• Journal of Ocean Engineering and Technology
• /
• v.30 no.2
• /
• pp.69-74
• /
• 2016

A new wave-piercing-type high-speed planing boat without a chine was developed, and its basic performance was investigated in a model test, including the resistance, trim, and sinkage. The maximum speed of the developed ship was 35 knots. The hull form was developed by combining a VSV (very slender vessel) and TH (transonic hull), which have large deadrise angles at the bow. The main dimensions were estimated by a statistical approach using actual ship data. The effect of a side fin attached at the stern near the water line was investigated from a resistance point of view. It was found that the developed hull form showed the possibility of a new concept for a high-speed planing hull without a chine, and the side fin played an important role in increasing the resistance performance by controlling the trim and sinkage in the high-speed range.

• Korean Journal of Computational Design and Engineering
• /
• v.11 no.1
• /
• pp.1-10
• /
• 2006

This paper addresses B-spline curve approximation of a set of ordered points to a specified toterance. The important issue in this problem is to reduce the number of control points while keeping the desired accuracy in the resulting B-spline curve. In this paper we propose a new method for error-bounded B-spline curve approximation based on adaptive selection of dominant points. The method first selects from the given points initial dominant points that govern the overall shape of the point set. It then computes a knot vector using the dominant points and performs B-spline curve fitting to all the given points. If the fitted B-spline curve cannot approximate the points within the tolerance, the method selects more points as dominant points and repeats the curve fitting process. The knots are determined in each step by averaging the parameters of the dominant points. The resulting curve is a piecewise B-spline curve of order (degree+1) p with $C^{(p-2)}$ continuity at each knot. The shape index of a point set is introduced to facilitate the dominant point selection during the iterative curve fitting process. Compared with previous methods for error-bounded B-spline curve approximation, the proposed method requires much less control points to approximate the given point set with the desired shape fidelity. Some experimental results demonstrate its usefulness and quality.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.6
• /
• pp.868-876
• /
• 2014

Arleigh Burke(DDG-51) and Sejong warship are AEGIS destroyer of US Navy and Korea Navy. These are designed to make more than 30knots by applying a COGAG(COmbined Gas turbine And Gas turbine) system. However, the gas turbine(LM2500) in this system has a low SFC (Specific Fuel Consumption) when the warship operated low speed. So, many kinds of companies are researching the HED(Hybrid Electric Drive) system to improve this problem. The purpose of this paper is to analyze the HED system and simulate by Sejong warship data. Serveral methods were used for that purpose. More specifically, the equipment modeling are employed for regression analysis by LabVIEW. As a result, it was found that the warship installed HED system could cut their fuel bills by as much as about 80,000,000won per year.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.18 no.3
• /
• pp.300-308
• /
• 2015

Recently supercavitating underwater torpedo moving at high speed (over 200 knots) has been interested for their practical advantage of the dramatic drag reduction. Cavitator located in front of the torpedo plays an important role to generate a natural supercavity and control the motion of the object. Supercavity can be created artificially by injection of compressed gas from the rear of the cavitator at a relatively low speed. In this paper, we investigated physical characteristics of artificial supercavities through cavitation tunnel experiments. One of the main focuses of the study was to measure pressure inside the cavity, and examined variation of the gravity effects appearing according to different amount of injected air. It was also found that a stable supercavity could be sustained at injection rates less than that required to form the stable supercavity because of hysteresis effect.

• Journal of the Society of Naval Architects of Korea
• /
• v.43 no.5 s.149
• /
• pp.578-585
• /
• 2006

Cavitation related erosion damages on semi-spade rudder generally occur at around leading edge of lower-face and behind gap of lower pintle. To get the idea of gap entrance profile for the latter case, a series of tests with large models has been carried out at MOERI. In the tests, the flow pattern around lower pintle have been investigated and visualized by high speed camera. Additionally, cavitation inception tests and pressure measurements have also been conducted for better comparison. As a result a new model (F rudder) has been developed. The new model turned out to have stable pressure distribution along the surface and so the cavitation inception speeds within ${\pm}5^{\circ}$ of rudder angle were delayed approx. 4 knots in average.

• Journal of the Society of Naval Architects of Korea
• /
• v.44 no.2 s.152
• /
• pp.166-173
• /
• 2007

Collision analysis problems between ship to ship can be generally classified into the external mechanics(outer dynamics) and internal mechanics(inner dynamics). The former can be also dealt with the concept of fluid-structure interaction and the use of rigid body dynamic program, depending on the ways handling the hydrodynamic pressure due to surrounding water. In this study, full scale ship collision simulation was carried out, such as a DWT 75,000 ton striking ship collided at right angle to the middle of a DWT 150,000 struck ship with 10 knots velocity, coupling MCOL, a rigid body mechanics program for modeling the dynamics of ships, to hydrocode LS-DYNA. It could be confirmed that more suitable damage estimation would be performed in the case of the collision simulations with consideration of surrounding water through the comparison with the collision simulation results of fixed struck ships without it. Through this study, the opportunity could be obtained to establish a more effective ship collision simulation technique between ship to ship.

• Korean journal of applied entomology
• /
• v.46 no.1 s.145
• /
• pp.169-173
• /
• 2007

Root-knot nematode damage was found on yam, Dioscorea bulbifera in Andong Korea. From the root-knots, female nematodes were isolated and subjected to DNA sequence analysis. Sequence of cytochrome oxidase subunit II (COII) was analyzed from the genomic DNA of the isolate. COII locus size and sequence of the nematode isolate were similar to those of Meloidogyne javanica or M. incognita. However, an analysis of HinfI restriction site, a species-specific character between these two species, showed that the isolate did not match to either M. javanica or M. incognita.

• Archives of Craniofacial Surgery
• /
• v.14 no.2
• /
• pp.111-114
• /
• 2013

The anterior maxillary sinus walls are the most frequently injured sites in midfacial fractures. The maxillary sinus is a difficult surgical site for reduction and fixation due to its narrow surgical field, and has a chance of developing sinusitis when sufficient treatment is not given. In this study, the methods developed by the authors for managing such are introduced. Two small openings were made on both sides of the fracture line, then a suture knot was tied instead of wiring for reduction and fixation. Then an absorbable mesh was applied on top of the fracture site, with a suture knot for additional fixation. This method was applied on an actual patient, and it was a convenient method despite the narrow surgical field that was provided. The authors believe that using suture knots to fixate fractured segments and absorbable mesh is relatively convenient and economically efficient when it comes to the reduction and fixation of the maxillary sinus wall fracture with several fragments.

• Journal of the Korean Society of Costume
• /
• v.58 no.8
• /
• pp.120-136
• /
• 2008

This study examined sewing methods used to reinforce the opening of clothes of the Joseon period. Through the analysis of a total of 117 clothing items of the Joseon period, the following results were obtained. 1. Most costumes of the Joseon period had the opening. The purpose of the opening was to allow one to put on and take off a costume, act comfortably, and turn a costume Inside out. The opening was located on the Side, Conte. Back, fgwi(Side opening of pants), Wristband, Armhole, and Godae(the bark part of the collar). 2. As the opening tended to get easily worn out, it was often reinforced. The 1911owing three methods were used to reinforce the opening of clothing items of the Joseon period: a method to attach a cloth such as Dang, Binding, and Badae; a method using a variety of knots; and a method by sewing stitches such as a sort of cross stitch called Satteugi, Prick stitch, and Loop. 3. The most frequently used reinforcing method was the one that used a knot(34 items), followed by the one by sewing Satteugi(27 items), and the one using Dang(25items). The most frequently detected location of the opening was Side(59 items), followed by Agui(37 items), Wristband(19 items), and Center Back(13 items). 4. The reinforced opening made a costume more endurable and elastic, decorative and neat.

• Archives of Reconstructive Microsurgery
• /
• v.10 no.1
• /
• pp.49-54
• /
• 2001

Sutures support wound healing during the initial phase. As the tensile strength of a wound increases, the need for the presence of sutures becomes less important. For this reason, absorbable suture materials have been sought. Nowadays, commonly used suture materials are Chromic Catgut, Coated Vicryl, and PDS. Among these materials, Coated Vicryl is the most popular. Studies were conducted to compare the handling properties, reliability of knots, wound healing, and tissue reactivity(Inflammation, Fibroblast proliferation, Collagen deposition, Giant cell reaction, Absorption) between AILEE vicryl and ETHICON vicryl. We used twelve purebred New Zealand white rabbits, and biopsied the tissue at three, seven, fourteen, and thirty days post implantation. The results showed that both were supple and easy to handle and tie, and gross and histologic differences were not apparent.