• International Journal of Quality Innovation
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• 제8권1호
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• pp.137-153
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• 2007

Failure mode and effects analysis (FMEA) is a preventive technique in reliability management field. The successful implementation of FMEA technique can avoid or reduce the probability of system failure and achieve good product quality. The FMEA technique had applied in vest scopes which include aerospace, automatic, electronic, mechanic and service industry. The marking process is one of the back ends testing process that is the final process in semiconductor process. The marking process failure can cause bad final product quality and return although is not a primary process. So, how to improve the quality of marking process is one of important production job for semiconductor testing factory. This research firstly implements FMEA technique in laser marking process improvement on semiconductor testing factory and finds out which subsystem has priority failure risk. Secondly, a CCD position solution for priority failure risk subsystem is provided and evaluated. According analysis result, FMEA and CCD position implementation solution for laser marking process improvement can increase yield rate and reduce production cost. Implementation method of this research can provide semiconductor testing factory for reference in laser marking process improvement.

• International journal of advanced smart convergence
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• 제8권4호
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• pp.207-213
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• 2019

Assistance for the quality assurance management and developers to provide high quality software products. Using a bug record keeping system is exceptionally important in software progress, and it is followed vastly by majority of software producing companies in modern era. Regular application of a bug record keeping system is very helpful in developing software systems. We developed this system which helps the software testing team to keep a complete record of their testing activities during the software testing, also increases your confidence in the software quality, class and worth. Our proposed system offers trouble-free and effortless approaches to acquire desired information about bug, also produces different kinds of reports like summary reports, detailed reports etc. It gives facility to create, delete and update any project. Our developed application system is designed by using visual c# at front end and sql server 2008 management studio express at back end.

• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.174-179
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• 2016

In this paper, a novel full-aperture reflective null measuring method is proposed to detect the transmission wavefront of a conformal dome surface. An aspheric compensator is designed and placed behind the dome to reflect the aspheric testing wave back to the same path. To ensure the feasibility of this method, tolerance analysis is conducted, and guidance to assembly is given accordingly. The accuracy of this method is verified to be λ/30 (λ =3.39 μm) by Monte Carlo algorithm. In addition, the influence of different error factors, including the thickness error and decenter error of the dome, on the testing wavefront is analyzed. Simulation and experiment indicate that this method is practical and simple, and can measure the conformal domes precisely and comprehensively.

• Journal of Magnetics
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• 제21권4호
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• pp.570-576
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• 2016

The shape optimization of the stator and the rotor is important for electrical motor design. Among many motor design parameters, the stator tooth and yoke width are a few of the determinants of noload back-EMF and load torque. In this study, we proposed an equivalent magnetic circuit of motor stator for efficient stator tooth and yoke width shape optimization. Using the proposed equivalent magnetic circuit, we found the optimal tooth and yoke width for minimal magnetic resistance. To verify if load torque is truly maximized for the optimal tooth and yoke width indicated by the proposed method, we performed finite element analysis (FEA) to calculate load torque for different tooth and yoke widths. From the study, we confirmed reliability and usability of the proposed equivalent magnetic circuit.

• 한국도로학회논문집
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• 제17권5호
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• pp.25-31
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• 2015

PURPOSES: The objective of this study is to analyze the relationship between the FWD back-calculated modulus and dynamic modulus of asphalt layers for existing asphalt pavements. METHODS: To evaluate the dynamic modulus of the asphalt mixture in the existing and new asphalt layers, the uniaxial direct tension test was conducted on small asphalt specimens obtained from the existing asphalt-covered pavements. A dynamic modulus master curve was estimated by using the uniaxial direct tension test for each asphalt layer. The falling weight deflectometer (FWD) testing was conducted on the test sections, and the modulus values of pavement layers were back-calculated using the genetic algorithm and the finite element method based back-calculation program. The relationship between measured and back-calculated asphalt layer moduli was examined in this study. The normalized dynamic modulus was adopted to predict the stiffness characteristics of asphalt layers more accurately. RESULTS: From this study, we can conclude that there is no close relationship between dynamic modulus of first layer and back-calculated asphalt modulus. The dynamic moduli of second and third asphalt layers have some relation with asphalt stiffness. Test results also showed that the normalized dynamic modulus of the asphalt mixture is closely related to the FWD back-calculated modulus with 0.73 of R square value. CONCLUSIONS: The back-calculated modulus of asphalt layer can be used as an indicator of the stiffness characteristics of asphalt layers in the asphalt-covered pavements.

• 한국전문물리치료학회지
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• 제27권2호
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• pp.149-154
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• 2020

Background: The range of pelvic tilt is one of modifiable risk factors in preventing the lower back pain. Objects: The purpose of this study were to compare the range of pelvic tilt motion by testing position and sex. Methods: One hundred five young adults (61 females and 44 males) agreed to participate in measuring the anterior and posterior pelvic tilt with the PALM (Palpation Meter) in sitting and standing. The range of pelvic tilt motion was defined as the difference between the pelvic anterior and posterior tilt angles. Results: In general, the anterior pelvic tilt was greater (p < 0.01) in standing than in sitting and the posterior pelvic tilt was lesser (p < 0.01) in sitting than in standing. The anterior pelvic tilt in sitting and standing was greater (p < 0.01) in the females than in the males. However, the effect of sex on the posterior pelvic tilt was only significant in sitting (p < 0.01), but not in standing (p = 0.78). The range of pelvic tilt was greater (p = 0.03) in sitting but not significantly (p = 0.07) affected by the sex. Conclusion: The pelvic tilt motion in these young adults showed large variability and further studies are needed to understand better its relationship to the prevalence of the lower back disorders.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.669-673
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• 2007

In this study, real-time hybrid test using a shaking table for the control performance evaluation of a U-shaped TLCD controlling the response of earthquake-excited building structure is experimentally implemented. In the test, the building structure is used as a numerical part, on which a U-shaped TLCD adopted as an experimental part was installed to reduceits response. At first, the force that is acting between a TLCD and building structure is measured from the load cell attached on shaking table and is fed-back to the computer to control the motion of shaking table. Then, the shaking table is so driven that the error between the interface acceleration computed from the numerical building structure with the excitations of earthquake and the fed-back interface force and that measured from the shaking table. The control efficiency of the TLCD used in this paper is experimentally confirmed by implementing this process of shaking table experiment on real-time.

• 응용통계연구
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• 제28권3호
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• pp.541-559
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• 2015

VaR는 금융위험을 측정하고 관리하기위한 중요한 도구로 현재 널리 사용되고 있다. 특히 금융자산 수익률의 변동성에 적합한 모형을 찾는 것은 VaR의 정확한 측정을 위해 중요한 과제이다. 본 연구에서는 한국의 코스피, 중국의 항셍, 일본의 니케이지수들로 구성된 포트폴리오의 VaR를 측정하기 위한 변동성모형으로 다양한 일변량모형들과 다변량모형들을 함께 고려하여 그 성과를 비교하였다. 사후검증을 통해 전체적으로 일변량모형들보다는 다변량모형들이 VaR의 측정에 더 적합한 것으로 보여 졌으며 특히 DCC와 ADCC모형이 더욱 우수한 것으로 나타났다.

• 응용통계연구
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• 제26권1호
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• pp.163-185
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• 2013

본 논문에서는 장기기억 변동성 모형의 필요성을 Value-at-Risk(VaR) 추정의 관점에서 알아본다. 이를 위해, KOSPI 수익률의 VaR을 FIGARCH, FIEGACH와 같은 장기기억 변동성 모형과 GARCH, EGARCH와 같은 단기기억 변동성 모형을 적용하여 각각 추정한 후, 각 변동성 모형에 따른 추정의 적절성을 사후검증을 통하여 비교해 본다. 사후검증을 통해, KOSPI 수익률 과정이 장기기억 속성을 가짐을 확인할 수 있으며, 적절한 VaR의 추정을 위해서는 장기기억 변동성 모형을 적용하는 것이 필요함을 알 수 있다.

• 응용통계연구
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• 제29권1호
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• pp.171-180
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• 2016

바젤 위원회는 시장위험의 측정 도구로 Value-at-Risk(VaR)와 expected shortfall(ES)을 사용할 것을 제안하였다. 여러 문헌에서 VaR와 ES의 다양한 추정 방법들이 연구 되었다. 본 연구에서는 준모수적인 방법인 conditional autoregressive value at risk(CAViaR), conditional autoregressive expectile(CARE) 방법들, 그리고 Gaussian 준최대가능도 추정량(QMLE)를 이용한 방법을 사후 검정을 통해서 비교하고자 한다. 각 방법의 타당성을 확인하기 위해서, VaR에 대한 사후 검정은 unconditional coverage(UC)와 conditional coverage(CC) 검정을 사용하고 ES에 대한 검정은 붓스트랩 방법을 사용한다. S&P500 지수와 현대 자동차 주식가격 지수에 대하여 실증 자료 분석이 수행되었다.