• Corrosion Science and Technology
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• v.20 no.6
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• pp.451-465
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• 2021

In this investigation, electrochemical characteristics and damage behavior of 316L stainless steel polymer electrolyte membrane fuel cell(PEMFC) were analyzed by potentiodynamic and potentiostatic tests in cathode operating condition of PEMFC. As the result of potentiodynamic polarization test, range of passive region was larger than range of active region. In the result of potentiostatic test, damage depth and width, pit volume, and surface roughness were increased 1.57, 1.27, 2.48, and 1.34 times, respectively, at 1.2 V compared to 0.6 V at 24 hours. Also, as a result of linear regression analysis of damage depth and width graph, trend lines of damage depth and width according to applied potentials were 16.6 and 14.3 times larger, respectively. This demonstrated that applied potential had a greater effect on pitting damage depth of 316L stainless steel. The damage tendency values were 0.329 at 6 hours and 0.633 at 24 hours with applied potentials, representing rapid growth in depth direction according to the test times and applied potentials. Scanning electron microscopy images revealed that surface of specimen exhibited clear pitting damage with test times and applied potentials, which was thought to be because a stable oxide film was formed by Cr and Mo.

• Korean Institute of Interior Design Journal
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• v.22 no.6
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• pp.140-150
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• 2013

The weaving of Mosi(fine ramie) in the Hansan region was inscribed on the representative list of the UNESCO intangible cultural heritage in 2011. Unlike other fabric, as the Mosi is very sensitive towards humidity it needs different conditions for its workspace. The Hansan region is near the sea with many mountains around where it is easy for the Mosi to grow and is an appropriate place to weave Mosi. Recently the manpower for weaving of Mosi in the Hansan area is decreasing with the decrease of workspace drastically. After the investigation of workspace for the weaving of Mosi in the Hansan area, most of the places were done in individual houses and it could be classified in 1. Mosi storeroom, 2. Shed(Gwang che), 3. Dugout hut, 4. Under the toenmaru The depth of the dugout hut and under the toenmaru is around 80~60cm which is similar with the depth of the prehistoric dugout hut houses. The towns for weaving of Hansan Mosi are formed mostly in the Seochungun district, but the Hoamri Hansan-myeon and Gayangri Masan-myeon has the most traditional workspaces and they are still forming and maintaining the traditional town composition. However the numbers are too small and maintaining the traditional town is getting more difficult, so a plan for the maintenance should be made to continue to keep it as UNESCO intangible cultural heritage.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.2
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• pp.103-111
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• 1996

In this paper, we studied on both electrochemical polarization behaviors and pitting characteristics of ultra high strength Al-Cu-Li-Mg-Ag-Zr alloys(named C1 and C2) and 2090 alloy according to their treatments in the deaerated 3.5% NaCl, using by the potentiodynamic and the potentiostatic method, SEM micrograph and surface roughness including depth of pitting attack. With the cyclic polarization curves, the hysteresis of the C1 and C2 alloys appeared more remarkably than that of the 2090 alloy, because of precipitation microstructural difference between C1, C2 alloys and 2090 alloy. In the pitting experiments, the correlations between pitting growth and aging conditions were analyzed with the SEM micrograph and measurement of the pit depth.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.273-276
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• 2008

Thermoplastic resin takes place stress relaxation and creep according to temperature and time. In room temperature, time dependent deformation (TDD) of polymer was carried out at previous study. In this study, it evaluates time dependent deformation to relate temperature. Nanoscale indents can be used as cells for molecular electronics and drug delivery, slots for integration into nanodevices, and defects for tailoring the structure and properties. Therefore, it is important to control pattern depth for change of indent depth by creep when using Nanoindenter. For evaluating TDD at high temperature, it is occurred thermal-nanoindentation test by changing hold time at maximum load. Temperature is putted at $90^{\circ}C$, hold time at maximum loads are putted at 1, 10, 50, 100, 200, 300 and 500s.

• Clinical Endoscopy
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• v.51 no.6
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• pp.527-533
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• 2018

There have been many advances in endoscopic imaging technologies. Magnifying endoscopy with narrow-band imaging is an innovative optical technology that enables the precise discrimination of structural changes on the mucosal surface. Several studies have demonstrated its usefulness and superiority for tumor detection and differential diagnosis in the stomach as compared with conventional endoscopy. Furthermore, magnifying endoscopy with narrow-band imaging has the potential to predict the invasion depth and tumor margins during gastric endoscopic submucosal dissection. Classifications of the findings of magnifying endoscopy with narrow-band imaging based on microvascular and pit patterns have been proposed and have shown excellent correlations with invasion depth confirmed by microscopy. In terms of tumor margin prediction, magnifying endoscopy with narrow-band imaging offers superior delineation of gastric tumor margins compared with traditional chromoendoscopy with indigo carmine. The limitations of narrow-band imaging, such as the need for considerable training, long procedure time, and lack of studies about its usefulness in undifferentiated cancer, should be resolved to confirm its value as a complementary method to endoscopic submucosal dissection. However, the role of magnifying endoscopy with narrow-band imaging is expected to increase steadily with the increasing use of endoscopic submucosal dissection for the treatment of gastric tumors.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1155-1162
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• 2023

The Korea Research Institute of Ships and Ocean Engineering (KRISO), which is developing the core technology for the buoyancy engine of underwater gliders, has developed a test module that can vertically ascend and descend with a buoyancy engine to verify the performance of the developed buoyancy engine. The independent test module was tested in a 15 metre deep pit in the Ocean Engineering Basin to verify its ability to ascend and descend. In order to test at a shallower depth than the real sea, it was necessary to know the negative buoyancy value during descent and the time at which the buoyancy engine would be activated. To do this, we solved the equation of motion in the vertical direction to obtain these values and applied them to the tank test. To validate the usefulness of solving the equation, we also compared the depth of descent over time measured in the test with the results calculated from the solution.

• Explosives and Blasting
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• v.8 no.4
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• pp.3-22
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• 1990

The $\varphi{4.5}$ meters pilot tunneling work is almost done to the $\varphi{11.3}$ meters twin tunnel of NAM SAN No1. The south side pit of 400 meters is weak zone of Rock status, so client request us to allow the cautious blasting pattern for drilling on the condition of 0.2 kine vibration allowance limited for the safety of side running tunnel. The pattern of cautious blasting carried out by 6 time divided fiving on the round drilling depth of 1.20 meters(1.10) and also applied control blasting method with line drilling due to the reduction of vibration.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.80-88
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• 2010

A simple computational model for modeling of subsurface crack growth under cyclic contact loading is presented. In this model, it is assumed that the initial fatigue crack will initiate in the region of the maximum equivalent stress at certain depth under the contacting surface. The position and magnitude of the maximum equivalent stress are determined by using the equivalent contact model, which is based on the Hertzian contact conditions with frictional forces. The virtual crack extension method is used for simulation of the fatigue crack growth from the initial crack up to the formation of the surface pit due to contact fatigue. The relationships between the stress intensity factor and crack length are then determined for various combinations of equivalent contact radii and loadings.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.46-50
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• 2000

A theoretical model for the evaluation of small surface fatigue crack initiated from a pit-type surface flaw is presented. The low frequency scattering model is developed based on the reciprocity principle for the elastic wave scattering. The effect of the flaw on the surface wave reflection from the crack is taken into account approximately by means of the stress intensity factor of cracks on a through thickness hole. The reflection coefficient of surface wave is derived for the prediction of small surface crack depth. Calculated results for pits with different sizes are illustrated.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.132-136
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• 2005

It is widely accepted that the reading mechanism of Super-RENS(super-resolution near field structure) and Super-ROM(super-resolution read only memory) is closely related with non-linear temperature dependent material properties such as refractive indices, phase change. Furthermore, the dynamic change of the temperature distribution also an essential part of reading mechanism of Super-RENS/ROM. Therefore, the knowledge of the temperature distribution as a function a time is one of the important keys to reveal the physics of reading mechanism in Super-RENS/ROM. We calculated time-dependent temperature distribution in a 3-dimensional Super-ROM disk structure when moving laser beam is irradiated. With a help of commercial software FEMLAB which employed finite element method, we simulated the temperature distribution of ROM structure whose pit diameter is 120-nm with 50-nm depth. Energy absorption by moving laser irradiation, time variations of heat transfer processes, heat fluxes, heat transfer ratios, and temperature distributions of the complicate 3-dimensional ROM structure have been obtained.