• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.31.4-32
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• 2008

The microwave instruments are used many areas of the space remote sensing and space science applications. The imaging radar of synthetic aperture radar (SAR) is well known microwave radar sensor for earth surface and ocean research. Unlike radar, microwave radiometer is passive instrument and it measures the emission energy of target, i.e. brightness temperature BT, from earth surface and atmosphere. From measured BT, the geophysical data like cloud liquid water, water vapor, sea surface temperature, surface permittivity can be retrieved. In this paper, the radiometer characteristics, system configuration and principle of BT measurement are described. Also the radiometer instruments TRMM, GPM, SMOS for earth climate, and ocean salinity research are introduce. As first korean microwave payload on STSAT-2, the DREAM (Dual-channels Radiometer for Earth and Atmosphere Monitoring) is described the mission, system configuration and operation plan for life time of two years. The main issues of DREAM unlike other spaceborne radiometers, will be addressed. The calibration is the one of main issues of DREAM mission and how it contribute on the space borne radiometer. In conclusion, the radiometer instrument to space science application will be considered.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_1
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• pp.29-33
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• 2001

A numerical simulation was carried out to investigate the mechanism of snowfall around the Seoul region during a cold air-outbreak in the winter season. A particular case was selected for this study(Dec. 19, 1999). The inflow directions of the synoptic flow in the upper and lower levels were westerly and north-westerly, respectively. Plus, there was a deep trough and thermal ridge at a level of 500/700/850 hPa over the Bal-Hae region, in the northern part of the Korean peninsula. According to the model results, snowfall occurred around the Seoul region with the simultaneous existence of a strong static instability in the lower atmosphere, northerly or westerly dry air advection, and strong thermal advection toward the Seoul region. There was a strong convergence thereby indicating the existence of convective rolls in the clouds. The main energy source of convection over the Yellow sea was a sensible heat flux. The main moisture source was convection. Radiative cooling in the cloud layer intensified the static instability in the lower atmosphere.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.87.2-87.2
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• 2012

H${\alpha}$ transient bright kernels may be an important diagnostic of energy conversion processes occurring in the choromosphere during flares. We observed an H${\alpha}$ kernel that occurred in AR 11263 in associated with a small flare on 2011 Autust 5th using the Fast Imaging Solar Spectrograph installed at the 1.6m New Solar Telescope of Big Bear Solar Observatory. We find that both the H${\alpha}$ line and the CaII 8542${\AA}$ line appear in emission, with a red asymmetry in that they display red wings of enhanced emission. The red asymmetry shows 5-30 km/s downward motion for 8 minutes. We determine some physical parameters by adopting the Cloud mode and discuss the physical meaning of these results.

• Journal of the Korean Institute of Gas
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• v.13 no.3
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• pp.43-48
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• 2009

The energetic and environmental problems have been getting serious after the revolution of modern industry. Therefore, demand of gas as an eco-friendly energy source is increasing. With the demand of gas, the use of gas is also increased, so injury and loss of life by the fire have been increasing every year. Hence the influence on flame caused by Vapor Cloud Explosion in enclosure of experimental booth was calculated by using the API regulations. And the accident damage was estimated by applying the influence on the adjacent structures and people into the PROBIT model. According to the probit analysis, the spot which is 5meter away from the flame has nearly 100% of the damage probability by the first-degree burn, 27.8% of the damage probability by the second-degree burn and 14.5% of the death probability by the fire.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.376-379
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• 2016

최근 대규모 사용자를 대상으로 하는 응용 서비스에서 생체인증의 도입이 증가함에 따라, 생체인증을 수행하는 기반 시스템이 요구하는 연산 자원과 저장 능력이 높아지고 있다. 그러나 기존의 연구에서는 이러한 요구사항에 대하여 시스템의 정량적 확대만을 고려하고 있어 많은 컴퓨팅 비용과 에너지 소모를 야기한다. 따라서 본 연구에서는 대규모 사용자를 대상으로 하는 인증 시스템에서 매칭작업에 대한 연산량 최소화와 에너지 사용면에서의 효율성을 위하여 클라우드 기반의 통합인증 시스템을 설계하고 이를 효율적으로 운용하는 방법을 제시한다. 연구의 결과는 인증 서비스의 운용비용 감소와 탄소배출 감소를 이루어 생체인증 관련 산업발전에 기여할 것으로 기대된다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.131-131
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• 2011

태양광 및 태양열 설비의 효율적인 관리를 위해서는 관련 일사정보가 사전정보로 제공되어 시스템 운용을 위한 입력인자로 활용되어야 한다. 특히 전력그리드에 연계되어 설비가 활용된다고 하면, 그 에너지 공급이 불규칙적인 신재생에너지원의 특성으로 인해 에너지 공급량의 예측이 선행되어 기존의 전력공급체계가 이를 지원할 수 있는 모델과 시스템이 구비되어야 한다. 기존의 다양한 연구들이 한정된 국소지점에 대해 다양한 예측기법을 적용하여 평가를 실시하였지만, 장기간의 결과 축적이 이루어지지 못해 그 신뢰성 확보에 어려움을 겪고 있다. 본 연구에서는 현재 한국에너지기술연구원에서 관리되는 일사정보를 활용하여 청명한 날의 표준 일사 데이터베이스를 생성하고, 기상청에서 RSS(Rich Site Summary) 형태로 지원하는 운량정보를 이용하여 3시간 이상의 미래정보를 계속적으로 산출할 수 있는 시스템을 제작하고자 하였다.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.72.4-73
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• 2016

For the development of magneto rotational instability, which drives mass accretion in protoplanetary disks, sufficient ionization degree is needed. Cosmic rays are believed to be one of the dominant ionization sources for protoplanetary disk gas. In previous studies, ionization rates are computed by considering the effect of attenuation of the cosmic ray (CR) intensity as a function of column density in an unmagnetized cloud. However, in reality particles should sweep up larger column density to reach at the midplane of disk due to their gyromotion. In this study, we investigate the propagation of CR protons in a protoplanetary disk by solving transport and energy loss equations. We discuss the change in CR intensity due to magnetic field in a protoplanetary disk.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.36.3-37
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• 2018

By utilizing large-scale graph analytic tools in the modern Big Data platform, Apache Spark, we investigate the topological structures of five different multiverses produced by cosmological n-body simulations with various cosmological initial conditions: (1) one standard universe, (2) two different dark energy states, and (3) two different dark matter densities. For the Big Data calculations, we use a custom build of stand-alone Spark cluster at KIAS and Dataproc Compute Engine in Google Cloud Platform with the sample sizes ranging from 7 millions to 200 millions. Among many graph statistics, we find that three simple graph measurements, denoted by (1) $n_\k$, (2) $\tau_\Delta$, and (3) $n_{S\ge5}$, can efficiently discern different topology in discrete point distributions. We denote this set of three graph diagnostics by kT5+. These kT5+ statistics provide a quick look of various orders of n-points correlation functions in a computationally cheap way: (1) $n = 2$ by $n_k$, (2) $n = 3$ by $\tau_\Delta$, and (3) $n \ge 5$ by $n_{S\ge5}$.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.247-253
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• 2021

Electrocoalescence is an active technique in petroleum industry, formation of raindrop in cloud, and digital microfluidics. In the present work, electrocoalescence of two droplets under the constant electric potential in air was studied. Through this experiment, we found that the electrocoalescence process could be divided three phases; deformation, formation of liquid bridge, and merging. And the condition for formation of liquid bridge between two droplets was obtained. For the connection of experimental result in constant potential condition with general case in constant charge condition, relationship of charge and potential difference was deduced by numerical computation. In high electric potential case, flat interfaces after recoiling were observed. It was interpreted through a numerical simulation of electric field.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.450-470
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• 2023

Traditional cloud computing faces some challenges such as huge energy consumption, network delay and single point of failure. Edge computing is a typical distributed processing platform which includes multiple edge servers closer to the users, thus is more robust and can provide real-time computing services. Although outsourcing data to edge servers can bring great convenience, it also brings serious security threats. In order to provide image retrieval while ensuring users' data privacy, a privacy preserving image retrieval scheme in edge environment is proposed. Considering the distributed characteristics of edge computing environment and the requirement for lightweight computing, we present a privacy-preserving image retrieval scheme in edge computing environment, which two or more "honest but curious" servers retrieve the image quickly and accurately without divulging the image content. Compared with other traditional schemes, the scheme consumes less computing resources and has higher computing efficiency, which is more suitable for resource-constrained edge computing environment. Experimental results show the algorithm has high security, retrieval accuracy and efficiency.