• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.79-86
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• 1995

The structural materials for cryogenic technology have been recently developed to support the many modern large-scale application from superconducting magnets for nuclear fusion reactor, magnetic levitation railway to LNG tankers. However it is pointed out that quenching phenomenon is one of the serious problems for the integrity of these applications, which is mainly attributed to the rapid temperature rising in the material due to some extrinsic factors of structures. From the viewpoint of fracture mechanics, it is therefore very important to clarify the mechanism of temperature rising of structural material due to cyclic loading at cryogenic temperature. From this purpose, fatigue test was carried out for high manganese steel at liquid helium temperature(4.2K) using triangular stress waveform to identify both the mechanism of temperature rising near crack tip and the effect of loading stress waveform on temperature rising near crack tip and the effect of loading stress waveforms on temperature rising. As the results, two types of temperature rising, that is, regular and burst types were observed. And a periodical temperature rising corresponding to the stress waveforms was also found. The peaks of the temperature rising were recorded near both the maximum and the minimum values of the applied stress. The sudden temperature rises, which indicated the higher values than those of periodical temperature rises under the repetition of stress, were observed at the final region of crack growth. It was shown that the peak values of the temperature rising increased with stress intensity factor range.

• Biomolecules & Therapeutics
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• v.6 no.4
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• pp.351-357
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• 1998

In order to understand the mechanism of the regulation of CYPIAI gene expression and ethoxy-resorufin deethylase (EROD) activity in ex vivo system, we have studied the action of TCDD and 3MC in theisolated perfused male rat liver. CYPIAI myNA level and EROD activity were measured in rat liver that wasisolated and perfused with va.ious chemicals such as 2,3,7,8-tet.achlorodibenzo-p-dioxin (TCDD), 3-methyl-cholanthrene (3MC), $17{\beta}$-est.adios ($E_2$), morin. TCDD or 3MC alone perfusion into male rat liver resulted in increase of CYPIAI mRNA level and the magnitude of stimulation was one and half times higher with TCDD treatment than 3MC treatment. However $E_2$ perfusion into male rat liver showed slight stimulation of CYPIAI mRNA level. When $10_{-8}$ M $E_2$ was perfused concomitantly with either $10_{-9}$ M TCDD or $10_{-9}$ M 3MC, stimulated CYPIAI mRNA by either TCDD or 3MC was inhibited. Morin was examined for its effects on CYPIAI mRNA level and result was similar to that was observed with estrogen except that morin alone did not change the level of CYPIAI mRNA. EROD activity was also stimulated with either TCDD or 3MC perfusion, and the magnitude of EROD stiumlation was similar to that of CYPIAI mRNA stimulation in response to TCDD or 3MC perfusion. This data is different from the data that we have obtained with female rat liver. Concomitant perfusion either $E_2$ or morin with TCDD or 3MC inhibited 3MC perFusion or TCDD perfusion stimulated EROD activity. These data confirm the hypothesis that TCDD and 3MC might act through the same mechanism of action on the regulation of CYPIAI gene expression in male rat liver.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.2
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• pp.157-164
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• 1999

To determine molecular mechanisms of Aquaporin-CD (AQP2) gene regulation, the promoter region of the AQP2 gene was examined by transiently transfecting a promoter-luciferase reporter fusion gene into mouse renal collecting duct cell lines such as mIMCD-3, mIMCD-K2, and M-1 cells, and NIH3T3 mouse embryo fibroblast cells. PCR-Southern analysis reveals that mIMCD-3 and mIMCD-K2 cells express AQP2, but M-1 and NIH3T3 cells do not, and that the treatment with cpt-cAMP $(400\;{\mu}M)$) or forskolin/isobutylmethylxanthine (IBMX) increased the AQP2 expression in IMCD cells. In both IMCD and NIH3T3 cells, the constructs containing the promoter of AQP2 gene showed promoter activities, indicating lack of tissue-specific element in the 1.4 kb 5'-flanking region of the mouse AQP2 gene. Luciferase activity in the IMCD cells transfected with the construct containing 5-flanking region showed responsiveness to cpt-cAMP, indicating that the 1.4 kb 5'-flanking region contains the element necessary for the regulatory mechanism by cAMP. The promoter-luciferase constructs which do not have a cAMP-responsible element (CRE) still showed the cAMP responsiveness in IMCD cells, but not in NIH3T3 cells. Increase in medium osmolarity did not affect AQP2 promoter activity in mIMCD-K2 cells. These results demonstrate that AQP2 gene transcription is increased with cAMP treatment through multiple motifs including CRE in the 5'-flanking region of the gene in vitro, and the regulatory mechanism may be important for in vivo regulation of AQP2 expression.

• Journal of Korean Association for Spatial Structures
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• v.13 no.2
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• pp.83-91
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• 2013

The core aim of this dissertation is to empirically scrutinize a strength characteristic of beam-column frame subjected to the cyclic lateral load, a beam-column frame of un-reinforced masonry wall, and a shear wall frame. First and foremost, I embark upon making three prototypes vis-$\grave{a}$-vis this research. By conducting this process, I touch on an analysis of cyclic behavior and a damage characteristic of the beam-column frame, the beam-column frame of un-reinforced masonry wall, and the shear wall frame. What is more, through the previous procedure, the next part delves into the exact stress transfer path and the destructive mechanism to examine how much and how strong the beam-column frame of un-reinforced Masonry Wall does have a resistance capacity against earthquake in all the architecture constructed by the above-mentioned frame, as well as school buildings. In addition to the three prototypes, two more experimental models, a beam-column frame and shear wall frame, are used to compare with the beam-column frame of un-reinforced masonry wall. Lastly, the dissertation will suggest some solutions to improve the resistance capacity against earthquake regarding all constructions built with non bearing wall following having examining precisely all the analysis with regard to not only behavior properties and the damage mechanism of the beam-column frame and the beam-column frame of un-reinforced Masonry Wall but also the resistance capacity against earthquake of non bearing wall and school buildings.

• Journal of Mushroom
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• v.2 no.3
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• pp.115-126
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• 2004

Somatic hybrids of inter-compatible and inter-incompatible strains were obtained by protoplast fusion. The fusion products between compatible strains, Pleurotus ostreatus and P. florida, formed heterokaryons, while fusants between incompatible strains such as P. cornucopiae + P. florida, P. ostreatus + Ganoderma applanatum, P. florida + Ganoderma lucidum, and P. ostreatus + Flammulina velutipes formed synkaryons that retained genes from both parents. The heterokaryons showed the same level of basidioma development. In contrast, the synkaryons showed unique characteristics including clamp connection formation at mitosis, either partner basidioma development, and abnormal segregation and recombination compared with inter-compatible strains. Synkaryons can be classified into homokaryoyic and heterokaryotic type. A comparison of somatic hybrids with compatible and incompatible strains was made using random amplified polymorphic DNA (RAPD) analysis. The heterokaryons between compatible species showed the same level of variability and contained both parental RAPD bands. In contrast, most of the synkaryons between incompatible species showed similarity to those of either parental bands and non-parental RAPD bands. Synkaryons can be classified into microgenome insertion type and macrogenome insertion type. A tetrapolar mating system was found among monospore isolates in somatic hybrids and wild type P. ostreatus. Homokaryons from each somatic hybrid combination were paired with tester homokaryons of the initial wild type of P. ostreatus. The changed mating types were identified in progenies. The pattern of mating type switching in somatic hybrids depends on compatibility of fusion partner. There are several factors related to the mechanism of clamp connection formation and fruiting body development of synkaryons. Of these,the major factor may be associated with self-fertility and mating type switching such as homokaryotic fruiting of wild type P. ostreatus. This review will discuss these aspects.

• Animal cells and systems
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• v.2 no.1
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• pp.145-152
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• 1998

The spinning apparatus and production of secretory silk from silk gland of the black widow spider, Latrodectus mactans were studied with scanning and transmission electron microscopes. The silk glands were located in seven groups on the spinnerets including each pair of major and minor ampullate, 3 pairs of tubuliform, 1 pair of flagelliform, 2 pairs of aggregate, about 50 pairs of pyriform and over 250 pairs of aciniform glands, respect- ively. Each group of silk gland feeds silk into one of the three spinneret pairs. Secretory silk is synthesized from rough endoplasmic reticulum (rER) of glandular epithelial cells. The secretory silk is transported from toe rER into the secretory vacuoles which are grown up by fusion with the surrounding small vesicles including the secretory silk. The secretory vacuoles, which show a gradual increase in electron density with the process of maturity, are formed without involvement of the Golgi complex, suggesting that they do not play an important role in the processing of the secretory silk. The secretory silk products are released by the mechanism of apocrine secretion, losing part of their cytoplasm. Moreover, another type of silk precursor, possibly protein, appears as granular material, and is also discharged to the luminal cavity.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.6
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• pp.510-517
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• 2015

For the self-directed rehabilitation of upper extremity hemiplegia patients, in this paper we propose an interface method capable of doing bilateral exercises in rehabilitation robotics. This is a method for estimating information of movements from the unaffected-side, and projects it to the affected-side in order. That the affected-side is followed the movements of the unaffected-side. For estimation of the unaffected-side movements information, gyro sensor data and acceleration sensor data were fused. In order to improve the measurement error in data fusion, a HDR filter and a complementary filter were applied. Estimated motion information is derived the one side of the drive input of rehabilitation robot. In order to validate the proposed method, experimental equipment is designed to be similar to the body's joints. The verification was performed by comparing the estimation angle data from inertial sensors and the encoder data which were attached to the mechanism.

• Journal of Applied Reliability
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• v.14 no.4
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• pp.243-247
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• 2014

The Spinal cage is the cage-shaped implantable medical device used to treat structural abnormalities caused by degenerative intervertebral disks. In order to secure enough space to provide the mechanical stability and the intervertebral fusion, after removing the intervertebral disc, the Spinal cage is transplanted between the intervertebral space. A hammer is used to push the spinal cage into a narrow space during the spinal cage transplant surgery. Due to the impact and pressure, damage occurs frequently on the spinal cage. In this study, a test model is constructed to measure the value of impulse generally applied on the Spinal cage. The figures of internal impulse before and after the improvement of the Spinal cage are then compared to suggest direction to improve the reliability of the spinal cage.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.166-177
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• 1997

The high strength AlZnMgCu0.5 alloy is a light metal with good age hardenability, and has a high tensile and yielding strength. Therefore, it can be used for structures requiring high speciple strength. Even though high strength AlZnMgCu alloy has good mechanical properties, it has a lot of problems in TIG and MIG welding processes. Since lots of high heat absorption is introduced into the weldment during TIG and MIG processes, the microstructural variation and hot cracks take place in heat affected zone. Therefore, the mechanical properties of high strength AlZnMgCu0.5 alloy can be degraded in weldment and heat affected zone. Welding process utilizing high density heat source such as electron beam should be developed to reduce pore and hot cracking, whichare usually accompanied by MIG and TIG welding processes. In this work, electron beam welding process were used with or without AlMg4.5Mn as filler material to avoid the degradation of mechanical properties. Mechanical and metallurgical characteristics were also studied in electron beam weldment and heat affected zone. Moreover hot cracking mechanism was also investigated.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.1
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• pp.8-15
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• 2009

Structural studies have been performed on precipitation hardening found in $Ni_{3}Al$ based ordered alloys using transmission electron microscopy (TEM). Tilt experiments by the weak-beam method were made to obtain some information concerning the cross slip mechanism of the superlattice dislocation. The strength of ${\gamma}'-Ni_3$(Al,Ti) increases over the temperature range of experiment by the precipitation of fine $\gamma$ particles. The peak temperature where a maximum strength was obtained shifted to higher temperature. Over the whole temperature range, the interaction between dislocation and $\gamma$ precipitates is attractive. On the temperature range of 773 K to 973 K, the dislocations in ${\gamma}'$ matrix move on (111) primary slip plane. When the applied stress is removed, the dislocations make cross slip into (010) plane, while those in $\gamma$ precipitates remain on the (111) primary slip plane. The increase of high temperature strength in ${\gamma}'-Ni_3$(Al,Ti) containing $\gamma$ precipitates is due to the restraint of cross slip of dislocations from (111) to (010) by the dispersion of disordered $\gamma$ particles.