• Journal of Digital Convergence
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• v.16 no.2
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• pp.151-156
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• 2018

The purpose of this study is to conduct a meta-analysis of 18 papers that can be verified among the papers on the subject of TPM. Five hypotheses were set for the analysis and meta - analysis was carried out with CMA as presented in each research paper. As a result of analysis, I-square value is more than 75% in four hypotheses. Therefore, the null hypothesis that the size of the population effect is the same for all studies was rejected. The reason for the heterogeneity is that the research characteristics such as the distribution of the respondents, the study conditions, the study period, and the study area are different. In this case, a summary statistic of the individual studies that can be classified according to the characteristics of the research is needed to analyze the effect size difference. However, individual studies do not provide a summary statistic that can classify the effect differences, so it is not possible to analyze the causes of heterogeneity.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.64-72
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• 2016

In this paper, we utilize a Gaussian process to predict the power consumption in the air-conditioning system. As the power consumption in the air-conditioning system takes a form of a time-series and the prediction of the power consumption becomes very important from the perspective of the efficient energy management, it is worth to investigate the time-series model for the prediction of the power consumption. To this end, we apply the Gaussian process to predict the power consumption, in which the Gaussian process provides a prior probability to every possible function and higher probabilities are given to functions that are more likely consistent with the empirical data. We also discuss how to estimate the hyper-parameters, which are parameters in the covariance function of the Gaussian process model. We estimated the hyper-parameters with two different methods (marginal likelihood and leave-one-out cross validation) and obtained a model that pertinently describes the data and the results are more or less independent of the estimation method of hyper-parameters. We validated the prediction results by the error analysis of the mean relative error and the mean absolute error. The mean relative error analysis showed that about 3.4% of the predicted value came from the error, and the mean absolute error analysis confirmed that the error in within the standard deviation of the predicted value. We also adopt the non-parametric Wilcoxon's sign-rank test to assess the fitness of the proposed model and found that the null hypothesis of uniformity was accepted under the significance level of 5%. These results can be applied to a more elaborate control of the power consumption in the air-conditioning system.

• Korean Journal of Optics and Photonics
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• v.15 no.3
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• pp.241-247
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• 2004

The collimator is necessary for the assembly and evaluation of high resolution satellite telescope. Traditionally, the off-axis paraboloid has been used as a collimator. However, it has some disadvantages in that it can suffer from air turbulence when the focal length of a collimator is long, which may result in some error in the measurement. In contrast, since the Cassegrain type collimator folds the beam, it occupies smaller space compared to the off-axis paraboloid for the same focal length. This can reduce the air turbulence, which can improve the measurement accuracy. In this paper, we explain the process of design and manufacturing of a diameter 450 mm Cassegrain type collimator, to evaluate the diameter 300 mm satellite telescope. After assembly of primary and secondary mirrors, the final wavefront error of the collimator was 0.07λ(λ=633 nm), which is the diffraction limit.

• Journal of Periodontal and Implant Science
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• v.47 no.3
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• pp.182-192
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• 2017

Purpose: Contact and distance osteogenesis occur around all endosseous dental implants. However, the mechanisms underlying these processes have not been fully elucidated. We hypothesized that these processes occur independently of each other. To test this, we used titanium (Ti) tubes to physically separate contact and distance osteogenesis, thus allowing contact osteogenesis to be measured in the absence of possible triggers from distance osteogenesis. Methods: Sandblasted and acid-etched (SLA) and modified SLA (modSLA) implants were used. Both types had been sandblasted with large grit and then etched with acid. The modSLA implants then underwent additional treatment to increase hydrophilicity. The implants were implanted into rabbit tibiae, and half were implanted within Ti tubes. The bone-to-implant contact (BIC) ratio was calculated for each implant. Immunohistochemical analyses of bone morphogenetic protein (BMP)-2 expression and new bone formation (Masson trichrome stain) were performed. Results: The implants outside of Ti tubes were associated with good bone formation along the implant surface. Implantation within a Ti tube significantly reduced the BIC ratio (P<0.001). Compared with the modSLA implants, the SLA implants were associated with significantly higher BIC ratios, regardless of the presence or absence of Ti tubes (P=0.043). In the absence of Ti tubes, the bone adjacent to the implant had areas of new bone formation that expressed BMP-2 at high levels. Conclusions: This study disproved the null hypothesis and suggested that contact osteogenesis is initiated by signals from the old bone that undergoes distance osteogenesis after drilling. This signal may be BMP-2.

• Environmental and Resource Economics Review
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• v.23 no.1
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• pp.43-65
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• 2014

In this paper, we test for allocative efficiency of productive inputs including electricity and measure the divergence between the actual and optimal level of electricity for the chemical products, which is a relatively highly electricity-intensive sector in Korean manufacturing industries, by estimating a shadow cost function. Supposing cost minimization subject to market prices was achieved, we derive the price elasticities of demand for each input and simulate the impact of a 10% increase in power rate on its demand and supply price by estimating jointly a cost function with an inverse supply relation. The null hypothesis of allocative efficiency of inputs is rejected over the period 1982-2006. On average, electricity is used more than optimal level by 98% per year. The demand for electricity decreases by 11.4%, and supply price, on average, falls by 0.08%, other things being equal.

• The Korean Journal of Applied Statistics
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• v.30 no.6
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• pp.1027-1036
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• 2017

Multiple comparisons are required to confirm whether or not something is significant if the null hypothesis to test whether the difference between more than three treatments is rejected in a one-way layout. There are both parametric multiple comparison method Tukey (1953) and Nonparametric multiple comparison method based on Kruskal-Wallis (1952).This procedure is applied to a mixed sample of all data and then an average ranking is used for each of three or more treatments. In this paper, a new nonparametric multiple comparison procedure based on joint placements for a one-way layout as extension of the joint placements described in Chung and Kim (2007) was proposed. Monte Carlo simulation is also adapted to compare the family wise error rate (FWE) and the power of the proposed method with previous methods.

• The Journal of Korean Physical Therapy
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• v.16 no.3
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• pp.192-204
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• 2004

The surface electromyographic(sEMG) analyses were knee joint angle during open kinetic chain exercise (OKC) and close kinetic chain exercise (CKC) in vastus medialis (VM), vastus lateralis (VL), and rectus femoralis (RF). Ten subjects with normal , aged 20 to 30(X=27.4, SD=3.23), were randomized Statistical techniques for data analysis were applied paired t-test. The 0.05 level of significane was used as the critical level for rejection of the null hypotheses for the study. And the results were: 1) Both OKC and CKC improved the strength of quadriceps muscle as the knee joint flexion was increased. 2) In OKC, the strength of VM was improved the most at the 30 degree angle. 3) In CKC, the strength of VM was improved the most at the 30 degree angle. 4) The VM/VL ratio was the largest at the 10 and 20 degree angles in OKC and CKC. 5) The VM/VL ratio at 10, 20, and 30 degree angles was significantly different between OKC and CKC (P < 0.05). Base on the results, the OKCE is recommended for the knee joint patients, especially for the patellofemoral pain syndrome patients, during the early phase of rehabilitation. In order to improve strength of the quadriceps, muscle strength training at 30 degree angle is recommended. In order to improve VM/VL ratio, 10 and 20 degree angles are recommended during OKCE and CKCE, respectively. Future researches are warranted comparing electromyographic analysis between OKCE and CKCE in the quadriceps at a certain work lead, and muscle strength performance in the quadriceps at different positions of foot.

• Journal of Korean Society of Transportation
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• v.35 no.5
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• pp.447-457
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• 2017

This study aims to analyze the accidents of green mode bicycle. In pursuing the above, this study gave special emphasis on modeling the bicycle accidents reflecting the regional characteristics. The main results are as follows. First, the null hypotheses that the number of accident and ratio of serious injury and fatality (FSI) were the same over regions were rejected. Second, as the common variables, the number of bicycle was judged to have positive (+) impact to the accidents and the bicycle using ratio was inferred to increase the ratio of FSI. Third, the elderly population ratio among 3 factors which gave impact to the accidents of Si_A (city-county consolidation) was concluded to have the greatest elasticity. The developed area ratio between 2 factors in Si_B (city which is not consolidated) was, however, estimated to have the higher elasticity. Fourth, the number of car registration among 5 accident factors of Gun (county) was analyzed to have the greatest elasticity. Finally, the commuting trip ratio among 7 accident factors of Gu (district) was judged to have the greatest elasticity. This study can be expected to give some implications to regional policy-making related to bicycle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.414-419
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• 2016

A study of a precision test according to the control method of an injection molding machine was carried out. The effects of the screw stroke, holding pressure, melt temperature on both the hydraulic and electric injection molding machine were examined. In addition, hypothesis testing was performed to determine the deviation of the data obtained in the experiments. The conclusions obtained in this study were as follows. Significant deviations in the screw stroke, melt temperature and holding pressure occurred in that order. The hydraulic type showed significantly more variation between the products compared to the electric type. In addition, using a mini tab from the statistics program, a hypothesis was proposed and the P value of the injection stroke, holding pressure, melting temperature injection stroke and melting temperature had adopted a null hypothesis ($H_0$). The holding pressure, which showed mutual differences, adopted an alternative hypothesis ($H_1$).

• Restorative Dentistry and Endodontics
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• v.41 no.1
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• pp.6-11
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• 2016

Objectives: The purpose of this in vitro study was to evaluate the accuracy of working length (WL) determination of four electronic apex locators (EALs), namely, Root ZX (RZX), Elements diagnostic unit and apex locator (ELE), SybronEndo Mini Apex locator (MINI) and Propex pixi (PIXI) using Stainless steel (SS) and nickel-titanium (NiTi) hand files. The null hypothesis was that there was no difference between canal length determination by SS and NiTi files of 4 EALs. Materials and Methods: Sixty extracted, single rooted human teeth were decoronated and the canal orifice flared. The actual length (AL) was assessed visually, and the teeth were embedded in an alginate model. The electronic length (EL) measurements were recorded with all four EALs using SS and NiTi files at '0.5' reading on display. The differences between the AL and EL were compared. Results: The results obtained with each EAL with SS and NiTi files were compared with AL. A paired sample t test showed that there was a statistical significant difference between EAL readings with SS and NiTi files for RZX and MINI (p < 0.05). The accuracy of RZX, ELE, MINI and PIXI within ${\pm}0.5 mm$ of AL with SS/NiTi files were 93.3%/70%, 90%/91.7%, 95%/68.3%, and 83.3%/83.3%, respectively. Conclusions: The results of this study indicate that Root ZX was statistically more accurate with NiTi files compared to SS files, while MINI was statistically more accurate with SS files compared to NiTi files. ELE and PIXI were not affected by the alloy type of the file used to determine WL.