• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.127-132
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• 1996

Recently in the country a corrosion of steel is accelerated due to using of sea sand including salts, and critical problem on the durability of concrete structure is occured. Thus a control of steel corrosion is very important in the stability of structure. Coated steel is in use with a method of steps of steel corrosion in U.S,A. Japan etc, and as well in domestic case the manufactured coating steel of three types is on the market. Those are Epoxy coated steel, Zinc-strength, concrete specimen size, bar diameter, which can affect bond characteristics between steel and concrete in order to know their relative bond characteristics.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.449-452
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• 2004

The lap splice lengths of deformed steel reinforcing bars and GFRP bars with two different to surface type were experimentally compared using beam specimens. The purpose was to evaluate the length required of the GFRP bar to develop strength equivalent to the conventional steel reinforcing bar. The main test variable was the lap splice length. Two different GFRP bar surfaces were tested: (1) spiral-type GFRP bars and (2) sand coated GFRP bars. For the conventional steel bars (SD400 grade), strength over 400 MPa in tension was reached using the lap splice length of $30d_b$. Splice failure was observed in the specimen with the lap splice length of $20d_b$. For the spiral-type and sand coated GFRP bars, the tensile strength developed in the GFRP bars decreased with decreasing splice lengths. Development of the cracks on beam surfaces was clearly visible for the beams reinforced with the GFRP bars. Mid-span deflections, however, were significantly smaller than the comparable beams with conventional steel bars indicating potential ductility problem.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권1호
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• pp.104-110
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• 2016

The transport of silver nanoparticles (AgNPs) was investigated through a column packed with sand. A series of column experiments were carried out to evaluate the effect of ionic strength (IS), pH, electrolyte type and clay mineral on mobility of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs). The deposition of PVP-AgNPs was increased with increasing solution ionic strength and decreasing pH. Furthermore, the depositon of PVP-AgNPs was affected by the electrolyte type (NaCl vs. NaNO₃) and was shown to be greater at NaNO₃ solution. Also, the transport of PVP-AgNPs was greatly increased after the pre-deposition of clay particles on sand. Our results suggest that various environmental factors can influence the mobility of PVP-AgNPs in soil-groundwater systems and should be carefully considered in assessing their environmental risks.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.419-426
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• 2000

The purpose of this study is to present the application of WFS co-mixtures for retaining wall as flowable backfill. The fly ash, generated at the Tae-An thermoelectric power plant, was used in this research and was classified as Class F. Green Sand, Furane Sand, and Coated Sand, which had been used at a foundry located in Pusan, were used. Couple of laboratory tests and small scale retaining wall tests were performed to obtain the physical properties of the WFS co-mixtures and the possibility of backfill materials of retaining wall. The range of permeability for all the co-mixtures was from 3.0${\times}$10$\^$-3/ cm/s to 6.0${\times}$10$\^$-5/ cm/s. The unconfined strength of the 28-day cured specimens reached around 550kPa. Results of the consolidated-undrained triaxial test showed that the internal friction angle is between 33.5$^{\circ}$ and 41.8$^{\circ}$. The lateral earth pressure against wall decreased up to 80% of initial pressure within a 12 hours and the total lateral earth pressure is less than that of typical granular soil. It was enough to construct the backfill for the standard retaining of 6m with just two steps, like fill the co-mixtures for half of retaining wall, and then fill the others after 1 day. The stability of retaining wall for overturning and sliding increased as the curing time elapsed.

• 대한환경공학회지
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• 제28권5호
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• pp.558-562
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• 2006

여과공정에서 망간제거특성을 고찰하기 위하여 모래, 망간사 등의 4가지 여재를 사용한 여과실험이 실시되었다. 여과속도는 123 m/d였고, 칼럼당 유입량은 $3.9m^3/d$이었다. 실험기간은 약 1년이었으며, 실험기간 동안 여재별로 이산화망간 부착량, 탁도제거율, 망간제거율, 유기물제거율 등을 고찰하였다. 평균 망간농도 0.208 mg/L의 여과지 유입수(잔류염소 1.0 mg/L)를 사용하여 여과실험한 결과 모래+망간사 칼럼은 98.9%, 망간사칼럼은 99.2%의 망간제거율을 보였다. 기존 모래여과지를 망간제거를 위해 사용할 경우 여층의 전부를 망간사로 교체하지 않고 일부만 교체하여도 망간제거에 충분한 효과가 나타나는 것으로 조사되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제17권2호
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• pp.117-123
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• 2013

원형 구조물의 보수/보강 및 FRP를 구조부재로 활용한 신설 구조물 시공을 위해서는 일정한 곡률반경을 갖는 곡면 FRP 부재가 요구된다. 그러나 현재까지 FRP 곡면부재는 수작업 (hand-lay-up) 또는 필라멘트 와인딩 (filament winding) 작업에 의해서만 생산이 가능하였으며, 대량 연속생산에는 한계가 있다. 또한 일반적으로 인발성형법 (pultrusion method)으로 생산된 FRP 부재가 상대적으로 물리적 특성이 우수한 것으로 알려져 있다. 따라서 FRP 부재를 일정곡률을 유지하며 인발로 뽑아낼 수 있는 신개념의 곡면 FRP 부재 인발성형법 제안 및 성형장비를 개발, 곡면 FRP 제품을 생산하였으며, 본 연구에서는 곡면 FRP 부재를 이용한 구조물 보수/보강시 야기될 수 있는 FRP와 콘크리트 부착면의 동결융해 영향을 분석하였다.

• Journal of Periodontal and Implant Science
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• 제41권5호
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• pp.242-247
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• 2011

Purpose: The purpose of this study was to characterize the osseointegration of the fibronectin-coated implant surface. Methods: Sand-blasted, large-grit, acid-etched (SLA) surface implants, with or without a thin calcium phosphate and fibronectin coating, were placed in edentulous mandibles of dogs 8 weeks after extraction. All dogs were sacrificed forhistological and histomorphometric evaluation after 4- and 8-week healing periods. Results: All types of implants were clinically stable without any mobility. Although the bone-to-implant contact and bone density of the SLA implants coated with calcium phosphate (CaP)/fibronectin were lower than the uncoated SLA implants, there were no significant differences between the uncoated SLA surface group and the SLA surface coated with CaP/fibronectin group. Conclusions: Within the limits of this study, SLA surfaces coated with CaP/fibronectin were shown to have comparable bone-to-implant contact and bone density to uncoated SLA surfaces.

• 한국해양공학회지
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• 제13권2호통권32호
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• pp.108-115
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• 1999

To study measurement of coated steel corrosion in mortar, a transient electro-magnetic(TEM) method was adapted. The sensors were made of enamelled wire with diameter of 0.25mm(transmitter), 0.1mm(receiver) and the secondary electro motive force(EMF) was measured with SIROTEMIII. The sensors configuration was used as in loop configuration. After coated steels were corroded by the salt spray during 3, 7, 15, 25days, they were embedded in mortar which were made from sand : cement : water ratio of 2 : 1 :0.5. To investigate coated steel corrosion in mortar, the sensors were used. ( sensorl - $T_x$ : $4{\Omega}$, $R_x$ : $10{\Omega}$, $3{times}3cm$, sensor2 - $T_x$ : $8{\Omega}$, $R_x$ : $10{\Omega}$, $3{times}3cm$, sensor3 - $T_x$ : $4{\Omega}$, $R_x$ : $10{\Omega}$, $6{times}6cm$, sensor4 - $T_x$ : $8{\Omega}$, $R_x$ : $10{\Omega}$, $6{times}6cm$). The obtained results showed that the secondary EMF was decreased with specimens of 3, 7days corroded coationg steel in mortar and then increased with specccimens of 15, 25days corroded one. And it was confirmed that measurement of coated steel corrosion in mortar by a transient electro-magnetic(TEM) method is possible.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.195-196
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• 2006

Direct laser sintering (DLS) technology for the resign coated sand is one of attractive technologies to produce molds and cores for the foundry industry rapidly and cost effectively. The objective of this case study is to develop casting pilot models using computer simulation technology, DLS RP machine and industrial computed tomography. The proposed casting design was verified by the Z-Cast software in the fields of fluid flow and solidification during the casting process. Casting parts with aluminum alloy using the post-curing treated sand moulds and cores are accurate to dimension and defect free.

• 한국터널지하공간학회 논문집
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• 제13권3호
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• pp.277-289
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• 2011

본 연구에서는 압축력을 받는 터널 라이닝 부재 특성에 보다 부합된 조건에서 FRP-콘크리트 접촉면의 전단 저항력을 평가할 수 있는 새로운 시험법을 제안하였으며, 제안 시험법은 기존 시험방법에 비해 시험체 제작과 시험방법이 매우 용이하다. 제안된 시험법을 기반으로 FRP와 콘크리트 복합소재의 전단저항성능을 좌우하는 규사코팅의 최적조건을 도출하기 위한 매개변수 연구를 실시하였다. 다양한 시료에 대한 시험결과를 기존 연구결과와의 비교분석을 통하여 제안 시험법의 타당성을 보였으며, FRP부재와 콘크리트 접촉면의 전단저항을 극대화 시킬 수 있는 효과적인 규사입경 및 밀도에 대한 최적 조건을 제시하였다.