• Journal of Communications and Networks
• /
• v.17 no.4
• /
• pp.428-439
• /
• 2015

In this study, we present an approach for reducing the information inaccuracy of existing star aggregation based on bypass links when there are multi-constraint QoS parameters in asymmetric networks. In our approach, bypass links with low similarity are selected. Links that are not chosen as bypass links are included in each group depending on the star's link characteristics. Moreover, each link group is aggregated differently according to the similarity of the links that make up the group. The selection of a bypass link by using link similarity reduces the existing time complexity of O($N^3$) to O(N) by virtue of the simplification of the selection process. In addition, the adaptive integration according to the characteristics of the links in each group is designed to reduce the information inaccuracy caused by static aggregation. Simulation results show that the proposed method maintains low information distortion; specifically, it is 3.8 times lower than that of the existing method, even when the number of nodes in a network increases.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.19 no.2
• /
• pp.133-138
• /
• 2014

This paper proposes a low power-loss averaging current mode control using a resistor and bypass switch. Generally, current sensing method using a resistor has a disadvantage of power loss which degrades the efficiency of the entire systems. On the other hand, proposed measurement technique operating with bypass-switch connected in parallel with sensing resistor can reduce power loss significantly the current sensor. An analog-circuited bypass driver is implemented and used along with an average-circuit mode controller. The bypass switch bypasses the sensing current with a small amount of power loss. In this paper, a 50[W] prototype average current mode boost converter has been implemented for the experimental verification.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.424.2-424.2
• /
• 2016

Solar cell converts light energy to electric energy. But a solar cell generates low power, PV module is fabricated by connected in series with dozens of solar cell. Owing to solar cell connected in series, power of PV module is influenced by shading or mismatch power of solar cells. To prevent power loss of PV module by shading or mismatch current, Bypass diodes are installed in PV module. Bypass diode operating reverse voltage by shading or mismatch power of solar cells bypass mismatch current. However, bypass diode in module exposed outdoor is easily damaged by surge voltage. In this paper, we confirm characteristics variation of PV module with damaged bypass diode. As a result, power of PV module with damaged bypass diode is reduced and Temperature of that is increased.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.5
• /
• pp.416-422
• /
• 2012

This paper proposes a low power-loss current measurement using a resistor and bypass switch. Conventional current sensing method using a resistor has a disadvantage of power loss which degrades the efficiency of the entire systems. On the other hand, proposed measurement technique operating with bypass-switch connected in parallel with sensing resistor can reduce power loss significantly the current sensor. The propose measurement works for discrete-time sampling of current sensing. Even while the analog-digital conversion does not occur at the controller, the sensing voltage across the sensor still causes ohmic conduction loss without information delivery. Hence, the bypass switch bypasses the sensing current with a small amount of power loss. In this paper, a 90[W] prototype hardware has been implemented for photovoltaic MPPT experimental verification of the proposed low power-loss current measurement technique. From the results, it can be seen that PV power observation is successfully done with the proposed method.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.14 no.6
• /
• pp.79-88
• /
• 2010

This paper dealt with the performance modeling of a low bypass turbofan engine for supersonic aircraft. The Pratt and Whitney F100-PW-229 engine has been employed for low bypass turbofan engine performance modeling. Generally, the complete commercially-classified informations concerning the engine are unknown. The components' generic characteristics and assumptions made in order to build the F100-PW-229 engine performance model using by the published data from the open literature as basic data are described. Through the comparison of engine performance model's analysis data using Gasturb11 with engine deck data showed that the engine performance model was evaluated to be properly constructed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.239-248
• /
• 2010

This paper dealt with the Performance Modeling of a low-bypass turbofan engine for supersonic aircraft. The Pratt and Whitney F100-PW-229 engine has been employed for low-bypass turbofan engine performance modeling. Generally, The complete commercially-classified information concerning the engine are unknown. So, Components' generic characteristics are described and assumptions made in order to model the F100-PW-229 engine performance model. All the analysis has been undertaken using published data taken from the open literature. The results of the Engine Performance using Gasturb11 showed that the Engine performance model was evaluated to be properly constructed.

• Journal of Chest Surgery
• /
• v.27 no.7
• /
• pp.571-575
• /
• 1994

The hemodynamic effects of thyroid hormone are well established, and this hormone affects myocardial contractility, heart rate, and myocardial oxygen consumption. But the role of cardiopulmonary bypass on the thyroid function is not yet fully understood. We have studied twelve patients [male and female patients were equal in number] who were performed open heart surgery under cardiopulmonary bypass. The results are followed. 1] The serum level of T3 began to fall after cardiopulmonary bypass and sustained significantly till 24 hours after operation[p<0.05] 2] The concentrations of T4, Free T4, and TSH were slightly decreased after cardiopulmonary bypass but was maintained within normal range. 3] This above findings are similar to the "sick sinus syndrome" that is seen in severely ill patient. 4] We can propose that T3 would be effective in postoperative low cardiac output syndrome. syndrome.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.8
• /
• pp.966-974
• /
• 2019

In this study, we propose a CMOS power amplifier (PA) using a bypass technique to enhance the efficiency in the low-power region. For the bypass structure, the common-gate (CG) transistor of the cascode structure of the driver stage is divided in two parallel branches. One of the CG transistors is designed to drive the power stage for high-power mode. The other CG transistor is designed to bypass the power stage for low-power mode. Owing to a turning-off of the power stage, the power consumption is decreased in low-power mode. The measured maximum output power is 20.35 dBm with a power added efficiency of 12.10%. At a measured output power of 11.52 dBm, the PAE is improved from 1.90% to 7.00% by bypassing the power stage. Based on the measurement results, we verified the functionality of the proposed bypass structure.

• Journal of Chest Surgery
• /
• v.21 no.2
• /
• pp.240-245
• /
• 1988

This study was prospectively planned to realize the reduction of calcium ion in serum along with the cardiopulmonary bypass[CPB], to find out the cause of the reduction, and to verify the justification of the classical methods of calcium replacement. Nine patients with various open heart surgeries by CPB in 1987 wee selected at random. Calcium chloride was added as follows:: For each unit of ACD blood transfusion, 600mg of calcium chloride was added. In case of massive transfusion, 600 mg of calcium chloride was injected every 2 or 3 units of transfusion. On occasions such as weaning from CPB, or following defibrillation, or hypotension, weak myocardial contractility of the heart, calcium chloride was needed in an amount of 10 mg / kg. In ICU, calcium chloride was limited to use in low serum level or in emergency use. Total calcium decreased early bypass and progressively increased above the preoperative value during late bypass and three hours thereafter, Ionized calcium increased during late bypass and three hours following. Total and ionized calcium depicted similar patterns of change during open heart surgery. Decrease of the calcium at the early bypass was thought from reduction of total protein and alkalosis during bypass. Meanwhile, increase of both calciums during the end of surgery was presumably attributable to addition of calcium chloride in priming solution, injections of calcium chloride in the process of termination of bypass. We conclude that enough calcium was replaced by the classical methods of calcium supplement.

• International Journal of Fluid Machinery and Systems
• /
• v.6 no.3
• /
• pp.152-159
• /
• 2013

A two-dimensional Darrieus-type hydroturbine system, installed with a wear for flow streams such as small rivers and waterways, has been developed for hydropower utilization of extra-low head less than 2m. There are several problems such as flow rate change and flowing wastes to be solved for its practical use in natural flow streams. In the present study, at first, a design guideline in the case of overflow or bypass flow is shown by using simple flow model. Next, in order to avoid the unexpected obstacles flowing into the hydroturbine, an installation of waste screening system is examined. It is confirmed that the screen is effective with some amount of bypass flow rate, however the output power is remarkably deteriorated.