• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.292-296
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• 2010

본 연구에서는 상대적으로 소규모 홍수저감시설인 천변저류지의 설치를 통하여 대규모 유역 하도 전체에서의 홍수위 저감효과를 평가하고 그 효율을 극대화 하는 방안을 제시하였다. 본 연구에 적용한 다목적 최적화 기법(Multi-objective Optimization)으로는 NSGA-II(Non-dominated Sorting Genetic Algorithm II) 알고리즘을 적용하였으며 천변저류지 설치에 따른 수위 영향구간 분석 및 유역 전체 하도구간에서 전반적으로 발생하는 수리, 수문학적인 변화 평가 및 천변저류지 최적 조합을 선정하기 위하여 천변저류지의 용량을 최소화하면서 하도 전 구간에서의 수위 저감량을 최대화할 수 있도록 최적화 알고리즘의 목적함수를 설정하였다. 천변저류지 설치에 따른 홍수량의 변화를 해석하기 위하여 안성천 유역에 대하여 동역학적 홍수추적을 수행하였으며 저류형 구조물의 설치에 따른 홍수량 저감효과 및 그에 따른 홍수위의 변화를 동시에 해석하기 위하여 UNET 모형을 기반으로 한 HEC-RAS 부정류 해석을 실시하였다. 천변저류지 조합별로 다양한 경우의 수가 존재하므로 HEC-RAS 구동 모듈인 HECRAS Controller를 Visual Basic으로 코딩된 최적화 알고리즘 프로그램과 연동함으로써 각 경우의 수별로 동역학적 홍수추적 및 부정류 해석을 실시함으로써 천변저류지 조합별 각 측점에서의 홍수량 및 홍수위를 산정하여 저류지 용량을 최소화하면서 각 하도 측점별 수위저감량을 최대화 하는 최적해 집단(Pareto Front)을 산정하여 제시하였다.

• Journal of the Korea Society of Computer and Information
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• v.12 no.5
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• pp.273-284
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• 2007

This paper studies a periodic review inventory model with an e-MarketPlace transaction in reconfigurable manufacturing system(RMS). A decision maker can expand/reduce production capacity/quantities and/or replenish/dispose inventories from/to e-MarketPlace urgently to satisfy the stochastic demands. If inventories are replenished or disposed through e-MarketPlace, this leadtime is shorter than the production leadtime, but unit purchasing or selling cost is more expensive than that of expanding capacity or reducing production quantities respectively. Henceforth, trade-off on these alternatives is considered. In addition to this, in order to consider the economy of scale, our model includes the fixed cost for purchasing from e-MarketPlace and capacity expansion. We use dynamic programming and K convexity methods to characterize the nature of the optimal policy. Finally, We present the optimal inventory control policy which is composed by the combinations of a base stock and (s,S) type policy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1A
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• pp.12-17
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• 2009

We consider an OFDM based multiple AF relaying systems. Since the channel between first hop (source station-relay station) and second hop (relay station -destination station) varies independently, the subcarrier in the first hop can be paired to another subcarrier in the second hop for the increase of the system capacity. The conventional pairing which uses the brute force searching requires large complexity while giving optimal pairing for maximum system capacity. In this paper, we present sub-optimal subcarrier pairing scheme with low complexity. Every RS firstly pairs the subcarrier with the highest channel gain in the first hop to the subcarrier with highest channel gain in the second hop. The pair with the highest SNR among all the pairs is determined as final selected pair and the corresponding subcarriers are not selected at other RSs in the next paring iteration. This process is repeated until all the subcarriers are paired. Simulation results show the proposed pairing scheme achieves near optimal performance with low complexity.

• Journal of Korea Water Resources Association
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• v.52 no.4
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• pp.291-300
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• 2019

If pipes are damaged in a water distribution network (WDN), adjacent valves are closed to isolate the pipes for repair. Due to the closed valves, parts of WDN are isolated from water supply sources. The isolated area is divided into Intended Isolation Area (IIA) and Unintended Isolation Area (UIA). The IIA occurs by intention to isolate the damaged pipe, while UIA is unintentionally disconnected from the sources due to IIA. Thus, the extension of isolated area and suspended flows are mainly affected by number and location of installed valves in WDN. In this study, optimization models were developed to determine optimal valve locations in WDN. In a single-objective model, total water supply suspension is minimized, while a multi-objective model intends to simultaneously minimize the suspended flow and valve installation cost. Optimal valve placement results obtained from both models were compared and analyzed using a sample application network.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.302-302
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• 2022

최근 태풍, 집중호우로 인한 홍수피해가 빈번히 발생함하고 있다. 특히 상류에 저수지가 있을 경우 홍수조절을 통해 하류지역의 홍수피해를 저감하기도 하지만 급작스런 방류량의 증가 등으로 인해 하류지역의 피해가 증가되는 경우도 있다. 따라서 하류지역 홍수피해 저감을 위해 저수지의 홍수관리기능에 대한 관심도가 높아지고 있다. 대규모 다목적댐의 경우 다양한 저수지운영룰을 통해 수문을 운영하고 있어 홍수조절기능을 충분히 수행하고 있지만, 농업용저수지는 홍수관리에 있어 수문조작 전문성의 부족과 운영룰의 미정립 등으로 인해 취약성을 가지고 있는 상황이다. 본 연구에서는 수문이 설치된 1백만m³이상의 저수지 중 성주저수지를 연구대상저수지로 선정하였다. 비상수문을 통한 사전방류방안과, 저수지운영을 연구하여 농업용저수지의 홍수조절용량 확보를 위한 사전방류방안에 대해 연구하였다. 저수지운영은 Auto ROM을 적용하였고 홍수조절용량 확보를 위하여 홍수기 수위관리기법 중 사전방류기법을 채택하였다. 사전방류기법은 모의기법에 의한 사전방류와 최적화기법에 의한 최적사전방류량을 결정하는 방법으로 연구하였다. 홍수기의 제한수위는 유효저수량의 70%인 EL.179.7m, 65%인 EL.178.8m, 60%인 EL.177.8m로 설정하여 분석하였다. 모의기법에 의한 사전방류방법은 초기수위는 만수위에서부터 1.0m씩 감소하였고, 비상수문은 0.5m씩 개방하여 4.0m까지 개방 하였다. 사전방류의 시간은 24hrs, 48hrs를 적용하였다. 최적화기법에 의한 사전방류방법은 초기수위는 모의기법과 동일하고 목표수위를 제한수위(70%, 65%, 60%)가 되는 최적방류량을 산정하고 최적방류량을 방류할 수 있는 수문의 개방높이를 분석하였다. 2012년, 2020년의 호우사상에 대해 사전방류가 없는 경우와 모의기법, 최적화기법에 의한 사전방류결과를 적용한 경우를 비교하여 검토하였다. 그 결과 제한수위 70%를 유지할 경우 2012년은 모의기법이 5.6%, 최적화기법이 5.4%의 방류량 감소효과가 있으며 2020년은 모의기법이 9.0%, 최적화기법이 8.8%의 방류량 감소효과가 있는 것으로 검토되었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.23-28
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• 2010

We propose a reference vector diversity method in multi-cell multi-user uplink system with the subspace interference alignment to obtain higher sum rate capacity. The proposed method transmits several reference vectors before the data transmission, and selects the best reference vector to maximize the cell sum rate. The proposed method provides higher sum-rate capacity compared with the previous interferenc alignment. Simulation result exhibits the proposed method improves the sum-rate capacity by 60%.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.11
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• pp.50-55
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• 2009

In this paper, a distributed amplifier is designed using distributed network synthesis that provides the optimum absorption capability of a capacitance. Transfer functions of filters, which consist of the amplifier, are synthesized by a low-pass Chebyshev approximation. Capacitances that a filter network can absorb are calculated as a function of its minimum insertion loss(MIL) and ripple. Active devices in a distributed amplifier are modeled as equivalent circuits by using their S-parameters, and their equivalent capacitances are absorbed into filter structures by properly adjusting the MIL and ripple of a transfer function. As an application example, a distributed amplifier with the gain of about 12.5dB is designed that operates over the frequency range between 0.1 and 7.5GHz. Experimental results prove that distributed network synthesis, which considers capacitance absorption capability, is useful to the design of distributed amplifiers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.905-911
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• 2005

We propose an efficient adaptive subcarrier selection scheme, in which the active subcarriers and their modulation and coding schemes (MCSs) are selected at the receiver, and subsequently conveyed to the transmitter using limited feedback We theoretically show that capacity maximization can be achieved by selecting subcarriers with highest signal-to-noise ratios (SNRs) and adapting the number of active subcarriers according to channel environments. Furthermore, an ordering based adaptive subcarrier selection algorithm is proposed to select the optimal active subcarriers with low complexity. Numerical results show that the proposed adaptive subcarrier selection scheme provides higher capacity than that obtained by water-filling approaches, even with limited feedback.

• Journal of Korean Society for Geospatial Information Science
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• v.5 no.2 s.10
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• pp.131-144
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• 1997

Traffic jam densified day by day is phenomenon to occur lack of the road capacity in comparison with traffic density, but lack of the road cannot be concluded by main cause of traffic ism. Because the central function of a city would be concentrated upon the downtown and traffic demand would not be evenly distributed by the classification of an hour. Therefore, this study based on the fact that each driver will select the route generating traffic delay very low when path choice from origin to destination in travel plan estimating the quality of passage could be maintained the speed he want will approach to a characteristic grasp of a road, traffic, driver changing every moment by traffic-demand of road increased as a geometrical series with analysis a classification of a street, a intersection along the path on traffic density and highway capacity analysis the path using GIS techniques about complex street network, also will get the path of actual optimum for traffic delay trend creating under various condition the classification per a hour, a day of week and an incident through network such as analysis for traffic generation zone adjacent about street, intersection, afterward will expect the result increasing efficiency of the road-use through a good distribution of traffic by optimum-path choice, accordingly will prepare the scientific, objective, appropriate basis to decide the reasonable time of a road-widen and expansion through section analysis along a rate of traffic volume vs. road capacity.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.90-96
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• 2000

The optimum cooking conditions for large scale continuous gas cooker were studied with three varieties of rice. Optimum soaking time for the cooker was estimated to be 30 min at cooking temperature above $20{\circ}C$, while 60 min at cooking temperature below $10{\circ}C$. The ratio of water-to-milled rice giving the best eating quality was founded to be $1.41{\sim}1.48$, and corresponding moisture content of cooked rice ranged from 60 to 62% for different rice varieties. The optimum ratio of water to milled rice. (Chucheong) decreased from 1.50 to 1.37 with increase in the amount of milled rice from 4.0 to 6.5 kg in a cooking vessel. However, actual water uptake by rice (g water absorbed per g rice) on cooking was nearly constant value of 1.13, which means that evaporated water during cooking increases with decreasing the amount of rice in a cooking vessel.