• Journal of KIISE:Information Networking
• /
• v.30 no.4
• /
• pp.474-483
• /
• 2003

The secret sharing is the basic concept of the threshold cryptosystem and has an important position in the modern cryptography. At 1995, Jarecki proposed the proactive secret sharing to be a solution of existing the mobile adversary and also proposed the share renewal scheme for (k, n) threshold scheme. For n participants in the protocol, his method needs O($n^2$) modular exponentiation per one participant. It is very high computational cost and is not fit for the scalable cryptosystem. In this paper, we propose the efficient share renewal scheme that need only O(n) modular exponentiation per participant. And we prove our scheme is secure if less that ${\frac}\frac{1}{2}n-1$ adversaries exist and they static adversary.

• Tunnel and Underground Space
• /
• v.19 no.3
• /
• pp.167-173
• /
• 2009

Underground storage cavern is known as the most complicated underground project because of the complexity of construction schedule, tunnel size, and geological problems. In order to optimize the construction schedule of underground storage cavern, two up-to-date technologies were applied. The first technology was 3 dimensional visualization of complicated underground structures, and the second was 4 dimensional simulation considering construction resources, geological conditions and construction schedule. This application case shows that we can achieve optimized construction schedule in the ways to optimize the number of work teams, fleets, the sequence of tunnel excavation, the commencement time of excavation and the hauling route of materials and excavated rocks. 3 dimensional modeling can help designer being able to understand the status of complicated underground structures and to investigate the geological data in the exact 3 dimensional space. Moreover, using 4 dimensional simulation, designer is able to determine the bottle neck point which appear during hauling of excavated rocks and to investigate the daily fluctuation in cost.

• Korean Chemical Engineering Research
• /
• v.61 no.2
• /
• pp.217-225
• /
• 2023

2,3-Butanediol (2,3-BDO), which is used in various fields such as cosmetics and fertilizers, is a high value-added substance and the demand for it is gradually increasing. 2,3-BDO produced from the fermentation of microorganisms not only contains by-products of fermentation, but also varies greatly in feed composition depending on fermentation conditions, so it is difficult to efficiently operate the separation process to reach the target purity of the product. Therefore, in this study, through dynamic optimization of the bio-based 2,3-BDO distillation process, the optimal control route was explored to control the 2,3-BDO concentration of the bottom product to 99 wt% or more, when feed concentration changes. Steady and dynamic state process simulation, proportional integral (PI) controller design, and dynamic optimization were sequentially performed. As a result, the error between the 2,3-BDO concentration and the set point of the bottom product was reduced by 75.2%.

• Journal of Korea Society of Industrial Information Systems
• /
• v.28 no.5
• /
• pp.67-75
• /
• 2023

This paper deals with the operation of air taxis, which is one of the latest innovative technologies aimed at solving the issue of traffic congestion in cities. A key challenge for the successful introduction of the technology and efficient operation is a vertiport location problem. This paper employs a discrete choice model to calculate choice probabilities of transportation modes for each route, taking into account factors such as cost and travel time associated with different modes. Based on this probability, a mathematical formulation to maximize the utilization rate for air taxi is proposed. However, the proposed model is NP-hard, effective and efficient solution methodology is required. Compared to previous studies that simply proposed the optimization models, this study presents a solution methodology using the cross-entropy algorithm and confirms the effectiveness and efficiency of the algorith through numerical experiments. In addition to the academic excellence of the algorithm, it suggests that decision-making that considers actual data and air taxi utilization plans can increase the practial usability.

• Journal of Korea Society of Industrial Information Systems
• /
• v.25 no.2
• /
• pp.39-47
• /
• 2020

This paper introduces a novel system-level framework that derives energy efficient electric vehicle (EV) driving speed profile to extend EV driving range without additional cost. This paper first implements an EV power train model considering forces acting on a driving vehicle and motor efficiency. Then, it derivate the minimum-energy driving speed profile for a given driving mission defined by the route. This framework first formulates an optimization problem and uses the dynamic programming algorithm with a weighting factor to derive a speed profile minimizing both of energy consumption and driving time. This paper introduces various weighting factor tracking methods to satisfy the driving time constraint. Simulation results show that runtime of the proposed scaling algorithm is 34% and 50% smaller than those of the binary search algorithm and greedy algorithm, respectively.

• Journal of Korean Society of Transportation
• /
• v.26 no.5
• /
• pp.175-184
• /
• 2008

Uncertainties are unavoidable in engineering applications. In this paper we propose an alpha reliable multi-variable network design problem under demand uncertainty. In order to decide the optimal capacity enhancement, three performance measures based on 3E(Efficiency, Equity, and Environmental) are considered. The objective is to minimize the total budget required to satisfy alpha reliability constraint of total travel time, equity ratio, and total emission, while considering the route choice behavior of network users. The problem is formulated as the chance-constrained model for application of alpha confidence level and solved as a lexicographic optimization problem to consider the multi-variable. A simulation-based genetic algorithm procedure is developed to solve this complex network design problem(NDP). A simple numerical example ispresented to illustrate the features of the proposed NDP model.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.4
• /
• pp.1187-1208
• /
• 2022

One of the main goals of wireless sensor networks (WSNs) is to utilize the energy of sensor nodes effectively and maximize the network lifetime. Thus, this paper proposed a routing protocol for WSNs based on virtual force disturbing mobile Sink node (VFMSR). According to the number of sensor nodes in the cluster, the average energy and the centroid factor of the cluster, a new cluster head (CH) election fitness function was designed. At the same time, a hexagonal fixed-point moving trajectory model with the best radius was constructed, and the virtual force was introduced to interfere with it, so as to avoid the frequent propagation of sink node position information, and reduce the energy consumption of CH. Combined with the improved ant colony algorithm (ACA), the shortest transmission path to Sink node was constructed to reduce the energy consumption of long-distance data transmission of CHs. The simulation results showed that, compared with LEACH, EIP-LEACH, ANT-LEACH and MECA protocols, VFMSR protocol was superior to the existing routing protocols in terms of network energy consumption and network lifetime, and compared with LEACH protocol, the network lifetime was increased by more than three times.

• Journal of Microbiology and Biotechnology
• /
• v.31 no.9
• /
• pp.1305-1310
• /
• 2021

Shikimate is a key high-demand metabolite for synthesizing valuable antiviral drugs, such as the anti-influenza drug, oseltamivir (Tamiflu). Microbial-based strategies for shikimate production have been developed to overcome the unstable and expensive supply of shikimate derived from traditional plant extraction processes. In this study, a microbial cell factory using Corynebacterium glutamicum was designed to overproduce shikimate in a fed-batch culture system. First, the shikimate kinase gene (aroK) responsible for converting shikimate to the next step was disrupted to facilitate the accumulation of shikimate. Several genes encoding the shikimate bypass route, such as dehydroshikimate dehydratase (QsuB), pyruvate kinase (Pyk1), and quinate/shikimate dehydrogenase (QsuD), were disrupted sequentially. An artificial operon containing several shikimate pathway genes, including aroE, aroB, aroF, and aroG were overexpressed to maximize the glucose uptake and intermediate flux. The rationally designed shikimate-overproducing C. glutamicum strain grown in an optimized medium produced approximately 37.3 g/l of shikimate in 7-L fed-batch fermentation. Overall, rational cell factory design and culture process optimization for the microbial-based production of shikimate will play a key role in complementing traditional plant-derived shikimate production processes.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.2
• /
• pp.542-558
• /
• 2016

Vehicular Ad Hoc Networks (VANETs) are self-configuring networks where the nodes are vehicles equipped with wireless communication technologies. In such networks, limitation of signal coverage and fast topology changes impose difficulties to the proper functioning of the routing protocols. Traditional Mobile Ad Hoc Networks (MANET) routing protocols lose their performance, when communicating between vehicles, compromising information exchange. Obviously, most applications critically rely on routing protocols. Thus, in this work, we propose a methodology for investigating the performance of well-established protocols for MANETs in the VANET arena and, at the same time, we introduce a routing protocol, called Genetic Network Protocol (G-NET). It is based in part on Dynamic Source Routing Protocol (DSR) and on the use of Genetic Algorithms (GAs) for maintenance and route optimization. As G-NET update routes periodically, this work investigates its performance compared to DSR and Ad Hoc on demand Distance Vector (AODV). For more realistic simulation of vehicle movement in urban environments, an analysis was performed by using the VanetMobiSim mobility generator and the Network Simulator (NS-3). Experiments were conducted with different number of vehicles and the results show that, despite the increased routing overhead with respect to DSR, G-NET is better than AODV and provides comparable data delivery rate to the other protocols in the analyzed scenarios.

• Korean Journal of Computational Design and Engineering
• /
• v.10 no.1
• /
• pp.40-48
• /
• 2005

A hydraulic hose is an important part of the hydraulic system which transmits power using pressurized fluids. It allows relative motion between components at each end of the hose assembly, and it is much easier to route a hose assembly than it is to bend and install a rigid tubing assembly. Unnecessary loads, which drop the hose's pressure capability and shorten service life, depend on a hose-routing. Therefore, the Hydraulic system designers must be aware to consider unnecessary load does not affect the here. For this consideration in an early stage of the design process, CAD system must support the hose assembly routing design function which is to generate routing path and design fitting angle properly. This paper proposes 2 methods. One is to generate curves that are similar to routing paths of the real hose assembly using the energy minimization method and the optimization method. The other is to design fitting angles that are important design elements of a hose assembly using the Parallel Transport Frame. To implement the proposed methods above, commercial CAD software, CATIA has been integrated with our program.