• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.36.3-37
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• 2018

We present a new catalog of hard X-ray sources detected in the first 105 months of observations with the Burst Alert Telescope (BAT) on board the Neil Gehrels Swift observatory. The 105 month Swift-BAT survey is a uniform hard X-ray all-sky survey performed in the 14-195 keV band. The Swift-BAT 105 month catalog provides 1632 (422 new detections) hard X-ray sources in the 14 - 195 keV band above the 4.8 sigma significance level. Adding to the previously known hard X-ray sources, 34% (144/422) of the new detections are identified as Seyfert AGN in nearby galaxies (z < 0.2). The majority of the remaining identified sources are X-ray binaries (7%, 31) and blazars/BL Lac objects (10%, 43). As part of this new edition of the Swift-BAT catalog, we release eight-channel spectra and monthly sampled light curves for each object in the online journal and at the Swift-BAT 105 month Web site.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.371-374
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• 2015

Classical Cepheids (hereafter Cepheids) belong to a class of important variable stars that can be used to determine distances to nearby galaxies via the famous period-luminosity (PL) relations, i.e. the Leavitt Law. In turn, these distances can then be used to calibrate a host of secondary distance indicators located well within the Hubble flow, and ultimately determine the Hubble constant in a manner independent of the Cosmic Microwave Background (CMB) measurements. Some recent progress in determining the Hubble constant to within ~ 3% level via the Cepheid-based distance scale ladder (the SH0ES and the Carnegie Hubble Program) were first summarized in this Proceeding, followed by a brief discussion on the prospect of using ultra-long period Cepheids (ULPC) in future distance scale work. ULPC are those Cepheids with periods longer than 80 days, which seem to follow a different PL relation than their shorter period Cepheids. It has been suggested that ULPC can be used to determine the Hubble constant in "one-step". However, based on the two ULPCs found in M31, it was found that the large dispersion in derived distance moduli leads to a less accurate distance modulus to M31 compared to the classical Cepheids. This finding might raise an alert regarding the use of ULPCs in future distance scale work.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.328-328
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• 2021

최근 전 지구적인 기후변화의 영향은 강우량의 집중을 야기하며 홍수피해의 규모를 증가시키는 영향을 끼친다. 특히, 아세안 국가들은 해수면 상승, 태풍 및 집중호우에 의한 침수피해 빈발로 최소 2,000만명이 영향을 받고 있다. 국내의 홍수예보모형을 수출하여 아세안 국가에 구축하고 있으나 통신 시설이 불안정하여 중앙제어 방식의 기존의 홍수예보시스템만으로는 긴급상황에 대한 대처가 부족할 수 있다. 따라서 본 연구에서는 하나의 관측소에서 수위, 강우의 관측과 홍수예측, 경보까지 한번에 가능한 관측소를 개발하기 위해 관측된 수위와 강우자료를 활용하여 인공지능기반의 하천수위예측 모형을 개발하였다. 목표 리드타임은 30분에서 6시간으로 설정하였으며 모형은 Tensorflow로 구축하였다. 시계열 자료의 예측에 적합한 LSTM 기법을 적용하였다. 연구의 대상지역은 건설연의 계측시험유역인 설마천유역으로 하였으며 학습에는 2009년부터 2020년까지의 10분 단위 수위 및 강우량자료를 활용하였다. 연구결과 설마천 유역은 규모가 작고 도달시간이 짧아 1시간 후 예측까지는 높은 정확도를 나타냈으나 3시간 이상의 예측결과는 다소 낮게 평가되었다. 다만, 비상상황에서 통신이 두절된 상황에서 위급하게 대피를 위해 홍수경보를 발령하는데는 활용이 가능 할 것으로 판단된다.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.258-270
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• 2016

This study was conducted to test the green-tide mitigation technique in the lower part of the Sook Stream (Chusori) of Daecheong Reservoir from June 27 to August 24, 2014. And the effects were compared with weekly monitoring result of the watching station of the algae alert system (AAS) as well as test beds reach. The green-tide in a test bed was begun from the upstream, and it was gradually transferred and spread toward the downstream by the hydrological factors. The total amount of algae removed by algae removal device during the test period was 33,920 kg, and solids dewatered by natural gravity was 8,480 kg. Also chlorophyll-a content was 2.83 kg, the number of blue-green algae cells was equivalent to $78.6{\times}10^{14}$ cells. Compared with the results of the watching station of AAS, the pre-concentrate removal work in the outbreak waters was able to suggest the possibility of green-tide mitigation. In addition, an effective management of the green-tide was required spatial and temporal occurrence information and practical device technology. Particularly, the optimal timing of algae removal in the river-reservoir hybrid system was recommended at times before the monsoon rainy season and reached the lowest water level.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1433-1446
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• 2013

In this study, we proposed a methodology to develop Rating Curves for high water level using rainfall generation by the Monte Carlo Simulation (MCS) technique, optimized rainfall-runoff model, and flood routing model in an urban stream. The developed stage discharge Rating Curve based on observed data was contained flow measurement errors and uncertainties. The standard error ($S_e$) for observations was 0.056, and the random uncertainty ($2S_{mr}$) was analyzed by ${\pm}1.43%$ on average, and up to ${\pm}4.27%$. Moreover, it was found that the Rating Curve extensions by way of logarithmic and Stevens methods were overestimated to compare with the urban basin scale. Finally, we confirmed that the high water level extension by random generation of hydrological data using MCS can be reduced uncertainty of the high water level, and it will consider as a more reliable approach for high water level extension. In the near future, this results can be applied to real-time flood alert system for urban streams through construction of the high water level extension system using MCS procedures.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.7 no.2
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• pp.149-163
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• 2000

The purposes of this study were to investigate the pathway which stroke patients take in seeking medical care and to identify factors which influence that pathway. This study was conducted by a survey. The subjects were 130 adults, who were diagnosed with a stroke between January and April of 2000. Data was collected by means of a interview, questionnaires, and an Activity Index. The result of this study are summarized as follows: 1. The mean age of subject was 61.58 years. Forty-nine percent were men and fifty percent were women. The majority of the subjects were married. For educational level, thirty-three percent finished elementary school, and twenty-three percent, high school. Most of the subjects reported 'middle' economic status. Ninety-two percent lived with their spouse and children. The diagnosis for seventy-two percent was ischemic stroke and for twenty-two percent, hemorrhagic stroke. 2 The most frequent early sign of stroke was hemiplegia(43.3%), loss of consciousness (36.7%), dysarthria(33.3%). The type of hospital first used was a herb hospital(40.8%), or a western hospital(59.2%). The factors in their choice were ; distance from the hospital to the place that the stroke occurred(47.5%), desire for a herb hospital(15.8%), and an invitation(12.9%). The ischemic stroke patients preferred herb hospitals, but hemorrhagic stroke patients preferred a western hospitals. 3. The pattern of stroke patients seeking medical care was that forty-three percent of stroke patients pass through step 1, forty-six percent, through step 2, and 8.5% through step 3. The more steps, the higher the use of herb hospitals. 4. The factors influencing the pathway of stroke patients seeking medical care were diagnosis, and level of consciousness. Ischemic stroke patients used herb hospitals, more frequently hemorrhagic stroke patients, who used western hospitals. The alert patient preferred a herb hospital, but stupor patients preferred a western hospital. 5. The Activity Index was not related to the pathway which stroke patients used in seeking medical care.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.450-453
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• 2005

A forest fire occurs mainly as natural factor such as wind, temperature or human factor such as light. Recently, the most of forest fire prevention is prediction or prevision against forest fire by using remote sensing technology. However in order to forest fire prevention, the remote sensing has many limitations such as high cost and advanced technologies and so on. Therefore, we need to multisensor integration system that utilize not only remote sensing but also in-situ sensing in order to reduce large damage of forest fire though analysis of happen cause and prediction routing of occurred forest fire. In this paper we propose a multisensor integration system that offers prediction information of factors and route of forest fire by integrates collected data from remote sensor and in-situ sensor for forest fire prevention. The proposed system is based on wireless sensor network for collect observed data from various sensors. The proposed system not only offers great quality information because firstly, raw data level fuse different format of collected data from remote and in-situ sensor but also accomplish information level fusion based on result of first stage. Offered information from our system can help early prevention of factor and early prevision against occurred forest fire which transfer to SMS service or alert service into monitoring interface of administrator.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.559-572
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• 2019

In the southeast sea of Korea, the cold water is concentrated in every summer, showing in abnormal oceanic conditions. Cold water occurred in the southeast sea is dominantly influenced by wind, which occurs when the south wind is continuously blowing for 3 to 7 days more. In this study, water temperature, wind speed and direction data of KMA, KHOA and KHNP, Chlorophyll-a of COMS/GOCI, GHRSST Level 4 SST of NASA, and red tide alert data of the National Institute of Fisheries Science were used to analyze the correlation between occurrence and change of the cold water and the red tide of Cochlodinium polykrikoides. The upwelling cold water mass showed a characteristic of moving northward along the current and occurrence a high concentration of chlorophyll along the water mass. Also, when the warm current were strong, the characteristic of red tide showed a northward moving.

• Journal of Digital Contents Society
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• v.14 no.4
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• pp.455-462
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• 2013

This paper proposes a detection system that, by determining whether a dangerous act is being carried out among other pedestrians in the images captured using CCTV, provides pre-warnings and establishes emergency measures. To determine the presence of a dangerous act, after setting zones of interest and danger zones within those zones of interest, the danger level is determined in accordance with the range of encroachment upon detecting an object. Especially, this research aims at detecting a suicide jump from the bridge and extends to detecting a dangerous act among pedestrians from detecting a dangerous act of only one person with no one in the previous research. This system classifies the status into 3 levels as safe, alert, and danger according to the amount of part being over the bridge railing. If a situation is deemed as warning-worthy and emergency, the integrated control center is immediately alerted to facilitate prevention in advance.

• Safety and Health at Work
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• v.11 no.3
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• pp.275-283
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• 2020

Background: In the absence of a vaccine or treatment, the most pragmatic strategies against an infectious disease pandemic are extensive early detection testing and social distancing. This study aimed to summarize public and workplace responses to Coronavirus Disease-19 (COVID-19) and show how the Korean system has operated during the COVID-19 pandemic. Method: Daily briefings from the Korean Center for Disease Control and the Central Disaster Management Headquarters were assembled from January 20 to May 15, 2020. Results: By May 15, 2020, 11,018 COVID-19 cases were identified, of which 15.7% occurred in workplaces such as health-care facilities, call centers, sports clubs, coin karaoke, and nightlife destinations. When the first confirmed case was diagnosed, the Korean Center for Disease Control and Central Disaster Management Headquarters responded quickly, emphasizing early detection with numerous tests and a social distancing policy. This slowed the spread of infection without intensive containment, shut down, or mitigation interventions. After entering the public health blue alert level, a business continuity plan was distributed. After entering the orange level, the Ministry of Employment and Labor developed workplace guidelines for COVID-19 consisting of social distancing, flexible working schedules, early identification of workers with suspected infections, and disinfection of workplaces. Owing to the intensive workplace social distancing policy, workplaces remained safe with only small sporadic group infections. Conclusion: The workplace social distancing policy with timely implementation of specific guidelines was a key to preventing a large outbreak of COVID-19 in Korean workplaces. However, sporadic incidents of COVID-19 are still ongoing, and risk assessment in vulnerable workplaces should be continued.