• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.644-651
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• 2005

In this paper, a new predistortion method to reduce nonlinearity or a traveling wave tube amplifiers(IWTAs) is proposed. Nonlinear transfer characteristics of TWTA are analyzed using carrier complex power series. Inverse carrier complex power series or a predistortion linearizer to linearizer TWTA are also proposed. The inverse nonlinear distortion characteristics of predistorter can be realized with reflective structure that is composed of Schottky diode and resistive-terminated transmission line. The AM-to-AM and the AM-to-PM characteristics for TWTA by proposed predistortive linearizer on K-band were improved from -5.825 dB and -37.321^{\circ} to 0.786 dB and 6.742^{\circ}, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.1072-1077
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• 2007

In this paper, a power amplifier intermodulation distortion has been analyzed to improve linearity and the analysis results are used to minimize the distortion for linear power amplifier design. The proposed design technique is which the intermodulation distortions of the final amplifier are removed by driver intermodulation distortions. This proposed technique is based on AM to AM distortion analysis using power series, and AM to PM distortion analysis results using Bessel function. To verify this technique implement a cellular HPA(High Power Amplifier) 30W. From the results of the implementation and measurement for the linear power amplifier, the spurious characteristic is shown as 50 dBc at 1.98 MHz with 30 W with 20FA. These results show that distortion characteristics are improved as much as 10 dB in spurious characteristic compared with conventional design method.

• Clean Technology
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• v.21 no.3
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• pp.164-170
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• 2015

In this study, polysulfone-Escherichia coli biomass composite fiber (PSBF) was prepared by spinning the suspension of PS and E. coli biomass and amine-methylated PSBF (AM-PSBF) was fabricated through the methylation of amine groups in PSBF. As comparing the adsorption characteristics of basic dye, Basic Blue 3 (BB3) by the PSBF and AM-PSBF, the effect of the methylation of amine groups on BB3 adsorption was confirmed. pH edge experiments showed that the BB3 uptake of PSBF and AM-PSBF increased as pH was increased and the BB3 uptake of AM-PSBF was higher than that of PSBF at the same pH. Both of PSBF and AM-PSBF was reached at equilibrium within 5 h and kinetic experimental data were well fitted by the pseudo-first-order kinetic model. By the Langmuir model, the maximum adsorption capacities of PSBF and AM-PSBF at pH 8 were evaluated to be 28.9 and 20.7 mg/g, respectively. The maximum adsorption capacity of AM-PSBF was enhanced 1.4 times comparing that of PSBF. These results indicate that the methylation of amine groups in PSBF leads to the improvement of BB3 adsorption capacity. In addition, the results of desorption experiments revealed that AM-PSBF was repeatedly reusable.

• Applied Biological Chemistry
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• v.47 no.2
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• pp.182-186
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• 2004

Morphological observation of roots and molecular technique were used to investigate the symbiotic relationships between arbuscular mycorrhizal (AM) fungi and ginseng roots. Korean ginseng, Panax ginseng, was collected from 8 sites in Korea. Colonization pattern of AM fungi in ginseng roots was determined as an Arum type under light microscopes. Nested PCR using AM fungal specific primers was employed to amplify a partial region on 18s rDNA of AM fungi from the root extracted mixed DNA. The amplified DNA was cloned and analyzed by random fragment length polymorphism (RFLP) with restriction enzymes, AluI, HinfI and AsuC21. One from each RFLP pattern was selected for sequencing. A total 16 clones were sequenced and identified as 2 species of AM fungi; Paraglomus brasilianum and Glomus spurcum. Paramglomus brasilianum was found from most of the ginseng roots, in this syudy suggesting that this species of AM fungi could have specific relationship with the ginseng root. Possible roles of AM fungal species in ginseng roots are discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.206-214
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• 2020

This study examined the correlation between the respiratory pattern change (RPC) and abdominal mobility (AM) according to the positive result of the subjective lumbar instability factor (SLIF) in people with chronic low back pain (CLBP). Thirty-six adults with CLBP participated in this study. Twenty-eight items of the SLIFs were examined, and the subjects were divided into three groups according to the positive response numbers (PRN). After the change lists were scored, three RPC scores [costo-diaphragmatic RPC (CDRPC), breath hold change (BHC), and total RPC (TRPC)] were obtained. The abdominal mobility (AM) was measured between the maximal inspiration and exhalation at the xiphoid (AM1) and the 10^th rib (AM2) level of the trunk. The results showed that the RPC score and AM were compared according to the positive response number of SLIF, and the relationship between them was analyzed. A positive correlation was observed between the SLIF positive response number and CDRPC score, BHC score, and total RPC score, and a negative correlation was observed between the SLIFs positive response number and AM1 and AM2. Based on the results of this study, the combination of SLIF positive responses can be a predictor of non-physiological respiratory pattern changes in people with CLBP. Clinically, this prediction is expected to help save time for screening and improve the efficiency of therapy.

• Mycobiology
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• v.34 no.1
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• pp.7-13
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• 2006

Arbuscular mycorrhizas (AM) have mutualistic symbiosis with plants and thus efforts have been placed on application of these symbiotic relationships to agricultural and environmental fields. In this study, AM fungi were collected from 25 sites growing with 16 host plant species in Korea and cultured with Sorghum bicolor in greenhouse condition. AM fungal spores were extracted and identified using both morphological and molecular methods. Using morphological characters, total 15 morpho-speices were identified. DNA was extracted from single spore of AM fungi and a partial region on 18S rDNA was amplified using nested PCR with AM fungal specific primers AML1/AML2. A total of 36 18S rDNA sequences were analyzed for phylogenetic analysis and 15 groups of AM fungi were identified using both morphological and molecular data of spores. Among the species, 4 species, Archaeospora leptoticha, Scutellospora castanea, S. cerradensis, S. weresubiae were described for the first time in Korea and two species in Glomus and a species in Gigaspora were not identified. Morphological and molecular identification of AM fungal spores in this study would help identify AM fungal community colonizing roots.

• Journal of Physiology & Pathology in Korean Medicine
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• v.33 no.5
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• pp.282-287
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• 2019

In this study, we investigated the anti-obesity effects of various mixtures of Atractylodes macrocephala (AM) and Amomum villosum (AV) water extracts on high-fat diet (HFD) induced mouse model. We classified five groups as follows; control, HFD, HFD + AM extracts : AV extracts (100mg/kg) (1:1), HFD + AM extracts : AV extracts (100mg/kg) (2:1), HFD + AM extracts : AV extracts (100mg/kg) (3:1). Oral administration of various mixtures of AM and AV extracts for 6 weeks inhibited HFD-induced increases of body, liver and epididymal fat weights. Also, lipid profiles including LDL cholesterol were improved by various mixtures of AM and AV extracts treatment compared with HFD-fed group. Lipogenesis-related genes such as acetyl coA carboxylase (ACC) and fatty acid synthase (FAS) in liver changed in a favorable way for lipid biosynthesis by HFD compared to control, but various mixtures of AM and AV extracts-treated groups did not. Our results show that various mixtures of AM and AV extracts can prevent HFD-induced obesity in mice and suggests that the mechanisms are involved in expressions and modifications of lipogenesis-related genes such as ACC and FAS in liver.

• The Journal of Korean Medicine
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• v.35 no.2
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• pp.19-27
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• 2014

Objectives: To investigate the different effects of Sa-Am acupuncture with Spleen Jung-gyuck and Spleen Seung-gyuck on the radial pulse in healthy subjects. Methods: Sixty healthy volunteers (30 males and 30 females) participated in this study. The participants were randomly divided into three groups: control (C), Sa-Am acupuncture with Spleen Jung-gyuck (SP+) and Sa-Am acupuncture with Spleen Seung-gyuck (SP-). The radial pulse was measured using a multi-step tonometry system before, and 0, 30 and 60 minutes after acupuncture. Results: The heart rate adjusted radial augmentation index (RAI/HR) and high-tensioned pulse area (W area) significantly increased in the SP- group compared to the C and SP+ groups in males. The systolic pulse period (T4) increased significantly in the SP- group compared to the C and SP+ groups in females. The RAI/HR had positive correlations with W area and T4. Conclusion: The effects of Sa-Am acupuncture with Spleen Jung-gyuck and Spleen Seung-gyuck are different. Sa-Am acupuncture with Spleen Seung-gyuck induces acute increases of radial pulse parameters related to arterial stiffness in healthy subjects.

• Journal of Powder Materials
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• v.27 no.3
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• pp.256-267
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• 2020

Metal additive manufacturing (AM) technologies are classified into two groups according to the consolidation mechanisms and densification degrees of the as-built parts. Densified parts are obtained via a single-step process such as powder bed fusion, directed energy deposition, and sheet lamination AM technologies. Conversely, green bodies are consolidated with the aid of binder phases in multi-step processes such as binder jetting and material extrusion AM. Green-body part shapes are sustained by binder phases, which are removed for the debinding process. Chemical and/or thermal debinding processes are usually devised to enhance debinding kinetics. The pathways to final densification of the green parts are sintering and/or molten metal infiltration. With respect to innovation types, the multi-step metal AM process allows conventional powder metallurgy manufacturing to be innovated continuously. Eliminating cost/time-consuming molds, enlarged 3D design freedom, and wide material selectivity create opportunities for the industrial adoption of multi-step AM technologies. In addition, knowledge of powders and powder metallurgy fuel advances of multi-step AM technologies. In the present study, multi-step AM technologies are briefly introduced from the viewpoint of the entire manufacturing lifecycle.

• Biomolecules & Therapeutics
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• v.8 no.4
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• pp.332-337
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• 2000

Physicochemical properties of aspalatone (acetylsalicylic acid maltol ester, AM), which has been recently found to have an antithrombotic effect, were studied in terms of solubility, dissolution, partition coefficient (Pc) and stability. The solubility of AM at 37$^{\circ}C$ was about 1.2 mg/ml and the P$_{c}$ value for n-octanol/water and chloroform/water was 11.4 and 382.6, respectively. Dissolution rates of AM at pH 1.2 and 6.8 were more than 80% within 30 min. The degradation of AM followed apparent first-order kinetics, and was dependent on temperature, pH and ionic strength. From the pH-rate profile, the optimal pH was found to be at around 4.0. Half-lives at pH 1.2 and 6.8 were 33.5 and 44.4 hr, respectively. The degradation rate of AM at pH 1.2 was somewhat faster than that of aspirin, but at pH 7.0, the degradation rate of AM was slower than that of aspirin.n.