• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.87-94
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• 2023

As the latest weapon systems and electronic equipments are increasingly demanding stealth technology to improve the survivability of allies, it is necessary to implement low-observability technology that reduces the radar cross section(RCS). In order to implement this stealth technology, a method for low RCS characteristics by applying a shape design or a electromagnetic wave absorber is widely used. However, active phased array antennas have structural limitations in shape design, also when a absorber is applied to it, the performance of the antenna is degraded. Therefore, in this paper, in order to realize the low RCS characteristics of the active phased array antenna operating in the X-band, individual radiating elements suitable for applying the radio wave absorber were selected, and a 13x13 array antenna was designed and manufactured. Next, by comparing the measured results of the relative RCS and electrical performance for the manufactured antenna according to the presence and type of the absorber, it is shown that the electrical performance is maintained at an equal or higher level while obtaining the low RCS characteristics. Thereby the method proposed in this paper for implementing the low RCS characteristics was validated. Finally, it was confirmed that when the wave absorber is applied to the array antenna, the limitation of its performance deterioration can be overcome.

• Journal of Nutrition and Health
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• v.41 no.7
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• pp.594-601
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• 2008

Panax ginseng C.A. Meyer (Panax ginseng) has been used for several thousand years to prolong longevity in Asian countries. Ginsenosides are the most active components isolated from ginseng and belong to damarane saponin which are separated into protopanaxadiol and protopanaxtriol. To evaluate the complex effect of ginsenoside in apo E null mice, ginseng extract were intraperioneally (i.p.) injected and provided high-cholesterol diet for 12 weeks. Ginseng extract came from were i.p. injected with dose of 100 mg/kg/day for 4 weeks in the last experimental duration. Ginseng extract used experiment was abundant Rb1, Rc, Re, and Rg1 and PD：PT ratio was 1.2. The high-cholesterol diet induced liver damage was significantly reduced by ginseng extract. Results from plasma lipid profiles and atherogenic index were improved by ginseng extracts. The GE group significantly decreased plasma TG and TC by 73% and 61% compared to apo E (-/-) group. Also ginseng extract tend to decrease lipid profiles and lipidperoxidation contents in liver and heart. Ginseng extract with an abundant amount of Rg1 significantly suppressed the apoptosis induction of cardiac tissue. In conclusion, ginseng extract (PD：PT = 1) was improved lipid profiles and anti-oxidant effects.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.3
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• pp.273-288
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• 1997

In this work, the electromagnetic waves scattered from 2-dimensional random rough surfaces are characterized by the $4\times4$ Mueller matrix elements. The full wave solutions are used to compute these elements. The results of the full wave solutions for 1-dimensional random rough surfaces were shown to agree well with those of the experiment and the method of moments. The Mueller matrix elements are related to the like and cross polarized radar cross sections as well as to the relative phase of the vertically and horizontally polarized waves. The $4\times4$ Mueller matrix elements completely characterize electromagnetic scattering from target. The computed results of this paper can be useful to the field of active remote sensing or RCS.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.146-152
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• 2015

In this paper, we propose a boost DC-DC converter using a modification of the passive auxiliary resonant snubber circuit with a DC-DC converter in a typical active auxiliary resonant snubber-bridge inverter. The proposed boost DC-DC converter is small compared to the DC-DC converter according to the soft-switching scheme that requires a general auxiliary switch by realizing the soft switching operation as a DC-DC converter which does not require an auxiliary switch. It is light-weight, switch the turn-on and turn-off switching loss at the time of the superposition of the voltage and current is extremely small, so small. And the reduction of the surge voltage and current of the switch. In addition, the proposed boost DC-DC converter has a high efficiency over a wide load characteristics change area than conventional hard switching PWM boost converter using an RC snubber loss.

• Korean Journal of Medicinal Crop Science
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• v.16 no.2
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• pp.79-85
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• 2008

Some studies of dandelion have been carried out on bioactivities, however, no comparative analysis on antioxidant and cytotoxic activities in the Korean dandelion (T. coreanum NAKAI.; KD) and dandelion (T. officinale WEB.) have been reported. In this study, the extracts of KD and dandelion analyzed relative phenolic contents and free radical scavenging, antioxidant enzyme and cytotoxic activities. The extract of Korean dandelion leaves (KDL) exhibited a higher phenolics content ($368{\pm}11.5\;mg/l00\;g$) and a strong free radical scavenging activity ($RC_{50}$value;87.89 ug/ml) than other parts and BHT (120.12 ug/ml), synthetic antioxidant. At ascorbate peroxidase (APX) activity, the dandelion root (DR) had a greater (38.8 U/mg protein) antioxidant enzyme compare to the dandelion leaves (12.2 U/mg protein). The catalase (CAT) and superoxide dismutase (SOD) followed higher enzyme activity in Korean dandelion root (KDR) than other parts. In a cytotoxic activity against human cancer cell, the extracts of KDR was found to be active against Calu-6, HCT-116, and SNU-601 cell lines, with $IC_{50}$ values of 522.34, 532.74 and 614.85 ug/ml, respectively. These results suggest that KD and dandelion would be an alternative antioxidant source, based on natural plant resources.

• Nano
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• v.13 no.10
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• pp.1850121.1-1850121.11
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• 2018

In this study, a series of $LaMnO_3$-diamond composites with varied $LaMnO_3$ mass contents supported on micro-diamond have been synthesized using a sol-gel method. The as-prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and the Fourier transform infrared spectra (FTIR). Meanwhile, the photocatalytic performances were also tested by photoluminescence (PL) spectroscopy, ultraviolet-visible diffuse reflection spectra (UV-Vis DRS) and the degradation of weak acid red C-3GN (RC-3GN). Results show that the peak position of $LaMnO_3$ is shifted to low angle after the introduction of diamond, and perovskite particles uniformly distributed on the surface of diamond, forming a network structure, which can increase the active sites and the absorption of dye molecules. When the mass ratio of $LaMnO_3$ and diamond is 1:2 (LMO-Dia-2), the composite shows the most excellent photocatalytic activity. This result offers a sample route to enlarge the range of the application of micro-diamond and provide a new carrier for perovskite photocatalysts.

• Journal of the Korean Society of Safety
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• v.36 no.3
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• pp.24-30
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• 2021

Heat is generated during the synthesis and mixing process of chemical compounds due to a change in activation energy during the reaction. A runaway reaction occurs when sufficient heat is not removed during the heat control process within a reactor, rapidly increasing the temperature, reaction speed, and rate of heat generation inside the reactor. A risk assessment was executed using an RC-1 (Reaction Calorimeter) during Friedel-Crafts acylation. Friedel-Crafts acylation runs the risk of rapid heat generation during Active Pharmaceutical Ingredient (API) manufacturing; it was used to confirm the risk of a runaway reaction at each synthesis stage and during the mixing process. This study used experimental data to develop a safety efficiency improvement plan to control the risks of runaway and other exothermic reactions, which was implemented at the production site of a chemical plant.

• Journal of Ginseng Research
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• v.46 no.6
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• pp.711-721
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• 2022

The immune system is one of the most important parts of the human body and immunomodulation is the major function of the immune system. In response to outside pathogens or high inflammation, the immune system is stimulated or suppressed. Thus, identifying effective and potent immunostimulants or immunosuppressants is critical. Ginsenosides are a type of steroid saponin derived from ginseng. Most are harmless to the body and even have tonic effects. In this review, we mainly focus on the immunostimulatory and immunosuppressive roles of two types ginsenosides: the protopanaxadiol (PPD)-type and protopanaxatriol (PPT)-type. PPT-type ginsenosides include Rg1, Rg2, Rh4, Re and notoginsenoside R1, and PPD-type ginsenosides include Rg3, Rh2, Rb1, Rb2, Rc, Rd, compound K (CK) and PPD, which activate the immune responses. In addition, Rg1 and Rg6 belong to PPT-type ginsenosides and together with Rg3, Rb1, Rd, CK show immunosuppressive properties. Current explorations of ginsenosides in immunological areas are in the preliminary stages. Therefore, this review may provide some novel ideas to researchers who study the immunoregulatory roles of ginsenosides.

• Geomechanics and Engineering
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• v.33 no.3
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• pp.243-259
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• 2023

Turkey is one of the most important earthquake regions in Europe. This region has been exposed to many earthquakes of different magnitudes from past to present. It is of great importance to determine the dynamic properties of the soils for structures to be built in earthquake zones. In order to minimize the damages that may occur, the behavior of the soils under repeated loads should be known and taken into consideration in the design. In this study, 4 different point borings were taken near active fault lines in the North Anatolian fault zone (NAFZ). In order to determine the dynamic parameters of soils, both dynamic triaxial (TRX) and resonant column (RC) tests were carried out on undisturbed samples at every 5 m. As a result of the experiments, V_s and G_max values were obtained from the field and differences were determined. The dynamic behavior of the soil was examined at varying depths with the comparison of reference models in the literature and compatible results were obtained. Finally, the behavior at the transition region is highlighted. As a result, three shear modulus and dumping ratio models have been proposed for clay soils to be used in different soil conditions.

• Food Science and Preservation
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• v.30 no.3
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• pp.434-445
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• 2023

Hemp (Cannabis sativa L.) seeds have recently been attracting attention as a new high-value-added food material owing to their excellent nutritional properties, and research on the development of functional food materials using hemp seeds is actively progressing. This study aimed to evaluate the antioxidant properties of hemp seed protein hydrolysates. Protein hydrolysates were prepared from defatted hemp seed powder (HS) by enzymatic hydrolysis using five different proteases (alcalase, bromelain, flavourzyme, neutrase, and papain). 2,4,6-trinitrobenzene sulfonic acid (TNBS) assay and SDS-PAGE analysis revealed that HS showed a high degree of hydrolysis after treatment with each enzyme except papain. The total polyphenol content of the protein hydrolysates (<3 kDa) and the RC50 values obtained from two different antioxidant tests showed that alcalase hydrolysate (HSA) had a relatively high level of antioxidant capacity. In addition, treatment with HSA (25-100 ㎍/mL) significantly inhibited linoleic acid peroxidation. These results suggest that hemp seed protein hydrolysates are potential sources of natural antioxidants. Future studies will focus on the identification of active peptides from HSA.