• Journal of Astronomy and Space Sciences
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• 제20권2호
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• pp.133-142
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• 2003

접촉쌍성은 물리적 특성에 따라 5가지의 유형으로 분류되고 있다. 그러나 이와 같은 분류 이외에도 질량비가 극단적으로 작은(q＜0.2) 접촉쌍성이 또 다른 유형으로 분류됨을 확인하였다. Svechnikov & Kuznetsova(1990)의 목록에 따르면 이러한 유형의 접촉쌍성은 주성의 분광형이 A형의 한정된 영역에 분포하며 여러 가지 물리적 특성에 있어서 조기형 접촉쌍성과 만기형 접촉쌍성을 양분하는 중심 영역에 분포하고 있다.

• 기술혁신연구
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• 제6권2호
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• pp.178-207
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• 1998

This article suggests a methodology to decide the priority of investment project for venture business under the dynamic circumstance. By the Monte Carlo procedure on the probability distribution of cost and revenue, the model simulates the investment project to estimate profit ratio and risk. The profit ratio is calculated on the yearly basis for the relative comparison. The project risk is calculated as semi-variance under the target yield. After sufficient simulations in this fashion for several projects, the efficient projects with more profit and less risk are selected by the dominance principle. Then the regression equation of the selected projects is produced to find the relative value of the projects. The relative value is obtained through dividing the raw profit ratio by the estimated one on the equation. This value shows the degree to which the simulated project yields over the equation. The priority of investment is decided by this value. An examplary venture business of chemical development for semi-conductor is presented as a case study.

• 한국주거학회논문집
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• 제14권6호
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• pp.51-58
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• 2003

When apartment buildings are builed and re-builded, they tends to be taller. This tendency causes the problems for solar access and view in the neighboring area. So the impact factor of sunlight and view by apartment building in its neighboring area is examined. The results of this study are as follows： When analyzing sky view by dividing the sky vault into the differential area, the analysis of view can be efficient. The shorter the apartment building, the more the continuous solar access time. And the taller the building, the more the accumulated solar access time. As the height of building is taller and it is farther from the border of apartment building, view ratio, sky view ratio, and form ratio are increased. It implies that the slimmer the building, the more the visual environment can be improved.

• 산업경영시스템학회지
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• 제37권4호
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• pp.202-211
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• 2014

Pairs trading is a type of arbitrage investment strategy that buys an underpriced security and simultaneously sells an overpriced security. Since the 1980s, investors have recognized pairs trading as a promising arbitrage strategy that pursues absolute returns rather than relative profits. Thus, individual and institutional traders, as well as hedge fund traders in the financial markets, have an interest in developing a pairs trading strategy. This study proposes pairs trading rules (PTRs) created from a price ratio between securities (i.e., stock index futures) using rough set analysis. The price ratio involves calculating the closing price of one security and dividing it by the closing price of another security and generating Buy or Sell signals according to whether the ratio is increasing or decreasing. In this empirical study, we generate PTRs through rough set analysis applied to various technical indicators derived from the price ratio between KOSPI 200 and S&P 500 index futures. The proposed trading rules for pairs trading indicate high profits in the futures market.

• 센서학회지
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• 제7권4호
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• pp.293-299
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• 1998

본 연구의 목적은 22.9 kV-y 특별고압 배전선로상에서 가스절연개폐기를 이용한 전압측정장치의 개발에 있다. 본 논문에서 제안한 전압측정장치는 일종의 광대역 용량성 분압기로, 가스개폐기의 절연붓싱에 설치한 검출전극, 임피던스 정합회로 및 전압버퍼로 구성되며, 기설의 가스절연개폐기에 구조 변경 없이 설치될 수 있다. 제작된 전압측정장치는 교정과 적용성 평가를 위하여 25.8 kV, 400 A 가스절연개폐기에 설치되었으며, 5 ns의 상승시간을 갖는 직각파 발생기로 주파수 응답특성을 조사하였다. 실험결과로부터 본 전압측정장치의 주파수 대역은 1.35 Hz에서 약 13 MHz이었으며, 60 Hz 상용주파수 전압에서 분압비 오차는 0.2% 이하였다. 또한 상용주파수 전압과 비진동성 충격전압에 대한 분압비와의 편차는 0.7% 이하로 나타났다.

• 반도체디스플레이기술학회지
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• 제21권4호
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• pp.45-49
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• 2022

Through Silicon Via (TSV) is a technology that interconnects chips through silicon vias. TSV technology can achieve shorter distance compared to wire bonding technology with excellent electrical characteristics. Due to this characteristic, it is currently being used in many fields that needs faster communication speed such as memory field. However, there is performance degradation issue on TSV technology due to the parasitic capacitance. To deal with this problem, in this study, the parasitic capacitance with TSV design factors is analyzed using commercial tool. TSV design factors were set in three categories: size, aspect ratio, pitch. Each factor was set by dividing the range with TSV used for memory and package. Ansys electronics desktop 2021 R2.2 Q3D was used for the simulation to acquire parasitic capacitance data. DOE analysis was performed based on the reaction surface method. As a result of the simulation, the most affected factors by the parasitic capacitance appeared in the order of size, pitch and aspect ratio. In the case of memory, each element interacted, and in the case of package, it was confirmed that size * pitch and size * aspect ratio interact, but pitch * aspect ratio does not interact.

• Smart Structures and Systems
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• 제1권3호
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• pp.283-308
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• 2005

This paper features about the modeling and design of a fast output sampling feedback controller for a smart Timoshenko beam system for a SISO case by considering the first 3 vibratory modes. The beam structure is modeled in state space form using FEM technique and the Timoshenko beam theory by dividing the beam into 4 finite elements and placing the piezoelectric sensor/actuator at one location as a collocated pair, i.e., as surface mounted sensor/actuator, say, at FE position 2. State space models are developed for various aspect ratios by considering the shear effects and the axial displacements. The effects of changing the aspect ratio on the master structure is observed and the performance of the designed FOS controller on the beam system is evaluated for vibration control.

• 통합자연과학논문집
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• 제13권1호
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• pp.1-7
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• 2020

This paper proposes a novel fractional frequency reuse(FFR) based on dynamic user distribution. In the FFR, a macro cell is divided into two regions, i.e., the inner region(IR) and outer region(OR). The criterion for dividing the IR and OR is the distance ratio of the radius. However, these distance-based criteria are uncertain in measuring user performance. This is because there are various attenuation phenomena such as shadowing and wall penetration as well as path loss. Therefore, we propose a novel FFR based on dynamic user classification with signal to interference plus noise ratio(SINR) of macro users and classify the FFR into two regions newly. Simulation results show that the proposed scheme has better performance than the conventional FFR in terms of SINR and throughput of macro cell users.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.155-158
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• 2009

During the construction project period, a lot of change orders happen in the design and construction stage Especially, The change order during construction stage causes the huge construction cost increase and duration delay. Accordingly, research on the change order of the construction stage is being progressed relatively active in the design stage, but the design changes are rarely made. In the design stage, the owner has to pay a design addition cost when change order due to the demands of owner happens. However Korea has not the specific standard about design additional cost in design stage. Therefore, this study analyzes problems of design additional cost estimation methods through the case study, and then indicates the method that the ratio distributes to details dividing design tasks and the method of the PM(Project Management). Eventually, this study expects to minimize claim related the design additional cost in design stage.

• Steel and Composite Structures
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• 제42권5호
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• pp.711-722
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• 2022

In this paper, hyperbolic shear deformation plate theory is developed for thermal buckling of functionally graded plates with porosity by dividing transverse displacement into bending and shear parts. The present theory is variationally consistent, and accounts for a quadratic variation of the transverse shearstrains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. Three different patterns of porosity distributions (including even and uneven distribution patterns, and the logarithmic-uneven pattern) are considered. The logarithmic-uneven porosities for first time is mentioned. Equilibrium and stability equations are derived based on the present theory. The non-linear governing equations are solved for plates subjected to simply supported boundary conditions. The thermal loads are assumed to be uniform, linear and non-linear distribution through-the-thickness. A comprehensive parametric study is carried out to assess the effects of volume fraction index, porosity fraction index, aspect ratio and side-to-thickness ratio on the buckling temperature difference of imperfect FG plates.