• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.162-162
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• 2010

InSb has received great attentions as a promising candidate for the active layer of infrared photodetectors due to the well matched band gap for the detection of $3{\sim}5\;{\mu}m$ infrared (IR) wavelength and high electron mobility (106 cm2/Vs at 77 K). In the fabrication of InSb photodetectors, passivation step to suppress dark currents is the key process and intensive studies were conducted to deposit the high quality passivation layers on InSb. Silicon dioxide (SiO2), silicon nitride (Si3N4) and anodic oxide have been investigated as passivation layers and SiO2 is generally used in recent InSb detector fabrication technology due to its better interface properties than other candidates. However, even in SiO2, indium oxide and antimony oxide formation at SiO2/InSb interface has been a critical problem and these oxides prevent the further improvement of interface properties. Also, the mechanisms for the formation of interface phases are still not fully understood. In this study, we report the quantitative analysis of indium and antimony oxide formation at SiO2/InSb interface during plasma enhanced chemical vapor deposition at various growth temperatures and subsequent heat treatments. 30 nm-thick SiO2 layers were deposited on InSb at 120, 160, 200, 240 and $300^{\circ}C$, and analyzed by X-ray photoelectron spectroscopy (XPS). With increasing deposition temperature, contents of indium and antimony oxides were also increased due to the enhanced diffusion. In addition, the sample deposited at $120^{\circ}C$ was annealed at $300^{\circ}C$ for 10 and 30 min and the contents of interfacial oxides were analyzed. Compared to as-grown samples, annealed sample showed lower contents of antimony oxide. This result implies that reduction process of antimony oxide to elemental antimony occurred at the interface more actively than as-grown samples.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.130-137
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• 2008

$La_{0.7}Sr_{0.3}MnO_3$ films were deposited on $SiO_2$/Si and Si substrates annealed at $350^{\circ}C$ by rf magnetron sputtering. The oxygen gas flow rates were varied as 0, 40, and 80 sccm. Without post annealing process, $La_{0.7}Sr_{0.3}MnO_3$ thin films on $SiO_2$/Si and Si substrates were polycrystalline with (100), (110), and (200) growth planes. The grain size of $La_{0.7}Sr_{0.3}MnO_3$ thin films was increased with increasing oxygen gas flow rate. The sheet resistance of $La_{0.7}Sr_{0.3}MnO_3$ thin films was decreased with oxygen flow rate due to the increased grain size which induced a reduction of grain boundary. TCR (temperature coefficient of resistance) values of $La_{0.7}Sr_{0.3}MnO_3$ thin films were obtained from -2.0% to -2.2%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.655-662
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• 2000

Electron beam (EB) irradiation was applied to study microbial decontamination effects for kochujang powder by determining their microbiological and physicochemical qualities over gamma ray (GR) irradiation. The samples showed a high microbial population, such as 105~106 CFU/g of total aerobic bacteria, negative of yeasts & molds and coliforms. Total bacterial counts were decreased by 1~2 log cycles with EB irradiation at 5~7.5 kGy, and 10 kGy irradiation was enough to improve the microbiological quality by reducing populations to below 104CFU/g, which was similar to gamma energy. Such doses were effective for controlling the microbial growth in stored samples during storage for 4 months at room temperature. Decimal reduction doses (D10 value) on initial bacterial populations were 2.88~3.02 kGy in EB and 3.57~3.59 kGy in GR, which were influenced by initial populations and energy types applied. Based upon the above results, 7.5~10 kGy irradiation caused negligible changes in Hunter's color, capsaicin, fatty acid composition and organoleptic qualities. Considering the quality changes resulting from subsequent storage, such as a decrease in capsanthin content and an increase in TBA value in the samples, it is recommendable to irradiate kochujang powder at 7.5~10 kGy when used for food processing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.7
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• pp.915-920
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• 2007

Rice flour milled from spray-washed rice was stored at $5^{\circ}C$, $20^{\circ}C$, and $35^{\circ}C$ for 4 months and changes in flour properties during the storage were investigated. Moisture content of rice flour tended to decrease during the storage, and the reduction in the moisture content was higher at higher storage temperature. Compared to dry-milled rice flour, lightness of the rice flour milled from spray-washed rice was slightly higher and tended to increase slightly during the storage. Rapid Visco-Aanlyzer (RVA) peak viscosity of rice flour milled from spray-washed rice was higher throughout the storage period, compared to dry-milled rice flour. The RVA peak viscosity was lower in the order of rice flour stored at $5^{\circ}C$, $20^{\circ}C$, and $35^{\circ}C$. Little changes in setback viscosity were observed in rice flour stored at $5^{\circ}C$ and $20^{\circ}C$, while an increase in the setback viscosity was found in rice flour stored at $35^{\circ}C$. Total bacteria count was consistently lower in the rice flour milled from spray-washed rice, suggesting that spray-washing prior to milling could lower microbial growth of rice flour during storage.

• Journal of the Korean Geographical Society
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• v.51 no.2
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• pp.201-217
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• 2016

We accessed the climate change effects on the distributions of warm-evergreen broad-leaved trees (shorten to warm-evergreens below) in the Korean Peninsula (KP). For this, we first selected nine warm-evergreens with the northern distribution limits at mid-coastal areas of KP and climate variables, coldest month mean temperature and coldest quarter precipitation, known to be important for warm-evergreens growth and survival. Next, species distribution models (SDMs) were constructed with generalized additive model (GAM) algorithm for each warm-evergreen. SDMs projected the potential geographical distributions of warm evergreens under current and future climate conditions in associations with land uses. The nine species were categorized into three groups (mid-coastal, southwest-coastal, and southeast-inland) based on their current spatial patterns. The effects of climate change and land uses on the distributions depend on the current spatial patterns. As considering land uses, the potential current habitats of all warm-evergreens decrease over 60%, showing the highest reduction rate for the Kyungsang-inland group. SDMs forecasted the expansion of potential habitats for all warm-evergreens under climate changes projected for 2050 and 2070. However, the expansion patterns were different among three groups. The spatial patterns of projected coldest quarter precipitation in 2050 and 2070 could account for such differences.

• Journal of Conservation Science
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• v.38 no.3
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• pp.217-233
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• 2022

The remains found in Geumcheok-ri, Gyeongju are located in close proximity to the Ancient Tombs in Geumcheok-ri, Gyeongju (Historic Site) which were built between the late 5th and early 6th centuries, and these tombs are known to belong to the powerful rulers of that area. Using metallurgical techniques, this study was conducted on the iron objects obtained from the excavated remains in Geumcheok-ri, Gyeongju which are presumed to have a close relation to the nearby ruins that played an important role in the growth of Silla. To identify differences in manufacturing techniques based on the purpose of the iron objects, eight objects were selected after classifying them by use and the microstructure and non-metallic inclusions were investigated. The analyses results confirmed that the manufacturing process involved forging iron with a high or low carbon content to produce a particular shape, and that the carburization process was applied to iron post forging a shape to increase its strength when necessary. The mechanical properties were improved by selectively applying the steelmaking method and the heat treatment technique considering the functions of the parts, and the low temperature reduction was applied to the smelting process. Furthermore, in comparison with the iron objects excavated from the remains located in the center of Gyeongju and its outskirts, it is confirmed that there is similarity in the smelting and manufacturing techniques between these objects.

• Sleep Medicine and Psychophysiology
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• v.4 no.1
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• pp.57-65
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• 1997

As jet lag of modern travel continues to spread, there has been an exponential growth in popular explanations of jet lag and recommendations for curing it. Some of this attention are misdirected, and many of those suggested solutions are misinformed. The author reviewed the basic science of jet lag and its practical outcome. The jet lag symptoms stemed from several factors, including high-altitude flying, lag effect, and sleep loss before departure and on the aircraft, especially during night flight. Jet lag has three major components; including external de synchronization, internal desynchronization, and sleep loss. Although external de synchronization is the major culprit, it is not at all uncommon for travelers to experience difficulty falling asleep or remaining asleep because of gastrointestinal distress, uncooperative bladders, or nagging headaches. Such unwanted intrusions most likely to reflect the general influence of internal desynchronization. From the free-running subjects, the data has revealed that sleep tendency, sleepiness, the spontaneous duration of sleep, and REM sleep propensity, each varied markedly with the endogenous circadian phase of the temperature cycle, despite the facts that the average period of the sleep-wake cycle is different from that of the temperature cycle under these conditions. However, whereas the first ocurrence of slow wave sleep is usually associated with a fall in temperature, the amount of SWS is determined primarily by the length of prior wakefulness and not by circadian phase. Another factor to be considered for flight in either direction is the amount of prior sleep loss or time awake. An increase in sleep loss or time awake would be expected to reduce initial sleep latency and enhance the amount of SWS. By combining what we now know about the circadian characteristics of sleep and homeostatic process, many of the diverse findings about sleep after transmeridian flight can be explained. The severity of jet lag is directly related to two major variables that determine the reaction of the circadian system to any transmeridian flight, eg., the direction of flight, and the number of time zones crossed. Remaining factor is individual differences in resynchmization. After a long flight, the circadian timing system and homeostatic process can combine with each other to produce a considerable reduction in well-being. The author suggested that by being exposed to local zeit-gebers and by being awake sufficient to get sleep until the night, sleep improves rapidly with resynchronization following time zone change.

• Journal of Mushroom
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• v.19 no.3
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• pp.210-215
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• 2021

For sterilization of microorganisms of the Listeria genus contaminating enoki mushroom, pilot mushroom grower equipped with air sterilization devices were developed. Sterilization experiments were performed using physical and chemical treatments. Internal temperature and humidity were controlled, maintaining 6.62℃±0.30 in the upper shelves, 6.46℃±0.24 in the middle shelves, and 6.48℃±0.25 in the lower shelves. Humidities were 79.97%±4.42, 79.43%±4.06, and 79.94±4.30%, respectively, with a temperature setting of 6.5℃, and a relative humidity of 75%. A suitable enoki mushroom cultivation stage for air sterilizer application was during the growth stage, with temperature in the 6.5~8.5℃ range, and humidity of 70~80%. At these same internal conditions, the ozone concentration in the mushroom cultivator was found to be 160 ppb during ion-cluster generator operation. After physical sterilization, the Listeria innocua survival rate was 0.1 to 0.9% using ion cluster sterilization, and 9.3 to 10.6% using UV air sterilization. The Listeria innocua survival rates on different materials were 9.3~10.6% on the metal specimen, and 9.9~16.2% on the plastic wrapper. The survival rate was particularly high on the rough side of the plastic wrapper. Ion cluster air sterilization is a labor-saving and effective method for suppressing the occurrence of Listeria bacteria on mushroom growers walls and shelves. For the plastic wrapper, chemical sterilization is more effective than physical sterilization.

• Korean Journal of Environment and Ecology
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• v.34 no.5
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• pp.358-371
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• 2020

As climate change is expected to lead to a severe reduction of biodiversity, studies to investigate the reasons for habitat loss, growth decline, and death of Korean fir (Abies koreana Wilson), endangered alpine/subalpine species in Korea, have been conducted for years but found no clear answer yet. This study reviewed previous studies on Korean fir published in the journals in the past 40 years, 1980 through 2020, into 10-year units, examined the study trend by period, region, and subject with a focus on ecological studies, and analyzed the study results. The ecological studies were categorized into evolutionary ecology, physiological ecology, population ecology, and landscape ecology. Based on the results, we suggested the required research fields in the future. We found a total of 73 papers published in the past 40 years and 48 (65.8%) of them published in the past 10 years. In terms of region, Mt. Halla accounted for the most as 41 papers were on it. In terms of ecological subjects, the physiological ecology accounted for the most with 38, and the evolutionary ecology accounted for the least with 10. The review of the study results showed that many studies identified water stress caused by the water resource imbalance due to temperature increase and spring precipitation reduction following climate change as the main reason for the decline and habitat loss of Korean fir. However, recent studies suggested other factors, such as soil environment, disturbing organisms, and climatic events. The cause of the decline and death of the Korean fir not yet being clearly identified is that most of the studies dealt with the basic content, were carried out intermittently, and were concentrated in some regions. Therefore, we need long-term studies with advanced technology in each study subject at a local scale to find the cause of Korean fir decline and present sustainable management and conservation. Moreover, it is necessary to extend our study subjects to ecosystem ecology and systems ecology to integrate the results from various study subjects for a comprehensive understanding of the reason for Korean fir declines. The results of comprehensive studies could provide clearer answers for Korean fir's declines and the alternatives of conservation management and practices.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.2
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• pp.129-142
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• 1976

Optimum doses The optimum dose that may be defined as the dose below the maximum permissible dose, yet would bring about a significant storage life extension at refrigerated temperatures, varied with species of fish as well as with the postirradiation storage temperatures. Thus the dose of 0. 1 Mrad was considered to be optimum for the croaker and yellow corvenia at $0^{\circ}C$, while at $5^{\circ}C$ the dose of 0.2 Mrad would be suitable for both species. The roundnose flounder was more radiosensitive and even at the dose of 0.1 Mrad a slight irradiation odor was detected immediately after the radiation treatment. Such degree of irradiation odor disappeared upon storage, therefore, the dose of 0.1 Mrad was considered to be optimum for the roundnose flounder at both $0^{\circ}\;and\;5^{\circ}C$. Storage life extension The croaker meats irradiated at 0.1 Mrad could be held at $0^{\circ}C$ as long as 5 weeks in good acceptable conditions, while the unirradiated control became unacceptable within 2 weeks-3-4 for extension of storage life at $0^{\circ}C$. At the storage temperature of $5^{\circ}C$, the storage life of 0.2 Mrad irradiated samples was extended from less than one week to 4 weeks--4-5 fold extension. The storage life extension of 0.1 Mrad irradiated yellow corvenia at $0^{\circ}C$ was from less than 2 weeks for the unirradiated to 4 weeks-approximately a-s folds and that of 0.2 Mrad irradiated samples stored at $5^{\circ}C$ was from 5 days to 3 weeks 4-5 folds. The roundnose flounder meats irradiated at 0.1 Mrad could held at $0^{\circ}C$ for 3-4 weeks as compared to less than 1 week for the unirradiated and at $5^{\circ}C$ the storage life could be extended from less than 3 days to up to 3 weeks. Thus the storage life extension by 4-5 folds and by 6-7 folds was possible at $0^{\circ}C\;and\;5^{\circ}C$ storage, respectively. Postirradiation storage microbiology and biochemistry In general 10 fold reduction of initial microflora was realized as a result of irradiating fish samples at 0.1 Mrad. The extent of microflora reduction increased with increasing doses applied, but not proportionately dependent. The microbial growth in the irradiated was severely retarded during the subsequent storage period, lagging far behind that of the irradiated control samples except in the late storage phase, when the levels of microflora of the irradiated either approached to or rose above the levels of the unirradiated. The microbiological changes caused by irradiation was reflected in the pronounced suppression of TVB and TMA accumulation during the storage period. This suggests that irradiation treatment brought about both quantitative and qualitative changes in microflora initially present and it is reasonable to suggest that the microflora removed by irradiation in fact represent most of the flora capable of producing TVB and TMA in normal fish spoilage process.