• Journal of Navigation and Port Research
• /
• v.30 no.3 s.109
• /
• pp.173-179
• /
• 2006

A number of perforated plates are utilized for the passage of the crew and the equipment, reducing weight and the arrangement of piping. Hull girders in double bottom and floor plates are the typical parts which have those plates in a ship structure, and the perforated plate is usually positioned at the place which has less loading without local strength problems. In the case of utilizing the plate inevitably at the place which has large strength, an opening of the plate has large effect on the buckling strength due to in-plane rigidity and ultimate strength. Therefore the assessments of the elastic buckling strength and the ultimate strength for the perforated plate are the essential requirements for determining the dimensions of the parts at the initial design stage. With above reason, a need of the reasonable assessments for the elastic buckling strength and the ultimate strength has evolved. The numerical series analysis with the consideration of the effect due to various aspect ratios and slenderness ratios were performed using finite element method in this research. Simple formulas for the design are also proposed from the above analysis.

• Journal of Advanced Navigation Technology
• /
• v.21 no.6
• /
• pp.537-543
• /
• 2017

Underwater glider is the long-term operating underwater robot that was developed with a purpose of continuous oceanographic observations and explorations. Torpedo-type underwater glider is not efficient from an aspect of maneuverability, because it uses a single buoyancy engine and motion controller for obtaining propulsive forces and moments. This paper introduces a ray-type underwater glider(RUG) with dual buoyancy engine, which improves the control performance of buoyancy and motion compared with torpedo-type underwater glider. Carrying out Computational Fluid Dynamics (CFD) analysis as static pitch drift test, the performance of fluid resistance for gliding motion was identified. Based on the calculated hydrodynamic coefficients, the dynamic simulation compared and analyzed the motion performance of torpedo-type and ray-type while controlling same volume of buoyancy engine. Small-sized model of RUG was developed to perform fundamental performance tests.

• Korean Journal of Construction Engineering and Management
• /
• v.18 no.6
• /
• pp.109-120
• /
• 2017

Even though domestic construction companies are expanding into overseas construction markets, the profitability of overseas project are decreasing and finally some biggest domestic construction companies recorded heavy deficit one after another in 2013. Contract management, which is very deeply related to profitability, is the most difficult area to domestic construction companies, especially in Middle East and Asia where they have the highest market share and a high level of contract management is required. The purpose of this study is to assess their contract management competences to help them improve contract management skills and strategies. First, we defined the overseas project contract management process and selected competences from the each process stage. Then, we conducted a survey with overseas project experts. For considering their competences from various angles, we divided survey groups into domestic construction groups and other groups (Contract consultancy agencies and Construction research institutes) to understand the internal and external perspective of the domestic construction companies' contract management competences. The results of survey was analyzed by using paired samples t-test, Borich Needs Assessment Model and Independent t-test. We expected that the results of this study could contributes to establish strategies for enhancing the domestic construction companies' contract management competencies.

• Korean Journal of Construction Engineering and Management
• /
• v.19 no.6
• /
• pp.124-134
• /
• 2018

Despite the many advantages of modular housing, low preference for modular housing for consumers who are familiar with RC structure leads to high construction cost of modular housing. The cost of modular buildings is about 130% of that of RC structures, so it is urgent to secure economical efficiency of modular buildings. Therefore, in this study, after calculating the savings amount of modular housing by type of construction work, economic analysis was conducted from a long - term perspective. In order to carry out the research, the authors compiled and analyzed the material cost, labor cost, and expenses incurred by each type of work by reclassifying the statement of the modular housing into the factory production and the site installation. After that, Pareto diagrams were created to find a core work that is included in the cost ratio of about 80%, and selected it as a cost reduction subject. Based on the assumption that the market size of domestic modular housing is similar to the level of modular advanced countries such as Japan and European countries, six cost reduction methods were set up that reflects the characteristics of the modular construction method and used for the expert interviews. Cost saving potentials in percentage from the interview were converted to the amount of savings that can be achieved by each type of method when applying the method. Finally, the findings of the study are expected to suggest long-term directions for technical development for modular construction and cost savings.

• Korean Journal of Construction Engineering and Management
• /
• v.19 no.6
• /
• pp.14-23
• /
• 2018

In the domestic construction industry, large-scale housing construction projects are being carried out by construction companies with competitiveness in the domestic top 10, it is said that the competence of the construction engineer is a factor for the success of the project. In Korea, there is National Competency Standards (NCS) that systematize contents of knowledge, technology, and attitude required in order to perform job in industrial field as the importance of individual ability is systemized in the country. Therefore, in this study, defined the detail competence in construction administration works, and examined the level of competence and degree of impotance detailed competency of construction engineers using AHP analysis & ANOVA. As a result, it was found that the current capacity of the Engineers in the apartment construction work is insufficient compared to the level of the competence they think they have, and that they have different competencies depending on their work experience and job position. This means that if the career is accumulated, the capacity that is possessed naturally will be changed. Therefore, it will be necessary to improve the capacity of the construction engineers who have a short work experience and a low job level.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.31-40
• /
• 2017

This paper deals with the high precision of GPS measurement reduction and its implementation on near real-time and kinematic mode for those applications requiring centimeter-level precision of the estimated coordinates, even if target stations are a few hundred kilometers away from their references. We designed the system architecture, data streaming and processing scheme. Intensive investigation was performed to determine the characteristics of the GPS medium-range functional model, IGS infrastructure and some exemplary systems. The designed system consisted of streaming and processing units; the former automatically collects GPS data through Ntrip and IGS ultra-rapid products by FTP connection, whereas the latter handles the reduction of GPS observables on static and kinematic mode to a time series of the target stations' 3D coordinates. The data streaming unit was realized by a DOS batch file, perl script and BKG's BNC program, whereas the processing unit was implemented by definition of a process control file of BPE. To assess the functionality and precision of the positional solutions, an experiment was carried out against a network comprising seven GPS stations with baselines ranging from a few hundred up to a thousand kilometers. The results confirmed that the function of the whole system properly operated as designed, with a precision better than ${\pm}1cm$ in each of the positional component with 95% confidence level.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.5
• /
• pp.481-489
• /
• 2017

The study area,Cheonan Stream, is an urban river that flows through urban areas in close proximity to densely populated areas and multi-use facilities. The natural river improvement project from 2006 to 2015 improved the quality of life of local residents with the improvement of river function, the restoration of the natural ecosystem and the securement of hydrophilic space. A bike way in the constructed waterside space was built focusing on trails. This study suggests improvements appropriate for insufficient bike way function-related regulations. The problems of ramps, river crossing facilities, stairway facilities, safety facilities, signs, road markings, and parking facilities, etc.have arisen in the utilization situation and citizen consciousness survey. As an improvement, it was suggested that 12% or fewer ramps should be improved, a submerged bridge should be installed at 7 places separated by stepping bridges, and signs and road markings according to bike way-related regulations should be installed and bike parking facilities at Cheonan station and Cheonan bus terminal should be expanded. The bike way in the waterfront of ChoenanCheon(river) will increase the accessibility and utilization rate of short-distance transportation with the institutional expansion of bike use facilities and work organizations and the improvement of facilities in accordance with urban rivers and bike-related regulations. Therefore, it is expected that the development of the living space will be beneficial for the citizens due to the elimination of traffic in the city and the activation of bike traffic.

• Journal of Korean Society of Rural Planning
• /
• v.5 no.1 s.9
• /
• pp.95-103
• /
• 1999

The purpose of this study is to find out the distribution of underground biomass and its soil stabilizing effects. Bamboo and grass were examined and compared. 1. Thirty 'soil & root' samples were collected to the depth of 30cm with Impact-corer, and then divided into three sections(0-10cm, 10-20cm, 20-30cm). Each piece had a volume of $950cm^3$ and the underground biomass was separated from the soil particles by washing with flowing water. The average underground biomass rates of bamboo and grass were 10.8% and 4% of each sample, respectively. The rate of grass root biomass declined with depth, but the bamboo root biomass was at peak at around 20cm depth. 2. The shear strength was measured with con-penetration tester at each sample collecting site. Three measurements were made at each depth(0-10cm, 10-20cm, 20-30cm) and were compared with the impact counts needed to insert the corer to the depth of 30cm. The shear strength has clear correlations with underground biomass. The more underground biomass, the higher shear strength. The shear strength of bamboo was about three times larger than the grass.

• Journal of Korean Society of Rural Planning
• /
• v.21 no.2
• /
• pp.63-77
• /
• 2015

Improve the rural views of the Government and the municipalities with the intention of rural landscape planning. However, rural scenery evaluation of landscape types and element categories, landscape scenes, such as the valuation of resources selected, form a coherent system and ecological point of view is not only a Visual perspective of evaluation, or evaluation is made. This study evaluates the rural landscape through the rural landscape for rurality is implemented can explain the image. Rural amenity 100 represented the rural landscape in rurality with photos of photos, and scenes, photos, location-based rural Vista rurality landscapes drawn components. Selected landscape photography scenic landscapes in the u.s. survey and image vocabularies through surveys is representative of the landscape in rurality of each Vista location-specific photos and images began extracted factors. As a result, the Distant view is a town and village in the rolling hills of the surrounding environment is an image behind the Vista Skyline, Farmland Rural village forests, Behind the hills, Individual housing roof, Housing arrangement, The number of household includes landscape components. Factor analysis 'openness', 'intimacy', 'activity', 'complexity', 'safety' was down to five factors, such as a description of the overall factors that force was 66.45 percent. Middle distance view is close to being out of town houses and village environment, an image in the skyline hills Vista, farmlands, village forests, rolling hills, behind the scenes of the housing component of the neck, the sperm will honor an individual factor analysis results are 'intimacy', 'safety', 'openness', 'specificity', 'complexity' five factors the whole description of the capacity factors compared to 67.24 percent. Close-range view is mainly in Vista village embraced the individual elements and an image of a harmonious location in the surroundings of the sperm, individual houses, fences, gates, courtyard, Garden, garage, agricultural facilities, including, but not limited to, factors assay but an 'intimacy', 'complexity', 'safety', 'activity', 'openness' five factors, such as a description of the overall factors that force was 65.29%. This research seeks to determine the extent to which rurality of rural landscape Vista by location attributes and elements and representative officer in photo selection and rurality to extract the image. To date, followed by a comprehensive study, which was presented through the readjustment could not overlook the Visual elements. The future rural development officer for the evaluation of rural landscape classification and quantitative and objective assessment will have to come up with ways to do.

• Korean Journal of Soil Science and Fertilizer
• /
• v.40 no.4
• /
• pp.274-279
• /
• 2007

The toxicitiy of organic sludge such as municipal sewage sludge (MSS), industrial sewage sludge (ISS), alcohol fermentation processing sludge (AFPS) and leather processing sludge (LPS) were evaluated with three environmental biomarkers as acetylcholinesterase, cytochrome P450, and heat shock protein 70 extracted from earthworm (Eisenia fetida). Their toxicities were compared with those of pig manure compost (PMC). MSS, ISS, LPS, and AFPS did not significantly affect the acetylcolinesterase activity, whereas only the elutriate of PMC slightly was increased the activity. MSS, AFPS, and PMC tended to slightly inhibit the cytochrome $P_{450}$ activity, but ISS and LPS showed significantly the inhibitory effect on cytochrome $P_{450}$. The hsp70 expression began to increase after treatments and showed high induction at 6 hour, followed by zero level at around 12 hour. The quantity of the hsp70 expressed by elutriate treatments of PMC, AFPS, MSS, ISS, and LPS was 1.9, 3.0, 3.3, 4.4, and 4.7 fold higher than that of distilled water. These results indicate that in toxicity tests of five organic waste materials, four kinds of sludge materials appeared more toxic than PMC. Results of AChE, P450, and hsp70 of earthworm might be useful for expecting or assessing an effect by exposure of organic wastes to earthworms in soil.