• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.453-454
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• 2003

현재 우리 나라에서는 수송분야 중 항공기, 선박, 건설기계 농기계 등과 같은 비토로 이동오염원에 의한 대기오염에 대해서는 연구가 부진한 실정이다. 2001년 김포공항을 이용하던 국제선 항공기는 인천국제공항의 개항에 따라 이전하게 되었다. 이에 따라 항공기 이착륙에 의한 대기오염 배출이 상당 부분 김포지역에서 인천 영종도지역으로 이전되었을 것으로 예상된다. 본 연구에서는 미국 FAA에서 공항의 대기오염배출량 산출 및 주변지역의 농도예측에 선정모델로 추천하고 있는 EDMS (Emission and Dispersion Modeling System)을 사용하여 국제선 이전에 따른 김포공항 주변지역의 NOx 오염도 변화를 예측하고 이를 실측치와 비교 평가하고자 한다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.51-52
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• 2003

A numerical study on PM using a dispersion and deposition model which can analyze for both quantify and quality would not only offer us to understand our environment more easily, but also make it easy that we can make a plan in order to prevent air pollution. The U.S. EPA has proposed the CALPUFF modeling system as a guideline model for regulatory applications involving long-range transport and on a case-by-case basis for near-field applications where. non- steady- state effects which consider situations such as spatial variability in the meteorological fields, calm winds, fumigations, re-circulation or stagnation, and terrain or coastal effects may be important. (omitted)

• Journal of Communications and Networks
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• v.5 no.3
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• pp.230-239
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• 2003

In this paper, we propose a framework to study how to route packets efficiently in multipath communication networks. Two traffic congestion control techniques, namely, flow assignment and packet scheduling, have been investigated. The flow assignment mechanism defines an optimal splitting of data traffic on multiple disjoint paths. The resequencing delay and the usage of the resequencing buffer can be reduced significantly by properly scheduling the sending order of all packets, say, according to their expected arrival times at the destination. To illustrate our model, and without loss of generality, Gaussian distributed end-to-end path delays are used. Our analytical results show that the techniques are very effective in reducing the average end-to-end path delay, the average packet resequencing delay, and the average resequencing buffer occupancy for various path configurations. These promising results can form a basis for designing future adaptive multipath protocols.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.413-414
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• 1999

이미 선진국에서는 악취오염의 문제가 대기오염 문제로 관심의 대상이 되고 있다. 일반적으로 악취는 황화수소(H$_2$S), mercaptan류, 아민류 및 기타 자극성 있는 기체상 물질이 사람의 냄새 감각을 자극하여 불쾌감과 혐오감을 주는 냄새로서 정의되어 있다. 본 연구의 목적은 울산의 쓰레기ㆍ폐기물 매립장(삼산/성암/온산)중에서 성암 쓰레기 매립장의 악취 오염도를 분산모델링을 이용한 방법론 개발과 인근 주민의 피해를 예측함과 아울러 차후의 쓰레기ㆍ폐기물 매립장 건설에 있어서 악취오염 제어 및 관리대책을 수립하는데 참고 자료로 활용하고자 한다.(중략)

• ETRI Journal
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• v.38 no.6
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• pp.1031-1041
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• 2016

This paper presents millimeter-wave (mmWave) propagation characteristics and channel model parameters including path loss, delay, and angular properties based on 28 GHz and 38 GHz field measurement data. We conducted measurement campaigns in both outdoor and indoor at the best potential hotspots. In particular, the model parameters are compared to sub-6 GHz parameters, and system design issues are considered for mmWave 5G Giga communications. For path loss modeling, we derived parameters for both the close-in free space model and the alpha-beta-gamma model. For multipath models, we extracted delay and angular dispersion characteristics including clustering results.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.22-28
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• 2003

Predictions of the fuel spray dispersion and mixing processes are very important to improve the fuel consumption and exhaust emissions in GDI engines. Numerical and experimental analysis of the sprays with a swirl injector have been conducted. A numerical analysis is carried out using KIVA-II code with modified spray models. Experimental measurements are performed to show the global spray images and the local images near nozzle tip using laser sheet visualization technique. Computed and measured spray characteristics such as spray width, tip penetration are compared, and good agreements can be achieved. The spray head vortex is stronger as the injection pressure increases, but numerical calculations cannot show the head vortex properly.

• Advances in concrete construction
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• v.7 no.3
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• pp.183-189
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• 2019

In this study, it has been tried to prepare an analytical fragility curves for isolated straight continues highway bridges by considering different spectral intensity measures. A three-span concrete isolated bridge has been selected and the seismic performance of the bridge has been improved by Lead Rubber Bearing (LRB). Incremental Dynamic Analysis (IDA) is applied to the bridge in longitudinal direction. A suite of 14 earthquake ground motions from medium to sever motions are scaled and used for nonlinear time history analysis. Fragility function considers the relationship of earthquake intensity measures (IM) and probability of exceeding certain Damage State (DS). A full three dimensional finite element model of the isolated bridge has been developed and analyzed. A wide range of different intensity measures are selected and the optimal intensity measure which has the less dispersion is proposed.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.51.2-51.2
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• 2020

Luminous blue variables (LBVs) are massive evolved stars that show unpredictable photometric and spectral variation. It is generally assumed that they undergo one or more of large eruptions. We have obtained high dispersion NIR spectra of several LBVs with Immersion GRating INfrared Spectrometer (IGRINS). One notable feature in their IGRINS spectra is the existence of broad lines (~ a few hundred km/s) with unusual boxy profile. They are fluorescent lines of Fe II by Lyman α photons in the stellar wind. However, modeling of these lines with radiative transfer code CMFGEN predicts much weaker line strength. We propose that incorporating broadening of Lyman α line by scattering processes in dense wind can enhance the Fe II fluorescent lines. We further discuss how these Fe II fluorescent lines can be used to characterize massive LBV wind.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.2
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• pp.138-149
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• 2000

Various modeling techniques for ultrasonic wave propagation and scattering problems in finite solid media are presented. Elastodynamic boundary value problems in inhomogeneous multi-layered plate-like structures are set up for modal analysis of guided wave propagation and numerically solved to obtain dispersion curves which show propagation characteristics of guided waves. As a powerful modeling tool to overcome such numerical difficulties in wave scattering problems as the geometrical complexity and mode conversion, the Boundary Element Method(BEM) is introduced and is combined with the normal mode expansion technique to develop the hybrid BEM, an efficient technique for modeling multi mode conversion of guided wave scattering problems. Time dependent wave forms are obtained through the inverse Fourier transformation of the numerical solutions in the frequency domain. 3D BEM program development is underway to model more practical ultrasonic wave signals. Some encouraging numerical results have recently been obtained in comparison with the analytical solutions for wave propagation in a bar subjected to time harmonic longitudinal excitation. It is expected that the presented modeling techniques for elastic wave propagation and scattering can be applied to establish quantitative nondestructive evaluation techniques in various ways.

• Journal of the Korean Institute of Gas
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• v.18 no.3
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• pp.67-74
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• 2014

Buried natural gas pipelines in densely populated urban areas have serious hazards of property damages and casualties generated by release, dispersion, fire and explosion of gas caused by outside or inside failures. So as to prevent any accident in advance, managers implement danger management based on quantitative risk analysis. In order to evaluate quantitative risk about buried natural gas pipelines, we need calculation for radiant heat and pressure wave caused by calculation for release rate of chemical material, dispersion analysis, fire or explosion modeling through consequence analysis in priority, in this paper, we carry out calculation for release rate of pressured natural gas, radiant heat of fireball based in accident scenario of actual "San Bruno" buried high pressured pipelines through models which CCPS, TNO provide and compare with an actual damage result.