• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.1
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• pp.19-24
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• 2008

To reduce time-to-market, more and more embedded system developers and system-on-chip designers rely on microprocessor-based design methodology. ARM processor has been a major player in this industry over the last 10 years. However, there are many restrictions on developing embedded software using ARM processor in the early design stage. For those who are not familiar with embedded software development environment or who cannot afford to have an expensive embedded hardware equipment, testing their software on a real ARM hardware platform is a challenging job. To overcome such a problem, we have designed VMA (Virtual ARM Machine), which offers easier testing and debugging environment to ARM based embedded system developers. Major benefits that can be achieved by utilizing a virtual ARM platform are (1) reducing development cost, (2) lowering the entrance barrier for embedded system novices, and (3) making it easier to test and debug embedded software designs. Unlike many other purely software-oriented ARM simulators which are independent of real hardware platforms, VMA is specifically targeted on SYS-Lab 5000 ARM hardware platform, (designed by Libertron, Inc.), which means that VMA imitates behaviors of embedded software as if the software is running on the target embedded hardware as closely as possible. This paper will describe how VMA is designed and how VMA can be used to reduce design time and cost.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.455-460
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• 2006

Currently, the IETF group is working on service differentiation in the Internet. However, in wireless environments such as Ad-hoc networks, where channel conditions are variable and bandwidth is scarce, the Internet differentiated services are suboptimal without lower layers' support. The IEEE 802.11 standard for Wireless LANs is the most widely used WLAN standard today. 1t has a mode of operation that can be used to provide service differentiation, but it has been shown to perform badly. In this paper, we present a new service differentiation scheme for support QoS in the wireless IEEE 802.11, which is based on a multiple queuing system to provide priority of user's flow. We simulate and analyze the performance of our algorithm and compare its performance with the original IEEE 802.11b protocol. Simulation results show that our approach increases overall throughput in the MAC layer.

• Journal of radiological science and technology
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• v.11 no.2
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• pp.3-15
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• 1988

When X-rays were projected into a patient, there occured the phenomena such as penetration, absorption and scattering etc. The penetrating rays were recorded on films as X-ray image used for diagnosis but scattered rays caused the radiation hazard both to the patient, specialist and technicians. The soft tissue includes many organs which are sensitive to the radiation and in may occupy $40{\sim}50%$ of body weight. Therefore X-rays should be carefully projected to the patient and it is strongly recommended to analyse the distribution of X-rays, when ever the patient is exposed to X-rays. In this study, the distribution of X-ray according to the thickness, the radiation field and the tube voltages (kVp) in soft tissue, the following results were obtained: 1. Total transmitted rays which kept the step with X-ray tube voltage (kVp) increased in proportion to the increasing of X-ray tube voltage. 2. The scattered ray rate in the total transmitted ray was not significantly found with X-ray tube voltage. 3. The affecting factors of the scattered ray rate in total transmitted ray were shown through the radiation field and the thickness. 4. The dose of scattered ray by the angle was observed more in direction of primary ray ($0^{\circ}$) and back scattering ($160^{\circ}$) than in direction of $90^{\circ}$. 5. The more the distance from phantom to the patient should be less distribution of scattered ray.

• Journal of radiological science and technology
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• v.3 no.1
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• pp.37-41
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• 1980

In an attempt to provide optimum kVp for four spot films of stomach examinations, we measured experimentally film density and scatter radiation with field size. And to investigate the effect of concentrations in barium sulphite and kVp in spot films of stomach fluoroscopy were carried out and the following results were obained. 1. The entire density of film by field size has the sharpest increase from $10cm^2$ to $100cm^2$, and relatively flattened curve beyond $500cm^2$ in field size. 2. The quantity of scatter radiation reaching an X-ray film depends upon field size: the larger the fields, the more scatter radiation. 3. It is necessary for increasing 3 to 5kVp as for the absence of barium sulphite and 5 to 7 kVp in the case of 20 per cent and 25 per cent in barium sulphite concentrations to produce uniform density in the four spot films for stomach fluoroscopy.

• Journal of Life Science
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• v.5 no.1
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• pp.20-25
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• 1995

기생충감영시 cytokine으로 활성화된 대식세포가 방어기전의 Effector cell로 작용할 때 분비하는 nitric oxide의 양 및 TNF-$\alpha$ 와 IFN-$\gamma$의 분비정도와 nitric oxide와의 상관관계 등을 알아보기 위하여 3종의 흡충류, Fasciola, paragonimus, Schistosma의 조항원 (100mg/ml)을 마우스 복강내에 주사　 후 24시간, 72시간, 9일간격으로 마우스의 대식세포(1X10$^{6}$/ml)를 분리하여 RPMI 배지 (10% FCS 첨가)에서 48시간 배양후 Nitric TNF-$\alpha$ 및 IFN-$\gamma$를 ELISA로 정량하여 다음과 같은 결과를 얻었다. Nitrite 생성정도는 Fasciola 조항원으로 24시간 감작시킨 대식세포에서 가장 높게 나타났으며 (140$\mu$M/ml) Paragonimus 항원군에서는 24시간에 최고치에 달하였다가(34 $\mu$M/ml) 시간이 경과함에 따라 점차 감소하였다. IFN-$\gamma$는 Paragonimus 항원군에서만 대조군에 비해 높았으며 9일경에 최고치를 보였다(475ng/ml). TNF-$\alpha$는 Schistosoma 항원군에서는 nitric oxide의 생성과 분비 양상이 일치하였다. 위의 결과에 의하면, 흡충류항원으로 감작된 마우스 대식세포의 nitric oxide 생성에 영향을 미치는 cytokine의 종류는 흥충류에 따라 차이를 보였으며, 이 중 Paragonimus 항원에 의해서는 IFN-$\gamma$의 분비가 촉진되는 것으로 나타났고, Schistosoma 의 경우에는 TNF-$\alpha$가 nitric oxide의 생성에 관계함을 알 수 있었다.

• Journal of Korean Society for Quality Management
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• v.47 no.2
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• pp.295-314
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• 2019

Purpose: This study aims to investigate the factors affecting productivity performance for Korean SMEs of manufacturing which had obtained the certification of Productivity Management System(PMS) that is a Korean assessment program for enhancing maturity of company's management systems. Methods: The proposed model is based on the PMS model. The valid 759 data registered from 2010 to 2018 year was analyzed using SEM analysis for testing hypotheses. Results: The results are as follows. First, Leadership affects the five core sub-system processes positively, but doesn't a significant Business Performance directly. Secondly, HRM, Customer & Market Analysis, and Process Management excluding Productivity Development and Measurement Analysis and Knowledge Management have a significant effect on Business Performance. Lastly, when examining the mediation effect, Process Development, Customer & Market Analysis, and HRM have indirectly effect between Leadership and Business Performance. Conclusion: This study results suggest not only the role of leadership to improve productivity performance of SME, but also which core processes are focused and differentiated.

• Journal of radiological science and technology
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• v.10 no.1
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• pp.13-23
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• 1987

Author has studied for finding the method of decreasing the radiation dose and increasing diagnostic range in chest X-ray radiography. The study for the added filter thickness from half value layer to 1/8 value layer by decreasing curve and research for the exposure factors, decreasing ratio of radiation dose, ratio of scatter ray and image quality in chest X-ray radiography. The results were as follows: 1. By using the rare earth intensifying screen system at 120 Kvp, the sensitivity is increased by times and the exposure ratio is decreased 0.22 by comparison with the $CaWO_{4}$ intensifying screen system at 80 Kvp. 2. By using Al added filter of 1/8 value layer, the scatter ray is increased more than no filter, But the scatter ray is decreased more in $G_{4}/RxOG$ intensifying system than in LT-II/Rx intensifying system. 3. At 120 Kvp, the image quality value of $G_{4}/RxOG$ system is increased more than LT-II/Rx system compared with slight decreasing image quality value at 80 Kvp. Concluded that by using the added filter could decrease the radiation dose by 1/3 and obtain effective image quality with the added filter at high voltage hard exposure.

• Imaging Science in Dentistry
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• v.40 no.1
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• pp.9-14
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• 2010

Purpose : We evaluated the absorbed doses to the organs and calculated the effective doses when using the digital panoramic radiography. Materials and Methods : The absorbed dose averages in major organs of oral and maxillofacial region were measured using the Dental head phantom (CIRS Co., USA), $^nLi_2B_4O_7$ TLD chip and UD-716AGL dosimeter (Matsushita Electric Industrial Co., JPN) when performing indirect and direct digital panoramic radiography. Effective doses were calculated from correspond to ICRP 2007 recommendations for two panoramic radiography. Results : The absorbed dose average on indirect and direct digital panoramic radiography was highest in parotid glands as measured 1259.6 mGy and 680.7 mGy respectively. Absorbed dose average in another organs were high in order of esophagus, submandibular gland, tongue and thyroid gland on both types of digital panoramic radiography. The absorbed dose average was higher on indirect type than direct one (p<0.05). The effective dose was higher on indirect type than direct one as measured 13.28 mSv and 8.70 mSv respectively. Conclusion : The absorbed doses in salivary gland and oral mucosa were high. However, thyroid gland also demands the attention on radiography due to high tissue weighting factor in spite of the low absorbed dose.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.451-461
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• 1994

For developing countries which are in infant state of data communication services or don`t have their own Packet Switched Public Data Network(PSPDN), we present the strategy to construct the public data communication network, which guarantees the easy diffusion of data communication services, agrees with trends of telecommunication technology, and maximizes the outcomes to investments. With analyzing the characteristics of telecommunication infrastructures and demands of data communication services in a developing country, we show that the introduction of ISDN is the best solution for constructing a public data network. We also suggest aggressive approach to realize the packet switching functions into ISDN switching system and the networking scenario consisting of three graceful steps, based on the evolution of network architectures. Finally we show that the TDX-10 ISDN switching system, which is designed especially for developing countries, is helpful to commence the data communication era.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.1
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• pp.99-107
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• 1991

The purpose of this study was to decide the proper projection angle that could avoid the superimposition of the petrous portion of temporal bone and posterior clinoid process in cephalometric lateral and basal view of the 10 dry skulls and to analyze the reproducibility of a modified Accurad-100 head holder device from Denar Co. and a cephalostat head holder in 30 transcranial radiographs of the dry skull. The results were obtained as follows: The vertical angle was 24.5±4.1° and the horizontal angle was 3.0 ±5.7°. The distances between arbitrary 3 points which were on the TMJ area were as follows: AB 16.76±0.27㎜, BC 8.79±0.18㎜ in the transcranial radiographs using modified Accurad-100 head holder, AB 29.03±0.14㎜, AC 19.95±0.24㎜, BC 10.08±0.07㎜ in the transcranial radiographs using cephalostat.