• 한국물환경학회지
• /
• 제28권6호
• /
• pp.833-842
• /
• 2012

In this study Window interface to Hydrological Simulation Program-FORTRAN (HSPF) developed by the United States Environmental Protection Agency (EPA) was applied to the upstream of Namgang watershed to estimate its applicability for estimating Delivery Ratio (DR) of water pollutants for Total Maximum Daily Load (TMDL). BASINS/HSPF which is selected in this study, is found to be appropriate for simulation of daily flow and water quality in target basins. DR was estimated utilizing discharge loads of unobserved sub-basin and delivery load of unobserved locations obtained not by actual evaluation but by simulation through validation and verification. Annual average DR of BOD, TN and TP were 0.97 ~ 1.50, 2.23 ~ 3.21, and 0.81 ~ 1.09 respectively. Net DR of dependent basins excluding influence of upstream basin was 1.50 ~ 1.70, 0.55 ~ 0.69, and 0.24 ~ 0.31, all of which are lower than those of independent basins area. Utilizing the model selected by this research, DR and Net DR of unobserved basins will be estimated, which will help determine priorities in management of basin areas.

• 산업경영시스템학회지
• /
• 제43권4호
• /
• pp.76-83
• /
• 2020

Postal logistics organizations are characterized as having high labor intensity and short response times. These characteristics, along with rapid change in mail volume, make load scheduling a fundamental concern. Load analysis of major postal infrastructures such as post offices, sorting centers, exchange centers, and delivery stations is required for optimal postal logistics operation. In particular, the performance of mail traffic forecasting is essential for optimizing the resource operation by accurate load analysis. This paper addresses a traffic forecast problem of postal parcel that arises at delivery stations of Korea Post. The main purpose of this paper is to describe a method for predicting short-term traffic of postal parcel based on self-similarity analysis and to introduce an application of the traffic prediction model to postal logistics system. The proposed scheme develops multiple regression models by the clusters resulted from feature engineering and individual models for delivery stations to reinforce prediction accuracy. The experiment with data supplied by main postal delivery stations shows the advantage in terms of prediction performance. Comparing with other technique, experimental results show that the proposed method improves the accuracy up to 45.8%.

• 한국물환경학회지
• /
• 제32권6호
• /
• pp.589-599
• /
• 2016

Implemented since 2004, TPLC (Total Pollution Load Control) is the most powerful water-quality protection program. Recently, uncertainty of prediction using steady state model increased due to changing water environments, and necessity of a dynamic state model, especially the watershed model, gained importance. For application of watershed model on TPLC, it needs to be feasible to adjust the relationship (mass-balance) between discharged loads estimated by technical guidance, and arrived loads based on observed data at the watershed outlet. However, at HSPF, simulation is performed as a semi-distributed model (lumped model) in a sub-basin. Therefore, if the estimated discharged loads from individual pollution source is directly entered as the point source data into the RCHRES module (without delivery ratio), the pollutant load is not reduced properly until it reaches the outlet of the sub-basin. The hypothetic RCHRES generated using the HSPF BMP Reach Toolkit was applied to solve this problem (although this is not the original application of Reach Toolkit). It was observed that the impact of discharged load according to spatial distribution of pollution sources in a sub-basin, could be expressed by multi-segmentation of the hypothetical RCHRES. Thus, the discharged pollutant load could be adjusted easily by modification of the infiltration rate or characteristics of flow control devices.

• 한국전자거래학회지
• /
• 제9권3호
• /
• pp.277-288
• /
• 2004

멀티미디어 컨텐츠의 전송은 대용량 및 비정형적인 데이터를 처리해야하는 특성을 해결하는 데 목적이 있다. 이를 지원하기 위한 멀티캐스팅 기술에 대한 연구가 최근 활발히 진행되고 있다 본 연구에서는 멀티미디어 컨텐츠를 안정적이고 신속하게 전송하기 위해, 서버 그룹간의 멀티캐스트 라우팅을 지원하는 기법을 제안한다. 서버 노드의 부하에 따른 가중치에 따라 라우팅을 하여, 부하가 가중된 노드를 고려하여 컨텐츠 전송의 효율을 높이는 방법으로, 가중치는 멀티캐스트 서버의 통신 부하에 따라 계산한다. CDN(Contents Delivery Network)에서 둘 이상의 ES(Edge Server)가 존재하는 경우, 지연이 적은 라우팅을 제공함으로써 멀티미디어 컨텐츠를 효과적으로 전송할 수 있다. 멀티캐스트 서버간의 라우팅 기법을 설계하고 분석을 통해 네트워크의 부하를 줄여 네트워크 지연이 감소됨으로써 전체 네트워크 성능이 향상됨을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권9호
• /
• pp.3094-3109
• /
• 2014

This paper proposes a load balanced reliable routing protocol called LBR (Load Balanced Reliable routing) in wireless networks. The LBR protocol transmits messages through a reliable path considering the balancing of the traffic load. Recently, the authors have proposed a multipath-based reliable routing protocol called MRFR, which is an appealing protocol for fault tolerant reliable data transmission. However, However, MRFR has no concern with the problem of load balancing, which results in increasing congestion and consuming high energy at some network nodes. As a result, the problem affects negatively the performance of the network. Taking account of load balancing as a route selection criteria can avoid routing through the congested nodes and allows to find better routes. In this paper, we extend MRFR by considering load balancing in the route discovery process of reliable communication. The simulation results showed that the proposed protocol outperforms AODV in terms of end-to-end delay, packet delivery radio, and average jitter. Compared to MRFR, the LBR protocol has the same packet delivery ratio, and obtains a better efficiency of load balancing.

• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2008년도 춘계학술발표논문집
• /
• pp.87-90
• /
• 2008

This paper deals with the analytical approach for the reliability assessment in radially operated distribution systems. The approach can estimate the expected reliability performance of distribution systems by a direct assessment of the configuration of the systems using the reliability indexes such as NDP(Non-Delivery Power) and NDE(Non-Delivery Energy). The indexes can consider the number and configuration of the load, but can not consider the characteristics of the load which is the one of the most important factor in the investment cost for the distribution systems. Therefore, This paper presents the new indexes considering the expected interruption cost for the load section and shows the effectiveness by simulating at the model systems.

• 대한환경공학회지
• /
• 제32권2호
• /
• pp.175-184
• /
• 2010

본 연구에서는 유역모형인 BASINS/HSPF와 연계하여 비점유달부하량을 유황별(갈수기, 저수기, 평수기 등)로 산정하는 방법을 개발하고, 이를 전남지역에 위치한 동복천 유역에 적용하여 그 효용성을 평가하였다. 동복천 유역에 대한 BASINS/HSPF 모형의 보정 검증결과는 유출유량, BOD 및 T-P의 신뢰도지수가 각각 1.59, 1.41, 1.28로서 실측값과 예측값의 유사성은 높게 나타났다. 이와 같이 구축된 BASINS/HSPF 모형을 사용하여 동복천 유역의 갈수기, 저수기, 평수기에 대한 BOD와 T-P 비점유달부하량을 각각 구하면, 연간 일평균 비점배출부하량과 대비하여 0.36과 1.09, 0.82와 2.19, 6.02와 16.90이였다. 이러한 결과는 비점유달부하량을 유황별로 산정하여 서로 다르게 반영할 필요성이 있음을 보여주고 있으며, 이러한 경우에 본 연구에서 개발한 유황별 비점오염유달부하량 산정방법은 유용하게 사용될 수 있을 것이다.

• 한국물환경학회지
• /
• 제25권5호
• /
• pp.792-802
• /
• 2009

The objective of this study is to construct the watershed management system with link of the non-point sources model and to estimate delivery ratio duration curves for various pollutants. For the total water pollution load management system, non-point source model should be performed with the study of the characteristic about non-point sources and loadings of non-point source and the allotment of pollutant in each area. In this study, daily flow rates and delivered pollutant loads of Nakdong river basin are simulated with modified TANK model and minimum variance unbiased estimator and SWAT model. Based on the simulation results, flow duration curves, load duration curves, and delivery ratio duration curves have been established. Then GIS analysis is performed to obtain several hydrological geomorphic characteristics such as watershed area, stream length, watershed slope and runoff curve number. As a result, the SWAT simulation results show good agreements in terms of discharge, BOD, TN, TP but for more exact simulation should be kept studying about variables and parameters which are needed for simulation. And as a result of the characteristic discharges, pollutants loading with the runoff and delivery ratios, non-point sources effects were higher than point sources effects in the small-scale test bed of Nakdong river basin.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 C
• /
• pp.1059-1062
• /
• 1998

This paper which can simulate FRIENDS(Flexible Reliable Intelligent Electrical eNergy Delivery System) model of distribution electrical system presents a new algorithm. In the operation of FRIENDS model, dispersed energy storage(DES) systems have an important role. We can use the active and reactive power of DES to control customer's voltage. In this, the former means load levelling operation and the later means voltage control operation of DES. We focus our research on load levelling operation of DES. We develope an algorithm to get an optimal capacity and operation schedule of DES and then apply it to the FRIENDS model. The results show the effectiveness of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권7호
• /
• pp.2354-2370
• /
• 2015

The advantages of employing SCTP-based Concurrent Multipath Transfer (CMT) have been demonstrated to be very useful for data delivery over multi-homed wireless networks. However, there is still significant ongoing work addressing some remaining limitations and challenges. The most important concern when applying CMT to data delivery is related to handling packet reordering and buffer blocking. Another concern on this topic is that current sender-based CMT solutions seldom consider balancing the overhead and sharing the load between the sender and receiver. This paper proposes a novel Receiver-driven Cooperation-based Concurrent Multipath Transfer solution (CMT-Rev) with the following aims: (i) to balance overhead and share load between the sender and receiver, by moving some functions including congestion and flow control from the sender onto receiver; (ii) to mitigate the data reordering and buffer blocking problems, by using an adaptive receiver-cooperative path aggregation model, (iii) to adaptively transmit packets over multiple paths according to their receiver-inspired sending rate values, by employing a new receiver-aware data distribution scheduler. Simulation results show that CMT-Rev outperforms the existing CMT solutions in terms of data delivery performance.