• 물과 미래
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• 제23권4호
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• pp.499-507
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• 1990

홍수기중의 실시간 저수지 운영을 위해서는 매시간 on-line으로 입력된 자료와 예측치로부터 시간별 최적방류량을 구해야 한다. 이를 위해서 댐하류의 홍수피해를 최소화하고 홍수 말기의 용수보존을 고려하는 무의 모형의 기법을 발표한 바 있다. 본 논문에서는 홍수시의 대청댐의 단일저수지 운영을 위해 모형을 적용하고 결과를 검토하며, 과거의 측정된 유입량과 방류량자료도 검토한다. 초기저수위를 달리하여 각 재현 기간별 홍수수문곡선을 다루고, 강우유출 모형으로부터 얻은 예측유입량을 구하여 운영한 뒤에 실제값과 비교하였다. 연구결과에 의하면 예측유입량의 불확실성을 고려하기 위해 위험계수를 적용하면 홍수조절용량을 효율적으로 이용할 수 있다.

• 한국시뮬레이션학회논문지
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• 제24권2호
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• pp.11-17
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• 2015

유한버퍼를 갖는 시스템에 대한 분석은 광범위하게 연구되어 왔다. 하지만, 상수 공정시간을 갖는 시스템에 대해서도 안정 대기시간에 대한 고차평균과 꼬리확률에 대한 간결한 표현식은 소개된 적이 없다. 유한버퍼로 인한 차단현상으로 유발되는 복잡성 때문에 일반적인 대기행렬이론은 이를 적절히 다루지 못한다. 본 연구에서는 max-plus 대수를 활용한 기존 연구결과로 부터 상수 공정시간과 DBR (Drum-Buffer-Rope) 재고규칙을 따르는 라인생산시스템에서의 대기시간에 대한 간결한 표현식을 도출하였다.

• 한국지열·수열에너지학회논문집
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• 제8권2호
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• pp.61-69
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• 2012

Geothermal heat pump(GHP) systems have been shown to be an environmentally-friendly, efficient alternative to traditional cooling and heating systems in both residential and commercial applications. Although some experimental work related to performance evaluation of GHP systems with vertical borehole ground heat exchangers for commercial buildings has been done, relatively little has been reported on the performance simulation of these systems. The aim of this study is to evaluate the cooling and heating performance of the GHP system with 30 borehole ground heat exchangers applied to an commercial building($1,210m^2$) in Seoul. For this purpose, a typical design procedure was involved with a combination of design parameters such as building loads, heat pump capacity, circulating pump, borehole diameter, and ground effective thermal properties, etc. The cooling and heating performance prediction of the system was conducted with different prediction methods and then each result is compared.

• 전력전자학회논문지
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• 제25권5호
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• pp.369-375
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• 2020

Distribution energy resources have been increasing in recent years. However, output power is limited for distribution network stability. This study proposes an active distribution network that can reconfigure distribution lines by using an active phase controller. A conventional distribution network has a fixed structure, whereas an active distribution network has a variable structure. Therefore, the latter can increase the output power of distribution energy resources and decrease the overload of distribution line facilities. An active phase controller has two operation modes for minimizing circulating current during dynamic reconfiguration. In this study, voltage and current control algorithms are proposed for active phase controllers. The simulation of the proposed methods for active phase controllers is performed using PSIM software.

• Geomechanics and Engineering
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• 제3권2호
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• pp.117-130
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• 2011

The methods of design available for geocell-supported embankments are very few. Two of the earlier methods are considered in this paper and a third method is proposed and compared with them. In the first method called slip line method, plastic bearing failure of the soil was assumed and the additional resistance due to geocell layer is calculated using a non-symmetric slip line field in the soft foundation soil. In the second method based on slope stability analysis, general-purpose slope stability program was used to design the geocell mattress of required strength for embankment. In the third method proposed in this paper, geocell reinforcement is designed based on the plane strain finite element analysis of embankments. The geocell layer is modelled as an equivalent composite layer with modified strength and stiffness values. The strength and dimensions of geocell layer is estimated for the required bearing capacity or permissible deformations. These three design methods are compared through a design example. It is observed that the design method based on finite element simulations is most comprehensive because it addresses the issue of permissible deformations and also gives complete stress, deformation and strain behaviour of the embankment under given loading conditions.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.568-572
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• 2003

The height of valve body is limited to 30mm in the cook-top style gas valves for the domestic gas ranges. But the all the safety specifications of KS should be fulfilled and the magnetic power unit(MPU) should be installed in the valve body for the safety reason. The length of MPU body is longer than the 30mm that it should be located in the square direction of the knob shaft and therefore the implementation of the lever mechanism to transmit the press motion of the knob to the MPU valve is very difficult. In this paper, the hinged lever with inclined plate is used to transmit the press motion of the knob to the MPU valve. The analysis of the gas flow with using the commercial software of FLOW-3D shows that the gas flow capacity is fit for the domestic gas range. The performance and responsibility of the valve is tested for the mass production and the test results shows that the valve can be installed in the commercial gas range.

• 조명전기설비학회논문지
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• 제13권1호
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• pp.21-30
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• 1999

전력용 변압기의 절연 열화를 탐지하기 위한 연구가 오래 전부터 연구되어 왔으며 절연유에 함유된 연소성 가스분석 기술이 주로 활용되고 있다. 최근들어 고압 대용량화에따른 사고 파급효과가 커지게 되면서 on-line 탐지시스템의 필요성이 대두되면서 부분방전 신호 검출법이 연구되기 시작하였다. 본 연구는 부분방전 신호 검출법 중에서 탐촉자의 탈착이 용이한 초음파 신호 측정법에서 가장 큰 문제점인 잡음신호 분리를 위한 연구이다. 신호원의 개수와 위치를 측정할 수 있으므로 측정된 초음파 신호가 부분방전에 의한 것인지 외부 잡음인지를 구별할 수 있으며 변압기의 절연열화 판단에 한층 신뢰성을 향상시킬 수 있게 되었다.

• 대한안전경영과학회지
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• 제14권4호
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• pp.259-264
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• 2012

Automobile market was grown up by 1.7% at the first half of 2012 comparison with 2011 in China and this growth trend will be continued for a while. Under this market environment the China automobile companies expand the production capacity and result in heightening the intense competition for companies. This paper deals with the more efficient production line and production logistics through SPS(Synchronized Production System) with construction of MES(Manufacturing Execution System) in H automobile company in China. In plastic painting line we can simultaneously prepare the production quantity and delivery time according to assembly production plan by introducing MES. We can reduce the excess production and result in extreme reduction of inventory.

• Earthquakes and Structures
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• 제19권6호
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• pp.445-457
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• 2020

An ultra-high voltage (UHV) transmission system has the advantages of low circuitry loss, high bulk capacity and long-distance transmission capabilities over conventional transmission systems, but it is easier for this system to cross fault rupture zones and become damaged during earthquakes. This paper experimentally and numerically investigates the seismic responses and collapse failure of a UHV transmission tower-line system crossing a fault. A 1:25 reduced-scale model is constructed and tested by using shaking tables to evaluate the influence of the forward-directivity and fling-step effects on the responses of suspension-type towers. Furthermore, the collapse failure tests of the system under specific cross-fault scenarios are carried out. The corresponding finite element (FE) model is established in ABAQUS software and verified based on the Tian-Ma-Qu material model. The results reveal that the seismic responses of the transmission system under the cross-fault scenario are larger than those under the near-fault scenario, and the permanent ground displacements in the fling-step ground motions tend to magnify the seismic responses of the fault-crossing transmission system. The critical collapse peak ground acceleration (PGA), failure mode and weak position determined by the model experiment and numerical simulation are in relatively good agreement. The sequential failure of the members in Segments 4 and 5 leads to the collapse of the entire model, whereas other segments basically remain in the intact state.

• Earthquakes and Structures
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• 제25권1호
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• pp.57-67
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• 2023

The buckling of longitudinal reinforcements under seismic loading accelerates the degradation of the bearing capacity of reinforced concrete columns. The traditional hysteretic constitutive model of reinforcement, which does not consider buckling, usually overestimates the seismic performance of pier columns. Subsequent researchers have also proposed many models including the buckling effects. However, the accuracy of these hysteretic constitutive models proposed for simulating the buckling behavior is inadequate. In this study, based on their works, the influence of historical events on buckling is considered, the path of the re-tensioning phase is corrected by adjusting the boundary lines, and the positions of the onset buckling point and compressive buckling path during each buckling deformation are corrected by introducing correction parameters and a boundary line. A modified hysteretic constitutive model is obtained, that can more accurately reflect the buckling behavior of reinforcements. Finally, a series of hysteresis tests of reinforcements with different slenderness ratios were then conducted. The experimental results verify the effectiveness of the proposed modified model. Indicating that the modified model can more accurately simulate the equivalent stress-strain relationship of the buckling reinforcement segment.