• Journal of Environmental Science International
• /
• v.10 no.1
• /
• pp.1-8
• /
• 2001

This study was carried out estimating the dry deposition flux of $SO_2$at eight urban areas in Korea during one year of 1996. To calculate the deposition flux, deposition velocities were calculated by turbulence parameters estimated from routine meteorological data. Also, hourly averaged $SO_2$concentrations which calculated from air pollution monitoring data of each city were used. The dry deposition velocities were mostly higher in the coastal areas than the other areas, which would be caused by relatively strong wind. And, they were high in the daytime because of turbulence activities. The deposition flux of $SO_2$is mainly related to the atmospheric concentration. The annual average $SO_2$concentration and the deposition flux were 22.62ppb and 1510.52g/$\textrm{km}^2$/hr at Pusan respectively. Also, the flux was higher in winter than other season, which was a significant contribution of exhausted fuel for heating. While the deposition velocity was high to 0.688cm/sec at Yosu in case of strong wind and small cloud cover, the deposition flux was high to 1597.4g/$\textrm{km}^2$/hr at Pusan in case of weak wind and small cloud cover.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.301-310
• /
• 2006

A series of laboratory tests was carried out for analyzing compaction characteristics of hydraulic fill soils(or hydraulically filled soils). Hydraulic fill soils were settled down by the weight of soil particle itself in water and consolidated by the extraction of water from the soil structures. Water content and dry unit weight were observed as the depth of sedimentation and consolidation soil. It was found from the result that the optimum water content $(W_{cpt})$ of the maximum unit weight$(\gamma_{dmax})$ is higher than that of laboratory compaction test(KS F 2312 A method). It was due to difference in compaction energy and compaction effect between two methods. And the maximum dry unit of hydraulic fill soil is smaller than that of laboratory compaction test. Especially in terms of compaction effect, the maximum relative compaction degrees$(R_{cmax})$ of Seamangum dredged sand, river sand and mixed sand, half and half of dredged and river sands, were 85%, 91% and 86%, respectively. It means that the compaction effect can be $85\sim91%$ of the maximum unit weight in laboratory compaction test.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.12
• /
• pp.1259-1263
• /
• 2004

In this paper, the optimum design of ultrasonic dry cleaning head was investigated. The transducer instead of mechanical dynamic structure was used to generate ultrasonic wave and the horn-shape amplifier was utilized to solve the energy decaying problem of ultrasonic wave with propagating it through the media. The analyses of ultrasonic wave and a fluid for the selected structure of a cleaning head were carried out using SYSNOISE and ANSYS simulators, respectively. Based on simulator results, the distance between a horn and the substrate of 4 mm and the horn diameter of 10 mm were determined to maximize the energy of ultrasonic waves. The cooling structure was also considered to reduce the heat from the transducer and the horn. The equivalent circuit for the fabricated horn was deduced from HP4194A impedance/gain/phase analyzer and the frequency of an ultrasonic wave of 20.25 kHz was confirmed using the parameters of the equivalent circuit.

• ALGAE
• /
• v.22 no.3
• /
• pp.201-207
• /
• 2007

For getting primary cue of restoration, the algal flora and intertidal community structure of Deokjeokdo, Yeonpyeongdo and Ganghwado were investigated for from February to November 2006. The total of 28 species, including five Chlorophytes, five Phaeophytes, 17 Rhodophytes and one sea grass were identified. The occurrence of species according to sampling site was 22 species in Deokjeokdo, seven species in Yeonpyeongdo and four species in Ganghwado. Among them Gloiopeltis furcata, Ulva pertusa and Sargassum horneri in Deokjeokdo, Scytosiphon lomentaria in Yeonpyeongdo, Enteromorpha prolifera in Ganghwado were ominants. The algal zonation of intertidal zone was figured out by Gloiopeltis furcata, Caulacanthus okamurae – Corallina pilulifera – Ulva pertusa, Ahnfeltiopsis flabelliformis, Sargassum horneri, Undaria pinnatifida in Deokjeokdo, Bangia atropurpurea – Scytosiphon lomentaria – Ahnfeltiopsis flablleiformis in Yeonpyeongdo from upper to lower zone and Enteromorpha prolifera, Enteromorpha linza – Sargassum thunbergii, Myelophycus simplex in Ganghwado from middle to lower zone. The average of biomass was measured as 80.6 g dry wt. m–2 in Deokjeokdo, 32.2 g dry wt. m–2 in Yeonpyeongdo and less than 1 g dry wt. m–2 in Ganghwado.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.7 s.196
• /
• pp.106-111
• /
• 2007

In this paper, the transient brake time was studied on the van type vehicle with accelerometer. Experiments were carried out on the asphalt(new and polished), unpacked road(earth and gravel) and on wet or dry road conditions. The transient brake time is not effected bzy the vehicle speed. The transient brake time is about 0.41$\sim$0.43second on the asphalt road surface and the error range is within 0.1$\sim$0.16second. For the asphalt road condition, the transient brake time is not effected by both new asphalt road surface and the polished asphalt road surface. With compared by dry and wet road surface condition, the transient brake time of wet condition is longer than dry road condition and compared with unpacked road condition and packed road condition, unpacked road condition is shorter than packed road condition. It is considered that the transient brake time is effected by the road surface fraction coefficient. In other words, the transients brake time increases as friction coefficient decreases.

• Journal of the korean society of oceanography
• /
• v.37 no.2
• /
• pp.82-89
• /
• 2002

Butyltins (BTs) were measured in 2 species of shellfish and 16 species of fish collected along the Korean coast. Tributyltin (TBT) was detected in the mussels and oysters of sentinel organisms (20 to 940 ng Sn/g dry wt), indicating widespread contamination of TBT in the Korean coast. The elevated concentrations of TBT in the shellfish found in the sites near harbors or shipyards suggested that antifouling paints are probable major sources of butyltins in these areas. The TBT compound was detected in 12 out of 16 fish samples. The concentrations of TBT in fish muscles wee between 7 and 151 ng Sn/g dry wt, while the level in whole body of anchovy was very high (793 ng Sn/g dry wt). Exposure doses to Korean people via consumption of these marine products wee evaluated. The results suggested that the environmental levels of TBT were below the level of concern.

• Journal of the Korean Society of Tobacco Science
• /
• v.5 no.2
• /
• pp.17-24
• /
• 1983

Varietal difference of crop stand, growth of each organs and the factors of dry matter Production at different growth stage of three local tobacco varieties (Hyangcho, Youngwolyub and Yonginyub) were investigated in 1979 and 1980. Varietal variation of total standing crops was clear from 45th day after transplanting to end maximum value of photosyntheticinon-photosynthetic organs was Hyangcho: 1.9, Youngwolyub; 1.6, Yonginyub; 2.3. Maximum value of L/S and T/R ratio was clear from 35th day after transplanting to 45th day. RGR, NAR and CGR were in decreasing order of Yonginyub) Youngwolyub)Hyangcho through out growth stage, LAR and SLA were in decreasing from early growth stage to last growth stage, LAI was obtained to maximum value in the large growth state and LAI was increasing order of during the total growth period that it was Hyangcho is 7.6. Youngwolyub is 9.1 and Yonginyub is 8.7, SLA was Hyangcho;$2.088\textrm{cm}^2$/g/leaf, Youngwclyub;$2.173\textrm{cm}^2$/g/leaf and Yonginyub;$2.020\textrm{cm}^2$/g/leaf, respectively.

• Smart Structures and Systems
• /
• v.19 no.5
• /
• pp.553-565
• /
• 2017

Structural modeling of unencapsulated ionic polymer metal composite (u-IPMC) actuators that are used for flapping the insect scale-flapping wing of micro air vehicles (FMAV) in dry environmental conditions is carried out. Structural modeling for optimization of design parameters for retention of water, maximize actuation performance and to study the influence of water activity on the actuation characteristics of u-IPMC is explored for use in FMAV. The influence of equivalent weight of Nafion polymer, cations, concentration of cations, pre-treatment procedures on retention of water of u-IPMCs and on actuation parameters, flapping angle, flexural stiffness and actuation displacement are investigated. IPMC designed with Nafion having equivalent weight 900-1100, pre-heated at $30^{\circ}C$ and with sodium as the cations is promising for optimum retention of water and actuation performance. The actuation parameters while in operation in dry and humid environment with varying water activity can be tuned to desirable frequency, deflection, flap angle and flexural stiffness by changing the water activity and operational temperature of the environment.

• Computers and Concrete
• /
• v.21 no.5
• /
• pp.485-493
• /
• 2018

Statistical analysis has found useful application in the design of experiments (DOE) especially optimization of concrete ingredients however, to be able to apply the concept properly using computer aided applications there has to be an upper and lower limits of responses fed to the system. In this study, the production of high-performance steel fiber concrete (HPSFC) at five different fiber addition levels by volume with two aspect ratios of 60 and 83 were studied under two curing methods completely dry cured (DC) and moist cured (MC) conditions. In other words, this study was carried out for those limits based on material properties available in North Cyprus. Specimens utilized were cubes 100 mm size casted and cured for 28 days and tested for compressive strength. Minitab 18 statistical software was utilized for the analysis of results at a 5 per cent level of significance. Experimentally, it was observed that, there was fluctuation in compressive strength results for the two aspect ratios and curing regimes. On the other hand P-value hypothesis evaluation of the response showed that at the stated level of significance, there was a statistically significant difference between dry and moist curing conditions. Upper and lower limit values were proposed for the response to be utilized in DOE for future studies based on these material properties. It was also suggested that for a narrow confidence interval and accuracy of the system, future study should increase the sample size.

• Journal of ILASS-Korea
• /
• v.14 no.3
• /
• pp.131-138
• /
• 2009

In the present study, spread-recoil behavior of a drop of shear-thinning liquid (xanthan solution) on a dry wall (polished stainless-steel plate) was examined and compared with that of Newtonian liquid (glycerin solution). Nine different kinds of xanthan and glycerin solutions were tested, including three pairs of xanthan and glycerin solutions, each having the same viscosity in low shear rate region ($10^{-2}-10^0\;l/s$). The drop behavior was visualized and recorded using a CCD camera. The maximum diameter and the spreading velocity of the xanthan drops turned out to be significantly larger and the time to reach their final shape was much shorter compared to the cases with the glycerin solutions, due to the smaller viscous dissipation resulted from lower viscosity in the higher shear rate region (>$10^0\;l/s$). As a result, the maximum diameters were measured to be larger than the predicted values based on the model proposed for Newtonian liquids, and the deviation was more pronounced with the solution with the larger viscosity variation. Consequently, viscosity variation with the shear rate was found to be a dominant factor governing the spread-recoil behavior of shear-thinning drops.