• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.330-333
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• 2009

This paper proposes a method to estimate the flow speed of pedestrians in surveillance videos. In the proposed method, the average moving speed of pedestrians is measured by estimating the size of real-world motion from the observed motion vectors. For this purpose, pixel-to-meter conversion factors are calculated from camera geometry. Also, the height information, which is missing because of camera projection, is predicted statistically from simulation experiments. Compared to the previous works for flow speed estimation, our method can be applied to various camera views because it separates scene parameters explicitly. Experiments are performed on both simulation image sequences and real video. In the experiments on simulation videos, the proposed method estimated the flow speed with average error of about 0.1m/s. The proposed method also showed a promising result for the real video.

• Advances in environmental research
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• v.5 no.4
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• pp.263-282
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• 2016

Contaminant transport in groundwater induces major threat and harmful effect on the environment; hence, the fate of the contaminant migration in groundwater is seeking a lot of attention. In this paper a two dimensional numerical flow and transport model through saturated layered soil is developed. Groundwater flow and solute transport has been simulated numerically using proposed model. The model implements the finite volume time splitting method to discretize the main equations. The performance, accuracy and efficiency of the out coming numerical models have been successfully examined by two test cases. The verification test cases consist of two-dimensional, groundwater flow and solute transport. The final purpose of this paper is to discuss and compare the shape of contaminant plume in homogeneous and heterogeneous media with different soil properties and control of solute transport using a zone for minimizing the potential of groundwater contamination; furthermore, this model leads to select the effective and optimum remedial strategies for cleaning the contaminated aquifers.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.11
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• pp.599-605
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• 2009

This paper presents a numerical evaluation of the flow rate of air conditioner outdoor unit by investigating the effects of fan location and shroud shape. To determine optimal design parameters, we investigated the exhaust flow rate by changing shroud height, fan height, fan guide height, and fan width. The 3rd order central composite design was performed to select three most important parameters affecting the exhaust flow rate. According to the result of response surface method, the exhaust flow rate of the optimum model increased by 6.25% compared to that of the base model.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.270-272
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• 2021

최근 영상신호처리에 대한 딥러닝 기술이 비약적으로 발전함에 따라 다양한 방면으로 시도되고 있다. 그 중 machine level vision 에서 인지 기능을 하는 optical flow 를 end-to-end 학습 방식으로 제시하여 고성능 결과물을 도출하는 RAFT(Recurrent All-pairs Field Transform for Optical flow, 2020)에 대해 분석하고자 한다. RAFT 는 입력된 두 이미지에 대한 4D correlation volume 을 구축하여 모든 픽셀에 대한 정보를 사용한다. 또한, recurrent neural network 에서 차용한 반복적인 연산 학습 구조를 통하여 결과물인 flow field 의 정확도를 높인다. 해당 모델은 stereo dataset 을 사용하는 다른 모델에 비해 학습 시간이 짧고 용량이 작으면서 error rate 은 낮은 모습을 보인다. 현재 많은 연구에서 optical flow 를 접목하려는 움직임을 보이고 있고 다양하게 활용될 가능성이 다분하다는 점에서 주목할 가치가 있다.

• Journal of Digital Convergence
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• v.15 no.10
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• pp.411-417
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• 2017

This experimental research explores the effect of background music of TV documentary which can be classified as channel factor in the field of media effect, on audience's recall memory, flow, arousal of interest, evaluation of documentary. Most previous researches of media effect focused on the effect of sender factor and message factor on audience's memory, understanding, acquirement of knowledge, attitude, action. However the number of researches on the effect of background music on audience's various dependent variables is extremely limited, especially it is very difficult to find studies on the effect of background music of TV documentary on audience. Therefore this research tries to find the effect of background music of TV documentary on audience's recall memory, flow, arousal of interest, evaluation. For this research of experiment, 2 groups of subjects composed of 101 university students were exposed to 2 different video clips of TV documentary, one with background music, the other without it, After this experiment, Questions which were designed to measure audience's recall memory, flow, arousal of interest, evaluation were asked and analysed. This research found that background music of TV documentary increased audience's flow, degree of interest and raised evaluation, However meaningful effect of background music on audience's recall memory was not found.

• Economic and Environmental Geology
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• v.52 no.1
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• pp.37-48
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• 2019

In geological $CO_2$ sequestration, the behavior of $CO_2$ within a reservoir can be characterized as two-phase flow in a porous media. For two phase flow, these processes include drainage, when a wetting fluid is displaced by a non-wetting fluid and imbibition, when a non-wetting fluid is displaced by a wetting fluid. In $CO_2$ sequestration, an understanding of drainage and imbibition processes and the resulting NW phase residual trapping are of critical importance to evaluate the impacts and efficiencies of these displacement process. This study aimed to observe migration and residual trapping of immiscible fluids in porous media via cyclic injection of drainage-imbibition. For this purpose, cyclic injection experiments by applying n-hexane and deionized water used as proxy fluid of $scCO_2$ and pore water were conducted in the two dimensional micromodel. The images from experiment were used to estimate the saturation and observed distribution of n-hexane and deionized water over the course drainage-imbibition cycles. Experimental results showed that n-hexane and deionized water are trapped by wettability, capillarity, dead end zone, entrapment and bypassing during $1^{st}$ drainage-imbibition cycle. Also, as cyclic injection proceeds, the flow path is simplified around the main flow path in the micromodel, and the saturation of injection fluid converges to remain constant. Experimental observation results can be used to predict the migration and distribution of $CO_2$ and pore water by reservoir environmental conditions and drainage-imbibition cycles.

• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.13-23
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• 2014

To obtain optimum filter media, configuration method and greenhouse wastewater loading in small-scale constructed wetlands (CWs) for treating greenhouse wastewater, the apparatuses were constructed with 4 kinds of combined systems such as vertical flow (VH)-Horizontal flow (HF), HF-VH, HF-VF-HF, VF-HF-HF CWs. The efficiencies of pollutants in greenhouse wastewater were investigated in various CWs under different filter media, configuration methods and agricultural water loading. Removal rates of pollutants under different filter media were in the other of coarse sand>broken stone${\fallingdotseq}$calcite${\fallingdotseq}$mixed filter media for COD, broken stone>mixed filter media>coarse sand>calcite for T-N, and calcite>mixed filter media>broken stone>coarse sand for T-P. The removal rates of pollutants in HF-VH-HF CWs at different configuration methods were higher than those in other configuration methods. The removal rates of pollutants were higher in the order of $150L\;m^{-2}day^{-1}{\fallingdotseq}300L\;m^{-2}day^{-1}$ > $600L\;m^{-2}day^{-1}$ under different greenhouse wastewater loading. Therefore, optimum configuration method was HF-VH-HF CWs, the optimum filter media was mixed filter media (coarse sand : broken stone : calcite=1 : 1 : 1), and the optimum greenhouse wastewater loading was $300L\;m^{-2}day^{-1}$ in HF-VH-HF CWs.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.137-141
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• 2002

Anabaena variabilis ATCC 29413 grew in chromium (Cr) containing Chu-10 (basal) and nitrate-supplemented media, and the growth of the organism in $100{\mu}M$ chromium was found to be 50% of that in control medium. The growth in nitrate $({NO_3}^-)$ supplemented cultures was better as compared to cultures grown in basal medium. Free cells from basal and nitrate-supplemented media removed 5.2 and 7.4 nmol of chromium $mg^{-1}$protein in 8 h, respectively, from the medium containing $30{\mu}M$ chromium. The efficiency of chromium removal increased 7-fold in imidazole buffer (0.2 M, pH 7.0). A cell density equivalent to $100{\mu}g$ protein $ml^{-1}$ was found to be optimum for maximum Cr removal. Entrapment of cells in calcium-alginate beads did not affect the rate of Cr uptake by the cells. The efficiency of the laboratory-scale continuous flow bioreactor $(12.5{\times}2cm)$ loaded with alginate-immobilized cells (10 mg protein) and fed with $30{\mu}M$ chromium solution was compared at different flow rates. The efficiency of the bioreactor varied with flow rates. In terms of percent removal of Cr from influent, a flow rate of 0.1 ml $min^{-1}$ was found to be optimum for 6 h (54% Cr removal efficiency). Maximum amount of Cr (883 nmol) was removed by the cells in 3 h at a flow rate of 0.5 ml $min^{-1}$. The potential use of A. variabilis in removing Cr from industrial effluents is discussed.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.2
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• pp.197-215
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• 2015

Modeling water flow in variably saturated, porous media is important in many branches of science and engineering. Highly nonlinear relationships between water content and hydraulic conductivity and soil-water pressure result in very steep wetting fronts causing numerical problems. These include poor efficiency when modeling water infiltration into very dry porous media, and numerical oscillation near a steep wetting front. A one-dimensional finite element formulation is developed for the numerical simulation of variably saturated flow systems. First order backward Euler implicit and second order Crank-Nicolson time discretization schemes are adopted as a solution strategy in this formulation based on Picard and Newton iterative techniques. Five examples are used to investigate the numerical performance of two approaches and the different factors are highlighted that can affect their convergence and efficiency. The first test case deals with sharp moisture front that infiltrates into the soil column. It shows the capability of providing a mass-conservative behavior. Saturated conditions are not developed in the second test case. Involving of dry initial condition and steep wetting front are the main numerical complexity of the third test example. Fourth test case is a rapid infiltration of water from the surface, followed by a period of redistribution of the water due to the dynamic boundary condition. The last one-dimensional test case involves flow into a layered soil with variable initial conditions. The numerical results indicate that the Crank-Nicolson scheme is inefficient compared to fully implicit backward Euler scheme for the layered soil problem but offers same accuracy for the other homogeneous soil cases.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.57-63
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• 2007

In this study, the cone type baffle (CTB) was developed to improve the flow distribution in an upflow bioreactor. It was composed of two different zones (anoxic and oxic) by inserting the CTB in the middle of the bioreactor. Based on the results of the dye tracer tests, hydraulic retention time (HRT) for the anoxic, oxic and total volume of the bioreactor was found to be 0.998, 1.996 and 2.994 hr, respectively. And the theoretical HRT for each volume was 1.0, 2.0 and 3.0 hr, respectively. The values of HRT obtained from the tests coincide with theoretical values. Therefore, the flow pattern for each zone inside the bioreactor, which was divided by the CTB, was dominated by complete mix flow rather than plug flow. Based on the results of the transection measurements, the DO concentration for each zone inside the bioreactor was clearly distinguished. Consequently, the CTB played an important role in the separation of anoxic and oxic zones. Also, the each pollutans were reduced gradually along the height in the oxic zone. The reason is that the biomass in the media layer (Port 4 and 5) was higher than that in the mixed liquor layer without the media (Port 2 and 3).