• Composites Research
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• v.35 no.3
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• pp.175-181
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• 2022

Due to the increasing number of wireless communication devices in mmWave frequency bands, there is a high demand for electromagnetic interference (EMI) shielding and heat dissipating materials to avoid device malfunctions. This paper proposes an EMI shielding composite film with a high heat dissipation characteristic. To achieve this, a conductive grid is integrated with a polymer-based composite layer including magnetic and heat dissipating filler materials. A high shielding effectiveness (>40 dB), low reflection shielding effectiveness (<3 dB), high thermal conductivity (>10 W/m·K), thin thickness (<500 ㎛) are simultaneously achieved with a tailored design of composite layer compositions and grid geometries in 5G communication band of 26.5 GHz.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.271-281
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• 2019

This study investigated the shielding efficiency of various types of shielding materials and measured the dose by organ using the phantom. Results of Shielding Efficiency Measurement Using Personal Radiation Meter. Among the various shielding materials, 1.1 mm RNS-TX composed of nano tungsten showed the highest shielding efficiency and 0.2 mm lead shielding showed the lowest shielding efficiency. 99mTc 30 mCi was exposed to the phantom for 120 minutes and the result of the measurement of the organs. 20.53 mSv without radiation protective clothing, 8.75 mSv when wearing 0.25 mm Pb protective clothing, 6.03 mSv when wearing 0.5 mm Pb protective clothing. 131I 2 mCi mCi was exposed to the phantom for 120 minutes and the result of the measurement of the organs. 7.71 mSv without radiation protective clothing, 4.88 mSv when wearing 0.25 mm Pb protective clothing, 2.79 mSv when wearing 0.5 mm Pb protective clothing. 18F 5 mCi was exposed to the phantom for 120 minutes and the result of the measurement of the organs. 16.39 mSv without radiation protective clothing, 15.84 mSv when wearing 0.25 mm Pb protective clothing, 12.52 mSv when wearing 0.5 mm Pb protective clothing. None of the radiation workers working in the nuclear medicine department exceeded the dose limit. However, when compared with other workers in the hospital, they showed a relatively high dose. Therefore, it is necessary to prepare measures to reduce and manage the dose of radiation workers in the nuclear medicine department through the wearing of radiation protective clothing made of lightweight, shielding material with good shielding efficiency, circulation task, task sharing, and substitution equipment such as auto dispenser.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.1
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• pp.37-43
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• 2012

Radioactive waste transport package was developed to transport eight drums of low and intermediate level waste(LILW) in accordance with the IAEA and domestic related regulations. The package is classified with industrial package IP-2. IP-2 package is required to undergo a free drop test and a stacking test. After free drop and stacking tests, it should prevent the loss or dispersal of radioactive contents, and loss of shielding integrity which would result in more than 20 % increase in the radiation level at any external surface of the package. The objective of this study is to establish the safety test method and procedure for stacking test and to prove the structural integrities of the IP-2 package. Stacking test and analysis were performed with a compressive load equal to five times the weight of the package for a period of 24 hours using a full scale model. Strains and displacements were measured at the corner fitting of the package during the stacking test. The measured strains and displacements were compared with the analysis results, and there were good agreements. It is very difficult to measure the deflection at the container base, so the maximum deflection of the container base was calculated by the analysis method. The maximum displacement at the corner fitting and deflection at the container base were less than their allowable values. Dimensions of the test model, thickness of shielding material and bolt torque were measured before and after the stacking test. Throughout the stacking test, it was found that there were no loss or dispersal of radioactive contents and no loss of shielding integrity. Thus, the package was shown to comply with the requirements to maintain structural integrity under the stacking condition.

• Progress in Medical Physics
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• v.23 no.4
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• pp.234-238
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• 2012

A tumor on the eyelid is often treated using a high-energy electron beam, with a metallic eye shield inserted between the eyelid and the eyeball to preserve the patient's sight. Pretreatment quality assurance of the inner eyelid dose on the metallic shield requires a very small dosimetry tool. For enhanced accuracy, a flexible device fitting the curved interface between the eyelid and the shield is also required. The radiochromic film is the best candidate for this device. To measure the doses along the curved interface and small area, a 3-mm-wide strip of EBT2 film was inserted between the phantom eyelid and the shield. After irradiation with 6 MeV electron beams, the film was evaluated for the dose profile. An acrylic eye shield of the same size as the real eye shield was machined, and CT images free from metal artifacts were obtained. Monte Carlo simulation was performed on the CT images, taking into account eye shield material, such as tungsten, aluminum, and steel. The film-based interface dose distribution agreed with the MC calculation within 2.1%. In the small (millimeter scale) and curved region, radiochromic film dosimetry promises a satisfactory result with easy handling.

• Journal of Adhesion and Interface
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• v.18 no.2
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• pp.59-67
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• 2017

Recently, integration of parts is accelerating according to the growth of the smart mobile industry. The integration of these parts causes problems of interference phenomena between the parts, and the importance of electromagnetic wave shielding technology to solve this problem is highlighted. Electromagnetic wave shielding technology is implemented so as to reflect or absorb electromagnetic waves, and generally conductive materials are utilized for electromagnetic wave shielding. Transparent shielding technology is required according to recent industrial changes. In this research, we propose transparent the shielding film using imprint technology with conductive composite binder. Utilizing UV polymerized acrylic binder to produce a conductive composite binder. Spherical, plate and stacked silver particles were used for conductivity. The changes of the curing characteristics, conductivity and adhesion were observed according to the structural characteristics of the silver particles. The use of spherical particles was the most efficient in the curing process, and an additional curing system was required to complement the UV-shadowing structure. In the conductivity evaluation, the stacked structure showed excellent characteristics. The adhesion of spherical system was the best. It is evaluated as a result of irregularities on the surface. Ultimately, the patterned film using this showed excellent transparency characteristics.

• Journal of Radiation Protection and Research
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• v.30 no.1
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• pp.39-44
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• 2005

A new developing reactor isn't fixed the structure and the materials of reactor components. To perform the shielding analysis for a reactor vessel by $R-\theta$ geometry, it takes much effort and time to modeling of source term according to the change of reactor components every time. Therefore, we developed the shielding analysis system for the reactor vessel by $R-{\theta}$ geometry, which wasn't affected by the reactor core geometry. By using the developed shielding analysis system, we performed the shielding analysis for the reactor vessel of an integral reactor which has the hexagonal geometry of nuclear fuel assemblies in reactor core. We compared the results obtained from the developed system with those obtained from MCNP analysis. Because the results of developed shielding analysis system were more conservative than those of MCNP calculation, it is useful for shielding analysis. As we had developed the new shielding analysis system for a reactor vessel by $R-{\theta}$ geometry, we reduced error of model for reactor core which was formerly designed by hand and saved the time and the effort to design source term model of reactor core.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.345-345
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• 2007

본 연구는 x선 영상검출기 적용을 위한 $HgI_2$ 필름의 누설전류 특성 향상을 위한 연구로서, $HgI_2$기반의 다양한 물질을 이용하여 다층구조 방식으로 제작된 필름의 누설전류 특성평가 및 제작된 다층구조의 상부전극물질의 변화에 따른 누설전류 특성을 평가하였다. $HgI_2$기반 다층구조의 제작 물질은 Parylene, $PbI_2$, a-Se을 사용하여 시편(parylene/ITO, ITO/$HgI_2/PbI_2$/ITO, ITO/$HgI_2$/a-Se/ITO)을 제작하였으며, 필름 제작공정은 Screen print, PVD공정으로 다층구조 필름을 제작하였다. 또 한, 다층구조로 제작된 필름에 상부 전극물질은 Au, In, ITO를 사용하여 누설전류의 특성을 평가하였다. 측정 장치로 DC Power Supply(556H. EG&G : 50~200V), X 선 발생장치(Toshiba KXO-50N), 차폐체 (Al 및 Cu), Oscilloscope (LeCroy, LC334AM, USA), Electrometer (Keithley, 6517), Ion chamber 2060 (Radical Co.)을 이용하여, 제작된 $HgI_2$기반 다층구조 sample의 누설전류 특성을 실험하였다. 이 결과로 다층구조에 제작된 물질 및 상부전극에 따른 누설전류의 특성을 평가하였다.

• 전기의세계
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• v.42 no.5
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• pp.34-39
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• 1993

상온 초전도 물질의 발달과 더불어 초전도체의 응용분야 중의 하나인 MHD 추진선은 초전도체의 실용화가 이루어지면 추진기 없는 새로운 추진장치로써 큰 기대를 모으고 있다. 그러나 지금 현재까지 나타난 문제점들인 10-20 테스라급 정도의 고자장강도를 가진 초전도 코일의 제작, 선체 중량의 5% 이하로 줄일 수 있는 초전도 코일 시스템의 경량화, 강자장 발생에 따른 구조물의 지지문제, 누설자장을 최소화시킬 수 있도록 하는 자기 차폐문제, 전극문제들이 차례차례 해결된다면 꿈의 MHD 추진선은 반드시 실현될 것으로 생각된다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.103-106
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• 1999

감손우라늄(depleted uranium, DU)은 천연 우라늄에서 핵분열 물질인 U-235를 농축하는 과정에서 발생한다. U-235의 농도가 0.45%인 감손우라늄의 비방사능은 천연우라늄의 약70.8%에 분과하나 감손우라늄은 밀도가 19g/㎤으로 높고 천연우라늄에 비해 U-235의 농도가 상대적으로 낮기 때문에 외국의 경우는 방사선의 차폐체, 비행기나 헬리콥터 및 미사일의 무게중심제(counter-weight)로 사용되며 또한 플라이 휠 등 큰 내부에너지 저장을 위한 장치 등에 널리 이용되고 있다.(중략)

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.1
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• pp.87-95
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• 2015

Purpose : This study presents the usefulness assessment of secondary shield for the lens exposure dose reduction during radiation treatment of peripheral orbit. Materials and Methods : We accomplished IMRT treatment plan similar with a real one through the computed treatment planning system after CT simulation using human phantom. For the secondary shield, we used Pb plate (thickness 3mm, diameter 25mm) and 3 mm tungsten eye-shield block. And we compared lens dose using OSLD between on TPS and on simulation. Also, we irradiated 200 MU(6 MV, SPD(Source to Phantom Distance)=100 cm, $F{\cdot}S\;5{\times}5cm$) on a 5cm acrylic phantom using the secondary shielding material of same condition, 3mm Pb and tungsten eye-shield block. And we carried out the same experiment using 8cm Pb block to limit effect of leakage & transmitted radiation out of irradiation field. We attached OSLD with a 1cm away from the field at the side of phantom and applied a 3mm bolus equivalent to the thickness of eyelid. Results : Using human phantom, the Lens dose on IMRT treatment plan is 315.9cGy and the real measurement value is 216.7cGy. And after secondary shield using 3mm Pb plate and tungsten eye-shield block, each lens dose is 234.3, 224.1 cGy. The result of a experiment using acrylic phantom, each value is 5.24, 5.42 and 5.39 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Applying O.S.B out of the field, each value is 1.79, 2.00 and 2.02 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Conclusion : When secondary shielding material is used to protect critical organ while irradiating photon, high atomic number material (like metal) that is near by critical organ can be cause of dose increase according to treatment region and beam direction because head leakage and collimator & MLC transmitted radiation are exist even if it's out of the field. The attempt of secondary shield for the decrease of exposure dose was meaningful, but untested attempt can have a reverse effect. So, a preliminary inspection through Q.A must be necessary.