• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.3-23
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• 2017

The achievement of tissue engineering can be highly depending on the capability to generate complicated, cell seeded three dimensional (3D) micro/nano-structures. So, various fabrication techniques that can be used to precisely design the architecture and topography of scaffolding materials will signify a key aspect of multi-functional tissue engineering. Previous methods for obtaining scaffolds based on top-down are often not satisfactory to produce complex micro/nano-structures due to the lack of control on scaffold architecture, porosity, and cellular interactions. However, a bioprinting method can be used to design sophisticated 3D tissue scaffolds that can be engineered to mimic the tissue architecture using computer aided approach. Also, in recent, the method has been modified and optimized to fabricate scaffolds using various natural biopolymers (collagen, alginate, and chitosan etc.). Variation of the topological structure and polymer concentration allowed tailoring the physical and biological properties of the scaffolds. In this presentation, the 3D bioprinting supplemented with a newly designed plasma treatment for attaining highly bioactive and functional scaffolds for tissue engineering applications will be introduced. Moreover, various in vivo and in vitro results will show that the fabricated scaffolds can carry out their structural and biological functionality.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.220-227
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• 2018

Background: To understand the ecological characteristics of floating mat in which endangered species of Iris laevigata and Menyanthes trifoliata inhabit, we surveyed the vegetation and water environments of a floating mat wetland and examined the relations between ecological characteristics of the mat. Results: Although Phragmites australis and Zizania latifolia were found at all experimental quadrats (n = 61) as the major vegetational components of the floating mat wetland, they showed relatively poor growth performances in terms of shoot height (< 2 m) and biomass production (<$300g/m^2$) compared with those in soil-based wetlands because of oligotrophic water condition. The competitiveness and distribution of P. australis and Z. latifolia seemed to be determined by water level difference by micro-topography rather than water chemistry. Conclusion: P. australis and endangered plant species mainly occurred in the area of relatively shallow water, whereas Z. latifolia and deep-water species such as Scirpus fluviatilis mostly inhabit in the area of deep water on the floating mat. Continuously maintained water level and oligotrophic water condition in the floating mat appeared to be important environments for endangered species such as I. laevigata and M. trifoliata.

• Korean Journal of Metals and Materials
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• v.49 no.5
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• pp.395-399
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• 2011

In this study, micro gas sensors for ammonia gas were prepared by adopting MEMS technology and using a sol-gel process. Three types of sensors were prepared via different synthesis routes starting with W sol and Ru sol mixture. This mixture was deposited on a MEMS platform and the platform was subsegueny heated to a temperature of $350^{\circ}C$. The topography and crystal structure of the sensing film were studied using FE-SEM and XRD. The response of the gas sensor to $NH_3$ gas was examined at various operating temperatures and gas concentrations. The sensor response increased almost linearly with gas concentration and the best sensing response was obtained at $333^{\circ}C$ for 5.0 ppm $NH_3$ for the specimen prepared by coating $WO_3$ powders with the Ru sol mixture.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.1
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• pp.26-38
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• 2019

This study is based on the analysis of the characteristics of waterfront scenery. Recently, waterfront development has expanded residentially, commercially and into leisure space. In the development of the waterfront, it is necessary to apply designs suitable for urban and various other waterfront areas. In this study, the natural scenery of the waterfront was researched with respect to the Korean Jingyeong landscape paintings and the main elements of the scenery were analyzed. In this study, 105 painting of Korean Jingyeong landscapes paintings were selected for the analysis of the waterside scenery. The paintings of Jeong Seon were studied to categorize streams topographically into mountainous, upper, middle, lower, and ocean types. In addition, major micro-topography elements, which are 13 water image elements and 13 staffage elements were analyzed. The main waterfront landscape elements are divided into 13 types. The waterfalls were divided into long waterfalls, short waterfalls, cascading waterfalls, and other aspects considered were line stream, curve stream, multi-curve stream, pond, water surface, flow surface, wave surface, rock side, pile sandy side, sandy side. There are 13 kinds of staffage elements, include pine forest, pine trees, fir trees, bamboo trees, willow trees, broadleaf tree, villages, houses, gazebo, boat, bridges, and people. The waterfront landscape by a river area was explained according to each characteristic of the waterfront landscape and staffage, and their changes were analyzed in each area. The 105 paintings were divided into 35 pieces of mountainous streams, 9 upper streams, 5 middle streams, 35 lower streams, and 21 oceans, and the change of each waterfront landscape and staffage was analyzed. Based on the topographical analysis of the waterfront landscape and staffage, the results can be summarized into 5 types of the waterfront landscape. Based on the micro-topographical characteristics of the waterfront landscape styles are as follow. In the mountainous streams, long waterfall and deep forest type are apparent, which depicts deep mountain waterfall scenery, and a multi-stream forest is the scenery of a picnic in the mountains, which is a representative form of mountainous streams landscape. In the upper-middle stream, the water-surface and gazebo type is predominant. In the lower stream, the sandy-gazebo typ scenery is predominant and the sandy depiction is unique to lower stream landscape. Pile sandy-dock type is life scenes where human activity highlighted, is a representative form of the lower stream landscapes. The characteristic of the coastal landscape is the serpentine rock scenery on the beach and the wave-serpentine rock type that forms the main coastal landscape. The study aims to propose significant design elements for a natural waterfront landscape planning based on the analysis of landscape in the paintings of Jeong Seon.

• Advances in nano research
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• v.5 no.3
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• pp.245-251
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• 2017

Multiwalled carbon-nanotubes (MWCNT) and micro-structured carbon, such as biochar or activated carbon (AC), have been seen to significantly increase the growth indices of certain plant species such as maize (Zea mays L.). Seed imbibition is the stage where environmental factors that affect water transport across the seed coat barrier, make a large impact. This work explores the effect on water imbibition by maize seeds when the aqueous environment surrounding the seed is diluted by small concentrations (10 and 20 mg/l) of pristine MWCNT (p-MWCNT), carboxylate functionalized MWCNT (COO-MWCNT) and AC. The degree of sensitivity of the process to (i) large structural changes is seen by utilizing the nano (the MWCNT) and the micro (the AC) allotropic forms of carbon; (ii) to small changes in the purity and morphology of the p-MWCNT by utilizing 95% pure and 99% pure p-MWCNTs of slightly differing morphologies; and (iii) to MWCNT functionalization by using highly pure (97%) COO-MWCNT. Water imbibition was monitored over a 15 hour period by Near Infrared Thermography (NIRT) and also by seed weighing. Seed surface topography was seen by SEM imaging. Analysis of the NIRT images suggests rapid seed surface topological changes with the quantity of water imbibed. While further work is necessary to arrive at a conclusive answer, this work shows that the imbibition phase of the maize seed is sensitive to the presence of MWCNT even to small differences in the purity of the p-MWCNT and to small differences in the physicochemical properties of the medium caused by the hydrophilic COO-MWCNT.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.161-162
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• 2002

This study concerns the tribological behaviors of ultra-thin DLC coating with 3 nm thickness deposited in a mixed gas of argon + 20 % hydrogen as a function of humidity. Reciprocating wear tests employing a micro wear tester were performed under various normal loads and relative humidity in air environment. The chemical composition of the original and worn surfaces were studied by Auger electron spectroscopy (AES). It showed that the ultra-thin DLC coating exhibited low friction with enough wear stability at low normal load (0.18 N) and its tribological behavior was strongly dependent on the humidity. The sample surfaces before and after the test were examined using atomic force microscopy (AFM). Capillary force and meniscus areas were discussed in order to explain the influence of humidity on the friction force.

• Tribology and Lubricants
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• v.21 no.1
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• pp.1-7
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• 2005

Effect of Surface roughness on nanoscale adhesion was studied experimentally by using colloidal probe technique. Glass micro balls having the radius of $3.3\~17.4{\mu}m$ were glued at the end of AFM cantilevers to prepare colloidal probes. Adhesion force between the colloidal probe and Si-wafer was measured using pull-off force measuring method. Results showed that the measured adhesion forces are not the function of the radius of the glued balls because the ball surfaces are rough. It is also found that roughness parameters such as $R_a,\;R_q\;and\;R_{max}$ do not have important role on nanoscale adhesion. In order to find the effect of surface roughness on nanoscale adhesion, the bearing areas were extracted from the measured topography of glued balls. After normalizing the measured adhesion force with the bearing area, it was found that the normalized adhesion force kept constant as function of the radius of glued ball.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.128-131
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• 2002

Three Dimensional measuring system using optical interference is greatly needed for semiconductor surface or optical surface. The application of this system are : MEMS product, semiconductor surfaces, optical components, precise machined surface, etc. In this paper, Interferometry based measurement system is introduced, which is nondestructive and noncontact inspection system. This system have relatively many advantage, compared with AFM/STM, SEM, Stylus, etc. The developed system can measure the surface topography with high precision and resolution, and with few seconds. And the associated software algorithm is also developed for the ultra precision 3D measuring surface. Various samples that is measured using this system is showed in the latter of this paper.

• Journal of the Korean institute of surface engineering
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• v.25 no.2
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• pp.90-96
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• 1992

Thed effects of sputter gas pressure and substrate surface micro-roughness on the microstructure and surface topography have been investigated in the Cu thin films sputter deposited onto polyimide substrates. The surface roughness of polyimide was controlled by oxygen rf plasma treatment. In the Cu film deposited at the pressure of 5 mtorr, the surface is smooth and the columnar structure is not visible regardless of polyimide surface more open boundaries. The polyimide surface roughness enhances these effects, These phenomena can be explained in therm of atomic shadowing effect.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.3
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• pp.343-350
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• 2021

Unmanned aerial vehicles(UAV) photogrammetry provides a cost-effective option for collecting high-resolution 3D point clouds compared with UAV LiDAR and aerial photogrammetry. The main objectives of this study were to (1) validate the accuracy of 3D site model generated, and (2) determine the differences between Digital Elevation Model(DEM) and Digital Surface Model(DSM). In this study, DEM and DSM were shown to have varying degree of accuracy from observed data. The results indicated that the model predictions were considered tend to over- and under-estimated. The range of RMSE of DSM predicted was from 8.2 and 21.3 when compared with the observation. In addition, RMSE values were ranged from 10.2 and 25.8 to compare between DEM predicted and field data. The predict values resulting from the DSM were in agreement with the observed data compared to DEM calculation. In other words, it was determined that the DSM was a better suitable model than DEM. There is potential for enabling automated topography evaluation of the prior-harvest areas by using UAV technology.