• 유공압시스템학회논문집
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• 제3권3호
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• pp.8-13
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• 2006

It is very important for the manufacturers to predict the life of hydraulic system components according to the results of life tests. Since it takes too much time to test the hydraulic system components until failure, the no-failure test method is applied for the life test of them. If the shape parameter of Weibull distribution, the number of samples, the confidence level, and the assurance life are given, the no-failure test times of hydraulic system components can be calculated by given equation. Here, the procedures to obtain the no-failure test times of the hydraulic system components such as hydraulic motors and pumps, hydraulic cylinders, hydraulic valves, hydraulic accumulators, hydraulic hoses, and hydraulic filters are described briefly.

• 한국운동역학회지
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• 제12권2호
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• pp.259-278
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• 2002

본 연구에서는 볼 구질의 변화에 따른 스윙 동작의 운동학적인 변인을 3차원적으로 비교 분석하여 스윙 동작의 운동역학적인 원리를 제시하며, 볼 구질이 다른 스윙 동작의 차이점을 밝히는 데 목적이 있으며, 프로골퍼로 경력 3년 이상의 남자 선수 7명을 대상으로 스트레이트 성공, 페이드 성공과 실패로 구분하여 골프 스윙의 운동학적 변인들을 과학적으로 제시하기 위해 비교 분석한 결과 다음과 같은 결론을 얻었다. 페이드 성공시에는 임팩트를 지나서도 계속 손목의 각도가 근소한 차이로 줄어드는 것으로 나타났고 실패시에는 각 프레임의 각도가 규칙적으로 변하지 않게 나타났다. 이는 스트레이트 성공과 페이드 성공에 대한 손목각도의 차이가 영향을 미치는 것으로 나타나 다른 요인과 손목각도와의 관계를 분석하는 것이 필요하다고 하겠다. 페이드 실패의 경우는 임팩트시의 몸통 비틀림각도가 성공때 보다 작아지면서 클럽헤드가 오픈되지 못한 것으로 나타났다. 골프스윙의 형태의 변화로 인하여 어깨관절의 회전력을 더 많이 사용하여 파워을 증진시키기 위한 동작이며, 골프 스윙에서 어깨회전 운동은 축을 중심으로 회전하기 때문에 어깨회전각도의 차이는 없는 것으로 나타났다. 스트레이트 성공시 보다 페이드 성공시에 고관절의 회전각도가 점진적으로 일정하게 각이 커졌다. 이는 고관절의 회전을 더 크게 하여 지연히팅을 보다 자연스럽게 한 것으로 나타났다. 페이드 볼 구사시 임팩트 존에서 클럽의 페이스가 닫히는 것과 팔의 자연스러운 롤링 동작을 억제시키는 것으로 나타났다. 본 연구에서는 구질 변화에 따른 골프 스윙 동작을 스트레이트 성공, 페이드 성공과 실패시로 구분하여 운동학적 변인들을 3차원 동작 분석을 통하여 경기력 향사에 도움이 되고자 하였으며 앞으로 많은 연구자들이 각 종목에 있어서 경기력 향상을 위한 역학적인 분석이 계속 진행되어져야 할 것이다.

• Geomechanics and Engineering
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• 제17권1호
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• pp.97-107
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• 2019

Based on the results of Han et al. (2016), in the failure zone ahead of the tunnel face it can be obviously identified that a shear failure band occurs in the lower part and a pressure arch happens at the upper part, which was often neglected in analyzing the face stability of shield tunnel. In order to better describe the collapse failure feature of the tunnel face, a new improved failure mechanism is proposed to evaluate the face stability of shield tunnel excavated in layered soils in the framework of limit analysis by using spatial discretization technique and linear interpolation method in this study. The developed failure mechanism is composed of two parts: i) the rotational failure mechanism denoting the shear failure band and ii) a uniformly distributed force denoting the pressure arch effect. Followed by the comparison between the results of critical face pressures provided by the developed model and those by the existing works, which indicates that the new developed failure mechanism provides comparatively reasonable results.

• 한국안전학회지
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• 제26권6호
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• pp.104-110
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• 2011

In FMEA, the risk priority number(RPN) is used for risk evaluation on each failure mode. It is obtained by multiplying three components, i.e., severity, occurrence, and detectability of the corresponding failure mode. Each of the three components are usually determined on the basis of the past experience and technical knowledge. But this approach is not strictly objective in evaluating risk of a given failure mode and thus provide somewhat less scientific measure of risk. Assuming a homogeneous Poisson process for occurrence of the failures and causes, we propose a more scientific approach to evaluation of risk in FMEA. To quantify severity of each failure mode, the mission period is taken into consideration for the system. If the system faces no failure during its mission period, there are no losses. If any failure occurs during its mission period, the losses corresponding to the failure mode incurs. A longer remaining mission period is assumed to incur a larger loss. Detectability of each failure mode is then incorporated into the model assuming an exponential probability law for detection time of each failure cause. Based on the proposed model, an illustrative example and numerical analyses are provided.

• 대한치과보철학회지
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• 제30권4호
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• pp.508-525
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• 1992

The purpose of this study was to evaluate the effect of some resistance form designs on the bond strength of resin-retained prosthesis. Six sub-groups are designed in natural teeth group and resin teeth group . The framework designs in natural teeth group: 1) no groove preparation 2) groove at the center of distal surface 3) groove at the distobuccal line angle 4) 45 degree lateral load with no groove 5) 45 degree lateral load with center groove 6) splint two teeth with no groove. The framework designs in resin teeth group: 1) no groove preparation 2) groove at the center of distal surface 3) groove at the distobuccal line angle 4) metal covered the 1/2 of distal surface 5) metal covered the 1/2 of mesial surface 6) metal extended over the 114 of buccal surface. Specimens were treated electrolytic etching by Oxy-Etch and cemented with Panavia EX. Failure load was measured by Instron. Another 30 specimens were carried out fatigue tests by MTS 810 fatigue testing machine for 5000 cycles at different load level. The following results were obtained from this study. 1. The failure load was significantly increased by resistance forms. 2. The failure load was not increased by increase of total surface area bonded with teeth. The distal surface area played an important role in failure load. 3. In 45 degree lateral load group, the failure load was decreased significantly than that of in vertical load group. 4. Bond failure modes between static test and fatigue test exhibited no differences.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.279-286
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• 2002

Present all sorts of failure or no failure test methods are done for evaluate structural ability of pavement. It are Plane Plate Test, CBR Test, Benkelman Beam Test, FWD, Dynaflect, etc. but, each method of test not expect compatibility because the result very different by each method of test. Now among pavement's method of evaluation, no failure test gradually use because It quickly and simply obtain pavement's elastic modulus of each layer. But, It accompany expensiveness equipment, and It's degree of trust is lower against expensiveness equipment. Therefore this research practice comparative trustworthy Plane Plate Test, comparative low cost and quick Small FWD Test. And analyzed relation of Plane Plate Test with Small FWD Test.

• Journal of Construction Engineering and Project Management
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• 제6권4호
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• pp.24-34
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• 2016

Disputes seem to be synonymous with large-scale construction projects in Ethiopia. The purpose of this study is to determine the factors responsible for impacting the performance of Ethiopian public construction projects. To this end, 35 success and failure attributes responsible for impacting the performance of the projects were identified and presented to Ethiopian construction professionals in the form of a structured questionnaire, and responses were collected. The factor analysis conducted on the success and failure attributes influencing no-dispute performance separately resulted in six success factors and five failure factors. Further analysis using stepwise multiple regression indicates that owner competence and interaction among project participants have a positive impact on no-dispute performance. However, conflict among project participants has a negative impact on the no-dispute performance of Ethiopian public construction projects. Although Ethiopia-specific, the results reflect construction management problems common to both developed and developing countries. The findings are expected to help researchers and practitioners gain a better understanding of critical success and failure factors and to help them take proactive measures to avoid disputes in public construction projects.

• Journal of Trauma and Injury
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• 제28권3호
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• pp.104-107
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• 2015

Purpose: Nitric oxide (NO) is a vasodilator and inhaled NO (iNO) is used in acute respiratory distress syndrome (ARDS) to improve alveolocapillary gas exchange. The mechanism to improve oxygenation is likely to redistribute blood flow from unventilated areas to ventilated areas. Though improvement of oxygenation, iNO therapy has not been shown to improve mortality and considered as only rescue therapy in severe hypoxemia. We conducted the study to investigate an efficacy of iNO in trauma patients with severe hypoxemia. Methods: We reviewed the trauma patients who underwent iNO therapy retrospectively from 2010 to 2014. Degree of hypoxemia was represented as $PaO_2/FiO_2$ ratio (PFR) and the severity of patient was represented with sequential organ failure assessment (SOFA) score. Patients were divided into the survivor group and non-survivor group according to the 28-day mortality. Results: A total of 20 patients were enrolled. The mortality of 28-day was 40%. There were no significant differences between survivor and non-survivor group in age, sex, severity of injury, PFR and SOFA score. There was significant difference in initiation time of iNO after injury (p=0.047). Maximum combinations of sensitivity and specificity for timing of iNO therapy were observed using cut-off of 3-day after injury with a sensitivity of 88% and specificity of 75%. Conclusion: Though iNO therapy does not influence the mortality, iNO therapy may decrease the mortality caused by respiratory failure in the early phase of trauma.

• 대한산업공학회지
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• 제20권1호
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• pp.39-51
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• 1994

Almost all accelerated life tests assume that no basic failure mechanism changes within the test stresses. But accelerated life test, considering failure mechanism changes, is needed since failure mechanism changes when accelerating beyond the used stress. This paper studies the analysis when the failure mechanism changes within the test stresses. The piecewise linear regression, which the join point of two lines is estimated, is applied In particular, two accelerated life tests, with and without a change in failure mechanism are examined.

• Computers and Concrete
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• 제28권6호
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• pp.585-603
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• 2021

The validation based on the experimental data demonstrates that the concrete strength under triaxial compression (TC) is overestimated by Lubliner-Oller strength criterion (SC) but underestimated by Lubliner-Lee SC in ABAQUS. Moreover, the discontinuous derivatives of failure criterion exists near the unexpected breakpoints. Both resulted from the piecewise linear meridians of the original Lubliner SC with constants γ. Following the screen for the available failure criteria to determine the model parameter γ of Lubliner SC, Menétrey-Willam SC (MWSC) is considered the most promising option with a reasonable aspect ratio Kc but no other strength values required and only two new model parameters introduced. The failure surface of the new Lubliner SC based on MWSC (Lubliner-MWSC) is smooth and has no breakpoints along the hydrostatic pressure (HP) axis. Finally, predicted results of Lubliner-MWSC are compared with other concrete failure criteria and experimental data. It turns out that the Lubliner-MWSC can represent the concrete failure behavior, and MWSC is the optimal choice to improve the applicability of the concrete damaged plasticity model (CDPM) under TC in ABAQUS.