• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.283-290
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• 2009

This study focuses on the performance characteristics of polymer electrolyte membrane fuel cell (PEMFC) using the AC impedance technique. The experiment was carried out to investigate the optimal operating conditions of PEMFC such as cell temperature, flow rate, humidified temperature and back-pressure. The fuel cell performance was analyzed by DC electronic-loader with constant voltage mode and expressed by voltage-current density. Additionally, AC impedance was measured to analysis of ohmic and activation loss and expressed by Nyquist plot. The results showed that the cell performance increased with increase of cell temperature, air flow rate, humidified temperature and backpressure. Also, the activation loss decreased as the increase of cell temperature, air flow rate, humidified temperature and backpressure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5A
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• pp.441-450
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• 2006

Recently, with the exponential growth of the number of Internet users, IP traffic which occupies more than 90 percent of the entire Internet traffic affects significantly to the performance of networks. Therefore, the design of the self-similar traffic generator reflected the feature of IP traffic is very important to design the networks efficiently and evaluate the performance of it correctly. In this paper, we design the self-similar traffic generator using OPNET. In order to implement the self-similar characteristics, ON-OFF sources with Pateto distribution are employed and aggregated. The designed self-similarity traffic generator is evaluated and verified with R/S plot, variance time(VT) plot under the various offered loads and the number of sources. It is expected that the designed self-similar traffic generator can be put to practical use when wire or wireless networks is designed and verified as well as it can be useful to decide the specific parameter value for Internet traffic modeling.

• Journal of Ecology and Environment
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• v.33 no.4
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• pp.299-306
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• 2010

The use of local seed provenance is often recommended in forest restoration. Early vigor is a combination of the performance of seed germination and emergence after planting. The ability of young Brant's oak plants to grow and develop after emergence and its dependence on local habitat conditions was investigated in this study. The effects of seed source and shade on early growing seedlings of Brant's oak (Quercus brantii L.) were determined in field measurements. Seeds of Quercus brantii L. were collected from 4 forest areas (seed sources) in southern Zagros (Provinces of Kohkilouyeh-Bouyer Ahmad and Fars) at altitudes of 850, 1,100, 1,500, 2,100 m a.s.l., and planted in a nursery constructed in southwestern Iran. According to a split-plot design consisting of four blocks, each containing two main treatment plots (no shading, partial shading), each main plot was sub-divided into four sub-plots (for elevations of 850, 1,100, 1,500 and 2,100 m). Results showed that shade treatments had significant effects on emergence percentage and rate, shoot length, shoot dry weight (SDW), root dry weight (RDW), leaf area (LA), and chlorophyll content. Ecological factors also had an effect on seed performance. Altitude of seed source had a very significant effect on root length, LA, SDW, and RDW. The seeds collected from 850 m a.s.l. elevation showed the highest performance, especially in leaf area, root length, shoot dry weight, and root dry weight. Our results showed that the altitude of 850 m a.s.l. was the best for collecting Brant's oak seeds.

• Journal of Digital Convergence
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• v.17 no.10
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• pp.169-176
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• 2019

Recently, the Korean economy is congested with Japan's economic retaliation, the US-China trade war, the Bank of Korea's 0.25% base rate cut and Korea's economic growth forecast revision. The purpose of this study is to analyze the KOSPI, CPI, Treasury bonds(3 years) Interest rate & sales performance of all industries, and examine the impact of each index on the KOSPI. The analysis period is from January 2003 to June 2019, and the effect of each index on the KOSPI is analyzed. In numerical analysis, we performed correlation coefficients and regression analysis. In the model analysis, the distribution, quadrant, scatter, box-plot and impulse response were examined. This study examined the volatility and dynamic characteristics of each index. As a result, the KOSPI showed a high correlation with sales and Treasury bonds, but showed a very low correlation with the CPI. The KOSPI will continue to be affected by sales and interest rates.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.421-428
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• 2005

This paper described operation and vibration characteristics of a 'tail-fan' anti-torque performance test system. KARI (Korea Aerospace Research Institute) developed a 'tail-fan' anti-torque system of a helicopter and a performance test-rig to test the performance of the tail-fan. The performance test-rig consists of driving, supporting and rotating parts. In the process of the performance test, firstly, operation test of the test-rig were carried out to verify design specifications. Secondly, natural frequencies of fan blade and test-rig were measured respectively. Lastly, to find the operation rotating speed for the performance test, vibration test were carried out using accelerometers on tail gear box. The performance test conditions of the tail-fan to avoid a resonance were found from the fan-plot and vibration test results. The tail-fan performance tests were well done safely.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1619-1619
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• 2001

Ourwork aims to assess the content of dry matter, protein, cell wall parameters and water soluble carbohydrates in forages without having to handle samples, transport them to a laboratory, dry, grind and chemically analyze them. for this purpose, the concept of fresh forage analysis under field conditions by means of compact integrated NIRS InGaAs-diode array instruments on small plot harvesters is being evaluated for plant breeding trials. This work was performed with the world first commercial experimental forage plot harvester equipped with a NIRS module for the collection, compression, and scanning of forage samples (including automatic referencing and dark current measure ments). It was used for harvesting and analyzing a number of typical forage grass and forage legume plot trials. After NIRS measurements in the field each sample was again analyzed in the laboratory by means of a conventional grating spectrometer equipped with Si-and PbS-detectors. Conventional laboratory analysis of the samples was restricted to dry matter (DM) content by means of oven drying at 105. Routine chemometric procedures were then employed to assess the comparative accuracy and precision of the DM assessments in the spectral range between 950 and 1650nm by the NIRS diode array as well as by the conventional NIRS scanning instrument. The results of this study confirmed that the type of NIRS diode array instrument employed here functioned well even in rugged field operations. further refinements proved to be necessary for optimizing the automatic filling of the sample compartment to adjust for the wide variation in forage material under conditions of extremely low or high harvest yields. The error achieved in calibrating the apparatus for forages of typical DM content proved to be satisfactory (SECV < 1.0). Possibly as a consequence of higher sampling errors, its performance in atypical forages with elevated DM contents was less satisfactory. The error level obtained on the conventional grating NIR spectrometer was similar to that of the diode array instrument for both types of forage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.85-87
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• 2005

This study was conducted to identify the effective dyainage-time influencing rice yield and grain quality on a reclaimed saline soil, the experiment conducted at the Gyehwado substation of the Honam Agricultural Research Institute from 2002 to 2003. The experimental field contained $0.1\%\;and\;0.3\~0.4\%$ NaCl in soil solution, respectively. The experiment involved salinity levels as main plot and sub-plot where consisted of 6 treatments in a split plot design with three replicates. Rice yield performance showed a maximum at drainage-time for 35 days after flowering under medium salinity level, but indicated only $64\%$ of yield level compare to low soil salinity. Percentage of well-shaped rice was high in low soil salinity indicating there aye severe affection for grain quality in medium soil salinity regardless water drainage-time.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.357-357
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• 2017

The combined application of oil cake and rice bran into the soil surface was found useful for weed control in our previous pot study. The present study was undertaken to evaluate the performance of white clover (Trifolium repens L.) while incorporated in the paddy field and effects of combined fertilizer on weed control and rice yield. A plot was divided into two parts i.e. white clover incorporated and not incorporated. The nitrogen content of the incorporated white clover was $12.5gm^{-2}$. Chemical fertilizer and combined fertilizer plots were compared with non-fertilizer conditions. The mixed ratio of combined fertilizer was oil cake 1.35 and rice bran 1.0. Combined fertilizer was applied to the soil surface, and chemical fertilizer was mixed in the soil. Nitrogen application rate was $8gm^{-2}$ for any fertilizer. The weed numbers were significantly reduced in the white clover plot irrespective of application condition both at heading and harvest time. Also, weed control ability was improved by the use of combined fertilizer. In the not incorporated plot, the number of weeds was suppressed about 90% by applying combined fertilizer. The rice yield was markedly increased by the incorporation with white clover under all fertilization conditions. Contribution rates of increased rice yield by white clover and combined fertilizer were about 55% and about 25%, respectively. The rice yield was increased by the incorporation with white clover, and the number of weeds remarkably decreased as well. Also, these effects were improved due to combined application of oil cake and rice bran.

• The Journal of the Korea Contents Association
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• v.19 no.5
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• pp.24-34
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• 2019

This study compares in depth the song performed by two groups, one by 'Seo Taiji And His Boys'(X Generation) and the other by 'BTS'(C Generation) based on the discourse about the 'X Generation' in the 1990s and the 'C Generation' in the 2010s. It will specifically focus on the nature of 'home' that has great significance in the music video and will find the sociocultural meaning of it. Based on the analysis, the original performance by 'Seo Taiji and The Boys' demonstrated the vertical structure of enlightenment and discipline and narrated the story with the plot of 'maturity'. The meaning of 'home' in the original version shifts from a target of resistance to a subject of internalization. The remake music video of BTS demonstrated a horizontal structure of empathy and solidarity and narrated the story with the plot of 'pursuit/discovery'. The 'home' here can be considered the life itself of a person who maintains one's self identity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.977-982
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• 2000

Conventional transistors which have vertical structure show increased parasitic capacitance characteristics in accordance with the increase of non-active base area and collector area. These consequently have disadvantage for high speed switching performance. In this paper, a lateral structure transistor which has minimized parasitic capacitance by using SDB(Silicon Direct Bonding) wafer and oxide sidewall isolation utilizing silicon trench technology is presented. Its structural characteristics are designed by ATHENA(SUPREM4), the process simulator from SILVACO International, and its performance is proven by ATLAS, the device simulator from SILVACO International. The performance of the proposed lateral structure transistor is certified through the V$\_$CE/-I$\_$C/ characteristics curve, h$\_$FE/-I$\_$C/ characteristics, and GP-plot. Cutoff Frequency is 13.7㎓.