• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.4
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• pp.105-117
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• 2010

The topographical depressions in urban areas, the lack in drainage capability, sewage backward flow, road drainage, etc. cause internal inundation, and the increase in rainfall resulting from recent climate change, the rapid urbanization accompanied by economic development and population growth, and the increase in an impervious area in urban areas deteriorate the risk of internal inundation in the urban areas. In this study, the vulnerability of internal inundation in urban areas is analyzed and SWMM model is applied into Oncheoncheon watershed, which represents urban river of Busan, as a target basin. Based on the results, the representative storm sewers in individual sub-catchments is selected and the risk of vulnerability to internal inundation due to rainfall in urban streams is analyzed. In order to analyze the risk and vulnerability of internal inundation, capacity is applied as an index indicating the volume of a storm sewer in the SWMM model, and the risk of internal inundation is into 4 steps. For the analysis on the risk of internal inundation, simulation results by using a SMMM model are compared with the actual inundation areas resulting from localized heavy rain on July 7, 2009 at Busan and comparison results are analyzed to prove the validity of the designed model. Accordingly, probabilistic rainfall at Busan was input to the model for each frequency (10, 20, 50, 100 years) and duration (6, 12, 18, 24hr) at Busan. In this study, it suggests that the findings can be used to preliminarily alarm the possibility of internal inundation and selecting the vulnerable zones in urban areas.

• Economic and Environmental Geology
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• v.50 no.5
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• pp.363-373
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• 2017

In the present study, adaptability of cyber-physical system (CPS) for risk management of $CO_2$ storage site is examined and the subagging regression (SBR) method is proposed as a key component of the cyber-twin to estimate the risk due to potential $CO_2$ leakage. For these purposes, $CO_2$ concentration data monitored from a controlled $CO_2$ release field experiment is employed to validate the potentialities of the SBR method. From the validation study, it is found that the SBR method has robust estimation capability by showing minimal influence from anomalous measurements, and makes stable and sound predictions for the forthcoming $CO_2$ concentration trend. In addition, the method is found to be well suited as a tool of operational risk assessment based on real-time monitoring data due to the computational efficiency. The overall results suggest that the SBR method has potential to be an important component comprising the cyber twin of CPS for risk management of $CO_2$ storage site.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.72-77
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• 2010

The Incheon Bridge, which was opened to the traffic in October 2009, is an 18.4 km long sea-crossing bridge connecting the Incheon International Airport with the expressway networks around the Seoul metropolitan area by way of Songdo District of Incheon City. This bridge is an integration of several special featured bridges and the major part of the bridge consists of cable-stayed spans. This marine cable-stayed bridge has a main span of 800 m wide to cross the vessel navigation channel in and out of the Incheon Port. In waterways where ship collision is anticipated, bridges shall be designed to resist ship impact forces, and/or, adequately protected by ship impact protection (SIP) systems. For the Incheon Bridge, large diameter circular dolphins as SIP were made at 44 locations of the both side of the main span around the piers of the cable-stayed bridge span. This world's largest dolphin-type SIP system protects the bridge against the collision with 100,000 DWT tanker navigating the channel with speed of 10 knots. Diameter of the dolphin is up to 25 m. Vessel collision risk was assessed by probability based analysis with AASHTO Method-II. The annual frequency of bridge collapse through the risk analysis for 71,370 cases of the impact scenario was less than $0.5{\times}10^{-4}$ and satisfies design requirements. The dolphin is the circular sheet pile structure filled with crushed rock and closed at the top with a robust concrete cap. The structural design was performed with numerical analyses of which constitutional model was verified by the physical model experiment using the geo-centrifugal testing equipment. 3D non-linear finite element models were used to analyze the structural response and energy-dissipating capability of dolphins which were deeply embedded in the seabed. The dolphin structure secures external stability and internal stability for ordinary loads such as wave and current pressure. Considering failure mechanism, stability assessment was performed for the strength limit state and service limit state of the dolphins. The friction angle of the crushed stone as a filling material was reduced to $38^{\circ}$ considering the possibility of contracting behavior as the impact.

• Structural Engineering and Mechanics
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• v.50 no.5
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• pp.589-603
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• 2014

Expressions for determining the value of the impact force as reported in the literature and incorporated into code provisions are essentially quasi-static forces for emulating deflection. Quasi-static forces are not to be confused with contact force which is generated in the vicinity of the point of contact between the impactor and target, and contact force is responsible for damage featuring perforation and denting. The distinction between the two types of forces in the context of impact actions is not widely understood and few guidelines have been developed for their estimation. The value of the contact force can be many times higher than that of the quasi-static force and lasts for a matter of a few milli-seconds whereas the deflection of the target can evolve over a much longer time span. The stiffer the impactor the shorter the period of time to deliver the impulsive action onto the target and consequently the higher the peak value of the contact force. This phenomenon is not taken into account by any contemporary codified method of modelling impact actions which are mostly based on the considerations of momentum and energy principles. Computer software such as LS-DYNA has the capability of predicting contact force but the dynamic stiffness parameters of the impactor material which is required for input into the program has not been documented for debris materials. The alternative, direct, approach for an accurate evaluation of the damage potential of an impact scenario is by physical experimentation. However, it can be difficult to extrapolate observations from laboratory testings to behaviour in real scenarios when the underlying principles have not been established. Contact force is also difficult to measure. Thus, the amount of useful information that can be retrieved from isolated impact experiments to guide design and to quantify risk is very limited. In this paper, practical methods for estimating the amount of contact force that can be generated by the impact of a fallen debris object are introduced along with the governing principles. An experimental-calibration procedure forming part of the assessment procedure has also been verified.

• Journal of Convergence for Information Technology
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• v.9 no.8
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• pp.140-147
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• 2019

The purpose of this study is to find biomechanical parameters for optimal shoes production through an ergonomic usability assessment of five existing types of shoes preferred by B-BOY. Ten experts and ten non-experts participated in the experiment, and 12 infrared cameras (Qualis, Oqus), force plate (Kistler, 9286AA) and foot pressure plate (Zebris Gmbh, Zebris PDM-System) were used to obtain the data. The results of the study are as follows. First, P shoes with a friction coefficient of 0.38 and a free moment of 0.32 N/m/kg are desirable in terms of traction capability and safety. Second, on the cushion, it was found that the N shoes 2.51 N, sec/kg and non-expert, and 2.86 N and sec/kg were suitable. Third, it is deemed appropriate for C shoes with a forefoot average pressure of 10.11 KPa (right), 10.05 KPa (left), and V shoes with a rearfoot average pressure of 8.4 KPa (right) and 8.36 KPa (left). In conclusion, the combination of the structure and material of V shoes should be developed for traction and stability, N shoes for cushion, and walking balance for C and V shoes.

• Journal of Space Technology and Applications
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• v.3 no.3
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• pp.199-212
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• 2023

In contrast to the short-term nature of lunar missions in the past, lunar missions in new space era aim to extend the presence on the lunar surface and to use this capability for the Mars exploration. In order to realize extended human presence on the Moon, production and use of consumables and fuels required for the habitation and transportation using in-situ resources is an important prerequisite. The Global Exploration Roadmap presented by the International Space Exploration Coordination Group (ISECG), which reflects the space exploration plans of participating countries, shows the phases of progress from lunar surface exploration to Mars exploration and relates in-situ resource utilization (ISRU) capabilities to each phase. Based on the ISRU Gap Assessment Report from the ISECG, ISRU technology is categorized into in-situ propellant and consumable production, in-situ construction, in-space manufacturing, and related areas such as storage and utilization of products, power systems required for resource utilization. Among the lunar resources, leading countries have prioritized the utilization of ice water existing in the permanent shadow region near the lunar poles and the extraction of oxygen from the regolith, and are preparing to investigate the distribution of resources and ice water near the lunar south pole through unmanned landing missions. Resource utilization technologies such as producing hydrogen and oxygen from water by hydroelectrolysis and extracting oxygen from the lunar regolith are being developed and tested in relevant lunar surface analogue environments. It is also observed that each government emphasizes the use and development of the private sector capabilities for sustainable lunar surface exploration by purchasing lunar landing services and providing opportunities to participate in resource exploration and material extraction.

• Asia pacific journal of information systems
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• v.22 no.4
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• pp.7-29
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• 2012

Smartphone and its applications (i.e. apps) are increasingly penetrating consumer markets. According to a recent report from Korea Communications Commission, nearly 50% of mobile subscribers in South Korea are smartphone users that accounts for over 25 million people. In particular, the importance of smartphone has risen as a geospatially-aware device that provides various location-based services (LBS) equipped with GPS capability. The popular LBS include map and navigation, traffic and transportation updates, shopping and coupon services, and location-sensitive social network services. Overall, the emerging location-based smartphone apps (LBA) offer significant value by providing greater connectivity, personalization, and information and entertainment in a location-specific context. Conversely, the rapid growth of LBA and their benefits have been accompanied by concerns over the collection and dissemination of individual users' personal information through ongoing tracking of their location, identity, preferences, and social behaviors. The majority of LBA users tend to agree and consent to the LBA provider's terms and privacy policy on use of location data to get the immediate services. This tendency further increases the potential risks of unprotected exposure of personal information and serious invasion and breaches of individual privacy. To address the complex issues surrounding LBA particularly from the user's behavioral perspective, this study applied the privacy calculus model (PCM) to explore the factors that influence the adoption of LBA. According to PCM, consumers are engaged in a dynamic adjustment process in which privacy risks are weighted against benefits of information disclosure. Consistent with the principal notion of PCM, we investigated how individual users make a risk-benefit assessment under which personalized service and locatability act as benefit-side factors and information privacy risks act as a risk-side factor accompanying LBA adoption. In addition, we consider the moderating role of trust on the service providers in the prohibiting effects of privacy risks on user intention to adopt LBA. Further we include perceived ease of use and usefulness as additional constructs to examine whether the technology acceptance model (TAM) can be applied in the context of LBA adoption. The research model with ten (10) hypotheses was tested using data gathered from 98 respondents through a quasi-experimental survey method. During the survey, each participant was asked to navigate the website where the experimental simulation of a LBA allows the participant to purchase time-and-location sensitive discounted tickets for nearby stores. Structural equations modeling using partial least square validated the instrument and the proposed model. The results showed that six (6) out of ten (10) hypotheses were supported. On the subject of the core PCM, H2 (locatability ${\rightarrow}$ intention to use LBA) and H3 (privacy risks ${\rightarrow}$ intention to use LBA) were supported, while H1 (personalization ${\rightarrow}$ intention to use LBA) was not supported. Further, we could not any interaction effects (personalization X privacy risks, H4 & locatability X privacy risks, H5) on the intention to use LBA. In terms of privacy risks and trust, as mentioned above we found the significant negative influence from privacy risks on intention to use (H3), but positive influence from trust, which supported H6 (trust ${\rightarrow}$ intention to use LBA). The moderating effect of trust on the negative relationship between privacy risks and intention to use LBA was tested and confirmed by supporting H7 (privacy risks X trust ${\rightarrow}$ intention to use LBA). The two hypotheses regarding to the TAM, including H8 (perceived ease of use ${\rightarrow}$ perceived usefulness) and H9 (perceived ease of use ${\rightarrow}$ intention to use LBA) were supported; however, H10 (perceived effectiveness ${\rightarrow}$ intention to use LBA) was not supported. Results of this study offer the following key findings and implications. First the application of PCM was found to be a good analysis framework in the context of LBA adoption. Many of the hypotheses in the model were confirmed and the high value of $R^2$ (i.,e., 51%) indicated a good fit of the model. In particular, locatability and privacy risks are found to be the appropriate PCM-based antecedent variables. Second, the existence of moderating effect of trust on service provider suggests that the same marginal change in the level of privacy risks may differentially influence the intention to use LBA. That is, while the privacy risks increasingly become important social issues and will negatively influence the intention to use LBA, it is critical for LBA providers to build consumer trust and confidence to successfully mitigate this negative impact. Lastly, we could not find sufficient evidence that the intention to use LBA is influenced by perceived usefulness, which has been very well supported in most previous TAM research. This may suggest that more future research should examine the validity of applying TAM and further extend or modify it in the context of LBA or other similar smartphone apps.

• The Korean Journal of Nuclear Medicine
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• v.38 no.1
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• pp.30-40
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• 2004

Purpose: The aims of this study were to find brain regions in which gray matter volume was reduced and to show the capability of voxel-based morphometry (VBM) analysis for lateralizing epileptogenic zones in medial temporal lobe epilepsy (mTLE). The findings were compared with fluorodeoxyglucose positron omission tomography (FDG PET). Materials and Methods: MR T1-weighted images of 12 left mTLE and 11 right mTLE patients were compared with those of 37 normal controls. Images were transformed to standard MNI space and averaged in order to create study-specific brain template. Each image was normalized to this local template and brain tissues were segmented. Modulation VBM analysis was performed in order to observe gray matter volume change. Gray matter was smoothed with a Gaussian kernel. After these preprocessing, statistical analysis was peformed using statistical parametric mapping software (SPM99). FDG PET images were compared with those of 22 normal controls using SPM. Results: Gray matter volume was significantly reduced in the left amygdala and hippocampus in left mTLE. In addition, volume of cerebellum, anterior cingulate, and fusiform gyrus in both sides and left insula was reduced. In right mTLE, volume was reduced significantly in right hippocampus. In contrast, FDG uptake was decreased in broad areas of left or right temporal lobes in left TLE and right TLE, respectively. Conclusions: Gray matter loss was found in the ipsilateral hippocampus by modulation VBM analysis in medial temporal lobe epilepsy. This VBM analysis might be useful in lateralizing the epileptogenic zones in medial temporal lobe epilepsy, while SPM analysis of FDG PET disclosed hypometabolic epileptogenic zones.

• KDI Journal of Economic Policy
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• v.13 no.2
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• pp.97-127
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• 1991

This paper investigates the roles and the limitations of the Korean antitrust agencies-the Office of Fair Trade (OFT) and the Fair Trade Commission (FTC) during the making of the major industrial policies of the 1980's. The Korean antitrust agencies played only a minimal role in three major industrial policy-making issues in the 1980's- the enactment of the Industrial Development Act (IDA), the Industrial Rationalization Measures according to the IDA, and the Industrial Readjustment Measures on Consolidation of Large Insolvent Enterprises based on the revised Tax Exemption and Reduction Control Act. As causes for this performance bias in the Korean antitrust system, this paper considers five factors according to the current literature on implementation failure: ambiguous and insufficient statutory provisions of the Monopoly Regulation and Fair Trade Act (MRFTA); lack of resources; biased attitudes and motivations of the staff of the OFT and the FTC; bureaucratic incapability; and widespread misunderstanding about the roles and functions of the antitrust system in Korea. Among these five factors, bureaucratic incompetence and lack of understanding in various policy implementation environments about the roles and functions of the antitrust system have been regarded as the most important ones. Most staff members did not have enough educational training during their school years to engage in antitrust and fair trade policy-making. Furthermore, the high rate of staff turnover due to a mandatory personnel transfer system has prohibited the accumulation of knowledge and skills required for pursuing complicated structural antitrust enforcement. The limited capability of the OFT has put the agency in a disadvantaged position in negotiating with other economic ministries. The OFT has not provided plausible counter-arguments based on sound economic theories against other economic ministries' intensive market interventions in the name of rationalization and readjustment of industries. If the staff members of antitrust agencies have lacked substantive understanding of the antitrust and fair trade policy, the rest of government agencies must have had serious problems in understanding the correst roles and functions of the antitrust system. The policy environment of the Korean antitrust system, including other economic ministries, the Deputy Prime Minister, and President Chun, have tended to conceptualize the OFT more as an agency aiming only at fair trade policy and less as an agency that should enforce structural monopoly regulation as well. Based on this assessment of the performance of the Korean antitrust system, this paper evaluate current reform proposals for the MRFT A. The inclusion of the regulation of conglomerate mergers and of business divestiture orders may be a desirable revision, giving the MRFTA more complete provisions. However, given deficient staff experties and the unfavorable policy environments, it would be too optimistic and naive to expect that the inclusion of these provisions alone could improve the performance of the Korean antitrust system. In its conclusion, this paper suggests several policy recommendations for the Korean antitrust system, which would secure the stable development and accumulation of antitrust expertise for its staff members and enough understanding and conformity from its environments about its antitrust goals and functions.

• Journal of Korea Water Resources Association
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• v.45 no.3
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• pp.301-316
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• 2012

Two models, TANK and SWAT (Soil and Water Assessment Tool) were compared for simulating natural flows in the Paldang Dam upstream areas of the Han River basin in order to understand the limitations of TANK and to review the applicability and capability of SWAT. For comparison, simulation results from the previous research work were used. In the results for the calibrated watersheds (Chungju Dam and Soyanggang Dam), two models provided promising results for forecasting of daily flows with the Nash-Sutcliffe model efficiency of around 0.8. TANK simulated observations during some peak flood seasons better than SWAT, while it showed poor results during dry seasons, especially its simulations did not fall down under a certain value. It can be explained that TANK was calibrated for relatively larger flows than smaller ones. SWAT results showed a relatively good agreement with observed flows except some flood flows, and simulated inflows at the Paldang Dam considering discharges from upper dams coincided with observations with the model efficiency of around 0.9. This accounts for SWAT applicability with higher accuracy in predicting natural flows without dam operation or artificial water uses, and in assessing flow variations before and after dam development. Also, two model results were compared for other watersheds such as Pyeongchang-A, Dalcheon-B, Seomgang-B, Inbuk-A, Hangang-D, and Hongcheon-A to which calibrated TANK parameters were applied. The results were similar to the case of calibrated watersheds, that TANK simulated poor smaller flows except some flood flows and had same problem of keeping on over a certain value in dry seasons. This indicates that TANK application may have fatal uncertainties in estimating low flows used as an important index in water resources planning and management. Therefore, in order to reflect actually complex and complicated physical characteristics of Korean watersheds, and to manage efficiently water resources according to the land use and water use changes with urbanization or climate change in the future, it is necessary to utilize a physically based watershed model like SWAT rather than an existing conceptual lumped model like TANK.