• Ocean and Polar Research
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• v.41 no.1
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• pp.19-34
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• 2019

The present study obtained universal mathematical models of all elements and characteristics regarding hook and line fishing systems. To describe the hook and line fishing systems on site we used three kinds of coordinate systems: the earth based coordinate system, natural coordinate system, and flow (velocity) coordinate system. Mathematical models presented in this article allow us to define the shape of the fishing gear, the tension of the rope at different points, hydrodynamic resistance, diameter of the hook's wire, immersion depth of the fishing hooks, distance from hooks to the ground and the required lifting force of the floats. These models allow for the performance of computer simulations regarding any kinds of hook and line gears in still water or water where flow occurs.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.178-178
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• 2016

Every display is equipped with a cover glass to protect the underneath displaying devices from mechanical and environmental impact during its use. The strengthened glass such as Gorilla glass.$^{TM}$ has been exclusively adopted as a cover glass in many displays. Conventionally, the strengthened glass has been manufactured via ion-exchange process in wet salt bath at high temperature of around $500^{\circ}C$ for hours of treatment time. During ion-exchange process, Na ions with smaller diameter are substituted with larger-diameter K ions, resulting in high compressive stress in near-surface region and making the treated glass very resistant to scratch or impact during its use. In this study, PIIID (plasma immersion ion implantation and deposition) technique was used to implant metal ions into the glass surface for strengthening. In addition, due to the plasmonic effect of the implanted metal ions, the metal-ion implanted glass samples got colored. To implant metal ions, plasma immersion ion implantation technique combined with HiPIMS method was adopted. The HiPIMS pulse voltage of up to 1.4 kV was applied to the 3" magnetron sputtering targets (Cu, Ag, Au, Al). At the same time, the sample stage with glass samples was synchronously pulse-biased via -50 kV high voltage pulse modulator. The frequency and pulse width of 100 Hz and 15 usec, respectively, were used during metal ion implantation. In addition, nitrogen ions were implanted to study the strengthening effect of gas ion implantation. The mechanical and optical properties of implanted glass samples were investigated using micro-hardness tester and UV-Vis spectrometer. The implanted ion distribution and the chemical states along depth was studied with XPS (X-ray photo-electron spectroscopy). A cross-sectional TEM study was also conducted to investigate the nature of implanted metal ions. The ion-implanted glass samples showed increased hardness of ~1.5 times at short implantation times. However, with increasing the implantation time, the surface hardness was decreased due to the accumulation of implantation damage.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.192-192
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• 1999

SIMS(Secondary Ion Mass Spectrometry)는 다른 표면 분석장비와 비교하여^g , pp m,^g , pp b 단위의 미량분석이 가능한 장비로서, 특히 depth Profiling을 위한 dynamic SIMS는 Mass Spectrometer의 종류에 따라 Quadrupole SIMS (Q-SIMS)와, Magnetic Sector SIMS (M-SIMS)로 분류된다. 한편, Q-SIMS와 달리 M-SIMS의 경우, Transmission을 높여 주기 위해 Sample Holder에 수 keV의 bias를 걸어 주는데, 이로 인하여 분석 원소에 대한 Sensitivity가 향상되어 지는 반면, RSF의 변화와 같은 분석상의 Artifact가 발생하게 된다. 일반적으로 Q-SIMS의 경우에는 RSF의 RSD(Relative Standard Deviation)가 1%이내에서 보고되고 있지만 M-SIMS에 있어서는 이러한 Deviation이 M-SIMS보다 크게 나타난다. 이 차이는 주로 Sample Holder와 Immersion Lens 사이에 형성되는 Magnetic Field의 왜곡과 Spectrometer의 문제로부터 발생한다. 본 논문에서는 Sample Holder의 종류 및 holder so window 위치에 따라 RSF의 차이를 측정하고 그 data를 RS/1 통계 Package를 이용하여 계량적으로 검증하였으며, 그 차이의 원인과 대책을 제시하고자 한다. 실험에 사용된 Sample은 Si(100) p-type Wafer에 Boron을 이온 주입하여 제작하였다. 이온 주입 장비는 Varian E-500HP이며, 5.0E13 ions/cm2의 dose양을 80keV의 Energy로 각각 7도와 22도의 Tilt와 Twist Angle로 이온 주입을 하였다. SIMS분석에 사용된 Sample Holder는 각각 3 Hole, 9 Hole Type HOlder이며, 분석은 Cameca IMS-6f를 사용하여 B에 대한 Matrix Peak으로 28Si++를 얻었다. 실험 결과 3 Hole Type Sample Holder의 경우 RSF의 RSD는 5.84%, 9Hle Type Sample Holder의 경우는 14.3%로 나타났으나 분석 Window의 위치에 따르는 Grouping을 실시한 결과, 3 Hole Type Sample Holder의 경우 1.2%, 9Hole Type Sample Holder의 경우 9.8%로 RSF의 변화가 감소하였다. 이러한 Deviation은 Sample Holder를 Mount시킬 때 세 개의 Screw를 이용하여 Immersion Lens와의 평형을 잡아주기 때문에 발생하며, 이 Munting을 정확히 해줌으로써 RSF의 변화를 줄일 수 있으나, 실제로 완벽한 Mounting이 불가능하기 때문에 RSF를 일정하게 하기 위해서는 Sample Holder so Window의 취치를 일정하게 설정한 후 분석을 실시해야 한다고 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1188-1194
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• 2014

The purpose of this study is to estimate Chloride Attack Resistibility and mechanical properties of quaternary concrete adding fly ash, blast-furnace slag, and silica fume. Compressive strength, modulus of elasticity, chloride migration coefficient, charge passed from Rapid chloride penetration test(RCPT), and immersion testing in 3% NaCl are tested. Chloride migration coefficient and charge passed of quaternary concrete measured $0.032{\times}10^{-12}m^2/sec$ and 650 coulomb at 17 weeks, which are in a permitted limit. Also in immersion test, depth of chloride penetration and maximum chloride ion of quaternary concrete measured 3.7 mm and $10.211kg/m^3$ respectively. From the results, quaternary concrete adding fly ash, blast-furnace slag, and silica fume denotes improvement of mechanical properties and chloride attack resistibility.

• The Journal of the Korea Contents Association
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• v.22 no.8
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• pp.444-454
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• 2022

The purpose of this study is to investigate the effects of writing academic reflection journals and feedback activity experiences in untact online classes for engineering students who have taken communication liberal arts classes, and to find out the effect of these learning strategies to promote students' learning motivation, to check whether it is useful for class participation and immersion. In order to find out the effect of class, pre- and post-tests on learning motivation were conducted, and the students' reflection journals and in-depth interviews were analyzed using the topic analysis method, which is one of the qualitative research methods. As a result of the study, it was found that the reflection journal and feedback activity had a significant effect on individual learning understanding, immersion, attitude, etc. The study is meaningful in that it was able to confirm students' active learning attitudes and positive teaching effects with appropriate learning strategies according to changes in the untact educational environment. Various teaching-learning strategies according to changes in the educational environment should be sought and applied in many ways.

• Industry Promotion Research
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• v.9 no.3
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• pp.155-161
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• 2024

This study investigates user experiences of reward-based mini-games, gamified elements within the domestic mobile commerce sector. Recently, gamification marketing strategies have been actively employed in mobile commerce services to attract customers, increase dwell time, and enhance revisit rates. Conducting research on user experiences of gamified elements, we quantified evaluations of how users perceive these elements within mobile commerce. Using enjoyment, immersion, rewards, value, and utility as criteria, we designed a questionnaire and conducted surveys, followed by 1:1 in-depth interviews with users aged 20 to 40. The experimental results highlight the need for strategies to increase user satisfaction in terms of enjoyment and immersion, as well as the necessity to enhance user experiences related to predictable reward systems and product exploration to facilitate product purchases. It is hoped that this study will provide insights for companies seeking to incorporate gamified elements into their marketing strategies and improve user experiences.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.16-23
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• 2018

In this study, Polydimethylsiloxane (PDMS) was applied to Strain Hardening Cement Composites (SHCC) for penetrating water repellency. The penetration depth of PDMS, strength of SHCC, and chloride ion penetration resistance of SHCC were investigated. As a result of measuring penetration depth of PDMS when applying different application method, it was confirmed that all methods satisfied the requirements of KS F 4930. Although the immersion method showed the largest penetration depth, the spray method was considered to be more appropriate considering the ease of field application. Compressive strength tests showed that the penetration depth of PDMS decreased as the compressive strength of SHCC increased. The compressive strength of M4-A and M4-B specimens with large PDMS penetration depths decreased by 9.6% and 8.0%, respectively, compared with those of M4 specimens produced without PDMS. Compressive strengths of the M1-A and M1-B specimens with small PDMS penetration depths were reduced by 4% and 2.2%, respectively, compared with the M1 specimen. As a result, it can be seen that the strength reduction rate of SHCC increases as the penetration depth of PDMS increases. The chlorine ion penetration tests showed that the chlorine ion penetration resistance increases with the penetration depth of PDMS.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.679-686
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• 2005

The corrosion of reinforcement induced by chloride ingress is the main deterioration cause of coastal reinforced concrete structures. In this paper, an experimental study was executed to investigate the effect of the kinds and replacement ratios of mineral admixtures (fly-ash, ground granulated blast-furnace slag silica fume and meta-kaolin), W/B and curing time on chloride diffusion of concrete by long-time immersion test in chloride solution. According to the result, the use of mineral admixtures was effective in improving the resistant to chloride ingress. The chloride penetration depth and diffusion coefficient were decreased as replacement ratios of mineral admixture were increased. The kind and replacement ratio of the mineral admixture are more important than the W/B in reducing the chloride diffusion of concrete. Chloride binding capacity of mineral admixture, which was sequenced in the order of MK

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.2
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• pp.180-185
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• 2004

Conventional ultrasonic examination to detect micro and small surface cracks is based on the pulse-echo technique using a normal immersion focused transducer with high frequency, or an angle-beam transducer generating surface waves. It is difficult to make an automatic ultrasonic system that can detect micro and small surface cracks and position in a large structure like steel and ceramic rolls, because of the huge data of inspection and the ambiguous position data of the transducer. In this study, a high-precision scanning acoustic microscope with a 10MHz large-aperture transducer has been used to assess the existence, position and depth of a surface crack from the real-time A, B, C scans obtained by exploiting the ultrasonic diffraction. The ultrasonic method with large aperture transducer has improved the accuracy of the crack depth assessment and also the scanning speed by ten times, compared with the conventional ultrasonic methods.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.71-76
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• 2004

This paper investigate that the effect of the concrete containing mineral admixtures(pozzolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for $3\sim4$ replacement ratios under W/B ratios ranged from 0.40 to 0.55. Specimens were immersed in $3.6\%$ NaCl solution for 330 days, and penetration depth, water soluble chloride contents and acid soluble chloride contents were measured in 28, 91, 182 and 330 days. Then, diffusion coefficient were calculated using total chloride contents. As a results. the kinds of mineral admixture and replacement ratios had a great effect on the resistance property of the concrete to chloride ion invasion compared with the plain concrete. And the optimal replacement ratios of mineral admixture had a limitation for each admixtures. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures and the penetration depth from the concrete skin. Chloride diffusion coefficient of each concretes decreased with the time elapsed. and the diffusion coefficients of the concrete immersed salt water for 330 days had a establishment with the compressive strength measured before immersing.