• Journal of the Korea Concrete Institute
• /
• v.27 no.2
• /
• pp.157-167
• /
• 2015

Cement composites subjected to high-velocity projectile shows local failure and it can be suppressed by improvement of flexural toughness with reinforcement of fiber. Therefore, researches on impact resistance performance of cement composites are in progress and a number of types of fiber reinforcement are being developed. Since bonding properties of fiber with matrix, specific surface area and numbers of fiber are different by fiber reinforcement type, mechanical properties of fiber reinforced cement composites and improvement of impact resistance performance need to be considered. In this study, improvement of flexural toughness and failure reduction effect by impact of high-velocity projectile have been evaluated according to fiber type by mixing steel fiber, polyamide, nylon and polyethylene which are have different shape and mechanical properties. As results, flexural toughness was improved by redistribution of stress and crack prevention with bridge effect of reinforced fibers, and scabbing by high-velocity impact was suppressed. Since it is possible to decrease scabbing limit thickness from impact energy, thickness can be thinner when it is applied to protection. Scabbing of steel fiber reinforced cement composites was occurred and it was observed that desquamation of partial fragment was suppressed by adhesion between fiber and matrix. Scabbing by high-velocity impact of synthetic fiber reinforced cement composites was decreased by microcrack, impact wave neutralization and energy dispersion with a large number of fibers.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1059-1061
• /
• 2005

The bushing currently applied to pole-mounted type loadbreak switch has porcelain bushing which is connected with the mold cone. This type has potential problems of uncertainty of sealing of the interface part and gas leakage on the connected part between bushing and switch tank due to the weight of the porcelain. The Composite Bushing can solve these problems and also the secondary problem of the potential accident owing to the fragment of the porcelain bushing in breakage due to the outer impact.

• The Korean Journal of Pesticide Science
• /
• v.2 no.3
• /
• pp.79-84
• /
• 1998

Tandem HPLC and atmospheric pressure chemical ionization(APcI) LC/MS method was used for the determination and confirmation of carbendazim residues in soybean sprout. Fluorescence(FL) detector was connected in tandem with the ultraviolet(UV) detector for dual detection of the carbendazim residue at the excitation and emission wavelength of 280 nm and 310 nm, respectively. The limit of detection for carbendazim was $0.1{\mu}g/kg$ sample. Recoveries of carbendazim from fortified soybean sprout at 0.5, 1.0 and 2.0 ppm were averaged 89.1%. Mass spectrometry using a APcI source confirmed the carbendazim residue in the soybean sprout sample. Fragmentation pattern on the APcI LC/MS spectrum of carbendazim was simpler than that from electron impact(EI) mass spectrum. Carbendazim produced 3 major ions including m/z 133, m/z 159 and m/z 191($M^{+}$). This method was sensitive enough to provide reliable and reproducible results for practical applications.

• Journal of the Korea Society for Simulation
• /
• v.29 no.1
• /
• pp.1-9
• /
• 2020

The ballistic missile threat continues to increase with the proliferation of missile technology. In response to this threat, many kinds of interceptors have been emphasized over the years. For development of interceptor, systematic flight tests are essential. Flight tests provide valuable data that can be used to verify performance and confirm the technological progress of ballistic missile defense system including interceptor. However, during flight tests, civilians near the test region could be risk due to a lot of intercept debris. For this reason, reliable estimate of safety area for the flight tests should be preceded. In this study, prediction of safety area is performed through modeling and simulation. Firstly, behaviors of ballistic missile and interceptor are simulated for those entire phase including interception to obtain the relative intercept velocity and the relative impact angle. By using obtained data of kinetic energy, the fragment ejection velocity is calculated and fragment trajectories are simulated by considering drag, gravity and wind effects. Based on the debris field formation and hazard evaluation of debris, final safety area is calculated.

• Journal of Fashion Business
• /
• v.15 no.2
• /
• pp.145-159
• /
• 2011

The study aimed to analyze the status quo of manufacturing work environment and the work clothes' clothing comfort and wearer mobility of welding and grinding work processes in the machine and shipbuilding industries in South Korea. A questionnaire survey was conducted for the study, which consisted of questions about work clothes' clothing comfort and wearer mobility according to body parts. The findings derived from the research were: the high impact levels of work environment factors on welding and grinding work processes were noise, metal fragment, superheat, toxic gas, UV ray factors. Subject workers' assessment of work clothes' clothing pressures were in the levels between 3 (i.e. moderate) and 4 (i.e. comfortable) in a range of 5-point scale. The impact levels of wearer mobility factor were high on the work processes of welding and grinding in machine and grinding in shipbuilding. While welding process in shipbuilding showed a 'moderate' wearer mobility level and this was because its work postures were uncomfortable yet the rate of the motion change was low. The consideration to develop the work clothes specialized for certain work processes should include the materials' protecting performance from the hazardous work environment factors; and work clothes' designs that provides workers with maximized clothing comfort and wearer mobility for bending or tilting postures of upper, lower and lateral body parts defined in the study.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.493-498
• /
• 2002

Friction stir welding (FSW) is a relatively new solid-state joining process which can homogenize the heterogeneous microstructure by intensely plastic deformation arising from the rotation of the welding tool. The present study applied the FSW to an A356 aluminum (AI) alloy with the as-cast heterogeneous microstructure in the T6 temper condition, and examined an effect of microstructure on mechanical properties in the weld. The base material consisted of Al matrix with a high density of strengthening precipitates, large eutectic silicon and a lot of porosities. The FSW led to fragment of the eutectic silicon, extinction of the porosities and dissolution of the strengthening precipitates in the Al alloy. The dissolution of strengthening precipitates reduced the hardness of the weld around the weld center and the transverse ultimate tensile strength of the weld. Longitudinal tensile specimen containing only the stir zone showed the roughly same strength as the base material and a much larger elongation. Moreover, Charpy impact tests indicated that the stir zone had remarkably the higher absorbed energy than the base material. The higher mechanical properties of the stir zone were attributed to a homogenization of the as-cast heterogeneous microstructure by FSW.

• Preventive Nutrition and Food Science
• /
• v.3 no.2
• /
• pp.111-118
• /
• 1998

To develop a simple, rapid and simultaneous analytical method of phenolic compounds using gas chromatography (GC) and gas chromatography/mass spectrophometer (GC/Ms), this experiment was carried out to search the retention times of capillary columns and the characteristics of fragment ions in electron impact mass spectra. Most of trimethylsilyl derivatives and underivatized phenolic compounds were separated very well on three kinds of capillary columns(HP-1), Ultra-2 and HP-35). Quantitiative determination of phenolic compounds was achieved by internal standards (p-hydroxybenzoic acid iopropyl ester, p-hydroxybenzoic acid ethyl ester). Calibration plts were linear in the investigated range, and the limits of detection were about 5 ng at split mode method. When analyzed by three columns, theseparation times were fairly constant on two nonpolar columns, but a few compounds showed slightly different separation order by the itnermediate polar HP-35 column. The important characteristic patterns of TMS derivatives of phenolic compounds on the EI/MS spectrra appeared at the base peak of [M-15]+ ion and presented at high abundance in most TMS derivatives of phenoloc compounds. [M]+, [M-CH3-COO]+, [M-Si(CH3)4]+ and [M-Si(CH3)4 -CH3]+ also observed in mass spectra of these compounds . Although several compounds have the same retention times on GC column, it might be possible to identify these compounds by the different patternsof mass frgement ions. The TMS derivatives, thus , provide additional information for identification of phenolic compounds in biological systems.

• Journal of Trauma and Injury
• /
• v.37 no.2
• /
• pp.161-165
• /
• 2024

Femoral head fractures with associated hip dislocations substantially impact the functional prognosis of the hip joint and present a surgical challenge. The surgeon must select a safe approach that enables osteosynthesis of the fracture while also preserving the vascularization of the femoral head. The optimal surgical approach for these injuries remains a topic of debate. A 44-year-old woman was involved in a road traffic accident, which resulted in a posterior iliac dislocation of the hip associated with a Pipkin type II fracture of the femoral head. Given the size of the detached fragment and the risk of incarceration preventing reduction, we opted against attempting external orthopedic reduction maneuvers. Instead, we chose to perform open reduction and internal fixation using the Watson-Jones anterolateral approach. This involved navigating between the retracted tensor fascia lata muscle, positioned medially, and the gluteus medius and minimus muscles, situated laterally. During radiological and clinical follow-up visits extending to postoperative month 15, the patient showed no signs of avascular necrosis of the femoral head, progression toward coxarthrosis, or heterotopic ossification. The Watson-Jones anterolateral approach is a straightforward intermuscular and internervous surgical procedure. This method provides excellent exposure of the femoral head, preserves its primary vascularization, allows for anterior dislocation, and facilitates the anatomical reduction and fixation of the fracture.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.1
• /
• pp.187-192
• /
• 2010

In order to monitor the possibility of horizontal gene transfer between transgenic rice and microorganisms in a paddy rice field, the gene flow from a bifunctional fusion (TPSP) rice containing trehalose-6-phosphate synthase and phosphatase to microorganisms in soils was investigated. The soil samples collected from the paddy rice field during June 2004 to March 2006 were investigated by multiplex PCR, Southern hybridization, and amplified fragment length polymorphism (AFLP). The TPSP gene from soil genomic DNAs was not detected by PCR. Soil genomic DNAs did not show homologies on the Southern blotting data, indicating that gene transfer did not occur during the last two years in the paddy rice field. In addition, the AFLP band patterns produced by soil genomic DNAs from both transgenic and non-transgenic rice fields appeared similar to each other when analyzed by the NTSYSpc program. Thus, these data suggest that transgenic rice does not give a significant impact on the communities of soil microorganisms, although long-term observation may be needed.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.6
• /
• pp.2949-2953
• /
• 2012

The glutathione S transferase (GST) family is a major part of cellular defense mechanisms against endogenous and exogenous substances, many of which have carcinogenic potential. Alteration in the expression level or structure of the glutathione-S-transferase (GST) enzymes may lead to inadequate detoxification of potential carcinogens and consequently contribute to cancer development. A member of the glutathione-S-transferase (GST) family, GSTP1, is an attractive candidate for involvement in susceptibility to carcinogen-associated colorectal cancer. An $Ag{\rightarrow}G$ transition in exon 5 resulting in an Ile105Val amino acid substitution has been identified which alters catalytic efficiency. The present study investigated the possible impact of Ile105Val GSTP1 polymorphism on susceptibility to colorectal cancer. in Jordan We examined 90 tissue samples previously diagnosed with colorectal carcinoma, and 56 non-cancerous colon tissues. DNA was extracted from paraffin embedded tissues and the status of the GSTP1 polymorphism was determined using a polymerase chain reaction restriction fragment length polymorphism (RFLP) method. No statistically significant differences were found between colorectal cancer cases and controls for the GSTP1 Ile/Ile, Ile/Val and Val/Val genotypes. The glutathione S-transferase polymorphism was not associated with risk in colorectal cancer cases in Jordan stratified by age, sex, site, grade or tumor stage. In conclusion, the GSTP1 Ile105Val polymorphism is unlikely to affect the risk of colorectal cancer.