• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.10a
• /
• pp.179-182
• /
• 2001

Impacter tester was build of to evaluate the characterization of non-flamable Glass/phenol laminate plates under the low velocity impact. The damage of composite laminates are matrix cracking, delamination, and fiber breakage for impact energy. In this study, this is to find impact properties of Glass/phenol in used in a forehead part of lighting subway. To determine impact damage characteristics which is made in a laminate, use the UT C-scan after- macrography. And then evaluated the reduction of strength in a rate of impact energy with CAI(Compression After Impact) test

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2005.04a
• /
• pp.67-70
• /
• 2005

The carbon fiber reinforced/epoxy laminated composites were fabricated with initial fiber failures within the unidirectional fiber pre-pregnated ply. The fiber failures were made intentionally either parallel to and/or perpendicular to the unidirectional fibers within the ply. The pre-made clear-cut cracks were found to be healed partially after laminating process. The laminates were impacted with or without initial fiber failures within the laminates. The force versus deflection curves were compared. The partially healed laminates showed the reduced laminate stiffness as compared to those without any intentional fiber failures. The impact curves were compared with size and the location of the initial failures varied.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.19-24
• /
• 2004

The mode I stress intensity factor ($K_I$) of a newly proposed slow-crack-growth-test (Notched Ring Test, NRT) specimen was found using finite-element method. The theoretical $K_I$ value of NRT was not available in any references and could not be solved analytically. At first, in order to verify the accuracy of the finite-element approach, published $K_I$ values of several cracks were calculated and compared with finite-element results. The results were in excellent agreement within inherent errors of theoretical $K_I$. Finally the $K_I$ of NRT was found using 2- and 3-dimensional finite-element methods and expressed as a function of the applied load.

• Journal of the KSME
• /
• v.20 no.6
• /
• pp.474-488
• /
• 1980

이제까지의 결과를 종합하여 보면 다음과 같은 결론을 얻을 수 있다. 1. 국산 비피막공구는 의 산에 비하여 많은 절삭영역에서 양호한 성능을 가지고 있다. 2. 국산 비피막공구 W2는 중간 절 삭 영역에서 국산 W1과 외산 W3, W4보다 우수한 성능을 나타낸다. 3. W1은 저속이거나 절삭 깊이가 클 때, W2보다 좋은 성능을 가진다. 4. W1은 대체로 플랭크 마모에 의하여, W2는 저속. 저이송에서는 프랭크마모 그리고 그밖의 영역에서는 크레이터 마모에 의하여 수명이 결정된다. 5. 국산 피막공구 CW7은 외산 CW10, 13에 비하여 내마모성이 매우 좋다. 6. 중간절삭영역에서 W 2의 표면조도는 W1, W3, W4에 비하여 훨씬 좋다. 7. 피막층 유무와 피막재질에 따른 국산 및 외산의 절삭력 차이는 거의 없다.

• Journal of Korea Society of Industrial Information Systems
• /
• v.20 no.1
• /
• pp.27-35
• /
• 2015

In this paper, we suggested a RS485 based CSMA/CD protocol that is available in low speed multi-node networks such as industry control communication network and home network etc. The suggested protocol was compared to widely used Master-Slave protocol, Modbus. We modeled realistic control network and showed that the average delay and throughput performance were significantly improved in the different transmission rates.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.865-868
• /
• 2002

This study investigated the shape deformation of ball projectile(5.56mn) under the low energy impact by the use of the drop weight impact tester. ball projectile(5.56mm) consisted of the copper face with a lead core. The impact conditions were changed with the variations of the mass and the drop height of the impact tup. Shape deformation of ball projectile(5.56mm) after low velocity impact was measured using a video microscope and CCD camera. The test result showed that impact energy by changing of drop height of the impact tup affected shape deformation of ball projectile(5.56mm). So, it is important to study the relativity between shape deformation of ball projectile(5.56mm) and ballistic protection of plate(such as hybrid composite laminates) under the high velocity impact.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2003.05a
• /
• pp.123-127
• /
• 2003

본 실험은 자동차 시뮬레이터의 속도 변화(40, 70, 100km/h)와 롤러코스터 시뮬레이터의 운동성 구현 방법(washout 필터 적용, washout 필터 비적용) 에 따른 인간 감성을 탑승자의 주관적 평가를 통하여 비교 평가하였다. 자동차 시뮬레이터, 롤러코스터 시뮬레이터 실험은 각각 건강한 20대 남자 12명, 8명을 대상으로 simulator sickness, 쾌적감, 긴장감, 각성감, 속도감에 대한 주관적 평가를 실시하였다. 결과, 자동차 시뮬레이터에서의 저속주행보다 운동형태가 다양한 롤러코스터 시뮬레이터 주행시 쾌적감, 긴장감, 각성감, 속도감이 유의하게 높았다. 즉 자동차 시뮬레이터에서는 주행시 주행속도가 증가함에 따라 운전자의 감성의 정도는 상승하였고 시뮬레이터간 비교에서는 자동차 시뮬레이터의 저속 주행에 비해 롤러코스터 시뮬레이터 주행시 감성변화는 더 컸다. 이상에서 시뮬레이터 구현 방법에서 속도 요소와 다양한 운동성 요소가 탑승자의 감성에 영향을 주는 것으로 나타났다.

• 한국전산유체공학회:학술대회논문집
• /
• 2004.03a
• /
• pp.106-112
• /
• 2004

A kinetic theory analysis is made of low-speed gas flows around a micro-plate. The Boltzmann equation simplified by a collision model is solved by means of a finite difference approximation with the discrete ordinate method. The method does not suffer from statistical noise which is common in particle based methods and requires much less amount of computational effort. Calculations are made for flows around a micro-scale flat plate with a finite length of 20 microns. The method is assessed by comparing the results with those from several different methods and available experimental data.

• Annual Conference of KIPS
• /
• 2017.04a
• /
• pp.529-531
• /
• 2017

현재 IT 기술의 발전에 힘입어 선박 내에 발생하는 전자 데이터를 통해 선박 제어, 자율 운항, 상황 발생 시 정보 제공 등의 기능을 할 수 있는 전자 운항 선박이 등장하였다. 국내 선박용 항해 통신 장비 업체들에서 제작된 장비들은 NMEA 0183 표준 규격을 따르고 있다. 그러나, 이러한 표준규격 내에서의 저속의 데이터 전송으로 인한 향후 NMEA-2000에서의 멀티미디어 전송 및 USN 장비 호환을 위해서는 보다 효율적인 전송 처리 방안이 필요하며, 나아가 이더넷을 기반으로 하는 선박 제어가 필요로 하게 된다. 이러한 문제를 해결하기 위해서는 저속과 고속 데이터 전송시에 보다 효율적인 전송 방안을 고려하여야 하며, 또한 그러한 방안이 기존의 선박 전자 장비와 원활히 연동될 수 있도록 고려하여야 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.11
• /
• pp.967-974
• /
• 2017

Reaction wheel shows nonlinear torque response on low-speed region due to friction. Thus precise satellite attitude control on this region is hard to achieve. Previous research tries to solve this problem, by compensating friction or applying dither command. However, due to difficulties of drag torque modeling or frequent zero wheel speed crossing, these methods are not suitable to apply on the real satellite attitude control. To solve this problem, we propose the attitude controller gain adjustment method based on the attitude error.