• Title, Summary, Keyword: Propulsion performance

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On The Development of The Stern Form with Low Resistance and High Propulsive Efficiency for Full Ships (저저항(低抵抗) 고추진(高推進) 효율(效率)의 비대선(肥大船) 선미선형(船尾船型)의 개발(開發)에 관하여)

  • Ho-Chung,Kim;Chun-Ju,Lee;Young-Bok,Choi
    • Bulletin of the Society of Naval Architects of Korea
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    • v.27 no.3
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    • pp.89-99
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    • 1990
  • It is required to develop a hull form with low resistance and high propulsive efficiency for the improvement of the ship-board operational economy. Since the hull forms with low resistance frequently have lower propulsive efficiency and on the other hand the hull forms with higher propulsive efficiency don't show good resistance characteristics, it is always very difficult to obtain economical hull forms which require less propulsive power accordingly. Efforts have been made to pursue a stern form with excellent resistance and propulsion characteristics together by shaping the run of the so-called buttock-flow type stern, which is known to have good viscous resistance performance, like that of conventional aftbody(U-type or Hogner type) featured by high propulsive efficiency. First model tests confirmed that the above concept can be one of the alternative approaches to the design of the good stern form and by the continuing efforts thereafter for the refining of the concept, propelled by the first promising results, stern form of good resistance performance together with good propulsive efficiency has been realized to some extent. In addition, it is confirmed that the new new stern can have better cavitation and vibration characteristics due to uniform wake-fields and the compact engine room arrangement can be possible due to it's larger floor area in way of engine room double bottom as compared with usual barge stern.

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Study on the Calculation of Towing Force for LNG Bunkering Barge (LNG 벙커링 바지의 예인력 계산에 관한 연구)

  • Oh, Seung-Hoon;Jung, Jae-Hwan;Hwang, Sung-Chul;Jung, Hyun-Woo;Cho, Seok-Kyu;Jung, Dong-Ho
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • pp.158-161
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    • 2018
  • In this paper, the towing force is calculated for the LNG bunker barge. LNG bunkering barge is being developed as an infrastructure for the bunkering of LNG(Liquefied Natural Gas), an eco-friendly energy source. In the case of the LNG bunker barge, a self-propulsion is considered through retrofit from an operating point. Therefore, the LNG bunker barge is similar to the shape of the ship as compared to a towed barge, so a rule of the towed barge overestimates the towing force. In order to improve accuracy, the calm water resistance is calculated according to the ITTC 1978 method considering the wave resistance by the Rankine source method. The added resistance in waves is calculated using the modified radiated energy method considering the shortwave correction method of NMRI. The performance of the towing resistances through the calm water resistance and the added resistance in waves was compared with rules of the towed barge.

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Determination of Additives Content in Aviation Turbine Fuel Using Multi-dimensional GC-MS (Multi-dimensional GC-MS를 이용한 항공터빈유의 첨가제 분석)

  • Youn, Ju Min;Jang, Yoon Mi;Yim, Eui Soon;Kim, Seong Lyong;Kang, Yong
    • Journal of the Korean Applied Science and Technology
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    • v.35 no.4
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    • pp.1260-1268
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    • 2018
  • To improve fuel performance and specific characteristics of long storage and moving through fuel systems additives should be added in kerosene type aviation turbine fuel (AVTUR) such as antioxidant, fuel system icing inhibitor (FSII), electric conductivity improvers and so on. The dosage of additives has to be analyzed qualitatively and quantitatively due to inspect the quality of abnormal fuel and distinguish other petroleum products. Multi-dimensional GC-MS (MDGC-MS) with Deans switching technique are applied the determination of antioxidant and FSII, which are added with AVTUR containing complex mixture of hydrocarbons. Antioxidant and FSII in the range of 2.5-20 mg/L was quantitatively and qualitatively analyzed using MDGC-MS and the detection limit was about twice as low as that of the 1-dimensional GC-MS results. The method in this study has been higher peak resolution compared with GC-MS and could be simultaneously analyzed different two additives without sample pre-treatment.

Study on the Estimation of Towing Force for LNG Bunkering Barge (LNG 벙커링 바지의 예인력 산정에 관한 연구)

  • Oh, Seung-Hoon;Jung, Dong-Ho;Jung, Jae-Hwan;Hwang, Sung-Chul;Cho, Seok-Kyu;Sung, Hong-Gun
    • Journal of Navigation and Port Research
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    • v.42 no.6
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    • pp.378-387
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    • 2018
  • In this paper, the towing force for the LNG bunkering barge was investigated. Currently, LNG bunkering barge is being developed as an infrastructure for the bunkering of LNG (Liquefied Natural Gas), an eco-friendly energy source. In the case of the LNG bunkering barge, self-propulsion is considered through retrofit from an operating point. Therefore, the LNG bunkering barge's shape is similar to that of the ship as compared to a towed barge, so a rule of the towed barge overestimates the towing force. In order to improve accuracy, the calm water resistance was calculated using ITTC 1978 method which considers wave resistance by the Rankine source method. The added resistance in waves was calculated using the modified radiated energy method which considers the shortwave correction method of NMRI. The performance of the towing resistances through the calm water resistance and the added resistance in waves was compared to rules associated with towed barges.

Study on Development Method for Galileo/SAR Ground System in Korea (국내의 갈릴레오 탐색구조 지상시스템 개발 방안에 관한 연구)

  • Ju, In-Won;Lee, Sang-Uk;Kim, Jae-Hun
    • Journal of Satellite, Information and Communications
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    • v.2 no.1
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    • pp.35-40
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    • 2007
  • COSPAS-SARSAT is the search and rescue system for providing a distress alarm and a position identification using an international satellite and ground facilities. Aviators, mariners and land users worldwide are equipped with COSPAS-SARSAT distress beacons, which could help save their in emergency situations anywhere in the world. As the existing COSPAS-SARSAT system is generally operated by LEO(Low-altitude Earth Orbit) Satellite System, the time from the distress beacon to the rescue is more than 1 hour with average and the accuracy of the distress location is about 5 Km. Therefore, in order to overcome this problem, the development for the next generation SAR(search and rescue) system which uses the MEO(middle-altitude Earth Orbit) satellites is going on the Galileo project. EU is developing this project for the full operation capability in 2011, and this project will have SAR payloads and support to the Search and Rescue service-herein called SAR/Galileo. SAR/Galileo will have the performance of a few meter accuracy, within 10 minutes to rescue from reception of distress messages, and Return Link Service(from the SAR operator to the distress emitting beacon), thereby facilitating more efficient rescue operations and helping to reduce the rate of false alerts. As the disaster is larger every year, the ground station, MEOLUT for next generation ASR/Galileo is urgently needed for the lifesaving for the larger disaster, the research for beacon and the ground station such as MEOLUT for introducing the next generation SAR/Galileo in Korea is very timely and is important. This paper presents the procedures and the strategies for the participation, the area to develop reasonably, and the propulsion organization for developing the SAR/Galileo ground system in Korea.

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Development of 115K Tanker Design Adopted Ice Class 1A (Baltic Ice Class IA를 적용한 115K Ice Tanker 개발)

  • Kim, Hyun-Soo;Ha, Mun-Keun;Baek, Myeong-Chul;Kim, Soo-Young;Park, Jong-Woo;Chun, Ho-Hwan
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.6
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    • pp.120-125
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    • 2004
  • There are very few numbers of 115K FPP (Fixed Pitch Propulsion) Tankers for the Baltic ice class IA because the minimum power requirement of FMA (Finish- Swedish Maritime Association) needs quite large engine power and the 40 m Beam is out of calculation range of FMA minimum power requirements. The shipyard has no choice except to increase the engine power to satisfy FMA minimum power requirement Rule. And the operation cost, efficiency of hullform and its building cost are not good from the ship owners' point of view To solve this problem, the experience of ice breaking tanker development and the ice tank test results were adopted. The main idea to reduce the ice resistance is by reducing waterline angle at design load waterline. The reason behind the main idea is to reduce the ice-clearing force. Two hull forms were developed to satisfy Baltic Ice class IA. Two ice tank tests and one towing tank test was performed at MARC (Kvaener-Masa Arctic Research Center) and SSMB (Samsung Ship Model Basin) facilities, respectively. The purpose of these tests was to verify the performance in ice and open water respectively The hull form 2 shows less speed loss compared to Hull form 1 in open water operation but hull form 2 shows very good ice clearing ability. finally the Hull Form 2 satisfying Baltic ice class IA. The merit of this hull form is to use the same engine capacity and no major design changes in hull form and other related designs But the hull structure has to be changed according to the ice class grade. The difference in two hull form development methods, ice model test methods and analysis methods of ice model test will be described in this paper.

Fracture Characteristics of C/SiC Composites for Rocket Nozzle at Elevated Temperature (로켓 노즐목 소재 C/SiC 복합재 고온 파괴 특성)

  • Yoon, Dong Hyun;Lee, Jeong Won;Kim, Jae Hoon;Sihn, Ihn Cheol;Lim, Byung Joo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.11
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    • pp.927-933
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    • 2016
  • In a solid propulsion system, the rocket nozzle is exposed to high temperature combustion gas. Hence, choosing an appropriate material that could demonstrate adequate performance at high temperature is important. As advanced materials, carbon/silicon carbide composites (C/SiC) have been studied with the aim of using them for the rocket nozzle throat. However, when compared with typical structural materials, C/SiC composites are relatively weak in terms of both strength and toughness, owing to their quasi-brittle behavior and oxidation at high temperatures. Therefore, it is important to evaluate the thermal and mechanical properties of this material before using it in this application. This study presents an experimental method to investigate the fracture behavior of C/SiC composite material manufactured using liquid silicon infiltration (LSI) method at elevated temperatures. In particular, the effects of major parameters, such as temperature, loading, oxidation conditions, and fiber direction on strength and fracture characteristics were investigated. Fractography analysis of the fractured specimens was performed using an SEM.

Study on Cavitation Noise Predictions for an Elliptic Wing (타원형 날개에 대한 공동소음 예측 연구)

  • Jeong, Seung-Jin;Hong, Suk-Yoon;Song, Jee-Hun;Kwon, Hyun-Wung;Park, Il-Ryong;Seol, Han-Shin;Kim, Min-Jae
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.6
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    • pp.757-764
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    • 2019
  • Depressurization occurs around underwater objects moving at high speeds. This causes cavitation nuclei to expand, resulting in cavitation. Cavitation is accompanied by an increase in noise and vibration at the site, particularly in the case of thrusters, and this has a detrimental ef ect on propulsion performance. Therefore, predicting cavitation is necessary. In this study, an analytical method for cavitation noise is developed and applied to an elliptic wing. First, computational fluid dynamics are performed to obtain information about the flow fields around the wing. Then, through the cavitation nuclei density function, number of cavitation nuclei is calculated using the initial radius of the nuclei and nuclei are randomly placed in the upstream with large pressure drop around the wing tip. Bubble dynamics are then applied to each nucleus using a Lagrangian approach for noise analysis and to determine cavitation behavior. Cavitation noise is identified as having the characteristics of broadband noise. Verification of analytical method is performed by comparing experimental results derived from the large cavitation tunnel at the Korea Research Institute of Ships & Ocean Engineering.

Current status of global seed industry and role of golden seed project in Korea (국내외 종자산업의 현황과 GSP사업의 역할)

  • Shin, Wan Sik
    • Journal of Plant Biotechnology
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    • v.42 no.2
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    • pp.71-76
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    • 2015
  • Developed countries have set seed industry as a new growth engine, which demands strong support from the government. Multinational seed companies such as Monsanto and DuPont have made huge financial investment to secure their major roles in the global market. To spur domestic seed industry performance, Korean government laid out the foundation for developing seed industry through policy promotion in the late 2000s. In this paper, I look at the current state of the domestic and international seed market to provide information for improving the efficiency of the propulsion of the Golden Seed Project (GSP) along with its vision. The increasing size of global giant companies has been regarded to monopolize the world seed industry wherein ten renowned companies occupy 73% of the overall global market. In effect, this causes a price hike due to limited seed choices. Domestic seed market has been stuck in a range due to a sustained low agricultural production resulting in decreased seed demand and market size. Though breeding technologies for rice and vegetables are world-class, the technologies for top global crops such as cabbage, paprika, and forage are insufficient therefore professionals in this field are not easily employed. Moreover, there is a lack in appropriate infrastructure set up in the universities which adds to ineffective training of professionals. Being a key-supporting industry for agriculture, seed industry should be granted with strong and sustainable investment support from the government. In view thereof, GSP, which started in 2012, ambitions to spur researches outlined by excellent professionals in universities and seed companies aimed to drive seed export volume and quality and attain domestic seed self-sufficiency through adoption of export- and import-substitution seed types (10 varieties each) development strategies. To develop Korea's seed industry excellent achievement of GSP's goals should be drawn successfully and to do this beside development of high quality seeds, support programs for promotion of seed exports are also needed.