• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.45-53
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• 2009

Today, reduction of $CO_2$ exhaustion gas for global-warming prevention becomes important issues in all industrial fields. Hydraulic systems have been widely used in industrial applications due to high power density and so on. However hydraulic pump is always being operated by engine or electric motor in the conventional hydraulic system. Therefore most of the conventional hydraulic system is not efficient system. Recently, an electro-hydraulic hybrid system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. In the electro-hydraulic hybrid system, hydraulic pump is operated by electric motor only when hydraulic power is needed. Therefore the electro-hydraulic system can reduce the energy consumption drastically when compared to the conventional hydraulic systems. This paper presents a new kind of hydraulic load simulator which is composed of electro-hydraulic hybrid system. Disturbances in the real working condition make the control performance decrease or go bad. QFT controller is designed to eliminate or reduce the disturbance and improve the control performance of the electro-hydraulic load simulator. Experimental results show that the proposed controller is verified to apply for electro-hydraulic hybrid system with varied external disturbances.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.8
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• pp.638-651
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• 2000

When the bandwidth resources in a packet-switched network are shared among sessions by MAX-MIN flow control each session is required to transmit its data into the network subject to the MAX-MIN fair rate which is solely determined by network loadings. This passive behavior of sessions if fact can cause seri-ous QoS(Quality of Service) degradation particularly for real-time multimedia sessions such as video since the rate allocated by the network can mismatch with what is demanded by each session for its QoS. In order to alleviate this problem we extend the concept of MAX-MIN fair bandwidth allocations as follows: Individual bandwidth demands are guaranteed if the network can accommodate them and only the residual network band-width is shared in the MAX-MIN fair sense. On the other hand if sum of the individual bandwidth demands exceeds the network capacity the shortage of the bandwidth is shared by all the sessions by reducing each bandwidth guarantee by the MAX-MIN fair division of the shortage. we present a novel flow control algorithm to achieve this extended MAX-MIN fairness and show that this algorithm can be implemented by the existing ATM ABR service protocol with minor changes. We not only analyze the steady state asymptotic stability and convergence rate of the algorithm by appealing to control theories but also verify its practical performance through simulations in a variety of network scenarios.

• Journal of KIISE:Software and Applications
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• v.35 no.8
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• pp.512-521
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• 2008

Web-based information services should be evaluated for accessibility and usability with various types of Internet Web-browsing devices, interacting with web information servers. A reliable ubiquitous Web information server, accessible and usable with a variety of Web-browsing devices (e.g. a full-browsing mobile phone), should be a unified center for personalized ubiquitous Web information services as well as for business models based on personalized advertisements. We studied an estimation of the accessibility and usability in Web interaction for personalized ubiquitous Web information services, as metrics for real-time estimation. We show empirical results based on implementation and experiments in Korea, Japan and China, using a test-bed Web site ('ktrip.net') and single-character Korean domain names (e.g. 김.net, 이.net, 박.net, 최.net, ㄱ.net, ㄴ.net ... ㅎ.net, ㅏ.net, ... ㅔ.net, ㄱ.com, ㄴ.com ... ㅎ.com).

• Quality Improvement in Health Care
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• v.8 no.1
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• pp.56-72
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• 2001

Background : To shorten processing time for variety of medical affairs of the patient at the outpatient clinic of a big hospital is very important to qualify medical care of the patient. Therefore, patient's waiting time for medical examination is often utilized as a strong tool to evaluate patient satisfaction with a medical care provided. We performed this study to investigate factors delaying related with waiting time for medical examination. Methods : The data were collected from June 26 to July 30, 1999. A total 275 case of medical treatment and 5,634 patients who visited outpatient clinics of a tertiary hospital were subjected to evaluate the waiting time. The data were analyzed using frequency, t-test, ANOVA, $X^2$-test by SPSS Windows 7.5 program. Results : The mean patient's waiting time objectively evaluated ($30.9{\pm}33.9$ min) was longer than that subjectively by patient evaluated ($25.1{\pm}26.2$ min). Patient waiting time objectively evaluated was influenced by the starting time of medical examination, consultation hours, patients arriving time etc, as expected. The time discrepancy between two evaluations was influenced by several causative factors. Regarding the degree of patients accepted waiting time with the medical examination is 20 min. Conclusion : The results show that, besides the starting time of medical examination, consultation hours and patients arriving time, influence the patient's subjective evaluation of waiting time for medical examination and his satisfaction related with the service in the big hospital. In order to improve patient satisfaction related with waiting time for medical examination, it will be effective examination rather than to shorten the real processing time within the consultation room.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.2
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• pp.225-230
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• 2017

To generate mechanical movements in one-shot devices such as missiles and space launch vehicles, pyrotechnic mechanical device(PMD) such as pin pullers using pyrotechnic charge has been widely used. Reliability prediction of pin pullers is crucial to successfully execute target missions for the one-shot devices. Because the pin pullers require destructive tests to evaluate their reliability, one would need about 3,000 samples of success to guarantee a reliability of 99.9 % with a confidence level of 95 %. This paper suggests the application of a probit model using the charge amount as a functional parameter for estimation of functional reliability of pin puller. To guarantee target reliability, we propose estimation methods of the lower bound of functional reliability by applying the probit model. Given lower bound of functional reliability, we quantitatively show that the optimum amount of charge increases as the number of samples decreases. Along with a variety of simulations the validity of our new model via real test results is confirmed.

• Information Systems Review
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• v.7 no.1
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• pp.137-152
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• 2005

The mileage program has been one of the most popular royalty and promotion programs in marketing. With the remarkable growth and rapid pervasiveness of information technologies including the Internet, new and a variety of many other applications of mileage system than traditional ones have been observed. The objective of this research is to investigate the rising role of mileage point as a new private electronic money. In an attempt to identify the new role, we employ two factors: monetary confidence and monetary efficiency. This paper analyzes the status quo in the monetary uses of the mileage system by answering to those questions that "is it money?," and "what are the cases for real experiences in 'money-like' mileage and their implications?" with OK Cashbag case. Results show that OK Cashbag point is taking a different development route of money and performs limited monetary functions as private electronic money.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6625-6629
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• 2013

Breast cancer accounts for one third of new cancer cases among women. The need for biomarkers for early detection is the stimulus to researchers to evaluate altered expression of genes in tumours. Cancer-testis (CT) genes are a group with limited expression in normal tissues except testis but up-regulation in a wide variety of cancers. We here evaluated expression of two CT genes named FBXO39 and TDRD4 in 32 invasive ductal carcinoma samples, 10 fibroadenomas and 6 normal breast tissue samples, in addition to two breast cancer cell lines, MCF-7 and MDA-MB-231, by the means of quantitative real time RT-PCR. FBXO39 showed significant up-regulation in invasive ductal carcinoma samples in comparison with normal samples. It also was expressed in both cell lines and after RHOXF1 gene knock down it was down-regulated in MCF-7 but up-regulated in the MDA-MB-231 cell line. TDRD4 was not expressed in the MCF-7 cell line and any of the tissue samples except testis. However, it was expressed in MDA-MB-231 and was up-regulated after RHOXF1 gene knock down. Our results show that FBXO39 but not TDRD4 can be used for cancer detection and if proved to be immunogenic, might be a putative candidate for breast cancer immunotherapy.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.21-26
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• 2016

With the increased desire of TV consumers for interactivity and personalization, IPTV has been rapidly spread in recent years. IPTV can provide a variety of services through hundreds of channels, but the explosion of TV channels makes users even more difficult to find their desired contents. In addition, the channel zapping delay of IPTV is serious due to the limited network bandwidth. To resolve these problems, this paper distinguishes hot and cold channels by exploiting the real-time viewing rate as well as each user's viewing history, and then, maintains hot channels in the hot list, which is searched first during channel navigation and also prefetched to support the preview of channels. Experimental results show that the proposed scheme improves the IPTV channel seek time significantly compared to existing channel seeking interfaces.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.33-43
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• 2011

Recently, advances in mobile communication and location identifying technology of the moving object is evolving. Therefore, the location-based services based on request for service have increased and a variety of the indexing for the position management of moving objects has been studied. Because the index based on Euclidean space are no restriction of movement, it is difficult to apply to the real world. Also, there is additional cost to find adjacent road segments in road networks-based indexing. Existing studies of fixed static objects such as buildings or hospitals are not considered. In this paper, we propose an efficient road networks-based indexing for management of current positions. The proposed indexing partitions road networks by grids and has integrated road connection informations and manage separated extra indexing for fixed static objects. Through the experiment, we show that the proposed indexing based on road networks improves the performance of operation for search or update than existing indexing.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2321-2330
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• 2015

A variety of studies for indoor positioning are now being in progress due to the limit of GPS that becomes obsolete in the room. However, most of them are based on private wireless networks and the situation is difficult to commercialize them since they are expensive in terms of installation and maintenance costs, non-real-time, and not accurate. This paper applies the mark recognition algorithm used in existing augmented reality applications to the indoor vehicle positioning application. It installs floor marks on the ground, performs the perspective transformation on it and decodes the internal data of the mark and, as a result, it obtains an absolute coordinate. Through the geometric analysis, it obtains current position (relative coordinates) of a vehicle away from the mark and the heading direction of the vehicle. The experiment results show that when installing the marks every 5 meter, an error under about 30 cm occurred. In addition, it is also shown that the mark recognition rate is 43.2% of 20 frames per second at the vehicle speed of 20km/h. Thus, it is thought that this idea is commercially valuable.