• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.63-69
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• 2008

Reconfigurable RF one-chip solutions have been researched with the objective of designing for smaller-sized and more economical RF transceiver and it can be applied to a vehicular wireless terminal. The proposed voltage-controlled oscillator satisfies the targeted frequency range ($4.2{\sim}5.4\;GHz$) and the frequency planning which correspond to the standards such as CDMA(IS-95), PCS, GSM850, EGSM, WCDMA, WLAN, Bluetooth, WiBro, S-DMB, DSRC, GPS, and DVB-H/DMB-H/L(L Band). In order to improve phase noise performance, PMOS is adopted in the cross-coupled pair, the tail current source and MOS varactor in this VCO and differential-typed switching is proposed in capacitor array. Based on the measurement results, a total power dissipation is $5.3{\sim}6.0\;mW$ at 1.8 V power supply voltage. The oscillator is tuned from 4.05 to 5.62 GHz; The tuning range is 33%. The phase noise is -117.16 dBc/Hz at 1 MHz offset frequency and the FOM (Figure Of Merit) is $-180.84{\sim}-180.5$.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.251-261
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• 2022

The Centimeter Level Augmentation Service (CLAS) is the Precise Point Positioning (PPP) - Real Time Kinematic (RTK) correction service utilizing the Quasi-Zenith Satellite System (QZSS) L6 (1278.65 MHz) signal to broadcast the Global Navigation Satellite System (GNSS) error corrections. Compact State-Space Representation (CSSR) corrections for mitigating GNSS measurement error sources such as satellite orbit, clock, code and phase biases, tropospheric error, ionospheric error are estimated from the ground segment of QZSS CLAS using the code and carrier-phase measurements collected in the Japan's GNSS Earth Observation Network (GEONET). Since the CLAS service begun on November 1, 2018, users with dedicated receivers can perform cm-level precise positioning using CSSR corrections. In this paper, CLAS-based VRS-RTK performance evaluation was performed using Global Positioning System (GPS) observables collected from the refence station, TSK2, located in Japan. As a result of performing GPS-only RTK positioning using the open-source software CLASLIB and RTKLIB, it took about 15 minutes to resolve the carrier-phase ambiguities, and the RTK fix rate was only about 41%. Also, the Root Mean Squares (RMS) values of position errors (fixed only) are about 4cm horizontally and 7 cm vertically.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.214-222
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• 2001

A precise echosounding system to investigate the topographical characteristics of the coastal fishing ground was composed of a public-DGPS receiver, a single beam echosounder and a survey software. To confirm the usefulness of the system, a set-net fishing ground and the distribution of artificial reefs were surveyed. The results obtained are as follows : 1. The 2-D positioning error of the public-DGPS receiver with a DGPS mode and a GPS mode was 5.47 m, 7.03 m, respectively. 2. The experimented set-net fishing ground was located on the level ground at the depth of 9-10 m, a small size valley 1-2 m deep and approximately 10 m wide was found at a distance of 120 m from the set-net to the south. 3. In the artificial reefs' water area near the Jaran Bay, it was confirmed that twenty rectangular artificial reefs were established by the piece at the depth of 15-25 m and a natural reef 5-8 m high on the sea bed was located near the group of artificial reefs. 4. It was confirmed that the precise echosounding system was a useful tool in the pre-study to choice an appropriate water area to provide the artificial reef.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.458-465
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• 2004

To reaffirm the use of a mainstream CMOS process for designing passive-like attenuator structures, a linearly controlled variable attenuator is realized with 0.35${\mu}{\textrm}{m}$ 2-poly 4-metal CMOS process. It uses the П configuration for large attenuation range and suitable matching property. Compared to conventional passive-like CMOS attenuators, it is demonstrated that this work advances the frequency band from MHz to ㎓ (DC- l㎓), and reduces the size to 700${\mu}{\textrm}{m}$${\times}$300${\mu}{\textrm}{m}$.. Both simulation results and test results are provided. They show the improved linear relation between attenuation and control voltage. It is very useful in CDMA or GSM band, which uses under 1㎓ frequency band. An alternative topology, Bridged-T configuration, is proposed to get over the limit of applications by elevating operation bandwidth. The proposed topology covers over DC-2㎓ frequency band, which means that the proposed architecture can cover the tripleband (800MHz CDMA/GSM, 1.5㎓ GPS, 1.9㎓z PCS system) in applications as well. The simulation results are provided.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.78-95
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• 2011

This study has developed various DEMs with different spatial resolutions using many different interpolation methods with the aid of a 1:5,000 digital map. In addition, this study has evaluated the vertical accuracy of various DEMs constructed by check point data obtained from the network RTK GPS survey. The obtained results suggest that a DEM developed from the TIN-based Terrain method performs well in evaluating height restriction of buildings in a flying safety area considering general RMSE values, land-type RMSE values and profile evaluation results, etc. And, it has been found that three meters is the right spatial resolution for a DEM in evaluating height restriction of buildings in a flying safety area. Meanwhile, elevation values obtained by the DEM are not point estimation values but interval estimation values. This can be used to check whether the height of buildings in the vicinity of an airfield violates height limitation values of the area. To check whether the height of buildings measured in interval estimation values violates height limitation values of the area, this study has adopted three steps: 1) high probability of violation, 2) low probability of violation, 3) inconclusiveness about the violation. The obtained results will provide an important basis for developing a GIS related to the evaluation of height restriction of buildings in the vicinity of an airfield. Furthermore, although results are limited to the study area, the vertical accuracy values of the DEM constructed from a two-dimensional digital map may provide useful information to researchers who try to use DEMs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.560-565
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• 2002

In this paper, we implemented the sign board system that displays user's image, user's sentence, the information from DARC an[1 information based position by GPS module for vehicle. The existing sign board is displaying only user's image and sentence. Or other existing sign board is displaying the information via CDMA network. However, our system is also able to display the user's message like other system and gain the information more cheap by DARC. This system consists of 6 parts. The DARC control part classes the DARC information - news, weather, stock and time. The GPS control part gains moment and item to display with calculating the information of global position, direction, speed and satellite. The LED control part has two buffers to store and handle the image. The buffers help the system display various effected images on LED board. An external memory card includes the location based data, the option file and the displayed data files. The data files are stored by FAT 16 with the folder structure on external memory card. The USB controls the communication with PC. PC programs can control and monitor this system. This system is using G72l voice file format, for casting the information. This system was established at the vehicle and we monitored this system. The system displayed the DARC data , user's data and the location based data on the LED board, successfully.

• Korean Journal of Geomatics
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• v.3 no.1
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• pp.15-22
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• 2003

This study aims to construct a management system of road position information as part of the build-up to a maintenance and management system of highways. First, information on the positions of the roads were obtained by a real-time kinematic satellite surveying, and then the degree of accuracy was analyzed in comparison with the data of the existing design drawings. The linear coordinates of road center line obtained by using RTK GPS showed about 7.6-13.2cm errors in X and Y directions in the case of the national road No.2 section, and about 8.4-9.2cm errors in the case of local road No.1045 section. These errors were within the tolerance scope regulated by the TS survey, and could be practically used. In the case of vertical alignment, there were about 6.2cm errors in the Z direction in local road No.1045 section. Aerial photographs are normally used in producing numerical maps, and it can be practically used because the tolerance scope of the elevation control point is l0cm when the scale of aerial photographs is 1/1000. The management system of road position information, utilizing Object-Oriented Programming(OOP), was built having the data acquired in this way as the attribute data. The system developed in this way can enable us to spot the positions of road facilities, the target of management with ease, to easily update the data in case of changes in the positions of roads and road facilities, and to manage the positions of roads and road facilities more effectively.

• Journal of the Korean GEO-environmental Society
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• v.8 no.4
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• pp.19-25
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• 2007

Process analysis with ASM3 (Activated Sludge Model3) was performed to offer basic data for the optimization of aerated biofilter (ABF) process design and operation. This study was focused on the simulation of the nitrification reaction in ABF which was a part of the advanced nutrient treatment process using bio-adsorption. The ABF process has been developed for the removal of suspended solids and nitrification reaction in sewage. A GPS-X (General Purpose Simualtor-X) was used for the sensitivity analysis and operation assessment. Sensitivity of ASM3 parameters on ABF was analysed and 4 major parameters ($Y_A$, $k_{sto}$, ${\mu}_A$, $K_{A,HN}$) were determined by dynamic simulation using 70 days data from pilot plant operation. The optimized values were 0.14 for $Y_A$, 3.5/d for $k_{sto}$, 2.7/d for ${\mu}_A$ and 1.1 mg/L for $K_{A,HN}$, respectively. Simulation with optimized parameter values were conducted and TN, $NH_4{^+}-N$ and $NO_3{^-}-N$ concentrations were estimated and compared with measured data at the range of 10 min to 4 hrs of hydraulic retention time (HRT). The simulated results showed that optimized parameter values could represent the characteristics of ABF process. Especially, the ABF showed relatively high nitrification rate (60%) under very short HRT of 10 min. As a consequence, the ABF was thought to be successfully used in the site which having high variation of influent loading rate.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.111-119
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• 2022

The occurrence of cyanobacterial blooming and the contaminant sources were analyzed in the downstream of Jecheon Stream, a tributary of Chungju Reservoir. The concentrations of chlorophyll a at the Myungseo Fishing Point (GPS; 37°03'25.5"N, 128°03'13.6"E) were 399.2 and 184.8 mg m^-3 on October 18, 2015 and September 25, 2016, respectively, and the concentrations of total microcystins, a cyanobacterial toxin mainly produced by Microcystis, were 124.09 and 79.71 ㎍ L^-1, respectively. The occurrence of cyanobacterial blooming at the downstream of Jecheon Stream was closely related to the water level of Chungju Reservoir. The cyanobacterial blooming occurred after the increase of water level in Chungju Reservoir, when the water body stagnated. As a result of analyzing National Water Quality Monitoring Data of the upper region of Jecheon Stream, the main source of pollutant was Jangpyeong Stream, the tributary of Jecheon Stream, and the discharge water from Jecheon Wastewater Treatment Plant located in Jangpyeong Stream was considered to be the most important source of contaminant.

• Journal of Veterinary Clinics
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• v.29 no.1
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• pp.27-32
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• 2012

The purpose of this study was to evaluate survival rates of vitrified mouse blastocysts in various vitrification solutions (cryoprotectants) and apparatuses. The mouse blastocysts were harvested from culture of mouse 2 cell embryo and were divided into three group (i) untreated (control); (ii) exposed to cryoprotectant agents; or (iii) cryopreserved by various vitrification apparatuses. Vitrification solutions are 40% ethylene glycol (EG) + 5.8 mg/mL ficoll + 0.5M sucrose (EFS solution), 3M glycerol + 3M EG (ES solution), 20% EG + 20% dimethyl sulfoxide (ED solution), 3M EG + 1.0 m sucrose (ES solution). Vitrification apparatuses consisted of 5 groups ; closed plastic straw (CPS), electron microscope (EM) grid, cryoloop, open pulled straw (OPS), and glass micropippete in plastic straw (GPS). The survival rates of control were 88.0%. The survival rates of exposed blastocysts in EFS, GE, ED, and ES solutions were 70.8%, 43.5% (P<0.01), 83.3% and 65.2%, respectively. The survival rates of vitrified blastocysts in CPS, EM grid, cryoloop, OPS and GPS were 56.5% (P< 0.01), 72.7%, 83.3%, 60.9% (P<0.05) and 54.2% (P<0.01), respectively. Among the vitrification solutions, the highest survival rate was seen in blastocysts vitrified in EG + DMSO (83.3%). The survival rate was not significantly different from that of the control (88%). Blastocysts cryopreserved with glycerol in all groups had an overall low survival rate of 43.5%. Survival rate of mouse blastocysts between vitrification apparatuses showed higher in cryoloop.