• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.341-350
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• 2011

A simplified analytical study for micro-sized single metal particle combustion in air was conducted in the present study. The metal particle combustion consists of two distinct reaction regimes, ignition and quasi-steady burning, and the thermo-fluidic phenomena in each stage are formulated by virtue of the conservation and transport equations. When particle temperature reaches to 1200 K, ended an ignition stage and was converted at quasi-steady combustion stage. Effects of Initial particle size, convection, ambient pressure and temperature are examined and addressed with validation.

• Nuclear Engineering and Technology
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• v.17 no.1
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• pp.8-15
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• 1985

A model for thermal interactions of debris/water with gas flow from within and below debris bed was presented for severe accident analysis in LWR. The consumption of steam, production of hydrogen in the debris bed, generation of gases from below debris bed and generation of chemical heat are included in the conservation equations. The model has been incorporated in the MARCH code to estimate the gas production due to both metal/oxidation and hot debris/concrete interaction. The results indicate that the hydrogen source can potentially give a significant impact on the containment pressure transient and the conductive heat loss to concrete and the convective gas cooling in the debris bed have a small effect on the debris bed coolability. However, the reheating and melting of the debris particles could be delayed by the interaction of debris with concrete.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.93-95
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• 2014

In this paper, we proposed efficient forwarding path computing method using Context-Awareness Mobility Prediction Model. Context-Awareness Mobility Prediction Model is storing and classifying node's previous velocity and direction according to time in the hierarchical cluster structure. To overcome environment which node-to-node connection is broken off easily, the proposed algorithm calculate the connectivity formed matrix structure by comparing predicted velocity and direction, and use masking operation for selecting relay moving to destination. The proposed algorithm identified to show short delay by utilizing forwarding path which is continue node-to-node connection in the unstable situation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.01a
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• pp.107-108
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• 2023

기업 및 공공기관의 클라우드 서비스 도입이 확산되면서 업무 시스템에 대한 보안 요구사항이 변화하고 있다. 기존에는 보호해야 할 정보자산이 물리적으로 외부와 분리된 내부 공간에 집중되었다면 클라우드 환경에서는 자산의 분포 범위가 넓어지면서 내부와 외부의 경계가 모호해진다. 따라서 경계 기반의 전통적인 보안 방식은 클라우드 기반 업무환경에 적합하지 않으며 정보 서비스를 이용하는 전 주기에서 암묵적인 신뢰를 배제하고 지속적으로 검증을 수행하는 제로 트러스트 기반의 업무 시스템 운영이 필요하다. 본 논문에서는 스토리지 클라우드 서비스인 아마존 웹 서비스 S3(Simple Storage Service)에 대하여 제로 트러스트 모델을 설계하고, 직접 서비스를 운영하며 제안된 제로 트러스트 모델의 안전성을 검증한다. 제로 트러스트 모델은 스토리지에 접근하는 사용자에 대한 인증 및 식별 기술, 스토리지 암호화 기술, 암호화 키 관리 기술을 활용하여 설계하였으며 제로 트러스트 기술 적용 시, 스토리지 보안성이 향상되는 것을 실제 서비스 운영을 통한 실험을 통해 확인하였다.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11
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• pp.3490-3499
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• 2000

There are two approaches, HA(Home Agent)-based and FA(Froegn Agent)-based mulicasting in mobile computing environments based on mobile IP. If we consider efficiency of routing and bandwidth the FA-based model is better than the HA-based model. But in the case of a MH(Mobile Host) moves frequently it shows bad connection durability because of join and graph delays. To overcome this and to support effective mobile multicasting we propose an extended FA-based multicast routing. In our model previous FA for wards multicast packets to MH. while new FA processes a jion request from MH. That is in general case our model supports FA-based multicasting for efficiency but it provides unicast-based mulicasting for connection durability when MH moves to new FN(Roreign Network). To evaluate our model, we analyze connecction durability, bandwidth, overheads and routing sosts in many situations and compare with previous works.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.4
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• pp.59-71
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• 2001

The Current CORBA shows some limitations for its successful deployment in real time system applications. Recently, OMG adopted Real-Time CORBA specification, which is defined as an extension to CORBA. The goal of the Real-Time CORBA is to provide a standard for CORBA ORB implementations that support 'end to end predictability'. In order to support 'end-to-end predictability', Real Time CORBA specifies many components such as priority model, communication protocol configuration, thread management, and etc. Among them, 'priority model' is the most important mechanism for avoiding or bounding priority inversion in CORBA invocations. In this paper, we present our efforts on a design ,and implementation of the Priority Model in Real-Time CORBA specification. The implementation is done as an extension of omniORB2(v.3.0.0), a popular open source non real time ORB. Experiment results demonstrate that our priority model implementation shows better performance and predictability than the non real-time ORB.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.87-95
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• 1999

We propose a simulation model of 3-dimensional MPEG data over Asynchronous transfer Mode(ATM) networks. The model is based on a slice level and is named to Projected Vector Autoregressive(PVAR) model. The PVAR model is modeled using the Autoregressive(AR) model in order to meet the autocorrelation condition and fit the histogram, and maps real data by a projection function. For the projection function, we use the Cumulative Distribution Probability Function (CDPF), and the procedure is performed at each slice level. Our proposed model shows good performance in meeting the autocorrelation condition and fitting the histogram, and is found important in analyzing the performance of networks. In addiotion, we apply a smoothing method by which a periodic mean value. In general. the Quality of Service(QoS) depends on the Cell Loss Rate(CLR), which is related to the cell loss and a maximum delay in a buffer. Hence the proposed smoothing method can be used to improve the QoS.

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.28-38
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• 2004

This study presents the result of uncertainty and sensitivity analysis of a pharmacokinetic model which describes the distribution and removal of benzene at each organ when an indivisual inhales indoor contaminated air with benzene originated from groundwater. The pharmacokinetic model simulates the distribution of benzene deposited in organs of human body through inhalation of contaminated indoor air as well as degradation-metabolism in liver. This study focused on the uncertainty problem induced from the use of the single values for blood flow, partition coefficient, degradation constant, volume, etc. of each organ which was due to a lack of knowledge about these parameters or their measurements. To solve this problem, uncertainty analysis on the pharmacokinetic model was conducted simultaneously which would help understanding the risk assessment associated with VOCs.

• 한국해양학회지
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• v.28 no.2
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• pp.86-100
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• 1993

Three-dimensional baroclinic hydrodynamic model, BACHOM-3, is developed using ADI finite difference scheme. The model is applied to a uni-nodal standing wave in a rectagular basin. The model results for the surface elevation and velocities coincide with the analytical results. To verify the field applicability of the model and to investigate the flow patterns of the Suyoung Bay in Pusan, Korea, the model is applied to the bay. The numerically predicted velocity predicted velocity fields during spring tide at normal river flow are compared with field measurements, the comparisons show good agreement. A clockwise residual circulations at the first level (depth = 0∼2m) and the second level (depth=2∼5 m) of the central part of the bay occur, and the ebb flow is stronger than the flood flow. Computed velocity fields show that the phase difference of velocities between the surface layer and bottom layer occurs and the phase lag increases with height from the bottom. Then, the model is applied successfully for the computation of flow fields considering flood river flow and wind effects. When the wind is blowing toward the land from the sea, the flow patterns at the surface layer correspond with the wind direction, but the flow patterns at the near solid boundary of the lower layer show opposite currents to the wind direction.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.5
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• pp.459-466
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• 2012

The ionospheric delay is the largest error source in GPS positioning after the SA effect has been turned off. The ionospheric error can be easily removed by using ionospheric-free combinations but it is only restricted for dual-frequency receivers. Therefore, in this study, the regional ionospheric grid model was developed for single-frequency receivers. The developed model was compared with GIM to validate its accuracy. As a result, it yielded RMSE of 3.8 TECU for 10 days. And L1 medium- and long-range relative positioning was performed to evaluate positioning accuracy improvements. The positioning accuracy was improved by 46.7% compared with that without any correction of ionosphere and troposphere and was improved by 14.5% compared with that only tropospheric correction.