• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.129-131
• /
• 2007

In this paper, we research improvement in efficiency of single-phase induction motor by adapting the condition of the balanced and quasi-balanced operation. we maintain turns of auxiliary winding of the motor and adjust resistance and reactance. In this condition, resistance value and copper loss are much gloater. Namely, this is the condition only for balancing MMF without consideration of copper loss of stator winding. To make more practical design, therefore, we will perform winding design which is based on balanced operation condition and applies copper loss minimum. The problem of deterioration of starting torque is completed by rotor bar shape design.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 C
• /
• pp.1155-1157
• /
• 1999

The UPFC is known to have the ability to control both the real power flow and the reactive power flow. [1],[2] The power flow in the system is heavily related with the system security. [4] This paper deals with the operation of the UPFC to increase the power system security. The concept of the power system security is verified and the index to indicate the power system security level is suggested. And the algorithm to find the optimum operation point of the UPFC improving the system security level is presented.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권5호
• /
• pp.677-683
• /
• 2008

The electric propulsion system us closely related with the economical efficiency of ship operation. Fuel efficiency is mainly decided by propulsion system such as diesel engine, propulsion motor and steam turbine. The hybrid propulsion system for fishing boat consists of diesel engine and battery as propulsion power source. This paper is to design battery capacity according to power consumption with ship operation condition, and to test the power consumption of model ship in the circulating water channel. As a result. it can be known that the optimum ship operation condition affects the fuel efficiency.

• 전기학회논문지
• /
• 제61권6호
• /
• pp.797-803
• /
• 2012

In this paper, for minimizing the real-time operating load losses of the power transformer, a SCADA optimum operating system was developed, and the economic analyses on the test operation were performed. Transformer loss DB which reflects the economic integration operation criteria was constructed by referring the transformer manufacturer's loss data(iron loss, copper loss). Based on the loss DB, each substation transformer real-time loss was calculated according to the size of the transformer loads, and if integration or separation transformer operating conditions minimizing the loss are met, then a window pops-up and the dispatcher performs the substation equipments operation according to the procedure provided by this system. With the existing SCADA main program, the relation database of the substation facilities and integration/separation operation algorithm were developed and applied to Auto MTR Processor and pconn Processor Task module. Seven stations test data for seven months were analyzed for the economic analyses, and the results showed that Cost-Benefit ratio was 2.64, and IRR(Internal Rate of Return), 36%, which asserted the economic justification of the proposed system.

• Nuclear Engineering and Technology
• /
• 제48권4호
• /
• pp.1022-1035
• /
• 2016

A double-tube once-through steam generator (DOTSG) consisting of an outer straight tube and an inner helical tube is studied in this work. First, the structure of the DOTSG is optimized by considering two different objective functions. The tube length and the total pressure drop are considered as the first and second objective functions, respectively. Because the DOTSG is divided into the subcooled, boiling, and superheated sections according to the different secondary fluid states, the pitches in the three sections are defined as the optimization variables. A multi-objective optimization model is established and solved by particle swarm optimization. The optimization pitch is small in the subcooled region and superheated region, and large in the boiling region. Considering the availability of the optimum structure at power levels below 100% full power, we propose a new operating scheme that can fix the boundaries between the three heat-transfer sections. The operation scheme is proposed on the basis of data for full power, and the operation parameters are calculated at low power level. The primary inlet and outlet temperatures, as well as flow rate and secondary outlet temperature are changed according to the operation procedure.

• 한국가스학회지
• /
• 제8권4호
• /
• pp.15-22
• /
• 2004

본 연구는 LNG 기지 내 주요 프로세스 설비인 LNG 고압펌프의 운전유량 및 토출압력을 조절함으로서 공정운영 조건을 개선하기 위해 수행되었다. 공정 해석 시뮬레이터인 ASPEN PLUS를 사용한 고압펌프의 실제 운전 성능분석 및 천연가스 송출부하 분석을 통하여 계절별 적정 LNG 고압펌프 토출유량을 결정하였고 그 결과는 현장운전에 적용되었다. 이로 인하여 고압펌프 소모 전력비용을 낮출 수 있으며, LNG기지 내 운영 프로세스 압력을 감소 시켜 보다 안전적인 기지운영을 유도할 수 있었다.

• 한국물환경학회지
• /
• 제32권2호
• /
• pp.191-196
• /
• 2016

This study aimed to evaluate SBR operation cycle for removing the high-concentration organic matter of distillery wastewater in the ginseng processing plant. The experiment was conducted with the use of a laboratory scale SBR reactor and distillery wastewater as the influent. The results indicated an increase in pH from 4.08 to 7.59 of distillery wastewater after aeration for 2 hours. Also, the optimum SBR operation cycle for the removal of organic matter and nitrogen was 2 hr of aeration and 6 hr of anaerobic conditions. Adjustment of proper pH through aeration time is most critical in the SBR operation for distillery wastewater treatment. In this study, we presented an efficient method for distillery wastewater treatment.

• 대한기계학회논문집B
• /
• 제36권5호
• /
• pp.523-531
• /
• 2012

제습냉방시스템에서 주요 구성부품인 제습로터의 성능을 극대화 시키기 위한 방법으로 제습로터의 회전주기의 제어에 대한 연구를 수행하였다. 열과 물질전달의 과정을 모델화하여 얻은 수치해를 바탕으로 제습로터성능 시뮬레이션 프로그램을 구성하여, 재생공기 온습도, 풍량 등의 운전조건에 대하여 회전 주기에 따른 제습로터의 제습량을 구하였다. 성능 시뮬레이션 결과 검증을 위하여, 실험을 통해 측정된 값과 성능해석 모델을 이용하여 계산된 값을 비교함으로써 성능 시뮬레이션 모델의 타당성을 보였다. 각 운전조건에서 제습량이 최대가되는 제습로터의 회전주기를 최적 회전주기로 정의하였고, 회전주기를 고정(400s)할 때의 제습성능과 비교하여, 최적 회전주기제어가 제습성능에 미치는 영향을 분석하였다. 그리고 회귀분석법을 이용하여 재생온도, 외기상대습도, 풍량을 변수로 하는 최적 회전주기의 예측상관식을 개발하고 시뮬레이션 값과 비교하여 검토하였다.

• Tribology and Lubricants
• /
• 제37권5호
• /
• pp.172-178
• /
• 2021

An injector is a mechanical device present inside the engine. Its main function is to supply an appropriate volume of fuel into the combustion chamber, which is directly related to the overall engine efficiency of a car. During the operation of an injector, a magnetic force lifts the parts of the injector from closed position to open position which generates a horizontal force on the needle. The horizontal force acts on a different position from that of the center of mass of the needle. Therefore, this causes eccentricity in the needle and the generation of a tilting motion during the lifting operation which can result in wear. However, appropriate selection of clearances for these parts can prevent wear. In this study, lubrication analysis is conducted to determine the optimum clearance of parts with sliding motion inside the injector. The height functions are derived considering the dynamic behavior and relative velocity of the parts. Using the derived height function, the pressure profiles are calculated for the lubricated surfaces from the Reynolds' equation. Subsequently, the fluid reaction forces are calculated. The equations of motions are applied to the fluid reaction forces and external forces are solved to calculate the minimum film thickness between each part with variation in the clearances. Finally, the optimum clearances are determined. The effect of the clearances on the behavior of the moving parts is presented and discussed.

• 펄프종이기술
• /
• 제44권6호
• /
• pp.1-8
• /
• 2012

This study was carried out to explore optimum use of the products generated from the National Forest Management Operation (NFMO) as raw materials for kraft pulp. First of all, different wood species from NFMO were randomly mixed, and then they were used to make kraft pulp under the specified condition. All kraft pulps made from the mixed species displayed equal physical properties to those from foreign wood chips used in Moorim P&P Co. Ltd. For optical properties, most of the unbleached pulps had high brightness but the pulp made from wood species containing chestnut tree showed the lowest brightness due to its high kappa number. Finally, the products from NFMO had little negative effects on the properties of kraft pulps. This means that they could be used as complementary raw materials for kraft pulps with foreign wood chips.