• 대한장애인치과학회지
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• 제4권1호
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• pp.17-20
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• 2008

비정상적인 교상을 예방하기 위한 정확한 protocol은 존재하지 않는다. 하지만 전치부를 발치하는 등의 침습적인 방법을 사용하기 이전에 soft mouth guard를 사용하는 등의 보존적인 방법을 먼저 고려하는 것도 좋은 방법이라 생각되며, 보다 양호한 결과를 얻기 위해서는 관계되는 전문가들과의 협진이 필요 할 것으로 사료된다.

• 천문학회지
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• 제48권4호
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• pp.207-212
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• 2015

We introduce the Lee Sang Gak Telescope (LSGT), a remotely operated, robotic 0.43-meter telescope. The telescope was installed at the Siding Spring Observatory, Australia, in 2014 October, to secure regular and exclusive access to the dark sky and excellent atmospheric conditions in the southern hemisphere from the Seoul National University (SNU) campus. Here, we describe the LSGT system and its performance, present example images from early observations, and discuss a future plan to upgrade the system. The use of the telescope includes (i) long-term monitoring observations of nearby galaxies, active galactic nuclei, and supernovae; (ii) rapid follow-up observations of transients such as gamma-ray bursts and gravitational wave sources; and (iii) observations for educational activities at SNU. Based on observations performed so far, we find that the telescope is capable of providing images to a depth of R = 21:5 mag (point source detection) at 5-σ with 15 min total integration time under good observing conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권7호
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• pp.1831-1853
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• 2012

By sending periodically short bursts of traffic to reduce legit transmission control protocol (TCP) traffic, the low-rate denial of service (LDoS) attacks are hard to be detected and may endanger covertly a network for a long period. Traditionally, LDoS detecting methods mainly concentrate on the attack stream with feature matching, and only a limited number of attack patterns can be detected off-line with high cost. Recent researches divert focus from the attack stream to the traffic anomalies induced by LDoS attacks, which can detect more kinds of attacks with higher efficiency. However, the limited number of abnormal characteristics and the inadequacy of judgment rules may cause wrong decision in some particular situations. In this paper, we address the problem of detecting LDoS attacks and present a scheme based on the fluctuant features of legit TCP and acknowledgment (ACK) traffic. In the scheme, we define judgment criteria which used to identify LDoS attacks in real time at an optimal detection cost. We evaluate the performance of our strategy in real-world network topologies. Simulations results clearly demonstrate the superiority of the method proposed in detecting LDoS attacks.

• Journal of Astronomy and Space Sciences
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• 제33권2호
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• pp.109-117
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• 2016

We explain the results of Yu et al. (2015b) of the novel sharpness angle measurement to a large number of spectra obtained from the Fermi gamma-ray burst monitor. The sharpness angle is compared to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. It is found that more than 91% of the high temporally and spectrally resolved spectra are inconsistent with any kind of optically thin synchrotron emission model alone. It is also found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to 58⁺²³₋₁₈% of the peak flux. These results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed spectra. Since any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin synchrotron radiation are likely required in a full explanation of the spectral peaks or breaks of the GRB prompt emission phase.

• 한국통신학회논문지
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• 제24권9B호
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• pp.1616-1623
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• 1999

본 논문에서는 광대역 코드분할 다중접속(W-CDMA : Wideband-Code Division Multiple Access)방식을 이용하는 전력제어된 무선가입자망(WLL : Wireless Local Loop)시스템에서 무선구간 데이터전송을 위하여 에러제어방식이 추가된 WLL 시스템의 성능을 비교하였다. 영상코딩에는 baseline JPEG 압축방식을 사용하였고 채널코딩에는 연속적인 에러 수정을 위해 RS(Reed-Solomon)코드와 길쌈부호가 연쇄된 truncated Type-I Hybrid ARQ 방식을 이용하였다. truncated Type-I Hybrid ARQ방식을 적용한 경우 같은 BER에 대하여 실제 WLL시스텝보다 약 2dB의 Eb/No 이득이 있음을 시뮬레이션을 통해 알 수 있었다. 따라서 효과적인 저비트율(Low-Bit Rate)의 영상전송을 위한 방법을 제시하여 음성과 동일한 전력으로도 데이터의 요구 BER을 유지할 수 있도록 하였다.

• 천문학논총
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• 제30권3호
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• pp.811-819
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• 2015

The e-CALLISTO is a network of CALLISTO (Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories) spectrometers which detect solar radio bursts 24 hours a day in frequency range 45-870 MHz. The number of channels per spectrum is 200 and the time resolution of whole spectrum is 0.25 second. The Korean e-CALLISTO station was developed by Korea Astronomy and Space Science Institute (KASI) collaborating with Swiss Federal Institute of Technology Zurich (ETH Zurich) since 2007. In this paper, we report replacement of the tracking mount and development of the control program using Visual C++/MFC. The program can make the tracking mount track the Sun and schedule CALLISTO to start and to finish its observation automatically using the Solar Position Algorithm (SPA). Daily tracking errors (RMSE) are 0.0028 degree in azimuthal axis and 0.0019 degree in elevational axis between 2014 January and 2015 July. We expect that the program can save time and labor to make the observations of solar activity for space weather monitoring, and improve CALLISTO data quality due to the stable and precise tracking methods.

• 천문학회보
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• 제42권2호
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• pp.85.2-85.2
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• 2017

The coronal electron density is a fundamental and important physical quantity in solar physics for estimating coronal magnetic fields and analyzing solar radio bursts. To check a validation of coronal electron density distributions (CEDDs) from polarized brightness (pB) measurements with Van de Hulst inversions, we compare CEDDs derived from a polarized brightness (pB) observation [MLSO/MK4 coronameter] and one spectroscopic observation [SOHO/UVCS]. For this, we consider data observed in 2005 with the following conditions: (1) the observation time differences from each other are less than 1 minutes; and (2) O VI doublet (O VI $1031.9{\AA}$ and $1037.6{\AA}$) is well identified. In the pB observation, the CEDDs can be estimated by using Van de Hulst inversion methods. In the spectroscopic observation, we use the ratio of radiative and collisional components of the O VI doublet to estimate the CEDDs. We find that the CEDDs obtained from pB measurements are higher than those based on UVCS observations at the heights between 1.6 and 1.8 Rs (${\times}1.9$ for coronal streamer, 1.2 ~ 1.8 for background corona, and 1.5 for coronal hole), while they are lower than those based on UVCS at the heights between 1.9 and 2.6 Rs (${\times}0.1{\sim}0.6$ for coronal streamer, 0.5 ~ 0.7 for background corona, and 0.6 for coronal hole). The CEDDs of coronal streamers are higher than those of background corona at the between 1.6 and 2.0 Rs: ${\times}1.2{\sim}2.4$ for MK4 and 1.5 ~ 1.9 for UVCS.

• 농촌지도와개발
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• 제7권1호
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• pp.167-173
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• 2000

'거봉' 포도재배시 발생하는 결실불량 현상을 방지하기 위한 적절한 전정방법과 결과모지 선별방법을 구명하기 위하여 안성의 농가 포장과 원예연구소의 포장에서 수행한 연구결과는 다음과 같다. 약전정은 강전정에 비해 발아율, 신초수, 과방중, 착립률을 증가시킨 반면, 신초장, 신초당 엽수와 마디수, 단위 엽면적, 그리고 단위 엽생체중은 감소시켰다. 과실의 당도, 산함량 및 안토시아닌 함량은 약전정구와 강전정구간에 차이가 없었다. 평균신초장은 결과모지의 굵기가 굵을수록 뚜렷이 길어지는 경향을 나타내었으며, 엽면적과 엽록소함량은 결과모지의 굵기가 굵을수록 넓어지거나 높아지는 것으로 나타났다. 총탄수화물 및 N, P, K, Ca 및 Mg 등 무기성분 할량은 결과모지 굵기에 따라 유의한 차이를 보이지 않았으나 총탄수화물과 Ca함량은 결과모지 굵기가 가늘수록 높아지는 경향을 보였다. 과방당유핵과립수는 결과모지가 가늘수록 적어지고 착립률은 높아지는 경향을 나타냈다. 과방중, 과립중, 과방당 과립수, 당도, 안토시아닌 함량은 결과모지 굵기가 1cm 전후인 구에서 높게 나타났다.

• 상하수도학회지
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• 제35권6호
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• pp.517-531
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• 2021

The water supply facilities of Korea have achieved a rapid growth, along with the other social infrastructures consisting a city, due to the phenomenon of urbanization according to economic development. Meanwhile, the level of water supply service demanded by consumer is also steadily getting higher in keeping with economic growth. However, as an adverse effect of rapid growth, the quantity of aged water supply pipes are increasing rapidly, Bursts caused by pipe aging brought about an enormous economic loss of about 6,161 billion won as of 2019. These problems are not only worsening water supply management, also increasing the regional gap in water supply services. The purpose of this study is to classify hazard evaluation indicators and to rank the water distribution network hazard by cluster using the TOPSIS method. In conclusion, in this study, the entropy-based multi-criteria decision-making methods was applied to rank the hazard management of the water distribution network, and the hazard management ranking for each cluster according to the water supply conditions of the county-level municipalities was determined according to the evaluation indicators of water outage, water leakage, and pipe aging. As such, the hazard ranking method proposed in this study can consider various factors that can impede the tap water supply service in the water distribution network from a macroscopic point of view, and it can be reflected in evaluating the degree of hazard management of the water distribution network from a preventive point of view. Also, it can be utilized in the implementation of the maintenance plan and water distribution network management project considering the equity of water supply service and the stability of service supply.

• 한국환경농학회지
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• 제41권4호
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• pp.318-327
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• 2022

BACKGROUND: The mean annual temperature of the Korean Peninsula will continue to rise due to global warming. 'Shiranuhi' mandarin-a late-harvest cultivar-is primarily cultivated in plastic greenhouses where high temperatures cannot be directly avoided. Therefore, growth and fruit quality changes under elevated temperatures must be investigated. METHODS AND RESULTS: Elevated temperatures were divided into three groups [2℃ (T-I), 4℃ (T-II), and 6℃ (T-III) above the ambient temperature] during the 2019-2020 season. Mean temperatures were 17.1℃, 18.6℃, and 20.2℃ in T-I, T-II, and T-III, respectively. The bud bursts in T-II and T-III were earlier than that in T-I at 7 days and 11 days, respectibely. And the full blooms in T-II and T-III were earlier than that in T-I at 11 days and 23 days, respectively. Fruit size significantly increased with increased temperature. The citrus color index in the coloring phase markedly differed across treatments. Further, total soluble solid and acid contents markedly changed with temperature rise but the sugar-to-acid ratio did not. Sucrose content tended to decrease with increase in temperature, but citric acid content remained unaffected. CONCLUSION(S): Elevated temperature accelerated plant growth and development but delayed rind color development in 'Shiranuhi' mandarin. Therefore, rise in ambient temperature by >4.6℃ may negatively affect yield and fruit quality.