• Advances in concrete construction
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• v.9 no.2
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• pp.217-225
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• 2020

The recovery of waste proves a solution with two impacts: the environmental impact by the reduction of pollution and the gain of the occupied space by this waste, and the economic impact by the use of these lasts in the building and in the area of public works. The present research consists in recovering a waste marble (thrown powder exposed to the different meteorological phenomena) generated by the quarry marble of Fil-fila, located at the east side of Skikda in the north-east of Algeria, and add it, as sand in the composition of sand concrete. To carry out this research, we analyzed the evolution brought by the substitution of ordinary sand by marble waste sand, with 25%, 50%, 75% and 100% on the properties in the fresh state (density, workability and air content) and in the cured state (compressive strength, tensile strength, surface hardness and sound velocity). For durability we tested water absorption by immersion and chloride penetration. The results obtained are compared with control samples of 0% of substitution rate. In order to have a good filling of the voids in the granular skeleton; we added a quantity of limestone recycled fines from the quarries and for a good workability a super-plasticizing additive. The results showed that the partial substitution modified both the fresh and the hardened characteristics of the tested concretes, the durability parameters also improved.

• Archives of Plastic Surgery
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• v.35 no.6
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• pp.723-728
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• 2008

Purpose: The disinsertion of the phalangeal tendon distal insertion has difficulties in ordinary tenorrhaphy operation for the anatomical features, and still has controversy between non-surgical and surgical management. The purpose of this study is to select treatment for the injury of the phalangeal tendon distal insertion, as we've had a good results from operation treatment with Pull-in suture technique. Methods: We reviewed the hospital records of 12 patients treated with Pull-in suture technique with disinsertion of the phalangeal extensor or flexor tendon distal insertion from June 2006 to June 2007. Eight patients were involved with the tendon disinsertion without bone fracture, and 4 patients were involved with the fracture of the phalangeal tendon distal insertion site. After removal of the K-wire in week 6, active physical exercises were commenced immediately. The mean follow-up period was 12.4 months. Results: All the patients who had tendon disinsertion with bone fracture had IIB, by Wehbe and Schneider's classification 2, and we evaluated the results comparing the same finger of the other hand according to Crawford's evaluation criteria 5. The nine excellent and three good results were obtained and there were no limitation of motor for the patient who had operation for the rupture of flexor tendon as well. There were no particular complications during the follow-up period. Conclusion: The most important thing for the disinsertion of the phalangeal tendon distal insertion is to maintain an accurate and durable reduction state keeping the tension of tendon. At this point, after removal of the K-wire, the Pull-in suture technique allows accurate realignment of the tendon-bone unit without any specific instrumentation under the more stable state. The Pull-in suture technique seems to be a strong alternative for the treatment of disinsertion of the phalangeal tendon distal insertion, with successful treatment outcome(rapid functional recovery and high patient satisfaction).

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.457-465
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• 2007

In this paper, polymer-modified repair materials using polymer dispersions with six repair methods are prepared with various polymer-cement ratios, and tested for compressive and flexural strengths through each curing condition such as dry cure, water cure, and freezing and thawing cyclic action. And, the adhesive interface between the polymer-modified mortar and mortar substrate is observed by a scanning electron microscope. From the test results, the compressive and flexural strengths of cement mortar repaired by polymer-modified mortar are improved with a rise in the polymer-cement ratio regardless of the type of polymer and curing conditions. Such an improvement in the strengths of polymer-modified repair materials to ordinary cement mortar is explained by the high adhesion of polymer-modified mortar. Strength reduction of polymer-modified repair materials after freezing and thawing cyclic actions is recognized, but it is lower than that of unmodified mortar. Especially, cement mortar repaired by polymer-modified mortar with a St/BA emulsion has good strength properties compared with those of SBR latex and PA emulsion. Accordingly, it is judged that polymer-modified mortars with a St/BA emulsion are possible to use as repair materials to ordinary cement mortar and concrete.

• Advances in concrete construction
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• v.6 no.6
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• pp.561-583
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• 2018

A variety of polycarboxylate ether (PCE)-based superplasticizers are commercially available. Their influence on the rheological retention and slump loss in respect of concrete differ considerably. Fluidity and slump loss are the cardinal features responsible for the quality of concrete. These are related to the dispersion of cement particles and the hydration process which are greatly influenced by type of polycarboxylate ether (PCE)-based superplasticizers. On the backdrop of relatively less studies in the context of rheological retention of high strength self-consolidating concrete (HS-SCC), the experimental investigations were carried out aiming at quantifying the effect of the six different PCE polymers (PCE 1-6) on the rheological retention of HS-SCC mixes containing two types of Ordinary Portland Cements (OPC) and unwashed crushed sand as the fine aggregate. The tests that were carried out included $T_{500}$, V-Funnel, yield stress and viscosity retention tests. The supplementary cementitious materials such as fly ash (FA) and micro-silica (MS) were also used in ternary blend keeping the mix paste volume and flow of concrete constant. Low water to binder ratio was used. The results reveal that not only the PCEs of different polymer groups behave differently, but even the PCEs of same polymer groups also behave differently. The study also indicates that the HS-SCC mixes containing PCE 6 and PCE 5 performed better as compared to the mixes containing PCE 1, PCE 2, PCE 3 and PCE 4 in respect of all the rheological tests. The PCE 6 is a new class of chemical admixtures known as Polyaryl Ether (PAE) developed by BASF to provide better rheological properties in even in HS-SCC mixes at low water to binder mix. In the present study, the PCE 6, is found to help not only in reduction in the plastic viscosity and yield stress, but also provide good rheological retention over the period of 180 minutes. Further, the early compressive strength properties (one day compressive strength) highly depend on the type of PCE polymer. The side chain length of PCE polymer and the fineness of the cement considerably affect the early strength gain.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.39-40
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• 2010

The demands for longer span and reduction of story height have greatly increased as building structures become much larger and higher in recent years. Although the development of flexural members for reducing story height or making long span has been studied by many researchers and engineers, there is still a lack of efficient systems that meet these two demands simultaneously. This study aimed at developing a new composite beam system suitable for long span and reduction of story height, and proposed a prestressed composite beam with corrugated web. It has great resistance against non-symmetric construction load due to its strong out-of-plane shear strength with relatively small member height as well as good constructability and economic efficiency by removing/minimizing form work. The corrugated webs also make accordion effect introducing larger effective prestressing force to top and bottom flanges, which causes larger upward camber reducing the member deflection. Five full-scale specimens with key test parameters, which are web sectional shapes and number of drape points, were tested to understand their flexural behavior and to verify the performance of the proposed method. The experimental test results showed that the proposed prestressed composite beam had greater flexural strength and stiffness than the ordinary non-prestressed composite beam.

• Magazine of the Korean Society of Agricultural Engineers
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• v.10 no.2
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• pp.1443-1453
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• 1968

The reservoir is one of the important partsof facilities for development of irrigation water in Korea. Accordingly, construction of the reservoir will be stressed in the field of future development of agricultural water resources. In the meantime, storage capacity is actually is limited to some extent with various conditions. Acreage of benefited area shall be determined according to such conditions as catchment area, precipitation and unit water requirment within benefited area. According to results of the past construction of the reservoir, the ratio of catchment area to benefited area would be 4:1 to 2.5:1 or catchment area is approximately 2.5 times larger and over than benefited area. In order words, it is the ordinary practice in the construction of reservoir that benefited area should be less than 1/2.5 times as large as catchment area. Moreover, limitation of catchment area would prevent largely the vast drought-stricken area from being benefited by irrigation facilites. This has been, in fact, caused by the fact that a good deal of water stored in the reservoir overflows wastefully through spillway of the reservoir at th time of flood season, and that only very little of the overflowed water is available for irrigation. However, if the more wasted water is stored during the flood season, the larger area of farmland can irrigated. That is, catchment area can reduced to less than 2.5 times as large as benefited area. On the other hand, it is afraid that such reduction should bring about the increase of unit storage capacity. And storage capacity being maximized, costs for construction of the reservoir will be raised too highly, thus making the economics feasibility unfavorable. The purpose of this study is to decide the ratio of catchment area to benefited area toward the minimum level as possible in consideration of the hydrological and economic aspects. Kopung Project which is located in Sosan-kun, Chungnam Province is taken as an example for the review and analysis in this study, and as an example for crop, rice is taken. After consideration of this project, we can find out that annual average inflow is 726mm and annual average water requirements is 811mm. And the ratio of catchment area to benefited area is 1.2:1. This means that catchment area can be reduced even to 1.2 times as large as benefited area. In conclusion, this study reveals that the construction of reservoir is feasible in view of economic and technical points provided that catchment area is more than 1.5 times as large as benefited area.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.131-138
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• 2010

This research intends to analyze the basic characteristics of cements(hereinafter "CC") with affordable price and particle distribution effective as hydration heat face which are discharged at the outlet of smashing process of ordinary portland cement(hereinafter "OPC") manufacturing process such as fluidity, rigidity, temporary insulation temperature increase amount etc to review the potential of developing "CC" to 3 ingredients low heat cement that substitutes fly ash and blast furnace slag(hereinafter "BS"). As a result of experiment, fluidity tended to decrease with increase in CC substitution rate, and increase with increase in FA+BS substitution rate. Air amount tended to slightly decrease with increase in CC substitution rate, and decrease with increase in FA+BS substitution rate. Condensation characteristics were such that condensation time was delayed with increase in CC and FA+BS substitution rate. As for the temperature rising amount by temporary insulation, peak temperature decreased with increase in CC substitution rate and increase in FA+BS substitution rate in general, and thereafter, temperature tended to decrease slowly. Compressive strength decreased with increase in CC and FA+BS substitution rate, and as aging goes on, long term strength was equivalent to plain or higher. By and large, when FA+BS was substituted to CC, fluidity and air amount tended to decrease, but hydration heat face showed good reduction effects, suggesting possibility of development to 3 ingredients low heat cement.

• The Korean Journal of Air & Space Law and Policy
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• v.20 no.1
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• pp.211-253
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• 2005

Recently, the Korean Supreme Court released two important decisions concerning damages for the pain and suffering from Aircraft noise. The local people who are living near the Air Force practice site at Maehyang-ri and the Kimpo International Airport brought lawsuits against the Korean government requesting damages for their financial loss from the severe noise and the damages for their pain and suffering. Plaintiffs alleged that they suffered physical malfunctions, extreme disturbances and the reduction of property values from the extreme noises which were daily repeated. District Court of Seoul Province did not allow plaintiffs all but the damages for pain and suffering. Plaintiffs could not prove the causation between their financial loss and the noise. The Supreme Court confirmed the lower court's decision. Article V of the National Compensation Act (analogous to the Federal Tort Claims Act of the USA) reads, "the government shall be liable for any loss caused by the defect on establishment or maintenance of public facilities." In the two cases, the major issue was whether the government's establishment or maintenance of Air Force practice site and the airport was defective because they caused serious noise to surrounding neighbors. Previously, the Supreme Court interpreted the clause "defect on establishment or maintenance of public facilities" as failure of duty to provide safety measures to the degree generally required to ordinary manager. However the Court at this time interpreted differently that the defect could be found if the facility caused to any person loss to the degree intolerable. In the two cases the Court confirmed the lower court's finding that noise level at the site was severe enough to be intolerable. This standard is based on the severity of the loss rather than the failure of duty. It became easier for plaintiffs to prove the cause of action under this interpretation. The consequence of the ruling of these two cases is 'rush to the courtroom' by the local people at similar situations. The ruling of these two cases was not appropriate both in theory and in consequence. The Korean tort system is basically based on the theory of negligence. Strict liability is exceptional only when there is special legislation. The Court created strict liability rule by interpreting the Art. V of the National Compensation Act. This is against the proper role of the court. The result of the cases is also dismal. The government was already sued by a number of local people for damages. Especially the Department of Defense which is operating many airports nationwide has financial hardship, which will cause downsizing military practice by the Air Force in the long run, This is no good to anyone. Tens of millions of dollars which might be used for compensation might be better used to prevent further noise problem surrounding airports.