• Proceedings of the KWS Conference
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• 2006.05a
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• pp.181-183
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• 2006

• Steel and Composite Structures
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• v.21 no.6
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• pp.1227-1250
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• 2016

Most of the research work has been conducted on K-joints under static loading. Very limited information is available in consideration of fatigue strength of K-joints with concrete-filled chord. This paper aims to describe experimental and numerical investigations on stress concentration factors (SCFs) of concrete-filled circular chord and square braces K-joints under balanced axial loading. Experiment was conducted to study the hot spot stress distribution along the intersection of chord and braces in the two specimens with compacting concrete filled in the chord. The test results of stress distribution curves of two specimens were reported. SCFs of concrete-filled circular chord and square braces K-joints were lower than those of corresponding hollow circular chord and square brace K-joints. The corresponding finite element analysis was also conducted to simulate stress distribution along the brace and chord intersection region of joints. It was achieved that experimental and finite element analysis results had good agreement. Therefore, an extensive parametric study was carried out by using the calibrated finite element model to evaluate the effects of main geometric parameters and concrete strength on the behavior of concrete-filled circular chord and square braces K-joints under balanced axial loading. The SCFs at the hot spot locations obtained from ABAQUS were compared with those calculated by using design formula given in the CIDECT for hollow SHS-SHS K-joints. CIDECT Design Guide was generally quite conservative for predicting SCFs of braces and was dangerous for predicting SCFs of chord in concrete-filled circular chord and square braces K-joints. Finally SCF formulae were proposed for circular chord and square braces K-joints with concrete-filled in the chord under balanced axial loading. It is shown that the SCFs calculated from the proposed design equation are generally in agreement with the values derived from finite element analysis, which were proved to be reliable and accurate.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.1
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• pp.57-64
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• 2003

This study aims to discuss the characteristics on marketing distribution of landscape materials after consideration in the side of cognition on the present condition of marketing which is important factors for analysis in understanding the market of landscape materials. To do this, the investigation of marketing distribution are to collect data refer to purchases and sales reports and questionnaires, these results are used to analyzed the operative factor of forming market structure and problematic, improvement spot of marketing distribution. The periodic range of this paper is limited on 609 landscape materials and examination was performed from 21.Feb. to 15.Mar, in 2002. The results of the whole prices trends and marketing distribution survey can be summarized as follows : 1. Differences of cognition on marketing distribution among four group toward problematic spot on product and marketing of landscape materials was summarized as follows : 1) Group of landscape design : Interest of government, Various articles. 2) Group of landscape construction : Communication of marketing information, Role of intermediary ecc. 3) Group of landscape materials and cooperation between company and university : Interest of government ecc, 2. Differences of cognition on marketing distribution among four group toward improvemental spot on product and marketing of landscape materials was summarized as follows : 1) Group of landscape design and construction : Network of marketing distribution on landscape materials, Criterion of articles, Quality adiministration through establishment of sale level ecc.. 2) Group of landscape materials : Employment of specialist education program ecc.. 3) Group of cooperation between company and university : Conscious reformation of comsumer ecc.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.1
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• pp.44-53
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• 2014

A lightning strike to the aircraft seriously affects the aircraft and its components in various ways. As one of the most critical threats to the flight safety of an aircraft, fuel vapour ignition by lightning can occur through various means, notably through hot spot formation on the fuel tank skins. In this study, a coupled thermal-electrical approach using the commercial software ABAQUS is used to study the effects of a lightning strike on aircraft fuel tanks. This approach assumes that the electrical conductivity of a material depends on temperature, and that a temperature rise in a material due to Joule heat generation depends on electrical current. The inter-dependence of thermal and electrical properties-the thermal-electrical coupling-is analyzed by a coupled thermal-electrical analysis module. The analysis elucidates the effects of different material properties and thicknesses of tank skins and identifies the worst case of lightning zones.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.440-445
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• 2007

This paper deals with assessment of risk component for electrical safety and investigation on the spot of computer room in elementary middle high school. The investigation was carried out side by side for floor, outlet, panel board, earth leakage circuit breaker at computer room In order to assess electrical safety at computer room, grounding simulator and power quality monitor have been used. Potential rise has been measured and analyzed for ground rod and grounding grid by using the simulator. Phase and neutral-line current have been monitored in real time. As a consequence, it is desirable for us to install conductive tile at floor of computer room Grounding grid had better than ground rod for electrical safety. Neutral-line current was produced by unbalanced phase current.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.699-705
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• 2007

Recent experimental data shows that the noticeable feature of irregular roughened spots on the fuel surface occurs during the combustion test with PMMA/GOX in the hybrid rocket motor. The generation of these unexpected patterns is likely to be resulted from the disturbed boundary layer due caused by wall blowing which is intented to simulate the process of fuel vaporization. LES technique was implemented to investigate both the flow characteristics near fuel surface and the subsequent evolution of turbulence modified by the wall blowing. Simple channel geometry instead of circular grain configuration was used for the investigation without chemical reactions in order to allow for a focused examination on the near-wall behavior at the Reynolds number of 22,500. It was shown that the wall blowing pushed turbulent structures upwards making them tilted and this skewed displacement, in effect, left the foot prints of the structures on the surface. This change of kinematics may explain the formation of irregular isolated spots on the fuel surface observed in the experiment.

• Steel and Composite Structures
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• v.24 no.4
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• pp.455-465
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• 2017

This paper presents a series of ultimate and fatigue experimental investigation on concrete-filled rectangular hollow section (CRHS) X joints with Perfobond Leister rib (PBR) under tension. A total of 15 specimens were fabricated, in which 12 specimens were tested under ultimate tension and 3 specimens were investigated in fatigue test. Different parameters including PBR stiffening, brace-to-chord ratio (${\beta}$) and inclined angle (${\theta}$) were considered in the test. Each joint was tested to failure under tension load. Obtained from test result, PBR was found to improve the tension strength and fatigue durability of CRHS joint substantially. Concrete dowel consisted by PBR and concrete inside the chord stiffened the joint, which leaded to a combination failure mode of punching shear and chord plastification of CRHS joint under tension. Finite element analysis validated the compound failure mode. Stress concentration on typical spot of CRHS joint was mitigated by PBR which was observed from fatigue test. Initial fatigue crack presented in CRHS joint with PBR also differentiated with the counterpart without PBR.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.493-498
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• 2003

In case of slope failure by planted protection is constructed on the slope according to of the choice trend of a recently environmental-friendly countermeasure, there has a limitation about diagnosis and preparation of measure. Also, collapse of tunnel pithead department slope has maximum in construction and countermeasure method of construction choice unlike cut-slope. In this study, analyzed inside circumstance of slope using geophysical exploration for stability analysis and countermeasure inside presentation of tunnel pithead department slope which collapse happens. geophysical exploration used dipole(Dipole-Dipole) method that is based to distribution principle does specific resistance, goes side by side with on-the-spot observation and draws base strength parameter and executed stability analysis, and presented stabilization countermeasure inside of collapse slope on this. I wish to conduce in development and research for use technical development of geophysical exploration technique hereafter by executing geophysical exploration in road collapse spot applying through this study.

• Korean Journal of Veterinary Research
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• v.49 no.4
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• pp.309-317
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• 2009

The present study describes an investigation on an epidemic of Tuberculosis (TB) which has been occurred among dairy cattle farms in Jeongeup, Jeollabuk-do since 2007. The investigation was performed in three ways as follows: 1. Collecting information about bovine TB outbreaks using investigation reports, an on-the-spot and tracing-back investigations; 2. Analyzing the outbreak pattern; 3. Establishing hypothesis and performing statistical analysis on potential risk factors. In the early 2000s, TB outbreaks were sporadically reported in beef cattle, and only a small number ($1{\sim}2$) of reactors was confirmed in each of outbreak farms. The number of TB outbreaks has been suddenly increased from 2007, mainly in dairy cattle farms. And these outbreaks were temporarily clustered during the period, from March 2007 to April 2009 (relative risk, RR = 13.7, p < 0.001). And two spatial clusters of which radiuses were 0.3 km (RR = 6.9, p < 0.001) and 0.9 km (RR = 3.6, p < 0.01). The analysis to find risk factors was performed on 99 dairy farms (21 outbreaks), which are located in the most seriously affected village during 2007-2009. Middleman (odds ratio, OR = 47.4, p < 0.05) and raw milk collecting system (OR = 6.9, p < 0.05) were recognized as with the highest association. Considering the fact that all the outbreak farms except one had their own manure composting tank, it might be that the manure containing pathogen was leaked from tank and transmitted to other farms by fomites such as middleman or raw milk collecting system.

• Journal of Korean Society of Rural Planning
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• v.13 no.1 s.34
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• pp.73-84
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• 2007

The first theme of this study is to preserve and manage rural multi-functionality resource Information. This study is to suggest the method that can irradiate rural multi-functionality resource Information efficiently and constructively. GIS uses PDA and Tablet PC as an investigation tool and verifies the outcome of the development in the investigation system. This study enhanced the mobility function of PDA by installing recording system and camera to the PDA. Also, Using GPS has been ensured scientific precision and realism to the investigation. Direct input on spot can save time, cost and minimize human error by simplifying the investigation process. Database is composed of characters like scale, form, location, distance, resident's opinion and image of 37 resources. The survey system was applied in 170 villages and got a total of 12,270 resources data. Management system should be easy to input and output the surveyed information and to get reports in any kind of form ( i.e. final result can be produced as a map). By utilizing of the Rural Resource information system, the study made a simulation to compare the target areas before and after. Also, digitalized investigation system, minimized re-input and reprocessing of data and enabled to simplify and standardize the process than memorandum investigation. Data collected through digital system could offer people useful information by Web-GIS. It was need to specify practical way in decision-making and a way to measure the value of resources to align with the regional plan. Also, need to keep on developing statistical data and application program that can connect us to present the best solution to support regional planning. Therefore, quality of data is very important. Finally, it is very important to develop various programs to analyze space md rural resource by monitoring rural environment.