• 대한토목학회논문집
• /
• 제42권1호
• /
• pp.83-93
• /
• 2022

최근 도시철도 노인 무임승차제도에 대한 논란이 거세지고 있다. 이에 본 연구는 부산김해경전철의 운영적자를 재정지원 하고 있는 부산시와 김해시 소속 공무원들을 대상으로 노인무임승차제도에 관한 10년간의 의식변화를 비교·분석하였다. 부산김해경전철은 국내에서 유일하게 노인무임승차제도를 실시하지 않는 도시철도이다. 2011년 9월과 2021년 4월, 노인 무임승차제도에 대한 이해와 지식이 상대적으로 높은 지자체 공무원들의 의식 조사를 실시하여 그 변화 과정을 추적하고 행정적, 정책적 고찰을 수행하였다는 점에서 차별성을 지닌다. 분석 결과를 요약하면, 부산김해경전철 개통 전후 의식변화가 확실히 나타났으며, 개통 이후 시간이 지남에 따라 찬성과 반대가 거의 동일한 비율로 수렴하는 것으로 나타났다. 특히 개통 전에는 교통관련부서 근무경험이 없는 응답자일수록 찬성 비율이 높았으나 시간이 지날수록 근무경험이 없는 그룹도 찬성 비율이 차츰 낮아졌다. 또한 시간이 지날수록 노인 무임승차제도의 지속보다는 정책대안 모색의 필요성이 강조되었다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.47-50
• /
• 2011

Test Results of noise, ride comfort and vibration tests are investigated for three kinds of light rail transit vehicles which have passed the performance test and the test criteria has been satisfied. Noise level of light rail transit vehicles was 64~69dB(A) at stop and 74~75dB(A) when operated at full speed. The ride comfort index according to UIC 513R was 2.02 to 2.45. Vibration level of rubber tired light rail transit vehicle was from 'normal' to 'good' and that of iron wheel light rail transit vehicle was 'good' to 'excellent'. These data are the results for three kinds of light rail transit vehicles and more data can be accumulated after further performance test. These data can be used for a reference for the design of light rail transit vehicles.

• 제어로봇시스템학회논문지
• /
• 제16권11호
• /
• pp.1096-1103
• /
• 2010

This paper proposes CDC (Continuous Damping Control) algorithm and verifies in multi-body dynamic vehicle. In order to distinguish a road profile on driving, waviness calculated by the filtered vertical-accelerations of sprung and unsprung masses is introduced. Sky-hook control is used at a low waviness road and constant damping level control is used at a high waviness road, where the hard damping level is determined by waviness, roll rate, acceleration, and deceleration. The damping levels of ride, anti-roll, anti-squat, and anti-dive modules are calculated by tuning parameters which is dependent upon vehicle velocity. Therefore this high tunable algorithm is useful to improve the ride and handling performance under various driving conditions. In the simulations, tire and dampers are modelled by SWIFT (Short Wavelength Intermediate Frequency Tire) model and 1st order delay model, and results are compared with conventional damper's.

• 대한기계학회논문집A
• /
• 제28권11호
• /
• pp.1672-1684
• /
• 2004

In this paper, an active vibration control with the use of an air-cell seat for passenger cars is investigated. The roles of the air-cell inserted between the polyurethane foam of the seat and seat cover are first to extend the seat's capability to adopt various shapes of human body and to improve the ride-comfort against road disturbances. The air-cell seat is modeled as a 1-d.o.f. spring-damper system. Because an exact modeling of the air-cell itself is alomost impossible, its dynamic characteristics are analyzed through experiments. A road-adaptive gain-scheduled sky-hook control for the air-cell seat system is proposed. The skyhook gains are scheduled in such a way that the acceleration level transmitted to human body on various road conditions is minimized. Simulations and experimental results are provided.

• Journal of Mechanical Science and Technology
• /
• 제17권7호
• /
• pp.958-965
• /
• 2003

Structural integrity of either a passenger car or a light truck is one of the basic requirements for a full vehicle engineering and development program. The results of the vehicle product performance are measured in terms of ride and handling, durability, noise/vibration/harshness (NVH), crashworthiness and occupant safety. The level of performance of a vehicle directly affects the marketability, profitability and, most importantly, the future of the automobile manufacturer In this study, we used the virtual proving ground (VPG) approach for obtaining the dynamic characteristics. The VPG approach uses a nonlinear dynamic finite element code (LS-DYNA3D) which expands the application boundary outside the classic linear static assumptions. The VPG approach also uses realistic boundary conditions of tire/road surface interactions. To verify the predicted dynamic results, a single lane change test has been performed. The prediction results were compared with the experimental results, and the feasibility of the integrated CAE analysis methodology was verified.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 1999년도 춘계학술대회 논문집
• /
• pp.159-166
• /
• 1999

In this paper, running performance analyses of an articulated light rail vehicle are carried out using VAMPIRE software package. The stability analysis to determine the critical speed and the safety analysis such as derailment coefficients, lateral forces of wheels and reduction of wheel load are carried for the track conditions of straight, transition and curving range to the operating velocity of 40km/h. Also, ride quality is analyzed. As the results of analysis, the safety of light rail vehicle satisfied with the limit values and the ride quality for tare and full load condition was shown to the "not uncomfortable" level in ISO 2631-1 (1997) criteria.

• Smart Structures and Systems
• /
• 제21권5호
• /
• pp.705-713
• /
• 2018

High-speed rail (HSR) has been in operation and development in many countries worldwide. The explosive growth of HSR has posed great challenges for operation safety and ride comfort. Among various technological demands on high-speed trains, vibration is an inevitable problem caused by rail/wheel imperfections, vehicle dynamics, and aerodynamic instability. Ride comfort is a key factor in evaluating the operational performance of high-speed trains. In this study, online monitoring data have been acquired from an in-service high-speed train for condition assessment. The measured dynamic response signals at the floor level of a train cabin are processed by the Sperling operator, in which the ride comfort index sequence is used to identify the train's operation condition. In addition, a novel technique that incorporates salient features of Bayesian inference and time series analysis is proposed for outlier detection and change detection. The Bayesian forecasting approach enables the prediction of conditional probabilities. By integrating the Bayesian forecasting approach with time series analysis, one-step forecasting probability density functions (PDFs) can be obtained before proceeding to the next observation. The change detection is conducted by comparing the current model and the alternative model (whose mean value is shifted by a prescribed offset) to determine which one can well fit the actual observation. When the comparison results indicate that the alternative model performs better, then a potential change is detected. If the current observation is a potential outlier or change, Bayes factor and cumulative Bayes factor are derived for further identification. A significant change, if identified, implies that there is a great alteration in the train operation performance due to defects. In this study, two illustrative cases are provided to demonstrate the performance of the proposed method for condition assessment of high-speed trains.

• 전기전자학회논문지
• /
• 제25권2호
• /
• pp.399-407
• /
• 2021

본 논문에서는 계통망 사업자의 High Voltage Ride-Through(HVRT) 기능 요구조건을 만족하며, 정상상태에서의 손실을 최소화할 수 있는 Type 4 풍력발전기의 직류단 전압 설계 방법을 제안한다. 대용량 해상 풍력 발전에 사용되는 Type 4 풍력발전기는 전력 계통과 연계된 컨버터와 풍력 발전기와 연계된 컨버터가 직류단을 공유하는 Back-to-Back 컨버터 형태이다. Type 4 풍력발전기에서 HVRT 조건인 계통 고전압 사고가 발생한 경우 사고 전압 크기에 비해 직류단 전압이 부족하다면 과변조로 인해 계통측 컨버터의 전류 제어기가 원활하게 동작되지 못한다. 따라서 HVRT 기능을 만족하기 위해서는 고전압 사고의 전압 크기를 기준으로 직류단 전압을 설계해야 한다. 그러나 직류단 전압의 크기의 증가는 정상상태에서의 컨버터 손실 증가를 야기하므로, 직류단 전압을 크게 설계하였을 때 증가될 손실에 대한 고려가 포함되어야 한다. 본 논문에서는 사고 전압의 크기와 발생 손실이 고려된 직류단 전압을 설계하는 방법에 대해 설명하고, 제안하는 설계 방법의 타당성을 2MVA급 Type 4 풍력발전기의 PSCAD 모델 기반 HVRT 기능 시뮬레이션을 통해 확인하였다.

• Journal of Power Electronics
• /
• 제16권4호
• /
• pp.1551-1564
• /
• 2016

The high penetration level of inverter-based distributed generation (DG) power plants is challenging the low-voltage ride-through requirements, especially under unbalanced voltage sags. Recently, a flexible injection of both positive- (PS) and negative-sequence (NS) reactive currents has been suggested for the next generation of grid codes. This can enhance the ancillary services for voltage support at the point of common coupling (PCC). In light of this, considering distant grid faults that occur in a mainly inductive grid, this paper proposes a complete voltage support control scheme for the interface inverters of medium or high-rated DG power plants. The first contribution is the development of a reactive current reference generator combining PS and NS, with a feature to increase the PS voltage and simultaneously decrease the NS voltage, to mitigate voltage imbalance. The second contribution is the design of a voltage support control loop with two flexible PCC voltage set points, which can ensure continuous operation within the limits required in grid codes. In addition, a current saturation strategy is also considered for deep voltage sags to avoid overcurrent protection. Finally, simulation and experimental results are presented to validate the effectiveness of the proposed control scheme.

• Journal of Power Electronics
• /
• 제13권5호
• /
• pp.909-918
• /
• 2013

This paper proposes a coordinated control of the reactive power between the STATCOMs (static synchronous compensators) and the grid-side converters (GSC) of wind farms equipped with PMSGs (permanent-magnet synchronous generators), by which the voltage fluctuations at the PCC (point of common coupling) are mitigated in the steady state. In addition, the level of voltage sags is reduced during grid faults. To do this, the GSC and the STATCOM supply reactive power to the grid coordinately, where the GSCs are fully utilized to provide the reactive power for the grid prior to the STATCOM operation. For this, the GSC capability of delivering active and reactive power under variable wind speed conditions is analyzed in detail. In addition, the PCC voltage regulation of the power systems integrated with large wind farms are analyzed for short-term and long-term operations. With this coordinated control scheme, the low power capacity of STATCOMs can be used to achieve the low-voltage ride-through (LVRT) capability of the wind farms during grid faults. The effectiveness of the proposed strategy has been verified by PSCAD/EMTDC simulation results.