• Journal of Advanced Marine Engineering and Technology
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• 제9권2호
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• pp.143-152
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• 1985

In this paper, temperature distribution and thermal stress are investigated considering engine peak pressure and the time average temperature distribution in the piston under running conditions for the marine diesel engine. The induced stress are calculated by the Finite Element Method (FEM). The results obtained are summerized as follows. 1) The results calculated by the FEM present good agreement with other numerical solution in literatures. 2) It is comfirmed that the maximum compressive stresses are induced in the part of outside wall between the piston crown and the pin bush 3) In the axial direction, the hoop stresses are changed its sign at the portion of crown near the inner wall side. 4) Large gradient of temperature is shown in the piston crown near the side wall in the axial direction, in the part between the piston crown and the pin bush in radial direction. 5) In case of stress distribution of piston wall surface in the axial direction, the hoop stress is a little greater than axial stress, and the latter is greater than the radial stress.

• 전기학회논문지
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• 제57권9호
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• pp.1536-1545
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• 2008

In this paper, we research a new method for efficiency improvement of a single-phase Induction motor by minimization of the stator loss. To make this, we perform winding design which is based on balanced and quasi-balanced operation condition. It gives efficiency improvement greatly but poor starting torque simultaneously. To obtain the best efficiency improvement maintaining the maximum and starting torque, the optimal winding specification and rotor dimension is determined with variation of secondary resistance, running capacitor and turn ratio. Finally, this paper gives the comparison between the simulation results and experimental results.

• Journal of Communications and Networks
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• 제10권1호
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• pp.1-4
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• 2008

This paper reports the design of a multiwavelength fiber laser source that utilizes a linear cavity of hybrid Brillouin/Erbium fiber laser (BEFL). The output power, threshold power and free running cavity modes were investigated against the pump powers. The structure exhibited low threshold operation of 4 mW at 2.3 mW injected Brillouin pump power. The optimization of Brillouin pump wavelength, power and Erbium gain led to a maximum possible number of channels generated. Simultaneous and stable operation of 21 channels with 10.88 GHz channels spacing were obtained from this architecture at 1 mW injected Brillouin pump power and 90 m W Erbium doped fiber pump power in the 1555 nm region.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.94-100
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• 1999

The friction and wear behavior of MoS$_2$Coatings were investigated using a pin and disk type tester. The experiment was conducted using silicon nitride as pin material and MoS$_2$-on-bearing steel as disk material under different operating conditions that include linear sliding speeds in the range of 22~66mm/sec, normal loads varying from 9.8~29.4N, corresponding to maximum contact pressure of 1.78~2.830GPa and atmospheric conditions of high vacuum, medium vacuum, ambient air. The results showed that low friction coefficient of the coating has been identified when running in high vacuum and that friction coefficient and wear volume increased with increasing normal load. Also at high load conditions, the friction coefficient and wear volume increased with increasing sliding velocity.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.217-222
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• 2015

In this paper, a study was conducted for the optimization through shear web of shape the Edison program in wind power blade. We measured the displacement and stress distribution through two optimization methods to select the model with the smallest displacement and stress values. Before running the analysis, We try to find the inflection point through the shear web of the model and then analyze by introducing the geometric nonlinearity. The first optimization variables are introduced by the pitch angle and three web shapes. Third model such a honeycomb structure is good way to get an advantage for bending test. According to a method of previous optimization, third model is chosen and then the thickness of the web and blade as a variable is introduced, it is extracted as a result of displacement and the maximum stress per mass.

• Journal of Magnetics
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• 제16권4호
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• pp.417-422
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• 2011

This paper presents the characteristics of PM eddy current loss and harmonic iron loss for PM step-skewed Interior Permanent Magnet Synchronous Motor (IPMSM) with concentrated windings and multi-layered PM under the running condition of maximum torque per ampere (MTPA) and flux-weakening control. In particular, PM eddy current loss and harmonic iron loss in IPMSM have been numerically computed with three-dimensional Finite Element Analysis (3D FEA), whereby IPMSM with concentrated windings and multi-layered PM has been designed to identify the optimized skew angle contributing to the reduced PM eddy current loss and torque ripples, while maintaining the required average torque. Furthermore, numerical investigation on PM eddy current loss and iron loss at MTPA and flux-weakening control has been carried-out in terms of PM step-skew.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.969-974
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• 2008

As the railway becomes higher, the reliable stability and riding comfort of higher railway are required. To improve the riding comfort of high-speed trains, it is very helpful to use active suspension system for railway. In Japan, the high-speed train, Shinkansen has adopted semi-active suspension system and now it is running in the main trunk. In this paper, the authors introduce several technical trends of vibration control methods of Japanese Shinkansen. And the installation of semi-active suspension to HSR 350x and the test result of test run on the Kyoung-Bu high speed ling are also explained. After development of HSR 350x, new R&D national project of high speed train is progressed by Ministry of Land, Transport, and Maritime Affairs. This project is the development of Electric Multiple Unit of high speed train with 400km/h of maximum test speed. These result would be helpful to progress next generation high speed project.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.900-904
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• 2009

The measurement of contact wire uplift in electric railway is one of the most test method to accept the maximum permitted speed of new vehicles or pantographs. The contact wire uplift can be measured for shot periods when pantograph is running in monitoring station. This paper describes the development of two different methods for contact uplift measurement using vision-based system and wireless online monitoring system. Our vision-based system employs a high-speed CMOS (Complementary Metal Oxide Semiconductor) camera with gigabit ethernet LAN. The development of a real-time remote monitoring system that acquires data from any kind of sensor to be transmitted by wireless communication from overhead line and structure at 25 kV to a computer in catenary system. The proposed two kind of different measurement systems to evaluation for dynamic uplift of overhead contact wire shows promising on-field applications for high speed train such as Korea Tilting Train (TTX) and Korea Train eXpress (KTX).

• 대한방사선치료학회지
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• 제4권1호
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• pp.47-52
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• 1990

The MM-22 medical microtron at Korea Cancer Center Hospital has been running for radiotherapy since it was installed in 1986. The microtron is a very flexible radiation therapy device with excellent radiation field for photon or electron therapy. The microtron accelerates elections from an energy of minimun 5.3MeV to an energy of maximum 22.5MeV. The electrons are led from the microtron to the treatment head via a beam transport system and are used for radiotherapy. Present paper describes the system structures and operating characteristics of the MM-22 microtron and its therapy unit.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.217-221
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• 2001

Barber bogie and Y25 bogie is the main bogie of freight car which is used in the Korean railway. In case of Barber bogie and a mixed formation tile maximum speed limit of empty car is 70 km/h and that of loaded car is 90 km/t and also it runs a speed of 110 km/h in time of an exclusive formation of Y25 bogie. The car named as high speed freight car at present is Y25 bogie which modeled on the Y25 bogie or Europe developed in 1993, Y25 bogie has no problem about the running capacity up to the speed of 110 km/h, but it works as limiting factors to tile increasing cost of maintenance and repair expenses which caused by repair of bogie and the cost of materials. This study is going to describe the contents examined by analysis and tests, aimed at being used as an index of plan in the future through the strength test of high speed freight car which is used now.