• Title/Summary/Keyword: Optimal Operation

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A Study on Economic Analysis Algorithm for Energy Storage System Considering Peak Reduction and a Special Tariff (피크저감과 특례요금제를 고려한 ESS 경제성 분석 알고리즘에 관한 연구)

  • Son, Joon-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.10
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    • pp.1278-1285
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    • 2018
  • For saving electricity bill, energy storage system(ESS) is being installed in factories, public building and commercial building with a Time-of-Use(TOU) tariff which consists of demand charge(KRW/kW) and energy charge(KRW/kWh). However, both of peak reduction and ESS special tariff are not considered in an analysis of initial cost payback period(ICPP) on ESS. Since it is difficult to reflect base rate by an amount of uncertain peak demand reduction during mid-peak and on-peak periods in the future days. Therefore, the ICPP on ESS can be increased. Based on this background, this paper presents the advanced analysis method for the ICPP on ESS. In the proposed algorithm, the representative days of monthly electricity consumption pattern for the amount of peak reduction can be found by the k­means clustering algorithm. Moreover, the total expected energy costs of representative days are minimized by optimal daily ESS operation considering both peak reduction and the special tariff through a mixed-integer linear programming(MILP). And then, the amount of peak reduction becomes a value that the sum of the expected energy costs for 12 months is maximum. The annual benefit cost is decided by the amount of annual peak reduction. Two simulation cases are considered in this study, which one only considers the special tariff and another considers both of the special tariff and amount of peak reduction. The ICPP in the proposed method is shortened by 18 months compared to the conventional method.

Clinical and Neuroimaging Outcomes of Surgically Treated Intracranial Cysts in 110 Children

  • Lee, Eun-Jung;Ra, Young-Shin
    • Journal of Korean Neurosurgical Society
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    • v.52 no.4
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    • pp.325-333
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    • 2012
  • Objective : The indications and optimal surgical treatments for intracranial cysts are controversial. In the present study, we describe long-term clinical and neuroimaging results of surgically treated intracranial cysts in children. The goal of this study is to contribute to the discussion of the debate. Methods : This study included 110 pediatric patients that underwent surgeries to treat intracranial cysts. Endoscopic cyst fenestrations were performed in 71 cases, while craniotomies and cyst excisions (with or without fenestrations) were performed in 30 patients. Cystoperitoneal shunts were necessary for nine patients. Long-term results were retrospectively assessed with medical and neuroimaging records. Results : Clinical and radiological improvement was reported in 87.3% and 92.8% of cases, respectively, after endoscopic neurosurgery, and in 93.3% and 100% using open microsurgery whereas 88.9% and 85.7% after shunt operation. There were no statistical differences in clinical outcomes (p=0.710) or volume reductions (p=0.177) among the different surgeries. There were no mortalities or permanent morbidities, but complications such as shunt malfunctions, infections, and subdural hematomas were observed in 56% of the patients that had shunt operations. A total of 13 patients (11.8%) underwent additional surgeries due to recurrences or treatment failures. The type of surgery performed did not influence the recurrence rate (p=0.662) or the failure rate (p=0.247). Conclusion : Endoscopic neurosurgeries are less invasive than microsurgeries and are at least as effective as open surgeries. Thus, given the advantages and complications of these surgical techniques, we suggest that endoscopic fenestration should be the first treatment attempted in children with intracranial cysts.

Surgical Results of Selective Median Neurotomy for Wrist and Finger Spasticity

  • Kwak, Kyung-Woo;Kim, Min-Su;Chang, Chul-Hoon;Kim, Sang-Woo;Kim, Seong-Ho
    • Journal of Korean Neurosurgical Society
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    • v.50 no.2
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    • pp.95-98
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    • 2011
  • Objective : This study aimed to evaluate the surgical outcomes of selective median neurotomy (SMN) for spastic wrist and fingers. Methods : We studied 22 patients with wrist and finger spasticity refractory to optimal oral medication and physical therapy. The authors evaluated spasticity of the wrist and finger muscles by comparing preoperative states with postoperative states using the modified Ashworth scale (MAS). We checked patients for changes in pain according to the visual analog scale (VAS) and degree of satisfaction based on the VAS. Results : The preoperative mean MAS score was 3.27±0.46 (mean±SD), and mean MAS scores at 3, 6, and 12 months after surgery were 1.82±0.5, 1.73±0.7, and 1.77±0.81 (mean±SD), respectively. On the last follow-up visit, the mean MAS score measured 1.64±0.9 (mean±SD). Wrist and finger spasticity was significantly decreased at 3, 6, and 12 months after the operation (p<0.01). The preoperative mean pain VAS score was 5.85±1.07 (mean±SD), and the mean pain VAS score on the last follow-up visit after surgery was 2.28±1.8 (mean±SD). Compared with the preoperative mean pain VAS score, postoperative mean pain VAS score was decreased significantly (p<0.01). On the basis of a VAS ranging from 0 to 100, the mean degree of patient satisfaction was 64.09±15.93 (mean±SD, range 30-90). Conclusion : The authors propose SMN as a possible effective procedure in achieving useful, long-lasting tone and in gaining voluntary movements in spastic wrists and fingers with low morbidity rates.

Primary Malignant Melanoma in the Pineal Region

  • Park, Jae-Hyun;Hong, Yong-Kil
    • Journal of Korean Neurosurgical Society
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    • v.56 no.6
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    • pp.504-508
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    • 2014
  • A 59-year-old male patient had 5-month history of gait disturbance and memory impairment. His initial brain computed tomography scan showed 3.5×2.8cm sized mass with high density in the pineal region. The tumor was hypointense on T2 weighted magnetic resonance images and hyperintense on T1 weighted magnetic resonance images with heterogenous enhancement of central portion. The tumor was totally removed via the occipital transtentorial approach. Black mass was observed in the operation field, and after surgery, histopathological examination confirmed the diagnosis of malignant melanoma. Whole spine magnetic resonance images and whole body 18-fluoro-deoxyglucose positron emission tomography could not demonstrate the primary site of this melanoma. Scrupulous physical examination of his skin and mucosa was done and dark pigmented lesion on his left leg was found, but additional studies including magnetic resonance images and skin biopsy showed negative finding. As a result, final diagnosis of primary pineal malignant melanoma was made. He underwent treatment with the whole brain radiotherapy and extended local boost irradiation without chemotherapy. His preoperative symptoms were disappeared, and no other specific neurological deficits were founded. His follow-up image studies showed no recurrence or distant metastasis until 26 weeks after surgery. Primary pineal malignant melanomas are extremely rare intracranial tumors, and only 17 cases have been reported since 1899. The most recent case report showed favorable outcome by subtotal tumor resection followed by whole brain and extended local irradiation without chemotherapy. Our case is another result to prove that total tumor resection with radiotherapy can be the current optimal treatment for primary malignant melanoma in the pineal region.

Distributed Computing Models for Wireless Sensor Networks (무선 센서 네트워크에서의 분산 컴퓨팅 모델)

  • Park, Chongmyung;Lee, Chungsan;Jo, Youngtae;Jung, Inbum
    • Journal of KIISE
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    • v.41 no.11
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    • pp.958-966
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    • 2014
  • Wireless sensor networks offer a distributed processing environment. Many sensor nodes are deployed in fields that have limited resources such as computing power, network bandwidth, and electric power. The sensor nodes construct their own networks automatically, and the collected data are sent to the sink node. In these traditional wireless sensor networks, network congestion due to packet flooding through the networks shortens the network life time. Clustering or in-network technologies help reduce packet flooding in the networks. Many studies have been focused on saving energy in the sensor nodes because the limited available power leads to an important problem of extending the operation of sensor networks as long as possible. However, we focus on the execution time because clustering and local distributed processing already contribute to saving energy by local decision-making. In this paper, we present a cooperative processing model based on the processing timeline. Our processing model includes validation of the processing, prediction of the total execution time, and determination of the optimal number of processing nodes for distributed processing in wireless sensor networks. The experiments demonstrate the accuracy of the proposed model, and a case study shows that our model can be used for the distributed application.

Modeling and Analysis of Vehicle Detection Using Roadside Ultrasonic Sensors in Wireless Sensor Networks (WSN 기반 노변 초음파 센서를 이용한 차량인식에 대한 모델링 및 분석)

  • Jo, Youngtae;Jung, Inbum
    • Journal of KIISE
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    • v.41 no.10
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    • pp.745-761
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    • 2014
  • To address the problems of existing traffic information acquisition systems such as high cost and low scalability, wireless sensor networks (WSN)-based traffic information acquisition systems have been studied. WSN-based systems have many benefits including high scalability and low maintenance cost. Recently, various sensors are studied for traffic surveillance based on WSN, such as magnetic, acoustic, and accelerometer sensors. However, ultrasonic sensor based systems have not been studied. There are many issues for WSN-based systems, such as battery driven operation and low computing power. Thus, power saving methods and specific algorithms with low complexity are necessary. In this paper, we introduce optimal methodologies for power saving of ultrasonic sensors based on the modeling and analysis in detail. Moreover, a new vehicle detection algorithm for low complexity using ultrasonic data is presented. The proposed methodologies are implemented in a tiny microprocessor. The evaluation results show that our algorithm has high detection accuracy.

Bus Architecture Analysis for Hardware Implementation of Computer Generated Hologram (컴퓨터 생성 홀로그램의 하드웨어 구현을 위한 버스 구조 분석)

  • Seo, Yong-Ho;Kim, Dong-Wook
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.4
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    • pp.713-720
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    • 2012
  • Recently, holography has received much attention as the next generation visual technology. Hologram is obtained by the optical capturing, but in recent years it is mainly produced by the method using computer. This method is named by computer generated hologram (CGH). Since CGH requires huge computational amount, if it is implemented by S/W it can't work in real time. Therefore it should use FPGA or GPU for real time operation. If it is implemented in the type of H/W, it can't obtain the same quality as S/W due to the bit limitation of the internal system. In this paper, we analyze the bit width for minimizing the degradation of the hologram and reducing more hardware resources and propose guidelines for H/W implementation of CGH. To do this, we performs fixed-points simulations according to main internal variables and arithmetics, analyze the numerical and visual results, and present the optimal bit width according to application fields.

A Study on the Dynamic Export Yard Planning Considering Pattern of Coming-in Containers (반입 패턴을 고려한 동적 수출 장치장 운영 계획에 관한 연구)

  • Lee, Jong-Ho;Shin, Jae-Young
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2007.12a
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    • pp.337-339
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    • 2007
  • The productivity of container terminal is usually regarded same as the productivity of quay crane. Operation of quay crane for the export is started from picking up a container in yard block. In doing so, smooth flow of container is vital to maximize the productivity of quay crane. Improvement of quay crane's productivity means improvement of entire productivity in container terminal, which reinforces the competitiveness of terminal consequently. Setting effective plan is essential to improve work flow from yard to quay crane. For optimal plan, it is necessary to gather information about exact time schedule of come-and-go containers for loading, amount of containers that will be come to terminal. Generally, the arrival time of containers and the amount of containers are definite and predictable. However, in the case of export container, the arrival time of containers is random and unpredictable. This study examines the pattern of coming-in containers as time goes in container yard and provides the solution to how to plan export yard considering the change of state in terminal and adapt it to container yard plan

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Implementation of ACS-based Wireless Sensor Network Routing Algorithm using Location Information (위치 정보를 이용한 개미 집단 시스템 기반의 무선 센서 네트워크 라우팅 알고리즘 구현)

  • Jeon, Hye-Kyoung;Han, Seung-Jin;Chung, Kyung-Yong;Rim, Kee-Wook;Lee, Jung-Hyun
    • The Journal of the Korea Contents Association
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    • v.11 no.6
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    • pp.51-58
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    • 2011
  • One of the objectives of research on routing methods in wireless sensor networks is maximizing the energy life of sensor nodes that have limited energy. In this study, we tried to even energy use in a wireless sensor network by giving a weight to the transition probability of ACS(Ant Colony System), which is commonly used to find the optimal path, based on the amount of energy in a sensor and the distance of the sensor from the sink. The proposed method showed improvement by 46.80% on the average in energy utility in comparison with representative routing method GPSR (Greedy Perimeter Stateless Routing), and its residual energy after operation for a specific length of time was 6.7% more on the average than that in ACS.

Designing Revenue Sharing Contract for Irrational Newsvendors (소매상의 비합리성을 고려한 공급사슬의 수익 공유 계약 설계에 대한 연구)

  • Lee, Jung Min;Seo, Yong Won
    • Journal of the Korean Operations Research and Management Science Society
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    • v.41 no.2
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    • pp.101-127
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    • 2016
  • Irrational ordering decisions of supply chain members have been gaining growing importance in the area of supply chain management. Irrational ordering behaviors that deviate from the profit maximizing decisions in the newsvendor settings have observed with human experiments in recent research. These behaviors can be modeled with several typical decision bias elements. This bias in ordering decisions affects the performance of supply chain contracts designed based on the assumption that the supply chain members make optimal decisions, making it necessary to design supply chain contracts by considering the irrationality. The purpose of this research is to derive a method to design the revenue sharing contract that considers human irrationality in ordering decisions. This research considers a simple two-echelon supply chain consisting of one supplier and one retailer, where the supplier is assumed to be perfectly rational while the retailer making newsvendor type ordering decisions displays irrational ordering behaviors. Under this environment, this research analytically models the revenue sharing contract to maximize the total supply chain profit or the supplier's own profits while considering the three decision bias patterns of the retailer, which include the pull-to-center effect, the prospect theory, and the increased subjective sensitivity to the revenue sharing ratio. Irrationality parameters are measured through human experiments based on which and through numerical simulations, we showed that significant improvements in the supply chain performance can be achieved.