• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.237-246
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• 2008

The cross-sections of continuous multi-span beams sometimes suddenly increase, or become stepped, at the interior supports of continuous beams to resist high negative moments. The three-dimensional finite-element program ABAQUS (2006) was used to analytically investigate the inelastic lateral-torsional buckling behavior of stepped beams subjected to pure bending moment and resulted in the development of design equations. The flanges of the smaller cross-section were fixed at 30.48 by 2.54 cm, whereas the width and/or thickness of the flanges of the larger cross-section varied. The web thickness and height of beam was kept at 1.65 cm and 88.9 cm, respectively. The ratios of the flange thickness, flange width, and stepped length of beams are considered analytical parameters. Two groups of 27 cases and 35 cases, respectively, were analyzed for double and single stepped beams. The combined effects of residual stresses and geometrical imperfection on inelastic lateral-torsional buckling of beams are considered. First, the distributions of residual stress of the cross-section is same as shown in Pi, etc (1995), and the initial geometric imperfection of the beam is set by central displacement equal to 0.1% of the unbraced length of beam. The new proposed equations definitely improve current design methods for the inelastic LTB problem and increase efficiency in building and bridge design. The proposed solutions can be easily used to develop new design equation for inelastic LTB resistance of stepped beams subjected to general loading condition such as a concentrated load, a series of concentrated loads or uniformly distributed load.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.288-293
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• 2016

The study was performed to evaluate thermal insulation covering materials (TICMs) to protect peach trunks against freezing temperatures in winter season by investigating thermo-physical properties and practical thermal insulation effect of the TICMs which was made of white non-woven fabrics, yellow paper sheets, and waterproof fabric pads. Among the three TICMs, Waterproof fabric pad (double layer) possessed the best performance about thermal insulation rate and thermal resistance among three kinds of TICMs. Day thermal insulation effects of waterproof fabric pad, which prevent from temperature rise on the bark tissues of trunks during the day time, were $14.09^{\circ}C$. Night thermal insulation effects of them, which prevent from temperature decline on the bark tissues of trunks at night time, were $7.23^{\circ}C$. Waterproof fabric pad showed the highest day and night thermal insulation effects. Thus our results suggest that development of TICMs using waterproof fabric pad might be helpful to protect the bark tissues of trunks from freezing injury.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.571-575
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• 2014

'Dream Song' is a cultivar of Gypsophila paniculata developed by the Jeollabuk-do Agricultural Research & Extension Services in 2010 for cut-flower production. This hybrid was bred from 121 seedlings collected from an open-pollinated population of 'Gyp06-11'. It has novel morphological characteristics of upright plant type, lanceolate leaves, double florets with a few bright white-colored petals of obovate shape, truncate petal tips, and cup-shaped calyces. Furthermore 'Dream Song' has desirable cultivation characteristics including narrow branching angle, and moderate resistance to powdery mildew, thrips and leaf miners. Moreover it produces more primary branches, and longer internodes and flower stalks than reference cultivar 'Bristol Fairy' during summer cultivation in a subalpine area (500 m over the sea level). Flowering in 'Dream Song' is delayed by about 17 days as compared to 'Bristol Fairy'. 'Dream Song' produces normal flowers with 2 pistils and an average of 10.4 stamens, with fewer malformed flowers than 'Bristol Fairy'.

• Journal of Chest Surgery
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• v.23 no.4
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• pp.617-621
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• 1990

A heart supplies blood of about 15, 000 liters to each human organ in a day. A normal function of heart valves is necessary to accomplish these enormous work of heart. The disease of heart valve develops to a narrowness of a closure, resulting in an abnormal circulation of blood. In an attempt to eliminate the affliction of heart valves, the operative method to replace with artificial heart valves has developed and saved numerous patients over past 30 years. This replacement operation has been performed since early 1960`s in Korea, but all the artificial heart valves used are imported from abroad with very high costs until recent years. New artificial heart valves have been developed in Korea Advanced Institute of Science and Technology since early 1980`s. The first developed valve was designed with a free-floating pyrolytic carbon disk that is suspended in a titanium cage. The design of the valve was tested in vitro, and in animals in 1987. The results from this study was that the eccentrically placed struts creates a major and minor orifice when the disc opens and stagnation of flow in the area of the minor orifice has led to valve thrombosis. In this work, the design of the valve was changed from a single - leaflet valve to double - leaflet one in order to resolve the problems observed in the first - year tests. Morphological and hemodynamic studies were made for the newly designed valves through the in vitro and in vivo tests. The design and partial materials of the artificial heart valve was improved comparing with first - year`s model. The disc in the valve was modified from single - leaflet to bi - leaflet, and the material of the cage was changed from titanium metal to silicon - alloyed pyrolytic carbon. A test was made for the valve in order to examine its mechanical performance and stability. Morphological and hemodynamic studies were made for the valve that had been implanted in tricuspid position of mongrel dogs. All the test animals were observed just before the deaths. A new artificial heart valve was designed and fabricated in order to resolve the problems observed in the old model. The new valve was verified to have good stability and high resistance to wear through the performance tests. The hemodynamic properties of the valve after implantation were also estimated to be good in animal tests. Therefore, the results suggest that the newly designed valve in this work has a good quality in view of the biocompatibility. However, valve thrombosis on valve leaflets and annulus were found. This morphological findings were in accordance with results of surface polishing status studies, indicating that a technique of fine polishing of the surface is necessary to develop a valve with higher quality and performance.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.165-191
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• 1990

Although a number of studies have been performed to assure that residual stress caused by a mismatch of alloy porcelain thermal expansion can contribute to clinical failure of a ceramometal restoration, the interactive influence of cooling rate on the magnitude of thermal expansion difference and on bond strength between them have not been extensively analyzed. The objective of this study was to determine the influence of cooling rate and the number of firing cycles on the expansion mismatch and the flexural failure resistance of metal porcelain strip. Tested alloys included one Pd-Ag alloy, one Ni-Cr-Be alloy with two kinds of porcelain, Vita and Ceramco. Metal specimens were cast into rods with a height of 13mm and a diameter of 5mm. Subsequently, the castings were subjected to scheduled firing cycles without porcelain. And the porcelain specimens after being fired were trimmed into a bar with a final dimension of $5{\times}5{\times}25mm$. Thermal expansions of the alloys and porcelains were measured by using a push rod or a differential dialometer respecitvely. Porcelain glass transition temperatures and expansion values were derived alloy-porcelain pairs were assessed by comparing expansion values of the components at a porcelain glass transition temperature. Calculations were made using combinations of a Ni-Cr alloy or Pd-Ag alloy with each of two porcelain products. Metal-porcelain strip specimens were subjected to four point loading in an Instron testing machine until crack occured at the metal-cramic interface at the time of sharp decrease of load on recorder. On the basis of this study, the following conclusions may be stated: 1. Regardless of the kinds of ceramometal combinations, both of calculated and experimental data revealed that the double fired specimens exhibited a significantly lower flexural strength. 2. By the rise of the amount of mismatch, bond strength were decreased. 3. Thermal expansion value of Pd-Ag alloys were higher than that of Ni-Cr alloys. 4. Expansion curves of metal were proportional to the increase of temperature and were not affected by the experimental conditions, however porcelains did not show the same magnitude of metal, and a shift of the glass transition temperature to higher temperatures was observed when cooled rapidly 5. Alloy-porcelain thermal compatibility appeared more dependent on the porcelain than the alloy.

• The Korean Journal of Mycology
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• v.26 no.4 s.87
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• pp.450-457
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• 1998

The cryparin of Cryphonectria parasitica belongs to a cell wall associated fungal hydrophobin. The cryparin, though it is encoded by a single copy gene, is known for the high expression during the liquid culture of C. parasitica, and it turns out that 22% of total mRNA was transcribed for cryparin at 48hr after the liquid culture. In addition, it is also known as one of down-regulated fungal proteins by the presence of double stranded RNA virus, Cryphonectria hypovirus 1. In previous studies (Kim et al., 1999), we have constructed a cryparin-null mutant by replacing the cryparin gene with hygromycin B resistance gene due to site directed homologous recombination. In order for the promoter analysis of cryparin which seems to be very strong as well as mycoviral specific, it is preferable to have a strain with only a target promoter replaced and a discernable target site for incoming vectors. However, the cryparin-null mutant revealed the presence of an additional copy of transforming vector except the one which replaced the cryparin gene. In addition, the cryparin-null mutant did not contain any markers for targeted integration of incoming vectors. This prompts us to design an experiment to obtain a strain for promoter analysis of cryparin gene. A different mating type strain EP6(Mata, $met^-$) was mated with the cryparin-null mutant ${\triangle}$Crp194-7(MatA, Crp${\triangle}$::hph) to make the progenies with only a single replacement vector and $met^-$ characteristic remained. Nutritional assay as well as Southern blot analysis revealed that the progeny, ${\triangle}$Crp194-a6, was the methionine auxotroph with a single replacing vector in genome. Northern blot analysis and PAGE showed that there was no cryparin produced in this bred strain either.

• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.16-23
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• 2002

Physical properties of composite resins such as strength, resistance to wear, discoloration, etc depend on the degree of conversion of the resin components. The purpose of this study was to evaluate the degree of conversion of the composite resins according to the thickness of tooth structure penetrated by light and applied light curing time. The coronal portions of extracted human teeth (one anterior tooth, three posterior tooth) was embedded by pink denture material. the mounted teeth were cut into three illumination sections (1mm thickness enamel section, 1mm thickness dentin section, 2mm thicknes dentin section) and one backing section with cutting wheel. Thin resin films were made by using 6kg pressure between slide glass during 5 minutes Thin resin film was light cured on coupled illumination section during 40sec, 80sec and 120sec. each illumination section was coupled as follows; no tooth structure(X), ename section(E), enamel section + 1mm dentin section(ED1), enamel section + 2mm dentin section(ED2), enamel section + 1mm dentin section + 2mm dentin section(EDD). To simulate the clinical situation more closely, thin resin films was cured against a backing section of tooth structure. The degree of conversion of carbon double bonds to single bonds in the resin films were examined by means of Fourier Transform Infrared Spectrometer. The results were obtained as follows ; 1 As curing time was increased, conversion rate was increased and as tooth thickness which was penetrated by curing light was increased, conversion rate was decreased. 2. At all tooth thickness groups, conversion rate between 80sec and 120sec was not significantly increased(P＞0.05). 3. At 40sec group and 80sec, conversion rate between no tooth structure(X) group and 1mm enamel section(E) group was not significantly decreased(P＞0.05). 4. At 80sec group and 120sec, conversion rate between 1mm enamel section(E) group and 1mm enamel section + 1mm dentin section(ED1) group was not significantly decreased(P＞0.05).

• Annals of Clinical Neurophysiology
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• v.1 no.2
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• pp.91-98
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• 1999

Background : The pathogenesis of acute inflammatory demyelinating polyradiculoneuropathy (AIDP), Guillain Barre syndrome (GBS) is not clear, but it has been known that the immune mechanisms play an important role. Authors performed this study to establish an animal model of experimental allergic neuritis (EAN) by immunizing the myelin components of peripheral nerves and to understand the electrophysiological and histopathological features as well as the ${CD_5}^+$ B-lymphocyte changes in peripheral bloods in the EAN models. Methods : Lewis rats weighing 150-200 gm were injected subcutaneously in soles two times with total myelin, P0, P1, or P2 proteins purified from the bovine cauda eguina. The EAN induction was assessed by evaluating clinical manifestations. The electrophysiological and histopathological features were studied as routine methods. The ${CD_5}^+$ Blymphocytes were double stained using monoclonal FITC conjugated anti-rat CD45RA and R-PE conjugated anti-rat ${CD_5}^+$ antibodies and calculated using a fluorescence activated cell sorter (FACS). Results : The EAN animal models were established. In two out of five, in one out of two, in none out of three, and in none out of one Lewis rats injected with purified total myelin, P0, P1, P2 proteins respectively, They showed slow spontaneous motor activity and weak resistance against pulling back by tails. The typical electrophysiological and histologic findings in total protein and P0 induced EAN animal models were the decreased conduction velocity, the decreased compound muscle action potential (CMAP) amplitude and the dispersion phenomenon. The perivascular infiltrates of lymphocytes with focal demyelinating process were found in light microscopy. The ${CD_5}^+$ B-lymphocyte expression in three EANs were 2.38%, 3.50% 2.50%, which were not significantly increased, compared with those in normal controls. Conclusion : The EAN animal models were successfully established by injecting the total myelin and P0 myelin and they showed electrophysiological and histological features typical of demyelinating process. However they did not show an increased expression of ${CD_5}^+$ B-lymphocyte in peripheral bloods which could be indirect evidence of humoral autoimmunity.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.522-526
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• 2007

Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.35-60
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• 1997

Physical properties of composite resins such as strength, resistance to wear, discoloration, etc, depend on the degree of conversion of the resin components. The clinical behavior of restorative resins varies brand to brand. Part of this variation is associated with the filler and differences in the polymer matrix. The polymer matrix of resins may differ because the involved monomers are dissimilar and because of variation in the catalyst system. The purpose of this study was to evaluate the degree of conversion of the composite resins according to the depth of cure and light curing time. 7mm diameter cylindrical aluminum molds were filled with each of five different hybrid light curing composite resins(Z-100, Charisma, Herculite XRV, Prisma TPH, Veridonfil) on the thin resin films. The molds were 1mm, 2mm, 3mm, 4mm, and 5mm in depth to produce resin films of various heights. Each sample was given 20sec, 40sec, and 60sec illumination with a light source. The degree of conversion of carbon double bonds to single bonds in the resin films was examined by means of Fourier Transform Infrared Spectrometer. The results were obtained as follows; 1. There was difference in the degree of conversion among five light curing composite resins according to the depth of cure for 20sec, 40sec, and 60sec illumination with light source with statistical significance(P<0.05). 2. Five light curing composite resins show lower degree of conversion at surface of the resin than depth of 1mm. 3. The degree of conversion of five light curing composite resins was siginificantly reduced from the maximum for the resin film when the light passed through as little as 1mm of each composite. 4. The degree of conversion of five light curing composite resins decrease significantly at the depth of 4mm, and polymerization was not occured at the depth of 5mm except for Prisma TPH. 5. The degree of conversion of five light curing composite resins was increased with increased light curing time, and there was no significant differences in the degree of conversion above 4mm in Z-100, 3mm in Charisma, and at depth of 5mm in Herculite XRV and Veridonfil(P>0.05).