• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.569-577
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• 2019

Urban flooding has been a frequent phenomenon in recent years caused by the increase in maximum stormwater runoff arising from abnormal rainfall due to global warming, urban development, and development of lowlands according to population inflows. In order to respond positively against abnormal precipition in the city, it is necessary to check the GWI (Green Water Infra) effect and effectively utilize the existing stormwater detention tanks and treat stormwater to prevent local flooding. In this study, Overflow Type stormwater drainage methods are evaluated as a method of preventing urban flooding in abnormal precipitation using the Dynamic Wave Analysis SWMM (Storm Water Management Model) provided by the United States Environmental Protection Agency. Comparing and analyzing the Upward Watergate Type and Overflow Type, it was analyzed that the Overflow Type reduces the maximum flood discharge by 61 % and the total flood volume by 56 % in the rainfall of Typhoon Kong-rey. The application of the Overflow Type and the natural-pneumatic drainage method to the rainfall of Typhoon Soulik resulted in a 20 % reduction in maximum flood runoff and a 67 % reduction in total flood quantity. Therefore, as a solution to the abnormal rain fall, it is possible to improve the existing stormwater detection tank and install additional facilities. It is expected to be economically possible to strom drainage under limited conditions.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1147-1159
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• 2018

This study focuses on the verification of a rapid protection automation system using an inflatable structure. The inflatable structure is an automatic rapid protection system against human and material damage when the subsea tunnel is flooded. Especially, it is essential for construction and operation of subsea tunnels. In this study, we have experimentally verified the rapid protection automation system using the inflatable structure designed for this problem. In order to verify this, a model tunnel with a 40: 1 reduction ratio was constructed, and air pressure of 0.1 bar and 0.15 bar was injected to divide the tunnel according to the expansion rate at 10 sec and 20 sec. According to the results of the study, the protection efficiency was better at 0.15 bar than 0.1 bar when the expansion structure was expanded, and the protection efficiency and influent control efficiency were different according to the pneumatic injection time of the inflating structure. As a result of this study, it was found that the higher the internal air pressure of the inflated structure and the faster the inflation of rate, the more effectively the inflated structure was inflated. As a result of this study, it is necessary to further study the wedge type structure which is useful for the storage method of expansion structure, shape and expansion derivative, inhibition of expansion structure during protection and control of inflow water.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.282-288
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• 2022

Facial masks have become indispensable in daily life to prevent infection and spread through respiratory droplets in the era of the corona pandemic. To understand how effective two different types of masks (i.e., KF-94 mask and dental mask) are in blocking respiratory droplets, i) we preferentially analyze wettability characteristics (e.g., contact angle and contact angle hysteresis) of filters consisting of each mask, and ii) subsequently observe the dynamic behaviors of microdroplets impacting at high velocities on the filter surfaces. Different wetting properties (i.e., hydrophobicity and hydrophilicity) are found to exhibit depending on the constituent materials and pore sizes of each filter. In addition, the pneumatic conditions for stably and uniformly dispensing microdroplets with a certain volume and impacting behaviors associated with the impacting velocity and filter type change are systematically explored. Three distinctive dynamics (i.e., no penetration, capture, and penetration) after droplet impacting are observed depending on the type of filter constituting the masks and droplet impact velocity. The present experimental results not only provide very useful information in designing of face masks for prevention of transmission of infectious respiratory diseases, but also are helpful for academic researches on droplet impacts on various porous surfaces.

• Analytical Science and Technology
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• v.22 no.5
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• pp.395-406
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• 2009

The determination of iodine in the spent nuclear fuel and the volatile behavior during its acid dissolution have been studied by NAA(neutron activation analysis) and electron probe microanalysis (EPMA). Simulated spent fuels (SIMFUELs) were dissolved in $HNO_3$(1+1) at $90^{\circ}C$ for 8 hours. The iodine remained in a dissolver solution after dissolution, and that condensed in dissolution apparatus and trapped in the adsorbent by volatilization during the dissolution were determined, respectively. The condensed iodine was recovered by the redistillation with $HNO_3$(1+1) after transfer of the dissolver solution. The iodines in the dissolver and redistilled solution were separated by solvent extraction followed by ion exchange or precipitation method and determined by RNAA (radiochemical neutron activation analysis). The ion exchange column and filtration kit used for the isolation of iodine, which were prepared with a polyethylene tube, were used as an insert in the pneumatic tube for neutron irradiation. The iodine volatilized during the dissolution of SIMFUELs was collected in a trapping tube containing Ag-silica gel (Ag-impregnated silica gel) adsorbent, and the distribution of iodine trapped in the adsorbents were determined by EPMA. The adsorbing characteristics shown with the SIMFUELs were compared with those shown with a real spent fuel from the nuclear power plant.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.64-71
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• 2024

The external fuel tank of an aircraft is a main component that can increase the cruising range of the aircraft. It must be able to be stably separated from the pylon in an emergency situation. At this time, a separation load is applied to the fin and the pivot of the external fuel tank. To stably separate the external fuel tank, the structural soundness of the fin and the pivot must be confirmed. In this study, structural tests were conducted to verify the structural integrity of the external fuel tank pin and pivot when the external fuel tank was separated from the aircraft. Results are then presented. In this paper, a test configuration diagram consisting of the hydraulic and load control equipment, data acquisition system, and pneumatic supply unit used in the structural test was explained. Test installation and test load application plan for each test condition were provided. As results of the structural test, it was found that test load and internal pressure of the test specimen were properly controlled within the allowable range in each test. It was confirmed that serious structural defects in the test specimen did not occur under required load conditions. In conclusion, through structural test for design limit load and design ultimate load, it was proven that the fin and pivot of the external fuel tank for aircraft covered in this study had sufficient structural strength.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.27-47
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• 1992

Engineers have developed new instruments that aid in diagnosis and therapy Ultrasonic imaging has provided a nondamaging method of imaging internal organs. A complex transducer emits ultrasonic waves at many angles and reconstructs a map of internal anatomy and also velocities of blood in vessels. Fast computed tomography permits reconstruction of the 3-dimensional anatomy and perfusion of the heart at 20-Hz rates. Positron emission tomography uses certain isotopes that produce positrons that react with electrons to simultaneously emit two gamma rays in opposite directions. It locates the region of origin by using a ring of discrete scintillation detectors, each in electronic coincidence with an opposing detector. In magnetic resonance imaging, the patient is placed in a very strong magnetic field. The precessing of the hydrogen atoms is perturbed by an interrogating field to yield two-dimensional images of soft tissue having exceptional clarity. As an alternative to radiology image processing, film archiving, and retrieval, picture archiving and communication systems (PACS) are being implemented. Images from computed radiography, magnetic resonance imaging (MRI), nuclear medicine, and ultrasound are digitized, transmitted, and stored in computers for retrieval at distributed work stations. In electrical impedance tomography, electrodes are placed around the thorax. 50-kHz current is injected between two electrodes and voltages are measured on all other electrodes. A computer processes the data to yield an image of the resistivity of a 2-dimensional slice of the thorax. During fetal monitoring, a corkscrew electrode is screwed into the fetal scalp to measure the fetal electrocardiogram. Correlations with uterine contractions yield information on the status of the fetus during delivery To measure cardiac output by thermodilution, cold saline is injected into the right atrium. A thermistor in the right pulmonary artery yields temperature measurements, from which we can calculate cardiac output. In impedance cardiography, we measure the changes in electrical impedance as the heart ejects blood into the arteries. Motion artifacts are large, so signal averaging is useful during monitoring. An intraarterial blood gas monitoring system permits monitoring in real time. Light is sent down optical fibers inserted into the radial artery, where it is absorbed by dyes, which reemit the light at a different wavelength. The emitted light travels up optical fibers where an external instrument determines O2, CO2, and pH. Therapeutic devices include the electrosurgical unit. A high-frequency electric arc is drawn between the knife and the tissue. The arc cuts and the heat coagulates, thus preventing blood loss. Hyperthermia has demonstrated antitumor effects in patients in whom all conventional modes of therapy have failed. Methods of raising tumor temperature include focused ultrasound, radio-frequency power through needles, or microwaves. When the heart stops pumping, we use the defibrillator to restore normal pumping. A brief, high-current pulse through the heart synchronizes all cardiac fibers to restore normal rhythm. When the cardiac rhythm is too slow, we implant the cardiac pacemaker. An electrode within the heart stimulates the cardiac muscle to contract at the normal rate. When the cardiac valves are narrowed or leak, we implant an artificial valve. Silicone rubber and Teflon are used for biocompatibility. Artificial hearts powered by pneumatic hoses have been implanted in humans. However, the quality of life gradually degrades, and death ensues. When kidney stones develop, lithotripsy is used. A spark creates a pressure wave, which is focused on the stone and fragments it. The pieces pass out normally. When kidneys fail, the blood is cleansed during hemodialysis. Urea passes through a porous membrane to a dialysate bath to lower its concentration in the blood. The blind are able to read by scanning the Optacon with their fingertips. A camera scans letters and converts them to an array of vibrating pins. The deaf are able to hear using a cochlear implant. A microphone detects sound and divides it into frequency bands. 22 electrodes within the cochlea stimulate the acoustic the acoustic nerve to provide sound patterns. For those who have lost muscle function in the limbs, researchers are implanting electrodes to stimulate the muscle. Sensors in the legs and arms feed back signals to a computer that coordinates the stimulators to provide limb motion. For those with high spinal cord injury, a puff and sip switch can control a computer and permit the disabled person operate the computer and communicate with the outside world.

• Journal of Hospice and Palliative Care
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• v.8 no.2
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• pp.152-155
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• 2005

Purpose: The lower extremity edema (LEE) is a common distressful symptom in advanced cancer patients and is hard to manage. We analyze the characteristics of LEE in patients with advanced cancer to provide the basic information of causes and adequate management. Methods: Physical examination, assessment of the location and severity of edema, blood chemistry (albumin, creatinine), Doppler Sono for patients with suspecting deep vein thrombosis (DVT), and abdomen CT scan for patient with suspecting lymph edema were performed. Severity of edema was classified according to NCI lymph edema scaling and improvement was defined as lowering at least 1 grade of edema after management. Results: Among 154 patient who had been admitted to Hospice Ward from Mar 2003 to Jan 2004, 33 had LEE, and 6 had both upper extremity edema and LEE except generalized edema. Their underlying cancers were stomach (7), lung (6), biliary tract (5), liver (5), colorectal (5), pancreas (2), and others (9). There were 12 patient with grade I, 20 patients with grade II, and 7 patients with grade III edema. The causes were hypoalbuminemia (11), lymph edema (10), DVT (7), obstruction of inferior vena cava (IVC) or portal vein (6), and dependent edema (5). The common managements were including leg elevation and diuretics. Elastic stocking was applied for patients with DVT and leg massage and pneumatic compression was used for lymph edema. The 2/3 patients were improved after management. Conclusion: The incidence of LEE in terminal cancer pts was high (25.3%) and their causes were variable including lymph edema, DVT, hypoalbuminemia and dependent edema. Active noninvasive management according to causes could result in good palliation.

• Journal of Chest Surgery
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• v.40 no.3 s.272
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• pp.168-179
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• 2007

Background: The recent trend of an increasing number of patients with acute cardiogenic shock or chronic congestive heart failure following myocardial infarction, as well as the considerable number who can not be weaned from cardiopulmonary bypass after open heart surgery, call for immediate efforts to develop affordable ventricular assist devices that are suitable for the Korean physique. Recently, a pneumatic pulsatile ventricular assist device (VAD), named DKUH-75, has been developed by the Department of Biomedical Engineering, in collaboration with the Department of Thoracic and Cardiovascular Surgery of Dankook University College of Medicine. The feasibility of the DKUH-75 VAD was evaluated on the bases of common hemodynamic variables and echocardiographic measurements in pigs, which are subjected to an acute cardiogenic shock state following myocardial infarction, using a novel coronary artery ligation method employing the ischemic preconditioning concept. Material and Method: Acute cardiogenic shock was induced in 10 Yorkshire Landrace Duroc strain pigs by ligating the left anterior descending coronary artery via an ischemic preconditioning process. The hemodynamic variables were monitored, with epicardial echocardiographic measurements performed before and one hour after the ligation. The DKUH-75 VAD was implanted into 5 pigs one hour after the onset of the shock. The hemodynamic variables and echocardiographic measurements were taken one hour after installation of the VAD. Result: The systolic, diastolic and mean systemic arterial pressures were significantly decreased in all the experimental animals one hour after the ligation. The systolic, diastolic and mean pulmonary arterial pressures were increased (Eds note: this completely contradicts the preceding statement? However, if you mean the non-experimental animals this should be stated?). The left ventricular end diastolic pressure (LVEDP) was increased, but the cardiac index decreased, An increase in the left ventricular end systolic dimension and decreases in the fractional shortening and ejection fraction were observed all animals one hour after the coronary artery ligation. In all 5 of the VAD implanted pigs, the systolic and mean systemic arterial pressures were increased, and the pulmonary arterial pressures decreased one hour after the implantation; the LVEDP decreased, but the cardiac index was significantly increased, In the echocardiographic measurements, the left ventricular end systolic dimension decreased after the implantation of the VAD, but the fractional shortening and ejection fraction significantly increased. Conclusion: Significant improvements in the hemodynamic variables and echocardiographic measurements were observed in the 5 VAD implanted animals one hour after installation, which had been subjected to an acute cardiogenic shock state by ligation of the coronary artery, indicating that the DKUH-75 VAD could help in the recovery of the myocardial function. This suggests that the DKUH-75 VAD is feasible in the short term in relation to an acute cardiogenic shock state due to myocardial infarction.

• The Korean Journal of Pain
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• v.1 no.2
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• pp.214-222
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• 1988

With the arm in hyperabduction, we have carried out 525 procedures of supraclavicular brachial plexus block from Aug. 1976 to June 1980, whereas block with the arm in adduction has been customarily performed by other authors. The anesthetic procedure is as follows: 1) The patient lies in the dorsal recumbent position without a pillow under his head or shoulder. His arm is hyperabducted more than a 90 degree angle from his side, and his head is turned to the side opposite from that to be blocked. 2) An "X" is marked at a point 1 cm above the mid clavicle, immediately lateral to the edge of the anterior scalene muscle, and on the palpable portion of the subclavian artery. The area is aseptically prepared and draped. 3) A 22 gauge 3.5cm needle attached to a syringe filled with 2% lidocaine (7~8mg/kg of body weight) and epineprine(1 : 200,000) is inserted caudally toward the second portion of the artery where it crosses the first rib and parallel with the lateral border of the muscle until a paresthesia is obtained. 4) Paresthesia is usually elicited while inserting the needle tip about 1~2 em in depth. If so, the local anesthetic solution is injected after careful aspiration. 5) If no paresthesia is elicited, the needle is withdrawn and redirected in an attempt to elicit paresthesia. 6) If, after several attempts, no paresthesia is obtained, the local anesthetic solution is injected into the perivascular sheath after confirming that the artery is not punctured. 7) Immediately after starting surgery, Valium is injected for sedation by the intravenous route in almost all cases. The age distribution of the cases was from 11 to 80 years. Sex distribution was 476 males and 49 females (Table 1). Operative procedures consisted of 103 open reductions, 114 skin grafts combined with spinal anesthesia in 14, 87 debridements, 75 repairs, i.e. tendon (41), nerve(32), and artery (2), 58 corrections of abnormalities, 27 amputations above the elbow (5), below the elbow (3) and fingers (17), 20 primary closures, 18 incisions and curettages, 2 replantations of cut fingers. respectively (Table 2). Paresthesia was obtained in all cases. Onset of analgesia occured within 5 minutes, starting in the deltoid region in almost all cases. Complete anesthesia of the entire arm appeared within 10 minutes but was delayed 15 to 20 minutes in 5 cases and failed in one case. Thus, our success rate was nearly 100%. The duration of anesthesia after a single injection ranged from $3\frac{1}{2}$ to $4\frac{1}{2}$, hours in 94% of the cases. The operative time ranged from 0.5 to 4 hours in 92.4% of the cases(Table 3). Repeat blocks were carried out in 33 cases when operative times which were more than 4 hours in 22 cases and the others were completed within 4 hours (Table 4). Two patients of the 33 cases, who received microvasular surgery were injected twice with 2% lidocaine 20 ml for a total of $13\frac{1}{2}$ hours. The 157 patients who received surgery on the forearms or hands had pneumatic tourniquets (250 torrs) applied without tourniquet pain. There was no pneumothorax, hematoma or phrenic nerve paralysis in any of the unilateral and 27 bilateral blocks, but there was hoarseness in two, Horner's syndrome in 11 and shivering in 7 cases. No general seizures or other side effects were observed. By 20ml of 60% urcgratin study, we confirm ed the position of the needle tip to be in a safer position when the arm is in hyperabduction than when it is in adduction. And also that the humoral head caused some obstraction of the distal flow of the dye, indicating that less local anesthetic solution would be needed for satisfactory anesthesia. (Fig. 3,4).

• Tuberculosis and Respiratory Diseases
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• v.43 no.5
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• pp.755-762
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• 1996

Background : Continuous positive airway pressure(CPAP) is doubtlessly using as a medical treatment of choice for patients with obstructive sleep apnea (OSA) syndrome. CPAP is effective in OSA patients as a physical "pneumatic pressure splint" mechanism. We have done this study for two purposes, first to seek for the factors to determine the optimal CPAP titer, second to predict the minimal CPAP titer using the determined factors. Methods: We studied a 72 OSA patients who were treated with CPAP. All of them were studied by using a two nights polysomnographic rests in hospital. We compared the patients requiring CPAP over $10cmH_2O$ with those who required CPAP under 5cm $H_2O$ to determine the factors affecting the minimal CPAP titer. Results : The high CPAP group is characterized by a significantly higher body mass index(BMI), apnea index(AI) and apnea and hyponea index(AHI) and significantly lower lowest $SaO_2$. Regression analysis using the optimal four variables resulted in the following prediction equation for CPAP titer. CPAPtiter=8.382 + 0.064 ${\times}$ BMI + 0.077 ${\times}$ AI - 0.004 ${\times}$ AHI - 0.077 ${\times}$ lowest $SaO_2$ When this regression equation was applied to the 72 patients, the mean CPAP titer as predicted by the above equation was $7.80{\pm}2.96$ mmHg. Compared this value with actually determined CPAPtiter, $7.93{\pm}4.00$mmHg, there was no significant difference between the two values. Conclusion: Obesity, apnea severity and lowest Sa02 were strongly correlated with CPAP titer. Linear regression equation for CPAP titer using these indices predicted very closely the actually measured values in the sleep laboratory.