• 방사선산업학회지
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• 제17권4호
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• pp.443-449
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• 2023

KAERI(Korea Atomic Energy Research Institute) is conducting research and development of large-scale radiation generators and the latest radiation measuring instruments. In particular, research and development of security screening equipment using an electron beam accelerator and a neutron generator is in progress recently. Globally, 20 ft containers are used to transport imports and exports, and electron beam accelerators are radiation sources to measure the shape of the material inside the container during customs inspections in each country. KAERI is developing a device that can use an electron beam accelerator and a neutron generator sequentially to grasp the shape of various materials as well as the location of the internal target material. In this study, when using the neutron generator, the radiation dose and the degree of activation by neutron for the facility and surrounding environment, facility equipment were simulated using MCNP and FISPACT code. As a result, the shielding structures inside and outside the radiation control area were satisfactory to the reference level established conservatively based on the Korean Nuclear Act.

• 전기학회논문지
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• 제56권6호
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• pp.1130-1132
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• 2007

In this research, 3D position exploring system was developed to detect direction and position of radiation source by using two general CCD camera. This system consists of a radiation detection device, a controlling device, and a monitoring device. A radiation detection device is composed of a collimator, a scintillator, CCD sensor, and radiation shielding part. Incident radiation is firstly collimated with direction and converted into visual lights in a scintillator. The CCD sensor detect the converted visual light and send a signal as an image. This can explore a radiation source with direction and distance from geometrical structure of two sensors. From these information, the developed 3D position exploring system can provide 3D radiation source information. This research will be useful for managing and processing radioactive materials in remote.

• 진공이야기
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• 제3권3호
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• pp.19-23
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• 2016

BNNTs (Boron nitride nanotubes) is an analogue of CNTs (Carbon Nanotubes) in terms of lattice structure. In BNNTs, a boron atom forms sp2 hybridized bonding with three nitrogen atoms, and so does a nitrogen with three boron atoms in the honeycomb structure. Its innovative properties, such as high thermal conductivity, neutron shielding capability, superb oxidation resistance at $900^{\circ}C$, excellent chemical resistance, and superior mechanical properties are advantageous for a wide range of applications, especially for electric device packages, neutron shielding, protective coating materials, and functional composites. In this paper, boron nitride nanotube synthesis, properties and application are reviewed.

• 한국초전도ㆍ저온공학회논문지
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• 제15권2호
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• pp.20-23
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• 2013

For sensitive measurements of micro-Tesla nuclear magnetic resonance (${\mu}T$-NMR) signal, a low-noise superconducting quantum interference device (SQUID) system is needed. We have fabricated a liquid He dewar for an SQUID having a large diameter for the pickup coil. The initial test of the SQUID system showed much higher low-frequency magnetic noise caused by the thermal magnetic noise of the aluminum plates used for the vapor-cooled thermal shield material. The frequency dependence of the noise spectrum showed that the noise increases with the decrease of frequency. This behavior could be explained from a two-layer model; one generating the thermal noise and the other one shielding the thermal noise by eddy-current shielding. And the eddy-current shielding effect is strongly dependent on the frequency through the skin-depth. To minimize the loop size for the fluctuating thermal noise current, we changed the thermal shield material into insulated thin Cu mesh. The magnetic noise of the SQUID system became flat down to 0.1 Hz with a white noise of 0.3 $fT/{\surd}Hz$, including the other noise contributions such as SQUID electronics and magnetically shielded room, etc, which is acceptable for low-noise ${\mu}T$-NMR experiments.

• KEPCO Journal on Electric Power and Energy
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• 제1권1호
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• pp.15-20
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• 2015

To examine the magnetic shielding effect for carbon-based materials at extremely low frequencies (60 Hz), two types of carbon black (Super-P and Denka Black) and a natural graphite (HC-198) were mixed into organic binder at 10 wt.% to produce a coating solution, and a powder coating with varying thickness was applied on an aluminum disk measuring 88 mm in radius. A device was developed to measure the sheielding effect at extremely low frequencies. A closed circuit was achieved by connecting a transformer and a resistor. The applied voltage was fixed at 65 V, and the magnetic field was measured to being the range of 4.95~5.10 mG. Depending on the thickness of the coating layer, the magnetic field showed a decreasing trend. The maximum decrease in the magnetic field of 38.3% was measured when natural graphite was coated with specimens averaging $455{\mu}m$. This study confirmed that carbon-based materials enable magnetic shielding at extremely low frequencies, and that the magnetic shielding effect can be enhanced by varying the coating thickness.

• 한국결정성장학회지
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• 제29권3호
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• pp.123-131
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• 2019

본 연구에서는 $TiO_{2-x}$ 산화물 박막공정을 이용한 유해 자외선차단 투명 유연 소재를 개발하고자한다. 자외선 차단 특성: 자외선 파장대의 315 nm 차단율이 95 % 이상이면서, 자외선차단특성을 갖으면서 투명성을 높인 가시광선 투과율 78 % 이상(550 nm에서 전광투과율)의 시료를 만드는 공정기술을 개발하고자 하였다. 본 연구 결과로 고성능 자외선차단 박막의 유연 소자 공정조건을 확립하고, 이질성 특성의 투명 유연 소자의 혼합형 설계와 시장 요구에 다양하게 대응이 가능한 복합 증착 기술 정립, 롤투롤(roll-to-roll) 연속 공정의 실현 및 장비, 공정 국산화 기술 확립으로써 관련 산업으로의 기술 파급 효과가 클 것으로 사료된다.

• 한국전기전자재료학회논문지
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• 제33권2호
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• pp.83-87
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• 2020

In this letter, we propose and analyze a new asymmetric structure that can be used for next-generation power semiconductor devices. We compare and analyze the electrical characteristics of the proposed device with respect to those of symmetric devices. The proposed device has a p-emitter on the right side of the cell. The peak electric field is reduced by the shielding effect caused by the p-emitter structure. Consequently, the breakdown voltage is increased. The proposed asymmetric structure has an approximately 100% higher Baliga's figure of merit (~94.22 MW/㎠) than the symmetric structure (~46.93 MW/㎠), and the breakdown voltage of the device increases by approximately 70%.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2008년도 춘계학술발표대회 개요집
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• pp.17-17
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• 2008

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.147-148
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• 2023

Steel doors, which are common in general buildings, do not seal the gap between the door and the floor, so drafts, noise, dust, and lights flow from the outside, and shielding devices are installed in various materials and methods, such as adding magnetic gate paper to the side of the door or installing a gasket under the door, but performance is limited. Accordingly, in order to fundamentally solve these problems, we researched and developed a double gap blocking device that can improve fire resistance and airtightness performance in steel doors. Unlike general products, the double gap blocking device has the advantage of maximizing airtight performance by forming an air layer in the center when the door is closed, as well as greatly improving the fire resistance performance, which is the basic performance of the fire door.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2412-2420
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• 2024

The International Atomic Energy Agency (IAEA) mandates safeguards to ensure non-proliferation of nuclear materials. Among inspection techniques used to detect partial defects within spent nuclear fuel (SNF), gamma emission tomography (GET) has been reported to be reliable for detection of partial defects on a pin-by-pin level. Conventional GET, however, is limited by low detection efficiency due to the high density of nuclear fuel rods and self-absorption. This paper proposes a new type of GET named Spent Fuel Internal Tomography (SFIT), which can acquire sinograms at the guide tube. The proposed device consists of the housing, shielding, C-shaped collimator, reflector, and gadolinium aluminum gallium garnet (GAGG) scintillator. For accurate attenuation correction, the source-distinguishable range of the SFIT device was determined using MC simulation to the region away from the proposed device to the second layer. For enhanced inspection accuracy, a proposed specific source-discrimination algorithm was applied. With this, the SFIT device successfully distinguished all source locations. The comparison of images of the existing and proposed inspection methods showed that the proposed method, having successfully distinguished all sources, afforded a 150 % inspection accuracy improvement.