• Journal of the Society of Naval Architects of Korea
• /
• v.44 no.3 s.153
• /
• pp.228-237
• /
• 2007

The flow characteristics around a horn-type rudder behind an operating propeller of a high-speed large container carrier are studied through a numerical method in fully wetted and cavitating flow conditions. The computations are carried out in a small scale ratio of 10.00(gap space=5mm) to consider the gap effects. The Reynolds averaged Navier-Stokes equation for a mixed fluid and vapor transport equation applying cavitation model are solved. The axisymmetry body-force distribution technique is utilized to simulate the flow behind an operating propeller. The gap flow, the three-dimensional flow separation, and the cavitation are the flow characteristics of a horn-type rudder. The pattern of three-dimensional flow separation is analyzed utilizing a topological rule. The various cavity positions predicted by CFD were shown to be very similar to rudder erosion positions in real ship rudder. The effect of a preventing cavitation device, a horizontal guide plate, is also investigated.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.5 no.3
• /
• pp.454-467
• /
• 2013

A practical Ship Inner Shell Optimization Method (SISOM), the purpose of which is to improve the safety of the seagoing transport ship by decreasing the maximum Still Water Bending Moment (SWBM) of the hull girder under all typical loading conditions, is presented in this paper. The objective of SISOM is to make the maximum SWBM minimum, and the section areas of the inner shell are taken as optimization variables. The main requirements of the ship performances, such as cargo hold capacity, propeller and rudder immersion, bridge visibility, damage stability and prevention of pollution etc., are taken as constraints. The penalty function method is used in SISOM to change the above nonlinear constraint problem into an unconstrained one, which is then solved by applying the steepest descent method. After optimization, the optimal section area distribution of the inner shell is obtained, and the shape of inner shell is adjusted according to the optimal section area. SISOM is applied to a product oil tanker and a bulk carrier, and the maximum SWBM of the two ships is significantly decreased by changing the shape of inner shell plate slightly. The two examples prove that SISOM is highly efficient and valuable to engineering practice.

• Journal of the Society of Naval Architects of Korea
• /
• v.48 no.2
• /
• pp.178-182
• /
• 2011

Generally in order to reduce the steel weight of stiffened plate, stiffener spaces tend to be narrow and the plate gets thin. However, it will involve more fabrication cost because it can lead to the increase of welding length and the number of structural members. In the yard, the design which is able to reduce the total fabrication cost is needed, although it requires more steel weight. The purpose of this study is to find optimum stiffener spaces to minimize the fabrication cost for the cargo tank of LPG Carriers. Global optimization methods such as ES(Evolution Strategy) and GA(Genetic Algorithm) are introduced to find a global optimum solution and the sum of steel material cost and labor cost is selected as main objective function. Convergence degree of both methods in according to the size of searching population is examined and an efficient size is investigated. In order to verify the necessity of the optimum design based on the cost, minimum weight design and minimum cost design are carried out.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.7 no.1
• /
• pp.142-156
• /
• 2015

A new method for ship Inner Shell optimization, which is called Parametric Inner Shell Optimization Method (PISOM), is presented in this paper in order to improve both hull performance and design efficiency of transport ship. The foundation of PISOM is the parametric Inner Shell Plate (ISP) model, which is a fully-associative model driven by dimensions. A method to create parametric ISP model is proposed, including geometric primitives, geometric constraints, geometric constraint solving etc. The standard optimization procedure of ship ISP optimization based on parametric ISP model is put forward, and an efficient optimization approach for typical transport ship is developed based on this procedure. This approach takes the section area of ISP and the other dominant parameters as variables, while all the design requirements such as propeller immersion, fore bottom wave slap, bridge visibility, longitudinal strength etc, are made constraints. The optimization objective is maximum volume of cargo oil tanker/cargo hold, and the genetic algorithm is used to solve this optimization model. This method is applied to the optimization of a product oil tanker and a bulk carrier, and it is proved to be effective, highly efficient, and engineering practical.

• Korean Journal of Materials Research
• /
• v.16 no.10
• /
• pp.633-638
• /
• 2006

Silica powders with spherical shape and narrow size distribution were prepared by large-scale ultrasonic spray pyrolysis applying the droplet classification apparatus. On the other hand, silica powders prepared by large-scale ultrasonic spray pyrolysis without droplet classification apparatus had broad size distribution. Droplet classification apparatus used in this paper applied the principles of cyclone and dispersion plate with small holes. The droplets formed from the ultrasonic spray generator applying the droplet classification apparatus had narrow size distribution. The droplets with fine and large sizes were eliminated by droplet classification apparatus. The optimum flow rate of the carrier gas and diameter of the hole of the dispersion plate were studied to reduce the size distribution of the silica powders prepared by large-scale ultrasonic spray pyrolysis. The size distribution of the silica powders prepared by large-scale ultrasonic spray pyrolysis at the optimum preparation conditions was 0.76.

• The Journal of Korean Academy of Prosthodontics
• /
• v.32 no.1
• /
• pp.77-102
• /
• 1994

Many studies have been made on the masticatory and esthetic effects of prosthodontic treatments, but few on the restoration of pronunciation, especially in complete denture wearers. The purpose of this study is to provide a basis that could be of help to the complete denture wearers' speech adaptation by analyzing the influence of the palatal coverage upon the duration of consonants and vowels with the method of experimental phonetics. For this study, metal plates and resin plates were made for 3 male subjects in their twenties, who have good occlusion, and do not have speech and hearing disorders. Then 8 Korean consonants and 4 Korean vowels were selected, systemically considering phonetic variants such as the place and manner of articulation, lenis/fortis, mutual effect of each phoneme, etc. They were combined into meaningless tested words in the form of /VCV/, and were included in the carrier sentences. Each informant uttered the sentences 1) without the plate, 2) with the metal plate, 3) with the resin plate. The recorded data were analyzed through the waveform of sounds and spectrogram by using the program SoundEdit, Signalize, Statview 512+for the Macintosh computer. The duration of each segment was measured by searching for the boundaries between the preceding vowels and consonants, and between the consonants and the following vowels. The study led to the conclusion that. 1. With the palatal plate, the duration of all the tested words increased and the duration increased more with the resin plate than with the metal plate. 2. With the palatal plate, the duration of all the preceding vowels, consonants, and following vowels increased, but the temporal structure of the tested words was maintained. 3. As for the manner of articulation, fricative /s/(ㅅ) was greatly influenced by both kinds of palatal plates. 4. As for the place of articulation, alveolar sounds /d/(ㄷ), /n/(ㄴ) were greatly influnced by the kinds of palatal plates, and the velar sounds /n/(ㅇ), /g/(ㄱ) were influenced by the platal plates, but the kind of the palatal plates did not show any significance. 5. As for the lenis/fortis, lenis was influenced more by the kind of the palatal plates. 6. As for the influence of vowels upon each segment in the tested words, palatal vowel /i/(ㅣ) had greater influence than pharyngeal vowel /a/(ㅏ), and following vowels than preceding vowels.

• Asian-Australasian Journal of Animal Sciences
• /
• v.10 no.1
• /
• pp.141-146
• /
• 1997

Postmortem examination was conducted on 350 (three hundred and fifty) chickens. Related samples (Liver, heart, ovary, spleen, bone-marrow, and caecal junction) were collected. The appropriate materials from the samples were cultured into different media. A total 40(forty) isolates of salmonella pullorum and S. gallinarum were identified and preserved. Characterization of the isolates were done by cultural, morphological, biochemical, and serological tests. Salmonella pullorum antigen was prepared from the local isolate, standardized and tested. This antigen was used in the field for the detection of pullorum or fowl typhoid infection or carrier birds. The antigen consisted of suspension of Salmonella pullorum in 0.50 percent sodium chloride plus 1.5 percent sodium sulfate and inactivated with 1% formalin U.S.P. and standardized with McFarland scale iv or by pour plate method containing 800 million organisms per milliliter and stained by the addition of alcoholic crystal violet. Sterility, safety and potency were tested and found as good as other international antigens. The antigen was found to retain its quality for six months when preserved at room temperatures. The test was made by mixing one drop of the antigen with a drop of blood or a drop of serum, on a glass plate or white tile. The locally produced antigen was as good as antigens from Japan, Hungary, Holland and India. A serological study was conducted with the locally prepared antigen in different farms, and the incidence was 0-4% in government farms, 5-10% in commercial imported breeds and 0-3% in cross breed local farms respectively.

• Laser Solutions
• /
• v.8 no.3
• /
• pp.21-26
• /
• 2005

A bonding process between tape-carrier package and a glass panel with anisotropic conductive film (ACF) has been investigated by making use of high power diode laser as a heat source for cure. The results from modeling of process and from optical properties of layers showed that heat absorbed from polyimide film surface and ACF layer is dominant source of curing during laser illumination. Laser ACF bonding has better bonding quality than conventional bonding in view of peel strength, flatness, pressure unbalance and processing time. New ACF bonding processes by making use of high power diode laser are proposed.

• Journal of Ocean Engineering and Technology
• /
• v.25 no.3
• /
• pp.1-10
• /
• 2011

This paper estimates the residual longitudinal strength of a damaged double hull VLCC (Very Large Crude Carrier) under combined vertical and horizontal bending moments using Smith's method. The damage estimated in this study occurred due to collision or grounding accidents. The effects of the randomness of the yield stress, plate thickness, extent of damage, and the combination of these three parameters on the ultimate hull girder strength were investigated. Random variables were generated by a Monte Carlo simulation and applied to the double hull VLCC described by the ISSC (International Ship and Offshore Structures Congress) 2000 report.

• Proceedings of the Optical Society of Korea Conference
• /
• 2000.08a
• /
• pp.252-253
• /
• 2000

본 실험에서는 수 MW/$ extrm{cm}^2$ 의 매우 낮은 영역의 세기에서 순수한 GaAs의 bulk에 대하여 실험한 결과 비선형 흡수가 나타남을 관찰 하였으며, 더불어 자유전하 흡수 계수를 여러 가지 세기의 빛에서 측정한 결과 자유전하 흡수 단면적이 빛의 세기에 따라 변화하는 것을 관찰하였다.$^{(1)}$ GaAs의 굴절률이 3.6으로 매우 커서 Fabry-Perot 효과가 나타나므로 시료의 한쪽 면을 SiN로 무반사 코팅을 하여 실험 하였다. GaAs의 표면은 쉽게 레이저 빛에 의해 손상을 입는 것을 고려하여 같은 자리에서 여러 번의 실험을 하여 같은 결과가 나오는 것을 확인하여 실험 결과를 얻었다. 사용된 레이저는 Nd:YAG 레이저로서 1.064 $mu extrm{m}$의 파장에서 7 나노초의 펄스를 방출한다. 빛의 세기는 편광기와 half wave plate를 이용하여 변화 시켰다. (중략)