• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1005-1007
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• 2005

A Nonlinear approach to control of Small Scale Rotary Wing Unmanned Aerial Vehicle (R-UAV) is presented. Using Backstepping, a globally stabilizing control law is derived. We derive backstepping control law for angle of attack and sideslip control. The inherent nonlinear nature of the system are considered here which helps in naturally stabilizing without extensive external effort. Thus, the resulting control law is much simpler than if the feedback linearization had been used.

• 대한생식의학회:학술대회논문집
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• 2007.11a
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• pp.98.2-99
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• 2007

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.3
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• pp.51-60
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• 1998

Base isolation is an innovative design strategy that provides a practical alternative for the seismic design of structures. Base isolators, mainly employed to isolate large structures subjected to earthquake ground excitations and to rehabilitate structures damaged by past earthquakes, deflect and absorb the seismic energy horizontally transmitted to the structures. This study demonstrated that the base isolation system may offer effective performance for bridges during severe seismic events through shaking table tests. Two base isolation systems using laminated rubber bearings with and without hydraulic dampers are tested. The test results strongly show that the laminate rubber bearings cause the natural period of the bridge structure increased considerably, which results in the deck acceleration and the shear forces on the deck acceleratino and the shear forces on the piers reduced significantly. The results also demonstrate that the hydraulic dampers enhance the system's capacity in dissipating energy to reduce the relative displacement between the bridge deck and the pier.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.141-146
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• 2002

It becomes common to use computers to control electronic devices and security facilities in newly constructed buildings and house. There are many home application devices in the market which can be controlled by computers. But they are expensive and managed by specialized companies. This paper is focused on personal computers which are available in most homes and can be used to control home electronic appliances and home security facilities. We implemented a home automation server based on Linux. The standard parallel port of personal computer is used to connect sensors and actuators. Therefore, the cost of the server is very low. Moreover, the server is connected to Internet and anywhere we can control and monitor the home security facilities and home automation systems.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.903-908
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• 2007

휴대용 모바일 디바이스의 입력 장치로는 스타일러스나 터치 스크린의 채용이 가장 일반적이나, 이들 방식을 사용하기 위해서는 사용자는 두 손을 모두 사용해야 하는 불편함이 있다. 이러한 문제점을 해결하기 위해 가속도나 자이로 센서를 이용한 tilt navigation이 많은 관심을 받고 있다. Tilt navigation은 한 손으로 모바일 디바이스를 잡고 기울임으로써 원하는 기능이나 항목을 선택할 수 있는 장점이 있으나, 사용자에게 익숙하지 않아 아직 보편화 되지 않고 있다. 본 연구는 tilt navigation에서 사용자가 원하는 메뉴나 항목을 보다 쉽게 찾아 갈 수 있도록 메뉴 또는 항목 간의 이동 속도를 제어하는 알고리즘을 제안하고자 한다. 제안하는 알고리즘은 목표 항목을 찾아 가는 과정에서 과거의 기울임 정보를 바탕으로 목표 아이템이 존재하는 범위를 설정하고, 항목 간의 이동 속도를 범위의 크기에 비례하도록 설정하여 사용자가 목표 아이템을 보다 편리하게 찾고 선택할 수 있도록 한다. 또한 본 연구에서는 가속도 센서를 장착한 PDA를 이용하여 기존의 tilt navigation과 제안하는 알고리즘이 적용된 tilt navigation과의 목표 아이템을 찾아가는데 걸리는 소요 시간을 비교하여, 제안하는 알고리즘의 효과를 보이고자 한다.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.577-580
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• 2006

As this study is to estimate resistance of cement mortars using crushed sand under chemical attacks. Besides tests have been carried out with cement mortars by river sand and crushed sand by fine sand, cement mortars mix various proportions of silica fume and fly ash(up to 15% and 50% by weight for cement) were prepared and immersed in pure water, sodium sulfate solution, magnesium sulfate solution, seawater for 28days, 60days, 90days and 180days. Test on the change in the weight and compressive strength of cement mortars according to the duration of immersion time and the content of silica fume and fly ash was performed.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.04a
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• pp.430-433
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• 2004

본 논문은 이동 로봇의 조작에 관한 것으로, 특히 로봇의 이동 경로 또는 목적지를 사용자가 매우 직관적으로 설정할 수 있도록 하는 조작 방법에 관한 것이다.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.7
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• pp.666-674
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• 2001

Classical methods to find a minimal set of rules based on the rough set theory are known to be ineffective in dealing with new instances added to the universe. This paper introduces an inductive learning algorithm for incrementally retrieving a minimal set of rules from a given decision table. Then, the algorithm is validated via simulations with two sets of data, in comparison with a classical non-incremental algorithm. The simulation results show that the proposed algorithm is effective in dealing with new instances, especially in practical use.

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.117-122
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• 2012

We propose a hybrid multiple access (HMA) for uplink orthogonal frequency division multiple access (OFDMA) systems, which combines two resource sharing schemes: a scheduling-based resource allocation (SBRA) scheme and a contentionbased resource allocation (CBRA) scheme. The SBRA scheme is appropriate for non-real time high data rate traffic, and, CBRA is appropriate for near-real time low/medium data rate traffic. Thus, the proposed HMA scheme supports various types of traffic. As a CBRA scheme, our proposed random frequency hopping (RFH)-OFDMA scheme was presented. Simulation results show that the proposed HMA yields the best performance among various resource allocation schemes for uplink OFDMA systems.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.364-371
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• 2004

This study presented the reinforcing effect of sands by newly devised $Tirecell^{(R)}$ made by waste tires, tire mat by sidewalls of tires and Geocell. Plate loading tests were conducted for different reinforcing materials at the same condition. The combination of Tirecell and sidewall gives the highest increase of bearing capacity and reduction of settlement. The Geocell with the same hight of Tirecell gives similar reinforcement effect to the tire mat made by sidewalls.