• Journal of Energy Engineering
• /
• v.15 no.1 s.45
• /
• pp.52-59
• /
• 2006

This paper examined the conversion of methane to hydrogen and other higher hydrocarbons using dielectric barrier discharge with AC pulse power. Two metal electrodes of a coaxial-type plasma reactor were separated by gas gap and an alumina tube. The inner electrode was located inside the alumina tube. The alumina tube was located inside the stainless steel tube, which was used as the outer electrode. Effect of feed gas composition (methane, oxygen, argon, water and helium), flow rate, applied frequency, input volt-age on methane conversion and product distribution were studied. The major products of plasma chemical reactions were ethylene, ethane, propane, buthane, hydrogen, carbon monoxide and carbon dioxide. The increment of applied voltage and the usage of inert gas as the background (helium and argon) enhanced the selectivity of hydrocarbons and methane conversion. The addition of water in the feed stream enhanced the conversion of methane and yield of hydrogen. Higher voltage leads to higher yield of $C_2H_6,\;C_3H_8,\;C_4H_{10}$ and yield or $C_2H_2\;and\;C_2H_4$ appeared highly in lower voltage.

• Carbon letters
• /
• v.28
• /
• pp.31-37
• /
• 2018

This paper examines a simple one-step and catalyst-free method for synthesizing carbon nanoparticles from aliphatic alcohols and n-hexane with linear molecule formations by using a stable solution plasma process with a bipolar pulse and an external resistor. When the external resistor is adopted, it is observed that the current spikes are dramatically decreased, which induced production of a more stable discharge. Six aliphatic linear alcohols (methanol-hexanol) containing carbon with oxygen sources are studied as possible precursors for the massive production of carbon nanoparticles. Additional study is also carried out with the use of n-hexane containing many carbons without an oxygen source in order to enhance the formation of carbon nanoparticles and to eliminate unwanted oxygen effects. The obtained carbon nanoparticles are characterized with field emission-scanning electron microscopy, energy dispersive X-ray spectroscopy, and Raman spectroscopy. The results show that with increasing carbon ratios in alcohol content, the synthesis rate of carbon nanoparticles is increased, whereas the size of the carbon nanoparticles is decreased. Moreover, the degree of graphitization of the carbon nanoparticles synthesized from 1-hexanol and n-hexane with a high carbon (C)/oxygen (O) ratio and low or no oxygen is observed to be greater than that of the carbon nanoparticles synthesized from the corresponding materials with a low C/O ratio.

• Journal of the Korean Society for Railway
• /
• v.20 no.2
• /
• pp.203-209
• /
• 2017

Research on condition monitoring and diagnosis of power facilities has been conducted to improve the safety and reliability of electric power supply. Although insulation diagnostic techniques for unit equipment such as gas-insulated switchgears and transformers have been developed rapidly, studies on monitoring of cables have only included aspects such as whether defects exist and partial discharge (PD) detection; other characteristics and features have not been discussed. Therefore, this paper dealt with PD characteristics against void sizes and positions, and with defect localization in XLPE cable. Four types of defects with different sizes and positions were simulated and PD pulses were detected using a high frequency current transformer (HFCT) with a frequency range of 150kHz~30MHz. The results showed that the apparent charge increased when the defect was adjacent to the conductor; the pulse count in the negative half of the applied voltage was about 20% higher than that in the positive half. In addition, the defect location was calculated by time-domain reflectometry (TDR) method, it was revealed that the defect could be localized with an error of less than1m in a 50m cable.

• Journal of the Korean Vacuum Society
• /
• v.18 no.1
• /
• pp.54-59
• /
• 2009

We have measured the spatiotemporal behavior for the density of excited Xe atoms in the $1s_5$ metastable states by laser absorption spectroscopy in accordance with various shapes of ITO electrode. The maximum density of excited Xe atoms in the Is5 state in a discharge cell for fish-boned, T-shaped and squared ITO electrodes has been measured to be $3.01{\times}10^{13}\;cm^{-3}$, $2.66{\times}10^{13}\;cm^{-3}$ and $2.06{\times}10^{13}\;cm^{-3}$, respectively. Throughout this experiment, we could understand the influence of the shapes of ITO electrode of micro discharge cell on the high efficiency of AC-PDPs.

• Transactions on Electrical and Electronic Materials
• /
• v.7 no.1
• /
• pp.1-6
• /
• 2006

Hot carrier degradation and roll off characteristics of threshold voltage ($V_{t1}$) on NMOSFETs as I/O transistor are studied as a function of Lightly Doped Drain (LDD) structures. Pocket dose and the combination of Phosphorus (P) and Arsenic (As) dose are applied to control $V_{t1}$ roll off down to the $10\%$ gate length margin. It was seen that the relationship between $V_{t1}$ roll off characteristic and substrate current depends on P dopant dose. For the first time, we found that the n-p-n transistor triggering voltage ($V_{t1}$) depends on drain current, and both $I_{t2}$ and snapback holding voltage ($V_{sp}$) depend on the substrate current by characterization with a transmission line pulse generator. Also it was found that the improved lifetime for hot carrier stress could be obtained by controlling the P dose as loosing the $V_{t1}$ roll off margin. This study suggests that the trade-off characteristic between gate length margin and channel hot carrier (CHC) lifetime in NMOSFETs should be determined by considering Electrostatic Discharge (ESD) characteristic.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.11
• /
• pp.8-12
• /
• 2008

For the reduction of fabrication cost and process time of AC plasma display panel (PDP), indium tin oxide (ITO) layer was patterned as bus electrode using Nd:$YVO_4$ laser. In comparison with the chemically wet etched ITO patterns, laser ablated ITO patterns showed the formation of shoulders and ripple-like structures at the edge of the ITO lines. For the reduction of shoulders and ripple-like structures, pulse repetition rate and scan velocity of laser was changed. In addition, we analyzed a discharge characteristic of PDP test panel to observe how the shoulders and ripple-like structures influence on the PDP. Based on experimental results, the pattern etched at the 500 mm/s and 40 kHz was better than any other condition. From this experiment we could see the possibility of the laser direct patterning for the application to the patterning of ITO in AC-PDP.

• Korean Journal of Adult Nursing
• /
• v.14 no.1
• /
• pp.93-101
• /
• 2002

Using the APCHE III tool, this study was about the factors related to the death of ICU-patients. From 1999. 12. 1 to 2000. 9. 30, the 284 patients admitted to ICU at P university who were over 15 years of age were selected for the subjets. The data was analyzed through SPSS WIN program for frequency, percentile, $x^2$-test, t-test and logistic regression. The results are summarized as follows: 1) Of the 284 patients, 88died. The mortality is 31.0 percent. The average APACHE III point was $48.62{\pm}32.32$. The average point of non-survivors was higher than that of survivors. 2) There are the significant difference between APACHE III marks and mortality. The mortality rate were over 50 percent 60 points of the mark. When the marks were over 100 points, the mortality were over 90 percent. Below 40 points, the mortality was below 10 percent. Among the variables in the APACHE III, the most significant variables in explaining death were neurologic abnormalities, pulse, $PaO_2$/$AaDO_2$, creatinine, sodium, glucose, chronic health state and age. According to the variables, the models explained the 42.43 percent of the variance in patient's death. In conclusion, the APACHE III tool can be used to predict the progress of ICU patients, and can also be used for the selection of patients for ICU admission/discharge criteria.

• Journal of the Korean Vacuum Society
• /
• v.15 no.1
• /
• pp.57-63
• /
• 2006

We have examined the electrical and optical characteristics of the plasma display panel(PDP) produced by vacuum in-line sealing technology. We found that the luminous efficiency was decreased as the base vacuum level was increased. For the base vacuum level of $1\times10^{-3}$ Torr, the firing voltage was 235V at the discharge gas pressure of 400 Torr and the luminous efficiency was 0.8 lm/W at 180V sustaining pulse. However, for the base vacuum level of $1\times10^{-6}$ Torr, the firing voltage was reduced to 215V and the luminous efficiency was improved to 2.5lm/w. Finally, we demonstrated successfully the operation of tip-less PDP fabricated using vacuum in-line sealing method.

• Korean Journal of Oriental Medicine
• /
• v.16 no.3
• /
• pp.53-66
• /
• 2010

This study focuses on the contents about the Urinalysis which is the most representative one of the Tibetan medicine. Also, this study compares it with the Urinalysis of Traditional Korean medicine. This study focuses on the simple history, the theoretical system, the diagnosis and the urinalysis mainly based on the documents related to the Tibetan medicine. Also, through the comparison with the contents of textbook of Traditional Korean Medicine and the urinalysis shown in the Dongeuibogam(東醫寶鑑) which is the representative Korean medical book, the difference between Tibetan Medicine and Traditional Korean Medicine will be observed. The contents related about the urinalysis of the Tibetan medicine are more specific than those of Traditional Korean Medicine. By observing the color, scent, vapor and sediment of one's urine together with periodic changes more thoroughly, it is possible to find out the cause of a certain disease. However, Traditional Korean Medicine examines the medical conditions mainly based on the state of discharge and fever, showing a clear difference. The Tibetan medicine has an extremely specific type of urinalysis in comparison with that of Traditional Korean Medicine. It is the only characteristic of the Tibet medicine, which cannot be found in any other traditional medicine. By applying the viewpoint of the doctor who diagnoses the patient by measuring his or her pulse, it is possible to make the diagnosing process more specific and accurate. It is expected that the follow-up study will be continuously executed with the introduction of the system for the urinalysis of the Tibetan medicine to Traditional Korean medicine.

• Journal of Korean Public Health Nursing
• /
• v.4 no.2
• /
• pp.15-23
• /
• 1990

This study was carried out to explore the illness-related activities of the menopaused women. To achieve such a purpose, sixty-six cases of the middle aged women were sampled the naturally and the artificially menopaused group respectively from 1st, Aug. to 31th, Aug. in 1988. For the collection of data, 1, 140 women aged between 45-54 were selected through stratified sampling techniques in urban and rural area. Among them the final subjects for analysis were restricted to only those who had experienced menopause naturally or artificially. And then, after control for age and education analysis was performed. The data was analysed by use of frequency, percentage, $X^2-test,$ t-test, Pearson correlation coefficiency and stop-wise multiple regression. The obtained results were as follows. I. As for the se1f-perception on menopausal symptoms, it was revealed than Korean women, neithe in naturally and artificially, accepted the change of menstruation itself as serious. This shows us that middle-aged women had positively receptive attitudes that the change of menstruation is follwed by amenorrhea. 2. The artificially menopaused group scored more than the naturally one: (I) on the self-control activities such as self-assessment, lay-consultation, fever check, pulse check and observation of vagina discharge, (2) on the self-decision activities such as hospital and pharmacy utilization, (3) on the self maintenance activities such as walking, aerobic, weight check, skin care, skin protect, calori control diet control, milk intake, vegetable intake, cold water drinking before meal, parasol use and BP check The above results lead us that the self care practices of the menopaused women revealed' coping wit I menopausal symptoms at the first level in community and must be developed by the adequate nursin intervention.