• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.3
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• pp.265-270
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• 2004

Experiment study on a down scaled two-phase catalytic reactor is presented. As a preliminary step for the development of catalytic reactor, nano-particulate catalyst was prepared. Perovskite La$\_$0.8/Sr$\_$0.2/CoO$_3$is chosen and synthesized as a catalyst considering superior catalytic performance in reduction and oxidation process where oxygen is involved among the reagent. Reactor that has a scale of 2${\times}$10${\times}$25mm was made by machining of A1 block as a layered structure considering further extension to micro-machining. Hydrogen peroxide of 70wt% was adopted as reactant and was provided to the reactor loaded with 1.5 g of catalyst. Reactant flow rate was varied by precision pump with a range of 0.15cc/min to 17.2cc/min. Temperature distribution within reactor was recorded by 3 thermocouples and total amount of liquid product was measured. Temperature distribution and factors that affect temperature were observed and relation between temperature distribution and production rate was also analyzed. Relative time scale plays a significant role in the performance of the reactor. To obtain steady state operation, appropriate ratio of flow rate, catalyst mass and reactor geometry is required and furthermore to get more efficient production rate temperature distribution should be evenly distributed. The database obtained by the experiment will be used as a design parameter for micro reactor.

• Clinical Pain
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• v.19 no.1
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• pp.23-27
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• 2020

Our objective is to evaluate the applicability of segmental phase angle (PhA) via bioelectrical impedance analysis (BIA) for post-stroke complex regional pain syndrome (CRPS). Due to its noninvasiveness and convenience, various studies have used BIA in clinical conditions. We measured segmental PhA in 4 patients at the time of CRPS diagnosis and repeated 4 weeks after 2 weeks of steroid pulse therapy. In 3 cases, the affected-to-unaffected ratio of the upper limb PhA decreased at the time of diagnosis. In 2 cases with improvement of more than 5 points in the CRPS severity score (CSS), increased ratios were observed. In other 2 cases with improvement of less than 4 points in the CSS, no remarkable changes in the ratios were found. We suggest that the segmental PhA can be helpful in assessment of post-stroke CRPS and its recovery.

• Korean Journal of Materials Research
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• v.21 no.10
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• pp.563-567
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• 2011

We report the structural characterization of $Bi_xZn_{1-x}O$ thin films grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy. By increasing the Bi flux during the growth process, $Bi_xZn_{1-x}O$ thin films with various Bi contents (x = 0~13.17 atomic %) were prepared. X-ray diffraction (XRD) measurements revealed the formation of Bi-oxide phase in (Bi)ZnO after increasing the Bi content. However, it was impossible to determine whether the formed Bi-oxide phase was the monoclinic structure ${\alpha}-Bi_2O_3$ or the tetragonal structure ${\beta}-Bi_2O_3$ by means of XRD ${\theta}-2{\theta}$ measurements, as the observed diffraction peaks of the $2{\theta}$ value at ~28 were very close to reflection of the (012) plane for the monoclinic structure ${\alpha}-Bi_2O_3$ at 28.064 and the reflection of the (201) plane for the tetragonal structure ${\beta}-Bi_2O_3$ at 27.946. By means of transmission electron microscopy (TEM) using a diffraction pattern analysis and a high-resolution lattice image, it was finally determined as the monoclinic structure ${\alpha}-Bi_2O_3$ phase. To investigate the distribution of the Bi and Bi-oxide phases in BiZnO films, elemental mapping using energy dispersive spectroscopy equipped with TEM was performed. Considering both the XRD and the elemental mapping results, it was concluded that hexagonal-structure wurtzite $Bi_xZn_{1-x}O$ thin films were grown at a low Bi content (x = ~2.37 atomic %) without the formation of ${\alpha}-Bi_2O_3$. However, the increased Bi content (x = 4.63~13.17 atomic %) resulted in the formation of the ${\alpha}-Bi_2O_3$ phase in the wurtzite (Bi)ZnO matrix.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.58.4-59
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• 2015

We have performed single dish and VLBI monitoring observations of $H_2O$ and SiO masers toward the semi-regular variable star R Crateris using the Korean VLBI Network(KVN) 4 band receiving system. In the case of VLBI observations at 3 epochs, successful superposed maps of $H_2O$ and SiO masers were obtained on 2015 May by adopting the Source Frequency Phase Referencing(SFPR) method. These results enable us to investigate the development of outflow and asymmetric motions from SiO maser to $H_2O$ maser regions according to stellar pulsation which are closely related with a mass-loss process. Single dish monitoring observations were carried out from 2009 June to 2015 May. Intensity variations between $H_2O$ and SiO masers were investigated according to stellar phases together with peak velocity variations. We will compare the VLBI results with those of single dish.

• Journal of Ginseng Research
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• v.24 no.3
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• pp.143-147
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• 2000

In previous studies we have demonstrated that several individual ginsenosides such as Rc, Rd, Re and Ri relieves formalin-induced pain following systemic treatment. But it is unknown where these single ginsenosides induce antinociception. We investigated the antinoiceptive effect of four individual ginsenosides on formalin-induced pain after intrathecal (i.t.), intracereventricular (i.c.v.), or subcutaneous (s.c.) administration using mice. We found that ginsenoside Rc, Rd, and Re except Rf attenuated both acute and tonic phase of pain. Ginsenoside Rf attenuated only tonic phase of pain after i.t. administration. The ED$\_$50/ was 1.0 (0.55∼l.75 mg/kg) for Rc, 1.15 (0.6∼2.25 mg/kg) for Rd, and 8.9 (3.9∼20.5 mg/kg) for Re in acute phase of pain. The ED$\_$50/ was 0.3 (0.1∼0.85 mg/kg) for Rc, 0.6 (0.35∼l.1 mg/kg) for Rd, 2.45 (1.25∼4.65 mg/kg) for Re, and 1.9 (1.5∼4.25 mg/kg) for Rf in tonic phase of pain. We also found that ginsenoside Rc, Rd, Re, and Rf after i.c.v. administration attenuated both acute and tonic phase of pain. The ED5o for acute phase of pain was 0.9 (0.55∼l.4mg/kg) for Rc, 0.9 (0.45∼1.7 mg/kg) for Rd, 0.93 (0.5∼l .75 mg/kg) for Re, and 1.85 (0.95∼3.5 mg/kg) for Rf. The ED$\_$50/ for tonic phase of pain was 0.7 (0.45∼1.05 mg/kg) for Rc,1.25 (0.7∼2.2 mg/kg) for Rd, 0.85 (0.45∼1.6 mg/kg) for Re, and 0.8 (0.4∼1.45 mg/kg) for Rf. Thus, the order of the analgesic potency was Rc$\geq$Rd>Re>Rf in both i.t. and i.c.v. administration routes. However, s.c. pretreatment of four ginsenosides did not reduce formalin-induced pain. These results suggest that analgesic effect of ginsenosides is achieved through spinal or supraspinal site(s) in formalin test.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.321-324
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• 2002

In situ recovery of recombinant human granulocyte-macrophage colony stimulating factor (hGM-CSF) was performed in transgenic Nicotiana tabacum cell suspension cultures. Aqueous two-phase systems (ATPS) were used to utilize its biocompatibility. Transgenic plant cells could be grown up to 15.7 g/L in normal medium and 18.6 g/L in ATPS composed of 6% (w/w) polyethylene glycol (PEG) 20,000 and 10% (w/w) dextran 2,000,000. It was proved that the A TPS was not harmful to cell growth. In addition, It is expected to recover hGM-CSF simultaneously with cell growth. Using this method, maximum hGM-CSF concentration at 1.64 ng/mL was obtained on day 3.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.9-17
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• 2011

Nano-composite solders have been studied to improve the properties of Pb-free solder joints. The nanoparticles in the composite solders were carbon nanotubes(CNTs), metals (Ag, Ni, Cr, etc.), ceramics (SiC, $ZrO_2$, $TiB_2$, etc.). To fabricate the nano-composite solders, mechanical mixing methods and in-situ fabrication method has been used for well-dispersed nano phase. The characteristic properties of the nano-composite solders were high creep resistance, low undercooling, low IMC growth rate and fine microstructures. More researches on the nano-composite solders are required to improve the processibility and the reliability of the nano-composite solder joints.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.57.2-57.2
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• 2017

KVN is a millimeter VLBI array composed of three 21m-diameter radio telescopes at Seoul, Ulsan and Jeju island in Korea. KVN has unique simultaneous multi-frequency receiving systems, which enable us to correct phase fluctuation of troposphere by transferring phase solution of low frequency data to higher frequency data. Although KVN can achieve very high performance up to 130 GHz through multi-frequency technique, imaging capability is highly limited because of lack of the number of baselines. In order to enhance imaging capability and maximizing multi-frequency capability, we plan to extend KVN baselines from 3 to 10 (or more) by constructing new KVN stations. This talk introduce expected performances, science cases, required budgets and periods of the Extended-KVN.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.69-75
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• 2004

The degree of the indentation damage and strength degradation for 3Y-TZP ceramics and (Y,Nb)-TZP/$Al_2O_3$ dental implant composites was investigated under the Hertzian cyclic fatigue. Fatigue tests were conducted at contact loads of 500 to 3000 N and up to $10^6$ cycles in exact in vitro environments. At 500 N, no strength degradation and crack generation was observed up to $5{\times}10^5$ contact cycles. Fatigue properties of 3Y-TZP ceramics was superior to (Y,Nb)-TZP/ㅍ composites due to stress relief caused by the phase transformation from tettagonal to monoclinic phase. As contact load increased, the drastic reduction in strength was found when the damage transition from ring to radial crack occurred. The extent of strength degradation was more pronounced in vitro environments probably due to chemical corrosion of artificial saliva through cracks introduced during large numbers of contacts.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.3
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• pp.73-78
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• 2011

The pH is one of the most important factors affecting metabolism pathway and activity of hydrogen producing bacteria. The effect of operational pH on anaerobic hydrogen fermentation of food waste was evaluated at mesophilic condition. In this batch experiment, the initial pH was 8.0 and the operational pH was controlled at 4.7~7.0 by the addition of 5N KOH solutions. At the operational pH of 4.7, the lag phase and the maximum hydrogen production were 47.9h and 534.4 mL, respectively. The lag phase and the maximum hydrogen production were decreased as the operational pH increased. At the operational pH of 7.0, the lag phase and the maximum hydrogen production were 4.2 h and 213.8 mL, respectively.