• Journal of Environmental Science International
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• v.17 no.9
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• pp.1053-1068
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• 2008

This study aims to produce fundamental database for Environment Impact Assessment by monitoring vertical structure of the atmosphere due to the mountain valley wind in spring season. For this, we observed surface and upper meteorological elements in Sangin-dong, Daegu using the rawinsonde and automatic weather system(AWS). In Sangin-dong, the weather condition was largely affected by mountains when compared to city center. The air temperature was low during the night time and day break, and similar to that of city center during the day time. Relative humidity also showed similar trend; high during the night time and day break and similar to that of city center during the day time. Solar radiation was higher than the city, and the daily maximum temperature was observed later than the city. The synoptic wind during the measurement period was west wind. But during the day time, the west wind was joined by the prevailing wind to become stronger than the night time. During the night time and daybreak, the impact of mountain wind lowered the overall temperature, showing strong geographical influence. The vertical structure of the atmosphere in Dalbi valley, Sangin-dong had a sharp change in air temperature, relative humidity, potential temperature and equivalent potential temperature when measured at the upper part of the mixing layer height. The mixing depth was formed at maximum 1896m above the ground, and in the night time, the inversion layer was formed by radiational cooling and cold mountain wind.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.144-151
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• 2017

In this paper, the antenna for parking management using wireless communication in outdoor parking environment was proposed. The proposed antenna was miniaturized by using parasitic element to reduce the size of the radiating element of the basic ${\lambda}/2$ microstrip antenna. The dimensions of the proposed antenna are $35mm{\times}35mm{\times}20.1mm$ that is 98.7% smaller than $309.1mm(0.46{\lambda}){\times}296.1mm(0.441{\lambda}){\times}20.1mm(0.029{\lambda})$ of the basic ${\lambda}/2$ microstrip antenna. The electrical characteristics of the antenna are 1.1 dBi at the center frequency of 447 MHz, an omni-directional radiation pattern on the E-plane, and $87.5^{\circ}$ of HPBW on the H-plane. The miniaturized ${\lambda}/4$ folded microstrip antenna using parasitic element has proved to be easy to mount on the wireless repeater, the sensor node installed on the ground, and the strop bar in the outdoor parking environment.

• Journal of Life Science
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• v.20 no.2
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• pp.314-320
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• 2010

As the nature of triathlons is competition in three successive sports, triathletes experience elevated levels of stress on the body that are absent in single-sport athletic events, and consequently there are more potential medical problems to prepare for. Triathletes can also experience problems such as hypothermia, heat illness, excessive exposure to ultraviolet radiation, musculoskeletal injuries and trauma, immunosuppression, and haemolysis. Depending on the potentiality of such above-listed problems occurring in any given race, race organizers will prepare preventative measures and treatments accordingly. Olympic distance is not the only triathlon racing distance. Sprints, which are normally around half the Olympic distance, are common distances, as well as Long (2 km swim, 80 km bike, 20 km run), Ironman (3.8 km swim, 180 km bike, 42 km run), and ultra-distance events varying in length. Races of longer duration normally result in a higher percentage of athletes experiencing the above-mentioned medical problems, as well as inducing additional health risks such as hyponatraemia. Minimizing the occurrences of serious health issues is possible through the following means: carefully preparing for the probable race-day weather conditions; proper management and organization of the race; preparing an extensive water-safety and ground-course safety plan; distributing necessary nutrition along the course; and stressing the importance for athletes to have proper knowledge concerning race nutrition, biomechanical technique, physical preparation, and utilization of safe equipment. While risks of competing in triathlon are many, the instances of such medical problems are not excessive, and the triathlon has a reputation of being a reasonably safe sport as long as athletes with high risk take added precautions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.3
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• pp.50-56
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• 2010

In this paper, compact broad-band antenna using circular spiral slot and CPW (coplanar waveguide) feed is proposed. The proposed antenna is designed on the same plane of the substrate by using CPW fed structure, archimediean spiral slot structure. So it was achieved both the size of compact antenna and the broad band. A archimediean spiral slot structure is introduced for resonance of medium band operation. The distances of a CPW feeder line and a ground plane are modified for impedance matching and lower/higher band operation. The proposed antenna has a compact size ($8mm\;{\times}\;13mm$) and it is etched on the FR-4 (relative dielectric constant 4.4, thickness 0.8mm) dielectric substrate. The simulated impedance bandwidth (VSWR $\leq$ 2) and maximum gain of the proposed antenna are 5.98GHz (4.1GHz ~ 10.08GHz) and 3.97dBi, respectively. The measured impedance bandwidth (VSWR $\leq$ 2) and maximum gain of the proposed antenna are 6.02GHz (4.48GHz ~ 10.5GHz) and 2.68dBi, respectively. The simulation and measured result shows good impedance matching and radiation pattern over the interesting frequency bands. It can be applied to antenna of broad-band wireless communication system.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.316-316
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• 2017

The objective of this study is to estimate quantitatively soil salinity and soil loss at upland soils in agriculture land region in Saemangeum reclaimed land on the south Korea coasts. Soil loss and soil salinity are the most critical problem at reclaimed tidal saline soil in Korea. The several thematic maps of research area such as land cover map, topographic and soil maps, together with tabular precipitation data used for soil erosion and soil salinity calculation. Meteorological data were measured directly as air temperature, wind speed, solar radiation, and precipitation. The experiment was conducted 2% sloped lysimeter ($5.0m{\times}20.0m$) with 14 treatments and it were separated by low salinity division (LSD) and high salinity division (HSD) install. The cation content in ground water increased during time course, but in the case of land surface water the content was variable, and $K^+$ was lower than that of $Na^+$ and $Mg^{2+}$. At the LSD under rainproof condition, the salinity was directly proportional to soil water content, but at the HSD the tendency was no reversed. In condition of rainproof, the amount of soil salinity was higher at the HSD than at the LSD. Positive correlation was obtained between the soil water content and available phosphorous content at the rainfall division, but there was no significance at the surface soil of the rainproof division. Sodium adsorption ratio and anion contents in soil were repressed in the order of vinyl-mulching > non-mulching > bare field. According to the result of analyzing soil loss, soil loss occurred in a vinyl-mulching, a non-mulching and a bare field in size order, and also approximately 11.2 ton/ha soil loss happened on the reclaimed land area. The average soil loss amount by the unit area takes place in a non-mulching and bare field a lot. Our results indicate that soluble salt control and soil erosion are critical at reclaimed tidal saline soil and the results can provide some useful information for deciding management plans to reduce soil loss and salt damage for stable crop production and diverse utilization or cultivation could be one of the management options to alleviate salt damage at reclaimed tidal saline soil in Korea.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.921-932
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• 2010

This paper presents a dual-band array antenna based on a modified Sierpinski fractal structure. Array structure is mirror symmetric, and forms broadside radiation pattern for dual frequency band if the ports are fed with $180^{\circ}C$ phase difference between upper and lower $2{\times}1$ array. To use in-phase corporate feeding circuit, the phase inversion structure is designed by changing the position of patch and ground for upper and lower array. The dimensions of the array antenna is $28{\times}30{\times}5\;cm^3$ and the bandwidth of 855~1,380 MHz(47 %), 1,770~2,330 MHz(27 %) were achieved for -10 dB return loss. The measured gain is 9.06~12.44 dBi for the first band and 11.76~14.84 dBi for the second band. The half power beam width is $57^{\circ}$ for x-z plane and $46^{\circ}$ for y-z plane at 1,100 MHz and $43^{\circ}$ and $28^{\circ}$ at 2,050 MHz, respectively.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.1
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• pp.80-89
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• 2008

Generally, trees lining the streets are the most easily accessible green areas in the city and constitute the smallest basic unit in the formation of the urban linear green axis. This study attempts to interpret issues related to city trees from a comprehensive and relational viewpoint. The site of this study is Central Park Street in front of Incheon Metropolitan City Hall. This street is representative of those in Incheon City. This study is an inter-relational interpretation of issues by measuring the vitality of these trees. The following are results of this study: First, the vitality of city trees is higher in those trees growing in natural ground than those growing in plant gratings. This observation can lead to budget savings and increased natural areas in the city. Also, if planter and multi-layering planting methods are introduced where damage to trees is predicted, variation to urban landscape can be achieved while linking to reinforced rearing foundation of street-side trees. Second, there is need for a holistic approach to caring for street-side trees regarding the damage caused by drastic pruning and strong street lights. The typical functions of these trees, like supplying freshness in summer, absorbing solar radiation, and controlling the urban micro-climate are closely related to the vitality of the trees. Accordingly, the function and ecology should be understood holistically, not separately. In this aspect, the functional and ecological use of the multi-layering planting method is effective in protecting pedestrians from vehicles as well. Third, the fallen leaves of monotonous rows of trees have different ecological and functional effects. Not only is the index of greenness in the urban setting increased, but there are also aesthetic and symbolic effects. Fourth, in spite of being the street along which Incheon Metropolitan City Hall, major administrative buildings and Central Park are located, this street does not have its own special identity to discriminate it from other streets. It fulfills only functional criteria based on uniformity. If there is no paradigm shift from today's street system based on vehicles, the role of landscape architecture will be very passive in regards to street-side trees, the minimum unit of urban green. Fifth, on this particular street, many trees were planted in December, which reflects a deficiency of short and long-term strategy, like a street-tree master plan. In this aspect, we still lack a mature culture concerning these trees as a basic unit in urban greenery. Furthermore, there needs to be cultural introspection concerning present administrative practices.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.132-139
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• 2007

The Moderate Resolution Imaging Spectroradiometer (MODIS) regularly provides the eight-day gross primary productivity (GPP) at 1 km resolution. In this study, we evaluated the uncertainties of MODIS GPP caused by errors associated with the Data Assimilation Office (DAO) meteorology and a biophysical variable (fraction of absorbed photosynthetically active radiation, FPAR). In order to recalculate the improved GPP estimate, we employed ground weather station data and reconstructed cloud-free FPAR. The official MODIS GPP was evaluated as +17% higher than the improved GPP. The error associated with DAO meteorology was identified as the primary and the error from the cloud-contaminated FPAR as the secondary constituent in the integrative uncertainty. Among various biome types, the highest relative error of the official MODIS GPP to the improved GPP was found in the mixed forest biome with RE of 20% and the smallest errors were shown in crop land cover at 11%. Our results indicated that the uncertainty embedded in the official MODIS GPP product was considerable, indicating that the MODIS GPP needs to be reconstructed with the improved input data of daily surface meteorology and cloud-free FPAR in order to accurately monitor vegetation productivity in Korea.

• Journal of Astronomy and Space Sciences
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• v.26 no.1
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• pp.75-88
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• 2009

The main purpose of the current research is to introduce the alternative algorithm of the non-recursive batch filter based on the unscented transformation in which the linearization process is unnecessary. The presented algorithm is applied to the orbit determination of a low earth orbiting satellite and compared its results with those of the well-known Bayesian batch least squares estimation and the iterative UKF smoother (IUKS). The system dynamic equations consist of the Earth's geo-potential, the atmospheric drag, solar radiation pressure and the lunar/solar gravitational perturbations. The range, azimuth and elevation angles of the satellite measured from ground stations are used for orbit determination. The characteristics of the non recursive unscented batch filter are analyzed for various aspects, including accuracy of the determined orbit, sensitivity to the initial uncertainty, measurement noise and stability performance in a realistic dynamic system and measurement model. As a result, under large non-linear conditions, the presented non-recursive batch filter yields more accurate results than the other batch filters about 5% for initial uncertainty test and 12% for measurement noise test. Moreover, the presented filter exhibits better convergence reliability than the Bayesian least squares. Hence, it is concluded that the non-recursive batch filter based on the unscented transformation is effectively applicable for highly nonlinear batch estimation problems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.10
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• pp.80-85
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• 2010

In this paper, a MIMO antenna is proposed for LTE/DCSl800/USPCSl900 handset applications. The proposed antenna is based on the IFA and its wide bandwidth is obtained by using a stagger tuning technique. To improve the isolation, a suspended line is connected to the shorting points in two antennas, and capacitors and inductors are added to the connected suspended line. Two identical antennas of which dimension is 2.8cc($40{\times}10{\times}7mm$) are mounted on the two end lines of the system ground plane($40{\times}60mm$). Analysis of the antenna performance and optimization is performed using CST Microwave Studio. The bandwidths are satisfied for LTE band class 13(746-787MHz), class 14(758-798MHz) and DCSl800/USPCSl900 band (1710-1990MHz). The isolations between two antennas are about -12dB for LTE band and -10dB for DCSl800/USPCSl900 band. And the radiation efficiency of each antenna is about for LTE band 33% and 45% for DCSl800/USPCSl900 band respectively.