• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1723-1729
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• 2021

Energy and directional distribution of neutrons at the Beloyarsk NPP workplaces is a subject of this study. Measurements of H^*(10) rate and neutron energy distribution were taken at 8 workplaces, which can be divided into three categories: work with spent or fresh nuclear fuel, work with radionuclide neutron sources, work at the rooms adjusted to reactors. The Hp(10) measurements were performed only at 6 out of 8 locations, due to the fact that long term placing of an effective neutron moderator in fresh nuclear fuel storage facility is forbidden. As a result of the research energy and direction distribution of the neutron fields at 8 locations of the Beloyarsk NPP workplaces was obtained. To estimate the accuracy of the H^*(10) rate and Hp (10) measurements the reference values of dose equivalents were calculated using energy and directional distribution. To take into account the difference between the reference values and the measured results site-specific correction factors were calculated.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.167.4-167
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• 2001

Accurate mathematical models of spacecraft components are an essential of spacecraft attitude control system design, analysis and simulation. Gyro is one of the most important spacecraft components used for attitude propagation and control. Gyro errors may seriously degrade the accuracy of the calculated spacecraft angular rate and of attitude estimates due to inherent drift and bias errors. In this paper, a detailed mathematical model of gyro containing the relationships for predicting spacecraft angular rate and disturbances is proposed. Stochastic model describing random drift behavior is discussed in frequency domain and time domain. In order to illustrate this approach, we analyze the behavior for Litton´s Space Inertial Reference Uint(SIRU).

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.746-748
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• 1988

A way of improving the transient performance is suggested for a class of model reference adaptive control systems. To increase the convergence rate of a model following error, an error feedback term is incorporated into the control law.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.39-43
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• 2013

The present study has been conducted to investigate the fire combustion properties and fire behavior of an IEEE-383 qualified flame retardant cable. The reference reaction rate and reference temperature which are commonly used in pyrolysis model of fire propagation process was obtained by the thermo-gravimetric analysis of the cable component materials. The mass fraction of FR-PVC sheath abruptly decreased near temperature range of $250{\sim}260^{\circ}C$ and its maximum reaction rate was about $2.58{\times}10^{-3}$[1/s]. For the XLPE insulation of the cable, the temperature causing maximum mass fraction change was ranged about $380{\sim}390^{\circ}C$ and it has reached to the maximum reaction rate of $5.10{\times}10^{-3}$[1/s]. The flame retardant cable was burned by a pilot flame meker buner and the burning behavior of the cable was observed during the fire test. Heat release rate of the flame retardant cable was measured by a laboratory scale oxygen consumption calorimeter and the mass loss rate of the cable was calculated by the measured cable mass during the burning test. The representative value of the effective heat of combustion was evaluated by the total released energy integrated by the measured heat release rate and burned mass. This study can contribute to study the electric cable fire and provide the pyrolysis properties for the computational modeling.

• Journal of Korea Water Resources Association
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• v.40 no.7
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• pp.571-583
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• 2007

The effects of climatic changes owing to urbanization, geographical and topographical conditions on Penman-Monteith reference evapotranspiration, and energy and aerodynamic terms of Penman-Monteith reference evapotranspiration have been studied. In this study, 56 climatological stations including the Seoul metropolis in South Korea have been selected, and the area of study site was set at $314\;km^2$. The climatological station is centrally located In the study area with a 10 km radius. The geographical and topographical characteristics of these sites were examined using GIS analysis. Land use status of the study area was also examined to estimate the extent of urbanization. The study results indicated that the variation of reference evapotranspiration rate is closely related to urbanization in most climatological stations. The level of change in reference evapotranspiration was higher in areas with higher urbanization rates. The change in reference evapotranspiration appears to be caused by temperature rises following heat island phenomena due to urbanization, and by the decrease in humidity, wind speed and sunshine duration due to the Increase in residential areas in urban districts. Especially, the humidity decrease causes a significant decrease in evapotranspiration rate. The study results showed that climatic change due to urbanization and proximity to the coast had the greatest effect on reference evapotranspiration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3C
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• pp.271-278
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• 2006

Rate-constrained coding is one of the many coding-efficiency oriented tools of H.264/AVC, but mode decision process of RDO(Rate distortion optimization) requires high computational complexity. Many fast mode decision algorithms have been proposed to reduce the computational complexity of mode decision. In this paper, we propose two algorithms for reduction of mode decision in H.264/AVC, which are the fast reference frame selection and selective intra prediction mode decision. Fast reference frame selection is efficient for inter predication and selective intra prediction mode decision can effectively reduce excessive calculation load of intra prediction mode decision. The simulation results showed that the proposed methods could reduce the encoding time of the overall sequences by 44.63% on average without any noticeable degradation of the coding efficiency.

• ALGAE
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• v.25 no.2
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• pp.89-97
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• 2010

To test the feasibility of using chlorophyll ${\alpha}$ fluorescence to assess the establishment success of seagrass transplants, photosynthetic characteristics of eelgrass Zostera marina transplants were measured using a Diving-pulsed amplitude modulation fluorometer in Jindong Bay on the southern coast of Korea. Maximum quantum yield ($F_v/F_m$), photosynthetic efficiency ($\alpha$), saturating irradiance ($E_k$) and maximum electron transport rate ($ETR_{max}$) of transplants and reference plants in a nearby transplant site were measured using the fluorometer for 5 months. Additionally, shoot morphology, individual shoot weight and productivity of transplants and reference plants were also monitored. Shoot height, leaf weight and productivity of transplants were significantly reduced during the first two or three months after transplantation compared to those of reference plants, and then increased to the levels of reference plants Characteristics of chlorophyll a fluorescence, including $F_v/F_m$, $\alpha$, $E_k$ and $ETR_{max}$ of transplants were also significantly reduced in the initial period, but recovered slightly sooner than shoot morphology or leaf productivity. These results indicated that after transplantation, Z. marina transplant photosynthesis recovered faster than shoot morphology, biomass or productivity. Thus, chlorophyll a fluorescence can be used as an indicator for early assessment of the status of eelgrass transplants without destructive sampling.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.1
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• pp.40-47
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• 2009

Recently, dynamic proxy caching has been proposed on the distributed environment so that media objects by user's requests can be served directly from the proxy without contacting the server. However, it makes caching challenging due to multimedia large sizes, low latency and continuous streaming demands of media objects. To solve the problems caused by streaming demands of media objects, this paper has been proposed the grouping scheme with fuzzy filtering based on partition and mapping. For partition and mapping, this paper divides media block segments into fixed partition reference block(R$_f$P) and variable partition reference block(R$_v$P). For semantic relationship, it makes fuzzy relationship to performs according to the fixed partition temporal synchronization(T$_f$) and variable partition temporal synchronization(T$_v$). Simulation results show that the proposed scheme makes streaming service efficiently with a high average request response time rate and cache hit rate and with a low delayed startup ratio compared with other schemes.

• Journal of the Korean Electrochemical Society
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• v.24 no.3
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• pp.42-51
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• 2021

Dissociation into Lithium-polysulfide electrolyte due to repeated cycles during the Lithium/Sulfur battery reaction is a major problem of reduced battery lifespan. We searched for a porous carbon with a large specific surface area that infiltrated S to prevent liquid Lithium-polysulfide from being dissolved in electrolyte, induce adsorption of Lithium-polysulfide, and further increase conductivity. In order to obtain porous carbon spheres with a large specific surface area, the carbon spheres of 1939 m²/g were raised to 2200 m²/g through additional KOH treatment. In addition, through heat treatment with S, a carbon sulfur compound containing 75 wt% of S was fabricate and material analysis was conducted on the possibility of using the cathode material. The electrochemical characteristics of the Reference (622; sulfur: 60%, conductive material: 20%, binder: 20%) pouch cell and the pouch cell made using 75wt% of carbon sulfur compound were analyzed. 75wt% of carbon sulfur pouch cell showed a 20% increase in lifespan and 10% improvement in C-rate compared to the Reference pouch cell after 50 cycles.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1183-1188
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• 2015

The FM-QCSK(: Frequency Modulated Quadrature Chaos Shift Keying) system is one of the most efficient systems in chaotic literature. One of the problems in this system is that half the bit duration is used for sending a chaotic reference signal which leads to increase the energy losses and reduces the data rate. In this paper, a novel scheme to enhance the performance of FM-QCSK system has been proposed. With the proposed scheme, FM-QCSK would be able to operate at higher data rates with reduced BER(: Bit Error Rate) and energy consumption. The basic modification introduced by the proposed scheme is the use one reference chaotic signal to transmit multi information signals in both in-phase and quadrature-phase channels. The results showed that the proposed scheme have achieved more than 3 dB gains in SNR for AWGN channels respectively at $BER=10^{-3}$ over the conventional one. The results also showed that the optimum number information signals can be send per reference signal is 8.