• Sleep Medicine and Psychophysiology
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• v.8 no.2
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• pp.113-120
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• 2001

Objectives: Obstructive sleep apnea syndrome is common and may produce various symptoms and serious complications. A substantial number of research articles on obstructive sleep apnea syndrome have been published in Korea. However, we found such limitations as lack of sufficient sample size and lack of polysomnography-proven cases. Therefore, we aimed at studying clinical features and sleep structure in a sufficient number of Korean patients with obstructive sleep apnea syndrome diagnostically confirmed with polysomnography. Methods: We studied 801 subjects referred to the Division of Sleep Studies, Seoul National University Hospital, who were diagnosed as having obstructive sleep apnea syndrome with polysomnography. Subjects were excluded if they had central sleep apnea syndrome, periodic limb movement disorder, narcolepsy or REM sleep behavior disorder. Foreign patients were also excluded. First of all, we studied the clinical features of the subjects. Secondly, we compared sleep-related parameters of the study subjects with those of age/sex-matched normal values. Thirdly, correlations of respiratory disturbance index (RDI) with each of the sleep-related parameters were calculated. Results: Among the 801 subjects, 668 were male subjects (83.4%) and 133 female subjects (16.4%). Their mean age was 46.6 years (${\pm}13.5$). The mean body mass index (BMI) was 25.8 (${\pm}3.8$) and subjects with BMI was over 28.0 accounted for 22.8% of the total. Fifty subjects (6.2%) were found to take benzodiazepines. Mean RDI and mean nocturnal oxygen saturation of all subjects was 31.2 (${\pm}24.4$) and 94.5% (${\pm}3.6$), respectively. In comparison with normal values, the subjects showed longer sleep latency, lower sleep efficiency, decreased total slow wave sleep % (TSWS %), and decreased total REM sleep % (TREM %)(p<0.01 in all). RDI had a negative correlation with each TSWS % and TREM % (p<0.01, p<0.01). However, RDI did not have significant correlation with either sleep latency or sleep efficiency. Conclusion: In this study, 6.2% of patients diagnosed as having obstructive sleep apnea syndrome were found to take benzodiazepines, although they are generally considered to be of litte benefit or even dangerous because of the respiratory suppressing effect. The proportion of obese subjects was only 22.8% and Korean patients with obstructive sleep apnea syndrome seem to be less obese than those described in foreign journals. This study also suggests that the severity of obstructive sleep apnea syndrome may have a more significant effect on sleep architecture defined as TSWS % and TREM % than on sleep efficiency.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.13 no.1
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• pp.19-35
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• 2009

Objectives : In the study on the waveform analysis of radial artery pulse diagnosis, we need to establish fundamentals of contemporary pulse diagnosis research. To achieve certain experimental basis on traditional pulse diagnosis, we have to research the differences of pulse waveform according to pressure (in 5 level) and position (Chon, Gwan, Cheok in radial artery). As a first step, in present thesis, we tried to find the differences of pulse waveform according to pressure. Methods and Results : In this research, we analyzed seven parameters of the waveform at five levels of pressure. The parameters are E(so called 'energy', a representative of pulse strength), h1(height of percussion wave) and h2(height of subincisura). The results were as follows. 1. When we analyzed the change of the waveform according to pressure in the left Gwan, E, hl, h2 and A differed between 1st and 2nd grade, between 1st and 3rd grade, between 1st and 4th grade, between 1st and 5th grade, between 2nd and 3rd grade, between 2nd and 5th grade, between 3rd and 5th grade and between 4th and 5th grade in 95% confidence interval. 2. And t2, t4 differed between 1st and 2nd grade, between 1st and 5th grade, between 2nd and 4th grade, between 2nd and 4th grade, between 2nd and 5th grade, between 3rd and 4th grade, between 3rd and 5th grade and between 4th and 5th grade in 95% confidence interval. 3. W differed between 1st and 3rd grade, between 1st and 4th grade, between 2nd and 3rd grade, between 2nd and 4th grade, between 2nd and 5th grade, between 3rd and 4th grade, between 3rd and 5th grade, and between 4th and 5th grade in 95% confidence interval. 4. And h2/h1 differed between 1st and 4th grade, between 1st and 5th grade, between 2nd and 4th grade, between 2nd and 5th grade, between 3rd and 4th grade & between 3rd and 5th grade in 95% confidence interval. 5. There were differences between 1st and 2nd grade & between 2nd and 5th grade in the case of t4/t2 in 95% confidence interval. And there were differences between 1st and 5th grade, between 3rd and 4th grade, between 3rd and 5th grade & between 4th and 5th grade in the case of W/A in 95% confidence interval. And were differences between 1st and 2nd grade, between 2nd and 3rd grade, between 2nd and 4th grade, between 3rd and 4th grade, between 3rd and 5th grade & between 4th and 5th grade in the case of A/E in 95% confidence interval. Conclusions : As mentioned above, we conclude that the waveform analysis according to five grade pressure in the left Gwan shows the difference of waveform in each grade pressure.

• Journal of Acupuncture Research
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• v.20 no.5
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• pp.118-132
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• 2003

Objective: The aim of this study was to investigate the effects of Joksamni(ST36) combination on NAD PH-diaphorase, neuronal nitric oxide synthase(nNOS), neuropeptide Y(NPY) and vasoactive intestinal peptide (VIP) in the cerebral cortex of spontaneously hypertensive rat. Methods: The experimental groups were divided into four groups: Normal, Joksamni(ST36), Joksamni(ST36)+Eumneungcheon(SP9), and Joksamni(ST36)+Gokji(LI11). Needles were inserted into acupoints at the depth of 0.5cm with basic insertion method. Electroacupuncture was done under the condition of 2Hz electrical biphasic pulses with continuous rectangular wave lasting for 0.2ms until the muscles produced visible contractions. Such stimulation was applied continuously for 10 minutes, 1 time every 2 days for 10 sessions of treatments. Thereafter we evaluated changes in NADPH-d positive neurons histochemically and changes in nNOS, NPY and VIP positive neurons immunohistochemically. Results: The optical densities of NADPH-d positive neurons of the Joksamni(ST36)+Eumneungcheon(SP9) group in all areas of cerebral cortex and Joksamni(ST36)+Gokji(LI11) group in primary somatosensory cortex, visual cortex, auditory cortex, perirhinal cortex were significantly increased as compared to the Joksamni(ST36) group. The optical densities of NADPH-d positive neurons of the Joksamni(ST36)+Gokji(LI11) group were significantly decreased as compared to the Joksamni(ST36)+Eumneungcheon(SP9) group with the exception of primary somatosensory cortex. The optical densities of nNOS positive neurons of the Joksamni(ST36)+Eumneungcheon(SP9) group in all areas of cerebral cortex and Joksamni(ST36)+Gokji(LI11) group in auditory cortex, perirhinal cortex, insular cortex were significantly increased as compared to the Joksamni(ST36) group. The optical densities of nNOS positive neurons of the Joksamni(ST36)+Gokji(LI11) group were significantly decreased in all areas of cerebral cortex as compared to the Joksamni(ST36)+Eumneungcheon(SP9) group. The optical densities of NPY positive neurons of the Joksamni(ST36)+Gokji(LI11) group were significantly decreased in primary motor cortex, primary somatosensory cortex, cingulate cortex as compared to the Joksamni (ST36) and Joksamni(ST36)+Eumneungcheon(SP9) groups. The optical densities of VIP positive neurons of the Joksamni(ST36)+Eumneungcheon(SP9) group were significantly increased in all areas of cerebral cortex except for cingulate cortex as compared to the Joksamni(ST36) group. The optical densities of VIP positive neurons of the Joksamni(ST36)+Gokji(LI11) group were significantly decreased in auditory cortex, cingulate cortex, perirhinal cortex as compared to the Joksamni(ST36) group. The optical densities of VIP positive neurons of the Joksamni(ST36)+Gokji(LI11) group were significantly decreased in all areas of cerebral cortex as compared to the Joksamni(ST36)+Eumneungcheon(SP9) group. Conclusions: The result demonstrated that electroacupuncture on Joksamni(ST36) and its combination change the activities of the NO system and peptidergic system in the cerebral cortex of SHR and that acupoint combination is one of the important parameters for the effects.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.4
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• pp.255-265
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• 1999

CTD castings and current observations are taken in June, July and October, 1997 and May and July, 1998 to investigate the effect of the Keum River dyke on the structure of physical properties and the type of the Keum River estuary. Tide and tidal current relation shows that the ebbing is longer than the flooding by 1.5 hours with the early current reversing before high tide. In the rainy season (May to July), frequent large fresh water discharge during the ebbing from the dyke changes vertical salinity difference and time variation of salinity greatly near the head of the estuary, where salinity becomes lower than 2‰ in summer fresh water flooding. Halocline developed by the fresh water discharge makes two-layer structure, of which strength and depth increase in the low tide. The relationship between tide phase and surface salinity variation shows the phase lag of 2.5 hours near the head of the estuary but the standing wave relation down the estuary. This phase lag implies that a low salinity water diluted by the fresh water discharge for 2-3 hours in the ebb period moves with tidal excursion. In the dry season, vertical salinity difference reduces significantly. We calculate stratification and circulation parameters using the observed salinity structure, surface current and fresh water discharge. The Keum River estuary shows a partially mixed type, changing the stratification parameter from the rainy to the dry season. Mean flows of observed tidal current at lower and upper layer are landward and seaward, which are consistent with the circulation of a partially mixed estuary. Based upon the estuary type and circulation we suggest that the suspended materials will move toward the upstream due to low-layer mean flow and then the Keum River estuary will be a deposit environment.

• Clinical and Experimental Pediatrics
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• v.49 no.4
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• pp.417-423
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• 2006

Purpose : The objectives of this study were to assess ventricular function by tissue Doppler imaging in children who were receiving chemotherapy or who had received chemotherapy, and to apply repeated tissue Doppler imaging to make an early assessment in cardiac toxicity studies. Methods : This study was conducted on 23 oncology patients on-treatment or off-treatment from April 2005 to July 2005 at Dongsan Medical Center, Keimyung University. All patients(group 1) were divided into two groups, fractional shortening(FS) over 29 percent(group 2) and FS under 28 percent (group 3) in the first category. These same patients were also divided into the following groups : group treated with anthracyclin(group 4) and group treated without anthracyclin(group 5). Deceleration time(DT), isovolumic relaxation time(IVRT), FS, peak early diastolic(E), and peak late diastolic (A) velocity of transmitral flow were measured by M-mode and pulsed wave Doppler. Systolic(Sm), peak early diastolic(Em), and peak late diastolic(Am) velocity in apical 4-chamber and 2-chamber views were measured by tissue Doppler imaging. The author calculated a modified Tei index, E/A, E/Em ratio by using measured values. Results : Twenty three patients were enrolled : 12 boys and 11 girls. The average age of patients was 8 years and 4 months. Thirteen out of 23 patients were in the group treated with anthracyclin (group 4) and 6 had FS under 28 percent(group 3). E/Em ratio showed a significant difference between group 1 and control group($6.46{\pm}1.85$ vs $7.06{\pm}1.64$, P<0.05). Other parameters had no difference statistically. Conclusion : This study showed that the change of cardiac function developed earlier in diastolic function than in systolic function, as E/Em ratio reflecting the mean LV diastolic pressure showed a significant difference between the control group and chemotherapy groups. Echocardiography using tissue Doppler imaging is a non-invasive, comfortable and reliable method for post-chemotherapy follow up.

• Progress in Medical Physics
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• v.19 no.1
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• pp.73-79
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• 2008

Retinal prosthesis is regarded as the most feasible method for the blind caused by retinal diseases such as retinitis pigmentosa (RP) or age related macular degeneration (AMD). Recently Korean consortium launched for developing retinal prosthesis. One of the prerequisites for the success of retinal prosthesis is the optimization of the electrical stimuli applied through the prosthesis. Since electrical characteristics of degenerate retina are expected to differ from those of normal retina, we performed voltage stimulation experiment both in normal and degenerate retina to provide a guideline for the optimization of electrical stimulation for the upcoming prosthesis. After isolation of retina, retinal patch was attached with the ganglion cell side facing the surface of microelectrode arrays (MEA). $8{\times}8$ grid layout MEA (electrode diameter: $30{\mu}m$, electrode spacing: $200{\mu}m$, and impedance: $50k{\Omega}$ at 1 kHz) was used to record in-vitro retinal ganglion cell activity. Mono-polar electrical stimulation was applied through one of the 60 MEA channel, and the remaining channels were used for recording. The electrical stimulus was a constant voltage, charge-balanced biphasic, anodic-first square wave pulse without interphase delay, and 50 trains of pulse was applied with a period of 2 sec. Different electrical stimuli were applied. First, pulse amplitude was varied (voltage: $0.5{\sim}3.0V$). Second, pulse duration was varied $(100{\sim}1,200{\mu}s)$. Evoked responses were analyzed by PSTH from averaged data with 50 trials. Charge density was calculated with Ohm's and Coulomb's law. In normal retina, by varying the pulse amplitude from 0.5 to 3V with fixed duration of $500{\mu}s$, the threshold level for reliable ganglion cell response was found at 1.5V. The calculated threshold of charge density was $2.123mC/cm^2$. By varying the pulse duration from 100 to $1,200{\mu}s$ with fixed amplitude of 2V, the threshold level was found at $300{\mu}s$. The calculated threhold of charge density was $1.698mC/cm^2$. Even after the block of ON-pathway with L-(1)-2-amino-4-phosphonobutyric acid (APB), electrical stimulus evoked ganglion cell activities. In this APB-induced degenerate retina, by varying the pulse duration from 100 to $1200{\mu}s$ with fixed voltage of 2 V, the threshold level was found at $300{\mu}s$, which is the same with normal retina. More experiment with APB-induced degenerate retina is needed to make a clear comparison of threshold of charge density between normal and degenerate retina.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.145-156
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• 1997

ZrO2 phase transformations depending on the type and amount of dopants and the sintering temperatures were studied for the 2 components (CaO-, Y2O3-, MgO-ZrO2) and the 3 components(MgO-ZrO2-Al2O3)ZrO2 powder by X-ray diffraction and Raman spectroscopy. In the CaO- and Y2O3-ZrO2 systems, as the CaO and Y2O3 contents increased to 6~15mol% and 3~15mol% respectively, we were not able to identify between tetragonal and cubic in the X-ray diffraction patterns. On the other hand, all Raman modes shifted to lower wavenumbers, decreasing in intensity and the number of bands, markedly. These phenomena were caused by tetragonallongrightarrowcubic phase transformation and interpreted by the breakdown of the wave vector selection rule(k=0) and the structural disorder associated with the formation of oxygen sublattice which was caused by the substitution between Zr4+ ion and Ca2+ or Y3+ ion in ZrO2 matrix. The monoclinic to cubic phase transformation occurred in 10mol% MgO-ZrO2 system. As the Al2O3 content increased from 0 to 20mol% in the MgO-ZrO2-Al2O3 systems, cubic phase transformed to monoclinic phase, this is because the MgO didn't play a role in a stabilizer because of the formation of the spinel(MgAl2O4) by the reaction between MgO and Al2O3, Also, the ZrO2 phase transformation was explained by the change of it's lattice parameters depending on the type and amount of dopants. Namely, as the amount of dopant increased to 10~13mol%, the axial ra-tio c/a came close to unity with increasing the lattice parameter a and decreasing the lattice parameter c. At that time, the tetragonallongrightarrowcubic phase transformation occurred.

• Clinical and Experimental Pediatrics
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• v.50 no.5
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• pp.476-483
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• 2007

Purpose : The objective of this study was to assess ventricular function by tissue Doppler imaging (TDI) in children with congenital heart disease (CHD) who have been undergoing open heart surgery (OHS) using cardiopulmonary bypass. We tried to compare the parameters of tissue Doppler imaging before and after OHS in patients with congenital heart disease. Methods : This study was conducted on 32 patients with CHD after OHS from January 2005 to December 2005 at Kyungpook National University hospital. Patients who underwent 2-D echocardiography before and after their OHS. All patients were divided into three groups, left ventricular volume overloading group (group 1), and right ventricular volume overloading group (group 2), and right ventricular pressure overloading group (group 3). The TDIs were examined before and 1 to 3 months after OHS. Peak early diastolic (E), and peak late diastolic (A) velocity of transmitral flow were measured by pulsed wave Doppler examination. Peak systolic (Sm), peak early diastolic (Em), and peak late diastolic (Am) velocity in apical 4-chamber and 2-chamber views were measured by TDI. The author calculated E/Em ratio. Results : The patients were 14 boys and 18 girls and the average age of patients was 2 years and 3 months. The congenital heart diseases which have to get OHS were ventricular septal defect (13 cases), atrial septal defect (7), atrioventricular septal defect (3), isolated pulmonary stenosis (2) and tetralogy of Fallot (7). There were significant decrease of Sm, Em, Am measured on tricuspid annulus and E/Em measured on mitral annulus in apical 4 chamber view (P<0.05). Conclusion : This study showed significant decrease of Sm, Em, Am measured on tricuspid annulus and E/Em measured on mitral annulus in apical 4 chamber view after OHS. These changes might be due to the effects of cardiopulmonary bypass in OHS and/or hemodynamic changes after correction of congenital heart disease. To clarify these changes, further study on more patients is needed.

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.551-557
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• 2013

In the present study, pristine carbon nanotube (p-CNT) and thiolated carbon naotube (t-CNT) electrodes were investigated to improve their detectabilities for cadmium (Cd) and lead (Pb). In addition, we evaluate which reaction mechanism is used when the electrolyte contains both Cd and Pb metals. Square wave stripping was employed for analyzing the sensitivity for the metals. A frequency of 30 Hz, a deposition potential of -1.2 V vs. Ag/AgCl and a deposition time of 300 s were used as optimal SWSV parameters. t-CNT electrodes show the better sensitivity for both Cd and Pb metals than that of p-CNT electrodes. In case of Cd, sensitivities of p-CNT and t-CNT electrodes were $3.1{\mu}A/{\mu}M$ and $4.6{\mu}A/{\mu}M$, respectively, while the sensitivities for Pb were $6.5{\mu}A/{\mu}M$ (p-CNT) and $9.9{\mu}A/{\mu}M$ (t-CNT), respectively. The better sensitivity of p-CNT electrodes is due to the enhancement in the reaction rate of metal ions that are facilitated by thiol groups attached on the surface of CNT. When sensitivity was measured for the detection of Cd and Pb metals present simultaneously in the electrolyte, Pb indicates better sensitivity than Cd irrespective of electrode types. It is ascribed to the low standard electrode potential of Pb, which then promotes the possibility of oxidation reaction of the Pb metal ions. In turn, the Pb metal ions are deposited on the electrode surface faster than that of Cd metal ions and cover the electrode surface during deposition step, and thus Pb metals that cover the large portion of the surface are more easily stripped than that of Cd metals during stripping step.

• Tuberculosis and Respiratory Diseases
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• v.50 no.3
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• pp.343-352
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• 2001

Background : Advanced chronic obstructive pulmonary disease is characterized by progressive pulmonary hypertension leading to right heart dysfunction, which plays a Important role in clinical evaluation but remains difficult and challenging to quantify. The noninvasive doppler echocardiographic value referred to as the Tei index has been suggested as a simple, reproducible and reliable parameter of the right ventricular function. The purpose of this was to assess the right ventricular function in patients with chronic obstructive pulmonary disease using the Tei index and to evaluate its relationship with the pulmonary functional status. Methods : The study population comprised of 26 patients with chronic obstructive pulmonary disease and 10 normal control subjects. The Tei index was obtained by dividing the sum of the isovolumetric contraction and the relaxation times by the ejection time using a pulsed-wave doppler. It was compared with the other available Doppler echocardiographic parameters of systolic or diastolic function and with the pulmonary function of the patients. Results : The Tei indices of the patients with COPD were significantly higher than those of normal subjects($0.45{\pm}0.17$ vs. $0.27{\pm}0.03$, p<0.01). The isovolumetric contraction time/ejection time($0.32{\pm}0.08$ vs. $0.25{\pm}0.05$, p<0.05), the isovolumetric relaxation time/ejection time($0.29{\pm}0.16$ vs. $0.15{\pm}0.08$, p<0.05)and the preejection period/ejection time ($0.46{\pm}0.10$ vs. $0.38{\pm}0.06$, p<0.05) were prolonged and the ejection time ($255.2{\pm}32.6$ vs. $314.2{\pm}16.5$ msec, p<0.05) was significantly shortened in patients with COPD compared to normal subjects. The tei indices were inversely correlated with the $FEV_1$ (r=-0.46, p<0.05) and were prolonged significantly in patients with a severe obstructive ventilatory dysfunction(less than 35% of predicted $FEV_1$) compared to those with a mild and moderate ventilatory dysfunction. The tei indices showed an inverse correlation to with the ejection time (r=-0.469), the isovolumetric contraction time/ejection time(r=0.453), the isovolumetric relaxation time/ejection time(r=0.896) and the preejection period/ejection time(r=0.480). Conclusion : The tei index appeared to be a useful noninvasive means of evaluating the right ventricular function. It revealed a significant correlation with the pulmonary function in patients with COPD.