• Current Optics and Photonics
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• v.4 no.5
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• pp.434-440
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• 2020

Based on single-mode rate equations, we present an improved equivalent-circuit model for distributed-feedback (DFB) lasers that accounts for the effects of parasitic parameters and nonradiative recombination. This equivalent-circuit model is composed of a parasitic circuit, an electrical circuit, an optical circuit, and a phase circuit, modeling the circuit equations transformed from the rate equations. The validity of the proposed circuit model is verified by comparing simulation results to measured results. The results show that the slope efficiency and threshold current of the model are 0.22 W/A and 13 mA respectively. It is also shown that increasing bias current results in the increase of the relaxation-oscillation frequency. Moreover, we show that the larger the bias current, the lower the frequency chirp, increasing the possibility of extending the transmission distance of an optical-fiber communication system. The results indicate that the proposed circuit model can accurately predict a DFB laser's static and dynamic characteristics.

• Journal of Sasang Constitutional Medicine
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• v.28 no.2
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• pp.123-131
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• 2016

Objectives We observed what effects of Paced Breathing(PB) in specific respiration rate have on heart rate variability (HRV) according to Sasang Constitution.Methods HRV of 72 healthy participants in sitting position was recorded while they carried out usual breathing, 0.2Hz, 0.1Hz, and 0.05Hz PB each 5 minutes in consecutive order. Five minute of relaxation was permitted between each breathing. Finally, HRV indices were statictically analyzed of 32 participants (SOEUM: 11, SOYANG: 10, TAEEUM: 11) after data out of accord with respiration rate or outliers were excluded.Results and Conclusions According to respiration rates, there was no statistical significance of HRV among Sasang Constitution. Regardless of Sasang Constituion, 0.2Hz PB increased mean heart rate and decreased natural logarithmic low frequency(lnLF) oscillation of HRV without the change of natural logarithmic high frequency(lnHF), while 0.1Hz PB increased lnLF and standard deviation of N-N interval(SDNN), and slightly decreased lnHF without the change of mean heart rate. 0.05 Hz PB also showed the same effect as 0.1Hz PB, but was impracticable.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3771-3776
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• 2010

The dynamics of the $CN^-$-ligated ferric cytochrome c (CytcCN) in $D_2O$ at 283 K following Q-band photoexcitation at 575 nm was observed using femtosecond time-resolved vibrational spectroscopy. The equilibrium vibrational spectrum of the CN stretching mode of CytcCN shows two overlapping bands: one main band (82%) at $2122\;cm^{-1}$ with $23\;cm^{-1}$ full width at half maximum (fwhm) and the other band (18%) at $2116\;cm^{-1}$ with $7\;cm^{-1}$ fwhm. The time-resolved spectra show bleaching of the CN fundamental mode of CytcCN and two absorption features at lower energies. The bleach signal and both absorption features are all formed within the time resolution of the experiment (< 200 fs) and decay with a life time of 1.9 ps. One transient absorption feature, appearing immediately red to the bleach signal, results from the thermal excitation of low-frequency modes of the heme that anharmonically couple to the CN fundamental mode, thereby shifting the CN mode to lower energies. The shift of the CN mode decays with a lifetime of 2 ps, equivalent to the time scale for vibrational cooling of the low-frequency heme modes. The other transient absorption feature, which is 3.3 times weaker than the bleach signal and shifted $27\;cm^{-1}$ toward lower energies, is attributed to the CN mode in an electronically excited state where the CN bond is weakened with a lowered extinction coefficient. These observations suggest that photoexcited CytcCN mainly undergoes ultrafast radiationless relaxation, causing photo-deligation of $CN^-$ from CytcCN highly inefficient. As also observed in $CN^-$-ligated myoglobin, inefficient ligand photodissociation might be a general property of $CN^-$-ligated ferric hemes.

• Physical Therapy Rehabilitation Science
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• v.4 no.1
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• pp.28-31
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• 2015

Objective: Psychomotor imagery has been widely used to improve motor performance and motor learning. Recent research suggests that during visualization, changes occur in neurophysiological networks that make physical practice more effective in configuring functional networks for skillful behaviors. The aim of our pilot study was to determine if there was change and to what extent there was differentiation in modulation in electroencephalography (EEG) frequencies between visualizing a state of rest and a state of exercise performance and to identify the preponderant frequency. Design: Quasi-experimental design uncontrolled before and after study. Methods: EEG brain wave activity was recorded from 0-40 Hz from nine cerebral cortical scalp regions F3, Fz, F4, C3, Cz, C4, P3, POz, and P4 with a wireless telemetric EEG system. The subjects, while sitting on a chair with eyes closed, were asked to visualize themselves in a state of routine rest/relaxation and after a period of time in a state of their routine exercise performance. Results: The gamma frequency, 31-40 Hz, (${\gamma}$) was the predominant wave band in differentiation between visualizing a state of rest versus visualizing a state of exercise performance. Conclusions: We suggest these preliminarily findings show the EEG electrocortical activity for athletes is differentially modulated during visualization of exercise performance in comparison to rest with a predominant ${\gamma}$ wave band frequency observed during the state of exercise. Further controlled experimental studies will be performed to elaborate these observations and delineate the significance to optimization of psychomotor exercise performance.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.2
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• pp.163-170
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• 2024

In the literature, inhalation of cosmetic fragrances, including natural extracts or natural essential oils, has been reported to induce brainwave changes. Angelica gigas (AG) and Cnidium officinale (CO) are widely used in East Asian countries as traditional medicines to improve health, but there have been no previous reports of inhaling their aromas and assessing changes in brain activity through electroencephalogram (EEG) recordings. In this study, the scent of natural herbal extracts such as Artemisia princeps var. orientalis (Compositae), AG, and CO was inhaled and evaluated whether emotional state changes were caused by olfactory stimuli, and brain activity was confirmed through EEG records before and after inhaling the scent of natural herbal extracts in subjects aged 20 to 30. We also used an electrocardiogram (ECG) to record the electrical activity of the heart during fragrance administration. The test results indicated that inhaling the scents of Compositae, AG, and CO extracts, as well as the positive control lavender, significantly increased the relative alpha power and the alpha/beta ratio of brain waves across the brain regions. The ECG recordings indicated that the inhalation of Compositae fragrance significantly decreased the low-frequency/high-frequency ratio, and that the inhalation of traditional herbal extract fragrances resulted in comfort and relaxation.

• The Korean Journal of Pharmacology
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• v.19 no.2
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• pp.25-34
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• 1983

In this isolated study, it was aimed to elucidate the pharmacological properties of non-cholinergic, non-adrenergic inhibitory responses in the longitudinal strips of rabbit portal vein. 1) The portal vein responded inhibitory to electrical field stimulation in a frequency - and calcium-dependent manner after pretreatment with atropine, guanethidine and ergotamine, simultaneously. 2) When exogenous ATP, ADP, adenosine and cyclic AMP were added, respectively, they only showed the relaxations in the higher concentration without mimicing or affecting the inhibitory response induced by the electrical stimulation. The antagonist of purine substances, neither quinine nor isobutyl-methyl xanthine did influence on the relaxation. 3) The inhibitory response was significantly increased in the presence of $1{\mu}g/ml 4-amino-pyrineine (4-AP) which is $K^+-conduction$ blockade, but higher concentration of 4-AP directly decreased the vascular tone. 4) Though repeated application of ATP revealed the inhibitory effect on the relaxation, however, that of adenosine resulted rather increase of the amplitude. 5) After pretreatment with $^3H-adenosine$, $^3H-efflux$ induced by ATP or adenosine was markedly enhanced, but the electrical stimulation caused less $^3H-efflux$. 6) ^3H-efflux by electrical stimulation was not affected by the administration 4-AP, tetrodotoxin and adenosine.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.23 no.1
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• pp.43-47
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• 2012

Background and Objectives : Laryngopharyngeal reflux disease (LPRD) originates from regurgitation of gastric contents to the laryngopharynx, and it is relatively common disease in otolaryngology. Proton-pump inhibitor (PPI) medication is frequently using treatment method in present time, but controversies exist regarding treatment for it. High-resolution manometry (HRM) system is a newly developed device that using 36 channels and pressure topography plotting program, checking the function and status of esophagus. The aim of this study was to evaluate clinical usefulness of HRM in LPRD patients who do not response to PPI medication. Materials and Method : From July 2009 to July 2010, a total of 99 patients who were suspected LPRD according to symptoms (Reflux Symptom Index >13) and laryngoscopic findings (Reflux Finding Score >7) were retrospectively enrolled in this study. Patients were consisted of 31 men and 68 women, the mean age was 51.8 years, the mean BMI was 22.46. Patients have taken PPI medication for 2 months, after medication, they performed HRM. Comparative analysis was performed with results of the difference in symptoms. Results : In 99 patients, 37 patients (37.4%) show not improvement of LPRD symptoms after PPI medication. Among them, 18 patients (48.6%) showed abnormal findings that were classified as Peristaltic dysfunction (38.9%), Diffuse esophageal spasm (11.1%), Relaxation impairment of LES (11.1%), Achalasia (5.6%), Hypotensive LES (11.1%), Relaxation impairment of UES (11.1%), Nutcracker esophagus (5.6%), Decreased resting pressure (5.6%). Other 62 patients (62.6%) show improvement of LPRD symptoms, 23 patients (37.1%) showed abnormal findings. Most common finding was Peristaltic dysfunction (43.4%) More prevalent abnormal findings of HRM were found in patients who revealed no response to PPI medication (48.6% vs. 37.1%), but it does not reach the statistical significance. Conclusion : Although statistical significances is not showed, the difference observed in the frequency of HRM abnormal finding between response and no response for PPI medication. It has been estimated that HRM may be used to determine differential diagnosis in patients with LPRD. Further studies in lager population containing normal controls will be needed to prove clinical usefulness.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.22 no.2
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• pp.151-155
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• 2011

Background and Objectives : Laryngopharyngeal reflux disease (LPRD) originates from regurgitation of gastric contents to the laryngopharynx, and it is relatively common disease in otolaryngology. Proton-pump inhibitor (PPI) medication is frequently using treatment method in present time, but controversies exist regarding treatment for it. High-resolution manometry (HRM) system is a newly developed device that using 36 channels and pressure topography plotting program, checking the function and status of esophagus. The aim of this study was to evaluate clinical usefulness of HRM in LPRD patients who do not response to PPI medication. Subjects and Method : From July 2009 to July 2010, a total of 99 patients who were suspected LPRD according to symptoms (Reflux Symptom Index >13) and laryngoscopic findings (Reflux Finding Score >7) were retrospectively enrolled in this study. Patients were consisted of 31 men and 68 women, the mean age was 51.8 years, the mean BMI was 22.46. Patients have taken PPI medication for 2 months, after medication, they performed HRM. Comparative analysis was performed with results of the difference in symptoms. Results : In 99 patients, 37 patients (37.4%) show not improvement of LPRD symptoms after PPI medication. Among them, 18 patients (48.6%) showed abnormal findings that were classified as Peristaltic dysfunction (38.9%), Diffuse esophageal spasm (11.1%), Relaxation impairment of LES (11.1%), Achalasia (5.6%), Hypotensive LES (11.1%), Relaxation impairment of UES (11.1%), Nutcracker esophagus (5.6%), Decreased resting pressure (5.6%). Other 62 patients (62.6%) show improvement of LPRD symptoms, 23 patients (37.1%) showed abnormal findings. Most common finding was Peristaltic dysfunction (43.4%) More prevalent abnormal findings of HRM were found in patients who revealed no response to PPI medication (48.6% vs. 37.1%), but it does not reach the statistical significance. Conclusion : Although statistical significances is not showed, the difference observed in the frequency of HRM abnormal finding between response and no response for PPI medication. It has been estimated that HRM may be used to determine differential diagnosis in patients with LPRD. Further studies in lager population containing normal controls will be needed to prove clinical usefulness.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.73-82
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• 1998

Purpose : A precise NMR technique for measuring the rate of water exchange and cell membrane permeability across the hepatocyte membrane using liver-specific MR contrast agent is described. Materials and Methods : The rat hepatocytes isolated by perfusion of the livers were used for the NMR measurements. All experiments were performed on an IBM field cycling relaxometer operating from 0.02MHz to 60 MHz proton Larmor frequency. spin-echo pulse sequence was empolyed to measure spin-lattice relaxation time, T1. The continuous distribution analysis of water proton T1 data from rat hepatocytes containing low concentrations of the liver specific contrast agent, Gd-EOB-DTPA, modeled by a general two compartment exchange model. Results : The mean residence time of water molecule inside the hepatocyte was approximately 250 msec. The lower limit for the permeability of the hepatocyte membrane was $(1.3{\pm}0.1){\;}{\times}{\;}10^{-3}cm/sec$. The CONTIN analysis, which seeks the natural distribution of relaxation times, reveals direct evidence of the effect of diffusive exchange. the diffusive water exchange is not small in the intracellular space in the case of hepatocytes. Conclusions : Gd-EOB-DTPA, when combined with continuous distribution analysis, provides a robust method to study water exchange and membrane permeability in hepatocytes. Water exchange in hepatocyte is much slower thatn that in red blood cells. Therefore, tissue-specific contrast agent may be used as a functional agent to give physiological information such as cell membrane permeability.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.155.2-155.2
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• 2013

Strain-relaxed SiGe layer on Si substrate has numerous potential applications for electronic and opto- electronic devices. SiGe layer must have a high degree of strain relaxation and a low dislocation density. Conventionally, strain-relaxed SiGe on Si has been manufactured using compositionally graded buffers, in which very thick SiGe buffers of several micrometers are grown on a Si substrate with Ge composition increasing from the Si substrate to the surface. In this study, a new plasma process, i.e., the combination of PIII&D and HiPIMS, was adopted to implant Ge ions into Si wafer for direct formation of SiGe layer on Si substrate. Due to the high peak power density applied the Ge sputtering target during HiPIMS operation, a large fraction of sputtered Ge atoms is ionized. If the negative high voltage pulse applied to the sample stage in PIII&D system is synchronized with the pulsed Ge plasma, the ion implantation of Ge ions can be successfully accomplished. The PIII&D system for Ge ion implantation on Si (100) substrate was equipped with 3'-magnetron sputtering guns with Ge and Si target, which were operated with a HiPIMS pulsed-DC power supply. The sample stage with Si substrate was pulse-biased using a separate hard-tube pulser. During the implantation operation, HiPIMS pulse and substrate's negative bias pulse were synchronized at the same frequency of 50 Hz. The pulse voltage applied to the Ge sputtering target was -1200 V and the pulse width was 80 usec. While operating the Ge sputtering gun in HiPIMS mode, a pulse bias of -50 kV was applied to the Si substrate. The pulse width was 50 usec with a 30 usec delay time with respect to the HiPIMS pulse. Ge ion implantation process was performed for 30 min. to achieve approximately 20 % of Ge concentration in Si substrate. Right after Ge ion implantation, ~50 nm thick Si capping layer was deposited to prevent oxidation during subsequent RTA process at $1000^{\circ}C$ in N2 environment. The Ge-implanted Si samples were analyzed using Auger electron spectroscopy, High-resolution X-ray diffractometer, Raman spectroscopy, and Transmission electron microscopy to investigate the depth distribution, the degree of strain relaxation, and the crystalline structure, respectively. The analysis results showed that a strain-relaxed SiGe layer of ~100 nm thickness could be effectively formed on Si substrate by direct Ge ion implantation using the newly-developed PIII&D process for non-gaseous elements.