• Composites Research
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• v.20 no.5
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• pp.34-42
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• 2007

Strength and failure of adhesively bonded carbon composite-to-aluminum single-lap joints were studied by experiment. The main objective of this study is to investigate the effect of various parameters such as curing pressure for bonding, overlap lengths, and adherend thickness on the failure loads and modes of the bonded Joints with dissimilar materials. Experimental results show that the bonding pressure for composite-to-aluminum dissimilar materials should be 4 atm at the lowest. Failure load of the joints increases as the overlap length increases, but the strength (failure load divided by bonded area) decreases rapidly after the overlap width-to-length ratio is greater than 1. When the adherend thickness increase to double, bonding strength increase $12{\sim}55%$. Major failure mode of the joints is the delamination in the composite laminate and the location of delamination goes deeper into the laminates as the bonding pressure and overlap length increase.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.562-567
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• 2000

Many pressure vessels for power and industrial plant are fabricated from low alloy carbon steels. The inner sides of pressure vessels are commonly weld-cladded with austenitic stainless steels to minimize problems of corrosive attack. Disbonding cracks are often detected at the transition region of welding interlayer, which is serious problem to reliability of pressure vessels. We have developed C-scan system to high speed inspection of overlay weld using DSP(digital signal processor). This system consists of signal processing parts (oscilloscope, pulser/receiver, digitizer, DSP), scanner, program and position controller. The developed system has been applied to a practical ultrasonic testing in overlay weld, and demonstrated high speed with precision

• Journal of the Mineralogical Society of Korea
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• v.31 no.3
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• pp.161-172
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• 2018

Multi-anvil press (MAP) is one of the high pressure apparatuses and often generates the pressure-conditions ranging from 5 to 25 GPa and temperature-conditions up to $2,300^{\circ}C$. The MAP is, therefore, suitable to explore the pressure-induced structural changes in diverse earth materials from Earth's mantle and the bottom of the mantle transition zone (~660 km). In this study, we present the experimental results for pressure-load calibration of the 1,100-ton multi-anvil press equipped in the authors' laboratory. The pressure-load calibration experiments were performed for the 14/8 step, 14/8 G2, 14/8 HT, and 18/12 assembly sets. The high pressure experiments using ${\alpha}$-quartz, wollastonitestructure of $CaGeO_3$, and forsterite as starting materials were analyzed by powder X-ray diffraction spectroscopy. The phase transition of each mineral indicates the specific pressure that is loaded to a sample at $1,200^{\circ}C$: a transition of ${\alpha}$-quartz to coesite at 3.1 GPa, that of garnet-structure of $CaGeO_3$ to perovskite-structure at 5.9 GPa, that of coesite to stishovite at 9.2 GPa, and that of forsterite to wadsleyite at 13.6 GPa. While the estimated pressure-load calibration curve is generally consistent with those obtained in other laboratories, the deviation up to 50 tons is observed at high pressure above 10 GPa. This is partly because of the loss of oil pressure at high pressure resulting from the differences in a sample chamber, and the frictional force between pressure medium and second anvil. We also report the ${\sim}200^{\circ}C/mm$ of thermal gradient in the vertical direction of the sample chamber of 14/8 HT assembly. The pressure-load calibration curve and the observed thermal gradient within the sample chamber can be applied to explain the structural changes and the relevant macroscopic properties of diverse crystalline and amorphous earth materials in the mantle.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.32-39
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• 2018

In this paper, the calculation of the theoretical pressure transfer ratio due to the deformation of the thin-plate spring type check valve applied to the small piezoelectric-hydraulic pump was carried out. A thin-plate check valve is a flexible body that is deformed by an external force. The deformation of the check valve affects the rate at which the chamber pressure is transferred to the load pressure. The theoretical pressure transfer ratio for each model was calculated to compare the difference between the assumption that the thin-plate check valve is a rigid body and that of the flexible body model. The P-delta effect was considered for the calculation of the pressure transfer ratio of the flexible check valve model. In addition, a verification test for the calculated pressure transfer ratio obtained by considering the deformation of the flexible check valve model was carried out. The load pressure was measured by applying a thin-plate and ball-thin plate spring type check valves, respectively. The experimental pressure transfer ratio was calculated using the respective load pressure obtained from the experiments. The validity of the pressure transfer analysis of the check valve, taking into consideration the P-delta effect, was verified by comparing it with the theoretically calculated pressure transfer ratio.

• Annual Conference on Human and Language Technology
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• 1989.10a
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• pp.178-182
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• 1989

본 논문용 preview 기능을 갖는 한글 전자출판 시스템에 관한 것이다. 논리구조와 레이아웃 구조로 구조화된 문서를 작성 할 수 있는 문서작성 전용 에디터를 설계하였다. 이는 문서내용의 논리적 특성에 맞게 문서를 작성할 수 있는 내용 중심의 문서작성 에디터로, high level 적으로 문서를 만들 수 있게 한다. 아울러 문서내에서 context sensitive 한 성질을 갖는 그림 및 도표의 영역은 시스템이 자동으로 할당하도록 하는 알고리즘을 구현하였다. 이렇게 자동 할당된 그림 및 도표의 위치와 크기를 페이지 단위로 이동, 조정 할 수 있게 하므로서 이에 따른 텍스트도 적응적으로 처리되게 하였다. 또한 레이아웃 처리된 출력결과를 하드카피 하기 전에 디스플레이상에서 확인할 수 있는 preview 기능을 설계하였다. 본 시스템은 크게 압력부, 레이아웃 처리부, preview부, 출력부로 구성된다. 본 논문에서는 압력부와 레이아웃 처리부, preview부에 중점을 두어 설명하고 처리된 문서의 출력 결과를 보인다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.328-330
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• 2016

내시경을 이용한 진단 및 시술은 빈번하게 이루어지고 있으며, 대장암의 증가와 정부의 암 조기검진사업의 영향으로 시행건수가 많아지면서 천공 및 출혈 등의 의료사고도 늘어나고 있다. 내시경 장비를 이용한 시술은 시술자의 경험이나 감각, 숙련도에 의존하여 시행된다. 내시경 시술시 내시경 선단부의 수평 및 수직, 압력에 대한 실시간 정보를 제공하면 의료사고를 줄일 수 있다. 본 논문에서는 가속도와 자이로센서를 융합하여 각도 및 자세정보를 얻고 압력센서를 이용하여 선단부가 받는 압력을 시술자에게 제공하여 내시경 시술시 천공 및 출혈 등의 의료사고를 줄일 수 있는 방안을 제시한다.

• Composites Research
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• v.20 no.2
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• pp.1-9
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• 2007

To evaluate and investigate the aging characteristics and the structural service lifetime of the CFV(carbon fiber pressure vessel), natural aging tests were carried out using the CFVs, which had been placed and aged at outdoor and indoor laboratories for 10 and 15 years, respectively. To obtain the probabilistic characteristics of ageing characteristics in aged CFVs, inner pressure loading test was conducted with ring specimens taken from aged CFVs. And, to observe the interface morphology of aged CFVs, the micro-photographs were taken by SEM microscope and the fractured interfaces between the carbon fiber and the matrix resin were scrutinized. Based on the Weibull parameters of the tensile failure strain of aged CFVs, the degradation of the 10 and the 15 year aged CFV occur by 19% and 23%, respectively, and the effect of the placement, whether being placed inside the laboratory or not, is not so significant. However, the outer layer protection, such as painting, is found very advantageous to prevent CFV from aging.

• Proceedings of the Korea Contents Association Conference
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• 2019.05a
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• pp.341-342
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• 2019

본 연구는 기능성 신사화 착용이 즉각적인 선자세 족저압력 분포 변화에 미치는 영향을 확인하고자 하였다. 남성 물리치료사 8명을 대상으로 하루 간격을 두고 동일한 대상에게 일반적 신사화와 기능성 신사화를 착용하고 선 자세 동안 높은 족저압력의 발과 낮은 족저압력의 발간에 족저압력 분포를 비교하였다. 비교 분석 결과, 일반화를 착용한 선 자세에서 높은 족저압력의 발과 낮은 족저압력의 발간에 족저압력 비율이 유의한 차이를 보였지만 기능성 신사화에서 유의한 차이를 보이지 않았다. 그리고 높은 족저압력 분포 발에서 기능성 및 일반적 신사화간에 전족부와 후족부의 압력이 차이를 보였다. 선 자세에서 기능성 신사화가 일반적 신사화 보다 즉각적으로 정상 생리적 자세를 유도하는 것으로 보였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.67-74
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• 2006

An unsteady blockage-correction method utilizing wall pressure distribution on the test section has been developed for the wall interference correction of a closed test-section subsonic wind tunnel. The pressure distribution along the test section wall was decomposed into Fourier series and a quasi-steady method based on a measured-boundary-condition method was applied to each Fourier coefficient. The unsteady correction for a complete test period was accomplished by recombining each corrected terms. The present method was validated by appling computed unsteady flows over a cylinder and an oscillating airfoil in the test sections. The corrected results by the present method agreed well with free-air condition.

• Tunnel and Underground Space
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• v.25 no.5
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• pp.423-434
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• 2015

Scaled model tests were performed to investigate the influence of pillar width, rock strength and isotropy/anisotropy on the stability of twin tunnels. Test models had respectively different pillar widths, uniaxial compressive strengths of modelling materials and model types, where both the deformation behaviors around tunnels and the biaxial pressure data at a time of pillar cracking were analysed. The cracking pressures of the higher strength models were higher than the lower strength models, whereas the percentage of cracking pressure to uniaxial compressive strength of modelling materials showed an opposite tendency. The cracking pressures of the shallower pillar width models were lower than the thicker models, moreover the percentage of that showed a same tendency. It has been found that the pillar width was one of the main factors influencing on the stability of twin tunnels. Model types such as isotropy/anisotropy also influenced on the stability of twin tunnels. The anisotropic models showed lower values of both cracking pressures and the percentage of that than the isotropic models, where the pillar cracks of anisotropic models were generated with regard to the pre-existing joint planes.