• Smart Media Journal
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• v.5 no.1
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• pp.55-60
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• 2016

Mobility of the sensor networks proposed a new way to the efficient design of sensor networks and improvement of network system performance. Mobility results in a number of functional changes in the MAC protocol and routing protocol. Especially, the mobility of the nodes may occur the increase of the overhead of transmission or disconnection of the link. Therefore, the study of the energy efficient transmission is very important in mobile sensor networks. This paper proposed adaptive transmission mechanism on the distance-based power control. The proposed mechanism was analyzed better than conventional method in the average energy consumption and network life by simulation results.

• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.57-61
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• 2010

Nanosized surface structures of Cu powders were investigated at the atomic scale by field-emission transmission electron microscope techniques. The nanoscale surface oxide layer on the Cu powder was analyzed to be the $CU_2O$ phase by electron diffraction pattern and electron energy-loss spectroscopy. In addition, it was found from high-resolution transmission electron microscopy study that there are formed no surface oxide layers on the surface of alkanethiol coated Cu powders.

• Progress in Superconductivity and Cryogenics
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• v.25 no.2
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• pp.19-24
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• 2023

Recently, interest in renewable energy such as solar and wind power has increased as an alternative to fossil fuels. Renewable energy sources such as large wind farms require long-distance power transmission because they are located inland or offshore, far from the city where power is required. High-Temperature Superconducting (HTS) power cables have more than 5 times the transmission capacity and less than one-tenth the transmission loss compared to the existing cables of the same size, enabling large-capacity transmission at low voltage. For commercialization of HTS power cables, unmanned operation and long-distance cooling technology of several kilometers is essential, and pressure drop characteristic is important. The cryostat's spiral corrugation tube is easier to bend, but unlike the round tube, the pressure drop cannot be calculated using the Moody chart. In addition, it is more difficult to predict the pressure drop characteristics due to the irregular surface roughness of the binder wound around the cable core. In this paper, a CFD model of a spiral corrugation tube with a core was designed by referring to the water experiments from previous studies. In the four cases geometry, when the surface roughness of the core was 10mm, most errors were 15% and the maximum errors were 23%. These results will be used as a reference for the design of long-distance HTS power cables.

• Journal of Wind Energy
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• v.15 no.1
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• pp.43-49
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• 2024

This study performed a response analysis according to the transmission error of the yaw drive. To perform the response analysis, the excitation source of the transmission error was modeled and the outer ring of the first stage bearing and the outer ring of the output shaft bearing were used as measurement positions. The response results were analyzed based on the vibration tolerance values of AGMA 6000-B96. As a result of the response of the first stage bearing outer ring, the maximum displacement of the first stage planetary gear system was 5.59 and the maximum displacement of the second to fourth stage planetary gear systems was 4.21 ㎛ , 3.13 ㎛ , and 25.6 ㎛ . In the case of the output shaft bearing outer ring, the maximum displacement of the first stage planetary gear system was 1.73 ㎛, and the maximum displacement of the second to fourth stage planetary gear system was 1.94 ㎛, 0.73 ㎛, and 2.03 ㎛. According to AGMA 6000-B96, the vibration tolerance of first stage is 17.5 ㎛, and the vibration tolerance of the second to fourth stages is 58 ㎛, 80 ㎛, and 375 ㎛, which shows that the vibration tolerance is satisfied and it is safe.

• Journal of Korean Medical classics
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• v.23 no.2
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• pp.157-189
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• 2010

Many chapters of the Hwangjenaegyeong[HN] explain the process of transmission and transmutation of disease. The transmission and transmutation process in the HN can be categorized into one between the viscera and bowels, and another of the external pathogenic gi itself. The process between the viscera and bowels indicates the transport of the pathologic burden between each viscera and bowel. This again is categorized into three types. Interpromoting, intercontrolling and that by Saeng-yang(生陽), Sa-eum(死陰). Next, the transport of the pathogenic gi can be categorized into one moving inwards from the exterior according to personal traits, and that according to the three Eum and three Yang. Although there are numerous types of transmission and transmutation, there are two main criteria in understanding the process. First, whether the process is in accordance with the physiological or natural flow of the body. Interpromoting and three Eum three Yang processes are such examples. To follow the physiological flow of the body means to correspond to either the Heaven and Earth or the original physiology of the human body. Therefore, the disease progresses according to a certain date or season. This indicates a partial malfunction in the circulation of the vital energy, which is relatively easy to recover. In contrast, there are processes that go against the physiological flow, for example, intercontrolling transmission and transmutation. This process focuses on the movement of the pathogenic gi rather than the vital gi. The disease progresses regardless of the flow of the vital energy, and sequential functional damage occurs accordingly. Consequently, as the transmission and transmutation continue, formerly passed organs are left damaged, and the whole process is headed towards death. The second criteria for understanding the process is whether it is cyclic or not. To have a cyclic pattern means that the occurrence of a disease and the time of death is not fixed. Transmission and transmutation processes that have a cyclic pattern mostly follow the physiological flow of the body. As a result, they rarely end in deaths, and the process is centered on vital energy. On the other hand, those with acyclic patterns have a fixed occurrence and death point in the course of the disease. They are mostly unnatural processes, found in fatal acute diseases or consumption diseases.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.4
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• pp.287-295
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• 2012

Hydrodynamic performance of a movable submerged breakwater was analyzed using energy dissipation model. Based on two-dimensional boundary element method the equation of motion including a viscous dissipation term proportional to velocity squared was solved by Newton-Raphson method. Energy dissipation coefficients as well as reflection and transmission coefficients of a submerged flat plate were calculated with various plate lengths and thickness. Both real and imaginary components of body displacement and forces were used to solve the motion of breakwater accurately. The effect of the magnitude of dissipation coefficient on the body displacement was evaluated. The results from the potential theory with no dissipation term were found to be an overestimate in resonance frequency.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.198-202
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• 2014

In the solar heat collection system, we can determine how the collector will perform under specific conditions from the efficiency curve. By understanding the basic principles which govern the operation, designers can maximize the output from the collector. Absorptance, transmission and the total heat transfer coefficient were introduced to induce this efficiency curve. Designers who can make use of the implicit information on the curve in this report will generate systems which obtain the best return from their client's investment.

• Journal of electromagnetic engineering and science
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• v.9 no.3
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• pp.111-117
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• 2009

This paper presents an energy-efficient and bandwidth-efficient 2-1-1 relaying scheme in which a sensor node(SN) assists two others in their data transmission to a clusterhead in WSNs(Wireless Sensor Networks) using LEACH (Low-Energy Adaptive Clustering Hierarchy). We derive the closed-form BER expression of this scheme which is also a general BER one for the decode-and-forward cooperative protocol and prove that the proposed scheme performs the same as the conventional relaying scheme but obtains higher channel utilization efficiency. A variety of numerical results reveal the relaying can save the network energy up to 11 dB over single-hop transmission at BER of $10^{-3}$.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.1-7
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• 2008

Superconducting Magnetic Energy Storage (SMES) can inject or absorb real and reactive power to or from a power system at a very fast rate on a repetitive basis. These characteristics make the application of SMES ideal for transmission grid control and stability enhancement. The purpose of this paper is to introduce the SMES model and scheme to control the active and reactive power through the power electronic device. Furthermore, an optimal priority scheme is proposed for the combination of active and reactive power control to be able to stabilize power transient swings.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.114-114
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• 2010

산불에 노출되는 경우 열충격으로 작용하는 패턴과 특성을 검토하여 가속열화시험에 반영하는 것이 필요하다. 본 연구에서는 산불환경을 모의하여 복합열화시험을 실시하기위해 복합가속열화 챔버를 구축하였다. 온도는 주로 $200^{\circ}C$에서 최대 $1000^{\circ}C$까지 변화를 주면서 예비시험과 본시험 실하였다.