• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.3
• /
• pp.1049-1061
• /
• 2013

In this paper, a relative heat exchange rate is numerically compared for cast-in-place concrete energy piles with different heat exchange pipe configurations, and a new design method for energy piles is proposed. An equivalent heat exchange rate was estimated for the W-type (one series loop), multiple U-type (four parallel loops), and coil-type heat exchanger installed in the same large-diameter drilled shaft. In order to simulate a cooling operation in summer by a CFD analysis, the LWT (leaving water temperature) into a energy pile was fixed at $35^{\circ}C$ and then the EWT (entering water temperature) into a heat pump was monitored. In case of continuously applying the artificial maximum cooling load for 100 hours, all of the three types of heat exchangers show the marginally similar heat exchange rate. However, in case of intermittently applying the cooling load with a cycle of 8 hours operation-16 hours off for 7 consecutive days, the coil type heat exchanger exhibits a heat exchange rate only 86 % of the multiple U-type due to measurable thermal interference between pipe loops in the energy pile. On the other hand, the W-type possesses the similar heat exchange rate to the multiple U-type. The equivalent heat exchange rates for each configuration of heat exchangers obtained from the CFD analysis were adopted for implementing the commercial design program (PILESIM2). Finally, a design method for cast-in-place concrete energy piles is proposed along with a design chart in consideration of typical design factors.

• Journal of Chest Surgery
• /
• v.26 no.7
• /
• pp.513-520
• /
• 1993

Surgical treatment of aneurysm or dissection involving the ascending aorta and aortic arch still poses one of the most complicated technical and tactical challenges in surgery. The use of total circulatory arrest[TCA] with profound hypothermia in the surgical treatment of aneurysmal dissection involving the ascending aorta and aortic arch has been reported as popular surgical methods. However, the safe period of prolonged circulatory arrest with hypothermia remains controversial and ischemic damage to the central nervous system and uncontrollable perioperative bleeding have been the major problem. We have found profound hypothermic circulatory arrest with retrograde cerebral perfusion via the superior vena cava to achieve cerebral protection. We experiment the aortic anastomosis in 7 adult mongrel dogs, using profound hypothermic circulatory arrest with continuous retrograde cerebral perfusion[RGCP] via superior vena cava. We also studied the extent of cerebral protection using above surgical methods, by gas analysis of retrograde cerebral perfusion blood and returned blood of aortic arch, preoperative, intraoperative and postoperative electroencephalography and microscopic findings of brain tissue. The results were as follows: 1. The cooling time ranged from 15 minutes to 24 minutes[19.71$\pm$ 3.20 minutes] ; Aorta cross clamp time ranged from 70 minutes to 89 minutes[79.86 $\pm$ 7.54 minutes] ; Rewarming time ranged from 35 minutes to 47 minutes[42.86$\pm$ 4.30 minutes] ; The extracorporeal circulation time ranged from 118 minutes to 140 minutes[128.43$\pm$ 8.98 minutes] [Table 2]. 2. The oxygen content in the oxygenated blood after RGCP was 12.66$\pm$ 1.25 ml/dl. At 5 minutes after the initiation of RGCP, the oxygen content of returnedlood was 7.58$\pm$ 0.21 ml/dl, and at 15 minutes 7.35$\pm$ 0.17 ml/dl, at 30 minutes 7.20$\pm$ 0.19 ml/dl, at 60 minutes 6.63$\pm$ 0.14 ml/dl [Table 3]. 3. Intraoperative electroencephalographic finding revealed low amplitude potential during hypothermia, and no electrical impulse throughout the period of circulatory arrest and RGCP. Electrical activity appeared after reperfusion, and the electroencephalographic reading also recovered rapidly as body temperature returned to normal [Fig. 2]. 4. The microscopic finding of brain tissue showed widening of the interfibrillar spaces. But there was no evidence of tissue necrosis or hemorrhage [Fig. 3]. We concluded the retrograde cerebral perfusion during hypothermic circulatory arrest is a simplified technique that may have a excellent brain protection.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.11
• /
• pp.3418-3426
• /
• 2009

The purpose of this study was to investigate the feasibility of field operation protocol for cardiopulmonary resuscitation(CPR) in person with non-traumatic arrest. This study was performed from May 1 through June 27, 2008, and subjects were 150 students who are attending the department of Emergency Medical Service in J and K universities which located in Jeollabuk-do and Jeollanam-do areas. Practical conformance was verified using by nonequivalent control group pretest-posttest design. This study divided into two groups; experimental group that employed field operation protocol and control group that applied conventional CPR protocol, and comparative analyzed statistically the necessary time of the items of each protocol. The results indicated that each performance time of 18 items was reduced over 3 seconds except 5 items(assessment of consciousness, airway control, two times of artificial respiration, check of circulation, and five cycles of CPR). And time of 6 items(intubation, peripheral intravenous line, reassessment of consciousness, pupil reaction, carotid artery pulse, and vital sign) was minimized more than 60 seconds, and total performing time was shortened 110.85 seconds. The results suggested that total performing time in pre and post test where the protocol was applied for two groups showed a statistically significant decrease(t=-6.580, p=.000). Consequently, field operation protocol for cardiopulmonary resuscitation(CPR) in person with non-traumatic arrest will be a available manual which support prompt and accurate decision making, and improve emergency medical service.

• Journal of the Korean Chemical Society
• /
• v.43 no.4
• /
• pp.407-411
• /
• 1999

Studies have been carried out on the fabrication of PPy/GC and PPy/Pt electrode modified with polypyrrole film and determination of Cr(VI) by using 3-electrode system with modified electrodes. Modified electrodes were able to easily fabricated by cyclic voltammetry scanned from +1.0V to -1.0V(vs. Ag/AgCl) at 50 mV/sec. Film thickness could be controlled at same condition by the number of cycling up to 26 times. Reduction behaviour of Cr(VI) at PPy/GC electrode could be seen at wide potential ranges from +0.6V to -0.5V(vs. Ag/AgCl), and maximum reduction peak potential of the ion was observed at -0.25V(vs.Ag/AgCl). Calibration graph at its potential was linear from 0.1 ppm to 80.O ppm. Slope factor and relative coefficient were 1.75 mA/ppm and 0.998, respectively. Reduction behaviour of Cr(VI) at PPy/Pt electrode was similar to PPy/GC electrode, Calibration graph was linear from l.0 ppm to 60.0 ppm. Slope factor and relative coefficient were 0.5mA/ppm and 0.923, respectively. But PPy/GC modified electrode had about 3 times higher sensitivity than PPy/Pt modified electrode. Reduction behaviour of Cu(II), As(IlI), Pb(II), and Cd(II) couldn't be seen at PPy/GC electrode,Its metals had not lnterfered with Cr (VI) determination.

• Journal of Chest Surgery
• /
• v.40 no.9
• /
• pp.624-628
• /
• 2007

Between 2001 and 2006, 3 neonates that had multilevel left ventricular outflow tract obstruction and a ventricular septal defect underwent the Norwood-Rastelli procedure. The body weights ranged from 2.9 to 3.1 kg. The patients had a near normal sized mitral valve and left ventricle. We simultaneously performed a modified Norwood procedure with native tissues-to-tissue anastomosis without circulatory arrest, and a Rastelli type procedure using a non-valved conduit from the right ventricle to the pulmonary artery and intracardiac patch baffling from the left ventricle to the pulmonary valve via the ventricular septal defect. The postoperative courses were uneventful. During follow-up, there was one late mortality caused by a cardiac catheterization related complication at 7 months after surgery, One patient required a Rastelli conduit change. Two patients are doing well during a follow-up period of 1 and 5 years, respectively.

• Journal of Biomedical Engineering Research
• /
• v.19 no.2
• /
• pp.163-170
• /
• 1998

The ultimate goal of total artificial heart is permanent substitute for a failed heart in a patient without any other therapeutic modality. Until now, infection has been the main problem related to the mechanical circulatory support system. The best way to solve this catastrophic complication and to improve the quality of life of TAH patients in terms of tethering must be implantation of TAH totally. The EH-TAH has been developed in NCVC from 1987 for this purpose. The system consists of an energy converter and pumps, which are designed to be placed in abdomen and pericardial space separately for a good anatomical fit. To evaluate the anatomical fit and hemodynamic performance of the EH-TAH, in vivo test was done. General condition of the animal and hemodynamic status had been stable until the TAH stopped on the 11th pumping day. The estimated cardiac output was about 7.7L/min. The values of mean aortic pressure, left and right atrial pressure were 93$\pm$10, 19$\pm$3 and 15$\pm$4 mmHg, respectively. The correlation coefficient between left and right atrial pressure was 0.96, which represents the dynamic function of the interatrial shunt in controlling left-right imbalance of cardiac output. During pumping days, the temperature on the surface of actuator had been maintained at 39.7$\pm$0.4$^{\circ}C$, less than 1$^{\circ}C$ higher than the rectal temperature. The TAH stopped on the 11th day due to mechanical problems. We concluded that the EH-TAH possessed satisfactory basic performance including anatomic fit and hemodynamic adequacy, although there were several mechanical problems to be solved yet.

• Korean small business review
• /
• v.43 no.4
• /
• pp.27-57
• /
• 2021

How does authenticity influence the process that conducts a company's CSR Strategy? Authenticity, an internal/external alignment condition that an employee feels in relation to an organization, means the decision on how true and beneficial to employees through their experiences, such as thoughts and emotions. Also, it can be understood as a process of meaning formation between the organization's strategy to conduct CSR and the perception of employees conducting CSR. To prove the relation between authenticity and CSR clearly, we used various techniques like Text Mining, Topic Modeling and Semantic network analysis about O corporation's 657 review data, from 2015 to 2021. As a result of the analysis, we find out the special issues and types. The analysis shows that the issue concerning the 'external image' is the biggest characteristic of authenticity perception in other conditions. Furthermore, the types of authenticity perception evaluations are largely divided into acceptance and rejection, in detail, five categories. This study indicates that organizations should consider both external and internal conditions when establishing CSR strategies. In addition, it is necessary to be an interactive circular relationship between the organization and employee, collecting and reflecting employee's perceptions. Finally, this study proposes ways to overcome problems related to interaction.

• Journal of Chest Surgery
• /
• v.37 no.6
• /
• pp.517-523
• /
• 2004

Background: The location of intimal tear can vary in type A acute aortic dissection. The aim of this study was to assess the operative result according to the intimal tear site. Material and Method: From January, 1995 to May, 2003, 18 patients underwent surgery for acute type A aortic dissection. The patients were classified according to the intimal tear site. In Group I (n=11), the intimal tear site was located within the ascending aorta, in Group II (n=7), the intimal tear site was located in the aortic arch, descending aorta, or intramural hematoma only. All clinical data were analyzed retrospectively. Result: In Group I, the operative time, cardiopulmonary bypass time, aorta cross clamp time and circulatory arrest time were 381.5$\pm$81.0 min, 223.5$\pm$42.5 min, 146.4$\pm$34.8 min and 36.5$\pm$17.4 min, respectively; and in group II, 461.7$\pm$54.0 min, 252.5$\pm$45.3 min, 162.5$\pm$45.3 min and 47.0$\pm$14.4 min respectively. All of those were greater in group II. The overall hospital mortality rate was 27.8% (5/18) and was significantly higher in Group II (57.1%)(p=0.003) compared to that in Group I (9.1%). The causes of death were hemorrhage (n=1) in group I and hemorrhage (n=2), multiple organ failure (n=1), and rupture of abdominal aorta (n=1) in group II. Conclusion: Surgical treatment of acute type A aortic dissection with intimal tear in the ascending aorta results in an acceptable mortality rate, but in patients with intimal tear in the aortic arch or descending aorta, the operative mortality still remains high when only ascending aorta replacement was performed. In these circumstances, in order to improve surgical results, efforts to include the intimal tear site in the operative procedure will be needed.

• Korean Journal of Ecology and Environment
• /
• v.47 no.4
• /
• pp.319-327
• /
• 2014

Understanding and quantifying of carbon storage in ecosystem is very important factor for predicting change of global carbon cycle under the global climate change. We estimated total ecosystem carbon in Gyeryongsan National Park with naturally well preserved ecosystem in Korea. Vegetation of Gyeryongsan National Park was classified with mainly four communities with Quercus mongolica (1,743.5 ha, 38.0%), Quercus variabilis (1,174.0 ha, 25.6%), Quercus serrata (971.9 ha, 21.2%), Pinus densiflora (695.2 ha, 15.2%). Biomass and soil carbons were calculated from biomass allometric equations based on the DBH and carbon contents of soil and litter collected in quadrat in each community. The tree biomass carbon was in Quercus variabilis ($130.1tCha^{-1}$), Pinus densiflora ($111.1tCha^{-1}$), Quercus mongolica ($76.2tCha^{-1}$), Quercus serrata ($39.0tCha^{-1}$). Soil carbon storage was in Quercus mongolica ($159.7tCha^{-1}$), Quercus serrata ($121.0tCha^{-1}$), Pinus densiflora ($110.5tCha^{-1}$), Quercus variabilis ($90.8tCha^{-1}$). Ecosystem carbon storage was Pinus densiflora ($239.9tCha^{-1}$), Quercus mongolica ($235.9tCha^{-1}$), Quercus variabilis ($226.0tCha^{-1}$), Quercus serrata ($165.9tCha^{-1}$), total amount was $867.7tCha^{-1}$. The area of each vegetation carbon storage was Quercus mongolica ($411,200tCha^{-1}$), Quercus variabilis ($265,300tCha^{-1}$), Pinus densiflora ($166,800tCha^{-1}$), Quercus serrata ($161,200tCha^{-1}$) and the total ecosystem carbon amount estimated $1,045,400tCha^{-1}$ at Gyeryongsan National Park. Theses results indicate that different in naturally well preserved ecosystem.

• Journal of Chest Surgery
• /
• v.33 no.6
• /
• pp.445-468
• /
• 2000

Background: Retrograde cerebral perfusion(RCP) is currently used for brain protection during aorta surgery, however, for the safety of it, various data published so far are insufficient. We performed RCP using pig and investiaged various parameters of cerebral metabolism and brain injury after RCP under deep hypothermia. Material and Method: We used two experimental groups: in group I(7 pigs, 20 kg), we performed RCP for 120 minutes and in group II (5 pigs, 20 kg), we did it for 90 minutes. Nasopharyngeal temperature, jugular venous oxygen saturation, electroencephalogram were continuously monitored, and we checked the parameters of cerebral metabolism, histological changes and serum levels of neuron-specific enolose(NSE) and lactic dehydrogenase(LDH). Central venous pressure during RCP was mainained in the range of 25 to 30 mmHg. Result: Perfusion flow rates(ml/min) during RCP were 130$\pm$57.7(30 minutes), 108.6$\pm$55.2(60 minutes), 107.1$\pm$58.8(90 minutes), 98.6$\pm$58.7(120 minutes) in group I and 72$\pm$11.0(30 minutes), 72$\pm$11.0(60 minutes), 74$\pm$11.4(90 minutes) in group II. The ratios of drain flow to perfusion flow were 0.18(30 minutes), 0.19(60 minutes), 0.17(90 minutes), 0.16(120 minutes) in group I and 0.21, 0.20, 0.17 in group II. Oxygen consumptions(ml/min) during RCP were 1.80$\pm$1.37(30 minutes), 1.72$\pm$1.23(60 minutes), 1.38$\pm$0.82(90 minutes), 1.18$\pm$0.67(120 minutes) in group I and 1.56$\pm$0.28(30 minutes), 1.25$\pm$0.28(60 minutes), 1.13$\pm$0.26(90 minutes). We could observe an decreasing tendency of oxygen consumption after 90 minutes of RCP in group I. Cerebrovascular resistance(dynes.sec.cm-5) during RCP in group I incrased from 71370.9$\pm$369145.5 to 83920.9$\pm$49949.0 after the time frame of 90 minutes(p<0.05). Lactate(mg/min) appeared after 30 minutes of RCP and the levels were 0.15$\pm$0.07(30 minutes), 0.18$\pm$0.10(60 minutes), 0.19$\pm$0.19(90 minutes), 0.18$\pm$0.10(120 minutes) in group I and 0.13$\pm$0.09(30 minutes), 0.19$\pm$0.03(60 minutes), 0.29$\pm$0.11(90 minutes) in group II. Glucose utilization, exudation of carbon dioxide, differences of cerebral tissue acidosis between perfusion blood and drain blood were maintained constantly during RCP. Oxygen saturation levels(%) in drain blood during RCP were 22.9$\pm$4.4(30 minutes), 19.2$\pm$4.5(60 minutes), 17.7$\pm$2.8(90 minutes), 14.9$\pm$2.8(120 minutes) in group I and 21.3$\pm$8.6(30 minutes), 20.8$\pm$17.6(60 minutes), 21.1$\pm$12.1(90 minutes) in group II. There were no significant changes in cerebral metabolic parameters between two groups. Differences in serum levels of NSE and LDH between perfusion blood and drain blood during RCP showed no statistical significance. Serum levels of NSE and LDH after resuming of cardipulmonary bypass decreased to the level before RCP. Brain water contents were 0.73$\pm$0.03 in group I and 0.69$\pm$0.06 in group II and were higher than those of the controls(p<0.05). The light microscopic findings of cerebral neocortex, basal ganglia, hippocampus(CA1 region) and cerebellum showed no evidence of cerebral injury in two groups and there were no different electron microscopy in both groups(neocortex, basal ganglia and hippocampus), but they were thought to be reversible findings. Conclusion: Although we did not proceed this study after survival of pigs, we could perform the RCP successfully for 120 minutes with minimal cerebral metabolism and no evidence of irreversible brain damage. The results of NSE and LDH during and after RCP should be reevaluated with survival data.