• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.48-53
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• 1995

This study investigates a simple mathematical model for the quantitative estimation of regional myocardial blood flow in experimental canine coronary artery thrombosis using Rb-82 dynamic myocardial positron emission tomography. The coronary thrombosis was induced using the new catheter technique by narrowing the lumen of coronary vessel gradually, which finally led to partial obstruction of coronary artery. Ten Rb-82 dynamic myocardial PET scans were performed sequentially for each experiment using our 5, 10 and 20 second acquisition protocol, respectively, and three regions of interest were drawn on the transaxial slices, one on left ventricular chamber for input function and the other two on normal and decreased perfusion segments for the flow estimation in those regions. Single compartment model has been applied to the measured sets of regional PET data, and the rate constants of influx to myocardial tissue were calculated for regional myocardial flow estimates with the three parameter fits of raw data by the Levenberg-Marquardt method. The results showed that, (1) single compartment model suggested by Kety-Schmidt could be used for the simple estimation of regional myocardial blood flow, (2) the calculated regional myocardial blood flow estimates were dependent on the selection of input function, which reflected partial volume effect and left ventricular wall motion, and (3) mathematically fitted input and tissue time activity curves were more suitable than the direct application of the measured data in terms of convergence.

• Archives of Plastic Surgery
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• v.37 no.4
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• pp.396-399
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• 2010

Purpose: In hand injury, pedicle is usually damaged by avulsion injury or crushing injury. Because of postoperative pedicle obliteration, it is often hard to save the injured hand and fingers, even after successful replantation. The author introduces three cases of extensive hand injury, and successful results after applicatoin of multiple venous grafts to these patients. Methods: In all cases there was no circulation in any finger. In the first case, some vessels were extracted, so venous graft was applied to two sites of severely damaged venous sites. In the second case, venous grafts were applied to all four digital arteries of all fingers except thumb which got severely crushed, and two sites of dorsal veins. In the third case, venous graft was applied to all four digital arteries of all five fingers, and two sites of dorsal veins and palmar veins each. Results: In all cases, survival of hands and fingers was successful. In the second case, however, amputation in thumb and little finger at DIP joint level was inevitable, because of its severe damage, and the large dorsal defect on index finger was filled with DIEP free flap. Thumb was reconstructed with toe-to-thumb free flap, and additional debulking procedures and contracture release is furtherly needed. In the first case, additional surgery was done, as FDP tendon got re-ruptured, but in long term follow-up, satisfactory range of motion was attained. In the third case, FTSG on dorsal skin region was planned. as flap on dorsal area got partial necrosis. Conclusion: In hand injury, there are many structures to be repaired, but sometimes venous graft is avoided for its long operating time. Even though the length of damaged vessel is enough for anastomosis, the endothelium is often damaged (zone of injury). In extensive hand injury, successful reconstruction would be possible with active venous graft to all vessels suspicious for damage.

• Journal of Navigation and Port Research
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• v.47 no.4
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• pp.256-270
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• 2023

In this study, a sliding mode (SM) controller for dynamic positioning (DP) was specifically designed for a turret connection operation of a ship or an offshore structure in which an arbitrary point on the structure could be controlled as the motion center instead of the center of mass. The SM controller allows control of the arbitrary point and provides capability to manage uncertainties in the dynamics of ships and offshore structures, external forces caused by unknown changing marine environments, and transient performance of DP systems. The Jacobian matrix included in kinematic equations of the controlled object was modified to design the SM controller to control based on an arbitrary point of ships or offshore structures. To ensure robustness of the controller, the Lyapunov stability theory was applied in the design of the SM controller. In general, for robustness in DP control, gain scheduling based on a proportional-derivative (PD) control algorithm is employed. However, finding appropriate gains for gain scheduling complicates the application of DP systems. Therefore, in this study, the SM control algorithm was considered to mitigate the complexity of the DP controller for ships and offshore structures. To validate the proposed SM control algorithm, time-domain simulations were conducted and utilized to evaluate the performance of the control algorithm. The effectiveness of the proposed SM controller was assessed by comparing simulation results with results of a conventional PD control algorithm applied in DP control.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.688-696
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• 2023

In the present study, free roll decay and resistance performances of fishing vessels were evaluated with the combinations and variations of in the parameters of appendages which are attached to improve motion performance of fishing vessels. Computational Ffluid Ddynamics was used to perform free roll decay and resistance analysis. The roll period and decay coefficient were derived by the variations in the combination and dimensions of the primary appendages of the bilge keel and the under keel. It was observed thatThe variations of in the length of the under keel did not significantly impact to the roll damping coefficient. Conversely, for the bilge keel, an increase in the length and angle resulted in an increase in the roll damping coefficient. Comparison of resistance performance was additionally assessed among the selected hulls with the appendages and bare hull. The resistance of the hull with the appendages was higher than that of the bare hull due owing to the changes of in the pressure on the surface of the hull and trim angle. Throughout the present study, the impact of appendage parameter and arrangement on the free roll decay and resistance performance of fishing vessels were was assessed,. which This will be beneficial for the application of appendages to fishing vessels.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.74-81
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• 2024

In the near future, autonomous ships, ships controlled by shore remote control centers, and ships operated by navigators will coexist and operate the sea together. In the advent of this situation, a method is required to evaluate the safety of the maritime traffic environment. Therefore, in this study, a plan to evaluate the safety of navigation through ship control simulation was proposed in a maritime environment, where ships directly controlled by navigators and autonomous ships coexisted, using autonomous operation technology. Own ship was designed to have autonomous operational functions by learning the MMG model based on the six-DOF motion with the PPO algorithm, an in-depth reinforcement learning technique. The target ship constructed maritime traffic modeling data based on the maritime traffic data of the sea area to be evaluated and designed autonomous operational functions to be implemented in a simulation space. A numerical model was established by collecting date on tide, wave, current, and wind from the maritime meteorological database. A maritime meteorology model was created based on this and designed to reproduce maritime meteorology on the simulator. Finally, the safety evaluation proposed a system that enabled the risk of collision through vessel traffic flow simulation in ship control simulation while maintaining the existing evaluation method.

• The Korean Journal of Air & Space Law and Policy
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• v.30 no.2
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• pp.83-153
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• 2015

As our economy grows and the number of aircraft increase, the number of civil execution against aircraft cases are likely to increase as well in the future. The purpose of this article is to present the legal theory on the civil execution against aircrafts by drawing on the legal theory on the civil execution against vessels which constitute a relatively large number of cases thus observed. The provisions of the civil execution against immovables or vessel, shall basically apply mutatis mutandis to the civil execution against aircraft or light aircraft. The civil execution against ultra-light flying devices or a foreign aircraft shall be executed in conformity with the civil execution against movables. There are a compulsory auction, an auction to execute a security right to aircraft, and an auction under the right of retention, etc. in the civil execution against an aircraft. A compulsory execution against an aircraft means an execution carried out by a creditor against a debtor's aircraft to obtain satisfaction of claims for the purpose of payment of money. The court of execution of a compulsory execution against an aircraft shall be the district court having jurisdiction over the airport of stoppage or storage of such aircraft at the time of seizure. The forums of execution of a compulsory execution against an aircraft shall be exclusive forums. When a court has rendered an order on commencing an auction, it shall order an execution officer to receive a certificate of the aircraft's registration and other documents as required for its operation, and to submit them to the court. A court may revoke the procedures for a compulsory auction when an execution officer fails to obtain a transfer of the aircraft's registration certificate, etc. and the location of the aircraft is not evident, not later than an elapse of 2 months from the date on which an order on commencing an auction has been rendered. In the case where it is deemed that there exists a business-related need or other based on proper reasoning, the court may permit the aircraft's operation, upon the motion submitted by the debtor. In this case, there shall be a consent from the creditor, the highest bidder, the next highest bidder and successful bidder. A court may, upon a motion submitted by the creditor, make the dispositions required for observing and preserving the aircraft. When a debtor has submitted the documents under subparagraph 2 or 4 of the Article 49 of the Civil Execution Act, and furnished the guarantee equivalent to the claims of the execution creditors and the creditors demanding a distribution and to the costs for execution, before a declaration of bid, the court shall, upon request, revoke other procedures than those for distribution. The provisions of a obligatory auction against vessel or aircraft and an auction to execute a security right to real estate or vessel, shall apply mutatis mutandis to an auction to execute the security right to aircraft. In an auction to execute the security right to aircraft case, an executive title is not necessary. An executory exemplification is not necessary in an application for an auction to execute the security right to aircraft. A court should examine the existence of security right and claim secured. No order on commencing an auction procedure shall be issued with non-existence or invalidity of the security right and absence or extinguishment of the claim secured. Furthermore, these prohibitions are the reason of a decision on non-permit for sale, the court overlooked these prohibitions, and the decision on a permit for sale became final and conclusive, the successful bidder who paid the price and registered of ownership could not acquire ownership of the aircraft sold. A court may render a ruling to put plural aircrafts up for a blanket auction, only when they are in restraint and related matter (Supreme Court Order 2001Ma3688 dated on August 22, 2001). A righter of retention on aircraft may file a request for an auction against the aircraft. The provisions of an auction to execute a security right to aircraft shall apply mutatis mutandis to the formal auction. Airport facility fee and an aircraft are not in restraint and related matter, so an airport management corporation does not hold the right of retention on the aircraft (Supreme Court Decision 2011Da29291 decided on April 10, 2014). In an auction in accordance with the right of retention, all encumbrances (e.g., mortgages) on the sold aircraft shall be extinguished by a sale under the legal conditions for sale. Not only creditors who have claims for preferential payment but also general creditors could demand for distribution. The precedence of the claim of the right of retention on aircraft and that of general creditor's claims are equal.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.3
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• pp.191-200
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• 2017

Proper packaging design can meet both the environmental and economic aspects of packaging materials by reducing the use of packaging materials, waste generation, material costs, and logistics costs. Finite element analysis(FEM) is used as a useful tool in various fields such as structural analysis, heat transfer, fluid motion, and electromagnetic field, but its application in the field of packaging is still insufficient. Therefore, the application of FEM to the field of packaging can save the cost and time in the future research because it is possible to design the package by computer simulation, and it is possible to reduce the packaging waste and logistics cost through proper packaging design. Therefore, this study investigated the FEM papers published in Korea for the purpose of helping research design using FEM program in the field of packaging in the future. In this paper, we analyzed the 29 papers that were directly related to the analysis of FEM papers published in domestic journals from 1991 to 2017. As a result, we analyzed the research topic, FEM program, and analysis method using each paper, and presented the direction that can be applied in future packaging field. When the FEM is applied to the packaging field, it is possible to change the structure and reduce the thickness through the stress and vibration analysis applied to the packaging material, thereby reducing the cost by improving the mechanical strength and reducing the amount of the packaging material. Therefore, in the field of packaging research in the future, if the FEM is performed together, economical and reasonable packaging design will be possible.

• Journal of Chest Surgery
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• v.39 no.9 s.266
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• pp.674-680
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• 2006

Background: Acute myocardial infarction (MI) is a life-threatening disease and surgical revascularization plays a major role in selected cases. The purpose of this study is to evaluate the left ventricular contractility improvement by examining the wall motion score index (WMSI) and left ventricular ejection fraction (LVEF) in patients who under-went surgical revascularization under diagnosis of acute MI. Material and Method: From January, 2001 to December, 2004, 149 patients who underwent coronary artery bypass surgery within 2 weeks of acute MI were included. We evaluated pre- and postoperative left ventricular contractility by measuring WMSI and LVEF and examined the associating factors. Result: WMSI decreased from $1.54{\pm}4.30\;to\;1.43{\pm}0.40$ (p<0.001) and LVEF increased from $48.1{\pm}12.2%\;to\;49.7{\pm}12.3%$ after surgery (p=0.009). Off-pump technique, non-Q wave, anterior MI, and surgery within 7 days after MI were favorable factors for LVEF improvement (p=0.046, p=0.006, p=0.003, p=0.005, respectively). Conversely, aforementioned factors were irrelevant with WMSI improvement. For triple vessel disease, complete revascularization was favorable factor for WMSI improvement (p<0.001). Conclusion: Coronary artery by-pass surgery can improve WMSI and LVEF in patients with acute MI. In case of anterior MI with non-Q wave, early surgical revascularization within 7 days may be most beneficial in LVEF improvement. Regarding WMSI, complete revascularization may be essential.