• Journal of Plant Biotechnology
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• v.36 no.1
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• pp.1-6
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• 2009

A study was conducted to investigate in vitro micro propagation of four potato cultivars of Daese, Jasim, Chubaek and Haryeng in MS medium and PM medium (a medium containing half concentration of $NH_4NO_3$ and $KNO_3$, two fold concentration of $CaCl_2$ as compared to MS medium). During $1{\sim}2$ weeks of culture, Daese and Jasim showed better shoot elongation on the solid MS medium than Chubaek and Haryeng whereas Chubaek and Haryeng did better shoot elongation on the solid PM medium. But no difference was observed after 4 weeks of culture. As compared to shoot elongation on the solid medium, it was delayed at early stage of culture in the liquid medium without shaking. Shoot formation ratio of potato (above 4 cm of shoot length) began to increase significantly after 1 week of culture and kept on increasing until 4 weeks. The four cultivars showed the different patterns of shoot growth in bioreactor. The PM medium with a quarter salt strength was effective for the regeneration of axillary buds as well as shoot elongation of Jasim and Chubaek. Daese showed vigorous regeneration of axillary buds in the PM medium with a half salt strength. On the other hand, Haryeng showed slower growth than the other three cultivars.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.411-422
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• 2010

Self-sensing on micro-failure, dispersion degree and relating properties, of carbon nanotube(CNT)/epoxy composites, were investigated using wettability, electro-micromechanical technique with acoustic emission(AE). Specimens were prepared from neat epoxy as well as composites with untreated and acid-treated CNT. Degree of dispersion was evaluated comparatively by measuring volumetric electrical resistivity and its standard deviation. Apparent modulus containing the stress transfer was higher for acid-treated CNT composite than for the untreated case. Applied cyclic loading responded well for a single carbon fiber/CNT-epoxy composite by the change in contact resistivity. The interfacial shear strength between a single carbon fiber and CNT-epoxy, determined in a fiber pullout test, was lower than that between a single carbon fiber and neat epoxy. Regarding on micro-damage sensing using electrical resistivity measurement with AE, the stepwise increment in electrical resistivity was observed for a single carbon fiber/CNT -epoxy composite. On the other hand, electrical resistivity increased infinitely right after the first carbon fiber breaks for a single carbon fiber/neat epoxy composite. The occurrence of AE events of added CNT composites was much higher than the neat epoxy case, due to micro failure at the interfaces by added CNTs.

• Membrane Journal
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• v.24 no.1
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• pp.10-19
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• 2014

Porous flat sheet membranes for separators in Zn air batteries were prepared with polyethersulfone (PES) solutions by immersion precipitation phase inversion method. PES/polyvinylpyrrolidone(PVP)/N-methylpyrrolidone(NMP) mixtures were used for casting solutions and water was used for coagulant. With the separators, Zn air batteries were fabricated. The separators were characterized by means of stress-strain test, impedance test and SEM. The Zn air batteries were tested by current interrupt method (CIM) and galvanostatic discharge method. The tensile strength increased with increasing PES content in the casting solution while the ionic conductivity decreased. On the other hand, the ionic conductivity increased while the tensile strength decreased with increasing PVP content. The effect of ionic conductivity trend of the separator in the Zn air battery was confirmed through current interrupt method and galvanostatic discharge method experiments. The battery with the separator from casting solution with higher PES content showed higher IR drop and lower discharge capacity. And the battery with the separator from casting solution with higher PVP content showed lower IR drop and higher discharge capacity.

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.837-842
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• 1999

The Ta/TaN multilayer structure with repeating layers of a poly-crystalline Ta layer of high ductility and a TaN layer of high hardness is expected to exhibit toughness. This paper reports the results on the hardness and the adhesion strength of Ta/TaN multilayers and compositional gradient Ta/TaN layers deposited on the high speed steel substrate by reactive sputtering as a function of annealing temperature. The TaN film deposited with the $N_2$/Ar ratio of 0.4 in the reactive sputtering process exhibits the highest crystallinity, and the highest hardness and the results of scratch test of the Ta/TaN multilayers. The hardness and adhesion strength of the Ta/TaN multilayers becomes deteriorated with increasing the annealing temperature in the heat treatment right after depositing the layers. Therefore, post-annealing treatments are not desirable in the case of the Ta/TaN multilayers from the standpoint of mechanical properties. Also the hardness of Ta/TaN multilayers increases with decreasing the compositional modulation wavelength, but the adhesion property of the layers is nearly independent of the wavelength. On the other hand, the compositional gradient Ta/TaN film exhibits the highest hardness and the value of scratch test for the post-annealing temperatures of 20$0^{\circ}C$ and 40$0^{\circ}C$, respectively. This tendency of the compositional gradient Ta/TaN films differs from that of the Ta/TaN multilayers.

• Journal of Conservation Science
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• v.25 no.2
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• pp.161-169
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• 2009

The objective of this study was to investigate stability of Korean Paper(Hanji) which is being sold in the Korean markets according to aging treatment. In order to know the aging characteristics, the optical and mechanical properties of before and after wet and dry-heat aging treatment were examined. The optical and mechanical properties were shown higher reduction in the dry-heat aging treatment compared to the wet-heat aging treatment. The Soonji (pure mulberry Hanji) made from black mulberry bast pulp was shown a great reduction of the brightness and whiteness, and increase of the opacity in the aging treatment. On the other hand, in case of mechanical properties, the breaking length of Soonji made from white mulberry bast pulp was significantly higher than that of the others, and the tensile strength was shown drastic reduction in according to Soonji made from black mulberry bast pulp in the aging treatment. The burst strength of Soonji made from black and white mulberry bast pulp was shown the similar value in the wet-heat aging treatment. The folding endurance of Soonji made from white mulberry bast pulp was significantly higher than that of others before and after aging treatment. Consequently, Hanji was affected sensitive in the temperature compared to the humidity. Meanwhile, the density and color of the chinese ink was no significant changes before and after wet and dry-heat aging treatment.

• The Korean Journal of Rehabilitation Nursing
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• v.6 no.1
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• pp.79-89
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• 2003

Purpose: This research with one group pre-post design was carried out to test the practical feasibility to administrate the Music Movement program developed for the stroke patients. Subjects: 12 stroke survivors at "J" Public Health Center in Seoul. were participated in. The average age was 68 years old, the ratio of sex was almost 5.8:4.2, the duration of was almost over 1 year. Method: Music Movement program was conducted for 2 hours ${\times}$ 1day ${\times}$ 6 weeks. The contents of Music Movement program were consisted of the preparatory activities, main activities and the wrap up activities. The preparatory activities are ice braking, greeting, explanation of the aims of music movement program, and introduction of stroke disease and ROM exercise. The main activities are the body motions with singing and playing musical instruments. The wrap up activities are stretching and joints and discussion of home activities. Data Collection: The outcome variables are muscle strength, finger pinch power, ROMs, flexibility, depression, and life satisfaction. Depression was measured by CES-D(Kim, I. J., 1999), life satisfaction by ladder scale(McDowell & Newell, 1996), and ADL state(Holbrook & Skilbeck, 1983). Data Analysis: SPSS/PC 10.0 for Window was used. Wilcoxon Signed Ranks Test was used to analyze outcome measures. The level of statistical significance was set at p<.05. Results: This program was effective to decrease the depression level of subjects(p<.05). The muscle strength, hand grip power, ROMs, life satisfaction, and rehabilitation state of the subjects were slightly increased but no significant differences were found between the pre and post test. Additionally every patient replied that they were very satisfied and expressed their appreciation for this program very much. Of course they strongly want to continue to participate in and meet the peer group again. Conclusion: Considering these results, the practical feasibility of Music Movement program can be supported. Therefore, this Music Movement program can be examined with the quasi-experimental design with control group and ongoing reviews. After that, this program would be applied in public health centers, medical institutes, and welfare centers for the rehabilitation of stroke patients.

• Journal of Korean Society of Steel Construction
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• v.14 no.4
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• pp.557-566
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• 2002

This paper summarized the results of a full-scale cyclic seismic testing on four reduced beam section (RBS) steel moment connections. Specifically, these tests addressed a bolted web versus a welded web connection and strong versus medium panel zone (PZ) strength as key test variables. Specimens with medium PZ strength were designed to promote balanced energy dissipation from both PZ and RBS regions, in order to reduce the requirement for expensive doubler plates. Both strong and medium PZ specimens with welded web connection were able to provide sufficient connection rotation capacity required of special moment-resisting frames. On the other hand, specimens with bolted web connection performed poorly due to premature brittle fracture of the beam flange at the weld access hole. Unlike the case of web-welded specimens, specimens with cheaper bolted web connection could not transfer the actual plastic moment of the original (or unreduced) beam section to the column. No fracture occurred within the beam groove welds of any connection in this testing program. If fracture within the beam flange groove weld is avoided by using quality welding procedure as in this study, the fracture issue tends to move into the beam flange base metal at the weld access hole. Supporting analytical study was also conducted in order to understand the observed base metal fracture from the engineering mechanics perspective.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.13-22
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• 2007

This study was carried out to scrutinize possibility of manufacturing pitch pine (Pinus rigida) glued laminated timber in order to add values of pitch pine trees. Also, it was investigated to improve bending performance of pitch pine glulam. Pitch pine was imported as one of major plantation species in Korean peninsula. Machine stress rated grades of pitch pine lumber mostly ranged between E7 and E9. which grades were more or less inferior to producing high quality glulam. However, the adhesive properties between pitch pine and pitch pine, and between pitch pine and Japanese larch (Larix kaempferi Carr.), such as shear bond strength, wood failure rate and de-lamination rate of bonded layer submerged in cold and boiling water, were higher than Korean Standard criteria. These properties are essential for manufacturing glulam with single species or multiple species. The modulus of rupture (MOR) of pitch pine glulam exceeded the criterion of Korean Standard for glulam strength grade but modulus of elasticity (MOE) was lower than the criterion. On the other hand, the bending performances (MOR and MOE) were improved 20 percent by mixing with Japanese larch laminar. It is effective to arrange higher quality Japanese larch laminar at the outer layer of glulam for improving bending performances. In conclusion, it is possible to use low quality pitch pine as laminar of structural glulam for adding values of pitch pine.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.1
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• pp.73-83
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• 1997

Most of the materials used in various industrial fields and also in our daily life are multi-component materials or composite materials, and it is well known that there are many cases where adhesion between the constituents within the bonded systems plays an important role. There are various types of performance evaluation tests for the bonded materials, among which tests for evaluating the bond performance under various conditions may be regarded as the most interesting ones for those engaged in work related to adhesion. I have studied on the mechanism of adhesion form the rheological standpoint with my colleagues, including some students from Korea, and I am very happy to be able to have a talk on some of our research works. In Japan, the so-called "adhesives" are usually classified into two categories;adhesives and pressure sensitive adhesives (PSA). Adhesives are the materials which solidify after bonding and are after used as the structural adhesives because the adhesive strength is comparatively strong. On the other hand, the pressure sensitive adhesives never solidify and are used as PSA tapes, labels or decals. About the adhesives, we have examined the dependence of adhesive strength(shear, tensile, peel) upon both temperature and rate of deformation, and found out some empirical rules which are applicable to most of the adhesive systems. We have also developed a simplified theory of adhesion, which is deseribed in terms of mechanical equivalent mode1 and a few failure criteria. Although some of the common rules can be accounted for according to this theory, it must be pointed out that a fracture mechanical approach ms inevitable especially in the region where the meehanical relaxation time of the adhesive is extremely large [W. W. Lim and H. Mizumachi]. About the pressure sensitive adhesives, we have studied on the PSA performance (peel, tack, holding power) as a function of both the viscoelastic properties and surface chemical properties of the materials, and found out some rules, and again we have developed a theory which deseribes the mechanism. And in addition, we have studied on the miscibility between linear polymers and oligomers, because PSA is generally manufactured by blending gums and tackifier resins. Many phase diagrams have been found and some of them have been analyzed on thermodynamic basis, and it became evident that the miscibility is a very important factor in PSA [H. J. Kin and H. Mizumachi]. In this presentation, I want to emphasize the fact that the adhesion performance is closely related to the structure/property of the adhesives.adhesives.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.871-877
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• 2002

Alumina slurriers, having various amount of alumina and ratio of organic additives, were prepared for tape casting. The relative viscosities were compared to investigate influence of composition on stability of the slurry and plotted as a function of powder fraction. They raised with increasing powder fraction of slurries, revealing a exponential function curve, which means that stability of slurry was not affected by amount and composition of organic additives. Cast green tapes were tested under tensile condition at room temperature. The increase in alumina ratio and binder ratio was found to decrease strain to failure of green tapes from 363% to 45% and from 68% to 25%, respectively. Tensile strength of green tapes increased abruptly with increasing alumina ratio, which showed its maximum at 1 MPa. On other hand, Tensile strength increased continuously from 0.5 MPa to 4 MPa with increasing binder ratio. Mechanical properties of them were affected seriously and lost their properties by elevating temperature from 20$^{\circ}C$ to 80$^{\circ}C$.