• Journal of Chest Surgery
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• v.36 no.3
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• pp.123-130
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• 2003

Background: In order to develop the acute heart failure model for the animal experiment of the pneumatic ventricular assist device, we decided to use young pig whose coronary artery distribution is almost the same as humans and also very cheap in price. The purpose of this study is to develop stable, reproducible acute ischemic heart failure model in swine using coronary artery ligation method. Material and Method: Five young pigs whose weights are the same as adult humans are under experiment. Each pig was under endotracheal intubation and connected to a mechanical ventilator. Through left lateral thoracotomy, we exposed the heart and induced ischemic heart failure by coronary artery ligation. The ligation began at the distal part of the left anterior descending coronary artery. After 5 minutes of initial ligation we reperfused the artery and then re-ligated. Before and after each ligation-reperfusion procedure we assessed the left ventricular end-diastolic pressure, arterial pressure, and cardiac index. We also measured left ventricular end-diastolic dimension, end-systolic dimension, fractional shortening, ejection fraction using intraoperative epicardial echocardiography. After appropriate heart failure was established with sequential (from distal part of LAD to proximal location) ligation-reperfusion-ligation procedure, we inserted the ventricular assist device and operated. Result: We established stable acute ischemic heart failure in 3 of 5 young pigs with this sequential ligation-reperfusion-ligation procedure, and could maintained 50% less ejection fraction before the procedure according to intraoperative epicardial echocardiography. We also observed no ventricular arrhythmia usually associated with simple coronary artery ligation in large animals and no cardiac arrest associated with ventricular arrhythmia or myocardial stunning. In pathologic specimen, we observed scattered ischemic myocardium in all around the ischemic field induced by coronary artery ligation. Conclusion: Under the concept of ischemic preconditioning, we developed safe and reproducible acute ischemic heart failure model in swine using sequential coronary artery ligation-reperfusion-ligation method.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.1 no.1
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• pp.100-106
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• 1998

Purpose: Ceftriaxone, a potent parenteral third-generation semisynthetic cephalosporin is widely used for the treatment of a variety of bacterial infections in both children and adult. Review of recent data indicates that ceftriaxone treatment has been associated with the development of reversible biliary pseudolithiasis and that is thought by many to be a benign process. Despite, several reports describe patients with ceftriaxone pseudolithiasis who required cholecystectomy for presumed acute cholecystitis. In this study we evaluated the incidence, risk factors, and prognosis of gallbladder pseudolithiasis after ceftriaxone treatment. Methods: Between march, 1997 and January, 1998, any child admitted to the Children's hospital of National University of Seoul and prescribed ceftriaxone for probable or definite bacterial infection were eligible for the study. 21 of them had ultrasound examination on the 2~12 days later after the start of ceftriaxone treatment, 8 of whom documented gallbladder precipitates or pseudolithiasis during treatment by serial abdominal ultrasound. Repeat abdominal ultrasound was performed 10~80 days later after the end of ceftriaxone treatment. The children with underlying liver disease or decreased renal function were excluded in this study. Results: 1) 21 children had ultrasound examinations of gallbladder during ceftriaxone treatment and 8 (38%) of them acquired pseudolithiasis. 2) The patients who developed gallbladder pseudolithiasis were significantly older ($6.3{\pm}2.9$ yr. vs $2.2{\pm}3.1$ yr.)(p<0.05), and older than 24 months were probably the significant risk associated with this phenomenon (p<0.05). However, no significant differences in sex, type of infection, fasting, and ceftriaxone treatment regimen (dose, duration of therapy). 3) The abnormality found on gallbladder ultrasonography was a strikingly hyperechogenic material with post-acoustic shadowing in 5 patients without post-acoustic shadowing in 3 patients 4) Follow up of gallbladder ultrasound was performed in 6 patients after cessation of ceftriaxone treatment. Sonographic abnormalities completely resolved within 14 days post cessation of therapy in 2 patients; 30 days, 1 patient; 80 days, 3 patients. Conclusions: We suggest that routine abdominal ultrasound should be considered in all children who received high dose ceftriaxone in more than 24 months of age and developed hepatobiliary symptoms during or just after ceftriaxone treatment.

• Progress in Medical Physics
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• v.19 no.4
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• pp.269-275
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• 2008

Although MR imaging is generally applicable to depict knee joint deterioration it, is sometimes occurred to mis-read and mis-diagnose the common knee joint diseases. In this study, we employed magnetization transfer ratio (MTR) method to improve the diagnosis of the various knee joint diseases. Spin-echo (SE) T2-weighted images (TR/TE 3,400-3,500/90-100 ms) were obtained in seven cases of knee joint deterioration, FSE T2-weighted images (TR/TE 4,500-5,000/100-108 ms) were obtained in seven cases of knee joint deterioration, gradient-echo (GRE) T2-weighted images (TR/TE 9/4.56/$50^{\circ}$ flip angle, NEX 1) were obtained in 3 cases of knee joint deterioration, In six cases of knee joint deterioration, fat suppression was performed using a T2-weighted short T1/tau inverse recovery (STIR) sequence (TR/TE =2,894-3,215 ms/70 ms, NEX 3, ETL 9). Calculation of MTR for individual pixels was performed on registration of unsaturated and saturated images. After processing to make MTR images, the images were displayed in gray color. For improving diagnosis, three-dimensional isotropic volume images, the MR tristimulus color mapping and the MTR map was employed. MTR images showed diagnostic images quality to assess the patients' pathologies. The intensity difference between MTR images and conventional MRI was seen on the color bar. The profile graph on MTR imaging effect showed a quantitative measure of the relative decrease in signal intensity due to the MT pulse. To diagnose the pathologies of the knee joint, the profile graph data was shown on the image as a small cross. The present study indicated that MTR images in the knee joint were feasible. Investigation of physical change on MTR imaging enables to provide us more insight in the physical and technical basis of MTR imaging. MTR images could be useful for rapid assessment of diseases that we examine unambiguous contrast in MT images of knee disorder patients.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.42-49
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• 2004

Purpose : The quantization noise in magnetic resonance imaging (MRI) systems is analyzed. The signal-to-quantization noise ratio (SQNR) in the reconstructed image is derived from the level of quantization in the signal in spatial frequency domain. Based on the derived formula, the SQNRs in various main magnetic fields with different receiver systems are evaluated. From the evaluation, the quantization noise could be a major noise source determining overall system signal-to-noise ratio (SNR) in high field MRI system. A few methods to reduce the quantization noise are suggested. Materials and methods : In Fourier imaging methods, spin density distribution is encoded by phase and frequency encoding gradients in such a way that it becomes a distribution in the spatial frequency domain. Thus the quantization noise in the spatial frequency domain is expressed in terms of the SQNR in the reconstructed image. The validity of the derived formula is confirmed by experiments and computer simulation. Results : Using the derived formula, the SQNRs in various main magnetic fields with various receiver systems are evaluated. Since the quantization noise is proportional to the signal amplitude, yet it cannot be reduced by simple signal averaging, it could be a serious problem in high field imaging. In many receiver systems employing analog-to-digital converters (ADC) of 16 bits/sample, the quantization noise could be a major noise source limiting overall system SNR, especially in a high field imaging. Conclusion : The field strength of MRI system keeps going higher for functional imaging and spectroscopy. In high field MRI system, signal amplitude becomes larger with more susceptibility effect and wider spectral separation. Since the quantization noise is proportional to the signal amplitude, if the conversion bits of the ADCs in the receiver system are not large enough, the increase of signal amplitude may not be fully utilized for the SNR enhancement due to the increase of the quantization noise. Evaluation of the SQNR for various systems using the formula shows that the quantization noise could be a major noise source limiting overall system SNR, especially in three dimensional imaging in a high field imaging. Oversampling and off-center sampling would be an alternative solution to reduce the quantization noise without replacement of the receiver system.

• Clinical and Experimental Pediatrics
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• v.48 no.10
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• pp.1139-1142
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• 2005

Purpose : The aim of this study was to investigate the epidemiologic and clinical profiles of Kawasaki disease(KD) in children 8 years of age and older. Methods : For the epidemiologic study of KD in Korea, data of total 15,692 KD patients were collected from 1994 to 2002 on a 3 year basis, by the retrospective survey. Among them, data of 211 KD patients 8 years of age and older were analyzed and compared with those of the KD patients less than 8 years of age. Results : 211 patients 8 years of age and older(1.3% of total KD patients) with the mean age of 9.8 years, included 142 cases aged 8-10 years, 42 cases aged 10-12 years, and 27 cases aged 12 years and older. The male-to-female ratio was 1.9 : 1, the recurrence rate was 3.8%, and the prevalence of cases in sibling was zero. Coronary arterial(CA) abnormalities were detected by echocardiography in 25.4% of the cases, including 7.6% of CA aneurysm cases. There was 1 case complicated by myocardial infarction. Conclusion : Comparing with the data of the KD patients less than 8 years of age, data of 211 patients 8 years of age and older showed significantly higher incidences of CA abnormalities(25.4% : 19.8%) and CA aneurysms(7.6% : 4.0%).

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.87-91
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• 2015

As negative effects of climate change have been visualized and its direct damages to economy have been realized, the global efforts to respond to climate change by reducing greenhouse gas emission were accelerated. Korea's Carbon Footprint Labeling gets a lot of attention as one of the effective methods to contribute to national GHG reduction goal, and for enterprises to show customers how much effort the company put into global warming prevention. Consumers' interest on low-carbon products has been increasing. This study uses Life Cycle Assessment method to calculate the amount of carbon emission of dishwashing detergent, LG Household & Healthcare, which reduced carbon emissions by using raw materials that has relatively lower environment load. Life Cycle Assessment Method is based on guidelines of Carbon Footprint Labeling, Ministry of Environment, and pre-manufacturing, manufacturing, and disposal phase are included while use phase of the product is excluded from assessment. In order to understand the effects of eco-design on carbon emissions, the dishwashing detergent's carbon emissions are compared before and after the change of main raw materials. The result shows the improvement from $0.47kgCO_2eq/kg$ to $0.38kgCO_2eq/kg$ per product, and this means the main raw materials' carbon emissions could be reduced by around 9.4%, which is equivalent to 916tons of GHG emissions per year.

• Journal of Chest Surgery
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• v.32 no.6
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• pp.525-531
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• 1999

Background: We analyzed five hundred patients who underwent either isolated or concomitant coronary artery bypass grafting(CABG) between November 1981 and June 1997. Material and Method: There were 330 males and 170 females with a mean age of 57.4$\pm$8.9 years. To evaluate the preoperative status, we performed electrocardiograghy, echocardiography, MIBI scan, Duplex sonogram, common blood test including CK and LDH and coronary angiography. Result: Preoperative clinical diagnoses were unstable angina in 282 (56.4%), stable angina in 141 (28.2%), postinfarction angina in 58 (11.6%), acute myocardial infarction in 8 (1.6%), variant angina in 7 (1.4%) and failed percutaneous transluminal coronary angioplasty in 4 (0.8%) patients. Preoperative angiographic diagnoses were three-vessel disease in 263 (52.6%), two-vessel disease in 93 (18.6%), one-vessel disease in 71 (14.2%), left main disease in 68 (13.6%), and others in 5 (1.0%) patients. Patients had various risk factors for coronary disease, and the frequency of the risk factors such as hypertension, diabetes and smoking showed increasing tendency year by year. We used saphenous vein grafts in 1143, internal thoracic artery grafts in 442, radial artery graft in 17, and gastroepiploic artery graft in 1 anastomosis. The mean number of grafts was 3.2$\pm$1.2 per patient. Concomitant operations were prosthetic valve replacement or valvuloplasty in 31, coronary endarterectomy and angioplasty in 27, left main coronary angioplasty in 13, carotid endarterectomy in 5, and neurologic problems, bleeding, and perioperative myocardial infarction. The mean follow-up period was 25$\pm$23 months and there were 5 cases of reoperation. Conclusion: We hope that the surgical results would improve with the accumulation of experience, application of new myocardial protection technique, and timely intervention of mechanical assisted devices.

• Journal of the Korean earth science society
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• v.26 no.1
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• pp.93-105
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• 2005

Climatological characteristics in the variation of soil temperatures in Korea were investigated using Korea Meterological Administration's observation data. And the impacts of soil moisture on the variation of soil temperature were examined using observed precipitation data. The climatological averages of soil temperatures are ranged from 14.4 to $15.0^{\circ}C$ regardless of depths. And they showed an latitudinal gradient with a warm temperature at the southern region and 'U' shape as in the air temperature with a high value along the coastal region. The relatively higher heat capacity and low conductivity of soil compared to those of the air resulted in the significant delay of the maximum and minimum date with depth. As a results, soil acts as a heat source during winter while a heat sink during summer. Global warming and urban heat island have increased the soil temperatures with an average rate $0.3\~0.5^{\circ}C/10-year$ as in the air temperature during last 30 years $(1973\~2002)$. However, the warming rate is maximized during spring contrary to the winter in the air temperature. The temporal variation of soil temperatures is strongly affected by that of soil moisture through an modification of the heat capacity and heat convection. In general, the increased soil moisture clearly decreased the temporal variations and increased the deep layer soil temperatures during cold season.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.2
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• pp.160-168
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• 2000

Purpose: The purpose of this study was to evaluate the clinical and abdominal ultrasonogra- phic(US) features of spontaneously reduced transient small bowel intussusception in chlidren. Methods: We retrospectively reviewed the clinical and US findings of 98 children with intussusception who were admitted to the Pediatric Department of Ulsan Dong-Kang General Hospital from Mar. 1999 to Feb. 2000. Results: 1) Among 98 cases, there were 12 cases (12.3%) of transient small bowel intussusception(TSBI) and 86 cases (87.7%) of classic intussusception (CI). 2) The peak incidence of age in TSBI was over 3 years, which was older than that in CI. With regard to sex distribution, male predominated in both type. 3) Clinical symptoms and signs including cyclic irritability, vomiting, bloody stool, and abdominal mass in TSBI group were less common than those in CI group (41.7%, 33.4%, 0.0%, 0.0% vs 91.9%, 59.3%, 41.9%, 26.7%, respectively) but persistent abdominal pain was more common in TSBI group than in CI group (58.5% vs 11.2%). 4) The size of total target sign and surrounding peripheral hypoechoic rim of TSBI group on US were smaller than those of CI group ($11.95{\pm}2.61$ mm, $2.08{\pm}1.15$ mm vs $26.91{\pm}5.98$ mm, $7.86{\pm}2.77$ mm, respectively). 5) Concomittant illness was found more frequently in TSBI group than in CI group (66.7% vs 26.7%). 6) All case of TSBI group were reduced spontaneouly, which were confirmed by US, but none of CI group. Conclusion: Transient small bowel intussusception is probably more common than generally thought and its clinical and US findings is quite different from classical obstructing intussus-ception. Because all of our cases resulted in spontaneous reduction, we recommend careful observation and repeat examination rather than an immediate operation in transient small bowel intussusception.

• Investigative Magnetic Resonance Imaging
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• v.9 no.2
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• pp.101-108
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• 2005

Purpose : Early detection of small brain metastases is important. The purpose of this study was to compare the detectability of brain metastases according to the size between 1.5 T and 3.0 T MRI. Materials and Methods : We reviewed 162 patients with primary lung cancer who were examined for TNM staging. After administration of double dose of Gd-DTPA, MR imaging was performed with SPGR by 3.0 T MRI and then with T1 SE sequence by 1.5 T MRI. In each patient, three readers performed qualitative assessment. Sensitivity, positive predictive value, and diagnostic accuracy were calculated in 3.0 T and 1.5 T MRI according to size. Using the signal intensity (SI) measurements between the metastatic nodules and adjacent tissue, nodule-to-adjacent tissue SI ratio was calculated. Results : Thirty-one of 162 patients had apparent metastatic nodules in the brain at either 1.5 T or 3.0 T MR imaging. 143 nodules were detected in 3.0 T MRI, whereas 137 nodules were detected at 1.5 T MRI. Six nodules, only detected in 3.0 T MRI, were smaller than 3.0 mm in dimension. Sensitivity, positive predictive value, and diagnostic accuracy in 3.0 T MRI were 100 %, 100 %, and 100 % respectively, and in 1.5 T MRI were 95.8%, 88.3%, and 85.1% respectively. SI ratio was significantly higher in the 3.0 T MRI than 1.5 T MRI (p=0.025). Conclusion : True positive rate of 3.0 T MRI with Gd-DTPA was superior to 1.5 T MRI with Gd-DTPA in detection of metastatic nodules smaller than 3.0 mm.