• Journal of Chest Surgery
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• v.31 no.11
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• pp.1037-1042
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• 1998

Background: Among the various techniques for the adequate exposure of the mitral valve, the extended transseptal approach is the essential prerequisite for accurate repair or replacement of the mitral apparatus. But the efficacy and safty of the extended transseptal approach has not determined in Korea yet. Materials and methods: Retrospective data of 80 consecutive patients, operated from September 1992 to July 1997 were reviewed. Seventy- eight patients underwent mitral valve replacement and 2 patients underwent excision of left atrial myxoma. Thirty-eight of 78 patients had other concomitant procedures such as aortic valve replacement(n=22), tricuspid annulopasty(n=14), coronary artery bypass graft(n=1) and closure of ventricular septal defect(n=1). Mean follow up was 23.3±15.0 months and total follow up was 1792 patient-months. Results: The hospital mortality rate was 3.8%(3 patients). Two deaths were due to low cardiac output and one due to postoperative bleeding of coagulopathy. Among the 46 patients who had atrial fibrillation preoperatively, 45 had atrial fibrillation postoperatively and 1 converted to sinus rhythm. All 34 patients who were in normal sinus rhythm preoperatively remained in sinus rhythm after the operation. Mean aortic cross clamping time was 62 minutes for isolated mitral procedure and 90 minutes for concomitant procedures. There were no specific complications related to this approach. Conclusions: We suggest that the extended transseptal approach is an easy and good method for mitral valve surgery, especially in patients with small sized left atrium.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.1-8
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• 2017

Currently gas safety management in the industrial field has been done by LDAR as contact method or methane leak detector as non-contact method. But LDAR method requires a lot of man-power and methane leak detector have the limitation of methane only. Therefore the Research on the OGI(optical gas image) has big attention by industry. This research was undertaken to see the effect of background temperature difference of gas cloud on the clarity of OGI. The background temperature control panel was constructed to cool down the background temperature. OGI was taken at the various methane gas ejection rate and the designed temperature difference. The experimental results showed that the OGI(when the temperature difference is $-6^{\circ}C$) is more clear thane the OGI(when the temperature difference is zero). To quantify the clarity difference, MATLAB's RGB analysis method was employed. The RGB value of the OGI at ${\Delta}T-6^{\circ}C$ was 20% lower than the OGI at ${\Delta}T0^{\circ}C$. The clarity difference by T difference can be explained by the total radiation law. When the background temperature of the gas is lower than the air temperature, the radiation energy coming into the OGI lens is increasing. As the energy is increasing, the OGI image becomes clear.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.374-382
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• 2009

Steam generator(SG) tube, as a barrier isolating primary to the secondary coolant system of nuclear power plants(NPP), must maintain the structural integrity far the public safety and its efficient power generation capacity. And SG tubes bearing defects must be timely detected and taken repair measures if needed. For the accomplishment of these objectives, SG tubes have been periodically examined by eddy current testing(ECT) on the basis of administrative notices and intensified SG management program(SGMP). Stress corrosion cracking(SCC) on the SG tubes is not easily detected and even missed since it has lower signal amplitude and other disturbing factors against its detection. However once SCC is developed, that can cause detrimental affects to the SG tubes due to its rapid propagation rate. Accordingly SCC is categorized as prime damage mechanism challenging the soundness of the SG tubes. In this study, reproduced EDM notch specimens are examined for the detectability and quantitative characterization of the axial ODSCC by +PT MRPC probe, containing pancake, +PT and shielded pancake coils apart in a single plane around the circumference. The results of this study are assumed to be applicable fur providing key information of engineering evaluation of SCC and improvement of confidence level of ECT on SG tubes.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.227-241
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• 2005

This paper presents a practical and realistic Life-Cycle Cost (LCC) optimum design methodology for steel bridges considering the long-term effect of environmental stressors such as corrosion and heavy truck traffics on bridge reliability. The LCC functions considered in the LCC optimization consist of initial cost, expected life-cycle maintenance cost, and expected life-cycle rehabilitation costs including repair/replacement costs, loss of contents or fatality and injury losses, road user costs, and indirect socio-economic losses. For the assessment of the life-cycle rehabilitation costs, the annual probability of failure, which depends upon the prior and updated load and resistance histories, should be accounted for. For the purpose, Nowak live load model and a modified corrosion propagation model, which takes into consideration corrosion initiation, corrosion rate, and repainting effect, are adopted in this study. The proposed methodology is applied to the LCC optimum design problem of an actual steel box girder bridge with 3 continuous spans (40m+50m+40m=130m). Various sensitivity analyses are performed to investigate the effects of various design parameters and conditions on the LCC-effectiveness. From the numerical investigation, it has been observed that local corrosion environments and the volume of truck traffic significantly influence the LCC-effective optimum design of steel bridges. Thus, these conditions should be considered as crucial parameters for the optimum LCC-effective design.

• Journal of Chest Surgery
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• v.29 no.1
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• pp.32-37
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• 1996

Between May 1991 and September 1995, 7 patients underwent surgical repair of ventricular septal defect (VSD) complicated with myocardial infarction in Asan Medical Center. The patients included two male and five female. The ages of patients were ranged from 54 years to 76 years with a mean of 65 years. The sites of postinfarction ventricular septal defect were consist of anterior septal defect in 6 patients and anteroposterior septal defect in 1 patient. Preoperative 2D-echocardiography & angiography were performed in all patients in order to measure ventricular function and evaluate the extent of coronary artery disease. The operations were delayed till mean 24 $\pm$ 12days after myocardial infarction. All patients underwent infarctectomy and Teflon patch closures through the area of the left ventricle infarction or aneurysm in the anterior or apical aspect of postinfarction ventricular septal defect. The ventricular septal defect repaired simultaneously with coronary artery b pass graft in 3 patients, with ventricular aneurysmectomy in 5 patients, and with left ventricular thrombectomy in 1 patient. Patch fixation in the left side of interventricular septum by tracts-septal interrupted pledget suture reduced the recurrence rate of VSD. There were 2 postoperative complications : One with pneumonia, 1 patient with the skin necrosis of left thigh. There was ilo early death. The 6 patients except for one emigrant were followed up postoperatively between 3 and 63 months(mean .28 months), without any sequelae and late death. They are in New York Heart Association functional class I-II.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.674-682
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• 2018

Large industrial motors require a large area because of the high risk of shutdown accidents and large industrial accidents due to the lowering of the dielectric strength of the armature windings and overheating problems. Therefore, there is a demand for a large-capacity motor that has small size, light weight, and excellent dielectric strength compared with conventional motors. Superconducting motors have advantages of high efficiency and output power, low size, low weight, and improved stability. This results from greatly increasing the magnetic field generation by using superconductive field coils in rotating machines such as generators and motors. It is very important to design and analyze the cooling system to lower the critical temperature of the wires to achieve superconducting performance. In this study, a field loss analysis and low-temperature heat transfer analysis of the cooling system were performed through the conceptual design of a 100-HP high-temperature superconducting synchronous motor. The field loss analysis shows that a uniform pore magnetic flux density appears when high-temperature superconducting wire is used. The low-temperature heat transfer analysis for gaseous neon and liquid neon showed that a flow rate of 1 kg/min of liquid neon is suitable for maintaining low-temperature stability of the high-temperature superconducting wire.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.765-779
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• 2003

Physiological lipid mixtures comprised of cholesterol, ceramide and free fatty acid better maintain epidermal homeostasis and have been recently used for dermatoses induced by skin barrier damage, for example for atopic dermatitis and xerotic skin. Itching and dry atopic dermatitis of the skin may be related to altered skin barrier function. In a previous study, the use of multi-lamellar emulsion (MLE), which is a lipid mixtures containing cholesterol, pseudoceramide and free fatty acid, has been shown to accelerate the recovery of the epidermal permeability barrier. In this study, we assessed the efficacy of MLE compared with a currently used anti-itch moisturizer (AIM), the active ingredients of which are menthol and camphor, on barrier recovery after barrier disruption. To clarify the effect of MLE and AIM after acute barrier perturbation, we measured the relation between transepidermal water loss (TEWL) and the barrier recovery rate at 3, 6, 24, and 48 hours after tape stripping hairless mice and then observed changes in the stratum corneum (SC), including the intercellular lipid structure and secretion of lamellar bodies, by electron microscopy. MLE treated skin recover skin barrier function more rapidly, and AIM treated skin delayed barrier repair. Morphological changes in the epidermis, of MLE treated skin revealed well-conserved lipid multi-lamellar structures at 24 h after tape stripping, whereas AIM treated skin showed altered lamellar bilayers within the SC interstices at 48 h. In addition, MLE treated skin showed an increase in the number of LBs and in their secretions and a decrease in the number of SC layers versus AIM treated skin. These results suggest that MLE may accelerate the production of an epidermal permeability barrier in hairless mice by increasing the number and secretion of LB and improve the dryness and itch associated with an altered epidermal permeability barrier.

• Journal of Chest Surgery
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• v.29 no.3
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• pp.285-291
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• 1996

We have reviewed 157 cases of coarctation of aorta in the age of infancy and children from March 1973 to december 1994. Patients were 9) males and 64 females, and their age ranged from one month to fifteen years (23.8 $\pm$ 41.6months) with 113 infant cases. In the infantile age, congestive heart failure was the most common chief complaint (781113), and above that age, asymptom was most common (15/44). Isolated coarctation was present in 31 patients, and 9 patients had additional atrial septal defect (group I), 73 patients had associated ventricular septal defect (group II), and 44 patients had associated complex intracardiac lesions(group III). Aortic arch hypoplasia was present in 17 patients. , The operations perf'ormed were subclavian flap angioplasty in 71 patients, resection and anastomosis in 32 patients, patch aortoplasty in 26 patients, resd extended end-!o-end anastomosis in 27 patients, and direct angioplasty with resection of web in 1 patient. The early mortality was 17.2% (27/157) and re-coarctation rate was 18.0% (281157). The most common complication was respiratory problem in infants and postoperative hypertension in children.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.250-255
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• 2007

The RecA protein of Deinococcus radiodurans is essential for the extreme radiation resistance of this organism. The central steps involved in recombinational DNA repair require DNA-dependent ATP hydrolysis by recA protein. Key feature of RecA protein-mediated activities is the interactions with ssDNA and dsDNA. The ssDNA is the site where RecA protein filament formation nucleates and where initiation of DNA strand exchange takes place. The effect of sequence heterogeneity of ssDNA was examined in this experiment. The rate of homopolymeric synthetic ssDNA-dependent ATP hydrolysis was constant or nearly so over a broader range of pHs. For poly(dT)-dependent ATP or dATP hydrolysis, rates were generally faster, with a broader optimum between pH 7.0 and 8.0. Activities of RecA protein were affected by the ionic environment. The ATPase activity was shown to have different sensitivity to anionic species. The presence of glutamate seemed to slimulate the hydrolytic activity. Dr RecA protein was shown to require $Mg^{2+}$ ion greater than 2 mM for binding to etheno ssDNA and the binding stoichiometry of 3 nucleotide for RecA protein monomer.

• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.285-291
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• 2015

FTMS, TCS, ITS equipment such as high-pass highway are just a situation that does not lack traceability and passive surveillance is related to fault DB has so far consisted of an integrated operations management to maximize utilization of the facility. In addition, there is no replacement parts are replaced when a failure occurs, increasing the number of parts and repair time I have trouble growing, and becoming a service interruption whenever you replace each time. In this study, proactively manage the failure history of a highway facility ITS tries to preventive maintenance. Therefore, the error history is based on the reliability of the high-pass facilities theory to calculate the reliability of the system through a systematic statistical analysis Operational Availability. The fault number and the time the replacement period through the estimate decreases and can reduce the budget expenses by securing the spare parts quantity, establish a management plan in part by improving the quality of the system through constant preventive maintenance, quality of service at all times It may direct the non-stop operation state of the available state.