• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.1957-1958
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• 2013

• International Journal of Automotive Technology
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• v.6 no.1
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• pp.45-52
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• 2005

Interrupted creep tests for investigating the structural degradation during creep were conducted for a Mod.9Cr-1Mo steel in the range of stress from 71 to 167 MPa and temperature from 873 to 923 K. The change of hardness and tempered martensitic lath width was measured in grip and gauge parts of interrupted creep specimens. The lath structure was thermally stable in static conditions. However, it was not stable during creep, and the structural change was enhanced by creep strain. The relation between the change in lath width and creep strain was described quantitatively. The change in Vickers hardness was expressed by a single valued function of creep LCR(life consumption ratio). Based on the empirical relation between strain and lath width, a model was proposed to describe the relation between change in hardness and creep LCR. The comparison of the model with the empirical relation suggests that about 65% of hardness loss is due to the decrease of dislocation density accompanied by the movement of lath boundaries. The role of precipitates on subboundaries was discussed in connection with the abnormal subgrain growth appearing in low stress regime.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.1-7
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• 2007

To determine the effect of posture change on autonomic activity and to investigate valid parameters to reflex the autonomic activity from time-series pupil size data, a posture-related experiment was performed with 15 subjects, which involved measuring their electrocardiograms and pupil sizes. The experimental procedure consisted of three-sequence postures-supine, sitting and upright-for 5 minutes each, with rest sessions between postures. The subjects were notified of the entire experimental procedure. The parameters of the subjects' heart rate variability showed significant differences between the postures (heart rate: 63-70-80 beat, normalized low frequency power: 28-50-75, normalized high frequency power: 72-49-25 and ratio: 0.5-1.2-4.4 in supine-sitting-upright position respectively) as did the parameters of their mean pupil sizes (41300-53900-53700 pixels respectively) and the major frequencies (the third trend: 0.23-0.2-0.18 Hz respectively) of their pupil size variability according to changes in their autonomic activities induced by posture change. The experiment thus proved that posture change affects autonomic activity and that such activity can be estimated by the parameters of pupil size as similar as heart rate variability.

• Steel and Composite Structures
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• v.36 no.5
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• pp.521-531
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• 2020

The behavior variation of concrete dam is investigated, based on a new method for analyzing the data model of concrete dam in service process for the limitation of wavelet transform for solving concrete dam service process model. The study takes into account the time and position of behavior change during the process of concrete dam service. There is no dependence on the effect quantity for overcoming the shortcomings of the traditional identification method. The panel data model is firstly proposed for analyzing the behavior change of composite concrete dam. The change-point theory is used to identify whether the behavior of concrete dams changes during service. The phase space reconstruction technique is used to reconstruct the phase plane of the trend effect component. The time dimension method is used to solve the construction of multi-transformation model of composite panel data. An existing 76.3-m-high dam is used to investigate some key issues on the behavior change. Emphasis is placed on conversion time and location for three time periods consistent with the practical analysis report for evaluating the validity of the analysis method of the behavior variation of concrete dams presented in this paper.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.37-40
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• 2014

Article 29(3) of Occupational Safety And Health Act, which states a contractor can request a design change to an employer of businesses under the risk condition of construction of temporary structure, was established. Accordingly, in this study, recent fatal accidents caused by temporary structures were analyzed, and the level of inclusion of temporary structures in the design document were examined, and high risk temporary structures were classified. In addition, the requirements of design change of temporary structures were presented, and the qualifications of expert to certify the design change were proposed.

• Korean Journal of Remote Sensing
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• v.24 no.1
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• pp.25-33
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• 2008

To investigate the hydrologic impacts of climate changes on dam inflow for Soyanggangdam watershed $(2694.4km^2)$ of northeastern South Korea, SLURP (Semi-distributed Land Use-based Runoff Process) model and the climate change results of CCCma CGCM2 based on SRES A2 and B2 were adopted. By the CA-Markov technique, future land use changes were estimated using the three land cover maps (1985, 1990, 2000) classified by Landsat TM satellite images. NDVI values for 2050 and 2100 land uses were estimated from the relationship of NDVI-Temperature linear regression derived from the observed data (1998-2002). Before the assessment, the SLURP model was calibrated and verified using 4 years (1998-2001) dam inflow data with the Nash-Sutcliffe efficiencies of 0.61 to 0.77. In case of A2 scenario, the dam inflows of 2050 and 2100 decreased 49.7 % and 25.0 % comparing with the dam inflow of 2000, and in case of B2 scenario, the dam inflows of 2050 and 2100 decreased 45.3 % and 53.0 %, respectively. The results showed that the impact of land use change covered 2.3 % to 4.9 % for the dam inflow change.

• Journal of Construction Engineering and Project Management
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• v.5 no.2
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• pp.1-10
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• 2015

There is a high confidence based on scientific evidence that climate is changing over time. Now climate change is considered as one of the challenges facing the construction industry. As no project is risk free and climate change has a strong impact on the different phases of the construction project lifecycle. This research aimed at providing a platform of knowledge for the construction management practitioners about the impacts of climate change on the construction projects lifecycle, identify the most dangerous climate change factors on the construction project lifecycle, and identify the most affected phase by climate change factors through the construction projects lifecycle. The study depended on the opinions of civil engineers who have worked in the construction projects field among the reality of Gaza Strip. Questionnaire tool was adopted as the main research methodology in order to achieve the desired objectives. The questionnaire included 127 factors in order to obtain responses from 88 construction practitioners out of 98 representing 89.79% response rate about the influence of climate change on the generic lifecycle of construction projects. The results deduced that the most significant influence on the construction project lifecycle was related to the extreme weather events, rainfall change, and temperature change respectively. There was a general agreement between the respondents that the most affected phase by temperature, rainfall, and extreme weather events is the execution phase. The results also asserted with a high responses scale on the need to alternative procedures and clear strategies in order to face the climate change within construction industry.

• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.263-271
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• 2013

Change orders have been widespread in both the private and public construction sectors. In particular, in the case of G2B (Government to Business) contracts, adjustment of contract price and/or schedule extension is a frequent occurrence due to change orders. To uncover the causes of change orders and suggest an appropriate strategy, this study analyzed 296 cases of change orders in military facility construction projects from 2008 to 2010. The analysis revealed that the major causes of change orders are users' additional requirements (28.38%), a change of finishing materials (23.99%), and change of footing type (17.57%), in that order. Building on the results of this analysis, the authors suggest plans for practical improvements. Specific recommendations include 1) reflect user requirements at the early stage, 2) minimize the use of additional budget due to change orders, and 3) reduce the process and time for contract amendment, among others. The results of this study may provide significant implications to those involved in military construction projects, particularly project owners (i.e., the Ministry of Defense) and contractors.

• International conference on construction engineering and project management
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• 2017.10a
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• pp.281-290
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• 2017

As various stakeholders are involved in construction projects, disputes between the parties are more likely to occur, which is a very important issue for the participants in the projects. Claims in construction projects, however, are very complex and thus difficult to manage. In particular, as the cause of a claim in the preceding stage that has not been resolved in a timely manner has an effect on the cause of a claim in the following stage, it is difficult to find a point of compromise regarding a claim caused by the relationship between the causes that occur in the preceding and following stages. In this regard, this study sought to examine the rules for the generation of change order claims, which occur most frequently among the construction claims, and thus to select the key management targets through the analysis of the relationship between the causes of claims arising in the preceding and following stages for the efficient management of claims. It is expected that the use of rules for the generation of change order claims as well as of representative and similar cases will help the construction practitioners in judging claims, considering the relationships among the causes of the claims. Meanwhile, in this study, association analysis was conducted regarding the causes of the occurrence of change order claims in a design-build delivery method, and therefore, it is necessary to verify the effectiveness of the method when applied to other delivery methods.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.493-496
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• 2003

Transmittance and resistivity is investigated according to bending of ITO (indium tin oxide)film with four other multi-barrier film. Transmission data of ITO film with four ITO films showed there was about large 90% transmission above 550 nm wavelength at three multi-barrier structures. But, both -side hard coated structure showed relatively low 75% transmission above 550 nm wavelength. Also, resistivity change of four other multi-barrier film showed there was the lowest change at oneside hard coated structure. Subsequently, with result of resistivity change according to position, it was known the resistivity change of the center increased rapidly than that of the edge.