• 한국입자에어로졸학회지
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• 제6권1호
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• pp.9-20
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• 2010

This study examined the concentration level of the major air pollutants in public transportation. The study was conducted between February 2009 and March 2008 at Suwon-Yeosu line in Korea. $PM_{10}$ concentration level was $100{\mu}g/m^3$ on average. The $PM_{2.5}$ to PM10 ratio in transport is 0.37, which was lower than the results published by other researches. The result also demonstrated that outdoor $PM_{10}$ concentration was about 56~60% level compared to that of the cabin. $CO_2$ concentration level in the cabin was 1,359ppm, which does not exceed 2,000ppm, which is the guideline concentration level according to the Ministry of Environment. $CO_2$ concentration level in the cabin was $CO_2=23.4{\times}N+460.2$, and about 23.4ppm in $CO_2$ concentration level increased every time one passenger was added on. The experiment conducted on the train demonstrated that the average $PM_{10}$ concentration level was $100{\mu}g/m^3$ in case of the reference cabin while average $PM_{10}$ concentration level of the modified vehicle was $68{\mu}g/m^3$. Likewise, effect of the particle reduction device for the reduction of $PM_{10}$ concentration level was approximately 21%. Meanwhile there was almost no difference in the concentration level between reference and modified cabin in case of $PM_{2.5}$. Using zeolite as an adsorbent was made to reduce the $CO_2$ concentration level in the cabin. Number of passengers was factored in, to calculate the effect of the adsorption device, which demonstrated that about 36% of $CO_2$ concentration level was reduced in the modified cabin effect of the $CO_2$ reduction device. This research analyzed the current status concerning the quality of air in the public transportation and technologies were developed that reduces major air pollutants.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.556-562
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• 2011

Railroad started from invention of stream locomotive at the beginning of the industrial revolution. Development of diesel and electric locomotives in railroad induced science and technology since the industrial revolution. Korean high-speed train so-called high-speed train project, is localized 86.7%(compared to price), 92%(compared to number of parts). This technology has been contributed to KTX since 2004. High-speed railway was developed to integrated system, which is contained high technology such as civil, mechanical and electrical technology. This effects to advanced technology across the board science, technology, industry. High-speed railway is fast, safe, comfortable, eco-friendly as next generation's representative transportation. Furthermore it is inaugurate the era of the new railroad. Korea is opened the high-speed railway following Japan, France, Germany, Spain. Korea became the fifth nation of the high-speed railway. It joins the rank of developed countries operating at the speed of 300km/h. Especially, KTX is emerging as advanced transportation with reducing logistics costs significantly due to time advantage and transportation revolution. The purpose of this study is to present the strategy through internal and external railway market's analysis for Korea railway system's globalization expansion(overseas expansion).

• 한국정밀공학회지
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• 제33권7호
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• pp.529-534
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• 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.

• 한국정밀공학회지
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• 제33권7호
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• pp.535-540
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• 2016

The braking device in railway vehicles decelerates or stops the train by dissipating the thermal energy converted from kinetic energy into the air. Therefore, the brake system is crucial for safety. In this paper, we performed a study on an electromechanical brake actuator using an electrical motor as an alternative to pneumatic air cylinders to reduce the idle running time in braking, which subsequently increases braking distance, and to ensure reliable response characteristics. Especially, to analyze the response characteristics of the electromechanical brake actuator, we measure the delay time, response time and power consumption compared to the air cylinder. It is confirmed that the electromechanical brake actuator can reduce reaction time by 0.1 seconds (Braking Action) and 0.46 seconds (Brake Release) compared to the air cylinder.

• 한국생산제조학회지
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• 제26권4호
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• pp.378-386
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• 2017

Friction stir welding was performed using six welding conditions to evaluate the mechanical properties and microstructure of the welded zone based on its temperature change in the extruded plate of magnesium alloy AZ61. The welded zone temperature was measured using a thermocouple, and the maximum temperature ranges for the advancing and retreating sides were approximately $210-315^{\circ}C$ and $254-339^{\circ}C$, respectively. Depending on the welding conditions, a temperature difference of more than $100^{\circ}C$ was observed. In addition, the maximum yield strength and maximum tensile strength of the welded component was 84.4% and 96.9%, respectively, of those of the base material. For the temperatures exceeding $300^{\circ}C$, oxidation defects occurred in the weld zone, which decreased the mechanical strength of the weld zone. The microstructure and texture confirmed that fracture occurred because of the grain size deviation of the welding tool and the severe anisotropy of the texture of the welded joints.

• 한국철도학회논문집
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• 제16권1호
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• pp.1-6
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• 2013

본 연구에서는 복합소재 전동차용 대차프레임에 적용되는 4매 주자직 유리섬유/에폭시 복합소재에 대한 고유진동 특성과 주파수에 따른 감쇠특성을 평가하였다. 이를 위해 오토클레이브 성형을 통해 길이와 두께가 다른 유리섬유/에폭시 빔 시편을 제작하였다. 시험결과 감쇠비의 최대값은 최소 고유진동수에서 발생하였다. 또한, 주파수가 증가함에 따라감쇠비는 지수 함수적으로 임계치까지 감소하였다. 이후에는 주파수에 따라 증가하는 경향을 보였다.

• 전기학회논문지
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• 제64권7호
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• pp.1019-1025
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• 2015

The performance requirements on the safety-based functionality of railway signal systems have been reinforced and the effort for enhancement of the existing system or development of the new system is being accordingly made. In particular, various technical researches on replacement or improvement of the existing ATS(Automatic Train Stop) signaling system are now in progress for better operational efficiency. In this study, the complementary points for improvement or replacement of the currently used system(i.e., ATS) will be derived in terms of operating efficiency in an integrated operating environment with the newly introduced system(e.g., ATC: Automatic Train Control). This study can contribute to derive the need for improvement of the signaling system by checking the interface problems and comparing between different systems through the analysis of real operation cases in the field. Eventually, this analysis can be applied to prevent and estimate the collision accidents can be caused by the failure of the signaling system in advance. In addition, the results can be used to provide a future direction to secure the reliability in the parallel operation by integration based on different railway signaling systems.

• International Journal of Railway
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• 제4권4호
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• pp.93-96
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• 2011

The basic element of the EMS suspension is the electromagnet system, which suspends the vehicle without contact by attracting forces to the rails at the guideway. The suspension of a vehicle by attractive magnetic forces is inherently unstable and consequently it is continuously adjusted by the strength of the suspending electromagnet from rail irregularity and bending of the guideway. In order to improve reliable tracking, it needs to get feedback signals without measurement delay time. In this paper the concept of feedback control system with Kalman Filter in EMS is proposed. The input signals in the feedback control system are an air-gap and an acceleration signal. The air-gap signal with noise from the gap sensor is transformed to the filtered air-gap signal y without measurement delay time by using Kalman Filter. The filtered air-gap signal is transformed to a relative velocity and a relative acceleration signal. Then it multiplies these values by gain matrix in order to get the actuator's reference voltage value. The simulation results show that the dynamic responses of the suspension system can be improved by reducing the influence of measurement delay time of air-gap signals.

• 한국철도학회논문집
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• 제11권5호
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• pp.482-488
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• 2008

국내 최초로 민간자본이 투자된 대형 지하철인 서울 9호선은 김포공항과 강남을 연결하는 1차 구간이 2009년 개통을 앞두고 있다. 지자체와 민간이 시설을 건설하고 전문 공공교통 서비스회사가 운영을 맡는 9호선은 보유한 자원을 최고로 활용하여 최대의 효율성을 이끌어낼 필요가 있으며, 관련 기관과의 적극적인 협력을 통한 핵심역량발휘와 경쟁력 제고가 필요하다. 본고에서는 9호선 운영분야에 초점을 맞추어 완급결합을 중심으로 한 9호선 운전체계와, 타 교통수단과의 연계, 공항철도와의 효과적인 직결운행 측면에서 9호선의 운영개선 방안을 제시한다.

• International Journal of Internet, Broadcasting and Communication
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• 제14권2호
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• pp.79-88
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• 2022

Recently, securing stable supply of fresh food is deemed as one of the important tasks. Accordingly, now the presence of cold chain along with the needs of a comfortable and healthy life is growing as the online market expands and the contactless industry grows, however, cold chain is being studied only in the aspect of ground and sea transportation. And, due to global warming and strengthening global environmental regulations, we believe that it is necessary to convert the existing road-centered logistics system into a railway-centered logistics system, a low-carbon transportation means. Therefore, in this paper we calculated the maximum energy required by the reefer container as a basic research necessary for constructing the low temperature distribution and cold chain based on the reefer container railway, and conducted a study on methods of supplying the reefer container power utilizing 1. tramline, 2. battery, 3. generator. The results of this paper can be utilized as a foundational study for building a cold chain based on a reefer container dedicated to freight trains in the future.