• Journal of Electrical Engineering and Technology
• /
• v.5 no.4
• /
• pp.530-537
• /
• 2010

By development of renewable energy and more efficient facilities in an increasingly deregulated electricity market, the operation cost of distributed generation (DG) is becoming more competitive. International environmental regulations of the leaking carbon become effective to reinforce global efforts for a low-carbon paradigm. Through increased DG, operators of DG are able to supply electric power to customers who are connected directly to DG as well as loads that are connected to entire network. In this situation, a community energy system (CES) with DGs is a new participant in the energy market. DG's purchase price from the market is different from the DG's sales price to the market due to transmission service charges and other costs. Therefore, CES who owns DGs has to control the produced electric power per hourly period in order to maximize profit. Considering the international environment regulations, CE will be an important element to decide the marginal cost of generators as well as the classified fuel unit cost and unit's efficiency. This paper introduces the optimal operation of CES's DG connected to the distribution network considering CE. The purpose of optimization is to maximize the profit of CES. A Particle Swarm Optimization (PSO) will be used to solve this complicated problem. The optimal operation of DG represented in this paper would guide CES and system operators in determining the decision making criteria.

• Journal of Chest Surgery
• /
• v.26 no.12
• /
• pp.915-919
• /
• 1993

The management of Patent Ductus Arteriosus[PDA] with heart failure and cardiac cachexia in premature infants have been a disturbing and controversial problem in the field of pediatric cardiovascular surgery.We analysed our experiences to determine the rationale of surgical closure of PDA in infants . During a period of 7 years from January 1986 to December 1992, 12 infants under 2 months of age underwent operations for "hemodynamically significant" PDA which had caused severe heart failure.There were 6 male and 6 female patients. Their mean gestational age was 33.8 weeks and their mean body weight was 1990 g. ranged from 710 g. to 2900 g. Mean age at operation was 28.5days. Seven patients had history of Indomethacin trial. All patients were operated with double ligation technique under general anesthesia.There was no mortality and blood transfusion was not necessary in any patient during the operation.In all cases, we could confirm the complete closure of PDA after operation by follow-up echocardiography.Two patients died during their hospital stay and 1 patient died at 6 months after operation. The causes of death were sepsis with congestive heart failure, necrotizing entero colitis and pneumonia respectively.We can not detect any operation related complication which resulted in permanent sequelae as well as delayed complications related to nerve damage. These results indicate that surgical ligation of PDA in infants with severe heart failure is relatively safe and effective.effective.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.7
• /
• pp.2603-2609
• /
• 2010

Currently at port, various trials about the improvement of operating method for raising operation efficiency of transferring equipment are made, but if the delay is occurred to quay crane due to individual team method in YT operation, the problem which even arranged YT should stop the work. Therefore, this study installed wireless location determining device within yard and measured the location of YT with real-time. Also, in order to raise the location determination effect, we converted operating method into pooling operation method and arranged YT. Through this study, we can trace the movement of YT with real-time and the work control method which anlayzes and evaluates congestion of yard objectively is prepared.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.26 no.3
• /
• pp.155-163
• /
• 2020

This paper conducted a study on the operation plan of the packaging system to enhance the logistics efficiency between the manufacturer and the distributor, whose prior research in the relevant field was insignificant. By identifying problems and improvements in the operation of the packaging system between domestic manufacturers and distributors through the Retail Ready Packaging. The institutional aspects were investigated to confirm that the mediation role of government and social organizations was required to resolve issues (χ2 = 148.916, p < 0.001), and that guidelines that gathered diverse opinions for the rational operation of the packaging system were essential, while institutional aspects are needed to be supplemented to be willing to improve logistics efficiency (χ2 = 95.781, p < 0.001). In this study, even though the difference in perception between manufacturers and distributors is clear and the issue related to the operation of the packaging system is ongoing, if there is no effort to grasp the issue, the opinions between manufacturers and distributors will be left at odds and could become a social problem. Unnecessary interference from government and social organizations should be excluded, but the level of mediation to support win-win management in order to promote logistics standardization and reduce CO2 and national logistics costs can be explained as a catalyst for improving logistics efficiency through reasonable operation of the packaging system.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.9 no.3
• /
• pp.261-270
• /
• 2019

With the advent of the Fourth Industrial Revolution, multi-variety production in the up-to-date manufacturing environment is proceeding more rapidly whereby production planning and management have been getting more complicated. Moreover, the need to improve production efficiency through effective operation sequencing is further heightened. Fundamentally, the effective operation sequencing can reduce the set-up of the equipment, efficiently utilize the equipment, shorten the set-up time, and ultimately contribute to productivity improvement. This study deals with the problem of efficient operation sequencing in a situation where a single machine performs multiple operations. The complexity of the problem is very high when compared to the case where only one operation is performed on one machine, which is covered in most existing studies. In this paper, we propose an integer programming model to minimize the number of setups. This study aims at minimizing the number of mold replacement times in the process of processing a given production order for the wiring harness manufacturing process, which is one of the components of automobile electric field. In addition, brief case studies are presented to verify the validity of the proposed mathematical model.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.1241-1245
• /
• 2011

High RAM performance and efficient operation plan and maintenance equipment and policies are needed for improving the system availability performance such as punctuality and schedule adherence while reducing life cycle cost. Because railway systems are repairable, complex and have multi-echelon maintenance support structure, it is much complicated to set RAM performance targets and operation and maintenance plan. It is not easy to solve these problem by mathematical method and simulation can be consider for them. This article suggests the conceptual simulation model for analysing availability of railway system which has complex system structure and operation/maintenance environment.

• Proceedings of the IEEK Conference
• /
• 2000.06b
• /
• pp.40-43
• /
• 2000

The electrons and holes trapped in the tunneling oxide and interface-states generated in the Si/SiO$_2$ interface during program/erase (P/E) operations are known to cause reliability problems which can deteriorate the cell performance and cause the V$_{th}$ window close. This deterioration is caused by the accumulation of electrons and holes trapped in the oxide near the drain and source side after each P/E cycle. we propose three new erase schemes to improve the cell's endurance characteristics: (1)adding a Reverse soft program cycle after the source erase operation, (2)adding a detrapping cycle after the source erase operation, (3)adding a convergence cycle after the source erase operation. (3) is the most effective performance among the three erase schemes have been implemented and shown to significantly reduce the V$_{th}$ window close problem. And we are able to design the reliable periperal circuit of flash memory by using the (3).(3).

• Journal of international Conference on Electrical Machines and Systems
• /
• v.3 no.4
• /
• pp.451-457
• /
• 2014

Parallel operation systems have an advantage in that they can be constructed quickly and inexpensively by combining existing electric power converters. However, in this case, there is a peculiar problem in that a cross current flows between the electric power converters. To design a control system more simply and commonalize the core of combination reactors, we reviewed a system construction method for parallel operation systems constructed with three electric power converters.

• Journal of Korean Institute of Industrial Engineers
• /
• v.23 no.4
• /
• pp.645-660
• /
• 1997

An application of the genetic algorithm(GA) to the loading sequencing problem in port container terminals is presented in this paper. The efficiency of loading operations in port container terminals is highly dependent on the loading sequence of export containers. In order to sequence the loading operation, we hove to determine the route of each container handling equipment (transfer crane or straddle carried in the yard during the loading operation. The route of a container handling equipment is determined in a way of minimizing the total container handling time. An encoding method is developed which keeps intermediate solutions feasible and speeds up the evolution process. We determine the sequence of each individual container which the container handling equipment picks up at each yard-bay as well as the visiting sequence of yard-bays of the equipment during the loading operation. A numerical experiment is carried out to evaluate the performance of the algorithm developed.

• Journal of Chest Surgery
• /
• v.19 no.2
• /
• pp.306-312
• /
• 1986

The development of extracardiac valved conduits for establishment of RV-PA continuity has permitted repair of previously uncorrectable congenital heart anomalies and has facilitated the repair of other complex lesions. But the distressing problem of neointimal peel formation with eventual conduit obstruction in patients with Dacron valved conduits has led to the need for premature replacement in many patients. Therefore in the absence of pulmonary hypertension, hypoplastic pulmonary arteries, significant right ventricular dysfunction or unrepaired tricuspid regurgitation, preference of a valveless conduit to a valved conduit gives excellent results and may diminish the need for late reoperation. In our Hanyang University Hospital, the Rastelli operation was performed for the repair of pulmonary atresia with a valveless Gore-Tex conduit. The patient was operated on with good result. The CVP after operation was 8-13 mmHg at POD #0 and 4-6 mmHg from POD #3-4. Postoperatively the patient was acyanotic and had improved physical capacity compared with his preoperative status.