핵연료 피복관용 Zr 합금의 열처리에 다른 미세조직 및 부식특성

정용환,이명호,박상윤,김환철 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.12

The effects of final annealing temperature on microstructure and corrosion behavior of Zr-based alloys were investigated. Four kinds of Zr alleys were used for microstructural study and corrosion teat. Corrosion tests were carried out in static mini autoclave under 400℃ steam condition. Microstructures were analyzed by using TEM/EDS and image analyzer. The grain size and precipitate size of Zircaloy-4 increased with increasing the annealing temperature. As the annealing temperature increased, the corrosion resistance of Zircaloy-4 also increased due to the increase of precipitate size and grain size. Therefore, the precipitate size and grain size play an important role on the control of corrosion resistance of Zircaloy-4. However, it was considered from this study that the corrosion resistance of Nb-containing alloys would be controlled by the characteristics of beta phase rather than precipitate size.

Zr 합금의 석출물 및 부식특성에 미치는 Fe 와 Mn 첨가 영향

김현길,위명용,정용환,이명호,박상윤 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.11

In order to Investigate the effects of Fe and Mn on the precipitate and corrosion characteristics of Zr based alloys for nuclear fuel cladding, autoclave corrosion tests on the ternary(Zr-0.8Sn-X) alloys have been carried out at 360℃. The corrosion behavior of Zr-Sn-Fe alloy showed the cubic corrosion rate in the pre-transition region and the linear corrosion rate in the post-transition region. The good corrosion resistance in Zr-Sn-Fe alloy system was observed in Fe contents more than 0.2 wt%. The corrosion behavior of Zr-Sn-Mn alloy was significantly accelerated from the early stage. The lowest weight gain was observed in 0.2 wt% Mn. Based on the precipitate anallysis by TEM, it is thought that the corrosion of Zr-alloys would be related to the size of precipitate.

다공질 박막을 이용한 FET 형 용존 산소 센서의 유속 의존성 개선

김영진,손병기,이영철,정훈 경북대학교 전자기술연구소 2001 電子技術硏究誌 Vol.22 No.2

FET type dissolved oxygen sensor was proposed to overcome the disadvantages of the amperometric Clark sensor. The inherent problem of the proposed sensor, however, is the flow dependence of the sensor performances since the proposed sensor detects the pH change in close proximity to the working electrode. In this study, a hydrodynamic porous thin film which can reduce the flow dependence were proposed the suggested porous thin film were formed onto sensing area and working electrode with mixed polymer matrix of TEOS and DEDMS.

핵연료 피복관용 Zircaloy-4 및 Zr-Nb 합금의 열처리에 따른 부식 및 기계적 특성 평가

김현길,정용환,이명호,윤영균 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.7

Effects of final annealing temperature on the corrosion and mechanical behavior, and microstructure were investigated for Zircaloy-4(Zr-1.3Sn-0.2Fe-0.1Cr), Alloy-1(Zr-0.4Nb-0.6Sn-0.4Fe-0.2Cu) and Alloy-2(Zr-1Nb). The corrosion tests were carried out in 360℃ water and 70 ppm LiOH solution in the static mini autoclaves. The mechanical tests were performed using the universal material test machine. The corrosion rate of Zircaloy-4 was not accelerated as the precipitates on Zircaloy-4 grew with the increase of annealing temperature after recrystallization. But the corrosion rate of Alloy-1 and 2 was accelerated due to the formation and growth of β-Zr phases with increasing the annealing temperature. Therefore, the corrosion resistance of the Zr-Nb alloy system could be improved by the control of heat treatment. It was also confirmed that the mechanical properties of Zr-based alloys were affected by the addition of alloying elements, the recrystallization, and the precipitation with annealing temperature.

Zr-xNb 2원계 합금의 미세조직과 부식특성에 미치는 Nb 의 영향

김현길,임윤수,위명용,정용환 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.5

To develop the advanced Zr alloy for nuclear fuel cladding, the microstructure and corrosion characteristics of Zr-xNb binary alloys were studied of Nb addition. Microstructural observation and corrosion behavior of Zr-xNb alloys with niobium content were carried to develop an advanced nuclear fuel cladding materials. Niobium addition results in refining the final grain size, increasing precipitation in matrix and reducing corrosion resistance of the alloy in 360℃, 18.9㎫ water. The alloy with 0.2 wt.% Nb, especially, showed the highest corrosion resistance in this study which was related to columnar structure of the oxide and relatively high content of tetra-ZrO₂. This supports that the corrosion behavior of the Zr-Nb alloy significantly depended on the microstructure and composition of the oxide. mom the XRD analysis, SEM study and TEM observation on the oxide having equal oxide thickness, the 0.2 wt.% Nb alloy showing the best corrosion resistance had higher fraction of tetra-ZrO₂ and columnar structure than other alloys. Therefore, it is considered that the corrosion of Zr-xNb binary alloy would be controlled by the oxide characteristics like tetra-ZrO₂ and equiaxed structure.

MEMS 및 센서 시스템 ; FET 형 이온센서용 무선원격측정시스템

김영진,손병기,이영철,정훈 한국센서학회 2001 센서학회지 Vol.10 No.3

A wireless telemetry measurement system, using ISFETs, was developed for environmental monitoring applications, industrial processes, medical treatments and so on. This system is composed of the measurement part located at remote site and a personal computer(PC) which control whole instrument process. The measurement part transmits measured data to the PC by RF transceiver, and transmitted data are analyzed and handled in the PC. Proposed system utilizing time division multiplexing for the transmission of 3channel ISFET signal. The measurement part has an identification number(ID) so that the PC controls many measurement parts separately. Experiments were performed using pH-ISFETs, and the implemented system operates well within designed specification and accuracy of 0.1 pH.

화재완화를 위한 소듐 루프 건물의 구획화

김병호,권상운,정경채,김광락,황성태 한국산업안전학회 1998 한국안전학회지 Vol.13 No.3

Analysis on the study for the sodium fire mitigation was carried out using the CONTAIN-LMR code. Sodium loop building was partitioned into the many cells, in which the safety venting systems were installed for the purpose of improving the sodium fire safety and minimizing its effect on the sodium loop building. The effects of sodium fire on sodium loop building partitioned into the many cells and not partitioned were investigated. The peak pressure and temperature of each cell accompanied by sodium fire in sodium loop building partitioned were lower than those of sodium loop building not partitioned. In the case of partitioning sodium loop building, the pressures, temperatures and aerosols into cells were transferred through propagation path of CONTAIN-LMR sodium fire model simulated by this study, and the effect of sodium spray fire on sodium loop building was mitigated by partitioning building. In addition, the excessive rise of pressure into cells was prevented by installing the over-pressure exhaust valve and under-pressure exhaust valve on the flow path between cells.

FET 형 용존 산소 센서의 유속에 의한 영향 조사와 감쇄 기법

김영진,손병기,이영철,정훈 한국센서학회 2001 센서학회지 Vol.10 No.3

Recently, FET type dissolved oxygen sensor was proposed to overcome the disadvantages of the amperometric Clark-type sensor. The inherent problem of the proposed sensor, however, is the flow dependence of the sensor perfomances since the proposed sensor detects the pH change in clue proximity to the working electrode. In this study, we decided the direction which minimize the flow effect in FIA(flow injection analysis) system. And a hydrodynamic buffer layer which can reduce the flow dependence were proposed. The suggested buffer-layers were formed onto sensing area and working electrode with mixed polymer matrix of TEOS(tetraethylorthosilicate) and DEDMS (diethoxydimethylsilane).

수평방향의 정현파 가진을 받는 강체 블록의 비선형 로킹진동특성

김지훈,김정호,양인영,정낙규,정만용 한국산업안전학회 1999 한국안전학회지 Vol.14 No.4

This research concentrates on the influence of non-linearities associated with impact for the nonlinear rocking behavior of rigid block subjected to one dimensional sinusoidal excitation of horizontal direction. The transition of two governing rocking equations, the abrupt reduction in the kinetic energy associated with impact, and sliding motion of block. In this study, two type of rocking vibration system are considered. One is the undamped rocking vibration system, disregarding energy dissipation at impact and the other is the damped rocking system, including energy dissipation and sliding motion. The response analysis using non-dimensional rocking equation is carried out for the change of excitation parameters and friction coefficient. The chaos responses were discovered in the wide response region, particularly, for the case of high excitation amplitude and their chaos characteristics were examined by the time history, Poincare map, power spectra and Lyapunov Exponent of rocking responses. The complex behavior of chaos response, in the phase space, were illustrated by Poincare map. The bifurcation diagram and Poincare map were shown to be effective in order to understand chaos of rocking system.

질소이온주입에 따른 생체안전성 티타늄 임플란트의 마모특성

변응선,최종운,손선희,정용수 한국산업안전학회 1999 한국안전학회지 Vol.14 No.4

In this study, plasma source ion implantation was used to improve the wear properties of biocompatible titanium implant. In order to observe the effect of ion energy and dose on wear property of titanium implant, pin-on-disk type wear tests in Hank's solution were carried out. The friction coefficient of ion implanted specimens were increased from 0.47 to 0.65 under high energy and ion dose conditions. As increasing ion energy and ion dose, the amount of wear was reduced.