• Water Engineering Research
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• v.1 no.4
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• pp.309-320
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• 2000

In this study, laboratory study of the behavior of wastewater discharged from the Boston ocean outfall was compared with the predictions of mathematical models. The dta sets cover broad ranges of discharge conditions and oceanic conditions, and are associated with a typical type of outfall discharges with multiport diffusers. The laboratory data sets were obtained in density stratified towing tanks. These data sets were used to evaluate four commonly used models: UM, UDKHDEN, RSB and CORMI$\times$2 for minimum dilution, the height to the top of the wastefield, and wastefield thickness. For minimum diluation and height to the top of the wastefield, UM and RSB predictions agree well with laboratory data. UDKHDEN overestimated the minimum dilution and height to the top of the wastefield while CORMI$\times$2 underestimated these values. All of the model predictions for the wastefield thickness were widely scattered. about the measured values. The hydraulic model study reproduced the major features observed in the laboratory. It also afforded considerable insight into the mechanics of mixing of multiport risers which could not have been obtained either from the laboratory test or the mathematical models.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1094-1103
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• 2001

According to standard procedures as defined in the users handbook for sea level data processes, I was compared to Topex/Poseidon sea level data from the first 350days of mission and Tide Gauge sea level data from the Amsterdam- Crozet- Kerguelen region in the South Indian Ocean. The comparison improves significantly when many factors for the corrections were removed, then only the aliased oceanic tidal energy is removed by oceanic tide model(11) in this period. Making the corrections and smoothing the sea level data ()ver 60km along-track segments and the Tide Gauge sea level data for the time series results in the digital correlation and RMS difference between the two data of c=-0.12 and rms= 11.4cm, c=0.55 and rms=5.38cm, c=0.83 and rms=2.83cm, and c=0.24 and rms=6.72 for the Amsterdam, Crozet and Kerguelenplateau, and Kerguelen coast, respectively. It was also found that the Kerguelen plateau has a comparisons due to propagating signals(the baroclinic Rossby wave with velocity of -3.9 ~-4.2cm/sec, period of 167days and amplitude of 10cm) that introduce temporal lags(${\gamma}$: 10~30days) between the altimeter and tide gauge time series. The conclusion is that on timescales longer than about 10days the RMS sea level errors are less than or of the order of several centimeters and are mainly due to the effects of currents rather than the effects of stories(water temperature, density) and winds.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.189-206
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• 2015

The present study was conducted to investigate the oceanic characteristics of the northern East China Sea through identification of long-term variation patterns of oceanic environment factors, for the objective of gaining understanding of oceanic environment characteristics of the northern waters of East China Sea, which closely influence the oceanic environments of waters nearby South Korea. The study methodology included the use of oceanographic data (water temperature, salinity, dissolved oxygen, nutrients, and chlorophyll-a) on the northern East China Sea from the Korea Oceanographic Data Center (KODC), collected by season for 20 years between 1995 and 2014. Moreover, for the study on the distribution of nutrients, chlorophyll-a. The main water masses that affected the northern East China Sea during the study period were classified as Changjiang diluted water (CDW), Tiawan current warm water (TCWW), Yellow Sea cold water (YSCW), and Kuroshio source water (KW). The forces of CDW and TCWW that forms on the surface and sub-surface layers had weakened for 20 years and the force of KW that forms on the intermediate layer showed a distinctively decreasing trend. However, YSCW showed a trend of expanding its force. Phosphate and silicate exhibited a decreasing tendency and phosphate showed a pattern of being depleted on the surface layer after 2009. It is determined that one of the reasons for this is the concentration of nutrients introduced through CDW and TCWW being too low. The concentration of chlorophyll-a exhibited an increasing tendency during the study period, the reasons for which are determined to be the influences of increase in water temperature, supply of nutrients via YSCW, and increases in light transmission from decrease in suspended solid due to the construction of the Three Gorges Dam.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.12a
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• pp.63-72
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• 2007

Current estimates of the ice-mass balance over the Greenland and the Antarctica using retrievals of time-varying gravity from GRACE are presented. Two different GRACE gravity data, UTCSR RL01 and UTCSR RL04, are used for the estimates to examine the impact of the relative accuracy of background models in the GRACE data processing for inter-annual variations of GRACE gravity data. In addition, the ice-mass balance is appraised from the conventional GRACE data, which represents global gravity, and the filtered GRACE data, which isolates the terrestrial gravity effect from GRACE gravity data. The former estimate shows that there exists similar negative trends of ice-mass balance over the Greenland from UTCSR RL01 and UTCSR RL04 while the time series from the both GRACE data over the Antarctica differ significantly from each other, and no apparent trends are observed. The result for the Greenland from the latter calculation is similar to the former estimate. However, the latter calculation presents positive trends of ice-mass balance for the Antarctica from both GRACE data. These results imply that residual oceanic geophysical signals, particularly for ocean tides, significantly corrupt the ice-mass estimate over the Antarctica as leakage error. In addition, the spatial alias of GRACE is likely to affect the ice-mass balance because the spatial spectrum of ocean tides is not conserved via GRACE sampling, and thus ocean tides contaminate terrestrial gravity signal. To minimize the alias effect, I suggest to use the combined gravity models from GRACE, SLR and polar motion.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.444-451
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• 2007

The design parameters of transmitter and receiver channel systems for COMS, which provides meteorological and ocean data services, were analyzed and the channel design parameters for a proper design of a small user-terminal were proposed in this paper. The COMS transmits the oceanic observation data by using the S/L-band link to the earth station. The meteorological data also are transmitted to the earth station, the meteorological data services, which are processed in the earth station, are provided to user. The sensor data are transmitted as digital signal type and are received by bilateral small-sized user terminals. So the optimal channel system for transmission and reception of sensor data should be designed on the basis of the channel modeling and analyzed results for primary technologies.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.27-28
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• 2011

A solar flares have the 11-year cycle and release a large energy which may produce coronal mass ejections (CME). The NOAA (National Oceanic and Atmospheric Administration) predicted that the sun spot activity will be maximized in 2013-2014. A strong solar flare can cause the disturbance of global positioning system including various communication of TV, radio broadcasting. The actual solar storm in 1989 caused power outages in Canada during 9 hours and about 600 million people had experienced a blackout. Such a solar storm can shorten the GPS satellite's life span about 5 to 10 years which can be resulted in economic loss considering the amount of multi-billion won. This paper analyzed the recent solar storm of X-class occurred on 15th of February about 10:45 this year that was reached Korea (Bohyun observatory) on 18th of February about 10:30 (local time), and compared with the data of before and after a week. The proton data of 18th of February considered that the solar strom reached on earth showed a fluctuation compared to the data of before and after a week. The positioning results at Daejeon also showed higher positioning error compared to the data of before and after a week results.

• Korean Journal of Remote Sensing
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• v.25 no.1
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• pp.1-10
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• 2009

We studied on the relationship between oceanic variation in the offshore and abnormal sea surface temperature rise in the coastal area of the Yellow Sea using a variety of satellite and in-situ data during winter 2004. In results of the satellite data, the average value of sea surface temperature in the Yellow Sea for 2003 was $10^{\circ}C$, and the average value of sea surface temperature for 2004 was $13^{\circ}C$. It was higher than those of the last year about $3^{\circ}C$. In results of the in-situ data, the average value of surface layer temperature in the Yellow Sea for 2003 was $9.85^{\circ}C$, and the average value of surface layer temperature for 2004 was $12.17^{\circ}C$. In the same satellite data, it was higher than those of the last year about $3^{\circ}C$. In results of the T-S diagram, we divided definitely into water mass of the Yellow Sea and the East China Sea in 2003. But we didn't divide definitely into water mass of the Yellow Sea and the East China Sea in 2004. The average values of air temperature and wind speed for 2003 were $5.23^{\circ}C$ and 4.81 m/s, respectively. And, the average values of air temperature and wind speed for 2004 were $5.61^{\circ}C$ and 4.52 m/s, respectively. So, These were similar. But the wind directions for 2003 were superior northwestern wind, and the wind directions for 2004 were various northern wind. The wind directions were different from each other. Therefore, the abnormal sea surface temperature rise in the coastal area of the Yellow Sea during winter 2004 were better related to oceanic variation in the offshore than influences of atmosphere. In the future, We will do in-depth study for these.

• Korean Journal of Remote Sensing
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• v.14 no.2
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• pp.117-128
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• 1998

Topex/Poseidon satellite, launched in Auguest 1992, has provided more 5 years of very good quality data. Efficient improvements, either about instrumental accuracy or about sea level data correction, have been made so that Topex/Poseidon has become presently a wonderful tool for many researchers. The first mission data of 73 cycles, September 1992 - August 1994, was used to our study in order to know characteristics of environmental correction factors in the Amsterdam-Crozet-Kerguelen region of the South Indian Ocean. According to standard procedures as defined under user handbook for sea surface height data processes, then we have chosen cycles 43 as the cycle of reference because this cycle has provided the completed data for measurement points and has presented the exacted position of ground track compared to another cycles. It was computed variations of various factors for correction in ascending ground track 103(Amsterdam-Kerguelen continental plateau) and descending ground track170 (Crozet basin). Here the variations of ionosphere, dry troposphere, humid troposphere, electromagnetic bias, elastic tide and loading tide were generally very smaller as a few of cm, but the variations of oceanic tide(30-35cm) and inverted barometer(15-30cm) were higher than another factors. For the correction of ocean tide, our model(CEFMO: Code d' Elements Finis pour la Maree Oceanique) - This is hydrodynamic model that is very well applicated in all oceanic situations - was used because this model has especially good solution in the coastal and island area as the open sea area. Conclusionally, it should be understood that the variation of ocean free surface is mainly under the influence of tides(>80-90%) in the Amsterdam - Crozet- Kerguelen region of the South Indian Ocean.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.9
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• pp.32-39
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• 2006

In this paper, an iterative subspace-based calibration algorithm for a CDMA-based antenna array in the presence of unknown gain and phase error is presented. The algorithm does not depend on the array geometry and does not require a prior knowledge of the Directions Of Arrival (DOA) of the signals. The method requires the code sequence of a reference user only. The proposed algorithm is based on the subspace method and root finding approach, and it provides estimates of the calibration vector, the DOA and the channel impulse response, by using the code sequence of a reference user. The performance of the proposed algorithm was investigated by means of computer simulations and was verified using field data measured through a custom-built W-CDMA test-bed. The data show that experimental results match well with the theoretical calibration algorithm. Also, teh study propose an efficient algorithm using the simulated annealing technique. This algorithm overcomes the requirement of initial guessing in the subspace-based approach.

• The Journal of the Acoustical Society of Korea
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• v.24 no.1E
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• pp.21-27
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• 2005

Environmental mismatch has been one of important issues discussed in matched field processing for underwater source detection problem. To overcome this mismatch many algorithms professing robustness have been suggested. Feature extraction method (FEM) [Seong and Byun, IEEE Journal of Oceanic Engineering, 27(3), 642-652 (2002)] is one of robust matched field processing algorithms, which is based on the eigenvector estimation. Excluding eigenvectors of replica covariance matrix corresponding to large eigenvalues and forming an incoherent subspace of the replica field, the processor is formulated similarly to MUSIC algorithm. In this paper, by using the ocean experimental data, processing results of FEM and MVDR with white noise constraint (WNC) are presented for two levels of multi-tone source. Analysis of eigen-space of CSDM and FEM performance are also presented.