• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.491-496
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• 2001

In recent years, the research and development about the new material proceed rapidly and actively in the building industry. As building structures become bigger, higher and more specialized, so does the demand for material with higher strength. In the future, we will need to research repair and rehabilitation to make high strength concrete mixed steel fibrous building safe. The carbon fiber reinforced plastic bonding method is widely used in reinforcing the existing concrete structure among the various methods. The repair of initiate loaded reinforced high-strength concrete beams mixed steel fibrous with epoxy bonded Carbon Fiber Sheets(CFS) was investigated experimentally. The CFS thickness and length were varied to assess the peel failure at the curtailment of CFS, The behaviour of the repaired beams was represented by load-longitudinal steel strain relation and failure modes were discussed. The test results indicate that CFS is very effective for strengthening the demand beams and controlling deflections of reinforced high strength concrete beams mixed steel fibrous happen diagonal crack, the increase in the number of CFS layers over two layers didn't effect the increase in the strength of beams.

• 한국도로학회논문집
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• 제18권3호
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• pp.11-19
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• 2016

PURPOSES : This study supports the evidence that it is possible to rehabilitate a damaged pavement with a lane closure specifically based on the Gimcheon~Sunsan project. METHODS : The prediction results from the simulation programs were compared with field monitoring, which focused on traffic management planning, congestion (length, time, and passing speed), bypass, and user cost, among others. RESULTS : The research results showed that lane closure application and pavement repair of the aged pavement in Korea were possible, even though the prediction results were minimally different from the field monitoring. The road agency contributes to service life extension of the rehabilitated pavement using this method. CONCLUSIONS : A marginal effect caused by the lane closure was observed on travelling users or vehicles, and the user cost of pavement repair decreased. Therefore, introducing the repair method or rehabilitation in Korea is possible. Information dissemination through various media was properly done to execute the project well. Moreover, the construction area traffic utilized nearby alternative roads. Therefore, improving the repaired pavemen's service life while ensuring that the pavement management agency can provide a road with comfortable user riding quality was possible.

• Wind and Structures
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• 제8권1호
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• pp.61-78
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• 2005

This paper presents results from an investigation of the structural behaviour of a very slender 90 m high steel chimney erected at V$\ddot{a}$xj$\ddot{o}$ in southern Sweden in 1995. The chimney is equipped with a mechanical friction-type damper at the top. Due to a mistake during erection and installation of the chimney the transport fixings of the damper were not released properly and the chimney developed extensive oscillations in the very first period of service. This caused a great number of fatigue cracks to occur within a few months of service. After the functioning of the damper had been restored and the fatigue cracks were repaired an extensive program was initiated in 1996 to monitor the structural behaviour of the chimney under wind loading. In the investigation data were collected for more than six years of continuous measurements and regular observations of the chimney. The data obtained have some general relevance with respect to wind data, behaviour of a slender structure under wind loading, and the effect of a mechanical damper. Also some theoretical studies were performed as part of the investigation of the chimney.

• 건축역사연구
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• 제22권6호
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• pp.59-66
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• 2013

This study progressed an investigation on the cause of the efflorescence phenomenon of bricks in Suwon Hwaseong Fortress, which is designated as a UNESCO World Heritage by using diverse scientific analyses. The samples were taken in Hwaseong and analyzed using XRD and SEM-EDS for the material identification of efflorescence. We observed under a polarizing microscope and measured absorption factors for the basic investigation for traditional bricks. As a result of material identification, soluble salt($Na_2SO_4$, $KNO_3$) and insoluble salt($CaCO_3$) were detected. There was no big difference between original bricks and repaired bricks under the polarizing microscope. However, in terms of the water absorption rate, bricks which were used for repair nowadays showed low water absorption rate(1%). In conclusion, soluble salt and insoluble salt appeared due to an effect of an air pollution and joint mortar. Soluble salt was removed in the rainy season, but insoluble salt was not removed. As a result of the efficiency and safety tests for chemicals removing efflorescence, chemical E is likely to be the suitable chemicals for the efflorescence phenomenon of traditional bricks in Suwon Hwaseong Fortress. In the future, consideration whether the use of lime is available or not should be studied through comprehensive researches including repair work, construction work and the environment factor with lime. Also, physical, chemical identifications of repairing bricks will be required.

• 한국지진공학회논문집
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• 제9권3호
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• pp.69-75
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• 2005

본 논문에서는 RC 교가의 보수${\cdot}$보강 시 사용되는 강판피복과 CFRP의 내진 보수성능을 비교하고, 횡방향 철근비가 강판과 CFRP로 보수된 실험체의 성능에 미치는 영향을 분석하였다. 이를 위하여 다른 횡철근비를 갖는 3개의 교각 실험체를 각 3개씩 총 9개를 제작하여 보수 전과 강판 및 CFRP보수 후의 거동을 비교하였다. 비교에 사용된 거동은 이력거동과 극한거동이며 이러한 거동은 반복하중 및 단조증가하중실험의 수행을 통하여 구하였다. 각 횡철근비 및 보수방법에 대하여 이력거동, 최대하중 및 최대변위를 비교한 결과 강판과 CFRP로 보수된 실험체의 변위연성과 최대하중이 증가하였음을 확인하였다. 또한 횡방향 철근비가 증가함에 따라서 실험체의 변위연성이 증가하였고, 소성힌지의 위치도 높아짐을 알 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.292-298
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• 2001

An experimental investigation of the effect of composite patching repair was conducted to characterize the fatigue crack growth behavior in thick A16061-T6 (6mm) panels with single bonded patch by fiber reinforced composite patch. Four patch lengths and no patch plate were examined. An analytical procedure, involving three-dimensional finite element method having three layers to model cracked aluminum plate, epoxy by adhesive and composite patch, is calculated the stress intensity factors. From the calculated stress intensity factors, the fatigue crack growth rates are obtained. At the single patching type, different fatigue crack growth ratios through the plate thickness were investigated by using the experimental and analytical results. The results demonstrated that there was a definite variation in fatigue life depending on the size of composite patch. While crack reached the patch end, retardation of crack growth was also revealed in the bonded repair.

• 한국염색가공학회지
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• 제11권2호
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• pp.38-45
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• 1999

Natural red colorants were extracted from Phytolacca americana Linne by using 50% ethanol solution at room temperature for 12 hours. The colorant components were partially purified as yellow and deep red colorants by thin layer chromatography. Natural red colorants were consisted of major water-soluble red colorant, having maximum absorbance at 538nm and alcohol-soluble yellow colorant, having maximum absorbance at 664nm. Concentration of red colorants were calibrated by the equation of dye(mg/ml) $A_{538nm}\times{1.284}$. Red colorants were changed to yellow at extreme alkali pH and repaired 55% color intensity by neutralization of pH and stabled below $55^\circ{C}$. Dyeability of red colorants against wool fabrics was mainly operated by red pigment having 538nm absorbance without big color differences. Below $55^\circ{C}$, color differences $(\Delta{E}^*_{ab})$ were not changed in spite of big difference of chroma$(c^*)$, having higher scores at higher temperature. The effect of mordants were not drastically changed parameters of color difference without copper ion. Citric acid was big changes of color difference$(\Delta{E}^*_{ab})$ in spite of similar chroma$(c^*)$ values. From these experimental results, red colorants from Phytolacca americana Linne is available for wool fabric dyeing.

• 한국정밀공학회지
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• 제27권12호
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• pp.99-106
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• 2010

Gas turbines operation for power generation increased rapidly since 1990 due to the high efficiency in combined cycle, relatively low construction cost and low emission. But the operation and maintenance cost for gas turbine is high because the expensive superalloy hot gas path parts should be repaired and replaced periodically This study analyzed the initiation and propagation of the crack at the gas turbine blades which are coated with MCrAIY as a bond coat and TBC as a top coat. The sample blades had been serviced at the actual gas turbines for power generation. Total 7 sets of blades were analyzed and they have different EOH(equivalent operation hour). Blades were sectioned and the cracking distribution were measured and analyzed utilizing SEM(scanning electron microscope) and optical microscope. The blades which had 52,000 EOH of operation had cracks at the substrate and the maximum depth was 0.2 mm. Most of the cracks initiated at the boundary layer between TBC and bond coat and propagated down to the bond coat. Once bond coat is cracked, the base metal is exposed to the oxidation condition and undergoes notch effect. Under this environment, the crack branched at the inter-diffusion layer and propagated to the substrate. Critical cracks affecting the blade life were analyzed as those on suction side and platform.

• 한국임상수의학회지
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• 제21권4호
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• pp.406-408
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• 2004

A nine-month-old male Jindo with non weight-bearing on the right forelimb in flexed position, pain and edema of the elbow, and resist elbow extension was brought to the Veterinary Teaching Hospital, Chungbuk National University. Elbow radiographs showed loss of humeroradial joint space and lateral displacement of the radius and ulna. Closed reduction was reported the best therapy in most cases of luxation of the elbow but conservative reduction was impossible. Open reduction of the luxated elbow was performed and ruptured collateral ligaments were identified. Displaced elbow was required bloody surgical operation and gentle reduction to restore elbow joint. Internal reduction of choice for elbow luxation with rupture of collateral ligament in the dog was a double locking-loop suture pattern. To ensure secure grasping of parallel bundles of ligament fibers to transverse bites of each suture were placed superficial to the longitudinal bites. All ligaments were repaired with 3-metric (size 2 USP) monofilament polypropylene suture. No complications have been noted during a five-month follow up.

• 한국동물학회지
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• 제20권2호
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• pp.93-99
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• 1977

HeLa $S_3$세포에서 MMC에 의해 유발된 DNA회복합성은 농도$(0.05\\sim 0.5\\mu g/ml)$에 따른 증가를 보이지 않고 그 율도 비\ulcorner적 낮아 $0.1\\sim 0.5\\mu g/ml$ 농도에서 조사한 전 세포의 $7\\sim 9%$를 나타내고 있다. 시간 변화에 따른 실험에서는 MMC를 제거한 후 24시간까지 거의 비슷한 율로 DNA회복합성이 계속되고 있다. thymidine 상사체중 BUdR을 전처리한 군에서만이 MMC에 의한 DNA회복합성을 증가시켰다. 그러나 BUdR 또는 IUdR과 MMC를 복합처리 할 경우 시간경과에 따라 정상 DNA합성은 감소된다. 이들 결과는 MMC에 의해 유발된 DNA손상은 빠르고 느린 두단계로 회복됨을 암시하는 것이라 생각된다.