• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.319-322
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• 2003

For the analysis of leveling process by the 3-dimensional elastic-plastic finite element method, a finite element analysis program modeling large deformation of shell has been developed. This program fur analyzing large deformation of sheet during leveling includes spring-back analysis as well as efficient contact treatment between sheet and rolls of leveler. This is verified by the simple leveling experiment with 5 rolls at laboratory. Besides the leveling examples, problems within the category of large strain and rotation, such as 3-dimensional roll-up and gutter occurrence at continuous bending-unbending process are also tested for verification of the program. The residual curvatures of strip predicted by finite element analysis are within 20% error range of the experiment. The formation and direction of anticlastic curvature or gutter during bending-unbending under tension is predicted and this agrees with the experimental results.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.182-194
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• 1999

Occupant injury in rear end impact is rapidly becoming one of the most aggravating traffic safety problems with high human suffering and societal costs. Although rear end impact occurs at relatively low speed , it may cause permanent disability due to neck injuries resulting from an abrupt moment, shear force , and tension/compression force at the occipital condyles. The analysis is performed for a combined occupant-eat model response, using the SAFE(Safety Analysis for occupant crash Environment) computer program. The computational results are verified by those from sled tests. A parameter study is conducted for many physical and mechanical properties. Seat design has been performed based on the design of experiment process with respect to five parameters; seat-back upholstery stiffness, torsional stiffness of the seat-back. An orthogonal array is selected from the parameter study. A good design has been found from the analysis results based on the orthogonal array. The results show that reductions of stiffness in seat-back upholstery and joint are the most effective for preventing neck injuries.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제36권1호
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• pp.28-38
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• 2010

The factors influencing the relapse and recurrence of skeletal deformity after the orthognathic surgery include various factors such as condylar deviation, the amount of mandibular set-back, stretching force by the soft tissues and muscles around the facial skeleton. The purpose of this report is to recognize and analyze the possible factors of reoperation after orthognathic surgery, due to early relapses. Six patients underwent reoperation after the orthognathic surgeries out of 110 patients from 2006 to 2009 were included in this study. In most cases, clincal signs of the insufficient occlusal stability, anterior open bite, and unilateral shifting of the mandible were founded within 2 weeks postoperatively. Although elastic traction was initiated in every case, inadequate correction made reoperation for these cases inevitable. The chief complaints of five cases were the protruded mandible combined with some degree of asymmetric face and in the other one case, it was asymmetric face only. Various factors were considered as a major cause of post-operative instability such as condylar sagging, counter-clockwise rotation of the mandibular segment, soft tissue tension related with asymmetrical mandibular set-back, preoperatively existing temporomandibular disorder (TMD), poor fabrication of the final wafer, and dual bite tendency of the patients.

• 대한기계학회논문집A
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• 제30권3호
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• pp.269-278
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• 2006

This paper proposes slip line fields for bending of unequally notched specimens in plane strain that have a sharp crack in one side and a sharp V-notch in the other side. Depending on the back angle, two slip line fields are proposed, from which the limit moment and crack tip stress fields are obtained as a function of the back angle. Excellent agreement between slip line field solutions with those from detailed finite element limit analysis based on non-hardening plasticity provides confidence in the proposed slip line fields. One interesting point is that, for the unequally notched specimen, the difference between the crack tip triaxial stress for tension and that for bending increases significantly with increasing the back angle. This suggests that such a specimen could be potentially useful to investigate the crack tip constraint effect on fracture toughness of materials. In this respect, the possibility of designing a new toughness testing specimen with varying crack tip constraint is discussed.

• Asia Pacific Journal of Business Review
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• 제4권2호
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• pp.23-33
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• 2020

Uzbekistan has been gradually integrating into the world economy since gaining its independence back in 1991. The need to integrate stems from the desire to advance the national economy and social well-being of population through importing advanced technologies or stimulating exports. However, opening up the country also meant exposure to increase in the mobility of its human capital. As a result, Uzbekistan has witnessed labor migration in and out of the country in the past couple of decades, driven by various causes, which is having inevitable social and economic implications for the country. Intensifying processes in contemporary international labor market make migration as a mechanism, which has a back-to-back impact onto and from economic development of a country. From developing countries' perspective, international labor migration is an instrument for reducing tension in national labor markets, decreasing high rates of unemployment and expanding sources of income. From developed countries' perspective, international labor migration helps solve demographic problems like decreasing number of population, aging of population and shortage of labor force. Thus, this processes turned into a mechanism or a system, which is not possible to ignore. Uzbekistan, in particular, is increasing its participation in the international labor market due to its high rates of population growth and young population.

• 감성과학
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• 제12권4호
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• pp.373-380
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• 2009

본 연구에서는 세 단계의 각성 수준이 3-back 과제 수행능력에 어떠한 영향을 미치는지 관찰하고자 하였다. 10명의 남자(평균 $25.7{\pm}1.5$세) 대학생과 10명의 여자(평균 $24.5{\pm}1.8$세) 대학생이 본 실험에 참여하였다. 집단검사를 통해 추출된 사진을 이용하여 세 단계의 각성 수준 즉, 긴장, 중립, 이완감성을 유발하였다. 모든 피험자는 각 각성 수준에 대해 한 번씩, 총 3번의 실험에 참여하였다. 안정1(2분), 각성유발사진제시1(2분), 3-back 과 제1(2분), 각성유발사진제시2(2분), 3-back 과제2(2분), 안정2(2분)의 6단계로 실험이 진행되었고, 전 단계에서 피부전도수준(skin conductance level: SCL)도 함께 측정하였다. 3-back 과제의 정답률은 중립 조건일 때 가장컸고, 이완, 긴장 조건 순서였다. 반응시간은 세 조건 간의 차이가 나타나지 않았다. 모든 구간에서 측정된 피부전도수준은 긴장 조건일 때 가장 컸고, 중립, 이완 순서로 나타남으로써, 사용된 각성유발사진이 적절한 각성수준을 유발하였음을 확인하였다. 본 연구결과로부터 인지 처리와 무관하게 유발된 긴장도의 증가나 감소는 과제 수행능력을 감소시킬 수 있다는 사실을 유추할 수 있다.

• 디지털정책학회지
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• 제3권1호
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• pp.21-25
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• 2024

본 연구는 엉치엉덩관절의 불안정성에 초점을 맞춘 테이핑 방법이 요통에 도움이 될 수 있는 잠재 중재 방법인지에 대해 고려해 보고자 한 사례연구이다. 해당 사례는 58세 과거 디스크탈출증 및 협착증으로 인해 허리 수술 병력이 있는 남성이 지속적인 통증 감소를 위해 참여한 테이핑 교육 세션에서 나타난 주목할 만한 결과를 사례로 정리하였다. 중재 방법으로 테잎을 엉치뼈 2~4사이에 가시결절로부터 양쪽으로 80%< 장력으로 늘려 엉치엉덩관절을 지나게 붙이고 이후 끝 쪽은 양쪽 약 45° 방향으로 올려 중간볼기근(gluteus medius m.) 쪽으로 향하게 붙였다. 그 다음 엉덩뼈능선(iliac crest)로부터 척추기립근을 따라 10번째 갈비뼈 수준까지 이르는 양쪽 테이핑 방법이 적용되었다. 해당 중재를 통해 VAS와 ODI 두 검사도구로부터 VAS는 5에서 0, 장애지수는 13에서 0으로 각각 기록되는 긍정적 사례 결과를 관찰할 수 있었다.

• Computers and Concrete
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• 제3권4호
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• pp.213-233
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• 2006

Over the past years techniques for non-linear analysis have been enhanced significantly via improved solution procedures, extended finite element techniques and increased robustness of constitutive models. Nevertheless, problems remain, especially for real world structures of softening materials like concrete. The softening gives negative stiffness and risk of bifurcations due to multiple cracks that compete to survive. Incremental-iterative techniques have difficulties in selecting and handling the local peaks and snap-backs. In this contribution, an alternative method is proposed. The softening diagram of negative slope is replaced by a saw-tooth diagram of positive slopes. The incremental-iterative Newton method is replaced by a series of linear analyses using a special scaling technique with subsequent stiffness/strength reduction per critical element. It is shown that this event-by-event strategy is robust and reliable. First, the model is shown to be objective with respect to mesh refinement. Next, the example of a large-scale dog-bone specimen in direct tension is analyzed using an isotropic version of the saw-tooth model. The model is capable of automatically providing the snap-back response. Subsequently, the saw-tooth model is extended to include anisotropy for fixed crack directions to accommodate both tensile cracking and compression strut action for reinforced concrete. Three different reinforced concrete structures are analyzed, a tension-pull specimen, a slender beam and a slab. In all cases, the model naturally provides the local peaks and snap-backs associated with the subsequent development of primary cracks starting from the rebar. The secant saw-tooth stiffness is always positive and the analysis always 'converges'. Bifurcations are prevented due to the scaling technique.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.9-16
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• 2002

In this paper, we intend to demonstrate a new intuitive force-feedback device for advanced VR applications. Force feed-back for the device is tension based and is characterized by 7 degrees of freedom (DOF); 3 DOF for translation, 3 DOF for rotation, and 1 DOF for grasp). The SPIDAR-G (Space Interface Device for Artificial Reality with Grip) will allow users to interact with virtual objects naturally by manipulating two hemispherical grips located in the center of the device frame. We will show how to connect the strings between each vertex of grip and each extremity of the frame in order to achieve force feedback. In addition, methodologies will be discussed for calculating translation, orientation and grasp using the length of 8 strings connected to the motors and encoders on the frame. The SPIDAR-G exhibits smooth force feedback, minimized inertia, no backlash, scalability and safety. Such features are attributed to strategic string arrangement and control that results in stable haptic rendering. The design and control of the SPIDAR-G will be described in detail and the Space Graphic User Interface system based on the proposed SPIDAR-G system will be demonstrated. Experimental results validate the feasibility of the proposed device and reveal its application to virtual reality.

• 한국수소및신에너지학회논문집
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• 제13권1호
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• pp.65-73
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• 2002

Because of low flame ion density in hydrogen-air mixture, many residual electric energy could be existed in the ignition system of hydrogen engine, If these residual energy discharged abnormally during intake stroke, it may be the cause of backfire occurrence which is serious problem in development of hydrogen fueled engine but unsolved in spite of many concerned research on it. In this study, the possibility of backfire occurrence by abnormal electric discharge and countermeasure of that were investigated by using the experimental single cylinder hydrogen fueled engine with two types of ignition system. The results show that abnormal electric discharge appeared in low load with low ion density and then results in back fire occurrence, It is also seen that countermeasure method installing larger earth resistance in high tension code is effective to control abnormal electric discharge.