• 자원환경지질
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• 제52권2호
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• pp.199-212
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• 2019

머신러닝 기법을 활용한 분석에서 훈련 데이터의 샘플링 전략은 예측 정확도 뿐 만 아니라 일반화 능력에도 많은 영향을 미친다. 특히, 산사태 취약성 분석의 경우, 산사태 발생부에 대한 정보에 비해 산사태 미발생부에 대한 정보가 과도하게 많은 데이터 불균형 현상이 발생하며, 이에 따라 분석 모델의 훈련 데이터 설계 시 데이터 샘플링 과정이 필수적이다. 그러나 기존의 연구들은 대부분 산사태 미발생부 선택 시 발생부 데이터와 1:1의 비율을 갖도록 무작위로 선택하는 방법을 적용하였을 뿐, 특정한 선택 기준에 따라 분석을 수행하지 않았다. 따라서 본 연구에서는 훈련 데이터의 샘플링 전략이 모델의 예측 성능에 미치는 결과를 확인하기 위하여 산사태 발생부와 미발생부의 샘플링 전략기준에 따라 서로 다른 6개의 시나리오를 만들어 Random Forest 모델의 훈련에 사용하였다. 또한 Random Forest의 결과 중 하나인 변수 중요도를 각 산사태 유발인자들에 가중치로 곱하여 줌으로써 산사태 취약지수 값을 산정하였으며, 취약지수 값을 이용해 산사태 취약성도를 제작하고 각 결과 지도의 정확도를 비교 분석하였다. 분석 결과, 훈련데이터의 샘플링 방법에 상관없이 두 지역의 산사태 취약성 분석 결과는 모두 70~80%의 정확도를 보였다. 이를 통해 Random Forest 기법의 산사태 취약성 분석기법으로서의 적용 가능성을 확인하였으며, Random Forest 모델이 제공하는 입력변수의 중요도를 산사태 유발인자 가중치로 활용할 수 있음을 확인하였다. 또한 훈련 시나리오 간의 정확도를 비교한 결과, 특정한 기준에 의해 훈련 데이터를 설계하는 것이 기존의 랜덤 선택 방법보다 높은 예측 정확도를 기대할 수 있음을 확인하였다.

• Progress in Superconductivity
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• 제11권1호
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• pp.67-71
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• 2009

The effect of Cu substitution on the structural and superconducting properties of the $(Ru_{1-x}Cu_x)Sr_2(Eu_{1.34{\cdot}}Ce_{0.66})Cu_2O_z$ system with x = 0, 0.25 and 0.5 prepared under ambient pressure have been investigated. The X-ray diffraction patterns indicated that the Ru ions are replaced by the Cu ions. It is found that the Cu substitution for Ru significantly reduces the ferromagnetic component of field-cooled magnetic susceptibility, but results in a small change in diamagnetic onset transition temperature of zero-field-cooled magnetic susceptibility. In contrast to the Ru $Sr_2(Eu_{1.34{\cdot}}Ce_{0.66})Cu_2O_z$, bulk Meissner effect is observed in the field-cooled magnetization measurements of the Cu doped samples. The experimental results are discussed in connection with the spontaneous vortex phase interpretation.

• 지역사회간호학회지
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• 제33권1호
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• pp.53-62
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• 2022

Purpose: This study explored the effects of the elderly group's digital literacy and health empowerment on communication with doctors, considering moderating effect of health beliefs about chronic diseases. Methods: A one-on-one interview survey was conducted with 500 older adults in South Korea. The main variables were digital literacy, health empowerment, communication with doctors, and health belief of chronic diseases. Results: The interaction effect between health empowerment and susceptibility, and health empowerment and perceived barrier were significant. Conclusion: Communication with doctors greatly increased when the elders had high levels of health empowerment and low levels of susceptibility. Also, communication with doctors greatly increased when the elders had high levels of health empowerment and low levels of perceived barriers.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1996년도 특별강연 및 춘계학술발표 개요집
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• pp.173-175
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• 1996

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1994년도 특별강연 및 춘계학술발표 개요집
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• pp.54-56
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• 1994

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1995년도 춘계연구발표회 논문개요집
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• pp.46-47
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• 1995

• Corrosion Science and Technology
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• 제2권4호
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• pp.178-182
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• 2003

Slow Strain Rate Tests (SSRT) were carried out to investigate the effect of environmental factors on the Stress Corrosion Cracking (SCC) susceptibility of 3.5NiCrMoV steels used in discs for Low-Pressure (LP) steam turbines in electric power generating plants. The influences of dissolved oxygen on the stress corrosion cracking of turbine steel were studied, For this purpose, specimens were strained at variously oxygenated conditions at $150^{\circ}C$ in pure water. When the specimen was strained with $1{\times}10^{-7}s^{-1}$ at $150^{\circ}C$ in pure water, increasing concentration of dissolved oxygen decreased the elongation and the UTS. The corrosion potential and the corrosion rare increased as the amounts of dissolved oxygen increased. The increase of the SCC susceptibility of the turbine steel in a highly dissolved oxygen environment is due to the non protectiveness of the oxide layer on the turbine steel surface and the increase of the corrosion current. These results clearly indicate that oxygen concentration increases Stress Corrosion Cracking susceptibility in turbine steel at $150^{\circ}C$.

• Asian Pacific Journal of Cancer Prevention
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• 제13권10호
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• pp.5201-5205
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• 2012

Background: To evaluate the role of the X-ray repair cross complementing group 3 (XRCC3) T241M polymorphism in head and neck cancer susceptibility. Materials and Methods: We performed a meta-analysis of all available studies, which included 3,191 cases and 5,090 controls. Results: Overall, a significant risk effect of the T241M polymorphism was not found under homologous contrast (MM vs TT: OR=1.293, 95% CI=0.926-1.805; TM vs TT: OR=1.148 95% CI=0.930-1.418) and recessive models (MM vs TT+TM): OR=1.170, 95% CI=0.905-1.512, but a significantly increased risk was observed under a dominant model (MM+TM vs TT): OR=1.243, 95% CI=1.001-1.544. In stratified analyses, there were no significant associations for Asians or Caucasians. Conclusion: Our meta-analysis suggested the XRCC3 241M allele (MM+TM) might act as a head and neck cancer risk factor among all subjects, and the effect of T241M polymorphism on head and neck susceptibility should be studied with a larger, stratified population.

• 대한화학회지
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• 제29권6호
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• pp.646-650
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• 1985

RNase A에 對한 RNA의 加水分解反應性은 spermine에 의하여 抑制되었다. Spermine의 濃度가 增加함에 따라 RNase의 活性度는 점점 減少하다가 plateau에 到達되었다. 同一한 條件에서 spermine의 濃度가 增加함에 따라 RNA의 粘性度는 점점 增加되어 RNase의 活性度에서의 spermine의 依存性과 같이 plateau에 이르게 되었다. RNase A에 對한 RNA의 加水分解反應性에 미치는 spermine의 抑制效果는 denatured(變性) DNA에 의하여 救濟되나 native(本性) DNA에 의하여서는 無關하였다. 이들 實驗結果는 spermine에 의하여 RNA의 分子間 aggregation이 일어나며 그로 因하여 RNA의 RNase A에 對한 加水分解反應性이 抑制될 수 있음을 보여준다.

• 열처리공학회지
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• 제35권1호
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• pp.8-19
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• 2022

The metallic implant materials are widely used in biomedical industries due to their specific mechanical strenth, corrosion registance, and superior biocompatability. These metallic materials, however, suffer from the stress-shielding effect and the generation of artifacts in the magnetic resonance imaging exam. In the present study, we develope a Zr-based alloys for the biomedical implant materials with low elastic modulus and low magnetic susceptibility. The Zr-7Si-xSn alloys were fabricated by an arc melting process. The elastic modulus was 24~31 GPa of the zirconium-based alloy. The average magnetic susceptibility value of the Zr-7Si-xSn alloy was 1.25 × 10^-8cm³g^-1. The average I_corr value of the Zr-7Si-xSn alloy was 0.2 ㎂/cm². The Sn added zirconium alloy, Zr-7Si-xSn, is very interested and attractive as a biomaterial that reduces the stress-shielding effect caused by the difference of elastic modulus between human bone and metallic implant.