• Title/Summary/Keyword: mitigate

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USING LOW-VOLTAGE-HIGH-FREQUENCY ELECTRIC FIELD TO MITIGATE MINERAL FOULING IN A HEAT EXCHANGER

  • Tijing, Leonard D.;Pak, Bock-Choon;Baek, Byung-Joon;Lee, Dong-Hwan;Cho, Young-I.
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2315-2320
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    • 2007
  • This paper presents an investigative study on the efficacy of a new physical water treatment (PWT) technology using an oscillating electric field to mitigate mineral fouling in heat exchangers. Parallel graphite electrode plates immersed in water were used to generate the electric field directly in water. Artificial hard water at 500 ppm hardness was used in all fouling tests. The inlet temperatures were maintained at 23.5${\pm}$0.5$^{\circ}C$ and 85${\pm}$0.5$^{\circ}C$ for cold and hot water sides, respectively. The results at a cold water-side velocity of 0.3 m/s showed a 16-60% drop in fouling resistances from the baseline test depending on the frequency of the electric field for the PWT-treated cases.

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A Study on the Life Cycle Energy and $CO_2$ in the Apartment Housings (공동주택의 라이프사이클 에너지와 이산화탄소 추정에 관한 연구)

  • Lee, Kang-Hee;Chae, Chang-U
    • Journal of the Korean housing association
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    • v.19 no.4
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    • pp.89-96
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    • 2008
  • The environment has played a key role to improve the living condition and develop the industry. In building industries, we should consider the environment and mitigate the environmental affect. For mitigating the its affect, various areas of building technology have been developed and applied into filed work. In addition, the process in applying into field requires to conduct the assessment of the environmental affect and improve its applied technology. A lot of assessment methods are proposed in evaluate the building condition such as post-occupancy evaluation, life cycle management and life cycle assessment. Among these assessment methods, life cycle assessment is effectively utilized the environmental affect in building life cycle. Therefore, this paper aimed at analyzing the energy consumption and $CO_2$ emission in building life cycle, using the life cycle assessment and application of the example in apartment housing. This study shows that the maintenance and the production of building materials stage shares most of the amount of energy consumption and $CO_2$ emission and therefore plays an important role to planning the building in terms of the life cycle. Second, the other stages brings about a very small amount. It is important to decide the building shape and contents to mitigate the environmental affect in terms of material, volume, the pattern of the energy use and others.

A Study on the Mitigation Policies for Urban Heat Island (도시열섬 완화를 위한 제도개선)

  • Suh, Eung Chul
    • KIEAE Journal
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    • v.7 no.2
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    • pp.17-23
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    • 2007
  • While heat island has been recognized as an unique environmental nuisance in cities, the phenomenon tends to be regarded as an inevitable side effect on urbanization. Recently the nature of the heat island has been disclosed and efforts for the remedy have been discussed in many ways. Some pioneering actions have been taken to mitigate the strength of the heat island's intensity in several countries. After studies for the heat island and speculations on current pilot policies of 3 different countries has been done, mitigation policies for heat island has been suggested as followings. 1. Preservation of natural topography is essential because latent energy consumption(evapotranspiration) from the site is the single most important factor to mitigate the energy surplus caused by urban heat island. 2. Because current national zoning ordinance or building law can not effectively control the site specific local environment, heat island policy should be established or employed at local level. 3. Incentives for the mitigation should be adopted on the process of implementation because environment is public concern. 4. Wind can easily dissipate energy surplus which is the major driving force for heat island. Therefore local wind, the direction and intensity should be sustained and sometimes facilitated fully through policies.

Anti-interference Methods using Vector-based GPS Receiver Mode

  • Viet, Hoan Nguyen;Lee, Suk-Hwan;Kwon, Ki-Ryong
    • Journal of Korea Multimedia Society
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    • v.21 no.5
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    • pp.545-557
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    • 2018
  • The Global Positioning System (GPS) has become popular and widely used in many fields from military to civilian applications. However, GPS signals are suffered from interference due to its weak signal over wireless channel. There are many types of interference, such as jamming, blocking multipath, and spoofing, which can mislead the operation of GPS receiver. In this paper, vector-based tracking loop model with integrity check is proposed to detect and mitigate the harmful effect of interference on GPS receiver operation. The suggested methods are implemented in the tracking loop of GPS receiver. As a first method, integrity check with carrier-to-noise ratio (C/No) monitoring technique is applied to detect the presence of interference and prevent contaminated channels out of tracking channels to calculate position. As a second method, a vector-based tracking loop using Extended Kalman Filter with adaptive noise covariance according to C/No monitoring results. The proposed methods have been implemented on simulated dataset. The results demonstrates that the suggested methods significantly mitigate interference of Additive White Gaussian Noise (AWGN) and improve position calculation by 44%.

A Study on an Operation Strategy of Dual-Infeed HVDC System

  • Kim, Chan-Ki;Jang, Gilsoo
    • Journal of Electrical Engineering and Technology
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    • v.12 no.1
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    • pp.45-52
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    • 2017
  • This paper deals with the operation strategy of reactive power in a multi-infeed HVDC (MIHVDC) system, in which several converters are connected to the same or nearby separate AC buses. The potential problems concerning a MIHVDC system when feeding a weak AC network are as follows: the need for coordination of the recovery control, the possibility of voltage instability or low quality of the area connected to the MIHVDC system, and the risk of mutual commutation failures. These problems in MIHVDC systems are similar to those in single-infeed HVDC (SIHVDC) systems, but the differences with the phenomenon of the SIHVDC system are the interactions between converters. The main reason for the potential problems of HVDC systems (MIHVDC or SIHVDC) is voltage variation; therefore, to mitigate the voltage variations, the performances of the HVDC system should be enhanced. Consequently, to mitigate the potential problems of MIHVDC systems, several solutions are suggested in this study, including installing STATCOM and installing a line arrester on the tower. The study results will be applied to a multi-infeed HVDC system in Korea.

Applications of Sugarcane by-products to mitigate climate change in Ethiopia

  • Habte, Lulit;Mulatu, Dure;Ahn, Ji Whan
    • Journal of Energy Engineering
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    • v.27 no.3
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    • pp.36-40
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    • 2018
  • Climate change is one of the major issues in both the developed and developing world. Greenhouse gas (GHG) emission is one of the implications for climate change. It is increasing rapidly. Although the emission is much less when compared to the rest of the world, Ethiopia has also faced this global issue. The major source for GHG emission in Ethiopia is agriculture. Therefore, the agriculture sector has to be given more attention in Ethiopia. To overcome the problem, Climate-Resilient Green Economy (CRGE) strategy has been initiated. One way of executing this target is to create a sustainable and environmentally friendly pathway to use agricultural byproducts. Sugarcane is one of the major plants in Ethiopia. Its byproducts are bagasse, molasses, and press mud. Since it is a waste product, it is economical and creates a sustainable and green environment by reducing GHG emissions. Sugarcane byproducts have versatile applications like as fuel, as cement replacing material, as a mitigation for expansive soils, as biosorbent for the treatment of water and wastewater and also as a wood material. However, Ethiopia has not used this byproduct massively as it is readily available. This paper reviews the possible applications of sugarcane byproducts to mitigate climate change.

DroidSecure: A Technique to Mitigate Privilege Escalation in Android Application (DroidSecure: 안드로이드 어플리케이션 권한 상승 완화를 위한 기술에 대한 연구)

  • Nguyen-Vu, Long;Jung, Souhwan
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.26 no.1
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    • pp.169-176
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    • 2016
  • Android platform is designed to be user-friendly, yet sometimes its convenience introduces vulnerabilities that normal users cannot justify. In this paper, after making an overview of popular open source analysis tools for android applications, we point out the dangerous use of Permission Group in current Google Policy, and suggest a technique to mitigate the risks of privilege escalation that attackers are taking advantage of. By conducting the investigation of 21,064 malware samples, we conclude that the proposed technique is considered effective in detecting insecure application update, as well as giving users the heads-up in security awareness.