• Explosives and Blasting
• /
• v.30 no.2
• /
• pp.29-42
• /
• 2012

Variables influencing the free face movement due to rock blasting include the physical and mechanical properties, in particular the discontinuity characteristics, explosive type, charge weight, burden, blast-hole spacing, delay time between blast-holes or rows, stemming conditions. These variables also affects the blast vibration, air blast and size of fragmentation. For the design of surface blasting, the priority is given to the safety of nearby buildings. Therefore, blast vibration has to be controlled by analyzing the free face movement at the surface blasting sites and also blasting operation needs to be optimized to improve the fragmentation size. High-speed digital image analysis enables the analyses of the initial movement of free face of rock, stemming optimality, fragment trajectory, face movement direction and velocity as well as the optimal detonator initiation system. Even though The high-speed image analysis technique has been widely used in foreign countries, its applications can hardly be found in Korea. This thesis aims at carrying out a fundamental study for optimizing the blast design and evaluation using the high-speed digital image analysis. A series of experimentation were performed at two large surface blasting sites with the rock type of shale and granite, respectively. Emulsion and ANFO were the explosives used for the study. Based on the digital images analysis, displacement and velocity of the free face were scrutinized along with the analysis fragment size distribution. In addition, AUTODYN, 2-D FEM model, was applied to simulate detonation pressure, detonation velocity, response time for the initiation of the free face movement and face movement shape. The result show that regardless of the rock type, due to the displacement and the movement velocity have the maximum near the center of charged section the free face becomes curved like a bow. Compared with ANFO, the cases with Emulsion result in larger detonation pressure and velocity and faster reaction for the displacement initiation.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.1
• /
• pp.305-316
• /
• 2013

To find out if modern roundabout is still effective under drivers behavior and driving conditions in Busan Metropolitan City, the effects before and after introduction of roundabout were analyzed. According to analysis on velocity profile at roundabout, velocity deviation decreased, and average vehicle speed was close to design speed. As a result, it has been confirmed that most roundabouts were properly built. In terms of traffic operation, average vehicle speed improved by 87.2% when a traffic intersection was replaced by a roundabout. therefore, it has been found out that the introduction of roundabout has a positive effect on increasing vehicle speed by reducing traffic congestion. In addition, annual benefits expected from the replacement from a traffic intersection to a roundabout were KRW 872 million as follows; KRW 410 million in traffic communication, KRW 39 million in transportation safety, KRW 255 million in energy saving, KRW 95 million in reduction of air pollution and KRW 73 million in reduction of traffic signal installation cost. In other words, if 10% (193 spots) of all traffic intersections (1,926 spots in total) in Busan City are replaced by roundabouts, the municipal authority would be able to save about KRW 168.3 billion. According to analysis on the benefits expected from the installation of roundabouts compared to the investment cost for traffic intersections, about KRW 679 million could be saved per roundabout. Considering 10% of all traffic intersections in the City of Busan, about KRW 131 billion could be saved annually. The traffic accidents in roundabout usually occur because drivers aren't aware of right-of-way rules. Once the right-of-way rules settle, the number of traffic accidents would significantly decrease. In addition, it is urgent to promote education and campaign for drivers, pedestrians and bikers on the roundabout.

• Journal of Animal Environmental Science
• /
• v.10 no.3
• /
• pp.141-154
• /
• 2004

The solar powered water pump is very ideal equipment because solar power is more intensive when the water is more needed in summer and it is very helpful in the rural area, in which the electrical power is not available. The average so]ar radiation energy is 3.488 kWh/($m^2{\cdot}day$) in Korea. In this study, the automatic control logic and system of the water pump driven by the radiation energy were studied, designed, assembled, tested and analyzed for realizing the solar powered water pump. The experimental system was operated automatically and the cycle was continued. The average quantity of the water pumped per cycle was about 5,320 cc. The cycle time was about 4.9 minutes. The thermal efficiency of the system was about $0.030\%$. The pressure level of the n-pentane vapour in flash tank was 150$\%$450 hPa(gauge) which was set by the computer program for the control of the vapour supply. The pressure in the condenser and air tank during cycles was maintained as about 600 hPa and 1,200 hPa respectively. The water could be pumped by the amount of 128kg/($m^2{\cdot}day$) with the efficiency of $0.1\%$ and the pumping head of 10 m for the average solar energy in Korea.

• Journal of Bio-Environment Control
• /
• v.25 no.2
• /
• pp.89-94
• /
• 2016

This study was conducted to determine the optimum nutrient solution, pH, irrigation interval, light intensity and planting density to growth of common ice plant (Mesembryanthemum crystallinum L.) in a closed-type plant production system. Three-band radiation type fluorescent lamps with a 12-h photoperiod were used. Nutrient film technique systems with three layers were used for the plant growth system. Environmental conditions, such as air temperature, relative humidity and $CO_2$ concentration were controlled by an ON/OFF operation. Treatments were comparison of the nutrient solution of Horticultural Experiment Station in Japan (NHES) and the nutrient solution of Jeju National University (NJNU), pH 6.0 and 7.0, irrigation interval 5 min and 10 min, light intensity 90 and $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and within-row spacing 10 cm, 15 cm, 20 cm and 25 cm with between-row spacing 15 cm. Optimum macronutrients were composed N 7.65, P 0.65, K 4.0, Ca 1.6 and Mg $1.0mM{\cdot}L^{-1}$. There were no significant interactions between pH 6.0 and 7.0 about shoot fresh weight and shoot dry weight of common ice plant. Irrigation interval 5 min and 10 min was also the same result. Shoot fresh weight and shoot dry weight were highest at $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Shoot fresh weight and shoot dry weight were decreased according to increasing the planting density. From the above results, we concluded that optimum nutrient solution, optimum levels of pH, irrigation interval, light intensity and planting density were 6.0-7.0 and 10 min, $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and $15{\times}15cm$, respectively for growth of common ice plant in a closed-type plant production system.

• Journal of Chest Surgery
• /
• v.29 no.8
• /
• pp.916-922
• /
• 1996

In patients with pleural adhesion, video-assisted thoracic surgery (VATS) has been regarded as a contra- indication. When such adhesions were found during a thoracoscopic trial, the thoracotomy proceeded with for fear of parenchymal Injury and bleeding. We had a question whether or not thoracoscopic surgery should be done in such pleural adhesions. Of the 226 consecutive thoracoscopic surgeries from Jul. 1992 through Sep. 1995, pleural adhesions were detected intraoperatively in 50 cases (22.1%): a detailed breakdown is as follows: pneumothorax (16 cases), pleural disease (15), benign pulmonary nodule(7), mediastinal mass(5), hyperhidrosis (2), diffuse parenchymal or interstitial lung disease (2), bronchiectasis(2), and primary lung cancer(1). We classified pleural adhesions according to their extent and severity. Extent is categorized as the involved area of the lung: degree 1, II, or III; severity is given one of four grades: mild, moderate, severe, or ve y severe. In cases of very severe severity requiring decortication, the possibility of VATS was excluded. Of the 50 cases, mild adhesions were detected in 15 cases(30.0%), moderate in 29 (58.0%), and severe in 6 (12.0%). As for the extent of the adhesions, 8 cases (16.0%) were categorized as degree 1, 32 cases (64. 0%) as degree II, and 10 cases (20.0%) as degree III. For patients with pleural adhesions, the operation time, the chest tube indwelling time, and the postoperative hospital stay were all longer than for patients in the non-adhesion group. Postoperative complications, namely prolonged air-leakage and pleural drain- age, were more common (18.0% and 6.0%, respectively) than in the non-adhesion group (5.1% and 1.7%, respectively). Only two bronchiectatic patients (4%) were converted to an open thoracotomy because of in- ability to control bleeding. Although complications were encountered more frequently in the group with adhesions, patients were still able to enjoy the benefi s of thoracoscopic surgery. It is advisable to proceed with thoracoscopic surgery even in cases of unpredicted pleural adhesions.

• Journal of Chest Surgery
• /
• v.31 no.11
• /
• pp.1070-1075
• /
• 1998

Background: With the advent of thoracoscopy, there has been increasing interest in less invasive surgical bullectomy and pleurodesis. The recurrence rate, however, has been reported higher in surgery with thoracoscopy than with open thoracotomy and it is thought to be caused by inappropriate mechanical pleurodesis during thoracoscopic surgery. Materials and methods: We compared the short-term recurrence rates according to the intensities of pleural abrasion in 62 patients who underwent VATS for treatment of spontaneous pneumothorax from April 1996 to August 1997. The patients were divided into 2 groups: group A(n=32) included patients who received relatively weak pleural abrasion using Endo-forcep instrument for grasping the gauze, and group B(n=30) received strong pleural abrasion using conventional instrument wrapped tightly with gauze. Each intensity of pleural abrasion allowed petechia on the parietal pleura in group A, and some tearing and bleeding in group B. Results: Indications for operation, sex distribution, and age were comparable in both groups. There were no differences in chest tube indwelling time(3.78±3.35 vs 3.80±2.49 days), hospital stay(4.72±1.87 vs 4.67±2.20 days), and the amount and duration of analgesics required postoperatively. Persistent air-leak more than 7 days after surgery occurred in 4/32(12.5%) and 2/30(6.7%) in group A and B, respectively. No bleeding-related complication occured. Pneumothorax recurred 12.5%(4/32) and 0%(0/30) of patients at a mean follow-up of 9.7 and 9.6 months in group A and B, respectively, and it was statistically significant(p<0.05). Conclusions: Proper intensity of pleural abrasion is very important factor to reduce recurrence after VATS for spontaneous pneumothorax. During short-term follow-upafter surgery, we could achieve excellent result in reducing recurrence rate with VATS and strong pleural abrasion which is comparable to thoracotomy.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.2
• /
• pp.56-63
• /
• 2018

The management of Combined Sewer Overflows(CSOs) and Separated Sewer Overflows(SSOs) discharge directly to the effluent system in an untreated state, which occurs when the facility capacity is exceeded due to heavy rain, has become an important issue in recent years as the heavy rain becomes a regular phenomenon. Despite the continuous development of filtration technology, targeting densely populated urban areas, CSOs are rarely applied. Therefore, this study was carried out to optimize the process to apply CSOs in a pilot-scale horizontal flow filtration system with a rope-type synthetic fiber. The research was carried out in two steps: a preliminary study using artificial samples and a field study using sewage. In the preliminary study using an artificial sample, head loss of the filter media itself was analyzed to be approximately 1.1cm, and the head loss was increased by approximately 0.1cm as the linear velocity was increased by 10m/hr. In addition, the SS removal efficiency was stable at 81.4%, the filtration duration was maintained for more than 6 hours, and the average recovery rate of 98% was obtained by air backwashing only. In the on-site evaluation using sewage, the filtration duration was approximately 2 hours and the average removal efficiency of 83.9% was obtained when belt screen (over 450 mesh) was applied as a pre-treatment process to prevent the premature clogging of filter media. To apply the filtration process to CSOs and SSOs, it was concluded that the combination with the pre-treatment process was important to reinforce the hydraulic dimension for the stable maintain of operation period, rather than efficiency. Compared to the dry season, the quality of incoming sewage was lower in the rainy season, which was attributed to the characteristics of the drainage area with higher sanitary sewerage. In addition, the difference in removal efficiency according to the influent quality of the wet season and dry season was small.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.22 no.1
• /
• pp.53-66
• /
• 1980

The research work is concerned with the analytical and experimental studies on the heat transfer phenomenon around the underground concrete digester used for biogas production Systems. A mathematical and computational method was developed to estimate heat losses from underground cylindrical concrete digester used for biogas production systems. To test its feasibility and to evaluate thermal parameters of materials related, the method was applied to six physical model digesters. The cylindrical concrete digester was taken as a physical model, to which the model,atical model of heat balance can be applied. The mathematical model was transformed by means of finite element method and used to analyze temperature distribution with respect to several boundary conditions and design parameters. The design parameters of experimental digesters were selected as; three different sizes 40cm by 80cm, 80cm by 160cm and l00cm by 200cm in diameter and height; two different levels of insulation materials-plain concrete and vermiculite mixing in concrete; and two different types of installation-underground and half-exposed. In order to carry out a particular aim of this study, the liquid within the digester was substituted by water, and its temperature was controlled in five levels-35。 C, 30。 C, 25。 C, 20。C and 15。C; and the ambient air temperature and ground temperature were checked out of the system under natural winter climate conditions. The following results were drawn from the study. 1.The analytical method, by which the estimated values of temperature distribution around a cylindrical digester were obtained, was able to be generally accepted from the comparison of the estimated values with the measured. However, the difference between the estimated and measured temperature had a trend to be considerably increased when the ambient temperature was relatively low. This was mainly related variations of input parameters including the thermal conductivity of soil, applied to the numerical analysis. Consequently, the improvement of these input data for the simulated operation of the numerical analysis is expected as an approach to obtain better refined estimation. 2.The difference between estimated and measured heat losses was shown to have the similar trend to that of temperature distribution discussed above. 3.It was found that a map of isothermal lines drawn from the estimated temperature distribution was very useful for a general observation of the direction and rate of heat transfer within the boundary. From this analysis, it was interpreted that most of heat losses is passed through the triangular section bounded within 45 degrees toward the wall at the bottom edge of the digesten Therefore, any effective insulation should be considered within this region. 4.It was verified by experiment that heat loss per unit volume of liquid was reduced as the size of the digester became larger For instance, at the liquid temperature of 35˚ C, the heat loss per unit volume from the 0. 1m$^3$ digester was 1, 050 Kcal/hr m$^3$, while at for 1. 57m$^3$ digester was 150 Kcal/hr m$^3$. 5.In the light of insulation, the vermiculite concrete was consistently shown to be superior to the plain concrete. At the liquid temperature ranging from 15。 C to 350 C, the reduction of heat loss was ranged from 5% to 25% for the half-exposed digester, while from 10% to 28% for the fully underground digester. 6.In the comparison of heat loss between the half-exposed and underground digesters, the heat loss from the former was fr6m 1,6 to 2, 6 times as much as that from the latter. This leads to the evidence that the underground digester takes advantage of heat conservation during winter.

• Journal of Chest Surgery
• /
• v.41 no.6
• /
• pp.729-735
• /
• 2008

Background: This study was performed to evaluate the safety and efficacy of performing additional tetracycline pleurodesis during the thoracoscopic treatment of primary spontaneous pneumothorax. Material and Method: Between March 2004 and December 2007, 91 cases of primary spontaneous pneumothorax were treated by video-assisted thoracoscopic surgery. The thoracoscopic procedures included resection of the blebs and mechanical pleurodesis by scrubbing the parietal pleura. For 27 cases (Tetracycline group, group I), 20 mg/kg tetracycline was instilled into the pleural space through a trocar before closing the chest. The control group (group II) consisted of 64 cases of primary spontaneous pneumothorax for which the same thoracoscopic procedures alone were performed during the same study period. Result: There was no significant difference between the two groups in terms of the demographic data, the operative findings and the operation time. The percentage of cases that needed intravenous analgesics and the duration of intravenous analgesics were comparable in both groups. There was no significant difference in the duration of air leaks and complications between the two groups. The patients treated with tetracycline pleurodesis had a longer period of postoperative chest drainage (4.2 days vs 3.5 days, respectively, p=0.03) and hospitalization (5.0 days vs 4.0 days, respectively, p=0.006). During the follow up period, the ipsilateral recurrence rate was much lower for the patients who were treated with tetracycline pleurodesis (0% vs 10.9%, respectively, p=0.099), and freedom from recurrence tended to be more favorable for group I (p=0.077), although this was not statistically significant. Conclusion: Additional tetracycline pleurodesis during thoracoscopic treatment for primary spontaneous pneumothorax caused prolongation of chest drainage and a prolonged hospital stay. However, further investigations are needed because tetracycline pleurodesis can be performed safely without serious complications and it showed a distinct tendency to reduce the rate of recurrence.

• Tuberculosis and Respiratory Diseases
• /
• v.59 no.6
• /
• pp.613-618
• /
• 2005

Background : Recently, medical treatment of multi-drug resistant pulmonary tuberculosis has been unsuccessful. Through analyzing the cases with surgical treatment, we hope to provide some help in treating multi-drug resistant pulmonary tuberculosis in the future. Material and Method : A retrospective review was performed with 138cases of surgical treatment of multi-drug resistant tuberculosis during 10years from January 1994 to December 2003 at National Masan Hospital. Results : The ratio of men to women, 5.1:1 indicates that there were more incidences in men. The number of the resistant drugs was 5.3 with a mean age of 42.6 years. Cavitary lesions on the plain chest X-rays were seen in 94cases (68.1%). 128cases had positive sputum culture preoperatively. Types of operations were 24 pnemonectomies, 83 lobectomies, 10 bilobectomies, 19 lobectomies with segmentectomies or wedge resections, 1 wedge resection, and 1 carvenoplasty. There was no death after operation. There were 6cases of air leakage over a week, 6cases of postoperative bleeding, 8cases of bronchopleural fistula and empyema, 16cases of dead space, 1case of atelectasis, 1case of wound infection, 1case of cyst as postoperative complication. Postoperative complication showed higher long-term negative conversion rate of 92.8%. Conclusion : There has been many discussions about operative indications, postoperative drug regimens, length of postoperative chemotherapy. In our study, we showed higher long-term success rate of postoperative chemotherapy with pulmonary resection on multi-drug resistant pulmonary tuberculosis.