• Journal of Powder Materials
• /
• v.27 no.2
• /
• pp.126-131
• /
• 2020

The grain growth behavior of M-type Sr hexaferrite (SrM) grains is investigated with the addition of MnCO₃. First, the SrM powder is synthesized by a conventional solid-state reaction. The powder compacts of SrM are sintered at 1250℃ for 2 h with various amounts of MnCO₃ (0, 0.5, 1.0, and 4.0 mol%). There is no secondary solid phase in any of the sintered samples. Relative density increases when MnCO₃ is added to the SrM. Obvious abnormal grain growth does not appear in any of the SrM samples with MnCO₃. The average grain size increases when 0.5 mol% MnCO₃ is added to the SrM. However, as the amount of MnCO₃ increase to over 0.5 mol%, the average grain size decreases. These observations allow us to conclude that the growth of SrM grains is governed by the two-dimensional nucleation grain growth mechanism, and the critical driving force for the growth of a grain decreases as the amount of MnCO₃ increases.

• Korean Journal of Crystallography
• /
• v.7 no.2
• /
• pp.147-155
• /
• 1996

Floating Zone Image furnace with halogen lamps as heat source has been made and applied to the growth of high-Tc superconductor Bi2Sr2CaCu2O8. The manufactured crystal growth equipment is composed of holder unit for setting the halogen lamps at the focal point of the elliptical mirror, image furnace with maximum temperature of 1800℃ with 1kW halogen lamps, cooling unit, feeding unit for supplying source material to the molten zone, pulling unit for crystal growth, and the control unit in the range of 2mm/hr -40 mm/hr vertical movement and 15rpm - 12rpm rotation. Bi2Sr2CaCu2O8 fibers have been grown with 300W halogen lamps and characterized with XRD, SEM and EDS. The growth condition was air atmosphere, growth speed 3∼4mm/hr, rotation speed of upper and lower part 20∼25 rpm. The fiber was composed of 20∼25 rpm matrix phase and secondary phases such as (Sr,Ca)CuO2 and (Sr,Ca)2CuO3.

• Nuclear Engineering and Technology
• /
• v.25 no.1
• /
• pp.37-50
• /
• 1993

To evaluate the sequence of event and the Thermohydraulic behavior during total loss of feedwater accident and recovery procedure, a RELAP5/MOD3 calculation is performed and compared with the LOFT L9-l/L3-3 experiment. Also, the predictability of the code for the major Thermohydraulic phenomena following the accident is assessed. As a result, it is found that a pressure control using the spray until the time the water level reaches the top of the pressurizer, an overpressure protection by pressurizer PORV, a recovery of the secondary heat removal capability by refilling steam generator, and an effective cooldown by the continued natural circulation can be performed without core uncovery. It is also found that the plant-specific evaluation is necessary to confirm the effectiveness of the current symptom-oriented emergency operating procedure, especially in an overpressure protection performance and steam generator recovery performance.

• Korean Journal of Applied Biomechanics
• /
• v.24 no.4
• /
• pp.375-383
• /
• 2014

The purpose of this study was to assess the inter-segmental trunk motion during which multi-segmental movements of the spinal column was designed to interpret the effect of segmentation on the total measured spine motion. Also it analyzed the relative motion at three types of the spine models in drop landing. A secondary goal was to determine the intrinsic algorithmic errors of spine motion and the usefulness of such an approach as a tool to assess spinal motions. College students in the soccer team were selected the ten males with no history of spine symptoms or injuries. Each subject was given a fifteen minute adaptation period of drop landing on the 30cm height box. Inter-segmental spine motion were collected Vicon Motion Capture System (250 Hz) and synchronized with GRF data (1000 Hz). The result shows that Model III has a more increased range of motion (ROM) than Model I and Model II. And the Lagrange energy has significant difference of at E3 and E4 (p<.05). This study can be concluded that there are differences in the three models of algorithm during the phase of load absorption. Especially, Model III shows proper spine motion for the inter-segmental joint motion with the interaction effects using the seven segments. Model III shows more proper observed values about dynamic equilibrium than Model I & Model II. The findings have shown that the dynamic stability strategy of Model III toward multi-directional spinal motion supports for better function of the inter-segmental motor-control than the Model I and Model II.

• Nuclear Engineering and Technology
• /
• v.37 no.4
• /
• pp.375-384
• /
• 2005

To investigate the flow-accelerated corrosion (FAC) dependency of carbon steel (A106 Gr. B) and low-alloy steels (1Cr-1/2Mo, 21/4Cr-1Mo) on pH, orifice distance, and material, experiments were carried out. These experiments were performed using a flow velocity of 4 m/sec (partly 9 m/sec) at pH $8.0\~10.0$ in an oxygen-free aqueous solution re-circulated in an Erosion-Corrosion Test Loop at $130^{\circ}\;{\ldots}$ for 500 hours. The weight loss of the carbon steel specimens appeared to be positively dependent on the flow velocity. That of the carbon and low-alloy steel specimens also showed to be distinguishably dependent on the pH. At pH levels of $8.0\~9.5$ it decreased, but increased from 9.5 to 10.0. Utility water chemistry personnel should carefully consider this kind of pH dependency to control the water system pH to mitigate FAC of the piping system material. The weight loss of the specimens located further from the orifice in the distance range of $6.8\~27.2$ mm was shown to be greater, except for 21/4Cr-1Mo, which showed no orifice distance dependency. Low alloy steel specimens exhibited a factor of two times better resistance to FAC than that of the carbon steel. Based on this kind of FAC dependency of the carbon and low-alloy steels on the orifice distance and material, we conclude that it is necessary to alternate the composition of the secondary piping system material of NPPs, using low-alloy steels, such as 21/4Cr-1Mo, particularly when the system piping has to be replaced.

• Tuberculosis and Respiratory Diseases
• /
• v.82 no.3
• /
• pp.211-216
• /
• 2019

Background: Docetaxel is one of the standard treatments for advanced non-small cell lung cancer. Docetaxel is usually administered in a 3-week schedule, but there is significant toxicity. In this phase II clinical study, we investigated the efficacy and safety of a 4-weekly schedule of docetaxel monotherapy, as first-line chemotherapy for advanced squamous cell carcinoma in elderly lung cancer patients. Methods: Patients with stage IIIB/ IV lung squamous-cell carcinoma age 70 or older, that had not undergone cytotoxic chemotherapy were enrolled. Patients received docetaxel $25mg/m^2$ on days 1, 8, and 15, every 4 weeks. Primary endpoint was the objective response rate (ORR). Secondary endpoints were progression-free survival (PFS), overall survival (OS), and toxicity profiles. Results: A total of 19 patients were enrolled. Among 19 patients, 17 were for evaluated efficacy and safety. In the intent-to-treat population, ORR and disease control rate (DCR) were 11.8% and 47.1%, respectively. In the response evaluable population, ORR was 16.7% and DCR was 66.7%. Median PFS and OS were 3.1 months and 3.3 months, respectively. There were three adverse grade 3/4 events. Grade 1 neutropenia was reported in one patient. Conclusion: Our data failed to demonstrate efficacy of a 4-weekly docetaxel regimen, in elderly patients with a poor performance status. However, incidence of side effects, including neutropenia, was lower than with a 3-week docetaxel regimen, as previously reported.

• Journal of the Korean Physical Society
• /
• v.73 no.11
• /
• pp.1703-1707
• /
• 2018

Ferromagnetic ${\tau}-phase$ $Mn_{54}Al_{46}C_{2.44}$ particles were synthesized, and its composites with commercial $Sm_2Fe_{17}N_3$ and synthesized $Fe_{65}Co_{35}$ powders were fabricated. Smaller grain size than the single domain size of the $Mn_{54}Al_{46}C_{2.44}$ without obvious grain boundaries and secondary phases is the origin for the low intrinsic coercivity. It was confirmed that the magnetic properties of the $Mn_{54}Al_{46}C_{2.44}$ can be enhanced by magnetic exchange coupling with the hard magnetic $Sm_2Fe_{17}N_3$ and soft magnetic $Fe_{65}Co_{35}$. The high degrees of the exchange coupling were verified by calculating first derivative curves. Thermo-magnetic stabilities of the composites from 100 to 400 K were measured and compared. It was demonstrated that the $Mn_{54}Al_{46}C_{2.44}$ based composites containing $Sm_2Fe_{17}N_3$ and $Fe_{65}Co_{35}$ could be promising candidates for future permanent magnetic materials with the proper control of purity, magnetic properties, etc.

• The Journal of Pediatrics of Korean Medicine
• /
• v.37 no.3
• /
• pp.75-93
• /
• 2023

Objectives We aimed to analyze the registration status of interventional clinical trials in children and adolescents with chronic cough. Methods All interventional clinical trials registered up to 3 July, 2023 on the international clinical trial registry platform (ICTRP) of the World Health Organization (WHO) were analyzed. Information was extracted including study design, interventions, inclusion and exclusion criteria, and outcome indicators. Results A total of 18 interventional clinical trials were analyzed. For study design, multicentre trials, randomized allocation, parallel group design and phase 4 trials were the most frequently reported. Blinding was used in 44.4% and informed consents were obtained from 61.1%. For intervention, drugs were used in 61.1%, using placebo control group in 27.8%. Quality of life questionnaires were most frequently reported in 50% as the primary outcome, and adverse events were the most as the secondary outcome. In most cases, the assessment timepoints were after two weeks. Conclusions Based on the characteristics of clinical trial design analyzed in this study, it is necessary to design traditional Korean medicine clinical trials with improved quality and accuracy of information.

• Korean Chemical Engineering Research
• /
• v.43 no.4
• /
• pp.495-502
• /
• 2005

Copper was plated on the tungsten substrate by use of a direct copper electroless plating. The optimum deposition conditions were found to be with a concentration of $CuSO_4$ 7.615 g/L, EDTA of 10.258 g/L, and glyoxylic acid of 7 g/L, respectively. The solution temperature was maintained at $60^{\circ}C$. The pH was varied from 11.0 to 12.8. After the deposition, the properties of the copper film were investigated with X-ray diffractometer (XRD), Field emission secondary electron microscope (FESEM), Atomic force microscope (AFM), X-ray photoelectron spectroscope (XPS), and Rutherford backscattering spectroscope (RBS). The best deposition condition was founded to be the solution pH of 11.8. In the case of 10 min deposition at the pH of 11.8, the grain shape was spherical, Cu phase was pure without impurity peak ($Cu_2O$ peak), and the surface root mean square roughness was about 11 nm. The thickness of the film turned out to be 140 nm after deposition for 12 min and the deposition rate was found to be about 12 nm/min. Increase in pH induced a formation of $Cu_2O$ phase with a long rectangular grain shape. The pH control seems to play an important role for the orientation of Cu in electroless deposition. The deposited copper concentration was 99 atomic percent according to RBS. The resulting Cu/W film yielded a good adhesive strength, because Cu/W alloy forms during electroless deposition.

• Asian-Australasian Journal of Animal Sciences
• /
• v.31 no.5
• /
• pp.650-657
• /
• 2018

Objective: The study investigated the biological functions and mechanisms for controlling cashmere growth of Liaoning cashmere goat by ovarian carcinoma immunoreactive antigen-like protein 2 (OCIAD2) and decorin (DCN) genes. Methods: cDNA library of Liaoning cashmere goat was constructed in early stages. OCIAD2 and DCN genes related to cashmere growth were identified by homology analysis comparison. The expression location of OCIAD2 and DCN genes in primary and secondary hair follicles (SF) was performed using in situ hybridization. The expression of OCIAD2 and DCN genes in primary and SF was performed using real-time polymerase chain reaction (PCR). Results: In situ hybridization revealed that OCIAD2 and DCN were expressed in the inner root sheath of Liaoning cashmere goat hair follicles. Real-time quantitative PCR showed that these genes were highly expressed in SF during anagen, while these genes were highly expressed in primary hair follicle in catagen phase. Melatonin (MT) inhibited the expression of OCIAD2 and promoted the expression of DCN. Insulin-like growth factors-1 (IGF-1) inhibited the expression of OCIAD2 and DCN, while fibroblast growth factors 5 (FGF5) promoted the expression of these genes. MT and IGF-1 promoted OCIAD2 synergistically, while MT and FGF5 inhibited the genes simultaneously. MT+IGF-1/MT+FGF5 inhibited DCN gene. RNAi technology showed that OCIAD2 expression was promoted, while that of DCN was inhibited. Conclusion: Activation of bone morphogenetic protein (BMP) signaling pathway up-regulated OCIAD2 expression and stimulated SF to control cell proliferation. DCN gene affected hair follicle morphogenesis and periodic changes by promoting transforming growth $factor-{\beta}$ ($TGF-{\beta}$) and BMP signaling pathways. OCIAD2 and DCN genes have opposite effects on $TGF-{\beta}$ signaling pathway and inhibit each other to affect the hair growth.