• 한국표면공학회지
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• 제45권3호
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• pp.106-110
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• 2012

Oblique angle deposition (OAD) is a physical vapor deposition where incident vapor flux arrives at non-normal angles. It has been known that tilting the substrate changes the properties of the film, which is thought to be a result of morphological change of the film. In this study, OAD has been applied to prepare single and multilayer TiN films by cathodic arc deposition. TiN films have been deposited on cold-rolled steel sheets and stainless steel sheet. The deposition angle as well as substrate temperature and substrate bias was changed to investigate their effects on the properties of TiN films. TiN films were analyzed by color difference meter, scanning electron microscopy, nanoindenter and x-ray diffraction. The color of TiN films was not much changed according to the deposition conditions. The slanted and zigzag structures were observed from the single and multilayer films. The relation between substrate tilting angle (${\alpha}$) and the growth column angle (${\beta}$) followed the equation of $tan{\alpha}=2tan{\beta}$. The indentation hardness of TiN films deposited by OAD was low compared with the ones prepared at normal angle. However, it has been found that $H^3/E^2$ ratio of 3-layer TiN films prepared at OAD condition was a little higher than the ones prepared at normal angle, which can confirm the robustness of prepared films.

• Tribology and Lubricants
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• 제34권6호
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• pp.241-246
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• 2018

This research addresses the improvement of tribo-systems, specifically regarding the reduction of friction and wear through tribo-coupling between tetrahedral amorphous carbon (ta-C) with different types of counterpart materials, namely bearing steel (SUJ2), tungsten carbide (WC), stainless steel (SUS304), and alumina ($Al_2O_3$). A second variable in this project is the utilization of different values of duct bias voltage in the deposition of the ta-C coating - 0, 5, 10, 15, and 20 V. The results of this research are expected to determine the optimum duct bias and best counter materials associated with ta-C to produce the lowest friction and wear. Results obtained reveal that the tribo-couple between the ta-C coating and SUJ2 balls produces the lowest friction coefficient and wear rate. In terms of duct bias changes, deposition using 5 V produces the most optimum tribological behavior with lowest friction and wear on the tribo-system. In contrast, the tribo-couple between ta-C with a WC ball causes penetration through the coating surface layer and hence high surface delamination. This study demonstrates that the most effective ta-C coating duct bias is 5 V associated with SUJ2 counter material to produce the lowest friction and wear.

• 대한금속재료학회지
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• 제47권12호
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• pp.834-841
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• 2009

A study on the welding of electrogalvanized TRIP (Transformation-Induced Plasticity) steels was done to compare the life of the electrode and the alloying phenomena on the electrode tip surface using singlephase AC and inverter-DC resistance welding processes. A longer life of the electrode (>200 welds) was achieved using the inverter-DC welding process. The tensile shear strength was higher in the electrode life test when welded with the inverter DC welding machine it maintained a higher value even when the welding nugget diameter was smaller than specified. When spot-welding was conducted using the single-phase AC welding process, a higher wear rate of the electrode was observed compared to that with the inverter-DC process. An alloying layer used to determine the rate of electrode growth showed differences in the metallurgical features of the surface alloying and Zn penetration depending on whether the single-phase AC process or the inverter-DC welding process was used. Moreover, changes in the dynamic resistance during the electrode life test were correlated with the electrode wear (or growth) rate.

• 한국분말재료학회지
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• 제31권3호
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• pp.220-225
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• 2024

Molten salt reactors represent a promising advancement in nuclear technology due to their potential for enhanced safety, higher efficiency, and reduced nuclear waste. However, the development of structural materials that can survive under severe corrosion environments is crucial. In the present work, pure Ni was deposited on the surface of 316H stainless steel using a directed energy deposition (DED) process. This study aimed to fabricate pure Ni alloy layers on an STS316H alloy substrate. It was observed that low laser power during the deposition of pure Ni on the STS316H substrate could induce stacking defects such as surface irregularities and internal voids, which were confirmed through photographic and SEM analyses. Additionally, the diffusion of Fe and Cr elements from the STS316H substrate into the Ni layers was observed to decrease with increasing Ni deposition height. Analysis of the composition of Cr and Fe components within the Ni deposition structures allows for the prediction of properties such as the corrosion resistance of Ni.

• KSTLE International Journal
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• 제2권2호
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• pp.138-141
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• 2001

Tribological behaviors of a borate of triethanolamine in water solution were evaluated using a four-ball wear tester. X-ray photoelectron spectroscopy (XPS) was employed to study tribochemical species on worn scars of steel balls. Results show that a thick deposit layer was produced on the worn scars, which came from the decomposition of the borate. The surface film on the worn scars was mostly consisted with H$_3$BO$_3$, B$_2$O$_3$and large amounts of ferricyanides.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.203-204
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• 2002

The wear behaviour of steam generator (SG) tubes (Inconel 600 and 690) against support materials (405 and 409 ferritic stainless steels) has been experimentally studied in room temperature water using reciprocating wear apparatus with tube-an-plate configuration. The results showed that the wear rate of Inconel 690 was lower than that of lnconel 600 with increasing normal loads and sliding amplitudes. Also, plastic deformation layers appear below the surface of both SG tubes, which have a specific thickness and are small compared with their grain size. This means that wear rate of SG tubes in water condition is closely related to the formation and fracture of plastic deformation layers.

• Journal of Welding and Joining
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• 제5권1호
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• pp.57-63
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• 1987

A method which can be used for evaluating slag detachability is proposed in this study. The proposed method was intended to get an absolute value for slag detachability, to give consistent value for a given welded joint, and finally to be simple to test. With a test fig made in this study, an impact by dropping a steel ball (13Kg in weight) is applied on the back side of an as-welded plate having a slag layer on the weld bead. Such impact applied forces the slag to drop off from the bead surface. In order to make a quantitative evaluation the amount of slag removed was measured with increasing the number of drops. Using this method six kinds of fluxes were evaluated in terms of the effects of flux type, basicity and weding variables on the slag detachability. As an initial result of this test, it was found that welding heat input affects the detachability significantly. Most importantly the evaluation made using the presently proposed method gives the same order of ranking as that of the actual practice done by a welder.

• 한국진공학회지
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• 제1권2호
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• pp.259-268
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• 1992

냉연강판의 성능은 그 표면 상태에 의해서 많은 영향을 받는다. Temper-color(T/C)층은 tempering 과정 중 형성되는 다양한 색깔의 얇은 산화층으로서, 우 수한 표면 품질을 갖기 위해서는 방지 또는 제어되어져야 한다. T/C 현상을 이해하기 위하 여 여러 가지 표면 분석방법이 동원되었다. 유백색 T/C층의 표면은 1$mu extrm{m}$ 크기의 구형의 미 세구조로 구성되어 있었다. thens과정 중 C, Si, Mn과 Al이 표면으로 농화됨을 알았고, Mn 과 C은 정상시료에서 보다 T/C 시료에서 농화가 심하였다. T/C 시료에서의 산화층 두께는 정상시료의 60-$\AA$ 보다 매우 두꺼웠으나, 발생 정도에 따라 변화하였다. T/C층 내의 각 원소 산화 상태는, Si은 SiO2의 상태로, Mn은 MnO나 MnO2의 상태로 Fe는 극표면층의 Fe2O3 상태를 제외하고는 metallic 상태로 분석되었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1994년도 추계학술대회논문집; 한국종합전시장, 18 Nov. 1994
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• pp.323-330
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• 1994

본 연구에서는 다공질 흡음재료 중 closed cell 구조를 갖는 발포수지재료(Foamed Material)에 음(sound)이 입사할 때 발생하는 흡음현상을 보다 정확히 예측하기 위해서 다공질 흡음재료에 대한 Biot 이론에 근거한 Allard의 모델링기법[4]을 이용하여 해석 프로그램을 개발하였고, 이를 이용하여 다공질 흡음재료가 단층(single layer)일 때 이 재료의 Surface Impedance와 흡음률(Absorption Coefficient)을 예측하고, 물성치(parameters)변화에 따른 다공질 흡음재료의 흡음특성을 분석하였으며, 이 재료가 자동차 제조시 사용되는 압연강판(rolled steel piate)에 부착되었을 때의 투과손실(Transmission Loss)을 예측하였고, 또한 다공질 흡음재료는 중고주파 대역의 음에 대한 흡음특성은 좋지만 저주파 대역의 음에 대한 흡음특성은 좋지 않으므로 흡음 재료의 저주파 대역의 흡음특성을 향상시키기 위해서 2층(two layers)으로 하였을 때의 흡음특성을 분석하였다. 본 논문의 연구결과는 자동차 제조시 사용되어지는 다공질 흡음재료는 물론 산업용기계나 건축용등 여러 분야에서 사용되어지는 다공질 흡음재료의 흡음특성 분석에 응용될 수 있으리라 기대된다.

• Steel and Composite Structures
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• 제28권4호
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• pp.461-470
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• 2018

In this study, the effect of polyurethane foam filler, in addition to surface layer thickness and core material thickness, on vibration characteristics of sandwich structures was investigated. The manufacturing process was carried out according to the Taguchi method. The natural frequencies and damping ratios of the produced samples were determined experimentally for fixed-free boundary conditions. In addition, solid models were developed for test samples and their finite element analyses were performed with $ANSYS^{(R)}$ to obtain their natural frequencies and mode shapes. An acceptably good agreement was found with the comparison of experimental results with the numerically obtained ones. The most effective parameters on the vibration characteristics of the sandwich structure were determined by the Taguchi method.