• Korean Journal of Environment and Ecology
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• v.15 no.3
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• pp.237-246
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• 2001

To investigate the forest structure and to suggest the basic data of forest in the Dongwol Valley, the Gyeryongsan National Park, forty one plots were set up and surveyed. According to the analysis of classification by TWINSPAN, the community was divided by seven groups of Carpinus taxinora(I), Styrax japonica(II), Pinus densiflora A type(III), Quercus acutissima(IV), P. densinora-Q. valiabilis(V), p. densinora B type(Ⅵ) and Q. mongolica community(Ⅶ). The structure of communities were investigated using importance value. The survey results were summarized as follows: 1) the results of annual ring analysis revealed that the age of forest in the Dongwol Valley was about 30~50 years old,2) number of the average species was 15.6$\pm$4.7 and number of average individual was 124.9$\pm$36.4 per a plot(100$\textrm{cm}^2$). From the above results, it was anticipated that C. laxiflora will be climax species instead of Q. spp. and P. densinora.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.343-346
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• 1999

We have investigated the dielectric and electrical characteristics of palrnitic acid(PA), stearic acid(SA) and arachidic acid(AA) Langmuir-Blodgett(LB) films because these fatty acid systems have a same hydrophilic group and a different hydrophobic one(alky1 chain lqngth). The dielectric characteristics such as the capacitance-frequency(C-F) characteristics and the dielectric dispersion and absorption characteristics of PA, SA and AA through-plane were measured. In the result, the relative dielectric constants of PA, SA and AA LB films were about 3.0-4.6, 2.7-4.1 and 2.4-3.8, respectively. The relative dielectric constants were decreased in proportion to the chain length of alkyl group. Also, the dielectric dispersion and absorption of each fatty acid LB films have arisen from the dipole polarization in the range of $10^4~10^5[Hz]. And, the conductivity of PA, SA and AA LB films obtained from I-V characteristics were about $9{\times}10^{-14}, 3{\times}10^{-l4} and 5{\times}10^{-15}[S/cm], respectively. These results have shown the insulating materials and could control the conductivity by changing the length of alkyl group. Also, we have confirmed that the barrier height of fatty acid systems were about 1.32-1.40[eV] and the dielectric constant were about 3.0-4.2. These values were almost the same ones obtained from dielectric characteristics.

• Nuclear Engineering and Technology
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• v.50 no.3
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• pp.432-438
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• 2018

The occurrence of saturation in the CR-39 detector reduces and limits its detection dynamic range; nevertheless, this range could be extended using spectroscopic techniques and by measuring the net bulk rate of the saturated CR-39 detector surface. CR-39 detectors were irradiated by 1.5 MeV high alpha-particle fluence varying from $0.06{\times}10^8$ to $7.36{\times}10^8\;alphas/cm^2$ from Am-241 source; thereafter, they were etched in a 6.25N NaOH solution at a temperature of $70^{\circ}C$ for different durations. Net bulk etch rate measurement of the 1.5 MeV alpha-irradiated CR-39 detector surface revealed that rate increases with increasing etching time and reaches its maximum value at the end of the alpha-particle range. It is also correlated with the alpha-particle fluence. The measurements of UV-Visible (UV-Vis) absorbance at 500 and 600 nm reveal that the absorbance is linearly correlated with the fluence of alpha particles at the etching times of 2 and 4 hour. For extended etching times of 6, 10, and 14.5 hour, the absorbance is saturated for fluence values of $4.05{\times}10^8$, $5.30{\times}10^8$, and $7.36{\times}10^8\;alphas/cm^2$. These new methods pave the way to extend the dynamic range of polymer-based solid state nuclear track detectors (SSNTDs) in measurement of high fluence of heavy ions as well as in radiation dosimetry.

• Journal of the Korean Vacuum Society
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• v.18 no.4
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• pp.259-265
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• 2009

We fabricated the field effect transistor using single crystalline ZnO nanowires synthesized by a conventional thermal evaporation method and investigated their basic properties under the various conditions such as ultraviolet irradiation, reducing gas and electrolyte. The typical carrier concentration and mobility of the single crystalline ZnO nanowire with a diameter of 100 nm and length of 5 um were $1.30{\times}10^{18}cm^{-3}$ and $15.6cm^2V^{-1}s^{-1}$, respectively. The current of ZnO nanowire under ultraviolet irradiation significantly increased about 400 times higher as compared to in the darkness. In addition, the ZnO nanowire showed typical sensing characteristics for $H_2$ and CO due to well-known surface reactions and typical current-voltage characteristics under the 0.1 M NaCl electrolyte.

• Wind and Structures
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• v.32 no.2
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• pp.127-142
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• 2021

Wind load acting on a standalone structure is different from that acting on a similar structure which is surrounded by other structures in close proximity. The presence of other structures in the surrounding can change the wind flow regime around the principal structure and thus causing variation in wind loads compared to a standalone case. This variation on wind loads termed as interference effect depends on several factors like terrain category, geometry of the structure, orientation, wind incident angle, interfering distances etc., In the present study, a three building configuration is considered and the mean pressure coefficients on each face of principle building are determined in presence of two interfering buildings. Generally, wind loads on interfering buildings are determined from wind tunnel experiments. Computational fluid dynamic studies are being increasingly used to determine the wind loads recently. Whereas, wind tunnel tests are very expensive, the CFD simulation requires high computational cost and time. In this scenario, Artificial Neural Network (ANN) technique and Support Vector Regression (SVR) can be explored as alternative tools to study wind loads on structures. The present study uses these data-driven approaches to predict mean pressure coefficients on each face of principle building. Three typical arrangements of three building configuration viz. L shape, V shape and mirror of L shape arrangement are considered with varying interfering distances and wind incidence angles. Mean pressure coefficients (Cp mean) are predicted for 45 degrees wind incidence angle through ANN and SVR. Further, the critical faces of principal building, critical interfering distances and building arrangement which are more prone to wind loads are identified through this study. Among three types of building arrangements considered, a maximum of 3.9 times reduction in Cp mean values are noticed under Case B (V shape) building arrangement with 2.5B interfering distance. Effect of interfering distance and building arrangement on suction pressure on building faces has also been studied. Accordingly, Case C (mirror of L shape) building arrangement at a wind angle of 45º shows less suction pressure. Through this study, it was also observed that the increase of interfering distance may increase the suction pressure for all the cases of building configurations considered.

• Korean Journal of Metals and Materials
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• v.47 no.4
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• pp.209-216
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• 2009

It was evaluated that the microstructural and mechanical properties of Ta-bearing 9Cr-0.5Mo-2W ferritic/martensitic experimental steels. All the experimental steels showed the tempered martensitic microstructures, and $M_{23}C_6$ carbides, whose sizes were ranged from 200 to 300 nm, were easily observed at both boundaries of the prior austenite grain and the martensite lath. In addition, a relatively large Nb-rich MX carbonitrides were intermittently detected at the prior austenite grain boundaries, whereas a lot of Vrich MX carbonitrides, whose mean diameter was less than 50 nm, were observed randomly at both boundaries. Ta was mainly incorporated into the V-rich MX carbonitrides rather than the Nb-rich ones and their content was spanned from 5 to 20 at.%. Ta contents within the MX precipitates also increased as the content of Ta increased. Because the Ta addition into the steels would be attributed to the precipitation strengthening, solid solution strengthening and lath width reduction, it was shown that the mechanical properties, including hardness, tensile strength and creep rate of the 9%Cr-0.5Mo-2W steels were improved by the increase of Ta content. Especially, 9Cr-0.5Mo-2W-0.3V-0.05Nb-0.14Ta steel was revealed to be relatively excellent in the application for the SFR fuel cladding.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.116-128
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• 2022

Purpose: The paper aims to: 1) identify the reasons for the low usage of recycled paper in domestic workplaces and the premature state of recycled paper industry; 2) assess the environmental effects of replacing domestically consumed copy papers with recycled papers; and 3) suggest ways in which the recycled paper industry can expand in South Korea. Method: Questionnaire survey with cluster sampling is used to identify the attitudes and behavior with respect to recycled copy paper, the results of which are analyzed using SPSS. The environmental effect of replacing copy papers with recycled paper is assessed through the Life Cycle Assessment approach and Paper Calculator V4.0. Result: While the respondent's experience in using recycled copy paper was relatively low, they tend to acknowledge the need for its use and show relatively high satisfaction with the quality of the recycled paper. The environmental benefits of replacing ordinary copy paper with 40%+ recycled paper under the 10% market share increase scenario amounts to 60,000 tons of CO₂ emissions reductions. Conclusion: The results from the attitude survey and market research, five approaches to improving the recycled copy paper market are suggested.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.355-366
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• 2022

This paper proposes a microcode-based neural network accelerator controller for artificial intelligence accelerators that can be reconstructed using a programmable architecture and provide the advantages of low-power and ultra-small chip size. In order for the target accelerator to support various neural network models, the neural network model can be converted into microcode through microcode compiler and mounted on accelerator to control the operators of the accelerator such as datapath and memory access. While the proposed controller and accelerator can run various CNN models, in this paper, we tested them using the YOLOv2-Tiny CNN model. Using a system clock of 200 MHz, the Controller and accelerator achieved an inference time of 137.9 ms/image for VOC 2012 dataset to detect object, 99.5ms/image for mask detection dataset to detect wearing mask. When implementing an accelerator equipped with the proposed controller as a silicon chip, the gate count is 618,388, which corresponds to 65.5% reduction in chip area compared with an accelerator employing a CPU-based controller (RISC-V).

• Food Science of Animal Resources
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• v.43 no.5
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• pp.792-804
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• 2023

Non-aureus staphylococci (NAS), particularly antimicrobial-resistant NAS, have a substantial impact on human and animal health. In the current study, we investigated (1) the species profiles of NAS isolates collected from healthy broilers, farm environments, and farm workers in Korea, (2) the occurrence of antimicrobial-resistant NAS isolates, especially methicillin resistance, and (3) the genetic factors involved in the methicillin and fluoroquinolone resistance. In total, 216 NAS isolates of 16 different species were collected from healthy broilers (n=178), broiler farm environments (n=18), and farm workers (n=20) of 20 different broiler farms. The two most dominant broiler-associated NAS species were Staphylococcus agnetis (23.6%) and Staphylococcus xylosus (22.9%). Six NAS isolates were mecA-positive carrying staphylococcal cassette chromosome mec (SCCmec) II (n=1), SCCmec IV (n=1), SCCmec V (n=2), or nontypeable SCCmec element (n=2). While two mecA-positive Staphylococcus epidermidis isolates from farm workers had SCCmec II and IV, a mecA-positive S. epidermidis isolate from broiler and a Staphylococcus haemolyticus isolate farm environment carried SCCmec V. The occurrence of multidrug resistance was observed in 48.1% (104/216 isolates) of NAS isolates with high resistance rates to β-lactams (>40%) and fusidic acid (59.7%). Fluoroquinolone resistance was confirmed in 59 NAS isolates (27.3%), and diverse mutations in the quinolone resistance determining regions of gyrA, gyrB, parC, and parE were identified. These findings suggest that NAS in broiler farms may have a potential role in the acquisition, amplification, and transmission of antimicrobial resistance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.4
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• pp.419-427
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• 1985

The properties of lipids in cap and stalk of 'Koshin' (Shiitake, Lentinus edodes, withxpanded cap) were studied. It was also carried out that the characteristics of lipids in fresh 'Donko'(unexpanded cap) and the changes of lipids in those samples by various drying process. The total lipid (TL) content in the cap and stalk of 'Koshin' were 4.58% and 2.65% respectively. It was found that the contents of neutral lipids (NL, $46.7{\sim}48.8%$) and phospholipids (PL, $42.0{\sim}43.8%$) were high, while that of glycolipids(GL, $9.2{\sim}9.5%$) was low. The main lipid in NL was triacylglycerol (TG, $58.0{\sim}58.5%$) followed by sterolester (SE, $16.9{\sim}17.4%$), sterol (ST, $15.6{\sim}16.4%$), diacylglycerol (DG, $5.8{\sim}6.0%$) and monoacylglcerol (MG, $1.1{\sim}1.3%$). The main lipids in PL was phosphatidyl ethanolamine (PE, $58.3{\sim}6.02%$) followed by phosphatidyl choline (PC, $17.3{\sim}19.5%$), cardiolipin (CA, $12.8{\sim}14.0%$) and lyso-phophatidyl choline (LPD, $4.8{\sim}6.6%$). Fatty acid composition was significantly different among TL, NL, GL and PL contained in cap and stalk. The main fatty acids was $C_{18:2}$ followed by $C_{16:0}$ and $C_{18:1}$ acids. The TL contents in cap and stalk of fresh 'Donko' were 3.7% and 2.5%. The changes of TL contents, PoV by drying were not almost observed. AV(acid value) of TL in the sun dried samples was a little lower than those of the fresh and hot air dried samples, on the contrary NL content in TL of the former was a little higher than those of the latters. The main lipid in NL of the three samples was TG followed by SE, ST, DG, MG and free fatty acid (FFA). In the above lipids, FFA contents in NL of the sun dried sample was a little higher than those of the fresh and hot air dried samples, but TG content in NL of former was a little lower than those of the latters. The main lipid in GL of the three samples was digalactosydiglycerol (DGDG) followed by acylsterylglucoside(ASG), sterylglucoside (SG), monogalactosyldiglycerol (MGD) and cerebroside (CER). Influence of drying on these lipid content were nol almost recognized. The main lipid in PL of the three samples was PE followed by PC, CA, LPC and phosphat idyl serine (PS). In the above lipids, PE and PC contents in PL of the sun dried one were a little lower than those of the fresh and hot air dried ones. The main fatty acid in TL, NL, GL and PL of the three samples was $C_{18:2}$ followed by $C_{16:0},\;C_{18:1}$. The $C_{18:2}$ acid contents of the sun dried sample was a little lower than those of the fresh and hot air dried ones, while $C_{16:0}$ content of the former was a little higher than those of the former was a little lower than those of the latters.