• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.753-760
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• 2007

For protection of the cylinder wall of the ball mill for grinding raw ore. the inner side of the cylinder is covered with rubber liner. The rubber is easily worn down because the rubber relatively soft compared with raw ore. So the rubber liner in the ball mill cylinder must be replaced almost every year and the cost for replacing rubber liner formidable. In this paper, for reducing or excluding the cost of replacing rubber liner the basalt liner is designed. The basalt materials are generally harder than raw ore and the basalt liner in the ball mill does not wear down and so it can be used almost permanently. The concave surfaces are made on the liner of the ball mill and the liner in the cylinder wall plays also the role of raising the steel balls mixed in the raw ore. The section profiles of the concave surface have an important effect on the performance of the ball mill. The deep concave grooves raise the steel balls to high levels and give the large potential energy to the steel balls impacting to the raw ore. But if the concave grooves are too deep. the steel balls raised too high by the concave grooves fly along the parabolic path and reach to the other side of cylinder wall and so the steel balls do not play the roles of grinding the raw ore. The forces acting to a steel ball in a concave groove of the cylinder liner are also analyzed in this paper. The formulas calculating the height and the impact point of the steel ball are introduced and presented. Based to these formulas, the optimum section profiles of the basalt liner are presented.

• Steel and Composite Structures
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• 제44권3호
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• pp.423-436
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• 2022

This paper proposes an innovative thin-walled square concrete filled steel tubular (CFST) column with an octagonal/circular lining steel tube, in which the outer steel tube and the inner liner are fabricated independently of each other and connected by slot-weld or self-tapping screw connections. Twelve thin-walled square CFST columns were tested under quasi-static loading, considering the parameters of liner type, connection type between the square tube and liner, yield strength of steel tube, and the axial load ratio. The seismic performance of the thin-walled square CFST columns is effectively improved by the octagonal and circular liners, and all the liner-stiffened specimens showed an excellent ductile behavior with the ultimate draft ratios being much larger than 1/50 and the ductility coefficients being generally higher than 4.0. The energy dissipation abilities of the specimens with circular liners and self-tapping screw connections were superior to those with octagonal liner and slot-weld connections. Based on the test results, both the finite element (FE) and simplified theoretical models were established, considering the post-buckling strength of the thin-walled square steel tube and the confinement effect of the liners, and the proposed models well predicted the hysteretic behavior of the liner-stiffened specimens.

• 한국지반환경공학회 논문집
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• 제12권12호
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• pp.13-20
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• 2011

외수압에 의한 강관 라이닝 좌굴 사례를 조사, 평가하여 강관 라이닝의 안전성에 미치는 요소 및 그 중요도를 산정하고자 하였다. 대상터널은 ${\bigcirc}{\bigcirc}$광역상수도 도수시설인 직경 2m의 수로터널로서 터널 라이닝은 내부의 강관 라이닝과 배면의 뒷채움 콘크리트로 구성되어 있다. 두 개의 수로터널에서 발생된 강관 라이닝 좌굴 손상을 대상으로 손상의 형태 및 설계 조건을 상세하게 조사하였다. 좌굴 손상에 적용 가능한 좌굴 안전성 평가방법을 기존의 문헌 자료를 참조하여 선정하였으며, 손상에 대한 조사결과와 비교하였다. 또한 본 지역의 수리지질학적인 특성이 좌굴 손상에 미치는 영향을 검토하였다. 연구결과 수리지질학적 지층특성뿐만 아니라 터널 라이닝의 적절한 시공이 강관 라이닝의 좌굴에 영향을 미치는 중요한 요소이며, 외수압의 크기 결정은 수리지질 특성에 따라 산정되어야 하는 것을 알 수 있었다. 기존 손상 사례에 대한 연구는 압력 수로터널의 강관 라이닝에 대한 설계, 시공 및 유지관리 기간 중의 문제점 및 개선사항을 도출하는데 활용될 수 있을 것이다.

• Steel and Composite Structures
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• 제35권2호
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• pp.171-186
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• 2020

This paper aims at providing insights on the use of thermosetting liner for the repair of offshore pipelines exposed to corrosion and leakage. The work which covers both experimental and numerical approaches were aspired due to the high cost of repair for pipelines, limitations of thermoplastic material and limited study of reinforced thermosetting liner. The experiment involves a destruction test called the burst test, carried out on an API 5L X42 carbon steel pipe under four case studies, namely (i) intact pipe, (ii) pipe with corrosion defect, (iii) pipe with corrosion defect and repaired with thermosetting liner and (iv) pipe with leakage and repaired with thermosetting liner. The numerical simulation was developed to first validate the experimental results and later to optimize the design of the thermosetting liner in terms of the number of layers required to restore the original strength of the pipe. The burst test shows an improvement in 23% of the burst capacity for the pipe with corrosion defects, after being repaired with a three-layer thermosetting liner. The parametric studies conducted showed that with an addition of thermosetting layers, the burst capacity improves by an average of 1.85 MPa. In conclusions, the improvement in strength can be further increased with increasing thickness of the thermosetting liner. The thermosetting liner was also determined to fail first inside the host pipe.

• 터널과지하공간
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• 제13권3호
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• pp.225-234
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• 2003

구조물의 해체 대상이 철근 콘크리트에서부터 강구조물에 이르기까지 다양화되고 있다. 이러한 강 구조물의 해체는 최근 국내에서도 증가추세이다. 강 구조물을 해체하는데 이용되는 가소성 성형 폭약의 경우 그 대부분이 외국에서 수입되는 실정이다. 따라서 본 연구에서는 가소성 성형폭약의 국산 개발을 위해 최적 설계 변수설정을 위한 연구를 수행하였는데 그 주요 결과는 다음과 같다. 라이너 재질로는 알루미늄이나 납보다는 구리가 우수하고 그 굽힘각도는 45$^{\circ}$, 60$^{\circ}$, 120$^{\circ}$보다 90$^{\circ}$일 때 가장 좋은 결과를 얻을 수 있었다. 이외에도 폭약량에 따른 라이너의 두께, 최적이격거리등을 검토하였으며 폭약 및 라이너는 가소화시켜 해체 대상 강 구조물의 형태에 따라 결합력을 증대시키는 것이 효과적이다.

• 한국터널지하공간학회 논문집
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• 제14권2호
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• pp.131-139
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• 2012

본 연구에서는 도심지 소구경 터널굴착공법에서 파형강판으로 제작된 liner plate의 거동특성에 대해 알아보기 위해 유한요소 해석 프로그램인 MIDAS/GTS를 이용하여 수치해석을 실시하였다. 토피고 변화에 따라 liner plate의 거동특성을 알아보기 위해 토피고는 5 m, 10 m, 15 m, 20 m, 25 m 5가지 각 조건으로 해석을 실시하였다. 수치해석결과 liner plate의 최대변위와 최대축응력은 부재의 하단부에서 발생되며, 최대전단응력의 경우 부재의 천단부에서 발생되는 것으로 확인되었다. 또한 토피고에 따른 liner plate의 변위, 응력, 전단응력의 변화는 있었으나 그 차이가 미미하고 토피고가 증가함에 따라 점점 구조적 안정성이 확보되는 것으로 판단된다.

• Journal of Welding and Joining
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• 제32권5호
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• pp.65-71
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• 2014

Atmospheric plasma spraying (APS) is world-widely used process in the automotive industry as a method to provide wear resistance coatings for engine cylinder bore, using various materials. The weight of engine blocks can be considerably decreased by removing cast iron liners, which can finally result in the improvement of fuel efficiency. In this study, five kinds of powder materials, 1.2C steel powder and 1.2C steel powder mixed with 5, 10, 15, 20 wt.%. molybdenum powder, were deposited by atmospheric plasma spraying in order to investigate the effect of molybdenum on the wear resistance of coatings. Microstructural analysis showed that molybdenum splats were well distributed in 1.2C steel matrix with intimate bonding. The molybdenum added coatings showed better tribological properties than 1.2C steel coating. However, above the 15 wt.%. blending fraction, wear resistance was somewhat degraded with poor roughness of worn surface due to the brittle fracture occurred in molybdenum splats. Consequently, compared to conventional liner material, gray cast iron, 10 wt. pct. molybdenum blended 1.2C steel coating showed much better tribological properties and therefore it looks very feasible to replace gray cast iron liner.

• 대한기계학회논문집A
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• 제21권6호
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• pp.884-895
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• 1997

The finite element analysis for the tubular alumina liner which was shrink-fitted into a heat treated high speed steel (HSS) sleeve and subjected to high inner pressure and high temperature was performed. The parameters for the analysis were the interference between the alumina and the HSS, the temperature, the inner pressure, the coefficient of friction between the alumina and the HSS, and the taper at the sleeve ends. From the analysis, it was found that the tensile hoop stresses were decreased when the end parts of the HSS sleeve were tapered and the tensile stresses were decreased as the coefficient of friction between the alumina and the HSS was decreased. Also it was found that the alumina might be used as the structural liner for high pressure and high temperature when it was shrink-fitted into a heat treated HSS sleeve.

• 한국해양공학회지
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• 제14권3호
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• pp.72-77
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• 2000

In this paper, the effect of ground improvement and the countermeasure for the increase of strength in soft ground (wasted fill, marine clay) was studied through utilization of Soilcrete Cement as a material of ground improvement. Soil samples were obtained from $\bigcirc$$\bigcirc$$\bigcirc$ sanitary landfill to assess the applicability of the clay liner using Soilcrete Cement. Several laboratory tests were performed with the samples and skin corrosion tests of steel pipe covered with Soilcrete Cement were performed. As a result, Soilcrete Cement is considered to be applicable to the construction site and to be effective for the prevention of the corrosion of the steel pipe.

• 한국압력기기공학회 논문집
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• 제15권1호
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• pp.46-52
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• 2019

This work proposes a noncontact ultrasonic transducer for detecting wall-thinning of containment liner plates of nuclear power plants by measuring their thickness without physical contact. Because the containment liner plate is designed to prevent atmospheric leakage of radioactive substances under severe nuclear accident, its wall-thinning inspection is important for safety of nuclear power plants. Wall-thinning investigation of containment liner plates have been carried out by measuring their thickness with contact-type ultrasonic thickness gauge by inspectors and needs a lot of time and cost. As an alternative, an electromagnetic acoustic transducer measuring precisely thickness of containment liner plates without any physical contact or couplant was suggested in this research. A transducer generating and measuring shear ultrasonic waves in thickness direction was designed and wave field produced by the transducer was analyzed to verify the design. The working performance of the suggested transducer was tested with carbon steel plate specimens with various thicknesses. The test result shows that the proposed transducer can measure thickness of the specimens precisely without any couplant and implies that swift scanning of wall-thinning of containment liner plates will be possible with the proposed transducer.