• Journal of Pharmaceutical Investigation
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• v.31 no.4
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• pp.233-239
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• 2001

Local drug delivery by using biocompatible polymers has been developed in the treatment of periodontitis for many years. In the field of dental therapy, doxycycline is usually a first choice because of its broad-spectrum antibiotic activity. The strip releases antibiotics for a week, and the polymer should be degradable after a week. In this study, we prepared and evaluated the chitosan strips and nanoparticle strips containing doxycycline hydrochloride, and studied their antiacterial activity, dissoultion, and degrability in vitro. The weight of cast strip containing a 5 mg of doxycycline hydrochloride and a 45 mg of chitosan polymer was $57.67{\pm}0.17\;mg$. The release rate of doxycycline hydrochloride from the strip was measured by HPLC. The drug released from chitosan strip and nanoparticle strip was shown to be $50\;{\mu}g/mL$ in first 24 hours. In antibacterial test showed growth inhibitory activity after 24 hrs anaerobic incubation. In vitro degradability showed demolished weight of $93.74{\pm}0.08%$ chitosan strip, $82.48{\pm}1.29%$ chitosan nanoparticle strip, $2.47{\pm}1.99%$ polycarprolactione strip (control). These results showed that, with this doxycycline hydrochloride strip, it is feasible to obtain a sustained release of the drug within the periodontal pocket for seven days which may be improve for local drug delivery system for treatment of periodontal disease.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.174-180
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• 2012

In this study, the feasibility of spectral domain optical Doppler tomography for measuring blood flow characteristics in a micro-tube was demonstrated through several experiments. The use of an SD-ODT system in blood flow measurement can provide high resolution images (5 microns resolution). We prepared three capillary tubes to reveal the effect of different concentrations of hematocrit ratio (HR). One tube serves as the control. The two other tubes contained different concentrations of HR (5%, 25%). Three different capillary tube inlet flow velocities were tested in the present study. The Reynolds number (Re) which is based on the capillary tube inner diameter ranges from Re=6 to 48. We calculated a Doppler shift of the power spectrum of the temporal interference fringes with Kasai autocorrelation function to achieve the velocity profile of the flow. As a result, SD-ODT systems could not detect the cell depletion layer in the present study due to the limitation of spatial resolution. Nevertheless, these systems were proven to be capable of observing the RBCs of blood.

• Mycobiology
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• v.47 no.3
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• pp.335-339
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• 2019

Endophytic fungi have the ability to live inside the host plant tissues without causing neither symptoms of diseases/or harm. Opportunistic infections are accountable for majority of the outbreaks, thereby putting a burden on the health system. To investigate and characterize the bioactive compounds for the control of bacteria of clinical importance, extracts from endophytic fungi were isolated from indigenous South African medicinal plants. Extracts from endophytic fungi were isolated from 133 fungal strains and screened against Gram positive and negative bacteria namely Bacillus cereus, Escherichia coli, Enterococcus faecium, and E. gallinarum using disk diffusion. Furthermore, gas chromatography-mass spectrometry was performed to identify the bioactive compounds. Sixteen out of one hundred and thirty-three (12%) fungi extracts exhibited antibacterial properties against some of the selected bacteria. E. coli was found to be the most susceptible in contrast to E. faecium and E. gallinarum which were the most resistant. The isolate MHE 68, identified as Alternaria sp. displayed the greater spectrum of antibacterial activities by controlling selected clinical bacteria strains including resistant E. faecium and E. gallinarum. The chemical analysis of the extract from MHE 68 indicated that linoleic acid (9,12-octadecadienoic acid (Z,Z)) and cyclodecasiloxane could be accountable for the antibacterial activity. This is the first study conducted on the secondary metabolites produced by endophytic fungal strains isolated from the Pelargonium sidoides DC. possessing antibacterial properties.

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.256-260
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• 2014

Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers-aluminum (Al), chromium (Cr), and titanium dioxide ($TiO_2$) powder-coated on glass substrates. We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on substrates. The scintillators were observed via scanning electron microscopy (SEM), and scintillation characteristics were evaluated on the basis of the emission spectrum, light output, light response to x-ray dose, modulation transfer function (MTF), and x-ray images. Compared to control films without a reflective layer, CsI:Tl films with reflective layers showed better sensitivity and light collection efficiency, and the film with a $TiO_2$ reflective layer showed the best properties.

• Journal of Korean Society of Forest Science
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• v.81 no.4
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• pp.372-382
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• 1992

Recreation planning is essential activity to meet changing demands and to protect the resources. The recreation opportunity specturm(ROS) system is a principal part of a recreational management planning. In this study, the basic concepts and tenets of the ROS system described and reviewed the feasibility of applying to forest recreation planning to the Korean national forest. In Korea, the forest land as a major recreation place has used without the rational planning process. The control for the laissez-faire use on the forest area, the classification of recreational opportunity settings is the most important process and then it make a useful tool for providing proper recreational opportunity and site development guidance. Opportunity settings classification can help maintain diversity and enhance protection of forest resources. It can also improve the quality of recreational experiences and the management action guidances. GIS technology using the ARC/INFO could be useful in current attempts to identify analysis areas for predictive modeling of forest recreation site planning.

• Journal of IKEEE
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• v.2 no.1 s.2
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• pp.1-14
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• 1998

In this paper, Antenna, LNA, Mixer, VCO, and Modulation/Demodulation in Baseband processor which are the RF main components in Wireless LAN system for ultra high-speed communications network are studied. Antenna bandwidth and selective fading due to multipath can be major obstacles in high speed digital communications. To solve this problem, wide band MSA which has loop-structure magnetic antenna characteristics is designed. Distributed mixer using dual-gate GaAs MESFET can achieve over 10dB LO/RF isolation without hybrid, and minimize circuit size. As linear mixing signal is produced, distortions can be decreased at baseband signals. Conversion gain is achieved by mixing and amplification simultaneously. Mixer is designed to have wide band characteristics using distributed amplifier. In VCO design, Oscillator design method by large signal analysis is used to produce stable signal. Modulation/Demodulation system in baseband processor, DS/SS technique which is robust against noise and interference is used to eliminate the effect of multipath propagation. DQPSK modulation technique with M-sequences for wideband PN spreading signals is adopted because of BER characteristic and high speed digital signal transmission.

• Journal of Sensor Science and Technology
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• v.11 no.2
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• pp.67-76
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• 2002

We have presented a 2-dimensional fluxgate sensor with ferrite core, excitation, and pick-up coil. This fluxgate sensor system consists of a sensing element, driving circuits for excitation coil and signal processing for detecting second harmonic frequency component which is proportional to the DC magnetic to be measured. The sensor core is excited by a square waveform of voltage through the excitation coil of 80 turns. The second harmonic output of pick-up coil(x and y axis: 100 turns) is measured by FFT spectrum analyzer. This result is compared with output of PSD(phase sensitive detector) unit for detecting the second harmonic component. The measured maximum sensitivity is about 1580 V/T at driving frequency of 1.5 kHz and excitation current of 2 App. The nonlinearity of this system is measured about 2.3%(PSD) and about 1%(second harmonics of the pick-up). The angle error of the system is ${\pm}2$ %/FS.

• Smart Structures and Systems
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• v.29 no.4
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• pp.625-640
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• 2022

Maglev rail joints are vital components serving as connections between the adjacent F-type rail sections in maglev guideway. Damage to maglev rail joints such as bolt looseness may result in rough suspension gap fluctuation, failure of suspension control, and even sudden clash between the electromagnets and F-type rail. The condition monitoring of maglev rail joints is therefore highly desirable to maintain safe operation of maglev. In this connection, an online damage detection approach based on three-dimensional (3D) convolutional neural network (CNN) and time-frequency characterization is developed for simultaneous detection of multiple damage of maglev rail joints in this paper. The training and testing data used for condition evaluation of maglev rail joints consist of two months of acceleration recordings, which were acquired in-situ from different rail joints by an integrated online monitoring system during a maglev train running on a test line. Short-time Fourier transform (STFT) method is applied to transform the raw monitoring data into time-frequency spectrograms (TFS). Three CNN architectures, i.e., small-sized CNN (S-CNN), middle-sized CNN (M-CNN), and large-sized CNN (L-CNN), are configured for trial calculation and the M-CNN model with excellent prediction accuracy and high computational efficiency is finally optioned for multiple damage detection of maglev rail joints. Results show that the rail joints in three different conditions (bolt-looseness-caused rail step, misalignment-caused lateral dislocation, and normal condition) are successfully identified by the proposed approach, even when using data collected from rail joints from which no data were used in the CNN training. The capability of the proposed method is further examined by using the data collected after the loosed bolts have been replaced. In addition, by comparison with the results of CNN using frequency spectrum and traditional neural network using TFS, the proposed TFS-CNN framework is proven more accurate and robust for multiple damage detection of maglev rail joints.

• Journal of Animal Environmental Science
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• v.16 no.3
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• pp.227-236
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• 2010

This study was conducted to develop an measuring system and method for fermentation degree of liquid swine manure by visible ray. The constituent changes of liquid swine manure were examined. pH gradually increased with time, but EC gradually decreased. Malodor strength decreased gradually with aeration treatment with time. Control needed more time to decrease malodor strength than aeration treatment. In aeration treatment, there was no germination of seeds (radish, chinese cabbage) up to 6 weeks and germination rate at 15th week was over 50%. However, in control, there was no germination up to end of experiment. Circular chromatography method showed that there was change after 10th week in aeration treatment but there was no change up to end of experiment in control. As a result, the fermentation degree of liquid swine manure would have relations among pH, EC, germination rate, malodor concentration, and reaction of circular chromatography. The simple analytical instrument for liquid swine manure consisted of a tungsten halogen and deuterium lamp for light source, a sample holder, a quartz cell, spectrometer for spectrum analyzer, a malodour measuring device, a software, etc. Results showed that the simple analytical instrument that was developed can approximately predict the fermentation degree of liquid swine manure by visible ray. Generally, the experiment proved that the simple analytical instrument was reliable, feasible and practical for analyzing the fermentation degree of liquid swine manure.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.43-49
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• 2010

Autonomic nervous system (ANS) acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The activity of the ANS has been assessed by means of the heart rate variability (HRV). It has been reported that HRV is dependent on sex, age, body mass index, and smoking, etc. However, the effects of posture and sleep deprivation on HRV have rarely been reported. Objective of our work was to find out which posture is appropriate for stable HRV. We measured the number of sleep deprivation and HRV using power spectrum in six stages for 30 minutes. Increased low frequency (LF) power and high frequency (HF) power indicate enhanced sympathetic and parasympathetic activity, respectively. We determined the LF/HF ratio to minimize individual difference. It was found that sleep deprivation by awakening up subjects was affected by posture, which resulted in changes of LF/HF. Although LF/HF varied with time, it was more stable in sitting than in supine. In conclusion, we recommend sitting posture when measuring HRV because of less sleep deprivation resulting in less variation in LF/HF.