• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.748-753
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• 2008

Bi-directional load test is one of O-cell tests. The O-cell test is a system which may be used for performing static load tests on cast in situ reinforced concrete bored piles. The technique was devised and developed by Osterberg of Northwestern University(USA) and has been in use around the world. The principle of the method is that an O-cell is installed in a cast in situ bored pile base. Once the pile concrete reaches its design strength the cell is connected to an hydraulic pump and pressured. Pressurisation causes the cell to expand, developing an upward force on the section of pile above the cell loads, pile movements and strains within the pile then enable the capacity of the pile and its load settlement curves to be ascertained. Bi-directional load tests using O-cell are now becoming common practice around the world, particularly where the loads to be applied are high or where it is not convenient to perform top-down loading tests. In the study, calculate ultimate capacity of bi-directional load test using FEM and beam on elasto-plastic foundation theory.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.476-481
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• 2009

Bi-directional load test is one of O-cell tests. The O-cell test is a system which may be used for performing static load tests on cast in situ reinforced concrete bored piles. The technique was devised and developed by Osterberg of Northwestern University(USA) and has been in use around the world. The principle of the method is that an O-cell is installed in a cast in situ bored pile base. Once the pile concrete reaches its design strength the cell is connected to an hydraulic pump and pressured. Pressurization causes the cell to expand, developing an upward force on the section of pile above the cell loads, pile movements and strains within the pile then enable the capacity of the pile and its load settlement curves to be ascertained. The O-cell pile load test with variable end plate is operated on second steps - the first step is to confirming end bearing capacity with variable end plate and the second step is similar to the conventional O-cell test. In the study, To calculate ultimate capacity of bi-directional load test using model with the pile with variable end plate O-cell.

• Current Photovoltaic Research
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• v.8 no.4
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• pp.114-119
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• 2020

In this study, Mitigation of Potential-induced degradation (PID) for PERC solar cells using SiO2 Structure of ARC layer. The conventional PID test was conducted with a cell-level test based on the IEC-62804 test standard, but a copper PID test device was manufactured to increase the PID detection rate. The accelerated aging test was conducted by maintaining 96 hours with a potential difference of 1000 V at a temperature of 60℃. As a result, the PERC solar cell of SiO2-Free ARC structure decreased 22.11% compared to the initial efficiency, and the PERC solar cell of the Upper-SiO2 ARC structure decreased 30.78% of the initial efficiency and the PID reliability was not good. However, the PERC solar cell with the lower-SiO2 ARC structure reduced only 2.44%, effectively mitigating the degradation of PID. Na+ ions in the cover glass generate PID on the surface of the PERC solar cell. In order to prevent PID, the structure of SiNx and SiO2 thin films of the ARC layer is important. SiO2 thin film must be deposited on bottom of ARC layer and the surface of the PERC solar cell N-type emitter to prevent surface recombination and stacking fault defects of the PERC solar cell and mitigated PID degradation.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.884-890
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• 2009

The bi-directional pile load test with variable end plate overcomes the shortcoming of the Osterberg cell test. It is possible that the ultimate bearing capacity of the bi-direction can be known by using the loading of the end plate and two step procedures. The first step is to confirming end bearing capacity with variable end plate and the second step is similar to the conventional O-cell test. In the study, To calculate ultimate capacity of bi-directional load test using model with the pile with variable end plate O-cell, operated with end plate of 3 type on sand layer according to the relative density, loose, medium and dense conditions.

• Korean Journal of Materials Research
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• v.14 no.4
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• pp.287-292
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• 2004

A bio-composites were prepared by mechanical mixing with bioactive sol-gel derived $CaO-SiO_2$ and organic PEEK for bone repairing hybrid materials. The composites were characterized by in-vitro test. A bonelike apatite was formed on the surface of all bio-composites in SBF test. The cell morphology and adhesion on the surface of the composites having below 30% PEEK were clearly observed in L929 cell experiment.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.520-529
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• 2006

그 동안 몇 차례 오스터버그 셀$(O-cell^{\circledR})$을 이용한 양방향 말뚝 재하시험기법이 국내에 성공적으로 소개/적용된 바 있다. 이 방법은 상대적으로 새롭고 독특한 방법으로서 시험비용과 기존 재래적인 시험방법이 적용상 제한을 받는 경우나 대규모 시험에서 발생할 수 있는 문제점들을 극복할 수 있다. 국내에서는 설계목적을 위한 시험말뚝 뿐 아니라 설계하중이 큰 실제말뚝에 대한 시험이 증가하는 추세에 있다. 이 논문에서 소개하는 양방향 재하시험 방법을 적용하면 기존의 소규모 재하시험 방법에서 발생될 수 있는 주면 마찰력과 선단지지력의 분리측정이나 각각의 지지력에 대한 극한상태를 확인하지 못하는 한계를 극복할 수 있고 시험하중이 270MN을 초과하는 경우까지 적용할 수 있는 장점을 갖고 있다. 본 논문에서는 오스터버그 셀을 이용한 정적 재하시험 방법에 대하여 말뚝종류별로 상세히 기술하였으며 이 시험방법의 장점과 국내현장에 적용되었던 사례를 소개하였다.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1142-1147
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• 2008

Nano-structured porous carbon fiber(PCF) for the catalyst supports of the direct methanol fuel cell (DMFC) were prepared from the mesophase pitch by using the nano-MgO powders. Specific surface area of the PCFs was $8{\sim}58m^2/g$ and surface pore structures had almost meso pore diameter of 10~20 nm which were depending on the amount of MgO spheres. Aqueous reduction method was used to load 60 wt% PtRu on the prepared PCF supports. The electro-oxidation activity and single cell performance of the 60 wt% Pt-Ru catalysts were measured by cyclic voltammetry and unit cell test. The performances of these catalysts increased by 5~10% compared with one of commercial catalyst.

• Biomolecules & Therapeutics
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• v.3 no.2
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• pp.122-131
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• 1995

Five human cancer cell lines (HeLa S3, Hep 3B, KATO III, Hs 683, HeLa MR) and one human normal cell line (WI-38) were examined cell viability, northern blot analysis, western blot analysis, and in situ hybridization for the expression $O_{6}$ -methylguanine-DNAmethyltransferase (MGMT), which can repair $O_{6}$ -methylguanine produced in DNA by alkylating agents. In cell viability test, the lethal sensitivities of each strain against anti-tumor drug N,N-bis(2-chloroethyl)- N-nitrosourea (BCNU) were counted, and both BCNU treated and untreated cell extracts were examined for their MGMT inducibility by RNA dot blot analysis. Cell lines did not show MGMT induction by BCNU pretreatment. Tlle MGMT activity was assayed by measuring the $^3$H radioactivity transferred from the substrate DNA containing [methyl-$^3$H)-O$_{6}$ -methylguanine to acceptor molecules in the cell extracts. Extracts from the majority of tumor strains and normal cells contained substantial MGMT activity of varying degree, while the known Mer$^{[-10]}$ cell (lacked or severely depleted in MGMT activity) Hela MR, and Hs 683 (proved to be Mer$^{[-10]}$ ) were much more sensitive to BCNU than the rest of tumor strains, as measured by cell viability test. Overall results above, KATO III showed the highest expression level of MGMT among the strains examined. Furthermore, with all the tumor and normal strains tested, a good correlation was observed between MGMT expression and cellular resistance to BCNU. The varying levels of expression of MGMT in human cancer cells found in this study should provide a molecular basis for MGMT expression among tumor strains from different tissue origin, the information of antitumor agents selection for chemotherapy of cancers.

• Journal of Sensor Science and Technology
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• v.21 no.6
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• pp.395-401
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• 2012

The bond strength of three types of $TiO_2$ coatings onto fluorine-doped $SnO_2$ (FTO) glass was investigated with the aid of a tape test according to ASTM D 3359-95. Transmittance was then measured using an UV-vis spectrophotometer in the wavelength range of 300 nm to 800 nm to evaluate the extent of adhesion of $TiO_2$ nanorods/nanoparticles on FTO glass. A sharp interface between the coating layer and the substrate was observed for single $TiO_2$ coating ($TiO_2$ nanorods/FTO glass), which may be detrimental to the bonding strength. In multicoating sample ($TiO_2$ nanorod/$TiO_2$ nanoparticle/$TiO_2$ nanoparticle/FTO glass), the tape test was not performed due to severe peeling-off prior to the test. On the other hand, the dual coating sample ($TiO_2$ nanorod/$TiO_2$ nanoparticle/FTO glass) showed minimum variation of transmittance (4%) after the test, suggesting that the topcoat adheres well with the FTO substrate due to the presence of the $TiO_2$ nanoparticle buffer layer. The use of a $TiO_2$ nanorod electrode layer with good adhesion may be attributed to the excellent dye sensitized solar cell performance.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.95.1-95.1
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• 2005