• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.423-429
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• 2008

Microfiltration (MF) and ultrafiltration (UF) processes for removal of particulate materials (i.e., turbidity, microorganisms and viruses) have been used to produce drinking water with higher quality. As membrane filtration technique has become widely applied for drinking water treatment, the importance of membrane integrity test (MIT) has also been increasingly emphasized. The results of pressure decay test (PDT) were presented in the paper to monitor membrane integrity. In this paper the PDT was carried out with deliberately-defected membrane fibers to evaluate the sensitivity of PDT on membrane fiber damage. Variation of pressure decay rate and removal rate were investigated to evaluate the impact of defection (defection ratio) and pore size of membrane. The membrane integrity could be successfully monitored by the PDT. The pressure decay rate varied from $0.002{\sim}0.189kg_f/cm^2hr$ with the initial pressure ranged from 0.2 to $1.0kg_f/cm^2hr$. Higher initial pressure which provided with higher pressure decay rate was preferred to evaluate the defection of membrane fiber. As for the particle removal rate, the Log Removal Rate (LRV) of kaolin solution decreased significantly from 3.78 to 2.31 when one fiber out of 3,200 fibers was cut. The membranes with different pore size were tested to evaluate virus removal efficiency. The virus removal rate of the MF membrane ($0.1{\mu}m$) was about 30% although the poliovirus was smaller than the pore size of the MF membrane, indicating that the removal rate was much lower than Korea Water Works Association (KWWA) certificate LRV of 1.5.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.713-723
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• 2023

Climate change is significantly affecting coastal areas, and its impacts are expected to intensify. Recent studies on climate change adaptation and risk assessment in coastal regions increasingly integrate the concepts of recovery resilience and vulnerability. The aim of this study is to develop a measurement model for coastal hazard recovery resilience in the context of climate change adaptation. Before constructing the measurement model, a comprehensive literature review was conducted on coastal hazard recovery resilience, establishing a conceptual framework that included operational definitions for vulnerability and recovery resilience, along with several feedback mechanisms. The measurement model for coastal hazard recovery resilience comprised four metrics (MRV, LRV, RTSPV, and ND) and a Coastal Resilience Index (CRI). The developed indices were applied to domestic coastal erosion cases, and regional analyses were performed based on the index grades. The results revealed that the four recovery resilience metrics provided insights into the diverse characteristics of coastal erosion recovery resilience at each location. Mapping the composite indices of coastal resilience indicated that the areas along the East Sea exhibited relatively lower coastal erosion recovery resilience than the West and South Sea regions. The developed recovery resilience measurement model can serve as a tool for discussions on post-adaptation strategies and is applicable for determining policy priorities among different vulnerable regional groups.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.6
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• pp.801-806
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• 2004

The pilot study was conducted to (i) investigate the ability of various membrane integrity monitoring methods to detect changes in membrane integrity during operation, and (ii) determine the impact of membrane damage on microbial removal by microfiltration. Two variations of air pressure hold tests were investigated for direct integrity monitoring: pressure decay (PD) and diffusive air flow (DAF) tests which are most commonly used integrity tests for microfiltration (MF) membranes. Both PD and DAF tests were sensitive enough to detect one damaged fiber out of 66,000 under field operaing conditions. Indirect integrity monitoring such as turbidity and particle counting, however, responded poorly to defects in membrane systems. Microbial challenge study was performed using both new and deliberately damaged membranes, as well as varying the state of fouling of the membrane. This study demonstrated that MF membrane with nominal pore size $0.2{\mu}m$ was capable of removing various pathogens including coliform, spore, and cryptosporidium, at the level required by drinking water regulations, even when high operating pressures were applied. A sharp decrease in average log reduction value (LRV) was observed when one fiber was damaged, emphasizing the importance of membrane integrity in control of microbial contamination.

• Journal of The Korea Institute of Healthcare Architecture
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• v.24 no.4
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• pp.69-87
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• 2018

Purpose: This study has been started with the awareness that light and color are the main visual sensors of the multi-sensory stimulation environment to achieve the therapeutic environment for demented elderly. The purpose of this study therefore is for clarifying the application characteristics of therapeutic light and color for dementia care facilities. Methods: Internal and external literature reviews have been conducted for the investigation into a)disorders and visual system in demented elderly, b)therapeutic effects of light and color, c)heliotherapy, light therapy and color therapy to deduce the therapeutic characteristics of light and color for demented elderly, and finally into d)the application characteristics of it for dementia care facilities. Results: The application characteristics of the therapeutic light and color for dementia care facilities are classified into both qualitative and quantitative characteristics. Qualitative application characteristics of light represented using of daylight, using of lighting approximate to daylight, expansion of iluminance level, equality in iluminance Level, reduction of shadow, and as well as exclusion of blare. Quantitative application characteristics of it represented iluminance level, color temperature and color rendering index prescribed in international lighting standards. Qualitative application characteristics of color represented non-monochromatic color, color contrast, long wavelength of yellow-red colors, exclusion of short wavelength of blue colors and patterns, and as well as different colors for idenfication. Quantitative application characteristics of it represented kontrast(K) prescribed in DIN32975:2009 and light reflectance value(LRV) prescribed in BS8300:2009. Implications: To form dementia care facilities as therapeutic environment both qualitative and quantitative application characteristics of therapeutic light and color in dementia care facilities are needed.