• Journal of The Geomorphological Association of Korea
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• v.18 no.1
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• pp.15-27
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• 2011

The canals of China·Northern Europe are different from those of Korea in the phases of the times and physical environment as follows. As the coefficient of river regime is high and the slopes of river is high in our country, the sediments are much deposited on the floor and river channels are meandered and the depth of water are low. So we should dredge the river floor and should construct the dams and lock gates. These will cause streams to be late and to be flooded. The rising and falling of groundwater tables may be fatal to the buildings. The ecosystem will be ruined by water pollution and rising of water levels. We are concerned about the economy of the canals, the low velocity of the canals, reduction of the transportation cost, transshipment cost and terminal cost, tourism·leisure-typed waterway and extreme cost of waterway development. It is proper for us to put in good order and control waterway simply by means of annual schedule, not to construct canal.

• Korean Journal of Community Nutrition
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• v.29 no.2
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• pp.81-96
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• 2024

Objectives: This study aimed to investigate arterial stiffness index, physical activity, and food and nutrient intake in middle-aged adults over 40 years when the incidence of cardiovascular disease begins to increase. Methods: This study included 106 subjects (48 males and 58 females) aged between 40 and 64 years. The arterial stiffness index (brachial-ankle pulse wave velocity [baPWV], and ankle-brachial index [ABI]) were measured using a blood pressure pulse wave testing device. Physical activity was assessed using the Korean version of the Global Physical Activity Questionnaire, and food and nutrient intake was calculated using the Food Frequency Questionnaire. Results: The mean age of the subjects was 54.4 years. Although the ABI of the subjects was within the normal range, they were divided into tertiles to compare physical activity and food and nutrient intake. In males, the time spent on moderate to vigorous physical activity (MVPA) was significantly higher in T3 (600.6 min/week) than in T1 (304.4 min/week). In females, the time spent in sedentary behavior was significantly lower in T3 (294.5 min/week) than in T1 (472.1 min/week). In addition, the frequency of fish consumption was significantly higher in T3 (1.27 frequency/day) than in T1 (0.64 frequency/day) in females. Polyunsaturated fatty acid (PUFA) and ω-3 fatty acid intake, adjusted for energy intake, were significantly positively correlated with ABI (r = 0.200 and r = 0.218, respectively). Conclusions: High MVPA (in males), low sedentary behavior (in females), and PUFA and ω-3 fatty acid intake through fish consumption may be associated with low peripheral artery stiffness. Therefore, arteriosclerosis can be prevented through physical activity and proper dietary therapy.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.1
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• pp.65-72
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• 2010

In this study, the performances of a medium grade IMU which is aimed for Mobile Mapping System and a low grade IMU for pedestrian navigation are analyzed through simulations under GPS signal blockage. In addition, an analysis on the accuracy improvement of barometer, electronic compass, or multi-sensor(combination of barometer and electronic compass) to correct medium grade or low grade IMU errors in the situation of GPS signal blockage is performed. With the medium grade IMU, the three dimensional positioning error from INS exceeds the demanded accuracy of 5m when the block time is over 30 seconds. When we correct IMU with barometer, compass, or multi-sensor, however, the demanded accuracy is maintained up to 60 seconds. In addition, barometer is more effective than the electronic compass when they are combined. In case of low grade IMU like MEMS IMU, the three dimensional positioning error from INS exceeds the demanded accuracy of 20m when the block time is over 15 seconds. When we correct INS with barometer, compass, or multi-sensor, however, the demanded accuracy is maintained up to 15 seconds in simulation results. On the contrary to medium grade IMU, electronic compass is more effective than the barometer in case of low velocity such as pedestrian navigation. It is expected that the analysis suggested a method to decrease position or attitude error using aided sensor integration when MMS or pedestrian navigation is operated under 1he environment of GPS signal blockage.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.475-489
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• 2010

In order to verify the enhancement of ozone and carbon monoxide (CO) during springtime in East Asia, we investigated weather conditions and data from remote sensors, air quality models, and air quality monitors. These include the geopotential height archived from the final (FNL) meteorological field, the potential vorticity and the wind velocity simulated by the Meteorological Mesoscale Model 5 (MM5), the back trajectory estimated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the total column amount of ozone and the aerosol index retrieved from the Total Ozone Mapping Spectrometer (TOMS), the total column density of CO retrieved from the Measurement of Pollution in the Troposphere (MOPITT), and the concentration of ozone and CO simulated by the Model for Ozone and Related Chemical Tracers (MOZART). In particular, the total column density of CO, which mightoriginate from the combustion of fossil fuels and the burning of biomass in China, increased in East Asia during spring 2000. In addition, the enhancement of total column amounts of ozone and CO appeared to be associated with both the upper cut-off low near 500 hPa and the frontogenesis of a surface cyclone during a weak Asian dust event. At the same time, high concentrations of ozone and CO on the Earth's surface were shown at the Seoul air quality monitoring site, located at the surface frontogenesis in Korea. It was clear that the ozone was invaded by the downward stretched vortex anomalies, which included the ozone-rich airflow, during movement and development of the cut-off low, and then there was the catalytic photochemical reaction of ozone precursors on the Earth's surface during the day. In addition, air pollutants such as CO and aerosol were tracked along both the cyclone vortex and the strong westerly as shown at the back trajectory in Seoul and Busan, respectively. Consequently, the maxima of ozone and CO between the two areas showed up differently because of the time lag between those gases, including their catalytic photochemical reactions together with the invasion from the upper troposphere, as well as the path of their transport from China during the weak Asian dust event.

• Journal of the Korean earth science society
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• v.21 no.3
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• pp.315-322
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• 2000

In this study, the data used for the models were a set of 56 geologic estimates of long-term fault slip rates. The hest models were those in which mantle drag was convergent on the Transverse Ranges in the San Andreas fault system, and faults had a low friction (${\mu}$= 0.3). It is clearly important to decide whether these cases of low strength are local anomalies or whether they are representative. Furthermore, it would be helpful to determine fault strength in as many tectonic settings as possible. Analysis of data was considered by unsuspected sources of pore pressure, or even to question the relevance of the friction law. To contribute to the solution of this problem, three attempts were tried to apply finite element method that would permit computational experiments with different hypothesized fault rheologies. The computed model has an assumed rheology and plate tectonic boundary conditions, and produces predictions of present surface velocity, strain rate, and stress. The results of model will be acceptably close to reality in its predictions of mean fault slip rates, stress directions and geodetic data. This study suggests some implications of the thermoelastic characteristics to interpret the relationship with very low strength of San Andreas fault system.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.201-211
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• 2006

55 zooplankton taxa including 35 copepoda were observed in the Uldolmok waterway during the sampling period from August 2003 to April 2004. Neritic species showed the seasonal species fluctuation, and oceanic warm-water species occurred throughout the year. The number of taxa tended to increase at the flood tide from low tide to high tide, and to decrease at the ebb tide from high tide to low tide. Therefore, species composition of zooplankton in the Uldolmok waterway seemed to be affected by the inflow of oceanic waters with oceanic species all the year round. Total abundance of zooplankton ranged from 104 (February 2004) to 2,717 indiv. $m^{-3}$ (August 2003). According to the tidal cycle, the change of total abundance was more irregular and variable in November 2003 and February 2004 than August 2003 and April 2004. In August 2003 and April 2004, total abundance was low at the strong tide, and was high at low and high tide when tidal current was weak. Average abundances of dominant species such as Paracalanus indicus, Cirripedia nauplii and Acartia hongi were on the order of twice higher at ebb tide than flood tide. However, their abundances were also subject to wide fluctuation within flood tide and ebb tide. The changes of environmental parameters such as water temperature, salinity and chlorophyll-a concentration were negligible along the tidal periods in the Uldolmok waterway. Therefore, the advection, transfer and loss of zooplankton population derived from strong tidal current and eddy formed by the local difference of tidal velocity lead temporal variation of zooplankton community more complex and variable in the Uldolmok waterway.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.766-771
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• 1989

physicochemical properties of rice starch isolated from eight varieties were examined to evaluate the rice processing suitability The amylose contents of rice starch were varied with 16.7-29.7%, and IR 30, Godael, Aguja and Lengkwang varieties showed higher amylose content than the other varieties. The water binding capacity and blue value were in the range of 87.0 103.0 and 0.178-0.305, respectively. As the amylose content increased, the amylogram pasting temperature and the break down ratio increased, while the peak viscosity did not show any significant difference. The transmittance of 0.1% starch suspension slowly increased at $50^{\circ}C$ in the low-amylose content rice group, and rapidly increased at $65^{\circ}C$ in the high-amylose content rice group, but there were no differences above $75^{\circ}C$ among varieties. Also the low-amylose rice starch showed higher values in the swelling power and solubility. The hardness of the 30% rice starch gels was low in low-amylose one. During storage at $20^{\circ}C$ for 14 days, the increment of hardness was more slow in high-amylose one. The retrogradation velocity constant of rice starch gel by Avrami equation was the highest as 0.219 in Aguja variety.

• Clinical and Experimental Reproductive Medicine
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• v.44 no.3
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• pp.132-140
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• 2017

Objective: Correlations between semen parameters and sperm DNA fragmentation index (DFI) were investigated to identify characteristics of sperm without DNA damage that could be used in selecting sperm for intracytoplasmic sperm injection (ICSI). Pregnancy outcomes were compared to determine whether in vitro fertilization (IVF) or ICSI is a better choice for patients who have sperm with a high-DFI. Methods: Semen analysis was carried out in 388 patients who visited our IVF center for the first time to investigate correlations between sperm DFI and semen parameters. In addition, 1,102 IVF cycles in 867 patients were carried out in the present study; 921 cycles in the low-DFI group (DFI < 30%) and 181 cycles in the high-DFI group ($DFI{\geq}30%$). Both the low- and high-DFI groups were subdivided into IVF and ICSI cycle groups. Results: Sperm DFI showed significant inverse correlations with sperm motility (r = -0.435, p< 0.001) and morphology (r = -0.153, p< 0.05). Sperm DFI also showed significant correlations with rapid motility (r = -0.436, p< 0.001), and the kinetic parameters of average-path velocity (r = -0.403) and linearity (r = -0.412). Although there was no significant difference in the pregnancy rates between IVF (48.6%) and ICSI (44.8%) in the low-DFI group, the pregnancy rate of ICSI cycles (44.8%, p< 0.05) was significantly higher than IVF cycles (25.0%) in the high-DFI group. No significant difference was observed in the abortion rates between the low-DFI (52 of 921, 5.6%) and high-DFI groups (7 of 181, 3.8%). Conclusion: ICSI is a better choice than IVF for improving the pregnancy outcomes of patients who have sperm with a high DFI.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.35-41
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• 2021

VWTi, which is used as a commercial catalyst in NH3-SCR, exhibits excellent denitrification performance at 300 to 400 ℃, but there is a problem that efficiency decreases at low temperatures below 300 ℃. Research on catalysts containing promoter to increase low-temperature denitrification efficiency is steadily progressing. However, research on the cause of the improvement in low-temperature denitrification efficiency of the catalyst and the catalyst properties is insufficient. In this study, it was confirmed that by adding Sb to VWTi, denitrification performance was improved by more than 10% in NH3-SCR reaction below 300 ℃. At this time, the space velocity and the size of the catalyst particles were controlled to exclude the influence of external/internal diffusion. In addition, the catalytic properties according to the presence or absence of Sb were investigated by performing BET, TEM/EDS, O2-TPD, H2-TPR and DRIFTs analysis. It was judged that the addition of Sb increased the adsorbed oxygen species on the surface of the catalyst, thereby enhancing the redox properties of the catalyst at low temperature and exhibiting excellent denitrification performance.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2315-2320
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• 2007

This paper presents an investigative study on the efficacy of a new physical water treatment (PWT) technology using an oscillating electric field to mitigate mineral fouling in heat exchangers. Parallel graphite electrode plates immersed in water were used to generate the electric field directly in water. Artificial hard water at 500 ppm hardness was used in all fouling tests. The inlet temperatures were maintained at 23.5${\pm}$0.5$^{\circ}C$ and 85${\pm}$0.5$^{\circ}C$ for cold and hot water sides, respectively. The results at a cold water-side velocity of 0.3 m/s showed a 16-60% drop in fouling resistances from the baseline test depending on the frequency of the electric field for the PWT-treated cases.