• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.317-321
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• 2009

In order to analyze the high temperature phase formation and the sinterability of super ionic conductor $K^+-{\beta}/{\beta}"-Al_2O_3$ which is commonly used as a solid oxide electrolyte, the pure $K^+-{\beta}/{\beta}"-Al_2O_3$ powder in the ternary system $K_2O-LiO_2-Al_2O_3$ was synthesized by solid state reaction and formed to tube and disk using slip casting method and cold isostatic pressing (CIP), respectively. The slip casting was conducted in an alumina mold with the slurry containing 40 wt% of solid contents and the CIP was carried out under 20 MPa. The samples were sintered at $1600^{\circ}C$, $1700^{\circ}C$ and $1750^{\circ}C$, respectively, and their phase formation and the sintering density were investigated according to the forming method. The samples produced by CIP showed far higher ${\beta}"-Al_2O_3$ fraction as compared with those by slip casting. On the other hand, the samples by slip casting showed slightly higher sintering density. The relative density reached to about 83% at $1750^{\circ}C$ and for 1 h, independent of the forming method. In the case of 90 min socking time, the density was decreased owing to the exaggerated grain growth and the pores by $K_2O$ evaporation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.330-335
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• 2017

The demand for electric motor fuel cells has surged in the automotive industry, leading to a recent increase in the demand for square aluminum cans used as fuel cell battery casings. The air vent located on the bottom of the rectangular battery casing prevents large explosions by intermittent pressure release prior to the accumulation of abnormally high pressures. Conventionally, the square cup battery casing is produced via six-step deep drawing, with the outer shape of the vent being manufactured by welding to the square battery casing. On the other hand, this study directly incorporated the air vent outlet into the bottom surface of the rectangular casing. The product of a coupled finite element analysis technique applying the thickness and contour generated from the square cup multi-step deep drawing formation analysis was used as the forging input shape. The results yielded increased prediction accuracy and the advanced prediction of defects, such as swelling and fracture. Based on the results of the initial analyses, two of the generated forging shapes were determined to be suitable, with the optimal forging shape being determined by molding analysis. The results presented here were validated by mold fabrication and a subsequent comparison of the actual and analytical results.

• The Korean Journal of Urological Oncology
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• 제15권3호
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• pp.178-186
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• 2017

Purpose: Poloxamer 407 (P407) thermo-sensitive hydrogel formulations were developed to enhance the retention time in the urinary bladder after intravesical instillation. Materials and Methods: P407 hydrogels (P407Gels) containing 0.2 w/w% fluorescein isothiocyanate dextran (FD, MW 4 kDa) as a fluorescent probe were prepared by the cold method with different concentrations of the polymer (20, 25, and 30 w/w%). The gel-forming capacities were characterized in terms of gelation temperature (G-Temp), gelation time (G-Time), and gel duration (G-Dur). Homogenous dispersion of the probe throughout the hydrogel was observed by using fluorescence microscopy. The in vitro bladder simulation model was established to evaluate the retention and drug release properties. P407Gels in the solution state were administered to nude mice via urinary instillation, and the in vivo retention behavior of P407Gels was visualized by using an in vivo imaging system (IVIS). Results: P407Gels showed a thermo-reversible phase transition at $4^{\circ}C$ (refrigerated; sol) and $37^{\circ}C$ (body temperature; gel). The G-Temp, G-Time, and G-Dur of FD-free P407Gels were approximately $10^{\circ}C-20^{\circ}C$, 12-30 seconds, and 12-35 hours, respectively, and were not altered by the addition of FD. Fluorescence imaging showed that FD was spread homogenously in the gelled P407 solution. In a bladder simulation model, even after repeated periodic filling-emptying cycles, the hydrogel formulation displayed excellent retention with continuous release of the probe over 8 hours. The FD release from P407Gels and the erosion of the gel, both of which followed zero-order kinetics, had a linear relationship ($r^2=0.988$). IVIS demonstrated that the intravesical retention time of P407Gels was over 4 hours, which was longer than that of the FD solution (<1 hour), even though periodic urination occurred in the mice. Conclusions: FD release from P407Gels was erosion-controlled. P407Gels represent a promising system to enhance intravesical retention with extended drug delivery.

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.35-45
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• 2013

The concrete-filled tube column has the excellent structural performance. But it is difficult to connect with column and beam because of closed section. It suggests that pipe should be produced by welding two sides together where two shapes are joined after a channel is pre-welded onto the three sides in order to form an internal diaphragm. The upper diaphragm of the connection used the horizontal plate and the lower diaphragm used the Vertical plate. This research performed 6 monotonic tension experiments describing the connection upside and downside in order to evaluate the structural capability of the offered connection. And the cyclic loading experiment was performed about 2 T-Type column to beam connections. As to the experimental result edge cutting geometry, there was no big effect. An increase in the number of holes of the plate ultimate strength was increased by 5% and The thickness of the plate increases, the maximum strength was increased by 4%. T-Type connections until it reaches the plastic moment showed a stable behavior.

• Journal of Animal Science and Technology
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• v.50 no.3
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• pp.429-436
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• 2008

A bacterium producing cold-active cellulase and xylanase was isolated from pig feces. The isolate, DK42 strain, was found to be the Gram-positive, non-motile, catalase-positive, and spore-forming stain. Under an electron microscope, the cells were observed to be rod-shaped. The isolate was identified as Bacillus licheniformis DK42 on the basis of morphological and biochemical properties as well as 16S rRNA gene sequences. The characterization of crude cellulase and xylanase from B. licheniformis DK42 was investigated. Cellulase exhibited an optimum temperature and pH at 45℃ and 6.0, whereas xylanase exhibited an optimum temperature and pH at 55℃ and 6.0. Especially cellulase maintained approx. 50% of its maximum activity even at 10℃, indicating that it is cold-active. Both cellulase and xylanase were stable after 2hr at 35℃, whereas they lost their activities after 30min at 65℃.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.617-624
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• 2021

Concrete-filled steel tubular columns can improve the strength and deformation capacity of structures, thereby enabling the development of efficient structures. The Korean design standard (KDS41) regarding concrete-filled steel tubular structures, established by the architectural institute of Korea in 2005, was revised in 2009 and 2016. The objective was to understand the compressive strengths and deformation capacity of stub columns for concrete-filled square steel tubes under uniaxial compression and validate the KDS41's standard code for necessary corrections. Experiments were conducted on 26 specimens with parameters, such as the width-thickness ratio of cold-formed square tubes. The following values of the stub columns for concrete-filled square steel tubes were obtained: compressive strengths, relationship between the axial load and axial displacement, and failure modes. An analysis of these results enabled an understanding of the concrete-filled effect and the influence of the wide-thickness ratio. The compressive strengths of filled concrete saw a 9% increase compared to a state of uniaxial stress, which must be noted in a future edition of KDS41. After benchmarking the results regarding square steel tubes generated by cold forming to the guidelines provided by the KDS41, the KDS41's value of 2.26 for the limiting width-to-thickness ratio for the compact section was found to be inflated. With a safety concern, this paper proposes a more conservative value of 1.35.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.143-150
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• 2010

Purpose: The purpose of this study is to fabricate the new zirconia block (CNU block) and to evaluate fit of core and porcelain veneered zirconia crown. Material and methods: The experimental blocks were fabricated from the commercial ytrria-stabilized zirconia powder (KZ-3YE Type A). The powder was uniaxial pressing and the green bodies were conducted using the Cold Isostatic Pressing. The zirconia blocks were presintered at $1040^{\circ}C$ and the final sintering was performed at $1450^{\circ}C$. The Kavo Everest ZS $blank{(R)}$ (KaVo, Biberach/ $Ri{\beta}$.) was used as a control group. The linear shrinkage of CNU block and Kavo block were compared. Twenty-one cores for porcelain veneered crowns were fabricated with CAD/CAM system ($Everest{(R)}$, Biberach/ $Ri{\beta}$.). Group I; seven cores fabricated from Kavo blocks, Group II; seven cores fabricated from CNU blocks, Group III; seven cores from CNU blocks and porcelain veneering for crowns. All specimens were cemented and sectioned into two planes; diagonal and bucco-lingual. The measurement of the marginal, internal, and occlusal fit was carried out using SEM ($S-4800^{(R)}$) at $30{\times}$. The results were analyzed by one-way ANOVA test. Results: The linear shrinkage of the CNU block and the KaVo block was 19.00% and 20.09%. The marginal gap of cores ($29.67{\pm}6.58{\mu}m$) fabricated from CNU blocks showed significantly smaller than that of the cores of Kavo blocks ($36.84{\pm}7.18{\mu}m$) (P < .05). The internal gaps of the porcelain veneered crowns ($32.23{\pm}6.33{\mu}m$) were larger than those of the other two groups ($37.57{\pm}6.81{\mu}m$ and $38.14{\pm}6.81{\mu}m$). Conclusion: No statistically significant difference was found in between experimental groups and control group. The experimental groups in marginal gap showed significantly smaller than the control group.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.243-248
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• 2012

Nearby spiral galaxies M101 and M81 are considered to have undergone a galaxy-galaxy interaction. M101 has experienced HI gas infall due to the interaction. With AKARI far-infrared (IR) photometric observations, we found regions with enhanced star forming activity, which are spatially close to regions affected by the interaction. In addition, the relation between the star formation rate (SFR) and the gas content for such regions shows a significant difference from typical spiral arm regions. We discuss possible explanations for star formation processes on a kiloparsec scale and the association with interaction-triggered star formation. We also observed the compact group of galaxies Stephan's Quintet (SQ) with the AKARI Far-infrared Surveyor (FIS). The SQ shows diffuse intergalactic medium (IGM) due to multiple collisions between the member galaxies and the IGM. The intruder galaxy NGC 7318b is currently colliding with the IGM and causes a large-scale shock. The 160 micron image clearly shows the structure along the shock ridge as seen in warm molecular hydrogen line emission and X-ray emission. The far-IR emission from the shocked region comes from the luminous [CII]$158{\mu}m$ line and cold dust (~ 20 K) that coexist with molecular hydrogen gas. Survival of dust grains is indispensable to form molecular hydrogen gas within the collision age (~ 5 Myr). At the stage of the dusty IGM environment, [CII] and $H_2$ lines rather than X-ray emission are powerful cooling channels to release the collision energy.

• Journal of Korean Academy of Nursing
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• v.25 no.4
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• pp.641-652
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• 1995

Working as nurses, authors found that some patients were not content with their hospital life. Some patients wanted to move to another ward, and others complained about their ward atmosphere. In spite of patients' discomfort, nurses didn't know what made some patients complain about their ward. So, authors tried to find factors that influence atmosphere of hospital wards of the neurosurgery patients. To know the atmosphere of wards, authors selected five neurosurgery ward of a university hospital in Seoul. Observation took a month. An author observed using molar approach, in the morning, in the day time, and in evening time. Authors used concealment /no intervention technique. An author checked condition of people in the wards, and observed their verbal and nonverbal communication behavior their activities and environmental characteristics, and interpreted their meaning through ethnographic research methodology by Spradly. Authors found there was an important factors that influence the atmosphere of ward. It was a human and his attitude. At least one person who was willing to help others made ward atmosphere better. Helping others physically whenever needed, sup-porting the depressed emotionally, offering foods, or talking to others friendly brought good atmosphere. On the contrary, if everyone was indiffernt to others, the atmosphere became cold. Self-centered or selfish behaviors such as occupying too much area, using the toilet too long, covering other's suction bottle without permission and seeing others delicate or urinate were hurtful. In addition to the attitude of patients and their families, unkindness of medical teams including nurses and doctors and tasteless meal caused bad ward atmosphere. Based on this research finding, authors suggest the followings. A For the better atmosphere of ward 1. Nurses should try to make the ward atmosphere better by introducing new patient to older ones. 2. Every ward should have dividing curtains to keep patient's privacy. 3. All hospital personnel should be kind enough to make patients feel that they are repected. 4. Hospital should serve high quality meals to patients. 5. Patients had better stay with those in the similar condition. B. For the future studies 1. Repeated researches are necessary to check reliability of this results. 2. Researches for patients in different area such as ICU, or hemodialysis unit are necessary.

• Korean Journal of Plant Tissue Culture
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• v.27 no.4
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• pp.339-343
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• 2000

When plants are exposed to subfreezing temperatures ice crystals are forming within extracelluar space in leaves. The growth of ice crystal is closely related to the degree of freezing injury. It was shown that an antifreeze protein binds to an ice nucleator through hydrogen bonds to prevent growth of ice crystal and also reduces freezing damage. The antifreeze proteins in plants are similar to PR proteins but only the PR proteins induced upon cold acclimation were shown to have dual functions in antifreezing as well as antifungal activities. Three of the genes encoded for CLP, GLP, and TLP were isolated from barley and Kentucky bluegrass based on amino acid sequence revealed after purification and low temperature-inducibility as shown in analysis of the protein. The deduced amino acid of the genes cloned showed a signal for secretion into extracellular space where the antifreezing activity sup-posed to work. The western analysis using the antisera raised against the antifreeze proteins showed a positive correlation between the amount of the protein and the level of freeze tolerance among different cultivars of barely. Besides it was revealed that TLP is responsible for a freeze tolerance induced by a treatment of trinexapac ethyl in Kentucky bluegrass. Analysis of an overwintering wild rice, Oryza rufipogon also showed that an acquisition of freeze tolerance relied on accumulation of the protein similar to CLP. The more direct evidence for the role of CLP in freeze tolerance was made with the analysis of the transgenic tobacco showing extracellular accumulation of CLP and enhanced freeze tolerance measured by amount of ion leakage and rate of photosynthetic electron transport upon freezing. These antifreeze proteins genes will be good candidates for transformation into crops such as lettuce and strawberry to develop into the new crops capable of freeze-storage and such as rose and grape to enhance a freeze tolerance for a safe survival during winter.