• Title/Summary/Keyword: POGO

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Performance Test of PSD Oxidizer Drain Valve for KSLV-II (한국형발사체 PSD 산화제 배출밸브 성능시험)

  • Chung, Yonggahp;Han, Sangyeop;Kim, Suengik
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.1171-1175
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    • 2017
  • Cryogenic helium gas is used as the pressurant for the oxidizer pressurization of DR(Damper Receiver) sphere in the PSD(Pogo Suppression Device) system and liquid oxygen is used as the oxidizer for the propellant in Korea Space Launch Vehicle-II. The helium gas is stored in pressurant cylinders inside the cryogenic liquid oxygen tank and liquid oxygen is stored in the oxidizer tank. In this study, the performance test of PSD liquid oxygen drain valve for KSLV-II was considered.

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Development of KSR-III Propulsion Feeding System (KSR-III 추진기관 공급계 개발)

  • 이대성;조인현;정태규;강선일;김용욱;정영석;권오성;정동호;오승협
    • Journal of the Korean Society of Propulsion Engineers
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    • v.6 no.4
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    • pp.37-45
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    • 2002
  • The development process of KSR-III propulsion feeding system is subscripted. The purpose of propulsion feeding system is to feed a certain amount of propellant from propellant tank to engine by the end of combustion. Pressure-fed liquid rocket, KSR-III has the unique characteristics of both pressure regulator and cavitation venturi as a passive flow control device. Main parameters of feeding system are confirmed by both water test and CFD(전산유체) technique. Flow control effect with venturi is confirmed by water test. Initial stabilization characteristic of pressure regulator is confirmed by real propellant test. And, to avoid the effect of resonance between rocket and feeding system, this article deal with POGO(포고) analysis to the feeding system.

Review of Propellant Vibration and Control of Liquid Rocket Fuselage Feeding System (액체로켓 기체공급계의 추진제 진동특성 및 제어기술 동향)

  • Cho, Nam-Kyung;Kho, Hyun-Seok;Han, Sang-Yeop;Cho, In-Hyun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.89-94
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    • 2010
  • Fuselage propellant feeding system should supply propellants to engine with required flow rate, temperature and pressure. Propellant vibration in engine and feeding line changes feeding characteristics, and frequently inhibits to satisfy the required feeding requirements. Sloshing and POGO vibration are known to be the major vibration phenomena. Concerning sloshing and POGO, vehicle control and structural dynamics aspects are extensively studied, whereas, its effect on propellant feeding performance is not clearly understood. This paper focuses on the deviation of required feeding performance due to propellant vibration. Overall characteristics of propellant vibration and its effect on propellant supply to engine are reviewed and control mechanism for suppressing vibration is introduced.

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Numerical and Experimental Thermal Validation on Pogo-pin based Wire Cutting Mechanism for CubeSat Applications (큐브위성용 포고핀 기반 열선절단 분리장치의 열적 거동 분석 및 검증)

  • Min-Young Son;Bong-Geon Chae;Hyun-Ung Oh
    • Journal of Aerospace System Engineering
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    • v.17 no.2
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    • pp.94-102
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    • 2023
  • A nylon wire holding and release mechanism (HRM) has been widely used for deployable applications of CubeSat owing to its simplicity and low cost. In general, structural safety of solar panel with an HRM has been designed by performing structural analysis under a launch environment. However, previous studies have not performed thermal analysis for HRM in an on-orbit environment. In this study, Launch and Early Orbit Phase (LEOP) thermal analysis was performed to evaluate thermal stability of the mechanism in the orbital thermal environment of the pogo pin-based HRM applied to CubeSat. In addition, the effectiveness of the thermal design and performance of the pogo pin-based HRM were verified through a thermal vacuum test.

The Costumes and Cultures of Kouge in the era of Kamakura and the end of Heian in Japan (일본 헤이안 말·가마쿠라시대 공가의 복식과 문화)

  • Lee, Ja-Yeon
    • Fashion & Textile Research Journal
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    • v.14 no.2
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    • pp.203-210
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    • 2012
  • This study, focusing on the costumes of Kouge in the era of Kamakura and the end of Heian in Japan, aims to explore the aspects and characteristics of the costumes that were developed under political, economical, and social circumstances. The findings are the following. Male costumes include Sokdae, Pogo, Euigwan, Jikeui, Sueui, and Sugan, while female costumes include Shipidan, Sogyu, Sejang, and Hansam. Different clothes of Kuge were chosen depending on the types and purposes of the occasions: full dress and Yahkjang, a semi-dress, for a ceremonial purpose, street costume for a personal visit purpose, outdoor clothing for hunting and outdoor activities, Cheongjangsok, and Sukjikjangsok. In these various types of clothes we can assume the elegant life of aristocratic class of Kouge. In addition, different fabrics, patterns, and dresses were chosen depending on the grade of ranks of Kouge, so that Kouge can differentiate their ranks, keep the order of the ranks, and enhance their authority by themselves. With the advent in the era of Kamakura, the power of Kouge was weakened and their clothes underwent changes, some types of clothes were omitted or simplified or the clothes of subordinates were worn. In addition, when new forces appeared and new clothes came about, there were changes in the purpose and the wearer of the clothes: from ordinary clothes to official clothes, from the clothes of lower class to the clothes of higher class, and from Sukjikjangsok to Cheongjangsok.

Analysis for Pressure Oscillation on the Inlet of Turbo-Pump at the Moment of Launch Vehicle Engine Startup (발사체 엔진 시동시 PSD 유무에 따른 터보펌프 입구 배관 압력 섭동 해석)

  • Jung, Youngsuk;Kim, Juwan;Park, Kwangkun;Baek, Seungwhan;Cho, Kiejoo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.1144-1147
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    • 2017
  • It was reviewed about the pressure oscillation on the inlet of turbo-pump at the moment of engine startup and shutdown. Specially, This research was performed how much is the effect of PSD(Pogo Suppression Device) about the pressure oscillation on the inlet of turbo-pump at the moment of engine startup and shutdown. For analysis, propellant tank PSD and Engine are modelled with Flowmaster which is the commercial 1D program. As the analysis results, even though the PSD is installed in the pipeline, the pressure drop or rising at the moment of engine startup and shutdown is same compared to the case without PSD. However, it was confirmed that PSD reduces the pressure oscillation of the high frequency band as the original purpose of PSD.

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Dependence of System Dynamics on Characteristics of Pogo Suppression Device (포고억제장치에 의한 시스템 동특성 변화)

  • Lee Jun Kyoung;Koh Kwang Uoong;Lee Han Ju;Lee Sang Yong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.10a
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    • pp.121-125
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    • 2004
  • The effectiveness of the pogo suppression device (PSD) installed at the piping system simulating the fuel supply lines of the rocket engines was investigated. The system response defined as the ratio of the flow rate to the pressure in the main tube was obtained for various PSD gas volumes $(0,\;0.5,\;1,\;2\times10^{-6}\;m^3)$. Existence of a gas volume in the PSD reduced the system resonance frequency. With a larger gas volume, the resonance frequency became lower, but only slightly, though the fluctuations of the main tube pressure and the flow rate damped down considerably

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A Study on the Historical Origin of Private Security Industry in Korea (우리나라 보안산업의 역사적 기원에 관한 연구)

  • Lee, Chang-Moo
    • Korean Security Journal
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    • no.22
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    • pp.91-111
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    • 2010
  • Around the middle of the ninth century the strict bone-rank system of Silla frustrated many people who had political ambition but lacked nobility. They had to seek other ways, including maritime trade. Such an undertaking reflected and also increased their economic and military power. Trade prospered with T'ang China and with Japan as well. The threat of piracy to Silla's thriving maritime trade caused to create a succession of garrisons at important coastal points. Chonghae Jin (Chonghae garrison) was regarded as the most important of these. It was established in 828 by Chang Pogo. Chonghae Jin was on Wando, an island just east of the southwestern tip of Korea and a key place at this time in the trade between China, Korea, and Japan. From this vantage point Chang Pogo became a merchant-prince with extensive holdings and commercial interests in China and with trade contacts with Japan. Although piracy was rampant in East Asia at that time, either the Chinese or Silla government was not able to control it due to inner political strife and lack of policing resources. Infuriated by the piracy and the government's inability to control it, Chang Pogo came back to Silla to fight against the pirates and to protect maritime trade. He persuaded the king of Silla and was permitted to control the private armed forces to sweep away the pirates. In 829 he was appointed Commissioner of Chonghae-Jin with the mission of curbing piracy in that region. Chang's forces were created to protect people from pirates, but also developed into traders among Silla Korea, T'ang China, and Japan in the 9th century. This was geographically possible because the Chonghae Garrison was situated at the midpoint of Korea, China, and Japan, and also because Chang's naval forces actually dominated the East Asia Sea while patrolling sea-lanes. Based on these advantages, Chang Pogo made a great fortune, which might be collected from a charge for protecting people from pirates and the trades with China and Japan. Chang's forces could be termed the first private security company in the Korean history, at least in terms of historical documents. Based on historical documents, the numbers of private soldiers might be estimated to exceed tens of thousands at least, since Chang's forces alone were recorded to be more than ten thousand. Because local powers and aristocratic elites were said to have thousands of armed forces respectively, the extent of private forces was assumed to be vast, although they were available only to the privileged class. In short, the domination of Chang's forces was attributable to the decline of central government and its losing control over local powers. In addition it was not possible without advanced technologies in shipbuilding and navigation.

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A Study on tile Presumption of Chang Pogo's Maritime Routes (해상왕 장보고의 해상항로 추정에 관한 연구)

  • 김형근
    • Journal of the Korean Institute of Navigation
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    • v.25 no.1
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    • pp.77-91
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    • 2001
  • According to the many ancient literatures, it is said to be that Merchant Prince, Chang Pogo in unification Silla had traded with not only China, Japan but also Arab-Islam Countries, but unfortunately there is no definite records about this. Therefore in this study the writer would like to presume the sea routes of Merchant Prince, Chang Pogo in a unification Silla. For the purpose of this study the writer would like to study the reference books and materials regarding to the sea routes of prehistoric age and ancient three countries of Kingdoms and unification Silla. Especially the writer consider “The Work of Routes and Kingdoms” of Ibn Khurdarhbih regarding to the ancient sea routes of Korea, China, Arab-Islam Countries, and also the writer consider the ancient sea routes of Tang Dynasty in China and Ryukyu Kingdom in Japan. About this methodology of this study, the writer believe that the sea routes of today is the results of ancient sea routes, and this ancient sea routes could not be changed forever except special circumstance. According in this study the writer would like to persume the sea routes of Merchant Prince, Chang Pogo using like this methodologies. This presumption of the writer is originated on the basis of The Work of Routes and Kingdoms written by ancient Arabian Geographer, Ibn Khurdadhbih in the early years of 9th century. The Work of Routes and Kingdoms is geography, and the principal contents of this geography are the activities of Arab-Islam merchants and Chinese Merchants between Arab-Islam countries and China from 9th century to 11th century by ancient sea routes. But surprisingly in this geography, Silla was marked, and another ancient Arabian geogrpher, Al-Biruni marked Silla on his map, Qanun Al-mas'udi in the 9th century, and also another ancient Arabian geographer, Al-Idrisi marked Silla on his map in the 11th century. Especially Al-Biruni expressed the longitude and latitude of Silla on his map, he expressed Silla as following. “at the extreme end of China toward the East and few people travelled to it by sea”. Therefore the writer would like to presume that Arab-Islam merchants had traded with unification Silla in the 9th century, and also Merchant Prince, Chang Pogo had traded with not only China, Japan but also Arab-Islam Countries using above ancient sea routes in the 9th century.

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