• Advances in aircraft and spacecraft science
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• v.6 no.4
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• pp.333-348
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• 2019

Low fuel regression rate is the main drawback of hybrid rocket which should be overcome. One of the improvement techniques to this problem is usage of a solid fuel grain with a complicated geometry port, which has been promoted owing to the recent development of additive manufacturing technologies. In the design of a hybrid rocket fuel grain with a complicated geometry port, the understanding of fuel regression behavior is very important. Numerical investigations of fuel regression behavior requires a capturing method of solid fuel surface, i.e. gas-solid interface. In this study, level set method is employed as such a method and the preliminary numerical tool for capturing a hybrid rocket solid fuel surface is developed. At first, to test the adequacy of the numerical modeling, the simulation results for circular port are compared to the experimental results in open literature. The regression rates and oxidizer to fuel ratios show good agreements between the simulations and the experiments, after passing enough time. However, during the early period of combustion, there are the discrepancies between the simulations and the experiments, owing to transient phenomena. Second, the simulations of complicated geometry ports are demonstrated. In this preliminary step, a star shape is employed as complicated geometry of port. The slot number effect in star port is investigated. The regression rate decreases with increasing the slot number, except for the star port with many slots (8 slots) in the latter half of combustion. The oxidizer to fuel ratio increases with increasing the slot number.

• Journal of Gastric Cancer
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• v.24 no.1
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• pp.57-68
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• 2024

Reduced-port gastrectomy (RPG) includes all procedures derived from various efforts to minimize surgical invasiveness, with single-incision laparoscopic gastrectomy (SILG) being the ultimate reduced-port technique. However, there are challenges related to its feasibility, oncological validity, training, and education. This review describes the current issues and challenges, as well as the future prospects of RPG for gastric cancer. Gastrectomy, which started as an open surgery, has evolved into a laparoscopic surgery. With the advancements in laparoscopic technology, SILG has been used to minimize surgical scarring. However, owing to the technical difficulties of SILG, cases involving the addition of 1 trocar or needle grasper alongside the multichannel port have also been reported. Additionally, 3-port laparoscopic gastrectomy (3PLG) using only 3 trocars is also being performed. RPG, as a concept, includes a range of approaches such as SILG, 2-port laparoscopic gastrectomy, and 3PLG. These techniques aimed to reduce the number of ports or incisions required for laparoscopic gastrectomy. Despite technical difficulties, RPGs offer numerous advantages, including minimal invasiveness, excellent cosmetic outcomes, and the potential for improved postoperative recovery, such as reduced length of hospital stay and post-operative pain. It could be considered similar to conventional laparoscopic gastrectomy, and may not be oncologically inferior. Ongoing studies, such as the KLASS 12, are required to gain further insights.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.221-226
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• 2006

Around 2002, the United States Coast Guard (USCG) identified a need to re-capitalize their Reference Station (RS) and Integrity Monitor (IM) equipment used in the Nationwide Differential Global Position System (NDGPS). Commercially available off-the-shelf differential RS and IM equipment lacked the open architecture required to support long-term goals that include future system improvements such as use of new civil frequencies on L2 and L5 and realization of a higher rate NDGPS beacon data channel intended to support RTK. The first step in preparing for this future NDGPS was to port current RTCM SC-104 compatible RS and IM functionality onto an open architecture PC-based platform. Trimble's product Charisma is a PC-based RS and IM software designed to meet these USCG goals. In fact USCG engineers provided key designs and design insights throughout the development. We cannot overstate the contribution of the USCG engineers. Fundamental requirements for this effort were that it be sufficiently flexible in hardware and software design to support fluid growth and exploitation of new signals and technologies as they become available, yet remain backward compatible with legacy user receivers and existing site hardware and system architecture. These fundamental goals placed an implicit adaptability requirement on the design of the replacement RS and IM. Additionally, project engineers were to remain focused on sustaining the high level of differential GPS service that 1.5 million legacy users have come to depend on. This paper will present new hardware and software (i.e., Trimble's Charisma software) architecture for the next generation NDGPS RS and IM. This innovative approach to engineering on an open architecture PC-based platform allows the system to continue to fulfill legacy NDGPS system requirements and allows the USCG and others to pursue a scalable hardware re-capitalization strategy. We will use the USCG's recapitalization project to explain the essential role of the Charisma software.

• Journal of the Korean Society for Library and Information Science
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• v.53 no.4
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• pp.51-71
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• 2019

Memory is a mental activity for the future rather than the past, and the responsibility for restoring the memory rests on the current intellectuals. In this context, the library must demonstrate how it contributes to local development by restoring memory and analyzing social roles and functions. Based on the contributions of local development of public libraries as background information and through literature case studies, field surveys and interviews. This study has logically demonstrated local development to the local economic development, regenerating and promoting local culture, and forming a community in the open-port cities of Busan and Incheon. Nevertheless, the contribution of local development in terms of economic, cultural and community formation cannot be perfect. Subsequent research that reflects the historical geography and architectural arts of the library itself, and the perception and value of use of local residents is necessary.

• Journal of the Korean Institute of Navigation
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• v.14 no.3
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• pp.15-33
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• 1990

In recent years, propellers with various blade configurations such as highly skewed propellers are often fitted to ships from the viewpoint of reduction of vibration and noise. In the design of such propellers, design charts based on methodical series tests are to be complemented by theoretical calculations for accurate estimation of propeller open-water characteristics. The author intended to develop a method to estimate propeller open-water characteristics based on Quasi -Vortex - Lattice Method originally developed by Lan for solving planar thin wings, The Quasi - Vortex - Lattice Method has the simplicity and flexibility of Vortex - Lattice Method. Its accuracy is comparable to that of the Vortex - Lattice Method. Converged solution can be obtained with a small number of control points and further, leading edge suction force can be calculated directly. In the present paper, a numerical method to estimate propeller open-water characteristics based on the Quasi - Vortex - Lattice Method is reviewed and its application to marine propellers is described in detail. Comparison of propeller open-water characteristics obtained by the present method with experimental data showed good agreement for a wide variety of propellers including highly skewed propellers.

• Structural Engineering and Mechanics
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• v.12 no.6
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• pp.615-632
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• 2001

Ductility of open piled wharves under reversed cyclic loads has been investigated. Experimental testing of five wharf models having a scale of about 1:4 was conducted under the application of horizontal reversed cyclic loading. The experiments were designed to focus on the horizontal ultimate load, ductility and failure mode of the considered wharf models. Nonlinear numerical analyses using the finite element method were also performed on numerical models representing the experimentally tested wharves. The results of the experimental tests showed that open piled wharves possessed favourable ductile behaviour and that their load bearing capacity did not depreciate until a ductility factor of 3 to 4 was reached. The numerical analysis showed that the relative rotation that took place at the joints between the steel piles and the R.C. beam was responsible for a considerable portion of the total horizontal deformation of the wharves. Therefore, it was concluded that introducing the joint stiffness in calculating the deformations of open piled wharves was important to achieve reasonable accuracy.

• Journal of Gastric Cancer
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• v.23 no.3
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• pp.487-498
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• 2023

Purpose: Reduced port surgery (RPS) for gastric cancer has been frequently reported in distal gastrectomies but rarely in total gastrectomies. This study aimed to determine the feasibility of 3-port totally laparoscopic total gastrectomy (TLTG) with overlapping esophagojejunal (EJ) anastomosis. Materials and Methods: A total of 81 patients who underwent curative TLTG for gastric cancer (36 and 45 patients with 3-port and 5-port TLTG, respectively) were evaluated. All 3-port TLTG procedures were performed with the same method as 5-port TLTG, including EJ anastomosis with the intracorporeal overlap method using a linear stapler, except for the number of ports and assistants. Short-term outcomes, including the number of lymph nodes (LNs) harvested by station and postoperative complications, were analyzed retrospectively. Results: Clinical characteristics were not significantly different among the groups, except that the 3-port TLTG group was younger and had a lower rate of pulmonary comorbidity. There were no cases of open conversion or additional port placement. All operative details and the number of harvested LNs did not differ between the groups, but the rate of suprapancreatic LN harvest was higher in the 3-port TLTG group. No significant differences were observed in the overall complication rates between the 2 groups. Conclusions: Three-port TLTG with overlapping EJ anastomoses using a linear stapler is a feasible RPS procedure for total gastrectomy to treat gastric cancer.

• Journal of Navigation and Port Research
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• v.33 no.3
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• pp.227-233
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• 2009

This experimental study has been carried out to investigate the reduction in side friction of open caisson using air-jet method. For this study, the large size caisson having air-pockets was used. This caisson was used as substructure of bridge. By using air-jet method, settlement time was decreased and even settlement was reached to the depth which conventional methods could not be. We found that the side resistance decreases to less then half the expected value. In addition to these merits, the air-jet method can result in self-weight settlement without applying additional load. Also the open caisson damage caused by blasting can be prevented with this method.

• Journal of Korea Port Economic Association
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• v.26 no.1
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• pp.20-42
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• 2010

This study is aimed at evaluating transshipment competitiveness of Incheon New Port which will open in 2013. For this reason, we used Conjoint Analysis(CA) for a methodology of this research as CA had been frequently adopted for empirical analysis of new container terminal in previous studies. We have provided the questionnaires to the stake holders of the port such as experts in Port Authority(PA), logistics companies, and terminal operators. The result showed that transshipment competitiveness of Incheon New Port was subordinate to transshipment costs and port costs of Busan and Shanghai. Overall, we hope this study could help draw up the policies on a New Port that will attract transshipment cargoes and set up marketing plan for an early settlement.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.3
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• pp.149-161
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• 2018

As a result of analyzing the relationship between the smart growth principle and the regenerating factors of the port waterfront city, it was found to be highly related to the port waterfront regeneration plan. Factors that are related to the application of smart growth principle derived from association analysis are as follows: ⯈ community development suitable for walking ⯈ differentiated and attractive community building with definite place, ⯈ open space, farmland, beautiful natural scenery, environmental preservation, ⯈ strengthening and inducing development for existing communities, and providing diversity of transportation options. However, in the Jeju port redevelopment plan, the principles such as ⯈ complex land use ⯈ advantage of high-density architectural design method, ⯈ various housing opportunities and options, etc., need to be applied in implementation design. Since Jeju city and Jeju port possess the strong characteristic features of port waterfront city, so it is necessary to develop jointly applying smart growth principle through integrated port waterfront city regeneration plan.