• Journal of Korean Neurosurgical Society
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• v.63 no.5
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• pp.598-606
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• 2020

Objective : The purpose of this study was to evaluate the impact of time interval between index event and stenting on the periprocedural risk of stenting for symptomatic carotid stenosis and to determine the optimal timing of stenting. Methods : This retrospective study included 491 (322 symptomatic [65.6%] and 169 asymptomatic [34.4%]) patients undergoing carotid stenting. The symptomatic patients were categorized into Day 0-3, 4-7, 8-10, 11-14, 15-21, and >21 groups according to the time interval between index event and stenting. Periprocedural (≤30 days) risk for clinical (any neurological deterioration) and radiological (new infarction on postprocedural diffusion-weighted imaging) events of stenting in each time interval versus asymptomatic stenosis was calculated with logistic regression analysis adjusted for confounders, and provided as odds ratio (OR) and 95% confidence interval (CI). Results : Overall clinical event rate (4.3%) of stenting for symptomatic carotid stenosis was higher than that for asymptomatic stenosis (1.2%; OR, 3.979 [95% CI, 1.093-14.489]; p=0.036). Stenting in Day 0-3 (13.2%; OR, 10.997 [95% CI, 2.333-51.826]; p=0.002) and Day 4-7 (8.3%; OR, 6.775 [95% CI, 1.382-33.227]; p=0.018) was associated with high risk for clinical events. However, the clinical event rates in stenting after 7 days from index event (Day 8-10, 1.8%; Day 11-14, 2.5%; Day 15-21, 0%; Day >21, 2.9%) were not different from that in stenting for asymptomatic stenosis. Overall radiological event rate (55.6%) in symptomatic stenosis was also higher than that in asymptomatic stenosis (35.5%; OR, 2.274 [95% CI, 1.553-3.352]; p<0.001). The high risk for radiological events was maintained in all time intervals (Day 0-3 : 55.3%; OR, 2.224 [95% CI, 1.103-4.627]; p=0.026; Day 4-7 : 58.3%; OR, 2.543 [95% CI, 1.329-4.949]; p=0.005; Day 8-10 : 53.6%; OR, 2.096 [95% CI, 1.138-3.889]; p=0.018; Day 11-14 : 57.5%; OR, 2.458 [95% CI, 1.225-5.021]; p=0.012; Day 15-21 : 55.6%; OR, 2.271 [95% CI, 1.099-4.764]; p=0.028; Day >21 : 54.8%; OR, 2.203 [95% CI, 1.342-3.641]; p=0.002). Conclusion : This study showed that as stenting was delayed, the periprocedural risk for clinical events decreased. The clinical event risk was high only in stenting within 7 days and comparable with that for asymptomatic stenosis in stenting after 7 days from index event, although the radiological event risk was not affected by stenting timing. Therefore, our results suggest that delayed stenting after 7 days from symptom onset is a safe strategy for symptomatic stenosis.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.259-268
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• 2011

This study aimed to examine the kinematic characteristics of the national elite cross-country skiers' double poling technique and to provide the quantitative data for better performance. Four male elite cross-country roller skiers skied maximum velocity with Double Pole technique. The cycle characteristics with angles of elbow, hip, and knee joint were analyzed. The results showed that CM velocity of the body was increased with the third cycle, the cycle time and length were also increased. The poling time and recovery time rate showed with 32.79%, 67.44% respectively. The joint angles with elbow, hip and knee were $106^{\circ}$, $133.14^{\circ}$ $156.87^{\circ}$ at pole in event, $158.94^{\circ}$, $65.7^{\circ}$, $140.19^{\circ}$ at pole out event. Elite skiers should decrease double poling time rate and increase recovery time rate in order to improve the double poling performance. The cycle length and velocity of the double poling should be increased for the better performance. The elbow angle should be minimized at pole in event with maximum extension until pole out event. The hip and knee angles should be increased for the recovery phase.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.6
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• pp.73-80
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• 2017

The objective of this study is to investigate whether the daily rainfall depth derived from daily data represents the event rainfall depth derived from hourly data. For analysis, the 85th, 90th, and 95th percentile daily rainfall depths were first computed using daily rainfall data (1986~2015) collected at 63 weather stations. In addition, the storm event was separated by the interevent time definition (IETD) of 6, 12, 18, and 24 hr using hourly rainfall data. Based on the separated storm events, the 85th, 90th, and 95th percentile event rainfall depths were calculated and compared with the using hourly rainfall data with the 85th, 90th, and 95th percentile daily rainfall depths. The event rainfall depths computed using the IETD were greater than the daily rainfall depths. The difference between the event rainfall depth and the daily rainfall depth affects the design and size of the facility for controlling the stormwater. Therefore, the designer and policy decision-maker in designing the stormwater best management practices need to take into account the difference generated by the difference of the used rainfall data and the selected IETD.

• Convergence Security Journal
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• v.18 no.5_1
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• pp.33-43
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• 2018

In this paper, we want to solve the problems that users want to search the progress of attack, continuity of attack, association between attackers and victims, blocking priority and countermeasures by using visualization interface with multi-rotational axis and radial axis structure. It is possible to effectively monitor and track security events by arranging a time series event based on a multi-rotational axis structured by an event generation order, a subject of an event, an event type, and an emission axis, which is an objective time indicating progress of individual events. The proposed interface is a practical visualization interface that can apply attack blocking and defense measures by providing the progress and progress of the whole attack, the details and continuity of individual attacks, and the relationship between attacker and victim in one screen.

• Korean Journal of Computational Design and Engineering
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• v.15 no.4
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• pp.279-288
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• 2010

In this paper, a DEVS(Discrete EVent Systems Specification)-HLA(High Level Architecture) interface was developed in order to perform the simulation using the combined discrete event and discrete time simulation model architecture in a distributed environment. The developed interface connects the combined simulation model with the HLA/RTI(Run-Time Infrastructure) which is an international standard middleware for distributed simulation. The interface consists of an interface model, a model interpreter, and a distributed environment interpreter. The interface model was defined by using the combined simulation architecture in order to easily connect the existing combined simulation model without modification with the HLA/RTI. The model interpreter takes charge of data transmission between the interface model and the combined simulation model. The distributed environment interpreter takes charge of data transmission between the interface model and the HLA/RTI. To evaluate the applicability of the developed interface, it was applied to the diving simulation of a submarine in a distributed environment. The result shows that a simulation result in a distributed environment using the interface is the same to the result in a single computing environment.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.10a
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• pp.24-30
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• 1993

When modeling a complex system we use an event tree to analyze propagation of failure. An event tree cannot represent the statistical interrelationships among parameters, but it can be represented as a statistically identical influence diagram so that parameter updating can be easily performed. After updating parameters we can calculate posterior distribution of the failure rate for each path. But exact distribution requires considerably complex numerical integration. We propose an approximation method to calculate the posterior and derive the predictive distribution of the time to next failure. Finally we introduce the system which implements our methodology.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.60.2-60.2
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• 2019

Based on our experience on exoplanet transit observation, we propose the exoplanet science cases with Small Telescope Network. One is the follow-up observation for validation of exoplanet candidates. TESS(Transiting Exoplanet Survey Satellite) is pouring out exoplanet candidates in bright stars(V<15) on all the sky. Since Small Telescope Network will consist of 0.5-1m telescopes, we will expect to produce promising outcomes from the follow-up observation of bright candidates. Next is the transit time observation. By spectroscopy of space and large telescopes during transit event, it can be possible to find the bio signatures in exoplanet atmosphere. So, in terms of cost, it is critical to determine the exact time of transit event. In addition, detecting the variation of transit time can reveal another exoplanet and exomoon in the system. In order to determine the transit time and its variation, the accumulation of transit event data is more important than the quality of photometric data. We expect that it can be a challenging project of Small Telescope Network.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1087-1094
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• 2010

With recent growth of population and industry, urban development grows into grand scheme of excavation and construction in urban area. As the development progress advanced, the developments get large and deepen. With a progress of technology development in geotechnical engineering in Korea, most our grand scheme of projects follows great progress. On the other hand, some excavation in construction site caused direct or indirect event that affects the adjacent or surrounding structures by excavation from time to time. This event usually happens around residential and commercial area where underground tunnel, subway station, commercial building, and high-rises excavation site is, could lead great damage on economy as well as personal injury or human casualties. In order to prevent this event, the study has to be done with analysis on various events of excavation and its cause. In this paper, the research has collected the various excavation events and their causes to analyze on each site and event to define emphasis on surrounding environment.

• Journal of the Korean Society for information Management
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• v.25 no.4
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• pp.227-243
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• 2008

This study investigates an event detection method with the aim of generating an event-focused news summary from a set of news articles on a certain event using a multi-document summarization technique. The event detection method first classifies news articles into the event related topic categories by employing a SVM classifier and then creates event clusters containing news articles on an event by a modified single pass clustering algorithm. The clustering algorithm applies a time penalty function as well as cluster partitioning to enhance the clustering performance. It was found that the event detection method proposed in this study showed a satisfactory performance in terms of both the F-measure and the detection cost.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.219-227
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• 2008

The DEVS (Discrete Event Systems Specification) formalism supports specification of discrete event models in a hierarchical modular manner. MATLAB/Simulink is widely used for modeling, simulating and analyzing continuous and discrete time systems. This paper proposes a realization of the DEVS formalism in MATLAB/ Simulink. The proposed design enables to use a great amount of mathematical packages and functions included in MATLAB /Simulink. The design is also employed as real time simulation and hybrid system simulation which is a mixture of continuous systems and discrete event systems. The paper introduces Simulink-DEVS model, in which a simulation algorithm is embedded. The model consists of a Simulink-atomic model and a Simulink-coupled model. In addition, the time advance algorithm to simulate the model is suggested. The algorithm handles the time synchronization and the accommodation of different concepts specific to continuous and discrete event models. Two experimental results are presented for a pure discrete event model and a hybrid model.