• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.450-451
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• 2010

In this paper, the low-cost drive circuit of dc motor for a multipurpose small-size electric vehicle is developed. In order to change smoothly the rotating direction of dc motor for traction, the operating sequence of both the field current and the armature voltage according to the angle of a pedal of vehicle is suggested. The simulation study is carrier out to verify the proposed method, and the control system is implemented with 8-bit AVR.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.244-244
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• 2012

Polymer memory devices have attracted considerable attention because of their advantages such as low cost potential, good scalability, flexibility, simplicity in structure, and large capacity for data storage. Metal/poly (4,4'-aminotriphenylene hexafluoroisopropylidenediphthalimide) (6F-TPA PI)/metal system has been found to show an electrical bi-stable behavior. Here, we show a novel set-up of 6F-TPA PI/Al sample in which holes are injected by photoelectron emission process instead of direct charge carrier injection via metal electrode. In this process, an irreversible electrical phase transition of 6F-TPA PI is found, leading to a write-once-read-many (WORM) behavior. The photoelectron spectroscopy results measured before and after the switching process revealed that the irreversible electrical phase transition of 6F-TPA PI is attributed to the chemical modification of the carbonyl group in phthalimide moiety.

• Electrical & Electronic Materials
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• v.11 no.11
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• pp.37-45
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• 1998

In this paper, present status of super high-efficiency tandem solar cells has been reviewed and key issues for realizing super high-efficiency have also been discussed. In addition, the terretrial R&D activities of tandem cells, in the New Sunshine Program of MITI(Ministry of International Trade and Industry) and NEDO(New Energy and Industrial Technology Development Organization) in Japan are reviewed briefly. The mechanical stacked 3-junction cells of monolithically grown InGaP/GaAs 2-junction cells and InGaAs cells have reached the highest efficiency achieved in Japan of 33.3% at 1-sun AM1.5. This paper also reports high-efficiency InGaP/GaAs 2-junction solar cells with a world-record efficiency of 26.9% at AM0, 28$^{\circ}C$ and radiation damage recovery phenomena of the tandem cell performance due to minority-carrier injection under light illumination or forward bias, which causes defect annealing in InGaP top cells. Future prospects for realizing super-high efficiency and low-cost tandem solar cells are also described.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.131-139
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• 2000

A design of CPS attitude determination system is described in this paper. The designed system is a low cost high precision 24 channel single frequency GPS(Global Positioning System) receiver which provides a precise absolute heading and pitch (or roll) as well as a position. It uses commercial chip-set and consists of two RF parts, two signal-tracking parts, a processor, memory parts and I/Os. In order to determine precise attitude, accurate carrier phase measurements and an efficient integer ambiguity resolution method are required. To meet these requirements, a PLL (Phase Locked Loops) is designed, and an algorithm called ARCE (Ambiguity Resolution with Constraint Equation) is adopted. The hardware and software structure of the system will be described, and the performance evaluated under various conditions will be presented. The test results will promise that more reliable navigation system be possible because the system provides all navigational information such as position, velocity, time and attitude.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2436-2438
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• 2000

In this paper, field test results of a new efficient integer ambiguity resolution algorithm for precision Carrier Differential GPS(CDGPS) positioning are presented. The new algorithm is based on a reconfiguration Kalman filter which is designed to be used for the real-time precise positioning with low cost, single frequency, conventional C/A code GPS receivers. The tests were performed both in static and kinematic environment

• KSBB Journal
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• v.15 no.5
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• pp.514-520
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• 2000

Simultaneous nitrification and denitrification of ammonia and organic compounds-containing wastewater were performed in a fluidized bed biofilm reactor with polysulfone(PS) hollow fiber as a double layer biomass carrier. The PS hollow fiber fragment has both aerobic and anoxic environments for the nitrifiaction and denitrification at the shell and lumen-side respectively. The reactor system showed about 80% nitrification efficiency stably throughout the ammonia load conditions applied in the experiment. Denitrification efficiency depended on organic load and C/N ratio. High free ammonia concentration and low dissolved oxygen resulted in nitrite accumulation which leads to enhance organic carbon efficiency in denitrification when compared to nitrate denitrification. The simultaneous nitrification and denitrification reactor system has an economic advantages in reduced chemical cost of organic carbon for denitrification as well as compact reactor configuration.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.1
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• pp.46-57
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• 2008

Since the 90's, Korean Air transport market has been more expanded because of economic growth, the construction of airport infrastructure, and the advent of low cost carrier. Especially, the air traffic demand in Busan metropolitan area has been increasing steadily. Therefore, in this paper, we developed a new forecasting model which could expect the future air traffic demand in Busan area. This model is developed by regression analysis using social-economic variables such as GRDP, income, and the number of people, and dummy variables, for instance, KTX opening, Japan economic depression, SARS and so on. Result from demand forecasting by this new model suggests that the new airport system is needed in order to sustain the increasing air traffic demand in Busan area.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1105-1112
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• 2022

Field data monitoring systems such as renewable energy generation and smart farm integrated control are developing from PC and server to mobile first, and various wireless communication and application services have emerged with the development of IoT technology. Low-power wide-area networks are services optimized for low-power, low-capacity, and low-speed data transmission, and data collected in the field is transmitted to designated storage servers or cloud-based data platforms, enabling data monitoring. In this paper, we implement an IoT repeater that collects field data with a single device and transmits it to a wireless carrier cloud data flat using a low-power wide-area network, and a monitoring app using it. Using this, the system configuration is simpler, the cost of deployment and operation is lower, and effective data accumulation is possible.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.290.2-290.2
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• 2016

Recently, organic thin-film transistors have been widely researched for organic light-emitting diode panels, memory devices, logic circuits for flexible display because of its virtue of mechanical flexibility, low fabrication cost, low process temperature, and large area production. In order to achieve high performance OTFTs, increase in accumulation carrier mobility is a critical factor. Post-fabrication thermal annealing process has been known as one of the methods to achieve this by improving the crystal quality of organic semiconductor materials In this paper, we researched the properties of pentacene films with X-Ray Diffraction (XRD) and Atomic Force Microscope (AFM) analyses as different annealing temperature in N2 ambient. Electrical characterization of the pentacene based thin film transistor was also conducted by transfer length method (TLM) with different annealing temperature in Al- and Ti-pentacene junctions to confirm the Fermi level pinning phenomenon. For Al- and Ti-pentacene junctions, is was found that as the surface quality of the pentacene films changed as annealing temperature increased, the hole-barrier height (h-BH) that were controlled by Fermi level pinning were effectively reduced.

• Journal of Navigation and Port Research
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• v.33 no.2
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• pp.99-104
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• 2009

The Kinematic GPS is well known to provide a quite good accuracy of positioning within an level. Although kinematic GPS assures high precision measurement on the basis of an appreciable distance between a reference station and an observational point, it has measurable distance restriction within 20 km from a reference station on land. Therefore, it is necessary to make out a simple and low-cost method to obtain accurate positioning information without distance restriction In this paper, the velocity integration method to get the precise velocity information of a ship is explained. The experimental results of Zig-zag maneuver and Williamson turn as the ship's maneuvering test, and other experimental results of ship's movement during leaving and entering the port with low speed were shown. From the experimental results, ship's course, speed and position are compared with those obtained by kinematic-GPS, velocity integration method and dead reckoning position using Gyro-compass and Doppler-log.