• Journal of Korean Society of Water and Wastewater
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• v.23 no.1
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• pp.57-67
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• 2009

Under the supply-oriented policy, efficiency and rationale have not been fully considered in planning of water supply facilities in Korea. As a case, this study shows that large-size systems are suffering from overcapacity problem of water treatment plants, and thus discusses what options should be applied to deal with inefficiency. Water demand of large-size systems has suddenly decreased for the last 10 years while water demand has been often assumed to increase at a regular rate in planning of plants according to excess capacity hypothesis. This inconsistency led to a serious overcapacity. In 2006, total excess capacity of nine large-size systems was more than 1.2 times as large as maximum daily demand of total customers in Seoul. However, their options are expected to stay ex post facto. To prepare the risk of overcapacity, and draw large benefits out of the plants, the authors and other professionals in Korea should further discuss the more adaptive method for prediction of water demand, and systems integration between a large-size system and adjoining systems.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.817-827
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• 2016

The resistance in series model has been frequently used for determination of various filtration resistance to correctly understand the membrane fouling behaviour in MBR (membrane bio-reactor) for wastewater treatment. The cake layer resistance ($R_c$) which is commonly determined by calculation of flux dataset that are obtained empirically before and after removing the cake layer on membrane surface. However, the calculated Rc values are very dependent on the cleaning methods adapted for removal of cake layer. This study investigated how the various cleaning options affect $R_c$. Seven different cleaning methods were employed: i) ultrasonication (100 W, 10 min), ii) ultrasonication (200 W, 60 min), iii) ultrasonication (400 W, 120 min), iv) water rinsing in a shaker (100 rpm, 10 min), v) water rinsing in a shaker (300 rpm, 60 min), vi) water rinsing, vii) sponge scrubbing. For the hydrophilic PES membrane, the cake layer removal efficiencies ranged from 64% to 10%, indicating that the removal of cake layer was highly dependent on the cleaning options. For the hydrophobic PVDF membrane, the cake layer removal efficiencies ranged from 79% to 97%. Consequently, a standardized method for cake layer removal to determine cake resistance ($R_c$) is needed for correct interpretation of the fouling phenomena.

• KIEAE Journal
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• v.10 no.2
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• pp.63-69
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• 2010

Diverse problems in wind environment has occurred through rapid urbanization and growth of high-rise building numbers, This study aims to propose the CFD (Computational Fluid Dynamics) simulation method and evaluation standard of wind environment in site planning of high rise apartment housing. The CFD simulation method proposed in this study is not existing detail simulation, but it is the method that a designer can correct and develop the design through immediate evaluation of design options in concept design phase. Therefore, the proposed CFD simulation method of wind environment in this study uses the BIM based CFD tool in which the 3D model in concept design phase can be used as for the CFD simulation. In this paper, the study examines existing evaluation standards of comfortableness level in wind environment for pedestrian near buildings, and selects new evaluation method which is possible to apply to the proposed CFD simulation method. In addition, it is to examine calculation time-spending and appropriate mesh division method for finding CFD result which is useful to find the best design options in aspect of wind environment in concept design phase. Furthermore, it proposes the wind environment evaluation method through BIM based CFD simulation.

• Journal of the Korean Institute of Rural Architecture
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• v.16 no.2
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• pp.9-18
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• 2014

UNL housing fair started 14 years ago and is hosted by the Daily Nebraskan. An annual event, the housing fair is expected to draw anywhere between 500 and 1,000 UNL students according to Daily nebraskan. It's manager coordinates with sponsors to determine each company's ad campaign for the every semester. Sponsors generally find the housing fair an effective tool because it brings them face-to-face with students especially inclined to seek out new living options. So this study is to analyse UNL housing fair to provide students potions. Students can learn about places to live off-campus by attending UNL housing fair. When housing fair is opened by Daily Nebraskan, the place is abuzz with students investigating off-campus living options. In addition, property management companies also are available to inform students of their policies and practices. Also this study is to analyse the housing life of UNL off-campus students. Therefore this study has been focused on the surrounding residential areas, their apartment sites and their apartments for UNL students.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.1
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• pp.33-41
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• 2013

Due to a high level of system ductility, steel moment resisting frames have been widely used for lateral force resisting structural systems in high seismic zones. Earthquake field investigations after Northridge earthquake in 1994 and Kobe earthquake in 1995 have reported that many steel moment resisting frames designed before 1990's had suffered significant damages and structural collapse. In this research, seismic performance assessment of steel moment resisting frames designed in accordance with the previous seismic provisions before 1990's was performed. Buckling-restrained braces and shear walls are considered for seismic retrofit of the reference buildings. Increasing stiffness and strength of the buildings using buckling-restrained braces and shear walls are considered as options to rehabilitate the damaged buildings. Probabilistic seismic performance assessment using fragility analysis results is used for the criteria for determining an appropriate seismic retrofit strategy. The fragility contour method can be used to provide an intial guideline to structural engineers when various structural retrofit options for the damaged buildings are available.

• Nuclear Engineering and Technology
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• v.38 no.2
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• pp.109-118
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• 2006

Various indirect power cycle options for a helium cooled gas cooled fast reactor (GFR) with particular focus on a supercritical $CO_2(SCO_2)$ indirect cycle are investigated as an alternative to a helium cooled direct cycle GFR. The balance of plant (BOP) options include helium-nitrogen Brayton cycle, supercritical water Rankine cycle, and $SCO_2$ recompression Brayton power cycle in three versions: (1) basic design with turbine inlet temperature of $550^{\circ}C$, (2) advanced design with turbine inlet temperature of $650^{\circ}C$ and (3) advanced design with the same turbine inlet temperature and reduced compressor inlet temperature. The indirect $SCO_2$ recompression cycle is found attractive since in addition to easier BOP maintenance it allows significant reduction of core outlet temperature, making design of the primary system easier while achieving very attractive efficiencies comparable to or slightly lower than, the efficiency of the reference GFR direct cycle design. In addition, the indirect cycle arrangement allows significant reduction of the GFR &proximate-containment& and the BOP for the $SCO_2$ cycle is very compact. Both these factors will lead to reduced capital cost.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.277-280
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• 2006

Most real world design evaluation and risk-based decision support combine quantitative and qualitative (linguistic) variables. Decision-making based on conventional mathematics that combines qualitative and quantitative concepts always exhibit difficulty in modelling actual problems. The successful selection process for choosing a design/procurement proposal is based on a high degree of technical integrity, safety levels and low costs in construction, corrective measures, maintenance, operation, inspection and preventive measures. However, the objectives of maximising the degree of technical performance, maximising the safety levels and minimising the costs incurred are usually in conflict, and the evaluation of the technical performance, safety and costs is always associated with uncertainties, especially for a novel system at the initial concept design stage. In this paper, a design-decision support framework using a composite structure methodology grounded in approximate reasoning approach and evidential reasoning method is suggested for design evaluation of machinery space of a ship engine room at the initial stages. It is a Multiple Attribute Decision-Making (MADM) or Multiple Criteria Decision Making (MCDM) framework, which provides a juxtaposition of cost, safety and technical performance of a system during evaluation to assist decision makers in selecting the winning design/procurement proposal that best satisfies the requirement in hand. An illustrative example is used to demonstrate the application of the proposed framework.

• Journal of Environmental Policy
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• v.12 no.3
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• pp.73-96
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• 2013

This aim is to explore the change of lifestyle caused by climate change and develop available adaptation policies against climate threats in Central Asia with the perspective of nomadism, which depends entirely on natural ecosystem. This article also attempts to pinpoint the dynamics between nomadic lifestyle and adaptation options for the resilience of nomadic community against climatic change threats. The adaptation options and opportunities as well as the impacts of land use change and nomadic pastoralists' lifestyle caused by climate change cannot be overemphasized. We suggest that nomadic lifestyle may aggravate the degree of vulnerability to climate change threats, whereas the capacity of nomad to successfully adapting to new environment in developing countries can be superior to that of settler lifestyle in one place in developed countries.

• Journal of Korean Elementary Science Education
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• v.30 no.4
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• pp.442-458
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• 2011

Digital textbook project is one of government-driven project to improve education due to integrating technology. Digital textbook need to be universally designed to fit for each student. Recently, universal design for learning( UDL) gains great attention as one of promising approaches for the development of the digital textbook through giving various options and flexibility to all students. UDL has three main principles, first provide multiple means of representation, second provide multiple means of action and expression, third provide multiple means of engagement. The purpose of the study is to analyze fourth grade science textbook according to three UDL guidelines and suggest implications to improve an existing science textbook. The results indicated that fourth grade science digital textbook has been partly applied UDL guidelines like implementing multimedia and multi- mode contents, learning and communication tools, and motivation strategies. But options which students can choose according to their needs and styles are insufficient and tools for expression and communication need to enhance for helping each student to overcome his/her obstacles for learning and need to be more and elaborate to support learner-centered science digital textbook.

• Journal of Yeungnam Medical Science
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• v.21 no.1
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• pp.12-22
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• 2004

The management of coincident glaucoma and cataract is not only a common clinical challenge but also an important research topic in the ophthalmic surgical field. The purpose of this article is to compare the different surgical options on the basis of their achievable postoperative intraocular pressure (IOP) control, success rates, and complication rates reported in the related literature, and to give advice on how to manage typical situations of patients with both glaucoma and cataract. Main topics were focused on indications and rationale of 3 surgical options (only cataract surgery first and later trabeculectomy, only trabeculectomy first and later cataract surgery, or simultaneous combined surgery). Modern clear corneal cataract extraction techniques resulted in a modest intermediate-term reduction of IOP and has considerably improved the success rates of combined glaucoma and cataract surgery. It also enabled future trabeculectomy to be successfully performed at a later date if necessary. Trabeculectomy alone achieved better IOP regulation than phacotrabeculectomy (combined surgery), but subsequent cataract surgery may compromise preexisting filtering bleb. Combined surgery augmented with mitomycin C achieved a lower IOP than combined surgery alone but had a higher complication rate. In conclusion, the choice of the preferred surgical method should be determined according to the target pressure, the amount of glaucomatous damage, and the grade of visual disturbance caused by the cataract. Phacotrabeculectomy with adjunctive mitomycin C offers visual improvement and achieves the best IOP lowering of all types of combined glaucoma and cataract surgery currently used but is associated with potentially sight-threatening complications.