• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.323-332
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• 2019

Non-curable rubberized polymer asphalt waterproof coating materials in Korea and China are manufactured without advanced quality control techniques and common standard, And they are exposed consistent water leakage problems. Import and application of Korean waterproofing products and installation methods is difficult in the present situation as the Chinese standard(JC/T 2428) is different in nature with the Korean counterpart products, And quality assurance is inevitable based on mutual standards. In order to resolve this issue, alternatives such as using standards provided by the ISO (International Organization for Standardization) are generally employed, but there is no such ISO standard as a waterproof material for non-curable rubberized polymer asphalt material. Furthermore, it is unreasonable to develop the ISO standard for rubber asphalt seals for exchange in terms of time and cost. This study proposes that the establishment of a quality standard that can be applied for both countries will be required via an joint international standard that outlines the properties of materials if applied in mutual trade exchange.

• Journal of Chest Surgery
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• v.31 no.5
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• pp.481-487
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• 1998

The surgical management of acute type B dissection is controversial. The complexity of the repair usually requires a period of aortic cross-clamping exceeding 30 minutes, which can cause ischemic injury of the spinal cord. Several forms of distal perfusion have been considered for use to prevent this injury. To determine the safety and efficacy of a graft replacement with cardiopulmonary bypass in reparing acute dissection of descending thoracic aorta, we retrospectively reviewed our surgical experience treating 8 patients who had aortic dissection secondary to atherosclerosis, trauma, and carcinoma invasion. Cardiopulmonary bypass was performed with two aortic cannulas for simultaneous perfusion of the upper and lower body and one venous cannula for draining venous blood from the right atrium or inferior vena cava. Although aortic cross-clamp time was relatively long (average, 117.8 minutes; range, 47 to 180 minutes) in all cases, there was no neurologic deficit immediately after graft replacement for the aortic lesion. Two patients(25%) of relatively old age died on the postoperative 31st and 41st days, respectively, because of delayed postoperative complications, such as pulmonary abscess and adult respiratory distress syndrome. Although any of several maneuvers may be appropriate in managing dissection of the descending aorta, graft replacement with cardiopulmonary bypass during aortic cross-clamping may be a safe and effective method for the treatment of acute dissection of the descending thoracic aorta.

• Journal of Chest Surgery
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• v.29 no.11
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• pp.1212-1217
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• 1996

From Dec. 1993 to May 1995, 9 male and 5 female patients ranging in age from 25 to 65 years, were operated on for ascending aorta and/or aortic arch diseases. Six patients had acute aortic dissection, type A(ruptured in 4 cases); four had ruptured ascending aortic aneurysm; three had annuloaortic ectasia(ruptured in 1 cases); one had aortic arch aneurysm. The diagnostic procedures were echo cardiography and dynamic CT scan in all patients having acute dissection or rupture. The aortic angiography was performed in two cases. Indications for operations were rupture in five cases, acute aortic dissection in five cases, severe congestive heart failure in two cases, progressive aortic insufficiency in one case and impending rupture in one case. The emergent repair was performed in ten cases(71%). The surgical treatment consisted of 6 Cabrol operations, a Cabrol operation combined with arch replacement, a modified Bentall operation, 4 replacement of ascending aorta, a replacement of aortic arch, and a replacement of ascending aorta and aortic arch. Complications were a hypoxic encephalopathy, two atrial fibrillations, a sternal deheiscence, and a mediastinitis. Two early mortality(14%) were due to intractable bleeding and multiple organ failure, and one late mortality(7%) was due to ventricular arrhythmia. In eleven survivors, follow-up period was from 2 months to 12 months and the course was uneventful.

• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.37-46
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• 2013

Lane closure in freeway work zone due to maintenance and repair of freeway facilities results in abrupt change of traffic flow. Sudden change of traffic flow results strong interactions among vehicles, and reduces capacity compared to the ordinary traffic condition. Such capacity reduction is likely to cause congestion, traffic queues, and economic loss cost. This study aims to determine the base capacity for a short-term freeway work zone that can be used to establish a work zone schedule in advance without any traffic impact. First, the research collected detector data and schedule data of road works on all freeways in Korea. Second, the research determined 23 study sites finding the capacity values of work zone after matching two kinds of data. All study sites had varying characteristics regarding traffic flow being adjacent to work zone during road works. The capacity values were reviewed in terms of lane closure configuration, the types of work, and design speed. Finally, research proposed capacity values for a short-term freeway work zone with the design speeds of 100 kph, 120 kph and 1,700 pcphpl, 1,750 pcphpl, respectively.

• Journal of Life Science
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• v.17 no.12
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• pp.1723-1728
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• 2007

Rubus coreanus Miquel (RCM), a type of red raspberry, grows wild in Korea and China and its unripe fruit is used as a folk medicine for the treatment of impotence and as a diuretic. RCM was extracted with methanol and then further fractionated it into for different types. In this study, we investigated the antioxidant activity of a RCM extract (ext.) and its fraction (fr.). DPPH free radical scavenging activity assay, total polyphenols contents, total flavonoids contents assay were used to analyze antioxidant activity. The DPPH free radical scavenging activity $(RC_{50}:1.67{\mu}g/ml)$ and total polyphenols contents $(546.25{\mu}g/mg)$ were higher in butanol fraction than in other fr. And total flavonoids contents was higher in ethylacetate fr. $(141.78{\mu}g/mg)$. We applied comet assay to measure the DNA damage in the individual cells and exposed time course at $IC_{50}$. Comet assay is a rapid and sensitive fluorescent microscopic method to examine DNA damage and repair at individual cell level. The butanol fro from RCM significantly induced 54.12%, 57.95% of DNA damage after treated RCM for 8 hr. In conclus

• Journal of Life Science
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• v.18 no.4
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• pp.580-584
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• 2008

$O^6-methylguanine-DNA$ methyltransferase (MGMT) is a DNA repair protein that protects cells against the carcinogenic effects of alkylating agents. The loss of MGMT expression was commonly known due to hypermethylation of CpG islands in its promoter region. We evaluated the expression of MGMT by immunohistochemistry in order to examine the relationship between loss of MGMT expression and clinicopathological characteristics in 74 Korean patients with non-small cell lung cancers. Loss of MGMT was detected in 25 (33.8%) of 74 cases. The loss of MGMT expression was frequently seen in the adenocarcinoma than in the squamous cell carcinoma (p=0.021). However, there was no significant differences between loss of MGMT expression and other clinicopathological characteristics, including age, gender, smoking status, tumor size, tumor T stage, and lymph node metastasis (p>0.05). In conclusion, loss of MGMT expression was related with the histologic type of lung cancer. Further methylation study of MGMT promoter is needed to evaluate the relationships with immunohistochemical expression of MGMT and to clarify the role of MGMT in lung cancer.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.379-385
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• 2019

The purpose of this study is to investigate the damage status of wood sleepers on concrete track of urban transit at different locations and to analyze the causes of damages. In addition, the turnout maintenance history during the service period of about 24 years was analyzed in conjunction with the train passing tonnage and that was to compare the current repair history. The most frequent damage components were rail, tie plate, spike and wooden sleeper. And, the damage caused by the defect of the rail fastening system such as spike and tie plate according to the deformation of the wooden sleeper was analyzed as the main type of damage. As a result, the damage of track components of turnout system was on the increase because they are directly affected by the train passing tonnage. The supplementary points of the check sheet for current turnout maintenance were derived and the improvement proposal was suggested based on the research results.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.35-42
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• 2014

Thermal analysis properties and adhesive properties of self-healing agents were evaluated through differential scanning calorimetry, reaction heat measurement, and adhesive shear test. D1E0, D3E1, D1E1, D1E3, and D0E1, depending on the mixing ratio of DCPD and ENB, were considered as self-healing agents. The amount of Grubbs' catalyst, depending on the type of self-healing agents, was varied from 0.1 wt% to 1.5 wt%. In the case of DCPD, the polymerization reaction occurred faster and the stabilized adhesive strength increased as the amount of catalyst increased; however, a large amount of catalyst was required. ENB had excellent reactivity with a small amount of the catalyst; however, high reaction heat was observed at the early stage of polymerization. Thermal analysis properties and adhesive properties of self-healing agents can be controlled by varying a mixing ratio of DCPD and ENB. Among the self-healing agents used for this study, the D3E1 would be one of the most preferable candidates with regard to maximum adhesive strength, reaching time to maximum adhesive strength, stabilized adhesive strength, and reaction heat.

• Composites Research
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• v.34 no.5
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• pp.290-295
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• 2021

The application of lightweight structural composites to automobiles as a solution in line with global fuel economy regulations to curb global warming is recognized as a megatrend. This study was conducted to provide a technical approach that can respond to the issue of replacing parts that require conductive properties to maximize the application of thermoplastic carbon fiber reinforced plastics (CFRPs), which are advantageous in terms of repair, disposal and recycling. By utilizing the properties of the low-viscosity polymerizable oligomer matrix, it was possible to prepare a thermoplastic CFRP exhibiting excellent impregnation properties while uniformly mixing the conductive filler. Various carbon-based conductive fillers such as carbon black, carbon nanotubes, graphene nanoplatelets, graphite, and pitch-based carbon fibers were filled up to the maximum content, and electrical and thermal conductive properties of the fabricated composites were compared and studied. It was confirmed that the maximum incorporation of filler was the most important factor to control the conductive properties of the composites rather than the type or shape of the conductive carbon filler. Experimental results were observed in which it might be advantageous to apply a one-dimensional conductive carbon filler to improve electrical conductivity, whereas it might be advantageous to apply a two-dimensional conductive carbon filler to improve thermal conductivity. The results of this study can provide potential insight into the optimization of structural design for controlling the conductive properties of thermoplastic CFRPs.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.4
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• pp.253-263
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• 2021

Concrete structures are damaged by aging and external environmental factors. This type of damage is to appear in the form of cracks, to proceed in the form of spalling. Such concrete damage can act as the main cause of reducing the original design bearing capacity of the structure, and negatively affect the stability of the structure. If such damage continues, it may lead to a safety accident in the future, thus proper repair and reinforcement are required. To this end, an accurate and objective condition inspection of the structure must be performed, and for this inspection, a sensor technology capable of detecting damage area is required. For this reason, we propose a deep learning-based image processing algorithm that can detect spalling. To develop this, 298 spalling images were obtained, of which 253 images were used for training, and the remaining 45 images were used for testing. In addition, an improved loss function and data augmentation technique were applied to improve the detection performance. As a result, the detection performance of concrete spalling showed a mean intersection over union of 80.19%. In conclusion, we developed an algorithm to detect concrete spalling through a deep learning-based image processing technique, with an improved loss function and data augmentation technique. This technology is expected to be utilized for accurate inspection and diagnosis of structures in the future.