• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.349-354
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• 2001

In this study, we investigated the effect of the impacting ang1e of particles, the scanning times and the stand-off distance on the surface roughness and the weight-loss rate of samples with no mask, and the wall profile and overetching of samples with different mask pattern in powder blasting of soda-lime glass. The varying parameters were the different impact angles between 50$^{\circ}$ and 90$^{\circ}$, scanning times of nozz1e up to 40 and the stand-off distances 70mm and 100mm. The widths of mask pattern were 0.2mm, 0.5mm and 1mm. The powder was alumina sharp particles, WA#600. The mass flow rate of powder during the erosion test was fixed constant at 175g/min and the blasting pressure of powder at 0.2MPa

• 한국전산구조공학회논문집
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• 제27권6호
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• pp.615-624
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• 2014

LNG 방열 시스템의 선형 동적해석 모델을 사용하여 슬로싱 충격 압력을 구조해석에 적용 시 사용되는 이상화된 삼각파 압력에 대해서 검토하였다. 삼각파 압력의 최대값, 지속시간, 비대칭성의 충격파에 대한 구조 안전성 평가를 위해서 멤브레인 구조의 허용기준과 슬로싱 압력에 관련된 간략화된 파괴압력에 대해 검토하고, 슬로싱 충격 압력의 지속시간과 비대칭성으로 특징 지워진 이상화된 삼각파 형상의 압력을 고려한 일련의 선형 동적해석을 수행하여 설계기준으로 사용할 파괴압력을 도출하였다. 본 논문에서 제시한 방법을 통해서 방열시스템 구조 요소의 안전성을 평가하기 위한 파괴 압력을 선정할 수 있고 모형실험을 통한 슬로싱 압력과의 비교를 통하여 방열시스템의 구조안전성을 평가할 수 있을 것이라 판단된다. 또한 해석결과를 통해 방열시스템에서의 최대 응력은 매우 짧은 순간의 충격하중 하에서는 압력의 비대칭성 보다는 하중 지속시간에 많은 영향을 받고 있음을 검토하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1467-1469
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• 2002

This paper aims to investigate the characteristics of braided thermoplastic and thermosetting composite and pressure relief for polymer arrester. In general, braided composite has potential for improved impact and delamination resistance. Manufacturing processes of the braided composite could also be automated and could potentially lead to lower costs. Therefore, in consideration of characteristics of pressure relief for polymer arrester, the fabric pattern of braided composite was studied. And polymer arrester module was manufactured with braid.

• Structural Engineering and Mechanics
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• 제59권5호
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• pp.795-802
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• 2016

Gas pipelines are types of structures that are highly susceptible to corrosion. Sometimes, the pipes are subjected to a thinning of the wall thickness at the inside or outside wall due to erosion/corrosion. Therefore, it is important to evaluate the strength of the pipes undergoing corrosion to maintain the integrity of the piping systems. The main purpose of this study is to understand failure aspects caused by degradation of metal due to corrosion through. The ASME standard offers a relationship for the yielding pressure of the corroded pipes which was compared with the finite element results. The results demonstrate to obtain accurate results, the ASME relationship is unreliable. Moreover, pitting corrosion must be considered critical more than of other types.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1109-1112
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• 2004

This study reports on the pressure relief design and braided composite of surge arrester. Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. As a solution, this study describes pressure relief design performance of arresters with braided composite module. In general, braided composite has Potential for improved impact and delamination resistance. Manufacturing processes of the braided composite could also be automated and could potentially lead to lower costs. Therefore, in consideration of characteristics of pressure relief for polymer arrester, the fabric pattern of braided composite was decided. And Polymer arrester module was manufactured with braid. The mechanisms of pressure occurrence and relief were investigated basically by analyzing arc energy and the correlation between thermal shock and indoor pressure in pressure relief test.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권2호
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• pp.227-245
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• 2013

Reliable strength assessment of the Liquefied Natural Gas (LNG) cargo containment system under the sloshing impact load is very difficult task due to the complexity of the physics involved in, both in terms of the hydrodynamics and structural mechanics. Out of all those complexities, the proper selection of the design sloshing load which is applied to the structural model of the LNG cargo containment system, is one of the most challenging one due to its inherent randomness as well as the statistical analysis which is tightly linked to the design sloshing load selection. In this study, the response based strength assessment procedure of LNG cargo containment system has been developed and proposed as an alternative design methodology. Sloshing pressure time history, measured from the model test, is decomposed into wavelet basis function targeting the minimization of the number of the basis function together with the maximization of the numerical efficiency. Then the response of the structure is obtained using the finite element method under each wavelet basis function of different scale. Finally, the response of the structure under entire sloshing impact time history is rapidly calculated by synthesizing the structural response under wavelet basis function. Through this analysis, more realistic response of the system under sloshing impact pressure can be obtained without missing the details of pressure time history such as rising pattern, oscillation due to air entrapment and decay pattern and so on. The strength assessment of the cargo containment system is then performed based on the statistical analysis of the stress peaks selected out of the obtained stress time history.

• 한국의류학회지
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• 제35권9호
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• pp.1039-1048
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• 2011

This research develops a basic design structure for scuba diving wetsuits suitable for the shape of Korean men in their 30's as well as enhances the reduction rate for underwater activity. The clothing pressure and fitness tests were performed using four different types of body suits. The usable data of the tests were coded for further statistical analysis that includes one way-ANOVA test and S-N-K Multiple Range Test by using SPSSWIN 17.0. An analysis of the results shows: (1) The results of the clothing pressure test (using a dummy) indicated that the larger the reduction rate, the stronger the clothing pressure gets (with an exception on the knee area). It has great impact on clothing pressure with regards to the different body parts. The different reduction rates should be applied to body parts accordingly. (2) In the case of test subjects, the overall mean values of the clothing pressure were lower than the ones with the dummy (attributable to the cushion function of body skin and muscle as well as the high stretch of the fabric). (3) In evaluating the subjective fit test of four types of body suits, a statistically significant difference was found in the relation between pattern reduction rates and all parts of the body. It was revealed that the reduction rate of 'B' pattern (X: 4%, Y: 3%) was the most suitable pattern and the 'B' pattern scored highest in the motion functional fit test performed by a test subject.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.181-184
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• 2014

Loose Parts Monitoring System(LPMS) monitors loosened or detached parts and foreign parts inside the pressure boundary of a reactor coolant system (RCS). It is difficult to discriminate valid signal from LPMS alarms at full power since the signal pattern by thermal shocks and structure friction are similar to those by loose metal impacts. In addition, It is more difficult to discriminate the impact signals induced by the rod driving, sensor hard-line movement and loosened component since they have similar frequency characteristics with valid signals. This paper classifies the signal patterns by analyzing actual LPMS signal captured during nuclear power plant operation.

• 대기
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• 제25권4호
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• pp.611-622
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• 2015

Heavy rainfall ($>30mm\;hr^{-1}$) over the Korean Peninsula is examined in order to understand thermo-dynamic characteristics of the atmosphere, using radiosonde observational data from seven upper-air observation stations during the last 17 years (1997~2013). A total of 82 heavy rainfall cases during the summer season (June-August) were selected for this study. The average values of thermo-dynamic indices of heavy rainfall events are Total Precipitable Water (TPW) = 60 mm, Convective Available Potential Energy (CAPE) = $850J\;kg^{-1}$, Convective Inhibition (CIN) = $15J\;kg^{-1}$, Storm Relative Helicity (SRH) = $160m^2s^{-2}$, and 0~3 km bulk wind shear = $5s^{-1}$. About 34% of the cases were associated with a Changma front; this pattern is more significant than other synoptic pressure patterns such as troughs (22%), migratory cyclones (15%), edges of high-pressure (12%), typhoons (11%), and low-pressure originating from Changma fronts (6%). The spatial distribution of thermo-dynamic conditions (CAPE and SRH) is similar to the range of thunderstorms over the United States, but extreme conditions (supercell thunderstorms and tornadoes) did not appear in the Korean Peninsula. Synoptic conditions, vertical buoyancy (CAPE, CIN), and wind parameters (SRH, shear) are shown to discriminate among the environments of the three types. The first type occurred with high CAPE and low wind shear by the edge of the high pressure pattern, but Second type is related to Changma front and typhoon, exhibiting low CAPE and high wind shear. The last type exhibited characteristics intermediate between the first and second types, such as moderate CAPE and wind shear near the migratory cyclone and trough.

• Structural Engineering and Mechanics
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• 제55권2호
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• pp.263-280
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• 2015

This paper describes a study of the collision of hard steel spheres against aluminium thin circular plates at speeds up to 140 m/s. The tests were monitored by a high speed camera and a chronoscope, which allowed the determination of the ballistic limit and the plate deformation pattern. Quasi-static material parameters were obtained from tests on a universal testing machine and dynamic mechanical characterization of two aluminium alloys were conducted in a split Hopkinson pressure bar. Using a damage model, the perforation of the plates was simulated by finite element analysis. Axisymmetric, shell and solid elements were employed with various parameters of the numerical analysis being thoroughly discussed, in special, the dynamic model parameters. A good agreement between experiments and the numerical analysis was obtained.