• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.3
• /
• pp.547-554
• /
• 2005

Ethernet has been given a greater attention recently due to tendency of unifying most of transmission technique to ethernet. This paper studied the design of MAC which contains high layer interface, transmit engine, flow control block, receive engine, reconciliation sublayer, configuration block, statistics block, and XGMll interface block. Performance evaluation was performed using C language for 10cbps ethernet Data Link to design the optimum hardware, then internal FIFO and initial parameters were evaluated. When offered load is $95\%$, the size of the internal FIFO is required 512-word. When offered load is $97\%$, the size of the internal FIFO is required 1024-word. Based on the result of performance evaluation, MAC was designed in VHDL Language and verified using simulator. MAC core that processes 64-bit data, operates at 168.549MHz and hence supports the maximum 10.78Gbps. The designed MAC core is applicable to an area that needs a high-speed data processing of 10Gbps or more.

• Asia pacific journal of information systems
• /
• v.17 no.3
• /
• pp.1-24
• /
• 2007

With the development of information technology (IT), various information systems (IS) such as Web-based systems and mobile systems have appeared utilizing different technologies. However, recent studies on IS use and user satisfaction rarely account for technological differences among IS and environmental characteristics where IS are intended to be used. The purpose of this research is to investigate the determinants of the use of Web-based ticketing systems for cultural activities and to empirically validate their relationships. Environmental psychology suggests that human beings respond to external stimuli from environments with their emotions, and their emotional states influence human actions, e.g., IS use in this research. Applying environmental psychology to the use of Web-based systems in the culture and entertainment industry, we propose that web site characteristics first influence a user's internal state of mind (i.e., flow) and then the flow state influences the IS use. Studies related to the state of flow collectively affirm the key role played by the flow construct in shaping individual attitudes and behaviors toward IS. Users' flow states are captured by their shopping enjoyment, perceived behavioral control, and the level of concentration on the IS use. Referring to social presence theory, we have included such web site characteristics as content quality, context of web site, and community quality. In our research model, a second order construct is utilized to represent web site quality, because flow theory suggests that holistic experiences with web-based systems (rather than individual characteristics of the web site) are important in explaining the IS use. Further, we have included trust as another important factor influencing the IS use since business transactions on the web encompass higher uncertainty comparing to offline transactions. In order to test our hypotheses, we have conducted an online survey which results in 1,141 valid responses in the final sample. The data were collected from respondents who have experiences in Internet ticketing systems. Although it was a convenient sample, the sample represents a wide variety of user demographics. Validity and reliability of the research instrument were tested and research hypotheses were examined using PLS Graph 3.0. The results indicate that web site characteristics significantly influence the level of user concentration, user's enjoyment in shopping, and perceived behavioral control. Further, the use of Internet ticketing systems is influenced by users' flow states and trust in the web channel. User satisfaction is turned out to be affected by the use of Internet ticketing systems. Unlike extant research on the relationship between web site characteristics and its use, our study has found that, in the culture and entertainment industry, the impact of web site characteristics on IS use is mediated by a user's flow state. This finding has a practical implication that web site design should include as many features that enhance shopping enjoyment and concentration. Other practical implications of these findings and future research implications are also discussed.

• Herbal Formula Science
• /
• v.13 no.1
• /
• pp.49-69
• /
• 2005

This Study was designed to investigate the effect of Sunkihwalhyul -Tang extract(SHT) on the change of cerebral hemodynamics [regional cerebral blood flow(rCBF), pial arterial diameter(PAD) and mean arterial blood pressure(MABP)] in normal and cerebral ischemic rats, and further to determine the mechanisms of action of SHT on hemodynamics. In addition, this study was designed to investigate whether SHT inhibits lactate dehydrog enase(LDH) activity in neuronal cells and cytokines production in serum of cerebral ischemic rats. The results were as follows 1. SHT significantly increased rCBF and PAD in a dose-dependent manner, but MABP was not changed by injecting SHT. These results suggest that SHT significantly increases rCBF by dilating PAD. 2. The SHT-induced increase in rCBF was significantly inhibited by pretreatment with indomethacin(IDN, 1 mg/kg, i.p.), an inhibitor of cyclooxygenase and methylene blue(MTB, $10{\mu}g/kg$, i.p.), an inhibitor of guanylate cyclase. 3. The SHT-induced dilation in PAD was significantly inhibited by pretreatment with IDN and MTB. 4. The SHT-induced some increase in MABP was significantly increased by pretreatment with IDN. These results suggest that the mechanism of action of SBT is mediated by guanylate cyclase. 5. Both rCBF and PAD were significantly and stably increased by SHT(10 mg/kg, i.p.) during the period of cerebral reperfusion, which contrasted with the findings of rapid and marked increase in control group. 6. SBH significantly inhibited LDH activity in neuronal cells. These results suggest that SHT prevents the neuronal death. 7. In cytokine production in the senlm drawn from femoral artery 1 hr after middlecerebral arterial occlusion, sample group showed significantly decreased production of IL-1$\beta$ production, decreased production TNF-$\alpha$ and increased Production of IL-10 compared with control group. 8. In cytokine production in the serum drawn femoral artery 1 hr after reperfusion, sample group showed significantly decreased production of IL-1$\beta$ and TNF-$\alpha$ as wellas significantly increased production of IL10 compared with control group. These results suggest that SHT mediated by guanylate cyclase has inhibitive effect on the brain damage by inhibiting LDH activity, IL-1$\beta$ and TNF-$\alpha$ production, and by accelerating IL-10 production. The present author thinks that SHT has an anti-ischemic effects through the improvement of cerebral hemodynamics and inhibitive enects on the brain damage.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.12 no.4
• /
• pp.40-46
• /
• 2016

In order to improve air quality of indoor environment, studies of the underfloor air distribution (UFAD) system for application in buildings are actively in progress based on temperature and air flow distribution. However, although the age of air is the major evaluation parameter, there has been very little study on this parameter for the UFAD system. In this study, we investigated the age of air to reach the air diffuser, which is installed at the bottom of the interior by the UFAD system. Computational fluid dynamics simulations showed no regular pattern to the maximum value of the age of air in accordance with air flow rate and the velocity at air diffuser. These factors can be deduced from air movement by considering that air emitted from air conditioners was rotated according to the bottom shape of the floor, and then, the age of air in the rotation center was increased. The average age of air of internal interior was reduced considerably as the flow velocity at the underfloor air diffuser was increased from 0.5 m/s to 1.0 m/s However, the age of air was not substantially affected with change in the air volume. Moreover, when the flow velocity at the underfloor air diffuser was higher than 1.0 m/s, the age of air showed no significant difference with change in air volume or height of measurement. These results imply that indoor air quality is more substantially influenced by flow velocity than air volume, and the appropriate flow velocity is 1 m/s or more.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.731-736
• /
• 2011

A pneumatic driving solenoid valve operates pneumatic control devices by opening/closing operating flow passage when the command is given by control system for the liquid-propellant feeding system of space launch vehicle. The simulation model of pneumatic driving solenoid valve is designed with AMESim to verify the designs and evaluate the dynamic characteristics and pneumatic behaviors of valve. To validate a valve simulation model, the simulation results of their operating durations of valve by AMESim analysis are compared with the results of experiments. In addition, the results of internal flow simulation with FLUENT are utilized to improve the accuracy of valve-modeling. Using the model, we analyze performance of valve; opening/closing pressure, operating time on various design factors; shape of control valve seat, drainage seat, rate of sealing diameter, volume of control cavity. This study will serve as one of reference guides to enhance the developmental efficiency of ventilation-relief valves with the various operating conditions, which shall be used in Korea Space Launch Vehicle-II.

• Korean Chemical Engineering Research
• /
• v.52 no.5
• /
• pp.592-602
• /
• 2014

In the Integrated Gasification Combined Cycle (IGCC), the stability of the gasifier has strong influences on the rest of the plant as it supplies the feed to the rest of the power generation system. In order to ensure a safe and stable operation of the entrained-flow gasifier and for protection of the gasifier wall from the high internal temperature, the solid slag layer thickness should be regulated tightly but its control is hampered by the lack of on-line measurement for it. In this study, a previously published dynamic simulation model of a Shell-type gasifier is reproduced and two different linear model predictive control strategies are simulated and compared for multivariable control of the entrained-flow gasifier. The first approach is to control a measured secondary variable as a surrogate to the unmeasured slag thickness. The control results of this approach depended strongly on the unmeasured disturbance type. In other words, the slag thickness could not be controlled tightly for a certain type of unmeasured disturbance. The second approach is to estimate the unmeasured slag thickness through the Kalman filter and to use the estimate to predict and control the slag thickness directly. Using the second approach, the slag thickness could be controlled well regardless of the type of unmeasured disturbances.

• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.1
• /
• pp.97-105
• /
• 2005

In order to reduce the uncertainties and improve the air flow field, objective analysis using asynoptic observational data is chosen as a method that enhances the reality of meteorology. In surficial data and their numerical interpolation for improving the interpretation of meteorological components, objective analysis scheme should perform a smooth interpolation, detect and remove the bad data and carry out internal consistency analysis. For objective analysis technique which related to data reliability and error suppression, we carried out two quality control methods. In site quality control, asynoptic observational data at urban area revealed low representation by the complex terrain and buildings. In case of wind field, it was more effective than temperature field when it were interpolated near waterbody data. Many roads, buildings, subways, vehicles are bring about artificial heat which left out of consideration on the simulation of air flow field. Therefore, in temperature field, objective analysis for more effective result was obtained when surficial data were interpolated as many as possible using value quality control rather than the selection of representative site.

• THE JOURNAL OF KOREAN ORIENTAL ONCOLOGY
• /
• v.9 no.1
• /
• pp.15-37
• /
• 2003

Objective: We are aimed to identify anti-tumor effects of Curcuma longa L. on the stomach cancer cells through molecular biologic methods. Material & Methods: We used AGS as human stomach cancer cells obtained from American Type Culture Collection. The boiled extract of Curcuma longa L. $5{\mu}l$ (Sample I), $10{\mu}l$ (Sample II) was treated to cultural media(ml) for 0, 6, 12, 24, 48 hours. We measured the killing effect on stomach cancer cells through Trypan blue exclusion test and the suppressive effect on viability of stomach cancer cells via MTT assay. For identification of its anticancer mechanism, the revelation of Bcl-2, Bcl-XL, and Bax which are genes related to apoptosis using the quantitative RT-PCR, change of mitochondria membrane permeability and membrane potential via flow cytometry, the cycle of cell mitosis, caspase cleavage and annexin V staining were examined. Results: 1. showed significant killing effect on stomach cancer cell than the control group with a time(6 hours later) and density dependent manner, which was statistical significance. 2. Extract of Curcuma longa L. showed suppressive effect on viability of stomach cancer cells that each test groups had more suppressive effects on viability of stomach cancer cells than the control group with a time(6 hours later), which was statistical significance.(p<0.05) 3. In the test about the revelation of genes related to apoptosis, the revelation of Bcl-2 and Bcl-XL decreased with a density manner which was statistical significance. but the revelation of Bax was not changed with statistical significance. 4. Extract of Curcuma longa L. caused apoptosis by decreasing the absorbance of mitochondria with statistical significance, and also induced apoptosis by decreasing the membrane potential of mitochondria. 5. Extract of Curcuma longa L. destructed the cell cycle of cell mitosos. 6. Cell apoptosis was induced by extract of Curcuma longa L. certificated by method of caspase cleavage and annexin V staining. Conclusion: This experiment showed that Curcuma longa L. has anti-tumor effect with statistical significance. This is in vitro experiment and basic experiment on Curcuma longa L.. We hope more progressive research on Curcuma longa L. will go on and its anti-tumor effects will be more practically identified.

• The Journal of Internal Korean Medicine
• /
• v.27 no.2
• /
• pp.379-393
• /
• 2006

Objectives: We are aimed to identify anti-tumor effects of Curcuma aromatics on some kinds of cancer cells through molecular biologic methods. Materials & Methods: We used 4 kinds of cancer cell lines such as lung cancer cells(AS49), cervical cancer cells(HeLa), glioma cancer cells(A172) and prostate cancer cells(PC3). We treated the boiled extract of Curcuma aromatica $5{\mu}g,\;10{\mu}g$ to cultural media(ml) for 24 hours. We measured the cytotoxicitv on 4 kinds of cancer cells through tryphan blue exclusion test and the suppressive effect on viability of 4 kinds of cancer cells via MTT assay. We measured change of mitochondria membrane potential via flow cytometry. The quantitative RT-PCR was used to examine the effect on the revelation of Bcl-2 and Bax which are genes related to apoptosis. We examined the effect on the revelation of Bcl-2 Protein and Bar protein by western blot analysis. Results : In the experiment of tryphan blue exclusion test, the extract of Curcuma aromatica showed more significant killing effect on AS49, HeLa than the control group with density dependent manner, which was statistically significant. In the experiment of MTT assay the extract of Curcuma aromatica showed more suppressive effect on viability of A549, HeLa than the control group with density dependent manner, which was statistically significant. Curcuma aromatica induced apoptosis by decreasing the membrane potential of mitochondria in A549, HeLa. In the experiment of the revelation of genes related to apoptosis, the revelation of Bcl-2 decreased and the revelation of Bax increased in A549, HeLa treated with Curcuma aromatica with dose dependent manner. In the experiment of the revelation of protein related to apoptosis, the protein levels of Bcl-2 decreased and the protein levels of Bax increased in AS49, HeLa treated with Curcuma aromatica with dose dependent manner. Conclusions: From this study, we can infer that Curcuma aromatica has anti-tumor effect on lung cancer cells and uterine carcinoma cells but not on glioma cells and prostate cancer cells.

• The Journal of Internal Korean Medicine
• /
• v.27 no.2
• /
• pp.429-443
• /
• 2006

Objectives : The Purpose of this study was to identify anti-tumor effects of Curcuma longa L. on some kinds of cancer cells through molecular biologic methods. Materials & Methods : We used 4 kinds of cancer cell lines such as glioma cells(A172), cervical cancer cells(HeLa), Prostate cancer cells(PC3), lung cancer cells(A549). We injected the boiled extract of Curcuma longa L. $5{\mu}g,\;10{\mu}g$ to culture media(ml) for 24 hours. We measured the cytotoxic effect on 4 kinds of cancer cells through trypan blue exclusion test and the suppressive effect on viability of 4 kinds of cancer cells via MTT assay. We measured the change of mitochondria membrane potential via flow cytometry. The quantitative RT-PCR was used to examine the effect on the revelation of Bcl-2 and Bax which genes are related to apoptosis. We examined the effect on the revelation of Bcl-2 protein and Bax protein by western blot analysis. Results: 1. Extract of Curcuma longa L. showed significant cytotoxic effect on A172, HeLa, PC3 compared to the control group with density dependent manner. 2. Extract of Curcuma longs L. showed significant suppressive effect on viability of A172, HeLa, PC3 compared to the control group with density dependent manner. 3. Curcuma longs L. induced apoptosis by decreasing the membrane potential of mitochondria in A172, HeLa, PC3. 4. In the test about the revelation of genes related to apoptosis, the revelation of Bcl-2 decreased and the revelation of Bax increased in A172. HeLa, PC3 treated with Curcuma longa L. with density dependent manner. 5. In the test about the revelation of protein related to apoptosis, the protein levels of Bcl-2 decreased and the protein levels of Bax increased in A172, HeLa, PC3 treated with Curcuma longa L. Conclusions: This experiment shewed that Curcuma longs L. has anti-tumor effect on glioma, cervical, Prostate cancer cells except on lung cancer. We hope that anti-tumor effects of Curcuma longa L. will be more Practically identified.