• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.694-694
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• 2013

With the growing need of more effective energy harvesting, solar energy has been sought as one of the prominent candidates among the eco-friendly methods. Although many types of solar cells have been developed, the electronic conversion efficiency is limited by the material's physical properties: solar cells can only harvest solar energy from limited range in solar energy spectrum. To overcome this physical limit, we approached by using the down conversion effect, transforming the high energy photons to low energy photons, to the range the designated solar cell can convert to electronic energy. In our study, we have fabricated GaAs single junction solar cells and applied CdSe quantum dots for down-conversion. We examine the effects of such application on the solar cell efficiancy, fill-factor, JSC, VOC, etc.

• Proceedings of the KSR Conference
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.375-380
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• 2004

Vibration of railway vehicle has harmful effect to dynamic performances of railway represented to stability, safety and ride comfort. Hence reduction of vibration has been discussed as an important problem and has been widely investigated. A new technology of vibration control, energy regenerative control, is introduced. Energy regenerative damper using this new vibration control converts vibration energy into other kind of energy that we can utilize. In this paper, this energy regenerative damper is applied to the dynamic absorber and vehicle suspension. And it is evaluated whether the energy regenerative railway vehicle suspension is possible.

• ETRI Journal
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• 제33권3호
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• pp.299-309
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• 2011

Energy consumption is a key issue in body sensor networks (BSNs) since energy-constrained sensors monitor the vital signs of human beings in healthcare applications. In this paper, packet size optimization for BSNs has been analyzed to improve the efficiency of energy consumption. Existing studies on packet size optimization in wireless sensor networks cannot be applied to BSNs because the different operational characteristics of nodes and the channel effects of in-body and on-body propagation cannot be captured. In this paper, automatic repeat request (ARQ), forward error correction (FEC) block codes, and FEC convolutional codes have been analyzed regarding their energy efficiency. The hop-length extension technique has been applied to improve this metric with FEC block codes. The theoretical analysis and the numerical evaluations reveal that exploiting FEC schemes improves the energy efficiency, increases the optimal payload packet size, and extends the hop length for all scenarios for in-body and on-body propagation.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제61권8호
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• pp.1193-1198
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• 2012

An instantaneous amplitude (IA) estimator using the symmetric higher order differential energy operator is proposed. The amplitude estimator and the instantaneous frequency (IF) estimator based on the symmetric higher order differential energy operator coincide with the analyzed signal in time, and they show better estimation results than the IA and IF based on the higher order differential energy operator. Various IF and IA estimators are applied to AM-FM signals for the performance comparison. Among the IF and IA estimators, the IF and IA estimators based on the symmetric higher order energy operator show the best estimation accuracy. Then, the IA and IF estimators are applied to the distorted power line signal to show their usefulness as power disturbance detectors.

• Journal of Applied Reliability
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• 제14권2호
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• pp.137-146
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• 2014

This paper is to develop Energy-FMEA for Energy Review of ISO 50001 Energy Management System. Energy Review is the core requirement of ISO 50001. This study develop Energy-FMEA and suggest Energy Review Inventory and Assessment Criteria for performing Energy-FMEA. Also, it shows case study to verify whether to proper.

• Transactions of Materials Processing
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• 제10권6호
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• pp.449-456
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• 2001

The concept of stress wave was introduced through the quantized kinetic energy which is related to the potentional energy change of atom, molecular bond energy. Differentiated molecular bond energy $\varphi$() by the lst order displacement u becomes force F(F = d$\varphi$($u_i$)/du), if resversely stated, causing physically atomic displacement $u_i$. Such physical phenomena lead stress(force/area of applied force) can be expressed by wave equation of linearly quantized physical property. Through the stress wave concept, formation of dislocation, which could not explained easily from a theory of continuum mechanics, can be explained. Moreover, this linearly quantized stress wave equation with a stress concept for grains in a crystalline solid was applied to three typical metallic microstructures and a simple shape. The result appears to be a product from well treated equations of a quantized stress wave. From this result, it can be expected to answer the reason why the defect free and very fine diameters of long crystalline shapes exhibit ideal tensile strength of materials.

• Proceedings of the SAREK Conference
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.558-562
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• 2008

This study is being conducted to develope an infill system applied to Mock-Up House of the Korean long life housing. This paper presents result of study and an infill system applied to Mock-up house, commenced in June 2005. We also present the mechanical system and technology, the capability of interface, and other factors.

• Journal of Hydrogen and New Energy
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• 제26권6호
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• pp.532-540
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• 2015

Electrochemical alane ($AlH_3$) production process can be provided as a synthesis route which close a reversible cycle. In this study, growth inhibition of dendrite as key issues in this process was investigated. Main cause of dendrite growth was because Al fine powder separated in consumption process of Al electrode was moved to Pd electrode. In an effort to avoid this, use of glass block with uniform holes was the most effective to inhibit the amount of dendrite to that of $AlH_3$. Furthermore, effects of Al electrode (anode) type and electrolyte concentration were investigated and the optimal condition for inhibiting dendrite formation was proposed.

• Journal of Magnetics
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• 제15권3호
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• pp.116-122
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• 2010

An accurate analytical equation for the total energy in the framework of the single domain model is used to study the thermal stability of nanostructured synthetic ferrimagnets. Elliptical cells are considered that have lateral dimensions of 160 nm (long axis)$\times$80 nm (short axis) and varying values of thickness asymmetry for the two magnetic layers. The direction of the applied magnetic field, which points to the $45^{\circ}$ direction, is in the opposite direction to the thicker layer magnetization. A significant difference is observed in the applied magnetic field dependencies of the equilibrium magnetic configuration and the magnetic energy barrier when using the simplifying assumption that the self-demagnetizing field is identical in magnitude to the dipole field. At a small thickness asymmetry of 0.2 nm, for example, the magnetic energy barrier is reduced from 68 kT (T=300 K) to 6 kT at the remanent state and a progressive switching behavior changes into a critical behavior, as the simplifying assumption is used. The present results clearly demonstrate the need for an accurate analytical equation for the total energy in predicting the thermal stability of nanostructured synthetic ferrimagnets.

• Journal of the Korean housing association
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• 제24권6호
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• pp.69-79
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• 2013

The concept of sustainable development to preserve natural environment through economy in resources and energy is gradually distinguished since environmental problems as a series of air pollution and global warming take place now. Building occupies more than 1/3 of energy consumption in the whole world. Energy consumption of buildings caused a quick increase in the amount of energy use by air conditioning, which has a lot of effects on exhaustion of fossil energy as well as an increase in environmental load. Therefore, this research intends to suggest characteristics and direction for the designing of acclimatization's housing through the case study on acclimatization's housing. Acclimatization's housing is designed to reduce building load from the designing stage unlike green home or low-energy apartment. Also, factors which are commonly applied to acclimatization's housing are applied complexly by design strategic factors of Heating, Cooling and Lighting. The applied design factors make effects mutually and complexly. In addition, design strategy showed different priority by designing direction.