• The Journal of Korean Institute of Communications and Information Sciences
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• 제28권9A호
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• pp.702-709
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• 2003

In this paper, we propose an efficient and QoS-aware MAC scheduling algorithm for Bluetooth, which considers both throughput and delay performance of each Master-Slave pair in scheduling decisions, and thus, attempts to maximize overall performance. The proposed algorithm, MTDPP (Modified Throughput-Delay Priority Policy), makes up for the drawbacks of T-D PP (Throughput-Delay Priority Policy) proposed in [6] and improves the performance. Since Bluetooth employs a master-driven TDD based scheduling algorithm, which is basically operated with the Round Robin policy, many slots may be wasted by POLL or NULL packets when there is no data waiting for transmission in queues. To overcome this link wastage problem, several algorithms have been proposed. Among them, queue state-based priority policy and low power mode-based algorithm can perform with high throughput and reasonable fairness. However, their performances may depend on traffic characteristics, i.e., static or dynamic, and they require additional computational and signaling overheads. In order to tackle such problems, we propose a new scheduling algorithm. Performance of our proposed algorithm is evaluated with respect to throughput and delay. Simulation results show that overall performances can be improved by selecting suitable parameters of our algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제26권12A호
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• pp.2027-2035
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• 2001

In this paper, we present an audio stream delivery using the AMR (Adaptive Multi-Rate) coder that was adopted by ETSI and 3GPP as a standard vocoder for next generation IMT-2000 service in which includes combined sender (FEC) and receiver reconstruction technique in the Internet. By use of the media-specific FEC scheme, the possibility to recover lost packets can be much increased due to the addition of repair data to a main data stream, by which the contents of lost packets can be recovered. The AMR codec is based on the code-excited linear predictive (CELP) coding model. So we use a frame erasure concealment for CELP-based coders. The proposed scheme is evaluated with ITU-T G.729 (CS-ACELP) coder and AMR - 12.2 kbit/s through the SNR (Signal to Noise Ratio) and the MOS (Mean Opinion Score) test. The proposed scheme provides 1.1 higher in Mean Opinion Score value and 5.61 dB higher than AMR - 12.2 kbit/s in terms of SNR in 10% packet loss, and maintains the communicab1e quality speech at frame erasure rates lop to 20%.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제18권5호
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• pp.708-720
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• 1993

The new preventive control mechanisms for traffic management in BISDN/ATM networks can be divided into Connection Admission Control(CAC), Usage Parameter Control (UPC), and Priority Control. Of these mechanism, Usage Parameter Control continuously monitors the parameters admitted in the network's entry point to guarantee quality of service of connections already admitted. Upon detecting traffic that violates the negotiated parameter, it takes the necessary control measures to prevent congestion. Among these traffic control methods, this paper focuses on the Usage Parameter Control method, and proposes and designs GRACE-LB(Guaranteed Rate Acceptance & Control Element-using Leaky Bucket) which improves upon existing UPC models. GRACE-LB modifies the previous LB model by eliminating the cell buffer, dividing the token Pool into two pools, Long-term pool, Short-term pool, and changing the long-term token generating form using 'Cycle Token' into the same bursty form as the traffic source. Through this, GRACE-LB achieves effective control of the Average Bit Rate(ABR) and burst duration of bursty multimedia traffic which previous LB models found difficult to control. Also, since GRACE-LB can e implemented using only simple operations and there are no cell buffers in it, it has the merit of being easily installed at any place.

• The Journal of Korean Association of Computer Education
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• 제11권6호
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• pp.65-76
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• 2008

Since Cyber Home Learning is an e-learning system promoted with policy goals of reducing private tutoring costs, solving gaps among regions, and improving scholastic attainments, preceding researches to verify its effects have been developed of evaluation standards focused on achievement of its policy goals rather than educational goals. The evaluation standards suggested in preceding researches have limitations in clearly reviewing Cyber Home Learning's effects by teaching-learning activities factors and Cyber Home Learning's improvement related to teaching-learning activities. Therefore, an evaluation model capable of analyzing effects of Cyber Home Learning from pedagogical aspect is required. The goal of this paper is to design pedagogical evaluation model according to teaching-learning activities factors and analyze effects of Cyber Home Learning. For the goal, researches from Korea and abroad related to Cyber Home Learning have been examined, pedagogical evaluation model was designed according to teaching-learning activities factors, and the model was then experimented through survey and in-depth interview on students who used Cyber Home Learning. It is expected that results of this paper can be used as a basic data to improve quality of Cyber Home Learning service for teaching-learning activities, and will contribute to establishment of more developmental Cyber Home Learning policy in the future.

• Journal of Korean Academy of Nursing
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• 제16권3호
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• pp.108-122
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• 1986

Changing concepts of health care, are stimulating the demand for health care, thereby orienting society to health care rights to such an extent that they are deemed as fundamental ones inalienable to man. Concomitantly, qualitative as well as quantative improvement is being sought in the nursing service field. Today, efforts are being made in various areas, especially to qualitatively improve nursing services. A second issue concerns proper staffing. It is important to study staffing, in as much as it continues to be the most persistent and critical problem facing hospital nursing administrators today. It involves quantity, quality, and utilization of nursing personnel. A great deal of attention has been focused on this problem since mid 1930's when nursing services began to be felt as an important segment of hospital operation representing the largest single item of hospital budgets. Traditionally, the determination and allocation of nursing personnel resources has relied heavily on gloval approaches which make use of fixed staff-to-patient ratios. It has long been recognized that these ratios are insensitive to variations between institutions and among individual patients. Therefore, the aim of this thesis is to point to the urgent need for the development of methodology and criteria suited to the reality of Korea. The present research selected one place, the W Christian Hospital, and was conducted over a period 10 days from January, and nurses who were them on duty in their unit. The total num-her of patients surveyed was 1,426 and that of 354. The research represents many variables affecting the direct patient care time using the result from the direct observation method, then using a calculation method to estimate the relationship between the patients care time and selected variables in the hospital setting. The amount of direct patient care time varies with many factors, such 89 the patients age. diagnosis and time in hospital. Differences are also found from hospital, clinic to clinic, ward to ward, and even shift to shift. In this research, the calculation method of estimating the required member of nursing staff is obtained by dividing the time of productive patient care activity(with the time of patient care observed), by the sum of the productive time that each the staff can supply, i.e., 360 minutes, which is obtained by deducting the time for personal activities. The results indicate a substantial difference between the time of productive patient care observed directing and the time of the productive patient care estimated using calculating method. If we know accurately the time of the direct patient care on a shift, there required number of staff members calculated if the proper method can be determinded should be able the time of the direct patient care be estimated by the patient classification system, but this research has shown this system to be in accurate in Korea. There are differences in the recommended time of productive patient care and the required number of nursing staff depending upon which method is used. The calculated result is not very accurate, so more research is needed on the patient classification system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.146-170
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• 2017

Joint channel assignment and routing is a well-known problem in multi-radio wireless mesh networks for which optimal configurations is required to optimize the overall throughput and fairness. However, other objectives need to be considered in order to provide a high quality service to network users when it deployed with high traffic dynamic. In this paper, we propose a re-configuration optimization model that optimizes the network throughput in addition to reducing the disruption to the mesh clients' traffic due to the re-configuration process. In this multi-objective optimization model, four objective functions are proposed to be minimized namely maximum link-channel utilization, network average contention, channel re-assignment cost, and re-routing cost. The latter two objectives focus on reducing the re-configuration overhead. This is to reduce the amount of disrupted traffic due to the channel switching and path re-routing resulted from applying the new configuration. In order to adapt to traffic dynamics in the network which might be caused by many factors i.e. users' mobility, a centralized heuristic re-configuration algorithm called State-Aware Joint Routing and Channel Assignment (SA-JRCA) is proposed in this research based on our re-configuration model. The proposed algorithm re-assigns channels to radios and re-configures flows' routes with aim of achieving a tradeoff between maximizing the network throughput and minimizing the re-configuration overhead. The ns-2 simulator is used as simulation tool and various metrics are evaluated. These metrics include channel-link utilization, channel re-assignment cost, re-routing cost, throughput, and delay. Simulation results show the good performance of SA-JRCA in term of packet delivery ratio, aggregated throughput and re-configuration overhead. It also shows higher stability to the traffic variation in comparison with other compared algorithms which suffer from performance degradation when high traffic dynamics is applied.

• Journal of the Korean Society of Food Science and Nutrition
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• 제35권8호
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• pp.990-996
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• 2006

This research was conducted to evaluate the changes in allergenicity of shrimp by physical treatments using competitive indirect enzyme-linked immunosorbent assay (Ci-ELISA). Shrimp was subjected to physical treatments such as high hydrostatic pressure (HHP), sonication, autoclave and microwave. Heat-stable protein (HSP) purified from raw shrimp was used as a major allergen. The binding ability of monoclonal IgG and shrimp-allergic patients' IgE to HSP treated with HHP decreased, increasing the pressure up to 400 MPa. Especially, it became less than 50% at 400 MPa. The binding ability of mAb to HSP treated with sonication (10, 20, 30 and 60 min) decreased with the treated time. Especially, it became less than 60% with the treatment for 60 min. The allergenicity change of HSP treated with autoclave and microwave little decreased. The binding ability of mAb to HSP during the treatment for 20 min became more than 70%. The results suggest that allergenicity of HSP in raw shrimp be more easily lost by HHP or sonication treatment than by autoclave or microwave treatment.

• Journal of Integrative Natural Science
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• 제4권2호
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• pp.149-157
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• 2011

Urbanization of the world's population has given rise to more than 450 cities around the world with populations in excess of 1 million (megacity) and more than 25 so-called metacities with populations over 10 million (Brinkhoff, 2010). The United States today has a total resident population of more than 308,500,000 people, with 81 percent residing in cities and suburbs as of mid - 2005 (UN, 2008). Urban meteorology is the study of the physics, dynamics, and chemistry of the interactions of Earth's atmosphere and the urban built environment, and the provision of meteorological services to the populations and institutions of metropolitan areas. While the details of such services are dependent on the location and the synoptic climatology of each city, there are common themes, such as enhancing quality of life and responding to emergencies. Experience elsewhere (e.g., Shanghai, Helsinki, Tokyo, Seoul, etc.) shows urban meteorological support is a key part of an integrated or multi-hazard warning system that considers the full range of environmental challenges and provides a unified response from municipal leaders. Urban meteorology has come to require much more than observing and forecasting the weather of our cities and metropolitan areas. Forecast improvement as a function of more and better observations of various kinds and as a function of model resolution, larger ensembles, predicted probability distributions; Responses of emergency managers, government officials, and users to improved and probabilistic forecasts; Benefits of improved forecasts in reduction of loss of life, property damage, and other adverse effects. A national initiative to enhance urban meteorological services is a high-priority need for a wide variety of stakeholders, including the general, commerce and industry, and all levels of government. Some of the activities of such an initiative include: conducting basic research and development; prototyping and other activities to enable very--short and short range predictions; supporting and improving productivity and efficiency in commercial and industrial sectors; and urban planning for long term sustainability. In addition urban test-beds are an effective means for developing, testing, and fostering the necessary basic and applied meteorological and socioeconomic research, and transitioning research findings to operations. An extended, multi-year period of continuous effort, punctuated with intensive observing and forecasting periods, is envisioned.

• Journal of The Korean Society of Grassland and Forage Science
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• 제19권4호
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• pp.355-362
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• 1999

This experiment was conducted to evaluated the effect of maturity at harvest and wrap colors on the quality of round baled rye(Secal cereale L.) silage at the forage experimental field, Grassland and Forage Crops Division, National Livestock Research Institute, Suwon in 1998. The experiment was consist of split-plot design with three repications. The main plots were three different harvesting stages : boot, heading, and flowering stages, the subplots were wrap colors : white, black, and light green color. Acid detergent fiber(ADF) and neutral detergent fiber(NDF) of rye silage were increased with delayed harvesting date, but there were no significant differdence among wrap colors. However, average in vitro dry matter digestibility (IVDMD) of rye silage with white color wrap tended to have higher than those of other colors. The silage pH of heading stage was highest (5.12), and that of flowering stage was lowest (4.57) in different harvest stages. Among tested wrap colors, white color wrap resulted on lowest pH than others (p<0.05), but there were no significant difference between black and light green color. Dry matter (DM) content of rye silage were increased as harvest stage progressed (p<0.05). However, DM content of white color was highest among warp colors, but there was signifiant difference (p<0.05). Ammonia-N content of silage harvested at boot stage was the highest in harvest stage, but there was no difference between heading and flowering stages. Among wrap colors tested, ammonia-N content of black color was highest, but there was no significant difference. The number of lactic acid bacteria of white colors was highest in different colors, and that of flowering stage was highest among harvest stage. Acetic and butyric acid contents were decreased as harvest stage progressed, and lactic acid was increased from 6.33 to 7.98%. However, wrap colors did not influence lactic acid concentration. Among different wrap colors, outside temperature of rye silage was affected by air temperature, but effect of inside temperature was minimal. Black color wrap increased inside temperature by $3{\sim}5^{\circ}C$. The results of this study indicate that rye should be harvested for round bale silage after heading stage. The quality of rye silage wrapped white and light green color will increase slightly.

• Journal of the Korean Society of Radiology
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• 제14권3호
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• pp.203-209
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• 2020

The purpose of this study is to assess the mechanical stability and alignment of the patient positioning system (PPS) of Leksell Gamma Knife Perfexion(LGK PFX). The alignment of the PPS of the LGK PFX was evaluated through measurements of the deviation of the coincidence of the Radiological Focus Point(RFP) and the PPS Calibration Center Point(CCP) applying different weights on the couch(0, 50, 60, 70, 80, and 90 kg). In measurements, a service diode test tool with three diode detectors being used biannually at the time of the routine preventive maintenance was used. The test conducted with varying weights on the PPS using the service diode test tool measured the radial deviations for all three collimators 4, 8, and 16 mm and also for three different positions of the PPS. In order to evaluate the alignment of the PPS, the radial deviations of the correspondence of the radiation focus and the LGK calibration center point of multiple beams were averaged using the calibrated service diode test tool at three university hospitals in Busan and Gyeongnam. Looking at the center diode for all collimators 4, 8, and 16 mm without weight on the PPS, and examining the short and long diodes for the 4 mm collimator, the means of the validation difference, i.e., the radial deviation for the setting of 4, 8, and 16 mm collimators for the center diode were respectively measured to 0.058 ± 0.023, 0.079 ± 0.023, and 0.097 ± 0.049 mm, and when the 4 mm collimator was applied to the center diode, the short diode, and the long diode, the average of the radial deviation was respectively 0.058 ± 0.023, 0.078 ± 0.01 and 0.070 ± 0.023 mm. The average of the radial deviations when irradiating 8 and 16 mm collimators on short and long diodes without weight are measured to 0.07 ± 0.003(8 mm sd), 0.153 ± 0.002 mm(16 mm sd) and 0.031 ± 0.014(8 mm ld), 0.175 ± 0.01 mm(16 mm ld) respectively. When various weights of 50 to 90 kg are placed on the PPS, the average of radial deviation when irradiated to the center diode for 4, 8, and 16 mm is 0.061 ± 0.041 to 0.075 ± 0.015, 0.023 ± 0.004 to 0.034 ± 0.003, and 0.158 ± 0.08 to 0.17 ± 0.043 mm, respectively. In addition, in the same situation, when the short diode for 4, 8, and 16 mm was irradiated, the averages of radial deviations were 0.063 ± 0.024 to 0.07 ± 0.017, 0.037 ± 0.006 to 0.059 ± 0.001, and 0.154 ± 0.03 to 0.165 ± 0.07 mm, respectively. In addition, when irradiated on long diode for 4, 8, and 16 mm, the averages of radial deviations were measured to be 0.102 ± 0.029 to 0.124 ± 0.036, 0.035 ± 0.004 to 0.054 ± 0.02, and 0.183 ± 0.092 to 0.202 ± 0.012 mm, respectively. It was confirmed that all the verification results performed were in accordance with the manufacturer's allowable deviation criteria. It was found that weight dependence was negligible as a result of measuring the alignment according to various weights placed on the PPS that mimics the actual treatment environment. In particular, no further adjustment or recalibration of the PPS was required during the verification. It has been confirmed that the verification test of the PPS according to various weights is suitable for normal Quality Assurance of LGK PFX.