• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.17-30
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• 2023

This study investigates the impact of water immersion and high temperature on the shear strength of cemented sand through direct shear tests. Standard Jumunjin sand was used and cemented with binders, such as ultra-rapid hardening cement and an epoxy aqueous solution. The binder was mixed at concentrations of 4%, 8%, or 12%. Subsequently, cylindrical cemented specimens with a diameter of 64 mm and height of 25 mm were produced using compaction. The curing period was three days, and the specimens were cured under dry air, immersion, and heating conditions. The heating condition involved subjecting the immersed specimens to a microwave oven three times for three minutes to achieve an internal temperature of approximately 90℃. Regardless of the binder type, the cohesion of the cemented sand increased with higher binder content, whereas the internal friction angle exhibited a slight increase or decrease. Compared with ultra-rapid hardening cemented sand, epoxy-cemented sand displayed an average cohesion that was five times higher and an internal friction angle that was 10° higher. Overall, irrespective of binder type, the shear strength decreased during water immersion and increased during heating. Notably, the epoxy-cemented sand exhibited a three-fold increase in cohesion and a more than 20° increase in the internal friction angle during heating.

• Kyungpook Mathematical Journal
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• v.54 no.2
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• pp.271-292
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• 2014

We introduce a new method to transform a knot diagram into a diagram of an unknot using a polynomial representation of the knot. Here the unknotting sequence of a knot diagram with least number of crossing changes can be realized by a family of polynomial maps. The number of singular knots in this family is defined to be the singularity index of the diagram. We show that the singularity index of a diagram is always less than or equal to its unknotting number.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.9-19
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• 2011

The paper describes the validation of two time domain methods to simulate the behaviour of a destroyer operating in steep, stern-quartering seas. The significance of deck-edge immersion and water on deck on the capsize risk is shown as well as the necessity to account for the wave disturbances caused by the ship. A method is described to reconstruct experimental wave trains and finally two deterministic validation cases are shown.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.363-371
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• 2000

There are some concepts that could achieve Near-Field Recording (NPR). One of concepts is the use of the flying head with Solid Immersion Lens (SIL). The basic concept of this is almost same with that of Hard Disk Drive (HDD). This study presents the flying characteristics of the slider for NFR. Numerical simulations are performed using FEM and Broydon-Fletcher-Goldfarb-Shanno (BFGS) method. Some modifications are considered to improve flying characteristics of the slider.

• International Journal of Contents
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• v.9 no.4
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• pp.30-34
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• 2013

Internet banner advertisement has become recognized as an important media, and its influence has been increasing. The merits of Internet banner advertisement are diversity and consumer immersion. Especially, by using various types and visual expression methods, the automobile Internet banner advertisement has evolved into what attracts curiosity and interest of potential consumers. Thus, to find efficient communication method for automobile Internet banner advertisement, this study, by comprehensively analyzing various advertisement methods in previous researches, suggested an advertisement type and a visual expression method suitable to automobile Internet banner advertisement. Four types of automobile Internet banner advertisement are production form, production purpose, expression form, and advertisement area. Four visual expression methods are action form, image, change form, and moving form. And, through case analysis, this study also examined the value of the newly suggested method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.241-242
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• 2021

In this study, we develop the damage depth diagnostic technology of fire damage concrete and propose an method of impaired depth due to fire by drying impaired concrete after immersing. Test results indicated that when assesing impared depth due to fire with the dry method after water immersing, impaired depth was clearly found and furthermore, compared with that by Phenolphthalein method 10 mm of damage depth was additionally identified, which is imposible to asses when Phenolphthalein is applied.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.245-246
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• 2021

In this study, we develop the damage depth diagnostic technology of fire damage concrete and propose an method of impaired depth due to fire by drying impaired concrete after immersing. Test results indicated that when assesing impared depth due to fire with the dry method after water immersing, impaired depth was clearly found and furthermore, compared with that by Phenolphthalein method 15 mm of damage depth was additionally identified, which is imposible to asses when Phenolphthalein is applied.

• Journal of Physiology & Pathology in Korean Medicine
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• v.28 no.6
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• pp.674-682
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• 2014

The purpose of this study was to identify the effect of applying oriental music therapy and reliability of electroencephalogram(EEG) equipment. The study was approved by the critical trial judge committee from ${\bigcirc}{\bigcirc}$(IRB No. 2013-07) university. In order to measure test-retest reliability for 15 subjects, EEG for same participants were measured using same method mentioned above after 2 hours from the first measurement. Same provider implemented to each person at same time. Firstly, EEG was measured for 5 minutes after the subject with attached electrodes sat on chair comfortably for 10 minutes. Then, the subject was given mental stress using the four fundamental arithmetic operations for 5 minutes, and measured EEG for another 5 minutes. After that the subject sat on the chair comfortably listening oriental medicine music therapy for 5 minutes, and EEG was measured for 5 minutes again. There was no side effect regarding music therapy reported. Raw data, which was measured in each step, were converted through FFT(fast fourier transform) and analyzed after divided into certain frequency including ${\alpha}$ wave, ${\beta}$ wave, ${\theta}$ wave, immersion wave, stabilization wave, sef100 wave, and sef95 wave. Data were analyzed using wilcoxon signed rank test, Intraclass correlation coefficient(ICC), repeated measures ANOVA with the SPSS program. In test-retes method, there were significantly differences in ${\alpha}$ wave, ${\beta}$ wave, immersion wave, stability wave, ${\theta}$ wave, sef100 wave, sef95 wave. ICC has shown a high degree of reliability that it was ${\alpha}$ wave .877, ${\beta}$ wave .855, ${\gamma}$ wave .895, immersion wave .897, stability wave .816, ${\theta}$ wave .904, sef100 wave .910, sef95 wave .776. Also, there was a statistically significant difference in ${\alpha}$ wave after applying oriental music therapy. Based on these results, it is considered that average of the channel EEG and application of oriental music therapy would be practiced by increase of sample size using this machine.

• Journal of the Society of Disaster Information
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• v.18 no.4
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• pp.713-728
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• 2022

Purpose: This study examined the effect of VR safety education content quality on behavioral intention and collect operational opinions through interview. Method: Based on the survey data of 93 former and current officers, the hypothesis was verified. In addition, 15 fire safety experience centers were visited to conduct interview. Result: For the quality of VR safety education contents, immersion and convenience had a significant effect on usage satisfaction, recommendation intention, and field application intention. In addition, convenience and aesthetic experience had a significant effect on the educational effect, but immersion and diversity did not significant. In the interview, they suggested that VR education has high user satisfaction and good educational effects. The quality of content(particularly immersion and convenience) is an important factor in VR education. In the long-term persepective, it is necessary to prepare a standard teaching plan for each disaster, in addition, manpower, expertise, maintenance problems, and etc. Conclusion: Through these results, it was confirmed that VR experience content quality affects behavioral intention and educational effect and that efforts and investments to improve content quality are needed to enhance the effectiveness of VR experience education. And the contents derived from the interview will be helpful in the operation of an effective fire safety experience center.

• Corrosion Science and Technology
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• v.5 no.4
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• pp.129-136
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• 2006

High temperature corrosion behavior of AISI-type 316L stainless steel for the MCFC(molten carbonate fuel cell) bipolar application was studied by immersion test and penetration attack method in anode environment ($650^{\circ}C$, $Li_2CO_3/K_2CO_3=62/38$ mol%, $H_2/CO_2=80/20$ vol%) without or with different $CaCO_3$ content. Not only immersion test method but also morphological observation of samples in the carbonate melts are adopted as experimental methods. With aid of the morphological observation of cross section of samples immersed in a carbonate melt was possible to obtain penetration attack. The concentration effect of $CaCO_3$ inhibitor was investigated in order to verify the optimum concentration for practical application in MCFC stack operation. The corrosion rate in the presence of $CaCO_3$ was proven to be decreased as a function of $CaCO_3$ concentration. The corrosion rate in the presence of $CaCO_3$ was measured with a value of 6.9 mpy which is 2.4 times lower than that of inhibitor-free electrolyte. The cross section microscopy revealed that the internal penetration by oxidation in molten carbonate is very severe. In this case, the attack was occurred not only dissolution loss in the electrolyte by corrosion reaction but also weight gain through oxide layer by internal penetration.