• Proceedings of the KSME Conference
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• 2001.06a
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• pp.951-955
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• 2001

The experimental comparison between bonded and unbonded types stem-cement interface was carried out on axisymmetric stem-cement-aluminum model of the femoral component of a total hip replacement. Human femur was modeled in non-tapered and tapered($7.5^{\circ}$) aluminum hollow cylinders to emulate the diaphyseal and metaphyseal segments of the femur. For unbonded type, we tested stems with three different taper angles($5^{\circ},\;7.5^{\circ},\;10^{\circ}$). In every case, the cement-aluminum interface was designed to endure 8MPa shear strength. (a measured value at cement-bone interface) We tested aluminum models under axial loading for both cases. As an experimental result, it was found that unbonded stem sustained more axial load as bonded stem in both cases, diaphyseal and metaphyseal models. The unbonded types failed in cement mantle under axial compressive load, while the bonded ones failed in shear at cement-aluminum interface. These results suggest that a polished stem will sustain much higher axial load than a roughened stem. And a polished stem will make more stable cement-bone interface that may promote better osteosythesis around the stem.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.212-215
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• 2003

In this paper, a model pole transformer was designed to improve the reliability of pole transformers and its short circuit withstand strength was tested. The failure causes of the pole transformers which had been operated in the field were analyzed and several patterns of the causes were determined. A novel countermeasure was devised to prevent the failures of the pole transformers in advance. A model pole transformer was designed and made in accordance with the given specifications to strengthen the short circuit withstand capability and its characteristic was tested. As a result, the advanced performance of the model pole transformer was confirmed and novel techniques in manufacturing process was suggested. It is considered that all the methods employed in the developing process will be helpful to design and manufacture the pole transformers thus the reliability of pole transformers in distribution lines will be improved.

• Journal of Korean Physical Therapy Science
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• v.19 no.1
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• pp.47-54
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• 2012

Purpose : This study is to know the effect on muscle activity when people use mouse aid or not in computer working environment. Method : 11 people of both sex in their twentieth were tested. As a independent variable, the condition without mouse aid and the condition with movable mouse aid were selected, and as a dependent variable, MVC(%) on four muscles and inconvenience degree(RPE scale) on three body part(wrist, forearm, shoulder) were measured. Result : Analyzing the research, MVC(%) of extensor muscle of finger had notably higher muscle activity than other muscles, and there wasn't notable difference in muscle activity before and after using mouse aid. In case of using mouse aid, we tested by giving RPE questionnaire which segmentalized mental fatigue degree into hand, forearm, and shoulder, and resultingly, there wasn't notable differences perspectively. However, people felt less tiredness subjectively after they use the mouse aid. Conclusion : The usage of mouse aid seems to give comfort to computer users.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.704-709
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• 2009

The emergence of methicillin-resistant of Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) has led to an urgent need for the discovery and development of new antibacterial agents. As part of an ongoing investigation into the antibacterial properties of the natural products, (2S)-7,4'-dihydroxy-5-methoxy-8-(${\gamma}$, ${\gamma}$-dimethylally)-f1avanone (2S-DMDF), isolated from the roots of Sophora flavescens, was found to be antibacterial active MRSA and VRE. Sophora flavescens has been used as antibacterial, antiviral, antiprotozoal, anti-inflammatory. Therefore, this study investigated the antibacterial activity of 2S-DMDF against all the bacterial strains tested. In this result, at the end point of an optically clear well, the minimum inhibitory concentrations (MICs) ranged from 0.97 to 15.6 mg/ml for 2S-DMDF, from 125 to 256 mg/ml for ampicillin, and from 64 to 512 mg/ml for gentamicin with MRSA, also, 7.8 to 15.6 mg/ml for 2S-DMDF, from 125 to 256 mg/ml for ampicillin, and from 512 to 1024< mg/ml for vacomicin with VRE. These findings indicated that the application of the tested 2S-DMDF alone might prove useful in the control and treatment of MRSA and VRE infections.

• The Mathematical Education
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• v.47 no.4
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• pp.487-503
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• 2008

In this paper, descriptive assessment method for middle school mathematics was evaluated by developing a framework for designing and grading problems for descriptive assessment and analyzing the effectiveness of the problems. The new descriptive assessment problems were developed by reviewing the current 7th National Mathematics Curriculum of Korea and aligned mathematics textbooks to define a set of problem design principles and evaluation framework for the assessment strategy. The developed problems were first pilot tested and then revised based on the feedback from the test. The final version was field tested by 100 students in 7th grade middle school. After the field test, the problems were graded by two middle school math teachers and one math education researcher to determine the overall correlation between graders and also to analyze effectiveness of the evaluation framework of the test. This result of this study is expected to assist in the further development of descriptive problems and grading framework by providing a reference work for teachers to better understand the process and the limitations of executing the new assessment strategy.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.172-173
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• 1998

A research collection of Pseudomons solanacearum bacteria, a pathogen causing ‘bacteria wilt’ disease of more than 265 plant species, represented for northern provinces of Vietnam has recently been established and was saved for examination of antifungal activity in their culture fluids. All strains used in this work have been isolated from infected tomato, potato, and groundnut collected from production fields and they express different levels of virulence on their host plants. Cell-free culture fluids of these strains were tested for antifungal activity (to inhibit growth of mycelium and to destroy germination tube of fungal spores) on a number of fungi that either infect or associate with vegetable crops of Solanaceae family (tomato, potato, pepers...), fruit plants (banana), and even well-known by Vietnamese traditional medicine herbal plants belonging to Trifoliatus, Schefflera, Homalomena and Panax genera (Araliaceae family) of which roots are used as a resource of the herbal material. The antifungal activity was found in nearly all strains tested. Result of study on chitin, CMC, tween 80 and casein degradation abilities of the latter suggested that antifungal activity of positively-found strains may be due to their ability of extracelluar chitinase's excretion that destroy fungal cell wall.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.8
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• pp.111-121
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• 2005

A 100kW class gas turbine combustor was developed and tested for PPU(Primary Power Unit) of ground vehicle. The combustor which employed annular-reverse type and pressure swirl atomizer was designed through 1-D analysis, 3-D thermal flow analysis and combustor performance was experimentally investigated on the combustor test rig. The test result was satisfactory. The developed combustor was also tested for environmental and endurance specification under engine adopted conditions and the application of a state-of-the-art gas turbine combustor to ground vehicle PPU turned out to be successful.

• YAKHAK HOEJI
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• v.45 no.1
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• pp.108-115
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• 2001

We have recently reported the development of a high efficiency expression vector, pCK, which can drive a high level of gene expression in mouse skeletal muscle. In this study, we tested the therapeutic potential of pCK expressing human VEGF165, pCK-VEGF in the rabbit ischemic hind limb model. To determine the optimal dose of plasmid DNA, various concentrations of pCK-CAT were injected into the muscle of a rabbit hind limb and the levels of CAT activity were determined. It was found that the expression level of the exogenously added gene became stable between 250 and 1,000 $\mu$g. Based on this result, we tested whether intramuscular transfer of 500$\mu$g of pCK-VEGF could actually modulate collateral vessel development in a rabbit ischemic hind limb model. It was found that relative to the control group injected with the pCK lacking the VEGF sequence, single intramuscular doses (500$\mu$g) of pCK-VEGF produced statistically significant augmentation of collateral vessels as determined by the angiographic vessel count, maximal blood flow by Doppler flowmeter and the number of capillaries by histology. These results suggest that a single 500$\mu$g-delivery of pCK-VEGF is potent enough to induce sufficient angiogenic activity and achieve therapeutic benefit on this rabbit model.

• YAKHAK HOEJI
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• v.47 no.3
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• pp.184-189
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• 2003

Peptide deformylase (PDF) is essential and unique to bacteria, thus making it an attractive target for the discovery of novel antibacterial drugs. PDF deformylates the N-formylmethionine of newly synthesized polypeptides in prokaryotes. In this study, a pdf gene from Staphylococcus aureus 6538p was cloned in pET-14b vector and PDF protein was over-produced in Escherichia coli BL21 (DE3). NH$_2$-terminal His-tagged PDF protein was purified by nickel-nitrilotriacetic acid (Ni-NTA) metal-affinity chromatography. Enzymatic activity of purified 6xHis-tagged PDF was tested on the substrate (formyl-Methionine-Alanine-Serine) by formate dehydrogenase-coupled spectrometric assay of peptide deformylase. For the discovery of new PDF inhibitors from chemical libraries and culture broths of soil bacteria, a target-oriented screening system using a 96-well plate was developed. About 3,000 commercial chemical libraries were tested in this screening system, and 2 chemicals (0.07％) among them showed an inhibitory activity against PDF enzyme. This result showed that a new screening system can be used for the discovery of new PDF inhibitors.

• Mycobiology
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• v.31 no.4
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• pp.229-234
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• 2003

A total of 24 isolates of Phytophthora infestans were tested and analyzed for their resistance to metalaxyl fungicides. Sensitivity to metalaxyl was determined by growing isolates on 20% V8 medium amended with 0, 5, and 100 ${\mu}g/ml$ metalaxyl. Four isolates among the 24 tested were resistant to metalaxyl. Eleven isolates were intermediate and nine isolates were sensitive. Amplified fragment length polymorphism(AFLP) assay was used to identify the amplification products of resistant isolates. As a result, selected fragments were cloned, sequences and primer pairs were developed which linked to metalaxyl insensitivity in P. infestans using competitive PCR.