• Nuclear Engineering and Technology
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• 제49권1호
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• pp.178-188
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• 2017

To study the effects of zirconium (Zr) addition on the microstructure, hardness and the tensile properties of oxide dispersion strengthened (ODS) ferritic-martensitic steels, two kinds of 9Cr-ODS ferritic-martensitic steels with nominal compositions (wt.%) of $Fe-9Cr-2W-0.3Y_2O_3$ and $Fe-9Cr-2W-0.3Zr-0.3Y_2O_3$ were fabricated by the mechanical alloying (MA) of premixed powders and then consolidated by hot isostatic pressing (HIP) techniques. The experimental results showed that the average grain size decreases with Zr addition. The trigonal ${\delta}$-phase $Y_4Zr_3O_{12}$ oxides and body-centered cubic $Y_2O_3$ oxides are formed in the 9Cr-Zr-ODS steel and 9Cr non-Zr ODS steel, respectively, and the average size of $Y_4Zr_3O_{12}$ particles is much smaller than that of $Y_2O_3$. The dispersion morphology of the oxide particles in 9Cr-Zr-ODS steel is significantly improved and the number density is $1.1{\times}10^{23}/m^3$ with Zr addition. The 9Cr-Zr-ODS steel shows much higher tensile ductility, ultimate tensile strength and Vickers hardness at the same time.

• 대한의생명과학회지
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• 제18권2호
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• pp.152-159
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• 2012

Campylobacter species are known to the high optimum growth temperature ($42^{\circ}C$) and the cause of enteritis in people. Erythromycin has a curative effect for enteritis caused by the bacteria. However, the rate of erythromycin-resistant bacteria was not well known until recently in Korea. Swine are one of sources of the infection with a Campylobacter species which cause the symptom of a high temperature. In this study, we cultured rectum fecal specimens of 100 pigs in an area of Buan-gun, Jeonbuk Province during July 2009. As a result, the detection rate of C. jejuni and C. coli and the rate of erythromycin-resistant bacteria for the separated Campylobacter species on the condition of high temperature were investigated. The possession or not of hipO and glyA gene and ciprofloxacin-resistant gene gyrA was also reviewed with biochemical characteristics and PCR.

• 한국임상약학회지
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• 제24권1호
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• pp.1-8
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• 2014

Objective: Currently, rivaroxaban is widely used clinically for thromboprophylaxis after surgery. However, there are concerns on effectiveness and safety of rivaroxaban for its proper use. We aimed to evaluate the effectiveness and safety of rivaroxaban in orthopaedic patients after total hip replacement surgery in a large medical centre after the preferred formulary was switched from enoxaparin to rivaroxaban. Methods: The study was conducted on the patients who underwent hip arthroplasty surgery at the department of Orthopaedic Surgery at Seoul St. Mary's Hospital, South Korea. Electronic medical records were retrospectively reviewed to identify patients treated with rivaroxaban following total hip replacement between February 2011 and March 2012. Evaluation criteria included indications for use, dose, initiation and duration of therapy, drug interactions, adverse reactions, and status of health care reimbursement. The patients who were on enoxaparin were also reviewed as a reference. Results: We identified 57 patients who received rivaroxaban and 50 who received enoxaparin. All patients were prescribed the drugs for Korean Food and Drug Administration-approved indications. No thromboembolic or bleeding events were observed in either group. However, only 5.3% of rivaroxaban- treated patients had an appropriate length of prophylaxis and only 3.5% began rivaroxaban treatment at the recommended time. Surprisingly, 47.4% of rivaroxaban-treated patients received rivaroxaban despite being ineligible for reimbursement benefits. Conclusion: Rivaroxaban was generally well tolerated clinically. However, the duration of treatment, the time of initiation and patient eligibility for reimbursement require improvements, emphasising the need for education which indicates the area of pharmacists' involvement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.17-19
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• 1988

$YBa_2Cu_3O_{7-x}$ oxide superconductors were fabricated by the hot isostatic pressing (HIP). It was shown that their structures were orthorombic and constited of a single (123) phase. While as-sintered compacts had many pores, they were remarkably reduced by Hiping. The on-set and off set temperature of (123) compound sintered at $950^{\circ}C$ in oxygen and hiping at $880^{\circ}C$ were the highest and it showed 0 resistance at $90^{\circ}K$. The critical current density ($J_c$) of the above superconductor was $27A/cm^2$ and it also showed a number of twin structures, which are typical of high $T_c$ superconductor. It seemed that the low current density may be due to the many pores of starting-sintered compacts.

• 한국세라믹학회지
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• 제25권2호
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• pp.131-135
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• 1988

The microstructural changes in partially stabilized MgO-ZrO2 alloys during heat treatment and mechanical properties of ZrO2(Y2O3)/Al2O3 systems have been studied. 9mol% MgO-ZrO2 powders were sintered at 1800$^{\circ}C$ for 4 hours and these specimens were aged at 1420$^{\circ}C$ and 1100$^{\circ}C$ secondly. These specimens have high thermal shock resistance and high toughness. The bend strength of Y-PSZ/Al2O3 composites conventially sintered were increased by HIP from 650MPa to 980MPa.

• 한국운동역학회지
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• 제21권1호
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• pp.1-7
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• 2011

The purpose of this study was to investigate changes in kinetic and kinematic variables associated with an increase in upper body weight. Eighteen healthy male university students($175.96{\pm}4.19\;cm$, $70.79{\pm}8.26\;kg$) participated. Eight motion analysis cameras(Qualysis Oqus 500) and 2 force AMTI platforms(Advanced Mechanical Technologies Inc. OR6-7, US) were used to record motion and forces during the drop landing at a frequency of 120 Hz and 1200 Hz, respectively. QTM software(Qualisys Track Manager) was used to record the data, and the variables were analyzed with Visual 3D and Matlab 2009. For the drop landing, a box of $4{\times}2{\times}0.46\;m$ was constructed from wood. Knee and ankle maximum flexion angle, knee flexion angle, knee and ankle angle at landing, time for maximum ankle flexion after landing, and time for maximum knee flexion after landing were calculated. There was a significant change in the time for maximum and minimum ground force reaction and the time for maximum dorsal flexion after landing(p<.05) with increasing weight. There was no significant change for the hip, knee, and ankle ROM, whereas there was an increase in the angle ROM as the weight increased, in the order of ankle, knee, and hip ROM. This result shows that the ankle joint ROM increased with increasing weight for shock attenuation during the drop landing. There was a trend for greater ankle ROM than knee ROM, but there was no clear change in the ROM of the hip joint with increasing weight. In conclusion, this study shows the importance of ankle joint flexibility and strength for safe drop landing.

• The Korean Journal of Physiology and Pharmacology
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• 제1권6호
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• pp.681-690
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• 1997

Loss of synaptic transmission and accumulation of extracellular $K^+([K^+]_O)$ are the key features in ischemic brain damage. Here, we examined the effects of several $K^+$channel modulators on the early ischemic changes in population spike (PS) and $[K^+]_o$ in the CA1 pyramidal layer of the rat hippocampal slice using electrophysiological techniques. After onset of anoxic aglycemia (AA), orthodromic field potentials decreased and disappeared in $3.3{\pm}0.22\;min$ $(mean{\pm}SEM,\;n=40)$. The hypoxic injury potential (HIP), a transient recovery of PS appeared at $6.0{\pm}0.25\;min$ (n=40) in most slices during AA and lasted for $3.3{\pm}0.43\;min$. $[K^+]_o$ increased initially at a rate of 0.43 mM/min (Phase 1) and later at a much faster rate (12.45 mM/min, Phase 2). The beginning of Phase 2 was invariably coincided with the disappearance of HIP. Among $K^+$ channel modulators tested such as 4-aminopyridine (0.03, 0.3 mM), tetraethylammonium (0.1 mM), NS1619 $(0.3{\sim}10\;{\mu}M)$, niflumic acid (0.1 mM), glibenclamide $(40\;{\mu}M)$, tolbutamide $(300\;{\mu}M)$ and pinacidil $(100\;{\mu}M)$, only 4-aminopyridine (0.3 mM) induced slight increase of $[K^+]_o$ during Phase 1. However, none of the above agents modulated the pattern of Phase 2 in $[K^+]_o$ in response to AA. Taken together, the experimental data suggest that 4-aminopyridine-sensitive $K^+$channels, large conductance $Ca^{2+}-activated$ $K^+$ channels and ATP-sensitive $K^+$ channels may not be the major contributors to the sudden increase of $[K^+]_o$ during the early stage of brain ischemia, suggesting the presence of other routes of $K^+$ efflux during brain ischemia.

• Tribology and Lubricants
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• 제21권5호
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• pp.216-220
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• 2005

The sliding wear behaviors of three different compositions of novel low temperature degradation-free zirconia/alumina (LTD-free Z/A) composites were examined in a ceramic-ceramic contact pair. The wear tests were performed by using a pin-on-disk type wear tester in a linear reciprocal sliding motion with a line contact in both dry and bovine serum lubricated conditions at room temperature. From the results of dry sliding wear tests, Z/A#1((5.3Y, 4.6Nb)-TZP/80 $vol\%Al_2O_3$) showed the best wear resistance among three kinds of LTD-free Z/A composites. For the bovine serum lubricated sliding wear tests, wear was too little to be measured for all kinds of Z/A composites. These novel LTD-free Z/A composites having excellent wear resistance demonstrated a potential as the alternative materials for the ceramic-ceramic contact pairs of femoral head and acetabular liner in total hip replacement.

• 한국주조공학회지
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• 제27권3호
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• pp.135-139
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• 2007

To produce higher quality of titanium casting at a lower cost, the new titanium casting technology by using a permanent metal mold was developed and applied to fabricate hip joint for biomedical application. The present study was carried out to investigate the reactivity and fluidity of the Ti-6.0 wt%Al-4.0 wt%V alloy with metal mold by applying various ceramic powders coating on the mold surface. The molten titanium for manufacturing hip joint was poured into steel mold. No reaction layer was formed on the surface of specimens fabricated steel mold coated with $Y_2O_3$ powder.

• 대한족부족관절학회지
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• 제22권1호
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• pp.8-15
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• 2018

Ankle osteoarthritis is a debilitating condition that causes severe pain associated with functional impairment and decreased activity. Ankle osteoarthritis, unlike that of the knee or hip joint, is rare in primary arthritis. Most cases are traumatic arthritis that occur after ankle sprain or fractures or chronic ankle instability. Although ankle fusion has been regarded as the standard treatment of ankle osteoarthritis in the past, total ankle arthroplasty (TAA) is increasing due to the development of the implant design and surgical techniques. TAA is biomechanically superior to ankle fusion by preserving the movement of the ankle joint. In particular, it is functionally superior to ankle fusion because it enables normal joint motion during gait. In addition, there is an advantage of preserving the movement of the hindfoot and reducing the abnormal stress applied to the adjacent joints after ankle fusion to prevent the occurrence of long-term adjacent joint arthritis. Although the short-term and mid-term results of TAA have been reported to be excellent, long-term follow-up has a relatively low survival rate and high complication rate compared to total knee or hip arthroplasty. Therefore, continuous and further research is needed.