• The Korean Journal of Physiology and Pharmacology
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• v.3 no.6
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• pp.587-595
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• 1999

This study was designed to investigate effects of calcium antagonists on endothelial and neuronal dysfunction of right coronary artery (RCA) induced by ischemia- reperfusion in anesthetized, open-chest pigs. After reperfusion, pigs were sacrificed and the RCA was rapidly dissected for in vitro experiments. Experimental groups were divided into 4 groups: control (C-RCA), ischemia-reperfusion only (I-RCA), verapamil infusion (VI-RCA) and nifedipine infusion (NI-RCA) group, respectively. The ischemia did not affect hemodynamics, mean arterial pressure, heart rate, LVdP/dtmax, and decreased RCA flow. Arterial pressure and heart rate during ischemia-reperfusion were decreased in VI-RCA and NI-RCA, and RCA flow during reperfusion was increased in NI-RCA. 5-Hydroxytryptamine (5-HT) produced concentration-dependent contractions in C-RCA. The 5-HT-induced contractions were potentiated in I-RCA and VI-RCA, but not in NI-RCA. Endothelium-dependent relaxation by calcium ionophore A23187 was inhibited in I-RCA and VI-RCA, and recovered in NI-RCA. Cyclic GMP contents were decreased in I-RCA group alone. Electrical field stimulation in C-RCA produced transient and frequency-dependent contractions and at 50 Hz caused biphasic contractions. The transient contractions were not affected by pretreatment with phentolamine and atropine, but the biphasic contraction was altered by the pretreatment. Both contractions were inhibited in I-RCA, and were partially recovered in VI-RCA and NI-RCA. Ischemia-reperfusion of RCA in pigs causes endothelial and neuronal dysfunctions, and calcium antagonists partially prevent both.

• Journal of Korea Technology Innovation Society
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• v.18 no.1
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• pp.126-150
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• 2015

Korea's experiences in the use and development of nuclear energy are recognized as a successful model as a developing country in the international nuclear community. With these experiences, Korea is able to contribute to the progress of Korean nuclear industry and international society as a nuclear advanced country. This paper reviews and analyzes the current situation and major issues in securing the international legal status of RCA Regional Office hosted by Korean Government since 2002. In this connection, major political environments and relevant issues in facilitating the revision of RCA Agreement and securing legal status of the RCARO are also investigated. It is essential to amend the 1987 RCA Agreement or to conclude the its supplementary agreement for the securing of the international legal status of RCA Regional Office at the RCA policy meeting prior to extension of the agreement in 2017 and after. It is recommended for the Korean Government to establish and operate the inter-ministry governmental task force teams to facilitate and support the required actions in the national and diplomatic actions in the regional level for the sustainable development of the RCA and RCA Regional Office.

• Toxicological Research
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• v.11 no.2
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• pp.193-197
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• 1995

Antibody-toxin conjugates, termed immunotoxins, are currently being evaluated as potential new anticancer agents and one of the most extensively studied toxins for construction of immunotoxin is ricin which exists in the seeds of castor bean, Ricinus communis. Another toxic lectin from castor bean is RCA (Ricinus communis agglutinin). Both toxins are very homologous. We reported the puriffcation procedure and biological properties of ricin from the Korean castor bean in another place and here we report those of RCA. The purified RCA shows three bands on denatured SDS PAGE while ricin shows two bands. On cultured $K_{562}$ cells ricin and RCA both inhibit the multiplication of cells extensively. $30{\mu}g/ml$ of ricin shows 73% of inhibition rate at day 4 compared to 68% in same condition of RCA. The inhibition of multiplication of cells are directly proportional to the concentration of toxins and the incubation period. In every case ricin was more toxic than RCA. The $LD_{50}$ dose of ricin on ICR mice was 60 ng at day 3 but that of RCA was $10{\mu}g$.

• Structural Engineering and Mechanics
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• v.69 no.4
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• pp.399-405
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• 2019

The present study assessed the reliability-based reinforcement ratio of FRP reinforced concrete structure applying recycled coarse aggregate (RCA) concrete. The statistical characteristics of FRP bars and RCA concrete were investigated from the previous literatures and the mean value and standard deviation were employed for the reliability analysis. The statistics can be regarded as the material uncertainty for configuring the probability distribution model. The target bridge structure is the railway bridge with double T-beam section. The replacement ratios of RCA were 0%, 30%, 50%, and 100%. From the probability distribution analysis, the reliability-based reinforcement ratios of FRP bars were assessed with four cases according to the replacement ratio of RCA. The reinforcement ratio of FRP bars at RCA 100% showed about 17.3% higher than the RCA 0%, where the compressive strength at RCA 100% decreased up to 27.5% than RCA 0%. It was found that the decreased effect of the compressive strength of RCA concrete could be compensated with increase of the reinforcement ratio of FRP bars. This relationship obtained by the reliability analysis can be utilized as a useful information in structural design for FRP bar reinforced concrete structures applying RCA concrete.

• International Journal of Concrete Structures and Materials
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• v.7 no.1
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• pp.61-69
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• 2013

This paper discusses the properties of RCA, the effects of RCA use on concrete material properties, and the large scale impact of RCA on structural members. The review study yielded the following findings in regards to concrete material properties: (1) replacing NA in concrete with RCA decreases the compressive strength, but yields comparable splitting tensile strength; (2) the modulus of rupture for RCA concrete was slightly less than that of conventional concrete, likely due to the weakened the interfacial transition zone from residual mortar; and (3) the modulus of elasticity is also lower than expected, caused by the more ductile aggregate. As far as the structural performance is concerned, beams with RCA did experience greater midspan deflections under a service load and smaller cracking moments. However, structural beams did not seem to be as affected by RCA content as materials tests. Most of all, the ultimate moment was moderately affected by RCA content. All in all, it is confirmed that the use of RCA is likely a viable option for structural use.

• Quality Improvement in Health Care
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• v.23 no.1
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• pp.11-23
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• 2017

Root Cause Analysis (RCA) has been widely used as a structured approach to investigate patient safety incidents. RCA helps identify what, how, and why something happened, therefore preventing recurrence of incidents. Since many quality tools can be used during RCA, various formats of RCA exist. If RCAs are performed incorrectly or incompletely, they are likely to produce unusable results. To address this issue, RCA software has been developed. The use of RCA software in investigating patient safety incidents may offer several advantages, such as potential reduction in learning time, shortening of the analytic process, facilitation of collection, analysis, and presentation of data and production of meaningful RCA reports. We introduced six healthcare RCA software and compared characteristics. Results from this study will enable the RCA team to choose proper RCA software.

• International Journal of Concrete Structures and Materials
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• v.8 no.2
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• pp.165-172
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• 2014

Recycled coarse aggregate (RCA) made from waste concrete is not a suitable structural material as it has high absorption of cement mortar, which adheres on the aggregate surface and on the tiny cracks thereon. Therefore, when using RCA made from waste concrete, much water must be added with the concrete, and slump loss occurs when transporting. Hence, its workability is significantly worse than that of other materials. In this study, surface of RCA was coated with water-soluble polycarboxylate (PC) dispersant so that its characteristics improved. Each possibility was evaluated: whether its slump loss can be controlled, by measuring its workability based on the elapsed time; and whether it can be used as a structural material, by measuring its strength. Moreover, the carbonation due to cement mortar adhesion was measured through a carbonation test. As a result, RCA coated with PC dispersant was found to be better than crushed coarse aggregate and RCA when the physical properties of the fresh concrete and the mechanical, durability of the hardened concrete were tested.

• Journal of Applied Reliability
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• v.16 no.1
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• pp.71-77
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• 2016

Purpose: Root cause analysis (RCA) refers to any systematic process that identifies the causes that contribute to a focus event. The immediate cause of a focus event is often a symptom of underlying causes and may not truly identify the root causes that should be identified and addressed. Currently many RCA tools are available. Different investigators use different RCA tools on different issues. No standardized or commonly agreed way to analyse root causes exists. The purpose of this study is to propose the methodology of RCA process commonly useable for various issues. Methods: The methodology of RCA process is produced based on the hybrid RCA tools. The effectiveness assessment matrix of actions through the root cause candidates is presented. Results: No single RCA technique proposed has so far covered all necessary aspects. A hybrid approach which combines the best features of various techniques is proposed. The effectiveness assessment matrix helps us to identify the root cause to correct or eliminate system vulnerabilities effectively. Conclusion: This hybrid approach and effectiveness assessment matrix can provide guidance of RCA process across many industries and situations.

• Quality Improvement in Health Care
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• v.24 no.1
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• pp.9-22
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• 2018

Purpose: The purpose of this study is to develop the Korean root cause analysis (RCA) software that can be used to systematically investigate underlying causes for preventing or reducing recurrence of patient safety incidents. Methods: We reviewed the existing guidelines and literatures on the RCA in order to figure out the RCA process. Also we examined the existing RCA softwares for investigating patient safety incidents to design the contents and interface of the RCA software. Based on the results of reviewing literatures and softwares, we developed a draft version of the Korean RCA software that can be easily used in Korean hospital settings by RCA teams. Results: The Korean RCA software consisted of several modules, which are modules for identifying patient safety incidents, organizing RCA team, collecting and analysing data, determining contributory factors and root causes, developing the action plans, and guiding evaluation. Conclusion: The Korean RCA software included optimized RCA process and structured logic for cause analysis. Thus even beginners in RCA are expected to easily use this software for investigating patient safety incidents. As software has been developed with the public financial support, it will be distributed free of charge. We hope that it will contribute to facilitating patient safety improvement activities in Korea.

• Korean Journal of Microbiology
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• v.44 no.2
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• pp.164-167
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• 2008

Recently, rolling circle amplification (RCA) technique has been widely focused in the field of gene amplification just like PCR method. We have developed RCA-mer, which is a web-based program searching for primer candidates from a given sequence. It can be applied to find primer lists in DNA amplification experiment based on RCA method. The RCA-mer compares 8-mer primer lists with user's input sequence such as vector, mitochondria, and microbial genome sequence. After calculating 8-mers existences in a given sequence, it displays matched and no-matched primer lists with their GC-contents. In addition to it, RCA-mer can search the existence of 8-mer primer lists in two sequences whether they are co-existed or not. Users can apply candidate primer lists to their researches which use RCA techniques.