• Proceedings of the KWS Conference
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• 2002.10a
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• pp.127-132
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• 2002

Recent deepwater offshore structures in Gulf of Mexico utilize butt welded tubular joints. Application of welded tubular joint includes tendons, production risers, and steel catenary risers. Fatigue life assessment of these joints becomes more critical because the structures to which they are attached are allowed to undergo cyclic and sometimes large displacements around an anchored position. Estimating the fatigue behavior of these tubular members in the design stage is generally conducted by using S-N curves specified in the codes and standards. Applying the stress concentration factor of the welded structure to S-N approach often results in very conservative assessment because the stress field acting on the tubular has a non-uniform distribution through the thickness. Fracture mechanics and fitness for service (FFS) technology have been applied in the design of the catenary risers. This technology enables the engineer to establish proper requirements on weld quality and inspection acceptance criteria to assure satisfactory structural integrity during its design life. It also provides guidance on proper design curves to be used and a methodology for accounting for the effects of non-uniform stress distribution through the wall thickness. An attempt was made to develop set of S-N curves based on fracture mechanics approach by considering non-uniform stress distribution and a threshold stress intensity factor. Series of S-N curves generated from this approach were compared to the existing S-N curves. For flat plate butt joint, the S-N curve generated from fracture mechanics matches with the IIW class 100 curve when initial crack depth was 0.5 mm (0.02"). Similar comparison with API X′ was made for tubular joint.. These initial crack depths are larger than the limits of inspection by current Non-destructive examination (NDE) means, such as Automatic Ultrasonic Inspection (AUT). Thus a safe approach can be taken by specifying acceptance criteria that are close to limits of sizing capability of the selected NDE method. The comparison illustrates conservatism built into the S-N design curve.

• Convergence Security Journal
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• v.15 no.6_2
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• pp.99-106
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• 2015

The purpose of this study was to explore the direction in applying platform business model to the site to facilitate the growth of a private security guard service according to the development phase of economy, The directions of platform business application to be suggested through the study method are as follows. First, ensuring publicness. It should be able to integrate the government's and private sector's ability to collect and impart information. Second, securing self-regulation. Self-regulation should be guaranteed in the limit not to abuse or misuse others' information in re-producing and using information on private safe management and public order. Third, ensuring access. Past safety management has been controlled by public order power such as nation, military and police power, but access should be made to be convenient between suppliers and demanders. Fourth, securing profitability. In conclusion, those supplying and consuming private security guard service should be able to get their wanted value and share economic profits.

• Advances in pediatric surgery
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• v.17 no.1
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• pp.45-50
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• 2011

Meckel's diverticulum (MD) has various clinical presentations and due to the limitation of imaging studies, pre-operative diagnosis is a challenge in pediatric patients. Recently, laparoscopic exploration has been suggested as a favorable method for the diagnosis and treatment of complicated MD. We investigated the results of laparoscopic-assisted surgery compared with open technique. We retrospectively studied patients who underwent resection of complicated MD at our institute from 1997 to 2010 and compared 11 treated by laparoscopic-assisted diverticulectomy (LD) with 11 treated by open diverticulectomy (OD) for complicated MD. Operation time was not significantly different in the two groups. Hospital stay and time to diet were not significantly different. Two patients were re-admitted due to mechanical ileus in the LD group. None of patients in either group needed re-operation. Considering the possibility of false-positive results with imaging studies and the cosmetic benefit, laparoscopic-assisted surgery is a safe and effective treatment modality to diagnose and treat complicated Meckel's diverticulum.

• Archives of Reconstructive Microsurgery
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• v.19 no.1
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• pp.61-67
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• 2010

Emergency free flap has been advocated to cover the severely injured extremity for more than two decades, due to its numerous advantages such as low incidence of flap failure and infection rate and early recovery of function. But there are very few reports about these. The authors report their experience in using the emergency free flap for reconstruction of extremities. For last 10 years, 4 patients ranging from 3 to 27 years old with severely traumatized extremities were treated with emergency free flap transfers. Three were males and the other was a female. Flap size ranged from $2{\times}5\;cm^2$ to $7{\times}22\;cm^2$. The locations of the recipient site were the dorsum of the foot, the cubital fossa, the popliteal fossa and the upper arm. The number of the donor sites used was as follows: one scapular flap, two parascapular flaps, and one radial forearm flap with the radial bone. All of the flaps survived without need of re-exploration. There was no infection or flap loss. Involved joints have recovered a normal range of motion. Therefore, we consider that the emergency free flap is a very safe and reliable method to cover the severely injured extremities.

• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.261-271
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• 2024

The widespread adoption of aluminum slab formwork in modern construction, evident in both domestic and international projects, offers numerous advantages. However, a critical challenge persists regarding the dismantling process for these slabs. The current industry standard involves dropping the slabs to the ground floor upon removal. This practice raises several concerns, notably the generation of significant noise pollution that disrupts nearby communities. More importantly, the risk of worker injuries due to falls from height during the dismantling process is a serious safety hazard. Additionally, the impact from dropping the slabs can damage the aluminum itself, leading to increased replacement costs. These drawbacks necessitate the exploration of alternative dismantling techniques that prioritize worker safety, material sustainability, and overall process efficiency. Accordingly, in this study, when the entire first-generation slab formwork of an apartment house is simultaneously lowered to a reachable position for workers, it is then disassembled and lifted for transport to the next floor. This approach has the potential to demonstrate improvements in safety, quality, economy, and process efficiency.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.6
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• pp.473-480
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• 2013

Researches for various lunar landing technologies are in progress for the lunar exploration program planned for early 2020s in Korea. This paper shows the integrated simulation for safe lunar landing guidance/control system in powered descent phase. Generally, the lunar lander uses on/off(bang-bang) controller to control the RCS jet thrusters instead of proportional controller. In this paper, the on/off controller using phase-plane switching function, and thruster selection algorithm to control sixteen thrusters are applied. Also additional guidance commands are calculated by a proposed fuzzy logic guidance algorithm. The simulation results show that lunar lander can follow a reference trajectory which is generated by optimization method, then land on the surface safely.

• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.263-275
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• 2023

The Sun-Earth Lagrange point L4 is considered as one of the unique places where the solar activity and heliospheric environment can be observed in a continuous and comprehensive manner. The L4 mission affords a clear and wide-angle view of the Sun-Earth line for the study of the Sun-Earth and Sun-Moon connections from he perspective of remote-sensing observations. In-situ measurements of the solar radiation, solar wind, and heliospheric magnetic field are critical components necessary for monitoring and forecasting the radiation environment as it relates to the issue of safe human exploration of the Moon and Mars. A dust detector on the ram side of the spacecraft allows for an unprecedented detection of local dust and its interactions with the heliosphere. The purpose of the present paper is to emphasize the importance of L4 observations as well as to outline a strategy for the planned L4 mission with remote and in-situ payloads onboard a Korean spacecraft. It is expected that the Korean L4 mission can significantly contribute to improving the space weather forecasting capability by enhancing the understanding of heliosphere through comprehensive and coordinated observations of the heliosphere at multi-points with other existing or planned L1 and L5 missions.

• Journal of Chest Surgery
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• v.13 no.4
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• pp.346-355
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• 1980

It has been proposed that wide individual variation in response to heparin be not considered in the conventional set protocol for the control of heparin and protamine during extracorporeal circulation. In this paper, two protocol of heparin and protamine therapy were compared to assess the role of the Activated Clotting Time [ACT] in relation to heparin, protamine, and postoperative blood loss and transfusion. The study groups consisted of the 31 patients [adults 15 and children 16] anticoagulated with the conventional heparin protocol and the 31 patients [adults 15 and children 16] anticoagulated with ACT protocol during extracorporeal circulation. In the conventional heparin protocol, two mg of heparin per kg was administered initially with an additional 0.75 mg of heparin per kg every 30 minutes of extracorporeal circulation, and reversal was accomplished with protamine in a dose of 1.5 times the total milligram of heparin. In the ACT protocol, two mg of heparin per kg was administered initially with an additional dose of heparin enough to reach an ACT of 480 seconds [within safe zone 300 to 600 seconds] from the patient`s dose response curve every 1 hour of extracorporeal circulation, and reversal was done with protamine in a dose of 1.3 times the milligram of the residual heparin. The results were summarized as follows. After a dose of 2 mg per kg of heparin, the patient`s ACT varied from 240 to 600 seconds in adults and from 240 t~ 660 seconds in children. In the ACT group the total amount of heparin administered was markedly reduced when compared to the conventional group, and less protamine was required to neutralize heparin. The dose of heparin administered decreased from 7.07 [SE 0.42] mg/kg of the conventional group to 4.92 [SE 0.32] mg/k8 of the ACT group in adults and from 10.17 [SE 1.15] mg/kg to 5.23 [SE 0.24] mg/kg in children, which represent 30.4% and 48.6% decrease respectively. The dose of protamine administered for reversal decreased from 10.6 [SE 0.63] mg/kg of the conventional group to 3.35 [SE 0.35] mg/kg of the ACT group in adults and from 15.7 [SE 1.70] mg/kg to 3.26 [SE 0.27] mg/kg in children, which represent 68.4% and 79.2% respectively. The ratio of protamine to heparin administered in the conventional group was 1.50:1 in adults and 1.54:1 in children, but in the ACT group 0.68:1 in adults and 0.62:1 in children. Postoperative blood loss and transfusion revealed no statistically significant difference between the two groups. Although six patients in the conventional group and one in the ACT group needed re-exploration for continuous hemorrhage, no case of generalized oozing was encountered, and in each case a definite bleeding site was identified. Author would like emphasizing the value of the ACT protocol in controlling heparin and protamine administration during extracorporeal circulation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.495-500
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• 2006

Satellite systems for objects positioning appeared indispensable for performing basic tasks of maritime navigation. Navigation, understood as safe and effective conducting a vehicle from one point to another, within a specific physical-geographical environment. [Kopacz, $Urba{\acute{n}}ski$, 1998]. However, the systems have not solved the problem of accessibility to reliable and highly accurate information about a position of an object, especially if surveyed toward on-shore navigational signs or in sea depth. And it's of considerable significance for many navigational tasks, carried out within the frameworks of special works performance and submarine navigation. In addition, positioning precisely the objects other than vessels, while executing hydrographical works, is not always possible with a use of any satellite system. Difficulties with GPS application show up also while positioning such off-lying dangers as wrecks, underwater and aquatic rocks also other naturaland artificial obstacles. It is caused by impossibility of surveyors approaching directly any such object while its positioning. Moreover, determination of vessels positions mutually (mutual geometrical relations) by teams carrying out one common tasks at sea, demands applying the navigational techniques other than the satellite ones. Vessels'staying precisely on specified positions is of special importance in, among the others, the cases as follows: - surveying vessels while carrying out bathymetric works, wire dragging; - special tasks watercraft in course of carrying out scientific research, sea bottom exploration etc. The problems are essential for maritime economy and the Country defence readiness. Resolving them requires applying not only the satellite navigation methods, but also the terrestrial ones. The condition for implementation of the geo-navigation methods is at present the methods development both: in aspects of their techniques and technologies as well as survey data evaluation. Now, the classical geo-navigation comprises procedures, which meet out-of-date accuracy standards. To enable meeting the present-day requirements, the methods should refer to well-recognised and still developed methods of contemporary geodesy. Moreover, in a time of computerization and automation of calculating, it is feasible to create also such software, which could be applied in the integrated navigational systems, allowing carrying out navigation, provided with combinatory systems as well as with the new positioning methods. Whereas, as regards data evaluation, there should be applied the most advanced achievements in that subject; first of all the newest, although theoretically well-recognised estimation methods, including estimation [Hampel et al. 1986; $Wi{\acute{s}}niewski$ 2005; Yang 1997; Yang et al. 1999]. Such approach to the problem consisting in positioning a vehicle in motion and solid objects under observation enables an opportunity of creating dynamic and interactive navigational structures. The main subject of the theoretical suggested in this paper is the Interactive Navigational Structure. In this paper, the Structure will stand for the existing navigational signs systems, any observed solid objects and also vehicles, carrying out navigation (submarines inclusive), which, owing to mutual dependencies, (geometrical and physical) allow to determine coordinates of this new Structure's elements and to correct the already known coordinates of other elements.

• Journal of Trauma and Injury
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• v.23 no.2
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• pp.170-174
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• 2010

Purpose: As techniques and instruments for video-assisted thoracic surgery (VATS) have been evolving, attempts to perform VATS for chest trauma have been increasing. Several studies have demonstrated the feasibility and safety of VATS for thoracic trauma. We reviewed our experience to evaluate the clinical feasibility and safety of VATS for thoracic trauma. Methods: Fifty-two patients underwent thoracic surgery for chest trauma in Asan Medical Center from January 1990 to December 2009. VATS was performed in 21 patients who showed stable vital signs. We reviewed retrospectively the medical records of those patients to investigate the results of VATS for thoracic trauma. Results: Thoracic exploration for chest trauma was performed in 52 patients. There were 46 males (88.5%) and 6 females (11.5%). The median age was 46.0 years (range: 11~81 years). There were 39 blunt and 13 penetrating traumas. A standard posterolateral thoracotomy was performed in 31 patients, and VATS was tried in 21 patients. We performed successful VATS in 13 patients; 11 males (84.5%) and 2 females (15.5%) with a median age of 46.0 years (range: 24~75 years). The indication of VATS was persistent intrathoracic hemorrhage in 10 patients and clotted hemothorax in 3 patients. There were no complications, but there were two mortalities due to multiple organ failure after massive transfusion. In 8 patients, VATS was converted to a standard posterolateral thoracotomy for several reasons. The reason was inadequate visualization for bleeding control or evacuation of the hematoma in 5 patients. In 3 patients, VATS was performed to evaluate diaphragmatic injury. After the diaphragmatic injury had been confirmed, a standard posterolateral thoracotomy was performed to repair the diaphragm. Conclusion: VATS should be safe and efficient method for diagnostic evaluation and surgical management of stable patients with thoracic trauma.