• 대한토목학회논문집
• /
• 제42권5호
• /
• pp.607-616
• /
• 2022

전 세계적으로 이상 기후 및 자연재난 등으로 인하여 철근콘크리트 구조물의 부식 및 열화 현상이 빈번히 발생됨에 따라 구조물의 노후화가 가속화되고 있다. 건설 분야에서는 이러한 내하력 저하에 대응하기 위하여 최근 저 중량 고강도 재료 장점을 가진 유리섬유 복합재료(GFRP)를 활용하여 많은 노후 구조물에 대하여 보수·보강을 수행하고 있다. 본 연구에서는 유리섬유에 비하여 보다 경제적이고 친환경적인 바잘트 섬유 복합재료(BFRP)를 활용하여 콘크리트 압축부재의 내진보강을 위한 횡구속 효과를 더욱 효과적으로 제공할 수 있는 보강재를 개발하고 그 성능을 평가하였다. 실험 시 고려된 주요 변수로는 바잘트섬유 복합재료(BFRP) 시공 시 적용되는 함침 수지의 양생 온도와 대상 콘크리트 압축부재의 재료 특성을 고려하였다. 콘크리트 압축부재의 재료 특성에 따른 횡구속 보강효과를 조사하기 위하여 본 연구에서는 일반 콘크리트와 섬유 보강을 통하여 내구성능이 개선된 콘크리트 시험체를 각각 제작하여 성능을 평가하였다. 그 결과, 일반 콘크리트의 경우 3.15배, 섬유 보강 콘크리트의 경우 약 3.72배의 보강 효과가 나타났으며 압축부재 내구특성 개선에 따른 보강 효과의 차이는 크지 않음을 알 수 있었다. 마지막으로 GFRP 압축부재 보강재에 대한 선행연구 결과를 통하여 바잘트 보강 복합재료의 성능을 비교한 결과 BFRP 보강재의 횡구속 보강효과가 상대적으로 약 1.18배 GFRP 보강재에 비하여 성능이 우수한 것으로 나타났다.

• Archives of Pharmacal Research
• /
• 제25권5호
• /
• pp.655-663
• /
• 2002

Liver fibrosis is a prepathological state wherein damaged liver tissues in chronic liver diseases, such as hepatitis, are not repaired to normal tissues, but converted to fibrous tissue. 5-(2-Pyrazinyl)-4-methyl-1,2-dithiol-3-thione (oltipraz), a cancer chemopreventive agent, is effective against a wide variety of chemical carcinogens. Recently, we reported that oltipraz inhibits liver fibrogenesis (Kang et al., 2002). In the present study, the effects of oltipraz in combination with dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDb) on dimethylnitrosamine (DMN)-induced liver fibrogenesis were assessed in rats. Oltipraz (30 mg/kg body weight, po, 3 times per week for 4 weeks) was found to inhibit the increases in plasma ALT, AST and bilirubin by DMN, whereas DDB (30 mg/kg body weight, po, 3 times per week for 4 weeks) attenuated the increases in the plasma ALT and bilirubin. The lowered plasma protein and albumin contents in DMN-treated rats were completely restored by oltipraz, but not by DDB. DDB decreases liver cell injury and inflammation through inhibition of nuclear factor-kB. DMN increased the accumulation of liver collagen, as indicated by the increase in the 4-hydroxyproline content in liver homogenates, which was reduced by treatment with oltipraz, but not by DDB. Given the differential effect between oltipraz and DDB, the potential enhancement of antifibrotic efficacy by the drugs was assessed in the animal model. Despite the minimal effect of DDB on DMN-induced fibrogenesis, DDB (5-25 mg/kg), administered together with oltipraz (25-5 mg/kg), showed an additive protective effect against hepatotoxicity and fibrosis induced by DMN, which was shown by the blood chemistry parameters and histopathological analysis. The adequate composition ratio of oltipraz to DDB was 5:1. These results provide information on the pharmaceutical composition, comprising of oltipraz and DDB as the active components, for the treatment and/or prevention of liver fibrosis and cirrhosis.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 추계학술발표대회
• /
• pp.5.2-5.2
• /
• 2009

From 10 years ago, the development of nano-devices endeavored to achieve reconstruction of information technology (IT) and nano technology (NT) industry. Among the many materials for the IT and NT industry, zinc oxide (ZnO) is a very promising candidate material for the research of nano-device development. Nano-structures of ZnO-based materials were grown easily via various methods and it attracts huge attention because of their superior electrical and optical properties for optoelectronic devices. Recently, among the various growth methods, MOCVD has attracted considerable attention because it is suitable process with benefits such as large area growth, vertical alignment, and accurate doping for nano-device fabrication. However, ZnO based nanowires grown by MOCVD process were had the principal problems of 1st interfacial layers between substrate and nanowire, 2nd a broad diameter (about 100 nm), and 3rd high density, and 4th critical evaporation temperature of Zinc precursors. In particular, the growth of high performance nanowire for high efficiency nano-devices must be formed at high temperature growth, but zinc precursors were evaporated at high temperature.These problems should be repaired for materialization of ultra high performance quantum devices with quantum effect. For this reason, we firstly proposed the growth method of vertical aligned slim MgZnO nanowires (< 10 nm) without interfacial layers using self-phase separation by introduced Mg at critical evaporation temperature of Zinc precursors ($500^{\circ}C$). Here, the self-phase separation was reported that MgO-rich and the ZnO-rich phases were spontaneously formed by additionally introduced Mg precursors. In the growth of nanowires, the nanowires were only grown on the wurzite single crystal seeds as ZnO-rich phases with relatively low Mg composition (~36 at %). In this study, we investigated the microstructural behaviors of self-phase separation with increasing the Mg fluxes in the growth of MZO NWs, in order to secure drastic control engineering of density,diameter, and shape of nanowires.

• Journal of Chest Surgery
• /
• 제19권2호
• /
• pp.232-237
• /
• 1986

The intraventricular conduction disturbances have been documented after correction of ventricular septal defects by any surgical route but debated its etiology. And so the frequency of conduction disturbances following right ventriculotomy, right atriotomy and pulmonary arteriotomy for closure of ventricular septal defects was compared in various conditions. The present series consists of 218 patients with ventricular septal defects. They had the surgical repair at the Seoul National University Hospital from January 1983 to October 1984. Conduction disturbances were studied with conventional 12 leads electrocardiogram. Of the 218 VSD`s 139 patients were repaired via vertical right ventriculotomy, 45 patients via right atriotomy, 34 patients via pulmonary arteriotomy. 1] Of 218 patients the frequency of RBBB was 26.1% and the frequency of RBBB + LAH was 6.0%. 2] There is no statistical difference between right ventriculotomy group [30.2%] and right atriotomy group [24.4%]. But there is significant difference between right ventriculotomy group and pulmonary arteriotomy group [11.8%] [P<0.05]. 3] In respect to anatomical classification by Kirklin`s method, the frequency of RBBB was higher in type II [32.1%] than in type I [14.9%]. [P<0.05] But in each anatomical type, there is no influence of the various surgical approach on the incidence of postoperative RBBB. 4] The frequency of RBBB was 31.8% in patch closure group and 14.3% in direct closure group. [P<0.05] Although the result suggests that there is no significant difference in various surgical approaches on the incidence of postoperative conduction disturbances, it may be reduced by a new-ventricular approach or a limited incision at right ventricular outflow tract in right ventricular approach.

• Journal of Chest Surgery
• /
• 제21권6호
• /
• pp.1117-1123
• /
• 1988

Prolapse of the aortic valve is the main cause of insufficiency of the aortic valve as a complication of ventricular septal defect. Aortic insufficiency gets worse by the progress of prolapse of aortic valve due to lack of support of the valve and the hemodynamic effect of blood flow through the ventricular septal defect. This produces typical clinical picture, that may be serious and threatening when it is untreated. Type and timing for the surgical treatment of the ventricular septal defect with aortic insufficiency is considered. Among 113 ventricular septal defect, 9 patients of ventricular septal defect with associated aortic insufficiency were experienced from June. 1983 to June 1988 at the Department of Thoracic and Cardiovascular Surgery, Chon-Buk University Hospital. Male was 6 patients and female was 3 patients. Ages were from 7 years to 24years. 5 patients were from 10 to 19 years age. 3 patients were below 10 years age. The ratio of pulmonary blood flow to systemic f low [Qp/Qs] was 1.53 and in pulmonary vascular resistance, normal or slight increase was 7 patients, moderate 1 patient, and severe 1 patient. Ventricular septal defect was subpulmonic in 5 patients and infracristal in 4 patients. Prolapse of right coronary cusp was 7 patients, right and non coronary cusp 1 patient and non coronary cusp 1 patient. Teflon patch closure of ventricular septal defect was undertaken in 3 patients and primary closure in 1 patient. Among the 4 patients of defect closure alone, one patient performed valve replacement 7 months later due to progressive regurgitation and cardiac failure and the result was good. The other 3 patients were good result. Closure of ventricular septal defect and aortic valvuloplasty performed in 4 patients. 2 patients of these required valve replacement for the sudden intractable cardiac failure and died due to low cardiac output. The cause of intractable cardiac failure was tearing of repaired valve at the fixed site. The other 2 patients were good result. Closure of ventricular septal defect and valve replacement performed in 1 patient with good result.

• 대한임상검사과학회지
• /
• 제43권4호
• /
• pp.179-187
• /
• 2011

Animal models are important tools in thrombosis research and preclinical drug development. In recent studies, ferric chloride ($FeCl_3$) has been widely used to induce arterial thrombosis in a variety of species. The purpose of this study was to find an optimal concentration of $FeCl_3$ and validate this model suited better for thrombosis research. A small piece of filter paper, soaked in $FeCl_3$ solution (10, 20 or 35%, v/v, in distilled water) was topically applied on the carotid artery of SD rats to measure the time to occlusion (TTO) and thrombus weight (TW) to ascertain 35%, as an optimal $FeCl_3$ concentration ($8.63{\pm}0.92min$; p =0.000, $0.79{\pm}0.03mg/mm$; p =0.000, respectively). To validate this experimental model, Ginkgo biloba special extract EGb761 (5, 10 or 30 mg/kg) as a reference agent administered by peritoneal route for 1h prior to the induction of thrombosis, showed significantly delayed TTO in a dose dependent manner ($18.50{\pm}2.17$, $29.17{\pm}1.83$, and $38.00{\pm}1.79min$, respectively) and significantly reduced TW and repaired collagen fibre in the injured vessel compare to vehicle group. Our results provide a simple, reproducible and well controlled in vivo screening system to induce thrombosis in rats by the topical application of 35% $FeCl_3$ to assess the efficacy of the new anti-thrombotic agents.

• Journal of Microbiology and Biotechnology
• /
• 제9권1호
• /
• pp.70-77
• /
• 1999

An extremely cadmium-tolerant budding yeast, Hansenula anomala B-7 underwent a morphological switch in response to either heat shock treatment or cadmium stress, respectively. It exhibited a morphological transition from a unicellular yeast form to a pseudohyphae-like coagulation when subjected to prolonged heat shock treatment. In contrast, the yeast cells showed an irregularity in surface morphology when given thermal stress for a short time. Patterns of proteins expressed in the pseudohyphae-like cells demonstrated that several proteins were overexpressed while others were underexpressed in comparison with those prepared from the cells in the yeast form. It was a striking feature, however, that nearly 40％ of the proteins extracted from the cells in the pseudohyphae form appeared to be composed of a single polypeptide. This polypeptide was apparently overexpressed during the pseudohyphae phase and its molecular weight was estimated to be 58 kDa according to SDS-PAGE analysis. However, a significant level of the protein was not observed in the cells before transition to pseudohyphae. The architecture of the cell shape was also damaged when incubated in a medium containing more than 1,000 ppm (8.9mM) of cadmium ions, although able to proliferate at a slow rate. However, the irregularity in the cell morphology exerted either by the brief heat shock treatment or by the cadmium stress with the high concentrations of the metal ions was not repaired, even though the damaged cells were allowed to grow for sufficient time in fresh, cadmium-free medium.

• 한국임상수의학회지
• /
• 제21권3호
• /
• pp.253-258
• /
• 2004

DNA double-strand break (DSB) is a serious treat for the cells including mutations, chromosome rearrangements, and even cell death if not repaired or misrepaired. Ku heterodimer regulatory DNA binding subunits (Ku70/Ku80) bound to double strand DNA breaks are able to interact with 470-kDa DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and the interaction is essential for DNA-dependent protein kinase (DNA-PK) activity. The Ku80 mutants were designed to bind Ku70 but not DNA end binding activity and the peptides were treated in breast cancer cells for co-therapy strategy to see whether the targeted inhibition of DNA-dependent protein kinase (DNA-PK) activity sensitized breast cancer cells to ionizing irradiation or chemotherapy drug to develop a treatment of breast tumors by targeting proteins involved in damage-signaling pathway and/or DNA repair. We designed domains of Ku80 mutants, 26 residues of amino acids (HN-26) as a control peptide or 38 (HNI-38) residues of amino acids which contain domains of the membrane-translocation hydrophobic signal sequence and the nuclear localization sequence, but HNI-38 has additional twelve residues of peptide inhibitor region. We observed that the synthesized peptide (HNI-38) prevented DNA-PKcs from binding to Ku70/Ku80, resulting in inactivation of DNA-PK complex activity in breast cancer cells (MDA-465 and MDA-468). Consequently, the peptide treated cells exhibited poor to no DNA repair, and became highly sensitive to irradiation or chemotherapy drugs. The growth of breast cancer cells was also inhibited. These results demonstrate the possibility of synthetic peptide to apply breast cancer therapy to induce apoptosis of cancer cells.

• Journal of Welding and Joining
• /
• 제15권1호
• /
• pp.101-108
• /
• 1997

손상된 터어빈 로터강의 보수 용접에 있어서 용접부의 크립 파단 수명과 탄화물간의 관계가 연구되었다. 탄화물은 탄화물 추출 복제법을 이용하여 확인되었으며 로터강에는 Molybdenum 주성분의$M_2C$, Vanadium 주성분의 $M_4C_3$, 및 Chromium 주성분의 $M_{23}C_6$와 $M_7C_3$ 탄화물이 존재하였다. 한편 ICHAZ에서 파단된 시험편의 파단면에서는 구상의 조대한 Molybdenum 주성분의 $M_6C$ 탄화물이 발견되었다. 조대한 Molybdenum 주성분의 $M_6C$ 탄화물의 석출은 탄화물 주위에 고용경화 원소인 Molybdenum 농도를 떨어뜨려 기공 발생 원인을 제공하였다. CGHAZ에서 파단된 용접부의 파단면에서는 조대한 $M_6C$ 와 $M_{23}C_6$가 발견되었다.

• Tuberculosis and Respiratory Diseases
• /
• 제78권3호
• /
• pp.239-245
• /
• 2015

Background: Chronic obstructive pulmonary disease is characterized by emphysema, chronic bronchitis, and small airway remodeling. The alveolar destruction associated with emphysema cannot be repaired by current clinical practices. Stem cell therapy has been successfully used in animal models of cigarette smoke- and elastase-induced emphysema. However, the optimal dose of mesenchymal stem cells (MSCs) for the most effective therapy has not yet been determined. It is vital to determine the optimal dose of MSCs for clinical application in emphysema cases. Methods: In the present study, we evaluated the therapeutic effects of various doses of MSCs on elastase-induced emphysema in mice. When 3 different doses of MSCs were intravenously injected into mice treated with elastase, only $5{\times}10^4$ MSCs showed a significant effect on the emphysematous mouse lung. We also identified action mechanisms of MSCs based on apoptosis, lung regeneration, and protease/antiprotease imbalance. Results: The MSCs were not related with caspase-3/7 dependent apoptosis. But activity of matrix metalloproteinase 9 increased by emphysematous lung was decreased by intravenously injected MSCs. Vascular endothelial growth factor were also increased in lung from MSC injected mice, as compared to un-injected mice. Conclusion: This is the first study on the optimal dose of MSCs as a therapeutic candidate. This data may provide important basic data for determining dosage in clinical application of MSCs in emphysema patients.