In this study, non-destructive technologies that can be applied to evaluate the integrity of valve materials, safety against internal pressure caused by corrosion, and the blocking function of large-diameter water valves during operation without requiring specimen collection or manpower entering the inside of the valve were tested to assess the reliability of the technologies and their suitability for field application. The results showed that the condition of the graphite structure inside the valve body can be evaluated directly through the optical microscope in the field without specimen collection for large-diameter water butterfly valves, and the depth of corrosion inside the valve body can be determined by array ultrasound and the tensile strength can be measured by instrumented indentation test. The reliability of each of these non-destructive techniques is high, and they can be widely used to evaluate the condition of steel or cast iron pipes that are significantly smaller in thickness than valves. Evaluation of blocking function of the valves with mixed gas showed that it can be detected even when a very low flow rate of mixed gas passes through the disk along with the water flow. Finally, as a result of evaluating the field applicability of non-destructive technologies for three old butterfly valves installed in the US industrial water pipeline, it was found that it is possible to check the material and determine the suitability of large-diameter water valves without taking samples, and to determine the corrosion state and mechanical strength. In addition, it was possible to evaluate safety through the measurement results, and it is judged that the evaluation of the blocking function using mixed gas will help strengthen preventive response in the event of an accident.

In this study, the physical properties and fracture characteristics according to the tensile load are evaluated on the materials of the polymeric filler and carbon fiber-based composite sleeve technique. The polymeric filler and the composite sleeve technique are applied to areas where the pipe body thickness is reduced due to corrosion in large-diameter water pipes. First, the tensile strength of the polymeric filler was 161.48~240.43 kgf/cm2, and the tensile strength of the polyurea polymeric filler was relatively higher than that of the epoxy. However, the tensile strength of the polymeric filler is relatively very low compared to ductile cast iron pipes(4,300 kgf/cm2<) or steel pipes(4,100 kgf/cm2). Second, the tensile strength of glass fiber, which is mainly used in composite sleeves, is 3,887.0 kgf/cm2, and that of carbon fiber is up to 5,922.5 kgf/cm2. The tensile strengths of glass and carbon fiber are higher than ductile cast iron pipe or steel pipe. Third, when reinforcing the hemispherical simulated corrosion shape of the ductile cast iron pipe and the steel pipe with a polymeric filler, there was an effect of increasing the ultimate tensile load by 1.04 to 1.06 times, but the ultimate load was 37.7 to 53.7% compared to the ductile cast iron or steel specimen without corrosion damage. It was found that the effect on the reinforcement of the corrosion damaged part was insignificant. Fourth, the composite sleeve using carbon fiber showed an ultimate load of 1.10(0.61T, 1,821.0 kgf) and 1.02(0.60T, 2,290.7 kgf) times higher than the ductile cast iron pipe(1,657.83 kgf) and steel pipe(2,236.8 kgf), respectively. When using a composite sleeve such as fiber, the corrosion damage part of large-diameter water pipes can be reinforced with same level as the original pipe, and the supply stability can be secured through accident prevention.

In this study, as the proportion of aged pipelines increases rapidly, in the event of an accident caused by corrosion and structural deterioration of metal pipes, appropriate overlay welding is applied in the field to partially repair it. The size of the base steel plate and the selection of a stable welding method were evaluated, and possible problems caused by the overlay welding were identified, and improvement measures were proposed. For the test, a new steel pipe coated with epoxy lining on the inner surface and polyethylene on the outer surface was subjected to a tensile test by processing the repaired specimen through overlay welding with a steel plate after artificial cracking, and structural safety was evaluated after repair. Furthermore, the influences of the size of the throat and the size of the steel plate were analyzed. As a result of the tensile test by dividing the repaired steel plate overlay into a constraint and non-constraint conditions, the tensile load was concentrated in the welded part and damage occurred in the welded part. It was found that the maximum load leading to breakage increases as the size of the welding throat increases. In addition, it was found that the resistance to load increased slightly as the size of the overlaid steel plate increased, but the effect was not significant, confirming the need for repair in consideration of the site conditions. As a result of evaluating the damage to the coating material on the back side of the welding, it was confirmed that the coating material on the opposite side of the welding burned black(epoxy) or was greatly deformed by heat(polyethylene). Therefore, it is necessary to secure structural stability through repainting, etc. in order to prevent damage to the coating material on the opposite side during overlay welding.

In this study, in order to manufacture STS 316L seamless pipes with 18mm, 25mm, and 42mm diameters that can be used for high pressure, we intend to make predictions through design and finite element analysis and produce real objects. It was measured to have the highest hardness value in the deformed part, and it is expected to be due to work hardening. It has been interpreted that plastic deformation does not occur up to 1,000bar for STS 316L seamless pipes with a diameter of 18mm and 25mm, but plastic deformation occurs at 900bar or more in STS 316L seamless pipes with a diameter of 42mm.

The purpose of this study was to evaluate the corrosion damage of large diameter metallic pipes buried in reclaimed land due to the corrosion effect by soil, and to propose a method of installing metal pipes in the reclaimed land. The results are as follow. First, the soil of the reclaimed land was gray clay, the soil specific resistance indicating soil corrosiveness was at least 120 Ω-cm, the pH was weakly acidic(5.04 to 5.60), the redox potential was at least 62 mV, the moisture content was at most 48.8%, and chlorine ions and sulfate ions were up to 4,706.1 mg/kg and 420 mg/kg. Therefore, the overall soil corrosivity score was up to 19, and the external corrosion effect seems to be very large. Second, the condition of straight part of pipes was in good condition, but most of KP joints were affected by corrosion at a severe level. The reason for this seems to be that KP joints accelerated corrosion due to stress and crevice corrosion in addition to galvanic corrosion in the same environment. Third, as a result of evaluating correlations of each item that affects the corrosion on the external part, the lower the soil resistivity and redox potential, the greater the effect on the KP joints corrosion, and the moisture content, chloride ion, and sulfate ion, the higher the value, the greater the effect on the corrosion of KP joints. In addition, among soil corrosion items, the coefficient of determination of soil resistivity with corrosion of KP joints was the highest with 0.6439~0.7672. Fourth, when installing metal pipes or other accessories because the soil of the reclaimed land is highly corrosive, it is necessary to apply a corrosion preventive method to extend the life of pipes and prevent leakage accidents caused by corrosion damage to the joint.

In order to commercialize large diameter PP pipes, the cutting work was attempted with the cutting machine (∅18″and AL120 cutter, 2100 r.p.m) used for the conventional PE or PVC pipe(∅1200 mm, t 70), but the cutting work was failed because the material of “PP pipe” melted and sticked to the surface of the wheel-cutter. In order to find the optimal structure and number of blades for wheel-cutters, an experimental investigation the temperature measurement of specimen and wheel-cutter and the visualization of cutted specimen surface and chip shape were carried out during and after experiment. In addition, modelings for cutting and heat transfer mechanisms have been developed for theoretical analysis. The theoretical and experimental results were in good agreement. The results show that the appropriate structure and the rotational speed of wheel-cutter are W60 and 650 rpm for the large diameter PP pipe cutting machine.

Due to the sewer induced ground subsidence, there is an increasing demand for the advanced visual inspection technique for the existing sewer pipe structures. This study aim to develop a new condition assessment method using visual inspection device with automatic crack extracting and real-time gas monitoring systems for large diameter glass-fiber reinforced plastic sewer pipes. In this paper, a high-precision image capturing system that automatically extracts cracks in the large-diameter sewer pipes and sewage culverts with a diameter of 1,000 mm or more, and a real-time gas detection sensor for investigator safety were considered. By analyzing the module technology of the visual inspection device, the test device and their software for system integration were developed. It is expected that the developed technique inspecting conditions of the GFRP sewer pipes using the proposed visual inspection device in this study can be effectively used for various types of underground structures in the future.

This study develops a model to estimate the economic life of the large-diameter water supply pipeline in Korea by supplementing existing methods used to perform similar calculations. To evaluate the developed methodology, the model was applied to the actual target area with the conveyance pipe in P waterworks. The application yielded an economic life computation of 39.7 years, considering the cost of damages, maintenance, and renewal of the pipeline. Based on a sensitivity analysis of the derived results, the most important factor influencing the economic life expectancy was the predicted failure rate. The methodology for estimating the economic life of the water supply pipeline proposed in this study is one of the core processes of basic waterworks facility management planning. Therefore, the methods and results proposed in this study may be applied to asset management planning for water service providers.

Multi-regional water supply system, which installed for supplying multiple water demands, is characterized by large-sized, long-distance, tree-type layout. This system is vulnerable to long-standing service interruption when a pipe breaks is occurred. In this study, a numerical method is proposed to calculate drainage time that directly affects time of service interruption. To begin with, governing equations are formulated to embed the delayed drainage effect by the friction loss, and to resolve complicated connection of pipelines, which are derived from the continuity and energy equations. The nonlinear hydraulic equations are solved by using explicit time integration method and the Newton-Raphson method. The developed model is verified by comparing the result with analytical solution. Furthermore, the model’s applicability is validated by the examples of pipelines in serial, in parallel, and complex layout. Finally, the model is utilized to suggest an appropriate actions to reduce the deviation of draining time in the C transmission line of the B multi-regional water supply system.

Because freesia is a crop that is typically vegetatively propagated from offsets, a degradation in its genetic character or an onset of after successive culturing over a long period. To produce virus-free freesia corms, apical meristem culture and rapid mass propagation must be established. This study aimed to establish the rapid mass production of in vitro freesia corms using a bioreactor. Shoots (12 – 15 cm in height) obtained from tissue culture were used as the plant material in a balloon-type bubble bioreactor in which medium strength, sucrose concentration, inoculation plant volume, and medium exchange method were determined. Medium strengths tested included full strength (1), 1/2, and 1/4 strength MS medium; sucrose concentration 9% 12%, and 15%, and inoculation plant volumes were tested at 40, 80, 120, and 160 shoots/1L medium. MS medium was supplemented with a 1/2 volume of the initial volume or the medium was completely exchanged with a new medium or not exchanged at all throughout the experiment. Results indicated the best growth of freesia corms at 1/2 strength medium, 9% sucrose, 120 shoots/L medium, with complete medium exchange 4 weeks after initiating the experiment. Under these culturing conditions, corms with 0.5 g fresh weight, 0.15 g d ry w eight, 1 3 mm h eight, a nd 0 .9 mm diaeter were harvested from the bioreactor within only 6 weeks, which were large enough to be planted in field. Thus, our results indicated that the cost and period for the production of freesia corms in vitro can be markedly decreased.

In this study, we suggested the jacking method of small diameter sewer pipe for improving workability of the pipe at the weak ground. The jacking method minimizes the space and time in constructing small diameter sewer pipe. In addition, to use this method do not cause road restrictions during the construction period. In this study, the construction process of the small diameter sewer pipe is explained. In addition, to ensure the safety during construction, the design consideration such as earth pressure and the jacking force of the steel pipe, and safety against boiling of the ground were examined. For verify the safety of this jacking method, it is necessary to carry out an experiment to estimate the safety of main pipe under construction.

Due to the sewer induced ground subsidence, there is an increasing demand for the advanced visual inspection technique for the existing sewer pipe structures. This study aim to develop a visual inspection device and real-time transmission system of inspection data with precisely evaluated structural and operational conditions of underground sewer pipe structures. In this paper, a high-precision image capturing system that automatically extracts cracks in the large-diameter sewer pipes and sewage culverts with a diameter of 1,000 mm or more, a real-time gas detection sensor for investigator safety were studied. By analyzing the module technology of the visual inspection device, the concept design for system integration was derived, and the real time transmission system of the inspection result was developed to establish the technical basis for the commercialized device. Also the crack detection test using crack calibration was carried out for the proposed image capturing camera system, and the position accuracy using L1 grade GPS module was tested in this study. The inspection technique of the existing structure condition using the visual inspection device in this study can be effectively used for various structures types and advanced composite structures in the future.

프리지아 구경을 기내에서 급속대량증식시킬 목적으로 액 체진탕배양을 이용한 신초 생육 및 구경 비대에 적합한 몇 가지 조건을 구명하기 위해 실험을 수행하였다. 기내에서 획득 한 프리지아 부정아를 MS 배지 농도와 sucrose 농도를 달리한 액체배지에서 배양했을 때, 1/2 MS배지와 3% sucrose 농도에 서 생체중과 건물중이 가장 높게 나타나는 등 생육이 가장 빠 르고 좋았던 것으로 나타났다. 액체진탕배양에서 프리지아의 구경을 비대시킬 목적으로 배양 온도, sucrose 농도, 광의 유 무가 구경비대에 미치는 영향에 대해 실험을 수행하였다. 구 경의 비대는 1/2 MS 배지에 9% sucrose를 첨가하여 17℃ 암 조건에서 배양했을 때 가장 우수하였다. 이런 조건에서 6주간 배양하였을 때, 구경 생체중과 구고는 각각 2.5g, 23mm로 농 가에 정식 가능한 크기로 생장되었음을 확인하였으며, 이는 대조구(고체배지)에 비해 5배 이상 증가한 크기였다. 광조건 하에서도 구경 비대는 양호하였으나, 구경의 측아로부터 자구 가 발생하는 문제가 확인되었다.

국내 육성 프리지아(Freesia)가 농가에 보급되고 시간이 지나면서 바이러스에 감염되거나 품질이 저하되는 문제가 발생하고 있다. 고품질을 유지하기 위해서는 생장점 배양을 통해 무병종구를 만들고 기내에서 급속 대량증식하여 농가에 보급하는 일이 시급하다. 본 연구에서는국내에서 육성된 프리지아 ‘Shiny Gold’와 ‘Gold Rich’의자구를 이용하여 효과적인 급속 대량증식 기술을 찾고자실험을 수행하였다. 배지는 MS기본배지에 호르몬을 첨가하지 않은 배지와 5.0mg•L−1 NAA+5.0mg•L−1 Kinetin를 넣은 호르몬배지 2종류를 이용하였다. 치상방법은 자구를 횡으로 절단한 절편체를 정상으로 치상(정상치상)한경우와 위아래를 거꾸로 치상(역위치상)하는 2가지 방법을 이용하였다. 치상한 절편체는 23oC의 암배양실에서 5주간 배양한 후, 광도 60µmol•m−2s−1 (16/8, 주/야)의 광환경으로 옮겨 주었다. 치상 10주째에 두 품종 모두 역위치상하였을 때, 정상치상에 비해 부정아 발생이 2~6배 정도 증가하였다. 이러한 결과는 호르몬 유무에 상관없이 비슷한 결과를 보였다. 역위치상하고 19주 후 ‘ShinyGold’의 신초수는 기본배지에서 절편체당 42.7개로 정상치상에 비해 약 2.5배 증가되었고, 호르몬 첨가배지에서는 17.7개로 정상치상에 비해 약 7.1배 증가되었다. ‘GoldRich’를 역위치상 하였을 때, 기본배지에서는 신초수가 절편체당 55.4개로 대조구에 비해 약 1.7배 증가되었고, 호르몬 첨가배지에서는 61.0개로 대조구에 비해 약 2.4배증가되었다. 결론적으로 프리지아 자구를 기내에서 급속대량증식 하고자 할 때, 호르몬 유무와 상관없이 자구를횡으로 절단하여 역위치상 하는 방법이 효율적이라는 것을 알 수 있었다.

HCFFT (Hybrid Concrete Filled FRP Tube) is consisted of pultruded FRP unit module, filament winding FRP which is in the outside of mandrel composed of circular shaped assembly of pultruded FRP unit modules, and concrete which is casted inside of the circular tube shaped hybrid FRP pile. The pultruded FRP can increase the flexural load carrying capacity and the filament winding FRP can provide the confinement for the concrete filled inside. The axial and flexural load carrying capacities of small diameter HCFFT piles were evaluated through the experimental and theoretical studies. In this study, we suggest the cross-section and manufacturing process of large diameter HCFFT pile which is expected to improve the quality and productibility of large diameter HCFFP pile.

The end shape of tube for automobile power steering system has influence on the ability of performance. In this case study, we attempted to optimize the forming process of a small tube using Taguchi experimental design methodology. A preliminary experimen

실험식물로는 Gladiolus gandavenesis L. ‘Spic and Span’과 ‘Nova Lux’를 사용하였다. ‘Spic and Span’의 경우 맹아된 지상부 생육의 경우 초장, 엽수, 및 맹아수 등에서는 큰 차이가 없었다. 초장, 엽수 총 맹아수는 전체적으로 유의성은 없었다. 엽폭은 NH4 +:NO3 − 비율이 50:50일 때 1.38로 유의성이 컸다. ‘Spic and Span’의 경우 전체적으로 NH4 +:NO3 − 비율 의 영향을 받지 않는 것으로 생각된다. 지하부 생육을 살펴보면 구고, 구생체중 등에서 비슷한 생육을 보였으 나 NO3 −가 증가할수록 목자수가 2.4개로 유의성 있게 많았다. ‘Nova Lux’의 지상부 생육은 NH4 +:NO3 − 비 율이 50:50에서 가장 좋았다. 초장은 모든 처리구에서 유의성이 없었고, 엽폭은 1.45cm로 가장 컸으며, 총 맹아수는 25개로 많았다. NH4 +가 증가할수록 구직경, 구고, 생체중, 목자수 등의 지하부 생육은 증가하는 경 향이었다. 전체적으로 두 품종 모두 지상부 생육은 NH4 +:NO3 − 비율이 50:50에서 가장 좋았고, 지하부 생 육에서 ‘Spic and Span’은 NO3 −, ‘Nova Lux’는 NH4 +가 많으면 목자가 많이 생산되었다.

본 시험은 제주도 화산회토양에서 식용 Canna의 구경크기에 따른(10, 15, 20, 25cm) 생육특성 및 수량을 구명하기 위하여 2003년 5월 20일부터 11월 24일까지 시험하였다. 초장은 구경크기 l0cm 파종에서 78.8cm 이었던 것이, 구경크기가 커짐에 따라 점차적으로 커져서 구경 25cm 크기에서는 129.1cm 커졌다(). 구경크기에 따른 엽장, 엽폭, 엽수, 분지수, 경직경 및 구경수는 초장반응과 비슷한 경향이었다. 생초수량, 구경