• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1999년도 전력전자학술대회 논문집
• /
• pp.333-337
• /
• 1999

This paper presents the DQ transfomation space space vector modulation method to devel control algorithm of distribu STATCON(STATic CONdenser) for line volt regulation, dc link voltage regulation harmonics compensation. The Performance an of a PI with ramp comparision and synchro reference frame current controller is carried Based on these analysis, the control perform are desirable to compensate the harmonics a regulate dc link and line voltage of Distrib line.

• 전자공학회논문지B
• /
• 제30B권12호
• /
• pp.21-30
• /
• 1993

In this paper, we propose a connected Korean digit recohnition system employing neural networks and lexical constraints of the Korean digits. In the proposed recognition system, firstly, each frame of digit string is labelled by phoneme classification neural networks.which are trained with the reference phoneme segments extracted form an isolated digit based on the position information. And, the frame labels are combined with each other for constructing the phoneme segments. Then, these segments are combined to form a digit candidate using the digit combination rules. The digit candidate is decided based on the condition for digit decision. If the condition is not satisfied, the digit candidate is further recognized using the digit decision neural network in the next step. In our approach, the neural networks are trained with 10 isolated digits uttered by 5 male speakers. To investigate the performance of the proposed recognition system, an intensive computer simulation on the 30 connected digit strings uttered by 5 male speakers is performed. The simulation result indicates that 95.6% digit recognition rate and 82% digit string recognition rate are provided by the proposed Korean digit recognition system.

• 제어로봇시스템학회논문지
• /
• 제11권7호
• /
• pp.587-594
• /
• 2005

In this paper, a robust correlation-based video tracking is proposed to track a moving object in correlated image sequences. A correlation-based video tracking algorithm seeks to align the incoming target image with the reference target block image, but has critical problems, so called a false-peak problem and a drift phenomenon (correlator walk-off. The false-peak problem is generally caused by highly correlated background pixels with similar intensity of a moving target and the drift phenomenon occurs when tracking errors accumulate from frame to frame because of the nature of the correlation process. At first, the false-peaks problem for the ordinary correlation-based video tracking is investigated using a simple mathematical analysis. And, we will suggest a robust selective-attention correlation measure with a gradient preprocessor combined by a drift removal compensator to overcome the walk-off problem. The drift compensator adaptively controls the template block size according to the target size of interest. The robustness of the proposed method for practical application is demonstrated by simulating two real-image sequences.

• 대한기계학회논문집A
• /
• 제40권2호
• /
• pp.147-156
• /
• 2016

본 연구에서는 자전거의 경량화를 위해 탄소섬유 복합재료, 유리섬유 복합재료, 케블라섬유 복합재료를 자전거 프레임의 재료로 사용하여 강도 설계 및 최적화를 수행하고 재료 성능을 비교하였다. 이를 위해 유럽표준위원회가 제시하는 자전거 안전사항을 기준으로 복합재료가 가진 이방적 특성을 활용하여 적층각 최적화와 두께 최적화를 수행하였다. 또한, 최적화된 무게, 복합재료의 강도와 비용을 바탕으로 Digital logic 방법으로 재료별 자전거 프레임의 성능을 비교하였으며 이를 통해 섬유강화복합재료를 사용한 자전거 프레임의 구조적 안정성을 확보하며 동시에 경량화를 수행할 수 있었고, 자전거 프레임에 적합한 복합재료를 선별할 수 있었다.

• 해양환경안전학회지
• /
• 제30권1호
• /
• pp.108-117
• /
• 2024

본 연구에서는 너클 라인이 다수 존재하면서 안팎 형상이 비대칭으로 설계된 특이점을 갖는 쌍동선의 자항성능을 예측하기 위해 CFD 해석을 수행하였고, 해석 기법에 따른 차이를 파악하기 위해 MRF(Moving Reference Frame) 기법과 SDM(Sliding Mesh) 기법을 적용하였다. MRF 기법을 적용한 경우에는 time step당 프로펠러를 1˚ 회전시켰고, SDM 기법의 경우 10˚, 5˚, 1˚씩 회전시키며 각 기법별 예측된 자항성능을 비교하였다. 자항점 추정을 위한 몇 가지 프로펠러 회전수에서의 해석 결과 중 프로펠러의 토크는 기법에 따른 차이가 거의 없었지만 추력 및 선체가 받는 저항은 MRF 기법보다는 SDM 기법을 적용했을 때 더 낮게, SDM 기법의 time step당 프로펠러 회전각이 작을수록 높게 계산되었다. 선형 내삽을 통해 추정된 자항점의 프로펠러 회전수, 추력, 토크와 실선 확장법을 사용해 추정된 실선의 전달동력, 반류 계수, 추력 감소 계수 및 프로펠러 회전수도 동일한 경향을 보였으며, 대부분의 자항효율은 반대의 경향을 보였다. 프로펠러 후류의 경우 MRF 기법을 적용했을 때 정확도가 떨어졌고, SDM 기법의 time step당 프로펠러 회전각에 따라 표현되는 후류의 차이는 거의 없었다.

• 지구물리
• /
• 제9권3호
• /
• pp.151-158
• /
• 2006

Highly accurate surface velocity estimation using modern geodetic techniques plays very important role in the geological and geophysical interpretation. Researches with GPS are ongoing in many countries of the world. This study aims to estimate the amount of crustal deformation and the direction of deformation in the Korean Peninsula and in its neighbor. We used GAMIT that is a comprehensive GPS analysis package developed at MIT. Then, a Global Kalman filter called GLOBK is used to combine the results from GAMIT and to estimate the relative and absolute velocity vector for the crustal deformations. To estimate station velocity accuracy and reliably, it is extremely important to pay great attention to the reference frame. Firstly, using the Suwon (SUWN) of Eurasian plate as main frame, we estimate the relative amount of crustal deformation and a direction of Eurasian plate and North American plate, Secondly, using ITRF 2000 as main frame, we estimate the absolute crustal deformation of Eurasian plate and North American plate. The continent of Eurasian where has the Korean Peninsula deforms 33.36 mm per year to East-Southeast (ESE), and Japanese Tsukuba (TSKB) in North American plate deforms to South-Southwest (SSW). Finally, the Korean Peninsula is approaching the Japanese Island and the rate of horizontal crustal deformation between the Suwon and the Tsukuba is about 31.98 mm per year in the moving direction of N85.9oW (274.1o) for the past three years.

• 한국지반환경공학회 논문집
• /
• 제2권3호
• /
• pp.89-99
• /
• 2001

본 연구에서는 가장 널리 사용되고 있는 지반모델인 Modified Cam-Clay 모델을 이용하여 피에조콘 관입 및 소산시험의 수치해석을 수행하였다. Modified Cam-Clay 모델 및 관련 유한요소 식들을 피에조콘 관입의 대변형 현상을 고려하기 위하여 Updated Lagrangian frame에서 formulation 하였다. 유한요소 해석 결과 얻어진 콘 관입저항치, 간극수압 및 소산곡선을 양산지역 현장 시험결과와 비교 분석하였다. 수치해석 결과는 시험결과와 비교적 잘 부합하는 것으로 고찰되었으나 보다 현실에 근접한 simulation을 위하여 연속적인 깊은 관입의 적절한 수치해석적 modeling이 요구되는 것으로 고찰되었다.

• 한국가구학회지
• /
• 제23권1호
• /
• pp.10-25
• /
• 2012

This article aimed at understanding the characteristics of Swedish furniture design since 1980s in the reference to the major paradigm changes in the contemporary design field. For this, the authors examined the theoretical background of modern and post-modern design paradigms to identify today's design tendencies. And we used this frame in the analysis of the latest examples of Swedish furniture design. The main characteristics of Swedish furniture design since 1980s included 'furniture as art object', 'the succession of the Swedish Modern (neo-modernism)', and 'conscious design for sustainable development'. These could be viewed as the consequences of the choices that the Swedish furniture industry and designers made during the last decade, that was to take plurality and contradiction as the accompanying values of the traditional Swedish modern design.

• Journal of Mechanical Science and Technology
• /
• 제15권7호
• /
• pp.831-838
• /
• 2001

Torque ripple control of brushless DC motor has long been the main issue of the servo drive systems in which the speed fluctuation, vibration and acoustic noise need to be minimized. The vast majority of the methods for suppressing the torque ripple require the Fourier series analysis and either the iterative or least mean square minimization. In this paper, a novel approach based on the d-q-0 reference frame that achieves ripple-free torque control with maximum efficiency is presented. The proposed method optimizes the reference phase current waveforms including even the case of 3-phase unbalanced condition, and the motor winding currents are controlled to track the optimized current waveforms by the delta modulation technique. As a results, the proposed approach provides a simple and yet effectine means for obtaining the optimal motor excitation currents. The validity and applicability of the proposed control scheme are verified through simulations and experimental investigations.

• Journal of the Korean Wood Science and Technology
• /
• 제44권2호
• /
• pp.264-273
• /
• 2016

The insulation of a building envelope influences the hygrothermal performance as well as the thermal performance of the building. While most of Korean wood frame houses have an interior insulation system, the exterior insulation system with high thermal performance has recently been applied. While it can be effective in energy savings for better insulation performance, without consideration of the moisture, condensation and mould growth can occur. Therefore, in this study, hygrothermal behaviour, water content, and mould growth were analyzed using hygrothermal simulation of an exterior wall of a wood frame house with which the interior insulation and exterior insulation systems were applied. The wall layer included Wall A (Interior insulation) and Wall B (Exterior insulation). The U-values were identified as 0.173 and $0.157W/m^2K$, respectively. The total water content and OSB absolute water content of Wall A were confirmed to be higher than those of Wall B, but the absolute water content did not exceed the reference value of 20%. The moisture content of the two walls was determined to be stable in the selected areas. However, mould growth risk analysis confirmed that both Wall A and Wall B were at risk of mould growth. It was confirmed that as the indoor setting temperature decreased, the mould index and growth rate in the same area increased. Therefore, the mould growth risk was affected more by indoor and outdoor climate conditions than by the position of the insulation. Consequently, the thermal performance of Wall B was superior to that of Wall A but the hygrothermal performances were confirmed to be similar.