• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.20-28
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• 2014

In this paper, based on the characteristics of proportional navigation, a composite guidance law is proposed for impact angle control of passive homing missiles maintaining the lock-on condition of the seeker. The proposed law is composed of two guidance commands: the first command is to keep the look angle constant after converging to the specific look angle of the seeker, and the second is to impact the target with terminal angle constraint and is implemented after satisfying the specific line of sight(LOS) angle. Because the proposed law considers the seeker's filed-of-view(FOV) and acceleration limits simultaneously and requires neither time-to-go estimation nor relative range information, it can be easily applied to passive homing missiles. The performance and characteristics of the proposed law are investigated through nonlinear simulations with various engagement conditions.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.1
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• pp.66-75
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• 2002

For the theoretical performance analysis of Viterbi Decoder for wireless LAN with data rate 12Mbps, code rate 1/2 and constraint length 7 defined in IEEE 802.11a, the transfer function is derived using Cramer's rule and the first-event error probability and bit error probability is derived under the AWGN. In the design process, input symbol is quantized into 16 steps for 4 bit soft decision and register exchange method instead of memory method is proposed for trace back, which enables the majority at the final decision stage. In the implementation, the Viterbi decoder based on parallel architecture with pipelined scheme for processing 12Mbps high speed data rate and AWGN generator are implemented using FPGA chips. And then its performance is verified in real time.

• KSCI Review
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• v.14 no.2
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• pp.147-152
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• 2006

Data size of moving current GIS great exponentially from 2D to 3D and the processing speed becomes slow thereby and user's real time rendering request is growing. Have problem that time and expense to process data of bulky quantity produce constraint condition of the processing speed. third dimension processing skill, virtual reality processing skill etc. and third dimension GIS about space data of bulk much overmuch to materialize. In this paper DEM data that acquire from satellite or aviation solve these problem embody virtual city in web save topography information that visualization to 3D visualization by VRML, and use modelling tool and acquire 3D campus information for building and road. 3D information acquired this to express texture and natural gifts that have truth stuff more to thing through near texture mapping work 3D imagination illustration of web based embody can.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.229-236
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• 2017

An efficient frequent pattern algorithm is essential for mining association rules as well as many other mining tasks for convergence with its application spread over a very broad spectrum. Models for mining pattern have been proposed using a FP-tree for storing compressed information about frequent patterns. In this paper, we propose a centroid frequent pattern growth algorithm which we called "CAWFP-Growth" that enhances he FP-Growth algorithm by making the center of weights and frequencies for the itemsets. Because the conventional constraint of maximum weighted support is not necessary to maintain the downward closure property, it is more likely to reduce the search time and the information loss of the frequent patterns. The experimental results show that the proposed algorithm achieves better performance than other algorithms without scarifying the accuracy and increasing the processing time via the centroid of the items. The MapReduce framework model is provided to handle large amounts of data via a pseudo-distributed computing environment. In addition, the modeling of the proposed algorithm is required in the fully distributed mode.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.4
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• pp.388-398
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• 2002

Video representation through representative frames (key frames) has been addressed frequently as an efficient way of preserving the whole temporal information of sequence with a considerably smaller amount of data. Such compact video representation is suitable for the purpose of video browsing in limited storage or transmission bandwidth environments. In a case like this, the controllability of the total key frame number (i.e. key frame rate) depending on the storage or bandwidth capacity is an important requirement of a key frame selection method. In this paper, we present a sequential key frame selection method when the number of key frames is given as a constraint. It first selects the desired number of initial key frames and determines non-overlapping initial time intervals that are represented by each key frame. Then, it adjusts the positions of key frames and time intervals by iteration, which minimizes the distortion. Experimental result demonstrates the improved performance of our algorithm over the existing approaches.

• Journal of the Korean Data and Information Science Society
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• v.21 no.5
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• pp.853-861
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• 2010

Experimental conditions are set with environmental factors which can affect ship navigation. In FTS simulation, infinite simulation can be theoretically tested with no time constraint but the simulated result with the same experimental condition is repeated due to mathematical model. RTS simulation can give more resonable results but costs at lest 30 minutes for only experimental time. The mixture of two simulation methods using probability density function has been proposed: some of experimental conditions in which ship-handling is most difficult are selected with FTS and are tested in RTS. It has drawback that it does not consider the navigation route but aggregated track index. In this paper, anomaly detection approach is suggested to select some experimental conditions of FTS simulation which are most difficult in ship-handling during the navigation route. An empirical result has been shown.

• Journal of The Korean Astronomical Society
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• v.47 no.6
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• pp.293-302
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• 2014

Simultaneous time monitoring observations of $H_2O$ $6_{16}-5_{23}$, SiO J = 1-0, 2-1, 3-2, and $^{29}SiO$ ${\upsilon}=0$, J = 1-0 lines are carried out in the direction of the Mira variable star TX Cam with the Korean VLBI Network single dish radio telescopes. For the first time, the $H_2O$ maser emission from TX Cam is detected near the stellar velocity at five epochs from April 10, 2013 (${\phi}=3.13$) to June 4, 2014 (${\phi}=3.89$) including minimum optical phases. The intensities of $H_2O$ masers are very weak compared to SiO masers. The variation of peak antenna temperature ratios among SiO ${\upsilon}=1$, J = 1-0, J = 2-1, and J = 3-2 masers is investigated according to their phases. The shift of peak velocities of $H_2O$ and SiO masers with respect to the stellar velocity is also investigated according to observed optical phases. The $H_2O$ maser emission occurs around the stellar velocity during our monitoring interval. On the other hand, the peak velocities of SiO masers show a spread compared to the stellar velocity. The peak velocities of SiO J = 2-1, and J = 3-2 masers show a smaller spread with respect to the stellar velocity than those of SiO J = 1-0 masers. These simultaneous observations of multi-frequencies will provide a good constraint for maser pumping models and a good probe for investigating the stellar atmosphere and envelope according to their different excitation conditions.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.176-183
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• 2011

This paper is intended on providing solutions for overcoming constraints to the transmission of the Important Intangible Cultural Properties related to dance successors. For accommodating this approach, six career dancers, from the Dance Society of the Important Intangible Cultural Properties, were invited as the research participants for this study. The In-Depth Interviews and the classification analysis are used as a way of structuring and understanding my observations about these tasks. These interviews have also been verified by an expert group. In conclusion, this study identifies numerous obstacles which can restrict the transmission of the Important Intangible Cultural Properties are as follows; first, the dance successors are constrained by personal reasons such as physical strength and mutual understanding at home; second, the dance successors are affected by the structural constraint of programs such as required time for the completion of training, efficiency of the training program and the educational environment; third, the dance successors are constrained by personal relations such as the relationship between themselves, or between the dance successors and holders of Important Intangible Cultural Properties. Suggested solutions for overcoming the constraints to training programs are; building small sized training centers throughout the country; making training time realistic for individuals; and making programs to train the dancers as well as making it sociable.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1731-1737
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• 2007

This paper considers subway routing problem. Given a schedule of train to be routed by a railway stock, the routing problem determines a sequence of trains while satisfying turnaround time and maintenance restrictions. Generally, the solution of routing problem is generated from set partition formulation solved by column generation method, a typical integer programming approach for train-set. However, we find the characteristics of metropolitan subway which has a simple rail network, a few end stations and 13 departure-arrival patterns. We reflect a turn-around constraint due to spatial limitations has no existence in conventional railroad. Our objective is to minimize the number of daily train-sets. In this paper, we develop two basic techniques that solve the subway routing problem in a reasonable time. In first stage, we formulate the routing problem as a Min-cost-flow problem. Then, in the second stage, we attempt to normalize the distance covered to each routes and reduce the travel distance using our heuristic approach. Applied to the current daily timetable, we could find the subway routings, which is an approximately 14% improvement on the number of train-sets reducing 15% of maximum traveling distance and 8% of the standard deviation.

• Journal of Energy Engineering
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• v.5 no.1
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• pp.87-92
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• 1996

This paper formulates dynamic optimization model for Time-Of-Use Rates when a electric power system consists of three generators and a rating period is divided into three sub-periods. We use Pontryagin's Maximum Principle to derive optimal price and investment policy. Particularly the cross-price elasticities of demand are considered in the objective function. We get the following results. First, the price is equal to short-run marginal cost when the capacity is sufficient. However, if the capacity constraint is active, the capacity cost is included in the price. Therefore it is equal to the long-run marginal cost. Second, The length of rating period affects allocation of capacity cost for each price. Third, the capacity investment in dynamic optimization is proportional to the demand growth rate of electricity. However the scale of investment is affected by not only its own demand growth rate but also that of other rating period.