• Imaging Science in Dentistry
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• v.42 no.3
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• pp.175-182
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• 2012

Purpose: The aim of this study was to provide sex-matched three-dimensional (3D) statistical shape models of the mandible, which would provide cephalometric parameters for 3D treatment planning and cephalometric measurements in orthognathic surgery. Materials and Methods: The subjects used to create the 3D shape models of the mandible included 23 males and 23 females. The mandibles were segmented semi-automatically from 3D facial CT images. Each individual mandible shape was reconstructed as a 3D surface model, which was parameterized to establish correspondence between different individual surfaces. The principal component analysis (PCA) applied to all mandible shapes produced a mean model and characteristic models of variation. The cephalometric parameters were measured directly from the mean models to evaluate the 3D shape models. The means of the measured parameters were compared with those from other conventional studies. The male and female 3D statistical mean models were developed from 23 individual mandibles, respectively. Results: The male and female characteristic shapes of variation produced by PCA showed a large variability included in the individual mandibles. The cephalometric measurements from the developed models were very close to those from some conventional studies. Conclusion: We described the construction of 3D mandibular shape models and presented the application of the 3D mandibular template in cephalometric measurements. Optimal reference models determined from variations produced by PCA could be used for craniofacial patients with various types of skeletal shape.

• Journal of the Korean GEO-environmental Society
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• v.18 no.7
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• pp.13-20
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• 2017

Soil nailing is ground reinforcement method using the shear strength of ground and the pullout shear resistance force of nail. It is mainly used for reinforcement of cut slopes, earth retaining structures and retaining walls, etc. It may be designed considering the pullout resistance of nail in the case of earth retaining structure and retaining wall, but it should be designed considering not only pullout resistance but also shear and bending resistance in the case of slope. However, conservative designs considering only pullout resistance are being done and most of the studies are about increasing pullout resistance by improving of material, shape and construction method of nail. Actually, Shear bending deformations occur centering on the active surface in ground reinforced with the nail. The grout with relatively low strength is destroyed and separated from the reinforcing material. As a result, the ground is collapsed while reducing the frictional resistance rapidly. Therefore, it is necessary to develop the method to increase the shear resistance while preventing separation of nail and grout body. In this study, an experimental study was conducted on new soil nailing method which can increase shear resistance by forming protrusions through pressurized grouting after installing a packer on the outside of deformed bar.

• Journal of Radiation Protection and Research
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• v.15 no.2
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• pp.113-122
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• 1990

After four years of planning, equipment acquisition, facility construction and beam testing, the KCCH cyclotron facility was put into operation in November1986. Now the KCCH cyclotron(MC-50) has been used for four years in neutron therapy and radioisotope production. Up to December 1989, 179(1852 sessions) patient have undergone neutron therapy. Radioisotope production for nuclear medicine use was started from March 1989 after extensive work to overcome target transport, target melting, beam diagnostic and chemical processing problems. This status report introduces the cyclotron facility, and the experiences of neutron therapy and isotope production with the MC-50 cyclotron. Besides, the operation results and the general troubles of the MC-50 during 1989 are summarized. Total operation time was 1252.5 hours. Four hundred hours were used for neutron therapy of 599 treatment sessions and 832.5 hours for radioisotope production. Total amount of produced raioisotope was 1695 mCi(Ga-67 : 1478mCi, Tl-201 : 107 mCi, I-123 : 25mCi, In-111 : 85mCi). Twenty hours were used for scheduled beam testing. In 1989, 882% of the planned operation were performed on schedule and this rats is improved remarkably compared to 71.0% in 1988.

• Journal of Environmental Health Sciences
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• v.40 no.5
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• pp.331-345
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• 2014

Objectives: The exponential growth of chemicals, an area of high concern in developed countries like the US (i.e., the Gore Initiative) and in the EU (i.e., REACH), as well as recent chemical accidents in Korea, have provoked nationwide concerns and resultant legal enforcement. This study aims to compare the laws of the Ministry of Environment (the Chemical Substances Control Act (CSCA), Act on the Registration and Evaluation, etc. of Chemical Substances (ARECS)) with those of the Ministry of the Employment and Labor (Occupational Safety and Health Act (OSHA)). Methods: Each law pertaining to the Ministry of Environment and the Ministry of the Employment and Labor was downloaded from the official legal information system (www.law.go.kr). The objectives of each law and the major contents related to chemical management were compared and summarized. Results: The CSCA and the ARECS are focused on the protection of people and the environment, while the OSHA relates to the protection of workers. The right to know of people and workers has been reinforced. The former two laws emphasize prevention, but the OSHA contains both preventive and post-accident measures. The role of the Ministry of Employment was reinforced with the promulgation of the CSCA and ARECS, which contain regulations such as adjacent area impact evaluation, risk control planning, chemical statistical survey and construction and operation of information, provision of risk control plans, response to chemical accidents and registration of chemical substances. Conclusion: We found that the three laws discussed here have several similar clauses designed to protect people and the environment from risks that may be caused by the use of chemicals, even though there are some differences among them in terms of objectives and contents. This review concluded that several clauses that can be regarded as double regulation should be unified in order to minimize the waste of government administrative resources and socio-economic losses.

• Asian Journal of Turfgrass Science
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• v.12 no.1
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• pp.49-78
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• 1998

Nowadays, there are increasing demands of golf courses and it is necessary to make more golf courses than the present. To do this, we need to improve the environmental problems with the regional inhabitants, and it is said that the first thing to be considered in developing any golf course in Korea is to preserve the environment. In this context, the purpose of this study is to set forth several design factors to lessen the negative impacts which are accompanied with the development of golf courses. 1. The present conditions of golf courses in Korea Many new golf courses have come into being, particularly since the late 1980s, and now, in the year of 1997, over one hundred of golf courses are doing their business, yet the number of golf course is still less than required. So far, over a half of them have been made in the vicinity of Seoul on account of various reasons, and this has adversely affected on our natural environment. This unreasonable development of golf courses has caused serious water pollution, landslides and the other problems. Also, the topography of Korea is not good for golf courses. Although the demands of golf courses are increasing, the suitable sites for them are very limited, and therefore it is sometimes unavoidable to make golf courses on steep hills. Consequently, in designing golf courses in Korea, the most important thing is the balance between natural environment and artificial environment. 2.Eco-friendly golf course design factors 1) The concept of eco-friendly golf courses Ecologically sustainable and sound golf courses which are made by eco-friendly approaches 2)Basic conditions of eco-friendly golf courses (1)The most suitable sites (2) Conservation of existing ground as much as possible (3)Proper use of agricultural chemicals which have great impacts on the environment (4) Reasonable use of fertilizers (5) Developing a specialized fertilizer only for grass (6) Adaptation of organic agriculture (7) Improvement of grass sorts (8) Establishing reservoirs for purifying the water from golf courses 3) Eco-friendly golf courses (1) Location-Enough area /Gentle slope/Winding ground/Including lakes or streams /Not crossing wind's main direction Facing south or southeast /Suitable soIl for grass /Good drainage /Low level of underground water (2)Course layout and design -Consideration about existing contours as much as possible -Adaptation of Scotish design trend -Various holes' configuration -Consideration toward surrounding landscapes -Reducing grass areas -Giving buffer zones -Adapting computer methods in the process of site analysis and design (3) Eco-friendly considerations in constructing and managing golf courses -Protection of wildlife -Reuse of existing forests and preservation of topsoil -Renovation of old-fashioned courses -Reducing grass areas -Purification of water -Standization of management -Strict regulations against chemicals -Recycling organic materials -Through separation of the water inside golf courses and out of bounds -Getting proper construction works done in a due time 4.Eco-friendly considerations from a viewpoint of cultural environment 1) Well-matched landscape design and events planning 2) Implement of identifications and awarding systerns 3)Acknowledgement of superintendents' qualitications in the maintenance of golf courses 4)Increasing public golf courses and keeping good relationships with the neighbors near golf courses Key words: Pro-environmental development, Golf course.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.3
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• pp.193-202
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• 2013

The concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn), nickel (Ni), and arsenic (As) in sand samples collected from selected children's playground and their correlation with environmental parameters, such as concentration of particulate matter in the atmosphere ($PM_{10}$), apartment age (> 5 years), clay and organic matter contents in sand samples, were analyzed. The average heavy metal concentration in samples was 0.040 mg $kg^{-1}$ for Cd, 0.200 mg $kg^{-1}$ for Cr, 1.75 mg $kg^{-1}$ for Cu, 15.1 mg $kg^{-1}$ for Ni, 3.42 mg $kg^{-1}$ for Pb, 66.7 mg $kg^{-1}$ for Zn and 0.750 mg $kg^{-1}$ for As, all of which were below the environmental regulatory level established by Korea Ministry of Environment. However, in the consideration of direct and oral exposure by children to playground sand, the risk of the concentration range in the samples might be greatly enhanced. Heavy metal concentration in samples collected from high $PM_{10}$ (> $70{\mu}gm^{-3}$) area was slightly greater than in samples from low $PM_{10}$ (< $70{\mu}gm^{-3}$), indicating the contribution of particulate matter in air phase to heavy metal concentration in playground sand samples. The concentrations of both Cd and Pb were the highest in apartments older than 21 years (0.050 mg $kg^{-1}$ and 5.28 mg $kg^{-1}$ for Cd and Pb respectively) and showed positive correlation with apartment age (p<0.01 and p<0.001 for Cd and Pb, respectively). Clay content in playground sands ranged 3.8~11.2% and was positively correlated with heavy metal concentration. Organic matter content was negligible (mostly < 0.1%) and showed poor correlation with heavy metal concentration. In conclusion, concentration of heavy metals in playground sand was found to be predominantly influenced by the apartment age and clay content in sand samples and supplemented by dust deposition of particulate matter ($PM_{10}$) from atmosphere.

• Journal of Korea Water Resources Association
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• v.43 no.3
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• pp.295-308
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• 2010

As an attempt to explore the impact of droughts which may be worse by the climate change, the change in the water balance of the Han-river basin is analyzed. To accomplish it, we suggest a procedure consisting of three successive sub-procedures: daily rainfall generation for 70 years by the RegCM3 RCM ($27{\times}27\;km$) with the A2 scenario, daily discharge simulations by SLURP using the generated daily rainfall data, and monthly water balance analysis by K-WEAP (Korean Water Evaluation and Planning System) based on the SLURP simulation. Since significant uncertainty is involved in forecasting the future water consumption and water yields, we assumed three water consumption scenarios and fifty water yields scenarios. Three water consumption scenarios are, namely, "LOW", "MEDIUM", and "HIGH" according to the expected amount of water consumption. The fifty daily discharges are obtained from the SLURP simulations during the drought period. Finally, water balance analysis is performed by K-WEAP based on 150 combinations from three water consumption scenarios and the fifty daily discharges. Analysis of water scarcity in small basins of the Han River basin showed concentration of water scarcity in some small basins. It was also found that water scarcity would increase in all small basins of the Han River basin.

• Journal of the Korean Geotechnical Society
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• v.33 no.7
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• pp.5-16
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• 2017

Soil nailing is the most general method to reinforce the slope by taking pullout and shear resistance force of the nail for stabilizing the slope. Domestic soil nailing design method considers only pullout resistance and does not consider the shear resistance sufficiently. In case of nail, the effect of tensile stress is dominant, but it is desirable to design by considering shear stress as well as tensile stress in case of slope where circle failures occur. Recently, studies on the shear resistance effect of nails have been carried out in the geotechnical field. However, many researches on the shear reinforcement effect of soil nailing have not been conducted until now. Most of the studies are about increasing pullout resistance by improving material, shape and construction method of nail. Therefore, it is necessary to the study on shear resistance of soil nailing and development of new methods to increase the shear force. In this study, large shear test and limit equilibrium analysis have been performed for a new soil nailing method to increase the shear resistance by forming protrusions through pressurized grouting after installing a packer on the outside of deformed bar. The study results showed that shear resistance of protrusion type soil nailing increased compared to soil nailing and it is more effective when applied to the ground with large strength parameters.

• Journal of the Korean Institute of Intelligent Systems
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• v.5 no.1
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• pp.52-64
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• 1995

Robot manipulator is a highly nonlinear-time varying system. Therefore, a lot of control theory has been applied to the system. Robot manipulator has two types of control; one is path planning, another is path tracking. In this paper, we select the path tracking, and for this purpose, propose the intelligent control¬ler which is combined with fuzzy logic and neural network. The fuzzy logic provides an inference morphorlogy that enables approximate human reasoning to apply to knowledge-based systems, and also provides a mathematical strength to capture the uncertainties associated with human cognitive processes like thinking and reasoning. Based on this fuzzy logic, the fuzzy logic controller(FLC) provides a means of converhng a linguistic control strategy based on expert knowledge into automahc control strategy. But the construction of rule-base for a nonlinear hme-varying system such as robot, becomes much more com¬plicated because of model uncertainty and parameter variations. To cope with these problems, a auto-tuning method of the fuzzy rule-base is required. In this paper, the GA-based Fuzzy-Neural control system combining Fuzzy-Neural control theory with the genetic algorithm(GA), that is known to be very effective in the optimization problem, will be proposed. The effectiveness of the proposed control system will be demonstrated by computer simulations using a two degree of freedom robot manipulator.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.187-194
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• 2010

As the design of the pillar width (PW) of the parallel tunnels in downtown area, in which are located in plains zone with deep alluvium compared with mountain tunnels, is directly related with pre-compensation payment and costs of the underground area, it has to be planned as to keep minimum distance while securing the stability of the parallel tunnels. Although PW of downtown road tunnel in Korea is standardized as 1.5D(D: diameter of the tunnels), PW sometimes has to be reduced within 1.5D to adjust the tunnel lines to the city plan in the cases of the inlet and outlet of the tunnels. In this paper, the design and the analyses of optimum PW of the NATM type road tunnel in the downtown area are introduced. The relationship among the tunnel line planning and underground compensation fee, and ground characteristics are evaluated. In the determination of PW distance, the numerical analyses of underground road tunnels were performed, including the use of the strength decrease method and strength/stress ratio method. In the cases of inlet and outlet part of the tunnels where the stability of the pillars is poor due to contiguous construction of the parallel tunnels, the reinforcement methods are recommended for securing the stability. Numerical verification was performed for the reinforcement proposed.