• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.457-457
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• 2013

Current-voltage (I-V) measurements of crystalline silicon solar cells was conducted under dark conditions with the temperature range of 260 K~350 K. Using the calculation method, we extracted the crucial factors of ideality factor (n) and activation energy (Ea) to investigate the carrier conducting path in the space charge region (SCR) and the quasi-neutral region (QNR). Values of n were decreased with increasing temperature in both SCR and QNR. We also conformed that the value of Ea of SCR was larger than that of QNR about 0.4 eV. The temperature dependence of n indicates that the carrier conducting path is dominated by carrier recombination-generation in the SCR region than in the QNR region.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1313-1316
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• 2001

Generally, container carrier has larger engine than other commercial vessels and the engine casing is located in accommodation space. Therefore, the noise levels of cabins and engine room could be exceeded the specified noise limits and might be an annoyance to crews, and which can result in poor ship quality. Main subject of this study is to predict noise levels of the 4,500 TED container carrier by statistical energy analysis method in order to comply with contracted noise limits and to compare with the measured values. Additionally, through the contribution analysis of noise sources to each cabins, and appropriate countermeasures are proposed and the reduction effect of each noise control measure is studied by the analysis method. This study will contribute to reduce the noise levels of similar vessel.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.446-454
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• 2022

This study proposes a carrier-based pulse width modulation (PWM) method for leakage current reduction and neutral point (NP) current control in a three-phase three-level converter, which is a carrier-based PWM version of the previously proposed low-frequency common mode voltage PWM. Three groups of space vectors with the same common mode voltage are used. When the averaged NP current needs to be positive or negative, the specific groups are employed to produce low-frequency common mode voltages. The validity of the proposed PWM method is verified through experiments.

• The Korean Journal of Air & Space Law and Policy
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• v.18
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• pp.41-64
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• 2003

This paper describes the liability regime of the air carrier under the Montreal Convention of 1999 for the international cargo, comparing to those of the existing Warsaw system. Also this paper deals with main issues of the Montreal Convention which are relevent for the carrier's liability in the carriage of the air cargo. The Warsaw Convention was adopted in 1929 and modified successively in 1955, 1961, 1971, 1975, and 1999. The Montreal Convention of 1999 modernized and consolidated the Warsaw Convention and related instruments. The air carrier is liable by application of principle of strict liability as stated in the Montreal Convention : The carrier is liable for the destruction or loss of, or damage to cargo and delay during the carriage by air, and the carrier's liability is limited to a sum of 17 Special Drawing Rights per kilogramme. However, the Montreal Convention has some outstanding issues with respect to the liability of the air carrier : potential conflicts between the Montreal Convention and the Warsaw Convention, the amounts of limits of the carrier's liability, the duration of the carrier's liability, the exessive litigation, and the aviation insurance. Therefore, the conditions and limits of the carrier's liability under the Montreal Convention should be readjusted and regulated in detail.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.733-742
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• 2007

Bone morphogenetic proteins have been shown to possess significant osteoinSductive potential, but in order to take advantage of this effect for tissue engineering, carrier systems are essential. Successful carrier systems must enable vascular and cellular invasion, allowing BMP to act as a differentiation factor. The carrier should be reproducible, non-immunogenic, moldable, and space-providing, to define the contours of the resulting bone. The purpose of this study was to review available literature, in comparing various carriers of BMP on rat calvarial defect model. The following conclusions were deduced. 1. Bone regeneration of ACS/BMP, ${\beta}-TCP/BMP$, FFSS/BMP, $FFSS/{\beta}-TCP/BMP$, MBCP/BMP group were significantly greater than the control groups. 2. Bone density in the ACS/BMP group was greater than that in ${\beta}-TCP$, FFSS, $FFSS/{\beta}-TCP$ carrier group. 3. Bone regeneration in FFSS/BMP group was less than in ACS/BMP, ${\beta}-TCP/BMP$, MBCP/BMP group. However, New bone area of $FFSS/{\beta}-TCP/BMP$ carrier group were more greater than that of FFSS/BMP group. ACS, ${\beta}-TCP$, FFSS, $FFSS/{\beta}-TCP$, MBCP were used for carrier of BMP. However, an ideal carrier which was reproducible, non-immunogenic, moldable, and space-providing did not exist. Therefore, further investigation are required in developing a new carrier system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.56-62
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• 2011

A Satellite transponder is mounted on the Satellite and performs radio communications with the ground station. A Digital transponder compared to The analog transponder is made easy and accurate performance prediction. Also Modulation Scheme, Data Rate, Loop Bandwidth, Modulation Index and etc. can be changed on orbit, by implementing FPGA can reduce the weight and volume. The core technology of digital transponder is Carrier Recovery loop. Dynamic Range, Frequency Tracking Range, Frequency Tracking Rate and Coherent performance are determined by the performance of the Carrier Recovery loop. In this paper, we proposed the structure of Carrier Recovery loop for the Satellite digital transponder, then tested and verified the structure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1048-1054
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• 2012

This paper presents a Carrier phase fault detection (FD) method for GPS RTK (Global Positioning System Real Time Kinematic) in dynamic environment. There are various error sources in dynamic environment and these errors decrease the reliability of FD results. Due to the reason, Carrier phase measurements are separated into satellite induced signal, user induced signal and other remaining errors. Especially the user-induced signal is computed by user dynamic which is estimated by time-differenced Carrier phase (TDCP) and Doppler shift. TDCP makes it possible to avoid integer ambiguity resolution. Computer simulation is conducted to verify the suggested method. By applying impulse, step and ramp faults, the FD performance is analyzed.

• Journal of Astronomy and Space Sciences
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• v.33 no.1
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• pp.45-54
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• 2016

This study developed an approach for improving Carrier-phase Differential Global Positioning System (CDGPS) based realtime satellite relative navigation by applying laser baseline measurement data. The robustness against the space operational environment was considered, and a Synthetic Wavelength Interferometer (SWI) algorithm based on a femtosecond laser measurement model was developed. The phase differences between two laser wavelengths were combined to measure precise distance. Generated laser data were used to improve estimation accuracy for the float ambiguity of CDGPS data. Relative navigation simulations in real-time were performed using the extended Kalman filter algorithm. The GPS and laser-combined relative navigation accuracy was compared with GPS-only relative navigation solutions to determine the impact of laser data on relative navigation. In numerical simulations, the success rate of integer ambiguity resolution increased when laser data was added to GPS data. The relative navigational errors also improved five-fold and two-fold, relative to the GPS-only error, for 250 m and 5 km initial relative distances, respectively. The methodology developed in this study is suitable for application to future satellite formation-flying missions.

• ETRI Journal
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• v.27 no.3
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• pp.319-325
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• 2005

In this paper the effect of temperature on the electrical properties of organic semiconductor disperse orange dye 25 (OD) have been examined. Thin films of OD have been deposited on $In_{2}O_{3}$ substrates using a centrifugal machine. DC current-voltage (I-V) characteristics of the fabricated devices $(Al/OD/In_{2}O_{3)$ have been evaluated at varying temperatures ranging from 40 to $60^{\circ}C$. A rectification behavior in these devices has been observed such that the rectifying ratio increases as a function of temperature. I-V characteristics observed in $Al/OD/In_{2}O_{3)$ devices have been classified as low temperature $({\leq} 50^{\circ}C)$ and high temperature characteristics (approximately $60^{\circ}C$). Low temperature characteristics have been explained on the basis of the charge transport mechanism associated with free carriers available in OD, whereas high temperature characteristics have been explained on the basis of the trapped space-charge-limited current. Different electrical parameters such as traps factor, free carrier density, trapped carrier density, trap density of states, and effective mobility have been determined from the observed temperature dependent I-V characteristics. It has been shown that the traps factor, effective mobility, and free carrier density increase with increasing values of temperature, whilst no significant change has been observed in the trap density of states.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.491-500
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• 2005

Every time laboratory in the world follows an international standard time scale and GPS (Global Positioning System) is playing an important role. Korea Research Institute of Standards and Science is also operating a permanent GPS station for time transfer. To improve the accuracy and precision of the clock offsets derived from GPS we used carrier phase measurements. In addition, we tested four different kinds of GPS satellite orbits and compared the results. The precision of the time offsets using rapid and ultra-rapid orbits was about 0.5 nanoseconds (ns). Tn the case of broadcast orbits, the precision was better than 2 ns.