• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.2
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• pp.17-28
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• 2015

In this paper, it is accomplished to design a control method for such an actuation system of simplified ON/OFF mechanism with actuation command limit. First of all, based on experimental data, the modeling works for nonlinear/linear actuation dynamics are performed, which are govern by PWM command as a control input. Using the linearized model, a classical PI control method is designed to satisfy the aimed control performance requirements, and a control algorithm is proposed to realize the required control performance in the effective control region through resolving the issue for the PWM command limit which reduces the control performance. Finally, through control simulations, the design method is verified and the corresponding control performance improvement is evaluated.

• The Transactions of the Korea Information Processing Society
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• v.3 no.3
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• pp.512-522
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• 1996

To provide broadband ISDN service for the users in scattered locations, the application of satellite communications network is seriously considered. To trans mit ATM cells efficiently in satellite communications, it is effective to use TDM A method. However, it is necessary to have a method to compensate the cell delayvari-ation caused by the difference between TDMA and ATM. This paper optimized the cell control time(Tc) when traffic inputs have poisson or markov modulated poisson process by applying cell delay variation characteristics of time stamp method, which has the most advantages among compensation methods or cell delay variation. This paper also intorduces a method of reducing the cell clumping phenomena by adapting discrete time stamp method, including the analysis and evalutation of the range of required quality of CDV distribution by ATM transmission.The result of the experiment shows that CDV distribution-range can be controlled to 1.2$\times$Tc which reduces overall cell delay variation by discrrete time stamp method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.1
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• pp.57-67
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• 2013

In Korea, there are debris-flow disasters induced by typhoon and localized torrential rainfall annually. There are particularly extensive debris-flow disasters in Gangwon-do because of its geomorphological characteristics; the extensive coverage of mountainous region, steep slope, and shallow soil. In this paper, we constructed a GIS database about topological characteristics of debris-flow basin in Gangwon-do by years of field survey. Also, we conducted frequency analysis based on this database with the digital forest type map and the digital soil map. We analyzed frequencies of debris-flow by simple count for topological characteristics, whereas we analyzed by considering an area ratio based on GIS for physiognomic and geologic characteristics. We used slope, aspect, width, depth and destruction shapes for analysis about topological characteristics of debris-flow basin. Also we used attributes of forest physiognomy, diameter, age, and density about physiognomic characteristics, and i n terms of geologic characteristics, we used attributes of drainage class, effective soil depth, subsoil properties, subsoil grave content, erosion class, parent material of soil, and topsoil properties. In consequence, we figured out topographic, forest physiognomic, and geologic characteristics of debris-flow basin. This result is applicable to establish a rational disaster prevention policy as a fundamental information.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1128-1134
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• 2014

In this paper, the effects of a metamaterial slab with negative permeability in a magnetically coupled wireless power transfer system (WPT) in the overall performance are analyzed quantitatively in terms of the effective quality factors of the loop resonators and coupling coefficient considering the slab losses, based on an equivalent circuit. Using the ideal metamaterial slab(lossless slab), the WPT efficiency is improved considerably by the magnetic flux focusing. However, the practical lossy slab made of RRs or SRRs limits the significant enhancement of WPT efficiency due to the relatively high losses in the slab consisting of RRs or SRRs near the resonant frequency. For the practical loop resonator, other than a point magnetic charge, using the practical lossy metamaterial slab in order to improve the transfer efficiency, the width of the slab needs to be optimized somewhat less than the half of the distance between two loop resonators. For the low-loss slab with its loss tangent of 0.001, the WPT efficiency is maximized at 93 % when the ratio of the slab width and the distance between the two resonators is approximately 0.35, compared with 53 % for the case without the slab. The efficiency in case of employing the high-low slab(loss tangent: 0.2) is maximized at 61 % when the slab ratio is 0.25.

• Korean Journal of Plant Resources
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• v.26 no.5
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• pp.613-618
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• 2013

This study was conducted to investigate the morphological characteristics of leaf and the genetic diversity of Berchemia racemosa var. magna which is only found in Anmyeon Island of South Korea. ANOVA test showed that there were significant differences among individuals within population in all 10 leaf characteristics. Average characteristics of 39 individuals were 11.8 cm in leaf length, 7.1 cm in leaf width, 1.67 in leaf index, 5.4 cm in upper 1/3 width, 6.2 cm in lower 1/3 width, 3.6 cm in petiole length, 0.19 mm in leaf thickness, 11.5 ea. in number of veins (left), 11.4 ea. in number of veins (right) and 61.7 $cm^2$ in leaf area, respectively. Except for leaf thickness (18.8%), petiole length (21.7%) and leaf area (22.0%), the coefficients of variation of most leaf characteristics were relatively low (<15.0%). A total of 50 bands was generated from 8 selected I-SSR primers. The estimates of genetic variation were 1.719 in effective number of alleles ($A_e$), 26.0% in proportion of polymorphic bands (P), 0.410 in expected heterozygosity ($H_e$) and 0.598 in Shannon's diversity index (S.I.), respectively. In spite of the small number and the limited distribution, the B. racemosa var. magna population in Anmyeon Island showed high genetic diversity.

• Journal of Sensor Science and Technology
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• v.3 no.1
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• pp.68-77
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• 1994

Grid type 70Ni-30Co thin films on slide glass at $250^{\circ}C$ has been fabricated to develope. From fabricated sensors using above process, we investigated the relation of temperature, resistivity, line width to magnetoresistance and we obtained the following results after observation of coercive force, saturated magnetization, maxium usable sensitivity, delay time, slew rate, white noise, resolution of the sensors. We confirmed that the $600{\AA}$ thin film at $250^{\circ}C$ formed crystalized magnetic anisotropy spontaneously and the sensor using the thin film had capability of detecting magnetic field with sensitivity of 230 nT. In these devices, the magnetoresistance change was increased linearly in ${\pm}10$ Oe range, and the magnetoresistance effect was increased when the ratio between line width and length was increased. When the devices was soldered using indium, the temperature-resistivity coefficient showed $8{\times}10^{-3}/deg$ and increased during the specific properties as magnetic field sensor were weakened. In this studies, the coercive forces of the films were about 5.1 A/cm and saturated magnetizations were 0.64 T, and the delay time in these devises was $5{\mu}s$ and slew rate showed 0.39 $Oe/{\mu}s$ and white noise was -120 dB.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.471-478
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• 2010

Thin films play an important role in many technological applications including microelectronic devices, magnetic storage media, MEMS and surface coatings. It is well known that a thin film's material properties can be very different from the corresponding bulk properties and thus there has been a strong need for the development of a reliable test method to measure the mechanical properties of a thin film. We have developed an alternative and convenient test method to overcome the limitations of previous membrane deflection experiment and uniaxial tensile test by adopting a white light interferometer having sub-nanometer out-of-plane displacement resolution. The freestanding aluminium specimens are tested to verity the effectiveness of the test method developed and get the tensile properties. The specimens are 0.5 rum wide, $1{\mu}m$ thick and fabricated through MEMS processes including sputtering. 1 to 5 specimens are fabricated on Si dies. The membrane deflection experiments are carried out by using a homemade tester consisted of a motor-driven loading tip, a load cell, and 6 DOF alignment stages. The test system is compact enough to set it up beneath a commercial white light interferometric microscope. The white light fringes are utilized to align a specimen with the tester. The Young's modulus and yield point stress of the aluminium film are 62 GPa and 247 MPa, respectively.

• Korean Journal of Food Science and Technology
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• v.49 no.4
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• pp.444-452
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• 2017

This study aims to investigate the physicochemical properties of the extruded rice snack with added the containing mealworm. Adding the mealworm addition enhanced protein and unsaturated fatty acid contents, which are insufficient in rice. As the extrusion process variables, the death temperatures and moisture content were set to at respective 130 and $140^{\circ}C$, and 20 and 25%, respectively. The expansion ratio increased as with death temperature, whereas the increased moisture content decreased. The nitrogen solubility index and protein digestibility index increased with the added mealworm content of mealworm increased. As mealworm content and death temperature, and moisture content increased, DPPH radical scavenging activity significantly increased but the rancidity decreased. As the result of this study, confirmed that the addition of mealworm to the extruded rice snack was the confirmed as the effective process to improve nutrition, and antioxidation. Also, death temperature and moisture content have an effect on softened the texture of extruded rice snack.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.1
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• pp.85-93
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• 2015

Previous studies have estimated crash prediction models with the fixed effect model which assumes the fixed value of coefficients without considering characteristics of each intersections. However the fixed effect model would estimate under estimation of the standard error resulted in over estimation of t-value. In order to overcome these shortcomings, the random effect model can be used with considering heterogeneity of AADT, geometric information and unobserved factors. In this study, data collections from 89 intersections in Daejeon and estimates of crash prediction models were conducted using the random and fixed effect negative binomial regression model for comparison and analysis of two models. As a result of model estimates, AADT, speed limits, number of lanes, exclusive right turn pockets and front traffic signal were found to be significant. For comparing statistical significance of two models, the random effect model could be better statistical significance with -1537.802 of log-likelihood at convergence comparing with -1691.327 for the fixed effect model. Also likelihood ration value was computed as 0.279 for the random effect model and 0.207 for the fixed effect model. This mean that the random effect model can be improved for statistical significance of models comparing with the fixed effect model.

• Journal of Mushroom
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• v.20 no.4
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• pp.241-248
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• 2022

To elucidate how cultivation temperature affected various traits including pileus color, yield and morphology of Pleurotusspp. Main results were as follows. Pileus lightness of all cultivars of Pleurotustested became higher as cultivation temperature increased, while those of Santari, Hwang-geumsantari and Sunjung at 21℃ were lower than at 18℃. Redness and yellowness of pileus decreased as cultivation temperature increased; those of chromatic pileus cultivars showed noticeable difference. Yellowness of cultivar with chromatic pileus was higher than that of cultivar with achromatic pileus. Yield was increased as cultivation temperature increased, Wonhyeung 1ho; low temperature favored cultivar showed high yield when it was cultivated at low temperature andno fruiting body at 21℃. Valid number of stipes were generally higher at 18℃, and its correlation coefficient with yield was low. Length and stipe thickness changed consistently (larger and thicker) upon cultivation temperature; the coefficient of determination(R²) 0.514 for lengthof Heuktari and 0.963for stipe thickness of Santari were high. Correlation coefficient of one trait was highly related with multiple traits. In the future, we will conduct research on the changes of expressed genes involved in the pigments for pileus color by RNA expression analysis.