• The KIPS Transactions:PartD
• /
• v.16D no.4
• /
• pp.517-526
• /
• 2009

It is possible to indicate the complex design and execution of object-oriented program with dynamic UML diagram. This paper shows the way how to make several test cases from sequence, state, and activity diagram among dynamic UML diagram. Three dynamic UML diagrams about withdrawal work of ATM simulation program are drawn. Then different test cases are created from these diagrams using previously described ways. To evaluate effectiveness of test cases, mutation testing is executed. Mutants are made from MuClipse plug-in tool based on Eclipse which supports many traditional and class mutation operators. Finally we've got the result of mutation testing and compare effectiveness of test cases, etc. Through this document, we've known some hints that how to choose the way of making test cases.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.14 no.1
• /
• pp.57-67
• /
• 2015

A large amount of work has been done in the areas of routing, MAC, QoS, capacity, location service, cooperative communication, fault tolerance, mobility models and various applications of mesh networks thanks to their merits of cost-effective way of deployment and flexibility in extending wireline services. Although multi-path routing protocols have been proposed to be used to provide QoS and fault-tolerance, there has not been any significant results discussed that support both in the literature to our best knowledge as they are often required in military and public safety applications. In this paper, we present a novel routing protocol for a mesh network based on the OFDM-TDMA collision-free MAC that discovers and maintains multiple paths that allows retransmitting and forwarding packets that have been blocked due to a link failure using an alternative next-hop node such that the delay-capacity tradeoff is reduced and the reliability is enhanced. Simulation results show that the proposed protocol performs well in terms of both the QoS and delivery ratio.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.2
• /
• pp.10-16
• /
• 2016

For higher reliability against a link failure of a control network in railway vehicles, a recovery mechanism is needed. We introduce a problem that, when a link failure occurs in a ring-topology control network, a node may experience a significant increase of transmission delay depending on its relative position within the network. We then propose two mechanisms to solve this problem: (1) differentiating and prioritizing node traffic in forwarding; and (2) switching some nodes to a backup bus-topology network. Our simulation study shows that, while the first mechanism achieves a limited gain by only compensating queuing delay, the second one gets a sufficient gain which is impacted by the number of nodes switched to the bus network.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.6
• /
• pp.1056-1063
• /
• 2008

This paper describes an efficient design of a multi-standard Viterbi decoder that supports multiple constraint lengths and code rates. The Viterbi decoder is parameterized for the code rates 1/2, 1/3 and constraint lengths 7,9, thus it has four operation nodes. In order to achieve low hardware complexity and low power, an efficient architecture based on hardware sharing techniques is devised. Also, the optimization of ACCS (Accumulate-Subtract) circuit for the one-point trace-back algorithm reduces its area by about 35% compared to the full parallel ACCS circuit. The parameterized Viterbi decoder core has 79,818 gates and 25,600 bits memory, and the estimated throughput is about 105 Mbps at 70 MHz clock frequency. Also, the simulation results for BER (Bit Error Rate) performance show that the Viterbi decoder has BER of $10^{-4}$ at $E_b/N_o$ of 3.6 dB when it operates with code rate 1/3 and constraints 7.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.6
• /
• pp.1190-1194
• /
• 2007

In sensor network, the importance of transporting data with reliability is growing gradually to support communications. Data flow from sink to nodes needs reliability for the control or management, that is very sensitive and intolerable, however relatively, data flow from nodes to sink is tolerable. In this paper, with emphasis of the data flow from sink to nodes, we proposed the mechanism that establishes confidence interval for transport. Establishing confidence interval herby-hop, not end to end, if errors happen or there's missing data, this mechanism recovers them with selective acknowledgement using fixed window. In addition, this mechanism supports franc congestion control depending on the buffer condition. Through the simulation, we showed that this mechanism has an excellent performance for error recovery in sensor network.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.8
• /
• pp.1596-1603
• /
• 2007

In this paper, we experimented by three kind of method for feature parameter, training method and recognition algorithm of most suitable for speech recognition system and considered. We decided speech recognition system of most suitable through two kind of experiment after we make speech recognizer. First, we did an experiment about three kind of feature parameter to evaluate recognition performance of it in speech recognizer using existent MFCC and MFCC new feature parameter that change characteristic space using PCA and ICA. Second, we experimented recognition performance or HMM, SVM and RVM by studying data number. By an experiment until now, feature parameter by ICA showed performance improvement of average 1.5% than MFCC by high linear discrimination from characteristic space. RVM showed performance improvement of maximum 3.25% than HMM in an experiment by decrease of studying data. As such result, effective method for speech recognition system to propose in this paper derives feature parameters using ICA and un recognition using RVM.

• Journal of Korea Port Economic Association
• /
• v.25 no.3
• /
• pp.1-20
• /
• 2009

A survey to pallet users was conducted in an aspect of the efficiency and benefit. The questionnaire identified the preference about the main variables such as price, size, conformity, material, which are the criteria of the users' choice. staffs in the capital region was selected as respondents and Cluster Analysis and Simulations was carried out with Conjoint Analysis. The result shows that the variables of material and conformity between facilities and products were more important than the variable of size. The respondents prefer the pallets with a various range of products because warehouses should keep a range of products under various condition of temperature. In accordance, the companies that provide a pallet pool service should set up individual marketing strategy by a type of customers so as to maximize the competitiveness in domestic or international markets. Furthermore, supplying standardized pallets should be consistent with the standardization not for individual logistics units, but for whole logistic systems. To achieve this, it requires the compatibility amongst a range of logistics activity participants by their characteristics.

• Journal of the Korea Society of Computer and Information
• /
• v.13 no.5
• /
• pp.219-227
• /
• 2008

As found in research on constraint satisfaction problems, the choice of variable ordering heuristics is crucial for effective solving of constraint optimization problems. For the special problems such as energy-efficient clustering in heterogeneous wireless sensor networks, in which cluster heads have an inclination to be near a base station, we propose a new approach based on the static preferences variable orderings and provide a pnode heuristic algorithm for a specific application. The pnode algorithm selects the next variable with the highest Preference. In our problem, the preference becomes higher when the cluster heads are closer to the optimal region, which can be obtained a Priori due to the characteristic of the problem. Since cluster heads are the most dominant sources of Power consumption in the cluster-based sensor networks, we seek to minimize energy consumption by minimizing the maximum energy dissipation at each cluster heads as well as sensor nodes. Simulation results indicate that the proposed approach is more efficient than other methods for solving constraint optimization problems with static preferences.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.4
• /
• pp.97-103
• /
• 2020

Wireless sensor networks collect and analyze sensing data in a variety of environments without human intervention. The sensor network changes its lifetime depending on routing protocols initially installed. In addition, it is difficult to modify the routing path during operating the network because sensors must consume a lot of energy resource. It is important to measure the network performance through simulation before building the sensor network into the real field. This paper proposes a WSN model for a low-energy adaptive clustering hierarchy protocol using DEVS kernel models. The proposed model is implemented with the sub models (i.e. broadcast model and controlled model) of the kernel model. Experimental results indicate that the broadcast model based WSN model showed lower CPU resource usage and higher message delivery than the broadcast model.

• Journal of Korean Society of Forest Science
• /
• v.110 no.3
• /
• pp.453-461
• /
• 2021

The energy use of forest biomass is crucial to deal with climate change and achieve the carbon-neutral goal. This study aims to analyze the economic feasibility of forest biomass thermal energy facilities and calculate the optimal subsidy level of heat supply to ensure continued operation of the facilities. To achieve this aim, the net present value approach (NPV) and call option price model are adopted considering wood chip price volatilities. The Forest Energy Self-Sufficient Village Project financed by Korea Forest Service is considered as the research case study. In our analysis, when 50% of the initial investment is given to the subsidies and RECs are applied to only power generation, NPV and IRR are both negative and the investment value using the real option model is also zero. We concluded that some heat subsidies should be acknowledged to keep the facilities operating. Besides, the simulation results reveal reliable economic values when the heating subsidy is priced at KRW 0.0248 per kcal.