• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.347-358
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• 2012

This study aimed to investigate the change of wind speed during winter and summer seasons for 50 years(1961-2010). It were analyzed the mean wind speed, maximum wind speed, windy days and storm days on January and August of 13 weather stations in South Korea. The mean wind speed was decreased in the coastal region(Busan, Jeju, Ulsan, Pohang) in winter and summer seasons. Also it was similar to windy day. The relationship between wind speed and mean temperature has negative correlation in winter season. The relationship is low in summer season. The number of windy day and storm day has negative relation with monthly mean temperature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.2977-2997
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• 2018

In big data era, fresh data grows rapidly every day. More than 30,000 gigabytes of data are created every second and the rate is accelerating. Many organizations rely heavily on real time streaming, while big data stream computing helps them spot opportunities and risks from real time big data. Storm, one of the most common online stream computing platforms, has been used for big data stream computing, with response time ranging from milliseconds to sub-seconds. The performance of Storm plays a crucial role in different application scenarios, however, few studies were conducted to evaluate the performance of Storm. In this paper, we investigate the performance of Storm under different application scenarios. Our experimental results show that throughput and latency of Storm are greatly affected by the number of instances of each vertex in task topology, and the number of available resources in data center. The fault-tolerant mechanism of Storm works well in most big data stream computing environments. As a result, it is suggested that a dynamic topology, an elastic scheduling framework, and a memory based fault-tolerant mechanism are necessary for providing high throughput and low latency services on Storm platform.

• Journal of Astronomy and Space Sciences
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• v.34 no.4
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• pp.245-250
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• 2017

As a part of collaborative efforts to understand ionospheric irregularities, the Korea ionospheric scintillation sites (KISS) network has been built based on global positioning system (GPS) receivers with sampling rates higher than 1 Hz. We produce the rate of TEC index (ROTI) to represent GPS TEC fluctuations related to ionospheric irregularities. In the KISS network, two ground-based GPS sites at Kiruna (marker: KIRN; geographic: $67.9^{\circ}$ N, $21.4^{\circ}$ E; geomagnetic: $65.2^{\circ}$ N) and Chuuk (marker: CHUK; geographic: $7.5^{\circ}$ N, $151.9^{\circ}$ E; geomagnetic: $0.4^{\circ}$ N) were selected to evaluate the ROTI value for ionospheric irregularities during the occurrence of the 2015 St. Patrick's Day storm. The KIRN ROTI values in the aurora region appear to be generally much higher than the CHUK ROTI values in the EIA region. The CHUK ROTI values increased to ~0.5 TECU/min around UT=13:00 (LT=23:00) on March 16 in the quiet geomagnetic condition. On March 17, 2015, CHUK ROTI values more than 1.0 TECU/min were measured between UT=9:00 and 12:00 (LT=19:00 and 22:00) during the first main phase of the St. Patrick's Day storm. This may be due to ionospheric irregularities by increased pre-reversal enhancement (PRE) after sunset during the geomagnetic storm. Post-midnight, the CHUK ROTI showed two peaks of ~0.5 TECU/min and ~0.3 TECU/min near UT=15:00 (LT=01:00) and UT=18:00 (LT=04:00) at the second main phase. The KIRN site showed significant peaks of ROTI around geomagnetic latitude=$63.3^{\circ}$ N and MLT=15:40 on the same day. These can be explained by enhanced ionospheric irregularities in the auroral oval at the maximum of AE index

• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.68-75
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• 2010

Recently, the intensity and frequency of typhoons have been on the increase due to unusual weather phenomena and climate change. In particular, on September 13, 2003, typhoon MAEMI (0314) caused heavy damage in the provinces of Busan and Gyongnam, but also provided an opportunity to perform a variety of studies on storm surge. According to investigation reports on the damage resulting from typhoon MAEMI, the areas where coastal inundation occurred were located in reclaimed land under coastal development. In this study, through an image data analysis of historic and present day typhoons affecting Masan, we found that the inundation damage areas corresponded to reclaimed lands. Therefore, using the area around Busan, including the southeastern coast of Korea where typhoons lead to an increased storm surge risk, we performed a storm surge/inundation simulation, and examined the inundation effect on reclaimed land due to the intensified typhoons predicted for the future by climate change scenarios.

• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.133-147
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• 2019

Challenging Minisatellite Payload (CHAMP) satellite magnetic data are used to investigate the latitudinal variation of the storm-time meso-scale field-aligned currents by defining a new metric called the FAC range. Three major geomagnetic storm events are considered. Alongside SymH, the possible contributions from solar wind dynamic pressure and interplanetary magnetic field (IMF) $B_Z$ are also investigated. The results show that the new metric predicts the latitudinal variation of FACs better than previous studies. As expected, the equatorward expansion and poleward retreat are observed during the storm main phase and recovery phase respectively. The equatorward shift is prominent on the northern duskside, at ${\sim}58^{\circ}$ coinciding with the minimum SymH and dayside at ${\sim}59^{\circ}$ compared to dawnside and nightside respectively. The latitudinal shift of FAC range is better correlated to IMF $B_Z$ in northern hemisphere dusk-dawn magnetic local time (MLT) sectors than in southern hemisphere. The FAC range latitudinal shifts responds better to dynamic pressure in the duskside northern hemisphere and dawnside southern hemisphere than in southern hemisphere dusk sector and northern hemisphere dawn sector respectively. FAC range exhibits a good correlation with dynamic pressure in the dayside (nightside) southern (northern) hemispheres depicting possible electrodynamic similarity at day-night MLT sectors in the opposite hemispheres.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.523-532
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• 2015

Hydrocyclone is widely used in industry, for its simple design, high capacity, low maintenance and low operational cost. The objective of this study is to develop hydrocyclone coagulation and filtration system. The system is made of hydrocyclone ballasted coagulation with polyaluminium chloride silicate (PACS) and upflow filter to treat micro particles in urban storm runoff. Roadside sediment particles (< $200{\mu}m$) was mixed with tap water to make various turbid suspensions to simulate urban storm runoff. The filter cartridge was filled with polyethylene media system and ran 1hr per everyday and total operation time were 8.19hrs and backwashing everyday after end of operation. The operation condition of flowrate was $8.2{\sim}11.9m^3/day$ (mean $10.1m^3/day$) and surface overflow rate (SOR) based on filter surface area was $45.5{\sim}65.9m^3/m^2/day$ (mean $55.7m^3/m^2/day$). The range of PACS dosage concentration was 14.0~31.5 mg/L. As the results of operation, the range of removal efficiency of turbidity, SS were 81.0~95.8% (mean 89.5%) 81.8~99.0% (mean 91.4%), respectively. An increase of filtration basin retention time brought on increased of removal efficiency of turbidity and SS, and increase of SOR brought on decreased of removal efficiency. During the first flush in urban area, storm runoff have an high concentration of SS (200~600 mg/L) and the filtration bed becomes clogged and decreased of removal efficiency. Backwashing begins when the drainage pipe valve at the filtration tank bottom is completely open (backwashing stage 1). Backwashing stage 2 was using air bubbles and water jet washing the media for 5 mins and open the drainage valve. After backwashing stage 1, 2, 61.83~64.04%, 18.53~27.51% of SS loading was discharged from filtration tank, respectively. Discharged SS loading from effluent was 7.12~14.79% and the range of residual SS loading in fliter was 2.26~5.00%. The backwashing effects for turbidity, SS were 89.5%, 91.4%, respectively. The hydrocyclone coagulation and filtration with backwashing system, which came out to solve the problems of the costly exchange filter media, and low efficiency of removing micro particles of filter type nonpoint treatment devices, is considered as an alternative system.

• Journal of the Korean Geographical Society
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• v.33 no.3
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• pp.395-409
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• 1998

The purpose of this paper is to determine the atmospheric conditions in whih urban areas affect the precipitation processes and to evaluate whether certain weather types show more apparent urban effect on precipitation modification over five cities in the southem United States. Each heavy rainstorm is classified into one of three synoptic weather types (frontal storm, airmass storm or tropical disturbance storm). Heavy rainstorm day is defined as day producing rainfall totals that equal o exceed 2 inches (50.08 mm). Houston, Dallass and San Antonio show possible urban effects on rainfall totals and frequencies of heavy rainstorms by airmass storm type while New Orleans and Memphis do not reveal any distinct precipitation enhancements through the synoptic analysis. The results of TSA (Trend Surface Analysis) show that frontal and tropical disturbance storm types have stronger climatic gradients than airmass types and the patterns of rainfall totals have stronger trends than those of rainfall frequencies for the five cities. The results suggest that airmass type events may well reveal possible precipitation enhancements due to urban effects since they are less influenced by a strong climate gradient and they provide favorable conditions for development of urban heat islands. Residual analysis confirms that rainfall totals and frequencies of heavy rainstorms by airmass storm type have positive residuals over the city or the major effect area.

• Journal of Astronomy and Space Sciences
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• v.39 no.4
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• pp.145-158
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• 2022

The dynamics of the outer zone radiation belt has received a lot of attention mainly due to the correlation between the occurrence of enhancing relativistic electron flux and spacecraft operation anomalies or even failures (e.g., Baker et al. 1994). Relativistic electron events are often observed during great storms associated with ultra low frequency (ULF) waves. For example, a large buildup of relativistic electrons was observed during the great storm of March 24, 1991 (e.g., Li et al. 1993; Hudson et al. 1995; Mann et al. 2013). However, the dominant processes which accelerate magnetospheric radiation belt electrons to MeV energies are not well understood. In this paper, we present observations of Pc5 ULF waves in the recovery phase of the Bastille day storm of July 16, 2000 and electron and proton flux simultaneously oscillating with the same frequencies as the waves. The mechanism for the observed electron and proton flux modulations is examined using ground-based and satellite observations. During this storm time, multiple packets of discrete frequency Pc5 ULF waves appeared associated with energetic particle flux oscillations. We model the drift paths of electrons and protons to determine if the particles drift through the ULF wave to understand why some particle fluxes are modulated by the ULF waves and others are not. We also analyze the flux oscillations of electrons and protons as a function of energy to determine if the particle modulations are caused by a ULF wave drift resonance or advection of a particle density gradient. We suggest that the energetic electron and proton modulations by Pc5 ULF waves provide further evidence in support of the important role that ULF waves play in outer radiation belt dyanamics during storm times.

• Korean Journal of Veterinary Service
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• v.46 no.2
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• pp.167-173
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• 2023

An 8-year-old female neutered Maltese dog exhibited signs of serious thunderstorm phobia including panting, wandering, shivering, hiding, crying or whining, or trying to escape from the house. In this study, we administered clomipramine and alprazolam and observed behavioral improvement for 3 years. Clinical symptoms measured according to the storm phobia assessment (SPA) were significantly high with an initial total score of 19 points. However, it improved to a total score of 8 on day 176 after drugs administration and returned to the normal level with the total score of 5 points on the 983 days. When the symptoms for the first 4 treatments and the last 4 treatments were compared in 2 groups, the total score of all clinical symptoms decreased to -62.83% in the last 4 treatments. This study found that treatment with alprazolam and clomipramine was associated with a decrease in clinical signs of storm anxiety, suggesting that two drugs would be effective in reducing symptoms caused by anxiety, thunderstorm phobia, and noise phobia. In this follow up study, we hope that more studies would be conducted on behavior modification for treatment of storm phobia in veterinary medicine.

• Journal of Korea Water Resources Association
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• v.40 no.7
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• pp.533-543
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• 2007

This study characterized and qualitatively analyzed the storm events recorded in the Annals of Chosun Dynasty. First of all, the storm events are retrieved using the like Keun-Bi (big rain), Keun-Mul (high water), Hong-Soo (flood), and Pok-Woo (torrential rain). The storm events cited as Keun-Bi do not include any in detail explanation about the storm and damages, but the storm events cited as Keun-Mul, Hong-Soo, and Pok-Woo generally include in detail information. That is, the Keun-Bi was named simply based on the amount of rainfall, but the other three were named considering the runoff with significant damages. Evaluation of effective rainfall derived by the simple SCS method showed that most storm events named Keun-Bi had small antecedent five day rainfall amount to be categorized into AMC-1, but the others mostly into AMC-III. As result, the effective rainfall of Keun-Mul, Hong-Soo, and Pok-Woo were estimated much higher than those of Keun-Bi. Most storm events with lengthy explanation belong to the events with lots of damages, which also includes Keun-Mul, Hong-Soo, and Pok-Woo.