• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.1395-1398
• /
• 1997

Flexible parts comparing with rigid parts can be deformed by contact force during assembly. for successful assembly, information about their deformation as well as possible misalignment between mating parts is essential. Howecer, because of the complex relationship between parts deformation and reaction forces, it is difficult to acquire all required information from the reaction forces alone. In this paper, we measure parts deformation and misalignments by using the visual sensing system presented for flexible parts assembly. Experimental results show that the system can be effectively used for detecting parts deformation and misalignments between mating parts.

• 정보저장시스템학회논문집
• /
• 제6권2호
• /
• pp.47-51
• /
• 2010

We investigate misalignment characteristics of 5/8 modulation code for holographic data storage. The 5/8 modulation code does not have any isolated patterns that is the most unwanted problem for holographic data storage. As the results, the 5/8 modulation code showed a strong side of misalignments, and the code has the best performance among uncoded, 5/9, and 6/8 modulation codes when there are large misalignments.

• 대한한의학회지
• /
• 제28권3호통권71호
• /
• pp.45-56
• /
• 2007

Objectives : We investigated the possibility of cervical spine misalignment caused by scalenus anticus syndrome to find out how it affects cervical spine misalignments. Methods : 28 patients with scalenus anticus syndrome (sample group), along with 21 participants without neck pain (control group), who attended the Dept. of Oriental Rehabilitation Medicine, College of Oriental Medicine, Dong-guk University from the 20th of June to the 30th of November, 2006 were investigated. After researching misalignments through neutrality, flexion and extension lateral x-ray examination views, we measured the difference of each length of cervical spine misalignment. We analyzed the relationships among the neutrality lateral, flexion lateral and extension lateral positions. Results : We found with statistical significance that there were differences in length of cervical spine misalignments between the sample and control groups. Furthermore, we found that C3 and C4 vertebra bodies were shown in lateral neutrality position, only C3 vertebra body in flexion lateral position, and C2, C3, and C4 vertebra bodies in extension lateral position. Conclusions : It is considered that scalenus anticus syndrome could increase cervical spine misalignment which could be a factor in causing cervical spine disease.

• 한국통신학회논문지
• /
• 제37A권10호
• /
• pp.809-814
• /
• 2012

본 논문은 멀티레벨을 가지는 홀로그래픽 저장 장치에서 EM (Expectation-maximization) 알고리즘을 이용한 적응 문턱전압검출기를 제안한다. 멀티레벨을 이용한 홀로그래픽 저장 장치의 경우 DC 오프셋의 정도에 따라 비적응 문턱전압검출기의 성능에 매우 심각한 영향을 미친다. EM 방법은 채널을 통과한 데이터를 이용해 Expectation step과 maximization step을 반복하면서 평균과 분산을 추정하는 방법이다. DC 오프셋이 있는 상황에서 제안된 방법을 적용하여 문턱값을 찾아내서 검출한 결과 일정한 한도 내의 DC 오프셋의 경우는 DC 오프셋이 없는 경우와 동일한 성능을 보였다.

• 제어로봇시스템학회논문지
• /
• 제5권7호
• /
• pp.841-847
• /
• 1999

For successful assembly of flexible parts, informations about their deformation as well as possible misalignments between the holes and their mating parts are essential. Such informations can be acquired from visual sensors. For robotic assembly, the corrective assembly motion to compensate for such misalignments has to be determined from the measured informations. However, this may not be simply derived from the measured misalignment alone because the part deformation progressively occurs during misalignment compensation. Based on the analysis of flexible parts assembly process, this paper presents a neural net-based inference system that can infer the complex relationship between the corrective motion and the measured information of parts deformation and misalignments. And it verifies the performance of the implemented inference system. The results show that the proposed neural net-based misalignment compensation algorithm Is effective in compensating for the lateral misalignment, and that it can be extended to the assembly tasks under more general conditions.

• 대한전자공학회논문지TC
• /
• 제42권2호
• /
• pp.17-22
• /
• 2005

본 논문에서는 OFDMA 역방향 시스템에서 시간오차에 의한 사용자간 간섭을 분석하고 역방향 수신기의 성능 열화 정도를 제시한다. 이를 위해, 각 사용자의 서로 다른 시간오차를 기준 사용자 대한 상대적인 시간오차로 표현한다. 그리고 역방향 수신기의 평균 신호대 간섭잡음비를 상대적인 시간오차의 최대값을 변수로 갖는 함수로 유도한다. 분석결과는 상대적인 시간오차 증가에 의한 평균 신호대 간섭잡음비의 성능 열화로 확인하였다. 또한, 데이터 부반송파 사이의 보호 부반송파를 사용하여 상대적인 시간오차에 의한 사용자간 간섭의 영향을 감소시킬 수 있음을 확인하였다.

• 한국강구조학회 논문집
• /
• 제16권4호통권71호
• /
• pp.479-492
• /
• 2004

본 연구에서는 강상판의 U리브를 현장에서 상향의 용접자세로 용접이음을 실시할 경우, 용접이음부에는 시공오차에 의한 단차가 발생하고, 응력집중이 발생하기 쉽다. 따라서 본 연구에서는 이면재가 부착된 용접이음부에 대해 응력해석 및 실험을 실시하였다. 이면재가 부착된 U리브 용접이음부의 단차, 루트부 형상, 루트갭 및 이면재의 폭과 두께를 변화시켜 응력해석을 실시한 결과, 단차가 커질수록 응력집중계수는 현저히 증가하였으며, 루트갭도 커질수록 응력집중계수가 증가하는 것을 알 수 있었다. 또한 단차 및 루트갭이 동일한 경우에는 루트부 형상이 직각인 경우보다 반원인 경우에 응력집중계수가 작게 나타났으며, 이면재의 폭 및 두께는 응력집중계수에 그다지 영향을 미치지 않는 것으로 나타났다. 이면재가 부착된 시험편의 피로실험에서는 단차가 커질수록 피로수명이 현저히 저하되었으며 피로균열은 이면재가 부착된 모재측 루트부에서 발생하여 용접비드 표면측으로 전파하였다. 응력해석에서 루트부의 형상이 반원인 경우, 응력집중계수가 작게 나타나므로, 용접조건을 변화시켜 루트부 곡률반경 및 플랭크각을 제어하는 루트부 형상제어법를 개발하였다.

• 전자공학회논문지A
• /
• 제32A권1호
• /
• pp.36-44
• /
• 1995

For a parabolic reflector antenna, a simple method is presented for computing efficiently the average power pattern degradations caused by the surface roughness of the reflector and misalignments between the reflector and the feed. In this procedure, both nonuniform surface errors and nonuniform illuminations are employed. The assumptions to derive the expressions are that in each annular region of the antenna, the rms value of the surface roughness is known, and in a zone in a annular region, the phase error by misalignments is constant, and can be taken to its value at the center of the zone. Detailed parametric studies are performed with derived expressions to determine the effects of those errors and illumination tapers on parameters such as gain and sidelobe levels.

• 한국강구조학회 논문집
• /
• 제8권3호통권28호
• /
• pp.13-20
• /
• 1996

With the adoption of welded joints rather than bolted joints, we investigate the fatigue strength and the fatigue crack initiation of U-type trough rib and welded specimen with misalignment in a steel deck plate. The stress concentration factor of welded specimens with a misalignment is also verified by a finite element method. The main conclusions obtained from this study are as follows Experimental results of full-scaled U-type trough rib models have indicated that fatigue life depends on misalignments of welded joints in steel deck plate ; The more misalignments are, the less the fatigue life is. It has also shown that fatigue crack propagates from the welded root to the bead surface. We have also obtained the same results from both the fatigue test of welded specimens with a misalignment and the stress analysis of a finite element method.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.155-160
• /
• 2008

Using a three-dimensional (3-D) FE analyses, this paper provides the shape optimization of the standard test specimen for the torsion test, as well as a method for analyzing effects of misalignment under the angular and concentric misalignment. For verification, FE analysis is performed, which is designed for the perfectly full-model. To optimize the design shape of the torsion-controlled fatigue test specimen, we performed sensitivity analysis using shape parameters. Additionally, two kinds of misalignment (angular misalignment and concentric misalignment) are applied to the circular and tubular specimens to show effects of misalignments in the FE analysis. The present results will provide valuable information for designing shafts for every kind of mechanical system under torsional force.