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Mechanical Alloying에 의한 Ti_xCu_90-xAl_10(x=50,60)의 비정질화 및 열적성질
강종욱,김현구,김혜숙,이상열 조선대학교 기초과학연구소 1996 自然科學硏究 Vol.19 No.1
Amorphous powders of the Ti_xCu_(90-x)Al_10(x=50,60) system were synthesized by mechanical alloying method under an argon atmosphere. The amorphization process of the Ti_xCu_(90-x)Al_10(x=50,60) powders after milling by MA were studied by XRD, SEM and DSC experiments. We found that the best milling conditions of the Ti_xCu_(90-x)Al_10(x=50,60) powders were a ball-to powder weight ratio of 15 : 1 and a revolving velocity of 250rev min^-1 in this experiment. XRD patterns of the Ti_xCu_(90-x)Al_10(x=50,60) powders obtained by MA showed broad peaks as the increasing of milling times of the powders. So we confirmed the amorphization of the powders. The position of peak intensity 2θ(max.) of amorphous powders decreased nearly linearly with the increase of titanium concentration. Average particle size of the Ti_xCu_(90-x)Al_10(x=50,60) powders were 20∼26㎛ from SEM micrograph. In the DSC experiment, crystallization temperature and peak temperature were observed to increase for the Ti_xCu_(90-x)Al_10(x=50,60) powders with increased titanium concentration. The activation energy of the Ti_50Cu_40Al_10 and Ti_60Cu_30Al_10 powders were 260.57 and 253.10KJ/mole, respectively. the crystallization fraction of the Ti_50Cu_40Al_10 and Ti_60Cu_30Al_10 powders were found to be 3.02% at 458℃ and 1.32% at 477.2℃.
( Hyun Wuk Kang ),( Dong Chul Lee ),( Yu Il Kim ),( Sunmin Kim ),( Hong Jun Shin ),( Chul Kyu Park ),( Hee Jung Ban ),( Yong Soo Kwon ),( In Jae Oh ),( Kyu Sik Kim ),( Young Chul Kim ),( Sung Chul Lim 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1
Background: Gamma-glutamyltransferase (GGT) is an enzyme mainly produced from the cells of the hepatobiliary tract. And, It has been introduced as a biomarker for oxidative stress by smoking as well as alcohol consumption. This study was performed to evaluate the association between smoking and serum GGT concentration Methods: The effect of cigarette smoking on serum activities of the enzyme, GGT was investigated using the data of the 5th Korea National Health and Nutrition Examination Survey (5th KNHANES, 2010 to 2012); a cross-sectional survey in the general population of Korea. Results: We analyzed 11,670 subjects (age> 19 years) who had the data about smoking status and serum GGT levels. Subjects comprised 4,597 subjects who are cigarette smokers and 7,073 who do not smoke, which serves as control. The mean ± standard deviation (S.D) of serum GGT levels in cigarette smokers and non-smokers were 48.74± 69.35 U/L and 23.18± 24.03 U/L respectively, showing a significant increase in serum level of GGT (P<0.001) when compared with controls. GGT levels showed a significant positive correlation with amount of smoking (r=0.249, P<0.001). Cigarette smoking produced a significant increase in GGT activity irrespective of low to moderate alcohol consumption Conclusions: The levels of serum GGT was significantly associated with the status and amount of smoking. Smoking should be taken into account when assessing the signifi-cance of GGT activities.
( Hyun Wuk Kang ),( Dong Chul Lee ),( Yu Il Kim ),( Sun Min Kim ),( Hong Jun Shin ),( Chul Kyu Park ),( Hee Jung Ban ),( Yong Soo Kwon ),( In Jae Oh ),( Kyu Sik Kim ),( Young Chul Kim ),( Sung Chul Li 대한결핵 및 호흡기학회 2014 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.118 No.-
Background: Gamma-glutamyltransferase (GGT) is an enzyme mainly produced from the cells of the hepatobiliary tract. And, It has been introduced as a biomarker for oxidative stress by smoking as well as alcohol consumption. This study was performed to evaluate the association between smoking and serum GGT concentration Methods: The effect of cigarette smoking on serum activities of the enzyme, GGT was investigated using the data of the 5th Korea National Health and Nutrition Examination Survey (5th KNHANES, 2010 to 2012); a cross-sectional survey in the general population of Korea. Results: We analyzed 11,670 subjects (age> 19 years) who had the data about smoking status and serum GGT levels. Subjects comprised 4,597 subjects who are cigarette smokers and 7,073 who do not smoke, which serves as control. The mean ± standard deviation (S.D) of serum GGT levels in cigarette smokers and non-smokers were 48.74± 69.35 U/L and 23.18± 24.03 U/L respectively, showing a significant increase in serum level of GGT (P<0.001) when compared with controls. GGT levels showed a significant positive correlation with amount of smoking (r=0.249, P<0.001). Cigarette smoking produced a significant increase in GGT activity irrespective of low to moderate alcohol consumption Conclusions: The levels of serum GGT was significantly associated with the status and amount of smoking. Smoking should be taken into account when assessing the significance of GGT activities.
Gyu Hyun Kang,Dong Wuk Son,Jun Seok Lee,Su Hun Lee,Sung Hyun Bae,Sang Weon Lee,Geun Sung Song 대한신경손상학회 2022 Korean Journal of Neurotrauma Vol.18 No.2
Objective: This study aimed to compare the radiological and clinical outcomes of oblique lumbar interbody fusion (OLIF) and posterior lumbar interbody fusion (PLIF) surgeries and to confirm the effects of additional partial laminectomy on the surgical outcomes of OLIF. Methods: This retrospective study included 130 patients who underwent OLIF or PLIF for single-level fusion. Among them, 42 patients underwent PLIF and open pedicle screw fixation and 88 underwent OLIF and percutaneous pedicle screw fixation. In the OLIF group, 42 patients received additional neural decompression through partial laminectomy and discectomy (direct OLIF), whereas the remaining 46 patients did not (indirect OLIF). To measure the neurological deficits, the clinical outcomes were evaluated using a visual analog scale for back and leg pain and the Oswestry Disability Index. Radiologic outcomes were evaluated based on the disc and foraminal heights as well as the segmental lordotic and lumbar lordotic angles. Results: The improvement in the clinical outcomes did not differ significantly among the 3 groups. Radiologically, the 2 OLIF groups showed statistically significant improvements in the disc and foraminal heights when compared with the PLIF group. The PLIF group showed a significant decrease in the disc height and segmental lordotic angle when compared with the OLIF group in the postoperative 1-year period. Conclusion: Both OLIF and PLIF showed similar clinical outcomes in the single-level lumbar fusion. However, OLIF grafts showed an advantage over PLIF with respect to the radiographic outcomes and complication rates. Additionally, partial laminectomy did not significantly affect the radiological results.
강대현(Dae Hyun Kang),이범재(Bum Jae Lee),윤창배(Chang Bae Yun),김강욱(Kang Wuk Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Induction hardening has been used to improve torsional strength and characteristics of wear for axle shaft which is a part of automobile to transmit driving torque from differential to wheel. After rapidly heating and cooling process of induction hardening, the shaft has residual stress and material properties change which affect allowable transmit torque. The objective of this study is to predict the distribution of residual stress and estimate the torsional strength of induction hardened axle shafts which has been residual stress using finite element analysis considered thermo mechanical behavior of material and experiments. Results indicate that the torsional strength of axle shaft depends on the surface hardening depth and distribution of residual stress.
강대현(Dae Hyun Kang),이범재(Bum Jae Lee),윤창배(Chang Bae Yun),김강욱(Kang Wuk Kim) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.5
고주파열처리(induction hardening)는 엔진의 구동력을 차동장치에서 바퀴까지 전달해주는 부품인 액슬축(axle shaft)의 비틀림 강도를 증가시키기 위해 적용되는 열처리 방법이다. 고주파 열처리 과정의 급속가열과 급속냉각은 소재에 잔류응력과 물성치를 변화시켜 액슬축의 허용 전달토크를 변화시킨다. 본 연구에서는 고주파 열처리한 액슬축의 잔류응력의 분포와 열처리 깊이에 따른 비틀림 강도 변화를 열물성 및 상변태를 고려한 유한요소 해석을 통해 예측하였으며 이를 시험과 비교하였다. Induction hardening has been used to improve the torsional strength and characteristics of wear for axle shaft that is used to transmit driving torque from the differential to the wheel in automobiles. After the rapid heating and cooling processes of induction hardening are carried out, the shaft has residual stress and material properties change; this affects the allowable transmitted torque. The objective of this study is to predict the distribution of residual stress and estimate the torsional strength of induction-hardened axle shafts with residual stress. In this study, the finite element method is used to study the thermomechanical behavior of the material, and the results are compared with experimental results. The results indicate that the torsional strength of the axle shaft depends on the surface hardening depth and distribution of residual stress.
강현철,박규태,이한욱,최동혁 연세대학교 산업기술연구소 1989 논문집 Vol.21 No.2
In a HANGUL text recognition system, there are certain limits in character recognition due to noises or flaws in the character itself. Therefore, a postprocessing following the recognition is necessary to increase the overall recognition rate. In this paper, a morpheme separation algorithm is proposed by separating HANGUL EOJUL into the two categories according to the combined type. Also, a modified PCA for the HANGUL EOJUL modification is implemented.