Dynamic Young's Modulus and Internal Friction in Polycrystalline Copper

Kang, Chang-Seog,Chang, Si-Young,Hong, Sung-Kil 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.5

An attempt has been made to measure the temperature dependence of dynamic Young's modulus together with the related variation of internal friction in polycrystalline copper. A mechanical spectroscopy study was employed using a standard servo hydraulic fatigue testing machine equipped with a scanning laser extensometer. Dynamic Young's modulus and internal friction were measured over a temperature range of 298 to 873 K at very low frequencies of 0.1, 0.05, and 0.01 Hz. One internal friction peak was observed over the ranges 450 to 700 K, together with marked decreases in the dynamic Young's modulus in the same temperature range. From a quantitative analysis of the experimental data with the relaxation strength, relaxation time, and activation energy, it is concluded that the peak phenomenon is due to grain-boundary sliding relaxation.

Aflatoxin B_1 투여가 急性 肝 病變에 미치는 영향에 對한 病理學的 硏究

장선문,이충식,강대영 충남대학교 의과대학 지역사회의학연구소 1989 충남의대잡지 Vol.16 No.1

In an attempt of elucidate the pathologic and histochemical changes of aflatoxin B_2-induced hepatie lesions, the present study in male Sprague-Dawley rats was undertaken to evalute the relation between pathologic change of the liver and histochemical changes of several enzymes : alkaline phosphatase, acid phosphatase and succinic dehydrogenase at 3. 9. 24. 48. 72, and 144 hours after single administration of aflatoxin B_1 by gastric tube. The aflatoxin B_1 was dissolved in peanut oil(0.5㎎ aflatoxin B_1 to 0.5ml peanut oil). Grouop of male rats received aflatoxin B_1 1㎎ per ㎏ of body weight, respectively. Control animals were given a similar volume of peanut oil alone. The results on morphologic and histochemical changes were as follows: 1. The necrotic change of liver was mainly periportal, and it became most severe at 24 hours and was more prominent in the large dose group than the small dose group. 2. Biliary ductular cell proliferation started to appear within 72 hours and after became regressed later in the small dose group, but it remained approximately 144 hours after exposure in the large dose group. 3. Electron microscopically, all three groups showed irregular nuclear membrane and nucleolar change characterized by segregation of granular and fibrillar elements. All the group showed cytoplasmie changes such as dilatation of rough endoplasmic reticulum with detached ribosome, hyperplasia of smooth endoplasmic reticulum, increased numbers of lipid droplets and mitochondrial alteration. The above change in the large dose group was more severe than those of the small dose group. 4. In the histochemical study of experimental animals, there was a decrease in the intensity of the staining reaction of alkaline phosphatase and succinic dehydrogenase within 24 hours and a progressive decrease in staining intensity was noted at 144 hours. And then the staining intensity of the acid phosphatase was similar to that shown by the control animal. In summary, the data obtained by present experiments indicate aflatoxin B_1 exerts periportal necrosis of hepatic lobules accompanied by bile ductular cell proliferation, and inhibition of protein synthesis, as jedged by elertron microscopic and histochemical changes.

Predictive Risk Assessment Using Cooperation Concept for Collision Avoidance of Side Crash in Autonomous Lane Change Systems

Hyunsoo Lee,Chang Mook Kang,Wonhee Kim,Woo Young Choi,Chung Choo Chung 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10

We present an innovative approach to risk assessment using cooperation concept for collision avoidance of side crash for autonomous lane change system. The cooperation concept is proposed to check an available space in the target lane for lane change in a short period of the future. Before moving to the target lane, the ego vehicle needs to check whether the object vehicle is cooperative or not for the lane change. The object vehicles are indexed as cooperative driver (CD) or non-cooperative driver (NCD) through the conditions based on the relative longitudinal acceleration and the collision free time. If the object vehicle is CD, the ego vehicle moves toward the target lane within the original lane for the preparation of the lane change. The ego vehicle should keep its lateral position within the original lane until the situation for the lane change becomes safe. As soon as the risk assessment becomes safe, the lane change is performed. Therefore, lane change can be started in advance compared to the conventional methods. The proposed method was validated via computational simulation and experimental results.

Effect of Total Hip Arthroplasty on Ipsilateral Lower Limb Alignment and Knee Joint Space Width: Minimum 5-Year Follow-up

Choi Yun Seong,Park Jung-Wee,Kim Tae Woo,Kang Kee Soo,Lee Young-Kyun,Koo Kyung-Hoi,Chang Chong Bum 대한의학회 2023 Journal of Korean medical science Vol.38 No.20

Background: This study aimed to 1) assess the effect of total hip arthroplasty (THA) on coronal limb alignment, namely, the hip–knee–ankle angle (HKA), 2) identify factors that determine changes in the HKA, and 3) determine whether alignment changes influence the knee joint space width. Methods: We retrospectively evaluated 266 limbs of patients who underwent THA. Three types of prostheses with neck shaft angles (NSAs) of 132°, 135°, and 138° were used. Several radiographic parameters were measured in the preoperative and final radiographs (at least 5 years after THA). A paired t-test was used to confirm the effect of THA on HKA change. Multiple regression analysis was performed to identify radiographic parameters related to HKA changes following THA and changes in knee joint space width. Subgroup analyses were performed to reveal the effect of NSA change on the HKA change, and the proportion of total knee arthroplasty usage and changes in radiographic parameters between maintained joint space and narrowed joint space groups were compared. Results: The preoperative mean HKA was 1.4° varus and increased to 2.7° varus after THA. This change was related to changes in the NSA, lateral distal femoral angle, and femoral bowing angle. In particular, in the group with a decrease in NSA of > 5°, the preoperative mean HKA was largely changed from 1.4° varus to 4.6° varus after THA. The prostheses with NSA of 132° and 135° also led to greater varus HKA changes than those with an NSA of 138°. Narrowing of the medial knee joint space was related to changes in the varus direction of the HKA, decrease in NSA, increase in femoral offset. Conclusion: A large reduction in NSA can lead to considerable varus limb alignment after THA, which can have adverse effects on the medial compartment of the ipsilateral knee.

Rat의 복강내에 투여한 5-fluorouracil-polyglycolic acid 제형이 장기에 미치는 영향에 관한 연구

강대영,송규상,최정목,노승무,정경수,오정연,김진향,양준묵,최선웅,이진호,조준식,민병무,김용백,김창식,박근성,김승영,김학용,인현빈 충남대학교 의과대학 지역사회의학연구소 1998 충남의대잡지 Vol.25 No.1

For more effective intraperitoneal chemotherapy, the authers made 5-fluorouracil-polyglycolic acid composite disks(FU-PGA disks) with 5-fluorouracil and polyglycolic acid, a biodegradable polymer. We inserted the FU-PGA disk into the peritoneal cavites of Sprague-Dawley male rats, the control and three experimental groups; one FU-PGA disk insert group(300mg/kg), two FU-PGA disk insert group(600mg/kg), and three FU-PGA disk insert group(900mg/kg). The control group received a similar number of PGA disk inserts. A pharmacokinetic study was performed to measure the 5-fluorouracil concentration in the peritoneal fluid, blood, and tissues(liver, kidney and heart) at 24 hours, 72hours and 168 hours after insertion of the FU-PGA disk. Light and electron microscopic studies were done. The results were as follows: 1) The number of white blood cells and platelets decreased after FU-PGA insertion. The degree was proportional to the duration and amounts inserted. The change in the number of red blood cells varied slightly. 2) Light microscopically, slight changes were noted at 168 hours in the 3 disk insert group (900mg/kg). Mild fatty change and hepatocyte degeneration around the central veins of the liver were noted, with vacuolar degeneration in the proximal convoluted tubules of the kidney. 3) Electron microscopically,the liver showed focal increases of lipid droplets in the hepatocytes, and irregular nuclear membrane with focal nucleolar segregation of the fibrillar and granular elements. Also the double membranous structure of the hepatocytes and Kupffer cells was widened with bleb formation. The kidney showed wide separation of the nuclear double membrane in the proximal convoluted tubular cells and mesangial cells, with vacuolation and myelin figure formation in the mitochondria of the proximal convoluted tubular cells, at 72 hours and 168 hours in the 2 to 3 FU-PGA insert groups. The heart showed focal loss of cristae,vacuolation and myelin figure formation in the mitochondria of the 2 to 3 FU-PGA insert groups. In conclusion, despite the large amont of FU-PGA inserted, the histopathological changes in the liver, kidney and heart were slight, and consonant with the very low amount of 5-fluorouracil concentrations detected in the liver, kidney and heart. The above results suggest that the FU-PGA composite can serve as a new device for releasing drugs in a controlled manner and easily targeted to intraperitoneal organs. This device can improve the efficacy of intraperitoneal chemotherapy for gastric cancer.

Case Report : A Case of Occupational Hypersensitivity Pneumonitis Associated with Trichloroethylene

( Young Jae Kim ),( Eu Dong Hwang ),( Ah Young Leem ),( Beo Deul Kang ),( Soo Yun Chang ),( Ho Keun Kim ),( In Kyu Park ),( Song Yee Kim ),( Eun Young Kim ),( Ji Ye Jung ),( Young Ae Kang ),( Moo Suk 대한결핵 및 호흡기학회 2014 Tuberculosis and Respiratory Diseases Vol.76 No.2

Trichloroethylene (TCE) is a toxic chemical commonly used as a degreasing agent, and it is usually found in a colorless or blue liquid form. TCE has a sweet, chloroform-like odor, and this volatile chlorinated organic chemical can cause toxic hepatitis, neurophysiological disorders, skin disorders, and hypersensitivity syndromes. However, the hypersensitivity pneumonitis (HP) attributed to TCE has rarely been reported. We hereby describe a case of HP associated with TCE in a 29-year-old man who was employed as a lead welder at a computer repair center. He was installing the capacitors on computer chip boards and had been wiped down with TCE. He was admitted to our hospital with complaints of dry coughs, night sweats, and weight losses for the past two months. HP due to TCE exposure was being suspected due to his occupational history, and the results of a video-associated thoracoscopic biopsy confirmed the suspicions. Symptoms have resolved after the steroid pulse therapy and his occupational change. TCE should be taken into consideration as a potential trigger of HP. Early recognition and avoidance of the TCE exposure in the future is important for the treatment of TCE induced HP.

인위적 근피로 유발후 단축성과 신장성 근수축 운동시 근 토크의 변화

강영석,안창영,윤성원,나윤수 서울여자대학교 자연과학연구소 1995 자연과학연구논문집 Vol.6 No.-

The purpose of this study was to investigate the change of the peak torque, average power and total work of muscle function in the fatigue during eccentric(ECC) and concentric contraction (Con). Subjects were seven (7) adults man, who were paticipated in the ECC and CON experiments. Their gastronemus muscle were measured by CYBEX(Lurnax Co.) 6000system. Muscle fatigue was induced by 50 repetitionplantar flexion at 180 /sec load speed. In pre and post test, peak, average power and total work were analized when subjects were tested plantar flexion at 180/sec load speed. the summary of this results is as following : 1. Peak torque in the ECC were significantly higher than that of the CON. 2. Average power and total work of the Eccentric contraction appeared a higher than that of the Concentric contraction significantly. As a results. peak torque, average power and total workin the ECC was significantly higher than that of the CON throughout the experiments. In this fact, Mechanical efficiency in the ECC will expect to be higher than that of the CON.

A Re-evaluation of the Concept of Topic

( Kang¸ Sun Young ),( Chang¸ Kyung Ki ) 현대영미어문학회 1983 현대영미어문학 Vol.1 No.-

Design of a shape memory composite(SMC) using 4D printing technology

Kang, Minkyu,Pyo, Youngjun,Jang, Joon young,Park, Yunchan,Son, Yeon-Ho,Choi, MyungChan,Ha, Joo wan,Chang, Young-Wook,Lee, Caroline Sunyong Elsevier 2018 Sensors and actuators. A Physical Vol.283 No.-

<P><B>Abstract</B></P> <P>A fused deposition modeling (FDM) tool was used to fabricate a shape memory composite (SMC) that combined a shape memory alloy (SMA) with a shape memory polymer (SMP). The SMA caused a shape memory effect due to a phase change between martensite and austenite phases, in turn due to a temperature change. Also, the SMP had a shape memory effect caused by changes in the proportions of hard and soft segments near the glass transition temperature (T<SUB>g</SUB>). Usually, common SMAs and SMPs are not reversible, so these materials do not go back to their original shapes once they are deformed. In this study, we fabricated 4D printing actuator via reversible SMC actuations using 3D printing technology. Nylon 12 was used as the 3D printing material in filament form. Moreover, the volume fraction of SMA to SMP was varied to find the optimum ratio for good operation cycles. A volume fraction of SMA:SMP of 1:5 showed the largest length change, of 8 mm, and the most rapid response time, of 4 s in overall dimension of 140mm×10mm×1mm (length×width×thickness).Thus, the SMC showed promising results for the application of stents and valve controllers that could be manufactured by 3D printing technology.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An 4D printed SMC actuator was fabricated using SMA and SMP with a FDM 3D printer. </LI> <LI> A volume fraction of SMA:SMP of 1:5 showed the largest length change of 8 mm, and the most rapid response time of 4 s. </LI> <LI> The reversible actuator mechanism explains the SMC actuation via each shape memory effect. </LI> <LI> SMC showed potential application for stents and valve controllers via 3D printing technology to achieve customized designs. </LI> </UL> </P>

사염화탄소 투여 흰쥐에서 간섬유화 진행에 따른 Propranolol 의 약동학적 지표들의 변화

이민호,강주섭,강문수,윤병철,이오영,함준수,변재원,윤창옥 대한간학회 2001 Clinical and Molecular Hepatology(대한간학회지) Vol.7 No.2

Background/Aims : This study was designed to determine the effect of hepatic fibrotic severity on pharmacokinetics of propranolol in CC1q - treated rats. Methods - 1 mL/kg of 10% CC14 in olive oil was injected intramuscularly to rats twice weekly for 4, 6, 8 and 10 weeks, respectively (n=6). Control (n=6) was a sham - injected equal dose of olive oil for 10 weeks. After intravenous bolus injection of 2 mg/kg propranolol to rats, the serum propranolol concentrations were analyzed for 4 hours at various time points by a HPLC - fluorimetric system, and pharmacokinetic parameters such as Co, MRT, AUC, Vdss, tl/2(p) and CLp were determined. Then, a small amount of hepatic tissue was obtained and subjected to determination of the hepatic 4 - hydroxyproline content, which confirmed the hepatic fibrotic severity. Results : The serum concentrations of propranolol at 0.5, 1, 2 and 4 hours were significantly increased in CC1q-treated rats (p$lt;0.01). In proportion to the duration of CC4 treatment, Co and AUC were significantly increased, and Vdss and CLp were significantly decreased (p$lt;0.001). But MRT and t1/2(β) were not significantly changed. The hepatic 4 -hydroxyproline content was gradually increased in CC4-treated rats (p$lt;0.001). Conclusion - Gradual changes in pharmacokinetic parameters of propranolol were seen to be dependent on the hepatic fibrotic severity. We suggest that gradual dosage modification, according to their hepatic fibrotic severity, is necessary for many drugs administered to patients with chronic liver disease.(Korean J Hepatol 2001;7:181-188)