• International Journal of Aeronautical and Space Sciences
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• 제14권2호
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• pp.183-192
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• 2013

This paper presents formation reconfiguration using impulsive control input for spacecraft formation flying. Spacecraft in a formation should change the formation size and/or geometry according to the mission requirements and space environment. To modify the formation radius and geometry with respect to the leader spacecraft, the follower spacecraft generates additional control inputs; the two impulsive control inputs are general control type of the spacecraft system. For the impulsive control input, Lambert's problem is modified to construct the transfer orbit in relative motion, given two position vectors at the initial and final time. Moreover, the numerical simulation results show the transfer trajectories to resize the formation radius in the radial/along-track plane formation and in the along-track/cross-track plane formation. In addition, the maneuver characteristics are described by comparing the differential orbital elements between the reference orbit and transfer orbit in the radial/along-track plane formation and along-track/cross-track plane formation.

• Journal of Astronomy and Space Sciences
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• 제37권1호
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• pp.51-60
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• 2020

This study designs and analyzes satellite formation flying concepts for the Small scale magNetospheric and Ionospheric Plasma Experiments (SNIPE) mission, that will observe the near-Earth space environment using four nanosats. To meet the requirements to achieve the scientific objectives of the SNIPE mission, three formation flying concepts are analyzed: a cross-shape formation, a square-shape formation, and a cross-track formation. Of the three formation flying scenarios, the cross-track formation scenario is selected as the final scenario for the SNIPE mission. The result of this study suggests a relative orbit control scenario for formation maintenance and reconfiguration, and the initial relative orbits of the four nanosats meeting the formation requirements and thrust limitations of the SNIPE mission. The formation flying scenario is validated by calculating the accumulated total thrust required for the four nanosats. If the cross-track formation scenario presented in this study is applied to the SNIPE mission, it is expected that the mission will be successfully accomplished.

• International Journal of Aeronautical and Space Sciences
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• 제9권2호
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• pp.71-78
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• 2008

New formation flight controller for unmanned aerial vehicles is proposed. A behavioral decentralized control approach called formation geometry center control is adopted. Trajectory tracking as well as formation geometry keeping are the purpose of the formation flight, and therefore two controllers are designed: a trajectory tracking controller for reference trajectory tracking, and a position controller for formation geometry keeping. Each controller is designed using Lyapunov stability theorem to guarantee the asymptotic stability. Formation flight controller is finally obtained by combining the trajectory tracking controller and the formation geometry keeping controller using a weighting parameter that depends on the relative distance error between unmanned aerial vehicles. Numerical simulations are performed to validate the performance of the proposed controller.

• 수산경영론집
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• 제44권1호
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• pp.59-70
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• 2013

The purpose of this paper is to integrate various models of price formation and let the data choose the most proper model. After the data choose the proper model, one can analyze the price formation process and demand structures for fishery resources under the restriction of Korean fisheries regulations. This study suggests the integrated model including quasi-linear price formation model, Translog price formation model, AIDS price formation model and Lewbel price formation model as level variables. It also suggests another integrated model including AIDS price formation model, Rotterdam price formation model, Latinen-Theil price formation model and Neves price formation model as difference variables. The empirical results show that the AIDS price formation model is the most preferred in both level and difference variables of fishery resources. The estimated parameters show that all sample species have (-) sign of price flexibilities, thus following the law of demand. The scale flexibilities of all species are estimated as (-) sign, thus being adapted to the theory. The contribution and results are summarized as follows. First, the integrated model of fishery market demand has been developed and the data can choose the proper model without arbitrary choice of the researcher. Second, the fishery market demand structure could be analyzed in a way different from the ordinary demand analysis, which is based upon price flexibility and scale flexibility. Third, the integrated model for fishery resources can be used easily when catching restrictions are imposed by policies.

• Tribology and Lubricants
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• 제13권4호
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• pp.33-39
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• 1997

In order to establish a new temperature criterion to prevent the pistons from ring sticking due to deposit formation, bench test and engine test were performed. The effects of oil degradation and temperature on deposit formation was studied by a modified panel coking test. Oil degradation was analyzed by FTIR. Oil oxidation and nitration were selected as a factors to evaluate oil degradation. Bench test results show that oil oxidation is more effective to the deposit formation than oil nitration. And the temperature increase accelerates deposit formation and deposit formation increase rapidly above 26$0^{\circ}C$. Especially, in case of degraded oil, the deposit formation increases so rapidly that ring sticking can occur. The effect of piston temperature on the deposit formation was confirmed by engine test.

• International Journal of Control, Automation, and Systems
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• 제4권4호
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• pp.466-479
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• 2006

This paper addresses a formation navigation issue for a group of mobile robots passing through an environment with either static or moving obstacles meanwhile keeping a fixed formation shape. Based on Lyapunov function and graph theory, a NN formation control is proposed, which guarantees to maintain a formation if the formation pattern is $C^k,\;k\geq1$. In the process of navigation, the leader can generate a proper trajectory to lead formation and avoid moving obstacles according to the obtained information. An evolutionary computational technique using particle swarm optimization (PSO) is proposed for motion planning so that the formation is kept as $C^1$ function. The simulation results demonstrate that this algorithm is effective and the experimental studies validate the formation ability of the multiple mobile robots system.

• 자원환경지질
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• 제15권4호
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• pp.177-188
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• 1982

The Chungju and Seosan Groups have been known usually as Precambrian formations in Korea. But their relative and absolute ages have been controvericial problem in relation with other geologic system such as so-called Ogcheon and Yeoncheon Systems in Korea. This study has mainly focused on the corelation of the Chungju Group with the Seosan Group in their stratigraphy, structure, metamorphism, and iron ore deposits. In the process of study, the auther surveyed and reclassified the Chungju and Seosan Groups and corelated with Gyeonggi and Ogch cheon metamorphic belts and got some new data. The Chungju iron-bearing formations showing transtitional relation with the Gyeonggi Gneiss Complex and the Jangamri Formation consisting mainly of pebble bearing calcarious phyllite, should be seperated from the Gyemyeongsan formation which is mainly composed of metavolcanic rocks. The Jangamri Formation and the coaly phyllite, which can be corelated respectively with the Hwaggangri Formation and Changri Formation in Ogcheon Group, are repeated in the Gyemyeonsan and Munjuri Formations with the overturned anticlinal folding(F1). So the Chungju Group which was defined as an indipendant geologic unit from the Ogcheon Group should be limited only on the Chungju iron Formation. The Seosan Group can be classified stratigraphically such as Seosan Formation consisting of iron-bearing quartzite and mica schist, Daesan Formation overlying unconformably on the Seosan Formation and Gyeonggi Gneiss Complex. Taean Formation overlying unconformably on the Daesan Formation should be seperated from Seosan Group. There are many similarity in the stratigrphy, structure, and metamorphic facies between Chungju and Seosan Groups exept the metavolcanic rocks in the Gyemyeongsan and Munjuri Formations and the pebble bearing calcareous phyllite in the Jangamri Formation. The two Groups were deformed with two kinds of differant stages, the first shows $N30^{\circ}-40^{\circ}E$ trend of fold axis, the second $N70^{\circ}-80^{\circ}W$ respectively. The Seosan Formation, which is the lowest formation in Seosan Group and bearing the iron formation, was metamorphosed at 2500 m. y. before. These age is similar with the metamorphic age of Gyeonggi metamorphic belt and with the age of Algoman and Kenoran Orogenies which devide the Precambrian into Archean and Proterozoic Era. So the Seosan Formation, which is included in some migmatitic rocks of Gyeonggi Gneiss Complex, is the oldest formation in Korea and can be corelated with the Anshan Group which bears the oldest iron formation in China. The metamorphic facies of the Precambrian metamorphism in Seosan area is simillar with that of Chungju area, showing high temperature-low pressure amphibolite facies which is corelated with the Gyeonggi metamorphic belt, the oldest metamorphic belt in Korea ($650^{\circ}-680^{\circ}C$, 3.2-4.4 Kb). The high temperature intermediate pressure amphibolite facies in Seosan area with the low temperature-intermediate presure greenschist facies of Taean formation is corelated with that of Ogcheon Group ($590^{\circ}-640^{\circ}$ C, 5.2-6.3 Kb). The Chungju and Seosan iron formations were deposited in Archean, showing geochemical composition of Precambrian iron formations. The Chungju iron formation was mainly formed by the chemical precipitation, on the other hand, the Seosan iron formation was formed by alternated action of chemical and detrital depositions.

• 시큐리티연구
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• 제11호
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• pp.1-20
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• 2006

민간경비 조직은 국민의 안전과 보호라는 책임을 지닌 조직으로 다른 조직과는 다른 특수성을 가진다. 민간경비조직은 업무 수행 중에 신체의 안전에 위협을 받거나, 예기치 않은 돌발 상황이 발생하거나, 무거운 책임을 지닌 조직이 가지는 보수성, 획일적이고 수직적인 상하관계 등의 특징을 지니게 되는데 이러한 특수성으로 인해 민간경비 조직 내 커뮤니케이션의 중요성은 더욱 강조된다. 이러한 민간경비조직의 다양한 특징들이 조직의 목표 달성을 위해 효과적으로 이용되기 위해서는 조직 내 구성원들의 효과적이고 원활한 커뮤니케이션이 절실히 요구된다고 할 수 있다. 따라서 본 연구의 목적은 민간경비조직 구성원간의 커뮤니케이션이 조직성과에 어떠한 영향을 미치는가에 대한 관련성을 규명하는데 있으며, 민간경비원의 조직을 이해하고 이들을 통한 업무의 효율성을 제고함은 물론 민간경비조직의 발전을 위한 그 기초자료를 제공하는데 의의를 둔다. 이에 대한 분석된 자료의 결론은 다음과 같다. 첫째, 사회 인구통계학적 특성에 따른 커뮤니케이션에는 차이가 있는 것으로 나타났다. 둘째, 사회 인구 통계학적 특성에 따른 조직성과에는 차이가 있는 것으로 나타났다. 셋째, 커뮤니케이션은 직무만족에 유의한 영향을 미치는 것으로 나타났다. 넷째, 커뮤니케이션은 조직몰입에 유의한 영향을 미치는 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제8권2호
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• pp.118-122
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• 1987

The micelle formation of NaDC was studied by fluorometric and viscometric measurements. The thermodynamic parameters of the primary and secondary micellization of the bile salt were evaluated. The primary micelle formation was appeared to be an entropy driven process due to hydrophobic effect, while the major driving force for secondary micelle formation of the bile salt is the large negative enthalpy. The secondary micelle provides less hydrophobic environment to pyrene than the primary micelle does. The cooperative aggregation of primary micelles via hvdrogen bond formation was proposed for the secondary micelle formation.

• 대한수의학회지
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• 제41권3호
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• pp.293-298
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• 2001

This study was conducted to observe the bone and cartilage formation of mouse fetuses. Mouse litters were sacrificed at pregnant 14th and 18th day and examined for gross skeletal formation using cartilage and bone staining. We identified well developed cartilage formation at the 14th pregnant day in mouse fetus. However mouse fetus at the 14th pregnant day did not show any part of bone formation. At 18th pregnant day, mouse fetus showed well developed body shape and bone and cartilage formation. This results will provide basic information for the evaluation of mouse malfromation and impairment of skeleton formation. Further study will be needed for exact explanation of bone formation from cartilage portion.