• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.861-868
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• 2017

In this study, a novel magnetic field generator, using a shielding effect for controlling the dynamic stiffness and damping of magnetorheological gels, is proposed. A magnetorheological gel is a smart material that can alter its stiffness and damping, and it can be used as a vibration absorber and in vehicle suspension. It is necessary to control the magnetic field to use magnetorheological gels in various applications. There are two types of magnet field generators, namely the electromagnet and permanent magnet, and the electromagnet is generally used in practical applications. However, owing to its limitations, the electromagnet is not suitable for long-term use. Therefore, in this paper, a novel magnetic field generator is proposed to address such problems for use in real applications.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.248-255
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• 2018

It is known that the road noise on the rear seat of a hatchback type car is worse than that of a sedan type car because of the weakness on sealing structure. Therefore, a sound sealing system and sufficient absorption/insulation performance are required. In the case of a compact segment car, however, the application of the sufficient absorption and insulation materials is limited, because of the restriction on the production cost and weight of the car. In this study, we estimate the noise transmission path on the vehicle's body structure from tires and ground using the PBNR (Power Based Noise Reduction) method which is useful in quantitative measurement. Based on these results, we suggest an alternative absorption/insulation method for the better performance of rear seat road noise reduction in a compact hatchback car.

• Analytical Science and Technology
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• v.13 no.4
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• pp.474-483
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• 2000

An inductively coupled plasma atomic emission spectrometer/shielding system was specially designed and built for the analysis of radioactive materials. Both of an inductively coupled plasma source and a sample transfer system to be contacted with radioactive materials was installed in a stainless steel glove box. In terms of analytical capability and radiation safety, characteristic feature of the system was investigated. Its applicability to the determination of fission products and corrosion products in the radioactive materials such as spent fuel dissolver solution and the primary coolant of nuclear power reactors was evaluated. In the concentration range $0.01-0.1mgL^{-1}$, the relative standard deviation was found to be less than 5%.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.73-83
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• 2022

The purpose of this paper was to identify a method to improve received noise in a specific frequency band, caused by RF radiation signals during aircraft operation. The communication equipment of the aircraft is critical to the performance and safety of the flight mission, as it is responsible for the function of internal and external communications. Noise-free, clean communication quality, as well as transmission and receiving functions have to be implemented. Thus, the cause analysis of the reception noise in a specific frequency band, was analyzed through trouble shooting. The receiving noise due to the RF radiation signal emitted from the subsystem unit inside the aircraft, was improved by shielding with a CAP with electroless nickel plating applied. Additionally, the measurement and verification results of the improvement method are also described.

• Progress in Medical Physics
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• v.26 no.4
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• pp.250-257
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• 2015

Multi-leaf collimator (MLC) systems are frequently used to deliver photon-based radiation, and allow conformal shaping of treatment beams. Many proton beam centers currently make use of aperture and snout systems, which involve use of a snout to shape and focus the proton beam, a brass aperture to modify field shape, and an acrylic compensator to modulate depth. However, it needs a lot of time and cost of preparing treatment, therefore, we developed the manual MLC for solving this problem. This study was carried out with the intent of designing an MLC system as an alternative to an aperture block system. Radio-activation and dose due to primary proton beam leakage and the presence of secondary neutrons were taken into account during these iterations. Analytical calculations were used to study the effects of leaf material on activation. We have fabricated tray model for adoption with a wobbling snout ($30{\times}40cm^2$) system which used uniform scanning beam. We designed the manual MLC and tray and can reduce the cost and time for treatment. After leakage test of new tray, we upgrade the tray with brass and made the safety tool. First, we have tested the radio-activation with usually brass and new brass for new manual MLC. It shows similar behavior and decay trend. In addition, we have measured the leakage test of a gantry with new tray and MLC tray, while we exposed the high energy with full modulation process on film dosimetry. The radiation leakage is less than 1%. From these results, we have developed the design of the tray and upgrade for safety. Through the radio-activation behavior, we figure out the proton beam leakage level of safety, where there detects the secondary particle, including neutron. After developing new design of the tray, it will be able to reduce the time and cost of proton treatment. Finally, we have applied in clinic test with original brass aperture and manual MLC and calculated the gamma index, 99.74% between them.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2171-2174
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• 2008

The design of thermal radiation shield cooled by a cryocooler is presented. This study is motivated mainly by our recent development of prototype superconducting magnet system for the Cyclotron K120. The superconducting magnet system is composed of the magnet cryostat, transfer line and supply cryostat. In order to minimize thermal radiation load, the superconducting coil form in the magnet cryostat is enclosed by the thermal radiation shield which is thermally connected to the first-stage cold head of a two-stage cryocooler in the supply cryostat. Since the supply cryostat is located far from the magnet cryostat large temperature gradient along the thermal shield is unavoidable. In this paper, the thermal radiation shield is optimized to minimize temperature gradient with taking into account the cryogenic load, system structure and electrical load. The effect of heat source from thermal conduction through mechanical supports on the temperature distribution of thermal radiation shield is also discussed.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.407-408
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• 2003

다중입력조건에 따른 단일 출력퍼지시스템인 인구밀도와 도로조건에 따른 소개속도의 모델링시스템에서는 인구밀도와 도로조건의 퍼지멤버쉽에 대한 소개속도의 상승작용을 확인할 수 있었다. 그러나 도로조건을 평가하는 방법을 포장과 비포장으로만 구분함으로 인해 발생하는 퍼지추론과정에서 비탄력성은 향후 도로조건에 대한 세밀한 조사를 통하여 퍼지멤버쉽함수의 형태를 재고해야 할 것으로 판단된다. 실제 원자력시설에서 발생할 수 있는 사고의 경우 방사능에 노출될 수 있는 일반대중은 방사능에 대한 깊은 지식을 가지지 못하는 경우가 대부분이다. 따라서 차폐효과 혹은 소개속도를 정량적으로 파악하기 힘든 경우가 많다. 따라서, 이러한 퍼지시스템은 방사선 비상대응 시스템을 개발하는 의사결정자나 비상시 방사능에 노출되는 사람들의 대응 방식을 모델링하는데 유용할 것으로 판단된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.603-604
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• 2017

In this paper, we propose system that automatically controlls greenhouse to make best environment to grow crops. The proposed system is consist of the function to automatically open and close water-roof, control the tublar well of groundwater and remote monitor information of greenhouse.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2031-2033
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• 2004

In this paper, electromagnetic wave environment generated from electronic equipments was investigated. Since the main source of electromagnetic waves are electronic equipments, the field intensity of a harmful electromagnetic wave was measured and its harmful level was analyzed. It was also found that the result was 23%${\sim}$38% in case of TV set and microwave oven. Based on this analysis, this study proposed efficient shielding method to suppress unwanted electromagnetic wave.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.10a
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• pp.351-354
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• 2003

최근 안전 분야에서 기능성 고분자 재료의 응용분야로서 첨단 전기전도성 고분자복합재료를 이용한 섬유상, 구형, flake 등 각종 형상의 금속, 흑연, carbon black, whisker 등의 전도성 filler를 고분자 matrix에 혼입하여 전도성 고분자를 성형가공하여 복합성형체를 제조하고 electrical hazard를 감소시키기 위한 정전기방지효과, 자기발열체, 전자기파 차폐효과 등의 특성을 나타내는 고분자 성형체상으로 가공된 소재로 화학공장, 산업설비, 각종 제조설비의 제조 공정용 제어, 과전류차단 및 외부 전자기파에 의해 발생되는 이상작동 등을 방지하는 안전시스템 소재용으로서 다양하게 사용되고 있다.(중략)