• Proceedings of the KIEE Conference
• /
• 2005.11b
• /
• pp.198-200
• /
• 2005

This paper illustrates the pragram features of reliability evaluation on operation mode (operational planning and operating) of power system. The eighty eight relative reports and papers with seventeen kinds of reliability programs were Investigated in this paper. Two programs, PRA and ASSESS, were focused on the operation mode reliability evaluation program and the comparions of the two program features are introduced.

• Journal of Korean Society for Atmospheric Environment
• /
• v.7 no.1
• /
• pp.31-40
• /
• 1991

This study shows the correlation between $NO_x$ emission in the exhaust gas and various operation factors of dual fuel engine for Co-generation system. General tendency was shown that the thermal efficiency was lowered by the change of operation factors. However these were not confirmed on this experiment. Increasing T4 temperature (exhaust gas temperature at turbo-charger inlet) reduces $NO_x$ emission rate. The higher T4 temperature requires lower excess air as the excess air ratio is controlled by T4 temperature on gas mode operation. Another tendency was that $NO_x$ emission rate is reduced in case of increasing boost air temperature, quantity of pilot oil or bypassing flue gas through the exhaust gas boiler. The diameter of the fuel injection nozzle was changed smaller than design value and the injection timing was readjusted. Thus $NO_x$ emission rate could be reduced as retarding injection timing and changing hole diameter of fuel injection nozzle, however maxium engine out-put was decreased by changing fuel nozzle on the diesel mode operation.

• Journal of Industrial Technology
• /
• v.27 no.A
• /
• pp.47-53
• /
• 2007

A theoretical model based on Rayleigh-Ritz method is proposed to predict the resonance frequency of a W/T(Wind Turbine) tower structure supported by guy cables. In order to verify the validity of the theoretical model, a reduced W/T tower system is manufactured and tested. Frequency response and mode data are determined by modal testing and finite element analysis is performed to calculate the natural frequency of the tower model. Numerical and experimental results are compared with those by the theoretical analysis. Parametric study by the theoretical model shows how the cable tension and cable elasticity influence the resonance frequency of the W/T tower structure. Finally, vibration response under various rotating speed is investigated to examine the possibility of severe resonance.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.273-274
• /
• 2014

다 출력 Flyback 타입 전원공급장치(Switch Mode Power Supply)에서 제어 출력단과 비 제어 출력단 부하 차이로 인하여 비 제어 출력단 전압이 크게 상승하는 현상이 발생한다. 본 논문은 전원공급장치 트랜스포머 결합도가 비 제어 출력 전압 변동 상승에 미치는 영향을 분석하기 위해 다양한 트랜스포머 권선 방법을 제시하였고, 이를 실험을 통해 검증하였다.

• Journal of Korean Society of Transportation
• /
• v.12 no.3
• /
• pp.29-47
• /
• 1994

Although subway system continues to be the backbone of transportation systems in a city like Seoul, there will still be areas across the city where subway services are not avaliable. Interest has steadily grown to fill this missing routes in overall urban transportation system. Light Rail Transit (L.R.T) system has been recently thought to be an appropriate mode of transportation by businessmen, professionals and transportation industry. In this regards, the purpose of this study is to explore whether L.R.T can be a feasible form of urban rail mode in the context of Seoul. First, the study develops the mathematical models to derive optimum route networks and stations. Integer Programming is employed to determine whether alternative routes are financially viable from the viewpoint of revenue maximization principles. Second, mathematical models developed are applied to Yoido area in order to examine the validity of model structures. The models constructed turns out be capable of handling alternative routes and stations. Application of models are successfully carried out to derive financially feasible set of routes and stations.

• Journal of IKEEE
• /
• v.22 no.4
• /
• pp.1210-1213
• /
• 2018

In this paper, we propose a method to reduce the amount of current through the Timing Control of the duty cycle and the Report Attribute Control at the MAC Layer in consideration of the Sleep Mode under the IoT wireless environment. The use of a duty cycle is an effective way to reduce energy consumption on wireless sensor networks where the node is placed in sleep mode periodically. In particular, we studied how to control power efficiency through duty rate in Short Transition Time and ACK Time processing while satisfying radio channel limitation criterion. When comparing before and after the improvement considering the delay time constraint, we validated the correlation of the electrical current reduction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2019.05a
• /
• pp.122-124
• /
• 2019

최근 IoT 시스템의 관심도가 높아지고 있어 기본 활용 기술의 방법 중 블루투스 비콘 모드를 이용한 정확한 위치 탐지 방법에 대한 연구가 진행되고 있다. 본 논문에서는 블루투스 모듈의 비콘 모드를 활성화하여 불특정 다수의 사용자들에게서 획득한 정보의 고유아이디(UUID, Universally Unique Identifiers) 식별 및 특정 기기의 위치를 파악하여 해당 UUID의 위치 탐지 방법을 제안하였다. 비콘 정보의 수신신호세기(RSSI, Received Signal Strength Indicator)값을 이용하여 불특정 사용자의 위치를 탐지하고, 설정된 RSSI의 범위 구간에 따라 탐지 객체의 IoT 모듈에 접근 여부를 판단하고, 접근이 감지되었을 때 해당 모듈의 IoT 모듈의 기능을 작동시키는 방식으로 활용할 수 있다. 또한, 위치 탐지의 정확성을 위해 RSSI의 데이터를 저장하고, 저장된 데이터 관찰을 통하여 해당 블루투스의 위치 데이터를 보다 정확하게 파악하는 시스템을 설계하였다.

• Korean Chemical Engineering Research
• /
• v.55 no.6
• /
• pp.816-821
• /
• 2017

An integrated slow mixing/sedimentation and net fit fiber filtration system has been developed to reduce the high concentrations of suspended solid (SS) and total phosphorus (T-P) in the reject water from sewage/wastewater. A filtration device used in this experiment consists of coagulation, in-line mixing, air injection, slow mixing/sedimentation, and filtration processes. The performance test using this device was carried out with six operational modes for reject water from sewage treatment plant. Experimental conditions used were 16.7, 33.3, 41.7 and 50.0 ton/day of flow rate and 2~4 of Al/P molar ratio. By injection of coagulant in each operational mode, the high removal efficiencies of SS and T-P were obtained, but continuous operation time was decreased to 7.8~11.4 min in most modes. However, when the Mode 5 of the developed filtration device was applied, the continuous operation time was maintained up to 88.2 min. Also, it was found that the continuous operation time in the Mode 5 using the developed system was increased from 8 to 11.3 times longer than those in other modes. Backwashing flow rate was also very low at 5.4% of total filtered water. Therefore, it can be concluded that the Mode 5 of the developed filtration system was the most efficient treatment method for the removal of high concentrations of SS and T-P.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.3
• /
• pp.383-391
• /
• 1986

Mode shapes and natural frequencies of the bell type shell are analyzed numerically by the finite element method. The impulse hammer method and the Fast Fourier Transform analyzer are used for the experimental test. All types of mode shapes are expressed by the computer graphics. Numerical solutions are good agreement with the experimental results. The sustaining sound of the typical bell-type shell depend upon the first flexural mode (0-2 mode) and the second flexural mode (0-3 mode), and their mode shapes are independent upon thickness Dangjwas, holes, and added mass effects. Asymmetric effects by Dangjwas, holes and added mass give rise to beat frequencies, and the added mass is found to be most effective.

• Journal of Korean Society of Steel Construction
• /
• v.28 no.6
• /
• pp.459-465
• /
• 2016

In this paper, it was performed the fatigue test to examine the effect of cyclic loading for the simple T-joint. Axial force of bolt by clamping and the change of the force by applied load were measured in the joint. And the bolt force, the failure mode and the fatigue strength under cyclic loading were investigated. The parameters of the tension joint were set to be the flange thickness and the diameter of bolt to a different stiffness of the joint in response to the combination. From the fatigue test, failure mode of tensile joints under cyclic loading could be evaluated using a static ultimate load of the specific failure mode in EC3. The fatigue strength of the tension joints was considerably higher than the fatigue strength of the EC3(36) that does not consider a lever action. However, the additional axial force by lever action occurs to an increase in the axial force of the bolt it requires a careful evaluation of the fatigue strength.