• 응용통계연구
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• 제15권2호
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• pp.233-250
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• 2002

Cox의 비례위험모형(proportional hazards model)은 생존자료(survival data)에 대한 회귀모형으로 경제학 및 의·공학을 비롯한 여러 응용 분야에서 가장 널리 쓰이고 있는 모형 중 하나이다. 그러나, 이 모형은 일반선헝모형에 비해 잔차 분석을 통한 회귀 진단의 연구가 널리 알려져 있지 않아, 국내의 실제 자료 분석에서는 잔차 분석에 대한 활용이 거의 이루어지지 않고 있는 실정이다. 이에 본 논문에서는 그 동안 제안된 여러 잔차들을 비교 분석하고, S-plus 프로그램을 이용한 PBC(primary biliary cirrhosis) 자료분석을 통해 각 잔차들의 의미를 고찰하고자 한다.

• 유공압시스템학회논문집
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• 제8권4호
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• pp.9-16
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• 2011

Because of the increasing demand on the high precision and high response of a machinery, proportional control valves are widely adopted at various application fields. This paper studies on the static and dynamic characteristics of a pilot proportional pressure control valve. An experimental apparatus including hydraulic pump, variable speed inverter, pressure and flow sensors and data aquisition system was set up. And various experiments such as P-Q-V curves, step responses due to input voltage and flow rate, hysteresis, frequency response of the proportional valve was carried out and the results are discussed.

• 한국생산제조학회지
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• 제19권2호
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• pp.191-197
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• 2010

In spite of a large amount of previous research, detail study on modified mass in proportional damping system is not well understood. It is common to predict structural dynamic design parameters due to the change of mass, but to predict the amount of modified mass and the location where the mass is being modified are rarely found in previous literature. Such inverse problem required detail analytical study in order to understand structural modification in proportional damping system. This paper predicts the modified mass and the modified mass location in proportional damping system using sensitivity coefficients and iterative method. The sensitivity coefficients are obtained from the change of eigenvectors due to mass modification. This method is applied to a horizontal beam and three degree of freedoms system. To validate the predicted changing mass and its location, the obtained results are compared to the reanalysis result which shows good agreement.

• Communications for Statistical Applications and Methods
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• 제24권6호
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• pp.583-604
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• 2017

The most popular regression model for the analysis of time-to-event data is the Cox proportional hazards model. While the model specifies a parametric relationship between the hazard function and the predictor variables, there is no specification regarding the form of the baseline hazard function. A critical assumption of the Cox model, however, is the proportional hazards assumption: when the predictor variables do not vary over time, the hazard ratio comparing any two observations is constant with respect to time. Therefore, to perform credible estimation and inference, one must first assess whether the proportional hazards assumption is reasonable. As with other regression techniques, it is also essential to examine whether appropriate functional forms of the predictor variables have been used, and whether there are any outlying or influential observations. This article reviews diagnostic methods for assessing goodness-of-fit for the Cox proportional hazards model. We illustrate these methods with a case-study using available R functions, and provide complete R code for a simulated example as a supplement.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.212-217
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• 2001

This paper presents the stability characteristics of a rotor-bearing system supported by actively controlled hydrodynamic journal bearing. The proportional and derivative controls including coupled motion are adopted for the control algorithm to control the hydrodynamic journal bearing with a circumferentially groove. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than conventional analysis which uses the Reynolds condition. The stability characteristics are investigated with the Routh-Hurwitz criteria using the linear dynamic coefficients which are obtained from the perturbation method. The stability characteristics of the rotor-bearing system supported by active controlled hydrodynamic journal bearing are investigated for various control gain. It is found that the speed at onset of instability is increased for both proportional and derivative control of the bearing, and the proportional and derivative control of coupled motion is more effective than proportional and derivative control of uncoupled motion.

• 패션비즈니스
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• 제10권6호
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• pp.91-109
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• 2006

This study aims at strengthening the national competitiveness of Korea's clothing industry as it provides substantial information on the human body proportion and proportional dimension standards for Chinese women and improves the fitness of clothing, considering human proportion in the production of clothing products for export to China. This study selected by simple random sampling Chinese women in Beijing and Shanghai, China, whose age is between 19-50 from June 23 to August 7, 2004. The stature of the average Chinese woman belonging to the High Frequency group is 7.09 times as long as the length of the head. We developed the body proportional dimension standards with the same proportion with High-Frequence group. The basic size of proportional dimension standards for Chinese women has the stature of 159cm, (chest circumference)/2 of 42.8cm.

• 대한기계학회논문집A
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• 제35권12호
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• pp.1607-1612
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• 2011

본 논문에서는 솔레노이드 밸브의 동특성 분석 후, 적분기가 추가된 LQG/LTR 제어기를 설계한다. 솔레노이드 밸브의 동특성은 백색잡음 입력 신호에 대한 출력응답을 측정하여 얻은 주파수 응답과 커브피팅을 통해 규명된다. 본 논문에서 적분기가 추가된 LQG/LTR 제어의 목적은 시스템의 응답성을 향상시킬 뿐만 아니라 복잡한 입력신호에 대한 추종 능력도 향상시키는 것이다. 마지막으로 실험을 통해 제어기의 성능이 검증되며, 성능이 향상되었음을 확인할 수 있다.

• 터널과지하공간
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• 제8권2호
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• pp.79-86
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• 1998

This study was performed to suggest to suggest suitable design conditions of water curtain system through analysis on pressure down in boreholes by hydraulic tests carried out I construction fields for underground oil storages. The influence by hydraulic conductivities of rock mass around boreholes on pressure down in boreholes was analysed. The relationship between array of boreholes and their pressure down was also analysed. Groundwater flow analysis on crude oil and LPG storages was carried out to evaluate results of field tests and to investigate distribution of hydraulic gradient in rock mass around cavern using finite difference method. As the results, hydraulic tests showed that pressure down in boreholes was inverse proportional to the hydraulic conductivity of surrounding rock mass. The rate of pressure down of boreholes was not influenced by water curtain system more than 20m over cavern and was proportional to installation interval of boreholes. The hydraulic gradient in rock mass around cavern was proportional to distance and interval of boreholes and its value was not satisfactory to oil tightness condition in case of no water curtain system.

• 한국소음진동공학회논문집
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• 제16권5호
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• pp.470-478
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• 2006

An efficient method for change of eigenvectors and eigenvalues due to the modifying proportional damping structure using sensitivity coefficients is presented. Sensitivity coefficients are determined by iteration with eigenvalue and eigenvectors before modification of system. The proposed method is applied to examples of 3 degrees of freedom system and plate by modifying mass and stiffness. The predicted change of eigenvectors and eigenvalues are in a good agreement with these from the structural re-analysis after modification of mass and stiffness.

• Journal of the Korean Data and Information Science Society
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• 제9권2호
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• pp.119-138
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• 1998

The case of proportional cell frequencies for the two-way cross-classification with interaction is considered. Several types of hypotheses for the general unbalanced data that are commonly used in the literature are shown, and they are written out for this particular case. A reparameterized form of the cell means model is defined to establish the reparameterized model, and orthogonal property of the model is shown using the augmented matrix and the numerator sums of squares are computed. Different ways of producing the same analysis of variance tables are shown in both orthogonal and nonorthogonal situations.