• Journal of Ocean Engineering and Technology
• /
• v.11 no.4
• /
• pp.221-226
• /
• 1997

This study was carried out for the hull form development of G/T 340ton class high speed fishery patrol ship by Chosun University at the Circulating Water Channel cooperatively with Korea Maritime Service. Same size of 15knots class fishery patrol ship was selected as a parent form (Model number : CU-015), and modified fore and after body to be suitable for the operation at 20 knots. To minimize the breaking wave in the vicinity of fore body at high speed zone, high bulb nose and slender fore body hull form was chosen as an initial condition. Meanwhile, to ensure the engine room space keeping high resistance-propulsion performance, U-type stern hull form was developed.

• Journal of Environmental Health Sciences
• /
• v.38 no.4
• /
• pp.323-331
• /
• 2012

Objectives: The objective of this study was to investigate the possible effects of environmental cadmium (Cd) exposure on of bone mineral density (BMD) levels. Methods: A total of 171 residents around abandoned mines in Chungcheongnam-do were surveyed in 2008-2011. Urinary Cd and BMD were analyzed by atomic absorption spectrometry and Dual-Energy X-ray absorptionmetry, respectively. Osteoporosis and osteopenia were defined by T-scores set by the WHO; Tscore ${\geq}$ -1.0, normal; -1.0 > T-score > -2.5, osteopenia; and T-score ${\leq}$ -2.5, osteoporosis. Logistic and multiple linear regressions were applied to estimate the association between U-Cd levels and BMD. Results: The U-Cd geometric mean of 171 Koreans was 2.79 ${\mu}g/g{\cdot}cr$. The U-Cd concentration was significantly higher among women (2.98 ${\mu}g/g{\cdot}cr$) than men (2.39 ${\mu}g/g{\cdot}cr$). With the multiple regression model, the BMD was influenced by U-Cd, BMI, and monthly income. With the logistic regression model, osteoporosis was associated with U-Cd levels (OR = 3.239, 95% CI = 1.770-5.927). Conclusions: We conclude that exposure to cadmium is associated with an increased risk of osteoporosis.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.3
• /
• pp.429-432
• /
• 2015

Radio Frequency (RF) coils in Magnetic Resonance Imaging (MRI) systems interact with a patient's tissues, resulting in the absorption of RF energy by the tissues. The presence of an electrically conducting medical implant may concentrate the RF energy and causes tissue heating near the implant devices. Here we present a novel design for a medical lead to reduce this undesired heating. Specific Absorption Rate (SAR), an indicator of heating, was calculated. Remcom XFdtd software was used to calculate the peak SAR distribution (1g and 10 g) in a realistic model of the human body. The model contained a medical lead that was exposed to RF magnetic fields at 64 MHz (1.5 T MRI), 128 MHz (3 T MRI) and 300 MHz (7 T MRI) using a model of an MR birdcage body coil. Our results demonstrate that, our proposed design of adding nails to the medical lead can significantly reduce the SAR for different MRI systems.

• Tuberculosis and Respiratory Diseases
• /
• v.50 no.1
• /
• pp.12-28
• /
• 2001

Background and Object : Immunostimulatory CpG-oligodeoxynucleotides (ISS CpG-ODN) up-regulate the $T_{H1}$-type immune response and down-regulate the $T_{H2}$-type response. This study was performed to investigate the immune response changes resulting from ISS CpG-ODN on bronchial hyperresponsiveness, eosinophilic inflammation and mucus hypersecretion in rat asthma. Materials and Methods : 10 normal controls(NC) and 26 asthmatic rats, which were generated by ovalbumin(OVA) sensitization and challenge, were studied. The asthmatic rats were randomized into 11 asthma controls(AC) and 15 in the asthma-CpG treatment group(CpG). The CpG group was administered ISS CpG-ODN intramuscularly and the AC group was administered a placebo(0.9% NaCl) on day 15 and 20. After CpG-ODN or placebo administration, we measured the IFN-${\gamma}$($T_{H1}$-type cytokine) and IL-4($T_{H2}$-type cytokine) levels in the bronchoalveolar lavage fluid(BALF), the specific airway resistance(sRaw), eosinophilic fraction in BALF, eosinophilic infiltration, goblet cell dysplasia and MUC5AC gene expression in the lung tissue. Results : In the BALF of the CpG group, the IFN-${\gamma}$ concentration was significantly high and the IL-4 concentration was significantly low when compared with the AC group. Both the sRaw and eosinophilic fraction, and infiltration into the BALF and lung tissue significantly lower in the CpG group when compared with the AC group. However, little difference in goblet cell dysplasia and MUC5AC gene expression was observed between the CpG group and the AC group. Conclusion : ISS CpG-ODN decreases bronchial hyperresponsiveness and eosinophilic inflammation in the rat asthma model through the up-regulation of the $T_{H1}$-type immune response with the down-regulation of the $T_{H2}$-type response. However, the effect of these immune response changes on mucus hypersecretion was is not remarkable in this study.

• Proceedings of the Korean Magnestics Society Conference
• /
• 1996.10a
• /
• pp.116-117
• /
• 1996

• Steel and Composite Structures
• /
• v.32 no.2
• /
• pp.199-212
• /
• 2019

This paper presents an investigation on seismic behavior of out-of-code Q690 circular high-strength concrete-filled thin-walled steel tubular (HCFTST) columns made up of high-strength (HS) steel tubes (yield strength $f_y{\geq}690MPa$). Eight Q690 circular HCFTST columns with various diameter-to-thickness (D/t) ratios, concrete cylinder compressive strengths ($f_c$) and axial compression ratios (n) were tested under the constant axial loading and reversed cyclic lateral loading. The obtained lateral load-displacement hysteretic curves, energy dissipation, skeleton curves and ductility, and stiffness degradation were analyzed in detail to reflect the influences of tested parameters. Subsequently, a simplified shear strength model was derived and validated by the test results. Finally, a finite element analysis (FEA) model incorporating a stress triaxiality dependent fracture criterion was established to simulate the seismic behavior. The systematic investigation indicates the following: compared to the D/t ratio and axial compression ratio, improving the concrete compressive strength (e.g., the HS thin-walled steel tube filled with HS concrete) had a slight influence on the ductility but an obvious enhancement of energy dissipation and peak load; the simplified shear strength model based on truss mechanism accurately predicted the shear-resisting capacity; and the established FEA model incorporating steel fracture criterion simulated well the seismic behavior (e.g., hysteretic curve, local buckling and fracture), which can be applied to the seismic analysis and design of Q690 circular HCFTST columns.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.6
• /
• pp.521-529
• /
• 2014

In this study, numerical simulations and model tests are performed for the hull-form development of a G/T 29ton class coastal angling fishing boat. The numerical simulations are mainly used for the design of bow hull-form and the resistance performance is improved by the adoption of high bulbous bow. And, the resistance performances of the existing boat and the designed boat are verified by the model tests. The results of the experiments and calculations show that the effective power of the designed boat is 13.6% less than that of the existing boat at design speed. Therefore, the results of this research could be used as one of the fundamental data for the design of G/T 29ton class coastal angling fishing boat.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.49 no.4
• /
• pp.1-6
• /
• 2012

This paper presents the extraction and analysis of small-signal parameters of tunneling field-effect transistors (TFETs) by using TCAD device simulation. The channel lengths ($L_G$) of the simulated devices varies from 50 nm to 100 nm. The parameter extraction for TFETs have been performed by quasi-static small-signal model of conventional MOSFETs. The small-signal parameters of TFETs with different channel lengths were extracted according to gate bias voltage. The $L_G$-dependency of the effective gate resistance, transconductance, source-drain conductance, and gate capacitance are different with those of conventional MOSFET. The $f_T$ of TFETs is inverely proportional not to $L_G{^2}$ but to $L_G$.

• Journal of the Korean Chemical Society
• /
• v.21 no.1
• /
• pp.23-31
• /
• 1977

For the metal complex of $d^1$ configuration with the octahedrally coordinated ligands, the crystal field parameter, 10Dq, is calculated from first principles within the framework of the crystal field theory. With the point charge model, the configuration interaction is introduced by use of the Shull-L$\"{o}$wdin functions. Through the Integral Hellmann-Feynman Theorem, the higher order effect is visualized. It is found that the higher order effect on 10Dq is about $50{\%}$ of the first order effect. Since 3d function is angularly undistorted and radially equally distorted in $E_g\;and\;T_{2g}$ states, due to the octahedral potential, the calculated 10Dq is still the unique parameter for the splitting.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.10a
• /
• pp.98-107
• /
• 2004

The objectives of this research are to establish the criteria of peel occurrence considering the shape of bond terminus and to compare the strength properties of some adhesive joints. The criteria of feel occurrence at the bond terminus was suggested. Peel loads of some adhesive joint(butt joint, T -shape specimen, single lap joint) were determined from tensile tests. Principal stress distributions of these joints were determined from finite element method analysis. Then, peel occurrence was estimated with intensity of stress singularity ' $K_{prin.}$' when the terminus shape was square, with average principal stress when the terminus shape was rounded. The conclusions are summarized as follows; (1) In the non-filleted model(e.g., butt joint, T-shape specimen), principal stress shows singularity at the bond terminus, intensity of stress(principal stress) singularity ' $K_{prin.}$&apso; can use as the criteria of peel occurrence at the bond terminus. (2) In the filleted model(e.g., single lap joint), principal stress doesn't show singularity at the bond terminus. Average principal stress can use as the criteria of peel occurrence at the bond terminus.'t show singularity at the bond terminus. Average principal stress can use as the criteria of peel occurrence at the bond terminus.