• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.1171-1176
• /
• 2005

The latest technical development of steel plate girder railway bridge are developing in ways to maximize its durability of materials in use of high strength steel and efficiency of maintenance and management by the introduction of simplified and standardization ideas. In addition to this, it is also expected to reduce the cost of bridge construction and to simplify the process of bridge manufacturing. Referring to this, composite few plate girder railway bridge is highly recommendable that is very economical with the fine exterior. In this paper, it will analyse the variation of dynamic behavior of existing composite few plate girder railway bridge with ballast caused by modified Slab Track through interpretation of limited enzyme in order to obtain the existing data for improvement of Slab Track system from Ballast Track system. Consequently, it can help maximize economic efficiency and structural capability. As a results, although the natural frequency by modified Slab Track are decreased, it is hardly influencing on the safety of railway bridges. It is also evident in the case of slab deck with a reduced scale in comparison with Ballast Track. Therefore, it is expected to reduce the cost of a railway bridge plan. And, it can expect the synergistic effect of the ensure long term durability of bridge caused by decreased stresses of bottom flange due to reduced dead load. As a result, the analytical study are carried out to investigate the composite few plate girder railway bridge could be the optimal design method for the dynamic safety of a girder section.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.29 no.5
• /
• pp.444-450
• /
• 2007

In general, labiolingual or buccolingual widths of residual alveolar bone are insufficient in edentulous area, because of alveolar resorption. Horizontal augmentation is bone graft procedure with a view to reinforcing horizontally insufficient bone quantity for installation of implants. The standard method is taking appropriate amount of block bone from intraoral or extraoral autogenous bone, and solid fixation with screws or mini-plate on labial or buccal side of residual alveolar bone. The purpose of this study is to discuss clinical usefulness of horizontal augmentation with autogenous block bone by observation and analysis of course of 41 implants installed to 12 patients by horizontal augmentation in Seoul National University Bundang Hospital from July, 2002 to December, 2005. The mean age of patients is 52.7, from 19 to 70, and the number of men and women is each 2 and 10. Block bone was taken from symphysis, body, ramus of mandible or iliac bone. And 6 types of implants were installed simultaneously or not, the diameters of implants are from 3.3 to 5.5mm, the lengths are from 8 to 15mm. The operator added artificial bone grafting material and optionally covered with membrane. The mean periods of observation after operation and final prosthetics were 28.6 and 17.0 months. As a result, 40 among 41 implants survived, the survival rate was 97.6%. Average 0.9mm crestal resorption was observed at final point of time by periapical view of each patients. Major complication related to the procedure was numbness in 7 patients.

• Journal of the Korean Dietetic Association
• /
• v.24 no.1
• /
• pp.1-18
• /
• 2018

Sustainable practices of school foodservices are gaining more attentions. The study aimed to investigate dietitians' performance levels of sustainable practices in school foodservice settings in Gyeonggi Provinces. Using a survey method was used, and data were collected from 358 participants (response rate 59.7%) to be analyzed using the SPSS program. The evaluation tool for sustainable practices of school foodservices consisted of four sections and 34 criteria with 100 points. Employment status of the respondents was as follows: nutrition teachers 40.9%, dietitians (permanent) 45.1%, and temporary position dietitians 13.2%. Dietitians' performance for sustainable practices marked 65.67 points out of 100 (performance rate 66%) and were in the following order by section: sustainable foodservice management criteria (69%), support activities (69%), planning and evaluation (68%), and outcome management (52%). Regarding sub-sections, criteria that acquired higher performance rates were labelling of food origin (99%), use of seasonal vegetables and fruits (98%), food waste management by contract dealer (98%), and planning for reducing of food waste and solid waste (91%). Meanwhile, criteria that showed the lowest scores were installing water conservation devices on equipment (19%), operating food donation programs for communities (21%), use of sensor lights for electricity conservation (24%), planning for annual energy conservation (40%), and implementation of education programs for foodservice workers on sustainable activities (42%). Performance scores differed according to school levels and working experience of dietitians, indicating that dietitians at elementary school foodservices or with work experience of 15 to 20 years showed higher performance than those at high schools or with less than 5 years of work experience (P<0.001, P<0.05). Based on the results, action plans for improvement were suggested.

• Journal of Korean Association for Spatial Structures
• /
• v.7 no.5
• /
• pp.39-48
• /
• 2007

Recently, the trend of construction has been concentrated on the development of structural systems improved economically. As a result, the usage of High Performance Steel which simplifies the girder structures and shortens the construction time is increasing. Also the interest in Longitudinally Profiled(LP) plate as a structural element for girders has been increased. The LP can distribute efficiently the sectional force applied to the structure, and also reduce the self-weight and the number of welding points. The LP plate was developed in Europe originally and its application has been increased rapidly on steel structures in Korea. Though it is used widely and internationally, the study for the LP plate application is rarely performed. In this paper, sectional stress and deflections were analyzed in the different section types by solid element in the finite element method; finally the workability, as well as economical efficiency of the LP plate produced in Korea was evaluated.

• Korean Journal of Construction Engineering and Management
• /
• v.19 no.3
• /
• pp.70-78
• /
• 2018

Due to the increasing concern about climate change, efforts to reduce environmental load are continuously being made in construction industry, and life cycle assessment (LCA) is being presented as an effective method to assess environmental load. Since LCA requires information on construction quantity used for environmental load estimation, however, it is not being utilized in the environmental review at the initial design stage where it is difficult to obtain such information. In this study, a construction quantity computation system based on the standard section was developed for the drainage facilities of the road and utilized in the model to calculate the environmental load. This model can estimate the environmental load by calculating the amount of resources required for LCA using only the information available at the initial design stage. To verify the validity of the model, five validation cases were applied and compared with the unit estimation model and the multiple regression analysis model. As a result, it is confirmed that the mean absolute error rate is 9.94%, which is relatively accurate and effective model in the initial design stage.

• Proceedings of the KOR-KST Conference
• /
• 1998.09a
• /
• pp.185-191
• /
• 1998

Metro, as a kind of city rail transit, is a modem city passenger transit system with mass transportation and independent special rails. It has become a backbone of the traffic in the metropolis and an important modern symbol of a city. A modem traffic system is indispensable for Shanghai to be an international metropolis of finance, trade and economy. At present, Shanghai metro line No. 1 and its extension have been put into operation, metro line NO. 2 will be put into trial operation by the end of 1999, the Pearl Line, an elevated rail transit system is under construction and other lines will be constructed later according to the plan. But the funding of the city rail transit construction (both metro and light rail) is a big difficult problem to the infrastructure construction of the metropolises either at home or abroad, which is also a problem to restrict the development of the city rail transit of Shanghai. We have learned from the internal and external experiences of the rail transit construction that it is an important means to deal with the funds of the city rail transit construction to actively utilize foreign funds. It makes up the shortage of the internal funds on the one hand, the external advanced science and technology and the management experiences can be introduced on the other hand. In order to discuss and study conveniently with you together the new problems appearing in the metro construction and to open up a new train of thought, this article will give out a certain analysis and description to the funding method in the metro construction of Shanghai and the characteristics of utilizing foreign funds in the rail transit construction as well as the problems which we are faced with.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.456-463
• /
• 2005

This paper describes a design process of end-milling cutters: solid model of the designed cutter is constructed along with computation of cutter geometry, and the wheel geometry as well as wheel positioning data fur fabricating end-mills with required cutter geometry is calculated. In the process, the main idea is to use the cutting simulation method by which the machined shape of an end-milling cutter is obtained via Boolean operation between a given grinding wheel and a cylindrical workpiece (raw stock). Major design parameters of a cutter such as rake angle, inner radius can be verified by interrogating the section profile of its solid model. We studied relations between various dimensional parameters and proposed an iterative approach to obtain the required geometry of a grinding wheel and the CL data fer machining an end-milling cutter satisfying the design parameters. This research has been implemented on a commercial CAD system by use of the API function programming, and is currently used by a tool maker in Korea. It can eliminate producing a physical prototype during the design stage, and it can be used fur virtual cutting test and analysis as well.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.3
• /
• pp.83-90
• /
• 2010

Composite materials can be used economically and efficiently in civil engineering applications when standards and procedure for analysis, design, construction and quality control are to be established. Bridge systems, including the girders and cross-beams, and concrete decks behave as the specially orthotropic plates. For such systems with sections, boundary conditions other than Navier solution types, it is very difficult to obtain its analytical solution. To design the bridge made by the composite materials, cross-section was used as the form-core shape for economical reason and finite difference method was used for output of the stress value. The Tsai-Wu failure criterion for stress space is used. In this paper, the rate of tensile strength reduction due to increased size was considered. And also numerical study is made for these cases.

• Polymer(Korea)
• /
• v.35 no.6
• /
• pp.610-614
• /
• 2011

In this study, the effect of solvent on the pre-irradiation grafting of VBC(vinylbenzyl chloride) onto a ETFE(polyethylene-co-tetrafluoroethylene) was evaluated. ETFE film was irradiated to generate radical species onto its backbone chain. Each irradiated film was immersed into VBC monomer mixtures diluted with various solvents such as toluene, heptane, and isopropanol etc. for grafting process and then the degree of grafting of each film was measured. FTIR analysis confirmed that the VBC-g-ETFE film was successful prepared. For the films prepared in the various solvents, the mechanical strength and the distribution pattern of the graft polymer over the cross-section of the films were measured and the effect of solvent was evaluated.

• Journal of Environmental Science International
• /
• v.28 no.10
• /
• pp.873-885
• /
• 2019

In this study, a load duration curve was applied to the Jangseongcheon, one of the tributaries of the Yeongsan River, to assess whether the target water quality was achieved. In addition, pollution of the water body was investigated to develop and suggest the optimal management time with respect to polluted flow sections and monthly conditions. The average flow rates of sections JS1 and JS2 were $0.25m^3/s$ and $1.08m^3/s$, respectively. The BOD and T-P for water-quality standards at JS1 were rated at II, whereas the COD and TOC were rated at III, thus indicating a fair level of water quality. By contrast, the BOD at JS2 was rated at III, the T-P at IV, and the TOC at V, indicating poor water quality in this section. The load duration curve was plotted using the actual flow data measured in eight-day intervals for eight years from 2011 to 2018 at locations JS1 and JS2 in the Jangsungcheon Basin. In an assessment using the load duration curve on whether the target water quality was met at location JS1, all of the water quality parameters (BOD, COD, TOC, T-N, T-P, and SS) satisfied the target water quality. By contrast, at location JS2, parameters COD, TOC, T-N, and T-P exceeded target values by more than 50%, indicating the target water quality was not met. The discharge loads of locations JS1 and JS2 were analyzed to identify the reasons the target water quality was exceeded. Results revealed that the land system contributed considerably. Furthermore, the discharge load of JS2 accounted for more than 80% of the load on the entire basin, excluding that of JS1. Therefore, the best method for restraining the inflow of pollutants into the stream near location JS2 must be applied to manage the water quality of the Jangsungcheon.