• Proceedings of the PSK Conference
• /
• 2005.11a
• /
• pp.146-148
• /
• 2005

• Journal of Welding and Joining
• /
• v.33 no.6
• /
• pp.21-26
• /
• 2015

Recently, application of UHSS(Ultra High Strength Steels) whose tensile strength is over 1000MPa to car body structure are growing due to great needs for light weighting and improved crash worthiness. However, their poor weldability is one of obstacles to expand selecting to car body. In this study, effect of Phosphorus contents on resistance spot weldability of high elongation DP980 steel whose Si content is over 1% was investigated. The cross tension strength (CTS) was decreased showing partial interface fracture as Phosphorus content increase because of solidification segregation of Phosphorus. In order to improve resistance spot weldability by modification of welding condition, in-situ post-weld heating pulse was introduced after main pulse. The optimum cooling time between main and post pulse and post-pulse current condtion were determined through FEM welding simulation and DOE tests. The CTS was increased about 1.5 time showing plug fracture. The decrease of Phosphorus segregation was found to be a major reason for weld ductility and CTS improvement.

• Macromolecular Research
• /
• v.17 no.8
• /
• pp.603-608
• /
• 2009

Novel ultra-high molecular weight polyethylene (UHMWPE)/zirconia composites were previously prepared by the in situ polymerization of ethylene using a Ti-based Ziegler-Natta catalyst supported on to the surface of zirconia, as a bearing material for artificial joints. Tribological tests revealed that a uniform dispersion of zirconia in UHMWPE markedly increased the wear resistance. The effects of zirconia content on the oxidation behavior of the ${\gamma}$-ray-treated UHMWPE/zirconia composite surfaces were examined. The oxidation index that estimates the oxidation degree as the content of total carbonyl compounds was monitored using Fourier transform infrared spectroscopy-attenuated total reflectance. The changes in the surface composition due to the oxidation were confirmed by electron spectroscopy for chemical analysis. The extent of oxidation decreased with increasing zirconia content, which was attributed to the increased crystallinity as well as the decreased polymer portion of the UHMWPE/zirconia composites.

• Journal of Radiation Protection and Research
• /
• v.43 no.3
• /
• pp.85-96
• /
• 2018

Background: A variety of inorganic scintillators have been developed and improved for use in radiation detection and measurement, and in situ gamma-ray spectrometry in the environment remains an important area in nuclear safety. In order to verify the feasibility of promising scintillators in an actual environment, a performance test is necessary to identify gamma-ray peaks and calculate the radioactivity from their net count rates in peaks. Materials and Methods: Among commercially available scintillators, $LaBr_3(Ce)$ scintillators have so far shown the highest energy resolution when detecting and identifying gamma-rays. However, the intrinsic background of this scintillator type affects efficient application to the environment with a relatively low count rate. An algorithm to subtract the intrinsic background was consequently developed, and the in situ calibration factor at 1 m above ground level was calculated from Monte Carlo simulation in order to determine the radioactivity from the measured net count rate. Results and Discussion: The radioactivity of six natural radionuclides in the environment was evaluated from in situ gamma-ray spectrometry using an $LaBr_3(Ce)$ detector. The results were then compared with those of a portable high purity Ge (HPGe) detector with in situ object counting system (ISOCS) software at the same sites. In addition, the radioactive cesium in the ground of Jeju Island, South Korea, was determined with the same assumption of the source distribution between measurements using two detectors. Conclusion: Good agreement between both detectors was achieved in the in situ gamma-ray spectrometry of natural as well as artificial radionuclides in the ground. This means that an $LaBr_3(Ce)$ detector can produce reliable and stable results of radioactivity in the ground from the measured energy spectrum of incident gamma-rays at 1 m above the ground.

• Journal of Conservation Science
• /
• v.27 no.3
• /
• pp.277-290
• /
• 2011

The aim of this study is to examine the efficiency of ethylsilicate consolidants on sandstone according to its weathering state for an appropriate application to stone cultural heritage in Yeongyang area. Yeongyang area had sandstone and conglomeratic sandstone cultural heritages which needed conservation intervention due to granular disintegration and scaling on their surface. Hyeonri Three-storied Pagoda having typical stone materials in this area was investigated for the analyses of the material and deterioration. And both in-situ and laboratory applications of consolidants were conducted to the outcrop which had the same characteristics of rock type and weathering grade. As a result of the application, it was concluded that Wacker OH 100 and Remmers 300 showed the most appropriate consolidating effect, and Remmers 300 was the most effective to strengthen the loosen and granular-disintegrated surface of the sandstone.

• 한국지구물리탐사학회:학술대회논문집
• /
• 1999.08a
• /
• pp.156-175
• /
• 1999

Recently the application of geophysical well logging to geotechnical site investigation is increasing, because the merit that geophysical logs provide the high resolution and in-situ physical properties in volumes of rock surrounding the borehole. Geophysical well logs are used to identify lithologic boundaries and fracture, to determine the physical properties of rock(i.e., density, velocity etc.), and to detect permeable fracture zones that could be conduits for ground water movement through the rocks. The principle of heat-pulse meter, the calibration of gamma-gamma logging, and principles and data processing of full waveform sonic logging are briefly reviewed, and the case studies of geophysical logs are discussed. Correlation between velocity by sonic logging and rock mass classification such as RMR(Rock Mass Rating) value is considered.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.46 no.5
• /
• pp.19-26
• /
• 2014

In-situ $CaCO_3$ formation on recycled wood pulp was studied to improve optical property and filler attachment to the fiber furnish in papermaking. We tried to attach calcium oxide (CaO) to the recycled fibers, old newspaper (ONP) in this case, by using selected polymers before in-situ $CaCO_3$ formation reaction on fibers, and then, $CO_2$ was injected to the furnish until all the CaO on fiber surfaces was consumed. It was found that the attachment of newly formed $CaCO_3$ to recycled fibers became stronger by attaching CaO to the fibers before in-situ $CaCO_3$ formation reaction. It was expected that the polymers used for the attachment of calcium source to the fiber furnishes helped to keep the newly formed $CaCO_3$ strongly attached to the fiber surface as well as to retain the impurities associated with calcium source and recycled fibers, if any. In-situ $CaCO_3$ formation gave higher brightness and much less ERIC value in ONP sheet than the case when the equivalent amount of GCC was added to the furnish.

• International Journal of Highway Engineering
• /
• v.11 no.2
• /
• pp.85-98
• /
• 2009

The in-situ Compaction test using sand cone (RC) and Plate Bearing Capacity Test (PBT) has been widely used for evaluating the subgrade and subbase condition on the pavement system. However, because the in-situ RC and PBT test are expensive and take plenties of time for operation, these are very difficult to figure out the in-situ characteristics of subgrade and subbase strength in detail. Therefore, for faster and economical operation, this study is to compare the Light Falling Weight Tests and propose the LFWD test as the in-situ Compaction test. This study suggests the relationship between in-situ RC value, $K_{30}$, $M_R$ and $E_{LFWD}$ of the subgrade and subbase materials in Korea using the laboratory and in-situ testing.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.46 no.5
• /
• pp.27-34
• /
• 2014

In-situ $CaCO_3$ formation onto recycled wood pulp was studied to improve optical properties and ash attachment to the fiber furnish in papermaking. We controlled initial reaction temperature of in-situ $CaCO_3$ formation method from $30^{\circ}C$ to $50^{\circ}C$. It was found that the attachment of newly formed $CaCO_3$ to recycled fibers, old newspaper (ONP) in this case, was stronger than that of ground calcium carbonate (GCC, mean dia. $2.4{\mu}m$) addition case, but was not much different among those formed at different temperature. Morphologies of newly formed $CaCO_3$ were changed according to the reaction temperature. More aragonite shape was seen at higher temperature. In-situ $CaCO_3$ formation increased brightness and lowered ERIC value of ONP sheet greatly at the same level of ash contents when compared to GCC addition method, but gave equivalent ERIC and brightness when compared to those of the precipitated calcium carbonate (PCC) addition method. However, tensile strength of the handsheets of the in-situ $CaCO_3$ formation method were much greater than those of the PCC addition method.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.9
• /
• pp.1515-1518
• /
• 2007

A preparative method of Me2SCuX (X = Cl, Br) via one-pot reaction was developed from common chemicals such as benzyl halide, DMSO, and Cu(0). In the reaction mixture small molecules such as methyl halide and dimethyl sulfide etc. were efficiently generated in situ, resulting in the formation of Me2SCuX. Oxidation of Cu(0) in reacting with both benzyl halide (starting material) and methyl halide (in situ generated product) to Cu(I) followed by complexing with dimethyl sulfide (in situ generated product) could explain the formation of Me2SCuX. In particular we found out that heterogeneous reaction of Me2SCuX and arenediazonium tetrafluoroborate in acetonitrile was so effective to afford corresponding bromoaromatics under mild conditions.