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Indentation Damage of Porous Alumina Ceramics
하장훈,김도경,Chul-Seung Lee,Jong Ho Kim 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.1
The Hertzian indentation contact damage behavior of porous alumina with controlled pore shape was investigated by experiments. Porous alumina ceramics containing well-defined pore shape, size and distribution were prepared by incorporation of fugitive spherical starch. Porous alumina with isolated pore structure was prepared with porosity range up to 30%. The indentation stress-strain curves of porous alumina were constructed. Elastic modulus and yield stress can be obtained from the stress-strain relationship. Impulse excitation method for the measurement of elastic modulus was also conducted as well as Hertzian indentation and was confirmed as a useful tool to evaluate the elasticity of highly porous ceramics. Elastic modulus of the inter-connected pore structure is more sensitive to porosity than that of the isolated pore structure. When the specimen had isolated pore structure, higher yield point was obtained than it had inter-connected pore structure. This study proposed that the elastic modulus of porous ceramics is strongly related to not only porosity, but also the structure of pore.
경사 기공 구조를 가지는 규조토의 제조에 원심 분리 성형 공정 변수들이 미치는 영향
하장훈,오은지,송인혁,Ha, Jang-Hoon,Oh, Eun-Ji,Ahmad, Rizwan,Song, In-Hyuck 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.4
The purpose of our study was to develop the fabrication method of porous diatomite ceramics with a porosity gradient by centrifugal molding. The processing variables of centrifugal molding were derived from Stoke's law of sedimentation, which were the radius of the particles, the acceleration due to centrifugal molding and the dynamic viscosity of the slurry. And these could be controlled by ball-milling conditions, centrifugal conditions, and the addition of methyl cellulose, respectively. The effects of processing conditions on the gradient pore structure of diatomite were investigated by particle size analysis, scanning electron microscope, and mercury porosimeter.
장훈,배웅진,김수진,육성모,한동석,하유신,황성연,윤신희,Zhiping Wang,김세웅 대한남성과학회 2013 The World Journal of Men's Health Vol.31 No.3
Purpose: To evaluate the anti-apoptotic effect of the antioxidant reaction of anthocyanin on the prostate in an andropause animal model.Materials and Methods: Sprague-Dawley rats were divided into three groups (n=12 in each): control (Group I), andropause (Group II), andropause treated with anthocyanin (Group III). For induction of andropause, Group II and III underwent bilateral orchiectomy. Group III was treated with daily oral anthocyanin (160 mg/kg) for 8 weeks. After 8 weeks, the rats were sacrificed and their blood and prostates were examined pathohistologically and evaluated for oxidative stress and apoptosis. Oxidative stress was assessed by the activity of superoxide dismutase (SOD) and apoptosis in the prostate was identified by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling assay.Results: Group II showed markedly increased activity of SOD in serum over that observed in Group I, whereas the rats in Group III showed reduced oxidative stress compared to Group II. Despite no significant differences in prostate weight between Group II and III (p=0.078), the apoptotic index was significantly greater in Group II than Group I, and was significantly lesser in Group III than Group II.Conclusions: We suggest that the oxidative stress caused by low testosterone may be another inducer of apoptosis, and this apoptosis may partly contribute to the overall apoptosis of the prostate in the andropause animal model. Therefore, anthocyanin supplementation may contribute to preventing excessively rapid cell death by apoptosis in the prostate in an animal model of andropause.
전립선비대증 유발 백서에서 검은 콩에서 추출한 안토시아닌이 미치는 영향
장훈,하유신,김수진,윤병일,한동석,육승모,황태곤,김세웅 대한남성과학회 2010 The World Journal of Men's Health Vol.28 No.2
Purpose: Anthocyanin is known as a water soluble natural pigment and potent antioxidant. We extracted anthocyanin mediating antioxidant reaction from black soybeans, administered the extract to rats induced prostatic hyperplasia, and evaluate the effect of anthocyanin. Materials and Methods: Twenty four male rats were divided into 4 experimental groups: the control, BPH-induced, BPHinduced, and oral anthocyanin (40 mg/kg, 80 mg/kg)-administered groups. For exclusion of intrinsic testosterone influence, a bilateral orchiectomy was done on all except the control group. An experimental prostate hyperplasia was induced by the subcutaneous administration of 3 mg/kg testosterone propionate for 4 weeks to all except the control group. Anthocyanin administration was done in the last 4 weeks in the anthocyanin-administered groups. After 8 weeks, the prostates were removed and analyzed for their prostatic weight and histological examination. Then TUNEL staining was done on each group’s specimens, and they were analyzed for their apoptotic body counts. Results: The mean prostate weight was found to be 674.17±28.24 mg, 1,098.33±131.31 mg, 323.00±22.41 mg, and 324.00±26.80 mg in the control, BPH-induced, and oral anthocyanin-administered (40 mg/kg, 80 mg/kg) groups, respectively. The BPH-induced group showed statistically significant increases in their prostate weights compared with the control group (p<0.05) and the anthocyanin administered groups showed statistically significant decreases compared to the control and BPH-induced groups (p<0.05). Histologically injected testosterone led to prostatic hyperplasia, but anthocyanin-administered groups experienced this change to a lesser extent. Apoptotic body counts in 5×400/HPF were found to be 3.67±0.86, 1±0.94, 15.67±2.36, and 28.33±1.71 in each group. The anthocyanin-administered groups showed statistically significant increases in apoptotic body counts compared with the control and BPH induced groups (p<0.05). Conclusions: In a prostatic hyperplasia-induced rat model, administration of anthocyanin showed the reduction of prostate weight and the increase of apoptosis. We thought that such results were caused by antioxidant reactions of anthocyanin, and administration of the anthocyanin may be effective in benign prostatic hyperplasia, which is the representative geriatric disease of the urological system.
정계정맥류 유발 백서에서 고환조직의 변화와 정자 형성에 대한 안토시아닌의 효과
장훈,김세웅,김수진,육승모,한동석,하유신,홍성후,이지열,황태곤,황성연 대한남성과학회 2011 The World Journal of Men's Health Vol.29 No.1
Purpose: Varicocele is known as a main cause of primary male infertility and it supposed to be associated with oxidative stress. Anthocyanin is known as a natural plant pigment and novel antioxidant. This study was designed to investigate the effects of anthocyanin on a rat model of varicocele. Materials and Methods: Twenty four male rats, induced varicocele by partial obstruction of left renal vein, were divided into four experimental groups: the group induced varicocele for four weeks without anthocyanin, the group received anthocyanin (80 mg/kg) right after varicocele induction, group induced varicocele for eight weeks without anthocyanin, and the group received anthocyanin (80 mg/kg) after four weeks observation following varicocele induction. After anthocyanin treatment, testes from the rats in all groups were removed, weighed, and subjected to histological examination. Apoptosis in the testes was measured by the TUNEL assay. And the oxidative stress was evaluated by measurement of 8-hydroxy-2'-deoxyguanosine (8-OHdG). Results: Induction of varicocele led to decreasing left testis weight, decreasing spermatogenic cell density significantly (p<0.05). Also it led to increasing apoptotic body counts and increasing concentration of 8-OHdG significantly (p<0.05). However administration of anthocyanin right after varicocele induction prevent this change meaningfully (p<0.05). In group received anthocyanin after four weeks observation following varicocele induction, interestingly, there was no significant difference in testis weight, spermatogenic cell density, apoptotic body count and concentration of 8-OHdG compared to group induced varicocele for eight weeks without anthocyanin administration. Conclusions: These results suggest that anthocyanin is effective in decreasing the oxidative stress of testis in rat induced varicocele and may be effective in making a healthy sperm in patient of varicocele in early stage. However in patient under way in advanced stage, it is supposed that the anthocyanin cannot help having a protective effect from oxidative stress narrowly unless the condition of oxidative stress by varicocele is corrected. Further studies are needed to better understand the mechanisms and actions of anthocyanin and varicocele, and these studies may lead to the clinical application of anthocyanin in preventing male infertility by varicocele.
실리카 분말이 코팅된 수처리용 규조토계 세라믹 필터의 특성평가
배병서,하장훈,송인혁,한유동,Bae, Byung-Seo,Ha, Jang-Hoon,Song, In-Hyuck,Hahn, Yoo-Dong 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.1
In this study, diatomite based materials were investigated as a support filter for silica particle coating. The silica sol for coating was synthesized by a st$\ddot{o}$ber process. The diatomite support was dry-pressed at 10 MPa and sintered at $1200^{\circ}C$ for 1 hour. The coating sol was prepared as a mixture of EtOH and silica sol. The diatomite support was coated by a dip-coating process. Silica coated diatomite filter was sintered at $1000{\sim}1200^{\circ}C$ for 1 hour. The largest pore size was decreased with increasing concentration ratio of coating sol. The gas and water permeability of silica coated diatomite decreased with increasing of concentration ratio of the coating sol.