• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.250-256
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• 2013

Using shear wave velocity is more reasonable to estimate strength and integrity of rock compared with using compressional wave. It is often ambiguous to pick the dominant frequency caused by torsional wave when evaluating $V_S$ of rock specimen from FFRC method. It is also sometimes ambiguous to pick the first arrival point of S wave compared with P wave in the signals acquired from ultrasonic velocity method. Otherwise, the procedure of evaluating $V_P$ using ultrasonic velocity method and $V_L$ using FFRC method is relatively stable. Through the relationship between elastic modulus, poisson's ratio and $V_S$ can be obtained from $V_P$, $V_L$. Applicability was checked using model specimens having different material property and length and rock specimens sampled in mine area, and usefulness of proposed procedure was verified.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1125-1138
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• 2014

In this study, we applied an advanced non-parametric low-flow frequency analysis using boundary kernel by Representative Concentration Pathways (RCPs) climate change scenarios through Arc-SWAT long-term runoff model simulation at the Gwangdong storage reservoir located in Taeback, Gangwondo. The results show that drought frequency under RCPs was expected to increase due to reduced runoff during the near future, and the variation of low-flow time series was appeared greatly under RCP8.5 scenario, respectively. The result from drought frequency of Median flow in the near future (2030s) compared historic period, the case of 30-year low-flow frequency was increased (the RCP4.5 shows +22.4% and the RCP8.5 shows +40.4%), but in the distant future (2080s) expected increase of drought frequency due to the reduction of low-flow (under RCP4.5: -4.7% and RCP8.5: -52.9%), respectively. In case of Quantile 25% flow time series data also expected that the severe drought frequency will be increased in the distant future by reducing low-flow (the RCP4.5 shows -20.8% to -60.0% and the RCP8.5 shows -30.4% to -96.0%). This non-parametric low-flow frequency analysis results according to the RCPs scenarios have expected to consider to take advantage of as a basis data for water resources management and countermeasures of climate change in the mid-watershed over the Korean Peninsula.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.407-414
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• 2017

With an increase in urban crimes in various forms, this study is intended to analyze the effectiveness of the service design that presented a new model resolving crime risks through differentiated thinking paradigm and problem approaches. The empirical case addressed in this study is 'the project to create resident-driven safe community in Duryu-dong, Dalseo-gu, Deagu though service design'. This project is evaluated as having prepared a prevention-oriented local safety system through a preemptive and resident-centered process. The project was promoted as a 'natural monitoring capacity building program' for residents to prevent local crimes, a 'social role expansion program' for local safety, and 'crime prevention environment design', which provides comprehensive solutions for residents' safety. Here, designers act as exerts in designing a task-based platform that can be driven by residents rather than a visual environment improver, and reorganizing the local ecosystem by expanding the opportunities for residents to interact. This case identifies the role of service design as binding the solidarity of local residents beyond the improvement of the crime environment and giving them the potential capacity to maintain a safe living space in relation to a safety issues of community.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.9-20
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• 1999

A method is proposed to estimate the joint damages of a steel structure from modal data using the neural networks technique. The beam-to-column connection in a steel frame structure is represented by a zero-length rotational spring of the end of the beam element, and the connection fixity factor is defined based on the rotational stiffness so that the factor may be in the range 0~1.0. Then, the severity of joint damage is defined as the reduction ratio of the connection fixity factor. Several advanced techniques are employed to develop the robust damage identification technique using neural networks. The concept of the substructural indentification is used for the localized damage assessment in the large structure. The noise-injection learning algorithm is used to reduce the effects of the noise in the modal data. The data perturbation scheme is also employed to assess the confidence in the estimated damages based on a few sets of actual measurement data. The feasibility of the proposed method is examined through a numerical simulation study on a 2-bay 10-story structure and an experimental study on a 2-story structure. It has been found that the joint damages can be reasonably estimated even for the case where the measured modal vectors are limited to a localized substructure and the data are severely corrupted with noise.

• International Journal of High-Rise Buildings
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• v.1 no.1
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• pp.37-51
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• 2012

New generation of tall and complex buildings systems are now introduced that are reflective of the latest development in materials, design, sustainability, construction, and IT technologies. While the complexity in design is being overcome by the availability and advances in structural analysis tools and readily advanced software, the design of these buildings are still reliant on minimum code requirements that yet to be validated in full scale. The involvement of the author in the design and construction planning of Burj Khalifa since its inception until its completion prompted the author to conceptually develop an extensive survey and real-time structural health monitoring program to validate all the fundamental assumptions mad for the design and construction planning of the tower. The Burj Khalifa Project is the tallest structure ever built by man; the tower is 828 meters tall and comprises of 162 floors above grade and 3 basement levels. Early integration of aerodynamic shaping and wind engineering played a major role in the architectural massing and design of this multi-use tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria established at the onset of the project design. Understanding the structural and foundation system behaviors of the tower are the key fundamental drivers for the development and execution of a state-of-the-art survey and structural health monitoring (SHM) programs. Therefore, the focus of this paper is to discuss the execution of the survey and real-time structural health monitoring programs to confirm the structural behavioral response of the tower during construction stage and during its service life; the monitoring programs included 1) monitoring the tower's foundation system, 2) monitoring the foundation settlement, 3) measuring the strains of the tower vertical elements, 4) measuring the wall and column vertical shortening due to elastic, shrinkage and creep effects, 5) measuring the lateral displacement of the tower under its own gravity loads (including asymmetrical effects) resulting from immediate elastic and long term creep effects, 6) measuring the building lateral movements and dynamic characteristic in real time during construction, 7) measuring the building displacements, accelerations, dynamic characteristics, and structural behavior in real time under building permanent conditions, 8) and monitoring the Pinnacle dynamic behavior and fatigue characteristics. This extensive SHM program has resulted in extensive insight into the structural response of the tower, allowed control the construction process, allowed for the evaluation of the structural response in effective and immediate manner and it allowed for immediate correlation between the measured and the predicted behavior. The survey and SHM programs developed for Burj Khalifa will with no doubt pioneer the use of new survey techniques and the execution of new SHM program concepts as part of the fundamental design of building structures. Moreover, this survey and SHM programs will be benchmarked as a model for the development of future generation of SHM programs for all critical and essential facilities, however, but with much improved devices and technologies, which are now being considered by the author for another tall and complex building development, that is presently under construction.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.79-91
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• 2016

Geosynthetic-reinforced and Pile-supported (GRPS) embankment method is widely used to construct structures on soft ground due to restraining residual settlement and their rapid construction. However, effect of cyclic loading has not been established although some countries suggest design methods through many studies. In this paper, cyclic loading tests were conducted to analyze dynamic load transfer characteristics of pile-supported embankment reinforced with geosynthetics. A series of 3 case full scale model tests which were non-reinforced, one-layer-reinforced, two-layer reinforced with geosynthetics were performed on piled embankments. In these series of tests, the height of embankment and pile spacing were selected according to EBGEO (2010) standard in Germany. As a result of the vertical load parts on the pile and on the geosynthetic reinforcement measured separately, cyclic loads transferred by only arching effect decreased with strength geosynthetic-reinforced case. However, final loads on the pile showed no differences among the cases. These results conflict with previous studies that reinforcement with geosynthetics increases transfer load concentrated on piles. In addition, it is observed that the load transferred to pile decreases at the beginning of cycle number due to reduction of arching effected by cyclic loading. Based on these results, transferred mechanism for cyclic load on GRPS system has been presented.

• Journal of Gastric Cancer
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• v.4 no.3
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• pp.137-142
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• 2004

Purpose: There have been some controversies over the therapeutic principles of advanced gastric cancer, and the results of treatment have been variable, especially for stage III disease. This study was conducted to define the prognostic factors of stage III gastric cancer. Materials and Methods: This retrospective study was based on the medical records of 179 patients with stage III disease who received a gastrectomy from January 1990 to December 1994. The 5-year survival rate was analyzed according to the age, sex, tumor location, tumor size, Borrmann's type, depth of invasion, lymph-node metastasis, ratio of metastatic lymph nodes, type of surgical resection, extent of lymphnode dissection, curability of resection, postoperative chemotherapy, and pathological stage. The statistical analysis was done by using the Kaplan-Meier method, the log-rank test, and the Cox proportional hazards model. Results: The overall 5-year survival rate was $61.6\%$ the 5-year survival rates according to subgroup were $69.7\%$ for stage IIIa ($100\%$ for $T_{2}N_{2}$, $70.0\%$ for $T_{3}N_{1}$, $68.6\%$ for $T_{4}N_{0}$), and $54.1\%$ for stage IIIb ($T_{3}N_{2}$) (P<0.05). Among various clinicopathologic factors of stage III gastric cancer, the age of the patient, the tumor location, the gross type of tumor, the type of gastric resection, the extent of lymph-node dissection, the curability of resection, and the subgroups of stage III were statistically significant in the univariate survival analysis. The multivariate analysis defined the curability of resection, the extent of lymph-node dissection, the type of operation, the stage of disease, and the age of the patient as independent prognostic factors. Conclusion: A curative surgical resection and an extended lymph-node dissection are thought to be most important for improving the survival rate in stage III gastric cancer patients.

• The Journal of Advanced Prosthodontics
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• v.1 no.3
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• pp.113-117
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• 2009

STATEMENT OF PROBLEM. Recently Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) has been introduced due to superior flexural strength and fracture toughness compared to other dental ceramic systems. Although zirconia has outstanding mechanical properties, the phenomenon of decrease in the life-time of zirconia resulted from degradation in flexural strength after low temperature aging has been reported. PURPOSE. The objective of this study was to investigate degradation of flexural strength of Y-TZP ceramics after various low temperature aging treatments and to evaluate the phase stability and micro-structural change after aging by using X-ray diffraction analysis and a scanning electron microscope (SEM). MATERIAL AND METHODS. Y-TZP blocks of Vita In-Ceram YZ (Vita Zahnfabrik, Bad $S\ddot{a}ckingen$, Germany) were prepared in 40 mm (length) $\times$ 4 mm (width) $\times$ 3 mm (height) samples. Specimens were artificially aged in distilled water by heat-treatment at a temperature of 75, 100, 125, 150, 175, 200, and $225^{\circ}C$ for 10 hours, in order to induce the phase transformation at the surface. To measure the mechanical property, the specimens were subjected to a four-point bending test using a universal testing machine (Instron model 3365; Instron, Canton, Mass, USA). In addition, X-ray diffraction analysis (DMAX 2500; Rigaku, Tokyo, Japan) and SEM (Hitachi s4700; Jeol Ltd, Tokyo, Japan) were performed to estimate the phase transformation. The statistical analysis was done using SAS 9.1.3 (SAS institute, USA). The flexural strength data of the experimental groups were analyzed by one-way analysis of variance and to detect statistically significant differences ($\alpha$= .05). RESULTS. The mean flexural strength of sintered Vita In-Ceram YZ without autoclaving was 798 MPa. When applied aging temperature at below $125^{\circ}C$ for 10 hours, the flexural strength of Vita In-Ceram YZ increased up to 1,161 MPa. However, at above $150^{\circ}C$, the flexural strength started to decrease. Although low temperature aging caused the tetragonal-to-monoclinic phase transformation related to temperature, the minimum flexural strength was above 700 MPa. CONCLUSION. The monoclinic phase started to appear after aging treatment above $100^{\circ}C$. With the higher aging temperature, the fraction of monoclinic phase increased. The ratio of monoclinic/tetragonal + monoclinic phase reached a plateau value, circa 75% above $175^{\circ}C$. The point of monoclinic concentration at which the flexural strength begins to decrease was between 12% and 54%.

• Journal of the Economic Geographical Society of Korea
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• v.18 no.1
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• pp.115-135
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• 2015

In the glocalization a common phenomenon of several nations reveals knowledge innovation and growth by the important subject of region and state and is studied at theory and practice. the successful cases of regional development in an advanced country have leading innovation through regional innovation system and cluster. therefore we are necessary to analyse how the knowledge spillovers in innovative cluster as the reduced model of regional innovation system guide firm innovation and region growth. this article reviews theories and empirical studies of the knowledge spillovers in the regional innovation system and innovative cluster of innovative geography and proposes a new research issues for further explorations of the knowledge spillovers. Previous studies assist that knowledge spillovers exist in knowledge-based industries of specific local area and local innovation accomplishes through pure knowledge spillover. but limits of these studies include narrow region and technological area, few analytical variable and exclusion of rent knowledge spillover. therefore new research topics related with that exemplifies geographical dimension(concentration and decentralization), technological dimension(knowledge based industry), category of analytic variables(previous indicators, time, and social capital), conceptualization(appropriation means, markets for technology) etc.

• International Commerce and Information Review
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• v.13 no.2
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• pp.235-258
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• 2011

Our country is operating designating the 6 free economic zones. Korea has designated fixed areas as economic special zones and made their management and living conditions equivalent to the level of advanced countries they are to support. One-Stop Service for the administrative demands that require the assistance at a national level in foreign investment, education, finance etc. However, these free economic zones are modified by regional development projects rather than inviting foreign capital. For the free economic zones to be operated effectively, the following methods should be followed: first, active management support activities should be constructed for the purpose of attracting foreign capital, second, a business model specifically designed to attract foreign capital should be implemented, third and finally, the independence and professionalism for the free economic zones should be strengthened.