• 한국자동차공학회논문집
• /
• 제10권3호
• /
• pp.44-50
• /
• 2002

The connecting rod big-end bearing is one of the most heavily loaded components of the lubrication system of high-speed combustion engines. The supply oil flow has to pass to the main bearing and the rotating crankshaft before entering the connecting rod bearing. It is common knowledge that the centrifugal forces due to the crankshaft rotation influence the oil flow to connecting rod bearing through the oil supply bore, especially, when the oil supply system to the connecting rod bearing has a 180$^{\circ}$circumferential groove via a single drilling in the crankshaft. In this case, it should be confirmed that the groove oil pressure in the main bearing is sufficient to overcome these centrifugal forces. For the purpose, the dynamic oil pressure before entering oil supply bore to the connecting rod bearing was measured instead of averaged oil pressure in main gallery. Experimental test results show that the dynamic oil pressure in the oil groove was more useful than that of main gallery. And it was also found that the oil pressure fluctuation in the groove was sensitively affected by the reduction of the main bearing clearance.

• 전기학회논문지
• /
• 제60권9호
• /
• pp.1651-1655
• /
• 2011

The reference impedances which is about 95% supply impedance value of residential consumers' supply impedances was published by IEC in 1980. The reference impedances are the standard values for use in determining the voltage disturbance characteristics of electrical equipment like the flicker. In IEC 60725, the reference impedances for premises having service current capacities less than 100A per phase and for service current capacities more than 100A per phase are recommended. And these reference impedances are targeted for the countries using 50Hz power frequency. Because of the frequency difference, the reactance values of the reference impedances will be increased in 60Hz power system like Korea, And also the reference impedances are different significantly each other according to declared voltage variation, power consumption and service wire length etc. Therefore It is needed to calculate the reference impedances suitable for domestic low-voltage power system. In this paper, the reference impedances for service current capacities less than 100A in 220/380V, 60Hz single-phase two wire and three-phase four wire low-voltage system are calculated, And the equations for service current capacities more than 100A to calculate the modulus value of maximum supply impedances are suggested base on IEC 60725 and the reference impedances for those are calculated on service current of 100A per phase.

• 조명전기설비학회논문지
• /
• 제19권7호
• /
• pp.100-106
• /
• 2005

일반적으로 자외선(UV)을 발생하기 위한 방전등 구동용 직류 전원장치는 하드 스위칭 모드로 동작되어지는 고주파 스위칭 DC-DC 컨버터가 사용되고 있다. 구체적으로 전원장치는 전자 노이즈 장해에 의한 전자 회로의 오동작이나 각 구성 소자의 발열의 문제 등이 시스템의 신뢰성을 저하시키는 원인이 되고 있다. 그러므로 본 논문에서는 소프트 스위칭 회로 기술을 사용한 고주파 링크 DC-DC 컨버터로서 먼저 구체적으로 1차측 위상 천이 PWM DC-DC 컨버터와 제안한 2차측 위상 천이 PWM DC-DC 컨버터를 조합하여 방전등 구동용 직류 전원장치를 제안하였다. 제안하는 방전등 구동용 직류 전원장치는 시뮬레이션과 실험을 통하여 그 타당성을 서술하였다.

• 전력전자학회논문지
• /
• 제23권3호
• /
• pp.168-173
• /
• 2018

In this paper, an auxiliary power supply (APS) for railroad cars is proposed. The APS can reduce the number of devices required to supply power through structural modification and operates at a high switching frequency by application of a SiC device. The voltage stress on the device in the proposed circuit can be reduced to less than half of the input voltage of the system; thus, a device with low breakdown voltage can be designed. By adapting a SiC device instead of an IGBT device, the proposed circuit can reduce switching and conduction losses and operate at a high switching frequency, thereby reducing output voltage and inductor current ripples in the proposed circuit. The theoretical analysis results of the proposed APS are verified with a 40 kW computer-based simulation and a 2 kW experiment.

• 대한산업공학회지
• /
• 제34권3호
• /
• pp.362-372
• /
• 2008

Manufacturers, or vendors, and their customers continue to adopt vendor-managed inventory(VMI) program to improve supply chain performance through collaboration achieved by consolidating replenishment responsibility upstream with vendors. In this paper, we construct a mixed integer linear programming model and propose a genetic algorithm for the integrated inventory and routing problems with lost sales maximizing the total profit in the VMI supply chains which comprise of a single manufacturer and multi-retailer. The proposed GA is compared with the mathematical model on the various sized test problems with respect to the solution quality and computation time. As a result, the GA demonstrates the capability of reaching solutions that are very close to those obtained by the mathematical model for small problems and stay within 3.2% from those obtained by the mathematical model for larger problems, with a much shorter computation time. Finally, we investigate the effects of the cost and operation variables on the total profit of the problem as well as the GA performance through the sensitivity analyses.

• 한국통신학회논문지
• /
• 제27권11C호
• /
• pp.1132-1138
• /
• 2002

본 논문은 시간 제약 조건하에서의 최적 선택 공급 전압을 위한 전력 감소 스케줄링 알고리듬을 제안한다. 전력감소 스케줄링에서는 전력소비를 줄이기 위해 가변 전압 레벨을 이용해 최적 공급 전압을 선택 휴리스틱 방법으로 연산을 수행하여 제어 스텝을 결정한다. 그리고 최적 선택 공급 전압 바인딩에서는 그래프 컬러링 기법을 이용해 레지스터 상의 전력 소비의 주원인인 스위칭 활동을 최소화한다. 상위 수준 벤치마크 예제를 이용한 실험으로부터 우리는 최적 선택 공급 전압을 이용한 제안한 알고리듬이 획일화된 단일 전압을 이용한 알고리듬보다 전력 소비를 줄이는데 효율적임을 보인다.

• 로봇학회논문지
• /
• 제16권3호
• /
• pp.223-231
• /
• 2021

In this paper describes the research and development of a pipe robot for pipe rehabilitation construction of old water pipes. After the water supply pipe construction, the pipe is leaking, damaged, and aging due to corrosion. Eventually, resistance to the flow of water in lower supply efficiency and contaminated water such as rusty water, finally in various consumer complaints. In order to solve this problem, rehabilitation construction robot technology is required to secure the construction quality of pipe rehabilitation construction and restore the function of the initial construction period. The developed pipe rehabilitation construction robot required a hydraulic actuator for high traction and was equipped with a small hydraulic supply device. In addition, we have developed a hydraulic cylinder and a link system that supports the pipe inner diameter to develop a single pipe robot corresponding to 500 to 800mm pipe diameter. The analysis and experimental verification of the driving performance and unit function of the developed pipe reconstruction robot are explained, and the result of the integrated performance test of the pipe reconstruction robot at the water supply pipe network site is explained.

• Industrial Engineering and Management Systems
• /
• 제3권1호
• /
• pp.38-51
• /
• 2004

Over the years, most or many companies have focused their attention to the effectiveness and efficiency of their business units. As a new way of doing business, these companies have begun to realize the strategic importance of planning, controlling, and designing their own supply chain system. This paper analyzes the coordination issues in supply chains that consist of one manufacturer and multiple retailers operating under uncertain end customer demand and delivery lead-time. We use the Genetic Algorithm (GA) to determine the appropriate ordering and inventory level at which the manufacturer and multiple retailers can maximize the profit of the chain. This is performed under three controlling policies: the traditionally centralized controlling policy under the manufacturer's perspective, the entire chain’s perspective, and lastly the coordinating controlling policy with an incentive scheme. The outcome from the study reveals that the coordinating controlling policy with an incentive scheme can outperform the traditional centralized controlling policies by creating a win-win situation in which all members of the chain benefit from higher profit, thus resulting in more willingness from all members to join the chain.

• 한국재난정보학회 논문집
• /
• 제20권3호
• /
• pp.541-548
• /
• 2024

연구목적: 본연구는 현재 국내 대부분의 산업 현장에서 전원공급을 위해 사용하는 변압기의 접지방식을 비교하여 전원설비의 전원 품질의 안정성과 감전 사고의 위험성을 비교 분석하고자 한다. 연구방법: 비 접지방식은 1선지락 사고 발생 시 전원공급을 지속적으로 할 수 있고 감전 사고에 대한 위험성이 낮고, 직접접지 방식은 지락이나 낙뢰 등의 사고 발생 시 전원 차단을 빠르게 하여 부하 설비를 보호하는데 중점이 있음을 문헌을 통해 비교 설명하였다. 결과 및 결론: 지속적인 전원공급이 필요한 곳에서는 비접지 방식을 사용하여야 한다는 필요성에 대해 결론을 내렸다.

• 한국국방경영분석학회지
• /
• 제11권1호
• /
• pp.1-7
• /
• 1985

A computer-aided simulation model for inventory control was developed using Apple II Plus micro-computer. The model forecasts quarterly demands with Single Exponential Smoothing method and simulates Supply Demand Review and Inventory Level Settings for each items. The simulation is based on the assumption that the demand occurrences have their own probability distributions.