• Archives of Craniofacial Surgery
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• v.10 no.1
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• pp.23-28
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• 2009

Purpose: Blow out fracture can present tenderness, swelling, enophthalmos, extraoccular muscle limitation, paresthesia, diplopia according to severity of injury, so reconstruction of blow out fracture is important. Orbital soft tissue should be in orbit and defected orbital wall should be corrected by autologus tissue or alloplastic implants. Every implants have their merits and faults, every implants are used various. This study was designed to compare the sequelae of blow-out fracture repair using the alloplastic implants: micro-titanium mesh(Micro Dynamic titanium $mesh^{(R)}$, Leibinger, Germany), porous polyethylene ($Medpor^{(R)}$, Porex, USA), absorbable mesh plate(Biosorb $FX^{(R)}$ . Bionx Implants Ltd, Finland). Methods: Between January 2006 and April 2008, 52 patients were included in a retrospective study analysing the outcome of corrected inferior orbital wall fracture with various kind of implants. Implants were inserted through subciliary incision. Twenty patients were operated with micro-titanium mesh, fourteen patients with porous polyethylene and eighteen patients with absorbable mesh plate. In comparative category, enophthalmos, diplopia, range of motion of extraoccular muscle, inferior orbital nerve injury were more on frequently statistically in patients. Results: Fourteen of 18 patients underwent surgical repair to improve diplopia, 11 of 17 patients to improve parasthesia, 11 of 15 patients to improve enophthalmos, 8 of 9 patients to improve extraoccular muscle limitation. Duration of follow-up time ranged from 6 months to 12 months(mean, 7.4 months). There was no statistic difference of sequelae between micro titanium mesh and porous polyethylene and absorbable mesh plate in blowout fracture, inferior wall. Conclusion: There is no difference of sequelae between micro-titanium mesh, porous polyethylene and absorbable mesh plate in blow-out fracture, inferior wall. The other factors such as defect size, location, surgeon's technique, may influence the outcome of blow-out fracture repair.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.1
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• pp.65-72
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• 1992

The purpose of this study was to evaluate the flexure stregth of posterior 4-unit acrylic resin bridge with different pontic designs : 1) Conventional pontic 2) Hygienic pontic and 3) Modified hygienic pontic. All specimens were made of self-curing acrylic resin for provisional restorations. Self-curing acrylic resin was filled in a silicone mold by the drop-on technique ; and was polymerized in a pressure spot under 20 psi pressure. The test specimens which were simply shaped posterior 4-unit bridge were 38mm ion 4mm wide, and 35mm thick(connector : 3mm thick). Each specimen was subjected to an increasing load of Instron machine with its tip centered on the specimen at 90-degree angle, and the machine was operated with its load cell of 50kg and its crosshead speed, 2mm/minute : and then the load values at the moment of the fracture of them were recorded. This study was also performed to analyze their stress distributions by the finite element method. The obtained results were as follows : 1. Flexure strength of the hygienic pontic(9.78kg) and the modified hygienic pontic(10.17kg) was higher than that of conventional pontic(6.96kg). But no significant difference was found between the hygienci pontic and the. modified hygienic pontic. The above statistic values were appraised by ANOVA and Duncan's multiple range test 2. Stress was concentrated on the middle portion in every group : and the stress of conventional pontic was found the greatest of all pontic designs.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.1-15
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• 2008

Recently, because of the various factors by uncertainty of underground, the risks in tunnelling have been occurred increasingly. Therefore, it is very important to estimate and control the risks considering geotechnical conditions for tunnel stability and environmental problems by tunnel construction. In this study, the risk analysis for tunnel stability was carried out by classifying the risk factors such as ground support capacity, ground settlement, the inflow of groundwater into the tunnel and the damage by the earthquake. Also, the risk assessment for the environmental problems was performed by calculating the vibration and noise by blasting and the drawdown of the groundwater level caused by tunnel construction. Each risk factor was evaluated quantitatively based on the probabilistic and statistic technique, then it was analyzed the distribution characteristic along overall tunnel site. Finally, it was evaluated that how much each risk factor influences on the construction cost with a period for tunnel construction, so it is possible to perform reasonable tunnel design which was capable of minimizing the risks in the tunnel construction.

• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.505-516
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• 2011

Purpose: The purpose of this study is to supply basic data to establish new image for dental technicians by reflecting onto the education of dental technicians by grasping the image of dental technicians with the subjects of students in department of dental technology. Methods: It was studied with self-filling-in method through structured questionnaire from September 26, to October 21, 2011, with 421 subjects of the students in the department of dental technology in two colleges in Daegu. SPSS 18.0 for Windows was used to analyze the data, and frequency and percentage were used for statistic analysis, and correlation analysis and Multiple Linear Regression Analysis were used with mean and SD per each question. Results: It showed the highest recognition that the dental technicians is a 'specialist' as 4.66; the dental technicians has strong responsibility in his work as 4.42; the dental technicians takes an important role in improvement of public oral health as 4.39; and the dental technicians has professional intelligence and high technique as 4.33. So, it was found that they had image of professional and important role for oral health, and had their pride and selfconfidence as future dental technicians. Meanwhile, it showed that they had negative related-image as well as a job, that the dental technicians is too busy as 4.48; it requires improvement on image in the future as 4.27; it is a hard job with too much stress as 4.13. Conclusion: It is required for us and school to have continuous change and effort to make the students in the department of dental technology have positive mind for the dental technology to make them have pride for their job.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.791-798
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• 2018

The CFAR algorithm is mainly used for target detection in radar systems. In particular, OS CFAR is used in a non-uniform noise environment. However, it requires a large amount of computation, because it should sort reference cells in ascending order. This makes it difficult to apply the radar system in real time. In this paper, we describe how to reduce the computational burden of OS CFAR. We compared the power of the test cell and reference cell to determine only the presence or absence of target detection. The common reference cells overlapping in the reference cells of the three test cells are obtained. We first compare the test cell with the highest power value among the three test cells to the common reference cells. Next, we compare each test cell to general reference cells, excluding the common reference cells. The computation time is shortened by reducing the power comparison computation amounts.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.587-595
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• 2008

In order to aid the derivation of the IDF relationship for a station with insufficient duration-rainfall data, an approach to derive a simple and practical IDF formula is presented. The IDF formula is described simply by the term of the two parameters and a design frequency. The model parameters were estimated from a statistical technique based on the normal distribution of transformed rainfall intensities. In order to give the transformed data, both the Kruskal-Wallis statistic and the Manly transformation of duration-rainfall data were adopted. With the methods, the proposed IDF formula becomes a simpler model that compares well with conventional form. In addition, it allows avoiding an exceptional condition of the higher rainfall intensity for longer duration. The performance of the proposed formula was evaluated by using the limited rainfall data for short duration from two gauge stations. The result showed that the IDF formula developed in this work was an effective tool, providing a reliable relationship between the intensity and duration even though insufficient data are only available.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.821-831
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• 2014

Stochastic rainfall generators or stochastic simulation have been widely employed to generate synthetic rainfall sequences which can be used in hydrologic models as inputs. The calibration of Poisson cluster stochastic rainfall generator (e.g. Modified Bartlett-Lewis Rectangular Pulse, MBLRP) is seriously affected by local minima that is usually estimated from the local optimization algorithm. In this regard, global optimization techniques such as particle swarm optimization and shuffled complex evolution algorithm have been proposed to better estimate the parameters. Although the global search algorithm is designed to avoid the local minima, reliable parameter estimation of MBLRP model is not always feasible especially in a limited parameter space. In addition, uncertainty associated with parameters in the MBLRP rainfall generator has not been properly addressed yet. In this sense, this study aims to develop and test a Bayesian model based parameter estimation method for the MBLRP rainfall generator that allow us to derive the posterior distribution of the model parameters. It was found that the HBM based MBLRP model showed better performance in terms of reproducing rainfall statistic and underlying distribution of hourly rainfall series.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.3
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• pp.110-118
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• 2000

For reasonable fatigue design and estimation of fatigue durability considered fatigue strength and stiffness of the automotive body structure, many fatigue data must be insured according to the shapes, materials, and welding conditions of the spot welded lap joints. However, because it is actually difficult problem, there is need to establish a new method to be able to predict its fatigue life without any additional fatigue tests. Therefore, In order to improve such problems, in this study, the maximum stress function presenting the $\delta\sigma_{1max}―\delta P$ relation was defined form the relation between $\delta\sigma_{1max}-N_f$ and ${\delta}P-N_f$. By using the fatigue data on the IB type spot-welded lap joints previously obtained from the fatigue test results, fatigue life of the spot-welded lap joint previously obtained from the fatigue test results, fatigue life of the spot-welded lap joint having a certain dimension was tried to predict without any additional fatigue tests. And, its result was verified by ${\delta}P-$N_f$ curves. Obtained conclusion are as follows, 1) a maximum stress function considered the relation of the maximum principal stress, fatigue load, and the effects of geometrical factors of the IB type spot-welded lap joint was suggested. 2) the fatigue life predicted by the maximum principal stress function and the relation of $\delta\sigma_{1max}-N_f$ was well agreed with the fatigue life obtained through the actual fatigue test result. 3) the fatigue life of the IB type spot-welded lap joint having a certain dimension is able to be predicted without any additional fatigue tests from the fatigue life prediction method by the maximum principal stress function.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.46-54
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• 2017

'Consulting', which is the main research topic of the knowledge service industry, is a field of study that is essential for the growth and development of companies and proliferation to specialized fields. However, it is difficult to grasp the current status of international research related to consulting, mainly on which topics are being studied, and what are the latest research topics. The purpose of this study is to analyze the research trends of academic research related to 'consulting' by applying quantitative analysis such as topic modeling and statistic analysis. In this study, we collected statistical data related to consulting in the Scopus DB of Elsevier, which is a representative academic database, and conducted a quantitative analysis on 15,888 documents. We scientifically analyzed the research trends related to consulting based on the bibliographic data of academic research published all over the world. Specifically, the trends of the number of articles published in the major countries including Korea, the author key word trend, and the research topic trend were compared by country and year. This study is significant in that it presents the result of quantitative analysis based on bibliographic data in the academic DB in order to scientifically analyze the trend of academic research related to consulting. Especially, it is meaningful that the traditional frequency-based quantitative bibliographic analysis method and the text mining (topic modeling) technique are used together and analyzed. The results of this study can be used as a tool to guide the direction of research in consulting field. It is expected that it will help to predict the promising field, changes and trends of consulting industry related research through the trend analysis.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.246-252
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• 2017

In the defense acquisition, a company's goal is to maximize profits, and the government's goal is to allocate budgets efficiently. Each year, the government estimates the ratio of indirect cost sector to defense companies, and estimates the ratio to be applied when calculating cost of the defense articles next year. The defense industry environment is changing rapidly, due to the increasing trend of defense acquisition budgets, the advancement of weapon systems, the effects of the 4th industrial revolution, and so on. As a result, the cost structure of defense companies is being diversifying. The purpose of this study is to find an alternative that can enhance the rationality of the current methodology for estimating the ratio of indirect cost sector of defense companies. To do this, we conducted data analysis using the R language on the cost data of defense companies over the past six years in the Defense Integrated Cost System. First, cluster analysis was conducted on the cost characteristics of defense companies. Then, we conducted a regression analysis of the relationship between direct and indirect costs for each cluster to see how much it reflects the cost structure of defense companies in direct labor cost-based indirect cost rate estimates. Lastly a new ratio prediction model based on regularized regression analysis was developed, applied to each cluster, and analyzed to compare performance with existing prediction models. According to the results of the study, it is necessary to estimate the indirect cost ratio based on the cost character group of defense companies, and the direct labor cost based indirect cost ratio estimation partially reflects the cost structure of defense companies. In addition, the current indirect cost ratio prediction method has a larger error than the new model.