• International Journal of Quality Innovation
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• 제9권1호
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• pp.94-102
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• 2008

When facing the global severe competition, the enterprises all try their best to upgrade the quality, reduce the costs to reach the goal of customer satisfaction. Motorola was the earliest firm creating the term Six Sigma (6 ${\sigma}$); GE was the enterprise successfully fulfilling Six Sigma. The success of these two firms revealed the prominent effects and became the world-class model enterprises. The main purpose of promoting Six Sigma activity was to reduce the possible defects in the business process to the least through designing and monitoring business process in order to reach the goals such as the best quality and efficiency, the lowest costs, the shortest circular process time, maximum profits and customer satisfaction. This research used the Six Sigma technique to improve the business process of ceramics manufacturing plant and find out the major factors of slower core task time by the analytical process of Process Mapping, Pareto Chart, Simu18 simulation software and figures and proposed the improvement measures. Through the confirmation of the case companies, it successfully reduced the core process time and the organizational costs and increased the capacity.

• 한국공작기계학회논문집
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• 제17권6호
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• pp.49-55
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• 2008

Arc welding process is one of the most important technologies to join metal plates. Robotic welding offers the reduced manufacturing cost sought, but its widespread use demands a means of sensing and correcting for inaccuracies in the part, the fixturing and the robot. A number of problems that need to be addressed in robotic arc welding processes include sensing, joint tracking, and lack of adequate models for process parameter prediction and quality control. Problems with parameter settings and quality control occur frequently in the GMA(Gas Metal Arc) welding process due to the large number of interactive process parameters that must be set and accurately controlled. The objectives of this paper are to realize the mapping characteristics of bead width using a sensitivity analysis and develop the neural network and multiple regression method, and finally select the most accurate model in order to control the weld quality(bead width) for fillet welding. The experimental results show that the proposed neural network estimator can predict bead width with reasonable accuracy, and guarantee the uniform weld quality.

• 천문학논총
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• 제30권2호
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• pp.103-105
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• 2015

The 22 m diameter Mopra telescope in Australia is being used to undertake an improved survey of the CO J = 1-0 line at 3mm along the 4th quadrant of the Galaxy, achieving an order of magnitude better spatial and spectral resolution (i.e. 0.6 and 0.1 km/s) than the Dame et al. (2001) survey that is publically available for the Southern Galactic plane. Furthermore, the Mopra CO survey includes the four principal isotopologues of the CO molecule (i.e. $^{12}CO$, $^{13}CO$, $C^{18}O$ and $C^{17}O$). The survey makes use of an 8 GHz-wide spectrometer and a fast mode of on-the-fly mapping developed for the Mopra telescope, where the cycle time has been reduced to just 1/4 of a second. 38 square degrees of the Galaxy, from $l=306-344^{\circ}$, $b=0{\pm}5^{\circ}$ have currently been surveyed, together with additional 9 sq. deg. regions around the Carina complex and the Central Molecular Zone. We present new results from the survey (see also Burton et al., 2013, 2014). The Mopra CO data are being made publically available as they are published; for the latest release see the project website at www.phys.unsw.edu.au/mopraco.

• Journal of Power Electronics
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• 제19권4호
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• pp.1000-1010
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• 2019

The use of internal-model-based linear controller, such as resonant controller, is a well-established technique for the current control of grid-connected systems. Attractive properties for resonant controllers include their two-sequence tracking ability, the simple control structure, and the reduced computational burden. However, in the case of continuous-designed resonant controller, the transient performance is inevitably degraded at a low switching frequency. Moreover, available design methods for resonant controller is not able to realize the direct design of transient performances, and the anticipated transient performance is mainly achieved through trial and error. To address these problems, the zero-order-hold (ZOH) characteristic and inherent time delay in digital control systems are considered comprehensively in the design, and a corresponding hold-equivalent discrete model of the grid-connected converter is then established. The relationship between the placement of closed-loop poles and the corresponding transient performance is comprehensively investigated to realize the direct mapping relationship between the control gain and the transient response time. For the benefit of automatic tuning and real-time adaption, analytical expressions for controller gains are derived in detail using the required transient response time and system parameters. Simulation and experimental results demonstrate the validity of the proposed method.

• Steel and Composite Structures
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• 제50권4호
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• pp.429-441
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• 2024

This paper studies the free vibration behavior of trapezoidal shaped coupled double-layered graphene sheets (DLGS) system using first-order shear deformation theory (FSDT) and incorporating nonlocal elasticity theory. Two nanoplates are assumed to be bonded by an interlayer van der walls force and surrounded by an external kelvin-voight viscoelastic medium. The governing equations together with related boundary condition are discretized using a mapping-differential quadrature method (DQM) in the spatial domain. Then the natural frequency of the system is obtained by solving the eigen value matrix equation. The validity of the current study is evaluated by comparing its numerical results with those available in the literature and then a parametric study is thoroughly performed, concentrating on the series effects of angles and aspect ratio of GS, viscoelastic medium, and nonlocal parameter. The model is used to study the vibration of DLGS for two typical deformation modes, the in-phase and out-of-phase vibrations, which are investigated. Numerical results indicate that due to Increasing the damping parameter of the viscoelastic medium has reduced the frequency of both modes and this medium has been able to overdamped the oscillations and by increasing stiffness parameters both in-phase and out-of-phase vibration frequencies increased.

• 한국환경과학회지
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• 제20권12호
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• pp.1647-1661
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• 2011

The Government had devised legislation of Special Act and drew up guidelines for improving air quality in Seoul Metropolitan area. In 2007 local government of Seoul, Incheon and Gyeonggi conducted the results of application policy by reduced air pollutants emission for the first time. Although there was reduction of air pollutant emission in each local government, it was ineffective as expected using air pollution monitoring database. Therefore we worked out a way to prepare modeling input data using the results of enforcement plan. And we simulated surface $NO_2$ and PM10 before and after decrease in air pollutants emission and examine reduction effects of air pollution according to enforcement regulation except other influence, by using MM5-SMOKE-CMAQ system. Each local government calculated the amount of emission reduction under application policy, and we developed to prepare input data so as to apply to SMOKE system using emission reduction of enforcement plan. Distribution factor of emission reduction were classified into detailed source and fuel codes using code mapping method in order to allocate the decreased emission. The code mapping method also included a way to allocate spatial distribution by CAPSS distribution. According to predicted result using the reduction of NOx emission, $NO_2$ concentration was decreased from 19.1 ppb to 18.0 ppb in Seoul. In Gyeonggi and Incheon $NO^2$ concentrations were down to 0.65 ppb and 0.68 ppb after application of enforcement plan. PM10 concentration was reduced from 18.2 ${\mu}g/m^3$ to 17.5 ${\mu}g/m^3$ in Seoul. In Gyeonggi PM10 concentration was down to 0.51 ${\mu}g/m^3$ and in Incheon PM10 concentration was decreased about 0.47 ${\mu}g/m^3$ which was the lower concentration than any other cities.

• 한국지반공학회논문집
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• 제16권1호
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• pp.145-155
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• 2000

불연속면의 방향성은 암반의 과도변형이나 안정성에 영향을 미치는 특성 때문에 암반사면의 안정성 평가에 있어서 매우 중요한 역할을 한다. 불연속면의 방향측정에는 시추공(borehole)을 이용한 측정법이나 노두에서의 scanline을 이용하는 측정법과 같은 선형 측정법이 보편적으로 이용되나 이러한 측정 기법을 이용하여 획득한 자료들은 측선의 방향에 따라 쉽게 왜곡된다. 이러한 왜곡을 수정하기 위한 가중치 (weighting factor)가 적용되어도 특정 방향의 측선을 따라 자료를 획득할 경우 그 왜곡은 쉽게 보정되어지지 않는다. 즉, 불연속면의 방향자료 수집을 위해 이용된 선형 측선이 불연속면의 방향과 평행할 경우 대부분의 측선과 평행한 불연속면들은 조사 결과에 포함되지 않으며 이러한 현상은 불연속면들의 방향성 파악에 심각한 오류를 발생시킬 수 있다. 본 연구에서는 수직 측선 (borehole)에 의해 수집되어진 방향자료들과 수평 측선 (scanline)에 의해 수집되어진 방향자료들을 비교하였다. 서로 다른 두 방법에 의해 수집되어진 방향자료들은 큰 차이를 보이며, 이로 인해 불연속면들의 대표적인 방향성 결정에 장애가 되어진다. 불연속면의 경사각 분포와 수평과 수직 측선에 의해 수집되어진 자료들의 비교를 위해 등면적 극 평사투영망(polar stereo net)을 이용하였다.

• 생물정신의학
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• 제15권2호
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• pp.118-125
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• 2008

Objectives : The purpose of this study was to find brain regions in which gray matter volume was reduced and to show the capability of voxel-based morphpmetry(VBM) analysis for lateralizing clinically significant brain regions in dementia of Alzheimer's type patients compared to healthy group. Methods : MR T1-weighted images of the 20 dementia of Alzheimer's type patients were compared with those of the 20 normal controls. Images were transformed to standard MNI space. In order to observe gray matter volume change. Gray matter was smoothed with a Gaussian kernel. After these preprocessing, statistical analysis was performed using statistical parametric mapping software(SPM2). Results : Gray matter volume was significantly reduced in the bilateral parahippocampal gyri, Lt. anterior cingulate gyrus, Lt. posterior cingulate gyrus, bilateral superior temporal gyri Lt. middle temporal gyrus, Lt. superior, bilateral middle, Rt. anterior frontal gyri and Rt. precuneus in dementia of Alzheimer's type patient group. Conclusions : These VBM results confirm previous findings of temporal lobe and limbic lobe atrophic changes in dementia of Alzheimer's type, and suggest that these abnormalities may be confined to specific sites within that lobe, rather than showing a widespread distribution.

• 한국환경보건학회지
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• 제36권3호
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• pp.182-190
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• 2010

We examined the association of particulate matter with an aerodynamic diameter < $10\;{\mu}m$ ($PM_{10}$) with asthma-related hospitalization, stratified by socioeconomic status (SES), among children less than 15 years of age in Seoul, Korea, between 2003 and 2005. In addition, we estimated the reduction in the number of asthma-related hospitalizations that would result from implementing the World Health Organization (WHO) guideline. SES was defined based on data concerning health insurance premium grades, and grouped into two levels: lower-income group and control group. The lower-income group was classified as having an accumulated income which did not exceed the 50th percentile of the median income. Time-series analysis was performed to evaluate the association between $PM_{10}$ and asthma-related hospitalization. The Environmental Benefits Mapping and Analysis Program was used to analyze the impact on children's health. Based upon an increase of $10\;{\mu}g/m^3$ of $PM_{10}$, the asthma-related hospitalization risk for the lower-income group was increased by 1.78% (95% confidence intervals (CI) = 0.79-2.78%), while the risk for the control group was increased by 0.83% (95% CI = 0.34-1.32%). Attaining the WHO guideline, relative to the concentration in 2007, would result in a reduction in asthma-related hospitalizations of 18 cases per 100,000 of the children population in the lower-income group, and 7 cases in the control group. The health benefits of improved air quality for children in the lower-income group were thus 2.5 times greater than for children in the control group. Our results show that the lower-income group is disproportionately burdened with asthma-related hospitalization arising from air pollution. Therefore, biologically- and socioeconomically-disadvantaged populations should be considered in public health interventions in order to protect the children's health.

• 대한핵의학회지
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• 제38권1호
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• pp.30-40
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• 2004

목적: 본 연구의 목적은 첫째, 내측 측두엽 간질환자의 MR 영상에 화소기반 형태분석방법(VBM)을 적용하여 회백질 부피감소를 보이는 영역을 뇌 전체를 관찰하여 찾아내고자 하였다. 둘째, 본 연구에서 적용된 VBM방법이 내측측두엽 간질환자의 간질병소의 편측성을 평가하기에 쓰일 수 있을지 조사하였다. MR영상으로 VBM 결과를 FDG PET의 SPM 분석결과와 비교하였다. 대상 및 방법: 12명의 좌측 내측측두엽 간질환자와 11명의 우측 내측측두엽 간질환자의 T1 강조영상을 각각 37명의 정상 대조군의 영상과 비교하였다. 모든 영상을 표준 뇌 표준판에 공간정합한 후, 평균영상을 생성하여 연구-특정적 뇌 표준판을 만들고 이 연구 측정적 표준판에 다시 비선형 공간정규화 하였다. 영상을 분할하여 회백질영상을 추출하고 변조한 후 편평화하였다. 환자군과 정상군의 차이를 SPM99를 이용하여 허위발견률을 기준으로 통계처리하였다. FDG PET 영상을 SPM을 이용하여 정상대조군 22명과 비교하였다. 결과: 좌측 내측측두엽 간질환자는 좌측의 해마와 편도체 영역에 회백질 부피/농도가 감소하였고, 뇌의 양측 소뇌, 전대상회, 방추상회의 부피/농도가 감소하였다. 우측 내측측두엽 간질환자는 우측 해마의 서 회백질이 감소하였다. 좌측 내측측두엽 간질은 좌측 측두엽과 시상 우측 내측측두엽간질 환자는 우측측두엽에 광범위한 부위에 FDG 섭취가 감소하였다. 결론: VBM 방법을 적용한 결과 간질원인 병소 해마와 해마주변영역에서 유의하게 회백질 부피/농도가 감소하였다. FDG PET SPM 분석에서 간질원인병소의 대사 감소를 찾을 수 있었던 것처럼, 이 연구에서 적용한 변조 VBM 방법은 내측측두엽 간질환자의 간질원인병소를 편측화할 수 있었고 내측측두엽을 제외한 다른 뇌영역의 해부학적 변화를 발견하는데 도움이 되었다. 이에 비하여 간질원인병소인 좌우측측두엽의 넓은 부위에 FDG 섭취가 감소하여 대조되었다.