• Journal of Pharmacopuncture
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• v.21 no.2
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• pp.70-75
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• 2018

Objective: Diseases of the respiratory system are one of the main causes of death and include situation such as chronic obstructive pulmonary disease, pneumonia or asthma. Medicinal plants have beneficial effects on multiple diseases include respiratory disorders like asthma and bronchitis. The aim of this study was to evaluate the effects of U. dioica and L. Album on tracheal smooth muscle contraction. Material and methods: Hydroalcoholic extracts of L. Album and U. Dioica aerial parts were prepared by maceration method and standardized based on their total phenol content. The effect of the extracts on the KCl-induced contraction of rat trachea was examined in an organ bath chamber. Data was analyzed with spss software 22. Results: The extract of L. Album (5 mg/ml), similar to theophylline (20 mM), significantly reduced the KCl-induced tracheal contraction. On the other hand, U. Dioica (1 mg/ml and 5 mg/ml) augmented the KCl-induced contraction. Conclusion: The relaxant effect of L. Album on the trachea makes it as a candidate for the managing patients with asthma and obstructive pulmonary diseases. But because of U. Dioica potential constrictive effect on the trachea it is suggested that patients avoid consuming it.

• Journal of Surface Science and Engineering
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• v.47 no.3
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• pp.128-136
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• 2014

In the present study, we successfully developed an eco-friendly chemical etching solution and proper condition for plating on ABS material. The mechanism of forming Ni plating layer on ABS substrate is known as following. In general, the etching solution used for the etching process is a solution of chromic acid and sulfuric acid. The etching solution is given to the surface resulting in elution of butadiene group, so-called anchor effect. Such a rough surface can easily adsorb catalyst resulting in the increase of adhesion between ABS substrate and Ni plating layer. However a use of chromic acid is harmful to environment. It is, therefore, essential to develop a new alternative solution. In the present study, we proposed an eco-friendly etching solution composed of potassium permanganate, sulfuric acid and phosphoric acid. This solution was testified to observe the surface microstructure and the pore size of electrical Ni plating layer, and the adhesive correlation between deposited layers fabricated by electro Ni plating was confirmed. The result of the present study, the newly developed, eco-friendly etching solution, which is a mixture of potassium permanganate 25 g/L, sulfuric acid 650ml/L and phosphoric acid 250ml/L, has a similar etching effect and adhesion property, compared with the commercially used chromium acid solution in the condition at $70^{\circ}C$ for 5 min.

• Journal of Korea Foundry Society
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• v.21 no.4
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• pp.239-245
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• 2001

Microstructure and mechanical properties of Sn-3.1 wt.%Ag-6.9 wt.%Bi system solders on Cu-substrate were studied. The Sn3.1 wt.%Ag-6.9 wt.%Bi alloy was designed by phase diagram and chemical properties and was prepared by melting in argon atmosphere. The mechanical properties of solder/Cu joints were examined by shear strength test, and also creep test. The microstructure of Sn-3.1 wt.%Ag-6.9 wt.%Bi alloy consists of Bi-rich phase and $Ag_3Sn$ precipitate in {\beta}-Sn$ matrix phase. The shear strength of the joint was decreased with aging treatment. Crack path under shear test was through the solder. Similar crack path change mode was observed at the creep test of solder/Cu joint. The creep behavior of Sn-3.1 wt.%Ag-6.9 wt.%Bi alloy represented the inverse primary creep behavior at all test condition. It is suggested that the inverse primary creep behavior is induced from Bi solute atoms in Sn-matrix. The creep resistance of Sn-3.1Ag-6.9Bi alloy is better than that of Sn-3.5 wt.%Ag alloy at all test conditions.

• Journal of Korea Foundry Society
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• v.22 no.6
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• pp.281-287
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• 2002

In order to investigate the variation of microstructure and property of the Electro-slag Remelted M2 steel, microstructure observation, hardness, and bending test were performed by using optical microscope. SEM/EDS, rockwell hardness tester, charpy impact tester and bending tester, respectively. It was revealed that the number of inclusions and content of gas elements(S, O, N) in M2 steel fabricated by ESR process decreased markedly compared to those of AIM. It seems to be due to refining effect of ESR process. The volume fraction of carbides in quenched and tempered specimens after austenitizing at 1150$^{\circ}C$ and 1240$^{\circ}C$ was measured. The volume fraction of grain boundary carbides were found to be similar for both specimens. However, The volume fraction of carbides in grain decreased with an increase of austenitizing temperature. When specimen was austenitized at 1150$^{\circ}C$, grain boundary carbides showed needle like morphology. But, the carbides were broken with an increase of austenitizing temperature. The specimen austenitized at 1240$^{\circ}C$ showed higher hardness and lower bending strength compared to that of 1150$^{\circ}C$. As expected, toughness increased with sub-zero quenching treatment.

• Journal of the Korean Geotechnical Society
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• v.31 no.3
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• pp.27-38
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• 2015

Triaxial tests on sand-silt mixture specimens under low and high confining pressures were performed to understand their shear behaviors. The fines content in the mixture is lower than the threshold value. A series of tests under different conditions including fines contents (0%, 9.8%, 14.7%, 19.6%), density of specimen (controlled by different compaction energies of $E_c=22kJ/m^3$, $E_c=504kJ/m^3$), confining pressure (100 kPa, 1 MPa, 3 MPa, 5 MPa) were performed to investigate influences of these factors. Based on the test results, the threshold fines content, where the dominant structure of mixture changes from sand-matrix to fines-matrix, decreases with the increase of confining pressure. Under very high confining pressures, as a result of sand particle crushing, the behavior of the dense specimen is similar to that of the loose specimen which shows hardening, compression behavior, and shear strength increases with increase of fines content. In conclusion, silt is granular material like sand, and its influence on shear behavior of sand-silt mixture is very different from that of plastic fines on sand-fines mixture.

• Journal of Hydrogen and New Energy
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• v.19 no.5
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• pp.394-402
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• 2008

The Effects of Cu or Ni additives co-added with Ce/Zr mixed oxides to Fe-based oxide mediums were investigated for the purpose of the replacement of Rh, a precious metal additive, in terms of hydrogen storage(reduction by hydrogen) and release(water splitting). From the results of temperature programmed reduction(TPR), initial reduction rate of iron oxide in the mediums was greatly increased with the addition of Cu, similar to that of Rh. For isothermal redox reaction of 10 cycles, the total amounts of hydrogen evolved in water splitting steps for the mediums added with Cu or Ni were highly maintained at ca. 7 mmol/g-material, even though the oxidation rates were slightly lower than that for the medium added with Rh. This result suggests that the replacement of Rh to Cu or Ni is possible as a co-additive for Fe-based oxide mediums.

• Journal of the Korean GEO-environmental Society
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• v.15 no.7
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• pp.51-58
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• 2014

In-situ capping is a method to stabilize contaminated sediments by isolation. Few researches on the in-situ capping have been performed, although the engineering approach is still required to prevent the release of contaminants. In this study, hydraulic model test were conducted by using a wave generator to observe the change of cap thickness which is important factor in design of capping. Sands with particle size between 0.075 to 2 mm as capping materials were used to observe the change of capping thickness by waves. The experimental results show that the surface of capping materials is similar to wave form. The more wave height increases, the more erosion of capping materials increases.

• Journal of the Korean GEO-environmental Society
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• v.14 no.5
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• pp.23-32
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• 2013

This paper presents the effect of pile diameter on the lateral behavior of offshore pile for wind turbine. The material parameters of the soils were estimated through SPT on the Southwestern offshore area in Korea, where the first wind farm is planned. The FDM software, FLAC3D, and LPile were adopted to derive the load-displacement curve, p-y curve, and maximum bending moment at a specified displacement. It was found that the results from softwares significantly differ and the LPile could overestimate the allowable capacity. The maximum bending moment along the pile with 2m diameter could be as large as four times the bending moment with 1m diameter. Similar trend was observed for the allowable lateral capacity.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.1
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• pp.30-40
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• 2005

Purpose. The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the incisal reduction (2.0mm, 2.5mm, 3.0mm) and axial inclination ($4^{\circ}$, $8^{\circ}$, $12^{\circ}$) of the upper canine. Material and methods. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and the universal testing machine was used to measure the fracture strength. Results. 1. The fracture strength of the ceramic crown with 3.0mm depth and $12^{\circ}$ inclination was the highest (839N) Crowns of 2.0mm depth and $12^{\circ}$ inclination had the lowest strength (559N). 2. There was no significant difference in the fracture strength by axial inclination in the same incisal reduction group. 3. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin irrespective of incisal reduction.

• Journal of Periodontal and Implant Science
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• v.24 no.1
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• pp.120-130
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• 1994

The purpose of the present investigation was to compare the effectiveness of porous hydroxyapatite (PHA) and coralline based porous calcium carbonate(PCC) as implant materials in human periodontal osseous defects. 10 adult patients having periodontitis and 2 similar angular osseous defects ${\ge}$5mm as verified by radiographic analysis and clinical probing depth ${\ge}$4mm were selected. The measurements were recorded just before surgery and after 6 month. Clinical parameters used in this study included gingival recession, pocket depth, probing attachment level, Sulcus Bleeding Index, Plaque Index, tooth mobility and bone defect depth measurements. After initial therapy, patients were treated with mucoperiosteal flap surgery. The contralateral bony defects in each patient randomly assigned to either bone graft material, one with PHA(Interpore 200) and the other with coralline based calcium carbonate(Biocoral). After 6 month both groups showed statistically significant reduction of pocket depth, Sulcus Bleeding Index, Plaque Index and significant improvement in probing attachment level. No statistically significant differences were found between the groups. There were 3.0mm or 68% of bone repair with PHA and 3.1mm, 61% with PCC. These values were likewise not significantly different. The data and clinical impression strongly suggest that both PHA and PCC are alloplastic implants with clinically apparent acceptance by the soft and hard tissue and that they can be used as bone graft materials successfully.