• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.559-563
• /
• 2015

Monitor of All-sky X-ray Image (MAXI) is a Japanese X-ray all-sky surveyer mounted on the International Space Station (ISS). It has been scanning the whole sky since 2009 during every 92-minute ISS rotation. X-ray transients are quickly found by the real-time nova-search program. As a result, MAXI has issued 133 Astronomer's Telegrams and 44 Gamma-ray burst Coordinated Networks so far. MAXI has discovered six new black holes (BH) in 4.5 years. Long-term behaviors of the MAXI BHs can be classified into two types by their outbursts; a fast-rise exponential-decay type and a fast-rise flat-top one. The slit camera is suitable for accumulating data over a long time. MAXI issued a 37-month catalog containing 500 sources above a ~0.6 mCrab detection limit at 4-10 keV in the region ${\mid}{b}{\mid}$ > $10^{\circ}$. The SSC instrument utilizing an X-ray CCD has detected diffuse soft X-rays extending over a large solid angle, such as the Cygnus super bubble. MAXI/SSC has also detcted a Ne emission line from the rapid soft X-ray nova MAXI J0158-744. The overall shapes of outbursts in Be X-ray binaries (BeXRB) are precisely observed with MAXI/GSC. BeXRB have two kinds of outbursts, a normal outburst and a giant one. The peak dates of the subsequent giant outbursts of A0535+26 repeated with a different period than the orbital one. The Be stellar disk is considered to either have a precession motion or a distorted shape. The long-term behaviors of low-mass X-ray binaries (LMXB) containing weakly magnetized neutron stars are investigated. Transient LMXBs (Aql X-1 and 4U 1608-52) repeated outbursts every 200-1000 days, which is understood by the limit-cycle of hydrogen ionization states in the outer accretion disk. A third state (very dim state) in Aql X-1 and 4U 1608-52 was interpreted as the propeller effect in the unified picture of LMXB. Cir X-1 is a peculiar source in the sense that its long-term behavior is not like typical LMXBs. The luminosity sometimes decreases suddenly at periastron. It might be explained by the stripping of the outer accretion disk by a clumpy stellar wind. MAXI observed 64 large flares from 22 active stars (RS CVns, dMe stars, Argol types, young stellar objects) over 4 years. The total energies are $10^{34}-10^{36}$ erg $s^{-1}$. Since MAXI can measure the spectrum (temperature and emission measure), we can estimate the size of the plasma and the magnetic fields. The size sometimes exceeds the size of the star. The magnetic field is in the range of 10-100 gauss, which is a typical value for solar flares.

• Journal of the Korean Society of Safety
• /
• v.11 no.2
• /
• pp.150-159
• /
• 1996

In this paper, an A-team(Asynchronous Team ) based approach for Reactive power and volage control considering static security assessment in a power system with infrastructural deficiencies is proposed. Reactive power and voltage control problem is the one of optimally establishing voltage level given several constraints such as reactive generation, voltage magnitude, line flow, and other switchable reactive power sources. It can be formulated as a mixed-integer linear programming(MILP) problem without deteriorating of solution accuracy to a certain extent. The security assessment is to estimate the relative robustness of the system in Its present state through the evaluation of data provided by security monitoring. Deterministic approach based on AC load flow calculations is adopted to assess the system security, especially voltage security. A security metric, as a standard of measurement for power system security, producting a set of discrete values rather than binary values, is employed. In order to analyze the above two problems, reactive power/voltage control problem and static security assessment problem, in an integrated fashion for real-time operations, a new organizational structure, called an A-team, is adopted. An A-team is an organization for agents which ale all autonomeus, work in parallel and communicate asynchronously, which is well-suited to the development of computer-based, multi-agent systems for operations. This A-team based approach, although it is still in the beginning stage, also has potential for handling other difficult power system problems.

• The Journal of the Korea Contents Association
• /
• v.9 no.9
• /
• pp.18-30
• /
• 2009

Recently, although the requirement of quality of VOD content has been transferred upto the class of HD, conventional management systems characterized by OS dependency are truly limited in quality of video image, stability, and compatibility of network environments. In addition most of the content management systems realize very limited capabilities for the real affairs of content management and distribution services in such an OS dependent environment. In this paper, we propose a new scheme of HD-Class VOD Content Management System to solve these problems. We design and implement the proposed system based on open sources by using H.264 video compression method. The proposed system offers high quality content management method based on opened systems and independent on-line distribution method so that it can be realized as an integrated management scheme for VOD contents. Moreover, our system solves the problems of occasional cutting-down video, small screen, and poor image quality that exist in the conventional wmv-type CMS. According to the result of performance evaluation, our system maintains sufficient performance and tolerence for the case of large scale HD content operations or fabrications. We expect that the proposed integrated DB scheme will especially be effective when the content management applications are changed from Internet Web environments to mobile terminal environments.

• Korean Journal of Legislative Studies
• /
• v.23 no.2
• /
• pp.67-108
• /
• 2017

How well citizens are represented by their representatives holds critical importance in representative democracy. While previous studies of ideological congruence have largely focused on Western established democracies, there was not as much attention paid to young democracies including, South Korea. This article investigates ideological congruence in South Korea based on multiple survey data sources collected from 2002 to 2016. When it comes to unidimensional Left-Right ideology, the distance between citizens and governments, unlike its citizen-assembly counterpart, has widened since 2000 sending a negative signal to the norm of representative democracy. As to multidimensional issue positions, however, it turns out that ideological congruence in South Korea has varied along issues such as aids to North Korea and Welfare spending. These results provide both citizens and parties with some important implications. For citizens, they are required to distinguish which party or candidate is more representative of the issue they value the most beyond a simple Left-Right line; for parties, they are required to deal with how to represent their supporters as well as today's increasing independents by strengthening their organizational capacity and providing effective party programs.

• Journal of Convergence for Information Technology
• /
• v.9 no.12
• /
• pp.294-301
• /
• 2019

This study evaluated the antioxidant activity and the anti-inflammatory activity of ethanol extracted Pyracantha angustifolia (PE) or hot water extracted P. angustifolia (PW) using natural plant sources. In the DPPH and ABTS assay, the PE extracts showed the highest activity with an IC₅₀ of 3.78 ㎍/mL, IC₅₀ of 510.57 ㎍/mL, respectively. The total polyphenol content of PE extracts was 37.11±0.01 mgGAE/mL and PW extracts was 11.46±0.01 mgGAE/mL in a 1 mg/mL. The MTT assay showed no cytotoxicity at all concentration of two extracts in mouse macrophage cell line, RAW264.7. In addition, PE extracts strongly inhibited the production of NO, TNF-α cytokine secretion, and iNOS/TNF-α mRNA expression stimulated by LPS in RAW264.7 cells. Taken together, these results suggest that P. angustifolia, especially the ethanol extracts (PE), can be used as a cosmetic material containing natural antioxidant and anti-inflammatory properties.

• Journal of Korea Port Economic Association
• /
• v.37 no.1
• /
• pp.143-157
• /
• 2021

International organizations such as the World Health Organization, the Organization for Economic Development and Cooperation, and major developed countries recognize the seriousness of air pollution. International organizations such as the International Maritime Organization have also implemented various regulations to reduce air pollution from ships. In line with this international trend, the government has also enacted a special law on improving air quality in port areas, and is making efforts to reduce air pollution caused by ports. The purpose of the Special Act is to implement comprehensive policies to improve air quality in port areas. This study sought to identify the emissions of each source of air pollutants originating from the port and prepare basic data on setting the policy priorities. To this end, the analysis was conducted in six categories: ships, vehicles, loading and unloading equipment, railways, unloading/wild ash dust, road ash dust, and the methodology presented by the European Environment Agency(EEA) and the United States Environmental Protection Agency(EPA). The pollutants subject to analysis were analyzed for carbon monoxide(CO), nitrogen oxides (NOX), sulfur oxides(SOX), total airborne materials(TSP), particulate matter(PM10, PM2.5), and ammonia(NH3). The analysis showed a total of 7,122 tons of emissions. By substance, NOX accounted for the largest portion of 5,084 tons, followed by CO (984 tons), SOX (530 tons), and TSP (335 tons). By source of emissions, ships accounted for the largest portion with 4,107 tons, followed by vehicles with 2,622 tons, showing high emissions. This proved to be the main cause of port air pollution, with 57.6% and 36.8% of total emissions, respectively, suggesting the need for countermeasures against these sources.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.23 no.1
• /
• pp.54-58
• /
• 2019

Purpose At now, there are many kind of dedicated heart SPECT machine in clinical nuclear medicine. Among those, the fixed focusing type SPECT can make a good quality, quantity image because a detectors of this SPECT arranged forward a special ROI and didn't rotate around of body. So, in this paper, we will evaluate a spatial uniformity about resolution and sensitivity at a same plane of a fixed focusing type SPECT. Materials and Methods We used D-SPECT as a fixed focusing type SPECT and Cario MD as a rotated parallel type SPECT to comparing each other. We injected $^{99m}Tc(14.8MBq/1cc)$ to 10 capillary tube (diameter=1mm), and we set those line sources a tfield of view of each SPECT. And then we acquired SPECT date, we applied are construction by recommended methods. By using two tomography images, we calculated a full width of half maximum as a resolution and total counts as a sensitivity, and we compared a CV (coefficientofvariation) values between two images as a spatial uniformity. Results In case of D-SPECT, a CV of resolution and sensitivity are 7.45%, 12.34%. In case of Cario MD, an CV of resolution and sensitivity are 12.49%, 21.84% Conclusion As a results, CV of resolution and sensitivity of a fixed focusing type SPECT is 67.75%, 77.00% higher than ones of a rotated parallel type SPECT. It means that a fixed focusing type SPECT is more uniformed, because this new SPECT can reduce a motion blur artifact by rotating detector around body, also all of detector that made by semiconductor arrange forward a special FOV like heart.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.4
• /
• pp.633-642
• /
• 2021

Growing demand for electricity, when combined with the need to limit carbon emissions, drives a huge increase in renewable energy industry. In the electric power system, electricity supply always needs to be balanced with electricity demand and network losses to maintain safe, dependable, and stable system operation. There are three broad challenges when it comes to a power system with a high penetration of renewable energy: transient stability, small signal stability, and frequency stability. Transient stability analyze the system response to disturbances such as the loss of generation, line-switching operations, faults, and sudden load changes in the first several seconds following the disturbance. Small signal stability refers to the system's ability to maintain synchronization between generators and steady voltages when it is subjected to small perturbations such as incremental changes in system load. Frequency stability refers to the ability of a power system to maintain steady frequency following a severe system upset resulting in significant imbalance between generation and load. In this paper, we discusses these stability using system simulation by renewable energy deployment plan, and also analyses the influence of the renewable energy sources to the grid stability.

• Animal Bioscience
• /
• v.34 no.11
• /
• pp.1811-1821
• /
• 2021

Objective: A trial was conducted to investigate the effects of supplemental levels of Mn provided by organic and inorganic trace mineral supplements on growth, tissue mineralization, mineral balance, and antioxidant status of growing broiler chicks. Methods: A total of 500 male chicks (8-d-old) were used in 10-day feeding trial, with 10 treatments and 10 replicates of 5 chicks per treatment. A 2×5 factorial design was used where supplemental Mn levels (0, 25, 50, 75, and 100 mg Mn/kg diet) were provided as MnSO₄·H₂O or MnPro. When Mn was supplied as MnPro, supplements of zinc, copper, iron, and selenium were supplied as organic minerals, whereas in MnSO₄·H₂O supplemented diets, inorganic salts were used as sources of other trace minerals. Performance data were fitted to a linearbroken line regression model to estimate the optimal supplemental Mn levels. Results: Manganese supplementation improved body weight, average daily gain (ADG) and feed conversion ratio (FCR) compared with chicks fed diets not supplemented with Mn. Manganese in liver, breast muscle, and tibia were greatest at 50, 75, and 100 mg supplemental Mn/kg diet, respectively. Higher activities of glutathione peroxidase and superoxide dismutase (total-SOD) were found in both liver and breast muscle of chicks fed diets supplemented with inorganic minerals. In chicks fed MnSO₄·H₂O, ADG, FCR, Mn balance, and concentration in liver were optimized at 59.8, 74.3, 20.6, and 43.1 mg supplemental Mn/kg diet, respectively. In MnPro fed chicks, ADG, FCR, Mn balance, and concentration in liver and breast were optimized at 20.6, 38.0, 16.6, 33.5, and 62.3 mg supplemental Mn/kg, respectively. Conclusion: Lower levels of organic Mn were required by growing chicks for performance optimization compared to inorganic Mn. Based on the FCR, the ideal supplemental levels of organic and inorganic Mn in chick feeds were 38.0 and 74.3 mg Mn/kg diet, respectively.

• Smart Media Journal
• /
• v.9 no.4
• /
• pp.102-108
• /
• 2020

In this paper, we propose a real-time method of detecting hand motions and extracting the signal frame induced by EF(Electric Field) sensors. The signal induced by hand motion includes not only noises caused by various environmental sources as well as sensor's physical placement, but also different initial off-set conditions. Thus, it has been considered as a challenging problem to detect the motion signal and extract the motion frame automatically in real-time. In this study, we remove the PLN(Power Line Noise) using LPF with 10Hz cut-off and successively apply MA(Moving Average) filter to obtain clean and smooth input motion signals. To sense a hand motion, we use two thresholds(positive and negative thresholds) with offset value to detect a starting as well as an ending moment of the motion. Using this approach, we can achieve the correct motion detection rate over 98%. Once the final motion frame is determined, the motion signals are normalized to be used in next process of classification or recognition stage such as LSTN deep neural networks. Our experiment and analysis show that our proposed methods produce better than 98% performance in correct motion detection rate as well as in frame-matching rate.