• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.573-579
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• 2013

Hydrogen engine with homogeneous charged compression ignition can achieve high efficiency by high compression ratio and rapid chemical reaction rates spatially. However, it needs to expansion of the operation range with over-all load conditions which is very narrow due to extremely high pressure rise rate. The adoption of the lean boosting in a HCCI $H_2$ engine is expected to be effective in expansion of operation range since minimum compression ratio for spontaneous ignition is decreased by low temperature combustion and increased surround in-cylinder pressure. In order to grasp its possibility by using lean boosting in the HCCI $H_2$ engine, compression ratio required for spontaneous ignition, expansion degree of the operation range and over-all engine performance are experimentally analyzed with the boosting pressure and supply energy. As the results, it is found that minimum compression ratio for spontaneous ignition is down to the compression ratio(${\varepsilon}$=19) of conventional diesel engine due to decreased self-ignition temperature, and operation range is extended to 170% in term of the equivalence ratio and 12 times in term of the supply energy than that of naturally aspirated type. Though indicated thermal efficiency is decreased by reduced compression ratio, it is over at least 46%.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.15-23
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• 2022

The operation method of offline venues such as local festivals usually has problems such as the absence of real-time events and booth information, wasting time in the process of purchasing and receiving goods, and stagnating the movement of guests. This study increases the convenience of guests and managers by integrating all contents in the venue in the form of booth, thereby increasing the uniformity of event information and the efficiency of booth operation. In addition, a system was designed to minimize movement problems and improve performance by detecting the movement of guests within the venue and increasing the efficiency of arranging booths based on location data. It has been developed as a low-cost system that measures wireless packets with portable wireless LAN APs and control units. This has advantages in the operation of the venue, which consists of the installation and dismantling of variable booths in a short period of time. It is expected that the integrated operation of the venue will be utilized by linking the movement data of guests to activate visits and increase sales through data-based promotions.

• Plant Journal
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• v.18 no.4
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• pp.66-72
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• 2023

In order to respond to the demand for flexible operation of thermal power generation, development of natural sliding pressure operation that minimizes throttle loss by opening the turbine control valve 100% and maximize power generation efficiency in conjunction with ESS in order to quickly respond to fluctuations in the system frequency is required. The logic development of natural sliding pressure operation with ESS was developed to modify the existing logic at the power plant's top-level control logic such as the unit master, the boiler master and the turbine master. Cooperative control algorithms that complement the advantages and disadvantages of ESS operation (quick response, limited capacity) and power plant operation (slow response, continuous operation) not only improve efficiency when applied to actual power plants, but also respond quickly and flexibly to load demands to ensure system stability.

• Journal of Navigation and Port Research
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• v.46 no.1
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• pp.33-41
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• 2022

An important operational goal of a container terminal is to maximize the efficiency of the operation of quay cranes (QCs) that load and/or unload containers onto and from vessels. While the maximization of the efficiency of the QC operation requires minimizing the delay of yard tractors (YT) that transport containers between the storage yard and QCs, the delay is often inevitable because of traffic congestion. In this paper, we propose a method for learning a model that predicts traffic speed in a terminal using only YT operation data, even though the YT traffic is mixed with that of external trucks. Without any information on external truck traffic, we could still make a reasonable traffic forecast because the YT operation data contains information on the YT routes in the near future. The results of simulation experiments showed that the model learned by the proposed method could predict traffic speed with significant accuracy.

• Korean System Dynamics Review
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• v.17 no.2
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• pp.81-99
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• 2016

The service for waterworks is important infrastructure structuring the cities and the public properties affecting the health and the abundant lives of the residents at the same time. However, the waterworks project still has many problems in reality in spite of the continuous efforts from the nation, local governments and many related people in waterworks projects. From the aspect of the situation, this purpose of this study is to review the actual operation state and the operation principle on the basis of the accidents in the system and to suggest the policy leverages for accurate diagnosis of the waterworks project and for the efficient operation. The operation structure of the service for waterworks is the complicated system showing the overlapped forms of the relation with other various factors. Moreover, as this has been influenced by other external environments, it has flexible features that can be changed by unexpected factors even if the internally close causality has been established The domestic local operation of waterworks have been divided by an administrative district and it causes inefficiency in the aspect of the country and the local government with small sized of budget faces the insufficient investments. These phenomena have been shown in some small sized areas located in Chungcheongbuk-do and, making a realistic suggestion by the related local government to improve the waterworks operation project is urgent. For this reason, this study is to lead the policy leverages to increase the efficiency of the service for waterworks and to stabilize the structure of virtuous circle in the system. At first, the reformation of the waterworks structure should be performed after the various supports and system maintenance. At second, the service quality should be improved through the creativity in management and the consideration of the efficiency by the participation of private enterprises for waterworks service. At third, through the specialized waterworks operation, the quality improvement of the waterworks and satisfying the standard of natural environment should be related. In this context, the fundamental solutions for the problems of domestic waterworks service and finding realistic alternatives are considered to be the priority for the waterworks project to be operated efficiently.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.1
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• pp.47-56
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• 2010

At present, 265 national food waste recycling facilities have been operated by public facilities 95 and private facilities 160. it has continuously installed a food waste treatment facility from 1997. The government set up and implemented guidelines and inspection standards for the installation and operation of the facilities. However, unclear detailed examination items, designs and process standards for the installation procedures of the facilities are causing problems due to the unskilled operation management system, decrease in efficiency and defects of a facility. This study conducted mail and site surveys on 95 public food waste recycling facilities that it suggest the ways to operate facilities which minimize problems. At the result of investigation, a pre-treatment facility was not installed 2 systems(2 inputting facilities) and hopper covers and food was overloaded. also the transportation amount was excessive. In case of a main treatment facility, the secondary environmental pollution was caused by inexperienced operation and the efficiency of the facility was reduced due to excessive input of food. also the operation management standards of the facilities were inappropriate. The odor and food waste leachate treatment facility is investigated as problems that are unskilled operation, lack of regular inspection and inappropriate capacity of the treatment facility. Based on the problems found through the investigation, it suggested some ways of efficient operation. this study might contribute to minimize mistakes and defects and improve the efficiency of install and operation course of food waste recycling facilities through finding.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.877-882
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• 2014

The reduction of CO2 emission has been discussed in the Marine Environment Protection committee in the International Maritime Organization as the biggest causes of GHG for the purpose of indexing CO2 amounts released into the atmosphere from ships. Accordingly, various methods including the change in the hull design to improve energy efficiency, the coating development to reduce friction resistances, the additives development for improving thermal efficiency in an engine, the low-speed operation to reduce fuel consumptions, and etc. have been applied. The main engine of a ship is an electronic engine for improving the efficiency of the whole load area. However, marine generator engines still use mechanical drive engines in intake, exhaust, and fuel injection valve drive cams. In addition, most of marine generator engines in ships apply a part-load operation of less then 80% due to an overload protection system. Therefore, marine auxiliary diesel engine set at 100% load is necessary to readjust in order to efficient operation because of part-load operation. The objective of this study is to report the results of the part-load fuel consumption improvement by injection timing readjust to identifying the operational characteristics of a marine generator engine currently operated in a ship.

• Journal of Power System Engineering
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• v.17 no.5
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• pp.52-57
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• 2013

In this paper, an analysis on exergy efficiency of high-efficiency R717 OTEC power system for the efficiency and pressure drop in main components were investigated theoretically in order to optimize the design for the operating parameters of this system. The operating parameters considered in this study include turbine and pump efficiency, and pressure drop in a condenser and evaporator, respectively. As the turbine efficiency of R717 OTEC power system increases, the exergy efficiency of this system increases. But pressure drop in the evaporator of R717 OTEC power system increases, the exergy efficiency of this system decreases, respectively. And, in case of exergy efficiency of this OTEC system, the turbine efficiency and pressure drop in a condenser on R717 OTEC power system is the largest and the lowest among operation parameters, respectively.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1110-1116
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• 1993

A study on optimum operation performances of power efficiency, economy and exhaust emissions for a tractor was conducted. A mathematical model of multiple degree polynomial equation was applied to established the function of solid multiple parameter curves for specific fuel consumption (ge), cabon monoxide (CO) ,hydrcarbons (HC) and cabonaceous smoke (Rb). The optimum operation theorems for economy operation indicated by ge and for exhaust emissions described by Co , HC and Rb were obtained from analytical method and performance test data. The optimum operation theorems could exhibit optimum operation working points, curves, and regions. The optimum matching relations of engine speed and transmission parameters were analyzed by using computer simulation methods in accordance with the tractor specifications , actual farm working conditions in a typical drawbar pull work such as plowing , the optimum operation objective function, the ideal transmission ratio, practical gear shif ing positions and practical travel speed of the tractor TN55 medel. The results of the anlayzes indicated clearly that the optimum power efficient operation, energy saving and pollution reducing would be realized if the tractor would be operated according to theoptimum operation methods.

• Journal of Navigation and Port Research
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• v.35 no.1
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• pp.71-76
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• 2011

Recently, container terminal managers make an experiment on the double cycle and dual cycle operation, which ship loading and unloading were carried out simultaneously, for increasing the productivity of quay side. If, however, we make an experiment on dual cycle operation in a real job site, the efficiency is poor up to terminal operation method as YTs(Yard Tractors)' allocation method, QCs(Quay Cranes)' working speed, and position of export containers. Especially, using the existing yard operation method, it is difficult to support to dual and double cycle operation. Therefore, this paper examine more efficient terminal operation method, when terminal uses dual cycle operation. We developed a simulation model using simulation analysis software, Arena.