• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.245-251
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• 2005

When we design coastal and harbol facilities deepwater design wave and wind speed are the important design parameters. Especially, the analysis of these informations is a vital step for the point of disaster prevention. In this study, we made and an extreme value analysis using a series of deep water significant wave data arranged in the 16 direction and supplied by KORDI real-time wave information system ,and the wind data gained from Wan-Do whether Station 1978-2003. The probability distributions considered in this characteristic analysis were the Weibull, the Gumbel, the Log-Pearson Type III, the Normal, the Lognormal, and the Gamma distribution. The parameter for each distribution was estimated by three methods, i.e. the method of moments, the maximum likelihood, and the method of probability weight moments. Furthermore, probability distributions for the extreme data had been selected by using Chi-square and Kolmogorov-Smirnov test within significant level of 5%, i,e. 95% reliance level. From this study we found that Gumbel distribution is the most proper model for the deep water design wave height off the southwest coast of Korea. However the result shows that the proper distribution made for the selected site is varied in each extreme data set.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.59-65
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• 2004

A stable reference voltage generator is necessary to the infrared image signal readout circuit(ROIC) to improve noise characteristics of signal originated from infrared devices, that is, to gain good images. In this paper, bandgap circuit operating at cryogenic temperature of 77K for Infrared image ROIC(readout integrated circuit) was first made. It demonstrates practical use possibility through taking measurements and estimations. Bandgap circuit is a representative voltage reference circuit. Most of bandgap reference circuits which are presented so far operate at room temperature, and their characteristic are not suitable for infrared image ROIC operating at liquid nitrogen temperature, 77K. To design bandgap circuit operating at cryogenic temperature, suitable circuit is selected and the parameter characteristics of used devices as temperature change are seen by a theoretical study and fitted at liquid temperature with considering such characteristics. This circuit has been fabricated in the Hynix 0.6um standard CMOS process, and the output voltage measured shows that the stability is 1.042±0.0015V over the temperature range of 60K to 110K and is better than bandgap circuits operated at room temperature.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.466-473
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• 2013

In this paper, a compact planar multi-loop self-resonant coil of high quality factor with a coaxial cross section is proposed for effective wireless charging. The proposed coil has high Q-factor and a resonant frequency of a coil can be easily controlled by adjusting distributed capacitance. For designing the coil, a self-inductance and a distributed capacitance are calculated theoretically. The self-inductance is calculated from the sum of the mutual energies between small circular loops that are made by dividing the cross section of the coil. To verify its properties and calculation results, the self-resonant coils are fabricated by using a coaxial cable with characteristic impedance of $50{\Omega}$. The measured frequencies are very consistent with the calculated ones. In addition, the resonant frequency can be adjusted slightly by the tuning parameter ${\gamma}$. The resonant coils are applied to a tablet PC, the Q-factors of the Tx and Rx resonant coils are 282 and 135, respectively. As a result of measurement when height between the two resonant coils is 4.4 cm, the power transfer efficiency is more than 80 % within a radius of 5 cm.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.188-198
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• 2013

Maximally flat (MAXFLAT) half-band filters usually have wider transition band than other filters. This is due to the fact that the maximum possible number of zeros at $z={\pm}1$ is imposed, which leaves no degree of freedom, and thus no independent parameters for direct control of the frequency response. This paper describes a novel method for the design of FIR halfband filters with an explicit control of the transition-band width. The proposed method is based on a generalized Lagrange halfband polynomial (g-LHBP) with coefficients parametizing a 0-th coefficient $h_0$, and allows the frequency response of this filter type to be controllable by adjusting $h_0$. Then, $h_0$ is modeled as a steepness parameter of the transition band and this is accomplished through theoretically analyzing a polynomial recurrence relation of the g-LHBP. This method also provides explicit formulas for direct computation of design parameters related to choosing a desired filter characteristic (by trade-off between the transition-band sharpness and passband & stopband flatness). The examples are shown to provide a complete and accurate solution for the design of such filters with relatively sharper transition-band steepness than MAXFLAT half-band filters.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.1
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• pp.15-24
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• 2012

In this paper, we suggest the dynamic-response-free SMPS using a new high-resolution DPWM generator based on switched-capacitor delay technique. In the proposed system, duty ratio of DPWM is controlled by voltage slope of an internal capacitor using switched-capacitor delay technique. In the proposed circuit, it is possible to track output voltage by controlling current of the internal capacitor of the DPWM generator through comparison between the feedback voltage and the reference voltage. Therefore the proposed circuit is not restricted by the dynamic-response characteristic which is a problem in the existing SMPS using the closed-loop control method. In addition, it has great advantage that ringing phenomenon due to overshoot/undershoot does not appear on output voltage. The proposed circuit can operate at switching frequencies of 1MHz~10MHz using internal operating frequency of 100 MHz. The maximum current of the core circuit is 2.7 mA and the total current of the entire circuit including output buffer is 15 mA at the switching frequency of 10 MHz. The proposed circuit has DPWM duty ratio resolution of 0.125 %. It can accommodate load current up to 1 A. The maximum ripple of output voltage is 8 mV. To verify operation of the proposed circuit, we carried out simulation with Dongbu Hitek BCD $0.35{\mu}m$ technology parameter.

• Clean Technology
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• v.23 no.4
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• pp.364-377
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• 2017

In this study, to improve the low surface area of domestic anthracite as raw materials of activated carbon, characteristics on chemical activation and VOCs adsorption of activated carbon according to mixing ratio of anthracite and lignite. For these, properties of raw materials, parameter characteristics of preparation processes for activated carbon, and VOCs adsorption characteristic of the prepared activated carbon are analyzed. The experimental results showed that, the domestic anthracite had disadvantages of high contents for ash and lead, arsenic, which were exceeded for the heavy metal limits, in the properties of raw materials. To improve these diadvantages, using the mixing ratio of anthracite and lignite, and the optimum conditions for pretreatment, activation, washing, and pellitization process, the activated carbon had a range of BET (Brunauer-Emmett-Teller) surface area of $1,154{\sim}1,420m^2g^{-1}$ with mesopore development and hydrophobic surface property. The carbons were satisfied with the quality standard for granular activated carbon, and had similar physicochemical properties with the commercial activated carbon. The minimum mixing condition for commercial VOCs activated carbon performance must have the caloric value of above $5,640kcal\;kg^{-1}$, and the carbon had higher adsorption capacity with order of xylene > toluene > benzene according to more higher molcular weight and hydrophobic property.

• Journal of Trauma and Injury
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• v.19 no.1
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• pp.67-73
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• 2006

Purpose: The arterial base deficit (BD) has proven to be useful in the evaluation and management of trauma patients. Indicators such as the Triage-Revised Trauma Score (t-RTS) and the systemic inflammatory response syndrome (SIRS) score have been used as triage tools for emergency trauma patients in Korea. The purpose of this study was to assess the usefulness of the initial BD in predicting injury severity and outcome in the trauma population. Methods: The medical records of 308 consecutive trauma patients admitted to the Emergency Center of Masan Samsung Hospital from January 2004 to December 2004 were carefully examined prospectively and retrospectively, and 291 patients were selected as subjects for this research. The SIRS score and the t-RTS were calculated based on the records from the emergency department, and the BD was calculated based on the arterial blood gas analysis obtained within 30 minutes of admission. The efficiency of the three indicators as triage tools was evaluated by using cross tabulations in two - by - two matrices and by using a receiver operating characteristic (ROC) curve analysis. Results: When the mortality was used as the outcome parameter, the sensitivity and the accuracy of the initial BD were higher than those of the SIRS score (p<0.05) and were same as those of the t-RTS. The areas under the ROC curves of the initial BD, the SIRS score, and the t-RTS were $0.740{\pm}0.087$, $0.696{\pm}0.082$, and $0.871{\pm}0.072$, respectively (95% confidence interval). When emergency operation and blood transfusion requirements were used as outcome parameters, the comparisons of the sensitivities and the accuracies of the initial BD and the other two indicators showed the same pattern as mentioned above. The areas under the ROC curves of the initial BD were 0.7~0.8 and were larger than those of the SIRS score (p<0.05). Conclusion: The ability of the initial BD to predict injury severity and outcome was similar to those of the t-RTS and the SIRS score. Therefore, the authors suggest that the initial BD may be used as an alternative to previous triage tools for trauma patients.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.93-107
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• 2013

Thermal conduction of the particulate composites or granular materials can be widely used in porous materials and geotechnical engineering. And it has continued to develop "effective thermal conductivity" of medium by modeling energy relationship among particles in medium. This study focuses on the development of the effective thermal conductivity at the unsaturated conditions of soils using the modified network model approach assisted by synthetic 3D random packed systems (DEM method, Discrete Element Method) at the particle scale. To verify the network model, three kinds of glass beads and the Jumunjin sand are used to obtain experimental values at various unsaturated conditions. The PPE (Pressure Plate Extractor) test is then performed to obtain SWCC (Soil-Water Characteristic Curve) of soil samples. In the modified network model, SWCC is used to adjust the equivalent radius of thermal cylinder at contact area between particles. And cutoff range parameter to define the effective zone is also adjusted according to the SWCC at given conditions. From a series of laboratory tests and the proposed network model, the modified network model which adopts a SWCC shows a good agreement in modeling thermal conductivity of granular soils at given conditions. And an empirical correlation between the fraction of the mean radius (${\chi}$) and thermal conductivity at given saturated condition is provided, which can be used to expect thermal conductivity of the granular soils, to estimate thermal conductivity of granular soils.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5355-5358
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• 2014

Background: To assess the role of sonographic endometrial thickness and hysteroscopic polyp size in predicting premalignant and malignant polyps in postmenopausal women. Materials and Methods: A total of 328 postmenopausal women with abnormal uterine bleeding and thickened endometrium underwent operative hysteroscopy due to detection of endometrial polyps were included in this retrospective study. Preoperative endometrial thickness measured by transvaginal ultrasonography and polyp size on hysteroscopy were noted. Hysteroscopic resection with histology was performed for endometrial polyps. Endometrial thickness and polyp size were evaluated on the basis of final diagnosis established by histologic examination. Receiver operator characteristic curves were calculated to assess the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of endometrial thickness and polyp size for detecting pemalignant and malignant polyps. Results: Premalignant and malignant polyps were identified in 26 (7.9%) of cases. Sonographic measurement showed a greater endometrial thickness in cases of premalignant and malignant polyps when compared to benign polyps. On surgical hysteroscopy, premalignant and malignant polyps were also larger. Endometrial thickness demonstrated a sensitivity of 53.8%, specificity of 85.8%, PPV of 24.6% and NPV of 95.6% at a cut-off limit of 11.5 mm with diagnostic accuracy of 83.2%. Polyp size has a diagnostic accuracy of 94.8% with a sensitivity of 92.3%, specificity of 95.0%, PPV of 61.5% and NPV of 99.3% at a cut-off point of 19.5mm. Conclusions: Endometrial thickness measured by transvaginal ultrasonography is not sufficient in predicting premalignant and malignant endometrial polyps in postmenopausal women with abnormal uterine bleeding and thickened endometrium. Polyp size on hysteroscopy is a more accurate parameter, because of better sensitivity and specificity. However, while polyp size ${\geq}19.5mm$ seems to have a great accuracy for predicting premalignancy and malignancy, histologic evaluation is still necessary to exclude premalignant and malignant polyps.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.45-51
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• 2015

In this paper, we study the RF characteristics of the short wavelength thin-film transmission line employing microstrip line (ML)/coplanar waveguide (CPW) composite structure on silicon substrate for application to RFIC (radio frequency integrated circuit). The thin-film transmission line employing ML/CPW composite structure showed a wavelength shorter than conventional transmission lines. Concretely, at 10 GHz, the wavelength of the transmission line employing ML/CPW composite structure was 6.26 mm, which was 60.5 % of the conventional coplanar waveguide. We also extracted the bandwidth characteristic of the transmission line employing ML/CPW composite structure using equivalent circuit analysis. The S parameter of the equivalent circuit showed a good agreement with measured result. According to the bandwidth extraction result, the cut-off frequency of thin-film transmission line employing ML/CPW composite structure was 377 GHz. Above results indicate that the transmission line employing ML/CPW composite structure can be effectively used for application to broadband and compact RFIC.