• Corrosion Science and Technology
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• v.14 no.3
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• pp.147-152
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• 2015

Corrosion of steel reinforcement is a major factor in the deterioration of harbour and bridge structure. Steel corrosion in concrete must be checked for assessing the condition of a reinforced concrete structure. There are several ways how to measure the corrosion condition of reinforced concrete, but the corrosion potential measurement is a very simple, rapid, cost-effective and non-destructive technique to evaluate the severity of corrosion in reinforced concrete structure, therefore commonly used by engineers. However some particular situations may not relate to the reinforcement corrosion probability and a simple comparison of the corrosion potential data with the ASTM C876 Standard on steel reinforcement corrosion probability could be meaningless and not give reliable informations because of environment factors as oxygen concentration, chloride content, concrete resistance. Therefore this paper explains the risk of corrosion assessment in reinforced concrete structure and how many factors can affect the reliability of the corrosion potential data.

• Journal of Navigation and Port Research
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• v.27 no.6
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• pp.611-618
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• 2003

It can be said that the relationship between the maneuvering ability of operators and the navigational environment affects the safe degree of navigation in the collision avoidance situation. In order to reduce the occurrence probability of accident and to maintain the safety, it is necessary to clarify the relationship between human behavior and navigational environment. In this study, therefore, we analyzed and discussed the relationship between the maneuvering characteristics and the safety focused on human behavior as a fundamental factor of marine accidents using ship handling simulator and questionnaire. As a result, we concluded that navigational environment changes variously and the maneuvering ability of operators also varies with the navigational environment, and the ship handling characteristics strongly affect the occurrence probability of accident.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.542-554
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• 2015

Grain size, the content of ignition loss (IL), and the concentrations of chemical oxygen demand (COD), acid volatile sulfide (AVS), and trace metals (Fe, Mn, Cu, Pb, Zn, Cd, Cr, As, and Hg) in surface sediments from the Taehwa River estuary, Ulsan, were measured to evaluate pollution levels and potential ecological risks of organic matter and trace metals in estuarine sediment. The mean grain size (Mz) of sediments in the study region ranged from $-0.8-7.7{\varphi}$ (mean $2.8{\pm}2.4{\varphi}$). Surface sediments in the upstream region of the Taehwa River were mainly composed of coarse sediments compared to the downstream region. The concentrations of IL, COD, AVS and trace metals in the sediment were much higher at downstream sites of Myeongchon Bridge in the vicinity of industrial complexes than at upstream sites of those in the vicinity of the residential areas due to the anthropogenic input of organic matter and trace metals by industrial activities. On the basis of several geochemical assessment techniques [sediment quality guidelines (SQGs), enrichment factor (EF), geoaccumulation index ($I_{geo}$), pollution load index (PLI) and ecological risk index (ERI)], the surfaces sediments in the study region are not highly polluted for trace metals, except for As. However, the higher concentrations in downstream study regions of the Taehwa River could impact benthic organisms including shellfish (i.e. Manila clam) in sediments.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.1
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• pp.125-141
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• 2020

This study examines the effect of founders' strategic orientation and social capital on the performance of startups in Korean contexts. Founders' strategic orientation is proposed as the main factor to reduce the risk of failure and to increase the potential of future growth of the startup. Three main components of strategic orientation, entrepreneurial, market, technology, were simultaneously tested with a sample of Korean startups. Furthermore, founders' social capital, networks with supporting entities and the level of chemistry within founding members were also proposed to be important factors. We also tested possible mediating effects of social capital on the main impact of strategic orientation. With a sample of 79 startups founded less than 5 years in Seoul Metropolitan Areas, we found that technology orientation of founders only significantly increases the performance of startups, but both entrepreneurial and market orientation do not. Regarding social capital effect, the external networks of the founding members are effective as proposed, and also the high cohesiveness of founding members increases the startup performance. However, the mediating role of social capital is just partially confirmed. The implications of our findings, in both sense of firm's strategy and startup policy, are discussed. This study is expected to be a bridge connecting firms' strategy with startup policy-making in Korea.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.723-730
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• 2008

Due to the higher ratio of live load to total loads of railway bridges, the accumulated damage by cyclic fatigue is significant. Moreover, it is highly possible that the initiated crack grows faster than that of highway bridges. Therefore, it is strongly needed to assess the safety for the accumulated damage analytically. The initiation and growth of fatigue-crack are related with the stress range, number of cycles, and the stiffness of the structural system. The stiffness of the structural system includes uncertainties of the planning, design, construction and maintenance, which varies as time goes. In this study, the authors developed the design and risk assessment techniques based on the reliability theories considering the uncertainties in load and resistance. For the probabilistic risk assessment of crack growth and the remaining life of the structures by the cyclic load of railway and subway bridges, response surface method (RSM) combined with first order second moment method were used. For composing limit state function, the stress range, stress intensity factor and the remaining life were selected as input important random variables to the RSM program. The probabilities of failure and the reliability indices of fatigue life for the considered specimen under cyclic loads were evaluated and discussed.

• The Journal of the Convergence on Culture Technology
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• v.8 no.1
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• pp.507-512
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• 2022

The subjects of the study are the sedimentary rock slope of the Mesozoic Gyeongsang Supergroup, which has a high risk of failure. The rocks of the slope shall be sandstone, siltstone and dacite, and discontinuities shall develop beddings, shear joints, extension joints, and dacite dyke boundary planes. The type and scale of failure varies depending on the type of rock and the strike/dip of the discontinuities, but the planar failure prevails. Based on the face-mapping data, SMR, physical and mechanical testing of rocks, the critical equilibrium analysis, all representative sections required a countermeasure method because the acceptable safety factor during dry and rainy seasons were far below Fs=1.5 and Fs=1.2. After applying the countermeasure method, both the dry and wet conditions of the slope exceeded the allowable safety factor. In particular, the face-mapping data of the slope-face, the geological cross-sections of several representative sections perpendicular to the slope-face, and the critical equilibrium analysis and the presentation of countermeasure methods that have been reviewed based on them are expected to be reasonable tools for the slope stability.