• Journal of the Semiconductor & Display Technology
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• v.4 no.4 s.13
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• pp.19-26
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• 2005

The process optimization of ozone concentration and half life time was investigated in ultra pure water and alkaline solutions for the wet cleaning of silicon wafer surface at room temperature. In the ultra pure water,. the maximum concentration (35 ppm) of ozone was measured at oxygen flow rate of 3 liters/min and ozone generator power over 60%. The half life time of ozone increased at lower power of ozone generator. Additive gases such as $N_2$ and $CO_2$ were added to increase the concentration and half life time of ozone. Although the maximum ozone concentration was higher with the addition of $N_2$ gas, a longer half life time was observed with the addition of $CO_2$. When $NH_4OH$ of 0.05 or 0.10 vol% was added in DI water, the pH of the solution was around 10. The addition of ozone resulted in the half life time less than 1 min. In order to maintain high pH and ozone concentration, ozone was continuously supplied in 0.05 vol% ammonia solutions. 3 ppm of ozone was dissolved in ammonia solutions. The static contact angle of silicon wafer surface became hydrophilic. The particle removal was possible alkaline ozone solutions. The organic contamination can be removed by ozonated ultra pure water and then alkaline solution containing ozone can remove the particles on silicon surface at room temperature.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.811-817
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• 2002

Korean traditional soy sauce was desalted using electrodialyzer, and their physicochemical properties were analyzed. The salt content of soy sauce significantly decreased from initial 18.9 (w/v) to 0.47% (w/v) and the volume also decreased to 330 mL when 1,000 mL of soy sauce was desalted for 450 min at a current of 2 A. During the desalting process, the numbers of viable cells of total bacteria, yeasts, and molds increased due to the concentration effect of the electrodialysis. Turbidity increased from 3.1 to 8.5, and total nitrogen, total sugar, and reducing sugar contents also increased. The pH, and amino nitrogen and volatile base nitrogen contents slightly decreased, with ammonia content significantly decreasing from 19.4 to $1.3\;{\mu}mol/mL$. Free amino acids content increased twofold after electrodialysis. Gas chromatograms of soy sauce showed that profiles of the flavoring compounds did not change when electrodialyzed for 360 min, but most were removed after 540 min.

• Food Science and Preservation
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• v.20 no.1
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• pp.7-13
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• 2013

Mushrooms have a shorter shelf-life than most vegetables because of their very high respiration rates, sensitivity to enzymatic browning and susceptibility to microbial spoilage. This study was conducted to investigate effects of various packaging materials and precooling on the quality of mushrooms (Agaricus bisporus). Mushrooms were precooled at $4^{\circ}C$ for three hours and packaged using the following packaging materials; 1) polyethylene (PE) film bags of 0.03 mm thickness, 2) polypropylene (PP) film bags of 0.03 mm thickness, and 3) polystyrene (PS) tray+polyvinyl chloride (PVC) wrapper. The physiological changes (weight loss, gas composition, color, firmness, and sensory evaluation) associated with postharvest deterioration were monitored for 17 days at $10^{\circ}C$. The results showed that the PP film bag maintained quality of mushrooms most effectively, especially PP film bags inhibited decreasing firmness. The samples also exhibited smaller decreases in weight loss rate (0.57%) and Hunter L value (84.44) than PS tray+PVC wrapper (7.73%, 82.19) and PE film bags (0.89%, 82.96). Sensory evaluation level in all samples remained relatively constant during the first 5 days of storage. However, PE film bags and PS tray+PVC wrapper showed lower score of flavor, texture and color than PP film bags after 8 days of storage. This study suggested that PP film bag packaging effectively extends shelf-life of mushrooms during storage.

• Food Science and Preservation
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• v.20 no.2
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• pp.173-181
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• 2013

This study investigated that anti-browning effects of Atractylodis Rhizoma Alba extract and L-cysteine combination. Mushrooms were dipped in solutions (0.1% Atractylodis Rhizoma Alba extract containing 0.05% L-cysteine) for 3 min. The dipped mushrooms were packaged in a polystyrene (PS) tray and wrapped with a polyvinyl chloride (PVC) film, and stored for 14 days at $10^{\circ}C$. The browning inhibition activity (Hunter L, a, b color scale and tyrosinase inhibition activity) and quality changes (weight loss rate, gas composition, firmness and sensory evaluation) were analyzed during storage period. After 14 days, the Hunter L and ${\Delta}E$ value of mushrooms treated in 0.1% Atractylodis Rhizoma Alba extract containing 0.05% L-cysteine were 87.24 and 5.56, respectively. The mushrooms treated with 0.1% Atractylodis Rhizoma Alba extract containing 0.05% L-cysteine also showed higher firmness (13.31 N) and smaller weight loss rate (2.87%) than the untreated mushroom (11.42 N, 3.04%) on storage day 14. During storage period, the sensory evaluation showed that overall acceptability of mushrooms treated with 0.1% Atractylodis Rhizoma Alba extract containing 0.05% L-cysteine were higher than those of the untreated mushrooms, except those that were stored for five days. Overall, the mushrooms treated with 0.1% Atractylodis Rhizoma Alba extract containing 0.05% L-cysteine had a higher tyrosinase inhibition activity than the untreated mushrooms during storage period. This study suggests that the browning of the mushrooms treated with 0.1% Atractylodis Rhizoma Alba extract containing 0.05% L-cysteine solution were inhibited, and the that their shelf life was extended.

• Journal of the Korean Vacuum Society
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• v.15 no.6
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• pp.612-618
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• 2006

Surface modification of PTFE by ion irradiation was performed to improve its surface properties, In the case where argon was used to irradiate the PTFE films, an increase in the adhesion strength was observed when the ion fluence was over $1\times10^{15}\;ions/cm^2$, but the surface morphology dramatically changed to a needle-shaped one. However, when we used hydrogen ions under $O_2$ environmental gas, the adhesion strength increased at an ion fluence of $5\times10^{16}\;ions/cm^2$ and the surface morphology by the hydrogen irradiation was not needle-shaped. The surface morphology and adhesion strength of the hydrogen modified PTFE was influenced by the oxygen flow rate. It was confirmed by reflectance measurements that the surface properties of the hydrogen ion irradiated PTFE were superior to those of the argon ion irradiated PTFE.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.220-220
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• 2013

Surface-normal transmission electro-absorption modulator (EAM) are attractive for high-definition (HD) three-dimensional (3D) imaging application due to its features such as small system volume and simple epitaxial structure [1,2]. However, EAM in order to be used for HD 3D imaging system requires uniform modulation performance over large area. To achieve highly uniform modulation performance of EAM at the operating wavelength of 850 nm, it is extremely important to remove the GaAs substrate over large area since GaAs material has high absorption coefficient below 870 nm which corresponds to band-edge energy of GaAs (1.424 eV). In this study, we propose and experimentally demonstrate a transmission EAM in which highly selective backside etching methods which include lapping, dry etching and wet etching is carried out to remove the GaAs substrate for achieving highly uniform modulation performance. First, lapping process on GaAs substrate was carried out for different lapping speeds (5 rpm, 7 rpm, 10 rpm) and the thickness was measured over different areas of surface. For a lapping speed of 5 rpm, a highly uniform surface over a large area ($2{\times}1\;mm^2$) was obtained. Second, optimization of inductive coupled plasma-reactive ion etching (ICP-RIE) was carried out to achieve anisotropy and high etch rate. The dry etching carried out using a gas mixture of SiCl4 and Ar, each having a flow rate of 10 sccm and 40 sccm, respectively with an RF power of 50 W, ICP power of 400 W and chamber pressure of 2 mTorr was the optimum etching condition. Last, the rest of GaAs substrate was successfully removed by highly selective backside wet etching with pH adjusted solution of citric acid and hydrogen peroxide. Citric acid/hydrogen peroxide etching solution having a volume ratio of 5:1 was the best etching condition which provides not only high selectivity of 235:1 between GaAs and AlAs but also good etching profile [3]. The fabricated transmission EAM array have an amplitude modulation of more than 50% at the bias voltage of -9 V and maintains high uniformity of >90% over large area ($2{\times}1\;mm^2$). These results show that the fabricated transmission EAM with substrate removed is an excellent candidate to be used as an optical shutter for HD 3D imaging application.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1207-1213
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• 2011

This study was conducted to assess $N_2O$ emissions in agricultural soils of Korea. According to 1996 and 2006 IPCC (Intergovernmental Panel on Climate Change) methodology, $N_2O$ emission was calculated the sum of direct emission ($N_2O_{DIRECT}$) and indirect emission ($N_2O_{INDIRECT}$). To calculate $N_2O$ emissions, emission factor was used default of IPCC and activity data was used the food, agricultural, forestry and fisheries statistical yearbook of MIFAFF (Ministry for Food, Agriculture, Forestry and Fisheries). It was emitted 8,608 $N_2O$ Mg resulted from direct emission by application of chemical fertilizer and animal manure, input in n-fixation crops and input of crop residues and emissions converted $N_2O$ into $CO_2$ equivalent was 2,668 $CO_2$-eq Gg. Indirect emission as $N_2O_{(G)}$ (atmospheric deposition of $NH_3$ and $NO_X$) and $N_2O_{(L)}$ (leaching and runoffs) were 4,567 and 6,013 $N_2O$ Mg and emissions converted $N_2O$ into $CO_2$ equivalent were 1,416 and 1,864 $CO_2$-eq Gg, respectively. Total $N_2O$ emission in Korea agricultural soil in 2009 was 5,948 $CO_2$-eq Gg.

• Food Engineering Progress
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• v.13 no.1
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• pp.38-43
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• 2009

In this research, the contents of capsaicin and dihydrocapsaicin in various species of red pepper produced in the Goesan-gun County were determined by GC-MS. Further, the contents of capsaicin and dihydrocapsaicin in powdered red pepper products with very hot, hot, normal and mild taste were analyzed to present the degree of hot taste in their products based on contents of capsaicin. The contents of capsaicin in each species of red pepper were from 25.18 mg%(Daetong) to 123.62 mg%(Cheongyang). In the powdered red pepper sold in the market, the contents (mg%) of capsaicin in very hot, hot, normal and mild taste products were 101.98, 67.63, 37.74, and 14.73, respectively. Based on this result, the classification of hot taste by contents of capsaicin was presented in the 7 grades. Namely, the products currently sold in the market were classified into very hot, hot, normal and mild taste. In this research, the degree of hot taste was classified based on contents of capsaicin into 1st grade over 120 mg%, 2nd grade in 100-120 mg%, 3rd grade in 80-100 mg%, 4th grade in 60-80 mg%, 5th grade in 40-60 mg%, 6th grade in 20-40 mg% and 7th grade below 20 mg%. Thus, it is expected that the problem which arises when preparing the products such as kimchi, gochujang and seasoning sauces by using powdered red pepper, namely, the inconsistency of hot taste can be improved and maintained.

• Journal of Life Science
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• v.28 no.12
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• pp.1523-1528
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• 2018

This study investigated the chemical composition of four Korean cultivated Chrysanthemum indicum L. (Gamguk 1 ho, Gamguk 2 ho, Gamguk 3 ho, and Wonhyang) which are used in the food and fragrance industries to identify their volatile flavor compounds. These compounds were analyzed using headspace GC-MS from plant samples cultivated in the same region of Korea (Sancheong-gun, Gyeongsangnam-do). A total of 23 compounds were identified, eight of which were common across the four cultivars. The major flavor components in the three Gamguk plants were identified as 3-carene, camphene, ${\beta}$-phellandrene, eucalyptol and (+)-camphor. Eleven compounds, including (+)-camphor at 31.40%, were identified in Gamguk 1 ho. Gamguk 2 ho was found to contain 12 flavor compounds, predominant of which was camphene at 25.60%. Thirteen compounds including (+)-camphor (26.88%) were identified in Gamguk 3 ho, while 17 were detected in the Wonhyang cultivar, including trans-piperitol (47.33%), sabinene, and ${\gamma}$-terpinyl acetate. These results indicate differences in the type and ratio of functional volatile flavor ingredients in Chrysanthemum indicum L. cultivars which is highly valuable as material for fragrance product development.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.507-516
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• 2018

The closed chamber method, which is one of the most commonly used method for measuring greenhouse gases produced in rice paddy fields, has limitations in measuring dynamic $CH_4$ flux with spatio-temporal constrains. In order to deal with the limitation of the closed chamber method, some studies based on open-path of eddy covariance method have been actively conducted recently. The aim of this study was to compare the $CH_4$ fluxes measured by open-path and closed chamber method in the paddy rice fields. The open-path, one of the gas ($CO_2$, $CH_4$ etc.) analysis methods, is technology where a laser beam is emitted from the source passes through the open cell, reflecting multiple times from the two mirrors, and then detecting. The $CH_4$ emission patterns by these two methods during rice cultivation season were similar, but the total $CH_4$ emission measured by open-path method were 31% less than of the amount measured by closed chamber. The reason for the difference in $CH_4$ emission was due to overestimation by closed chamber and underestimation by open-path. The closed chamber method can overestimate $CH_4$ emissions due to environmental changes caused by high temperature and light interruption by acrylic partition in chamber. On the other hand, the open-path method for eddy covariance can underestimate its emission because it assumes density fluctuations and horizontal homogeneous terrain negligible However, comparing $CH_4$ fluxes at the same sampling time (AM 10:30-11:00, 30-min fluxes) showed good agreements ($r^2=0.9064$). The open-path measurement technique is expected to be a good way to compensate for the disadvantage of the closed chamber method because it can monitor dynamic $CH_4$ fluctuation even if data loss is taken into account.