• Journal of Power System Engineering
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• v.17 no.5
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• pp.44-51
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• 2013

This paper proposes and analyzes recycling of optical phonons emitted by nonradiative decay, which is a major thermal management concern for high-power light emitting diodes (LED), by introducing an integrated, heterogeneous barrier cooling layer. The cooling is proportional to the number of phonons absorbed per electron overcoming the potential barrier, while the multi-phonon absorption rate is inversely proportional to this number. We address the theoretical treatment of photon-electron-phonon interaction/transport kinetics for optimal number of phonons (i.e., barrier height). We consider a GaN/InGaN LED with a metal/AlGaAs/GaAs/metal potential barrier and discuss the energy conversion rates. We find that significant amount of heat can be recycled by the barrier transition cooling layer.

• Journal of Soil and Groundwater Environment
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• v.21 no.1
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• pp.1-5
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• 2016

Capillary barriers, consisting of relatively fine-over-coarse materials, have been suggested as an alternative to traditional compacted soil covers. So, We were analysed to capillary barrier effect according to five cases of multi-layer cover systems. Water balance simulation was conducted with unsaturated flow model HELP to assess unsaturated hydraulic parameters such as hydraulic conductivity, climate affecting the performance of capillary barriers. Simulation were conducted for 5 Cases in the Ulsan area. Result of simulation indicated that three cases was formed unsaturated condition and capillary barrier effect.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.1
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• pp.23-34
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• 2004

To validate the previous conceptual design of cover system, construction of the engineered barrier test facility is completed and the performance tests of the disposal cover system are conducted. The disposal test facility is composed of the multi-purpose working space, the six test cells and the disposal information space for the PR center. The dedicated detection system measures the water content, the temperature, the matric potential of each cover layer and the accumulated water volume of lateral drainage. Short-term experiments on the disposal cover layer using the artificial rainfall system are implemented. The sand drainage layer shows the satisfactory performance as intended in the design stage. The artificial rainfall does not affect the temperature of cover layers. It is investigated that high water infiltration of the artificial rainfall changes the matric potential in each cover layer. This facility is expected to increase the public information about the national radioactive waste disposal program and the effort for the safety of the planned disposal facility.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.5
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• pp.485-495
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• 2000

The parallel computer system that uses parallel program on the application such as a large scale business or complex operation is required. One of crucial operation of parallel computer system is synchronization. A representative method of synchronization is barrier synchronization. A barrier forces all process to wait until all the process reach the barrier and then releases all of the processes. There are software schemes, hardware scheme, or combinations of these mechanism to achieve barrier synchronization which tends to use hardware scheme. Besides, barrier synchronization lets parallel computer system fast because it has fewer start-up overhead. In this paper, we propose a new switch module that can implement fast and fault-tolerant barrier synchronization in hardware scheme. A proposed barrier synchronization is operated not in full-switch-driven method but in processor-driven method. An effective barrier synchronization is executed with inexpensive hardware supports. Therefore, a new proposed hardware barrier synchronization is designed that it is operated in arbitrary network topology. In this paper, we only show comparison of barrier synchronization on Multistage Interconnection Network. This research results in 24.6-24.8% reduced average delay. Through this result, we can expect lower average delay in irregular network.

• Korean Institute of Interior Design Journal
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• v.26 no.3
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• pp.13-24
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• 2017

Promoting barrier-free living environments is necessary in residential facilities on which senior citizens rely most of their lives. Safety of elder people can be reassured by a certification system based on the existing barrier-free certification program in public facilities. The range of certification does not cover all living area, but is limited to the bathroom, which is a sanitary space. Given the nature of BIM modeling, an existing multi-family building was selected and modeled, as the certification process requires all the necessary information and various viewport. BIM modeling of the bathroom was conducted in accordance with the requirements of the certification for barrier-free living environment. The results suggested that there is a need for a removal of thresholds, larger doors, better selection of finishing materials, sufficient room for a wheelchair, larger space next to the toilet, and the availability of an emergency bell and grab bars. Such information supports the potentials of BIM modeling, and it is expected that an automated certification system would be established in the foreseeable future.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.2
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• pp.157-178
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• 2013

This study gives a conceptual and basic direction to develop a URL (underground research laboratory) program for establishing the performance and safety of a deep geological disposal system in Korea. The concept of deep geological disposal is one of the preferred methodologies for the final disposal of spent nuclear fuel (SNF). Advanced countries with radioactive waste disposal have developed their own disposal concepts reasonable to their social and environmental conditions and applied to their commercial projects. Deep geological disposal system is a multi-barrier system generally consisting of an engineered barrier and natural barrier. A disposal facility and its host environment can be relied on a necessary containment and isolation over timescales envisaged as several to tens of thousands of years. A disposal system is not allowed in the commercial stage of the disposal program without a validation and demonstration of the performance and safety of the system. All issues confirming performance and safety of a disposal system include investigation, analysis, assessment, design, construction, operation and closure from planning to closure of the deep geological repository. Advanced countries perform RD&D (research, development & demonstration) programs to validate the performance and safety of a disposal system using a URL facility located at the preferred rock area within their own territories. The results and processes from the URL program contribute to construct technical criteria and guidelines for site selection as well as suitability and safety assessment of the final disposal site. Furthermore, the URL program also plays a decisive role in promoting scientific understanding of the deep geological disposal system for stakeholders, such as the public, regulator, and experts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.10
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• pp.903-910
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• 2013

An autostereoscopic multi-view 3D display system has the narrower degrees of freedom in the observational directions, such as the horizontal and perpendicular directions to the display plane, than the glasses-on type of 3D display. In this paper, we propose an innovative method to expand the width of the viewing zone formed in the depth direction while maintaining the number of views in the horizontal direction by using a triple segmented-slanted parallax barrier (TS-SPB) in the glasses-off type of 3D display. The validity of the proposal was verified by an optical simulation based on an environment similar to an actual case. The maximum number of views that can be displayed in the horizontal direction is 2n, and the width of the viewing zone with depth increased up to a factor of 3.36 compared to the existing one-layered parallax barrier system.

• Journal of the Korean Society of Safety
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• v.34 no.1
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• pp.40-44
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• 2019

Experimental studies have been carried out to investigate characteristics of gas explosion using a multi layered water gel barrier in a vented explosion chamber. The chamber is consisted of 1600 mm in length, with a square cross-section of $100{\times}100mm^2$. The gel concentration of inner layer of MLWGB ranged from 10% to 90% with intervals of 10% by weight of gel. Displacement of the MLWGB was photographed with a measured using a high-speed video camera, and pressure development was measured using a data acquisition system. It was found that MLWGBs with 10 ~ 20% inner layer concentrations were ruptured during the explosions. As the concentrations of inner layer increased from 30% to 90%, the barriers were not ruptured. As the gel concentrations of the inner layer increased, the displacement increased toward the chamber exit and the pressure decreased for the ruptured barriers. It was found that the pressure attenuation obtained from the MLWGB was higher than that of the single water gel barrier. For the cases of non-ruptured barriers, the pressure inside the chamber less increased with increasing gel concentrations of the inner layer. It was also found that the displacement moved back into the chamber for non-ruptured MLWGBs, and it was sensitive to the gel concentrations.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.4
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• pp.439-455
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• 2020

Numerical model was developed that simulates radionuclide (3H and 14C) transport modeling at the 2nd phase facility at the Wolsong LILW Disposal Center. Four scenarios were simulated with different assumptions about the integrity of the components of the barrier system. For the design case, the multi-barrier system was shown to be effective in diverting infiltration water around the vaults containing radioactive waste. Nevertheless, the volatile radionuclide 14C migrates outside the containment system and through the unsaturated zone, driven by gas diffusion. 3H is largely contained within the vaults where it decays, with small amounts being flushed out in the liquid state. Various scenarios were examined in which the integrity of the cover barrier system or that of the concrete were compromised. In the absence of any engineered barriers, 3H is washed out to the water table within the first 20 years. The release of 14C by gas diffusion is suppressed if percolation fluxes through the facility are high after a cover failure. However, the high fluxes lead to advective transport of 14C dissolved in the liquid state. The concrete container is an effective barrier, with approximately the same effectiveness as the cover.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.265-266
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• 2018