• Journal of Radiation Protection and Research
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• 제48권1호
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• pp.44-51
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• 2023

Background: Aptamers are currently being used in various fields including medical treatments due to their characteristics of selectively binding to specific molecules. Due to their special characteristics, the aptamers are expected to be used to remove radionuclides from a large amount of liquid radioactive waste generated during the decommissioning of nuclear power plants. The radiological effects on the aptamers should be evaluated to ensure their integrity for the application of a radionuclide removal technique. Materials and Methods: In this study, Monte Carlo N-Particle transport code version 6 (MCNP6) and Monte Carlo damage simulation (MCDS) codes were employed to evaluate the radiological effects on the aptamers. MCNP6 was used to evaluate the secondary electron spectrum and the absorbed dose in a medium. MCDS was used to calculate the DNA damage by using the secondary electron spectrum and the absorbed dose. Binding experiments were conducted to indirectly verify the results derived by MCNP6 and MCDS calculations. Results and Discussion: Damage yields of about 5.00×10^-4 were calculated for 100 bp aptamer due to the radiation dose of 1 Gy. In experiments with radioactive materials, the results that the removal rate of the radioactive ⁶⁰Co by the aptamer is the same with the non-radioactive ⁵⁹Co prove the accuracy of the previous DNA damage calculation. Conclusion: The evaluation results suggest that only very small fraction of significant number of the aptamers will be damaged by the radioactive materials in the liquid radioactive waste.

• 조명전기설비학회논문지
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• 제12권3호
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• pp.114-123
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• 1998

The multi-resonant converter(MRC) minimizes a parasitic oscillation by using the resonant tank circuit absorbed parasitic reactances existing in a converter circuit. So it si possible that the converter operated at a high frequency has a high efficiency because the losses are reduced. Such a MHz high frequency applications provide a high power density [W/inch3] of the converter. But the resonant voltage stress across a switch of the resonant tank circuit is 4~5 times a input voltage. This h호 voltage stress increases the conduction loss because of on-resistance of a MOSFET with higher rating. Thus, in this paper we proposed the alternated multi-resonant converter (AT MRC) differ from the clamp mode multi-resonant converter and applicated it to the forward MRC. The AT forward MRC can reduce the voltage stress to 2~3 times a input voltage by using two series input capacitor. The control circuit is simple because tow resonant switches are driven directly by the output pulse of the voltage controled oscillator. This circuit type is verified through the experimental converter with 48V input voltage, 5V/50W output voltage/power and PSpice simulation. the measured maximum voltage stress is 170V of 2.9 times the input voltage and the maximum efficiency of 81.66% is measured.

• 한국전자파학회논문지
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• 제7권4호
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• pp.353-362
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• 1996

본 논문에서는 토끼를 대상으로 하여 그 두부에 전자파가 조사(照射)된 경우에 대해 토끼 두부를 3충 구모델로 근사해서 SAR분포를 계산하였다. 계산 결과를 확인하기 위해 주파수 2,450MHz인 마이크로파를 출력세기별로 5그룹으로 설정하여 각각에 대한 노출 전 후의 EEG를 전두부(前頭部)에서 측정하였다. 실험에서 전자파 조사 후에는 뇌전위의 전체평균값은 조금 감소히였고, 특히 $\theta$, $\delta$그리고 $\beta$파의 평균합성비율은 증가하였다. 이 결과는 마이크로파 조사후 전기적 생리활동의 감소와 뇌파의 속파화 경향을 나타낸다. 측정된 뇌전위로써 생체에 대한 전기 생리적 효과를 정량적으로 파악하여 최대허용노출(Maximum Permissible Exm posure)의 객관적인 추정을 하였다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
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• pp.155-156
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• 2012

In the modern age, as man's demand of energy is continuously grew, tidal becomes one of the sustainable energy sources that have been investigating thoroughly recently. Tidal turbine has proved high potential as a future power-generating device. To effectively capture tidal energy on site, a group of tidal turbines should be used and positioned in some formation with proper size and space so that energy can be absorbed from multiple point. Thus, the turbines together with the flow filed becomes a huge domain, a tidal farm. So, it becomes more convenient if a whole turbine farm is simulated by means of actuator discs since the time and cost for analysis can be reduced. This paper aims to evaluate the operating performance (power efficiency and energy restoration rate), mutual influence (for different longitudinal and lateral spaces), the influence of velocity profiles, turbulence intensity and the far wake characteristic of tidal turbines operating in farm formation. The results of this study help contributing to the present development of tidal turbine as the future potential energy conversion machinery.

• 한국광학회지
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• 제3권4호
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• pp.222-226
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• 1992

$Ar^{+}$레이저로 펌핑되는 Nd:glass레이저를 제작하여 그 특성을 조사하였다. 레이저 공진기는 오목거울 두 개와 98% 고반사 평면경, 그리고 Brewster 각도로 놓인 Nd:glass 의 이득 매질로 구성되었으며, 효율적인 펌핑을 위해서 $Ar^{+}$레이저 광선을 공진기 길이 방향으로 입사하여 공진모우드의 beam waist에서 초점이 맺히도록 하였다. Nd:glass의 열존도도가 작아서 흡수된 펌핑빔에 의해 생성된 잔열로 인한 매질의 손상이 우려되기 때문에 mechanical chopper 로 펌핑빔을 100Hz로 끊어서 입사하여 잔열의 생성을 줄였다. 1.5W로 펌핑될 때 Nd:glass 레이저의 출력은 70mW이었고 발진이 되는 문턱에서의 펌핑파워는 520mW이었으며 slope efficiency는 7.4%이었다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.275-281
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• 2011

Solar reforming of methane with $CO_2$ was successfully tested with a direct irradiated absorber on a parabolic dish capable of $5kW_{th}$ solar power. The new type of catalytically activated metallic foam absorber was prepared, and its activity was tested. Ni was applied as the active metal on the gamma - alumina coated Ni metal foam for the preparation of the catalytically-activated metal foam layer. Compared to conventional direct irradiation of the catalytically-activated ceramic foam absorber, this new metallic foam absorber is found to exhibit a superior reaction performance at the relatively low insolation or at low temperatures. In addition, unlike direct irradiation of the catalytically-activated ceramic foam absorber, metallic foam absorber has better thermal resistance, which prevents the emergence of cracks caused by mechanical or thermal shock. The total solar power absorbed reached up to 2.1kW and the maximum $CH_4$ conversion was almost 40%.

• Nuclear Engineering and Technology
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• 제39권5호
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• pp.591-602
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• 2007

The results of Reactivity-Initiated Accidents (RIA) experiments have been analysed and the main variables affecting the fuel failure propensity identified. Fuel burn-up aggravates the mechanical loading of the cladding, while corrosion, or better the hydrogen absorbed in the cladding as a consequence of corrosion, may under some conditions make the cladding brittle and more susceptible to failure. Experiments point out that corrosion impairs the fuel resistance for RIA transient occurring at cold conditions, whereas there is no evidence of important embrittlement effects at hot conditions, unless the cladding was degraded by oxide spalling. A fuel failure threshold correlation has been derived and compared with experimental data relevant for BWR and PWR fuel. The correlation can be applied to both cold and hot RIA transients, account taken for the lower ductility at cold conditions and for the different initial enthalpy. It can also be used for non-zero power transients, provided that a term accounting for the start-up power is incorporated. The proposed threshold is easy to use and reproduces the results obtained in the CABRI and NSRR tests in a rather satisfactory manner. The behaviour of advanced PWR alloys and of MOX fuel is discussed in light of the correlation predictions. Finally, a probabilistic approach has been developed in order to account for the small scatter of the failure predictions. This approach completes the RIA failure assessment in that after determining a best estimate failure threshold, a failure probability is inferred based on the spreading of data around the calculated best estimate value.

• Journal of the Optical Society of Korea
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• 제20권6호
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• pp.778-783
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• 2016

We synthesized $Er^{3+}-Yb^{3+}$, $Pr^{3+}-Yb^{3+}$, and $Er^{3+}-Pr^{3+}-Yb^{3+}$ -doped oxyfluoride glass ceramics containing $CaF_2$ nanocrystals by proper thermal treatments. Spectral characteristics of down- and up-converted emissions in three kinds of glass ceramics under 365-nm and 980-nm excitations were compared and explained by cross relaxations, excited-state absorptions, and energy-transfer processes between different ions. The huge reduction of up-conversion emission in the triply doped glass ceramics under 980-nm excitation compared to the $Er^{3+}-Yb^{3+}$ codoped one was explained by the split pump power and the direct energy transfer from $Er^{3+}$ to $Pr^{3+}$ ions. Increasing $Yb^{3+}$ concentration from 2% to 10% in the triply doped glass ceramics showed more than quadratic enhancement of the absorbed power, and we explained it by the enhanced energy-transfer efficiency from $Yb^{3+}$ to $Er^{3+}$ ions. We also observed enhanced up-converted emissions of $Er^{3+}$ and $Pr^{3+}$ ions in three kinds of glass ceramics under simultaneous excitation at 980 nm and 1550 nm, and suggested detailed up-conversion mechanisms.

• Journal of Power Electronics
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• 제16권1호
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• pp.238-248
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• 2016

The state-of-charge (SOC) and state-of-health (SOH) estimation of batteries play important roles in managing batteries for automotive applications. However, an accurate state estimation of a battery is difficult to achieve because of certain factors, such as measurement noise, highly nonlinear characteristics, strong hysteresis phenomenon, and diffusion effect of batteries. In certain vehicular applications, such as idle stop-start systems (ISSs), significant errors in SOC/SOH estimation may lead to a failure in restarting a combustion engine after the shut-off period of the engine when the vehicle is at rest, such as at a traffic light. In this paper, a dual extended Kalman filter algorithm with a dynamic equivalent circuit model of a lead-acid battery is proposed to deal with this problem. The proposed algorithm adopts a battery model by taking into account the hysteresis phenomenon, diffusion effect, and parameter variations for accurate state estimations of the battery. The validity of the proposed algorithm is verified through experiments by using an absorbed glass mat valve-regulated lead-acid battery and a battery sensor cable for commercial ISS vehicles.

• 동력기계공학회지
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• 제18권4호
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• pp.104-111
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• 2014

In this study, EH36 is thick steel plate, which welded by auto $CO_2$ gas welding machine, has been applied on offshore filed. The specimen was examined by indentation tester and it was measured for fracture toughness at $18^{\circ}C$, $0^{\circ}C$, $-20^{\circ}C$ and $-45^{\circ}C$ by low temperature chamber, respectively. The absorbed energy was got on same temperature by Charpy impact tester. The weld surface was observed for watch of changed crystalline structure by optical microscope, and fracture surface of impact test specimen were observed by scanning electron microscope(SEM).