• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.221-230
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• 2001

This study was performed to evaluate hard tissue cephalometric norms for Korean adults which can be implemented in surgical orthodontic treatment planning using selected horizontal reference plane especially for Koreans (Male: $SN-7.5^{\circ}$, Female: $SN-9.0^{\circ}$) and a simplified analytical method. 70 males and 70 females consisting of freshmen of Yonsei University from 1996 to 1997 and students from the Dental College of Yonsei University were chosen according to clinical examination and cephalometric analysis. The samples had normal profiles, normal anteroposterior skeletal relationship(ANB angle of $0^{\circ}$ to $4^{\circ}$ and Wits appraisal of -4.0mm to 0mm), and Class I molar and canine relationship. They had no missing or supernumerary teeth and had no experience of orthodontic or prosthetic treatment. After the selection of 23 landmarks and the construction of horizontal and vertical reference lines, 22 skeletal and 12 dental measurements were taken. These consisted of vertical and horizontal linear measurements and angular measurements. The results were as follows. 1. Mean and standard deviation of the measurements were calculated for males and females. 2. Most of the skeletal vertical measurements, and maxillary and mandibular length were bigger in males than females. Whereas anterior facial height ratio(N-ANS/ANS-Me) as well as maxillary and mandibular antero-posterior position in relation to the vertical reference line(N-perpendicular) showed no signigicant difference between sexes. 3. Maxillary and mandibular dental antero-posterior position in relation to the vertical reference line(N-perpendicular) showed no significant difference between sexes. 4. The upper incisor show(U1-Stms) was $2.1{\pm}1.7mm$ in males and $3.3{\pm}1.7mm$ in females. In this study, hard tissue cephalometric norms of Korean adults for orthognathic surgery were obtained.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.717-724
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• 2010

The flash point is one of the most important physical properties used to determine the potential for fire and explosion hazards of flammable liquids. Despite the needs of the experimental flash point data for the design and construction of chemical plants, there is often a significant gap between the demands for the data and their availability. This study have built and compared two models of partial least squares(PLS) and support vector machine(SVM) to predict the experimental flash points of 893 organic compounds out of DIPPR 801. As the independent variables of the models, 65 functional groups were chosen based on the group contribution method that was oriented from the assumption that each fragment of a molecule contributes a certain amount to the value of its physical property, and the logarithm of molecular weight was added. The prediction errors calculated from cross-validation were employed to determine the optimal parameters of two models. And, an optimization technique should be used to get three parameters of SVM model. This work adopted particle swarm optimization that is one of heuristic optimization methods. As the selection of training data can affect the prediction performance, 100 data sets of randomly selected data were generated and tested. The PLS and SVM results of the average absolute errors for the whole data range from 13.86 K to 14.55 K and 7.44 K to 10.26 K, respectively, indicating that the predictive ability of the SVM is much superior than PLS.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.2
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• pp.15-31
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• 2024

The characteristics of elderly traffic accidents were identified by reflecting the situation of the elderly population in Korea, which is entering an ultra-aging society, and the relationship between independent and dependent variables was analyzed by classifying traffic accidents of serious or higher and traffic accidents of minor or lower in elderly pedestrian traffic accidents using binomial variables. Data collection, processing, and variable selection were performed by acquiring data from the elderly pedestrian traffic accident analysis system (TAAS) for the past 10 years (from 13 to 22 years), and basic statistics and analysis by accident factors were performed. A total of 15 influencing variables were derived by applying the logistic regression model, and the influencing variables that have the greatest influence on the probability of a traffic accident involving severe or higher elderly pedestrians were derived. After that, statistical tests were performed to analyze the suitability of the logistic model, and a method for predicting the probability of a traffic accident according to the construction of a prediction model was presented.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.581-590
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• 2017

For effective improvement of water quality in Seokmun reservoir, this study implemented various analyses including the tributary water quality and flowrate monitoring, contamination of sediment, investigation of pollution source, selection of priority management target tributary by stream grouping method. The COD concentration of the majority of tributaries in Seokmun reservoir watershed was relatively higher than BOD concentration. The concentration of water pollutants regardless of water quality parameters in Yeokcheon, Dangjincheon, Sigokcheon, Baekseokcheon, small stream in Jinkwanri and Janghangri were higher than the other tributaries. The pollution sources in the Seokmun reservoir watershed were mostly distributed in the population, livestock, and industry. The pollutants, which located in Yeokcheon, Dangjincheon, Baekseokcheon, and small stream in Janghangri selected as priority management target tributary, should be preferentially reduced for improving the water quality in Seokmun reservoir. As the evaluation results of water quality in Seokmun reservoir for the effect of water quality improvement according to various scenarios using water quality model, it was found that the water quality in Seokmun reservoir due to the construction of a wastewater treatment plant for management of pollutants in the watershed would be satisfied the class V of water environment standard in reservoir.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.6
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• pp.545-559
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• 2002

There has been increasing use of IPS Empress $2^{(R)}$ owing to easy fabrication method, high esthetics similar to natural teeth, good marginal accuracy, and sufficient fracture strength. However, in clinical application, although a luting agent and the tooth cementation bonding procedure influence the marginal accuracy and fracture strength restoration, there has been a controversy in the selection of proper luting agent. This study was to measure the marginal fidelites and fracture strength of IPS Empress crowns according to three cement types, Protec $cem^{(R)}$, Variolink $II^{(R)}$ and Panavia $21^{(R)}$. After construction of 12 experimental dies for each group, IPS Empress $2^{(R)}$ crowns were fabricated and luted the metal master die prepartion of the maxillary right premolar. Marginal gaps before cementation and after cementation were measured. Buccal incline on the functional cusp of specimens were loaded until the catastrophic failure and fracture strength was measured. The results of this study were as follows: 1. The range of gap was $34.04{\pm}4.84{\mu}m$ before cementation and $37.88{\pm}5.00{\mu}m$ after cementation, which showed significant difference by paired t-test (p<0.05). The difference in the results from marginal accuracy according to measuring point proved to be not statistically significant by two-way ANOVA test (p>0.05). 2. The difference in the results from marginal accuracy according to three cement types Proved that The Variolink $II^{(R)}$ cement group had the least gap, $35.43{\pm}5.03{\mu}m$, and showed superior marginal accuracy while there existed statistic significance in Protec $cem^{(R)}$ cement group, $39.06{\pm}4.41{\mu}m$ or Panavia $21^{(R)}$ cement group, $39.16{\pm}4.39{\mu}m$ by two-way ANOVA test & multiple range test (p<0.05). 3. The difference in the results from fractures strength testing according to three cement type groups proved to be statistically significant (p<0.05). The Variolink $II^{(R)}$ cement group shows highest fracture strength of $1257.33{\pm}226.77N$, Panavia $21^{(R)}$ cement group has $1098.08{\pm}138.45N$, and Protec $cem^{(R)}$ cement group represents the lowest fracture strength of $926.75{\pm}115.75N$. 4. Three different cement groups of different components showed acceptable marginal fidelity and fracture strength. It is concluded that IPS Empress $2^{(R)}$ crowns luted using Variolink $II^{(R)}$ cement group had stronger fracture strength and smaller marginal gap than the other cement groups. Although Variolink $II^{(R)}$ resin cement seemed acceptable to clinical applications in IPS Empress $2^{(R)}$ system, the IPS Empress $2^{(R)}$ system still requires long-term research due to the lack of data in clinical applications.

• Journal of the Korean Geotechnical Society
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• v.26 no.5
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• pp.57-64
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• 2010

Kriging techniques have been used to estimate the spatial distribution of soil layers and soil properties in the geotechnical engineering area. Since the selected kriging technique may provide different values of estimation, the selection of method is important in the geotechnical estimation. In this paper, the spatial distribution of the thickness of consolidation layer of Songdo International City is estimated using simple, ordinary, and universal kriging techniques, and the reliability of estimated results is analyzed. It is shown that the consolidation layer thickness estimated by the simple kriging technique is larger than those by other kriging techniques when the location of estimation is far from the locations where the measured data exist. In this case, the reliability of the simple kriging technique is observed to be lower than those of other techniques. Universal kriging gives a negative value for thickness of consolidation layer in some locations away from the data. It is concluded that the ordinary kriging is the most optimized estimation technique because the reliability of ordinary kriging technique is higher than those of other ones and the consolidation layer thickness estimated by the ordinary kriging locates within the reasonable range.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.6
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• pp.45-52
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• 2019

As international criteria and standards are required in the fields of design and construction, landscape performance must also be considered not only for the value of the landscape but also for providing quality assurance and sustainability. Given the lack of research on landscape performance, the present research was purposed to analyze the importance of potential assessment categories and items using an analytical network process. A list of assessment items, which is composed of 20 items and 6 categories, was derived through a literature review and a preliminary survey of 11 landscape professionals. An ANP model was established and a survey was conducted among 30 landscape practitioners to determine the weight of priorities considering the criteria. The results of ANP showed that the categories of site selection, preservation and health, and convenience had high priorities while materials had the lowest importance score. For the assessment items, a monitoring plan was the highest importance, followed by cultural/ historic preservation, management cost reduction, and natural ground areas. Despite the difficulties in quantifying landscape achievements, most respondents agreed that there needs to be an evaluation system for landscape performance in order to assure the quality and sustainability of landscape development. More research and discussion are needed to develop an assessment system for landscape performance that is applicable to Korean context.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.851-857
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• 2018

In this research, LCA analysis of the manufacturing process of pot bearing for fixed, movable in all directions, movable in one direction was carried out to analyze the environmental load using the LCA methodology. Especially, the water footprint that has been and issue in recent years was analyzed. As a result of LCA, it was analyzed that the contribution of the plate was more than 64.2% in all of the six impact categories in the case of fixed pot bearing base, and more than 94% in the category of resource depletion and photochemical oxidant creation. In the case of all direction pot bearing and one direction pot bearing, the contribution of PTFE was the highest in the global warming and stratospheric ozone depletion, and the contribution by the plate was higher in the other impact categories. The water footprint of each type of pot bearing was analyzed as $22.4m^3\;H_2O\;eq/kg$ for one direction pot bearing, $17.1m^3\;H_2O\;eq/kg$ for fixed pot bearing, and $14.1m^3\;H_2O\;eq/kg$ for all direction pot bearing. As a result of life cycle analysis, the contribution of water use in manufacturing was more than 65% in all three types. The results of this study can be used as basic data for decision making in construction method and material selection of bridges in the future.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.458-467
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• 2019

The purpose of this study is the suggestion of optimized parameters in OI (Optimal Interpolation) by experimental study. The observation of applying optimal interpolation is ADCP (Acoustic Doppler Current Profiler) data at the southwestern sea of Korea. FVCOM (Finite Volume Coastal Ocean Model) is used for the barotropic model. OI is to the estimation of the gain matrix by a minimum value between the background error covariance and the observation error covariance using the least square method. The scaling factor and correlation radius are very important parameters for OI. It is used to calculate the weight between observation data and model data in the model domain. The optimized parameters from the experiments were found by the Taylor diagram. Constantly each observation point requires optimizing each parameter for the best assimilation. Also, a high accuracy of numerical model means background error covariance is low and then it can decrease all of the parameters in OI. In conclusion, it is expected to have prepared the foundation for research for the selection of ocean observation points and the construction of ocean prediction systems in the future.

• Journal of Digital Convergence
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• v.19 no.4
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• pp.355-363
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• 2021

The purpose of this research is to explore the selection attributes that the director of a taekwondo gym places importance on when purchasing a work of taekwon gymnastics for the competition. We conducted in-depth interviews with 6 participants using qualitative case study techniques, and analyzed data using Creswell's (2015) spiral analysis method. The data analysis results show music, trainees, characteristics of the work, criteria for evaluating the competition, producer competence, and price factors. As a result of the research, music should be produced around diverse and differentiated genres and music preferred by the trainees, and the appropriate theme should be selected considering the expressiveness and level of the trainees. The work should be considered creative works that harmonize the movement ratio of Taekwondo movements and dance, and the length of the work should be adjusted according to the purpose of the buyer, and the construction of the work should be based on the regulations of the competition. The manufacturer should ensure smooth communication with the buyer, including coaching ability and experience at the convention site. Prices will be affordable and affordable, and prices will need to be calculated based on special prices or mentoring periods for a small number of buyers.