The main hydraulic pump is a device that generates the hydraulic pressure needed for the K2 tank. It is a pressure-compensated swash plate piston pump that generates the hydraulic power necessary to drive the hydraulic device. Hydraulic pump design changes were made due to frequent failures of the hydraulic pump. As a result of checking the operation records of the hydraulic pump, about 71% of the total engine operation time was in a stationary state where hydraulic pressure was not needed. This has the problem of constantly running when the engine is started, consuming unnecessary endurance time, and generating high noise. In this study, ISG(Idle Stop & Go) was applied to improve operation method. When applying ISG, the pressure can be reduced to about 85% or less in an environment where the operation of the main hydraulic pump is not necessary. So, the lifespan of the main hydraulic pump increases as a result of ISG application, thereby reducing the waste of national funds due to maintenance costs. Also, it is expected to contribute to improving combat power by reducing crew fatigue due to noise reduction.

In this article, improvement of heat screen failure for battle tank is proposed. The heat screen applied to protect a cam sensor from engine heat was cracked by vibrations generated in the engine. To solve this problem, the configuration of the heat screen was changed to a structure that can avoid engine vibration levels. The improved heat screen has first mode frequency at 4,000 RPM band outside the main operating range of the engine, and heat dissipation is at the same level as conventional heat screen. As a result, the improved heat screen secured reliability by improving vibration effects by approximately 163% while maintaining heat dissipation performance.

K1A1 tank commander’s primary thermal sight is a device that enables tank commanders to detect, identify, aim and track the target by observing targets in all directions during day, night and in situations of smokescreen and fog through 360° rotation independent from the gunner’s primary thermal sight and stabilizing the line of sight even under the vibrations occurring when the tank is standstill and moving. The main function of this device is to detect and process visible and thermal images and deliver the final images to the tank commander. One of the core parts to that end is the observation window (daytime/ thermal image window). This core part is mounted at the entrance of the optical path for observing the target and plays the role of making visible light during the daytime and infrared light during the night pass through the target and transmitting the resultant images to the internal optical system of the tank commander’s primary thermal sight. Such core parts have been selected as depot maintenance items so that they are replaced by new parts instead of being recycled when they are subjected to maintenance in most cases. That is, the military budget is wasted because such parts are replaced by new parts despite that they can be recycled for maintenance. Therefore, this study proposed a mounting tool for polishing and coating observation windows (daytime and thermal image window) using planar polishing equipment and DLC (Diamond-Like Carbon) coating equipment. In addition, this study presented an amendment (proposal) of the Depot Maintenance Work Request (DMWR) already published to verify the performance of recycled products including the establishment of inspection standards for recycling processes.

K-1계열 전차의 전차장 열상조준경은 주야간 및 연막, 안개 등의 상황에서 포수조준경과 독립적으로 360°회전을 통한 전 방향의 표적 관측과 전차가 정지 및 기동 간 발생하는 진동에서도 조준선을 안정화하여 전차장이 표적의 감지, 식별, 조준 및 추적 할 수 있는 장치이다. 이 장치 의 주요기능 중 하나인 가시상 및 열상을 감지하고 처리하여 최종 영상을 전차장에게 전달하는 것으로 이를 위한 핵심 부품은 주간 및 열상 창이다. 이 핵심 부품은 목표물을 관측하는 광행 로 입구에 장착되어 있으며, 목표물에 대해서 주간에는 가시광, 야간에는 적외선을 통과하여 전 차장 열상조준경의 내부 광학계통으로 전달하는 기능을 수행한다. 이와 같은 핵심부품에 대한 정비는 창 정비 품목으로 선정되어 대부분 재생정비가 아닌 신품 교환 정비를 하고 있는 실정 이다. 즉, 재생정비가 가능한 품목임에도 불구하고 신품교환에 따라 군 예산이 낭비되고 있다. 따라서 본 연구는 평면연마장비와 DLC(diamond-like carbon) 코딩장비를 활용하여 주간 및 열상 창을 연마·코팅할 수 있도록 장착치구를 개발하였다. 또한 재생공정에 대한 검사기준 정립을 포함하여 재생품에 대한 성능검증을 위해 기 발간된 창 정비작업요구서(DMWR) 수정(안)을 제시 하였다.

In development of high speed Rigid conductor line(R-bar) over 250km/h, it is important to develop the method to anticipate the mechanical stability of the R-bar and of the transition structure which connects the flexible Overhead Contact Line. To do this, firstly, the FE(Finite Element) model for a transition structure was established and the initial deformed configurations due to gravitational force is obtained by a static analysis and the pantograph was modeled by a simplified mass-spring-damper system and the contact behavior between conductor and pantograph was defined by the penality method. Secondly, FE analysis results were reviewed with the test results of contact force between conductor and pantograph at the low speed of train. Finally, using the established analysis method, the evolution of contact forces was performed for a newly designed high speed R-bar and for its transition structure.

Mechanical fatigue tests which consist of an alternate load and compression cycle show that droppers for 400km/h operation have cyclic mechanical strength of 300N with compression amplitude 0.05m. Numerical simulations for forces on the dropper during the passage of a train tell that dynamic forces can be varied up to 15% due to installation tolerance. Taking into account of the 15% variation, we end up with the maximum allowable peak load of 260N for the dropper. Peak value of measured forces on the dropper at the speed of 400km/h is 152N, which is less than the maximum allowable peak load of 260N. Conclusively, the possibility of fatigue fracture for the dropper is quite low.

Formulation of the finite element method(FEM) for dynamic interaction between a pantograph and contact wire, including non-linear formulation associated with contact wire stagger in the railway overhead contact line is presented. Penalty method is chosen for modelling contact between a pantograph and contact wire. The formulation is validated by comparing the simulated contact forces with measurements taken from 300 km/h KTX operation.

Recently, the quiet fan development is one of important issues for comfort of railroad car. The purpose of this study is to find the vibration and noise source of the line flow fan for reduction the noise level. For a vibration and noise source identification, experiments with microphone and acceleration were carefully carried out. The noise of line flow fan is caused by various factors, such as turbulent flow noise, blade passing frequence and unbalance. In order to reduce the fan noise, the blade shape, distance and angle of housing guide should be modified.

For the purpose of the enhancement of the air conditioner performance and fuel effciency, several cases of centrifugal impeller for passenger car air conditioner have been numerically analyzed by changing central angle of blades and length of outlet for shape optimization of the impeller. Commercial CFD program Fluent 6.3.26 has been used to compute velocity, temperature, pressure and turbulence intensity that can lead numerous results. The central angles of two blades and three cases of outlet length led 4～12% and 3.5～6.4% differences of velocity and flow rate, respectively. The velocity distribution near the blade surface was axisymmetric and had a maximum value of 22.19 m/s and velocity of the vertical direction of the impeller showed linear increase with horizontal direction. At case 3 of oultet length, there existed a a minimum pressure value of -133320 Pa.

In this paper, we presents overview of performance qualification and testing method for new OCL (overhead contact line) up to 400 km/h. The track-side and on-board monitoring system are proposed to measure current collection performance. The proposed systems will be capable of measuring abnormal behavior quality of current collection between pantograph and contact wire.

The detail design for overhead line can be divided into a MD(Mounting Diagram) design and pegging plan process. A MD design for a high-speed overhead line was performed by the design software. The MD design of Honam High-Speed catenary system was also performed the software. However, the MD design software for 400km/h overhead line is needed, because the tension of wires and conditions are different from 350km/h system. Therefore, in this study, a MD design software for 400km/h overhead line system is developed.