• Plant Journal
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• v.17 no.4
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• pp.35-40
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• 2021

In this study, a technical characteristic test was conducted on the gas turbine generator system of Seoincheon Combined cycle no.6 to derive and verify the model constants. As a result of the generator maximum/minimum reactive power limit test, the maximum reactive power limit is 80 MVar and the minimum is -30 MVar. The generator uses the GENROU model, the field time constant (T'do) is 4.077 s, and the inertial constant (H) is 5.461 P.U. Excitation system used ESST4B model to derive and verify model constants by simulating no-load 2% AVR step test, PSS modeling derived from PSS2A model constants, and simulated and compared measurement data measured when PSS off/on Did. The GGOV1 model was used for the governor-turbine, and the numerical stability of the determined governor-turbine model constant was verified by simulating a 10% governor step test through the PSS/E simulation program

• Journal of the Semiconductor & Display Technology
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• v.4 no.4 s.13
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• pp.13-17
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• 2005

The behavior of ozone in $NH_4OH$ was investigated to evaluate the solution as a cleaning chemical of the silicon wafer. The solubility of ozone in DI(Deionized) water increased as the oxygen flow-rate decreased and ozone generator power increased. Ozone in DI water showed solubility of 100 ppm or higher at room temperature. Ozone concentration was stabilized at the range of ${\pm}2ppm$ by controlling oxygen flow rate and ozone generator power. On the contrary, the solubility of ozone in $NH_4OH$ was very low and strongly depended on the concentration of $NH_4OH$ and pH. The redox potential of ozone was saturated within 10 minutes in DI water and decreased rapidly with the addition of $NH_4OH$. The behavior of ozone in $NH_4OH$ is well explained by redox potential calculation.

• Corrosion Science and Technology
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• v.18 no.4
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• pp.138-147
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• 2019

Pipes and components of the secondary system in the pressurized water reactor (PWR) are mainly comprised of manufactured carbon steel. Thus, the generated carbon steel corrosion products are transported into the steam generator and deposited, thereby deteriorating the integrity of the steam generator. Environmental condition in the secondary system of the PWRs differs across different locations. So, the corrosion rate and types of corrosion products depend on specific locations in the secondary system. In this study, the quantity and chemical compositions of corrosion products generated in various locations that vary in different temperatures and chemistry conditions were investigated. As a result of evaluating the PWR "Unit A" that is in current operation, the amount of corrosion products generated in the section of high temperature feedwater system was identified as the largest source in the secondary system. Major components of corrosion products were iron oxides such as magnetite, hematite, and lepidocrocite.

• Biomedical Engineering Letters
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• v.8 no.4
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• pp.383-392
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• 2018

For prompt gamma ray imaging for biomedical applications and environmental radiation monitoring, we propose herein a multiple-scattering Compton camera (MSCC). MSCC consists of three or more semiconductor layers with good energy resolution, and has potential for simultaneous detection and differentiation of multiple radio-isotopes based on the measured energies, as well as three-dimensional (3D) imaging of the radio-isotope distribution. In this study, we developed an analytic simulator and a 3D image generator for a MSCC, including the physical models of the radiation source emission and detection processes that can be utilized for geometry and performance prediction prior to the construction of a real system. The analytic simulator for a MSCC records coincidence detections of successive interactions in multiple detector layers. In the successive interaction processes, the emission direction of the incident gamma ray, the scattering angle, and the changed traveling path after the Compton scattering interaction in each detector, were determined by a conical surface uniform random number generator (RNG), and by a Klein-Nishina RNG. The 3D image generator has two functions: the recovery of the initial source energy spectrum and the 3D spatial distribution of the source. We evaluated the analytic simulator and image generator with two different energetic point radiation sources (Cs-137 and Co-60) and with an MSCC comprising three detector layers. The recovered initial energies of the incident radiations were well differentiated from the generated MSCC events. Correspondingly, we could obtain a multi-tracer image that combined the two differentiated images. The developed analytic simulator in this study emulated the randomness of the detection process of a multiple-scattering Compton camera, including the inherent degradation factors of the detectors, such as the limited spatial and energy resolutions. The Doppler-broadening effect owing to the momentum distribution of electrons in Compton scattering was not considered in the detection process because most interested isotopes for biomedical and environmental applications have high energies that are less sensitive to Doppler broadening. The analytic simulator and image generator for MSCC can be utilized to determine the optimal geometrical parameters, such as the distances between detectors and detector size, thus affecting the imaging performance of the Compton camera prior to the development of a real system.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.439-446
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• 2022

Efforts to reduce carbon dioxide(CO₂) emissions are being carried out due to climate environmental problems. Eco-friendly ships are also being developed, and various energy saving measures have been developed and applied. In ships, researches have been conducted in various fields such as electric propulsion system and energy saving devices. In addition, the development of ships using various renewable energy, such as kite using wind power and wind power generation, has been carried out. This paper proposes a plan to use renewable energy for ships by applying wave generators to small ships. In 2016, 130 small domestic ships drifted by sea due to discharge of starting storage batteries, and discharge cases accounted for the largest portion of the causes of domestic ship accidents. This is due to the excessive use of storage batteries for starting the main engine by departing in a weak storage battery state for small ships. Accordingly, two type wave power generators - opened flow wave power generator and enclosed vibrator type wave power generator - are developed for charging a starting storage battery when the ships are stationary at sea or port. Opened flow wave power generator utilizes the flow of fluid in the ship by using wave induced ship motion. Enclosed vibrator type wave power generator utilizes the pendulum kinetic energy located in a ship due to wave induced ship motion.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.83-88
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• 2008

The QPP interleaver has been gaining attention since it provides contention-free interleaving functionality for high speed parallel turbo decoders. In this paper we first show that the quadratic term $f_2x^2%K$ of $f(x)=(f_1x+f_2x^2)%K$, the address generating function, is periodic. We then introduce a low-power address generator which utilizes this periodic characteristic. This generator follows the conventional method to generate the interleaving addresses and also to save the quadratic term values during the first half of the first period. The saved values are then reused for generating further interleaved addresses, resulting in reduced number of logical operations. Power consumption is reduced by 27.38% in the design with fixed-K and 5.54% in the design with unfixed-K on average for various values of K, when compared with the traditional designs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.13-18
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• 2008

The global warming due to greenhouse gases is now the hottest issue all over the world. The world has been under $CO_2$ war since the Kyoto Protocol was opened for signature on December 11, 1997 in Kyoto, Japan. The Kyoto Protocol now covers more than 164 countries globally as of July 2006. Countries that ratify this protocol commit to reduce their $CO_2$ emissions, or engage in emissions trading. Korea is also expected to obey the Protocol starting in 2013, which will give a serious shock especially to the electric power industry. The power plants burning the fossil fuel produce more than 20 percent of national total $CO_2$ emission. This paper resents the calculation of the amount and cost of $CO_2$ emission w.r.t. generator MW output and its application to power system operation. The $CO_2$ emission function is derived using the input-output coefficients of the thermal power plants. The optimal power system operation considering $CO_2$ emission and its cost is demonstrated on a five-bus sample power system.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.62-67
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• 2019

This study was focused on the design and the performance analysis of integral Hot BoP for recovering waste heat from high-temperature exhaust gas in 2 kW class solid oxide fuel cell (SOFC). The hot BoP system was consisted of a catalytic combustor, air preheater and steam generator for burning the stack exhaust gas and for recovering waste heat. In the design of the system, the maximum possible heat transfer was calculated to analyze the heat distribution processes. The detail design of the air preheater and steam generator was carried out by solving the heat transfer equation. The hot BoP was fabricated as a single unit to reduce the heat loss. The simulated stack exhaust gas which considered SOFC operation was used to the performance test. In the hot BoP performance test, the heat transfer rate and system efficiency were measured under various heat loads. The combustibility with the equivalent ratio was analyzed by measuring CO emission of the exhaust gas. As a result, the thermal efficiency of the hot BoP was about 60% based on the standard heat load of 2 kW SOFC. CO emission of the exhaust gas rapidly decreased at an equivalent ratio of 0.25 or more.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1652-1655
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• 2008

Indoor air quality (IAQ) of subway becomes a key issue as the IAQ guidelines for public transportation published. There are two major sources regarding IAQ of subway; One is the sources coming from outdoor air and the other is sources of inside. Particulate matters smaller than 10 micrometer (PM10) and carbon dioxide ($CO_2$) are recognized as the one of the most severe pollutants in Korea. The source of PM10 is mainly coming from outdoor air, however, the source of $CO_2$ is coming from passengers exhaust. According to the guidelines, the level of $CO_2$ should be lower than 2500ppm for normal operating time and lower than 3500ppm for rush hour. In order to satisfy these guidelines, the volume of mechanical ventilation should be increase which consumes extra energy for heating or cooling. Therefore, the optimum volume of mechanical ventilation should be calculated for energy saving. In this study, we measured the natural ventilation rate by door-opening which can reduce the load of mechanical ventilation. The $CO_2$ generator and sensors were used to measure the change of $CO_2$ by periodic door-opening of subway.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.461-462
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• 2016

본 논문은 100kW 급 비상발전용 ESS 상용화 개발을 제안한다. 비상발전기란 전력계통이 정지되었을 때 발전장치를 구동시켜 전력을 생산하는 자가발전설비를 말한다. 제안하는 시스템은 2Level 전압형 100kW 급 비상발전용 ESS 로써 정상 시 계통 전원과 동기 운전을 수행하는 계통 연계형 전력변환장치이다. 수배전 수용가에 설치되어 운영이 가능하며 일반적인 ESS PCS 기능인 주파수 조정 (Frequency Regulation), 출력 안정화, 첨두부하 저감 (Peak Shaving), 부하평준화 (Load Leveling), 수요반응 (Demand Response)에 추가하여, 자가발전 (Black Start), 무효전력제어 등의 기능을 적용 하였다. 제안된 100kW 급 비상발전기용 ESS PCS 는 시뮬레이션 및 프로토 타입을 이용하여 성능을 검증하였다.