• Neonatal Medicine
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• v.18 no.1
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• pp.82-88
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• 2011

Purpose: This study aims to describe the clinical characteristics of adrenal insufficiency-associated hypotension in preterm infants and the effects of hydrocortisone therapy on their cardiovascular system and serum electrolytes. Methods: Twelve preterm infants less than 32 gestational weeks admitted to neonatal intensive care unit (NICU) of the Seoul National University Bundang Hospital from January 2007 to August 2009 with clinical and laboratory findings suggestive of adrenal insufficiency were analyzed retrospectively. Results: Gestational age was 27.8${\pm}$2.5 weeks and birth weight was 1,110${\pm}$307 g. Postnatal age, postmenstrual age, weight at the onset of adrenal insufficiency-associated hypotension were 19${\pm}$7 day, 30.6${\pm}$2.4 weeks, 1,285${\pm}$365 g. In preterm infants who showed vasopressor resistance, intravenous hydrocortisone was started with a stress dose of 4 mg/kg/day, maintained for 2.2${\pm}$0.7 days, and then tapered. Serum cortisol concentration before hydrocortisone administration was 11.6${\pm}$4.1 mg/dL. Mean blood pressure increased from 25.0${\pm}$5.4 mmHg to 35.0${\pm}$5.3 mmHg, 38.3${\pm}$8.0 mmHg and 41.9${\pm}$6.5 mmHg at time of hydrocortisone administration and 2, 4 and 6 hours after hydrocortisone administration. Urine output increased from 0.9${\pm}$0.6 mL/kg/hr to 4.1${\pm}$3.4 mL/kg/hr. Twelve hours after the administration of hydrocortisone, dopamine requirement decreased from 11.0${\pm}$2.9 $\mu$g/kg/min to 8.0${\pm}$2.3 $\mu$g/kg/min, and to 5.5${\pm}$3.4 ${\mu}g$/kg/min after 24 hours. Serum sodium concentration was increased from 130${\pm}$4 mEq/L to 136${\pm}$4 mEq/L, serum potassium concentration was decreased from 6.1${\pm}$1.1 mEq/L to 4.6${\pm}$0.6 mEq/L before and 12 hours after hydrocortisone administration. Conclusion: In preterm infants with adrenal insufficiency-associated hypotension, hydrocortisone administration improved blood pressure and urine output, decreased vasopressor requirement, and normalized serum electrolyte abnormalities.

• Radiation Oncology Journal
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• v.19 no.1
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• pp.66-73
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• 2001

Purpose : For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. Method and Materials : For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, ElC-1 ion chambers manufactured by A-150 plastic and used IC-l7M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was S co per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and there results were compared with measured results. Results : The absorbed dose of fast neutron beams was $6.47\times10^{-3}$ cGy per 1 MU at the 4 cm depth of the water phantom, which is assumed to be effective depth for BNCT. The magnitude of gamma contamination intermingled with fast neutron beams was $65.2{\pm}0.9\%$ at the same depth. In the dose distribution according to the depth of water, the neutron dose decreased linearly and the gamma dose decreased exponentially as the depth was deepened. The factor expressed energy level, $D_{20}/D_{10}$, of the total dose was 0.718. Conclusion : Through the direct measurement using the two ion chambers, which is made different wall materials, and computer calculation of isodose distribution using MCNP simulation method, we have found the dose characteristics of low fluence fast neutron beams. If the power supply and the target material, which generate high voltage and current, will be developed and gamma contamination was reduced by lead or bismuth, we think, it may be possible to accelerator-based BNCT.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.138-149
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• 2000

Purpose : It was studied that the relationship between radiation dose, dose rate and the frequency of chromosomal aberrations in peripheral lymphocytes. Methods and Materials : Peripheral lymphocytes were irradiated in vitro with 6 MeV X-ray at dose ranges from 50 cGy to 800 cGy. The variations of the frequency of chromosomal aberrations were observed according to different radiation dose rate from 20 cGy/min to 400 cGy/min at constant total dose of 400 cGy which it was considered as factor to correct biological radiation dose measurement. Results : The yields of lymphocytes with chromosomal aberrations (dicentric chromosome, ring chromosome, acentric fragment pairs) are 0% at 50 cGy, 9% at 100 cGy, 20% at 200 cGy, 27% at 300 cGy, 55% at 400 cGy, 88% at 600 cGy, and 100% at 800 cGy. The value of Ydr is 0.000 at 50 cGy, 0.093 at 100 cGy, 0.200 at 200 cGy, 0.354 at 300 cGy, 0.612 at 400 cGy, 2.040 at 600 cGy, and 2.846 at 800 cGy. The relationship between radiation (D) and the frequency of dicentrlc chromosomes and ring Chromosomes (Ydr) can be expressed as Ydr=0.188${\times}$10$^{-2}$ D/Gy+0.422${\times}$10$^{-4}$/Gy$^{2}$${\times}$D$^{2}$ The Value of Qdr is 0.000 at 50 cGy, 1.000 at 100 cGy, 1.000 at 200 cGy, 1.333 at 300 cGy, 1.118 at 400 cGy, 2.318 at 600 cGy, and 2.846 at 800 cGy. When 400 cGy is irradiated with different dose rate each of 20, 40, 60, 80, 100, 160, 240, 320, and 400 cGy/min, Ydr is each of 0.982, 0.837, 0.860, 0.732, 0.763, 0.966, 0.909, 1.006, and 0.806, and Qdr is each of 1.839, 1.555, 1.654, 1.333, 1.381, 1.750, 1.6000, 1.710, and 1.318. Conclusion : There are not the significant variations of Ydr and Qdr values according to different dose rate. And so radiation damage is influenced by total exposed radiation doses and is influenced least of all by different dose rate when it is acute single exposure.

• Tuberculosis and Respiratory Diseases
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• v.47 no.3
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• pp.321-330
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• 1999

Background : Early diagnosis and proper antibiotic treatment are very important in the management of ventilator-associated pneumonia (VAP) because of its high mortality. Bronchoscopy with a protected specimen brush (PSB) has been considered the standard method to isolate the causative organisms of VAP. However, this method burdens consumer economically to purchase a PSB. Another useful method for the diagnosis of VAP is quantitative cultures of aspirated specimens through bronchoscopic bronchoalveolar lavage (BAL), for which the infusion of more than 120 m1 of saline has been recommended for adequate sampling of a pulmonary segment. However, occasionally it leads to deterioration of the patient's condition. We studied the diagnostic efficacy of minibronchoalveolar lavage (miniBAL), which retrieves only 25 ml of BAL fluid, in the isolation of causative organisms of VAP. Methods: We included 38 consecutive patients (41 cases) suspected of having VAP on the basis of clinical evidence, who had received antibiotics before the bronchoscopy. The two diagnostic techniques of PSB and miniBAL, which were performed one after another at the same pulmonary segment, 'were compared prospectively. The cut-off values for quantitative cultures to define causative bacteria of VAP were more than $10^3$ colony-forming units (cfu)/ml for PSB and more than $10^4$ cfu/ml for BAL. Results: The amount of instilled normal saline required to retrieve 25 ml of BAL fluid was $93{\pm}32 ml$ (mean${\pm}$SD). The detection rate of causative agents was 46.3% (19/41) with PSB and 43.9% (18/41) with miniBAL. The concordance rate of PSB and miniBAL in the bacterial culture was 85.4% (35/41). Although arterial blood oxygen saturation dropped significantly (p<0.05) during ($92{\pm}10%$) and 10 min after ($95{\pm}3%$) miniBAL compared with the baseline ($97{\pm}3%$), all except 3 cases were within normal ranges. The significantly elevated heart rate during ($l25{\pm}24$/min, p<0.05) miniBAL compared with the baseline ($1l1{\pm}22$/min) recovered again in 10 min after ($111{\pm}26$/min) miniBAL. Transient hypotension was developed during the procedure in two cases. The procedure was stopped in one case due to atrial flutter. Conclusion: MiniBAL is a safe and effective technique to detect the causative organisms of VAP.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.592-600
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• 1997

Background : The level of imposed work of breathing (WOB) is important for patient-ventilator synchrony and during weaning from mechanical ventilation. Triggering methods and the sensitivity of demand system are important determining factors of the imposed WOB. Flow triggering method is available on several modern ventilator and is believed to impose less work to a patient-triggered breath than pressure triggering method. We intended to compare the level of imposed WOB on two different methods of triggering and also at different levels of sensitivities on each triggering method (0.7 L/min vs 2.0 L/min on flow triggering ; $-1\;cmH_2O$ vs $-2cm\;H_2O$ on pressure triggering). Methods : The subjects were 12 patients ($64.8{\pm}4.2\;yrs$) on mechanical ventilation and were stable in respiratory pattern on CPAP $3\;cmH_2O$. Four different triggering sensitivities were applied at random order. For determination of imposed WOB, tracheal end pressure was measured through the monitoring lumen of Hi-Lo Jet tracheal tube (Mallincrodt, New York, USA) using pneumotachograph/pressure transducer (CP-100 pulmonary monitor, Bicore, Irvine, CA, USA). Other data of respiratory mechanics were also obtained by CP-100 pulmonary monitor. Results : The imposed WOB was decreased by 37.5% during 0.7 L/min on flow triggering compared to $-2\;cmH_2O$ on pressure triggering and also decreased by 14% during $-1\;cmH_2O$ compared to $-2\;cmH_2O$ on pressure triggering (p < 0.05 in each). The PTP(Pressure Time Product) was also decreased significantly during 0.7 L/min on flow triggering and $-1\;cmH_2O$ on pressure triggering compared to $-2\;cmH_2O$ on pressure triggering (p < 0.05 in each). The proportions of imposed WOB in total WOB were ranged from 37% to 85% and no significant changes among different methods and sensitivities. The physiologic WOB showed no significant changes among different triggering methods and sensitivities. Conclusion : To reduce the imposed WOB, flow triggering with sensitivity of 0.7 L/min would be better method than pressure triggering with sensitivity of $-2\;cm\;H_2O$.

• Tuberculosis and Respiratory Diseases
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• v.43 no.2
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• pp.190-200
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• 1996

Background : Mechanical ventilation constitutes the last therapeutic method for acute respiratory failure when oxygen therapy and medical treatment fail to improve the respiratory status of the patient. This invasive ventilation, classically administered by endotracheal intubation or by tracheostomy, is associated with significant mortality and morbidity. Consequently, any less invasive method able to avoid the use of endotracheal ventilation would appear to be useful in high risk patient. Over recent years, the efficacy of nasal mask ventilation has been demonstrated in the treatment of chronic restrictive respiratory failure, particularly in patients with neuromuscular diseases. More recently, this method has been successfully used in the treatment of acute respiratory failure due to parenchymal disease. Method : We assessed the efficacy of Bilevel positive airway pressure(BiPAP) in the treatment of acute exacerbation of chronic obstructive pulmonary disease(COPD). This study prospectively evaluated the clinical effectiveness of a treatment schedule with positive pressure ventilation via nasal mask(Respironics BiPAP device) in 22 patients with acute exacerbations of COPD. Eleven patients with acute exacerbations of COPD were treated with nasal pressure support ventilation delivered via a nasal ventilatory support system plus standard treatment for 3 consecutive days. An additional 11 control patients were treated only with standard treatment. The standard treatment consisted of medical and oxygen therapy. The nasal BiPAP was delivered by a pressure support ventilator in spontaneous timed mode and at an inspiratory positive airway pressure $6-8cmH_2O$ and an expiratory positive airway pressure $3-4cmH_2O$. Patients were evaluated with physical examination(respiratory rate), modified Borg scale and arterial blood gas before and after the acute therapeutic intervention. Results : Pretreatment and after 3 days of treatment, mean $PaO_2$ was 56.3mmHg and 79.1mmHg (p<0.05) in BiPAP group and 56.9mmHg and 70.2mmHg (p<0.05) in conventional treatment (CT) group and $PaCO_2$ was 63.9mmHg and 56.9mmHg (p<0.05) in BiPAP group and 53mmHg and 52.8mmHg in CT group respectively. pH was 7.36 and 7.41 (p<0.05) in BiPAP group and 7.37 and 7.38 in cr group respectively. Pretreatment and after treatment, mean respiratory rate was 28 and 23 beats/min in BiPAP group and 25 and 20 beats/min in CT group respectively. Borg scale was 7.6 and 4.7 in BiPAP group and 6.4 and 3.8 in CT group respectively. There were significant differences between the two groups in changes of mean $PaO_2$, $PaCO_2$ and pH respectively. Conclusion: We conclude that short-term nasal pressure-support ventilation delivered via nasal BiPAP in the treatment of acute exacerbation of COPD, is an efficient mode of assisted ventilation for improving blood gas values and dyspnea sensation and may reduce the need for endotracheal intubation with mechanical ventilation.

• Tuberculosis and Respiratory Diseases
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• v.52 no.1
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• pp.14-23
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• 2002

Background: The opitmal ventilator setting during partial liquid ventilation(PLV) is controversial. This study investigated the effects of various gas exchange parameters during PLV in normal rabbit lungs in order to aid in the development of an optimal ventilator setting during PLV. Methods: Seven New-Zealand white rabbits were ventilated in pressure-controlled mode with the following settings; tidal volume($V_T$) 8 mL/kg, positive end-expiratory pressure(PEEP) 4 $cmH_2O$, inspiratory-to-expiratory ratio(I:E ratio) 1:2, fraction of inspired oxygen($F_TO_2$) 1.0. The respiration rate(RR) was adjusted to keep $PaCO_2$ between 35~45 mmHg. The ventilator settings were changed every 30 min in the following sequence : (1) Baseline, as the basal ventilator setting, (2) Inverse ratio, I:E ratio 2:1, (3) high PEEP, adjust PEEP to achieve the same mean inspiratory pressure (MIP) as in the inverse ratio, (4) High $V_T$, $V_T$ 15 mL/kg, (5) high RR, the same minute ventilation (MV) as in the High $V_T$. Subsequently, the same protocol was repeated after instilling 18 mL/kg of perfluorodecalin for PLV. The parameters of gas exchange, lung mechanics, and hemodynamics were examined. Results: (1) The gas ventilation(GV) group showed no significant changes in the $PaO_2$ at all phases. The $PaCO_2$ was lower and the pH was higher at the high $V_T$ and high RR phases(p<0.05). No significant changes in the lung mechanics and hemodynamics parameters were observed. (2) The baseline $PaO_2$ for the PLV was $312{\pm}$ mmHg. This was significantly lower when decreased compared to the baseline $PaO_2$ for GV which was $504{\pm}81$ mmHg(p=0.001). During PLV, the $PaO_2$, was significantly higher at the high PEEP($452{\pm}38$ mmHg) and high $V_T$ ($461{\pm}53$ mmHg) phases compared with the baseline phase. However, it did not change significantly during the inverse I:E ratio or the high RR phases. (3) The $PaCO_2$ was significantly lower at high $V_T$ and RR phases for both the GV and PLV. During the PLV, $PaCO_2$ were significantly higher compared to the GV (p<0.05). (4) There were no important or significant changes in of baseline and high RR phases lung mechanics and hemodynamics parameters during the PLV. Conclusion: During PLV in the normal lung, adequate $V_T$ and PEEP are important for optimal oxygenation.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.248-259
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• 2007

The aim of this research was to study the effect of intermittent polymerization on marginal adaptation by comparing the marginal adaptation of intermittently polymerized composite to that of continuously polymerized composite. The materials used for this study were Pyramid (Bisco Inc., Schaumburg, U.S.A.) and Heliomolar (Ivoclar Vivadent, Liechtenstein) . The experiment was carried out in class II MOD cavities prepared in 48 extracted human maxillary premolars. The samples were divided into 4 groups by light curing method: group 1- continuous curing (60s light on with no light off), group 2-intermittent curing (cycles of 3s with 2s light on & 1s light off for 90s); group 3- intermittent curing (cycles of 2s with 1s light on & 1s light off for 120s); group 4- intermittent curing (cycles of 3s with 1s light on & 2s light off for 180s). Consequently the total amount of light energy radiated was same in all the groups. Each specimen went through thermo-mechanical loading (TML) which consisted of mechanical loading (720,000 cycles, 5.0 kg) with a speed of 120 rpm for 100hours and thermocycling (6000 thermocycles of alternating water of $50^{\circ}C$ and $55^{\circ}C$). The continuous margin (CM) (%) of the total margin and regional margins, occlusal enamel (OE), vertical enamel (VE), and cervical enamel (CE) was measured before and after TML under a $\times200$ digital light microscope. Three-way ANOVA and Duncan's Multiple Range Test was performed at 95% level of confidence to test the effect of 3 variables on CM (%) of the total margin: light curing conditions, composite materials and effect of TML. In each group, One-way ANOVA and Duncan's Multiple Range Test was additionally performed to compare CM (%) of regions (OE, VE CE). The results indicated that all the three variables were statistically significant (p < 0.05). Before TML, in groups using Pyramid, groups 3 and 4 showed higher CM (%) than groups 1 and 2, and in groups using Heliomolar. groups 3 and 4 showed higher CM (%) than group 1 (p < 0.05). After TML, in both Pyramid and Heliomo)ar groups, group 3 showed higher CM (%) than group 1 (p < 0.05) CM (%) of the regions are significantly different in each group (p < 0.05). Before TML, no statistical difference was found between groups within the VE and CE region. In the OE region, group 4 of Pyramid showed higher CM (%) than group 2, and groups 2 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). After TML, no statistical difference was found among groups within the VE and CE region. In the OE region, group 3 of Pyramid showed higher CM (%) than groups 1 and 2, and groups 2,3 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). It was concluded that intermittent polymerization may be effective in reducing marginal gap formation.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.1
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• pp.54-59
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• 2017

Purpose The present study aimed at assessing the effectiveness of the respiratory gating method used in the flow mode and additional localized respiratory-gated imaging, which differs from the step and go method. Materials and Methods Respiratory gated imaging was performed in the flow mode to twenty patients with lung cancer (10 patients with stable signals and 10 patients with unstable signals), who underwent PET/CT scanning of the torso using Biograph mCT Flow PET/CT at Bundang Seoul University Hospital from June 2016 to September 2016. Additional images of the lungs were obtained by using the respiratory gating method. SUVmax, SUVmean, and Tumor Volume ($cm^3$) of non-gating images, gating images, and additional lung gating images were found with Syngo,bia (Siemens, Germany). A paired t-test was performed with GraphPad Prism6, and changes in the width of the amplitude range were compared between the two types of gating images. Results The following results were obtained from all patients when the respiratory gating method was applied: $SUV_{max}=9.43{\pm}3.93$, $SUV_{mean}=1.77{\pm}0.89$, and $Tumor\;Volume=4.17{\pm}2.41$ for the non-gating images, $SUV_{max}=10.08{\pm}4.07$, $SUV_{mean}=1.75{\pm}0.81$, and $Tumor\;Volume=3.56{\pm}2.11$ for the gating images, and $SUV_{max}=10.86{\pm}4.36$, $SUV_{mean}=1.77{\pm}0.85$, $Tumor\;Volume=3.36{\pm}1.98$ for the additional lung gating images. No statistically significant difference in the values of $SUV_{mean}$ was found between the non-gating and gating images, and between the gating and lung gating images (P>0.05). A significant difference in the values of $SUV_{max}$ and Tumor Volume were found between the aforementioned groups (P<0.05). The width of the amplitude range was smaller for lung gating images than gating images for 12 from 20 patients (3 patients with stable signals, 9 patients with unstable signals). Conclusion In PET/CT scanning using the respiratory gating method in the flow mode, any lesion movements caused by respiration were adjusted; therefore, more accurate measurements of $SUV_{max}$, and Tumor Volume could be obtained from the gating images than the non-gating images in this study. In addition, the width of the amplitude range decreased according to the stability of respiration to a more significant degree in the additional lung gating images than the gating images. We found that gating images provide information that is more useful for diagnosis than the one provided by non-gating images. For patients with irregular signals, it may be helpful to perform localized scanning additionally if time allows.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.3856-3868
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• 2011

Until recently, research trend in real estate has been focused on real estate market and the market analysis. But the studies on real estate training program development for real estate agents to improve their job performance are relatively short in numbers. Thus, this study shows empirical analysis of the needs for the training programs for real estate agents in Cheonan to improve their job performance. The results are as follows. First, in the survey of asking what educational contents they need in order to improve real estate agents' job performance, most of the respondents show their needs for the analysis of house's value, legal knowledge, real estate management, accounting, real estate marketing, and understanding of the real estate policy. This is because they are well aware that the best way of responding to the changing clients' needs comes from training programs. Secondly, asked about real estate marketing strategies, most of respondents showed their awareness of new strategies to meet the needs of clients. This is because new forms of marketing strategies including internet ads are needed in the field as the paradigm including Information Technology changes. Thirdly, asked about the need for real estate-related training programs, 92% of the respondents answered they need real estate education programs run by the continuing education centers of the universities. In addition, the survey showed their needs for retraining programs that utilize the resources in the local universities. Other than this, to have effective and efficient training programs, they demanded running a training system by utilizing the human resources of the universities under the name of the department of 'Real Estate Contract' for real estate agents' job performance. Fourthly, the survey revealed real estate management(44.2%) and real estate marketing(42.3%) is the most chosen contents they want to take in the regular course for improving real estate agents' job performance. This shows their will to understand clients' needs through the mind of real estate management and real estate marketing. The survey showed they prefer the training programs as an irregular course to those in the regular one. Despite the above results, this study chose subjects only in Cheanan and thus it needs to research more diverse areas. The needs of programs to improve real estate agents job performance should be analyzed empirically targeting the real estate agents not just in Cheonan but also cities like Pyeongchon, Ilsan and Bundang in which real estate business is booming, as well as undergraduate and graduate students whose major is real estate studies. These studies will be able to provide information to help develop the customized training programs by evaluating elements that real estate agents need in order to meet clients satisfaction and improve their job performance. Many variables of the program development learned through these studies can be incorporated in the curriculum of the real estate studies and used very practically as information for the development of the real estate studies in this fast changing era.