• International Journal of Highway Engineering
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• v.11 no.3
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• pp.141-149
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• 2009

Objective of this study was to characterize the particle size distribution(PSD) and quantify the pollutant concentration in highway runoff. Runoff samples during two rainfall events at four road sites in Gyunggi-Do were collected and PSD and associated pollutant distribution was quantified. Also, rainfall amount, flow rate, and other pollutants in samples were analyzed. PSDs in each sample were analyzed and compared with temporal trends of other pollutants. High partial event mean concentrations(PEMC) of particulates were observed at the beginning of runoff and rapid decrease thereafter. Other pollution parameters such as turbidity, TSS, BOD, TN, and TP also have similar temporal runoff trend with the PEMC. Especially PEMC was well correlated with total suspended solids(TSS) and turbidity. Cu, Pb, Zn had high concentration both runoff and sediment. Heavy metals in sediment were strongly bound to fine particles that have the large surface area-to-volume ratios.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.2
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• pp.78-83
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• 2019

Sounds based machine fault diagnosis recovers all the studies that aim to detect automatically abnormal sound on machines using the acoustic emission by these machines. Conventional methods that use mathematical models have been found inaccurate because of the complexity of the industry machinery systems and the obvious existence of nonlinear factors such as noises. Therefore, any fault diagnosis issue can be treated as a pattern recognition problem. We propose here an automatic fault diagnosis method of hand drills using discrete wavelet transform(DWT) and pattern recognition techniques such as artificial neural networks(ANN). We first conduct a filtering analysis based on DWT. The power spectral density(PSD) is performed on the wavelet subband except for the highest and lowest low frequency subband. The PSD of the wavelet coefficients are extracted as our features for classifier based on ANN the pattern recognition part. The results show that the proposed method can be effectively used not only to detect defects but also to various automatic diagnosis system based on sound.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.122-122
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• 2012

Geosynchronous electron flux dropouts are most likely due to fast drift loss of the particles to the magnetopause (or equivalently, the "magnetopause shadowing effect"). A possible effect related to the drift loss is the radial diffusion of PSD due to gradient of PSD set by the drift loss effect at an outer L region. This possibly implies that the drift loss can affect the flux levels even inside the trapping boundary. We recently investigated the details of such diffusion process by solving the diffusion equation with a set of initial and boundary conditions set by the drift loss. Motivated by the simulation work, we have examined observationally the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropouts. For this work, we have first identified a list of geosynchronous flux dropout events for 2007-2010 from GOES satellite electron measurements and solar wind pressures observed by ACE satellite. We have then used the electron data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measurements to investigate the particle fluxes. The five THEMIS spacecraft sufficiently cover the inner magnetospheric regions near the equatorial plane and thus provide us with data of much higher spatial resolution. In this paper, we report some case studies showing energy dependence during magnetopause shadowing effect.

• Polymer(Korea)
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• v.27 no.4
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• pp.330-339
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• 2003

Three kinds of macro-reticular bead-typed chelating resins having thiol groups were obtained from basic resins like poly(strene-co-divinylbenzene) (PSD) and poly(styrene-co-methyl methacrylate-co-divinylbenzene) (PSMD): the chelating resin (I) was prepared by chloromethylation of phenyl rings of PSD followed by thiolation using thiourea. The chelating resin (ll) was designed to provide enough space to chelate heavy metal ions; one chloromethyl group was obtained by chlorination of hydroxymethyl group provided by reduction of carboxylic ester group of PSMD and another chloromethyl group was obtained by direct chloromethylation of pendent phenyl group using chloromethyl methyl ether. Both of chloromethyl groups were thiolated by using thiourea. The chelating resin (III) was prepared by chlorosulfonation of phenyl rings of PSD followed by thiolation using sodium hydrosulfide. The adsorbtivity toward heavy metal ions was evaluated. The hydrophobic chelating resin (I) with thiol groups showed highly selective adsorption capacity f3r mercury ions. However, the chelating resin (II) with thiol groups showed mere effective adsorption capacity toward mercury ions than chelating resin (I) with thiol groups, and showed some adsorption capacity for other heavy metal ions like Cu$\^$2＋/, Pb$\^$2＋/, Cd$\^$2＋/ and Cr$\^$3＋/. On the other hand, the chelating resin (III) which have hydrophilic thiosulfonic acid groups was found to be effective adsorbents for some heavy metal ions such as Hg$\^$2＋/, Cu$\^$2＋/, Ni$\^$2＋/, Co$\^$2＋/, Cr$\^$3＋/ and especially Cd$\^$2＋/ and Pb$\^$2＋/.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.3
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• pp.177-184
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• 2008

The purpose of this study was to compare the performance characteristics of Andersen and total suspended particulate (TSP) samplers in terms of particle size distribution (PSD) and mass sampling efficiency. In the present study, two Andersen and four TSP samplers were selected and tested to quantitatively estimate human exposure to fly ash representing industrial particulate matter (PM) in a carefully controlled chamber. The PSD characteristics, a mass median aerodynamic diameter and a geometric standard deviation, were found from the sampled PM of airborne samplers in the chamber. An Andersen sampler was compared with a TSP sampler quantified by a coulter counter multisizer, as a reference sampler, to describe the correlation of mass sampling efficiencies between two types of samplers. Overall results indicate that Andersen samplers overestimated small PM due to particle bounce phenomena between impaction stages. There was reasonably good correlation ($R^2$ = 0.89 and 0.91) between the mass sampling efficiencies of Andersen and TSP samplers during the two tests. However, the lower values of slope (0.71 and 0.72) in two tests showed that the Andersen sampler underestimated PM (> AD $10.1\;{\mu}m$) with sufficient inertia due to a relatively lower Andersen inlet velocity at 0.8 m/s comparing with the operating air velocity at 2.1 m/s in the sampling zone of a chamber.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.21 no.2
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• pp.67-71
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• 2015

Shock and vibration inputs are transmitted from the transporting vehicle through the packaging to the fruit during the parcel delivery service. The vibration causes sustained bouncing of fruits against each other and the container wall. The steady state vibration input may cause serous fruit injury, and the damage is particularly severe if the fruits are bounced at its resonance frequency. The determination of the resonance frequencies of the fruits and vegetables may help the packaging designer to determine the proper packaging system providing adequate protection for the fruits, and to understand the complex interaction between the components of the fruits when they relate to expected transportation vibration inputs. To analyze the vibration properties of the apples for optimum packaging design during transportation for parcel delivery service, random vibration tests were carried out. In the random vibration test, the resonance frequency and PSD of the apples in packaging system for parcel delivery service in the test were in the range of 13 to 99 Hz and $0.0143{\sim}0.0923G^2/Hz$.

• The Korean Journal of Rehabilitation Nursing
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• v.18 no.2
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• pp.128-134
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• 2015

Purpose: The purpose of this study was to compare the effects of hand massage provided with different intervals and periods on pain and sleep disturbance after orthopedic surgery. Methods: A non-equivalent control group pretest- posttest design was used. The subjects were admitted in an orthopedic hospital to get a surgery. They were divided into three groups. Group I (n=30) had hand massage every day. Group II (n=30) had hand massage every other day. Control group (n=31) had usual care. Data of all three groups were collected on the day before operation, POD (postoperative day) 6 and POD12. Hand massage was given for 2 and half minutes per hand. Results: Pain on POD6 of experimental group II was reduced more than those of control group. Pains on POD12 of both experimental groups were reduced more than those of control group. On POD6, only perceived sleep disturbance (PSD) was significantly different among groups. On POD12, PSD, total sleeping time, and sleep efficiency were more improved in the experimental groups. Conclusion: Hand massage was effective on the reduction of pain and sleep disturbance after orthopedic surgery. Applying hand massage on alternate day was effective enough. Also the effects were more obvious after 12 days.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.679-690
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• 1996

Acrylic copolymer was synthesized from 2-dimethylaminoethyl methacrylate and alkylmethacrylate containing long chain hydrocarbon group. To facilitate emulsification in water, acrylic copolymer was treated with acetic acid, and therefore acetated acrylic copolymer was produced. Acetated acrylic copolymer was perfectly emulsified in water and showed increased emulsion stability. Polymer as a cement dispersion agent(PDCM-PSD) was prepared by blending the newly synthesized acetates acrylic copolymer with sodium gluconate, oleic acid, and triethanolamine. The applicability of the blended polymer was examined, and it was found that the effects of dispersion and water-proof(0.3~0.5) were excellent.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.83-89
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• 2010

This paper presents the impacts of Ultra Wide-Band(UWB) sensor using frequency of 4.5 GHz on Broadband Wireless communication system which uses frequency of 4.5 GHz. The Minimum Coupling Loss (MCL) method and Spectrum Engineering Advanced Monte Carlo Analysis Tool (SEAMCAT) is used to evaluate the interference effects of UWB sensor on Broadband Wireless communication system, respectively. The minimum protection distance between single UWB sensor and mobile station of Broadband Wireless communication system should be more than 1.2 m to guarantee the co-existence. In case of multiple UWB sensors, UWB transmitting PSD of around -68.5 dBm/MHz below should be required to guarantee interference probability of 5% below for mobile station of Broadband Wireless communication system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1138-1147
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• 2012

In this paper, an efficient power control based MF-TDMA resource allocation scheme is proposed for next generation military satellite communication systems. The proposed scheme has the flexibility is used to support heterogeneous terminals with differ in transmission capabilities. The method can be divided into two parts : burst size calculation and burst structure determination. At first, we estimate the link budget taken into account a dynamic satellite link state variation. Then, applicable ACM level and burst size is chosen. In burst structure determination phase, we reorganize the burst structure in time-frequency domain by controlling limited power, bandwidth, time resources. In particular, we compensate the power spectral density among different terminals to integrate them in same transponder, Furthermore, we increase the packing efficiency by controlling the ACM level of the burst in applicable power spectral density range. Simulation results show that the method increase the spectral efficiency and burst packing efficiency. In addition, slot allocation rejection ratio is successfully reduced.