• The Journal of Engineering Geology
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• v.32 no.2
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• pp.257-270
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• 2022

This study evaluated the hydraulic factors contributing to the decreasing groundwater levels across Jeju island. Time-series data for groundwater level, precipitation, and groundwater usage and information on land use were acquired, and the correlations among them were analyzed to evaluate the causes of the decreasing groundwater. The effects of precipitation and groundwater usage on the fluctuations of groundwater level were quantified using response surface analysis and sensitivity analysis, and methods for groundwater quantity management by region were proposed. The results showed that the rate of groundwater decrease in the western region was larger than that in the eastern region. For the eastern region, the influence of precipitation was large and the rate of decrease in the groundwater level was relatively small. The geological formation of this part of the island and continuous seawater intrusion suggest that although the absolute amount of groundwater extracted for use was large, the decrease in the groundwater level was not seen to be great due to an increase in pressure by seawater intrusion. Overall, precipitation and groundwater usage had the greatest effect on the amount of groundwater in the western region, and thus their data would be most useful for informing groundwater management, whereas other factors (e.g., sea level and the location of the freshwater-seawater transition zone) must be considered when understanding Jeju's eastern region. As the characteristics of groundwater level fluctuations in the eastern and western regions are distinct, an optimal management plan for each region should be proposed to ensure the efficient management of groundwater quantity.

• Tuberculosis and Respiratory Diseases
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• v.41 no.4
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• pp.379-388
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• 1994

Background : In sleep apnea syndrome, arterial oxygen saturation($SaO_2$) decreases at a variable rate and to a variable degree for a given apneic period from patient to patient, and various kinds of cardiac arrythmia are known to occur. Factors supposed to affect arterial oxygen desaturation during apnea are duration of apnea, lung voulume at which apnea occurs, and oxygen consumption rate of the subject. The lung serves as preferential oxygen source during apnea, and there have been many reports related with the influence of lung volume on $SaO_2$ during apnea, but there are few, if any, studies about the influence of oxygen consumption rate of an individual on $SaO_2$ during breath holding or about the profile of arterial oxygen resaturation after breathing resumed. Methods : To investigate the changes of $SaO_2$ and heart rate(HR) during breath holding(BH) and rebreathing(RB) and to evaluate the physiologic factors responsible for the changes, lung volume measurements, and arterial blood gas analyses were performed in 17 healthy subjects. Nasal airflow by thermistor, $SaO_2$ by pulse oxymeter and ECG tracing were recorded on Polygraph(TA 4000, Gould, U.S.A.) during voluntary BH & RB at total lung capacity(TLC), at functional residual capacity(FRC) and at residual volume(RV), respectively, for the study subjects. Each subject's basal metabolic rate(BMR) was assumed on Harris-Benedict equation. Results: The time needed for $SaO_2$ to drop 2% from the basal level during breath holding(T2%) were $70.1{\pm}14.2$ sec(mean${\pm}$standard deviation) at TLC, $44.0{\pm}11.6$ sec at FRC, and $33.2{\pm}11.1$ sec at RV(TLC vs. FRC, p<0.05; FRC vs. RV, p<0.05). On rebreathing after $SaO_2$ decreased 2%, further decrement in $SaO_2$ was observed and it was significantly greater at RV($4.3{\pm}2.1%$) than at TLC($1.4{\pm}1.0%$)(p<0.05) or at FRC($1.9{\pm}1.4%$)(p<0.05). The time required for $SaO_2$ to return to the basal level after RB(Tr) at TLC was not significantly different from those at FRC or at RV. T2% had no significant correlation either with lung volumes or with BMR respectively. On the other hand, T2% had significant correlation with TLC/BMR(r=0.693, p<0.01) and FRC/BMR (r=0.615, p<0.025) but not with RV/BMR(r=0.227, p>0.05). The differences between maximal and minimal HR(${\Delta}HR$) during the BH-RB manuever were $27.5{\pm}9.2/min$ at TLC, $26.4{\pm}14.0/min$ at RV, and $19.1{\pm}6.0/min$ at FRC which was significantly smaller than those at TLC(p<0.05) or at RV(p<0.05). The mean difference of 5 p-p intervals before and after RB were $0.8{\pm}0.10$ sec and $0.72{\pm}0.09$ sec at TLC(p<0.001), $0.82{\pm}0.11$ sec and $0.73{\pm}0.09$ sec at FRC(p<0.025), and $0.77{\pm}0.09$ sec and $0.72{\pm}0.09$ sec at RV(p<0.05). Conclusion Healthy subjects showed arterial desaturation of various rates and extent during breath holding at different lung volumes. When breath held at lung volume greater than FRC, the rate of arterial desaturation significantly correlated with lung volume/basal metabolic rate, but when breath held at RV, the rate of arterial desaturation did not correlate linearly with RV/BMR. Sinus arrythmias occurred during breath holding and rebreathing manuever irrespective of the size of the lung volume at which breath holding started, and the amount of change was smallest when breath held at FRC and the change in vagal tone induced by alteration in respiratory movement might be the major responsible factor for the sinus arrythmia.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.1105-1113
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• 1997

Background : Prone position improves oxygenation in some patients with ARDS. According to some authors, prone position can also improve the deteriorated hemodynamics induced by PEEP. But these respiratory and hemodynamic effects of prone position has not yet been fully established. Methods : Twentythree consequtive patients with ARDS(M : F= 11 : 12, $62.1{\pm}20.8yrs$) were the subjects for this study. ABGA, static compliance of the respiratory system, mean arterial pressure and pulse rate were obtained in supine position and at 5min, 0.5h and 2h of prone position. Positive respiratory response was defined as 20mmHg or more increase in $PaO_2/FIO_2$ within 2h of prone position. Early of late respiratory responses were defined if the positive response was observed within of after 3 day of ARDS onset, respectively. Positive hemodynamic response was defined as 10mmHg or more increase in mean arterial pressure at 5min of prone position. Results : Fifteen patients (65%) showed positive respiratory response. In the respiratory responders, $PaO_2$ was $69.8{\pm}17.6mmHg$ in supine position, $83.2{\pm}22.6mmHg$ in prone position 0.5h, $96.8{\pm}22.7mmHg$ in prone position 2h(p<0.001), and $PaO_2/FIO_2$ was $108{\pm}41mmHg$, $137{\pm}57mmHg$, $158{\pm}50mmHg$, respectively(p=0.001). Age, sex, cause of ARDS, supine $PaO_2$ and $PaO_2/FIO_2$ were not different between the respiratory responders and the nonresponders. The respiratory responders, however, showed higher mean arterial pressure than the nonresponders($91.1{\pm}13.1mmHg$ vs. $76.0{\pm}18.7mmHg$, p=0.035), and tendency of higher survival rate(9/15 vs. 2/8, p=0.074). Static compliance of the respiratory system was decreased in prone position 0.5h($28.4{\pm}7.9ml/cm$ $H_2O$ vs. $23.8{\pm}7.6ml/cm$ $H_2O$, p=0.007). The overall rate of early response(n=23) and late response(n=11) were similar(14/23 vs. 7/11, p>0.05). But patient without early response showed late response only in 25%(1/4), while patient with early response showed late response in 85.7%(6/7)(p=0.072). Five patients(22%) showed positive hemodynamic response, two of them being respiratory nonresponders. There were no differences in the baseline mean arterial pressure or the level of PEEP applied in supine between the hemodynamic responders and the hemodynamic nonresponders. Conclusions : Prone position either improved oxygenation or increased arterial pressure in significant proportion of patients with ARDS. And the respiratory response to prone position was thought to be determined in the early stage of ARDS.

• Investigative Magnetic Resonance Imaging
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• v.8 no.2
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• pp.79-85
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• 2004

Purpose : To evaluate the usefulness and reproducibility of $^1H$ MRS in different 1.5 T MR machines with different coils to compare the SNR, scan time and the spectral patterns in different brain regions in normal volunteers. Materials and Methods : Localized $^1H$ MR spectroscopy ($^1H$ MRS) was performed in a total of 10 normal volunteers (age; 20-45 years) with spectral parameters adjusted by the autoprescan routine (PROBE package). In all volunteers, MRS was performed in a three times using conventional MRS (Signa Horizon) with 1 channel coil and upgraded MRS (Echospeed plus with EXCITE) with both 1 channel and 8 channel coil. Using these three different machines and coils, SNRs of the spectra in both phantom and volunteers and (pre)scan time of MRS were compared. Two regions of the human brain (basal ganglia and deep white matter) were examined and relative metabolite ratios (NAA/Cr, Cho/Cr, and mI/Cr ratios) were measured in all volunteers. For all spectra, a STEAM localization sequence with three-pulse CHESS $H_2O$ suppression was used, with the following acquisition parameters: TR=3.0/2.0 sec, TE=30 msec, TM=13.7 msec, SW=2500 Hz, SI=2048 pts, AVG : 64/128, and NEX=2/8 (Signa/Echospeed). Results : The SNR was about over $30\%$ higher in Echospeed machine and time for prescan and scan was almost same in different machines and coils. Reliable spectra were obtained on both MRS systems and there were no significant differences in spectral patterns and relative metabolite ratios in two brain regions (p>0.05). Conclusion : Both conventional and new MRI systems are highly reliable and reproducible for $^1H$ MR spectroscopic examinations in human brains and there are no significant differences in applications for $^1H$ MRS between two different MRI systems.

• Tuberculosis and Respiratory Diseases
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• v.46 no.5
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• pp.697-708
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• 1999

Background : Leukotriene (LT) $C_4$, $D_4$, and $E_4$, the main components of slow-reacting substance of anaphylaxis (SRS-A), have been suggested to play an important role in bronchial asthma such as antigen-induced bronchoconstriction, airway hyperreactivity, and pulmonary eosinophil accumulation. The purpose of this study was to evaluate the effects of treatment with the cysteinyl-LTs (cys-LTs) antagonist, pranlukast on allergen-induced guinea pig asthma model. Methods : Guinea pigs of treatment and placebo groups were sensitized by subcutaneous injection of ovalbumin(OVA) and challenged by inhalation of aerosolized OVA (1% weight/volume OVA). Normal control group did not sensitize with OVA. Oral ingestion of pranlukast and normal saline to the treatment and placebo groups was performed. In the treatment and placebo groups, airway resistance was measured before and after oral ingestion. Serum $LTC_4$ and eosinophilic infiltration of the bronchiolar and peribronchiolar tissues were measured after ingestion in the treatment and placebo groups. Results : Allergen-induced airway constriction developed in 20 (8 in treatment group, 12 in placebo group) among 35 guinea pigs. Airway resistance was significantly decreased at 3 and 6 minutes after OVA challenge in the pranlukast treatment group. In the placebo group, there was no difference of airway resistance between before and after saline ingestion. Serum $LTC_4$ levels showed 348.4 pg/ml in the treatment group, 373.9 pg/ml in the placebo group, and 364.4 pg/ml in the control group. There were no statistically significant difference between treatment and placebo group (p=0.232), and treatment and control group (p=0.501). Eosinophilic infiltrations in the peribronchiolar region per one-microscopic field ($\times$400 high power fields) demonstrated 7.06 in the treatment group, 19.2 in the placebo group, and 4.50 in the control group. There was significant decrement of eosinophilic infiltration in the treatment group which was compared with placebo group (p=0.001). Conclusion : These results demonstrate that pranlukast, a cys-LTs receptor antagonist, can attenuate allergen induced early-phase bronchoconstriction and eosinophilic infiltration in the bronchiolar tissues.

• Tuberculosis and Respiratory Diseases
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• v.45 no.5
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• pp.1012-1021
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• 1998

Background : It is known that airway inflammation is present in most patients with asthma, but the relationship between symptoms and the severity and nature of airway inflammation has not been established. Cough variant asthma is defined as an asthma in which the dominant symptom is cough, and the condition can be successfully treated with inhaled steroids. This study was performed to evaluate the time course of bronchial responsiveness according to an inhaled anti-inflammatory therapy and the factors which affect the resolution of bronchial responsiveness, and an efficacy of nedocromil to cough asthma. Method: A prospective study for the investigation of bronchial responsiveness according to an inhaled anti-inflammatory treatment in sixty-one cough asthmatics was performed. Twenty-three entered budesonide ($400{\mu}g{\times}2/day$), twenty-two entered nedocromil ($4mg{\times}2/day$) and sixteen patients entered combined group. The bronchial hyperresponsiveness (BHR) was estimated by methacholine challenge test using counted breath method. The symptom was estimated by 'symptom score'. Reevaluation of BHR and symptom was performed at 2 month after treatment, and if BHR was not resoluted at this time, regarded as a non-responder, and then follow-up of BHR and symptom was performed at 4- and/or 6 month after treatment. Results: The improvement of BHR and symptom was significant in 2 month (p<0.05), but there was no change of them during follow-up period of 4- and/or 6 month in non-responders. In comparison of allergic markers such as serum total IgE, peripheral eosinophil count and skin test reactivity between responders and non-responders, there was no difference in each other. However, in comparison of other factors such as cumulative pack-years, symptom duration, age, gender, and the initial degree of PC20, there was a significant difference in each other(p<0.05). The percent of patients with the resolution of BHR in 2 month was not different in each group(p=0.95). There was no significant difference in the degree of improvement of BHR and symptom in each group. Conclusion: Bronchial responsiveness and symptom was not significantly improved in non-responders during follow-up period of 4- and/or 6 month. The effect of inhaled nedocromil was equivalent to that of inhaled steroid in cough asthmatics, and the response to combined treatment is not superior to that achieved by either of these agents used alone.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.5-19
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• 1998

Introduction: Direct histologic and bacteriologic examination of a representative specimen of lung tissue is the only certain method of providing an accurate diagnosis in various pulmonary diseases including diffuse pulmonary diseases. The purpose of national survey was to define the indication, incidence, effectiveness, safety and complication of open and thoracoscopic lung biopsy in korea. Methods: A multicenter registry of 37 university or general hospitals equipped more than 400 patient's bed were retrospectively collected and analyzed for 3 years from the January 1994 to December 1996 using the same registry protocol. Results: 1) There were 511 cases from the 37 hospitals during 3 years. The mean age was 50.2 years(${\pm}15.1$ years) and men was more prevalent than women(54.9% vs 45.9%). 2) The open lung biopsy was performed in 313 cases(62%) and thoracoscopic lung biopsy was performed in 192 cases(38%). The incidence of lung biopsy was more higher in diffuse lung disease(305 cases, 59.7%) than in localized lung disease(206 cases, 40.3%) 3) The duration after abnormalities was found in chest X-ray until lung biopsy was 82.4 days(open lung biopsy: 72.8 days, thoracoscopic lung biopsy: 99.4 days). The bronchoscopy was performed in 272 cases(53.2%), bronchoalveolar lavage was performed in 123 cases(24.1%) and percutaneous lung biopsy was performed in 72 cases(14.1%) before open or thoracoscopic lung biopsy. 4) There were 230 cases(45.0%) of interstitial lung disease, 133 cases(26.0%) of thoracic malignancies, 118 cases(23.1%) of infectious lung disease including tuberculosis and 30 cases (5.9 %) of other lung diseases including congenital anomalies. No significant differences were noted in diagnostic rate and disease characteristics between open lung biopsy and thoracoscopic lung biopsy. 5) The final diagnosis through an open or thoracoscopic lung biopsy was as same as the presumptive diagnosis before the biopsy in 302 cases(59.2%). The identical diagnostic rate was 66.5% in interstitial lung diseases, 58.7% in thoracic malignancies, 32.7% in lung infections, 55.1 % in pulmonary tuberculosis, 62.5% in other lung diseases including congenital anomalies. 6) One days after lung biopsy, $PaCO_2$ was increased from the prebiopsy level of $38.9{\pm}5.8mmHg$ to the $40.2{\pm}7.1mmHg$(P<0.05) and $PaO_2/FiO_2$ was decreased from the prebiopsy level of $380.3{\pm}109.3mmHg$ to the $339.2{\pm}138.2mmHg$(P=0.01). 7) There was a 10.1 % of complication after lung biopsy. The complication rate in open lung biopsy was much higher than in thoracoscopic lung biopsy(12.4% vs 5.8%, P<0.05). The incidence of complication was pneumothorax(23 cases, 4.6%), hemothorax(7 cases, 1.4%), death(6 cases, 1.2%) and others(15 cases, 2.9%). 8) The 5 cases of death due to lung biopsy were associated with open lung biopsy and one fatal case did not describe the method of lung biopsy. The underlying disease was 3 cases of thoracic malignancies(2 cases of bronchoalveolar cell cancer and one malignant mesothelioma), 2 cases of metastatic lung cancer, and one interstitial lung disease. The duration between open lung biopsy and death was $15.5{\pm}9.9$ days. 9) Despite the lung biopsy, 19 cases (3.7%) could not diagnosed. These findings were caused by biopsy was taken other than target lesion(5 cases), too small size to interpretate(3 cases), pathologic inability(11 cases). 10) The contribution of open or thoracoscopic lung biopsy to the final diagnosis was defininitely helpful(334 cases, 66.5%), moderately helpful(140 cases, 27.9%), not helpful or impossible to judge(28 cases, 5.6%). Overall, open or thoracoscopic lung biopsy were helpful to diagnose the lung lesion in 94.4 % of total cases. Conclusions: The open or thoracoscopic lung biopsy were relatively safe and reliable diagnostic method of lung lesion which could not diagnosed by other diagnostic approaches such as bronchoscopy. We recommend the thoracoscopic lung biopsy when the patients were in critical condition because the thoracoscopic biopsy was more safe and have equal diagnostic results compared with the open lung biopsy.