as the main bearing stiffness is increased, the input load of the gearbox decreases, whereas the input shaft deflection increases. The stiffness component for the pitch moment has the largest influence on the gearbox input load. Although the gearbox life increases at a higher main bearing stiffness, the economic efficiency and durability of the entire drive train system should also be considered in the selection of the main bearing stiffness.

• Nuclear Engineering and Technology
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• 제32권1호
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• pp.67-76
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• 2000

Significant wall thinning due to flow accelerated corrosion(FAC）was recently reported in main feedwater pipes in 3 Korean pressurized water reactor(PWR) plants. The main feedwater pipes in one plant were repaired using overlay weld method at the outside of pipe, while those in 2 other plants were replaced with new pipes. In this study, the effect of the wall thinning in the main feedwater pipes on piping integrity was evaluated using finite element method. Especially, the effects of both the overlay weld repair and the stress concentration in notch-type thinned area on the piping integrity were investigated. The results are as follows : (1) The piping load carrying capacity may significantly decrease due to FAC. In special, the load carrying capacity of the main feedwater pipe was reduced by about 40% during about 140 months operation in Korean PWR plants. (2) By performing overlay weld repair at the outside of pipe, the piping load carrying capacity can increase and the stress concentration level in the thinned area can be reduced.

• 한국물환경학회지
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• 제23권3호
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• pp.356-366
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• 2007

In this paper a methodology is developed to prioritize replacement of water distribution pipes according to the economical efficiency of replacement and assess the long-term effects of water main replacement policies on water distribution systems. The methodology is implemented with MATLAB to develop a computer algorithm which is used to apply the methodology to a case study water distribution system. A pipe break prediction model is used to estimate future costs of pipe repair and replacement, and the economically optimal replacement time of a pipe is estimated by obtaining the time at which the present worth of the total costs of repair and replacement is minimum. The equation for estimating the present worth of the total cost is modified to reflect the fact that a pipe can be replaced in between of failure events. The results of the analyses show that about 9.5% of the pipes in the case study system is required to be replaced within the planning horizon. Analyses of the yearly pipe replacement requirements for the case study system are provided along with the compositions of the replacement. The effects of water main replacement policies, for which yearly replacement length scenario and yearly replacement budget scenario are used, during a planning horizon are simulated in terms of the predicted number of pipe failures and the saved repair costs.

• 수산해양교육연구
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• 제20권1호
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• pp.78-89
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• 2008

This study is intended to analyse the economic sensitivity of imported fishery products due to decrease in or elimination of tariff rates through the progress of free trade. Forty-seven species of fishes were selected for this study on the basis of the HS Code. The substitution and price effects were calculated using the price elasticities of both domestic and imported demands for fishery products under the assumption of 5% decrease in a tariff rate. Seven main economic variables were extracted from the fishery industry which can mediate the substitution and price effects. A multiple regression analysis was conducted to obtain the influence weights of these main economic variables on both effects. The order of sensitivity of the fishes was calculated using these weights. The 47 fish species were classified into four groups according to their sensitivity based on the means and the standard deviations of their total scores on seven main economic considerations. Nine fish species such as squids, hair tails, shellfishes, and crabs belonged to the hyper-sensitive group, whereas 15 fishes such as eels, sea breams, and sea weeds belonged to the sensitive group. Twelve species including common sea basses, cods, and abalones were among the less-sensitive group, and 11 species including skate rays and mud fishes comprised the non-sensitive group.