• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3740-3747
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• 2009

To protect the citizens' health of Gyeongju and to secure basic data for the assessment of health and environmental risk, distribution characteristics of meteorological elements were investigated and numerical simulation of wind field using RAMS model was carried out. In addition, measurement and analysis of air pollutants, forecasting the behavior air pollutants using ISC-AEROMOD view, and health and environmental risk-influenced zones were defined through managing air polluting materials to prevent health damage and property damage. According to the survey results of air pollution in Gyeongju and surroundings, average annual concentration of air pollutants in Gyeongju was slightly lower than that in Pohang and Ulsan areas, but concentration of particulate matters and nitrogen dioxide at Gyeongju Station Square and Yonggang Crossing were sometimes higher than that in Pohang and Ulsan areas. Results of the modeling of moving and diffusion of air pollutants that affect citizens' health showed that parts of the 1st through 4th industrial complexes together with POSCO were included in particulate matters and sulfur dioxide influenced areas in Pohang Steel Complex area, and that Haedo-dong, Sangdae-dong, Jecheol-dong and Jangheung-dong in Pohangnam-gu represented locally worsened air quality due to a quantity of air pollutant emission from dense steel industries and large scale industrial facilities.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.671-678
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• 1997

Water surface velocity meters with microwave were applied to stream discharge measurements and its practical aspects were evaluted. The rating of the surface velocity meters was performed through a carriage and a water tank for the ship model test. It gave5.5% or less errors of average measured velocities under the vertical tilt ang1e of 20$^{\circ}$, 35$^{\circ}$, or 45$^{\circ}$ . A surface velocity meter was used to measure flood velocities at Yoju bridge from 8:00 a.m. to 10:00 a.m. on August 26, 1995. The results showed that surface velocities ranged from 2 to 4 m/s. With the measured surface velocities multiplied by 0.85, the discharge was computed as 10,500 m$^3$/s. It differed $\pm$2% or less from the value of a stage-discharge curve and that of an unsteady flow simulation. Although the measured data are used sparsely per 40 or 60 meters, the computed discharges do not give large variation. Stream discharge measurements were also performed under the normal condition without floods. With the known values of Taechong Dam releases. the depth averaging factors of velocity were calculated by 0.83~0.87. Although there are errors from wind action and inherent ones in the velocity meters, the research showed that surface velocity meters could be an simple and practical alternative for flood discharge measurements.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.401-406
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• 2010

Vessel Operator has been navigating with subjective sate distance in accordance with night & daytime, fore & aft, port & stbd abeam and visibility situation. This sate distances may different depending on inside & outside harbor limit, current, wind and visibility situation. By now, the concept of proper sate distance between navigating vessels has been adopted in Korea, using the early 1980's foreign data. And the safe distance is being used with the same value without any consideration of inside & outside harbor and the kind of vessel. So it is necessary to evaluate or search proper distance concept based on different sate consciousness of Korean manners. This paper aims to develop the basic model for marine traffic evaluation and the new model of marine traffic congestion. Also this paper proposes the basic control guideline of vessel traffic service center. The result of this study showed that minimum sate distance should be 4.4L forward, 3.1L aft and 26L abeam in case of good visibility in daytime, considering various parameters such as visibility, day and night. Some differences Here found between the existing minimum sate distance and the new minimum sate distance derived from the result of this study.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.3-17
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• 2004

Space-borne Earth observation technique is one of the most cost effective and rapidly advancing Earth science research tools today and the potential field and micro-wave radar applications have been leading the discipline. The traditional optical imaging systems including the well known Landsat, NOAA - AVHRR, SPOT, and IKONOS have steadily improved spatial imaging resolution but increasing cloud covers have the major deterrent. The new Earth observation satellites ENVISAT (launched on March 1 2002, specifically for Earth environment observation), ALOS (planned for launching in 2004 - 2005 period and ALOS stands for Advanced Land Observation Satellite), and RADARSAT-II (planned for launching in 2005) all have synthetic aperture radar (SAR) onboard, which all have partial or fully polarimetric imaging capabilities. These new types of polarimetric imaging radars with repeat orbit interferometric capabilities are opening up completely new possibilities in Earth system science research, in addition to the radar altimeter and scatterometer. The main advantage of a SAR system is the all weather imaging capability without Sun light and the newly developed interferometric capabilities, utilizing the phase information in SAR data further extends the observation capabilities of directional surface covers and neotectonic surface displacements. In addition, if one can utilize the newly available multiple frequency polarimetric information, the new generation of space-borne SAR systems is the future research tool for Earth observation and global environmental change monitoring. The potential field strength decreases as a function of the inverse square of the distance between the source and the observation point and geophysicists have traditionally been reluctant to make the potential field observation from any space-borne platforms. However, there have recently been a number of potential field missions such as ASTRID-2, Orsted, CHAMP, GRACE, GOCE. Of course these satellite sensors are most effective for low spatial resolution applications. For similar objects, AMPERE and NPOESS are being planned by the United States and France. The Earth science disciplines which utilize space-borne platforms most are the astronomy and atmospheric science. However in this talk we will focus our discussion on the solid Earth and physical oceanographic applications. The geodynamic applications actively being investigated from various space-borne platforms geological mapping, earthquake and volcano .elated tectonic deformation, generation of p.ecise digital elevation model (DEM), development of multi-temporal differential cross-track SAR interferometry, sea surface wind measurement, tidal flat geomorphology, sea surface wave dynamics, internal waves and high latitude cryogenics including sea ice problems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.1
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• pp.50-60
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• 2018

In this paper, we developed a broadband multi-layered radome applicable for high-power applications. In this regard, we presented the wave propagation characteristics of the broadband multi-layered radome with the ABCD matrix and obtained the optimal thickness and the material constant for each layer by an optimization algorithm called "particle swarm optimization," implemented by a commercial numerical modeling tool. Further, we redesigned it in view of mechanical properties to reflect environmental conditions such as wind, snow, and ice. The power transmission property was reanalyzed based on the recalculated data of each layer's thickness to consider the limitations of the fabrication of a large structure. Under the condition of a peak electric field strength that is 10 dB above the critical electric field strength in air breakdown, we analyzed the air breakdown by radio frequency(RF) in the designed radome using the commercial full-wave electromagnetic tool. The radome was manufactured and tested by continuous wave(CW) RF small signal and large signal in an anechoic chamber. The test results showed good agreement with those attained by simulation.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1115-1129
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• 2016

To analyze human thermal environments in protected horticultural houses (plastic houses), human thermal sensations estimated using measured microclimatic data (air temperature, humidity, wind speed, and solar and terrestrial radiation) were compared between an outdoor area and two indoor plastic houses, a polyethylene (PE) house and a polycarbonate (PC) house. Measurements were carried out during the daytime in autumn, a transient season that exhibits human thermal environments ranging from neutral to very hot. The mean air temperature and absolute humidity of the houses were $14.6-16.8^{\circ}C$ (max. 22. $3^{\circ}C$) and $7.0-12.0g{\cdot}m^{-3}$ higher than those of the outdoor area, respectively. Solar (K) and terrestrial (L) radiation were compared directionally from the sky hemisphere (${\downarrow}$) and the ground hemisphere (${\uparrow}$). The mean $K{\downarrow}$ and $K{\uparrow}$ values for the houses were respectively $232.5-367.8W{\cdot}m^{-2}$ and $44.9-55.7W;{\cdot}m^{-2}$ lower than those in the outdoor area; the mean $L{\downarrow}$ and $L{\uparrow}$ values were respectively $150.4-182.3W{\cdot}m^{-2}$ and $30.5-33.9W{\cdot}m^{-2}$ higher than those in the outdoor area. Thus, L was revealed to be more influential on the greenhouse effect in the houses than K. Consequently, mean radiant temperature in the houses was higher than the outdoor area during the daytime from 10:45 to 14:15. As a result, mean human thermal sensation values in the PMV, PET, and UTCI of the houses were respectively $3.2-3.4^{\circ}C$ (max. $4.7^{\circ}C$), $15.2-16.4^{\circ}C$ (max. $23.7^{\circ}C$) and $13.6-15.4^{\circ}C$ (max. $22.3^{\circ}C$) higher than those in the outdoor area. The heat stress levels that were influenced by human thermal sensation were much higher in the houses (between hot and very hot) than in the outdoor (between neutral and warm). Further, the microclimatic component that most affected the human thermal sensation in the houses was air temperature that was primarily influenced by $L{\downarrow}$. Therefore, workers in the plastic houses could experience strong heat stresses, equal to hot or higher, when air temperature rose over $22^{\circ}C$ on clear autumn days.

• Atmosphere
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• v.28 no.1
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• pp.37-51
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• 2018

In this study, we investigate the performance of Global Seasonal Forecasting System version 5 (GloSea5) in Korea Meteorological Administration on the relationship between El $Ni{\tilde{n}}o$ and East Asian climate for the period of 1991~2010. It is found that the GloSea5 has a great prediction skill of El $Ni{\tilde{n}}o$ whose anomaly correlation coefficients of $Ni{\tilde{n}}o$ indices are over 0.96 during winter. The eastern Pacific (EP) El $Ni{\tilde{n}}o$ and the central Pacific (CP) El $Ni{\tilde{n}}o$ are considered and we analyze for EP El $Ni{\tilde{n}}o$, which is well simulated in GloSea5. The analysis period is divided into the developing phase of El $Ni{\tilde{n}}o$ summer (JJA(0)), mature phase of El $Ni{\tilde{n}}o$ winter (D(0)JF(1)), and decaying phase of El $Ni{\tilde{n}}o$ summer (JJA(1)). The GloSea5 simulates the relationship between precipitation and temperature in East Asia and the prediction skill for the East Asian precipitation and temperature varies depending on the El $Ni{\tilde{n}}o$ phase. While the precipitation and temperature are simulated well over the equatorial western Pacific region, there are biases in mid-latitude region during the JJA(0) and JJA(1). Because the low level pressure, wind, and vertical stream function are simulated weakly toward mid-latitude region, though they are similar with observation in low-latitude region. During the D(0)JF(1), the precipitation and temperature patterns analogize with observation in most regions, but there is temperature bias in inland over East Asia. The reason is that the GloSea5 poorly predicts the weakening of Siberian high, even though the shift of Aleutian low is predicted. Overall, the predictability of precipitation and temperature related to El $Ni{\tilde{n}}o$ in the GloSea5 is considered to be better in D(0)JF(1) than JJA(0) and JJA(1) and better in ocean than in inland region.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.4
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• pp.344-353
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• 2016

The cause of abnormal tidal residuals was examined by analyzing sea levels, sea surface atmospheric pressures, winds at ten tide stations, and current, measured at the coast of the Yellow Sea from the night of November $24^{th}$ to the morning of the $25^{th}$ in 2013, along with weather chart. Additionally, the cross-correlations among the measured data were also examined. The 'abnormal tidal residuals' mentioned in this study refer to differences between maximum and minium tidal residuals. The largest abnormal tidal residual was identified to be a difference of 176 cm occurring over 4 hours and 1 minute at YeongJongDo (YJD) with a maximum tidal residual of 111 cm and minimum of -65 cm. The smallest abnormal tidal residual was 68 cm at MoSeulPo (MSP) during 8 hours 52 minutes. The cause of these abnormal tidal residuals was not a meteo-tsunami generated by an atmospheric pressure jump but wind generated by the pressure patterns. The flow speed due to these abnormal tidal residuals as measured at ten tide stations was not negligible, representing 16 ~ 41 % of the annual average ebb current speed. From the cross correlation among the tidal residuals, winds, and tidal residual currents, we learned the northern flow, due to southerly winds, raised the sea level at Incheon when a low pressure center located on the left side of the Korean Peninsula. After passing the Korean Peninsula, a southern flow due to northerly winds decreased the sea level.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.497-512
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• 2017

Temporal and spatial variations in surface water temperature were studied using data from temperature monitoring buoys deployed at 47 stations around Boryeong from 2011-2012 off the west coast of Korea. Temperature fluctuations are predominant at diurnal and semidiurnal periods for all seasons, and their amplitudes are large in spring and summer but small in autumn. The maximum annual change in air temperature takes place on August 2nd and August 22th for water temperature, which means the phase for air temperature precedes water temperature by 20 days. The diurnal period of water temperature fluctuation is predominant around Daecheon and Muchangpo Harbors, with the semidiurnal period around Wonsan Island, and the shallow water constituent period on the estuary around Daecheon River. On the whole, air and water temperatures fluctuate with wind. Spectral analyses of temperature records show significant peaks at the 0.5, 1 and 15 day marks with 7-10 day periods of predominant fluctuations. Cross-correlation analyses for the temperature fluctuation show that the waters around Boryeong can be classified into four areas: a mixed water zone around the southeast side of Wonsan Island, an off-shore area to the west, an off-shore area to the south and a coastal area along the shore from Song Island to Muchangpo Harbor.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.531-541
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• 2020

In this study, a computed tide of a real tide was introduced to improve the numerical solutions for tides and tidal flow simulations. The real tide was defined considering the nodal modulation amplitude, phase correction factor, astronomical argument, and tidal harmonic constants of all the constituents. The numerical simulation was performed using the real tide parameters for the west-south coastal waters of Korea, where the observation data for tides, tidal currents, waves, and winds over two seasons exist. The tidal flow simulation of the real tide was simulated successfully. The correlation coefficient between the observed and calculated values was 1.0, which indicated both accurate amplitude and phase. The U- and V-components of the tidal current obtained for the real tide had average valid correlations of 0.83 and 0.936, respectively. The speed error for the residual current was 0.006 m/s on the average, which indicated an insignificant difference, and the directional behavior of the residual current was very similar. In addition, the velocity error was attributed to various weather effects, such as high waves and wind storms. Therefore, this model is expected to improve current solutions provided that weathering forces, such as waves and winds, are considered.