• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.4
• /
• pp.365-370
• /
• 2012

Most path planning algorithms for a marine robot in the ocean environment have been developed without considering the robot's heading angle. As a result, the robot has a difficulty in following the path correctly. In this paper, we propose a limit-cycle circle set that applies to the $Theta^*$ algorithm. The minimum turning radius of a marine robot is calculated using a limit-cycle circle set, and circles of this radius is used to generate a configuration space of an occupancy grid map. After applying $Theta^*$ to this configuration space, the limit-cycle circle set is also applied to the start and end nodes to find the appropriate path with specified heading angles. The benefit of this algorithm is its fast computation time compared to other 3-D ($x,y,{\theta}$) path planning algorithms, along with the fact that it can be applied to the 3-D kinematic state of the robot. We simulate the proposed algorithm and compare it with 3-D $A^*$ and 3-D $A^*$ with post smoothing algorithms.

• Journal of Korea Game Society
• /
• v.19 no.6
• /
• pp.91-98
• /
• 2019

This study verified the memory occupancy, CPU processing speed, and average frame comparison of texture formats of ASTC and ETC in mobile Android OS. The virtual game scene was implemented as an experimental environment and built on the Android platform. Based on this, comparative verification data was extracted. ASTC has a 36% lower share of memory usage of 2D textures than ETC. CPU processing speed was 18% faster. The average frame confirmed 54 frames that was 58% higher. In the smart mobile game environment, ASTC confirmed the result of comparative advantage over ETC.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.6 no.2
• /
• pp.167-172
• /
• 2006

As ubiquitous devices are fast spreading, the communication problem between humans and these devices is on the rise. The use of context is important in interactive application such as handhold and ubiquitous computing. Context is not crisp data, so it is necessary to introduce the fuzzy concept. The proxity relation is represented by the degree of closeness or similarity between data objects of a scalar domain. A context manager of context-awareness system evaluates imprecise queries with the proximity relations. in this paper, a systematic proximity elicitation method are proposed. The proposed generation method is simple and systematic. It is based on the well-known fuzzy set theory and applicable to the real world applications because it has tuning parameter and weighting factor. The proposed representations of proximity relation is more efficient than the ordinary matrix representation since it reflects some properties of a proximity relation to save space. We show an experiments of quantitative calculate for the proximity relation. And we analyze the time complexity and the space occupancy of the proposed representation method.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2009.04a
• /
• pp.217-221
• /
• 2009

With the increase in individual income and leisure time, those urban residents who want to stay in farmland on weekend are being increased. On the contrary, rural economic situation is getting worse due to the lack of labor and income. For this, as a win-win strategy between urban and rural life, a Kleingarten(below 'KG') has been attracted by local government such as Kyunggi prefecture in Korea. This article exam the situation of KG, a weekend farm where one can stay the night in a log cabin, from the perspective of Multi-habitation. For this purpose, this study surveyed four KG areas; two cases at Yangpyung and Yeonchoen in Korea, the rest are at Kasama and Yachiyo in Japan. The findings are as following. First, a standard regulation for the application and management of users in KG should be established as soon as possible. Second, the exchange between users in KG and local residents around KG should be activated in terms of well organized exchange program. Third, a sufficient budget by public sectors or an economic scheme where private sectors can participate in this program should be arranged. Lastly, a use of post occupancy should be well managed by user themselves in KG and well monitored by supervisor of KG simultaneously.

• Journal of the Korean Institute of Navigation
• /
• v.25 no.1
• /
• pp.23-32
• /
• 2001

This paper treats the berth planning problem which is encountered at public container terminals. The main issue of the berth planning problem is to decide how to allocate the berths to scheduled calling containerships of which the ETA' s are given beforehand. Three optimization models for the berth planning problem are proposed in the formulation of set problems. Some heuristic algorithms for generating the decision variables of the models are also devised by using the concept of the ship's waiting time and the modified berth occupancy rate. Computational experiments based on the data arising from the real public container terminal are also carried out and the results are reported to show that the proposed optimization models and the heuristic algorithms for generating the decision variables are applicable and useful for the berth planning problem at public container terminals.

• Journal of the Korean Institute of Rural Architecture
• /
• v.16 no.1
• /
• pp.53-61
• /
• 2014

The purpose of this study is to analyze present condition and users' behavior on waterfront in local city. To analyze the current physical statues and behavioral issues, 3 cities including Jinju city(Nam river), Ulsan city(Taewha river), and Dae-gu city(Gumho river) has chosen as research areas, the questionnaire and field survey were conducted in research areas focusing on post occupancy evaluation. In this study, it was found that main behaviors of waterfront were rest and exercise and overall satisfactions of waterfront were related to the decision-making for revisitation. However, unsatisfactory physical factors of waterfront were the position and number of facilities related to the behaviors such as rest, exercise, and bicycle riding. Especially, most unsatisfactory factor was the inadequate lighting in respect of intensity of illumination and position although much people had been used each waterfronts at nighttime. In conclusion it was thought that it was necessary to reinforce the program related to culture and leisure such as public performance and to establish infrastructure related to life-time sport and various outdoor exercise for waterfront activation.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.11
• /
• pp.4585-4603
• /
• 2015

Video streaming services make up a large proportion of Internet traffic on both fixed and mobile access throughout the world. Adaptive streaming allows for dynamical adaptation of the bitrate with varying network conditions, to guarantee the best user experience. Adaptive bitrate algorithms face a significant challenge in correctly estimating the throughput as it varies widely over time. In this paper, we first evaluate the throughput estimation techniques and show that the method that we have used offers stable response to throughput fluctuations while maintaining a stable playback buffer. Then, we propose an adaptive bitrate scheme that intelligently selects the video bitrates based on the estimated throughput and buffer occupancy. We show that the proposed scheme improves viewing experience by achieving a high video rate without taking unnecessary risks and by minimizing the frequency of changes in the video quality. Furthermore, we show that it offers a stable response to short-term fluctuations and responds swiftly to large fluctuations. We evaluate our algorithm for both constant bitrate (CBR) and variable bitrate (VBR) video content by taking into account the segment sizes and show that it significantly improves the quality of video streaming.

• Health Policy and Management
• /
• v.10 no.4
• /
• pp.75-98
• /
• 2000

This study applied Data Envelopment Analysis(DEA) and Ratio Analysis and Regression Analysis to a set of Korean Public Corporation Medical Centers to evaluate their relative human resource efficiencies. The output measure used in this study was based on health insurance system which was used in both in-patient departments and out-patient departments. Inputs included working time of the doctors, nurses, technicians, and managerial department staff. Based on the data provided on the inputs and outputs, the analysis showed 23 of the 34 hospitals to be relatively inefficient. Each hospital with an efficiency rating of less than 1 was considered relatively inefficient. In addition, managerial strategies based on dual variables were constructed to indicate the manner In which inefficient hospitals may be made efficient. A subsequent analysis of t-test revealed that the bed occupancy rate, medical revenue per 100beds, value added revenue per staff, medical revenue per staff were statistically significant. The results of this study suggest the DEA is a promising tool for evaluating relative human resource efficiency in hospitals which have multiple inputs and outputs and where the efficient production function is not specifiable with any precision. But it is considered that efficiency evaluations may be most effective]y accomplished by Incorporating a combination of methodologies such as ratio analysis and regression analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.5
• /
• pp.1532-1553
• /
• 2014

Radio spectrum is a precious resource and characterized by fixed allocation policy. However, a large portion of the allocated radio spectrum is underutilized. Conversely, the rapid development of ubiquitous wireless technologies increases the demand for radio spectrum. Cognitive Radio (CR) methodologies have been introduced as a promising approach in detecting the white spaces, allowing the unlicensed users to use the licensed spectrum thus realizing Dynamic Spectrum Access (DSA) in an effective manner. This paper proposes a generalized framework for DSA between the licensed (primary) and unlicensed (secondary) users based on Continuous Time Markov Chain (CTMC) model. We present a spectrum access scheme in the presence of sensing errors based on CTMC which aims to attain optimum spectrum access probabilities for the secondary users. The primary user occupancy is identified by spectrum sensing algorithms and the sensing errors are captured in the form of false alarm and mis-detection. Simulation results show the effectiveness of the proposed spectrum access scheme in terms of the throughput attained by the secondary users, throughput optimization using optimum access probabilities, probability of interference with increasing number of secondary users. The efficacy of the algorithm is analyzed for both imperfect spectrum sensing and perfect spectrum sensing.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2008.04a
• /
• pp.339-344
• /
• 2008

The purpose of this study was to find out the residents' perceptive opinions of apartment housing environment and to contribute to develop a apartment unit plan in Daejeon City. This research was performed by a questionnaire survey method, 464 data was collected from apartment residents lived in about $85m^2$ unit with 3 rooms and the apartments was limited to the complexes within 3 years at Yuseong-gu and Seo-gu. By analyzing those data, findings are as follows: 1) Residents thought living room, kitchen and bathroom were importment space in a unit plan. They needed a storage function in an entrance and a intermediate room, and Anbang(materbed room) so did. L-DK plan type was very preferred. 2) Sub-kitchen was needed for a refrigerator of Kinch, the location of it was realted to a main kitchen and a uitility. the third room was needed for library, home office and storage space. 3) The enlargment remodeling of balcony was showed livingroom balcony or personal bedrooms at the time of occupancy. They needed the balcony near a kitchen or an utility to equip a storage facility. And residents were preferred to their taste rather than a choice of interior concept package services.