• Journal of Hydrogen and New Energy
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• v.35 no.1
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• pp.105-113
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• 2024

The natural gas dehydration process plays a central role in liquefying LNG. This study proposes two natural gas dehydration process systems applicable to liquefied natural gas (LNG) liquefaction plants, and compares and analyzes energy optimization measures through simulation. The fuel gas from feed stream (FFF) case, which requires additional equipment for gas circulation, disadvantages are design capacity and increased energy. On the other hand, the end flash gas (EFG) case has advantages such as low initial investment costs and no need for compressors, but has downsides such as increased power energy and the use of gas with different components. According to the process simulation results, the required energy is 33.22 MW for the FFF case and 32.86 MW for the EFG case, confirming 1.1% energy savings per unit time in the EFG case. Therefore, in terms of design pressure, capacity, device configuration, and required energy, the EFG case is relatively advantageous. However, further research is needed on the impact of changes in the composition of regenerated gas on the liquefaction process and the fuel gas system.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2839-2844
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• 2007

Micro hydraulic power generation of which the output is less or equal to a 100kW is attracting considerable attention. This is because of its small, simple, renewable, and abundant energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Moreover influences of pressure and velocity distributions with the variations of runner vane angle on turbine performance are investigated by using a commercial CFD code.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.7
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• pp.1044-1050
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• 2008

Most of developed countries, the consumption of fossil fuels has been serious problems that cause serious environment pollution like acid rain, global warming. Also, we have faced that limitation fossil fuels will be exhausted. Currently, small hydropower attracts attention because of its small, clean, renewable, and abundant energy resources to develop. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Tubular-turbine among small hydraulic power generation can be used at low-head. The purpose of this study is to research turbine's efficiency due to runner vane angle using CFD analysis.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.896-908
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• 2022

As a part of probabilistic risk (or safety) assessment (PRA or PSA) of nuclear power plants (NPPs), the primary role of human reliability analysis (HRA) is to provide credible estimations of the human error probabilities (HEPs) of safety-critical tasks. In this regard, it is vital to provide credible HEPs based on firm technical underpinnings including (but not limited to): (1) how to collect HRA data from available sources of information, and (2) how to inform HRA practitioners with the collected HRA data. Because of these necessities, the U.S. Nuclear Regulatory Commission and the Korea Atomic Energy Research Institute independently developed two dedicated HRA data collection systems, SACADA (Scenario Authoring, Characterization, And Debriefing Application) and HuREX (Human Reliability data EXtraction), respectively. These systems provide unique frameworks that can be used to secure HRA data from full-scope training simulators of NPPs (i.e., simulator data). In order to investigate the applicability of these two systems, two papers have been prepared with distinct purposes. The first paper, entitled "SACADA and HuREX: Part 1. The Use of SACADA and HuREX Systems to Collect Human Reliability Data", deals with technical issues pertaining to the collection of HRA data. This second paper explains how the two systems are able to inform HRA practitioners. To this end, the process of estimating HEPs is demonstrated based on feed-and-bleed operations using HRA data from the two systems.

• International Journal of High-Rise Buildings
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• v.4 no.2
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• pp.103-107
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• 2015

China's rapidly growing cities offer a unique opportunity to create highly sustainable communities. Architects and their clients, typically real estate developers, are highly focused on strategies that are effective at reducing energy and water usage at the scale of the individual building or within a master plan of multiple related buildings. However, a closer look at energy consumption reveals that transportation uses more energy worldwide than residential and commercial buildings combined. In light of this, it is appropriate that China is making massive investments in transportation infrastructure like heavy rail rapid transit and grade separated expressways, but the end result of these investments to date has been to enable people to live further from where they work and shop rather than closer - while simultaneously not creating walkable communities. Using positive and negative examples from Asia and the rest of the world, this article will investigate the specific urban design policies such as height limits, setbacks, land use restrictions, parking ratios, and parcel size which might change to enable the creation of truly sustainable communities for China's 21st century.

• Journal of Industrial Technology
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• v.30 no.A
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• pp.9-15
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• 2010

Recently, Smart Grid is a emerging topic in power and communication industry. Smart Grid refers to a evolution of the electricity supply infrastructure that monitors, protects, and intelligently optimize the operation of the interconnected elements including various type of generators, power grid, building/home automation system and end-use consumers. In order to successful implementation of Smart Grid, energy management function will be the key factor that coordinates and optimally controls the various loads according to the operating condition and environments, and the load patterns in residential and commercial building will be required as fundamental element for load management. In this study, we collects many types of energy usage data of electric appliances, analyze their load curves, and make the general load patterns for electrical appliance.

• Korean Journal of Organic Agriculture
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• v.29 no.4
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• pp.485-505
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• 2021

This study investigated consumers' perceptions and willingness to pay (WTP) for fruit and vegetables grown using renewable energy such as solar power, geothermal, waste heat from incinerators, hot water from thermal power plants. To this end, this study conducted an online survey of 1,050 consumers in Seoul, Gyeonggi, and the six metropolitan cities, and the main findings are as follows. First, most of the consumers perceived climate change as a serious problem, and 82.8% recognized the government's declaration of carbon zero was appropriate, which means that the government's active response to climate change is important. Second, on the pros and cons of the use of renewable energy when cultivating fruits and vegetables, opinions in favor of solar power were the highest, followed by geothermal heat, waste heat from waste incineration plants, and thermal power generation hot drainage. Third, at least 28.0% to 41.7% of consumers were willing to purchase fruits and vegetables using renewable energy more expensive than fruits grown using fossil energy such as kerosene. This means that the fruit and vegetable market using renewable energy is valuable as a niche market.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.6
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• pp.422-426
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• 2018

The lithium-ion battery pack of an electric vehicle (EV) deserves to be considered for an alternative use within smart-grid infrastructure. Despite the long automotive service life, EV batteries retain over 70~80% of their initial capacity. These battery packs must be managed for their reliability and safety. Therefore, a battery management system (BMS) should use specific algorithms to measure and estimate the status of the battery. Most importantly, the BMS of a grid-connected energy storage system (ESS) must ensure that the lithium-ion battery does not catch fire or explode due to an internal short from uncontrolled dendrite growth. In other words, the BMS of a lithium-ion battery pack should be capable of detecting the battery's status based on the electrochemical reaction continuously until the end of the battery's lifespan. In this paper, we propose a new protection algorithm for a dendritic lithium battery. The proposed algorithm has applied a parameter from battery pack aging results and has control power managing.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1166-1171
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• 2008

Despite of the increasing number of the application of drilled shaft piles in construction site, most studies on pile capacity have been focused on the side shear resistance. But it is common that the drilled shaft is socketed on the rock so as to use its bearing resistance. The prediction of the end movement and characteristics of the bearing capacity of the pile is great important as well. Therefore, a series of scaled model tests were carried out in order to study the characteristics of the bearing capacity on rock mass. The material of the test block was cement mortar which was mixed with sand, cement and water, and the size of a test block size was $240{\times}240{\times}240mm$. The axial load was applied by a miniaturized pile of 45mm in diameter and flat jacks and steel plate were used for confinement to simulate the real underground loading conditions. The relation of load-displacement was measured in various different conditions of rock mass such as strength, discontinuity of the rock mass and in-situ stress, so q-w curves of the end of the pile were presented for each condition.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3204-3220
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• 2021

We perform the task of video object segmentation by incorporating a conditional random field (CRF) and convolutional neural networks (CNNs). Most methods employ a CRF to refine a coarse output from fully convolutional networks. Others treat the inference process of the CRF as a recurrent neural network and then combine CNNs and the CRF into an end-to-end model for video object segmentation. In contrast to these methods, we propose a novel higher-order CRF model to solve the problem of video object segmentation. Specifically, we use CNNs to establish a higher-order dependence among pixels, and this dependence can provide critical global information for a segmentation model to enhance the global consistency of segmentation. In general, the optimization of the higher-order energy is extremely difficult. To make the problem tractable, we decompose the higher-order energy into two parts by utilizing auxiliary variables and then solve it by using an iterative process. We conduct quantitative and qualitative analyses on multiple datasets, and the proposed method achieves competitive results.