• 방사선산업학회지
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• 제18권2호
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• pp.133-140
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• 2024

The Korean 2^nd basic plan for management of high-level radioactive waste presented a plan to manage spent nuclear fuel through dry storage facilities in NPP on-site. For the construction and operation of the facility, it is necessary to develop the monitoring system of the integrity of spent nuclear fuel before operation. NUREG-1536 recommends that the theoretical cask array, typically in the 2×10 array, should account for shadowing effect among the dry storage casks. The objective of this study was to evaluate neutron flux accounting for shadowing effect among dry storage casks. The neutron release rate was evaluated using ORIGEN based on the design basis fuel condition. And the simulation of dry storage casks and evaluation of the shadowing effect were performed using MCNP. Shadowing effect of other dry storage casks was the highest at the center of the dry storage facility of the 2×10 array compared with the outside of the cask. The shadowing effect of neutron flux on the surface among the metal casks was approximately 18% at point 1, 23% at point 2, and 43% at point 3. For the concrete casks, the shadowing effect of neutron flux on the surface was approximately 46% at point 1, 51% at point 2, and 52% at point 3. This means that correction is necessary to monitor the integrity of spent nuclear fuel in each dry storage cask through evaluation of shadowing effect. The results of this study will be used for comparative analysis of neutron measurement data from spent nuclear fuels in dry storage cask. Additionally, the neutron flux evaluation procedure used in this study could be used as the basic data of safety assessment of dry storage cask and development of safety guide.

• 한국어교육
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• 제29권2호
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• pp.49-72
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• 2018

The purpose of this study is to introduce an efficient measure in Korean language education for learners of Korean by applying shadowing techniques which focus on improving not only listening and speaking skills but also reading and writing skills. First of all, the study discusses about the definition of shadowing along with the effect of shadowing. The second part will be about examining the proposed method related to shadowing technique which is comprised of original shadowing techniques and other techniques transformed from the original. Thirdly, the paper will be discussing background information of the shadowing technique in previous researches and experiments using shadowing techniques in Korean language education. Finally, there will be an introduction of learning measures that apply to skill unification. Most of the previous researches of the shadowing technique were limited to a few students with only mid-to-high level learners while this method could cover up to a wide range of learners. The most effective way of learning a foreign language would firstly be the suggested method and the focus should be on repetition and practice of the learners.

• 반도체디스플레이기술학회지
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• 제9권4호
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• pp.13-18
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• 2010

Extreme ultraviolet (EUV) lithography using 13.5 nm wavelengths is expected to be adopted as a mass production technology for 32 nm half pitch and below. One of the new issues introduced by EUV lithography is the shadowing effect. Mask shadowing is a unique phenomenon caused by using mirror-based mask with an oblique incident angle of light. This results in a horizontal-vertical (H-V) biasing effect and ellipticity in the contact hole pattern. To minimize the shadowing effect, a refilled mask is an available option. The concept of refilled mask structure can be implemented by partial etching into the multilayer and then refilling the trench with an absorber material. The simulations were carried out to confirm the possibility of application of refilled mask in 32 nm line-and-space pattern under the condition of preproduction tool. The effect of sidewall angle in refilled mask is evaluated on image contrast and critical dimension (CD) on the wafer. We also simulated the effect of refilled absorber thickness on aerial image, H-V CD bias, and overlapping process window. Finally, we concluded that the refilled absorber thickness for minimizing shadowing effect should be thinner than etched depth.

• ETRI Journal
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• 제31권5호
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• pp.500-505
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• 2009

The detrimental effect of short-term fading and shadowing can be mitigated using microdiversity and macrodiversity systems, respectively. In this paper, implementation of selection combining at both micro and macro levels to improve system performance is analyzed. An assessment of the performance of such a system is carried out by considering the desired signal as Rician fading with lognormal shadowing and cochannel interference signal as Rayleigh fading superimposed over lognormal shadowing. The proposed analysis is complemented by various performance evaluation results, including the effects on overall system performance of fading severity, shadowing spreads and branch correlation existing at the base station, and correlation between base stations.

• 열처리공학회지
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• 제22권5호
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• pp.275-281
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• 2009

The microstructure of copper films prepared by a sputtering apparatus, which was fabricated to enhance the shadowing effect, was investigated by scanning electron microscopy. Black copper films were deposited on copper wires at an Ar pressure of 10 Pa. The black films had an extremely porous structure composed of separated columns. This structure is quite similar to that of black titanium films prepared by cylindrical magnetron sputtering. These results suggest that the porous structure composed of separated columns is easily formed for metal films by enhancing the shadowing effect.

• 상하수도학회지
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• 제22권4호
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• pp.421-427
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• 2008

UV disinfection is widely used in water treatment facilities and wastewater treatment plant because of its effectiveness to removal of pathogen and Giardia which is resistant to traditional chemical disinfection. As a design and performance tool of UV disinfection system, 3 dimensional UV intensity models were composed and simulated to compare each other and to find affecting factors in this study. Reflection, refraction and absorption are important parameters in UV intensity model and MPSS and MSSS model can reflect these parameters while LSI model can not. Absorption is the most important parameters among the reflection, refraction, absorption and shadowing so, this should not be neglect. Based on this simulation, shadowing effect is negligible when the number of installed lamp is a few but, this effect can not be neglectable when the number of installed lamp is quite a few. The errors according to shadowing effect is increased as the number of lamp installed increased.

• Journal of Communications and Networks
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• 제6권3호
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• pp.226-234
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• 2004

This work presents a deterministic channel that rules according to inverse a power propagation law. The proposed channel model allows us to derive the lower bound and upper bound of packet's capture probability in Rayleigh fading and shadowing cellular mobile system. According to these capture probabilities, we analyze the system performance in the case of finite stations and finite communicated coverage of a base station. We also adopted a dynamic backoff window size to discuss the robustness of IEEE 802.11 draft standard. Some suggestions and conclusions from numerical results are given to establish the more strong CSMA/CA protocol.

• 전기학회논문지
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• 제59권1호
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• pp.144-151
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• 2010

The shadowing effects lead to the serious power losses of the PV module. The shadowing effects are caused by several factors such as leafs, dust, antenna and clouds. The dye-sensitized solar cells are more economical than the conventional silicon solar cell that's why the dye-sensitized solar cells are recently focused on. We carried out research on the efficiency of the dye-sensitized solar cell depending on the level of shadow changing the formula of the circuit. The research on the efficiency of the large dye-sensitized solar cell depending on the level of shadow focused on commercialization was carried out. As the results, it is known that the series and parallel connection method is the best choice for the least losses of PV module assemblies. It is especially known that one more series connection is the best choice for the least losses about shadowing effects and current losses in the series and parallel connection.

• ETRI Journal
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• 제30권3호
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• pp.355-364
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• 2008

Multiple-input multiple-output (MIMO) systems can provide significant increments in capacity; however, the capacity of MIMO systems degrades severely when spatial correlation among multipath channels is present. This paper demonstrates that the influence of shadowing on the channel capacity is more substantial than that of multipath fading; therefore, the shadowing effect is actually the dominant impairment. To overcome the composite fading effects, we propose combining macroscopic selection diversity (MSD) schemes with MIMO technology. To analyze the system performance, the capacity outage expression of MIMO-based MSD (MSD-MIMO) systems using a characteristic function is applied. The analytic results show that there are significant improvements when MSD schemes are applied, even for the two-base-station diversity case. It is also observed that the effect of spatial correlation due to multipath fading is almost negligible when multiple base stations cooperatively participate in the mobile communication topology.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.325-328
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• 2000

The control of the data retention time is a main issue for realizing future high density dynamic random access memory. In this paper, we propose the new implantation scheme by gate-related ion beam shadowing effect and buffer-enhanced $\Delta$ Rp increase using buffered N- implantation with tilt and 4X-rotation that is designed on the basis of the local-field-enhancement model of the tail component. We report an excellent tail improvement of the retention time distribution attributed to the reduction of electric field across the cell junction due to the redistribution of N- concentration which is intentionally caused by Ion Beam Shadowing and Buffering Effect using tilt implantation with 4X-rotation.