• Journal of Information Technology Services
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• v.14 no.3
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• pp.183-196
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• 2015

The concept of energy-efficient networking has begun to spread in the past few years, gaining increasing popularity. A common opinion among networking researchers is that the sole introduction of low consumption silicon technologies may not be enough to effectively curb energy requirements. Thus, for disruptively boosting the network energy efficiency, these hardware enhancements must be integrated with ad-hoc mechanisms that explicitly manage energy saving, by exploiting network-specific features. The IEEE 802.3az Energy Efficient Ethernet (EEE) standard is one of such efforts. EEE introduces a low power mode for the most common Ethernet physical layer standards and is expected to provide large energy savings. However, it has been shown that EEE may not achieve good energy efficiency because mode transition overheads can be significant, leading to almost full energy consumption even at low utilization levels. Coalescing techniques such as packet coalescing and interrupt coalescing were proposed to improve energy efficiency of EEE, but their implementations typically adopt a simple policy that employs a few fixed values for coalescing parameters, thus it is difficult to achieve optimal energy efficiency. The paper proposes adaptive interrupt coalescing (AIC) that adopts an optimal policy that could not only improve energy efficiency but support performance. AIC has been implemented at the sender side with the Intel 82579 network interface card (NIC) and e1000e Linux device driver. The experiments were performed at 100 M bps transfer rate and show that energy efficiency of AIC is improved in most cases despite performance consideration and in the best case can be improved up to 37% compared to that of conventional interrupt coalescing techniques.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.670-675
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• 2000

The purpose of the study is development and investigation about basic performance of the system operation on a dual fueled cogeneration system(CGS), which is operated with biogas and gas oil. As often seen in dual fueled CGS performance, the electric generating efficiency was obtained about 26□. Methane contained in the biogas could not bum completely at lower load, and it was discharged into exhaust gas. Considerable amount of the methane burned in the exhaust pipe, and the heat recovery ratio was 42□ on heat balance. As a result, the total heat efficiency, which is a summation of generating efficiency and heat recovery efficiency reached to about 70□. The supply of biogas into the engine reduces smoke density and NOx concentration in exhaust gas. At lower load, methane burned slowly and large portion of it was discharged without burning. Therefore the measures are desirable that promotes combustion of methane at lower load.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.4
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• pp.216-223
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• 2006

In this paper, a methodology for the efficiency improvement of the photovoltaic system without adding some elements or increasing the cost comparing with the conventional system is discussed. It is suggested the optimal photovoltaic module configuration through its performance analysis, and also the suitable maximum power point tracking (MPPT) voltage considered the system cost and the efficiency of the converter. The high efficiency photovoltaic system by using the parallel power transfer (PPT) based MPPT converter is proposed and analyzed theoretically comparing with the conventional Buck type MPPT converter. Finally, it is designed and implemented the proposed photovoltaic system for supplying DC 48V by using the PPT based MPPT converter. And the effect of the efficiency improvement and the usefulness of the proposed system is proved through some preliminary simulation and experiment results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.12
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• pp.1073-1081
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• 2013

The definition of the radiation efficiency is very important to estimated underwater radiated noise of a ship. Considering the structure of the ship, it can be found that the hull of a ship consists of a lot of plates supporting by longitudinal and transverse stiffener. Therefore, various modes of the hull vibration occur related to the combination of these plates including stiffeners. In this paper, the method to define the radiation efficiency is suggested considering the vibration mode of the hull based on Uchida's experimental equation of the radiation efficiency. The suggested method is verified by the experiments with various kinds of naval vessels.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.11
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• pp.747-752
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• 2015

Underwater radiated noise is an important characteristic in the naval weapon systems. It is difficult to measure the radiation efficiency of underwater vehicle, such as UUV(unmanned underwater vehicle) and underwater weapons in real operation environment. In this study, acoustic radiation efficiency of a circular cylindrical structure is measured in the laboratory-water tank. The radiation efficiency is compared with the numerical results and it is found that they are in a good agreement. Therefore, the measurement method can be applied effectively for predicting the underwater radiation noise and effectiveness of radiation reduction means.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.3
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• pp.97-103
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• 2006

The development of a heat exchanger production model based on the microlamination technology and it's economic efficiency is addressed. A microchannel production model is proposed for the high-volume production. The microlamination system is made up of lamina patterning, laminae sorting and laminae bonding. A cost estimation model is developed based on the hewn cycle time and capital equipment costs. An economic efficiency analysis is performed to determine the cost drivers under the different market and product scenarios. The result of the economic efficiency analysis indicated that the device size and the production rate have a great effect on the overall manufacturing cost of microlamination devices. And it can be concluded that the microlamination should focus on bonding larger laminae and reducing both cycle time and warpage.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.232-242
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• 1996

In this study, the simulation program for the prediction of volumetric efficiency of the internal combustion engine by the resonator has been developed, when the resonator is mounted on the intake system of 4-cycle SI engines for the improvement of volumetric efficiency. The experimental work has also been carried out for the verification of the program, and it is found that the result of calculation by the simulation program fits qualitatively well with that of experiment. To get the optimal mounting position of resonator on the intake system, the influence of the variation of dimensions of resonator such as neck length, volume and neck diameter were examined by the numerical calculation of the program in advance and the results were compared with the experiments. It is found that the position which is departed 150cm from plenum chamber is better than any other positions, and the average amount of the increase of volumetric efficiency is about 2∼3%

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.3
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• pp.279-287
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• 1996

Pressure drop and fractional collection efficiency of automotive cabin air filters were examined to obtain the basic data for the development of high performance domestic cabin air filters. Pressure drop of MA-V100 was higher than that of VF-V100, and it increased with the air flow rate. VF-V100 had longer time to rise the critical pressure drop than that MA-V100 had. Total collection efficiency of MA-V100 for initial and dust loaded conditions was higher than that of VF-V100. Also, fractional collection efficiency of MA-V100 for the fine particles was higher than that of VF-V100. Particla size distribution for the minimum collection efficiency ranged from 0.02 $\mu$m to 0.04 $\mu$m for MA-V100 and it ranged from 0.02 $\mu$m to 0.15 $\mu$m for VF-V100.

• 한국정보컨버전스학회:학술대회논문집
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• 2008.06a
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• pp.157-160
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• 2008

The pursuit of efficiency is taken for granted in today's public administration, and the limit of this study exists in the point that we should carefully deal with combining the redundancy scheme to the public administration. Accordingly, although this study should suggest the specific plans and backgrounds of the needs for the redundancy, it will only find out the applicability of the redundancy to the public administration for its purpose. Redundancy means the excess or superfluity in something, which means the surplusage status ranging from the wasteful and excessive supplies, insignificant additions, to the surplusage in a legal pleading. The emphasis of this study is placed on the changes in the rigidity in believing that the removal of the redundancy from the public administration is the best option in any case of the efficiency. In addition, the necessity of the overlapped organization should not be neglected by the concept of the efficiency. Indeed, it is necessary to correct the overlapped function of superfluity and ambiguity public administration, in order to remove the neglect conflicts between the organizations, to guarantee the inconsistency in the public administration and to ensure the efficiency in the public administration volunteering.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.533-539
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• 2004

The rotary compressor is widely used for the air conditioner because it is efficient and compact. In recent, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce noise level and to improve efficiency. The new type muffler that has two side discharge holes and dome shape represents much lower overall noise level, especially noise levels around 1kHz than the old type one that has one center discharge hole In acoustic spectra. Also it has higher air conditioner efficiency by lower oil discharging amount of a compressor than old type one that has rectangular shape and two side discharge holes. The noise reduction and efficiency improvement effects of the new type muffler were verified by tests for rotary compressors and air conditioners.