• Journal of Astronomy and Space Sciences
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• 제20권1호
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• pp.1-10
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• 2003

A precise kinematic orbit determination (P-KOD) procedure for Low Earth Orbiter(LEO) using the GPS ion-free triple differenced carrier phases is presented. Because the triple differenced observables provide only relative information, the first epoch's positions of the orbit should be held fixed. Then, both forward and backward filtering was executed to mitigate the effect of biases of the first epoch's position. p-KOD utilizes the precise GPS orbits and ground stations data from International GPS Service (IGS) so that the only unknown parameters to be solved are positions of the satellite at each epoch. Currently, the 3-D accuracy off-KOD applied to CHAMP (CHAllenging Min-isatellite Payload) shows better than 35 cm compared to the published rapid scientific orbit (RSO) solution from GFZ (GeoForschungsZentrum Potsdam). The data screening for cycle slips is a particularly challenging procedure for LEO, which moves very fast in the middle of the ionospheric layer. It was found that data screening using SNR (signal to noise ratio) generates best results based on the residual analysis using RSO. It is expected that much better accuracy are achievable with refined prescreening procedure and optimized geometry of the satellites and ground stations.

• Journal of Astronomy and Space Sciences
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• 제35권1호
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• pp.31-37
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• 2018

Pc1 pulsations are geomagnetic fluctuations in the frequency range of 0.2 to 5 Hz. There have been several observations of Pc1 pulsations in low earth orbit by MAGSAT, DE-2, Viking, Freja, CHAMP, and SWARM satellites. However, there has been a clear limitation in resolving the spatial and temporal variations of the pulsation by using a single-point observation by a single satellite. To overcome such limitations of previous observations, a new space mission was recently initiated, using the concept of multi-satellites, named the Small scale magNetospheric and Ionospheric Plasma Experiments (SNIPE). The SNIPE mission consists of four nanosatellites (~10 kg), which will be launched into a polar orbit at an altitude of 600 km (TBD) in 2020. Four satellites will be deployed in orbit, and the distances between each satellite will be controlled from 10 to 1,000 km by a high-end formation-flying algorithm. One of the possible science targets of the SNIPE mission is observing electromagnetic ion cyclotron (EMIC) waves. In this paper, we report on examples of observations, showing the limitations of previous EMIC observations in low earth orbit, and suggest possibilities to overcome those limitations through a new mission.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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• pp.27.5-28
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• 2010

The unexpected observation condition or insufficient measurement modeling can lead to uncertain measurement errors. The uncertain measurement error of orbit determination problem typically consists of noise, bias and drift. It must be removed by using a proper estimation process for better orbit accuracy. The estimation of noise and drift is not easy because of their random or unpredictable variation. On the other hand, bias is a constant difference between the mean of the measured values and the true value, so it can be simply removed. In this study, precision orbit determination with SLR observations considering range bias estimation is presented. The Yonsei Laser-ranging Precision Orbit Determination System (YLPODS) and SLR NP (Normal Point) observations of CHAMP satellite are used for this work. The SLR residual test is performed to estimate the range bias of each arc. The result shows that we can get better orbit accuracy through range bias estimation.

• Journal of Astronomy and Space Sciences
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• 제36권3호
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• pp.133-147
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• 2019

Challenging Minisatellite Payload (CHAMP) satellite magnetic data are used to investigate the latitudinal variation of the storm-time meso-scale field-aligned currents by defining a new metric called the FAC range. Three major geomagnetic storm events are considered. Alongside SymH, the possible contributions from solar wind dynamic pressure and interplanetary magnetic field (IMF) $B_Z$ are also investigated. The results show that the new metric predicts the latitudinal variation of FACs better than previous studies. As expected, the equatorward expansion and poleward retreat are observed during the storm main phase and recovery phase respectively. The equatorward shift is prominent on the northern duskside, at ${\sim}58^{\circ}$ coinciding with the minimum SymH and dayside at ${\sim}59^{\circ}$ compared to dawnside and nightside respectively. The latitudinal shift of FAC range is better correlated to IMF $B_Z$ in northern hemisphere dusk-dawn magnetic local time (MLT) sectors than in southern hemisphere. The FAC range latitudinal shifts responds better to dynamic pressure in the duskside northern hemisphere and dawnside southern hemisphere than in southern hemisphere dusk sector and northern hemisphere dawn sector respectively. FAC range exhibits a good correlation with dynamic pressure in the dayside (nightside) southern (northern) hemispheres depicting possible electrodynamic similarity at day-night MLT sectors in the opposite hemispheres.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.87-90
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• 2005

The FORMOSAT-3/COSMIC mission is a micro satellite mission to deploy a constellation of six micro satellites at low Earth orbits. The final mission orbit is of an altitude of 750-800 lan. It is a collaborative Taiwan-USA science experiment. Each satellite consists of three science payloads in which the GPS occultation experiment (GOX) payload will collect the GPS signals for the studies of meteorology, climate, space weather, and geodesy. The GOX onboard FORMOSAT -3 is designed as a GPS receiver with 4 antennas. The fore and aft limb antennas are installed on the front and back sides, respectively, and as well as the two precise orbit determination (POD) antennas. The precise orbit information is needed for both the occultation inversion and geodetic research. However, the instrument associated errors, such as the antenna phase center offset and even the different cable delay due to the geometric configuration of fore- and aft-positions of the POD antennas produce error on the orbit. Thus, the focus of this study is to investigate the impact of POD antenna parameter on the determination of precise satellite orbit. Furthermore, the effect of the accuracy of the determined satellite orbit on the retrieved atmospheric and ionospheric parameters is also examined. The CHAMP data, the FORMOSAT-3 satellite and orbit parameters, the Bernese 5.0 software, and the occultation data processing system are used in this work. The results show that 8 cm error on the POD antenna phase center can result in ~8 cm bias on the determined orbit and subsequently cause 0.2 K deviation on the retrieved atmospheric temperature at altitudes above 10 lan.

• 천문학회보
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• 제37권2호
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• pp.125.1-125.1
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• 2012

The wave number 4 (wave-4) and wave number 3 (wave-3) longitudinal structures in the thermospheric neutral mass density are understood as tidal structures driven by diurnal eastward-propagating zonal wave number 3 (DE3) and wave number 2 (DE2) tides, respectively. However, those structures have been identified using data from limited time periods, and the consistency and recurrence of those structures have not yet been examined using long-term observation data. We examine the persistence of those structures by analyzing the neutral mass density data for the years 2001-2008 taken by the CHAllenging Minisatellite Payload (CHAMP) satellite. During years of low solar activity, the amplitude of the wave-4 structure is pronounced during August and September, and the wave-4 phase shows a consistent eastward phase progression of $90^{\circ}$ within 24 h local time in different months and years. During years of high solar activity, the wave-4 amplitude is small and does not show a distinctive annual pattern, but the tendency of the eastward phase shift at a rate of $90^{\circ}$/24 h exists. Thus the DE3 signature in the wave-4 structure is considered as a persistent feature. The wave-3 structure is a weak feature in most months and years. The amplitude and phase of the wave-3 structure do not show a notable solar cycle dependence. Among the contributing tidal modes to the wave-3 structure, the DE2 amplitude is most pronounced. This result may suggest that the DE2 signature, although it is a weak signature, is a perceivable persistent feature in the thermosphere.

• 미술이론과 현장
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• 제6호
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• pp.51-76
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• 2008

Nous obserbons dans le champs de l'art aujourd' hui, le changement radical provoquant $\'{e}$tant donn$\'{e}$ que le pouvoir du march$\'{e}$ de l'art s'augmente de plus en plus. C'est pour cela que le champ du discours de l'art n'est actuellement plus form$\'{e}$ par des notions esth$\`{e}$tiques artistiques, mais par celles qui sont r$\'{e}$serv$\'{e}$es au domaine de l'$\'{e}$conomie et du march$\'{e}$. Il n'est plus significatif de croire la valeur esth$\`{e}$tique de l'oeuvre d'art, puisque l'esth$\`{e}$tique elle-m$\^{e}$me ne fonctionne plus. Par contre, le syst$\`{e}$me de donner le prix $\`{a}$ l'oeuvre d'art fonctionne rigoureusement. En plus, cette situation s'aggrave $\'{e}$tant donn$\'{e}$ que la mondialisation du march$\'{e}$ de l'art s'installe avec rapidit$\'{e}$. Malgr$\'{e}$ la mondialisation de l'art, des gens qui habitent par exemple $\`{a}$ S$\'{e}$oul ne peuvent pas s' approcher facilement de ce qui se passe $\`{a}$ New York, le vrai centre de l'art contemporain. Dans cette situation, le champ de discours de l'art n'a pas d'autre solution de se r$\'{e}$tr$\'{e}$cir remaquablement et le sujet de discussion sur le grand art est remplac$\'{e}$ par celui du success de l'art. Cette recherche est arriv$\'{e}$e $\`{a}$ remarquer que le syst$\`{e}$me du foire internationale de l'art fonctionne comme une locomotive dans le march$\'{e}$ de l'art qui est le vrai dominateur de l'art contemporain. Aujourd'hui les grands clients du monde de l'art et les jeunes sp$\'{e}$ctateurs, les clients de l'avenir s'assemblent autour de quelques foires internationales r$\'{e}$put$\'{e}$s qui ont de l'autorit$\'{e}$. C'est ainsi que l'achat et la vante de l'oeuvres d'art est suffisamment mondialis$\'{e}$ et que le syst$\`{e}$me local du march$\'{e}$ est d$\'{e}$rang$\'{e}$ et s'$\'{e}$ffondr$\'{e}$gravement. Malgr$\'{e}$ la diff$\'{e}$rence significative, la majorit$\'{e}$ des galeries d'art lacaux s'oblige de suivre $\`{a}$ la suite du style du foire internationale de l'art. C'est la raison pour laquelle que cette recherche se fait une id$\'{e}$e nette que la prosp$\'{e}$rit$\'{e}$ actuelle du march$\'{e}$ de l'art n'est que la situation $\'{e}$conomique ou financi$\`{e}$re. A ce stade de la r$\'{e}$flexion, cette recherche arrivera $\`{a}$ poser une question primordiale ci-dessous: "Si l'art qu'on $\`{a}$ l'intention de proclamer ne serai plus possible de faire r$\'{e}$fl$\'{e}$chir sur la libert$\'{e}$ et la solidarit$\'{e}$ humain, la dignit$\'{e}$ de l'homme, cet art n'est plus autre chose que l'insignifiance. Au lieu de parcourir divers ph$\'{e}$nom$\`{e}$ne du march$\'{e}$ de l'art aujourd'hui, cette recherche fixera son attention sur la r$\'{e}$alit$\'{e}$ du foire internationales de l'art. Dans ce context, cette recherche sera compos$\'{e}$e par trois chapitres donc le premi$\`{e}$re essayera de r$\'{e}$pondre $\'{a}$ la question de son influence extraodinairement puissante. Le deuxi$\`{e}$me chapitre essayera d'analiser la r$\'{e}$alit$\'{e}$ et la source du pouvoir du foire internationale de l'art. Nous essayeront au troisi$\`{e}$me chapitre de configurer le point de vue critique qui permettra de bien comprendre notre sujet.

• 한국균학회지
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• 제30권2호
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• pp.73-77
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• 2002

본 연구는 농업과학기술원 응용미생물과에 보존된 망태버섯속(Dictyophora sp.)에 대한 인공배양 자실체 및 균사체의 형태적 특징을 관찰하였다. 이 버섯의 알과 성숙한 자실체는 대, 치마, 갓, 대주머니로 이루어져 있다. 알은 타원형으로 내피막, 젤라틴층, 외피막으로 싸여 있으며, 표면에는 백색의 침상 균사돌기로 싸여 있다. 성숙한 자실체는 대주머니 안에 젤라틴층이 액화되어 남아 있으며, 포자는 갓 위에 짙은 녹색의 포자층을 형성하고 있다. 치마는 대주머니 위로 길게 내려오고, 그물망의 눈은 다각형이며, 밤꽃 냄새가 난다. 균사체에서 후막포자 모양의 팽대세포(swelling cell)가 확인되었으며, clamp connection도 존재하였다. 본 연구를 통하여 공시균주 KACC 50650은 Dictyophora echinovolvata로 동정되었으며, 한국명으로는 '흰돌기망태버섯'으로 명명하고자 한다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2004년도 대한지구물리학회.한국지구물리탐사학회 공동학술대회 초록집
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• pp.3-17
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• 2004

Space-borne Earth observation technique is one of the most cost effective and rapidly advancing Earth science research tools today and the potential field and micro-wave radar applications have been leading the discipline. The traditional optical imaging systems including the well known Landsat, NOAA - AVHRR, SPOT, and IKONOS have steadily improved spatial imaging resolution but increasing cloud covers have the major deterrent. The new Earth observation satellites ENVISAT (launched on March 1 2002, specifically for Earth environment observation), ALOS (planned for launching in 2004 - 2005 period and ALOS stands for Advanced Land Observation Satellite), and RADARSAT-II (planned for launching in 2005) all have synthetic aperture radar (SAR) onboard, which all have partial or fully polarimetric imaging capabilities. These new types of polarimetric imaging radars with repeat orbit interferometric capabilities are opening up completely new possibilities in Earth system science research, in addition to the radar altimeter and scatterometer. The main advantage of a SAR system is the all weather imaging capability without Sun light and the newly developed interferometric capabilities, utilizing the phase information in SAR data further extends the observation capabilities of directional surface covers and neotectonic surface displacements. In addition, if one can utilize the newly available multiple frequency polarimetric information, the new generation of space-borne SAR systems is the future research tool for Earth observation and global environmental change monitoring. The potential field strength decreases as a function of the inverse square of the distance between the source and the observation point and geophysicists have traditionally been reluctant to make the potential field observation from any space-borne platforms. However, there have recently been a number of potential field missions such as ASTRID-2, Orsted, CHAMP, GRACE, GOCE. Of course these satellite sensors are most effective for low spatial resolution applications. For similar objects, AMPERE and NPOESS are being planned by the United States and France. The Earth science disciplines which utilize space-borne platforms most are the astronomy and atmospheric science. However in this talk we will focus our discussion on the solid Earth and physical oceanographic applications. The geodynamic applications actively being investigated from various space-borne platforms geological mapping, earthquake and volcano .elated tectonic deformation, generation of p.ecise digital elevation model (DEM), development of multi-temporal differential cross-track SAR interferometry, sea surface wind measurement, tidal flat geomorphology, sea surface wave dynamics, internal waves and high latitude cryogenics including sea ice problems.

• 한국언론정보학보
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• 제75권
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• pp.9-42
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• 2016

이 연구는 한국 사회 남성들의 명품 소비가 갖는 사회문화적 의미는 무엇이며, 개인이 명품 제품에 어떤 의미를 부여하고 또 이를 소비하는 과정에서 어떤 경험과 실천을 하는지 분석하고 있다. 이러한 의미와 실천을 둘러싼 일련의 과정들이 개인의 삶에 개입되는 방식과 이들의 총합으로서 한국 사회의 브랜드 소비와 물질문화를 둘러싼 다기한 지형과 문화정치를 비판적으로 독해하고 있다. 연구 방법으로 30대 남성 9명을 대상으로 심층면접을 통해 이들의 명품 소비 경험을 수집하였다. 연구 대상자들은 자기표현이나 타인과의 관계를 위한 상징적 욕구의 충족과 정체성 및 라이프스타일(lifestyle)의 연장선상에서 명품 제품을 소비하고 있었다. 이들에게 명품은 애착의 대상일 뿐 아니라, 새로운 관계와 자기 정체성의 형성 과정으로서 이를 소비하는 일련의 활동을 통해 지속적인 만족감이나 자기 효능감을 경험한다. 이들은 자신의 준거 집단으로부터 브랜드 소비 양식을 학습하면서 명품과 명품이 아닌 제품을 혼용해 사용하는 포스트모던(postmodern)적 소비 행태와 전략을 드러내기도 한다. 한국 사회에서 적절한 명품소비는 타자와의 관계에서 우위를 점하기 위한 전략이나 필요로 인식되며, 이에서 파생되는 기호들은 현대사회의 남성성이 경제적 자본과 연동되는 자기관리, 자기계발 등의 가치와 불가분의 관계에 있음을 시사한다.