• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 춘계학술대회 논문집
• /
• pp.185-189
• /
• 2003

According to opening Seoul-Busan high speed rail line in 2004, we are studying to offer speedily for the parcel service of high speed rail-combined transport as it does, tender the quality freight services within a one and the same high speed train formation. Therefore, we reviewed for various types of HSR-combined transport and suggested to application methods in Korean high speed rail line. Through these kinds of approaches, we are able to expect the fulfillment of customer needs for high speed rail market segments, the profit maximization of future railway operating companies, and enhancement for cost-effective rail network operation of the mixed traffic on infrastructure cost-reduction in national logistics.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 추계학술대회 논문집
• /
• pp.724-729
• /
• 2005

Winter weather condition can cause icing and ice coats on 25 kV overhead contact wire. This generates shocks at the mechanical interface of the collecting strips of the pantograph and the contact wire and extra electrical resistance, which may affect quality of current collection at the contact wire / collecting strips of pantograph interface. De-icing operations should he performed just before train operation to avoid the formation of another ice layer. Thus, the work in this paper is investigation and analysis of de-icing system which could be applied to the electric car line of railways.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.305-307
• /
• 2005

In the cold and temperate regions of Korea the icing and ice coats on 25[kV] electric car line during winter is a very serious problem. This generates shocks at the mechanical interface of the collecting strips of the pantograph and the contact wire and extra electrical resistance, which may affect quality of current collection at the contact wire / collecting strips of pantograph interface. De-icing operations should be performed just before train operation to avoid the formation of another ice layer. This paper presents temperature analysis of the de-icing system which could be applied to the electric car line of railways.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 추계학술대회 논문집
• /
• pp.564-569
• /
• 2013

An accurate railway environmental noise prediction model is required to make the proper solution of the railway noise problems. In this paper, an engineering model for predicting the noise of conventional passenger cars is presented considering the acoustic source strength in octave-band frequencies and the propagation over grounds with varying surface properties. Since the formation of a train can be variable, the source strength of each locomotive and passenger car was estimated by measuring the pass-by noise and analysing the wheel-rail rolling noise. Some validation cases show on the average small differences between the predictions of the present model and the measurement results.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.981-984
• /
• 2011

에틸렌 연료의 이중모드 스크램제트 연소기에서 연소와 충격파 열 발생의 과도 과정을 고해상도 기법을 이용하여 수치적으로 연구하였다. 연료 분사 이후 질량 공급에 의한 아음속 유동 감속을 위하여 연소기 확장부에 조절용 공기를 공급한다. 공기와 연료가 충분히 혼합된 수 ms 이후 점화가 이루어지며, 압력 상승은 격리부에 흡입구 노즐까지 전진하는 충격파 열을 형성한다. 이후 후방 공기공급을 중단하면 배출 과정이 진행되면서 후방 공기 공급 이전 상태로 서서히 복원된다. 본 연구의 결과는 이중모드 스크램제트 연소기에서 작동 영역과 특징의 이해를 돕는 상세 과정을 보여주었다.

• Structural Monitoring and Maintenance
• /
• 제1권1호
• /
• pp.131-157
• /
• 2014

Special track systems used to divert a train to other directions or other tracks are generally called 'railway turnout'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction complexities may dominate the choice of track forms or certain components. With the difficulty to seek for high-quality timbers with dimensional stability, a methodology to replace aged timber bearers in harsh dynamic environments is to adopt an alternative material that could mimic responses and characteristics of timber in both static and dynamic loading conditions. A critical review has suggested an application of an alternative material called fibre-reinforced foamed urethane (FFU). The full-scale capacity design makes use of its comparable engineering characteristics to timber, high-impact attenuation, high damping property, and a longer service life. A field trial to investigate in-situ behaviours of a turnout grillage system using an alternative material, 'fibre-reinforced foamed urethane (FFU)' bearers, has been carried out at a complex turnout junction under heavy mixed traffics at Hornsby, New South Wales, Australia. The turnout junction was renewed using the FFU bearers altogether with new special track components. Influences of the FFU bearers on track geometry (recorded by track inspection vehicle 'AK Car'), track settlement (based on survey data), track dynamics, and acoustic characteristics have been measured. Operational train pass-by measurements have been analysed to evaluate the effectiveness of the replacement methodology. Comparative studies show that the use of FFU bearers generates higher rail and sleeper accelerations but the damping capacity of the FFU help suppress vibration transferring onto other track components. The survey data analysis suggests a small vertical settlement and negligible lateral movement of the turnout system. The static and dynamic behaviours of FFU bearers appear to equate that of natural timber but its service life is superior.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 춘계학술대회 논문집
• /
• pp.2173-2178
• /
• 2008

Railroad is the major factor of vibration source in railway vehicles, and it must carefully maintained the original condition to secure the safety and good ride comfort of passenger. Measuring the condition of rail irregularities such as surface, alignment, gauge, twist and cant etc is required to maintain the good performance of railroad. Currently, the various rail irregularity measurement systems(EM120, ROGER1000K and the Total Rail Irregularity Measurement system of Korea High Speed Train) are operated in Korea to estimate the rail irregularity. It is hard to verify the correlation of one rail irregularity data of a measurement system with the other, because they have been adopted different rail irregularity estimation methods. The best method securing the reliability of the irregularity data is the direct confirmation on the ground where the measurement system had detected as a fault section, but it is impossible to apply all sections simultaneously due to limitation of time, labor, cost and equipments. There is a method to secure the reliability of the data by using acceleration values. Rail irregularities, the major factor of vibration in railway vehicle, are transmitted to the vehicle acceleration through masses, springs, dampers and joints as the system dynamic formation. In this study, Transition Function has been adopted by using the rail irregularity and the acceleration value regarding as input & output parameters respectively. It has been verified by comparing the analyzed results with real measured irregularity data from the Total Rail Irregularity Measurement system of Korea High Speed Train. Also various methods has been accomplished to verify the correlation between rail irregularities and acceleration values.

• 한국버섯학회지
• /
• 제7권1호
• /
• pp.1-8
• /
• 2009

국립원예특작과학원 버섯과에 보존하고 있는 볏짚버섯속(Agrocybe ) 30균주에 대하여 버섯발생 실험을 실시하고, 자실체의 형태적 특성을 조사하였다. 볏짚버섯속 균주중 톱밥배지를 사용한 병재배에서 자실체가 발생된 것은 19균주 이었다. 이중 ASI 19007 등 13균주(I; A. chaxingu )와, ASI 19003 등 5균주(II; A. cylindracea ), ASI 19008(III; Agrocybe sp.)로 그룹 지어졌는데, ASI 19008은 균배양기간, 버섯발생기간 등 재배적 특성과 자실체의 형태적 특징이 다른 2그룹과 차이가 많았다. 또한 재배 계절에 따라 재배적 특성이 다르게 나타났는데 봄, 가을, 겨울에는 ASI 19003 균주가, 여름에는 ASI 19007 균주가 수량이 많고 품질도 좋았다. 따라서 본 연구결과는 계절에 알맞은 품종의 선택을 통하여 볏짚버섯속균의 연중 안정생산이 가능하여 농가소득 증대에 기여할 것으로 본다.

• 한국전자파학회논문지
• /
• 제30권4호
• /
• pp.328-331
• /
• 2019

LFM(Linear Frequency Modulated) 펄스 열의 믹서 출력 신호를 이용하면 높은 샘플링 주파수의 ADC 없이 높은 거리해상도를 얻을 수 있으므로 합성개구레이다(synthetic aperture radar: SAR)에 사용되어 높은 해상도의 영상을 얻을 수 있다. 하지만 펄스 폭이 길거나 비행체와 표적 간의 상대속도가 빠를 때는 stop-and-go 근사화에 따른 오차가 발생한다. 따라서 본 논문에서는 근사화 없이 표적의 위치마다 다른 필터를 적용하는 기법인 시간 영역 상관관계(time domain correlation: TDC)를 사용한 직하 방향 영상형성을 제안한다. 특히, 영상에서 고스트 영상(ghost image)이 나타나는 것을 막기 위해 회전하는 안테나 구조를 제안하고, 모의실험 결과에서 회전하지 않는 안테나 구조를 사용했을 때 획득한 영상과 비교, 분석한다.

• 한국정밀공학회지
• /
• 제33권7호
• /
• pp.529-534
• /
• 2016

During the past few years, several incidents of freight car wheel failure during operation have occurred due to fatigue crack and overheating from braking. Tensile residual stress on the wheel tread creates an environment conducive to the formation of thermal cracks that may threaten the safety of train operations. It is important to investigate the residual stress on wheels in order to prevent derailment. In the present paper, the residual stress on wheels is measured using the x-ray diffraction system and the residual stress is analyzed using FEM. The result shows that the residual stress on the wheel rim is lower than that on the wheel tread center and the stress on over-braked wheels changes from compression residual stress to tensile residual stress.