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유효응력 (有效應力) 과 전위 구조로 해석한 70Cu-30Ni 합금의 Creep 변형 기구
홍준화,남수우 대한금속재료학회(대한금속학회) 1980 대한금속·재료학회지 Vol.18 No.5
온도범위 0.44∼0.64T_m과 응력범위 15∼336㎫의 실험조건하에서 70Cu-30Ni 고용체 합금의 creep 변형기구를 규명하는 연구로서 변형기구의 정확한 원인을 확인하기 위하여 유효응력을 측정하여 다음과 같은 온도에 무관한 creep 변형 속도방정식을 얻었다. ε˙_s=1.84×10^(-4)(σ^*/σ_(0.05))^(2.6) 여기서 σ^*와 σ_(0.05)는 각각 유효응력과 0.05연신하의 항복응력을 뜻한다. 실험을 통하여 얻어진 자료를 분석한 결과 상기의 합금이 실험조건하에서의 변형기구는 jog을 포함하는 나사전위의 jog 부분의 비보존적 운동에 의해서 지배받는 것으로 결론 지어진다. The steady state creep deformation mechanism of 70Cu-30Ni solid solution alloy was investigated for the temperature range of 0.44∼0.64T_m. For the better understanding of the mechanism the effective stress was measured and the creep rate was expressed with the effective stress as ε˙_s=1.84×10^(-4)(σ^*/σ_(0.05))^(2.6) where σ^* and σ_(0.05) are the effective stress and 0.05 strain offset proof stress, respectively. The observed experimental results indicate that the creep deformation mechanism of the given alloy under the stress range of 15∼336㎫ is controlled by the non-conservative motion of the jogged screw dislocations.
홍준화,홍석창 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
Quinazolinones are a significant class of annulated six-membered N-heterocycles. They are key structure motifs for a synthetic pharmaceutical, because of their wide range of biological properties. Due to above reasons, numerous synthetic methods of quinazolinones have been developed, however, most of cases required the specific functional group on the substrates. These showed less atom-efficiency compared with the attractive cross-dehydrogenative coupling (CDC) reactions, which can use unfunctionalized simple substrates. Herein, we describe a direct synthesis of a quinazolinone via CDC between methyl arenes and anthranilamides. The C-H functionalization of benzylic sp3 carbon is achieved in the presence of iron catalyst and oxidant, the following dual amination of sp3 carbon complete the annulation process. This protocol tolerate various kind of functional group, which provide 27 samples of 2-aryl quinazolinone using various methyl arenes.
홍준화,이철주,최진욱,소동문 대한흉부외과학회 2006 Journal of Chest Surgery (J Chest Surg) Vol.39 No.5
흉부 둔상으로 인한 무명동맥 손상은 드문 것으로 보고되고 있다. 본원에서는 교통사고로 인한 흉부 둔상으로 발생한 40세 남자 환자의 무명동맥 박리 및 가성 동맥류를 흉부 전산화 단층촬영으로 진단하여 상행대동맥과 무명동맥 간에 인조혈관 우회로 조성술로 성공적으로 치료하였다. 환자는 술 후 별다른 합병증 없이 1주일만에 퇴원할 수 있었으며 현재 외래 추적 중이다.
Type 316L 스테인리스가의 입계 석출 및 예민화에 미치는 질소의 영향
홍준화,류우석,오용준 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.8
Nitrogen effect on sensitization behavior of type 316L stainless steel was investigated in view of thermal precipitation. The investigated alloys had a variation in carbon and nitrogen contents. The sensitization resistance was improved with decreasing of carbon content and increasing of nitrogen content. From a microstructural observation on the sensitized alloys, it was found that the addition of nitrogen up to 0.15% increased sensitization resistance through suppressing the initiation and growth of M_(23)C_6 type carbide. M_6C type carbide was only formed at the alloy with medium nitrogen content. Besides carbides, Mo-rich precipitates such as intermetallic η and χ phases, and five-fold symmetry phase were observed at the grain boundary. These phases were more popular in the medium nitrogen alloy than in low nitrogen alloy at the same aging condition. From a TEM-EDS(energy despersive spectroscope) analysis, it was found that these Mo-rich phases had not a significant deterimental effect on the sensitization resistance.
GDF15 Is a Novel Biomarker for Impaired Fasting Glucose
홍준화,정효균,박혜윤,정경혜,이주희,정진규,김군순,김현진,구본정,송민호 대한당뇨병학회 2014 Diabetes and Metabolism Journal Vol.38 No.6
Background: Growth differentiation factor-15 (GDF15) is a protein that belongs to the transforming growth factor β superfamily. An elevated serum level of GDF15 was found to be associated with type 2 diabetes mellitus (T2DM). T2DM is an inflammatory disease that progresses from normal glucose tolerance (NGT) to impaired fasting glucose (IFG). Hence, we aimed to validate the relationship between GDF15 and IFG. Methods: The participants were divided into the following three groups: NGT (n=137), IFG (n=29), and T2DM (n=75). The controls and T2DM outpatients visited the hospital for routine health check-ups. We used fasting blood glucose to detect IFG in nondiabetic patients. We checked the body mass index (BMI), C-reactive protein level, metabolic parameters, and fasting serum GDF15 level. Results: Age, BMI, triglyceride, insulin, glucose, homeostatic model assessment-insulin resistance (HOMA-IR), and GDF15 levels were elevated in the IFG and T2DM groups compared to the NGT group. In the correlation analysis between metabolic parameters and GDF15, age and HOMA-IR had a significant positive correlation with GDF15 levels. GDF15 significantly discriminated between IFG and NGT, independent of age, BMI, and HOMA-IR. The serum levels of GDF15 were more elevated in men than in women. As a biomarker for IFG based on the receiver operating characteristic curve analysis, the cutoff value of GDF15 was 510 pg/mL in males and 400 pg/mL in females. Conclusion: GDF15 had a positive correlation with IR independent of age and BMI, and the serum level of GDF15 was increased in the IFG and T2DM groups. GDF15 may be a novel biomarker for detecting IFG in nondiabetic patients.