• Journal of Positioning, Navigation, and Timing
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• 제6권4호
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• pp.195-203
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• 2017

A 2U cube satellite called SNUGLITE has been developed by GNSS Research Laboratory in Seoul National University. Its main mission is to perform actual operation by mounting dual-frequency global positioning system (GPS) receivers. Its scientific mission aims to observe space environments and collect data. It is essential for a cube satellite to control an Earth-oriented attitude for reliable and successful data transmission and reception. To this end, an attitude estimation and control algorithm, Attitude Determination and Control System (ADCS), has been implemented in the on-board computer (OBC) processor in real time. In this paper, the Extended Kalman Filter (EKF) was employed as the attitude estimation algorithm. For the attitude control technique, the Linear Quadratic Gaussian (LQG) was utilized. The algorithm was verified through the processor in the loop simulation (PILS) procedure. To validate the ADCS algorithm in the ground, the experimental verification via a single axis Hardware-in-the-loop simulation (HILS) was used due to the simplicity and cost effectiveness, rather than using the 3-axis HILS verification (Schwartz et al. 2003) with complex air-bearing mechanism design and high cost.

• 건축역사연구
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• 제11권2호
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• pp.23-35
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• 2002

Even though there have been greate changes in the types and contents of the housing plan in Korea since the Modem age, it seems that the identity of traditional dwelling culture is still remains within it. The purpose of this study is to examine the characteristics and features in the development of the 'Public Standard' Housing Unit Plan by comparing the differences and similarities in unit plans in housings built on Japanese occupation period and those built after the period. From the study, we can conclude as follows: 1. The public standard housing unit plans on both periods have shown the common features in the composition of their physical forms in the way that the front-row area still remains the traditional housing culture and the rear-row area reflects the desires of the modem lives. The structure of the dual-row unit plan appeared in the public standard housing plan was caused by the cultural acculturation in Japanese occupation period. 2. The public standard housing unit plans, however, show the differences in the contents and meaning in units plans with the them of the Japanese housing because of the cultural differences. These differences took placed autonomously through the change of housing plans in the modern time, and have the common features such that 1) the changes in the Maru-centered plan type differ in composition from the inner-corridor plan type used Japanese housing, and 2) the composition of the open-inner spaces in the double-row housing plan reflects the single-row outer open space In the traditional housing. All of these cultural progresses in the public standard housing unit plans was took place as the result of the inner-oriented and notional circulations derived from the modernity. However, the transformed unit plans still contains the identity derived from the variation of the traditional Korean building elements such as Maru and Ondol. In other words, those are the Maru-centered and composed housing plans with juxtaposition of the inner block and the outer block. As the conclusion, though the public standard dwelling unit plan has the similarity in the physical form, it is different in the cultural Identity and meaning from the public standard plans before the independence from the Japan occupation.

• 한국컴퓨터정보학회논문지
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• 제16권12호
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• pp.235-246
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• 2011

현재 우리는 사회, 문화, 정치, 경제, 기술에 있어 국가 간의 경계가 무너지는 글로벌화와 다 분야 기술의 컨버전스 및 이종 서비스의 융합이 광범위하게 진행되는 시대에 살고 있고, 이러한 변화의 물결은 지식과 정보 사회를 넘어서 스마트 사회로의 진입을 재촉하고 있다. 과거에는 방대한 양의 지식과 정보를 생성하고, 가공하며, 축적하는 것에 집중했다면, 현재 사회는 이러한 축적된 지식과 정보를 시공간의 제약 없이, 보다 지능적이면서, 저렴하게, 융합된 형태로 제공될 수 있기를 기대하고 있다. 본 논문에서는 스마트서비스의 개념과 다양한 사례를 살펴보고 지식 정보사회의 서비스 통합 패러다임을고려하여스마트서비스 제공을 위한 플랫폼으로서의 구현요소와 서비스플랫폼 현황분석, 관련기관별 주요역할, 구현요소확보방안 등 스마트 플랫폼 구현전략을 제시하였다.

• 소음진동
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• 제9권1호
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• pp.196-205
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• 1999

6승의 비선형 항을 가지는 두개의 질량으로 구성된 비선형 해밀톤계에 대해서, 비선형 정규모드인 주기운동의 존재성, 분기현상 및 궤도 안정성을 연구하였다. 운동방정식의 직접적분을 통해 4차원 위상공간에서의 운동궤적을 2차원 면으로 투영하는 푸앙카레 사상을 구하였고, 또한 버크 호프-구스타프슨 표준 변환을 통해 구한 운동적분을 이용하여 에너지가 작을때 푸앙카레 사상에 나타나는 불변 곡선들의 해석적인 표현을 유도하였다. 본 논문에서 연구한 진동계는 비선형 계수의 값에 따라 2개 또는 4개의 비선형 정규모드를 가짐이 밝혀졌다. 푸앙카레 사상은, 분기된 모드는 안정하고, 원래의 모드는 안정한 상태에서 불안정한 상태로 변한다는 것을 분명하게 보여주었다.

• 한국해양공학회지
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• 제19권2호
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• pp.67-73
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• 2005

This paper describes depth, heading and speed control of an underwater vehicle that has four stern thrusters of which forces are coupled in the diving and, steering motion, as well as the speed of the vehicle. The optimal linear quadratic controller is designed based on a linearized- state space model, developed by combining the dynamic equations of speed, steering and diving motion. The designed controller gives provides an optimal thrust distribution, minimizing the given performance index to control speed, depth and heading simultaneously. To validate the performance of the controller, a simulation and tank-test are carried out with DUSAUV (Dual Use Semi-Autonomous Underwater Vehicle), developed by KORDI as a test-bed for testing new underwater technologies. Optimal gains of the controller are tuned, using a computer simulation environment with a nonlinear 6-DOF numerical DUSAUV model, developed by PMM (Planner Motion Mechanism) test. To verify the performance of the presented controller in experiment, a tank-test with DUSAUV is carried out in the ocean engineering basin in KORDI. The experimental results are also compared with the simulation results to investigate the accordance of the numerical and the real mode.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2004년도 추계학술대회 논문집
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• pp.111-116
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• 2004

This study is aimed to be used as basic data to plan Korean style cohousing for double-income families in the future by studying their lifestyle, housing needs and housing awareness on cohousing. The results of the study are as follows. 1) As for the life style of the subject families, it was a housewife that mainly does the household affairs despite of the status of double-income family. Also, as for the social activity, almost half of the respondents said that the spending in child-care facilities was not sufficient and wanted to send their children to ones within their neighborhood. 2) As far as housing awareness on cohousing concerned, among specific items, the child care area, the household affairs division area, and participatory awareness of residents in housing planning and management got higher scores, while as for awareness on utilizing common space, using the common hobby rooms, promenades and benches, exercise facilities, common yard, and study rooms got higher scores. When asked about the necessity for cohousing in Korea, they gave very positive answers, but the answer to their willingness to reside in it was less positive. 3) Summarizing the housing needs on cohousing, it turned out that more people wanted to reside in suburban area with others having common grounds with them as for a desirable residence environment. They wanted the neighborhood to be composed of 10${\sim}$29 families, and medium-density semi-detached house occupied by owners. They wanted a mixture of independent management and entrust management for managing common facilities, and common meal once a week. They wanted indoor exercise facilities to be more extended than other common facilities, and the house of $100m^{2}{\sim}130m^{2}$ with 3 bedrooms, 2 bath rooms, and a large living room and dining room.

• 대한수학회지
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• 제46권2호
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• pp.363-447
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• 2009

The author previously defined the spectral invariants, denoted by $\rho(H;\;a)$, of a Hamiltonian function H as the mini-max value of the action functional ${\cal{A}}_H$ over the Novikov Floer cycles in the Floer homology class dual to the quantum cohomology class a. The spectrality axiom of the invariant $\rho(H;\;a)$ states that the mini-max value is a critical value of the action functional ${\cal{A}}_H$. The main purpose of the present paper is to prove this axiom for nondegenerate Hamiltonian functions in irrational symplectic manifolds (M, $\omega$). We also prove that the spectral invariant function ${\rho}_a$ : $H\;{\mapsto}\;\rho(H;\;a)$ can be pushed down to a continuous function defined on the universal (${\acute{e}}tale$) covering space $\widetilde{HAM}$(M, $\omega$) of the group Ham((M, $\omega$) of Hamiltonian diffeomorphisms on general (M, $\omega$). For a certain generic homotopy, which we call a Cerf homotopy ${\cal{H}}\;=\;\{H^s\}_{0{\leq}s{\leq}1}$ of Hamiltonians, the function ${\rho}_a\;{\circ}\;{\cal{H}}$ : $s\;{\mapsto}\;{\rho}(H^s;\;a)$ is piecewise smooth away from a countable subset of [0, 1] for each non-zero quantum cohomology class a. The proof of this nondegenerate spectrality relies on several new ingredients in the chain level Floer theory, which have their own independent interest: a structure theorem on the Cerf bifurcation diagram of the critical values of the action functionals associated to a generic one-parameter family of Hamiltonian functions, a general structure theorem and the handle sliding lemma of Novikov Floer cycles over such a family and a family version of new transversality statements involving the Floer chain map, and many others. We call this chain level Floer theory as a whole the Floer mini-max theory.

• 한국정보과학회논문지:데이타베이스
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• 제30권2호
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• pp.176-183
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• 2003

질의 최적화에 사용하기 위한 선택도 추정 방법은 히스토그램, 샘플링 그리고 패러미터에 의한 요약 방법 등이 제시되고 있다. 히스토그램을 이용한 선택도 추정은 상용 데이타베이스 시스템에서 가장 보편적으로 사용되는 방법이지만, 이동 객체를 위한 시공간 데이타베이스에서는 데이타 분포가 지속적으로 변화함으로써 기존의 히스토그램 방법을 이용하는 것은 제한이 많게 된다. 특히 미래 질의를 위해서는 데이타 갱신을 반영하는 동적 관리가 가능하며, 정화도를 유지할 수 있는 다른 접근 방법이 필요하다. 따라서 시공간 객체를 위한 선택도 추정 방법은 질의 술어가 요구하는 데이타 분포에 대한 히스토그램이 필요하며, 본 논문에서는 미래의 시공간 영역 질의 술어에 대하여 신속히 히스토그램을 생성할 수 있도록 쌍대성과 한계 분포 방법을 이용한 히스토그램을 제안한다. 쌍대 공간에서 이동 객체에 대한 데이타 시놉시스를 이용하여 구성된 시공간 히스토그램은 이동 궤적의 선형성이 유지하는 시간 동안 정확성을 보장하면서 빠른 시간에 생성이 가능하다. 또한 동적 갱신을 점증적으로 지원함으로써 효율적으로 갱신된 정보를 반영할 수 있고 추정 결과의 정확성을 향상시킬 수 있다.

• 한국측량학회지
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• 제24권2호
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• pp.167-173
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• 2006

전리층은 안테나에서 수신되는 GPS 신호에 가장 큰 오차를 유발시킨다. 이중 주파수(L1,L2)를 모두 사용하는 수신기는 두 주파수의 선형조합을 통해 전리층의 오차를 효율적으로 제거할 수 있지만, 단일 주파수 수신기(L1)는 전리층 모델을 이용하여 오차를 계산해야 한다. 본 연구에서는 한국천문연구원에서 운영하는 9개의 GPS 기준국 망 데이터를 이용하여 위 경도 각각 $1^{\circ}{\times}1^{\circ}$의 공간 해상도를 갖는 격자 기반의 새로운 전리층 모델을 개발하였고, 매 관측 시간대별로 한반도 상공의 총전자수(Total Electron Contents, TEC)를 계산하였다. 기존의 Klobuchar 모델과 새롭게 개발된 KASI 전리층 모델에 의한 측위 결과를 서로 비교하였고, 전리층의 총전자수 변화에 따른 모델의 정밀도를 제시하였다.

• 천문학회보
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• 제37권2호
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• pp.107.1-107.1
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• 2012

We present the results of far-ultraviolet (FUV) observations of comet C/2001 Q4 (NEAT) obtained with Far-ultraviolet Imaging Spectrograph (FIMS) on board the Korean microsatellite STSAT-1, which operated at an altitude of 700 km in a sun-synchronous orbit. FIMS is a dual-channel imaging spectrograph (S channel 900-1150 ${\AA}$, L channel 1350-1750 ${\AA}$, ${\lambda}/{\Delta}{\lambda}$ ~ 550) with large image fields of view (S: $4^{\circ}.0{\times}4^{\prime}.6$, L: $7^{\circ}.5{\times}4^{\prime}.3$, angular resolution 5'-10') optimized for the observation of diffuse emission of astrophysical radiation. Comet C/2001 Q4 (NEAT) was observed with a scanning survey mode when it was located around the perihelion between 8 and 15 May 2004. Several important emission lines were detected including S I (1425, 1474 ${\AA}$), C I (1561, 1657 ${\AA}$) and several emission lines of CO $A^1{\Pi}-X^1{\Sigma}^+$ system in the L channel. Production rates of the notable molecules, such as C I, S I and CO, were estimated from the photon fluxes of these spectral lines and compared with previous observations. We compare the flux and the production rates in the radius of $3{\times}10^5$ km with $20{\times}10^5$ km from the central coma. We obtained L-channel image which have map size $5^{\circ}{\times}5^{\circ}$ The image was constructed for the wavelength band of L-channel (1350 - 1710 ${\AA}$. We also present the radial profiles of S I, C I, CO obtained from the spectral images of the central coma. The radial profiles of $2{\times}10^6$ km region are compared with the Haser model.