• 한국시뮬레이션학회:학술대회논문집
• /
• 한국시뮬레이션학회 2004년도 춘계학술대회 논문집
• /
• pp.63-68
• /
• 2004

The objective of this paper is to analyze the combined productivity at container terminal. We present a mode3 for combined productivity that perform the container transportation between apron and yard. Usually, the efficiency of container terminal is evaluated by productivity of container cranes at apron, but there are other equipment such as transport vehicles and yard cranes. Therefore, a method that can estimate the combined productivity of equipment of container terminal is required. We performed various simulation experiment and analyzed combined productivity to estimate the required number of equipment.

• 무역학회지
• /
• 제47권4호
• /
• pp.271-292
• /
• 2022

In Korea, the road transport industry is pointed out as a major cause of air pollutants, so management control is needed. Existing studies used only positive input and output variables to measure regional efficiency. However, it is necessary to consider the environmental pollution problem in efficiency analysis. In this study, an undesirable SBM analysis using CO₂ was conducted to measure efficiency of domestic regions. In addition, SDM was conducted to examine the ripple effect between domestic regions. As a result of the analysis, the efficiency of the capital area such as Seoul, Gyeonggi, and Incheon was high in the road transport industry. However, the efficiency of the road transportation industry in Daegu and Gangwon was low. In the SDM analysis, it was found that the regional equipment capabilities had a great influence on efficiency. In order to improve efficiency, it is necessary to increase and improve the equipment capacity of the road transport industry.

• 국제학술발표논문집
• /
• The 5th International Conference on Construction Engineering and Project Management
• /
• pp.226-230
• /
• 2013

In the tall building construction, the slab formwork largely impacts on construction cost. Because productivity of a slab formwork is influenced by a number of and the efficiency of equipment, using the equipment-based construction method, an appropriate equipment input planning is crucial for the productivity. Meanwhile, the general equipment input planning is conducted by intuition based on experience due to the lack of equipment productivity data. Thus, this study develop a simulation model to analyze table formwork productivity and to propose an optimum equipment input plan that reflects the construction process, based on the full consideration of the economic factors. This study developed a simulation model by using CYCLONE and the data for the model was collected by measuring the duration of each unit activity in the tall building where table forms were applied. It is expected that a simulation model helps users to make better decision on the equipment input planning of slab formwork.

• 한국기계기술학회지
• /
• 제13권4호
• /
• pp.157-164
• /
• 2011

Hybrid car can improve fuel efficiency using a power of motor that is generated during constant-speed or deceleration driving. The motor is located between engine and transmission. But, when voltage of main battery is low, fuel efficiency is low because the voltage can't run the motor. In this situation, this study observed fuel efficiency when using solar cell for assistance power. In order to verify a fuel consumption of hybrid car equipped solar cell for assistance power, the car was tested downtown driving. As hybrid car was equipped solar cell for assistance, fuel consumption was reduced 8.35 % at running air conditioner. And, at air conditioner doesn't work, fuel consumption was reduced 6.88 %. This point of view, CO2 is expected to reduce in similar proportion.

• 반도체디스플레이기술학회지
• /
• 제17권4호
• /
• pp.51-55
• /
• 2018

As the OLED industry develops, display equipment is becoming larger. As a result, the stage required for display equipment is getting bigger. This enlargement led to increase in OLED production and industrial development. However, due to the large scale of the stage, other problems due to overheating and overheating caused by heavy load on the linear motor, which is mainly used in the stage, must be solved. In this study, a linear motor equipped with a cooling channel is modeled and the three - dimensional heat conduction flow analysis for this model is simulated using Fluent to analyze the cooling efficiency and cooling efficiency according to the cooling water flow rate. As a result, the cooling channel was effective and the cooling effect and efficiency were the best when the flow rate was about 5 ~ 10 L./min. In addition, the cooling effect is increased when the flow rate is increased, but the efficiency is significantly lowered when the flow rate is more than the predetermined value.

• 대한토목학회논문집
• /
• 제32권4D호
• /
• pp.357-366
• /
• 2012

기존의 품셈과 지방세법은 건설중장비가 수 년에 걸친 감가상각 대상임에도 불구하고, 물가지수를 제대로 반영하지 못하고 있다. 이에 본 연구에서는, 법인세법과 지방세법 및 기업회계기준서를 분석하여 국내 감가상각제도의 특징과 상각방법을 정리하여 제시하였고, 경제성 이론이 반영된 건설중장비 자본회수계수를 제시하였고, 정액법과 정률법을 사용하여 표준품셈을 기준으로 한 감가상각과 세법을 기준으로 한 감가상각 사례를 제시하였다. 개선방안으로는, 건설중장비의 자발적 사용기간 신청제도와 현행제도와의 관계를 설명하고 도입을 제안하였으며, 국내물가지수를 기초로 월단위 기계경비 감가상각율표를 개발하여 제공하였으며, 그 적용방안을 예시하였다. 또한, 제안한 방안의 장점과 단점을 분석하여 연구의 적용한계와 차후 개선방향도 제시해 보았다. 본 연구를 통해 품셈과 세법에 보다 합리적이고 객관적인 현실성을 반영할 수 있을 것으로 판단된다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.974-981
• /
• 2007

Seoul Metro has operated the air cooling equipment established in a machine room of a station building to improve our services focused on our customers who use Seoul Metro during the summer season. However, a new set of problems has arisen with the cooling tower to support a heat exchange of cooling water. One of them is loss of efficiency in the air conditioner. The leading cause of this problem is that we use an underground type of the cooling tower. As the machine room of a station building is located in the underground of inner city because of the nature of the subway, it is difficult to establish the cooling tower on the ground. The underground structure of the No. $1{\sim}4$ subway line is unsuitable for the location requirements of the underground type of the one because it has a limited space to set up the air cooling equipment, for example, the cooling tower and a ventilating opening. As a result of such an unfavorable condition, the cooling tower doesn't work efficiently and the warmth of cooling water because of insufficiency of a heat exchange and a refrigerator's technical obstacle such as a high-temperature and a high-pressure has arisen. Accordingly, the efficiency of the air conditioning is getting lower and lower. Another problem is too wasteful with water. Each station uses the water over 30 tons every day with waterworks to replenish the cooling tower such as a evaporation, a scattering and a distribution of water. Nevertheless, the more an air conditioner increase, the more the use of water supply increase. For this reason, we can't help wasting an enormous amount of water and discharging the congelation of a low temperature(about $15^{\circ}C$) occurred in a heat exchanger inside an air conditioner. The purpose of this study is to analyze the utility of congealing water to improve efficiency of the air cooling equipment and save energy as a supplementary water for the cooling tower.

• 산업경영시스템학회지
• /
• 제33권4호
• /
• pp.100-113
• /
• 2010

Manufacturing companies' cost competitiveness with respect to equipment management can be achieved by satisfying additional market demands by their own capacity without purchasing additional equipments. In essence, it can be accomplished by making continuous investigation into bottlenecks and improvement on them. Therefore, equipment performance measure systems should be designed so that they can support manufacturing companies' such endeavors. With the purpose of establishing an effective equipment performance measurement system for detecting and improving bottlenecks, this study (1) suggests some desirable features that such a system should have, (2) evaluates conventional equipment performance measurement systems in terms of their usefulness for the detection and improvement of bottlenecks, and (3) proposes an improved system. We also perform a simulation experiment to demonstrate the limitations of the conventional systems and show how the proposed system can resolve the problems.

• Journal of Power Electronics
• /
• 제11권6호
• /
• pp.880-889
• /
• 2011

In this paper, a novel Active Voltage Quality Regulator (AVQR) topology with a thyristor rectifier and an adaptive dclink voltage control strategy are proposed. The proposed AVQR can efficiently mitigate the long duration variations (e.g. undervoltages/overvoltages), voltage imbalances and voltage harmonics. Compared with conventional AVQRs, it can regulate the load voltage very well with a much lower dc-link voltage. This is accomplished by replacing the diode rectifier with a thyristor rectifier. Moreover, its dc-link voltage can vary with the deviations of the supply voltage through the proposed adaptive dc-link voltage control strategy. All of these contribute to its significantly higher efficiency for online operating, which is very important and attractive for many applications. The proposed topology and control strategy are theoretically analyzed in detail. Simulation results are also provided in the paper. Finally, the feasibility and effectiveness of the proposed method are verified by means of experimental results from a 2kVA prototype. Both of the simulation and experimental results show that the proposed AVQR can achieve a much higher efficiency and similar regulation performance when compared with the conventional ones.

• Journal of Advanced Marine Engineering and Technology
• /
• 제29권2호
• /
• pp.185-193
• /
• 2005

The present study composed a diesel-atkinson cycle of high expansion as a method of achieving high efficiency in diesel cycle engines. It also interpreted the cycle engine thermodynamically analysis to determine the possibility of the improvement of thermal efficiency and clarified the characteristics of several factors . According to the result of theoretical analysis, heat efficiency was highest when expansion-compression ratio Reど:1. In addition. diesel engines with high apparent compression ratio had higher expansion-compression ratio than otto engines and consequently their effect of high expansion was high. which in turn enhanced thermal efficiency. When the atkinson cycle was implemented in a real diesel engine by applying the miller cycle through the variation of the closing time of the intake valve, the effective compression ratio and the quantify of intake air decreased and as a result, the effect of high expansion was not observed. Accordingly. the atkinson cycle can be implemented when the quantity of intake air is compensated by supercharge and the effective compression ratio is maintained at its initial level through the reduction of the clearance volume. In this case. heat efficiency increased by $4.1\%$ at the same expansion-compression ratio when the apparent compression ratio was 20 and the fuel cut off ratio was 2. As explained above, when the atkinson cycle was used for diesel cycle. heat efficiency was improved. In order to realize high expansion through retarding the intake value closing time, the engine needs to be equipped with variable valve timing equipment, variable compression ratio equipment and supercharged Pressure equipment. Then a diesel-atkinson cycle engine is realized.