• Proceedings of the Korean Geotechical Society Conference
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• 1999.02a
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• pp.14-22
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• 1999

Daylight collapse have been occurred by about 6.$^{0}$ m deep at ground surface which connected to the ground surface and excessive overbreak have been occurred by the space and height of 3.$^1$~6.$^2$m at crown head part of the tunnel during tunnelling of lower-half part after completing upper-half part on tunnelling of a phyllite mountain by NATM method at the construction work of two way-double track national road. This study is a successful illustration case of earth improvement by confirming structural safety of the tunnel in a whole through solving the cause of the tunnel collapse and the work have completed successfully through applying such earth strengthening method as cement mortarㆍcement milk injection, S.G.R, steel pipe reinforced multi-step grouting etc.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2009.05a
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• pp.144-149
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• 2009

본 논문은 스틸 파이프 생산시 저불량율, 고수율을 가진 제품을 분류하고 모형화하기 위하여 과거 스틸 파이프 생산이력을 비교, 분석하여 주요 특성들이 불량율, 수율에 어떠한 영향을 미치는가를 파악함으로써 향후 스틸 파이프 생산 공정에서 저불량율, 고수율의 제품을 생산하는데 주요한 지표로 활용코자 하는데 그 목적이 있다. 과거 스틸 파이프 산업에 대한 주요 특성별 수율 측정에 대한 연구가 미흡하였으나, 본 논문에서 이를 구체화 하여 주요 특성별 불량률과 수율이 어떠한 형태를 나타내는지를 분류하고, 그 영향정도를 구분하고자 한다.

• Journal of Power System Engineering
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• v.20 no.4
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• pp.26-31
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• 2016

The implementation of chirplet transform to locate axially aligned defects in pipes has been investigated. The results are obtained from experiments performed on a carbon steel pipe using magnetostrictive sensors. Chirplet transform is applied to the reflected signal to separate the individual modes from dispersive and multimodal waveform. The separated modes are used to calculate reflection coefficients which would be used to characterize defects. It is found that the reflection from a defect consists of the wave pulses with gradually decaying amplitudes. Also the results show that the reflection coefficient initially increases with the crack length but finally reaches an oscillating regime.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.931-933
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• 1992

The static charges generated at the interface between the insulating oil and the solid materials, can be affected by impurities such as moisture. This paper investigated the charging tendency of clean oil and the oil with moisture in stainless steel pipe. The experimental results show that static electrification of the oil with moisture is smaller than that of the clean oil, and the oil is positively charged.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1106-1116
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• 1994

Leak Before Break(LBB) design concept is applied to piping systems of newly-built Yonggwang 3, 4 nuclear generating stations as a design alternative to the provision of pipe whip restraints, in recognition of the questionable benefits of providing such restraints. The objective of this paper is to evaluate the material properties (tensile and fracture toughness) of SA312 TP316 stainless steel and their associated welds manufactured for shutdown cooling system of Yonggwang 3, 4 nuclear generating stations. Effect of various parameters such as specimen orientation, test temperature, welding on material properties were examined.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.198-203
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• 1993

In this study, byusing EMAT(Electro Magnetic Acoustic Transducer) the artificial slit is installed on 12B-SUS pipe test piece. By mading 4 cycle SH-bust wave (EMA) incidence to 45 .deg. angle, the signaldata of pulse, which is recevied from EMAT translated intodigital-signal-processing-method SSP and Deconvolution method by using FACOM. Results of these indicated that (1) this method of this study shows exellent result more than Ultrasonic testing method; (2) noise is well removed by SSP using signal dataa and resolving power and S/N ratio are advanced; (3) regradless of Ultrasonic wave, whichhas properties of generalstainless steel is generated into multiscattering and reflection phenomena, the resolving power of more than two times is progressed by being translated into Decon-volution method; and (4) as addition-averaging-processing number is increaing, the resolving power and S/N ratio are improved and the satisfactory signal is obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.4
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• pp.324-331
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• 2014

The sensor configuration of the magnetostrictive guided wave system can be described as a single continuous transducing element which makes it difficult to separate the individual modes from the reflected signal. In this work we develop the mode decomposition technique employing chirplet transform based on the maximum likelihood estimation, which is able to separate the individual modes from dispersive and multimodal waveform measured with the magnetostrictive sensor, and estimate the time-frequency centers and individual energies of the reflection, which would be used to locate and characterize defects. Simulation results on a carbon steel pipe are presented, which show the accurate mode separation and more discernible time-frequency representation could become enabled using the proposed technique.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.125-128
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• 2002

The uplift capacity and displacement of an earth anchor for improving the wind resistance of the 1-2W type plastic film pipe on greenhouse was tested using the steel circular vertical earth anchor with various diameters and embedded depths (L) in dry sand. The diameter (B) of the model anchor is 90mm, 120mm, 150mm, respectively. The model tests were performed embedded depth ratios (L/B) ranging from $1{\sim}3$ in loose density. In the case of diameter 90mm, as the uplift loading increased, the uplift capacity also increased until the loading was reached to ultimate uplift capacity. After that, the uplift capacity was continually increased or decreased until the experiment was finished. In general, the ultimate uplift capacity was different depending upon the anchor diameter and embedded depth ratios.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.91-100
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• 2004

This study presents the development of a new aluminum seat frame for the commercial bus. Back moment and seat belt anchorage analysis of the conventional steel seat frame was conducted as a base model. Effective aluminum section dimensions for aluminum pipe were calculated from equivalent stiffness and equivalent weight study. Back moment and seat belt anchorage strength with the developed aluminum seat frame were compared to those of the base model. Additionally, to pass the fatigue test, shape modification of side frame assembly was conducted. From this study we could reduce the weight of seat frame more than 5 kg. And the current analysis model and procedure can provide useful informations in designing a new commercial car seat and can reduce the overall design cost and time.

• Journal of Powder Materials
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• v.4 no.4
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• pp.252-257
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• 1997

Cu-brazed layer between the sintered-cam(Fe-5Cr-lMo-0.5P-2.5C, wt%) and seamless steelpipe(0.25-0.35C, 0.3-1.0 Mn, bal Fe, wt%) in the camshaft shows a columnar structure of $\gamma$-phase growing from the steel pipe. Liquid phase sintered 60Fe-40Cu alloys are carburized to simulate the brazing process giving rise to the columnar growth. Liquid film migrations and columnar growth of $\gamma$-grains are observed in the carburized regions. The $\gamma$-grains grow in the same direction as the C-diffusion. Fe-solubility in the liquid of carburized region is higher than in the uncarburized by about 0.3 at%. The columnar growth is driven by the gradient of the supersaturated Fe-solute in the liquid between two adjacent $\gamma$-grains.