• Journal of Sensor Science and Technology
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• v.11 no.5
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• pp.309-318
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• 2002

A stoichiometric mixture of evaporating materials for $CdIn_2S_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CdIn_2S_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CdIn_2S_4$ single crystal thin films measured with Hall effect by van der Pauw method are $9.01{\times}10^{16}\;cm^{-3}$ and $219\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CdIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=2.7116\;eV-(7.74{\times}10^{-4}\;eV)T^2/(T+434)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CdIn_2S_4$ have been estimated to be 0.1291 eV and 0.0248 eV, respectively, by means of the photocurrent spectra and the Hopfield quasi cubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}5$ states of the valence band of the $AgInS_2$/GaAs epilayer. The three photocurrent peaks observed at 10K areascribed to the $A_1$-, $B_1$-, and C1-exciton peaks for n = 1.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.364-370
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• 1994

The purpose of this study is to evaluate the clinical application of the no carrier added $[^{51}Cr]Cr(III)$-EDTA complexes, produced at Korea Cancer Center Hospital. The $[^{51}Cr]Cr(III)$-EDTA complexes, usefut for measurement of GFR were prepared at room temperature in the presence of bicarbonate catalysts. The radiochemical purity of $[^{51}Cr]Cr(III)$-EDTA was over 99% by paper electrophoresis. The time activity curves were obtained by counting the blood samples from 5 volunteers and counting the head and neck regions with whole body counter after injection of the $^{51}Cr$-EDTA, respectively. After the nonlinear regression, the area under curve was obtained. The plasma clearance of the $^{51}Cr$-EDTA was calculated with injected dose/AUC. The clearance rate calculated with the head and neck counting data was in good agreement with the result from the plasma sample radioactivity at 1-3 hrs after injection. From this result, the counting of head and neck region and the nonlinear regression by 2-compartment model could be applied for the measurement of the clearance rate. Using MIRD system, the absorbed radiation dose was calculated by residence $time{\times}S$. The absorbed whole body radiation dose was negligibly small.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.77-88
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• 2000

In this paper, the 3-mode variable gain high power amplifier for a transmitter of INMARSAT-B operating at L-band(1626.5-1646.5 MHz) was developed. This SSPA can amplify 42 dBm in high power mode, 38 dBm in medium power mode and 36 dBm in low power mode for INMARSAT-B. The allowable errol sets +1 dBm as the upper limit and -2 dBm as the lower limit, respectively. To simplify the fabrication process, the whole system is designed by two parts composed of a driving amplifier and a high power amplifier. The HP's MGA-64135 and Motorola's MRF-6401 were used for driving amplifier, and the ERICSSON's PTE-10114 and PTF-10021 for the high power amplifier. The SSPA was fabricated by the RP circuits, the temperature compensation circuits and 3-mode variable gain control circuits and 20 dB parallel coupled-line directional coupler in aluminum housing. In addition, the gain control method was proposed by digital attenuator for 3-mode amplifier. Then il has been experimentally verified that the gain is controlled for single tone signal as well as two tone signals. In this case, the SSPA detects the output power by 20 dB parallel coupled-line directional coupler and phase non-splitter amplifier. The realized SSPA has 41.6 dB, 37.6 dB and 33.2 dB for small signal gain within 20 MHz bandwidth, and the VSWR of input and output port is less than 1.3:1. The minimum value of the 1 dB compression point gets more than 12 dBm for 3-mode variable gain high power amplifier. A typical two tone intermodulation point has 36.5 dBc maximum which is single carrier backed off 3 dB from 1 dB compression point. The maximum output power of 43 dBm was achieved at the 1636.5 MHz. These results reveal a high power of 20 Watt, which was the design target.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.880-886
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• 2007

We have proposed a new "hybrid" envelope elimination and restoration(EER) transmitter architecture using an efficiency optimized power amplifier(PA) and modified bias modulator. The efficiency of the PA at the average drain voltage is very important for the overall transmitter efficiency because the PA operates mostly at the average power region of the modulation signal. Accordingly, the efficiency of the PA has been optimized at the region. Besides, the bias modulator has been accompanied with the emitter follower for the minimization of memory effect. A saturation amplifier, class $F^{-1}$ is built using a 5-W PEP LDMOSFET for forward-link single-carrier wideband code-division multiple-access(WCDMA) at 1-GHz. For the interlock experiment, the bias modulator has been built with the efficiency of 64.16% and peak output voltage of 31.8 V. The transmitter with the proposed PA and bias modulator has been achieved an efficiency of 44.19%, an improvement of 8.11%. Besides, the output power is enhanced to 32.33 dBm due to the class F operation and the PAE is 38.28% with ACLRs of -35.9 dBc at 5-MHz offset. These results show that the proposed architecture is a very good candidate for the linear and efficient high power transmitter.

• Journal of Cadastre & Land InformatiX
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• v.50 no.1
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• pp.107-123
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• 2020

With stabilization of the recent multi-GNSS infrastructure, and as multi-GNSS has been proven to be effective in improving the accuracy of the positioning performance in various industrial sectors. In this study, in view that SF(Single frequency) GNSS receivers are widely used due to the low costs, evaluate effectiveness of SF Real Time Point Positioning(SF-RT-PP) based on four multi-GNSS surveying methods with RTCM-SSR correction streams in static and kinematic modes, and also derive response challenges. Results of applying SSR correction streams, CNES presented good results compared to other SSR streams in 2D coordinate. Looking at the results of the SF-RT-PP surveying using SF signals from multi-GNSS, were able to identify the common cause of large deviations in the altitude components, as well as confirm the importance of signal bias correction according to combinations of different types of satellite signals and ionospheric delay compensation algorithm using undifferenced and uncombined observations. In addition, confirmed that the improvement of the infrastructure of Multi-GNSS allows SF-RT-SPP surveying with only one of the four GNSS satellites. In particular, in the case of code-based SF-RT-SPP measurements using SF signals from GPS satellites only, the difference in the application effect between broadcast ephemeris and SSR correction for satellite orbits/clocks was small, but in the case of ionospheric delay compensation, the use of SBAS correction information provided more than twice the accuracy compared to result of the Klobuchar model. With GPS and GLONASS, both the BDS and GALILEO constellations will be fully deployed in the end of 2020, and the greater benefits from the multi-GNSS integration can be expected. Specially, If RT-ionospheric correction services reflecting regional characteristics and SSR correction information reflecting atmospheric characteristics are carried out in real-time, expected that the utilization of SF-RT-PPP survey technology by multi-GNSS and various demands will be created in various industrial sectors.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.345-358
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• 2021

This study focuses on the development of the liquid air production process that uses LNG (liquefied natural gas) cold energy which usually wasted during the regasification stage. The liquid air can be transported to the LNG exporter, and it can be utilized as the cold source to replace certain amount of refrigerant for the natural gas liquefaction. Therefore, the condition of the liquid air has to satisfy the available pressure of LNG storage tank. To satisfy pressure constraint of the membrane type LNG tank, proposed process is designed to produce liquid air at 1.3bar. In proposed process, the air is precooled by heat exchange with LNG and subcooled by nitrogen refrigeration cycle. When the amount of transported liquid air is as large as the capacity of the LNG carrier, it could be economical in terms of the transportation cost. In addition, larger liquid air can give more cold energy that can be used in natural gas liquefaction plant. To analyze the effect of the liquid air production amount, under the same LNG supply condition, the proposed process is simulated under 3 different air flow rate: 0.50 kg/s, 0.75 kg/s, 1.00 kg/s, correspond to Case1, Case2, and Case3, respectively. Each case was analyzed thermodynamically and economically. It shows a tendency that the more liquid air production, the more energy demanded per same mass of product as Case3 is 0.18kWh higher than Base case. In consequence the production cost per 1 kg liquid air in Case3 was $0.0172 higher. However, as liquid air production increases, the transportation cost per 1 kg liquid air has reduced by $0.0395. In terms of overall cost, Case 3 confirmed that liquid air can be produced and transported with $0.0223 less per kilogram than Base case.

• Korean Journal of Biological Psychiatry
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• v.15 no.2
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• pp.83-91
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• 2008

Objectives : Neurological soft signs have been regarded as endophenotypes associated with the genetic basis of schizophrenia. This study was to investigate the intra-familial correlations of the neurological soft signs according to their genetic loading. Methods : Schizophrenic patients(N=14) were included, who had one parent with a family history of schizophrenia and the other without it. Genetic loading was determined by the patient's family history of schizophrenia using the Family Interview for Genetic Studies(FIGS). These parents were subdivided into two groups. The first group was designated as 'presumed carriers'(N=9) of genetic loading, who had one or more schizophreic firstor second-degree relatives. The second group was designated as 'presumed non-carriers'(N=11) of genetic loading, who had no schizophrenic first- or second-degree relatives. Normal controls(N=12) consisted of people without schizophrenic relatives. NSS were evaluated using the Neurological Evaluation Scale-Korean Version (NES-K), and the intra-familial correlations of NSS were tested using the Intra-Class Coefficients(ICC) method. Results : The scores of Motor Coordination subdimension of NES-K were significantly correlated between the patients and their presumed carriers(ICC=.804, p=.016), but not significantly correlated between the patients and their presumed noncarriers. In other subdimensions of NES-K, no significant correlation were found between the patients and their parents regardless of the genetic loading. But, there were no statistically significant differences in the scores of Motor Coordination subdimension of NES-K between the patients and controls. Conclusion : This study did not prove that the neurological soft signs might be an endophenotype of schizophrenia that cosegregate with the genetic loading. The future study using more subjects than this would be needed.

• Pediatric Infection and Vaccine
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• v.11 no.1
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• pp.73-80
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• 2004

Purpose : The serial clinical findings, biochemical results, and serological hepatitis B virus(HBV) markers in Korean children with chronic HBV infection were analyzed to determine the relationships among these factors. Methods : Ninety children have been chosen from those who have visited to the Department of Pediatrics at St. Vincent's Hospital in The Catholic University of Korea from July 1st, 1995 to June 30th, 2000. The sample patients were followed up for over six months. HBV markers and liver function tests were all performed. Results : All children were asymptomatic at presentation. Eighty-three percent of the children had a history of chronic HBV infection in their families. Eighty-one percent were HBeAg positive, 16% were anti-HBe positive, while 3% were all HBeAg and anti-HBe negative. The prevalence of HBeAg among three age groups : 0~5; 6~10; and 11~15 year-old was 90%, 96% and 61% respectively. The prevalence of HBeAg in less than 10 year-old group was significantly higher than 11~15 year-old group(P=0.001). Serum ALT levels were within 40 IU/L in 64% children, 41~80 IU/L in 17%, 81~200 IU/L in 10%, and beyond 201 IU/L in 9%. The percentage of abnormality of ALT levels in HBeAg positive patients was significantly higher than that of HBeAg negative(P=0.036). Eleven of the 73 HBeAg positive children lost their HBeAg and seroconverted to anti-HBe. In these cases, all had transient elevations in ALT levels before HBeAg seroconversions. The annual rates of spontaneous seroconversion of HBeAg and HBsAg were 9.7% and 0.6%, respectively. Conclusion : Recognition of the dynamics of these changes in viral markers and biochemical findings is needed in the selection and evaluation of therapeutic regimens, establishment of treatment, and calling for controlled trials with adequate follow-up. The hepatitis B carrier state may be asymptomatic in children however, continued surveillance of carriers is important to determine the individual adverse prognostic factors of chronic HBV infections.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.378-382
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• 2000

The effects of bisphenol A (BPA), known as one of the endocrine disrupting chemicals (EDCs), on the hatching of fertilized eggs (FE) and the spawning of adult fish in songsari, Oryzias latipes were investigated. In condition of the experimental groups, incubated water temperature was $25.0{\pm}0.5^{\circ}C$ and photoperiod was 16 h (light) : 8 h (dark). fE were exposed to aqueous solutions of BPA at nominal concentration of 50, 100 and $200 {\mu}g/l$. The time required in hatching of FE was long in the BPA $50 and 100 {\mu}g/l$ treatment groups when compared to the controls, and in the BPA $200 {\mu}g/l$ treatment group, FE failed to hatch. And also hatching rate was decreased in the BPA treatment groups in comparison to the controls, Adult fishes were reared to oral administration via a diet of 50, 100 and $200 {\mu}g/g$ body weight BPA concentration for 3 weeks, Number of total eggs spawned in the adult fish were fewer in the BPA 100 and 200 treatment groups than in the controls and BPA 50 treatment group. Frequency of abnormal eggs in the total eggs spawned was 11.8 and $16.2{\%}$ in the control and acetone carrier control lower than 36.8, 46,8 and $74.1{\%}$ in the BPA 50, 100 and 200 treatment groups, respectively. And hatching rate of FE decreased in the BPA treatment groups in comparison to the controls. In these results, inhibition of the hatching of FE and the quantity and quality of spawned eggs in adult fish were observed from BPA treatment groups when compared to the controls.

• Journal of Sensor Science and Technology
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• v.6 no.4
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• pp.328-336
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• 1997

The CdSe thin films were grown on the Si(100) wafers by a hot wall epitaxy method (HWE). The source and substrate temperature are $600^{\circ}C$ and $430^{\circ}C$ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by the van der Pauw method and studied on the carrier density and mobility dependence on temperature. From Hall data, the mobility was increased in the temperature range 30K to 150K by impurity scattering and decreased in the temperature range 150k to 293k by the lattice scattering. In order to explore the applicability as a photoconductive cell, we measured the sensitivity(${\gamma}$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in Cu vapor compare with in Cd, Se, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of $1.39{\times}10^{7}$, the MAPD of 335mW, and the rise and decay time of 10ms and 9.5ms, respectively.