• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.629-634
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• 2011

초고속 비행체에 적용 가능한 소모성 터빈엔진 개발을 위한 사전연구를 수행하였다. 엔진 요구도 및 설계점 결정을 위한 가상 운용임무형상을 선정하고, 유사급 엔진과 참고문헌 등을 통해 확보된 데이터를 활용하여 설계점 해석을 수행하였는데, 해면고도, 마하수 1.2 조건에서 터빈입구온도 3,600R에 대한 설계점 계산결과, 비추력 2599.4 ft/s, 비연료소모율 1.483 lb/($lb^*h$)이 예측되었다. 설계점 계산결과를 기준으로 두 가지 임무형상에 대한 엔진 성능해석결과, 엔진 최대 순추력을 결정하는 설계변수는 천음속 및 낮은 초음속영역에서는 터빈입구온도, 높은 초음속 영역에서는 압축기 출구온도임을 확인하였다. 이밖에도 단순, 저가, 경량의 엔진형상으로 축류형 다단압축기와 직류형 연소기, 1단 축류터빈, 고정 수축팽창 노즐이 적용된 단순터보제트엔진을 제시하였다.

• 한국추진공학회지
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• 제17권1호
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• pp.97-102
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• 2013

초고속 비행체에 적용 가능한 소모성 터빈엔진 개발을 위한 사전연구를 수행하였다. 엔진 요구도 결정을 위한 가상 운용임무형상을 선정한 후, 유사급 엔진과 참고문헌 등을 통해 확보된 설계변수 값을 활용하여 설계점 해석을 수행하였는데, 해면고도, 마하수 1.2 조건에서 터빈입구온도 3,600 R에 대한 설계점 계산결과, 비추력 2,599.4 ft/s, 비연료소모율 1.483 lb/(lb*h)이 예측되었다. 두 가지 임무형상에 대한 엔진 성능해석결과로부터 엔진 최대 순추력을 결정하는 설계변수는 천음속 및 낮은 초음속영역에서는 터빈입구온도, 높은 초음속 영역에서는 압축기 출구온도임을 확인하였다. 이밖에도 단순, 저가, 경량의 터빈엔진형상으로 축류형 다단압축기와 직류형 연소기, 1단 축류터빈, 고정 수축팽창 노즐이 적용된 단순터보제트엔진을 제시하였다.

• Smart Structures and Systems
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• 제29권5호
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• pp.653-660
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• 2022

Gravel scattering that is generated during operation of high-speed railway vehicle is cause to damage of vehicle such as windows, axle protector and so on. Especially, those are frequently occurred in winter season when snow ice is generated easily. Above all, damage of vehicle windows has not only caused maintenance cost but also increased psychological anxiety of passengers. Various methods such as heating system using copper wire, heating jacket and heating air are applied to remove snow ice generated on the under-body of vehicle. However, the methods require much run-time and man power which can be low effectiveness of work. Therefore, this paper shows that large-area heating system was developed based on heating coat in order to fundamentally prevent snow ice damage on high-speed railway vehicle in the winter season. This system gives users high convenience because that can remotely control the heating system using IoT-based wireless communication. For evaluating the applicability to railroad sites, a field test on an actual high-speed railroad operation was conducted by applying these techniques to the brake cylinder of a high-speed railroad vehicle. From the results, it evaluated how input voltage and electric power per unit area of the heating specimen influences exothermic performance to draw the permit power condition for icing. In the future, if the system developed in the study is applied at the railroad site, it may be used as a technique for preventing all types of damages occurring due to snow ice in winter.

• 전기학회논문지
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• 제58권3호
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• pp.598-604
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• 2009

This paper proposes a vehicle detector with an anisotropic magnetoresistive (AMR) sensor and addresses experimental results to show the detector's performance. The detector consists of an AMR sensor and mechanical and electronic apparatuses. The AMR sensor, composed of four magnetoresistors, senses disturbance of the earth's magnetic field caused by a vehicle moving over the sensor and then produces an output indicative of the moving vehicle. This paper verifies performance of the detector on the basis of experimental results obtained from the field tests carried under the two traffic conditions on local highways in Korea. First, I show the vehicle counting performance on a low speed congested highway by comparing the vehicle counts measured by the detector with the exact counts. Second, both vehicle counts and average speeds calculated from the measured point-occupancy on another continuously free running highway are compared with the reference values obtained from a loop detector which has two independent loop coils, where I have used several performance indices including mean absolute percentage error (MAPE) to show the performance consistency between the two types of detectors.

• 자동차안전학회지
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• 제4권2호
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• pp.5-10
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• 2012

Whiplash is the most frequent injury among occupants in low speed rear-end car collision. The aim of this paper is to analyze thecorrelation between influence parameters of head restraints and whiplash injury criteria.In this paper, DFSS (Design for Six Sigma) method is used for optimum design of head restrains. Four control factors of head restraints have selected by function matrix method. The effects of the control factors have been experimentally evaluated by using a sled pulse from 16km/h relative velocity which is suggested by KNCAP (Korean New Car Assessment Program). In order to reduce the noise factors of dynamic tests, whiplash tests were repeated twice. By using DFSS, the correlation between control factors and injury criteria has been comprehended.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1451-1455
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• 2007

MAGLEV(Magnetic Levitation) with Middle-low speed be classified as a kind of LRT(Light Rail Transit) in KOREA. Also this vehicle has adopted LIM propulsion method. The MAGLEV has adopted LIM type in operational or developing model in the world. The power rail of LIM is very similar with the 3th rail of LRT in the functional property but the structure and shape of power rail is different with that. WE have to search the optimal power rail system for Korean MAGLEV vehicle. In this paper, we suggest the conceptual design and direction of design for power rail of Korean MAGLEV developing.

• 한국소음진동공학회논문집
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• 제16권12호
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• pp.1231-1237
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• 2006

The vibration of a running railway vehicle can be classified on lateral, longitudinal and vertical motions. The important factor on the stability and ride quality of a railway vehicle is the lateral motion. The contact between wheel and rail with conicity influences strongly on the lateral motion. In this study, an experiment for the vibration of a running railway vehicle was performed using a of the scale model of a railway vehicle. Also, the effects on the car-body, bogie and wheelset were examined for the weight and the stiffness of the second suspension system. The experimental results showed that the lateral vibration increases as the wheel conicity and stiffness of the second suspension system increase. And the lateral vibration of the bogie increases as the mass ratio between car-body and bogie increases. Also, the lateral vibration of the wheel becomes high at low speed, while the wheel of 1/20 conicity makes severe vibration at high speed running.

• 한국자동차공학회논문집
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• 제13권3호
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• pp.35-40
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• 2005

In the present study, the influence of operating conditions on fuel economy for hybrid electric vehicle was analyzed. In order to accomplish this, vehicle speed, engine speed, battery current and voltage, SOC (state of charge),motor speed and torque, generator speed and torque, engine coolant temperature etc. were measured in real time. The tests were carried out under different driving cycles which are urban and highway cycles, KOREA CITY cycle and on-road driving, and also under various operating conditions such as different initial SOC, with or without regenerative braking etc.. Generally, conventional gasoline engines show a poor fuel economy at stop and go driving, because braking energy is wasted and the engine is operated in low thermal efficiency regions. However, in case of hybrid vehicles, higher fuel economy can be obtained because of utilizing the maximum thermal efficiency regions of engine, idling stop of engine, and regenerative braking etc..

• Smart Structures and Systems
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• 제13권5호
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• pp.797-819
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• 2014

This paper presents a theoretical algorithm for constructing the mode shapes of a bridge from the dynamic responses of a test vehicle moving over the bridge. In comparison with those approaches that utilize a limited number of sensors deployed on the bridge, the present approach can offer much more spatial information, as well as higher resolution in mode shapes, since the test vehicle can receive the vibration characteristics of each point during its passage on the bridge. Basically only one or few sensors are required to be installed on the test vehicle. Factors that affect the accuracy of the present approach for constructing the bridge mode shapes are studied, including the vehicle speed, random traffic, and road surface roughness. Through numerical simulations, the present approach is verified to be feasible under the condition of constant and low vehicle speeds.

• 한국생산제조학회지
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• 제24권5호
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• pp.541-547
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• 2015

In this study, the performance of a low-floor midsize bus under development is predicted through simulations. To predict the vehicle's acceleration, maximum speed, and uphill driving performance, a forward simulator which calculates the vehicle power is developed. Also we verify the forward simulator by comparing simulations and test result for benchmarking vehicle. To predict the fuel consumption, we use a backward simulator for a specified road cycle. However, to predict the fuel consumption using the backward simulation the engine fuel-consumption map is needed. The engine fuel-consumption map extracting data from a similar sized diesel engine is used by re-scaling the maximum torque. As a result, we simulate the vehicle's forward performance with a new engine. Further, we simulated the backward performance to optimize the fuel efficiency and gearshift timing.