• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.253.2-253.2
• /
• 2014

Micro hollow cathode discharges (MHCDs) are high-pressure, non-equilibrium discharges. Those MHCDs are useful to produce an excimer radiation. A major advantage of excimer sources is their high internal efficiency which may reach values up to 40% when operated under optimum conditions. To produce strong excimer radiation, the optimisation of the discharge conditions however needs a detailed knowledge of the properties of the discharge plasma itself. The electron density and temperature influence the excitation as well as plasma chemistry reactions and the gas temperature plays a major role as a significant energy loss process limiting efficiency of excimer radiation. Most of the recent spectroscopic investigations are focusing on the ultraviolet or vacuum ultraviolet range for direct detection of the excimer. In our experiments we have concentrated on investigating the micro hollow cathodes from the near UV to the near infrared (300~850 nm) to measure the basic plasma parameters using standard plasma diagnostic techniques such as stark broadening for electron density and the relative line intensity method for electron temperature. Finally, the neutral gas temperature was measured by means of the vibrational rotational structures of the second positive system of nitrogen.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.433.1-433.1
• /
• 2014

The research of graphene, a monolayer of carbon atoms with honeycomb lattice structure, has explosively increased after appeared in 2004. As a result, its high transmittance, mobility, thermal conductivity, and outstanding mechanical and chemical stability have been proved. Especially, many researches were executed about the field of transparent electrode highlighting material of substituting the indium tin oxide (ITO). In addition, qualitative and quantitative improvements have been achieved due to many synthesis methods were discovered. Among them, mostly used method is chemical vapour deposition of graphene grown on copper or nickel. The transmittance, mobility, sheet resistance, and other many properties are completely changed according to these two types of synthesis method of graphene. In this research, considering the difference of characteristics as the synthesis method of graphene, what types of graphene should be used and how to use it were studied. The stacked graphene harvested on copper and multi-layer graphene harvested on nickel were compared and analyzed, as a result, the transmittance of 90% and the sheet resistance of $70{\Omega}{\square}$ was showed even though stacked graphene layers were 4 layers. The reason that could bring these results is lowered sheet resistance due to stacked monolayer graphenes. Moreover, light output power of the three stacked graphene spreading layer shows the highest value, but light-emitting diode with multi-layer graphene died out from 12mA due to also its high sheet resistance. Therefore, we need to clarify about what types of graphene and how to use the graphene in use.

• The Korean Journal of Mycology
• /
• v.36 no.2
• /
• pp.116-122
• /
• 2008

Fungal floras were investigated for the lysimeter soil treated with municipal sewage sludge (MSS), pig manure compost (PMC), industrial sewage sludge (ISS), leather processing sludge (LS), and alcohol fermentation processing sludge (FS). Fungal populations were higher in the FS, ISS, LS, or MSS-treated soil than in the chemical fertilizer-treated soil. Isolated fungi from the sewage sludge were identified as Penicillium spp., Gliocladium spp., Acremonium spp., Trichoderma spp., Aspergillus spp., Blastomyces spp., and Phoma spp.

• Korean Journal of Medicinal Crop Science
• /
• v.19 no.1
• /
• pp.31-37
• /
• 2011

Previous work demonstrated that an ethanol extract (HS0608) of a mixture of three medicinal plants of Curcuma longae radix, Phellinus linteus, and Scutellariae radix markedly inhibits $A{\beta}$ (25-35)-induced neurotoxicity. The present study was performed to further verify the neuroprotective effect of HS0608 on oxidative and ischemic cerebral injury using cultured rat cortical neurons and rats. Exposure of cultured cortical neurons to $100\;{\mu}M$ hydrogen peroxide ($H_2O_2$) induced neuronal apoptotic death. At $10-100{\mu}g/ml$, HS0608 inhibited neuronal death, elevation of intracellular calcium concentration ($[Ca^{2+}]_i$), and generation of reactive oxygen species (ROS) induced by $H_2O_2$ in primary cultures of rat cortical neurons. In vivo, HS0608 prevented cerebral ischemic injury induced by 2-h middle cerebral artery occlusion (MCAO) and 24-h reperfusion. The ischemic infarct and edema were significantly reduced in rats that received HS0608 (200 mg/kg). These results suggest that the anti-oxidative properties of HS0608 may be responsible for its neuroprotective effect against focal cerebral ischemic injury and that HS0608 may have a therapeutic role in neurodegenerative diseases such as stroke.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.6A
• /
• pp.676-684
• /
• 2008

In digital video broadcasting-terrestrial (DVB-T), which is the European digital terrestrial television standard, the orthogonal frequency division multiplexing (OFDM) has been adopted for signal transmission. The main reasons using OFDM are to increase the robustness against the frequency selective fading and impulse noise, and to use available bandwidth efficiently. However, channel variation within an OFDM symbol destroys orthogonality between subcarriers, resulting in inter-carrier interference (ICI), which increases an error floor in proportional to maximum Doppler spread. This paper provides an ICI analysis in both time and frequency domains while existing literatures analyze the ICI effects mainly in frequency domain and proposes the algorithms that estimate the channel impulse response and channel variation using least square (LS) algorithm which is the most simple channel estimation technique. And we propose adaptive channel estimation algorithm that estimates the velocity of terminals. The simulation results show that proposed algorithm has similar performance with about 1.5% computational complexity of noise and ICI reduction LS algorithm in low speed environments.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1823-1826
• /
• 2002

The purpose of this experiment was to develope Triggered Vacuum Switch (TVS) for the high voltage and high current. The TVS has an array of rods of alternate polarity in which a fixed gap spacing is maintained between the rods. The cross section of each rod has trapezoidal shape. It consists of electrode, ceramic chamber, getter and trigger. Currently, triggered vacuum switch (TVS) with seal-off has been designed and fabricated at PAL. An experimentation and trigger devices for TVS were designed for testing characteristics of electricity. For making the prototype of TVS, it is developed of fabrication process and fined of electrode material. The fabrication of the TVS is a lot of process which have manufacturing of part, chemical clean, ceramic brazing and metal welding. The fabricated TVS is tested of leak for vacuum, hold-off voltage and conditioning of trigger system. The TVS has pinch-off after it is removed of gas in the TVS and activated of getter in degassing furnace. The prototype TVS tested about 20 kV, 75 kA, 83 ${\mu}s$ with 100 kJ capacitor bank and inductance 5 ${\mu}H$. This paper describes the results of tests and the characteristics of the switch.

• The Korean Journal of Financial Management
• /
• v.21 no.1
• /
• pp.183-204
• /
• 2004

This paper introduces an observable connection structure between stocks in Korean stock market and investigates the formation principles of the observed connection structure between stocks in economic views. Several recent studies have been attempting to explain that the connection structure between stocks is organized by Power-Law distribution, this implies that most stocks have a few links, but only a few stocks have very large number of links. Therefore, we want to investigate the reason about why the connection structure between stocks exhibited by Mantegna's approach is Power-Law distribution. As a result we found that the number of connection between stocks is determined by market factors and specific firm factors among many other factors. In addition, if a stock is more affected by common factors(market) than specific firm factors, the stock has large number of links with other stocks, otherwise more affected by specific firm factors, the stock has a few links.

• The Journal of the Korea Contents Association
• /
• v.7 no.6
• /
• pp.99-106
• /
• 2007

This study aimed at finding out news viewership composition of the major 5 broadcasting companies in Korea and analysing the reasons behind their channel choice as we live in so-called the 'multi-channel era'. To figure out demographic features and channel preferences of viewers, the study focused on the 4 watcher types; channel loyalty type, brief news type, central watcher type and peripheral watcher type. The result shows that most viewers fall into the 'brief new type', which means that there is a close relation between life style changes and TV news-contents viewership. Channel preferences were found to differ according to demographic features of viewers like gender, age and professions.'Central Watcher' type was found to prefer KBS1; 'channel loyalty' type, MBC; 'peripheral watcher', SBS; and 'brief news' type, YTN, while only KBS2 has no distinctive viewership of its own.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.1 no.2
• /
• pp.1-13
• /
• 1998

The objective of this paper is to develop a cartographic model for water tank suitability for small forest fire extinction using GIS. Various digital maps were created using CAD & GIS for Amnam urban park, which is located in Seogu, Pusan city. The park had 4 small water tanks for fire extinction. The developed descriptive cartographic model identified the spatial effects of fire extinction due to the existing facilities. The prescriptive model to enhance spatial effects was developed for the determination and comparison of the effects of forest fire extinction due to the proposed facilities. This paper proved the techniques of GIS and cartographic modelling are significant for the suitability analysis of water tanks for small forest fire extinction.

• Korean Journal of Organic Agriculture
• /
• v.11 no.2
• /
• pp.91-101
• /
• 2003

This study was tried to examine the efficacy of apples that had grown with agro-chemical alternatives in an apple orchard. The chlorophyll content of apple leaves was a little higher in the plot of Charcoal powder, Chitosan, and Peat moss treatment among the other agro-chemical alternatives. On the contrary, the sugar content of apple fruits was higher in the plot of Amino acids, and Green ion calcium treatment, but there was quite a difference among them. Vitamin C content of apple fruits was high at the cell division period. It became lower at the hypertrophic period and then got higher again at the harvest. Vitamin C content was the highest in the chemical fertilizer plot as well. In an apple orchard where agro-chemical alternatives were used only, the commercial grade of ripened apples had declined by 25％, compared to those in customary cultivation. The commercial grade of ripened apples with agricultural chemicals using fertilizers and pesticides was over 90％ with over 250g of its weight in the plot of Charcoal powder, Amino acids, and Vitamin C treatment. Therefore. we guessed the environment-friendly method of cultivation in an apple orchard shall be established by reducing the usage of agricultural chemicals gradually and increasing the agro-chemical alternatives at the same time.