• Progress in Superconductivity
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• 제3권1호
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• pp.99-103
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• 2001

We have conducted two runs of interlaboratory comparison on Ag-sheathed Bi-2223 tapes to evaluate the level of measurement techniques for the critical current measurement. Two classes of specimens were prepared for parallel and serial routings and sent to four participating laboratories. The critical currents of specimens were measured at 77 K in zero magnetic field. In the first comparison, we used twenty different Bi-2223 tapes as specimens for comparison and participating laboratories measured the specimens using their own instruments and procedures. As a result, the scattering of data on the first comparison showed -3.0% to +l2.2% for the parallel routing and -0.7% to +l5.1% for the serial routing. Major sources of these variations were attributed to different measurement techniques. Thus, the second comparison of measurement was done on the same specimens under specified measurement conditions, particularly in terms of cooling procedure and sweep rate of the test current. The variations for the second comparison were decreased -3.1% to +3.2% far the parallel routing and -1.8% to +7.7% fur the serial routing.

• 한국의학물리학회지:의학물리
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• 제33권4호
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• pp.108-113
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• 2022

Purpose: Proton therapy has been used for optimal cancer treatment by adapting its Bragg-peak characteristics. Recently, a tissue-sparing effect was introduced in ultrahigh-dose-rate (FLASH) radiation; the high-energy transmission proton beam is considered in proton FLASH therapy. In measuring high-energy/ultrahigh-dose-rate proton beam, Faraday Cup is considered as a dose-rate-independent measurement device, which has been widely studied. In this paper, the feasibility of the simply designed Faraday Cup (Poor Man's Faraday Cup, PMFC) for transmission proton FLASH therapy is investigated. Methods: In general, Faraday cups were used in the measurement of charged particles. The simply designed Faraday Cup and Advanced Markus ion chamber were used for high-energy proton beam measurement in this study. Results: The PMFC shows an acceptable performance, including accuracy in general dosimetric tests. The PMFC has a linear response to the dose and dose rate. The proton fluence was decreased with the increase of depth until the depth was near the proton beam range. Regarding secondary particles backscatter from PMFC, the effect was negligible. Conclusions: In this study, we performed an experiment to investigate the feasibility of PMFC for measuring high-energy proton beams. The PMFC can be used as a beam stopper and secondary monitoring system for transmission proton beam FLASH therapy.

• 기술혁신연구
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• 제31권1호
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• pp.105-148
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• 2023

본 논문은 Schumpeter의 기술변화 3단계 개념에 기초해서 기술진보가 실질경제성장에 기여하는 정도를 측정하는 새로운 방법을 제시한다. 통계청 광업제조업조사 마이크로데이터를 이용해서 2003-2018년 기간 동안 기술진보의 실질 성장기여 정도를 총요소 생산성 성장률(성장회계방법), R&D투자 기여율, 슘페테리안 혁신성장률로 각각 측정하고 비교한 결과는 다음과 같다. 첫째, 성장회계의 총요소생산성 성장률과 슘페테리안 혁신 성장률에 의한 기술진보의 실질 성장기여에 대한 측정에서 상반된 결과를 나타낸다. 둘째, 생산성장률이 감소추세에 있으면 증가추세에 있을 때와 비교해서 생산성장률과 총요소생산성성장률 차이가 커지고, 반대로 증가추세에 있으면 감소추세에 있을 때와 비교에서 생산성장률과 총요소생산성성장률의 차이가 작아진다. 셋째, 혁신성장률에 영향을 미치는 기술기회, 즉, 어느 한 분야의 연구개발과 그 인접분야까지의 연구개발 유인이 혁신성장에 미치는 기여도는 3.3%에 불과하다. 이 결과가 기존의 기술진보의 성장기여에 대한 인식과 다른 이유는 기술진보라는 동일한 용어를 측정하면서 서로 다른 실체를 측정하고 있는 것에 기인한다. 따라서 총요소생산성 성장률은 거시적 경제효율성, R&D투자는 신기술공급의 효과성, 슘페테리안 혁신성장률은 기술진보의 경제적 영향을 측정하는 데 사용해야 한다. 본 논문 연구 결과의 정책적 함의는 다음과 같다: ① 기술공급일변도의 정책에서 기술공급과 신기술수요지원의 융합정책으로 전환, ② 임무지향형 R&D 정책과 국가 R&D와 민간 R&D가 연계되는 R&D 정책, ③ 신지식체화 정도를 반영한 자본재의 재분류.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.48-52
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• 2017

Discrepancy between a power supply current and an actual "spiral" coil current makes the conventional 4-probe measurement of a critical current ($I_c$) of a no-insulation (NI) high temperature superconductor (HTS) coil inaccurate and time-consuming. This paper presents a fast and accurate approach for $I_c$ measurement of NI HTS coils. With an NI HTS coil energized at a constant ramping rate, a complete analytic expression for the spiral coil current was obtained from a first-order partial differential equation that derived from an equivalent circuit model of the NI coil. From the analytic solution, both spiral coil current and radial leak current can be obtained simultaneously, which enables fast and accurate measurement of the NI coil $I_c$. To verify the proposed approach, an NI double-pancake (DP) coil, wound with GdBCO tapes of $6mm{\times}0.1mm$, was constructed and its $I_c$ was repeatedly measured with various ramping rates in a bath of liquid nitrogen at 77 K. The measured results agreed well with the calculated ones, which validates the proposed approach to measure $I_c$ of an NI HTS coil.

• 한국초전도ㆍ저온공학회논문지
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• 제7권1호
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• pp.21-24
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• 2005

The problem of fluctuation-induced digital errors in a rapid single flux quantum (RSFQ) circuit has been very important issue. So in this experiment, we calculated error rate of RSFQ switch in superconductiyity ALU, The RSFQ switch should have a very low error rate in the optimal bias. We prepared two circuits Placed in parallel. One was a 10 Josephson transmission lines (JTLs) connected in series, and the other was the same circuit but with an RSFQ switch placed in the middle of the 10 JTLs. We used a splitter to feed the same input signal to the both circuits. The outputs of the two circuits were compared with an RSFQ XOR to measure the error rate of the RSFQ switch. By using a computerized bit error rate test setup, we measured the bit error rate of 2.18$\times$$10^{12}$ when the bias to the RSFQ switch was 0.398mh that was quite off from the optimum bias of 0.6mA.

• 동의신경정신과학회지
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• 제18권1호
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• pp.111-122
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• 2007

Objective : Progressive muscle relaxation(PMR) therapy is the way of mind and body self-regulation which makes major muscles tension to be comfortable condition. It was considered to be important to check the level of relaxation in objective validity. Therefore, Heart rate variability(HRV) is the valuable measurement to investigate the effect of progressive muscle relaxation therapy on autonomic nerve system. Method : I studied 38 subjects. The subjects were measured HRV at first. And then, Using a CD player, the subjects listened to recorded PMR program for 15 minutes. After this progress, I rechecked HRV. Results : heart rate item of HRV was significantly decreased. Also, the numerical value of SDNN(standard deviation of all NN intervals) and SDSD(standard deviation of differences between adjacent NN intervals) items of HRV were showed significantly increased in all subjects after PMR. Conclusion : It indicated that PMR is efficient for inspiring resistance of the stress and a sense of stability, and PMR is a valuable method to reduce the mind stress and stiffness of body muscle.

• 한국의학물리학회지:의학물리
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• 제5권1호
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• pp.67-74
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• 1994

선량분포특성은 거리의 제곱에 반비례하기 때문에 근접조사에서 선원의 조그마한 오차는 선량계산에서 큰 차이를 초래할 수 있어서 선원의 정확한 거리 이동과 그에 따른 critical organ에 조사되는 선량의 정확도는 자궁경부암 환자의 치료성적에 결정적인 역할을 할 수가 있다. 특히 High Dose Rate의 RALS(Remote After Loading System)에서 선원의 정확한 calibration은 자궁경부암 환자의 치료에서 선량분포에 지대한 영향을 미치며 나아가 이 선량분포는 치료후 나타나는 재발 및 합병증이나 휴유증의 발생에도 큰 영향을 미치게 된다. 본 연구에서는 실제 RALS시 선원의 거리 이동을 측정하여 치료계획용 computer에서 계산된 선원간의 거리 이동과 비교 검토하였으며 Rectum 위치에 chamber를 삽입하여 실제 Rectum에 조사되는 선량과 computer에서 계산된 값들을 비교검토하였다. Tandem Source을 1cm 간격으로 거리를 이동하면서 실험을 되풀이 한 결과 처음 monitor로 1cm을 이동할 때 측정치가 0.8cm 이동한 것으로 나타났으며, 2번째부터 5번째까지의 거리 이동에서는 monitor의 값과 측정치의 값이 정확하게 일치하였다. 또한 12명의 환자를 대상으로 실시한 Rectum dose의 측정치는 computer계산치보다 평균 8%로 낮게 나타났다.

• 한국의학물리학회지:의학물리
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• 제6권1호
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• pp.13-18
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• 1995

고선량의 RALS(Remote Afterloding Syetem)를 이용한 근접조사에서 선원의 위치에 따라 선량분포는 거리제곱의 반비례 형태로 변화되므로, 관심점의 흡수선량은 선원의 교정에 의해 크게 영향을 받는다. 자궁경부암 강내치료시 정확한 흡수선량을 결정하고자 선원을 교정하고, 선원의 위치에 따른 선량분포도에 의한 계산값과 반도체 검출기와 전리함을 이용한 설측값과 차이를 비교하고 보정 방법을 논의 하였다. Bulcher-RALS를 이용하여 치료에 사용된 선원의 교정은 공기커마와 사각형 아크랄 팬톰을 이용하여 r 인자에 의한 거리 역자승법칙으로 계산하였고, Co-60 선원의 8cm 거리에서 검교정된 측정기를 이용한 선량율을 비교치로 이용하였다. 선량측정치의 재현성은 팬톰내에서 0.3~1.1% 였으며, 측정치의 분포는 Bulcher-RALS 선량분포도에 의한 계산값과 팬톰측정치의 비교에서 -3~17%, 강내치료를 받은 18 명의 환자를 대상으로한 직장내 흡수선량에서 체내 실측값과 차이는 환자와 선원의 위치에 따라 -6~＋21%로 측정값이 평균 6.3% 높게 나타났다.

• 한국초전도ㆍ저온공학회논문지
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• 제16권2호
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• pp.64-69
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• 2014

Measuring an exact amount of remaining cryogenic liquid propellant under microgravity condition is one of the important issues of rocket vehicle. A Pressure-Volume-Temperature (PVT) gauging method is attractive due to its minimal additional hardware and simple gauging process. In this paper, PVT gauging method using liquid nitrogen is investigated under microgravity condition with parabolic flight. A 9.2 litre metal cryogenic liquid storage tank containing approximately 30% of liquid nitrogen is pressurized by ambient temperature helium gas. During microgravity condition, the inside of the liquid tank becomes near-isothermal condition within 1 K difference indicated by 6 silicon diode sensors vertically distributed in the middle of the liquid tank. Helium injection with higher mass flow rate after 10 seconds of the waiting time results in successful measurements of helium partial pressure in the tank. Average liquid volume measurement error is within 11% of the whole liquid tank volume and standard deviation of errors is 11.9. As a result, the applicability of PVT gauging method to liquid propellant stored in space is proven with good measurement accuracy.

• Progress in Superconductivity
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• 제3권1호
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• pp.36-40
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• 2001

We have studied vortex dynamics in$ Bi_2$$Sr_2$$CaCu_2$O$_{8}$single crystals of unirradiated and irradiated samples by using 100 $\times$ $100\mu\textrm{m}^2$Hall sensor. Doses equivalent magnetic fields are 20 G, 100 G and 1 kG. In the magnetization measurement, a second magnetization peak (SMP) was observed in unirradiated, 20 G dose and 100 G dose samples in contrast to 1 kG dose sample. In the unirradiated sample, the SMP was observed in the range of 18 K ~ 35 K and the amplitude of the SMP decreased with increasing temperature. With increase of the irradiation dose, temperature region and sharpness of the SMP were reduced. In the magnetic relaxation measurement, we observed that the normalized relaxation rate S decreased with increasing the irradiation dose. Our results suggest that the vortex dynamics is not greatly affected by low-density columnar defects.s.