• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.988-996
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• 2012

Assuming perfect channel state information (CSI), the conventional interference alignment (IA) algorithm in the uplink cellular system suppresses inter-cell interference (ICI) by aligning ICI to a randomly selected reference vector. However, IA in practice relies on limited feedback between base stations and users, resulting in residual ICI. In this paper, we propose the optimization of the reference vector that minimizes the upper-bound of residual ICI power. Secondly, the iterative IA that designs the direction of transmit and receive filter is proposed to minimize the residual ICI as well as maximize the desired signals. Moreover, we propose the user scheduling method combined with proposed IA schemes which provides the multiuser diversity gain in multi-cell environments. Finally, the performance gain of the proposed IA algorithms compared with the existing IA are analyzed and demonstrated by simulation results.

• Quality Improvement in Health Care
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• v.4 no.1
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• pp.116-124
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• 1997

Background : As parking problem caused by increasing owner-driver and patients concentrating to a general hospital is becoming one of the dissatisfactions in medical care. It is time that a general hospital should solve the parking problem in a desirable way. The purpose of this survey is to let the clients understand the basic motivation of the pay parking and develop the better parking system. Methods : Clients of a tertiary care hospital in Chon-ju were surveyed by means of a questionnaire. All in all, 193 subjects answered the questionnaire. Results : In relation to previous experiences, 39.6% of the subjects experienced inconvenience with confused parking lot and the shortage of parking space. Under the current parking system, the subjects who felt the available parking space was enough were more than those who didn't 62.7% of the subjects answered that they could find the parking lot easily. 33.2% of the subjects mentioned that it was not easy to drive in the parking area ; The reasons were pointed out the shortage of space, disordered parking, and insufficient guide. 12.8% of the subjects satisfied with the current administering system of parking lot. The outpatients were more affirmative than the admitted patients about the charging system. As for the parking fee, 64% of the subjects answered that it is expensive, and 89.5% of the subjects thought imposing of parking fee is irrational. Conclusion : To say as a whole, the basic purpose of the charging system are more or less accepted. However, the management details like parking facilities and payment method are dissatisfactory, so it is necessary to improve the management system. It is also noted that the inpatients showed more negative attitude than the outpatients with the charging system. To secure a more convenient parking, the parking system should be considered in relation to the information service, kind guidance, improve facilities, personnel cooperation, fix outpatient scheduling system, etc.

• Structural Engineering and Mechanics
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• v.37 no.4
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• pp.427-442
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• 2011

In fatigue life design of mechanical components, uncertainties arising from materials and manufacturing processes should be taken into account for ensuring reliability. A common practice is to apply a safety factor in conjunction with a physics model for evaluating the lifecycle, which most likely relies on the designer's experience. Due to conservative design, predictions are often in disagreement with field observations, which makes it difficult to schedule maintenance. In this paper, the Bayesian technique, which incorporates the field failure data into prior knowledge, is used to obtain a more dependable prediction of fatigue life. The effects of prior knowledge, noise in data, and bias in measurements on the distribution of fatigue life are discussed in detail. By assuming a distribution type of fatigue life, its parameters are identified first, followed by estimating the distribution of fatigue life, which represents the degree of belief of the fatigue life conditional to the observed data. As more data are provided, the values will be updated to reduce the credible interval. The results can be used in various needs such as a risk analysis, reliability based design optimization, maintenance scheduling, or validation of reliability analysis codes. In order to obtain the posterior distribution, the Markov Chain Monte Carlo technique is employed, which is a modern statistical computational method which effectively draws the samples of the given distribution. Field data of turbine components are exploited to illustrate our approach, which counts as a regular inspection of the number of failed blades in a turbine disk.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1495-1504
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• 2013

Renewable energy integration and increased system complexities make system operator maintain supply and demand balance harder than before. To keep the grid frequency in a stable range, an appropriate spinning reserve margin should be procured with consideration of ever-changing system situation, such as demand, wind power output and generator failure. This paper propose a novel concept of dynamic reserve, which arrange different spinning reserve margin depending on time. To investigate the effectiveness of the proposed dynamic reserve, we developed a new short-term reliability criterion that estimates the probability of a spinning reserve shortage events, thus indicating grid frequency stability. Uncertainties of demand forecast error, wind generation forecast error and generator failure have been modeled in probabilistic terms, and the proposed spinning reserve has been applied to generation scheduling. This approach has been tested on the modified IEEE 118-bus system with a wind farm. The results show that the required spinning reserve margin changes depending on the system situation of demand, wind generation and generator failure. Moreover the proposed approach could be utilized even in case of system configuration change, such as wind generation extension.

• KIISE Transactions on Computing Practices
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• v.23 no.12
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• pp.691-697
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• 2017

Volcanic ash has been predicted to be the main source of damage caused by a potential volcanic disaster around Mount Baekdu and the regions of the Korean peninsula. Computer simulations to predict the diffusion of volcanic ash should be performed according to prevalent meteorological situations within a predetermined time. Therefore, a workflow using pipelining is proposed to parallelize the software used for this computation. Due to the nature of volcanic calamities, the simulations need to be carried out for various plausible conditions given that the parameters cannot be precisely determined during the simulations, even at the time of a volcanic eruption. Among the given conditions, computations need to be first performed for the condition with the highest probability so that a response to the volcanic disaster can be provided using these results. Further action can then be performed later based on subsequent results. The computations need to be performed using a volcanic disaster damage prediction system on a computing server with limited computing performance. Hence, an optimal distribution of the computing resources is required. We propose a method through which specific data can be provided first to the proposed pipeline-based workflow.

• Journal of Digital Convergence
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• v.13 no.6
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• pp.185-195
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• 2015

This study aims to study the change in the level of awareness of medical personnels regarding the patient safety culture(PSC) before and after the Leadership WalkRounds(LWR). The LWR in this study was based on the IHI and the models of the Patient Safety Rounds(PSRs) at University of Michigan, emphasizing the 5 steps of Preparation--Scheduling--Conducting--Reporting--Resolving. After the LWR the scores for the level of awareness showed a statistically significant increase from 2.63 to 3.36(p<.001). Among the participants, those who are pharmaceutists, women, 30.0~39.9 years old, or had work experience of a year or less showed particularly notable increase in awareness. The effect was significant across all categories of PSC, especially in Safety Accident Reporting(p<.001), then in Communication(p<.001). Therefore the LWR proved an convergent concept for applying new leadership skill and the concept of patient safety management as an method to elevate the frontline staffs' awareness of PSC.

• Journal of Intelligence and Information Systems
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• v.8 no.1
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• pp.159-173
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• 2002

The goal of this research is to develop of an intelligent injection mold process planning system using Case-Based Reasoning. Injection mold process planning is the planning of manufacturing process to produce an injection mold economically and efficiently. Automation of the process planning is required because the problems of handmade scheduling, the difficulty of training experts for process planning, the lack of domain experts, the spread of CAD/CAM system and flexible manufacturing. This research uses Case-Based Reasoning because the injection mold process planning is devised variously and complicatedly, but the process planning of similar injection molds is very similar to each other. The system that is developed by this research uses cases that are collected in a case base when planning the process of new injection mold. New injection mold process planning is devised by retrieving a case that was made from the most similar injection mold. This research presented and composed the cases of injection mold process planning, and devised a method of search and adaptation, and developed an intelligent injection mold process planning system with the experimental results.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.504-510
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• 2002

As the Scale of construction work is enlarged, complicated and diversified, construction information from the large number of construction sites is happened at site and reported to the head office. To simultaneously control the individual or large number of sites in large number of construction information, the necessity of making extract the important point of the information and the board of director's making a suitable decision to support the fields is increased. Also, as driving the construction industry to be informative, efficiently aggregating the information created in fields, efficiently making decision and controlling the construction work is increased the importance of the company's competitiveness factor. To simultaneously control multi-construction sites in the small and medium size construction firms define the fundamental and core information factor which needed in the head office and suggest the appling method.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.709-716
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• 2005

QoS is an important requirement of the FTTH (Fiber To The Home) subscriber in access network using E-PON (Ethernet Passive Optical Network). In this research, we describe the structure of the access network and propose a bandwidth guarantee scheme for subscriber and service according to the requirements of the subscriber, service and system. This scheme uses two kinds of the classification table, which are called 'service classification table' and 'subscriber classification table.' Using the classification table, we can identify the flow of the subscriber and service. Also, we compute the number of hash table entry to minimize the loss ratio of flows using the M/G/k/k queueing model. Finally, we apply the DRR scheduling through virtual queueing per subscriber instead of the aggregated class.

• KIISE Transactions on Computing Practices
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• v.23 no.10
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• pp.599-604
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• 2017

A useful application of smart assistants is to predict and suggest users' daily behaviors the way real assistants do. Conventional methods to predict behavior have mainly used explicit schedule information logged by a user or extracted from e-mail or SNS data. However, gathering explicit information for smart assistants has limitations, and much of a user's routine behavior is not logged in the first place. In this paper, we suggest a novel approach that combines explicit schedule information with patterns of routine behavior. We propose using inference based on a Markov decision process and learning with a reward function based on inverse reinforcement learning. The results of our experiment shows that the proposed method outperforms comparable models on a life-log dataset collected over six weeks.