• Journal of Electrical Engineering and Technology
• /
• v.12 no.3
• /
• pp.1046-1052
• /
• 2017

The load on the power grid of South Korea is expected to grow continuously until the late 2020s, and it is necessary to increase the transfer capacity from the Eastern grid to the Seoul-Gyeonggi region by reinforcing the transmission network for the electric power system to remain stable. To this end, the grid reinforcement by two bipole LCC HVDC transmission systems have been considered on account of the public acceptability and high growth of the fault current level, even though an additional 765kV system construction is more economical. Since the probability of the existing 765kV double circuit transmission line trip is extremely low, a dynamic simulation study was carried out to estimate the efficient HVDC capacity able to stabilize the transient stability by utilizing the HVDC overload capability. This paper suggests the application plan to reduce the HVDC construction capacity with ensuring the transient stability during the 765kV line trip.

• Journal of Power Electronics
• /
• v.16 no.1
• /
• pp.38-47
• /
• 2016

This paper presents DG based droop controlled parallel inverter systems with virtual impedance considering the unequal resistive-inductive combined line impedance condition. This causes a reactive power sharing error and dynamic performance degradation. Each of these drawbacks can be solved by adding the feedforward term of each line impedance voltage drop or injecting the virtual inductor. However, if the line impedances are high enough because of the long distance between the DG and the PCC or if the capacity of the system is large so that the output current is very large, this leads to a high virtual inductor voltage drop which causes reductions of the output voltage and power. Therefore, the line impedance voltage drops and the virtual inductor and resistor voltage drop compensation methods have been considered to solve these problems. The proposed method has been verified in comparison with the conventional droop method through PSIM simulation and low-scale experimental results.

• The Journal of Information Systems
• /
• v.17 no.4
• /
• pp.301-319
• /
• 2008

The display market has been replaced by the FPD (Flat Panel Display) from the CRT (Cathode-Ray Tube) since the late 1990s. In the FPD production line, the most equipment has high price. Thus, when the equipment has multi-function, the repetitive process is arranged for the equipment. However, such disposition of equipment results in more complicated process flow owing to repetitive operations. This reduces the production capacity and increases lead-time in turn. In this paper, we develop an AutoMod simulation system that derives to information about the quantity, production lead-time, utilities of facilities, and occupation rates of racks. In this simulation system, we consider the situation where the equipment might be broken and suspended randomly. For the developed system, we first evaluate a production plan with current layout and then, propose a revised alternative plan. Using the same simulation scheme, we investigate comparing the production quantity and lead-time with the two plans. In addition, for a proposed alternative, we try to forecast the most adequate rule between the two job dispatching rules which are FOR (Fewest Operation Remaining) and FCFS (First Come First Serve) through simulation.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.5
• /
• pp.94-103
• /
• 1997

It is necesary that analog buffer circuit should drive an external load in the VLSI design such as switched capacitor efilter (SCF), D/A converter, A/d converter, telecommunicatin circuit, etc. The conventional CMOS buffer circuit have many probvlems according as CMOS technique. Firstly, Capacity of large load ar enot able to opeate well. The problem can be solve to use class AB stages. But large load are operated a difficult, because an element of existing CMOS has a quadratic functional relation with inptu and outut voltage versus output current. Secondly, whole circuit of dynamic rang edecrease, because a range of inpt and output voltages go down according as increasing of intergration rate drop supply voltage. In this paper suggests that new differential CMOS line driver make out of operating an external of large load. In telecommunication's chip case transmission line could be a load. It is necessary that a load operate line driver. The proposal circuit is planned to hav ea high generation power rnage of voltage with preservin linearity. And circuit of capability is inspected through simulation program (HSPICE).

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.37 no.2
• /
• pp.1-8
• /
• 2014

The automobile manufacture is a typical integrated assembly production that the numerous parts are committed sequentially to the assembly line. In this type of automobile manufacture, WBS (white body storage) and PBS (paint body storage) are operated to adjust the production sequence and to buffer. Starvation (impossibility of production owing to the insufficient supply) or blocking (impossibility of production owing to the over capacity) could occur in some chance, hence, both storages (WBS, PBS) are integrated as a prevention. This system is called integrated storage. In this paper, we suggest the simulation model of 'WBS-PBS integrated storage' and methodology of operation considering both 'Color grouping' and 'Option leveling.'

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.490-497
• /
• 2011

When operating Express and Standard trains, which run with two different scheduled time, in a single line with limited number of side tracks for overtaking standard trains, it is required to have various modeling methodologies and simulations in order to calculate an optimum headway to maximize the capacity of the line with the best scheduled time. Especially it is inevitable that following trains have to slow down or stop in the middle of their operations due to the preceding trains, in case it is inappropriate controlled about either in which station an overtaking should be taken or how long it should be. This study is to analyze TPS data which have been produced with a simulation program which the team has invented to optimize Express and Standard mixed traffic plan and to introduce an algorism which shows detected conflict data, calculates appropriate dwell time after getting overtaken and helps to decide stations for overtaking.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.25 no.1
• /
• pp.103-114
• /
• 2001

In Korean clothing industry, most of the womens wear is manufactured by subcontractors. Because womens fashion is getting more rapidly changing, subcontractors production run of each orders is getting shorter too. Also the volume of each order is quite small compare to mens or childrens. So subcontractors are always in a hurry to adjust their production capacity to new order. Therefore they cannot afford to plan production line and allocate works efficiently enough to manufacture competitive products in terms of cost, lead time, as well as quality. The purpose of this study is to suggest a production planning model for womens apparel manufacture, which are relevant to the situation of Korean clothing industry.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.4
• /
• pp.1216-1231
• /
• 2021

With the increase in the population of our cities and the rapid increase in the number of private cars, urban traffic has become more and more congested. At this stage, urban public transportation has become one of the main ways to improve urban traffic congestion. Aiming at the problem of how to improve the basic capacity of buses in multi-line transfer stations, this paper conducts simulation research based on anylogic software. Through micro-simulation analysis of vehicles entering, stopping, and exiting the station, combined with the delay model theory, the vehicle is given Stop organization optimization and station layout improvement methods, so that vehicles can run in the station more stably, smoothly and safely. Case analysis shows that applying this method to the roadside parking problem, the main and auxiliary bus stations have a significant improvement in operating capacity compared with the conventional tandem double bus stations, and the service level of the main and auxiliary bus stations has been significantly improved.

• Proceedings of the KIEE Conference
• /
• 2005.11b
• /
• pp.35-38
• /
• 2005

This paper suggests the method that forecast Dynamic Line Rating (DLR). Thermal Overload Risk (TOR) of next time is forecasted based on current weather condition and DLR value by Monte Carlo Simulation (MCS). To model weather element of transmission line for MCS, we will propose the use of weather forecast system and statistical models that time series law is applied. Also, through case study, forecasted TOR probability confirmed can utilize by standard that decide DLR of next time. In short, proposed method may be used usefully to keep safety of transmission line and reliability of supply of electric Power by forecasting transmission capacity of next time.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.7
• /
• pp.4918-4924
• /
• 2015

In this paper, we consider the capacity improvement of systems exploiting dual-polarized antennas for two-user transmission. To this end, we analyze the upper bounds of ergodic capacities for multicast and unicast data services in the systems, and propose the condition for adjusting the complex cross-polarization discriminations (XPDs) to maximize the ergodic capacities. In addition, we present the adjustment condition of the complex XPDs that can achieve spectral efficiencies close to the maximum ergodic capacities with lower system complexity. Lastly simulation results demonstrate that the systems using the proposed conditions can obtain higher spectral efficiencies than the ones employing different adjustment conditions including the exiting adjustment condition.