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이경동 ( Kyeong-dong Lee ),유찬서 ( Chan-seo You ),라덕관 ( Deog-gwan Ra ) 한국환경기술학회 2009 한국환경기술학회지 Vol.10 No.1
철도 건설공사 주변지역의 지하수 오염실태를 분석하기 위하여 지표수질 4개소, 지하수질 6개소에 대하여 수질을 분석하였다. 지표수질 조사 결과, SW-1지점은 pH 7.0∼7.5, BOD 3.3∼7.5 mg/L, SS 6.0∼16.0 mg/L, DO 2.9∼8.6 mg/L, SW-2지점은 pH 7.6∼7.8, BOD 2.2∼16.0 mg/L, SS 9.0∼22.0 mg/L, DO 5.0∼8.2 mg/L, SW-3지점은 pH 7.5∼8.2, BOD 3.6∼8.4 mg/L, SS 15.0∼32.0 mg/L, DO 5.2∼11.2 mg/L, SW-4지점은 pH 8.5∼10.4, BOD 10.2∼44.0 mg/L, SS 13.0∼45.0mg/L, DO 6.1∼9.1 mg/L로 조사되었다. 지하수질 조사 결과, GW-1과 GW-4지점이 색도 기준치를 초과하였고, 전체 조사지점에서 1회이상 일반세균 기준치를 초과하였으며, 질산성질소가 기준치를 초과한 GW-3지점의 지하수를 음용수나 생활용수로 사용할 경우에는 문제가 야기될 수도 있으므로 주의를 요한다. In order to estimate the environmental pollution on railroad construction area, several water samples, 4 points for surface water and 6 points for ground water, were analyzed. The surveyed results on surface water quality were shown as below; pH 7.0∼7.5, BOD 3.3∼7.5 mg/L, SS 6.0∼16.0 mg/L, DO 2.9∼8.6 mg/L for SW-1 site, pH 7.6∼7.8, BOD 2.2∼16.0 mg/L, SS 9.0∼22.0 mg/L, DO 5.0∼8.2 mg/L for SW-2 site, pH 7.5∼8.2, BOD 3.6∼8.4 mg/L, SS 15.0∼32.0 mg/L, DO 5.2∼11.2 mg/L for SW-3 site, pH 8.5∼ 10.4, BOD 10.2∼44.0 mg/L, SS 13.0∼45.0 mg/L, DO 6.1∼9.1 mg/L for SW-4 site. In the meantime, on the survey of ground water quality for 6 points, the color for GW-1 and GW-4 sites were not satisfied the criterion. Additionally the number of total colony count was exceeded the criterion more once on each site respectively. Especially the ground water for GW-3 site was demanded some care in using as drinking or living water, due to the exceeded nitrate concentration against to its criterion.
Polystyrene Beads를 이용한 경량콘크리트의 강도특성에 관한 실험적 연구
이경동 ( Lee¸ Kyeong-dong ),한재익 ( Han¸ Jae-ik ) 한국구조물진단유지관리공학회 1999 한국구조물진단유지관리공학회 논문집 Vol.3 No.2
Recently, the study on mix design of lightweight concrete using the polystyrene foam balls is put into practice from the viewpoint to grade up the quality of concrete and recyclable usage of industrial by products. Polystyrene aggregate concrete, PAC, can be used as structural concrete in low strength application. For instance, PAC could be used in the middle part of sandwich panel where stresses are generally low and in the case of grid-type reinforcement where it does not need high bond strength but little compressive strength to resist the pressure of transverse reinforcement. From this point of view, the authors discussed the influence of fluidity and compressive strength of concrete by the difference of the volume percentage of polystyrene foam balls and water cement ratio.
피라미드형 전단열결재를 갖는 합성보의 변형거동과 S-N 곡선
이경동(Kyeong Dong Lee),곽기주(Kee Ju Kwak) 한국강구조학회 1995 韓國鋼構造學會誌 Vol.7 No.3
A steel plate-concrete composite slab system has been widely used in place of conventional reinforced concrete slabs for the reason that they have various advantages such as structural performance, safety and reduction of time and labors in field construction. In this paper, a series of bending fatigue tests was carried out on several types of PSC beams under various cross-sections and loading conditions. The results are as follows : (1) the fatigue failure of PSC beams results from the tensile fracture of bottom steel plate, and (2) fatigue strength of the plate for two million cycles can be estimated at 940kgf/㎠ from the S-N curves.
곽기주 ( Kwak Kee Ju ),이경동 ( Lee Kyeong Dong ),곽동림 ( Kwak Dong Lim ) 한국농공학회 1997 韓國農工學會誌 : 전원과 자원 Vol.39 No.1
An experimental study of the application of Silica fume for the high strength concrete was conducted. Nine specimens with three different contents of silica fume, 0%, 10%, 20% and with three water-cement ratio 30%, 40%, 50% were tested. Results shows that 10% of silica fume and 30% of water-cement ratio has a maximum strength with 700kg/cm<sup>2</sup> of compressive strength and 64kg/cm<sup>2</sup> of splitting tensile strength and 100kg/cm<sup>2</sup> of flexural strength. Slump value of the tested samples decreases with increasing water-cement ratio and elapsed time of silica fume. Splitting tensile strength(□□)and flexural strength(□□)and static modulus of elasticity(E) can be correlated with compressive strength(□□)from a regression analysis.
안호근 ( Ahn Ho-geun ),이경동 ( Lee Kyeong-dong ),정운조 ( Jeong Woon-jo ) 한국환경기술학회 2001 한국환경기술학회지 Vol.2 No.2
건축물에 사용되는 많은 양의 철근이 유통과정에서 자연산화에 의해 부식되어 폐기된다. 폐 철근의 재활용을 위하여 shot blaster로 처리한 다음 PVC, ABS, PB 및 PS계 폴리머를 도포하고, 도포철근의 기계적 강도, 부착강도 및 부식정도를 측정하여 신철근과 비교하였다. 폴리머 도포 철근의 기계적 강도는 신철근의 값과 유사하였다. ABS와 HIPS와 같은 PS계로 도포한 철근의 부착강도는 신철근보다 강하였고, PB와 PVC의 경우는 크게 감소함을 보였다. 도포철근의 처리온도에 따른 부착강도는 적어도 70℃까지 거의 동일하게 나타났다. 내부식성에 있어서 신철근은 42일 경과 후 물에 의해 심하게 부식되었으나, ABS 도포철근은 내부식성이 크게 향상되어 42일 경과하여도 철근표면에 전혀 변화가 없었다. 결과적으로 ABS 도포철근은 콘크리트 보강용 철근으로 재활용될 수 있음을 알았다. A great deal of steel bar has been spent because of the surface corrosion by natural oxidation in-course of the distribution. In order to reutilize the waste steel bar, polymer such as PVC, ABS, PB, and PS was coated on its surface after treating it with shot blaster. Mechanical property of the polymer-coated steel bar, adhesive strength, and corrosion state were investigated. Mechanical property of coated steel bar was similar to that of new steel bar. Adhesive strength of steel bar coated with ABS or HIPS was increased, but that of steel bar coated with PB or PVC was decreased.. Adhesive strength of the steel bar was nearly constant although it was thermally treated at 70°C. Also, new steel bar was easily oxidized under air atmosphere of 42 days after water showering, whereas the surface of ABS-coated steel bar was not changed at all due to remarkable enhancement of anti-corrosion property. It was, as a result, considered that ABS-coated steel bar could be reutilized in construction industry.
피라미드형 뒤벨을 갖는 강판·콘크리트 합성보의 피로강도
이재영(Jae Young Lee),양승현(Seung Hyoun Yang),이경동(Kyeong Dong Lee) 한국강구조학회 1993 韓國鋼構造學會誌 Vol.5 No.3
A steel plate-concrete composite slab with pyramidal shear connectors, named PSC composite slab, is expected to have sufficient bending strength and flexural rigidity for loads during and after construction. Fatigue problems play an important role in designing composite slab as bridge decks under traffic conditions. In this paper, a series of fatigue tests were carried out on several types of PSC beams under welding and loading conditions. The results are as follows : (1) the fatigue failure of PSC beams results from the tensile fracture of bottom steel plate, and (2) fatigue strength of the plate for two million cycles can be estimated at 1156㎏/㎠ from the S-N curves.