• Journal of Korean Society for Quality Management
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• v.41 no.4
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• pp.709-724
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• 2013

Purpose: The purpose of this study is to examine five evaluation models constructed by different normalization and aggregation methods in terms of the volatility of rankings and rank reversals. We also explore how the volatility of rankings of the five models changes and how often the rank reversals occur when the outliers are removed. Methods: We used data published in the Complete University Guide 2014. Two universities with missing values were excluded from the data. The university rankings were derived by using the five models, and then each model's volatility of rankings was measured. The box-plot was used to detect outliers. Results: Model 1 has the lowest volatility among the five models whether or not the outliers are included. Model 5 has the lowest number of rank reversals. Model 3, which has been used by many institutions, appears to be in the middle among the five in terms of the volatility and the rank reversals. Conclusion: The university rankings vary from one evaluation model to another depending on what normalization and aggregation methods are used. No single model exhibits clear superiority over others in both the volatility and the rank reversal. The findings of this study are expected to provide a stepping stone toward a superior model which is both reliable and robust.

• Journal of the Korean Society of Safety
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• v.25 no.4
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• pp.61-67
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• 2010

Though "Zero Accident Campaign" is a desirable campaign for industrial accident prevention and reducing victims, the number of industrial enterprises has been decreasing abruptly in recent years. One of the reasons for this phenomenon may be attributed to irrationality of 'target accident-free time periods' established by related organizations. This study was carried out to develop a new rational scheme for the campaign. Therefore, for a numerical basis, Poisson process was introduced, and problems induced by current target periods were analyzed mathematically one by one. As a result, it was verified that current target periods were uneven since the probability that manufacturing plants get them would be different form industry to industry. To develop countermeasures, a brand new method were suggested in this research. The first characteristic was that group classification should be based upon average accident rates resulted from past several years, and the second was that adjustment probability which can make the target acquisition probability even. About the suggested method, a questionnaire survey was conducted. To make a conclusion, most manufacturing plants agreed with the suggested method such high affirmative portion that the suggested method would be expected to help promote the campaign again.

• The Korean Journal of Applied Statistics
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• v.19 no.1
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• pp.81-96
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• 2006

This paper proposes a simple control chart method which can be practically used for asymmetric process data where the distribution is unknown. If we use the Shewhart type control charts which are based on normality assumption for the asymmetric process data, the type I error could increase as the asymmetry increases and the effectiveness of control chart to control variation decreases. To solve such problems, this paper suggests to calculate the control limits based on the quartiles. If we obtain the control limits by such quartile method, the type I error could decrease and it looks much more practical for asymmetric distributed process data.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.421-428
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• 2005

This paper described operation and vibration characteristics of a 'tail-fan' anti-torque performance test system. KARI (Korea Aerospace Research Institute) developed a 'tail-fan' anti-torque system of a helicopter and a performance test-rig to test the performance of the tail-fan. The performance test-rig consists of driving, supporting and rotating parts. In the process of the performance test, firstly, operation test of the test-rig were carried out to verify design specifications. Secondly, natural frequencies of fan blade and test-rig were measured respectively. Lastly, to find the operation rotating speed for the performance test, vibration test were carried out using accelerometers on tail gear box. The performance test conditions of the tail-fan to avoid a resonance were found from the fan-plot and vibration test results. The tail-fan performance tests were well done safely.

• Journal of Periodontal and Implant Science
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• v.30 no.2
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• pp.483-490
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• 2000

The aim of this study was to analyze the reliability of an ultrasonic device(SDM) measuring soft tissue thickness in relation to tooth position, and to find factors which can influence the reliability. The results showed that 1. measurement error was the largest in the maxillary second molar position and the smallest in the mandibular central incisor position. 2. in a box whisker plot, the difference between two measurements was most widely distributed in molar positions. 3. in Pearson correlation analysis, the relationship between two measurements was the highest in the maxillary lateral incisor position and, the lowest in the maxillary second molar, mandibular first and second premolar position. 4. a stepwise multiple regression analysis could explain the difference of two measurements with various independent variables in 29.7% (P<0.0001). Gingival thickness was the only variable influencing the measurement difference in a statistically significant level(P<0.0001). It can be concluded that its high reliability, ease to use and patient comfort justified the application of the SDM in measurement of soft tissue thickness.

• Journal of Powder Materials
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• v.20 no.3
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• pp.191-196
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• 2013

Nano-sized cobalt powder was fabricated by wet chemical reduction method at room temperature. The effects of various experimental variables on the overall properties of fabricated nano-sized cobalt powders have been investigated in detail, and amount of NaOH and reducing agent and dropping speed of reducing agent have been properly selected as experimental variables in the present research. Minitab program which could find optimized conditions was adopted as a statistic analysis. 3D Scatter-Plot and DOE (Design of Experiments) conditions for synthesis of nano-sized cobalt powder were well developed using Box-Behnken DOE method. Based on the results of the DOE process, reproducibility test were performed for nano-sized cobalt powder. Spherical nano-sized cobalt powders with an average size of 70-100 nm were successfully developed and crystalline peaks for the HCP and FCC structure were observed without second phase such as $Co(OH)_2$.

• Journal of Dental Anesthesia and Pain Medicine
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• v.16 no.2
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• pp.117-122
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• 2016

Background: The aim of this study was to compare the effectiveness and duration of action of two concentrations of bupivacaine with adrenaline for postoperative pain in patients undergoing surgical removal of four third molars under general anesthesia. Methods: Sixty patients undergoing surgical removal of four wisdom teeth received bupivacaine 0.5% (n = 30) or 0.25% (n = 30). The severity of pain in the immediate recovery period and at 2 and 24 h after surgery was recorded using the visual analogue scale. Differences were assessed by box and whisper plot and the Student's t-test. Results: The analgesic effects of the 0.25% and 0.5% doses were significantly different (P = 0.022) at 30 min after surgery but not after 2 and 24 h. The difference of mean of 0.25% and 0.5% was much higher after 0.5 h but less after 2 and 24 h. Conclusions: Bupivacaine 0.5% was statistically better for pain control during the immediate postoperative period, but there was no significant difference in pain control between the two dose strengths at 2 and 24 h after surgery.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1824-1827
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• 2003

During normal machine operation, partial discharge(PD) measurements were performed with turbine generator analyzer(TGA) in two high voltage motors. Two 6.6kV motors were installed with 80pF capacitive couplers at the terminal box. The PD patterns were displayed two dimensional and three dimensional. TGA summarizes each plot with two quantifies such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). Off-line PD measurements were conducted on one 4.16kV motor. The motor was energized to 2.4kV, 3.0kV, 3.5kV and 4.16kV, respectively. The PD levels in pC were measured with a conventional digital PD detector. The comparison of positive to negative PD indicates whether the defect elements of PD are within the insulation or on the insulation surface. Discharge at conductor surface was discovered in No. 1 motor. Internal discharges were generated in phase A, B and C of No. 2 motor, Slot discharges occurred in three phases of No. 3 motor.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1828-1830
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• 2003

Partial discharge(PD) tests are used to evaluate the insulation condition of stator windings in two 4.16kV and three 6.6kV motors. These tests were conducted using a conventional partial discharge detector(PDD) and turbine generator analyzer(TGA). Off-line PD measurements were performed on five high voltage motors. PD magnitudes ranged from 1000 pC to 5400 pC at the normal line-to-ground voltage. Five high voltage motors have been equipped with 80pF epoxy-mica coupler on the motor terminal box. The PD pulse from sensors were measured with the TGA instrument. TGA summarizes each plot with two Quantities such as the peak PD magnitude(Qm) and the total PD activity(NQN). The defect mechanisms of high voltage motor can be associated with PD patterns such as internal, slot and conductor surface discharges. The PDD and TGA test results of No. 4 motor showed that internal discharge was detected in voids of the groundwall insulation.

• Molecules and Cells
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• v.44 no.11
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• pp.843-850
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• 2021

The rapid increase in collateral omics and phenotypic data has enabled data-driven studies for the fast discovery of cancer targets and biomarkers. Thus, it is necessary to develop convenient tools for general oncologists and cancer scientists to carry out customized data mining without computational expertise. For this purpose, we developed innovative software that enables user-driven analyses assisted by knowledge-based smart systems. Publicly available data on mutations, gene expression, patient survival, immune score, drug screening and RNAi screening were integrated from the TCGA, GDSC, CCLE, NCI, and DepMap databases. The optimal selection of samples and other filtering options were guided by the smart function of the software for data mining and visualization on Kaplan-Meier plots, box plots and scatter plots of publication quality. We implemented unique algorithms for both data mining and visualization, thus simplifying and accelerating user-driven discovery activities on large multiomics datasets. The present Q-omics software program (v0.95) is available at http://qomics.sookmyung.ac.kr.