• International Journal of Highway Engineering
• /
• v.16 no.5
• /
• pp.121-131
• /
• 2014

PURPOSES : The goal of this study is to analyze the travel cost according to transferring from rotary to roundabout in Korea. METHODS : This study gives particular attentions to investigating the existing 48 rotaries in Korea and building the networks of before and after improvements using VISSIM, and analyzing their travel costs. RESULTS : The main results are as follows. First, from the field survey, the domestic rotaries were analyzed to need many improvements of geometric structure for the effective operation. Second, the difference of travel cost at 3-legged rotaries were evaluated to be less than other types of rotaries due to low traffic volume. Finally, the travel cost of 4-legged and multi-legged rotaries were analyzed to rapidly increase by increasing volume. CONCLUSIONS : This study analyzes the effects using both real and simulation data unlike the existing studies. Also, this study suggests the future research topics which compare and evaluate the relations between real data and simulation outputs.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.4
• /
• pp.724-730
• /
• 2017

SpaceWire invented for spacecrafts has Time-Code defined for time synchronization over SpaceWire network. A Time-Code suffers transmission delay of 14[bit-period] and jitter up to 10[bit-period] whenever it passes through a SpaceWire link, which is the primary cause of time synchronization error. This work presents a simple method to improve the time synchronization which uses two extended Time-Codes. Nodes on a SpaceWire network can find how much delay and jitter a received Time-Code has suffered while it passes through the network, and they can correct time synchronization error with this information. The proposed method was validated in a simulation environment developed based on OMNeT++. The simulation result showed that time synchronization error less than a few bit-periods can be achieved. The proposed method is cost effective and suitable for small-scale SpaceWire network systems.

• Journal of Internet Computing and Services
• /
• v.13 no.3
• /
• pp.31-47
• /
• 2012

The mobile Virtual Private Network (MVPN) of Internet Engineering Task Force (IETF) is not designed to support NEwork MObility (NEMO) and is not suitable for real-time applications. Therefore, an architecture and protocol which supports VPN in NEMO are needed. In this paper, we proposed the cost-reduced secure mobility management scheme (CR-SeMMS) which is designed for real-time applications in conjunction with VPN and also which is based on the session initiation protocol (SIP). Our scheme is to support MVPN in NEMO, so that the session is well maintained while the entire network is moved. Further, in order to reduce the authentication delay time which considers as a delaying factor in hands-off operations, the signaling time which occurs to maintain the session is shortened through proposing the hands-off scheme adopting an authentication method based on HMAC based One Time Password (HOTP). Finally, our simulation results show the improvement of the average hands-off performance time between our proposed scheme and the existing schemes.

• Journal of Construction Engineering and Project Management
• /
• v.7 no.1
• /
• pp.13-25
• /
• 2017

Construction projects have been observed to have problems of project delays and disruptions and the South African construction industry is not an exception. This research identified causes and effects of project delay and disruption through a desktop study. Subsequently, a questionnaire was designed and used to conduct a survey to obtain the views of the three main construction project participants - clients, consultants, and contractors. The questionnaire contains 48 causes and 13 effects of project delay and disruption identified from the desktop study. This research identified sixteen most important causes of project delay and disruption and five most important effects of delay and disruption. Sixteen most important causes were: (1) strikes, (2) rework due to errors during construction, (3) shortage of materials in market, (4) suspension of work by the client, (5) poor communication between the parties, (6) ineffective planning and scheduling of project, (7) delays in issuing working drawings, (8) mistakes and discrepancies in design documents, (9) shortage of labours and equipment, (10) delay in decision making process by the client, (11) unforeseen ground conditions, (12) unclear and inadequate details in drawing, (13) inadequate contractor's experience, (14) delay in approving changes in the scope of works, (15) delay in material delivery and (16) unacceptable quality of materials. The five major effects include: (1) create stress on contractors, (2) cost overrun, (3) time overrun, (4) poor quality of work due to rush, and (5) disputes. Furthermore, the result of this research was compared with the result of previous studies conducted in other regions of Africa in terms of causes and effects of project delay and disruption. The research concludes that numerous causes and effects of delay and disruption are limited to South African construction projects based on the comparison. The causes limited to South African construction projects include: (1) strikes, (2) suspension of work by the client (3) mistakes and discrepancies in design documents (4) delay in approving changes in the scope of works and (5) unacceptable quality of materials, while the two major effects limited to South African construction projects includes: (1) create stress on contractors and (2) poor quality of work. In conclusion, some recommendations were made in order to minimise the causes of delay and disruption identified.

• Korean Journal of Construction Engineering and Management
• /
• v.17 no.4
• /
• pp.95-102
• /
• 2016

Recently, a research regarding calculation of construction time extension-oriented incidental costs has been intensively suggested in quantitative aspect and recent studies on system improvement has been made continuously. In the case of Domestic Public Construction Works, State Contract Act is applied when the client is government whereas Local Government Contract Act is done when the client is local government, but more meticulous study is required because improvement plan is not proposed even there is a clear demand for improvement of these problems on calculation standard. Thus this study suggested appropriate standard by comparing each the calculation standards followed by 'State Contract Act' and 'Local Government Contract Act', considering the problems accorded, and analyzing field cases. Calculation method of other expenses was differently regulated as the revision of each regulation, and this demonstrates that there is a difference of actual cost from 12.37% to 24.95%. It is shown that less cost of construction time were calculated than actual cost according to a problem of calculation method by State Contract Act as the rate at the time of contract to be applied in other expense rate. This study suggested the rate against incidental cost and the rate of other expense per day against total construction cost as an appropriate rate calculation for other expense based on field database.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
• /
• v.41
• /
• pp.135-165
• /
• 2009

It is not difficult to understand from laws and practices in arbitration area that arbitrators appointed have as many rights as their duties to do their performing duties especially to participate in the proceeding and deliberations of the arbitral process. However, sometimes can be happened that an arbitrator who was appointed by a party, refuses to participate in the proceeding or resign during the arbitral process. Generally, in the case, it is provided that the arbitrator who fails to act can be replaced by a substitute arbitrator. When it is decided to change an arbitrator, the appointment of an substitute arbitrator is likely to cause time delay, high cost with inconvenience. And also it is to be considered for additional cost and delay from possible need for repeating the hearings that were held at former arbitral tribunal. Sometimes, a party want to delay intentionally the arbitration process by using right for challenging arbitrator or designing with an arbitrator who was appointed by the party. That is why the reason it has been discussed for allowing the truncated tribunal that the remaining arbitrators that is named as truncated tribunal are permitted to complete the proceeding and issue decisions or arbitral awards. Unfortunately there are uncertain views on the validity of arbitral proceeding or recognitions and enforcement of truncated tribunal decisions in international commercial arbitration. In this article it is focusing on discussing truncated tribunal's benefits or barriers and problems through comparing with famous arbitral rules of international arbitral institutes including rules of UNCITRAL, LCIA, KCAB and the revising draft arbitration rule of UNCITRAL.

• Journal of the Korea Institute of Building Construction
• /
• v.3 no.2
• /
• pp.95-102
• /
• 2003

Financial difficulties and claims frequently stop construction works and cause subsequent contract cancellations. However, as the criteria to assess costs have not been established, many cases of legal disputes over the assessment of cancellation costs are taking place and the concerned parties are suffering the loss of time and money. Therefore, the present research aimed at developing a rational and systematic model of cancellation cost assessment following the cancellation of contracts. The research was carried out in the following methods and scopes. 1 ) The research was focused on the assessment of fair cancellation costs from constructors' side for contracts cancelled by any causes for which the owners have liability. 2) To obtain basic materials about cancellation cost assessment methods, contracts, claims, contract cancellations and construction-related laws at home and abroad were examined. 3) A cost assessment model was developed for systematization and efficient operation of cancellation cost assessment, and the reliability and efficiency of the proposed model was verified through a case study. The conclusions drawn from the research are as follows. The importance of the cancellation cost assessment model was confirmed as, using the cancellation cost assessment model, direct cancellation cost and indirect cancellation cost could be assessed systematically, the number of disputable items could be reduced because reasonable evidences of actual spending were presented, and the loss of constructors could be minimized because systematic and rational cost assessment became possible for many disputable cases of indirect cancellation cost, which the constructors had been unable to prove so far though having spent.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.2
• /
• pp.726-737
• /
• 2017

The use of energy storage systems (ESSs) has become a feasible solution to solve the wind power intermittency issue. However, the use of ESSs increases the system cost significantly. In this paper, an optimal power flow control scheme to minimize the ESS capacity is proposed by using the zero-phase delay low-pass filter which can eliminate the phase delay between the dispatch power and the wind power. In addition, the filter time constant is optimized at the beginning of each dispatching interval to ensure the fluctuation mitigation requirement imposed by the grid code with a minimal ESS capacity. And also, a short-term power dispatch control algorithm is developed suitable for the proposed power dispatch based on the zero-phase delay low-pass filter with the predetermined ESS capacity. In order to verify the effectiveness of the proposed power management approach, case studies are carried out by using a 3-MW wind turbine with real wind speed data measured on Jeju Island.

• International Journal of Advanced Culture Technology
• /
• v.6 no.3
• /
• pp.151-162
• /
• 2018

In deriving the economic order quantity (EOQ) formula, it is tacitly assumed that the buyer has to pay product price while receiving the product from the supplier. However, as a marketing policy, some suppliers permit a delay in payments to the buyers to increase demand for the product they made. Credit transactions would have a positive effect on both suppliers and buyers. For a supplier who offers trade credit, it is an effective means of price differentiation to increase the demand for the product. Availability of opportunity to delay the payment in buyer effectively reduces the cost of holding stocks and therefore, the buyer has a lot of price options to choose his sales price for a customer. Since the buyer's order is affected by the customer's demand, the problems of determining the sales price and EOQ are interdependent and must be solved simultaneously. From this perspective, this paper evaluates the problem of determining the optimal sales price and EOQ for the buyer at the same time when the supplier allows a delay in payments for the product whose demand is represented as a function that decreases linearly with the sales price. For the analysis, it is also assumed that inventory is exhausted not only by customer's but also by decay.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.6
• /
• pp.23-29
• /
• 2011

In some applications of wireless sensor networks, requirements such as energy efficiency, real-time, and reliable delivery need to be considered. In this paper, we propose a novel routing algorithm for wireless sensor networks. It provides real-time, reliable delivery of a packet, while considering energy awareness. In the proposed algorithm, a node estimates the energy cost, delay and reliability of a path to the sink node, based only on information from neighboring nodes. Then, it calculates the probability of selecting a path, using the estimates. When packet forwarding is required, it randomly selects the next node. A path with lower energy cost is likely to be selected, because the probability is inversely proportional to the energy cost to the sink node. To achieve real-time delivery, only paths that may deliver a packet in time are selected. To achieve reliability, it may send a redundant packet via an alternate path, but only if it is a source of a packet. Experimental results show that the proposed algorithm is suitable for providing energy efficient, real-time, reliable communications.