• 대한조선학회논문집
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• 제55권3호
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• pp.196-204
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• 2018

Present paper shows the basic design procedure for platform support vessel operating in open sea, and hull form development process. General design concept considering the operating mission, operating sea condition and shipping freight, etc. is explained shortly. For the hull form design, the initial hull form was designed based on the reference PSVs. The resistance and propulsion test results for the initial hull form with twin Azimuth thruster were analyzed and a few items for improvement were derived. At the next stage, main parameters including Length, Cp-curve, Cb, Lcb, etc. were changed totally for the hull form improvement. Furthermore, 3 different bulbous bows for the fore-body design to reduce the wave resistance and after-body design to reduce the residual resistance were carried out. The best hull form among the 3 fore-bodies with same after-body was selected through the comparison of wave resistance calculation results. Twin ducted Azimuth thruster with the smaller propeller diameter than the former were adapted to increase the propulsive efficiency. The final hull form with the twin Azimuth thruster was evaluated to satisfy more than the target design speed 14 knots in sea condition with sea margin 15% at the 5,000kW BHP through the model test in KRISO.

• 한국안전학회지
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• 제21권4호
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• pp.49-54
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• 2006

The evaluation of elastic-plastic fracture characteristic was investigated in ferrite steel SA 516- Gr70 used for reactor coolant piping elbow and support skirt of pressure vessels. This paper describes the effect of temperature on J-R curve characteristic of this material. The elastic-plastic fracture mechanics parameter J is obtained with unloading compliance method. The test method were analyzed according to ASTM E 813-89 and E 1152-89. Unloading compliance $J_{IC}$ tests were performed on 1 CT specimens at varied temperatures from $25^{\circ}C$ to about $400^{\circ}C$ using a high temperature extensometer. At all temperature, valid $J_{IC}$ measurements could be made and $J_{IC}$ decreased with increasing temperature. SEM fractography schematically illustrates microvoid initiation, growth and coalescence at the tip of a preexisting crack.

• Geomechanics and Engineering
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• 제21권6호
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• pp.503-511
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• 2020

This study evaluated the side resistance of drilled shafts socketed into rock sections. Commonly used analysis methods for side resistance of piles in rocks are examined by utilizing a large number of load test data. The analysis of the unit side resistance of pile foundations embedded into rock sections is based on an empirical coefficient (α) and the uniaxial compressive strength (q_u) or its root (${\sqrt{q_u}}$). The Davisson criterion was used to interpret the resistance capacity from the load test results to acquire the computed relationships. The α-${\sqrt{q_u}}$ relationship is proven to be reliable in the prediction of friction resistance. This study further analyzed the relationship by including the effect of rock quality designation (RQD) on the results. Analysis results showed that the analysis model of α-${\sqrt{q_u}}$-RQD provided better prediction and reliability considering the RQD classification. Based on these analyses, the side resistance of drilled shafts socked into rocks is provided with statistical data to support the analysis.

• 한국세라믹학회지
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• 제46권5호
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• pp.534-539
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• 2009

Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

• 한국재료학회지
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• 제29권11호
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• pp.670-676
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• 2019

We study substrate support structures and materials to improve uptime and shorten preventive maintenance cycles for chemical vapor deposition equipment. In order to improve the rolling of the substrate support, the bushing device adopts a ball transfer method in which a large ball and a small ball are mixed. When the main transfer ball of the bushing part of the substrate support contacts the substrate support, the small ball also rotates simultaneously with the rotation of the main ball, minimizing the resistance that can be generated during the vertical movement of the substrate support. As a result of the improvement, the glass substrate breakage rate is reduced by more than 90 ~ 95 %, and the equipment preventive maintenance and board support replacement cycles are extended four times or more, from once a month to more than four months, and the equipment uptime is at least 15 % improved. This study proposes an optimization method for substrate support structure and material improvement of chemical vapor deposition equipment.

• 한국수소및신에너지학회논문집
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• 제31권2호
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• pp.202-209
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• 2020

In methanol steam reforming, commercial catalysts in the form of pellets are mainly used, but there are limitations to directly apply them to underwater weapon systems that require shock resistance and heat transfer characteristics. In this study, to overcome this problem, a multi-layer cup structure (MLCS) was applied to support a pellet type catalyst. The characteristics of pellet catalyst supported by MLCS and the pellet catalyst supported by conventional structure (CS) were compared by the reforming experiment. In the case of MLCS, a high methanol conversion rate was shown in the temperature range 200 to 300℃ relative to the CS manufactured with the same catalyst weight as MLCS. CS shown similar characteristics to MLCS when it manufactured in the same volume as MLCS by adding an additional 67% of the catalyst. In conclusions, MLCS can not only reduce catalyst usage by improving heat transfer characteristics, but also support pellet catalyst in multiple layers, thus improving shock resistance characteristics.

• 한국정보시스템학회지:정보시스템연구
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• 제17권2호
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• pp.73-94
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• 2008

Knowledge is a fundamental assets, therefore, the ability to create, acquire, integrate, and share knowledge has emerged as a fundamental organizational capability(Sambamurthy and Subramani, 2005). This apaper reports the results of an empirical study investigating the factors of acceptance and the moderating role of resistance in Knowledge Management Systems(KMS). The research model is based on the theory of planned behavior(TPB) and technology acceptance model(TAM). It includes the perceived usefulness instead of attitude, subjective norm, perceived behavior control and intention of acceptance of KMS. Also, three external variables namely task-technology fit, organizational support, and perceived rewards are added. In the research model, all hypothrses of the baseline model and the moderating effects of resistance were found to be significant. The authors also of fred several implications based chi the findings.

• Asian Journal for Public Opinion Research
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• 제10권3호
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• pp.149-177
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• 2022

This study analyzes how inoculation affects the spiral of silence. Inoculation could be a beneficial tool in a democracy as it elevates citizens' resistance to attitude change "forced" by "the winning opinion" in the spiral of silence on a certain controversial issue. The study examines essential variables combined with the theories of inoculation and spiral of silence, such as resistance to counter-attitudinal attack, fear of isolation, and issue-involvement. A two-wave field experiment was employed to assess the formation of public opinion on Taiwan's political future with the People's Republic of China. Results support that inoculation enhanced people's resistance to attitude change and decreased their fear of isolation. Individuals who are more issue-involved were also shown to be more affected by inoculation, which allowed them to resist attitude change. The decreased fear of isolation, coupled with more issue involvement, might elevate people's willingness to speak out in public. More political discussions regarding an important public issue might be expected in a democracy.

• 대한토목학회논문집
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• 제26권6C호
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• pp.407-419
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• 2006

현장타설말뚝이 주면저항력에 의해서만 지지되는 상황은 천공홀 바닥을 청소할 수 없어서 선단부 지지력의 반현 여부를 확신할 수 없을 때이다. 반대로, 신선한 기반암이 낮은 강도의 상부 재료 하부에 있는 경우는 암반에서의 선단지지력만으로 상부 하중을 지탱할 수 있으며, 상부 재료에서는 지지력 발현을 기대하지 않아도 된다. 그러나 신선암에서 일정 깊이 천공을 실시한 경우, 현장타설말뚝은 주면저항력과 선단지지력 모두를 기대할 수 있다. 암반에 근입된 현장타설말뚝의 거동에 관한 이론적 연구와 현장 시험을 통하여 작용 하중의 대부분이 통상 주면저항력에 의해서 지지되게 된다는 사실이 알려져 있다. 암-콘크리트 접촉면에서의 수직응력은 두 가지 기구에 의해 증가하게 된다. 먼저, 말뚝 상부에 작용하는 압축하중에 의해서 콘크리트는 탄성 다이레이션이 발생하고 두 번째로 거친 천공홀 표면에서 전단 변위를 통해서 접촉면의 역학적 다이레이션이 발생되게 된다. 수직 변위에 대한 근입부 주변 물질의 강성도가 일정하면, 작용하중이 증가함에 따라서 수직응력은 증가하게 되며 따라서, 전단강도의 증가 현상이 발생하게 된다. 본 연구에서는 수치해석을 통하여 암반에 근입된 현장타설말뚝의 주면부 거동특성을 조사하였다. 또한, 두부의 하중-침하량(선단부 침하량+말뚝의 탄성변형량) 관계가 비선형성을 띠는 원인 및 파괴기구를 충분히 조사함으로써 암반에 근입된 현장타설말뚝의 주면저항력에 영향을 미치는 요소들을 모두 고려하여 국내 풍화암 및 연암에 근입되는 현장타설말뚝의 설계차트를 제시하고 이를 검증하였다.

• 무역상무연구
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• 제57권
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• pp.243-282
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• 2013

This study aims to develop the research model about the factors that have impact on uTradeHub users' acceptance and resistance to innovation. The followings show the research hypotheses and the results of test. i) The result of H1 empirical analysis confirmed that relative advantage and task adaptedness of e-Trade have more impact on acceptance of innovation than on resistance to it. And also perceived risk and complicity of e-Trade have more impact on resistance of innovation than on acceptance to it. ii) The result of H2 analysis confirmed that the characteristics of foreign trading companies (support by CEO and IT infra maturity) has more impact on acceptance of innovation than on resistance to it. iii) The result of H3 analysis confirmed that characteristics of uTradeHub user' resistance has more impact on resistance of innovation than on acceptance to it. And also, it was confirmed that acceptance of innovation has more impact on the diffusion of e-Trade than resistance to innovation. iv) The result of H4 analysis confirmed that the difference of the degree and factors that has impact on the user's resistance and acceptance by adoption stage of e-Trade. This study has significance in that it arranges the concept and stages of e-Trade systematically and, unlike other studies, it goes beyond the acceptance and diffusion of e-Trade to the inclusion of resistance together in the model.