• Tribology and Lubricants
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• v.10 no.3
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• pp.29-38
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• 1994

The friction and wear of mild steel at dry sliding surfaces under different vacuum conditions have been investigated to understand the wear mechanisms. For the test, a ball-ondisk typed wear-rig has been built and implemented, allowing control of sliding speed, load and vacuum. Results show that, at a high sliding velocity, friction of low carbon steel (SS41) under a high vacuum is much higher than that of ambient condition and wear is much severer. It is due to lack of effective oxidation film formation on which steel surfaces could protect themselves against the severe wear. It has been shown, however, that there is a critical regime with contact conditions (at a low sliding velocity, a low load, and under a medium vacuum) at which effective, protective films of low carbon steel have been built on the surfaces in a friction process with a self-regulating way, resulting in both very low coefficients of friction (about 0.3) and mild wear. In order to investigate the protective films on steel surfaces, the worn surfaces and the wear debris have been experimentally analyzed with SEM, AES/SAM and XRD. A theoretical analysis of frictional heating at sliding surfaces, and an experimental analysis of the influence of oxidation wear under various vacuum conditions are described. The important variables on which self-formations of protective films at dry sliding surfaces depend, and the wear mechanisms are also investigated.

• Journal of the Korean Geographical Society
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• v.38 no.2
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• pp.156-172
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• 2003

In this paper we identify that there are High Higher surfaces(HH-surface) around Jeongdongjin and Daejin area where Higher surfaces(H-surface) of marine terrace are formed on a large scale. On the basis of an altitude of the ancient shoreline of the marine terraces, geomorphic surfaces can be classified into HH I (140m a.s.l), HH II (110m a.s.l), H I (90m a.s.l), H II (70m a.s.l), M (40m a.s.l), L I (25m a.s.l) and L II (10m a.s.l). Besides, we identify that the lowest surfaces(5~6m a.s.l) are found extensively in the research area which are assumed to be formed in the Holocene. Considering that the formation mechanism of the marine terraces in the research area is similar to that of the marine terraces at both Campo area in the south east coastal region of Korea md the thalassostatic terraces of Osip River in Samchuk in a short distance from the research area, we can assume that the HH-surfaces in both areas were formed in the same period. Based on the fact that L I- surface was formed on the Last Interglacial Stage of MIS 5, we can infer that M- was formed in MIS 7, H I- in MIS 9, H II- in MIS 11, HH I- in MIS 13 and HH II- in MIS 15. The reason for that H-surfaces, similar to those at Gampo area, to remain on a large scale is that the Holsteinian Interglacial continued for a long period of time and at that time there was a large wave-cut platform in the vicinity of the shoreline.

• Journal of the Korean Geographical Society
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• v.37 no.3
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• pp.222-236
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• 2002

The Osip-cheon river flowing on the east side of the Taeback mts. has formed river terraces on the several heights along the middle- and downstream. The river terraces are classified into 5 climatic ones and 7 thalassostatic ones. The thalassostatic ones are found to the height of 145-l50m level at 20-30m intervals. These vertical distribution is caused by the continuous uplift and periodical rise and fall of the sea-level. The high higher surfaces among the thalassostatic ones are the highest among those of Korea. The chronologies of the terraces are correlated to the marine oxygen isotope stages : The thalassostatic terraces on the level of 40 m.a.s.l. are to the stage 7, 70 m.a.s.l.. to the stage 9, 90 m.a.s.l. to the stage 9, 110 m.a.s.1. to the stage 11 and those of 150 m.a.s.1. to the stage 15 among the Interglacial Ages. The landuses and geomorphic landscapes of the Samchok area are chracteristic, because the karst landforms, such as doline and uvala, are developed on the surfaces of the middle-, the higher- and the high higher surfaces of river terrace.

• Analytical Science and Technology
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• v.30 no.1
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• pp.49-56
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• 2017

Here, we demonstrate surface functionalization of Au chips with 4-(carboxymethyl)aniline (CMA) and amine-terminated polyamidoamine (PAMAM) dendrimers for immobilization of antibodies on the Au surfaces. Use of the functionalization strategy led to high surface density of the immobilized antibodies on the Au chips. Specifically, we found that the functionalization of Au chips with CMA and amine-terminated $6^{th}$ generation PAMAM dendrimers allowed immobilization of immunoglobulin (IgG) antibodies with high surface density, which is 5 times higher than that obtained with Au surfaces functionalized with CMA and ethylenediamine.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.563-569
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• 2008

During braking operation, the surfaces of disk have severe contact conditions and high frictional heat would be generated between disk and pad surfaces. The heat makes high temperature gradient on disk surfaces and results in thermal deformation. To enhance the frictional heat dissipation, heat pipes are embedded in the ventilated type disk along the radial direction. The temperatures of the inner vent type disk and the brake disk with heat pipes are compared at the same operating conditions. By comparison a brake disk with heat pipes has higher cooling performance than the inner vent type disk.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.141-141
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• 2013

Shape control of metal nanocrystals has broad applications, including catalysis, plasmonics, and sensing. It was found that controlling the atomic arrangement on metal nanocrystal surfaces affects many properties, including the electronic dipole or work function. Tuning the surface structure of exposed facets of metal nanocrystals was enabled by shape control. We investigated the effect of shape on nanomechanical properties, including friction and adhesion forces. Two nanoparticles systems, high-index {321} and low-index {100}, were used as model nanoparticle surfaces. Scanning force microscopy was used to probe nanoscale friction and adhesion. Because of the abundant presence of high-density atomic steps and kinks, high-index faceted nanoparticles have a higher surface energy than low-index faceted cubic nanoparticles. Due to this high surface energy, high-index faceted particles have shown stronger adhesion and higher friction than low-index nanoparticles. We discuss the results in light of the differences in surface energy as well as the effect of capping layers in the measurement.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.140-146
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• 2007

To understand adhesive phenomena, we need to get force curve between two surfaces. And it is said that high stiffness force analysis system is needed to get precise force curve and more information of the surfaces. Usually the stiffness of the force measurement system is under the order of 10N/m. The stiffer force measurement system, however, results in more information on the surface, because higher stiffness lead to the wider range of force curves, secondly because the force curve obtained through the stiffer one describes more precise relationship between relative tip-sample separation and interaction force. In this paper, considering for stiffness and resolution, the cantilever was designed and we made adhesion force measurement apparatus with high stiffness and high resolution, so we measured adhesive force between Ag-ball and wafer.

• Journal of ILASS-Korea
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• v.16 no.2
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• pp.104-109
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• 2011

The present study investigated experimentally the spreading characteristics of a single liquid impinging on the inclined micro-textured aluminum (Al 6061) surfaces manufactured by using a micro computerized numerical control (${\mu}$-CNC) milling machine. The textured surfaces were composed of patterned micro-holes (diameter of $125\;{\mu}m$ and depth of $125\;{\mu}m$). In our experiment, the de-ionized (DI) water droplet of $4.3\;{\mu}l$ was impinged normally on the non-textured and textured surfaces at two different Weber numbers, and the droplet impinged on the inclined surfaces with different angles. A high speed camera was used to capture sequential digital images for measurement of the maximum spreading distance. It was found that for the textured surface, the measured apparent equilibrium contact angle (ECA) increased up to $105.8^{\circ}$, higher than the measured ECA of $87.6^{\circ}$ for the non-textured (bare) surface. In addition, it is conjectured that the spreading distance decreased because of a liquid penetration during droplet spreading through the holes, the increase in hydrophobicity, and viscous dissipation during impact process.

• Analytical Science and Technology
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• v.36 no.3
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• pp.121-127
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• 2023

The detection of blood at a crime scene is an important process for identification and case reconstruction. However, blood may be difficult to observe with the naked eye on dark or multi-colored surfaces. Acidic hydrogen peroxide (AHP) is a recently reported blood enhancement reagent that can enhance blood with high sensitivity by increasing the exposure time of the camera. However, it has never been compared to previously known techniques on dark or multi-colored surfaces. For this purpose, the method of observation/photographing (UV and IR photography), alginate casting, leuco rhodamine 6G (LR6G), and AHP were applied to bloody impression on dark or multi-colored surfaces and the results were compared. As a result, blood treated with AHP had a higher contrast to the surfaces than UV and IR photography, and it was applicable on all surfaces, opposed to alginate casting. In addition, AHP successfully enhanced blood on dark or multi-colored surfaces, similar to LR6G.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.350-353
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• 2001

Aligning capabilities for nematic liquid crystal (NLC) using a in-situ photodimerization method on various photo-crosslinkable polyimide (PI) based polymer and blending photopolymer surfaces were stuided. High pretilt angle of the NLC can be measured by obliquely polarized UV exposure on a photo-crosslinkable polyirnide based polymer surface containing biphenyl (BP), decyl (de), and cholesteryl (chol) group, respectively, However, the low pretilt angle of the NLC was measured by obliquely polarized UV exposure on the blending photopolymer (PI and cinnamate materials) surfaces. Consequently, the pretilt angle of the NLC generated on the photo-crosslinkable polyimide based polymer surfaces using the in-situ photodimerization method was higher than that of the blending photopolymers.