• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2134-2141
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• 2014

This paper addresses on a wind power system with BESS(Battery Energy Storage System). The concerned system consists of four parts: the wind speed production model, the wind turbine model, configure capacity of the battery energy storage, battery model and control of the BESS. First of all, we produce wind speed by 4-component composite wind speed model. Secondly, the maximum available wind power is determined by analyzing the produced wind speed and the characteristic curve of wind power. Thirdly, we configure capacity of the BESS according to wind speed and characteristic curve of wind speed-power. Then, we propose a control strategy to track the power reference. Finally, some simulations have been demonstrated to visualize the feasibility of the proposed methodology.

• 한국태양에너지학회 논문집
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• 제21권3호
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• pp.51-60
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• 2001

A greenhouse equipped with latent heat storage system was built to obtain various thermal properties, such as greenhouse air temperature, soil surface temperature, energy flow in latent heat storage, etc., which could be used in validation of greenhouse numerical model to be developed in this study. This numerical model expressed with Newton-Raphson method was programed by C-language and utilized to simulate greenhouse thermal behavior. Greenhouse air temperature and soil surface temperature predicted by the greenhouse model developed in this study were very close to the measured data obtained through almost 3 years of experiment. Therefore, it is concluded that the greenhouse model developed and verified by measured data could be utilized for simulating various thermal behaviors of greenhouses equipped with latent heat storage system to be used for energy saving purposes.

• 물과 미래
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• 제28권6호
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• pp.107-118
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• 1995

갈수기를 포함한 자연하천에서의 오염물질의 확산 및 이동 거동을 정확하게 예측하기 위하여 하천수로의 존재하는 저장대의 영향과 저장대에서의 오염물질의 저장 및 재방출 과정을 보다 정확하게 설명할 수 있는 수학적 모형을 개발하였다. 수학적 모형은 수치해석적인 방법에 의해 해를 구하고, 실험자료를 통해 검증하였다. 저장대에서의 오염물질의 저장과정을 설명하기 위한 두 개의 서로 다른 저장과정 부모형을 결합시킨 모형의 모의결과, 두 모형의 정확도에 있어서는 서로 대등하지만, 저장-확산 모형이 저장-교환 모형보다 저장 및 교환과정을 물리적으로 더욱 정확하게 표현할 수 있음이 밝혀졌다. 본 연구에서 개발된 저장-교환모형과 저장-확산 모형은 자연 하천으로 방류된 오염물질의 확산 및 혼합특성을 예측하는 모형으로서 종래의 1차원 확산모형에 비해 월등히 개선된 모형으로 판단된다.

• 한국방재학회 논문집
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• 제8권2호
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• pp.149-158
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• 2008

본 연구에서는 저류함수모형을 이용한 홍수유출분석의 시행에서 즘 더 정확한 모의가 가능할 수 있도록 유역에 대한 매개변수를 재 산정하였다. 매개변수의 산정을 위해 민감도분석을 실시하고, 한강유역을 대상으로 각 유역별 지형인자를 새로 추출하였으며, 이를 기준으로 홍수 모의를 통해 유역모형의 유출상수를 홍수직전유출고와의 관계로 회귀분석 하였다. 유역모형의 저류상수는 유역별 홍수사상에 따른 최적의 저류봉수식으로 도출하였으며, 산정된 매개변수를 이용한 보형의 수행 결과를 한국수자원공사의 K-Water(기준상수) 모형 및 한강홍수통제소 형과 비교하여 본 연루의 결과가 관측 수문곡선과 더 유사함을 제시하였다.

• Water Engineering Research
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• 제1권3호
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• pp.171-185
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• 2000

A mathematical model to adequately predict complex mixing characteristics of sorptive polluants in natural streams with pools-and-riffes has been developed. In this model, sorption of pollutants onto the bed sediment as well as mass storage and exchange in the storage zones were incorporated into one-dimensional mass balance equatins. The geometric and hydraulic characteristics of the pool-riffle sequences were properly conceptualized. Simulations with parameters of pool-and-riffle streams better fit the measured data in overall shape and peak concentration than simulations with parameters for uniform channels. The analyses on the characteristics of the storage zone model parameters reveal that a linear relationship between the logrithm of the storage zone volume ratio and a function of the friction factor exists. A linear relatiohship might also be tenatively assumed between the logarithm of the dimensionless mass exchange coefficient and the logarithm of the aspect ratio of the storage zone if some of the high values of the dimensionless mass exchange coefficient collected on the successive bed forms are excluded.

• 대한산업공학회지
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• 제27권4호
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• pp.328-336
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• 2001

In this paper, an approach is presented for determining the required storage capacity of a warehouse with leased public space. Storage assignment policies considered are randomized and class-based storage assignment policies. An analytic model for each of the storage policies is formulated with the objective of minimizing the cost of owned storage space and leased space while satisfying a desired service level of protection against space shortages. Cost functions used in the models are piecewise liear with fixed costs. For the models, algorithms are developed to generate optimal solutions. The approach is applied to the systems where the standard economic-order-quantity inventory model is used for all items being stored in the warehouse.

• 제어로봇시스템학회논문지
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• 제3권5호
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• pp.532-541
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• 1997

This article derives an analytic solution to determine the optimal size of multiple noncontinuous process and storage units. The total cost to be minimized consists of the setup cost of noncontinuous processing units and the inventory holding cost of feedstock/product storages. A novel approach, which is called PSW(Periodic Square Wave) model, is applied to represent the material flow among non-continuous units and storages. PSW model presumes that the material flow between unit and storage is periodic square wave shaped. The resulting optimal unit size has similar characteristics with the classical economic lot sizing model such as EOQ(Economic Order Quantity) or EPQ(Economic Production Quantity) model in a sense that the unit size is determined as the balance between setup and inventory holding cost. However, the influence of inventory holding cost of PSW model is different from that of EOQ/EPQ model. EOQ/EPQ model includes only the product inventory holding cost but PSW model includes all inventory holding costs around the non-continuous unit with proportional contribution. PSW model is suitable for analyzing interlinked process-storage system. The optimal lot size of PSW model is smaller than that of EOQ/EPQ model. This is quitea remarkable result considering that the EOQ/EPQ model has been is widely used since last half century.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.770-774
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• 2006

The determination of feasible design flood is the most important to control flood damage in river management. Model parameters should be calibrated using observed discharge but due to deficiency of observed data the parameters have been adopted by engineer's empirical sense. Storage coefficient in the Clark unit hydrograph method mainly affects magnitude of peak flood. This study is to estimate the storage coefficients based on the observed rainfall-runoff events at the four stage stations in the Hantan river basin. Model calibration is the process of adjusting model parameter values until model results match historical data. An objective function which is the percent difference between the observed and computed peak flows is available for measuring the goodness-of-fit between computed and observed hydrographs. By sensitivity analysis for the storage coefficient, it has been shown that the storage coefficients affect the peak flows. The Clark parameters adopted in the River Rectification Basic Plan have been estimated through an iterative process designed to produce a hydrograph with the peak flow.

• Journal of Biosystems Engineering
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• 제28권1호
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• pp.35-44
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• 2003

This study was conducted to develop proper model for cold storage facility that could of for uniform heat movement and air movement f3r green grocery and improve improper design of the existing container-type cold storage facility. For that reason, new model(dome-type) cold storage facility was developed using 3-D CFD(computational fluid dynamics) simulation. The size was 6m${\times}$6m${\times}$5m. Its size and configuration were same to simulation model. Unit cooler was designed to send cold air in 4 side ways. A dome-type cold storage facility showed uniform distributions of air temperature and velocity because cold air was forced to move down along the ceiling and the wall and then circulated to the unit cooler from the central part of the floor. Dome-type cold storage facility also showed by low wind velocity, below 1 m/s that could minimized cold damage and quality deterioration.

• 자원환경지질
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• 제50권2호
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• pp.159-170
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• 2017

다공성 구조의 장석과 주택 시방기준으로 제작된 바닥 축열층 모르타르의 열적 특성과 소비전력을 비교하였다. 실험을 위해 온수관이 설치된 2개의 실대형 모형을 제작하였다. 자외선 열화상 온도와 온도센서를 이용하여 가열과 냉각과정에서 축열층의 온도변화를 모니터링하였다. 시험동의 축열층은 $20-30^{\circ}C$ 구간의 온도 범위의 가열조건에서 $2-3.5^{\circ}C$ 높은 온도를 보였고 목표 온도에 도달하는 시간이 단축되었다. 온수관에서 멀어질수록 $4-4.8^{\circ}C$ 이상의 차이를 보였고 이는 장석 기반의 모르타르 축열층이 열적 평형에 빨리 도달하는 것을 지시한다. 가열 온도 $30^{\circ}C$를 기준으로 산정한 소비전력은 2.2배 차이를 보였고 단계별 온도 상승에서 소비전력은 66% 절감되었다. 냉각에서 시험동의 표면온도는 지속해서 $2^{\circ}C$ 이상 높았고 축열로 인해 보일러의 재가동 시간이 연장되는 것을 고려하면 에너지 효율은 더 증가할 것이다.