• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1362-1369
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• 2018

A method aimed at improving the beam-wave interaction efficiency by changing the coupling slot configuration has been proposed in the study of extended interaction oscillators (EIOs). The dispersion characteristics, coupling coefficient and interaction impedance of the high-frequency structure based on different types of coupling slots have been investigated. Four types of coupled cavity structures with different layouts of the coupling slots have been compared to improve the beam-wave interaction efficiency, so as to analyze the beam-wave interaction and practical applications. In order to determine the improvement of the coupling slot to a coupled cavity circuit in an EIO, we designed four nine-gap EIOs based on the coupled cavity structure with different coupling slot configurations. With different operating frequencies and voltages takes into consideration, beam voltages from 27 to 33 kV have been simulated to achieve the best beam-wave interaction efficiency so that the EIOs are able to work in the $2{\pi}$ mode. The influence of the Rb and the ds on the output power is also taken into consideration. The Rb is the radius of the electron beam, and the ds is the width of the coupling slot. The simulation results indicate that a single-slot-type EIO has the best beam-wave interaction efficiency. Its maximum output power is 2.8 kW and the efficiency is 18% when the operating voltage is 31 kV and electric current is 0.5 A. The output powers of these four EIOs that were designed for comparison are not less than 1.7 kW. The improved coupling-slot configurations enables the extended interaction oscillator to meet the different engineering requirements better.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.587-592
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• 2021

Change in the cortical thickness of long bones occurring with aging and osteoporosis is known to be a risk factor for fracture. The present study aims to investigate the dependencies of phase velocities of ultrasonic guided waves on the cortical thickness in 7 soft tissue-bone mimicking phantoms consisting of acrylic plates covered by a 2 mm-thick silicone rubber layer by using the axial transmission technique with a pair of transducers with a center frequency of 200 kHz and a diameter of 12.7 mm. Two distinct propagating waves with different velocities, the First Arriving Signal (FAS) and the Slow Guided Waved (SGW), were consistently observed for all the soft tissue-bone mimicking phantoms. The FAS velocity decreased slightly with increasing thickness, whereas the SGW velocity increased strongly with increasing thickness. The FAS and the SGW velocities were found to be closely consistent with the S0 and the A0 Lamb mode velocities for a free acrylic plate, respectively, suggesting that the presence of the soft tissue mimicking material (2 mm-thick silicone rubber layer) covering the acrylic plates does not influence significantly the velocity measurements.

• Steel and Composite Structures
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• v.48 no.2
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• pp.207-233
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• 2023

Steel-concrete composite box girder bridges are widely used in the construction of highway and railway bridges both domestically and abroad due to their advantages of being light weight and having a large spanning ability and very large torsional rigidity. Composite box girder bridges exhibit the effects of shear lag, restrained torsion, distortion and interface bidirectional slip under various loads during operation. As one of the most commonly used calculation tools in bridge engineering analysis, one-dimensional models offer the advantages of high calculation efficiency and strong stability. Currently, research on the one-dimensional model of composite beams mainly focuses on simulating interface longitudinal slip and the shear lag effect. There are relatively few studies on the one-dimensional model which can consider the effects of restrained torsion, distortion and interface transverse slip. Additionally, there are few studies on vehicle-bridge integrated systems where a one-dimensional model is used as a tool that only considers the calculations of natural frequency, mode and moving load conditions to study the dynamic response of composite beams. Some scholars have established a dynamic analysis model of a coupled composite beam bridge-train system, but where the composite beam is only simulated using a Euler beam or Timoshenko beam. As a result, it is impossible to comprehensively consider multiple complex force effects, such as shear lag, restrained torsion, distortion and interface bidirectional slip of composite beams. In this paper, a 27 DOF vehicle rigid body model is used to simulate train operation. A two-node 26 DOF finite beam element with composed box beams considering the effects of shear lag, restrained torsion, distortion and interface bidirectional slip is proposed. The dynamic analysis model of the coupled composite box girder bridge-train system is constructed based on the wheel-rail contact relationship of vertical close-fitting and lateral linear creeping slip. Furthermore, the accuracy of the dynamic analysis model is verified via the measured dynamic response data of a practical composite box girder bridge. Finally, the dynamic analysis model is applied in order to study the influence of various mechanical effects on the dynamic performance of the vehicle-bridge system.

• The Journal of the Acoustical Society of Korea
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• v.25 no.1
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• pp.21-29
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• 2006

In this Paper a split bandwidth wideband speech coder and its highband coding method are Proposed. The coder uses a split-band approach. where the wideband input speech signal is split into two equal frequency bands from 0-4kHz and 4-8kHz. The lowband and the highband are coded respectively by the 11.8kb/s G.729 Annex E and the proposed coding method. After the LPC analysis, the highband is divided by two modes according to the properties of signals. In stationary mode. the highband signals are compressed by the mixture excitation model; CELP algorithm and W (Matching Pursuit) algorithm. The others are coded by the only CELP algorithm. We compare the performance of the new wideband speech coder with that of G.722 48kbps SB-ADPCM and G.722.2 12.85kbps in a subjective method. The simulation results show that the Performance of the proposed wideband speech coder has better than that of 48kbps G.722 and no better than that of 12.85kbps G.722.2.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.3
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• pp.258-268
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• 2024

We presented foundational findings regarding the occurrence and acoustic characteristics of the finless porpoise through passive acoustic and visual surveys conducted on the southern coast of Korea, specifically at Hadong Jungpyeong Port. Over a survey period spanning from July 8 to August 16, 2023, totaling 40 days, we observed peaks in the number of clicks produced by this species on July 15, July 24, August 4, August 11, and August 16. The highest count, totaling 18,924 clicks, was recorded on July 15th, while the lowest count, at 3,888 clicks, occurred on August 8th. Examining the acoustic characteristics throughout the diurnal cycle, we found that the peak activity in terms of DPM (detection positive minute for one hour), DP10M (DPM for ten minutes), and overall number of click sounds was observed between 05:00 and 08:00, with a secondary peak occurring from 17:00 to 18:00. The quietest period was noted between 23:00 and 02:00. Furthermore, there was a significant increase in the number of clicks from sunrise, with the maximum count of 21,581 clicks recorded at 6 AM. This count gradually decreased until noon, experienced a slight increase thereafter, peaked again at sunset, and then declined. The dominant frequency mode of this species was 126 kHz, with a concentration ranging from 112 to 136 kHz. The average duration of a click sound was 127 ㎲, with approximately 16 sinusoids (cycles) within each click sound and an average cycle length of approximately 7.9 ㎲. These findings from our study are anticipated to serve as foundational data for the development of a Korean pinger and acoustic warning system.

• Journal of dental hygiene science
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• v.12 no.4
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• pp.348-358
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• 2012

This study aims to prepare the basic data of the teeth color by measuring analyze mode using the color of the maxillary anterior teeth (maxillary central incisor, lateral incisor, canine) of the college students in their twenties as the dental colorimeter. The maxillary anterior teeth of the subjects of study as 467 students (male 89, female 378) were measured from 14 November to 2 December, 2011, so the color of total 1,401 teeth was examined, and oral health and eating habit attributes were researched. The survey results were as follows. 1. The color of maxillary anterior teeth was changed from maxillary central incisor to maxillary canine, brightness ($L^*$) was decreased $76.79{\pm}4.86$ to $69.72{\pm}4.62$, red chroma ($a^*$) was increased $2.02{\pm}2.00$ to $4.10{\pm}2.60$, yellow chroma ($b^*$) was increased $15.51{\pm}3.42$ to $20.10{\pm}3.46$. 2. Brightness ($L^*$) was different according to sex (p< 0.001), major (p<0.001), grade (p<0.001), smoking (p<0.001), oral health education (p<0.01), daily brushing frequency (p<0.001), brushing method (p<0.05), oral hygiene devices (p<0.001), and red chroma ($a^*$) to major (p<0.001), daily brushing frequency (p<0.05), brushing time after meals (p<0.01), oral hygiene devices (p<0.01), and yellow chroma ($b^*$) to brushing time after meals (p<0.01), subjective tooth color (p<0.001). 3. Brightness ($L^*$) of eating habit attributes was different according to coke, candy ($R^2=0.053$, p<0.05). In conclusion, this study demonstrates that the color of maxillary anterior teeth has differences in brightness ($L^*$), red chroma ($a^*$), yellow chroma ($b^*$) from each tooth, also these showed various tendency according to the oral health and eating habit attributes.

• Tuberculosis and Respiratory Diseases
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• v.43 no.5
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• pp.683-692
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• 1996

Background: Although most of the patients with tuberculous pleural effusions completely reabsorbed their effusions and became asymptomatic within 2 to 4 months, later surgical procedures such as decortication is needed in some patients because of dyspnea caused by pleural loculations and thickening despite anti-tuberculous chemotherapy. It is obligatory to secure adequate drainage to prevent the development of complications. But, the best methods for treating loculated tuberculous pleural effusions remain debatable. Recent several reports revealed that intrapleural instillation of fibrinolytic agents is an effective adjunct in the management of complicated empyema and may reduce the need of surgery. Purpose : The effects of catheterization with intrapleural urokinase instillation were prospectively evaluated in the patients with septated tuberculous pleural effusion, and compared with other therapeutic effects of different modalities of therapy such as repeated thoracentesis and small-bored catheterization. Methods : Forty-eight patients diagnosed with tuberculous pleurisy were randomly separated into three groups; control group(n=13), catheter group(n=12), urokinase group(n=22). In urokinase group, dose of 100.000U urokinase was instilled into the pleural cavity via a percutaneous drainage catheter for complete drainage or total dose of 700,000U of urokinase. After two hours clamping, the catheter was opened and intermittently irrigated. The early and late effectiveness of therapies was assessed by radiographically and by measuring the volume of fluid drained from the catheter. Results : There was statistically significantly better result in the urokinase group in respect of frequency of catheterization, frequency of catheter obstruction and the duration of catheterization in early effectiveness(p < 0.05). There were no difference in radiologic improvement of follow-up in later phase chest X-ray between urokinase group and catheter group in later phase(p > 0.05). But there were more failure rates in control group especially honeycomb septa in pleural effusion sonographically than former two groups. And there were no complications of urokinase such as fever or hemorrhage. Conclusion : In the treatment of septated tuberculous pleurisy, there were better results in urokinase than those of catheterization alone in early effectiveness. And there was no difference in radiographic improvement between urokinase group and catheter group. Intrapleural instillation of urokinase is an effective and safe mode of treatment for septated tuberculous pleural effusions and alleviates the need for thoracotomy.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.21-31
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• 2010

This paper presents a design of PLL and SSCG for reducing the EMI effect at the electronic machinery and tools for DisplayPort application. This system is composed of the essential element of PLL and Charge-Pump2 and Reference Clock Divider to implement the SSCG operation. In this paper, 270MHz/162MHz dual-mode PLL that can provide 10-phase and 1.35GHz/810MHz PLL that can reduce the jitter are designed for 2.7Gbps/162Gbps DisplayPort application. The jitter can be reduced drastically by combining 270MHz/162MHz PLL with 2-stage 5 to 1 serializer and 1.35GHz PLL with 2 to 1 serializer. This paper propose the frequency divider topology which can share the divider between modes and guarantee the 50% duty ratio. And, the output current mismatch can be reduced by using the proposed charge-pump topology. It is implemented using 0.13 um CMOS process and die areas of 270MHz/162MHz PLL and 1.35GHz/810MHz PLL are $650um\;{\times}\;500um$ and $600um\;{\times}\;500um$, respectively. The VCO tuning range of 270 MHz/162 MHz PLL is 330 MHz and the phase noise is -114 dBc/Hz at 1 MHz offset. The measured SSCG down spread amplitude is 0.5% and modulation frequency is 31kHz. The total power consumption is 48mW.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.11 no.1
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• pp.251-268
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• 1998

125 Cases of Acne were treated by Acupuncture and Herb-med treatment during a three months duration from April 1996 to February 1998 in Kyung Hee Univ. Department of Ophthal, Otolaryngology. College of Oriental Medicine. We have observed the cases and the results as follows: 1. The age of average was 24.55 age : 21.91 in males, 24.55 in females. and in these, the gulf between males and females were showed statically significant diference. In the age of onset, averag was 16.96 age and mode was 18 age and male's average was 16.96 age, minimun was 11 age, maximum 40 age and female's average was 20.14 age, minimun was 10 age, maximum 40 age. and these were showed statically significant diference between males and females. 2. In the distribution of season, winter was the most with $37.8\%$ of out patients, the rest was similar to difference of each other. but there was clear difference between males and females. 3. In the duration of history, the average was 5.10 years and male's average was 5.13 years. on the other hand female's was 5.09 years but there is no any significant difference have a resemblance with each other. 4. In blood type, O type was the most with $35.20\%$ and there was in the order of A type was $26.40\%\;B\;type\;was\;23.20\%,\;AB\;type\;was\;15.20\%$ but these were not significant difference by the chi-tend and analysis of variance with total cases, males and females. 5. In select of the preference food, patients of the prefer worm food was $42.40\%\;and\;cool\;food\;was\;38.40\%,\;tepid\;food\;was\;24\%$ but these were no significant difference by the chi-test and ANOVA of each other. 6. the state of pulse classified into 11 type and average was 7.2 times, maximum was 29 times with Hyun Sae, at the same time, the female's average was 6.73 times, maximum was 27 times and male's average was 1.5 times. The result of test with each other, these were showed statically significant difference as compared total cases with males but there were not females ones. 7. In the frequency of the major cause, oversensitiveness was the most with $34.93\%$. secondly there was in order of indigestion $30.82\%$ and menstrual irregularity and menstruation pain $23.28\%$. constipation $10.96\%$ and these showed statically significant difference as compared the females with males on the result of test for difference with each other. 8. In frequency of the symptoms, itching was the most with $31.97\%$ and there was in order of nodule $20.49\%$, pustule $18.85\%,\;papule\;15.58\%,\;flare\;13.12\%$ and also these showed statically significant difference as compared the females with males 9. for the Distribution of acne region, face was the most with $64.06\%$ and there was in order of back $14.29\%,\;upper-chest\;11.69\%,\;neck\;7.79\%$ and there was no significant difference as compared total cases with males and females. 10. Acne applied 30 prescription to 4 weeks and over and 20 weeks and over was $23.3\%$, 30 weeks and over was $16.67\%$ and average of administration duration were 4.2 weeks(male's average 5.78, maximum 96 weeks and female's average 3.85, maximum 23 weeks) maximum was 96 weeks, minimum was 1 week. 11. In the acupuncture treatment, $96.6\%$ applied to acupuncture and average was 5.44 times, maximum 46 times, minimum 1 time(male's average 4.64, female's 5.62) but these were not any significant differeence. 12. for the medication, author made a investigation and comparison between control group with treated group in order to observe for the therapeutic effect during the 1 month and 2, 3. From these results, we can see that acne was improved by the oriental treatment. in the 1 month, average of control group was 13.24 and treated group was 11.78. these showed statically significant decrease in P<0.02 as compared the treated group with control group. In the 2 months, average of control group was 13.43 and treated group was 9.03. these showed statically significant decrease in P<0.003 as compared the treated group with control group. In the 3 months, average of control group was 13.78 and treated group was 8.06. these showed statically significant decrease in P<0.008 as compared the treated group with control group.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.1
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• pp.28-39
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• 2019

In the design process of counter measures against the beach erosion, information like the main sediment transport mode and yearly net amount of longshore and cross shore transport is of great engineering value. In this rationale, we numerically analyzed the yearly sediment budget of the Mang-Bang beach which is suffering from erosion problem. For the case of cross sediment transport, Bailard's model (1981) having its roots on the Bagnold's energy model (1963) is utilized. In doing so, longshore sediment transport rate is estimated based on the assumption that longshore transport rate is determined by the available wave energy influx toward the beach. Velocity moments required for the application of Bailard's model (1981) is deduced from numerical simulation of the nonlinear shoaling process over the Mang-Bang beach of the 71 wave conditions carefully chosen from the wave records. As a wave driver, we used the consistent frequency Boussinesq Eq. by Frelich and Guza (1984). Numerical results show that contrary to the Bailard's study (1981), Irribaren NO. has non negligible influence on the velocity moments. We also proceeds to numerically simulate the yearly sediment budget of Mang-Bang beach. Numerical results show that for ${\beta}=41.6^{\circ}$, the mean orientation of Mang-Bang beach, north-westwardly moving longshore sediment is prevailing over the south-eastwardly moving sediment, the yearly amount of which is simulated to reach its maxima at $125,000m^3/m$. And the null pint where north-westwardly moving longshore sediment is balanced by the south-eastwardly moving longshore sediment is located at ${\beta}=47^{\circ}$. For the case of cross shore sediment, the sediment is gradually moving toward the shore from the April to mid October, whereas these trends are reversed by sporadically occurring energetic wind waves at the end of October and March. We also complete the littoral drift rose of the Mang-Bang beach, which shows that even though the shore line is temporarily retreated, and as a result, the orientation of Mang-Bang beach is larger than the orientation of null pont, south-eastwardly moving longshore sediment is prevailing. In a case that the orientation of Mang-Bang beach is smaller than the orientation of null pont, north-westwardly moving longshore sediment is prevailing. And these trend imply that the Mang-Bang beach is stable one, which has the self restoring capability once exposed to erosion.