• 대기
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• 제23권3호
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• pp.321-329
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• 2013

This study examines the effect of aerosols on the vertical invigoration of continental stratiform clouds, using a dataset of Atmospheric Radiation Measurement (ARM) Intensive Operational Period (IOP, March 2000) at the Southern Great Plains (SGP) site. To provide further support to our observation-based findings, the weather research and forecasting (WRF) sensitivity simulations with changing cloud condensation nuclei (CCN) concentrations have been carried out for the golden episode over SGP. First, cross correlation between observed aerosol scattering coefficient and cloud liquid water path (LWP) with a 160-minutes lag is the highest of r = 0.83 for the selected episode, which may be attributable to cloud vertical invigoration induced by an increase in aerosol loading. Modeled cloud fractions in a control run are well matched with the observation in the perspective of cloud morphology and lasting period. It is also found through a simple sensitivity with a change in CCN that aerosol invigoration (AIV) effect on stratiform cloud organization is attributable to a change in the cloud microphysics as well as dynamics such as the corresponding modification of cloud number concentrations, drop size, and latent heating rate, etc. This study suggests a possible cloud vertical invigoration even in the continental stratiform clouds due to aerosol enhancement in spite of a limited analysis based on a few observed continental cloud cases.

• 한국항행학회논문지
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• 제14권2호
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• pp.266-271
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• 2010

본 연구에서는 스토리지 성능평가에 필요한 대표적인 성능지표로 IOPS 및 MB/s 을 결정하고 이를 평가하기 위한 지침을 개발하였다. 현재, 벤더 중립적인 스토리지 평가기준이 없기 때문에 스토리지 성능평가나 스토리지 자원 규모를 설계하는데 어려움이 있었다. 연구결과, OLTP 응용에 활용되는 스토리지는 IOPS를 성능지표로 하고 측정을 위한 블록크기는 4KB, 8KB, 16KB, 읽기대쓰기 비율은 7:3으로 측정하는 것을 제안하였다. 한편, 백업, VOD, LFP(Large File Processing) 과 같은 대용량 처리 응용에 사용되는 스토리지는 MB/s를 성능지표로 하고, 측정을 위한 블록크기는 64KB, 256KB, 1,024KB 으로 하고 읽기대 쓰기 비율은 1:0 으로 하는 것을 제안하였다. 끝으로 개발된 평가지침을 이용한 측정결과보고서 양식을 개발하였으며 측정도구로는 플랫홈에 비종속적인 Vdvench 측정도구를 제안하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.49-52
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• 2007

This study uses empirical method to estimate absorption coefficient of colored dissolved organic matter $(a_{dom})$ from GOCI satellite data with the relationship between band ratio of remote sensing reflectance $(R_{rs})$ and $a_{dom}$. For development of $a_{dom}$ estimation algorithm, the used data is in-situ data about ocean optical properties in the around seawater area of the Korean Peninsula during 1998 - 2005. The relationship of $R_{rs}$(412)/$R_{rs}$(555), $R_{rs}$(443)/$R_{rs}$(555), $R_{rs}$(490)/$R_{rs}$(555), $R_{rs}$(510)/$R_{rs}$(555) and $a_{dom}$(412) showed $R^2$ values of 0.707, 0.707, 0.597 and 0.552, respectively. The spectrum of $a_{dom}({\lambda})$ is shape of exponential function $a_{dom}({\lambda})$ value decreases with increasing wavelength. For estimation of $a_{dom}$ from satellite data, we developed an algorithm from the relationship of $a_{dom}$(412) and $R_{rs}$(412)/$R_{rs}$(555). This algorithm was employed on SeaWiFS imagery to estimate $R_{rs}$(412) in the South Sea, East Sea, Yellow Sea and northern East China Sea areas. Also, SeaDAS-derived $a_{dg}$(412) from same SeaWiFS imagery, These $a_{dg}$(412) was then compared with in-situ and empirical-algorithm-derived $a_{dom}$(412), but these values were different. We think two points that such different values are caused by discrepancy related to failure of standard atmospheric correction scheme, the other are caused by error related to definition of $a_{dom}$(412) and $a_{dg}$(412).

• 대기
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• 제21권2호
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• pp.185-196
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• 2011

The performance assessment in radiosonde observation on the special observation program (ProbeX-2009) is performed and the characteristics of precipitation using Auto Weather System (AWS) and radiosonde data in 2009 at the Ulleungdo are investigated. The launching time, observation time, and maximum altitude of radiosonde are satisfied with the regulation from Korea Meteorological Administration (KMA) and World Meteorological Organization (WMO) but the duration of observational time of radiosonde is much shorter than that of the ProbeX-2007 because the altitude of launching site is higher than others in 2007. From the analysis of trajectories of radiosonde, most radiosondes at the Ulleungdo tend to move into the east because the westerly prevail at the middle latitude. However, when the Okhotsk high is expanded to the Korean peninsula and the north-westerly winds strengthen over the East Sea as the subtropical high is retreated, radiosonde tends to move into the south-west and south-east, respectively. Maximum distance appears at the end of observation level before May but the level of maximum distance is changed into 100 hPa after June because the prevailing wind direction is reversed from westerly to easterly at the stratosphere during summer time. The condition of precipitation was more correlated with the dynamic instability except Changma season. Precipitation in 2009 at the Ulleungdo occurred under the marine climate so that total precipitation amounts and precipitation intensity were increased and intensified during nighttime. The local environment favorable for the precipitation during nighttime was while the wind speed at the surface and the inflow from the shoreline were strengthened. Precipitation events also affected by synoptic condition but the localized effect induced by topography was more strengthened at the northern part of Ulleungdo.

• 대한한의학회지
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• 제37권2호
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• pp.53-61
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• 2016

Objectives: Considering high prevalence of myopia in Asian countries, social cost paid for myopia may gradually increase in Korea. However, studies for developing myopia treatment are deficient. The study was to evaluate whether the periocular acupressure with a medical massager is effective for suppressing myopia progression. Methods: This study was an investigator-sponsored, prospective, open-labeled, and superiority pre and post single-armed study. 14 myopia children aged 7-12 years wore a medical massager for 15 minutes to stimulate periocular acupoints. For 24 weeks, the participants used the device twice a day. Based on prior studies, the refraction change of naturally proceeded myopia was set as -0.38 D. The axial length change of naturally proceeded myopia was set as 0.228 mm. To assess the safety, we performed vital sign check, physical examination, visual acuity test, slit lamp examination, IOP measurement, and fundus examination. Results: The refraction and axial length of the participants increased. For 24 weeks, the change in refraction was -0.38 D at the right eye and -0.40 D at the left. The change in axial length was 0.21 mm at the right and 0.22 mm at the left. In the safety assessment, any adverse event did not occur. Conclusions: There was no significant difference between the control group and the intervention group. The effect of growth may have more contributed to our result than that of acupressure. Based on our result, a full-scale study will not be conducted.

• 정보과학회 논문지
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• 제43권1호
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• pp.27-33
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• 2016

오늘날 가상화 기술은 가장 유용하게 사용되는 컴퓨팅 기술 중 하나이며 모든 컴퓨팅 환경에서 널리 활용되고 있다. 그러나 가상화 환경의 I/O 계층들은 호스트 머신의 I/O 동작 방식을 인지하지 못하도록 설계되어 있기 때문에 I/O 확장성 문제는 여전히 해결해야 할 문제로 남아 있다. 특히, 다중 큐 SSD가 보조 기억 장치로 사용될 경우, 증가한 잠금 경쟁과 제한된 I/O 병렬화 문제로 가상 머신은 다중 큐 SSD의 공인된 성능을 활용하지 못하는 문제가 발생한다. 이러한 성능 문제를 해결하기 위해 본 논문에서는 가상 CPU마다 전용 큐와 I/O 스레드를 할당하는 새로운 기법을 제안한다. 제안 기법은 성능 저하의 주요한 원인 중 하나인 잠금 경쟁을 효율적으로 분산시키고 또 다른 원인인 Virtio-blk-data-plane의 병렬화 문제를 해소한다. 제안 기법을 평가한 결과 최신 QEMU 보다 IOPS가 최대 155% 향상되는 것을 확인하였다.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제2권2호
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• pp.123-130
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• 2013

최근 유전체 데이터의 급격한 증가로 인해 이를 처리하기 위한 고성능 컴퓨팅 시스템이 필요로 하게 되었으며 대량의 유전체 데이터를 저장 관리할 수 있는 고성능 저장 시스템이 필요하게 되었다. 본 논문에서는 대략 5억 개 정도의 시퀀스 리드 데이터를 분석하는 유전체 분석 파이프라인의 I/O워크로드를 수집 및 분석하였다. 실험은 86시간 동안 수행되었다. 1031.7 GByte 크기의 630개 파일이 생성되었으며 91.4 GByte 크기의 535개의 파일이 삭제되었다. 전체 654개의 파일 중 0.3%인 2개의 파일이 전체 접근 빈도의 80%를 차지하여 전체 파일 중 일부분의 파일이 대부분의 I/O를 발생시킨다는 것을 알 수 있다. 요청 크기 단위로는 읽기에서 주로 512 KByte 크기 이상의 요청이 발생했고 쓰기에서 주로 1 MByte 크기 이상의 요청이 발생했다. 파일이 열려있는 동안의 접근 패턴은 읽기와 쓰기 연산에서 각각 임의와 순차패턴을 보였다. IOPS와 대역폭은 각 단계마다 고유한 패턴을 보였다.

• 대기
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• 제31권4호
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• pp.377-394
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• 2021

The recent largest forest fire in the Yeongdong region, Goseung/Okgae fires of 2019 occurred during YangGang wind event. The wind can be locally gusty and extremely dry, particularly in the complex terrain of Yeongdong. These winds can cause and/or rapidly spread wildfires, the threat of which is serious during the dry spring season. This study examines the spatial variability of the surface wind and its coupling with the upper atmospheric wind using the data during the IOP of the Gangwon Yeongdong Wind Experiments (G-WEX) conducted in 2020 and the data during YangGang wind event on 4~5 April 2019. In the case of IOPs, strong wind at the surface with a constant wind direction appears in the mountain area, and weak wind with large variability in wind direction appears from foothill to the coast in the vicinity of Gangneung region. However, in the 2019 event, strong wind at the surface with a constant wind direction appears in the entire region from the mountain to the coast, even with the stronger wind in the coast than in some part of the mountain area. The characteristics of the upper atmospheric wind related with the spatial distribution of surface wind show that during IOPs of G-WEX, a strong downdraft exists near the mountaintop in the level of about 1 to 4 km. However, in the 2019 event a strong downdraft is reinforced, when its location moves toward the coast and descends close to the ground. These downdrafts are generated by the breaking of mountain waves.

• 무역학회지
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• 제47권4호
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• pp.215-231
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• 2022

Analysis and forecasting of the Baltic Capsize Index (BCI) is important for managing an entity's losses and risks from the uncertainty and volatility of the fast-changing maritime transport market in the future. This study conducted volatility transition analysis through the GARCH model, using BCI which is highly related to steel raw materials. As for the data, 2,385 monthly data were used from March 1999 to March 2021. In this study, after basic statistical analysis, unit root and cointegration test, the GARCH, EGARCH, and DCC-GARCH models were used for volatility transition analysis. As the results of GARCH and EGARCH model, we confirmed that all variables had no autocorrelation between the standardized residuals for error terms and the square of residuals, that the variability of all variables at this time was likely to persist in the future, and that the variability of the time-series error term impact according to Iron ore trade (IoT). In addition, through the EGARCH model, the magnitude convenience of all variables except the Iron ore price (IOP) and Capesize bulk fleet (BCF) variables was greater than the positive value (+). As a result of analyzing the DCC-GARCH (1,1) model, partial linear combinations were confirmed over the entire period. Estimating the effect of variability transition on BCF and C5 with statistically significant linear combinations with BCI confirmed that the impact of BCF on BCI was greater than the impact of BCI itself.

• 대한안과학회지
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• 제59권12호
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• pp.1142-1151
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• 2018

목적: 삼출 나이관련황반변성에 대한 유리체내 항혈관내피성장인자 주사 치료의 장기 결과를 알아보고자 한다. 대상과 방법: 삼출 나이관련황반변성 진단 후 treat-and-extend 또는 as needed 방법으로 7년 이상 유리체내 항혈관내피성장인자 주사 치료를 시행 받은 환자들에 대한 후향적 의무기록 분석을 시행하였다. 주사 횟수, 최대교정시력 및 중심망막두께 등을 평가하였으며, 장기간 주사 치료에 따른 부작용 여부를 같이 조사하였다. 결과: 총 196명의 196안을 분석하였다(평균 나이 $68.6{\pm}9.6$세, 여성 77명). 평균 $78.0{\pm}16.5$개월 경과관찰하였고, 해당 기간 동안 평균 $17.3{\pm}13.5$회의 유리체내주사가 시행되었다. 치료 전 측정한 최대교정시력은 평균 $0.75{\pm}0.58$ logMAR, 중심망막두께는 $349.7{\pm}152.6{\mu}m$였고, 6개월째 두 수치 모두 최대 호전을 보였으나(p<0.05), 이후 점차 악화 소견을 보이며 7년째 최대교정시력 $0.91{\pm}0.78$ logMAR, 중심망막두께 $284.5{\pm}105.8{\mu}m$로 확인되었다. 주사 후 7년째 시력은 치료 전 시력과 강한 양의 상관관계를 보였다. 장기간 주사 동안 총 11회의 안압상승 및 3회의 전방 내 염증 증가 소견이 있었으나 안내염 등의 심각한 부작용은 관찰되지 않았다. 결론: 삼출 나이관련황반변성에서 유리체내 항혈관내피성장인자 주사 치료 후 초기 6개월간의 최대 시력 호전이 있었으나 5년 이상 경과 시 지속적인 시력 저하를 막지 못하였다. 진단 당시 시력이 장기 시력예후와 관련된 중요 예측 인자로 판단되며 적극적인 유리체 내주사 치료를 통해 더 나은 장기 시력 결과를 기대해 볼 수 있다.