• 한국정밀공학회지
• /
• 제12권1호
• /
• pp.15-21
• /
• 1995

Automatic monitoring of cutting process is one of the most important technologies for increasing the stability and the reliability of unmanned manufacturing system. In this study, the methods which use laser displacement signals and banded energy method are proposed to monitor chatter vibration in the turning process. From this method, the monitoring system of the chatter vibration was developed and investigated its practical possibility. As a result, it is shown by experiments that the chatter vibration can be detected accurately, and it can be widely used in most turning processes.

• Nuclear Engineering and Technology
• /
• 제48권1호
• /
• pp.33-42
• /
• 2016

Spacer grids play an important role in maintaining the proper form of the fuel assembly structure and ensuring the safety of reactor core design. This study applies the Monte Carlo method to the analysis of the neutronics effects of spacer grids in a typical pressurized water reactor (PWR). The core problem used to analyze the neutronics effects of spacer grids is a modified version of Korea Advanced Institute of Science and Technology benchmark problem 1B, based on an Advanced Power Reactor 1400 (APR1400) core model. The spacer grids are modeled and added to this test problem in various ways. Then, by running MCNP5 for all cases of spacer grid modeling, some important numerical results, such as the effective multiplication factor, the spatial distributions of neutron flux, and its energy spectrum are obtained. The numerical results of each case of spacer grid modeling are analyzed and compared to assess which type has more advantages in accuracy of numerical results and effectiveness in terms of geometry building. The conclusion is that the most realistic modeling for Monte Carlo calculation is the "volume-preserving" streamlined heterogeneous spacer grids, but the "banded" dissolution spacer grids modeling is a more practical yet accurate model for routine (deterministic) analysis.

• Journal of Radiation Protection and Research
• /
• 제26권3호
• /
• pp.155-159
• /
• 2001

Beta radiation is measured for an environmental monitoring purpose or for an internal radiation exposure monitoring of nuclear power plant's worker. In korea, strontium 89 and strontium 90 is measured for an environmental monitoring purpose. Also tritium and carbon 14 contained in urine is measured for an internal radiation exposure monitoring of nuclear power plant's worker. Because above isotopes emits low energy beta radiations having a wide range of energy, very complicated isotope separation preprocess is needed. In this study, two mixed beta emitting isotopes are measured simultaneously using a liquid scintillation counter(LSC) and analyzed by using a developed statistical method. Banded least square method is used to analyze the mixed spectrum, and the goodness-of-fitness test is proposed. Test results show that the developed procedure can be very useful for analyzing a mixed beta emitting isotopes.

• Nuclear Engineering and Technology
• /
• 제51권1호
• /
• pp.228-237
• /
• 2019

The crack growth responses of as-received and as-welded Alloy 600/182 and Alloy 690/152 welds to constant loading were measured by a direct current potential drop method using compact tension specimens in primary water at $325^{\circ}C$ simulating the normal operating conditions of a nuclear power plant. The as-received Alloy 600 showed crack growth rates (CGRs) between $9.6{\times}10^{-9}mm/s$ and $3.8{\times}10^{-8}mm/s$, and the as-welded Alloy 182 had CGRs between $7.9{\times}10^{-8}mm/s$ and $7.5{\times}10^{-7}mm/s$ within the range of the applied loadings. These results indicate that Alloys 600 and 182 are susceptible to cracking. The average CGR of the as-welded Alloy 152 was found to be $2.8{\times}10^{-9}mm/s$. Therefore, Alloy 152 was proven to be highly resistant to cracking. The as-received Alloy 690 showed no crack growth even with an inhomogeneous banded microstructure. The cracking mode of Alloys 600 and 182 was an intergranular cracking; however, Alloy 152 was revealed to have a mixed (intergranular + transgranular) cracking mode. It appears that the Cr concentration and the microstructural features significantly affect the cracking resistance and the cracking behavior of Ni-base alloys in PWR primary water.

• Nuclear Engineering and Technology
• /
• 제15권1호
• /
• pp.23-32
• /
• 1983

한반도에 분포하는 암석으로서 최고기의 암석으로 알려지고 있는 경기편마암 복합체중, 양평지역에 분포하는 우백질 편마암과 화강편마암류 및 시흥 지역에 분포하는 호상-안구상 편마암류를 대상으로 Rb-Sr법에 의한 암석 연대측정 연구를 실시하였다. 그 결과, 우백질 편마암과 호상-안구상 편마암류의 생성연대는 22억 내지 23억년으로 밝혀졌고, 화강편마암류의 관입시기는 14억년으로 측정되었다. 양평지역에서 채취한 시료중, 심하게 변질된 편마암류의 연대는 5억년이었다. 이 연대는 아마도 열수작용을 동반한 Caledonian조산운동의 시기와 밀접한 관계가 있을 것이다. 기타 여러지역에서 채취한 편마암류들에서 공통적으로 8-9억년의 년대가 측정된 것은 경기편마암 복합체가 받은 선캠브리아기의 화성 활동 혹은 광역변성 작용의 시기일 것으로 생각된다. 편마암류에서 분리한 흑운모는 시료 채취 지역에 다라 1억2천만년에서 2억7천만년으로 측정되었으며 이 연대는 본 지역에도 중생대 내지는 고생대 화성활동이 있었음을 뜻한다.

• 융합신호처리학회논문지
• /
• 제4권1호
• /
• pp.1-8
• /
• 2003

현재 사회전반에 걸쳐 급격히 증가하고 있는 멀티미디어 정보를 효율적으로 관리, 활용할 수 있는 방법이 다양하게 연구되고 있다. 본 논문에서는 정지영상 검색을 위해 사용자가 질의(query)를 요구하면 질의 물체를 배경으로부터 분할한 후 유사물체를 영상 데이터베이스 내에서 검색할 수 있는 내용기반 영상검색 시스템을 구현하였다. 질의영상이 들어오면 우선 메디안 필터링 처리를 하여 잡음 제거한 후 캐니 에지 탐지법으로 물체의 에지를 구한다. 그리고 볼록 다각형 기법을 이용하여 배경으로부터 질의물체를 분할한다. 분할된 영상으로부터 컬러 히스토그램을 구한 후 데이터 베이스내의 영상과 히스토그램 인터섹션을 하여 유사치를 구한다 또한 공간적 그레이 분포와 질감특성을 추출하기 위해 분할된 영상을 그레이 영상으로도 변환시켜 웨블릿 변환한 후 밴디드 오토코릴로그램과 에너지를 구해 유사치를 구한다. 이렇게 구한 유사치을 더해 최종 유사영상을 검색하는데 물체 분할기법을 사용함으로써 배경에 강인할 뿐 아니라 보다 정확한 물체 검색이 가능하였다.