• Ocean Systems Engineering
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• v.9 no.1
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• pp.43-77
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• 2019

A local-analytic-based Navier-Stokes solver has been employed in conjunction with a compound ocean structure motion analysis program for time-domain simulation of passing ship effects induced by multiple post-Panamax class ships in the exact condition of a real waterway. The exact seabed bathymetry was reproduced to the utmost precision attainable using the NOAA geophysical database for Virginia Beach, NOAA nautical charts for Hampton Roads and Norfolk harbor, and echo sounding data for the navigation channel and waterfront facilities. A parametric study consists of 112 simulation cases with various combinations of ship lanes, ship speeds, ship heading (inbound or outbound), channel depths, drift angles, and passing ship coupling (in head-on or overtaking encounters) were carried out for two waterfront facilities at NAVSTA Norfolk and Craney Island Fuel Terminal. The present paper provides detailed parametric study results at both locations to investigate the site-specific passing ship effects on the motion responses of ships moored at nearby piers.

• Journal of IKEEE
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• v.26 no.1
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• pp.36-42
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• 2022

This study presents an analysis of the human body channel as an electric signal path using body impulse response (BIR). The human body communications (HBC) has recently emerged as an effective signal transmission method to create wireless body area networks (WBAN). We provide body channel characteristics based on measured BIR in a proper experimental environment for the HBC using capacitive coupling with a customized channel sounding device, which can be applied as a guideline for the HBC system design. The frequency response of the BIR, extracted by a customized signal processing for the measure signals, shows the channel path loss (CPS) between 0 MHz and 100 MHz with an average CPS of approximately 46.8 dB. In addition, the relative noise power distributions can provide estimations on the signal to noise ratio at the HBC receiver in terms of capacitor and resistor values in the measured frequency band and the frequency band lower than 3 MHz considering the baseband signal detection.

• Journal of Astronomy and Space Sciences
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• v.15 no.2
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• pp.391-400
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• 1998

KSR-II, a two-stage sounding rocket of KARI was launched successfully at the west coast of the Korean Peninsula at 1000LST, June 11, 1998. For the ozone measurement mission, 8-channel UV and visible radiometers were onboard the rocket. The rocket measured the first in situ stratospheric and mesospheric ozone density profile over Korea during its ascending phase using the radiometer. Comparisons with Dobson spectrophotometer, ozonesonde, and HALOE onboard the UARS are shown together. Our results are in reasonable agreements with others.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.277-284
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• 2000

KARI(Korea Aerospace Research Institute) has measured the ozone density profiles over the Korean Peninsular since the launch of the Korean Sounding Rocket-I (KSR-I) in 1993. The purpose of ozone measurements is to obtain the stratospheric and mesospheric vertical ozone density profiles over the Korean Peninsular with solar UV radiometers. With the visible channel of the radiometer, the attitude variation of the rocket was corrected and compensated. Developed system is based on ozone detector designs onboard the KSR-I and KSR-II. We discuss the development of ozone detector which will be onboard the KSR-III and its circuit and vibration test results for EM model.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.13 no.1
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• pp.1-5
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• 1977

A series of echo-sounding and current measurements as well as the drogue and the drift bottle experiments were carried out in Asan Bay since November 1974. Several sand bars or sand flats covered by silts were developed at ebb tide in the bay. Sand waves and sand ripples were seen on the surface of the sand bars, around which sea channels of 8~ 12 meters in depth are formed. The main stream axis of the flood current which is separated into east and west branch flows southward. A cyclonic and an anticyclonic eddy are developed at the early stage of flood tide. They are transformed into a clockwise eddy before the slack water. The maximum tidal current speed observed was 3.1 ~ 3.2 knots at the entrance of the bay, while it was 1.O ~ 2.8 knots in the bay. The location of the main stream axis of the tidal current coincides well with the sea channel. A salt wedge was observed at the estuary of the Sabgyo-cheon River.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.372-375
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• 2004

The UV radiometer payload was launched successfully from the west coastal area of Korea Peninsula aboard KSR-III on 28, Nov 2002. KSR-III was the Korean third generation sounding rocket and was developed as intermediate step to larger space launch vehicle with liquid propulsion engine system. UV radiometer onboard KSR-III consists of UV and visible band optical phototubes to measure the direct solar attenuation during rocket ascending phase. For UV detection, 4 channel of sensors were installed in electronics payload section and each channel has 255, 290, 310nm center wavelengths, respectively. 450nm channel was used as reference for correction of the rocket attitude during the flight. Transmission characteristics of all channels were calibrated precisely prior to the flight test at the Optical Lab. in KARI (Korea Aerospace Research Institute). During a total of 231s flight time, the onboard data telemetered to the ground station in real time. The ozone column density was calculated by this telemetry raw data. From the calculated column density, the vertical ozone profile over Korea Peninsula was obtained with sensor calibration data. Our results had reasonable agreements compared with various observations such as ground Umkhr measurement at Yonsei site, ozonesonde at Pohang site, and satellite measurements of HALOE and POAM. The sensitivity analysis of retrieval algorithm for parameters was performed and it was provided that significant error sources of the retrieval algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.125-130
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• 2004

Various antennas have been developed to be used for UWB systems, However, Simultaneously meet omni-directional and low-VSWR requirements, essential for some applications such as UWB channel sounding. In this paper, we propose a novel wide band printed elliptic monopole antenna for UWB(Ultra wide Band). Wideband planar monopole disc antenna have been recently studied. The proposed antenna can cover m frequencies from 3.5GHz to 12GHz. it is determined from 10dB return loss. Antenna radiation pattern is omnidirectional at 3.5GHz - 10GHz. The antenna consists of the printed elliptical monopole disc with microstrip-line feed. Elliptic disc of antenna and ground height operate important to matching. The proposed antenna easy to construct UWB system.

• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.120-127
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• 1997

Depositional environment off the Shihwa Dam has been studied to investigate the change of sedimentation process and the pollution. In order to understand how the sediments are distributed, polluted and modified, depositional factors have been analyzed and compared with the previous data. Study area, located off the Shihwa Dam, was surveyed to collect 25 bottom samples and 2 cores in 1996 and echo-sounding in 1997. These sediments were analyzed for the study of the global characteristics of sediment such as grain size and organic matter. Among these samples, the selected twenty surface sediments were analyzed for the comparison with their contents of metallic elements (Al, Mn, Fe, V, Cr, Co, Ni, Cu, Zn, Cd, Pb, As). According to field and lab analysis of sediments, three sedimentological zones have been generally identified around study area; near the dam (sandy Silt), near the dike (Sand) and offshore (silty Sand) zones. Textural parameters show that the content of silt and clay is dominant near the dam excepting the dike zone of LNG Storage Base and offshore (Palmido). The total concentration of Mn, Ni, Fe, Zn and Cd in bulk sediments was increased after the construction of the dam, while the content of Mn and Cr were higher near tidal channel than in the offshore area. Meanwhile, the annual increasing pattern of some heavy metal has appeared in this area. Based on this primary study, modification of the depositional environment may be caused by the construction of the dam and LNG Storage Base. Additionally, environmental evaluation on organic/inorganic factors has been suggested for interpreting environmental changes caused by coastal development in the nearshore such as the Shihwa coastal area.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.1
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• pp.40-47
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• 2009

This paper presents the method of measuring the feedback interference channel, which is developed between the transmit and receive antennas of a wireless repeater by receiving the transmit signal at the receive antenna of the identical repeater, and experiment results obtained by analyzing the measurements. This experiment uses 2 GHz WCDMA signal and is carried out near a highway. The high-speed mobiles on highways cause reflected signals with high Doppler frequencies and large energy. In order to characterize the feedback channel, the power delay profile and the scattering function are estimated by identifying the delay spread, the Doppler spread, the number of fingers, and the attenuation with delay. Since the feedback interference channel is constructed between the fixed TX and RX antennas, which is dependent upon the multipaths developed by moving or fixed objects around the antennas, the channel shows different properties comparing to the conventional channels between the base station and the mobile station. Therefore, the results presented in the paper are expected to provide guidelines for designing and evaluating wireless repeater systems.

• Atmosphere
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• v.23 no.4
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• pp.453-470
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• 2013

As a part of the KIAPS Observation Processing System (KOPS), we have developed the modules of satellite radiance data pre-processing and quality control, which include observation operators to interpolate model state variables into radiances in observation space. AMSU-A (Advanced Microwave Sounding Unit-A) level-1d radiance data have been extracted using the BUFR (Binary Universal Form for the Representation of meteorological data) decoder and a first guess has been calculated with RTTOV (Radiative Transfer for TIROS Operational Vertical Sounder) version 10.2. For initial quality checks, the pixels contaminated by large amounts of cloud liquid water, heavy precipitation, and sea ice have been removed. Channels for assimilation, rejection, or monitoring have been respectively selected for different surface types since the errors from the skin temperature are caused by inaccurate surface emissivity. Correcting the bias caused by errors in the instruments and radiative transfer model is crucial in radiance data pre-processing. We have developed bias correction modules in two steps based on 30-day innovation statistics (observed radiance minus background; O-B). The scan bias correction has been calculated individually for each channel, satellite, and scan position. Then a multiple linear regression of the scan-bias-corrected innovations with several predictors has been employed to correct the airmass bias.