• Journal of the Korean Institute of Gas
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• v.10 no.1 s.30
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• pp.7-12
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• 2006

The quantity of gas which can be supplied by LPG storage tank become a standard of selection. In the absence of the maximum evaporation rates from LPG storage tanks by tank capacity, continuation using time, air temperature, it is in a problem for the dissemination of LPG Storage tanks. In this paper, we showed the maximum evaporation rates from LPG storage tanks by tank capacity, air temperature, continuous using time and remaining level.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.3
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• pp.129-134
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• 2004

The Available Transfer Capability (ATC) is defined as the measure of the transfer capability remaining in the physical transmission network for further commercial activity above already committed uses. The ATC determination s related with Total Transfer Capability (TTC) and two reliability margins-Transmission Reliability Capability (TRM) and Capacity Benefit Margin(CBM) The TRM is the component of ATC that accounts for uncertainties and safety margins. Also the TRM is the amount of transmission capability necessary to ensure that the interconnected network is secure under a reasonable range of uncertainties in system conditions. The CBM is the translation of generator capacity reserve margin determined by the Load Serving Entities. This paper describes a method for determining the TTC and TRM to calculate the ATC in the Bulk power system (HL II). TTC and TRM are calculated using Power Transfer Distribution Factor (PTDF). PTDF is implemented to find generation quantifies without violating system security and to identify the most limiting facilities in determining the network’s TTC. Reactive power is also considered to more accurate TTC calculation. TRM is calculated by alternative cases. CBM is calculated by LOLE. This paper compares ATC and TRM using suggested PTDF with using CPF. The method is illustrated using the IEEE 24 bus RTS (MRTS) in case study.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.21-27
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• 2020

Lithium-ion batteries are the heart of energy-storing devices and electric vehicles. Owing to their superior qualities, such as high capacity and energy efficiency, they have become quite popular, resulting in an increased demand for failure/damage prevention and useable life maximization. To prevent failure in Lithium-ion batteries, improve their reliability, and ensure productivity, prognosticative measures such as condition monitoring through sensors, condition assessment for failure detection, and remaining useful life prediction through data-driven prognostics and health management approaches have become important topics for research. In this study, the residual useful life of Lithium-ion batteries was predicted using two efficient artificial recurrent neural networks-ong short-term memory (LSTM) and gated recurrent unit (GRU). The proposed approaches were compared for prognostics accuracy and cost-efficiency. It was determined that LSTM showed slightly higher accuracy, whereas GRUs have a computational advantage.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.711-732
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• 2019

Many unmanned aerial vehicle (UAV) applications have been employed for performing data collection in facilitating tasks such as surveillance and monitoring objectives in remote and dangerous environments. In light of the fact that most of the existing UAV relaying applications operate in conventional half-duplex (HD) mode, a full-duplex (FD) based UAV relay aided wireless network is investigated, in which the UAV relay helps forwarding information from the source (S) node to the destination (D). Since the activated UAV relays are always floating and flying in the air, its channel state information (CSI) as well as channel capacity is a time-variant parameter. Considering decode-and-forward (DF) relaying protocol in UAV relays, the cooperative relaying channel capacity is constrained by the relatively weaker one (i.e. in terms of signal-to-noise ratio (SNR) or signal-to-interference-plus-noise ratio (SINR)) between S-to-relay and relay-to-D links. The channel capacity can be optimized by adaptively optimizing the transmit power of S and/or UAV relay. Furthermore, a hybrid HD/FD mode is enabled in the proposed UAV relays for adaptively optimizing the channel utilization subject to the instantaneous CSI and/or remaining self-interference (SI) levels. Numerical results show that the channel capacity of the proposed UAV relay aided wireless networks can be maximized by adaptively responding to the influence of various real-time factors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.313-322
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• 2013

Batteries, which are being used as energy sources in various applications, tend to degrade, and their capacity declines with repeated charging and discharging cycles. A battery is considered to fail when it reaches 80% of its initial capacity. To predict this, prognosis techniques are attracting attention in recent years in the battery community. In this study, a method is proposed for estimating the battery health and predicting its remaining useful life (RUL) based on the slope of the charge voltage curve. During this process, a Bayesian framework is employed to manage various uncertainties, and a Particle Filter (PF) algorithm is applied to estimate the degradation of the model parameters and to predict the RUL in the form of a probability distribution. Two sets of test data-one from the NASA Ames Research Center and another from our own experiment-for an Li-ion battery are used for illustrating this technique. As a result of the study, it is concluded that the slope can be a good indicator of the battery health and PF is a useful tool for the reliable prediction of RUL.

• Journal of Nutrition and Health
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• v.39 no.7
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• pp.610-616
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• 2006

This study was performed to investigate the effect of whole mandarin, peel or pulp intake of Citrus unshiu Marc. on antioxidative capacity and oxidative DNA damage in fifteen-month aged rats. Forty-eight male Sprague-Dawley rats $(621.9\;{\pm}\;10.1\;g)$ were blocked into four groups according to their body weights as control group, whole mandarin powder group, mandarin peel powder group and mandarin pulp powder group. Rats were raised with diets containing 5% (w/w) freeze dried mandarin formulations for four weeks. Total polyphenol content and total antioxidant status (TAS) of mandarin formulations were highest in peel powder, followed by whole powder and then pulp powder. The 8-hydroxy2'-deoxyguanosine concentrations of kidney in all mandarin groups were significantly lower than that of control group, and that of mandarin peel group was much lower than whole powder and pulp groups. Plasma TAS levels of all the experimental groups were higher than that of control group, and among mandarin groups, peel group showed higher level than remaining two groups. In conclusion, all the mandarin formulations were effective on antioxidative capacity in fifteen-month aged rats, and the peel was most effective one among three formulations.

• Steel and Composite Structures
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• v.37 no.4
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• pp.481-492
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• 2020

Twenty-two corrosion-damaged columns were simulated through accelerated steel corrosion tests. Eight specimens were directly tested to failure under axial load, and the remaining specimens were tested after concrete-filled steel tube (CFST) strengthening. This study aimed to investigate the damage of RC columns after corrosion and their restoration and enhancement after strengthening. The research parameters included different corrosion degrees of RC columns, diameter-to-thickness ratio of steel tube and the strengthening concrete strength. Experimental results showed that CFST strengthening method could change the failure mode of corrosion-damaged RC columns from brittleness to ductility. In addition to the bearing capacity provided by the strengthening materials, it can also provide an extra 26.7% amplification because of the effective confinement provided by steel tubes. The influence of corrosion on reinforcement and concrete was quantitatively analysed and considered in the design formula. The proposed formula accurately predicted the bearing capacity of the strengthened columns with a maximum error of only 7.68%.

• Geomechanics and Engineering
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• v.22 no.2
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• pp.153-163
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• 2020

Laboratory experiments were conducted with two different soil conditions to investigate rainfall infiltration characteristics. The soil layer materials that were tested were weathered granite soil and weathered gneiss soil. Artificial rainfall of 80 mm/hr was reproduced through the use of a rainfall device, and the volumetric water content and matric suction were measured. In the case of the granite soil, the saturation velocity and the moving direction of the wetting front were fast and upward, respectively, whereas in the case of the weathered gneiss soil, the velocity and direction were slow and downward, respectively. Rainfall penetrated and saturated from the bottom to the top as the hydraulic conductivity of the granite soil was higher than the infiltration capacity of the artificial rainfall. In contrast, as the hydraulic conductivity of the gneiss soil was lower than the infiltration capacity of the rainfall, ponding occurred on the surface: part of the rainfall first infiltrated, with the remaining rainfall subsequently flowing out. The unsaturated hydraulic conductivity function of weathered soils was determined and analyzed with matric suction and the effective degree of saturation.

• The Journal of the Korea Contents Association
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• v.9 no.1
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• pp.23-29
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• 2009

This paper presents a capacity estimation of a storage system accumulating all data sensed during the lifetime of an individual human being. The calculation assumes modern data compression and data collection schemes based on wearable or implanted devices under ubiquitous environment. More than 76% of the storage area is found to be used for video data storage of common TV image quality. The remaining storage area is for data from other sensing organs including audio, taste, olfactory and tactual systems in addition to indexing information. Total storage area of around 600 tera bytes is needed to cover 100 years of human life including his fetal period.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.768-776
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• 2010

In this paper, we consider a linear precoding for the effective spectrum sharing in multiple-input multiple-output (MIMO) cognitive radio system where a secondary user coexists with primary users. The secondary user employs the orthogonal space time block coding (OSTBC) at the transmitter. Assuming a flat fading channel and a maximum-likelihood receiver, the optimum precoder forces transmission referred to as eigen-beamforming. In this paper, to eliminate the interference, ZF criterion based eigen-beamforming is not only used but also the precoding weight is chosen to cancel the remaining interference. This weight is computed by vector's likelihood. Simulation results show stronger interference suppression capability, better SER performance, and higher capacity than the algorithm in [4].