• Journal of Korea Foundry Society
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• v.26 no.1
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• pp.17-26
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• 2006

The substitution of cooling method from water quenching to air cooling after solution heat treatment was aimed for the development of a convenient and economical heat treatment process of duplex stainless steels without deterioration of mechanical and corrosion resistant properties for the industry. In order to achieve this goal, the mechanical properties and corrosion properties of a ASTM A890-4A duplex stainless steel were systematically investigated as functions of casting condition and cooling method after solution heat treatment. A 3-stepped sand mold and a permanent Y-block mold were used to check the effects of solidification structure and cooling rate after solution heat treatment. The microstructural characteristics such as the ferrite/austenite phase ratio and the precipitation behavior of ${\sigma}$ phase and carbides were investigated by combined analysis of OM and SEM-EDX with an aid of TTT diagram. Hardness and tension test were performed to evaluate the mechanical properties. Impact property at $-40^{\circ}C$ and corrosion resistance were also examined to check the possibility of the industrial application of this basic study. Throughout this investigation, air-cooling method was proved to effectively substitute for water-quenching process after the solution heat treatment, when the duplex stainless steel was sand mold cast with a thickness below 15 mm or permanent mold cast with a thickness below 20 mm.

• Clinical and Experimental Pediatrics
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• v.62 no.3
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• pp.85-89
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• 2019

Purpose: We compared thyroid hormone profiles in children with nephrotic syndrome (NS) during the nephrotic phase and after remission. Methods: This study included 31 pediatric NS patients. The thyroid hormone profiles included serum levels of triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), and free T4. Results: Of the 31 patients, 16 (51.6%) showed abnormal thyroid hormone profiles: 6 had overt hypothyroidism, 8 had subclinical hypothyroidism, and 2 had low T3 syndrome. The mean serum T3, T4, and free T4 levels in the nephrotic phase and after remission were $82.37{\pm}23.64$ and $117.88{\pm}29.49ng/dL$, $5.47{\pm}1.14$ and $7.91{\pm}1.56{\mu}g/dL$, and $1.02{\pm}0.26$ and $1.38{\pm}0.23ng/dL$, respectively; the levels were significantly lower in the NS nephrotic phase (P=0.0007, P<0.0001, and P=0.0002). The mean serum TSH levels during the nephrotic phase and after remission were $8.05{\pm}3.53$ and $4.08{\pm}2.05{\mu}IU/mL$, respectively; they were significantly higher in the nephrotic phase (P=0.0005). The urinary protein/creatinine ratio during the nephrotic phase was significantly correlated with serum T3, T4, and free T4 levels (r=-0.5995, P=0.0032; r=-0.5797, P=0.0047; r=-0.5513, P=0.0078) as well as with TSH levels (r=0.5022, P=0.0172). A significant correlation was found between serum albumin and serum T3 levels during the nephrotic phase (r=0.5385, P=0.0018) but not between serum albumin and T4, TSH, or free T4 levels. These significant correlations all disappeared after remission. Conclusion: Abnormal thyroid hormone profile findings were observed in 51.6% of pediatric patients with NS. Thyroid hormone levels normalized after remission, regardless of levothyroxine therapy.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.1
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• pp.26-32
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• 2008

Effects of annealing treatment on microstructure and mechanical property of co-sputtered TiNi thin films were studied. As-deposited films showed amorphous state. However, above annealing temperature of $500^{\circ}C$ martensite phase (B19'), precipitate phase ($Ti_2Ni$) and a small amount of parent phase ($B_2$) were present, and phase transformation behaviors were three multi-step phase transformations $B19^{\prime}{\rightarrow}B_2$ and $B_2{\rightarrow}R-phase$ and $R-phase{\rightarrow}B19^{\prime}$. Increase of martensite transformation temperature, increase of microhardness and Young's modulus of TiNi films annealed above $500^{\circ}C$ were discussed in terms of precipitate phase.

• Natural Product Sciences
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• v.26 no.3
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• pp.236-243
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• 2020

Salvia plebeia R. Br. is a plant which has been used as an edible crop and traditional medicine in Asian countries. In this study, HPLC-PDA analysis and countercurrent chromatography (CCC) coupled with reversed-phase (RP) HPLC method were applied to isolate ten isolates from 3.3 g of n-butanol soluble extract from hot-water extract of S. plebeia. The use of CCC enabled us to efficiently fractionate the starting material with less sample loss and facilitate the isolation of compounds from S. plebeia extract using RP-HPLC. The isolates were determined to be caffeic acid (1), 6-hydroxyluteolin 7-O-β-D-glucoside (2), eudebeiolide B (3), (R)-rosmarinic acid (4), homoplantaginin (5), eudebeiolide D (6), plebeiolide C (7), salpleflavone (8), eupafolin (9) and hispidulin (10) based on the spectroscopic evidence.

• Journal of IKEEE
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• v.26 no.4
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• pp.560-567
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• 2022

This paper proposed an application of agile management method to resolve the electrical system issues identified during the mass production phase of aged aircraft performance improvement. The proposed method was applied from issue analysis to on-site verification and testing stage, before the formal configuration control process. At this time, the project was carried out by setting a sprint period to complete the verification according to requirements through daily scrum and sprint review. As a result, It was verified that the wiring installation of the aircraft, which was the output of the sprint, met requirements within the defined sprint period.

• Korean Management Science Review
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• v.26 no.3
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• pp.101-115
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• 2009

In this paper, we propose a technology mining framework for mobile communication industry. We develop a two phase approach of new technology identification and service enhancement. The new technology identification process consists of R&D issues analysis, technology theme design, and emerging technology sampling. On the other hand, existing service enhancement process has technology landscaping, keyword based search, and technological growth analysis. By implementing these two phase frameworks, we develop a technology portfolio for mobile communication industry.

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.61-65
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• 2012

Air-water flow measurements are of importance for the coastal and ocean engineering fields. Although kinematic investigations of the multi-phase flows have been conducted for long time, velocity measurements still are concerned with many researchers and engineers in coastal and ocean areas. In the present study, an imaging technique using shadowgraphy and fiber optic probe for velocity measurements of air bubbles is introduced. The shadow graphy image technique is modified from the typical image velocimetry methods, and optical fibers are used for the well-known intrusive coupled phase-detection probe system. Since the imaging technique is a non-intrusive optical method from the air, it is usually applied for 2D flows. On the other hand, the double fiber optic probes touch flows regardless of flow patterns. The results of the flow measurements by both methods are compared and discussed. The methods are also applied to the measurements of overtopping flows by a breaking wave over the structure fixed on the free surface.

• Journal of Species Research
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• v.13 no.1
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• pp.100-104
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• 2024

The purpose of this study was to isolate and identify wild yeasts from soil samples collected in Daegu and Cheongju city, Republic of Korea. To identify the wild yeast strains, pairwise sequence comparisons of D1/D2 region of the 26S rRNA gene sequence were done using Basic Local Alignment Search Tool (BLAST). The cell morphologies were observed by phase contrast microscope and assimilation test are done using API 20C AUX kit. All strains were assigned to the phylum Basidiomycota. Among 13 strains, 11 strains were previously reported, but two strains were unreported from the Republic of Korea. The two unrecorded yeast strains, GW1-3 and PG1-1-10C, belong to the genus Solicoccozyma (family Piskurozymaceae, order Filobasidiales, class Tremellomycetes). The two strains had oval-shaped and polar budding cells. This research showed the morphological and biochemical properties of the two unreported yeast species that had not officially reported in Korea.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.12-19
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• 2022

Propellant grains with embedded metal wires have been used for enhancement of burning rate while maintaining high loading density. For the performance design of a solid rocket motor using propellant grain with embedded metal wires, burn-back analysis is required according to number, location, arrangement angle of metal wires, and augmentation ratio of the propellant burning rate near a wire region. In this study, a numerical method to quickly calculate a burning surface area was developed in response to the design change of the propellant grain with embedded metal wires. The burning surface area derived from the developed method was compared with the results of a CAD program. Error rate decreased as the radial size of the grid decreased. Analysis for characteristics of burning surface area was performed according to the number and location of metal wires, the initial and final phases were shortened and the steady-state phase was increased when the number of metal wires increased. When arranging the metal wires at different radii, the burning surface area rapidly increased in the initial phase and sharply decreased in the final phase compared to the case where the metal wires were disposed in the same radius.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.6
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• pp.243-251
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• 2016

Silanized-hydroxypropyl methylcellulose (Si-HPMC)/phase transformed calcium phosphate (PTCP) composites are prepared to purpose application of injectable bone cements with enhanced biocompatibility. The crystal structure and chemical state of the synthesized PTCP and Si-HPMC as solid and liquid phase of the composite cements were measured by XRD and FT-IR. The handling and mechanical properties of cements were measured by injectability tests and three-point bending tests. The in-vitro mechanical properties, XRD, and SEM results of bone cements were showed that enhanced hardening behavior was an inherent function of bone cements after in-vitro test. The cytotoxicity result of bone cements also was showed enhanced biocompatibility. Therefore, these injectable cements had potential be used as calcium phosphate cements for biomedical applications.