• Nuclear Engineering and Technology
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• 제51권1호
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• pp.284-292
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• 2019

For the continuous operation of a nuclear reactor, burnt fuel needs to be replaced with fresh fuel, where appropriate (ex-vessel) fuel handling is required. Particularly for the Sodium-cooled Fast Reactor (SFR) refueling, its process has unique challenges due to liquid sodium coolant. The ex-vessel spent fuel transportation should concern several design features such as the radiation shielding, decay-heat removal, and inert space separated from air. This paper proposes a new design optimization methodology of cask shielding to transport the spent fuel assembly in a prototype SFR for the first time. The Particle Swarm Optimization (PSO) algorithm had been applied to design trade-offs between shielding and cask weight. The cask is designed as a double-cylinder structure to block an inert sodium region from the air-cooling space. The PSO process yielded the optimum shielding thickness of 26 cm, considering the weight as well. To confirm the shielding performance, the radiation dose of spent fuel removed at its peak burnup and after 1-year cooling was calculated. Two different fuel positions located during transportation were also investigated to consider a functional disorder in a cask drive system. This study concludes the current cask design in normal operations is satisfactory in accordance with regulatory rules.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.449-455
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• 2022

The rapid rise in the application of novel treatment techniques, such as intensity-modulated radiotherapy (IMRT), motivated us to survey the status of Korea's radiation safety management and the shielding designs of facilities employing medical linear accelerators (LINACs). To this end, a questionnaire was used to collect information on LINAC facilities and treatments, workload, shielding design, shielding management, and path of obtaining shielding information. Out of 100 domestic institutions, 52 responded to the survey. Approximately 70% of the institutions utilized IMRT for more than 60% of their cases, and an IMRT factor of 5 was adopted by 75% of these institutions. Over 80% of the institutions accounted for the applied time-averaged dose rate per week and instantaneous dose equivalent rates in their shielding designs. Approximately 45% of the institutions obtained important shielding information via a radiation shielding design company and the NCRP-151 report. Overall, most facilities were shown to follow the standards recommended by the relevant international agencies. However, the requirement to establish standardized shielding design information and clarify ambiguous paths for information acquisition was also highlighted. Therefore, the study's results can be used as a foundation for establishing a safety control system and for creating adequate shielding designs.

• 한국전자파학회논문지
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• 제16권9호
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• pp.862-871
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• 2005

본 논문에서는 전자기 차폐 구조로 널리 알려진 육각형 도파관 구조를 갖는 허니컴 구조의 차폐 효과를 정확하게 예측하기 위하여 기존의 차폐 효과 설계식을 수정하여 새로운 차폐 효과 설계식을 제안하였다. 허니컴의 차폐 효과 설계 방정식은 단일 격자의 차폐 효과와 무수히 많은 격자 구조의 차폐 효과의 합으로 표현되는데, 본 논문에서는 허니컴 구조를 이루고 있는 육각형 기본 격자를 해석하고, 기본격자가 다수의 배열로 이루어진 해석을 통해 일반화 된 차폐 효과 설계 방정식을 제안하였다. 제안한 차폐 효과 설계 방정식의 유효함을 입증하기 위하여 상용 소프트웨어의 3D EM 시뮬레이션과 비교하였다. 또한, 측정 결과와 비교하여 본 논문에서 제안한 수정된 차폐 효과 설계 방정식이 기존의 설계 방정식보다 더 정확하다는 것을 보여주었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.413-416
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• 2001

In high frequency range, RF circuit design without considering shielding effect can cause several significant changes due to increase in parasitic capacitance and inductance between RF signal lines and shielding box. In this paper, bandpass filter has been made to measure the shielding effect and its s-parameter has been measured by Vector Network Analyzer (VNA). Equivalent circuit model including the shielding effect has been constructed with the lumped elements extracted from the 3D electromagnetic simulator, Maxwell SI. Then, the validity of the model is verified using microwave circuit simulator, ADS (Advanced Design System).

• 한국의류산업학회지
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• 제10권3호
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• pp.385-388
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• 2008

Four kinds of PET fabrics were coated with Copper and Nickel by electroless chemical plating, and the electromagnetic wave shielding effectiveness for those samples have been examined. The shielding effectiveness showed between 90 dB and 70 dB, and it related to the fabric structure, such as cover factor and cloth density. The dense fabric structure showed the better shielding effect.

• 전기학회논문지
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• 제60권4호
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• pp.694-699
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• 2011

This paper compares the performance of lightning shielding analysis methods using the seven striking distance formulae in substation. For comparison, we evaluate the number of expected strikes and exposed area using WinIGS Software. Seven striking distance formulae are compared using the electrogeometric model analysis and the rolling sphere method. Based on the electrogeometric model analysis, the risk of shielding failure in either the whole substation or parts of it is determined. According to the simulation results, one can justify whether the substation satisfies the criterion of shielding design. In particular, according to the rolling sphere method, the exposed areas in substation determine the location of the additional shielding poles or shield wires. Therefore, the installation of the additional shielding poles and shield wires in substation was accepted by shield design at the phase conductors exposed in the larger area.

• 방사성폐기물학회지
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• 제18권spc호
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• pp.37-50
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• 2020

In this paper, an overview of the scoping calculation results is provided with respect to criticality and radiation shielding of two KBS-3V type PWR SNF disposal systems and one NWMO-type CANDU SNF disposal system of the improved KAERI reference disposal system for SNFs (KRS⁺). The results confirmed that the calculated effective multiplication factors (k_eff) of each disposal system comply with the design criteria (< 0.95). Based on a sensitivity study, the bounding conditions for criticality assumed a flooded container, actinide-only fuel composition, and a decay time of tens of thousands of years. The necessity of mixed loading for some PWR SNFs with high enrichment and low discharge burnup was identified from the evaluated preliminary possible loading area. Furthermore, the absorbed dose rate in the bentonite region was confirmed to be considerably lower than the design criterion (< 1 Gy·hr^-1). Entire PWR SNFs with various enrichment and discharge burnup can be deposited in the KRS⁺ system without any shielding issues. The container thickness applied to the current KRS⁺ design was clarified as sufficient considering the minimum thickness of the container to satisfy the shielding criterion. In conclusion, the current KRS⁺ design is suitable in terms of nuclear criticality and radiation shielding.

• 한국콘텐츠학회논문지
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• 제11권9호
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• pp.129-136
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• 2011

본 논문에서는 생활가전기기와 정보통신가전기기의 다양한 외형디자인에 응용할 수 있는 옻과 숯을 이용한 친환경 소재의 전자파 차폐 물질을 제시하였다. 제시된 전자파 차폐 물질은 전자레인지에서 사용되는 2.45 GHz에서는 약 96.3%, 이동전화의 사용 주파수 900 MHz, 1.8 GHz에서 각각 97.2%, 98.7%의 전자파를 차폐하였다. 기존에는 전자레인지와 이동전화에서는 방출되는 강한 전자파를 차단하기 위해 금속 재질이나 플라스틱 표면에 도전성 재료를 피복하는 방법이 이용되고 있으나, 친환경 소재인 옻과 숯을 활용함으로써 금속 재질을 탈피하여 제품의 경량화, 내열성, 내마모성, 내식성을 이룰 수 있는 한편, 부드럽고 친근한 이미지의 제품디자인이 가능하다.

• 한국정밀공학회지
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• 제18권2호
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• pp.177-185
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• 2001

This study shows the process design and forming analysis of permalloy shielding can that support the automobile multi-display parts to indicate the accurate information of car. This study is particularly important, since the strain and thickness of permalloy shielding can is known to affect the magnetic properties such as coercivity and permeability quite thickness of permalloy shielding can is known to affect the magnetic properties such as coercivity and permeability quite sensitively. The objective functions are strain and thickness deviation. The punch radius, die radius and blank holding force are considered as design parameters. Orthogonal array (OA) table and characteristics are applied to neural network (NN) as train data. After training, the optimal and robust condition of design parameters is selected. This study shows the correlation between the design methodology of NN and the statistical design of experiments (DOE) approach.

• 한국의학물리학회지:의학물리
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• 제29권1호
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• pp.42-46
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• 2018

The purpose of this study was to perform a survey of the radiation shielding design goals (P) and workload (W) based on the radiation safety reports concerned with structural shielding design for the IMRT treatment technique in Tomotherapy vaults. The values of the P and W factors as well as of a verified concrete thickness of the ceiling, bottom, sidewalls (sidewall-1 and sidewall-2), and door have been obtained from radiation safety reports for a total of 16 out of 20 vaults. The recommended and most widely used report for P values was the NCRP No. 151 report, which stated that the P factor in controlled and uncontrolled areas was 0.1 and 0.02 mSv/week, respectively. The range of the W factor was 600~14,720 Gy/week. The absorbed dose delivered per patient was 2~3 Gy. The maximum number of patients treated per day was 10~70. The quality assurance (QA) dose was 100~1,000 Gy/week. Fifteen values of the IMRT factor (F) were mostly used but a maximum of 20 values was also used. The concrete thickness for primary structures including the ceiling, bottom, sidewalls, and door was sufficient for radiation shielding. The P and W factors affect the calculation of the structural shielding design, and several parameters, such as the absorbed dose, patients, QA dose, days and F factor can be varied according to the type of shielding structure. To ensure the safety of the radiation shielding, it is necessary to use the NCRP No. 151 report for the standard recommendation values.