• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.391-396
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• 2016

The absorption efficiency of amine $CO_2$ absorbent (KoSol-5) developed by KEPCO research institute was evaluated using a 0.1 MW test bed. The performance of post-combustion technology to capture two tons of $CO_2$ per day from a slipstream of the flue gas from a 500 MW coal-fired power station was first confirmed in Korea. Also the analysis of the absorbent regeneration energy was conducted to suggest the reliable data for the KoSol-5 absorbent performance. And we tested energy reduction effects by improving the absorption tower inter-cooling system. Overall results showed that the $CO_2$ removal rate met the technical guideline ($CO_2$ removal rate : 90%) suggested by IEA-GHG. Also the regeneration energy of the KoSol-5 showed about $3.05GJ/tonCO_2$ which was about 25% reduction in the regeneration energy compared to that of using the commercial absorbent MEA (Monoethanolamine). Based on current experiments, the KoSol-5 absorbent showed high efficiency for $CO_2$ capture. It is expected that the application of KoSol-5 to commercial scale $CO_2$ capture plants could dramatically reduce $CO_2$ capture costs.

• Journal of the Korea Society for Simulation
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• v.18 no.3
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• pp.73-82
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• 2009

Due to the many advantages including low price, low power consumption, and miniaturization, the CMOS camera has been utilized in many applications, including mobile phones, the automotive industry, medical sciences and sensoring, robotic controls, and research in the security field. In particular, the 360 degree omni-directional camera when utilized in multi-camera applications has displayed issues of software nature, interface communication management, delays, and a complicated image display control. Other issues include energy management problems, and miniaturization of a multi-camera in the hardware field. Traditional CMOS camera systems are comprised of an embedded system that consists of a high-performance MCU enabling a camera to send and receive images and a multi-layer system similar to an individual control system that consists of the camera's high performance Micro Controller Unit. We proposed the SL-AVS (Small Size/Low power Around-View System) to be able to control a camera while collecting image data using a high speed synchronization technique on the foundation of a single layer low performance MCU. It is an initial model of the omni-directional camera that takes images from a 360 view drawing from several CMOS camera utilizing a 110 degree view. We then connected a single MCU with four low-power CMOS cameras and implemented controls that include synchronization, controlling, and transmit/receive functions of individual camera compared with the traditional system. The synchronization of the respective cameras were controlled and then memorized by handling each interrupt through the MCU. We were able to improve the efficiency of data transmission that minimizes re-synchronization amongst a target, the CMOS camera, and the MCU. Further, depending on the choice of users, respective or groups of images divided into 4 domains were then provided with a target. We finally analyzed and compared the performance of the developed camera system including the synchronization and time of data transfer and image data loss, etc.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.98-103
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• 2010

The effect of plasma treatment on surface characteristics of polycarbonate (PC) films was investigated using low pressure plasma and atmospheric pressure plasma with oxygen and argon. Untreated PC has a contact angle of $82.31^{\circ}$ with de-ionized water which reduced to $9.17^{\circ}$ as the lowest value after being treated with a low pressure plasma treatment with oxygen. Increase of delivered powers such as RF and AC with a high frequency and gas flow rates was not effective to reduce contact angles dramatically but gave the trend of reducing gradually. The surface of PC treated with plasma shows a low contact angle but the contact angle increases rapidly according to the exposure time in air ambient. Oxygen plasma was more effective to generate the polar functional group regardless of the type of plasma. Conclusively, a low plasma treatment with oxygen is more recommendable when the hydrophilic surface of PC is required.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.1
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• pp.23-29
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• 1995

There are many articles about the HID lamps about it's characteristics and simulation methods for lamp design or ballast design. For the electronic ballasts of HID lamps, There are some problems caused by acoustic-resonance which destabilizes the arc of HID lamps. So, some studies suggest the methods to avoid it. For example, the methods suggested are high frequence driving over 100[kHz], and mixed frequence driving which alternates high frequence and low frequence, and squarewave driving etc. This study suggests the electronic ballast of HID lamps that solves the problems of acoustic-resonance, and can control the luminance by constant current boostes chopper of which frequence is 30[kHz] and by the squarewave driving of which frequence is 55.5[Hz.] As follows, we have the good electronic ballast for HID lamps which has the characteristics of a light weight, and a function of luminance control and a high quality luminosity and which saves electrical energy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.79-84
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• 2013

DC/DC switching power converters are commonly used to generate a regulated DC output voltage with high efficiency. The DC/DC converter is composed of a PWM-IC (pulse width modulation-integrated circuit) controller, a MOSFET (metal-oxide semiconductor field effect transistor), inductor, capacitor, etc. It is shown that the variation of threshold voltage and the offset voltage in the electrical characteristics of PWM-IC increase by radiation effects in TID (Total Ionizing Dose) testing at the low energy ${\gamma}$ rays using $^{60}Co$, and 4 heavy ions applied for SEL (Single Event Latch-up) make the PWM pulse unstable. Also, the output waveform for the given input in the DC/DC converter is observed by the simulation program with integrated circuit emphasis (SPICE). TID testing on PWM-IC is accomplished up to the total dose of 30 krad, and the cross section($cm^2$) versus LET($MeV/mg/cm^2$) in the PWM operation is studied at SEL testing after implementation of the controller board.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.6
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• pp.309-313
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• 2013

Silicon carbide (SiC) has recently drawn an enormous industrial interest because of its useful mechanical properties such as thermal resistance, abrasion resistance and thermal conductivity at high temperature. Especially, high purity SiC is applicable to the fields of power semiconductor and lighting emitting diode (LED). In this work, high purity carbon powders as raw material for high purity SiC were prepared by a RF induction thermal plasma. Dodecane ($C_{12}H_{26}$) as hydrocarbon liquid precursor has been utilized for synthesis of high purity carbon powders. It is found that the filtercollected carbon powders showed smaller particle size (10~20 nm) and low crystallinity compared to the reactor-collected carbon powders. The purities of reactor-collected and filter-collected carbon powders were 99.9997 % (5N7) and 99.9993 % (5N3), respectively. In addition, the impurities of carbon powders synthesized by RF induction thermal plasma were mainly originated from the surrounding environment.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.116-121
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• 2009

In the design of mobile entertainment systems for historical heritage sites, it is important to not only overcome technical challenges imposed by power requirements, computation limits, and connectivity, but to support group experiences and consider users preferences for situated media consumption. Cultural heritage sites provide an opportunity to entertain and educate the public through the use of mobile media. The proposed system implemented on a Java-enabled mobile phone provides both audio and visual content that is tailored by tracking user movement with GPS, collecting various user inputs and demographics, and allowing for socially acceptable eavesdropping via wireless networking. By designing for the spatial, personal, and social considerations of the environment, we aim to help users navigate the diverse topology of the space and consume the vast quantities of historical media.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.630-635
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• 2015

Since, the existing analog village broadcasting system had been affected by the climate change such as rain and had some problems likes as short range, it had been changed to the digital system and its standardizations required to be developed from now. In order to deploy the efficient digital wireless village broadcasting system, some propagation profiles as well as service coverages should be analyzed in various radio environments. In this paper, we have set up the transmission power as a parameter and estimated the service coverage area ratio as well as the area ratio interfered into the nearby village in rural, suburban and urban environments using spectrum management intelligence system (SMIS). This paper provides the basic data to establish a standard using the radio propagation characteristics and received power for village broadcasting system in various environments.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.5
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• pp.1089-1098
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• 2018

As the development of quantum computers becomes visible, the researches on post-quantum cryptography to alternate the present cryptography system have actively pursued. To substitute RSA and Elliptic Curve Cryptosystem, post-quantum cryptography must also consider side channel resistance in implementation. In this paper, we propose a side channel analysis on NTRU, based on the implementation made public in the NIST standardization. Unlike the previous analysis which exploits a thousands of traces, the proposed attack can recover the private key using a single power consumption trace. Our attack not only reduces the complexity of the attack but also gives more possibility to analyze a practical public key cryptosystem. Furthermore, we suggested the countermeasure against our attacks. Our countermeasure is much more efficient than existing implementation.

• Progress in Medical Physics
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• v.19 no.4
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• pp.219-226
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• 2008

In this study, we have conducted characterization of imaging performance for a flat panel digital X-ray detector using amorphous Selenium and a-Si TFT which was developed by the authors. The procedures for characterization were in concordance with internationally recommended standards such as IEC (international electrotechnical commission). The measures used for imaging performance characterization include response characteristic, modulation transfer function (MTF), detective quantum efficiency (DQE), noise power spectrum (NPS), and quantum limited performance. The measured DQEs at lowest and highest spatial frequencies were 40% and 25% respectively, which was superior to that of commercial products by overseas vendor. The MTF values were significantly superior to that of CR and indirect type DRs. The quantum limited performance showed the detector was limited by quantum noise at the entrance exposure level below 0.023 mR, which is sufficiently low for general X-ray examination.