• Transactions of the Korean hydrogen and new energy society
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• v.29 no.4
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• pp.331-338
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• 2018

In this study, sulfonated PAES block copolymers have been synthesized via nucleophilic substitution reaction. Hydrophobic oligomer was prepared using 2,6-dihydroxynaphthalene and bis(4-chlorophenyl) sulfone, whereas hydrophilic oligomer was prepared using sulfonated bis(4-chlorophenyl) sulfone and bis(4-hydroxyphenyl) sulfone. The chemical structure of polymers was analyzed by $^1H$ NMR, FT-IR and GPC. The thermal properties of polymers were measured by TGA and DSC. The oxidative stability of membranes was investigated by Fenton's test. Furthermore, the proton conductivity of membrane was found to be 26 mS/cm at $90^{\circ}C$. All physiochemical properties suggest that fabricated membrane have a great potential for applications in PEMFC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3103-3120
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• 2015

This paper presents a single-phase energy metering chip with built-in calibration function to measure electric power quantities. The entire chip consists of an analog front end, a filter block, a computation engine, a calibration engine, and an external interface block. The key design issues are how to reduce the implementation costs of the computation engine from repeatedly used arithmetic operations and how to simplify calibration procedure and reduce calibration time. The proposed energy metering chip simplifies the computation engine using time-division multiplexed arithmetic units. It also provides a simple and fast calibration scheme by using integrated digital calibration functionality. The chip is fabricated with 0.18-μm six-layer metal CMOS process and housed in a 32-pin quad-flat no-leads (QFN) package. It operates at a clock speed of 4096 kHz and consumes 9.84 mW in 3.3 V supply.

• ETRI Journal
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• v.35 no.4
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• pp.677-686
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• 2013

In this paper, we first introduce a general architecture of an energy management system in a home area network based on a smart grid. Then, we propose an efficient scheduling method for home power usage. The home gateway (HG) receives the demand response (DR) information indicating the real-time electricity price, which is transferred to an energy management controller (EMC). Referring to the DR, the EMC achieves an optimal power scheduling scheme, which is delivered to each electric appliance by the HG. Accordingly, all appliances in the home operate automatically in the most cost-effective way possible. In our research, to avoid the high peak-to-average ratio (PAR) of power, we combine the real-time pricing model with the inclining block rate model. By adopting this combined pricing model, our proposed power scheduling method effectively reduces both the electricity cost and the PAR, ultimately strengthening the stability of the entire electricity system.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.4
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• pp.180-190
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• 2018

The preliminary study was carried out to utilize the rolling porous pendulum plate as a hybrid system combining blocking and extracting of wave energy. The Galerkin method suggested by Porter and Evans (1995) was used to solve the diffraction and radiation problems to obtain reflection and transmission coefficient, roll displacement, extracted power. The Galerkin method provides better convergence than the matched eigenfunction expansion method (MEEM), which improves the accuracy of the analytical solution even if the CPU time is shorter. The porous plate can not be said to be more effective than the impermeable plate in terms of wave energy extraction and wave blocking, but it has the advantage of reducing the wave load and exchanging seawater.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.827-839
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• 2021

Due to climate change and population growth, water scarcity is getting worse all over the world. Among various methods for desalination of seawater, the Multi-Effect Adsorptive Desalination method, which combines the existing Multi-Effect Desalination method and the Adsorptive Desalination method and can produce high-concentration-high-concentration freshwater, is emerging. Because the Multi-Effect Adsorptive Desalination method combines the two different methods, the system becomes complicated and the possibility of failure increases. Therefore, in this study, availability analysis was performed on the Multi-Effect Adsorptive Desalination process. A total of four types of reliability block diagrams were presented, and availability analysis was conducted based on them. The first form of a reliability block diagram is configured in series without any redundancy. The availability of the reliability block diagram composed of the serial system was found to be lower than the required availability. In order to increase availability, the redundancy to pumps and boiler are added to system. As a result of availability analysis, it was confirmed that designing desalination systems with redundancy to pump meets the 93% availability, which is typically required availability for various plants.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.559-561
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• 2022

인공지능 시대에 들어서면서 개인 맞춤형 환경을 제공하기 위하여 사람의 감정을 인식하고 교감하는 기술이 많이 발전되고 있다. 사람의 감정을 인식하는 방법으로는 얼굴, 음성, 신체 동작, 생체 신호 등이 있지만 이 중 가장 직관적이면서도 쉽게 접할 수 있는 것은 표정이다. 따라서, 본 논문에서는 정확도 높은 얼굴 감정 식별을 위해서 Convolution Block Attention Module(CBAM)의 각 Gate와 Residual Block, Skip Connection을 이용한 Identity- CBAM Module을 제안한다. CBAM의 각 Gate와 Residual Block을 이용하여 각각의 표정에 대한 핵심 특징 정보들을 강조하여 Context 한 모델로 변화시켜주는 효과를 가지게 하였으며 Skip-Connection을 이용하여 기울기 소실 및 폭발에 강인하게 해주는 모듈을 제안한다. AI-HUB의 한국인 감정 인식을 위한 복합 영상 데이터 세트를 이용하여 총 6개의 클래스로 구분하였으며, F1-Score, Accuracy 기준으로 Identity-CBAM 모듈을 적용하였을 때 Vanilla ResNet50, ResNet101 대비 F1-Score 0.4~2.7%, Accuracy 0.18~2.03%의 성능 향상을 달성하였다. 또한, Guided Backpropagation과 Guided GradCam을 통해 시각화하였을 때 중요 특징점들을 더 세밀하게 표현하는 것을 확인하였다. 결과적으로 이미지 내 표정 분류 Task에서 Vanilla ResNet50, ResNet101을 사용하는 것보다 Identity-CBAM Module을 함께 사용하는 것이 더 적합함을 입증하였다.

• Economic and Environmental Geology
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• v.49 no.1
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• pp.31-41
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• 2016

A program code was developed to calculate block hydraulic conductivity of the 2-D DFN(discrete fracture network) system based on equivalent pipe network, and implemented to examine the effect of joint orientation distribution on the hydraulic characteristics of fractured rock masses through numerical experiments. A rock block of size $32m{\times}32m$ was used to generate the DFN systems using two joint sets with fixed input parameters of joint frequency and gamma distributed joint size, and various normal distributed joint trend. DFN blocks of size $20m{\times}20m$ were selected from center of the $32m{\times}32m$ blocks to avoid boundary effect. Twelve fluid flow directions were chosen every $30^{\circ}$ starting at $0^{\circ}$. The directional block conductivity including the theoretical block conductivity, principal conductivity tensor and average block conductivity were estimated for generated 180 2-D DFN blocks. The effect of joint orientation distribution on block hydraulic conductivity and chance for the equivalent continuum behavior of the 2-D DFN system were found to increase with the decrease of mean intersection angle of the two joint sets. The effect of variability of joint orientation on block hydraulic conductivity could not be ignored for the DFN having low intersection angle between two joint sets.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.6
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• pp.818-822
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• 2003

In order to investigate the effect of different sources of energy on intake and nutrient utilization from urea molasses mineral block (UMMB), rumen fermentation pattern and blood biochemical constituents, 18 intact and 9 rumen fistulated male Murrah buffaloes aged about 3 years and average weight 310.8 kg were randomly allocated into three groups of 9 animals in each, thus each group having 6 intact and three rumen fistulated buffaloes. All animals were fed individually for 90 days. All buffaloes were offered wheat straw as basal roughage and urea molasses mineral block for free choice of licking. Three different energy sources viz., barley grain, (group I), maize grain (group II) and jowar green (group III) were offered to meet their nutrient requirement as per Kearl (1982). At the end of feeding trial, a metabolism trial of 7 days duration was carried out on intact animals to determine the digestibility of nutrients. Rumen fermentation studies were carried out on rumen fistulated animals. After the metabolism trial blood was collected from intact animals to estimate the nitrogen constituents in blood serum of animals fed on different sources of energy. Results revealed no significant difference in the intake of UMMB in three groups. Similarly, the intake of DM (kg), DCP (g) and TDN (kg) per day was similar in three groups statistically. The apparent digestibility of dry matter (DM), organic matter (OM), ether extract (EE) and nitrogen free extract (NFE) was significantly (p<0.05) more in group II than group III, whereas the digestibility of DM, OM and NFE was similar in group I and II. The digestibility of crude fiber (CF) and all the fiber fractions i.e. NDF, ADF, cellulose and hemicellulose was alike in 3 groups. Nitrogen balance (g/d) was significantly (p<0.05) more in group III as compared to group I and II, which were alike statistically, though the N intake (g/d) was similar in 3 groups but N balance (g/d) was significantly (p<0.05) less in group III as compared to other 2 groups. Significantly (p<0.05) higher concentration of total volatile fatty acids (TVFA), total nitrogen (TN) and its fractions were observed in group I and II as compared to group III. There was no effect on rumen pH, rumen volume and digesta flow rate due to different sources of energy in 3 groups. Similarly the blood serum biochemical parameters (NH3-N, urea-N and total protein) were statistically identical in 3 groups.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.162-167
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• 1999

In Auxiliary block of High speed train Power factor correction and Harmonics reduction is very important issue for efficient energy transport. The GTO-equipped PWM converter is used for traction untill resently. but the rising power capability of IGBTs resently allows to build IGBT-equipped PWM converter with a considerably increases switching frequency. In this paper presents switching pattern, control method, operation mode and tuned filter to reduce dc link voltage ripple for paralleled converter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.3
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• pp.289-293
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• 2013

In the noncoherent methods for UWB-IR (ultra-wideband impulse radio), block coded modulation (BCM) is better than the transmitted reference (TR) systems in terms of the energy efficiency and data rate. However, even BCM suffers from the performance degradation in the presence of strong inter-frame interference and inter symbol interference. We propose the transmitted reference based on the BCM (TR-BCM) which is the hybrid system of TR and BCM. Performance evaluation shows that the performance of TR-BCM is better than that of BCM in the high SNR range.