• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.407-410
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• 2006

Studies were performed on evaluating the applicability of activated carbon bugs on dye tracer tests as tracer detectors by using its adsorption isotherm of the grained activated carbon. We preliminary conducted several standard adsorption and extraction tests and obtained the relationship between standard dye solution and detected concentrations from activated carbon samples in dry and wet conditions. the slopes of the regression line were 0.71 for wet condition and 0.74 for dried one. Field dye tracer tests were performed in a karst area, where several faults occur along a stream and pass the test area. We sampled water samples and activated carbon samples at three points in Hwangji Pond, where groundwater outflows from the karst conduit. According to the results of breakthrough curve analysis, the regional flow along the conduit, which is assumed to cause a karst conduit, was estimated as 0.18 m/day. The relationship between the concentrations of water sample and extracted activated carbon bugs shows the similar slopes with those from standard solution tests. This suggests that activated carbon could be useful as a dye tracer detector because the extraced concentration can be quantified.

• Journal of the Korean Solar Energy Society
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• v.24 no.3
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• pp.27-38
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• 2004

A numerical investigation has been carried out for a solar system, which consists of all glass solar vacuum tubes Water is heated as it flows through the coaxial fluid conduit inserted in each tube. The space between the exterior of the fluid conduit and the glass tube is filled with antifreeze solution. This is to facilitate heat transfer from the solar heated absorber surface to water and to prevent the functional problems due to freezing in frigid weather conditions. A one-dimensional steady state model is fully described which will be used to develop three-dimensional model using STAR-CD. These models could be used efficiently in designing all-glass solar collector tubes with different geometrical parameters other than those considered in the present analysis. Results show good agreement when compared with other experimental data demonstrating the reliability of the present model.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.567-570
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• 2006

A numerical study has been carried out for a solar water heater which consists of double skin solar vacuum tubes. Water is heated as it flows through the coaxial fluid conduit inserted in each tube. The space between the exterior of the fluid conduit and the glass tube is tilled with antifreeze solution. This is to facilitate heat transfer from the solar heated absorber surface to water and to prevent the functional problems due to freezing in frigid weather conditions. A one-dimensional steady state model is fully described which will be used to develop three-dimensional model using STAR-CD. These models could be used efficiently in designing double skin solar collector tubes with different geometrical parameters other than those considered in the present analysis. Results show a good agreement when compared with other experimental data demonstrating the reliability of the one-dimensional model employed.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.629-636
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• 2001

Network is changed from voice-based network into multimedia-based network by development of communication technology and multimedia service. We need a large bandwidth for multimedia service. The optical fiber is a more suitable medium than existing copper-based cable for large bandwidth. But, it is so expensive than copper-based cable. So, Minimizing total cost becomes a more important concept. In order to construct a minimum cost network, we have to consider existing conduits in network. On the other hand, optical fiber network allows that larger amount of traffic can be transmitted than copper-based network does. However, a failure of a node or link can make a serious damage to the network service. Thus, we have to get multiple paths to support continuous service even if a loss of failure occurs in some point of the network. The network survivability problem is to design the network that can provide reliable service to customers anytime with minimum total cost. In an existing solution of the network survivability problem with conduits, a conduit is considered only one time. But, the conduit is reusable if the network satisfies the required survivability. Proposed algorithm can more effectively considered already existed conduit. Network survivability and edge cost is predetermined. The proposed algorithm finds the best solution by conduit sharing within the limits of network survivability. According to the simulation result, the proposed method can decrease 7% of total cost than an existing method by effective conduits adaption.

• Journal of Chest Surgery
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• v.46 no.6
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• pp.413-425
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• 2013

Background: Graft vessel preservation solution in coronary artery bypass surgery is used to maintain the graft conduit in optimal condition during the perioperative period. Nafamostat mesilate (NM) has anticoagulation and anti-inflammatory properties. Therefore, we investigated NM as a conduit preservative agent and compared it to papaverine. Methods: Sprague-Dawley (SD) rat thoracic aortas were examined for their contraction-relaxation ability using phenylephrine (PE) and acetylcholine (ACh) following preincubation with papaverine and NM in standard classical organ baths. Human umbilical vein endothelial cells (HUVECs) were cultured to check for the endothelial cell viability. Histopathological examination and terminal deoxynucleotidyl transferase dUTP nick end labeling assay were performed on the thoracic aortas of SD rats. Results: The anti-contraction effects of papaverine were superior to those of NM at PE (p<0.05). The relaxation effect of NM on ACh-induced vasodilatation was not statistically different from that of papaverine. Viability assays using HUVECs showed endothelial cell survival rates of >90% in various concentrations of both NM and papaverine. A histopathological study showed a protective effect against necrosis and apoptosis (p<0.05) in the NM group. Conclusion: NM exhibited good vascular relaxation and a reasonable anti-vasocontraction effect with a better cell protecting effect than papaverine; therefore, we concluded that NM is a good potential conduit preserving agent.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1991.10a
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• pp.464-464
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• 1991

We address the problem of designing a physical CATV network with switched-star topology in which the broadband interactive service is provided. There are two types of decision variables: One is where to place conduit paths, and the other is how many cable units to be installed on each link traversed by an established conduit path. Due to the serious drawback of the conventional approach partitioning the problem into two subproblems, the unified approach handled in one setting is used here to attack the whole problem without dividing into two ones. In this paper, we present a mathematical design model and propose an efficient solution method exploiting the nice structure of it. In addition to this physical design, some results on logical network configuration have also been made. Finally, computaional experiments are conducted to illustrate the efficiency of our design approach.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.97-99
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• 2006

Occurrence of Hwangji pond in Taebaek karst area was investigated in various hydrogeochemical ways and it is found out that there are underground cavern network and sinkholes under the pavement of Taebaek city. It is partially proved by dye tracing method.

• Journal of Chest Surgery
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• v.23 no.3
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• pp.465-473
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• 1990

Glutaraldehyde have been used as the most effective cross-linking agent for stabilizing collagen fibers and preventing biodegradation. We processed bovine pericardium in a solution containing 0.625% glutaraldehyde,0.05M HEPES buffer and 0.26% magnesium chloride in saline. The glutaraldehyde-preserved bovine pericardium was implanted in 36 patients at Seoul National University Hospital during a 11-month period between May 1989 and March 1990. 24 were males and 12 females, with ages ranging from 6 months to 168 months [mean age of 43 months]. In 12 patients, the glutaraldehyde-preserved bovine pericardium was used for orthotopic reconstruction of the pericardial sac. In 24 patients. the glutaraldehyde-preserved bovine pericardium was heterotopically implanted.; pulmonary monocusp implant and RVQT [right ventricular outflow tract] patch widening were performed in 10 patients, pulmonary monocusp implant in 6, RVOT patch widening in 4, valved conduit in 2, conduit and pulmonary angioplasty in 1, and ventricular septation in l. With vascular suture techniques, the anastomoses were immediately tight. There was no bleeding from the needle holes and no oozing through bovine pericardium itself. During the follow-up period of up to 10 months, no infections of the glutaraldehyde-preserved bovine pericardium occurred and no bovine pericardium-related complications were observed in this series.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.2
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• pp.261-268
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• 1996

An experimental study was performed to evaluate the efficacy of nerve growth factor(NGF) on inferior alveolar nerve in a rabbit model. In 20 New Zealand white rabbits, 14mm of bilat eral alveolar nerve were resected and the defects were repaired with the 17mm silicone conduits. In group I, 5mm autologous nerve segment were located centrally in the left side after tubulization and NGF solution(Sigma chemical 0.1 mg/mL) was instilled into each conduit. In group II, nerve repair modality was the same but no NGF solution was instilled into the conduits. On 2 months and 6 months postoperatively, the results were evaluated by clinical and hist omorphometric assessment. The result was that autologous nerve segment group show the best nerve regeneration effect and NGF instilled group the worst.

• Journal of Chest Surgery
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• v.28 no.7
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• pp.671-677
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• 1995

Skeletonization of the internal mammary artery [IMA during myocardial revascularization procedures may provide some advantages, compared with the pedicle graft of the artery. In 17 patients undergoing IMA grafting by skeletonization technique, flow through the artery was measured on mean arterial pressure of 50-55 mmHg immediately after cardiopulmonary bypass started [first flow and just before its anastomosis to left anterior descending artery [second flow . In 16 patients except 1 patient whose graft was injured during mobilization, the first flow of IMA graft was 32.3 $\pm$ 7.4 ml/min and the second flow increased to 59.6$\pm$25.9 ml/min without any treatment and the site for anastomosis of the IMA graft was more than 1.0 cm above the bifurcation. On the basis of previous clinical studies, the flow of the skeletonized IMA was greater than that of the pedicle graft [59.6 $\pm$ 25.9 ml/min versus 37.7$\pm$ 14.1 ml/min, p < 0.05 . In comparison between the skeletonized IMA and the IMA graft intraluminally dilated with papaverine solution, there was no significant difference between two flows[59.6 $\pm$25.7 ml/min versus 74.7 $\pm$31.4 ml/min, not significant , but the former showed longer graft and anastomosis of more proximal portion of the graft to left anterior descending artery. In conclusion, the technique of internal mammary artery skeletonization has consistently produced a satifactory conduit for myocardial revascularization procedures. We have adopted IMA skeletonization not only because of the flow, diameter, and vessel length obtained but also because of limited perivascular tissue disruption that occurs during the dissection.