• Journal of Electrochemical Science and Technology
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• v.2 no.1
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• pp.51-56
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• 2011

We develop a new nonwoven composite separator for a safer lithium-ion battery, which is based on coating of silica ($SiO_2$) colloidal particles/styrene-butadiene rubber (SBR) binder to a poly(ethylene terephthalate) (PET) nonwoven support. The $SiO_2$ particles are interconnected by the SBR binder and closely packed in the nonwoven composite separator, which thus allows for the development of unusual porous structure, i.e. highly-connected interstitial voids formed between the $SiO_2$ particles. The PET nonwoven serves as a mechanical support that contributes to suppressing thermal shrinkage of the nonwoven composite separator. The $SiO_2$/SBR content in the nonwoven composite separators plays an important role in determining their separator properties. Porous structure, air permeability, and electrolyte wettability of the nonwoven composite separators, in comparison to a commercialized polyethylene (PE) separator, are elucidated as a function of the $SiO_2$/SBR content. Based on this understanding of the nonwoven composite separators, the effect of $SiO_2$/SBR content on the electrochemical performances such as self-discharge, discharge capacity, and discharge C-rate capability of cells assembled with the nonwoven composite separators is investigated.

• Ocean Systems Engineering
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• v.5 no.3
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• pp.181-198
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• 2015

An OSV (Offshore Support Vessel) is being used to install a structure which is laid on its deck or an adjacent transport barge by lifting off the structure with its own crane, lifting in the air, crossing splash zone, deeply submerging, and lastly landing it. There are some major considerations during these operations. Especially, when lifting off the structure, if operating conditions such as ocean environmental loads and lifting off velocity are not suitable, the collision can be occurred due to the relative motion between the structure and the OSV or the transport barge. To solve this problem, this study performs the physics-based simulation of the lifting off step while the OSV installs the structure. The simulation includes the calculation of dynamic responses of the OSV and the structure, including the collision detection between the transport barge and the structure. To check the applicability of the physics-based simulation, it is applied to a problem of the lifting off step by varying the ocean environmental loads and the lifting off velocity. As a result, it is confirmed that the operability of the lifting off step are affected by the conditions.

• Electronics and Telecommunications Trends
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• v.36 no.4
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• pp.92-102
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• 2021

Outdoor sports activities have been restricted by serious air pollution, such as fine dust and yellow dust, and abnormal meteorological change, such as heatwave and heavy snow. These environmental problems have rapidly increased the demand for indoor sports activities. Virtual sports, such as virtual golf, virtual baseball, virtual soccer, etc., allow playing various sports games without going outdoors. Indoor sports industries and markets have seen rapid growth since the advent of virtual sports. Most virtual sports platforms use screen-based virtual reality techniques, which are why they are called screen sports. However, these platforms cannot support various sports games, especially virtual match games, such as squash, boxing, and so on, because existing screen-based virtual reality sports techniques use real balls and players. This article presents screen-based haptic-augmented reality technologies for a new virtual sports platform. The new platform does not use real balls and players to solve the limitations of previous platforms. Here, various technologies, including human motion tracking, human action recognition, haptic feedback, screen-based augmented-reality systems, and augmented-reality sports content, are unified for the new virtual sports platform. From these haptic-augmented reality technologies, the proposed platform supports sports games, including indoor virtual matches, that existing virtual sports platforms cannot support.

• Korean Journal of Remote Sensing
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• v.36 no.6_3
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• pp.1711-1720
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• 2020

Particulate matter (PM) that has been artificially generated during the recent of rapid industrialization and urbanization moves and disperses according to weather conditions, and adversely affects the human skin and respiratory systems. The purpose of this study is to predict the PM10 concentration in Seoul using meteorological factors as input dataset for multiple linear regression (MLR), support vector machine (SVM), and random forest (RF) models, and compared and evaluated the performance of the models. First, the PM10 concentration data obtained at 39 air quality monitoring sites (AQMS) in Seoul were divided into training and validation dataset (8:2 ratio). The nine meteorological factors (mean, maximum, and minimum temperature, precipitation, average and maximum wind speed, wind direction, yellow dust, and relative humidity), obtained by the automatic weather system (AWS), were composed to input dataset of models. The coefficients of determination (R2) between the observed PM10 concentration and that predicted by the MLR, SVM, and RF models was 0.260, 0.772, and 0.793, respectively, and the RF model best predicted the PM10 concentration. Among the AQMS used for model validation, Gwanak-gu and Gangnam-daero AQMS are relatively close to AWS, and the SVM and RF models were highly accurate according to the model validations. The Jongno-gu AQMS is relatively far from the AWS, but since PM10 concentration for the two adjacent AQMS were used for model training, both models presented high accuracy. By contrast, Yongsan-gu AQMS was relatively far from AQMS and AWS, both models performed poorly.

• Journal of the Korean earth science society
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• v.29 no.5
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• pp.428-436
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• 2008

This study observed the upper tropospheric ozone enhancement in the northern Atlantic for the Aerosols99 campaign in January-February 1999. To find the origin of this air, we have analyzed the horizontal and vertical fields of Isentropic Potential Vorticity (IPV) and Relative Humidity (RH). The arch-shaped IPV is greater than 1.5 pvus indicating stratospheric air stretches equatorward. These arch-shaped regions are connected with regions of RH less than 20%. The vertical fields of IPV and RH show the folding layer penetrating into the upper troposphere. These features support the idea that the upper tropospheric ozone enhancement originated from the stratosphere. Additionally, we have investigated the climatological frequency of stratospheric intrusion over the tropical north Atlantic using IPV and RH. The total frequency between the equator and $30^{\circ}N$ over the tropical north Atlantic exhibits a maximum in northern winter. It suggests that the stratospheric intrusion plays an important role in enhancing ozone in the upper troposphere over the tropical north Atlantic in winter and early spring. Although the tropospheric ozone residual method assumed zonally invariant stratospheric ozone, stratospheric zonal ozone variance could be caused by stratospheric intrusions. This implies that stratospheric intrusion influences ozone variance over the Atlantic in boreal winter and spring, and the intrusion is a possible source for the tropical north Atlantic paradox.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.3
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• pp.9-16
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• 2003

In support of remote sensing applications for monitoring processes of the Earth system, research was conducted to analyze the basic spectral response related to background soil and vegetation cover characteristics in the visible and reflective infrared wavelengths. Surface samples of seven stations were examined. Five soils were from land-field and two soils from tideland areas. The vegetation cover experiment was conducted on seven soil samples with known natural moisture content (%) by weight. To study the effect of vegetation cover, spectral measurements were taken on five or six vegetation cover treatments of the seven soils with 3 replications in air dry conditions. For collecting RS base data, used spectro-radiometer that measures reflection characteristics between 300~1,100nm was used and measured the reflection of vegetation from bean leaves. The relationships were evaluated for both a general soil line and for the individual lines of five soils, under air-dried condition as well as different vegetation cover ratio, through the determination of the line parameters. As vegetation cover ratio in bean leaves increases, features of soil reflectance decrease and those of plant reflectance become more and more apparent. In proportion to vegetation cover rate, near-infrared reflectance increased and visible reflectance decreased. Analysis results are compared to commonly used vegetation indices(RVI and NDVI ).

• Tunnel and Underground Space
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• v.10 no.2
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• pp.249-256
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• 2000

According to the industrial restructuring in the late 1980's, most domestic mines have been shutdown or suspended in operation. The closed underground excavation caverns remain in their abandoned conditions, and they will potentially cause environmental hazards. To evaluate the feasibility of the utilization of the abandoned caverns, the foreign crises were studied. As a result, we proposed several possible examples including underground storage cavern fur food products, underground compressed air energy system(CAES), and underground repository (or incineration plant) of industrial wastes. Among them, the underground waste repositories are most probable to be seen in Korea in the near future. For this, the study in rock engineering aspects should be conducted, which will include the establishment of support system and safety measure of the abandoned underground excavation caverns.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.2
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• pp.263-276
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• 2004

According to the annual emission estimates of U.S.A., fugitive dust, the particulate matter entrained in the ambient air which is caused from man-made or natural activities such as movement of soil, vehicles, equipments and windblown dust, contributes 90% of PM$_{10}$ emission. In spite of an importance of fugitive dust emission in PM$_{10}$ estimation, it is excluded in the national emission inventory of Korea so far. In this paper, an emission inventory of fugitive dust for each region and in major cities throughout the country, which is the first time in Korea these values have been compiled, is presented. Sources of fugitive dust emission have been classified into paved/unpaved roads, construction operations, agricultural operations, and natural sources. The emission factors of the existing fugitive dust emission were reassessed in a way that significantly improved the reliability of the estimated result. The Korea's first national emission inventory of fugitive dust by administrative districts proposed in this paper would provide scientific reference data for establishing an reduction strategy of PM$_{10}$ and preparing effective control measures, and would contribute to academic achievement in the atmospheric environments field and the establishment of CAPSS (Clean Air Policy Support System).stem).

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.4
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• pp.39-47
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• 1994

This research focuses on producing a cheap polymer, and also experiments for marking with the high strength polymer concrete structures. At present only a few tests on shear behavior in polymer reinforced concrete beams(PRC) have been reported. In the current experiments, the reinforced concrete beams with polymer fraction are investigated. The beams in this study are supported by conventional stirrups at appropriate intervals and they are designed to take static loads. The strength of beams are measured and the behavior of beams under each loading are oh served in order to determine some advantages of adding polymer to reinforced concrete beams. The static testing data consist of load, displacement, and strain at specified reinforcement locations, and the support displacement In the static tests, it has been observed that the beams fail in the same way as RC. However, it is observed to he rather weak in impact, hut it can he said that its increase of strength and excellency of repairing are verified. Consequently this work strongly suggests that the steam-curing or the air-curing or the air-curing must be performed to increase the strength.

• Carbon letters
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• v.13 no.2
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• pp.99-108
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• 2012

The sol-gel technique has been studied to fabricate a homogeneous Fe-Mo/MgO catalyst. Ambient effects (air, Ar, and $H_2$) on thermal decomposition of the citrate precursor have been systematically investigated to fabricate an Fe-Mo/MgO catalyst. Severe agglomeration of metal catalyst was observed under thermal decomposition of citrate precursor in air atmosphere. Ar/$H_2$ atmosphere effectively restricted agglomeration of bimetallic catalyst and formation of highly-dispersed Fe-Mo/MgO catalyst with high specific surface-area due to the formation of Fe-Mo nanoclusters within MgO support. High-quality thin-multiwalled carbon nanotubes (t-MWCNTs) with uniform diameters were achieved on a large scale by catalytic decomposition of methane over Fe-Mo/MgO catalyst prepared under Ar-atmosphere. The produced t-MWCNTs had outer diameters in the range of 4-8 nm (average diameter ~6.6 nm) and wall numbers in the range of 4-7 graphenes. The as-synthesized t-MWCNTs showed product yields over 450% relative to the utilized Fe-Mo/MgO catalyst, and indicated a purity of about 85%.