• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.517-520
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• 2003

Commercial video scope use CCD sensor and frame grabber for image capture and A/D interface but application limited by input resolution and high cost. In this paper we introduce portable video scope using CMOS sensor, USB pen and tuner card (low frame grabber) in place of commercial CCD sensor and frame grabber. Our video scope serves as an essential link between advancing commercial technology and research, providing cost effective solutions for educational, engineering and medical applications across an entire spectrum of needs. The software implementation is done using Direct Show in second version after initial trials using First version VFW (video for window), which gave very low frame rate. Our video scope operates on windows 98, ME, XP, 2000. The drawback of our video scope is crossover problem in output images caused due to interpolation, which has to be rectified for more efficient performance.

• ETRI Journal
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• 제37권4호
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• pp.657-666
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• 2015

We propose a two-stage resource allocation algorithm for the high link utilization of an orthogonal frequency-division multiplexing passive optical network (OFDM-PON). An OFDM-PON is assumed to use a synchronous frame structure in supporting service differentiation. In distributing resources, the proposed algorithm first allocates a time window for each optical network unit (ONU), and then it arranges a subchannel, which is a group of subcarriers. This algorithm needs to satisfy two constraints. First, computations for the resource allocation should be done using a frame unit. Second, an ONU has to use a single subchannel to send upstream data for multiple services within a frame duration. We show through a computer simulation that the proposed algorithm improves the link utilization.

• 한국레이저가공학회지
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• 제18권1호
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• pp.1-6
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• 2015

High welding speed and narrow weld seam are favorable for welding of magnesium alloy. Magnesium alloy is recommended for the smart frame because it has several advantages such as low density, high thermal conductivity, EMI shielding capability and good cast ability. This study is for the assembly welding of the magnesium smart frame with high productivity, good performance and low cost. The window for battery on AZ91D frame produced by die-casting was prepared by CNC machining. Corresponding AZ31 blank of 0.2mm thickness was prepared by die-blanking cut. All system set was fixed at the stationary bed but the laser beam was manipulated by scanner up-to 1,000mm/s speed. The weld joint between AZ31 sheet and AZ91D frame was welded by fiber laser on 850~1,000W output power. The joint showed penetration enough but some humping bead. The distortion by the weld heat was almost free because of the quick dissipation of the heat by small beam size and fast welding. Consequently, the thinner magnesium foil was assembled successfully to the magnesium frame of mobile phone.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
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• pp.35-38
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• 2004

In this paper, we investigate and analyze the problems encountered in frame-based estimation of TDOA(Time Difference of Arrival) using CPSP function. Spectral leakage occurring in framing of a speech signal by a rectangular window makes estimation of CPSP spectrum inaccurate. Framing with a Hamming window to reduce the spectral leakage effect distorts the signal due to the different weighting at temporally same sample, which make the TDOA estimation using CPSP function inaccurate. In this paper, we solve this problem by reducing the dynamic range of the spectrum of a speech signal with preemphasis. Experimental results confirm that the framing of pre-emphasized microphone output with a rectangular window shows higher success ratio of TDOA estimation than any other framing methods.

• 에너지공학
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• 제24권4호
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• pp.63-70
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• 2015

창문에서의 틈은 열 손실 뿐만 아니라 차음 성능에도 중대한 결함으로 작용되며, 특히 인체에 유해한 미세먼지 유입 경로로도 작용된다. 이러한 틈을 제거하기위해 많은 시도들이 이루어지고 있으나, 창문의 고유 기능인 이동특성으로 인해 해결하기 어려운 난제로 인식되어왔다. 본 연구는 이를 해결하기위해 수평 회전 휠과 곡선 레일을 적용한 새로운 유형의 미서기 창문을 제작하고, KS 시험 기준에 따라 사용성, 내구성, 기밀성능, 등의 성능 시험을 하였다. 시험 결과, 개폐력은 2000 N 중량의 창문에서 30 N, 개폐 반복성 시험에서는 100,000 cycles, 기밀성 시험에서는 10 Pa에서 $0.00m^3/(m^2h)$의 성능을 보여주었다. 상기 시험 결과, 새로운 구동 방식을 지닌 본 연구에서의 창문은 기밀성과 경제적 측면에서 새로운 접근 방식을 제시하고 있다.

• 한국통신학회논문지
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• 제39C권5호
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• pp.425-432
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• 2014

IEEE 802.11e EDCA(Enhanced Distributed Channel Access)는 서로 다른 AC(Access Category)에 따라서 CW(Contention Window)를 이용하여 Quality-of-Service(QoS)를 지원한다. 그러나 무선 네트워크 환경이 혼잡 (Congested)할 경우 패킷의 충돌 발생 확률을 높일 수 있다는 문제점이 여전히 존재한다. 이를 해결하기 위해 여러 방법들이 제시되었으나 혼잡 네트워크상에서는 동일 우선순위를 가지는 패킷 전송을 위해서 전송 채널을 이용하는 경쟁 과정에서 패킷 충돌(Collision)이 발생할 확률이 여전히 존재한다. 따라서 본 논문에서는 EDCA 포화 상태에서 전송 효율을 높이는 APCA(Advanced Priority Collision Avoidance) 알고리즘을 제안한다. 제안된 알고리즘은 IEEE 802.11e 표준을 기반으로 RTS/CTS (Request to Send / Clear to Send)를 이용하여 패킷 전송 FC(Frame Control) 필드의 예약된 필드(Reserved Field) 비트를 이용하여 데이터 패킷 충돌을 회피하는 것이다. 시뮬레이션의 결과로 제안된 알고리즘이 기존의 EDCA에 비해 패킷 전송 실패율이 감소했음을 보였다. Jain's fairness index를 이용하여 제안된 APCA 알고리즘이 네트워크 혼잡 상황에서 EDCA 방식 보다 공정성을 유지하는 것을 확인하였다.

• 정보처리학회논문지B
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• 제14B권7호
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• pp.473-480
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• 2007

비디오 영상 프레임들에서 2D 특징점들을 지속적으로 추적하는 문제는 프레임 간의 빈번한 특징점 매칭 실패로 인하여 어려움을 겪어왔다. 본 논문에서는 긴 비디오 프레임들에서 강건하게 2D 특징점들을 추적하는 기법을 제안한다. 이전 프레임까지 추적되어온 각 특징점에 대해 움직임 상태변수를 정의하고 이들 상태변수로부터 현재 프레임에서의 움직임을 예측한다. 예측된 움직임은 추적을 위한 탐색 윈도우를 설정을 위한 초기 위치로 지정된다. 유사성 검사를 통해서 탐색 윈도우 내에서 대응점을 결정한다. 측정 데이터를 반영하여 현재 프레임에서의 특징점의 움직임 상태 변수를 수정하는 과정을 갖는다. 특징점의 추적 결과는 오차를 포함하고 있고 잘못된 추적이 발생될 수 있다. 잘못 추적된 이상값들은 RANSAC 알고리즘을 적용하여 제거함으로써 정확한 특징점 추적이 지속될 수 있도록 한다. 실제 비디오 프레임들에 대해 특징점 추적을 실시한 결과 긴 비디오 프레임들에 대해서도 특징점 추적이 안정적으로 수행됨을 확인할 수 있었다.

• KIEAE Journal
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• 제16권3호
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• pp.77-82
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• 2016

Purpose: The aim of this study is to calculate U-factor of the window using international standard methods and compare quantitative and tendency difference focused on ISO standard 15099 and ISO standard 10077. And the result of ISO standard calculation methods is verified using thermal performance experiment to evaluate applicability of domestic certification system. This study is utilized a basis for activation of domestic window certification system. Method: First, 16 cases are selected that is combined a variety of frame, Glazing, spacer, etc. The selected cases were simulated using WINDOW&THERM based on ISO 15099 and 10077 calculation method. Second, experiment was conducted based on Korean standard condition. Then, it was compared the error of experiment and simulation results. Through this process, ISO 15099 and 10077 calculation methods were evaluated accuracy and utilization. Result: The results show that the difference of ISO 15099 and ISO 10077-2 is maximum 5.4%. The results of comparing U-factor errors based on the Korea standard experiment test found 2.4%. Consequently, it will be possible to combination calculation methods of ISO 15099 and ISO 10077 for a single window.

• 대한기계학회논문집A
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• 제27권5호
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• pp.681-687
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• 2003

Terrain surfaces have to be modeled in very detail and wheel-surface contacting geometry must be well defined in order to obtain proper ground-reaction and friction forces fur realistic simulation of off-road vehicles. Delaunay triangulation is one of the most widely used methods in modeling 3-dimensional terrain surfaces, and the T-search is a relevant algorithm for searching resulting triangular polygons. The T-search method searches polygons in a successive order and may not allow real-time computation of off-road vehicle dynamics if the terrain is modeled with many polygons, depending on the computer performance used in the simulation. The dynamic T-search, which is proposed in this paper, combines conventional T-search and the concept of the dynmaic-window search which uses reduced searching windows or sets of triangular surface polygons at each frame by taking advantage of the information regarding dynamic charactereistics of a simulated vehicle. Numerical tests show improvement of searching speeds by about 5% for randomly distributed triangles. For continuous search following a vehicle path, which occurs in actual vehicle simulation, the searching speed becomes 4 times faster.

• 한국기계가공학회지
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• 제13권4호
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• pp.106-112
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• 2014

This study presents the mechanical behavior of a ventilating window (a tsunami damper) on the building wall of a nuclear power plant. The window, which is under development, is used to ventilate a machinery room and the building under normal conditions, but it also provides a safety barrier for critical equipment against a tsunami caused by an earthquake. A finite element analysis was conducted to investigate the deflection and the stress distribution of the window under given loading conditions. With symmetry, a one-quarter portion of one window was modeled, and the pressure due to a great tide is assumed to be 7 bar. A structural analysis of the assembled frame, composed of a blade and casing, was also conducted using contact conditions to find the stress and strain configurations caused by the applied pressure.