• Journal of Korean Society for Atmospheric Environment
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• v.22 no.4
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• pp.451-458
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• 2006

Automotive exhaust is suspected to be one of the major reasons of the rapid increase in greenhouse effect gases in ambient air. As the concerns regarding global worming were increased, the pressure on mobile source greenhouse gas (GHG) emission were also increased. Carbon Dioxides contribute over 90% of total GHG emission and the mobile source occupies about 20% of this $CO_2$ emission. In this study, in order to investigate $CO_2$ emission characteristics from gasoline and LPG passenger cars (PC), which is the most dominant vehicle type in Korea, 53 vehicles were tested on the chassis dynamometer. $CO_2$ emissions and fuel consumption efficiency were measured. The emission characteristics by fuel type, model year, mileage, vehicle speed and transmission type were also discussed. Test modes used in this study were NIER 10 modes and CVS-75 mode, which have been used for developing emission factors and testing new vehicles respectively. The results of this study showed that the main factors which have significant influences on the $CO_2$ emissions are fuel type, transmission type, displacement of vehicle and mileage. The correlation between $CO_2$ emission and FE was also determined by comparing $CO_2$ emission and fuel consumption efficiency. The overall results of this study will greatly contribute to domestic greenhouse gas emissions calculation and designing national strategies for climate change.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1183-1189
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• 2002

In order to develope the porous alumina ceramics with high strength, the pore characteristics and compressive strength were investigated in terms of relation to the conditions of spark-plasma sintering and the contents of graphite as a pore precursor. Porous alumina bodies were successfully prepared by spark-plasma sintering and burning out graphite in air. High porous bodies were fabricated by sintering at 1000${\circ}C$ for 3 min under a pressure of 30 MPa, heating rate of 80${\circ}C$/min and on-off pulse type of 12:2. For example, alumina bodies prepared by the addition of 10∼30 vol% graphite showed high porosity of 50∼57%. Also, the open porosity increased with graphite content. The relationship between pore characteristics and graphite contents could be explained by percolation model depending on cluster number and size. Porous alumina bodies prepared by the addition of 10∼30 vol% graphite showed the high compressive strength of 55∼200 MPa. This great improvement in strength was considered to be mainly due to the spark-plasma discharges and the self-heating action between particles.

• Journal of Korea Water Resources Association
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• v.42 no.11
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• pp.921-931
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• 2009

For the assessment of climate change impacts for the Byeongseong stream, CGCM 3.1 T63 is selected as future climate information. The projections come from CGCM used to simulate the GHG emission scenario known as A2. Air temperature and precipitation information from the GCM simulations are converted to regional scale data using the statistical downscaling method known as MSPG. Downscaled climate data from GCM are then used as the input data for the SWAT model to generate regional runoff and water quality estimates in the Byeongseong stream. As a result of simple sensitivity analysis, the increase of CO2 concentration leads to increase water yield through reduction of evapotranspiration and increase of soil water. Hydrologic responses to climate change are in phase with precipitation change. Climate change is expected to reduce water yields in the period of 2021-2030. In the period of 2051-2060, stream flow is expected to be reduced in spring season and increased in summer season. While soil losses are also in phase with water yields, nutrient discharges (i.e., total nitrogen) are not always in phase with precipitation change. However, it should be noted that there are a lot of uncertainties in such multiple-step analysis used to convert climate information from GCM-based future climate projections into hydrologic information.

• Journal of Cadastre & Land InformatiX
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• v.51 no.2
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• pp.83-106
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• 2021

Interests in clean fuels have been soaring because of environmental problems such as air pollution and global warming. Unlike fossil fuels, hydrogen obtains public attention as a eco-friendly energy source because it releases only water when burned. Various policy efforts have been made to establish a hydrogen based transportation network. The station that supplies hydrogen to hydrogen-powered trucks is essential for building the hydrogen based logistics system. Thus, determining the optimal location of refueling stations is an important topic in the network. Although previous studies have mostly applied optimization based methodologies, this paper adopts machine learning to review spatial attributes of candidate locations in selecting the optimal position of the refueling stations. Machine learning shows outstanding performance in various fields. However, it has not yet applied to an optimal location selection problem of hydrogen refueling stations. Therefore, several machine learning models are applied and compared in performance by setting variables relevant to the location of highway rest areas and random points on a highway. The results show that Random Forest model is superior in terms of F1-score. We believe that this work can be a starting point to utilize machine learning based methods as the preliminary review for the optimal sites of the stations before the optimization applies.

• Toxicological Research
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• v.18 no.1
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• pp.13-22
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• 2002

In Korea, 2,320 tonnes of acetanilide were mostly wed as intermediates for synthesis in phar-maceuticals or additives in synthesizing hydrogen peroxide, varnishes, polymers and rubber. Only small amount of 120 kg were wed as a stabilizer for hydrogen peroxide solution for hair colouring agents in 1998. Readily available environmental or human exposure data do not exist in Korea at the present time. However, potential human exposures from drinking water, food, ambient water and in work places are expected to be negligible because this chemical is produced in the closed system in only one company in Korea and the processing factory is equipped with local ventilation and air filtering system. Acetanilide could be distributed mainly to water based on EQC model. This substance is readily biodegradable and its bioaccumulation is low. Acute toxicity of acetanilide is low since the L $D_{50}$ of oral exposure in rats is 1,959 mg/kg bw. The chemical is not irritating to skin, but slightly irritating to the eyes of rabbits. horn repeated dose toxicity, the adverse effects in rats were red pulp hyperplasia of spleen, bone marrow hyperplasia of femur and decreased hemoglobin, hematocrit and mean corpuscular hemoglobin concentration. The LOAEL for repeated dose toxicity in rats was 22 mg/kg/day for both sexes. Acetanilide is not considered to be genotoxic. In a reproductive/developmental toxicity study, no treatment-related changes in precoital time and rate of copulation, impregnation, pregnancy were shown in all treated groups. The NOAELs for reproduction and developmental toxicity (off-spring toxicity) are considered to be 200 mg/kg bw/day and 67 mg/kg bw/day, respectively. Ecotoxicity data has been generated in a limited number of aquatic species of algae (72 hr- $E_{b}$ $C_{50}$; 13.5 mg/l), daphnid (48hr-E $C_{50}$ > 100 mg/l) and fish (Oryzias latipes, 96hr-L $C_{50}$; 100 mg/l). Form the acute toxicity values, the predicted no effect concentration (PNEC) of 0.135 mg/1 was derived win an assessment factor of 100. On the basis of these data, acetanilide was suggested as currently of low priority for further post-SIDS work in OECD.in OECD.D.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.1-10
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• 2012

Mobility and quality of service (QoS) are becoming the more important issues in wireless communications. The traditional Internet service is expanding into new access media and applications. Since wireless communication services are accompanied by frequent handovers at remote sites, scalable and fast handover has become a prerequisite for ubiquitous communication. In this paper, the differentiated service (Diffserv) model is deployed in heterogeneous proxy mobile IPv6 (PMIPv6) networks to satisfy the QoS guaranteed service and fast handover requirements. The operational procedures for QoS guaranteed global roaming are presented. In addition, QoS management and handover cost evaluation schemes based on a mobile host's movement scope are proposed. This paper analyzes the reduction in handover delay in a network-based localized mobility management framework. We propose and analyze a PMIPv6 optimized with a global mobile access gateway (G-MAG), which is a network-based entity, to further improve the handover performance in terms of handover delay while maintaining minimal signaling overhead in the air interface among converged heterogeneous wireless networks. The handover signaling procedures with host-based MIPv6 are compared with network-based proxy MIPv6 (PMIPv6) and fast PMIPv6 assisted by G-MAG to show how much handover delay reduction can be achieved. Analytical results show that the handover delay is significantly reduced.

• Journal of the Korean Geotechnical Society
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• v.20 no.1
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• pp.109-120
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• 2004

There has been outstanding research on the soil-water characteristic curves of unsaturated soils over the past several decades. Unfortunately, unsaturated soil mechanics has not been considered as an important factor in Korea. In this paper, laboratory test and numerical analysis(SoilVision Professional ver 3.04) were performed to investigate the prediction method of soil-water characteristic curve and unsaturated permeability coefficient in reclaimed ground. The pressure cell, desiccator, and tensiometor tests were conducted on three types of reclaimed soils(dredged soil, sand, weathered granite soil). Numerical analysis was executed to compare the results with the laboratory test results and also compared with the results of each prediction method. Based on the laboratory test, three different types of soils have shown different soil-water characteristic curves. The hysteresis fir these soils is clearly defined. As a result of numerical analysis, Fredlund & Xing's method and Fredlund & Wilson's model proved to worke out well for reclaimed ground soils in Korea. Also, predicting method based on the soil-water characteristic curves from the particle-size distributions is flirty reliable for estimating unsaturated permeability coefficient.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.2
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• pp.92-108
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• 2017

Present work shows a numerical method to analysis of interaction analysis between solitary wave and onshore bridge. Numerical simulation is carried out by TWOPM-3D (three-dimensional one-field model for immiscible two-phase flows), which is based on Navier-Stokes solver. To do this, the solitary wave is generated numerically in numerical wave channel, and numerical results and experimental results were compared and analyzed in order to verify the applicability of force acting on an onshore bridge. From this, we discussed precisely the characteristics of horizontal and vertical forces (uplift and downward forces) changes including water level and velocity changes due to the variation of solitary wave height, water depth, onshore bridge's location and type, and number of girder. Furthermore, It is revealed that the maximum horizontal and vertical forces acting on the girder bridge show different varying properties according to the number of girder, although each maximum force acting on the girder bridge is proportional to the increasement of incident solitary wave height, and the entrained air in the fluid flow affects the vertical force highly.

• Explosives and Blasting
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• v.40 no.3
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• pp.19-32
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• 2022

Hydrogen is a fuel having the highest energy compared with other common fuels. This means hydrogen is a clean energy source for the future. However, using hydrogen as a fuel has implication regarding carrier and storage issues, as hydrogen is highly inflammable and unstable gas susceptible to explosion. Explosions resulting from hydrogen-air mixtures have already been encountered and well documented in research experiments. However, there are still large gaps in this research field as the use of numerical tools and field experiments are required to fully understand the safety measures necessary to prevent hydrogen explosions. The purpose of this present study is to develop and simulate 3D numerical modelling of an existing hydrogen gas station in Jeonju by using handheld LiDAR and Ansys AUTODYN, as well as the processing of point cloud scans and use of cloud dataset to develop FEM 3D meshed model for the numerical simulation to predict peak-over pressures. The results show that the Lidar scanning technique combined with the ANSYS AUTODYN can help to determine the safety distance and as well as construct, simulate and predict the peak over-pressures for hydrogen refueling station explosions.

• Journal of Industrial Convergence
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• v.17 no.4
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• pp.77-86
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• 2019

The purpose of this study was to identify the effect of Home Health Nursing based Respiratory Management Program (HHNbRMP) on unmet healthcare need and healthcare resource utilizations of patients applying the home mechanical ventilator in the home with amyotrophic lateral sclerosis. The subjects of this study were 40 patients placed in an experimental group(n=19) and a control group(n=21), respectively. This HHNbRMP based on Cox's interaction model was consisted of cognitive assent (education, specialized medical care, case management), internal motivation (airway clearance, thoracic and air accumulated exercise) and psychological response (meditation & active listening). The intervention was applied to experimental group during 12 weeks. As variables was measured at baseline, twelve, twenty-four weeks and healthcare unmet need, resource utilizations (admission, out patient department, emergency room) was measured at 24 weeks. The data were analyzed by t-test, ANOVA and Repeated Measures ANCOVA. This intervention was not effective the unmet healthcare need. But the admission in to the hospital among the healthcare resource utilizations variables showed a significant difference at twenty-four weeks(t=4.17, p=.049). This results suggest that applying this program tailored to patients condition, utility of medical resource would be decreased, specially admission.