• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.506-510
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• 2004

A torque transmission system composed of several gears and couplings is flexible. In order to get an exact response of motor, the torsional vibration due to an unexpected change of motor speed must be suppressed. Therefore, it is very important that motor control suppress vibration. Various methods to control it including dual inertia system are proposed. Specially, the method of vibration suppression is that vibration can be suppressed to fee㏈ack the estimated torsion torque via the disturbance observer filter being of normal filter. The suitable Proportional controller and coefficient parameter can be designed using CDM and the torsional vibration also be suppressed, but it has a low degree of adaptability to disturbance. The PID controller can be designed easily, but makes the excessive overshoot and oscillation for system response in the early period. To resolve these problems, simple and practical PID controller with two degree of freedom is proposed recently that it ran improve performance of obeying the reference unconcerned in any disturbance by changing the proportional gain by two degree of freedom parameter. But it has also the defect that parameter a must be changed to obtain the ideal Proportional parameter. On this paper, we design the controller which automatically adjusts parameter u using fuzzy Algorithm to overcome such defects. Also, we compare the proposed method with established one and evaluate them to confirm performance of the designed controller.

• Journal of the Korean Vacuum Society
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• v.14 no.4
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• pp.207-214
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• 2005

This paper presents a channel structure for promising high performance pseudomorphic high electron mobility transistor(pHEMT) switching device for design and fabricating of microwave control circuits, such as switches, phase shifters, attenuators, limiters, for application in personal mobile communication systems. Using the designed epitaxial channel layer structure and ETRI's $0.5\mu$m pHEMT switch process, single pole double throw (SPDT) Tx/Rx monolithic microwave integrated circuit (MMIC) switch was fabricated for 2.4 GHz and 5 GHz band wireless local area network (WLAN) systems. The SPDT switch exhibits a low insertion loss of 0.849 dB, high isolation of 32.638 dB, return loss of 11.006 dB, power transfer capability of 25dBm, and 3rd order intercept point of 42dBm at frequency of 5.8GHz and control voltage of 0/-3V These performances are enough for an application to 5 GHz band WLAN systems.

• Korean Journal of Weed Science
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• v.31 no.4
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• pp.368-374
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• 2011

This experiment was conducted to Investigate the herbicidal activity of naturally developed d-Limonene on the control of Sicyos angulatus L. which is destructive to biodiversity and ecosystem under greenhouse and open field condition. Among the tested concentrations, most efficacy of early foliar application(leaf stage with 1.5 and 3) of d-Limonene was found in $70mg\;mL^{-1}$, followed by $35mg\;mL^{-1}$, $17.5mg\;mL^{-1}$ in that order under greenhouse condition. The higher the d-Limonene concentration, the better the effect in greenhouse condition. In leaf stage with 2, 3 and 5 under open field condition, the higher the d-Limonene concentrations, the higher the weeding effect. The remarkable effect was, particularly, found in d-Limonene with $70mg\;mL^{-1}$ while little was found in the plants with d-Limonene with $35mg\;mL^{-1}$. In the case of 15 leaf stage of S. angulatus L. treated with d-Limonene under outside treatment effect was low. The treatment effect of d-Limonene under open field compared with greenhouse condition was more significant. It can be recommended that d-Limonene with $70mg\;mL^{-1}$ could control S. angulatus L. by 5 leaf stage.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.2
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• pp.41-48
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• 2011

In this study, the soil remediation by landfarming was carried out using microbial activators. Feasibility studies and reduction capacity of TPH(Total Petroleum Hydrocarbons) were investigated in order to find out how fast and eco-friendly the contaminated soil can be recovered. The lab-test confirmed not only the performance and degradation efficiency of microbial activators but also the effect of TPH reduction in the contaminated soil. The optimum growth conditions for indigenous microorganisms were identified using microbial activators. Based on the results of TPH removal, although there had been a little of difference in between natural decomposition and microbial activators until 20 days, the sample groups of microbial activators were higher than the control ones after 20 days. Microbial activators were applied to the field experiments on landfarming. Based on the results of removal rate in each floor of soil, it was found that the removal rates were 85.8 % in the upper, 84.4 % in the middle, and 66.10 % in the bottom. Considering that the reduction rate of TPH for the control group averaged 71.1%, the microbial activators might not be fully transferred into the bottom, which resulted from the piles of soil. As the piles have already reached 1 m in the field experiments, the low piles of soil under 0.6 m may enhance the treatment efficiency of TPH.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.17-25
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• 2022

The pintle injector has many advantages in the key characteristics of a liquid rocket engine, such as combustion stability, combustion efficiency, and wide range of comprehensive thrust control, design and manufacture, and test fired under supercritical conditions. The pintle injector is manufactured with a rectangular, single-row orifice for thrust control and production considerations. In order to verify the combustion performance of the pintle injector and its potential as a commercial injector, the combustion characteristics were analyzed by varying the TMR (Total Momentum Ratio) and BF (Blockage Factor). The result of the hot firing test showed that the heat flux increased as TMR increased, and it confirmed that the characteristic velocity efficiency was more affected by BF than TMR. Suppose a single-row pintle injector with efficiency characteristics insensitive to changes in TMR can achieve high efficiency at low fuel differential pressure conditions. In that case, the variable pintle injector's design flexibility can be increase.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.5
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• pp.78-89
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• 2022

Super - Bus Rapid Transit (S-BRT), adding the advantages of urban railroads to BRT, has emerged to solve the problem of low speed and reliability of the existing BRT. Notably, the S-BRT driveway is classified into exclusive lanes and roads, as BRT, in the domestic guidelines. However, S-BRT and BRT have different operating goals and characteristics, so it is necessary to systematize the S-BRT driveway. Therefore, this study classified an S-BRT driveway into exclusive lane, shared lane with overtaking lane, and shared lane without overtaking lane based on domestic conditions. Subsequently, a control strategy for transit signal priority in each driveway was presented by the study based on the characteristics of the driveway to achieve the S-BRT target service level. Finally, the S-BRT target service level was almost achieved, and the travel speed was high and increased in the order respectively in the exclusive lane, shared lane with overtaking lane, and shared lane without overtaking lane in the study. Hence, it is important to operate a transit signal priority considering the characteristics of each driveway when operating the S-BRT. In essence, this study is expected to be used as a reference for driveway design and transit signal priority operation when introducing S-BRT in each local government in the future.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.236-247
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• 1996

The main objective of this study was to evaluate the effectiveness of nutrient solutions, substrates, and nutrient solution concentrations in substrate culture of radish(Raphanus sativus L. var. sativus). Cooper's, Hoagland ＆ Arnon' 5, and Yamazaki's solution were used to determine the most suitable nutrient solution in deep flow culture(DFC). In result, Yamazaki's solution treatment showed better results than Hoagland's and Cooper's solution treatments in leaf length, leaf number, shoot and root fresh weights. Cooper's solution was much worse than others. Root shape index were low as 0.6 in all treatments. The selection of suitable was conducted among 14 kinds of substrates which were used commercially, such as sand, perlite and peatmoss, in substrates culture. Sand was the most proper in radish growth and shortened the growth periods. Sand also showed better results then others in leaf length, leaf number, shoot and root fresh weight. On the contrary, radish growth in peatmoss was the worst. Generally, root shape index was higher in substrate than in DFC. In order to investigate the suitable ionic strength in radish, Yamazaki's solution was treated with EC of 0.5, 1.0, 1.5, and 2.0 mS/cm. Generally radish growth above 1.0 mS/cm concentration was good, and the best result was shown in 1.5 mS/cm. Vitamin C contents were not significantly different in the roots of radish grown under 1.0 mS/cm or more. The highest vitamin C content was shown in 0.5 mS/cm, and so was thiocyanate content. Anthocyanin contents increased with the increase of the ionic strength in nutrient solution. Mineral nutrient contents had no significant statistical differences between the treatments, but potassium content was remarkably high in 1.5 mS/cm.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.67-76
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• 2023

In this study, in order to enhance the joint capacity between the existing reinforced concrete (R/C) frame and the reinforcement member, we proposed a novel concept of Internal Composite Seismic Strengthening Method (CSSM) for seismic retrofit of existing domestic medium-to-low-rise R/C buildings. The Internal CSSM rehabilitation system is a type of strength-enhancing reinforcement systems, to easily increase the ultimate horizontal shear capacity of R/C structures without seismic details in Korea, which show shear collapse mechanism. Two test specimens of full-size two-story R/C frame were fabricated based on an existing domestic R/C building without seismic details, and then retrofitted by using the proposed CSSM seismic system; therefore, one control test specimen and one test specimen reinforced with the CSSM system were used. Pseudo-dynamic testing was carried out to evaluate seismic strengthening effects, and the seismic response characteristics of the proposed system, in terms of the maximum shear force, response story drift, and seismic damage degree compared with the control specimen (R/C bare frame). Experiment results indicated that the proposed CSSM reinforcement system, internally installed to the existing R/C frame, effectively enhanced the horizontal shear force, resulting in reduced story drift of R/C buildings even under a massive earthquake.

• Herbal Formula Science
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• v.32 no.3
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• pp.235-245
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• 2024

Objective : The study's objective is to assess the components of Dendropanax morbifera (DM) utilizing UPLC-MS/MS and assess their antioxidant properties in order to establish fundamental information for quality control of herbal formulations. Methods : The DM leaves were ground into powder and extracted with water at 80℃. The extract was subsequently concentrated and subjected to freeze-drying for subsequent analysis. The LC-MS/MS analysis was performed using a 1260 series HPLC system and a 3200 QTrap tandem mass system in positive ion mode, with detection conducted at 280 nm. The Folin-Ciocalteu method was employed to measure the phenolic content, while a colorimetric method using aluminum chloride was used to determine the flavonoid content, with gallic acid and quercetin as standards, respectively. The evaluation of antioxidant activity was conducted through the measurement of DPPH radical scavenging activity, by adding the DPPH solution to the extract and recording the absorbance at 517 nm. Results : The UPLC-MS/MS analysis identified five polyphenolic compounds in the DM extract, specifically syringin, 6-hydroxyluteolin 7-O-laminaribioside, shaftoside, rutin, and kaempferol-3-O-rutinoside. The extract was found to contain a total phenolic content of 83.106 ± 0.21 mg GAE/g and a total flavonoid content of 87.963 ± 1.014 mg QE/g. The DM extract demonstrated substantial antioxidant properties, resulting in a reduction of DPPH radicals that was evident at concentrations as low as 40 ㎍/㎖. Conclusions : The study determined important polyphenolic compounds in DM and established its considerable antioxidant efficacy. These findings provide evidence for the efficacy of DM in disease prevention related to oxidative stress and establish a foundation for ensuring quality control in herbal preparations.

• FLOWER RESEARCH JOURNAL
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• v.19 no.4
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• pp.187-191
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• 2011

Rising soil temperature was effectively controled by shading net of 50% and cooled water to maintain average $18.8^{\circ}C$ (maximum $23^{\circ}C$), then shading net of 50% and ground water to maintain average $23.2^{\circ}C$ (max. $28.5^{\circ}C$), shading paint of 30% and shading net (50%) to maintain average $24^{\circ}C$ (max. $30^{\circ}C$) in that order. Alstroemeria 'Modena' most affected by shading and cooling water was better in shoot length as 95.9 cm and fresh weight as 67 g than those of other treatments. The production of cut flower was increased more 121% with treatment 50% shading net and cooling water, 59% with 50% shading net and ground water, and 65% with 30% shading paint than that of 50% shading net, respectively. Soil temperature was higher $8^{\circ}C$ with the plot of circulating warm water than untreated control plot. Alstroemeria 'Aspen', 'Modena', and 'Chanel' increased more plant growth such as plant height, fresh weight in warm water than in untreated control plot, but Alstroemeria 'Bordeaux' decreased plant height. Because of increasing plant growth, flower quality such as peduncle length, peduncle diameter, floret number and flower weight of 4 all cultivar was better in the plot of circulating warm water than untreated control plot. Also, the production of cut flower was increased the most in Alstroemeria 'Modena' by 38%, 'Aspen', 'Bordeaux', and 'Chanel' in that order.