• The KIPS Transactions:PartA
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• v.13A no.3 s.100
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• pp.191-198
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• 2006

Today's portable electric consumer devices, which are operated by battery, tend to integrate more multimedia processing capabilities. In the multimedia processing devices, multimedia system-on-chips can handle specific algorithms which need intensive processing capabilities and significant power consumption. As a result, the power-efficiency of multimedia processing devices becomes important increasingly. In this paper, we propose a reconfigurable data caching architecture, in which data allocation is constrained by software support, and evaluate its performance and power efficiency. Comparing with conventional cache architectures, power consumption can be reduced significantly, while miss rate of the proposed architecture is very similar to that of the conventional caches. The reduction of power consumption for the reconfigurable data cache architecture shows 33.2%, 53.3%, and 70.4%, when compared with direct-mapped, 2-way, and 4-way caches respectively.

• Journal of Internet of Things and Convergence
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• v.8 no.1
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• pp.23-29
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• 2022

The product to be developed in this study is a heat recovery device which generates steam or hot water at high temperature and high pressure by heating water using exhaust gas from diesel engine, gas engine, gas turbine, etc. as an exhaust gas boiler off heat boiler(EGB) type for ship and power generation. The steam vapor or the created warm water is used as the power source required for the steerage heating and hot water facility or the HFO heating of the ship, and the turbine drive. The principle of waste heat boilers serves to heat water as high temperature exhaust gas with heat pass through the tube of the boiler. The heated water is a structure that is sent to a cabin or turbine device in the form of steam. In this study, the objective of this study is to maximize the efficiency by increasing the heat transfer surface by replacing the tube which is the heat transfer part of EGB with the plate tube.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1035-1042
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• 2014

Reducing the friction of engine parts is an important issue in engine design. The loss of energy in the piston assembly due to mechanical friction ranges from 40 to 55%, and there is an increase in the total energy of about 5% if the friction of the piston can be removed. In order to reduce the friction loss at the level of each engine part, it is necessary to perform a comparative analysis with other engines to determine the important factors affecting the energy loss. Several studies have been performed to analyze the lubrication based on hydrodynamic modeling, since a piston lubrication system has dimensions in the nanoscale to microscale domain. Therefore, it is necessary to determine the correlations between the molecular and continuum systems. In this study, we investigated the friction changes due to the various interactions between molecules in the wall/fluid interface, where a microscopic movement of the oil film occurs along the cylinder liner of the engine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.318-321
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• 2005

The design and performance test of a low NOx gas turbine combustor to be used in 55kW class micro-gasturbine engine was performed in KARI's combustion test facility. The combustor is reverse flow-can type for easy installation of injector and other parts and LNG is used as fuel. The performance targets are $99.5\%$ combustion efficiency, less 10ppm NOx, $30\%$ patten factor and $4\%$ pressure loss. Most of the performances required are satisfied.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.361-366
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• 2001

A mim turbo-shaft engine of 50HP for UAV, which can be easily modified to turbo-prop and turbo-jet engine by sharing the core engine and has many applications to civilian demands and munitions, will be developed This kind of micro gas turbine engine has been developed mostly by the corporations which have special technology but are small in its scale. Especially, the gas turbine engine can be easily applied to other fields and developed by domestic technology, so that the sharing of technology is planed to realize through the cooperations with academies and research institutes. In this paper, the gas turbine engine, which has the compressor ratio of 3.8, the turbine inlet temperature of l180K and the engine speed higher than 100,000 rpm, is composed of centrifugal compressor, combustor, gas generator turbine, free power turbine and gear box. The competitiveness of the gas turbine engine can be obtained from minimizing its cost by the utilization of domestic infrastructure for the performance test and the decisive outsourcing.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.150-158
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• 2018

Numerical simulation and experimental study on the thermal flow field of the micro turbojet engine have been carried out for the purpose of developing infrared reduction technology for aircraft. A circular basic nozzle and five rectangular nozzles with different aspect ratio were considered. The conditions for CFD analysis were derived from the analysis of the engine performance. The temperature distribution of the nozzle plume was measured using a temperature sensing system. The thrust of the rectangular nozzle with the aspect ratio 5 was reduced about 1.8% compared to the circular nozzle, and the thrust decreased with increasing the aspect ratio of the nozzle. In the case of thermal flow field, it was observed that, as the aspect ratio increases, the exhaust plume in the experiment was formed wider than in the CFD analysis.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.244-253
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• 2000

Since no single routing-switching combination performs the best under various different types of applications, a flexible network is required to support a range of polices. This paper introduces an implementation of a look-up table routing engine offering flexible routing and switching polices without performance degradation unlike those based on microprocessors. By deciding contents of look-up tables, the engine can implement wormhole routing, virtual cut-through routing, and packet switching, as well as hybrid switching, under a variety of routing algorithms. Since the routing engine has a piplelined look-up table architecture, the routing delay is as small as one flit, and thus it can overlap multiple routing actions without performance degradation in comparison with hardwired routers dedicated to a specific policy. Because four pipeline stages do not induce a hazard, expensive forwarding logic is not required. The routing engine can accommodate four physical links with a time shared cut-through bus or single link with a cross-bar switch. It is implemented using Xilinx 4000 series FPGA.

• The KSFM Journal of Fluid Machinery
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• v.18 no.4
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• pp.30-35
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• 2015

This study analyzed the variations in the performance and operation of a 200 kW class micro gas turbine according to performance degradation of compressor and turbine. An in-house code, developed by the present authors and presented in the first part of these series of papers, were used for the analysis. The degradation of compressor and turbine were simulated by modifications in the their performance maps: mass flow rate, pressure ratio and efficiency were decreased from the reference values. Firstly, the variations in the operating conditions (air flow rate, pressure ratio) were predicted for the full load condition. Then, the same analysis were performed for a wide partial load operating range. The change in engine's performance (power output and efficiency) due to the component degradation was predicted. In addition, the change in the compressor surge margin, which is an important indicator for safe engine operation, was evaluated.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.389-394
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• 2014

In this paper, we report a new manufacturing method for friction reduction using micro-AAJ (abrasive air-jet) machining. AAJ machining employs compressed air to accelerate a jet of high-speed particles to mechanically machine features, including micro-channels and micro-holes, into glass, metal, or polymer substrates for use in microfluidics, MEMS (micro electromechanical systems). And we introduce the micro-AAJ machining system, which consists of a micro-AAJ nozzle and a five-axis positioning system. Various micro-AAJ nozzles can be used, depending on the required surface structure, and three-dimensional machining is possible. We machined samples under six different conditions and describe machining results obtained while using it. We also measured the coefficient of friction of micro-textured surfaces. We report the coefficient of friction of micro-textured surfaces patterned using micro-AAJ machining for engine piston ring.

• The KIPS Transactions:PartC
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• v.11C no.7 s.96
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• pp.937-950
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• 2004

In this paper, we present the design and implementation of new execution environment named Customizable Architecture for Flexible Execution Environment(CAFEs) that supports the mechanism of protocol customization and service referencing. We introduce a new concept as micro protocols and active services to enhance software reusability. Micro protocol represents a specific algorithm or functionality of existing network protocol and the active service is in charge of binding legacy application and releasing the active network oriented services. The pro-posed active network execution environment is made up of three parts, virtual network system, protocol and service manager, event engine. First, the virtual network system is used to connect each active nodes using virtual network channels which are based on multiple existing protocol layers. Second, the protocol and service manager is responsible for composing micro protocols and active services to develop new network proto-col and service easily. Finally, the event engine is used to detect the automatic transition of system components using event delegation model. To verify the CAFTs, we have an experiment about the delivery of web contents which are suitable for the user's terminals in the wireless Internet environment. As a result. we are able to obtain the availability of developed execution environment.